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1
Bernhard, Oliver Karl. "Proteomic Investigation of the HIV Receptors CD4 and DC-Sign/CD209." University of Sydney. Medicine, 2004. http://hdl.handle.net/2123/585.
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HIV infection and disease is a multistage process that involves a variety of cell types as the virus spreads through the body. Initially, dendritic cells (DCs) present at the mucosal site of infection bind and internalise HIV for degradation and presentation to T cells. As the DCs migrate to lymph nodes and mature, part of the internalised virions remains infective inside endosomal compartments. During formation of the immunological synapse between CD4 T cells and DCs, infective virions from dendritic cells are transferred to CD4 T cells leading to a strong infection of those cells allowing rapid virus dissemination throughout the body and establishment of the typical HIV infection. Various membrane receptors are involved in this process. Initial HIV binding to DCs is mediated by C-type lectin receptors such as the mannose receptor or DC-SIGN (DC specific intracellular adhesion molecule 3 grabbing non integrin) which is followed by virus internalisation and lysis albeit virus induced changes in endocytic routing prevents a proportion from degradation. Productive infection of DCs has also been observed allowing trans infection of CD4 T cells through a different mechanism. HIV infection of CD4 T cells, DCs and other cells is a multistep process initiated by binding of HIV envelope gp120 to the CD4 receptor, a 55 kDa transmembrane glycoprotein. Subsequent conformational changes in gp120 allow binding to a chemokine receptor, either CCR5 or CXCR4, followed by membrane fusion and infection. The aim of this thesis was to investigate protein associations with the HIV receptors DC-SIGN and CD4 in order to elucidate the mechanism of complex formation, virus entry and/or defining target sites for antiretroviral drugs. This thesis used a proteomic approach for studying the receptors with mass spectrometry-based protein identification as its core technology. A range of different approaches were developed and compared for identification of protein interactions and characterisation of the identified protein associations. An affinity purification of the CD4 receptor complex from lymphoid cells was used as the basis for detecting novel CD4-binding proteins. For this approach a strategy based on mass spectrometry identification of CD4 associating proteins using affinity chromatography and affinity-tag mediated purification of tryptic peptides was developed. This method proved successful for the identification of CD4 interacting proteins such as the strongly associated kinase p56lck, however a limited number of non-specifically bound proteins were also identified along the receptor complex. Using one-dimensional SDS-polyacrylamide gel electrophoresis followed by in-gel digests and mass spectrometry analysis, a large number of non-specifically binding proteins were identified along the CD4/lck complex. Evaluation of different lysis buffers in several independent experiments demonstrated that there was a large and inconsistent array of proteins that were obviously non-specifically bound to the receptor. No further specific binding partners were detected. These data suggested that protein interactions of CD4 on this cell type are of weak and/or transient nature. It also demonstrated a need for careful interpretation of proteomic data in the light of the propensity of non-specific binding under these conditions. To overcome dissociation of weak protein interactions, a method was developed using chemical cross-linking to preserve weak protein interactions on lymphoid cells. Affinity purification was used to purify CD4 along with cross-linked associated proteins and mass spectrometry analysis identified an interaction with the transferrin receptor CD71 and the tyrosine phosphatase CD45. The CD45-CD4 interaction is well known. The CD4-CD71 interaction was demonstrated to be a result from colocalization of the two molecules during formation of endocytic vesicles. Flow cytometry-based fluorescence resonance energy transfer (FRET) measurements were applied to confirm colocalization. A similar interaction was suspected for CD4 and DC-SIGN on the plasma membrane of DCs as cis infection of DCs has been demonstrated i.e. initial binding to DC-SIGN then to CD4/CCR5 on the same cell. Therefore, protein associations of DC-SIGN were investigated using the developed techniques. Using cross-linking, DC-SIGN was shown to assemble in large complexes on the surface of immature monocyte-derived DCs. Mass spectrometry analysis of the purified complexes identified them as homo-oligomers of DC-SIGN. The absence of CD4 suggested that the fraction interacting with CD4 at any one time must be small. The complexes of DC-SIGN were further characterised to be tetramers and successfully co-immunoprecipitated with HIV gp120 and mannan. DC-SIGN monomers were not evident demonstrating that the assembly of DC-SIGN into tetramers is required for high affinity binding of its natural and viral ligands. Thus potential antiviral agents aimed at blocking the early stage of HIV binding to DCs must simulate tetramers in order to neutralise the virus efficiently. Overall the thesis provides new information on protein interactions of CD4 and DC-SIGN, a careful investigation of "proteomics" techniques for identifying the proteins in affinity-purified samples and demonstrates the need for multifaceted analytical approaches to probe complex cellular systems.
2
Sather, Blythe Duke. "CD4+ Foxp3+ regulatory T cell homing & homeostasis /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/8343.
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Jacobs, Caron Adrienne. "The nanoscale organisation of HIV cell surface receptors CD4 and CCR5." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10056281/.
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The plasma membrane serves as the cell’s front line for interactions with, and response to, the external environment. The molecular mechanisms and regulation of cellular responses to extracellular signals are determined by the spatial organisation and dynamics of the various components comprising the plasma membrane. CD4 and CCR5 are two key cell surface molecules with important roles in immune cell function and regulation. They are also co-opted as the primary receptor and a co-receptor, respectively, by HIV. Biochemical studies have provided a detailed understanding of the molecular mechanisms of these interactions. Until recently, however, the small scale and rapid dynamics of these interactions has meant that a detailed view of the topology of the cell membrane and the organisation of receptors first encountered by the virus has been beyond the resolving power of available tools. The increasing capabilities of the emerging and rapidly developing super-resolution microscopy technologies are now optimally poised for us to address some of these questions. In this work, I have applied single molecule localization microscopy to unveil some of the nanoscale organisational properties of the cell surface receptors CD4 and CCR5. I have worked on the development of small labelling probes for CD4 and addressed some of the key aspects of sample preparation and labelling that can artificially alter the distribution of membrane associated target molecules. Here I report the first quantitative characterisation of the nanoscale organisation of CD4 and CCR5 in lymphoid cell plasma membranes, as well as how this organisation changes under different conditions, such as in response to cell signal-mimicking stimulation, or exposure to HIV envelope. This approach to characterising membrane receptor organisation can be further applied to in-depth studies of early host cell-virus interactions, as well as to other cell surface receptors and their organisation in the context of key cellular functions.
4
Wong, Phillip. "Changing TCR recognition requirements at discrete stages of intrathymic CD4 T cell development /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8351.
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Sáez, Borderias Andrea. "Regulation of natural killer and cd4+T cell function by NKG2 C-type lectin-like receptors." Doctoral thesis, Universitat Pompeu Fabra, 2009. http://hdl.handle.net/10803/7133.
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This work is centered on the study of the NKG2 C-type lectin-like receptors on NK and CD4+T cells. We provide evidence supporting that CD4+T cells specific for Human Cytomegalovirus (HCMV) may express different NK cell receptors, and demonstrate that the C-type lectin-like receptor NKG2D is expressed on cytotoxic CD4+T cells with an effector/memory phenotype, enhancing their TCR-dependent proliferation and cytokine production. A second part of the work is centered on the study of the CD94/NKG2 receptors on NK cells. We show that NKG2A can be induced on NKG2C+ NK cells upon activation with rIL-12 or when cocultured with HCMV-infected dendritic cells, and that NKG2A expression inhibits the response of NKG2C+NK clones against HLA-E-expressing targets, providing a potential regulatory feedback mechanism to control cell activation. Altogether, our results support that expression of NKG2 C-type lectin like receptors may be shaped during the course of viral infections, providing mechanisms to finely regulate both NK and CD4+T cell functions.Aquesta tesi es centra en l'estudi dels receptors lectina de tipus C NKG2 en cèl·lules Natural Killer i T CD4+. Demostrem que les cèl·lules T CD4+ específiques pel Cytomegalovirus Humà poden expressar diferents receptors NK, i que el receptor lectina tipus C NKG2D s'expressa en cèl·lules citotòxiques i de memòria, potenciant la proliferació i secreció de citocines depenent del TCR. La segona part d'aquesta tesi es centra en l'estudi de l'expressió dels receptors CD94/NKG2 en cèl·lules NK. Mostrem com l'expressió de CD94/NKG2A s'indueix en cèl·lules CD94/NKG2C+ estimulades amb IL-12 o cultivades amb cèl·lules dendrítiques infectades pel Cytomegalovirus Humà, i que l'expressió de CD94/NKG2A inhibeix la resposta de clons NK CD94/NKG2C+ envers dianes HLA-E+, constituint un possible mecanisme de feedback negatiu per controlar l'activació cel·lular. En resum, els nostres resultats demostren que l'expressió dels receptors lectina tipus C NKG2 pot ser modificada durant les infeccions víriques consitutint un possible mecanisme per regular la resposta tant de cèl·lules NK com T CD4+.
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Bernhard, Oliver. "Proteomic investigation of the HIV receptors CD4 and DC-SIGN/CD209 membrane protein interactions." Saarbrücken VDM Verlag Dr. Müller, 2004. http://d-nb.info/989278026/04.
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Ritsou, Elena. "The role of CD4 and CXCR4 mediated apoptosis in T cell depletion during HIV-1 infection." Thesis, Open University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390903.
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Ghazi, Bouchra. "Réponses cellulaires associées au récepteur KIR3DL2, marqueur spécifique des lymphocytes T tumoraux du syndrome de Sézary." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST0068.
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Le syndrome de Sézary (SS) est un variant leucémique et érythrodermique de lymphomes T cutanés épidermotropes. Son diagnostic repose à la fois sur des critères cliniques, la présence de lymphocytes T à noyau atypique cérébriforme sur un frottis sanguin et la mise en évidence dans la peau, les ganglions et le sang d’un clone lymphocytaire T CD4+. Notre laboratoire a identifié KIR3DL2 comme premier marqueur membranaire spécifique des cellules tumorales de Sézary. KIR3DL2 peut ainsi être utilisé pour le diagnostic et le suivi des patients atteints du SS. Toutefois, aucune étude n’a démontré de lien entre sa structure de récepteur inhibiteur et sa fonction dans les lymphocytes tumoraux de Sézary, et plus particulièrement son implication possible dans les mécanismes régulant la prolifération et/ou la résistance à l’apoptose des cellules tumorales.Au cours de ce travail deux axes ont été développés :- Un premier axe visant à mieux comprendre la fonction de KIR3DL2 et les mécanismes de signalisation intracellulaire initiés lors de son engagement par l’anticorps AZ158 dans les lymphocytes T tumoraux de Sézary. Nos résultats mettent en évidence un rôle de corécepteur inhibiteur pour KIR3DL2 dans les cellules tumorales de Sézary. En effet, l’engagement de KIR3DL2 inhibe la prolifération et l’AICD induites par la stimulation CD3, cette inhibition étant corrélée à une modulation négative des signaux médiés par le TCR. Ainsi, KIR3DL2 ne se comporte pas comme une unité de signalisation indépendante dans les cellules tumorales de Sézary, contrairement à ce qui est observé dans les cellules NK.- Un second axe portant sur l’évaluation d’une nouvelle fonction de KIR3DL2 comme récepteur pour les ODN CpG. Ainsi, nous rapportons pour la première fois un effet direct de l’ODN CpG sur les cellules tumorales T CD4+ de Sézary. En effet, nous avons observé un effet apoptotique de l’ODN CpG-C caspases-dépendant sur les lignées et les cellules tumorales circulantes. De plus, le traitement des cellules tumorales de patients Sézary avec l’ODN CpG-C conduit à une inhibition de l’activation constitutive du facteur de transcription STAT3.La réalisation de cette étude a permis de mieux comprendre la fonction et les mécanismes initiés à partir de KIR3DL2 dans les cellules tumorales T CD4+ de Sézary. De plus, ce travail ouvre de nouvelles perspectives thérapeutiques basées sur le ciblage direct et spécifique des cellules tumorales de Sézary pouvant être associé à une stimulation des acteurs immuns grâce à l’action des ODN CpGSézary syndrome (SS) is an aggressive leukemic and erythrodermic variant of cutaneous T-cell lymphoma. It is characterized by the presence of a clonal CD4+ T lymphocyte population in the skin, lymph nodes and peripheral blood. Our laboratory has previously identified the NK cell receptor KIR3DL2 as a valuable diagnostic and prognostic marker for the detection of the tumoral T cell burden of Sézary syndrome patients. However, the function of this receptor on the malignant T lymphocyte population remained unexplored. The specific expression of KIR3DL2 by SS patients malignant cells prompted us to investigate its possible influence on mechanisms regulating the tumoral cells outgrowth and apoptosis process.To this aim, two axes were developed. The first axis aimed to highlight the function of KIR3DL2 on the malignant T lymphocyte population and to elucidate the intracellular signaling mechanisms initiated by engagement of the receptor with the monoclonal antibody AZ158. Our results show that KIR3DL2 can exert an inhibitory co-receptor function in malignant Sézary cells. Indeed, triggering of KIR3DL2 inhibits the CD3-mediated proliferation and cell death of the CD4+ KIR3DL2+ cells, this inhibition being correlated to a down-modulation of the TCR-mediated signals. Thus, KIR3DL2 does not behave as an independent signaling unit in Sézary cells, unlike NK cells.The second axis aimed to evaluate a new function of KIR3DL2 as CpG ODN receptor. We show for the first time a direct effect of CpG ODN on tumoral CD4+ T Sézary cells. Thus, we observed a caspase-dependent apoptotic effect of CpG ODN-C on Sézary cell lines and circulating malignant T cells. This process of cellular death is correlated to a dephosphorylation of the transcription factor STAT3, which is found constitutively phosphorylated and activated in Sézary cells.This study has provided new insights into the function and the intracellular signaling pathways initiated by KIR3DL2 in malignant Sézary T cells. Furthermore, this work opens new therapeutic perspectives based on the direct and specific targeting of tumor cells that could be associated to immune cell stimulation through the use of ODN CpG
9
Fickinger, Andira Michele da Cruz. "Papel dos receptores de glutamato tipo NMDA em macrófagos, células dendríticas e células T CD4 ativadas in vitro." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/42/42133/tde-11072014-091556/.
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A neuroimunologia é o ramo da imunologia que estuda a relação entre sistema imune e o sistema nervoso. Muitos estudos têm demonstrado a capacidade direta de neurotransmissores em modular a resposta imune, assim como de citocinas em influenciar funções cognitivas. Neste contexto, o glutamato possui papel de destaque, por se tratar do neurotransmissor excitatório mais importante e mais abundante no sistema nervoso central dos mamíferos. Sua função é exercida através de dois tipos de receptores principais: i) os receptores ionotrópicos (iGluR) e ii) os receptores metabotrópicos (mGluR). A descoberta da expressão de receptores de glutamato em células do sistema imune tem despertado interesse científico, levantando questões acerca de sua expressão e função. No presente trabalho, avaliamos parâmetros como viabilidade celular, linfoproliferação e ativação de MAP quinase pelo receptor NMDAR esplenócitos totais e linfócitos cultivados in vitro. Nossos resultados demonstram que linfócitos em repouso e ativados apresentam diferentes perfis de expressão do receptor NMDAR. O uso do antagonista deste receptor, o MK801, foi capaz de reduzir a proliferação de linfócitos T CD4 e T CD8 estimulados com anti-CD3 em cultura de esplenócitos. Tal redução pode ser explicada por um aumento na taxa de morte celular, o que foi avaliado através de marcação com anexina-V, indicador de apoptose, ou 7-AAD, indicador de necrose. Para entendermos um pouco a respeito da sinalização do receptor NMDAR no sistema imune, avaliamos a fosforilação da MAP quinase ERK 1,2 em linfócitos T CD4 ativados na presença do agonista (NMDA) ou do antagonista (MK801) do receptor. Observamos um aumento na ativação desta quinase na presença de NMDA, o que é revertido na presença do MK801. Ao avaliar o papel do receptor NMDAR in vivo, verificamos uma redução significativa na gravidade da encefalomielite experimental auto-imune em animais tratados com MK801. Mais interessante, esta redução se correlaciona também com uma redução na fosforilação de ERK 1,2 em esplenócitos totais obtidos ao dia 7 pós-imunização. Em resumo, nossos dados sugerem que o receptor NMDA possui o papel de ativador de vias intracelulares importantes, como as da MAP quinase ERK 1,2; e que o seu bloqueio resulta em morte celular in vitro. Logo, isso indica a importância do glutamato como modulador da intensidade da resposta e viabilidade de linfócitos T CD4 e T CD8 in vitro e in vivo. Sendo assim, nossos resultados contribuem para um melhor entendimento dos fenômenos de imunoregulação, especialmente aqueles no campo da neuroimunologia ou neuroimunomodulação.Neuroimmunology is a field within immunology which studies the relationship between the nervous system and the immune system. Several studies have demonstrated the direct ability of neurotransmitters in modulating the immune response, as for cytokines in influencing cognitive functions. In this context, glutamate stands out for being the most important and abundant neurotransmitter in the mammal central nervous system. Its role is exerted through two main types of receptor: i) ionotropic receptors (iGluR) and ii) metabotropic receptors (mGluR). The discovery of glutamate receptor expression in immune cells has led to scientific interest, raising issues concerning its expression and function. In the present study, we evaluated parameters such as cell viability, lymphoproliferation, and activation of the MAP quinase pathway by the NMDA receptor on total splenocytes and lymphocytes cultured in vitro. Our results demonstrate that naive and activated lymphocytes present different profiles of NMDA receptor expression. The use of MK801, an antagonist for this receptor, was able to reduce the T CD4 and T CD8 lymphocyte proliferation stimulated with anti-CD3 in splenocyte culture. Such reduction may be explained by the increase of the cellular death rate, evaluated by annexin-V staining, indicator of apoptosis or 7-AAD, indicator of necrosis. With the intent of understanding part of the NMDA receptor signaling in the immune system, we evaluated the ERK 1,2 MAP quinase phosphorylation in T CD4 lymphocytes activated in the presence of the agonist (NMDA) or the antagonist (MK801) of the receptor. We observed an increase in this quinase activation in the presence of NMDA, which is reversed by the MK801. When evaluating the role of the NMDA receptor in vivo, we verified a significant reduction in the degree of experimental auto-immune encephalomyelitis in animals treated with MK801. More interesting, this reduction also correlates to a reduction on the phosphorilation of ERK 1,2 in total splenocytes obtained at the seventh day post-immunization. In sum, our data suggest that the NMDA receptor has the role of activating important intracellular pathways, such as the MAP quinases ERK 1,2; and that its blockage results in cellular death in vitro. As so, this indicates the importance of glutamate as a modulator of the intensity of response and the viability of T CD4 e T CD8 lymphocytes in vitro e in vivo. Thus, our result contribute for a better understanding of the immunoregulation phenomena, especially those in the neuroimmunology ou neuroimmunomodulation field.
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Deftos, Michael Laing. "Notch signaling in T cell development /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8364.
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Barton, Gregory Methven. "Positive selection of CD4 T cells by specific peptide-MHC class II complexes /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/4994.
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Valiathan, Rajeshwari Rajan. "Functional interactions of HIV-1 GAg with the cellular endocytic pathway /." Access full-text from WCMC, 2007. http://proquest.umi.com/pqdweb?did=1481666381&sid=16&Fmt=2&clientId=8424&RQT=309&VName=PQD.
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Mundin, Georgia Sabio Porto. "Identificação de marcadores moleculares para células T reguladoras humanas com perfil CD4+CD25+ por phage display." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5146/tde-28012009-131608/.
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Há dados na literatura indicando que as células que saem do timo com o fenótipo CD4+CD25+ são desenvolvidas continuamente como uma linhagem independente e possuem um papel importante no processo de regulação da resposta imune. Essas células são chamadas células T reguladoras naturais. Várias questões sobre estas células permanecem em aberto, como por exemplo, como elas são geradas, o que é determinante na sua atividade reguladora e que marcadores específicos podem ser usados para identificá-las? Dentro deste contexto, o nosso objetivo neste trabalho foi identificar no timo e em timócitos CD4+/CD25+ humanos, novas moléculas potencialmente importantes no desenvolvimento e/ou na atividade supressora das células T reguladoras naturais. Para este objetivo, utilizamos a abordagem de phage display, com uma biblioteca de fagos de peptídeos, e timos humanos obtidos de pacientes portadores de cardiopatias congênitas, submetidos a cirurgias cardíacas realizadas no InCor. A busca dessas moléculas foi feita, separadamente, em 3 tipos de material biológico: timócitos totais, fragmento do tecido tímico e timócitos CD4+/CD25+. Antes da incubação da biblioteca de fagos com os timócitos totais e timócitos CD4+/CD25+ (separação em FACS), foi realizada uma etapa de preclearing, incubando-se a biblioteca de fagos com um pool de células mononucleares de sangue periférico (PBMC) ou timócitos CD4+/CD25-, respectivamente. Os fagos não ligantes, recuperados desta etapa, foram então incubados com as células de interesse. Para o tecido tímico não foi feita etapa de pre-clearing. Os fagos obtidos com os diferentes materiais biológicos foram recuperados em cultura de bactérias e usados em ciclos posteriores de seleção. Após três ciclos de seleção, os fagos foram seqüenciados e identificados quanto à expressão de peptídeos ligantes para timócitos totais, timo e timócitos CD4+/CD25+, e analisados em bancos de dados no BLAST. Os fagos selecionados para validação um ligante de tecido tímico: M2C e um ligante de timócitos CD4+/CD25+: R2A fazem similaridade a duas proteínas associadas ao metabolismo da Vitamina D3, molécula envolvida em imunorregulação e indução de tolerância, em diversos modelos experimentais. Porém, não há dados na literatura a respeito do seu papel em células T reg naturais. Na validação molecular desses fagos, apesar de certa variabilidade entre os diferentes ensaios, verificamos, por ELISA, que os fagos se ligam preferencialmente a 1,25 diidroxivitamina D3, forma ativa da Vitamina D3. Entretanto, nos ensaios de validação funcional, a influência da vitamina D na diferenciação dessas células não foi confirmada de forma consistente, uma vez que só tivemos aumento no número de células CD4+/CD25+, em cultura com Vitamina D, em poucos experimentos. As moléculas identificadas no presente estudo podem ter implicações relevantes no processo de diferenciação e na atividade de células T CD4+CD25+ reguladoras e serão mais investigadas na continuidade deste trabalho.There are consistent data in literature indicating that thymic CD4+CD25+ cells play an important role in immune regulation and are continuously developed as an independent lineage in the thymus. These cells are known as natural regulatory T cells. Several questions about these cells remain unanswered, such as how they are generated, what is determinant in their regulatory function and which specific molecular markers can be used to identify them. Taking this into consideration, our aim was to identify new potentially important molecules in the development and/or supressive function of natural regulatory T cells, both in the thymus and in CD4+CD25+ thymocytes. For this, the phage display technique was employed, with a peptide phage library and thymic specimens obtained from children who underwent corrective cardiac surgery at the Heart Institute (InCor), in São Paulo. The search for these molecules was separately performed in 3 types of biological material: thymic tissue, thymocytes and CD4+CD25+ thymic cells. In the first stage, the phage peptide-library was incubated with a pool of PBMC (peripheral blood mononuclear cells). After the incubation, phages bound to PBMC were discarded (pre-clearing). In the second stage, unbound phages were incubated with either total thymocytes or CD4+CD25+ thymic cells. The pre-clearing stage was not perfomed in the thymic tissue. The phages obtained with after incubation with the different biological materials were recovered in E. coli culture and used in additional cycles of selection. After three rounds of selection, the recovered phages from the total thymocytes, from thymic tissue and thymocytes CD4+CD25+ were sequenced and their ligands identified. Among the phages selected for validation one ligand of thymic tissue: M2C and one ligand of CD4+CD25+ thymocytes: R2A present similarity to two proteins associated to the metabolism of Vitamin D3, a molecule involved in imunoregulation and toelrance induction in several experimental models. However, there are no data in the literature concerning the possible role of this moelcule in natural regulatory T cells. In the molecular validation of theses phages, although some variability between the diffeterent assays we have verified by ELISA, that the phages present preferential binding to the 1,25 dhydroxyvitamin D3, the active form of Vitamin D3. However, in the functional validation assays, the influence of the Vitamin D3 in the differentiation of these cells could not be consistently confirmed since we could observe an increase in the number of CD4+CD25+ cells cultured with vitamin D in only a few experiments. The ligand-receptor molecules we have defined in this study may have relevant implications in the development of CD4+CD25+ regulatory T cells in the thymus
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Lozza, Laura. "Analysis of human antigen-experienced CD4 T cells according to IL7Ralpha and CCR7 expression." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16110.
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Das Ziel dieser Arbeit war, die funktionellen Charkteristika von humanen antigenerfahrenen CD4-T-Zellen in Relation zur Expression von IL-7Ra und CCR7 zu untersuchen. Im Rahmen dessen wurden zwei verschiedene experimentelle Ansätze wurden gewählt: Zur Analyse von Populationen, die während einer Primärantwort auftreten, wurden antigenerfahrene CD4-T-Zellen in vitro mit TSST-beladenen dendritischen Zellen stimuliert. Der zweite Ansatz bestand darin, zirkulierende antigenerfahrene CD4-T-Zellen entsprechend ihrer CCR7- und IL7R-Expression zu isolieren, um die heterogenen zirkulierenden T-Zellen zu untersuchen. Die Experimente zeigen, daß IL7RhiCCR7+ T-Zellen Charakteristika zentraler Gedächtniszellen besitzen. IL7RlowCCR7–identifiziert hingegen Zellen mit Effektor-T-Zellmerkmalen. Dementsprechend wiesen IL7RlowCCR7– T-Zellen ein stark verringertes Zellüberleben auf, waren stark beeinträchtigt in darin in Anwesenheit von homöostatischen Zytokinen zu proliferieren und exprimierten nur wenig IL-2. Im Gegenzug überlebten IL7RhiCCR7+ T-Zellen gut, reagierten auf homöostatische Zytokine, sekretierten IL-2 und expandierten nach antigenspezifischer Stimulation. Interessanterweise erkannten ex vivo isolierte IL7Rlow T-Zellen vornehmlich persistierende Antigene. Dies weist darauf hin, daß diese Zellen chronisch aktiviert sind. In vitro konnte demonstriert werden, daß die funktionelle Ausprägung der den zentralen Gedächtniszellen ähnlichen IL7RhiCCR7+ T-Zellen deutlich von der Stärke der Stimulation während der Generierung der IL7RhiCCR7+ T-Zellen abhängt. Dieser Umstand stützt die Hypothese, daß die Quantität der Signale während der primären Stimulation die Richtung der Zelldifferenzierung bestimmt und ein solcher Mechanismus zur Heterogenität der zentralen Gedächtnis-T-Zellen in vivo beiträgt. Zusammenfassend kann man feststellen, daß, sich die Marker CCR7 und IL7R in Kombination als ein wertvoll zur Identifizierung von CD4-Gedächtnis- und –Effektor-T-Zellen erweisenThe aim of this work was to elucidate the functional characteristics of human antigen-experienced CD4 T cells according to the expression of IL7RAlpha and CCR7. Two different approaches were used: in order to analyze the subsets occurring during a primary response, antigen-experienced CD4 cells were analyzed in vitro after priming with the superantigen TSST. The signal strength of TCR-stimulation during the priming was modulated in order to understand how the levels of stimulation might influence the generation of memory-like T cells. The second approach was to isolate circulating CD4 T cells expressing different combinations of CCR7 and IL7R in order to analyze the heterogeneous pool of antigen-experienced cells found under steady state conditions ex vivo. The results revealed that both in vitro and ex vivo the IL7RhiCCR7+ T cell subset corresponds to cells with TCM characteristics whereas IL7RlowCCR7– identifies cells with effector characteristics. Correspondingly, IL7RlowCCR7–CD4 T cells showed low survival rates, impaired proliferation in the presence of homeostatic cytokines and a low IL-2 production, IL7RhiCCR7+ CD4 T cells survived well, responded to homeostatic cytokines, secreted IL-2 and expanded upon antigenic stimulation. Notably, ex vivo isolated IL7Rlow T cells preferentially recognized under steady state conditions persistent antigens, suggesting that these cells are chronically activated. Finally, it was demonstrated that IL7RhiCCR7+ TCM-like cells generated in vitro acquired different functional properties depending on the strength of stimulation during the priming. This fact supports the concept that the amount of signal received during the priming influences the cell fate decision contributing to the heterogeneity of the TCM pool in vivo. In summary, despite some differences observed between in vitro and ex vivo CD4 T cell subsets, the combination of the markers CCR7 and IL7R is useful to distinguish memory- from effector-like CD4 T cells.
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Fernandez, Sonia. "CD4? T-cell deficiency and dysfunction in HIV patients receiving combination antiretroviral therapy." University of Western Australia. School of Surgery and Pathology, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0120.
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[Truncated abstract] Failure to fully reconstitute the immune system is a common clinical problem in HIV patients who were severely immunodeficient before responding to combination antiretroviral therapy (CART). This can manifest as a deficiency in the number or function of CD4+ T-cells and occurs most often in patients who had a nadir CD4+ T-cell count below 100/μl when CART was commenced. Observational studies of large cohorts of HIV patients, such as the D:A:D study, have demonstrated that patients with low CD4+ T-cell counts have increased rates of death compared with patients who have normal CD4+ T-cell counts. Furthermore, individual case studies suggest that impaired recovery of pathogen-specific immune responses during CART is associated with opportunistic infections or disease progression. This thesis addresses possible causes of deficiencies in CD4+ T-cell number or function in HIV patients who were very immunodeficient prior to treatment and are responding (virologically) to CART. Firstly, the role of the thymus in producing naive CD4+ T-cells and the effects of persistent immune activation on the recovery of CD4+ T-cell numbers were assessed in patients with either low or high CD4+ T-cell counts after long-term CART. ... Proportions of antigen presenting cell (APC) subpopulations were examined in HIV patients with low or high CMV-specific CD4+ T-cell responses after long-term CART. HIV patients had significantly lower proportions of plasmacytoid dendritic cells (pDC) than HIV-negative controls. Furthermore, the proportions of pDC were positively correlated with CMV-specific CD4+ T-cell responses in HIV patients. Proportions of myeloid dendritic cells (mDC) were significantly higher in HIV patients than controls, and were also increased in patients with low CMV-specific CD4+ T-cell responses. Proportions of M-DC8+ dendritic cells or CD14+ monocytes did not differ between patients and controls, nor were they associated with CMV-specific CD4+ T-cell responses. Quantitation of cytokine (interferon-α, tumour necrosis factor-α, interleukin (IL) -12, IL-23, IL-15, IL-18 and IL-10) mRNA in unstimulated, purified populations of the APC described above revealed few significant differences between patients with low or high CD4+ T-cell IFN-γ responses to CMV. The only notable difference was the slight elevation of IL-15 mRNA levels in patients compared to controls. Since patients in the high responder group had the highest levels of IL-15 mRNA, this association may reflect the anti-apoptotic properties of IL-15. These studies provide valuable insights into the causes of persistent CD4+ T-cell deficiency and dysfunction in HIV patients on CART and may lead to better monitoring and treatments.
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Blish, Catherine Anne. "Modulation of T cell function and T cell receptor repertoire during the induction of peripheral tolerance /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/8323.
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Galperin, Moran. "Molecular and functional characterization of high avidity T cell receptors preferentially expressed by HIV-specific CD4 + T cells from HIV controllers." Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC251.
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Les « HIV controllers » (HICS) sont de rares patients qui contrôlent spontanément la réplication du VIH en absence de thérapie antirétrovirale. Ces patients sont caractérisés par un taux normal de Cellules T CD4+ et le maintien d'une charge virale indétectable (< 50 copies d'ARN viral / ml de plasma), et montrent un très faible risque de progression vers le sida, de nombreux travaux suggèrent que le contrôle de la réplication virale chez ces patients est dû à une réponse cellulaire antivirale. Particulièrement efficace, notre équipe a montré que ces hics maintiennent des réponses T CD4+ très sensibles, associées à l'expression de TCRS ayant une forte avidité pour certains peptides gag du VIH. Il a été montré en particulier que les cellules T CD4+ de hics répondent à de très faibles concentrations de l'épitope immunodominant GAG293. Dans une première étude, nous avons montré que les cellules T CD4+ des hics maintiennent une population de cellules effectrices de type THI, caractérisées par une production importante d'IFN gamma et du marqueur de dégranulation CD107a en réponse à une stimulation par GAG293, notamment, ces réponses TH1 effectrices persistent malgré la faible quantité d'antigènes viraux présents dans l'organisme des hics. Par contre, les patients traités voient leurs réponses T CD4+ effectrices décroître avec le temps suite à une inhibition par l'IL-10, ce qui suggère la persistance d'une immunosuppression. Malgré la thérapie antirétrovirale prolongée (> 10 ans), la persistance de réponses effectrices T CD4+efficaces malgré une faible virémie pourrait s'expliquer par la présence de cellules T CD4+ de haute avidité chez les hics. Ces résultats nous ont conduit à explorer les niveaux d'expression de T-BET dans les cellules de hics ex vivo, car ce facteur de transcription est critique pour la différenciation des T CD4+ naïves en cellules de type THI. Les niveaux d'expression de T-BET se sont révélés supérieurs chez les cellules TCD4+ des hics par rapport aux cellules issues de donneurs sains. Néanmoins, nous n'avons pas détecté une augmentation de l'expression de T-BET dans les cellules T CD4+ des hics par rapport à celles des patients traités. La possibilité que l'expression de T-BET diffère dans les cellules T CD4+ spécifiques du VIH chez les HICS et chez les patients traités reste à être explorée. La réponse de haute avidité observée pour les cellules T CD4+ des HICS semble s'expliquer par une propriété intrinsèque de leur TCR, en effet, les tétramères de molécules CMH II chargés en peptide GAG293 lient plus efficacement les TCR présents à la surface des cellules T CD4+ + des HICS que celles des patients traités, indiquant une différence dans l'avidité intrinsèque des TCRS, pour identifier les déterminants moléculaires qui sous-tendent cette réponse de haute avidité, nous avons caractérisé le répertoire TCR des cellules T CD4+ spécifiques de l'épitope immunodominant GAG293, les HICS ont montré un répertoire TCR hautement biaisé, caractérisé par une expression préférentielle des chaînes TCR TRAV24 et TRBV2, la présence de motifs conservés au sein des régions CDR3 de ces deux chaînes, et une prévalence élevée de clonotypes publics (n"18 pour chaque chaine de TCR). Les clonotypes publics les plus représentés ont été capables de générer des TCR fonctionnels ayant de affinité de l'ordre du micromolaire pour le complexe PCMH II, ce qui est remarquablement élevé pour les TCRS restreints par le CMH II. Nous avons montré que les TCR de haute affinité spécifiques pour GAG293 sont capables de reconnaitre jusqu'à 5 allèles différents de HLA-DR, de plus, après transduction à l'aide de lentivecteurs, ces TCR ont conféré une réponse spécifique à GAG293 très sensible et polyfonctionnelle aux cellules T CD4+ primaires. Par ailleurs, l'expression de ces TCR dans des cellules T CDS+ leur a permis de répondre à GAG293, malgré l'absence du corécepteur CD4, ces résultats suggèrent que des clonotypes publics ayant une fonctionnalité plus efficace sont impliqués dans le contrôle de l'infection par le VIH. Le transfert de ces TCR dans des cellules hétérologues pourraient contribuer au développement de nouvelles approches immunothérapeutiques contre le VIHHIV controllers are rare individuals who spontaneously control HIV replication without the need for therapeutic intervention, these patients are characterized by normal CD4+ T cell counts and viral loads, which remain below the limit of detection (<50 RNA copies per milliliter plasma) for extended periods of time, importantly, HIV controllers very rarely progress to aids, accumulating evidence suggests that control of viral replication in these patients is mediated by a particularly efficient cellular immune response. Indeed, our team previously reported that HIV controllers maintain a population of specific CD4+ T cells of high functional avidity, these cells were shown to produce IFN gamma in response to minimal amounts of the immunodominant GAG293 peptide. In a first study, we have shown that HIV controller CD4+ T cells maintain a population of highly efficient effector cells, which are characterized by increased production of IFN gamma and the degranulation marker CD107A in response to stimulation with GAG293, notably, these THI responses persisted in HIV controllers despite the minimal amount of viral antigens available to induce such responses, in contrast, CD4+ T cells from treated patients showed increased expression of IL-10, indicating negative immunoregulation after long-term antiretroviral therapy, the persistence of efficient CD4+ T effector responses in spite of low antigenemia may be explained by the presence of high avidity CD4+ T cells in HIV controllers. These findings prompted us to explore the ex vivo expression patterns of T-BET, which is a key transcription factor driving the differentiation towards THI lineage, T-BET expression levels were higher in HIV controllers compared with healthy blood donors, However, we did not detect Increased T-BET expression in controller CD4+ T cells compared to patients receiving highly active antiretroviral therapy (haart), the possibility that T-BET expression differs in the HIV -specific CD4+ T cells of controllers and treated patients remains to be tested. The high functional avidity observed in controller CD4+ T cells could be explained by an intrinsic property of their t cell receptors (TCRS), which efficiently round GAG293-loaded MHC class-II tetramers, to identify the molecular determinants underlying this hight avidity response, we characterized the TCR repertoire directed at the immunodominant capsid epitope, GAG293. HIV controllers showed a highly skewed repertoire characterized by a predominance of the TRAV24 and TRBV2 variable gene families, the presence of conserved motifs in both CDR3 regions, and a high prevalence of public clonotypes (N=18 for each TCR chain), the most prevalent public clonotypes generated TCR with affinities in the micro-molar range, at the high end of values reported for naturally occurring TCRS, the high-affinity GAG293-specific TCRS conferred broad HLA 11 cross-restriction, with up to 5 HLA-DR alleles recognized, high antigen sensitivity, and polyfunctionalityTo primary CD4+ T cells, in addition, CD8+ T cells could be redirected to target the conserved capsid major homology region by expressing a high-affinity GAG293-specific TCR, these findings indicate that TCR clonotypes with superior functions are associated with HIV control, amplifying or transferring such clonotypes may contribute to immunotherapeutic approaches that aim at a functional HIV cure
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Lundmark, Frida. "Genetic analysis of IL7R and other immune-regulatory genes in multiple sclerosis /." Stockholm : Karolinska institutet, 2007. http://diss.kib.ki.se/2007/978-91-7357-278-1/.
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Waas, Ruth. "EINFLUSS DER EXPRESSION ΑLPHA1-ADRENERGER REZEPTOREN VON CD4(+)-T-LYMPHOZYTEN AUF DIE EXTRAARTIKULÄRE ORGANMANIFESTATION BEI PATIENTEN MIT RHEUMATOIDER ARTHRITIS." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-131307.
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Katecholamine beeinflussen durch direkte Stimulation über adrenerge Rezeptoren die Funktion von Immunzellen. Ziel der Untersuchungen an Patienten mit Rheumatoider Arthritis war es, das Expressionsprofil unterschiedlicher adrenerger Rezeptorsubtypen in CD4(+)T-Lymphozyten dieser Patienten zu bestimmen. Zur Quantifizierung der Expression wurden semiquantitative RT-PCR-Analysen durchgeführt. Die Untersuchung zeigte, dass alpha1-adrenerge Rezeptoren in CD4(+)-T-Lymphozyten von RA-Patienten exprimiert werden. Es scheint eine Korrelation zwischen bestimmten extraartikulären Organmanifestationen (z.B. Sicca-Sydrom und Tenosynovitis) und der Expression alpha1-adrenerger Rezeptoren zu bestehen. Die gefundene differenzielle Expression der Rezeptoren in CD4(+)-T-Lymphozyten von RA-Patienten legen vertiefende Untersuchungen zur Relevanz des adrenergen Systems bei der Lymphozytenfunktionsmodulation nahe.
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Fadul, Nada, Jacob Couturier, Xiaoying Yu, Claudia A. Kozinetz, Roberto Arduino, and Dorothy E. Lewis. "Treatment-Naïve HIV-Infected Patients Have Fewer Gut-Homing β7 Memory CD4 T Cells than Healthy Controls." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/1497.
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OBJECTIVES: The integrin α4β7 is the gut-homing receptor for lymphocytes. It also is an important co-receptor for human immunodeficiency virus (HIV) via glycoprotein (gp)120 binding. Depletion of gut cluster of differentiation (CD)4 T cells is linked to chronic inflammation in patients with HIV; however, measuring CD4 cells in the gut is invasive and not routine. As such, establishing a peripheral marker for CD4 depletion of the gut is needed. We hypothesized that α4β7 CD4 T cells are depleted in the peripheral blood of treatment-naïve patients with HIV compared with healthy controls.
METHODS: The study groups were treatment-naïve patients with HIV and uninfected controls. Subjects were included if they were 18 years or older with no history of opportunistic infections, active tuberculosis, or cancer. We collected peripheral blood and examined on whole blood using flow cytometry for the following cell surface markers: CD4, CD45RO, chemokine receptor type 5, C-X-C chemokine receptor type 4 (CXCR4), and the integrin β7. We collected demographic information, including age, sex, and ethnicity, as well as viral load (VL) and CD4 count. Two-samplettests and Fisher exact tests were used to compare the differences between the two groups. Spearman correlation coefficients were calculated between CD4 count and log10-VL and percentage of CD4+/CD45RO+/β7+and log10-VL in patients.
RESULTS: Twenty-two subjects were enrolled in the study (12 patients with HIV and 10 controls). There were no differences in age or sex between the two groups. There were more Hispanics and fewer Asians in the group comprising patients with HIV compared with the control group (7 vs 2 and 0 vs 4,P= 0.05, respectively). Patients infected with HIV had significantly lower frequencies of CD4+/CD45RO+/β7+cells (median 12%, range 5-18 compared with uninfected controls: median 20%, range 11-26,P= 0.0007). There was a statistically significant difference in the percentage of CD4+/CD45RO+/C-X-C chemokine receptor type 4+cells between patients (72%, range 60%-91%) compared with controls (79%, range 72%-94%,P= 0.04). The percentage of CD4+/CD45RO+/chemokine receptor type 5+did not differ between the group of patients with HIV and the control groups (22%, range 11%-57% vs 27%, range 14%-31%;P= 0.8, respectively). There was no correlation between percentage of CD4+/CD45RO+/β+cells and log10-VL as measured by the Spearman correlation coefficient (r= 0.05,P= 0.88) in patients infected with HIV.
CONCLUSIONS: Memory CD4 β7+cells are reduced significantly in the peripheral blood of untreated patients infected with HIV, which could be used as a noninvasive indicator of intestinal CD4 T cell loss and recovery. Further studies are needed to examine whether depletion of these CD4+/CD45RO+/β7+cells in the peripheral blood parallels depletion in the gut of treatment-naïve patients with HIV and whether levels return to control levels after treatment.
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Engelschalt, Vivienne. "Mechanismen der antikörpervermittelten T-Zell-Depletion in vivo im Maus-Modell." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16234.
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Monoklonale Antikörper (mAk) werden bereits erfolgreich zur therapeutischen Depletion verschiedener Zellpopulationen in vivo verwendet, die Mechanismen der Depletion sind jedoch unklar geblieben. In dieser Arbeit wurden im Mausmodell die molekularen Grundlagen der CD4+ T-Zelldepletion (CD4 TZD) nach einmaliger Gabe (i.p.) von 100 µg des anti-CD4-mAk YTS191.1 untersucht. Dabei konnte eine starke Korrelation zwischen Depletion und der Modulation des CD4-Moleküls von der Oberfläche beobachtet werden. Gleichzeitig zeigten sich organabhängige Unterschiede, sowohl im zeitlichen Verlauf, als auch in der Effizienz der Depletion. Im Thymus konnten weder Depletion noch Modulation detektiert werden, in Milz und Lymphknoten (Lk) war die CD4 TZD nach starker CD4-Modulation bereits nach 48 h mit 80-90 % maximal, in den Peyer-Plaques jedoch niedriger und verzögert (50-60 % nach 72 h). Anhand C3-defizienter Mäuse konnte ferner kein wesentlicher Beitrag von Komplement an der CD4 TZD beobachtet werden. Im Gegensatz dazu konnte durch die Verwendung verschiedener FcGamma-Rezeptor (FcGammaR)-defizienter Mäuse (FcGammaRI, FcGammaRII, FcGammaRIII, FcGammaRI/III und FcRGamma) wie auch durch die Blockade des FcGammaRIV eine starke, zudem organabhängige Beteiligung von FcGammaR an der CD4 TZD gezeigt werden. Während in der Milz die CD4 TZD von FcGammaRIV vermittelt wurde, waren in den Lk und Peyer-Plaques FcGammaRI/III involviert. Diese Befunde korrelierten mit der starken Expression von FcGammaRIV in Milz, Lunge, Darm, Niere und Leber, während in den Lk nur eine schwache und in Thymus und Peyer-Plaques keine Expression detektiert werden konnte. Innerhalb der Milz konnten erstmalig F4/80hoch Makrophagen als FcGammaRIV+ identifiziert und somit als potenzielle Effektorzellen der CD4 TZD bestimmt werden. Der direkte Vergleich der Depletion von CD4+ T-Zellen mit der Depletion von ICOS+ T-Zellen verdeutlichte darüber hinaus, dass die Effizienz der Zelldepletion nicht nur von den Eigenschaften des verwendeten mAk, sondern auch von denen des Zielmoleküls abhängig ist.Monoclonal antibodies (mAb) are efficiently used for the therapeutic depletion of various cells in vivo yet the mechanisms of depletion are still unclear. In this work, the molecular principles of CD4+ T cell depletion (CD4 Tcd) by a single application of 100 µg of the anti-CD4 mAb YTS191.1.1 were investigated in the mouse. A strong correlation between the depletion and the surface modulation of the CD4 molecule could be observed. At the same time, organ-dependent differences in the kinetics as well as in the efficiency of depletion could be detected. In the thymus, neither modulation nor depletion were detectable. In the spleen and the lymph nodes (Ln), the modulation was strong and the depletion was maximal (80-90%) 48 h after mAb treatment. Interestingly, both modulation and depletion were decreased and delayed (50-60% after 72 h) in the Peyer`s patches. By using C3-deficient mice, no major contribution of complement to the CD4 Tcd was seen. On the contrary, with the help of different FcGamma-receptor (FcGammaR)-deficient mice (FcGammaRI, FcGammaRII, FcGammaRIII, FcGammaRI/III, and FcRGamma) and through the blockade of FcGammaRIV, a strong organ dependent involvement of FcGammaR could be shown. While the depletion in the spleen was clearly dependent on FcGammaRIV, in the Ln and the Peyer`s patches, FcGammaRI/III were involved. These findings correlated with the strong expression of FcGammaRIV in the spleen, the lung, the colon, the kidney, and the liver, while in the Ln the expression was weak and undetectable in the thymus and the Peyer`s patches. For the first time, F4/80high macrophages in the spleen could be identified as also being FcGammaRIV+, and are therfore considered as the potential effector cells of the CD4 Tcd. The direct comparison of the depletion of T cells via CD4 or ICOS pointed out that the target cell depletion is not only dependent on the properties of the mAb used, but also on those of the target molecule.
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Simões, Inês Tadeu dos Anjos. "Functional and therapeutical implications of ligand recognition by the scavenger-like lymphocyte receptors CD5 and CD6." Master's thesis, Faculdade de Ciências e Tecnologia, 2011. http://hdl.handle.net/10362/6582.
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Dissertação para obtenção do Grau de Mestre em
Genética Molecular e BiomedicinaThe CD5 and CD6 lymphocyte surface receptors are highly homologous members of the Scavenger Receptor Cystein Rich (SRCR) superfamily mainly expressed by all T lymphocytes and the B1a subpopulation of B cells. Although the ultimate function/s are far from being completely understood, CD5 and CD6 are known to play a relevant role in both lymphocyte development and differentiation by negatively modulating the survival/death-inducing intracellular signals generated during the antigen recognition. Recently, this group has developed a transgenic mouse line which expresses a soluble form of human CD5, likely blocking the ligand-receptor interactions mediated by CD5 and interfering with normal lymphocyte response. This study was aimed at furthering the study of the recombinant soluble human CD5 Transgenic(rshCD5Tg) mouse phenotypical analysis, its response to antigen stimuli and tumor implantation; the function of rshCD6 was also tested. It was observed that rshCD5Tg mice display an exacerbated immune response, likely due to a reduction in the number of T and B cells with regulatory/suppressive function (Treg, B1a, B10 cells) and the increase in effector cells (NKT, MZ B cells). In agreement with these phenotypical characteristics, the functional analysis of rshCD5Tg mice showed enhanced immune responses to Tdependent and –independent antigens, as well as enhanced anti-tumoral responses, with or without concomitant chemotherapy treatment. Importantly, both the phenotypical and functional findings could be reproduced in wild-type mice following prolonged infusion of purified exogenous rshCD5 protein. Overall, these results argue in favor of a relevant role of CD5-mediated molecular interactions in the homeostasis of functionally relevant lymphocyte subpopulations and open the possibility for CD5-based therapeutical interventions in different disease settings such as cancer, infection and immunodeficiency.
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Jellison, Evan Robert. "CD4 T Cell-Mediated Lysis and Polyclonal Activation of B Cells During Lymphocytic Choriomeningitis Virus Infection: A Dissertation." eScholarship@UMMS, 2008. https://escholarship.umassmed.edu/gsbs_diss/349.
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CD4 T cells and B cells are cells associated with the adaptive immune system. The adaptive immune system is designed to mount a rapid antigen-specific response to pathogens by way of clonal expansions of T and B cells bearing discrete antigen-specific receptors. During viral infection, interactions between CD4 T cells and B cells occur in a dynamic process, where B cells that bind to the virus internalize and degrade virus particles. The B cells then present viral antigens to virus-specific CD4 T cells that activate the B cells and cause them to proliferate and differentiate into virus-specific antibody-secreting cells. Yet, non-specific hypergammaglobulinemia and the production of self-reactive antibodies occur during many viral infections, and studies have suggested that viral antigen-presenting B cells may become polyclonally activated by CD4 T cells in vivo in the absence of viral engagement of the B cell receptor. This presumed polyclonal B cell activation associated with virus infection is of great medical interest because it may be involved in the initiation of autoimmunity or contribute to the long-term maintenance of B cell memory.
In order to directly examine the interactions that occur between T cells and B cells, I asked what would happen to a polyclonal population of B cells that are presenting viral antigens, if they were transferred into virus-infected hosts. I performed these studies in mice using the well-characterized lymphocytic choriomeningitis virus (LCMV) model of infection. I found that the transferred population of antigen-presenting B cells had two fates. Some antigen-expressing B cells were killed in vivo by CD4 T cells in the first day after transfer into LCMV-infected hosts. However, B cells that survived the cytotoxicity underwent a dynamic polyclonal activation manifested by proliferation, changes in phenotype, and antibody production.
The specific elimination of antigen-presenting B cells following adoptive transfer into LCMV-infected hosts is the first evidence that MHC class II-restricted killing can occur in vivo during viral infection. This killing was specific, because only cells expressing specific viral peptides were eliminated, and they were only eliminated in LCMV-infected mice. In addition to peptide specificity, killing was restricted to MHC class II high cells that expressed the B cell markers B220 and CD19. Mice depleted of CD4 T cells prior to adoptive transfer did not eliminate virus-specific targets, suggesting that CD4 T cells are required for this killing. I found that CD4 T cell-dependent cytotoxicity cannot be solely explained by one mechanism, but Fas-FasL interactions and perforin are mechanisms used to induce lysis.
Polyclonal B cell activation, hypothesized to be the cause of virus-induced hypergammaglobulinemia, has never been formally described in vivo. Based on previous studies of virus-induced hypergammaglobulinemia, which showed that CD4 T cells were required and that hypergammaglobulinemia was more likely to occur when virus grows to high titer in vivo, it was proposed that the B cells responsible for hypergammaglobulinemia may be expressing viral antigens to virus-specific CD4 T cells in vivo. CD4 T cells would then activate the B cells. However, because the antibodies produced during hypergammaglobulinemia are predominantly not virus-specific, nonvirus-specific B cells must be presenting viral antigens in vivo.
In my studies, the adoptively transferred B cells that survived the MHC class II-restricted cytotoxicity became polyclonally activated in LCMV-infected mice. Most of the surviving naïve B cells presenting class II MHC peptides underwent an extensive differentiation process involving both proliferation and secretion of antibodies. Both events required CD4 cells and CD40/CD40L interactions to occur but B cell division did not require MyD88-dependent signaling, type I interferon signaling, or interferon γ signaling within B cells. No division or activation of B cells was detected at all in virus-infected hosts in the absence of cognate CD4 T cells and class II antigen. B cells taken from immunologically tolerant donor LCMV carrier mice with high LCMV antigen load became activated following adoptive transfer into LCMV-infected hosts, suggesting that B cells can present sufficient antigen for this process during a viral infection. A transgenic population of B cells presenting viral antigens was also stimulated to undergo polyclonal activation in LCMV-infected mice. Due to the high proportion of B cells stimulated by virus infection and the fact that transgenic B cells can be activated in this manner, I conclude that virus-induced polyclonal B cell activation is independent of B cell receptor specificity. This approach, therefore, formally demonstrates and quantifies a virus-induced polyclonal proliferation and differentiation of B cells which can occur in a B cell receptor-independent manner.
By examining the fate of antigen-presenting B cells following adoptive transfer into LCMV-infected mice, I have been able to observe dynamic interactions between virus-specific CD4 T cells and B cells during viral infection. Adoptive transfer of antigen-presenting B cells results in CD4 T cell-mediated killing and polyclonal activation of B cells during LCMV infection. Studies showing requirements for CD4 T cells or MHC class II to control viral infections must now take MHC class II-restricted cytotoxicity into account. Polyclonal B cell activation after viral infection has the potential to enhance the maintenance of B cell memory or lead to the onset of autoimmune disease.
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Chau, Suk-yi, and 周淑怡. "A study of the expression of Sonic hedgehog and its receptors in T cells and the identification of Sonic hedgehog dowm-stream targets inactivated CD4+T cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31386234.
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Chau, Suk-yi. "A study of the expression of Sonic hedgehog and its receptors in T cells and the identification of Sonic hedgehog dowm-stream targets in activated CD4+T cells." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31386234.
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Ngandu, Jean Pierre Kabue. "Coreceptor expression and T lymphocyte subset distribution in HIV-infected and TB co-infected South African patients on anti-retroviral therapy." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2219.
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Thesis (MScMedSc (Pathology. Medical Virology))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: In 2007, AIDS caused an estimated 2.1 millions deaths worldwide; about 70% in sub-Saharan Africa. HIV preferentially targets activated CD4 T cells, expressing the major HIV receptor CD4, as well as the major chemokine coreceptors CCR5 and CXCR4. These coreceptors play a prominent role during HIV cell entrance phase, HIV transmission and also disease progression. They have been found to be differentially expressed by CD4 T cell subsets. Tuberculosis coinfection may enhance immune activation in vivo thus accelerating HIV disease progression and has become a major challenge in the control of TB in Africa. Introduction of HAART has reduced disease progression to AIDS, as well as risk of further morbidity and mortality. HAART results in a rapid decline of viral load and an initial increase of peripheral CD4 count, however little is known on the effect of HAART in regulation of coreceptor expression, immune activation status and CD4 T cell subset distribution in HIV infection and HIV/TB coinfection. This study is a cross-sectional analysis of coreceptor expression, immune activation status and CD4 T cell subpopulation distribution in South African HIV and HIV/TB coinfected patients before and after ARV. A total of 137 South African individuals were investigated, comprising 15 healthy normal donors (healthy subgroup), 10 patients with active pulmonary tuberculosis (PTB subgroup), 33 HIV-1 positive patients without active PTB (HIV subgroup), 23 positive patients with active PTB (HIV/PTB subgroup), 36 HIV-1 positive patients on ARV (HIV on ARV subgroup) and 20 HIV-1 positive patients with active PTB on ARV (HIV/PTB on ARV subgroup). CD4 absolute count and plasma viral load were determined for all donors. Freshly isolated PBMC were classified by flow cytometry into the following CD4+ T lymphocyte subsets: naïve (CD45+, CD27+), effector memory (CD45-, CD27-), central memory (CD45-, CD27+), and effector (CD45+, CD27-). Coreceptor expression and activation status was assessed by CCR5, CXCR4 and CD38 expression on CD4 T cell subsets. HIV, TB and HIV/TB coinfection was associated with a decrease in percentage CCR5+ T cells as compared to healthy controls, with the HIV/TB group showing the most extensive decrease. In treatment naive patients, CD4 T cells showed elevated surface expression of CCR5 and CD38 as determined by mean fluorescence intensity in HIV/TB co-infection compared to HIV infection alone. The percentage of antigen-experienced cells was higher in the HIV/TB co-infected group compared to the HIV group. The percentage of naïve T cells was decreased in both the HIV infected and the HIV/TB co-infected groups compared to healthy controls. HIV patients with more than 6 months of ARV showed decreased CCR5 and CD38 surface level expression in the HIV and the HIV/ TB co-infected subgroups. An increased percentage of naïve T cells was observed in the HIV infected subgroup, but not in the HIV/TB subgroup, similarly, a decreased percentage of antigen-experienced cells was observed in the HIV subgroup, but not in the HIV/TB co-infected subgroup. A positive correlation was found between CCR5 and CD38 expression, and CXCR4 and CD38 expression (Spearman coefficient of correlation respectively: r=0.59, p<0.001 and r=0.55, p<0.001). Furthermore we found plasma viral load positively associated with CD38 expression (r=0.31, p<0.001) and percentage activated CCR5+ expressing CD4 T cells positively related to viral load (r=0.31, p<0.001). Percentage naïve CD4 T cells was positively associated with CD4 count (r=0.60, p<0.001) and negatively correlated to viral load (r=-0.42, p<0.001). These results indicate that TB coinfection exacerbates certain aspects of dysregulation of CD4 T cell homeostasis and activation caused by HIV infection. In addition, ARV-associated decrease in coreceptor expression, immune activation status and a normalisation of CD4 T cell subset distribution was observed in HIV infected individuals, but not in HIV/TB coinfection. Despite viral suppression after ARV treatment, the decline in the immune activation marker CD38 and coreceptor CCR5 expression, increase in percentage naïve CD4 T cells and decrease of antigen-experienced cells did not reach the levels displayed in the healthy control group. This may indicate that ongoing (albeit reduced) T cell immune activation may occur in the presence of ARV. Further longitudinal studies are needed to closely monitor immune activation during ARV treatment. This study highlighted an association of TB disease with immune activation in HIV infection, the importance of T-cell activation in HIV pathogenesis and its impact on ARV treatment. Further studies are needed to identify causative factors that may lead to a persistent immune activation status during ARV treatment, and how TB coinfection confounds normal responses to ARV.
AFRIKAANSE OPSOMMING: In 2007 was ongeveer 2.1 miljoen sterftes wêreldwyd veroorsaak deur VIGS; ongeveer 70% in Sub-Sahara Afrika. CD4 T selle is die hoof teiken van MIV, aangesien dit die primêre CD4 reseptor, sowel as een of beide van die vernaamste chemokien koreseptore CCR5 en CXCR4 vrystel. Hierdie koreseptore speel ‘n prominente rol wanneer die MIV die sel binnedring, asook tydens MIV oordrag en verloop van die siekte. Dit word ook deur verskillende fraksies van CD4 T selle vrygestel. Gelyktydige TB infeksie mag immuunaktivering in vivo verhoog en dus die siekeproses versnel. MIV het ‘n groot uitdaging geword in die beheer van TB in Afrika. Bekendstelling van HAART het die ontwikkeling van VIGS vertraag, asook die risiko van verdere morbiditeit en mortaliteit. HAART veroorsaak ‘n vinnige afname in virale lading ‘n toename in CD4 telling, hoewel die spesifieke invloed van HAART op die regulering van koreseptor vrystelling, immuunaktivering en verspreiding van CD4 fraksies in MIV en MIV/TB infeksies nog onduidelik is. Hierdie studie het gepoog om koreseptor vrystelling, immuunaktiveringstatus en die verspreiding van CD4 subpopulasies in pasiënte met MIV en MIV/TB voor en na ARV behandeling te ondersoek. ‘n Totaal van 137 Suid-Afrikaanse individue is ondersoek en die studiegroep het bestaan uit 15 normale persone (gesonde subgroep), 10 pasiënte met aktiewe pulmonale TB (PTB subgroup), 33 MIV positiewe pasiënte sonder PTB (MIV subgroep), 23 MIV positiewe pasiënte met aktiewe PTB (MIV/PTB subgroep), 36 MIV positiewe pasiënte op ARV (MIV op ARV subgroep) en 20 MIV positiewe pasiënte met aktiewe PTB op ARV (MIV/PTB op ARV subgroep). Absolute CD4 telling en virale ladings was bepaal vir alle deelnemers. Vars geïsoleerde perifere bloed mononukleêre selle is geklassifiseer deur middel van vloeisitometrie as die volgende CD4 T limfosiet subgroepe: naïewe selle (CD45+, CD27+), effektor geheueselle (CD45-, CD27-), sentrale geheueselle (CD45-, CD27+), en effektor selle (CD45+, CD27-). Koreseptor vrystelling en aktivering was beoordeel volgens CCR5, CXCR4 en CD38 vrystelling op CD4 T sel subgroepe. HIV, TB en MIV/TB ko-infeksie is geassosieer met ‘n afname in die persentasie CCR5+ T selle, vergeleke met gesonde kontroles, waar die MIV/TB subgroep die grootste afname getoon het. In onbehandelde pasiënte het die CD4 T selle verhoogde vrystelling van CCR5 en CD38 op die oppervlakte getoon en dit is bevestig deur die gemiddelde fluoresserende vii intensiteit in die MIV/TB subgroep vergeleke met die subgroep met slegs MIV. Die MIV/TB subgroep het verder ook ‘n verhoogde persentasie totale geheue T selle getoon vergeleke met die MIV subgroep. Die persentasie naïewe T selle was egter verlaag in beide die MIV en MIV/TB subgroepe vergeleke met normale kontroles. MIV pasiënte wat langer as 6 maande op ARV behandeling was in beide die MIV en MIV/TB subgroepe, het ‘n verlaagde vrystelling van CCR5 en CD38 op die oppervlakte van die CD4 selle getoon. ‘n Verhoogde persentasie naïewe T selle het in die MIV subgroep voorgekom, maar nie in die MIV/TB subgroup nie. ‘n Soortgelyke tendens is gevind waar die persentasie totale geheueselle verlaag was in die MIV subgroep, maar nie in die MIV/TB subgroep nie. ‘n Positiewe korrelasie is gevind tussen CCR5 en CD38 vrystelling, asook CXCR4 en CD38 vrystelling (Spearman korrelasie koëffisiënt: r=0.59, p<0.001 en r=0.55, p<0.001 onderskeidelik). Verder het die plasma virale lading ‘n positiewe assosiasie getoon met CD38 vrystelling (r=0.31, p<0.001) en die persentasie geaktiveerde CCR5+ vrystellende CD4 T selle met virale lading (r=0.31, p<0.001). Die persentasie naïewe CD4 T selle het ‘n positiewe assosiasie getoon met CD4 telling (r=0.60, p<0.001) en ‘n negatiewe korrelasie met virale lading (r=-0.42, p<0.001). Volgens hierdie resultate vererger TB ko-infeksie sekere aspekte van die disregulasie van CD4 T selhomeostase en aktivering as gevolg van MIV infeksie. Verder kon ‘n ARVgeassosieerde afname in koreseptor vrystelling, immuunaktivering en normalisering van CD4 T sel fraksies bespeur word in die MIV subgroep, maar nie in die MIV/TB subgroep nie. Ten spyte van virale onderdrukking veroorsaak deur ARV behandeling, het die afname in die immuunmerker CD38 en koreseptor CCR5, toename in die persentasie naïewe CD4 selle en afname in totale geheue CD4 T selle nie die vlakke van die normale kontrolegroep bereik nie. Dit is moontlik dat volgehoue verlaagde T sel immuunaktivering nog steeds mag plaasvind in die teenwoordigheid van ARV. Verdere longitudinale studies is nodig om immuunaktivering tydens ARV behandeling te monitor. Hierdie studie het die belangrikheid van T sel aktivering in MIV patogenese en dit impak daarvan op ARV behandeling beklemtoon. Verdere studies is nodig om moontlike oorsake of bydraende faktore te identifiseer wat tot volgehoue immuunaktivering tydens ARV behandeling kan lei, asook tot mate waartoe TB ko-infeksie kan inmeng met die normale werking van ARV behandeling.
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Madera, Rachel F. "RNA-Sensing Pattern Recognition Receptors and Their Effects on T-Cell Immune Responses: A Dissertation." eScholarship@UMMS, 2012. https://escholarship.umassmed.edu/gsbs_diss/644.
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Virus infection is sensed by the innate immune system through germline encoded pattern recognition receptors (PRRs). Toll-like receptors (TLRs), retinoic acid-inducible gene-I-like receptors (RLRs) and nucleotide-binding oligomerization domain-like receptors (NLRs) serve as PRRs that recognize different viral components. Microbial nucleic acids such as Ribonucleic acid (RNA) are important virus-derived pathogen-associated molecular patterns (PAMPs) to be recognized by PRRs. Virus recognition may occur at multiple stages of the viral life cycle. Replication intermediates such as single-stranded RNA (ssRNA) and double-stranded RNA (dsRNA) are detected by the RNA-sensing PRRs that initiate innate and adaptive immune responses. Triggering of the innate immune system is a critical event that can shape the adaptive immune response to virus infection. Better vaccination strategies that lead to improved T-cell and antibody responses are needed for protection against pathogens. We sought to delineate the RNA-sensing PRR pathways that are activated during infection with an RNA virus, the signaling mediators involved and the influence on subsequent virus-specific adaptive immune responses.
To analyze the role of RNA-sensing PRRs in T-cell immune responses in vitro, we performed direct co-stimulation experiments on CD4+ T-cells of high purity. We utilized synthetic RNA-like immune response modifiers (IRMs) R-848 (MyD88-dependent) and poly I:C (MyD88-independent) as RNA PAMPs to determine the direct effects of RNA-sensing PRR activation on CD4+ T-cells. RNA PAMPs can act directly on CD4+ T-cells and modulate their function and phenotype. Maximal direct co-stimulatory effects were observed in CD4+ T-cells cultured with poly I:C compared to R-848. The cytoplasmic dsRNA-dependent protein kinase R (PKR) was also involved in poly I:C-mediated signaling in CD4+ T-cells.
We found differences in the RNA-sensing PRRs activated by R-848 between mouse and human CD4+ T-cells. We observed minimal direct co-stimulatory effects by R-848 in mouse CD4+ T-cells. In contrast, augmentation of Th1 responses by R-848 was observed in human CD4+ T-cells. TLR8 activation in human CD4+ T-cells may explain the observed differences.
We next explored the signaling pathways activated by RNA PAMPs in conventional dendritic cells (cDCs) and CD4+ T-cells that drive Th1 CD4 T-cell responses in isolated cDC/CD4 T-cell interactions. Allogeneic cDCs and CD4+ T-cells of high purity were cultured together with R-848 and poly I:C in MHC congenic mixed leukocyte reactions (MLRs). R-848 and poly I:C stimulation of type I IFN production and signaling was essential but not sufficient for driving CD4+ Th1 responses. The early production of IL-1α and IL-1β was equally critical.
To analyze the role of RNA-sensing PRRs in T-cell immune responses in vivo, we utilized a mouse model of heterosubtypic influenza A virus (IAV) infections. Using MyD88-/-, TLR7-/- and IL-1-deficient mice, we explored the role of MyD88-signaling in the generation of heterosubtypic memory CD4+ T-cell, CD8+ T-cell and antibody responses. We found that MyD88 signaling played an important role in anti-IAV spleen and lung CD4+ T-cell, spleen CD8+ T-cell and Th1 antibody immune responses. Anti-IAV lung heterosubtypic CD8+ T-cell responses were not dependent on MyD88 signaling.
Our in vitro and in vivo results show the pivotal role of RNA-sensing PRR pathway activation in T-cell immune responses. Understanding the complexity of the PRR pathways involved during viral infections and defining the subsequent immune response would have important implications for the generation of more effective vaccine strategies.
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Maroun, Christiane. "Distinct mechanisms regulate antigen receptor mediated signalling in CD4+ and CD8+ primary T cells." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39960.
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For the last two decades, available results have suggested that CD4 and CD8 are functional analogs which, expressed in a mutually exclusive fashion, have provided a fundamental basis for the characterization of the two T cell lineages. This functional analogy has been described during both T cell development and maturation, as well as during the activation of mature peripheral T lymphocytes. It has been demonstrated that the stringency for CD4/CD8 expression, and their ability to interact with MHC molecules during positive and negative selection, are comparable. Further, mAb mediated coaggregation of either CD4 or CD8 with TCR$ alpha beta$ enhances TCR$ alpha beta$ mediated responses in mature T cells to the same degree. These studies have suggested that both CD4 and CD8 need be juxtaposed with the antigen receptor complex in order to provide their positive functions. We have re-addressed the role of CD4 and CD8 during antigen receptor mediated T cell activation, and have characterized major distinctions between these two accessory activation molecules. Thus, while aggregation of membrane CD4 on primary CD4$ sp+$ lymph node T cells results in a 10-fold inhibition of DNA synthesis subsequently induced through TCR$ alpha beta,$ aggregation of CD8 on CD8$ sp+$ primary T cells has no effect. These results are correlated with the differential localization and activity of Lck in the two T cell lineages. Further, while membrane expression of the tyrosine specific phosphatase, CD45, predicates TCR$ alpha beta$ signalling both in CD4$ sp+$ and CD8$ sp+$ T cells, we present evidence indicating that the mechanism through which this phosphatase functions is distinct in the two T cell lineages. Taken together, the results presented demonstrate fundamental differences in the constraints placed on antigen receptor signalling in the two T cell lineages, which may reflect the distinct properties of CD4 and CD8 themselves, and/or lineage specific differences arising as a consequen
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Breuning, Johannes. "Molecular mechanisms of immune regulation by the receptors CD5 and CD6." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:d5ac44af-e452-4561-854d-53901a78da93.
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T cells are adaptive immune cells that are essential for initiating and regulating immune responses. T cell activation is triggered by stimulation of the T cell receptor. However, sustained T cell activation requires the function of a variety of coreceptors, among them CD5 and CD6. Both receptors have been shown to have activating and inhibitory functions and modulation of CD6 function is dependent on engagement by its ligand CD166. Costimulatory signalling by CD6 involves a phosphorylation-dependent interaction between the C-terminal Y662 residue and the adaptor protein SLP-76. However, the CD6 cytoplasmic region is one of the longest in the immune system and contains phosphorylated residues which suggests that additional signalling molecules can be recruited. I identified an interaction of CD5 and CD6 with the cytoskeleton via ezrin, radixin and moesin. This interaction has an activating function on Jurkat cell activation and may play a role in receptor localisation. I also identified the adapter protein GADS as a binding partner of the CD6 Y629 residue and found evidence for bivalent binding of the GADS/SLP-76 complex to the CD6 C terminus. Costimulation by CD6 is dependent on the recruitment of this complex and mutant CD6 that cannot recruit it does not provide costimulation and may even be inhibitory in the absence of its ligand. These results suggest a model in which costimulation by CD6 depends on cooperative binding of the GADS/SLP-76 complex to two C-terminal phosphotyrosine residues in the CD6 cytoplasmic region. Binding of this complex to CD6 may enhance long-term signalling by keeping GADS/SLP-76 at the membrane or it may provide an alternative signalling pathway that enhances TCR signalling.
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Glassman, Caleb R., Heather L. Parrish, Mark S. Lee, and Michael S. Kuhns. "Reciprocal TCR-CD3 and CD4 Engagement of a Nucleating pMHCII Stabilizes a Functional Receptor Macrocomplex." CELL PRESS, 2018. http://hdl.handle.net/10150/627048.
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CD4(+) T cells convert the time that T cell receptors (TCRs) interact with peptides embedded within class II major histocompatibility complex molecules (pMHCII) into signals that direct cell-fate decisions. In principle, TCRs relay information to intracellular signaling motifs of the associated CD3 subunits, while CD4 recruits the kinase Lck to those motifs upon coincident detection of pMHCII. But the mechanics by which this occurs remain enigmatic. In one model, the TCR and CD4 bind pMHCII independently, while in another, CD4 interacts with a composite surface formed by the TCR-CD3 complex bound to pMHCII. Here, we report that the duration of TCR-pMHCII interactions impact CD4 binding to MHCII. In turn, CD4 increases TCR confinement to pMHCII via reciprocal interactions involving membrane distal and proximal CD4 ectodomains. The data suggest that a precisely assembled macrocomplex functions to reliably convert TCR-pMHCII confinement into reproducible signals that orchestrate adaptive immunity.
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Sampaio, Raquel João Santos Ferreira Nunes. "The signaling role of the accessory receptors CD2 and CD6 in T cell activation." Tese, Instituto de Ciências Biomédicas Abel Salazar, 2007. http://hdl.handle.net/10216/7167.
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Sampaio, Raquel João Santos Ferreira Nunes. "The signaling role of the accessory receptors CD2 and CD6 in T cell activation." Doctoral thesis, Instituto de Ciências Biomédicas Abel Salazar, 2007. http://hdl.handle.net/10216/7167.
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Jiang, Ning. "Kinetic analysis of Fcγ receptor and T cell receptor interacting with respective ligands." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/26716.
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Low affinity Fcg receptor III (FcgRIII, CD16) triggers a variety of cellular events upon binding to the Fc portion of IgG. A real-time flow cytometry method was developed to measure the affinity and kinetics of such low affinity receptor/ligand interactions, which was shown as an easily operated yet powerful tool. Results revealed an unusual temperature dependence of reverse rate of CD16aTM dissociating from IgG. Except for a few studies using mammalian cell CD16s, most kinetics analyses use purified aglycosylated extracellular portion of the molecules, making it impossible to assess the importance of the receptor anchor and glycosylation on ligand binding. We used a micropipette adhesion frequency assay to demonstrate that the anchor length affects the forward rate and affinity of CD16s for IgG in a species specific manner, most likely through conformational changes. Receptor glycosylation dramatically reduced ligand binding by 100 folds. T cell receptor (TCR) is arguably the most important receptor in the adaptive human immune system. Together with coreceptor CD4 or CD8, TCR can discriminate different antigen peptides complexed with major histocompatibility complex (MHC) molecule (pMHC), which differ by as few as only one amino acid, and trigger different T cell responses. When T cell signaling was suppressed, TCR had similar affinity and kinetics for agonist and antagonist pMHC whose binding to CD8 was undetectable. TCR on activated T cell had a higher affinity for pMHCs, suggesting that TCRs organize themselves differently on activated T cells than on naïve T cells. In the absence of inhibitors for signaling, TCR binds agonist pMHC with several orders of magnitude higher affinity than antagonist pMHC. In addition, engagement of TCR by pMHC signals an upregulation of CD8 binding to pMHC, which is much stronger than the TCR-pMHC binding. The transition from weak TCR binding to the strong CD8 binding takes place around 0.75 second after TCR in contact with pMHC and can be reduced by several inhibitors of tyrosine and lipid phosphorylation, membrane rafts, and actin cytoskeleton. These results provide new insights to understanding T cell discrimination.
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Julià, Manresa Marc. "Receptores del sistema inmunitario innato (Toll-like receptors y receptores de la Fc-gamma) y adaptativo (CD5 y CD6) como factores de susceptibilidad, modificadores de la enfermedad y respuesta al tratamiento biológico en psoriasis." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668023.
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La psoriasis es una enfermedad inflamatoria crónica inmunomediada principalmente cutánea caracterizada por la presencia de placas eritematodescamativas en zonas de extensión y cuero cabelludo. En su fisiopatogenia se implican múltiples componentes tanto al sistema inmunitario innato como adaptativo. En esta Tesis Doctoral, se presentan 4 trabajos originales en los que se analiza el impacto de distintos polimorfismos genéticos de receptores del sistema inmunitario innato (receptores toll-like y de la Fc-gamma) y de sistema inmunitario adaptativo (CD5 y CD6) como factores modificadores del fenotipo, de susceptibilidad a la enfermedad y de respuesta al tratamiento de la psoriasis. Además, se aportan las primeras evidencias experimentales in vivo e in vitro de la implicación del receptor linfocítico CD6 en la fisiopatogenia de la enfermedad.Psoriasis is a chronic immuno-mediated inflammatory cutaneous disease characterized by the presence of erythematous and desquamative plaques tipically appearing in extension areas and the scalp. In its pathophysiology, multiple components of both the innate and adaptive immune system have been implicated. In this Doctoral Thesis, 4 original studies are presented analyzing different genetic polymorphisms of receptors belonging to both the innate (toll-like and Fc-gamma receptors) and adaptive immune system (CD5 and CD6) as potential factors that modify the phenotype, the susceptibility and the response to treatment in psoriasis. In addition, the first in vivo and in vitro experimental evidences of the involvement of CD6 lymphocyte receptor in psoriasis are provided.
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Maekawa, Akiko Medical Sciences Faculty of Medicine UNSW. "Characterisation of the immune co-receptor function of CD4." Publisher:University of New South Wales. Medical Sciences, 2007. http://handle.unsw.edu.au/1959.4/40498.
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CD4 is a co-receptor for binding of T cells to antigen-presenting cells (APC) and the primary receptor for human immunodeficiency virus-I. The disulfide bond in the second extracellular domain (D2) of CD4 is reduced on the cell surface, which leads to formation of disulfide-linked homodimers. A large conformational change must take place in D2 to allow for formation of the disulfide-linked dimer. Domain swapping of D2 is the most likely candidate for the conformational change leading to formation of two disulfide-bonds between Cysl30 in one monomer and Cysl59 in the other one (Cys133 and Cysl62 in the mouse CD4). Thus, we hypothesized that the domain swapping of D2 in CD4 regulates its co-receptor function of antigenspecific T cell activation. We found that mild reduction of the extracellular part of human CD4 resulted in formation of disulfide-linked dimers. We then tested the functional significance of dimer formation for co-receptor function using the engineered Jurkat T cell system by expressing wild-type or disulfide-bond mutant mouse CD4. Eliminating the D2 disulfide bond markedly impaired CD4's coreceptor function as assessed by antigen-specific IL-2 production. Exogenous wild type thioredoxin, but not redox-inactive thioredoxin, could inhibit the CD4-mediated IL-2 production, suggesting that the redox state of D2 disulfide bond is controlled by this oxidoreductase. Furthermore, structural modeling of the complex ofthe T cell receptor and domain-swapped CD4 dimer bound to class II major histocompatibility complex and antigen supports the domain-swapped dimer as the immune co-receptor. The known involvement of D4 residues Lys318 and Gln344 in dimer formation isalso accommodated by this model. These findings imply that disulfide-linked dimeric CD4 is the preferred functional co-receptor for binding to APC. Strategies to promote dimerisation of CD4 should, therefore, enhance the immune response, while inhibiting dimer formation is predicted to be immunosuppressive.
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Klosterhoff, Marta da Costa. "Desenvolvimento ontogênico do rim, timo e baço e expressão fenotípica dos receptores CD3 e CD4 em linfócitos do bijupirá Rachycentron canadum." reponame:Repositório Institucional da FURG, 2012. http://repositorio.furg.br/handle/1/2527.
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Dissertação(mestrado)- Universidade Federal do Rio Grande, Programa de Pós-Graduação em Aqüicultura, Instituto de Oceanografia, 2012.Submitted by Cristiane Silva (cristiane_gomides@hotmail.com) on 2012-08-29T19:19:57Z No. of bitstreams: 1 dissertao verso final-martaklosterhoff.pdf: 1924880 bytes, checksum: bc195444bdcc5176b1707b88f00b25c1 (MD5)
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O bijupirá Rachycentron canadum, apresenta várias características favoráveis para a aquicultura, como alta taxa de crescimento, bons coeficientes de eficiência alimentar e carne de excelente qualidade, entre outras. No presente estudo foi realizada uma análise do sistema imune do bijupirá através de técnicas de histologia e imunohistoquímica. A ontogenia dos órgãos imunocompetentes (rim anterior, timo e baço) em larvas e juvenis de bijupirá, desde a eclosão até 53 dias após a eclosão (dae), foi realizada através da análise histológica. O rim foi o primeiro órgão linfohematopoiético a aparecer, presente no 1º dia após eclosão (dae) (3,8 ± 0,04mm), o surgimento do baço foi no 5º dae (4,8 ± 0,2mm) e no 7º dae (5,4 ± 0,2 mm) o timo; conforme análise os órgãos linfóides tornaram-se evidente com o avanço da idade do peixe. Foi possível também estabelecer a presença de receptores específicos de linfócitos através da imunomarcação com anticorpo monoclonal anti-CD3 e anti-CD4. Foi encontrado no timo os primeiros receptores linfocitários CD3 ao 7º dae com 27% mm² e 99% mm² de tecido tímico aos 53 dae (154 ± 4,6mm). A expressão fenotípica dos receptores CD3 no rim foi destacada no 8º dae (6,5 ± 0,1mm) com uma expressão de 10% mm² e 32% mm² de tecido renal aos 53 dae. A imunomarcação dos receptores linfocitários CD4 foi destacada inicialmente no timo com 7 dae, com 5% mm² e aos 53 dae com 63% mm² de linfócitos imunomarcados com anti-CD4. No Rim, a população de linfócitos T4 foi registrada primeiramente aos 13º dae (12,4 ± 0,7 mm) com 9% mm² e aos 53 dae com 28% mm² da população linfocitária CD4 do tecido renal, definindo o desenvolvimento funcional do sistema específico, associada a capacidade da memória imunológica. Também foi possível estabelecer que ocorre uma repovoação de linfócitos T no rim anterior, os linfócitos que migram do rim anterior para o timo e adquirem receptores específicos de células T, retornando ao rim anterior e mantendo suas atividades imunes. O estudo dos mecanismos do sistema imune são importantes para o sucesso de um cultivo, pois as doenças são uma das principais causas de perdas econômicas na aquicultura em todo mundo.
The cobia Rachycentron canadum has several desirable traits for aquaculture, most importantly a rapid growth rate, good feed conversion ratio and good flesh quality. In the present study, the immune system of cobia was evaluated through histology and immunohistochemistry. Ontogeny of immunocompetent organs (head kidney, thymus and spleen) in cobia larvae and juveniles from hatching to 53 days after hatching (dah) was histologically described. The first lymphohematopoietic organ to appear was the kidney, at 1 dah (3.8 ± 0.04 mm), followed by the spleen at 5 dah (4.8 ± 0.2 mm) and the thymus at 7 dah (5.4 ± 0.2 mm); the lymphoid organs became evident as the fish grew older. It was also possible to establish the presence of specific lymphocyte receptors through immunolabeling with the monoclonal antibodies anti-CD3 and anti-CD4. The first evidence of CD3 lymphocyte receptors was found at 7 dah with 27% mm² of thymic tissue and at 8 dah (6.5 ± 0.1 mm) in the kidney, expressed in 10% of the kidney tissue. Initially, 5% mm2 of lymphocytes with CD4 lymphocyte receptors were initially immunolabeled in the thymus. In the kidney, T4 lymphocyte population was registered to be present at 13 dah (12.4 ± 0.7 mm) with 9% mm², defining the functional development of the specific system, associated to immunological memory capacity It was also possible to establish a repopulation of T lymphocytes in the head kidney; lymphocytes migrate from the head kidney to the thymus and acquire specific T-cell receptors, returning to the head kidney and maintaining their immune activities. The knowledge about the immune system mechanisms is important for farming activities, as diseases are the major causes of economic losses in global aquaculture.
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Weigand, Luise [Verfasser], Heinrich H. D. [Akademischer Betreuer] Meyer, and Angela [Akademischer Betreuer] Krackhardt. "Characterization of human MHC II-restricted T cell receptors with reactivity against B cells and tumor cells for therapeutic application in the context of adoptive T cell transfer of transgenic CD4 T cells / Luise Weigand. Gutachter: Angela Krackhardt ; Heinrich H. D. Meyer. Betreuer: Heinrich H. D. Meyer." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1016727798/34.
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Lamontagne-Blouin, Christopher. "Modulation of T cell antigen receptor signaling in CD8+ T lymphocytes following priming with homeostatic and inflammatory cytokines." Mémoire, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/6325.
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La stimulation de cellules T naïves nécessite du déclenchement de la signalisation par l'intermédiaire du récepteur d'antigène de cellule T (TCR) ainsi que l'activation simultanée des récepteurs de co-stimulation. Toutefois, les cellules T CD8+ naïves peuvent proliférer de façon antigène-indépendants suite à la stimulation synergique par certaines cytokines homéostatiques (IL-7 ou IL-15) et inflammatoires (IL-6 ou IL-21). Ces cellules pré-stimulées prolifèrent même à des faibles concentrations d'antigènes ou en présence d’agonistes du TCR. Ceci leur permet de sécréter des cytokines effectrices, d'être plus spécifiques à leur antigène et d’avoir une activité cytolytique plus importante. Les mécanismes déclenchés par les cellules T CD8+ permettant une sensibilité accrue à l'antigène suite à la "pré-stimulation aux cytokines" n'ont pas encore été élucidés. Nous avons utilisé trois différents modèles de souris transgéniques portant le TCR P14, PMEL ou 8.3-NOD sur les lymphocytes T CD8+ afin d’étudier les mécanismes moléculaires suite à la pré-stimulation aux cytokines. Les cellules T CD8+ portant le TCR transgénique amorcées avec les cytokines, possèdent une augmentation globale des protéines tyrosine-phosphorylés après stimulation du TCR par rapport aux cellules naïves. Cette augmentation de la phosphorylation de la protéine tyrosine a été associée à une augmentation de l'expression de CD8, et a été moins prononcé lorsque CD8 a également été réticulés avec le TCR. Ceci suggère que l'amorçage aux cytokines peut prédisposer le TCR et CD8 à colocaliser, ce qui renforcerait la phosphorylation des chaînes du TCR par la kinase Lck associée à CD8. Les lymphocytes T CD8+ amorcées aux cytokines présentent également des quantités accrues de radeaux lipidiques plasmatiques à la membrane, qui organisent la plate-forme de signalisation du TCR au cours de la stimulation antigénique. L’amorçage aux cytokines des lymphocytes T CD8+ a également augmenté la localisation de CD45, une phosphatase qui diminue l’inhibition automatique de la Lck dans les radeaux lipidiques. Cependant, l'amorçage aux cytokines n'a pas d'incidence sur la capacité des cellules CD8+ T pour former des conjugués avec les cellules présentatrices d'antigène puisées avec des peptides apparentés. En conclusion, ces résultats suggèrent que la composition et les fonctions des radeaux lipidiques peuvent moduler la sensibilité à l'antigène via le TCR lorsque les lymphocytes T CD8+ ont été pré-stimulés aux cytokines.
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Geleziunas, Romas. "Mechanisms of CD4 receptor downmodulation in HIV-1 infected cell lines." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41338.
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We have examined the factors leading to cell-surface downmodulation of CD4 in HIV-1 infected U-937 cells as a model system for the study of monocytic cells. In contrast to the rapid disappearance of CD4 transcripts in chronically infected T-cell lines, CD4 mRNA levels were unaltered following infection of U-937 cells and two other monocytic cell lines (PLB985 and THP-1) with HIV-III$ sb{ rm B}$. However, infected U-937 cells contained reduced levels of immunoprecipitable CD4 that were complexed intra-cytoplasmically with the HIV-1 envelope precursor, gp160. We next compared CD4 and actin biosynthesis in cellular clones that had been derived by limiting dilution of chronically-infected U-937 cells. In spite of a variety of viral phenotypes produced by these clones, including generation of defective particles, cell surface CD4 was absent in each case studied although levels of CD4 mRNA were not affected. In addition, biosynthesis of CD4 was reduced in all cases in which active expression of viral products had occurred. In general, we observed an inverse correlation between high levels of gp160 expression and CD4 biosynthesis. These findings were reproduced using a microsome-containing in vitro co-translation system involving both CD4 mRNA and gp160 mRNA. To rule out the possibility that U-937 monocytes might select HIV-1 variants unable to modulate CD4 gene expression, we passaged infectious virus from a U-937 clonal derivative onto different monocytic and T-lymphocytic cell lines. We found that infection of each of two lymphocytic cell lines, led to cytopathic replication, and reduced levels of CD4 transcripts. In contrast, infection of three monocytic cell lines failed to generate cytopathicity and did not cause CD4 transcript downmodulation. These studies demonstrate that CD4 transcript modulation in chronically-infected cell lines is determined by cell lineage and that CD4 biosynthesis is impaired during generation of gp160.
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Yáñez, Del Río Paula Andrea. "Detección de quimioquinas homeostáticas, sus receptores e interleuquina-7 en periodontitis crónica." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/148632.
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Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaLas enfermedades periodontales son un conjunto de patologías de etiología infecciosa y naturaleza inflamatoria que incluyen las gingivitis y periodontitis. Durante las periodontitis, si bien las bacterias que colonizan la bio-película subgingival pueden generar un daño directo al periodonto, es su interacción con el hospedero lo que provoca la formación del infiltrado inmuno-inflamatorio que lleva a la destrucción de los tejidos de soporte de los dientes y eventualmente a la pérdida de ellos. Durante la constitución de este infiltrado immuno-inflamatorio, los linfocitos T migran desde los linfonodos hacia los tejidos periodontales siguiendo la señalización de quimioquinas inflamatorias, las que aumentan localmente durante las periodontitis. En la última década, las quimioquinas homeostáticas han sido el foco de investigación de la patogénesis de varias enfermedades inflamatorias crónicas, tal como la artritis reumatoide y el síndrome de Sjögren, en las cuales participarían en la formación de estructuras linfoides ectópicas. La presencia de quimioquinas y citoquinas homeostáticas en estas agrupaciones linfoides lleva al incremento en la migración de células indiferenciadas hacia los tejidos inflamados, favoreciendo la presentación antigénica y diferenciación linfocitaria in situ, perpetuándose el proceso inflamatorio. En este trabajo de investigación se analizó la expresión de varias quimioquinas homeostáticas y sus receptores durante la periodontitis crónica. A partir de biopsias obtenidas de pacientes con periodontitis crónica e individuos sanos, se cuantificó mediante RT-qPCR la expresión de los mRNA de las quimioquinas CXCL12, CXCL13, CCL19 y CCL21, de los receptores CCR7, CXCR4 y CXCR5, y de la citoquina IL-7. Además, se cuantificó la secreción de CCL19, CCL21 y CXCL12 en el fluido gingival crevicular mediante ELISA. Finalmente, la expresión de CCR7 fue analizada usando Western Blot en homogeneizados tisulares. En las lesiones periodontales de pacientes con periodontitis crónica se expresaron mayores niveles de CCL19, CCL21, CXCL12, CCR7, CXCR4 y CXCR5 en comparación a los tejidos periodontales de individuos sanos, lo que contribuiría a explicar, al menos en parte, la cronicidad y sitioespecificidad de las periodontitis.
Adscrito a Proyecto de FONDECYT regular 1140904.
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Haas, Karen Marie. "Induction and regulation of bovine B lymphocyte responses /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9999290.
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Fourmentraux, Emmanuelle. "Modulation de l'activité lymphocytaire T CD4⁺ par le récepteur inhibiteur KIR2DL1." Paris 7, 2009. http://www.theses.fr/2009PA077022.
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L'activité fonctionnelle des cellules immunes est régulée par un équilibre entre des signaux activateurs et inhibiteurs. Les récepteurs inhibiteurs KIR (Killer cell Ig-like Receptors) exprimés par les cellules NK et par les lymphocytes T effecteurs mémoires lient les molécules du CMH-I et suppriment l'activation cellulaire via le recrutement de SHP-1. Pour mieux comprendre le rôle des KIR sur les cellules T CD4⁺, des transfectants KIR2DL1 ont été obtenus à partir d'une lignée T Jurkat et de lymphocytes T CD4⁺ primaires. Suite à une stimulation du TCR, la production d'IL-2 est augmentée dans les cellules T CD4⁺ transfectées par le KIR2DL1 indépendamment de son engagement, mais suite à son engagement l'activation induite par le TCR est inhibée. La co-stimulation du signal positif initié par le TCR via le KIR2DL1 nécessite des ITIM intacts et fait suite à leur phosphorylation. Il s'en suit le recrutement de SHP-2 et une augmentation de la phosphorylation de PKCθ et ERK. Lors du contact avec une cellule cible, la synapse est caractérisée par une augmentation du recrutement des p-Tyr, de SHP-2 et de la PKCθ. L'interaction avec une cellule cible exprimant les ligands du KIR2DL1 induit sa forte accumulation à la synapse et le recrutement de SHP-1/SHP-2 qui inhibent la production d'IL-2. Le KIR2DL1 induirait deux signaux opposés dans les cellules T CD4⁺ dépendant ou non de son engagement. Les résultats inattendus observés sur la régulation des cellules T CD4⁺ par le KIR2DL1, de part la dualité fonctionnelle des ITIM est fondamentale pour déterminer la capacité du système immunitaire à développer une réponse appropriée, c'est à dire à maintenir la balance tolérance/immunitéThe functional activity of immune cells is controlled by a balance between activators and inhibitors signals. The Inhibitory killer Ig-like receptors (KIR) expressed on NK cells and memory effectors T-cell recognize the CMH-I molecules and inhibit cellular activation by SHP-1 recruitment. To better understand the fonction of KIR receptors on CD4⁺ T-cells, KIR2DL1 transfectants were obtained from human T-cell line and from primary CD4⁺ T-cells. Following TCR stimulation, IL-2 production is increased in CD4+ T cells transfected by KIR2DL1 independently of its engagement. When KIR2DL1 is engaged by its cognate ligand the TCR activation is inhibited. Co-stimulation of the TCR signaling by KIR2DL1 requires intact ITIM and their phosphorylation. It induces a subséquent SHP-2 recruitment and an increased of PKCθ and ERK phosphorylation. Synapses leading to activation are characterized by an increase in the recruitment of p-Tyr, SHP-2, and p-PKCθ. Interaction of KIR2DL1 with its ligand leads to a strong synaptic KIR2DL1 accumulation and SHP-1/SHP-2 recruitment resulting in the inhibition of TCR-induced IL-2 production. These data reveal that KIR2DL1 may induce two opposite signaling outputs in CD4⁺ T cells, depending on whether the KIR receptor is bound to its ligand. The unexpected results observed on the regulation of CD4⁺ T cells by KIR2DL1 receptors, through the functional duality of ITIM, is fundamental to determine the immune System capacity to develop an adapted answer, i. E. To maintain the balance between tolerance and immunity
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Marcu, Jahan Phillip. "Novel Insights into CB1 Receptor Signaling and the Anabolic Role of Cannabinoid Receptors in Bone." Diss., Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/233543.
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Cell BiologyPh.D.
Activation of the CB1 receptor is modulated by aspartate residue D2.63176 in transmembrane helix (TMH) II. Interestingly, D2.63 does not affect the affinity for ligand binding at the CB1 receptor. Studies in class A GPCRs have suggested an ionic interaction between residues of TMHII and VII. In this report, modeling studies identified residue K373, in the extracellular (EC)-3 loop, in charged interactions with D2.63. We investigated this possibility by performing reciprocal mutations and biochemical studies. D2.63176A, K373A, D2.63176A-K373A, and the reciprocal mutant with the interacting residues juxtaposed, D2.63176K-K373D were characterized using radioligand binding and guanosine 5'-3-O-(thio)triphosphate functional assays. None of the mutations resulted in a significant change in the binding affinity of CP55,940 or SR141716A. Computational results indicate that the D2.63176-K373 ionic interaction strongly influences the conformation(s) of the EC-3 loop, providing a structure-based rationale for the importance of the EC-3 loop to signal transduction in CB1. Specifically, the putative ionic interaction results in the EC-3 loop pulling over the top (extracellular side) of the receptor; this EC-3 loop conformation may serve protective and mechanistic roles. These results suggest that the ionic interaction between D2.63176 and K373 is crucial for CB1 signal transduction. This work may help to aide drug design efforts for the effective treatment of different diseases. The cannabinoid receptors of osteoblasts may represent a target for the treatment of bone disorders such as osteoporosis. Our research demonstrates that cannabinoids can affect important signaling molecules in osteoblasts. In MC3T3-E1 osteoblastic cells, the CB1 antagonist, AM251, has been reported to induce increases in Runx2 mRNA, mineralized bone nodule formation, and activation of signaling molecules such as ERK and AKT (Wu et al., 2011). Studies from our lab characterizing mice in which both CB1 and CB2 receptors were inactivated by homologous recombination have demonstrated increased bone mass coupled with enhanced osteoblast differentiation of bone marrow stromal cells in culture (manuscript in preparation). We explored the effect of antagonizing CB1 and CB2 cannabinoid receptors in osteoblastic cells to gain insights into molecular pathways that may help to explain the effects of the endocannabinoid system (ECS) in bone development. Our data was generated by running time course experiments with MC3T3-E1 cells under the influence of SR141716A, SR144528 or both in combination. The cells were harvested with a lysis buffer at specific time points and analyzed by western blot analysis. Quantification of protein activation was calculated using LiCor imaging equipment and software. Within 15 minutes, treatment with the CB1 receptor antagonist SR141716A resulted in several fold increases in pERK, pSMAD158, and pAKT. SR144528, a CB2 receptor antagonist, caused increases in pERK and pSMAD158, but not pAKT. When both antagonists were applied together, pERK and pSMAD158 levels increased, while pAKT signaling was diminished compared to SR141716A alone. The finding that cannabinoid receptor antagonists alter the activity of the SMAD158 complex is a novel finding, which suggests that cannabinoids can influence bone morphogenic signaling pathways, and therefore play a significant role in osteoblast differentiation and function.
Temple University--Theses
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Bour, Stéphane. "Translational and post-translational modulation of the CD4 receptor following HIV-1 infection." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39808.
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This study was designed to better define the molecular interactions that govern cell surface depletion of the CD4 receptor after HIV-1 infection of susceptible cells. The effects of intracellular association between the envelope glycoprotein precursor gp160 and CD4 were addressed in the U-937 monocytic cell line. Formation of complexes between these molecules was shown to impact on the maturation and transport of both in U-937 cells that were chronically-infected with either wild-type virus or with viruses unable to cleave the viral envelope precursor protein gp160. This arrest in maturation was demonstrated to be pre-Golgi in nature and was characterized by a lack of oligosaccharide trimming and proteolytic cleavage, for CD4 and gp160, respectively. In addition, the half-lives of both proteins were increased as compared with uncomplexed counterpart molecules. This indicated that the disappearance of CD4 from the cell membrane was due to a blockage in the endoplasmic reticulum and not to gp160-induced degradation.The putative negative effect of HIV-1 infection on CD4 translation was further examined using both tissue culture and cell-free models. First, levels of immunoprecipitable CD4 in chronically-infected U-937 cells were altered as compared with uninfected cells despite an absence of CD4 mRNA down-modulation and a lack of vpu expression. The mechanisms underlying inhibition of CD4 translation were therefore addressed in a cell-free translation system. In the presence of canine pancreatic membranes, we observed that co-translation of gp160-encoding mRNAs resulted in a profound dose-dependent inhibition of CD4 synthesis. This effect was specifically targeted at CD4 and functionally distinct of vpu-mediated, post-translational degradation or CD4. We have further identified the gp160/gp120 envelope glycoproteins as the necessary and sufficient components in mediating the inhibition of CD4 translation in vitro.
To better define the molecular mechanisms involved, we asked whether the high affinity interaction between CD4 and gp160 played a role in this inhibition. Mutated CD4 molecules, which possessed a 20-fold lower affinity for gp160/gp 120 than wild type CD4, were protected from co-translational inhibition by HIV-1 mRNAs that encoded gp160. This suggests that direct interactions between gp160 and nascent CD4 peptides, caused premature termination of CD4 translation.
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Andrews, William David. "A study of the interaction between HIV-1 and its cellular receptor CD4." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282720.
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Shore, David A. "Structural aspects of aB T-cell receptor-mediated activation of the cytotoxic T-lymphocyte by the CD3 and CD8 glycoproteins." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419548.
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Pinheiro, Cláudia Ramos. "Reconhecimento de Candida albicans por fibroblastos murinos: envolvimento de receptores de reconhecimento de patógenos (TLR2 e CD14) e a proteína adaptadora MyD88." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/25/25149/tde-11112013-165304/.
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Os tecidos pulpar e periodontal são frequentemente agredidos por fatores ambientais como calor, trauma mecânico e micro-organismos, sendo estes considerados o fator etiológico principal das periodontopatias e periapicopatias. Dentre as células residentes desses tecidos, especial atenção tem sido dada ao papel dos fibroblastos no desenvolvimento da resposta imune. Fibroblastos são células que respondem à estímulos microbianos e existem evidências do papel de receptores do tipo Toll (TLR) no reconhecimento desses estímulos. Dessa forma, o presente trabalho teve como objetivo principal avaliar o reconhecimento de Candida albicans por fibroblastos gengivais e pulpares. Para tal, fibroblastos isolados a partir de tecido gengival e pulpar de camundongos do grupo controle e deficientes de TLR2, CD14 e MyD88 foram avaliados quanto à expressão de TLRs e moléculas de superfície, resposta proliferativa e produção de citocinas (TGF-β, IL-1β, TNF-α, IL-13 e IL-6), após a estimulação com agonistas de TLR2, TLR4 e C. albicans. Fibroblastos gengivais e pulpares, apesar de provenientes de tecidos diferentes, apresentaram características morfológicas semelhantes. Contudo, a cinética de crescimento dos fibroblastos gengivais deficientes de MyD88 foi mais lenta, e fibroblastos pulpares demoraram mais tempo para surgir a partir dos fragmentos de tecido. A ausência de TLR2 e da molécula adaptadora MyD88 não afetaram a produção de colágeno Tipo I pelos fibroblastos gengivais. Entretanto, fibroblastos deficientes de CD14 apresentaram baixa produção de colágeno. Ademais, os fibroblastos gengivais expressaram TLR2, TLR3, TLR4, assim como as moléculas de adesão ICAM-1 e CD44. A ausência de TLR2 e CD14 interferiu na resposta proliferativa de fibroblastos gengivais e pulpares, respectivamente. O reconhecimento de C. albicans por fibroblastos gengivais e pulpares modulou a produção das citocinas. A produção de TNF-α foi dependente da sinalização via MyD88, CD14 e TLR2, enquanto que a produção de IL-1β e IL-13 foi dependente de TLR2.Pulpal and periapical tissue are frequently injured by heat, mechanical trauma and microorganisms, which are considered the main etiological factor of periodontal and endodontic diseases. Among these tissue resident cells, special attention has been given to fibroblasts in the immune response. Fibroblasts are cells that recognize pathogens through Toll like receptors (TLR). The aim of this study was to evaluate the recognition of Candida albicans by pulpal and gingival fibroblasts from TLR2, CD14, MyD88 knockout mice and control group mice. The results were analyzed concerning the expression of TLR(s) and surface molecules, proliferative response and citokynes production (TGF-β, IL-1β, TNF-α, IL-13 e IL-6) after the cells stimulation with TLR2, TLR4 and C.albicans agonists. Gingival and Pulpal fibroblasts, even isolated from different tissue, showed morphological similarities; however, gingival fibroblast deficient of MyD88 show lower proliferative response and pulpa l fibroblasts needed more time to detach from tissue fragments. The production of Type I collagen was affected in gingival cells deficient of CD14. Gingival fibroblasts expressed TLR2, TLR3, TLR4, and the adhesion molecules (ICAM-1 and CD44). The absence of TLR2 and CD14 interfered with the proliferative response of pulpal and gingival fibroblasts, respectively. The recognition of C. albicans by gingival and pulpal fibroblasts modulated the citokynes production. TNF-α production after the recognition of C. albicans was dependent from MyD88, CD14 and TLR2 molecules, whereas the production of IL-1β and IL-13 was dependent of TLR2.
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Clement, Mathew. "The role of the CD8 co-receptor in CD8+ T-cell activation." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/47019/.
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CD8+ T-cells are essential for the immune control of pathogens and the natural eradication of cancer. CD8+ T-cells also play a major role in the pathogenesis of autoimmunity and alloreactivity. CD8+ T-cells recognize short peptide fragments (8-13 amino acids) presented at the target cell surface bound to Major Histocompatability Class I (MHCI) molecules. Tcell antigen recognition is unique in nature because it involves the binding of a single ligand (peptide–MHC [pMHC]) by two receptors (TCR and CD8). The CD8 glycoprotein, which serves as the coreceptor on MHCI-restricted T-cells, acts to enhance the antigen sensitivity of T-cells by binding to a largely invariant region of MHCI at a site distinct from the TCR docking platform. CD8 has been shown to have multiple roles including enhancing effects on early T-cell activation events and also in controlling the level of T-cell cross-reactivity. The pMHCI/CD8 interaction is classified as having a very weak binding affinity and very fast kinetics. I discovered that this low solution binding affinity is essential in maintaining homeostasis as dramatically increasing the strength of this interaction resulted in total loss of T-cell specificity and activation independent of TCR engagement. This led me to examine the possibility that anti-CD8 antibodies could also bypass the normal requirements for T-cell activation. I identified one specific clonotype of antibody capable of this phenomenon but simultaneously discovered multiple effector phenotypes of other anti-CD8 antibodies. These included both enhancing and inhibitory effects on pMHCI tetramer binding and CD8+ T-cell activation. Subsequently, I explored the possibility of using these inhibitory anti-CD8 antibodies to block T-cell function in systems which are highly dependent on CD8 such as autoreactive CD8+ T-cells. I demonstrated that targeting CD8 can be used as a strategy to block autoreactive CD8+ T-cell activation in the absence of any effect on pathogen specific immunity. This highlights a novel therapeutic strategy that warrants further investigation. Finally, I demonstrated that CD8 can alter the functional avidity of a CD8+ T-cell for its agonists and act to re-arrange the relative potencies of each of its potential agonists, a novel “focussing mechanism” for CD8 in T cell activation. These results provide new insight to the biological role of CD8 in T-cells and even predict a novel mechanism for CD8 in controlling T-cell function. My results also highlight the potential of targeting CD8 for immunotherapeutic design in autoimmune disorders.
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Marttila, Marko. "Cellular receptors for species B adenoviruses." Doctoral thesis, Umeå : Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1351.
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Al, Ssadh Hussain. "The role of immunological receptors CD74 and CD44 in association with the macrophage Migration Inhibitory Factor (MIF) on human breast cancer derived cells." Thesis, University of Essex, 2016. http://repository.essex.ac.uk/16169/.
Full textAbstract:
Synergistic interaction between pairs of membrane-bound receptors has been linked to signalling, cell communication and tumour progression. This study has shown that cluster of differentiation (CD) 74 and CD44 act in synergy and are susceptible to the effect of the macrophage migration inhibitory factor (MIF). MIF is a 12.5 kDa chemokine-like inflammatory mediator, whose ligand is the transmembrane receptor CD74. Recent data suggests that CD74 is involved in proinflammatory responses and tumorigenesis but detailed mechanisms are not fully understood. In normal cells CD74 functions as a chaperone of human leukocyte antigen (HLA)-DR biosynthesis and is expressed in antigen presenting cells in the absence of tumours. Notably, CD44 is also a transmembrane receptor and member of a family of cell adhesion molecules responsible for adhesion between adjacent cells (e.g. antigen presenting cells) and cells in the extracellular matrix. Western blotting and flow cytometry were employed to determine the quantitative expression of CD74, MIF and CD44 in three distinct breast tumour cell lines: CAMA-1, MDA-MB-231 and MDA-MB-435. All three cell lines showed a high expression of CD74, MIF and CD44. Modulation studies showed that IFN-γ and LPS can play a significant role in regulating the expression of CD74, proliferation and cell migration in CAMA-1 and MDA-MB-231 cells; suggesting that CD74 might be involved in controlling immunogenicity and immunoediting of breast cancer cells. To investigate the interaction of CD74 with CD44 and MIF, confocal microscopy and co-immunoprecipitation techniques were used. The three molecules form a multimeric complex in cytoplasmic compartments as measured by confocal microscopy, suggesting a mechanistic mode of action; in addition CD74, MIF and CD44 showed significant quantitative variations on all breast cancer derived cells. Knockdown of CD74 by CD74 siRNA significantly reduced CAMA-1 and MDA-MB-231 cell proliferation but increased the level of apoptotic cells. These data suggests that CD74, MIF and CD44, might facilitate signalling and hence could affect tumour progression. Measuring the co-expression levels of CD74, MIF and CD44 could potentially be used as a ‘biomarker signature’ for monitoring breast cancer tumours at different stages of the disease.