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Nassereddine, Aya. "Surface patterning strategies to dissect T-Cell adhesion and actin organisation." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0458.
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Pour une réponse immunitaire efficace, une interaction optimale entre les cellules T et les cellules présentatrices d'antigène (APC) est nécessaire. Elle se présente sous la forme d'un contact cellulaire à différentes échelles allant du moléculaire (1-10 nm) au cellulaire (1-10 micromètres). La liaison entre les récepteurs spéciaux des cellules T (TCR) et leurs ligands sur une APC entraîne une réorganisation moléculaire à plus grande échelle menant d'abord à la formation de micro-clusters de TCR, puis à une restructuration à l'échelle cellulaire de la membrane et du cytosquelette. La création d'un substrat artificiel avec des amas de ligands qui induisent à leur tour l'accumulation de TCR est un outil important pour comprendre le lien entre l'organisation du TCR et de son ligand, l'organisation du cytosquelette d'actine et l'impact de ces deux facteurs sur le comportement cellulaire global, notamment l'adhérence et la signalisation. Nous avons développé un nouveau substrat basé sur la nanotechnologie et utilisé une stratégie alternative basée sur l'auto-assemblage colloïdal pour montrer que le TCR est clairement groupé sur des points de 700 nm et non pas sur des points de 400 nm. L'actine est distribuée de manière homogène sous forme de réseau dans la plupart des cellules, mais dans quelques-unes d'entre elles, elle apparaît sous la forme de points co-localisés avec les amas de ligands. Une observation plus fine à l'aide de la microscopie de reconstruction optique aléatoire indique que les points peuvent en fait être des sites où des faisceaux d'actine se croisent pour former des nœuds non visibles à moindre résolution<br>For an efficient immune response, an optimal interaction between T-cells and antigen presenting cells (APC) is required; it takes the form of a cell-cell contact involving different scales ranging from the molecular (1-10 nm) to the cellular (1-10 micrometer). The ligation of the special T cell receptors (TCR) to its ligands on an APC, leads to larger scale molecular reorganisation leading first to formation of TCR micro-clusters, and later to cell-scale restructuring of both the membrane and the cytoskeleton. Patterning an artificial substrate with ligand-clusters that in turn induce TCR-clustering is an important tool to understand the link between the organisation of TCR and its ligand, the organisation of the actin cytoskeleton and the impact of both on overall cell behavior including adhesion and signaling. We developed a new nanotechnology based substrate (ligand-dot size down to 250 nm) and also used an alternative strategy based on colloidal self-assembly (700 or 400 nm) to show that TCR is clearly clustered on 700 nm dots but not on smaller 400 nm dots. Actin is homogeneously distributed in the form of a network in most cells but in a few of them, it appears as dots that co-localize with the ligand clusters. Finer observation using stochastic optical reconstruction microscopy indicates that the dots may in fact be sites where actin bundles cross each other forming nodes that are not visible at lower resolution. This work confirms a close link between T cell receptor organisation and actin structure
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Regateiro, Frederico Eugenio de Castro Soares. "Probing the mechanisms of action of induced regulatory T cells." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514982.
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Föger, Niko. "Costimulatory function of CD44 : acting in unison with the T cell receptor." kostenfrei, 2000. http://nbn-resolving.de/urn/resolver.pl?urn=nbn:de:bvb:20-opus-1186.
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Fields, Maria. "Homeostasis and function of Regulatory T Cells during Human Immunodeficiency Virus infection." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1408709850.
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Zhang, Michael Sining. "Characterizing how glycerol monolaurate (GML) affects human T cell signaling and function." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6347.
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The T cell receptor (TCR) activation induced signaling cascade is a major driver of T cell effector responses such as cytokine production and actin cytoskeletal rearrangement. Characterizing chemical modulators of this pathway has the benefits of both revealing basic science knowledge about these signaling processes and providing foundation for development of novel therapeutics.
Glycerol Monolaurate (GML) is a naturally occurring fatty acid monoester that is found as a monoglyceride in human breast milk and coconut oil. It is widely utilized in food, cosmetics, and homeopathic supplements. GML is a potent antimicrobial agent that targets a wide range of bacteria, fungi, and enveloped viruses. Because of this, GML has been developed as a preventative for menstrual associated Toxic Shock Syndrome, and is being tested to prevent HIV transmission and superficial skin infections. Interestingly, GML suppresses mitogen induced lymphocyte proliferation and inositol triphosphate production, suggesting that GML has immunomodulatory functions.
This thesis mechanistically examined how GML affects human primary T cells. Chapter III describes how GML potently altered order and disorder dynamics in the plasma membrane that resulted in reduced membrane-localized clustering of the proteins LAT, PLC-γ, and AKT, events integral for proper TCR signal propagation. Altered membrane signaling events induced selective inhibition of TCR-induced signaling events. Specifically GML reduced the phosphorylation of the regulatory P85 subunit of PI3K, and AKT and abrogated calcium influx. Functionally, GML treatment potently reduced TCR-induced production of the cytokines IL-2, IFN-γ, TNF-α, and IL-10. Chapter V shows that GML causes the mis-localization of the ARPC3 subunit of the Arp2/3 complex that leads to the formation of abnormal filopodia structures, and reduced cellular adhesion. Chapter V shows that human serum albumin binds directly to GML on the 12 carbon acyl chain. This interaction reverses GML induced suppression of TCR-induced formation of LAT, PLC-γ1, and AKT microclusters at the plasma membrane, AKT phosphorylation, and cytokine production.
These findings establish GML as a T cell suppressive agent in addition to an antimicrobial agent. This observation reveals the potential role of naturally occurring GML in human breast milk in the formation of microbiota and immune tolerance in the infant gastrointestinal tract. It also allows for optimization of the current applications of GML in various commercial products and therapeutic strategies. Finally this information provides the rationale to investigate GML in new remedial avenues as a topical agent to treat excessive inflammation in the skin, and vaginal and gut mucosal regions.
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Saeed, Mezida Bedru. "Nanoscale rearrangements in cortical actin filaments at lytic immunological synapses." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/nanoscale-rearrangements-in-cortical-actin-filaments-at-lytic-immunological-synapses(8d00dd58-7b1a-435b-ad6c-016b12ff34d9).html.
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Lytic effector function of Natural Killer (NK) cells and CD8+ T cells occurs through discrete and regulated cell biological steps triggered by recognition of diseased cells. Recent studies of the NK cell synapse support the idea that dynamic nanoscale rearrangements in cortical filamentous (F)-actin are a critical cell biological checkpoint for lytic granule access to NK cell membrane. Loss of function mutations in the LYST gene, a well-characterised cause of Chediak- Hegashi syndrome (CHS), result in the formation of giant lysosomal organelles including lytic granules. Here, we report a mismatch between the extent of cortical F-actin remodelling and enlarged lytic granules that limits the functionality of LYST- deficient NK cells in a human model of CHS. Using super-resolution stimulated emission depletion (STED) microscopy we found that LYST-deficient NK cells had nanoscale rearrangements in the organisation of cortical actin filaments that were indistinguishable from control cells- despite a 2.5-fold increase in the size of polarised granules. Importantly, treatment of LYST-deficient NK cells with actin depolymerising drugs increased the formation of small secretory domains at the synapse and restored their ability to lyse target cells. These data establish that sub-synaptic F-actin is the major factor limiting the release of enlarged lytic granules from CHS NK cells, and reveal a novel target for therapeutic interventions. While the importance of cortical actin filaments in NK cell cytotoxicity have been established, its persistence at the early stages of T cell synapse formation is disputed. We studied the organisation of cortical actin filaments in synapses formed by primary human T cells using STED microscopy and detected intact cortical actin filaments in key T cell effector subsets including memory CD8+ T cells as early as 5-minutes post-activation. Quantitative analysis revealed that activation specific rearrangements in cortical actin filaments at both CD4+ and CD8+ T cell synapses serve to increase the space between filaments. Additionally, comparison of cytolytic T cells with freshly isolated and IL-2 activated primary NK cells revealed that rapid maturation of the cortical actin meshwork is a specific feature of CD8+ T cell lytic synapses. Using chemical inhibition of actin nucleators, we show that increased cortical relaxation is mediated primarily by the activity of actin related proteins (Arp) -2/3. Taken together, these data establish the critical requirement for dynamic rearrangements in cortical actin filaments at lytic synapses but underscore cell-specific differences in its regulation.
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Remon, Kerry. "DEF6 aggregation is linked to active translation and mRNA turnover in T cells." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42985/.
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Spatiotemporal responses to extracellular signals have been documented in a wide variety of cells, such as neuronal synapses, cytotoxic T lymphocytes, germ cells and during embryo development. Selective release of a key molecule allows a cell to respond at a given moment, and cells ensure that the response can be initiated instantly by pre-producing and packaging the molecule, often storing the molecule as a granule. Differentially Expressed in FDCP6 is a guanine nucleotide exchange factor, primarily expressed in T cells, which has been previously shown to form cytoplasmic aggregates when phosphorylated by ITK. DEF6 also translocates to the immunological synapse following phosphorylation by LCK in response to antigenic presentation. As a result, DEF6 is a likely candidate in mediating a spatiotemporal response to an extracellular signal in T cells. Data presented in this work suggest that endogenous DEF6 forms cytoplasmic granules in a variety of T cell states and the DEF6 mutant Y210EY222E, which mimics ITK phosphorylation, interacts with mRNA. Moreover, DEF6 is hypothesised to have two unconventional RNA binding domains; a feature which has also been described in the literature within proteins that catalyse glycolysis. DEF6 is also shown to be in close proximity to PABP and eIF4E, both of which are translation factors, as well as active translation in resting Jurkat T cells and the immunological synapse. Furthermore, endogenous DEF6 co-localises with 4E-T, a P-body marker which is involved with miRNA mediated decay, in resting and stressed Jurkat T cells. These data corroborate that of Hey et al. (2012) and suggests that DEF6 does indeed interact with P-bodies. Finally, translocation of DEF6 appears to occur in response to an extracellular signal alternative to the T cell receptor during T-T communication and that the translocation may occur in vesicle-like structures in close proximity to LFA-1. Consequently, these data identify a novel link between DEF6 and active translation as well as mRNA turnover and that the extracellular signal required for this spatial response is not antigen presenting cell specific but rather a response to LFA-1 stimulation.
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Chen, Xinchun. "Effective Combination of Syngeneic HCT with CRCL Vaccination to Treat BCR-ABL+ Leukemia and CD4+CD25+FoxP3+ Regulatory T Cells Suppress Mycobacterium Tuberculosis Immunity in Patients with Active Disease." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/305143.
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Chronic myelogenous leukemia (CML) is a clonal hematopoetic stem cell disorder characterized by proliferation of cells expressing BCR-ABL fusion protein. In the BCR-ABL+ leukemia murine model, 12B1, we explored the therapeutic applicability of chaperone-rich cell lysate (CRCL) in the context of syngeneic hematopoietic cell transplantation (HCT) to treat pre-existing leukemia. Our results demonstrate that tumor growth is significantly delayed in mice receiving syngeneic HCT from 12B1 tumor CRCL immunized donors compared to animals receiving HCT from non-immunized donors. CRCL immunization post-immune HCT further hindered tumor growth when compared to immune HCT without post-transplant vaccination. The magnitude of the immune response was consistent with the anti-tumor effects observed in vivo. We also demonstrated that cured mice had developed long-term tumor specific immunity against 12B1 tumor cells. In addition, we documented that both T cells and NK cells contributed to the anti-tumor effect of CRCL vaccination as depletion of either subset hampered tumor growth delay. Thus, our results suggest that CRCL represents a promising vaccine capable of generating specific immune responses. This anti-tumor immunity can be effectively transferred to a host via HCT and further enhanced post-HCT with additional tumor CRCL immunizations.CD4+CD25+ regulatory T cells (Treg) play a central role in the prevention of autoimmunity and in the control of immune responses by down-regulating the function of effector CD4+ or CD8+ T cells. The role of Treg in Mycobacterium tuberculosis infection and persistence is inadequately documented. Therefore, the current study was designed to determine whether CD4+CD25+ FoxP3+ regulatory T cells may modulate immunity against human tuberculosis (TB). Ourresults indicate that the number of CD4+CD25+FoxP3+ Treg increases in the blood or at the site of infection in active TB patients. The frequency of CD4+CD25+FoxP3+ Treg in pleural fluid inversely correlates with local MTB-specific immunity(p<0.002). These CD4+CD25+FoxP3+ T lymphocytes isolated from the blood and pleural fluid are capable of suppressing MTB-specific IFN-γ and IL-10 production in TB patients. Therefore, CD4+CD25+FoxP3+ Treg expanded in TB patients suppress Mycobacterium tuberculosis immunity and may therefore contribute to the pathogenesis of human TB.
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Colin-York, Huw. "Investigating the active role of mechanical force during T-cell activation." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:0b35bf22-f37f-4286-872d-ea174be82c77.
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The role of mechanical force has gained increasing interest in the field of cell biology owing to the realisation that cells are continually subject to stresses and strains induced by the cellular environment. Cells are known to be able to sense and react to forces imposed on them by their local environment as well as being able to directly impart force during motility, adhesion and cell division. This is also true for cells of the adaptive immune system, specifically during the intimate cell-cell interaction occurring between the T-cell and Antigen Presenting Cell (APC), known as the Immunological Synapse (IS). This highly selective process by which a T cell is able to bind, recognise and react to only foreign antigens has been the focus of intense study due to its crucial importance in the adaptive immune response. The actin cytoskeleton is known to play an essential role in the formation and maintenance of the IS, but questions remain regarding the influence of forces generated by actin during this process. With the aim of measuring mechanical force generated at the IS, we present a novel method combining the super resolution imaging technique, Stimulated Emission Depletion (STED) microscopy and Traction Force Microscopy (TFM). Using the tunable kinetics of the 1G4 Jurkat T-cell system in combination with high spatial and temporal resolution microscopy we demonstrate that actin dynamics at the IS is antigen dependent and show by TFM that force generation occurs on two distinct time scales during activation, mediated by the actin cytoskeleton. Together, the results highlight the intimate links between the dynamics of the actin cytoskeleton, force generation and the antigen response of T cells during activation.
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Müller, Henrik. "Characterization of the cytokine profile in adults with latent and active tuberculosis from a high endemic country." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16317.
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Charakterisierung des Zytokinprofils in Erwachsenen mit einer latenten oder aktiven Tuberkulose in einem hoch endemischen Gebiet Die Tuberkulose (TB) stellt mit rund 2 Milliarden Infizierten weltweit ein globales gesundheitliches Problem dar. Während die große Mehrheit der infizierten Personen in der Lage sind die Krankheit zu kontrollieren, entwickelt sich bei ungefähr 10 % die aktive Form der TB aus. Der zugrunde liegende immunologische Prozess für diese Verteilung ist bis heute nicht bekannt und im Fokus dieser Arbeit. Das adaptive Immunsystem spielt eine entscheidende Rolle in der Immunabwehr gegen Mycobacterium tuberculosis (M. tuberculosis), dem Erreger der TB. Hierbei sind besonders CD4+ T-Zellen für die erfolgreiche Eingrenzung der Erkrankung verantwortlich. Im Vorfeld konnte bereits mehrmals eine Assoziation zwischen polyfunktionalen CD4+ T-Zellen und einem Schutz gegen verschiedenste Krankheitserreger gezeigt werden. Im Rahmen dieser Doktorarbeit wird versucht die Frage zu beantworten, ob eine erhöhte Frequenz von polyfunktionalen CD4+ T-Zellen auch gegen die Ausbildung einer aktiven TB schützen kann. Zur Bearbeitung dieser Fragestellung wurde das TH1 Zytokinprofil von Patienten mit aktiver TB untersucht und mit dem von gesunden latent infizierten Probanden (LTBI) verglichen. Desweiteren wurden die TB Patienten während der antimikrobiellen Therapie begleitet um Änderungen im Zytokinprofil von CD4+ T-Zellen beobachten zu können. Im Rahmen dieser Arbeit wurde zum ersten Mal die simultane Expression der vier TH1 Zytokine IFNg, TNFa, IL-2 und GM-CSF mit Hilfe der multifarben Durchflusszytometrie untersucht. Nach antigenspezifischer Stimulation konnten sowohl in unbehandelten und behandelten Patienten mit aktiver TB ein großer Anteil an multifunktionale Gedächtnis-T-Zellen nachgewiesen werden, die alle vier Zytokine gleichzeitig exprimierten. Bemerkenswerterweise konnte diese Population ebenfalls in LTBI gezeigt werden. Nach den ersten zwei Monaten der Therapie war der Anteil an multifunktionalen T-Zellen signifikant erhöht welches auf einen positiven Einfluss dieser Zellen auf die Behandlung hinweist. Um detaillierte Information über das Expressionspotential von CD4+ T-Zellen zu gewinnen wurden PBMCs mit einem Superantigen inkubiert. Hierbei unterschied sich das Zytokinprofil zwischen den beiden Studiengruppen signifikant und veränderte sich ebenfalls unter Therapie. Während die Expression von IFNg in TB Patienten niedriger war als in LTBI, war die Frequenz von TNFa, IL-2 und GM-CSF-positiver CD4+ T-Zellen signifikant höher in Patienten mit aktiver TB. Zusammenfassend ist zu sagen, dass sowohl in TB Patienten vor und nach Therapie, als auch in LTBI, multifunktionale CD4+ T-Zellen nachgewiesen werden können. Ein Unterschied in der Frequenz konnte dabei nicht festgestellt werden. Daher kann ein Zusammenhang zwischen der Existenz von multifunktionellen CD4+ T-Zellen und einem Schutz gegen eine mögliche Reaktivierung von der latenten zu der aktiven TB nicht beschrieben werden.<br>Characterization of the cytokine profile in adults with latent and active tuberculosis from a high endemic country Tuberculosis (TB) is a global health problem with ~2 billion infected people worldwide. The vast majority of infected individuals is able to control TB, while only ~10% develop active disease. The immunologic correlates determining the protection against reactivation of the latent form of active TB remain elusive. The adaptive immune system plays an important role in the response against Mycobacterium tuberculosis (M. tuberculosis), especially CD4+ T cells are crucial for efficient containment of the pathogen. Since polyfunctional CD4+ T cells have been associated with protection against various pathogens, the question was raised if higher frequencies of polyfunctional CD4+ T cells can be linked to protection against reactivation of active TB. To address this the TH1 T cell cytokine profile of active TB patients was analyzed and compared with healthy latently infected individuals (LTBI). Furthermore TB patients were followed up under anti-microbial therapy to monitor changes in the cytokine pattern expressed by CD4+ T cells. Hereby, for the first time, the simultaneous expression of four TH1 cytokines, IFNg, TNFa, IL-2 and GM-CSF, was investigated using multi color flow cytometry. After antigen-specific stimulation multifunctional memory T cells (CD45RO+) co-expressing IFNg, TNFa, IL-2 and GM-CSF were strongly represented in both treated and untreated TB patients. Interestingly, this proportion of polyfunctional memory T cells was also found in LTBI. After the first two months of drug treatment the proportion of antigen-specific polyfunctional T cells was significantly increased, indicating a positive impact of these cells during therapy. To gain detailed information about the potential of CD4+ T cells to produce cytokines we incubated PBMCs with a superantigen. In this case the profile was significantly different between these two groups and it changed during therapy. While the expression of IFNg was significantly lower in CD4+ T cell of TB patients in comparison to LTBI, the expression of TNFa, IL2 and GM-CSF showed significant higher frequencies in memory T cells of TB patients. To conclude, upon antigen stimulation, polyfunctional memory T cells are found in TB patients pre- and post therapy as well as in LTBI. A difference in the frequency between active TB patients and LTBI could not be detected and therefore a correlation with protection against reactivation from the latent to the active form of TB cannot be drawn.
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McGregor, Reuben Hendrik Cameron. "Immunoregulatory effects of vitamin D and its mechanism of action in CD4+ T cells." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/immunoregulatory-effects-ofvitamin-d-and-its-mechanism-of-action-in-cd4-t-cells(c5b983f9-2a27-48ce-b1a6-89569416a82b).html.
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Vitamin D (VitD) deficiency has been implicated in the pathogenesis of multiple diseases including chronic kidney disease (CKD). VitD has direct effects on most cells in the innate and adaptive immune system including; CD4+ T cells and dendritic cells (DCs) both of which express the vitamin D receptor (VDR). This thesis, divided into two distinct parts, dissects the effects of: a) in vivo repletion of VitD in a placebo controlled, double blinded clinical trial in CKD patients. Here we hypothesised that repletion with cholecalciferol in VitD insufficient/deficient adult patients would ameliorate systemic inflammation. And the effects of b) VitD treatment of CD4+ T cells in vitro using multiple techniques to delineate the mechanisms influencing cytokine regulation. Here we hypothesised that VitD treatment of CD4+ T cells would, through binding of liganded VDR, lead to epigenetic modifications affecting genes involved in the regulation of cytokine production. In vivo we show that VitD repletion in VitD-deficient and insufficient patients with early stage CKD has immunoregulatory effects on circulating myeloid DCs by reducing expression of HLA-DR (a marker of mature DC phenotype). In vitro we identify a novel signaling pathway in CD4+ T cells, induced by VitD. The hallmark effect of VitD on CD4+ T cells was the induction of an immunoregulatory phenotype characterized by inhibited Th1 and Th17 cytokines and induction of the antiinflammatory cytokine IL-10, a process we show to be regulated by induction of IL-6 and subsequent STAT3 signalling. We further show that these processes are genetically regulated by histone modifications driven by liganded VDR, both at putative enhancer and promoter sites. These findings, most notably, have implications for dysregulated immunoregulation in the setting of inflammatory skin diseases and the development of novel therapeutics for the treatment of these conditions.
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Ha, Hong Clinical School St Vincent's Hospital Faculty of Medicine UNSW. "Role of T cells and cytokines in the induction of tolerance to renal tubular antigen in active Heymann nephritis." Awarded by:University of New South Wales. Clinical School - St Vincent's Hospital, 2007. http://handle.unsw.edu.au/1959.4/40871.
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Idiopathic Membranous nephropathy (MN) is a common cause of nephrotic syndrome in humans, and many patients progress to end-stage kidney disease. The best available animal model of MN is active Heymann nephritis (HN) in which rats are immunized with renal tubular antigen (RTA) in complete Freund's adjuvant (CFA). Rats develop heavy proteinuria, a key measure of glomerular damage, and the disease is histologically identical to human MN. It has been thought that HN is mediated by antibody-based mechanisms. More recent evidence demonstrates a critical role for cytotoxic T cells. This thesis aims to further examine the role of T cell responses in active HN. First, the effect of the anti-CD3 monocIonal antibody (mAb) G4.18 was investigated. Anti-CD3 given 4 weeks after immunization prevented the development of proteinuria, delayed anti-RTA antibody responses, and reduced glomerular infiltration of CD8+ T cells and macrophages, but did not affect glomerular deposition of IgG or complement. Increased mRNA expression of the Th2 cytokines IL-4 and IL-5 was detected in draining lymph nodes. These findings suggest that immune deviation to a Th2 response reduces glomerular injury in HN. Second, the role of CD4+ T cells in immune tolerance was examined. Rats were given RTA in incomplete Freund's adjnvant (lFA) to induce tolerance to RTA, and three weeks later were immunized with RTA in CFA. Anti-CD4 mAb therapy at the time of RTA1IFA treatment had no effect on subsequent proteinuria or anti-RTA autibodies. Third, the role of IL-4 in this model of immune tolerance was examined. Anti-IL-4 mAb therapy blocked the induction of tolerance, and led to the development of proteinuria. Finally, the effect of treatment with IL-4 and IL-5 was examined. Treatment with these cytokines separately or together after immunization blocked the development of proteinuria, without a consistent effect on anti-RTA antibodies. These results demonstrate a central role for T cell regulation in HN, and show that immune deviation to a Th2 response is protective against glomerular injury. The findings may have implications in the future for focused therapeutic intervention in human idiopathic MN.
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Schuck, Sebastian D. "Mycobacterium tuberculosis-specific T-cell responses in latent infection and active disease." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/15916.
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Adaptive Immunantworten gegen Mycobacterium tuberculosis (M. tuberculosis) sind von entscheidender Bedeutung für die effektive Eindämmung des Erregers sowie den Schutz vor einer erneuten, sekundären Tuberkulose (TB). Obwohl Schlüsselfaktoren wie die Th1 Zytokine IFN-gamma und TNF-alpha bekannt sind, blieben Bemühungen zur Identifizierung eindeutiger immunologischer Parameter, welche ausschlaggebend für den Krankheitsverlauf sind, bislang erfolglos. Ein besseres Verständnis der zugrunde liegenden Immunprozesse sowie die Identifikation projektiver Biomarker für TB sind zentrale Ziele dieser Arbeit. Zur Bearbeitung dieser Fragestellungen wurden adaptive Immunantworten gegen M. tuberculosis in gesunden Probanden mit LTBI und Patienten mit aktiver TB analysiert. Hierfür wurde die Erkennung unterschiedlicher Proteine des Erregers durch die Messung IFN-gamma exprimierender CD4+ CD45RO+ Gedächtnis T Zellen untersucht. Eine Besonderheit war die Einbeziehung sogenannter Latenz-assoziierter Proteine, welche in Zusammenhang mit Dormanz und Reaktivierung des Bakteriums stehen. 7 Tage in vitro Inkubation in Verbindung mit einer zweimaligen Restimulation belegten eine spezifische Erkennung durch CD4+ CD45RO+ T Zellen für die Mehrheit der getesteten Proteine bei Spendern mit LTBI. Der darauf folgende Vergleich zwischen Patienten mit aktiver TB und Personen mit LTBI zeigte signifikant höhere T Zell Antworten für 7 der 35 M. tuberculosis Proteine während LTBI. Bemerkenswerterweise konnten spezifische T Zellen für eines der Protein, nämlich Rv3407, ausschließlich während LTBI gemessen werden und nicht bei Patienten mit aktiver TB. Diskriminanz Analysen zeigten, dass eine Unterscheidung zwischen LTBI und TB Patienten basierend auf T Zell Antwort gegen ausgewählte Latenz-assoziierte Antigene mit einer Genauigkeit von 82% möglich ist. Erneut erwies sich Rv3407 als der mit Abstand bedeutendste Faktor innerhalb der ausgewählten M. tuberculosis Proteine.<br>Adaptive immune responses to Mycobacterium tuberculosis (M. tuberculosis) are crucial for an efficient containment of the pathogen and protection against secondary tuberculosis (TB). Although key mediators like the Th1 cytokines IFN-gamma and TNF-alpha released by M. tuberculosis-specific T cells are known, the immunological correlates determining the outcome of infection remain elusive. A better understanding of the underlying immune processes and the identification of protective biomarkers for TB are central aims of this thesis. To address these topics adaptive immune responses to M. tuberculosis were analyzed in healthy LTBI and patients with active pulmonary TB. The recognition of M. tuberculosis derived antigens was studied by measuring the expression of IFN-gamma in CD4+ CD45RO+ memory T cells. A special hallmark was the inclusion of latency proteins associated with dormancy, reactivation and resuscitation of the pathogen. Seven days in vitro incubation of PBMC and two rounds of restimulation followed by FACS analysis revealed T cell mediated recognition of the majority of tested latency-associated proteins in donors with LTBI. Comparison between active TB and LTBI documented significantly higher T-cell responses against 7 of 35 tested M. tuberculosis latency-associated antigens in LTBI. Notably, T cells specific for one M. tuberculosis antigen, namely Rv3407, were exclusively detected in the subgroup of LTBI. Discrimination analysis revealed that the T-cell response against selected antigens with our novel assay is capable of distinguishing TB patients and LTBI with 82% accuracy using cross-validation. Again Rv3407 was by far the most influential component present in this cluster. Peptide pool stimulation in a similar fashion identified single distinct candidate epitopes within Rv3407 in four LTBI.
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Bergström, Ida. "Pro- and anti-inflammatory actions in coronary artery disease : with focus on CD56+ T cells and Annexin A1." Doctoral thesis, Linköpings universitet, Avdelningen för kardiovaskulär medicin, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-114123.
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¨The atherosclerotic process is considered to be driven by an imbalance between proand anti-inflammatory actions. Still, the inflammatory state in patients with coronary artery disease (CAD) remains to be clarified. Annexin A1 (AnxA1) is a glucocorticoidinduced protein which may have a key role in the anti-inflammatory response as a mediator of glucocorticoid effects. The general aim of this thesis was to deepen the knowledge of pro- and antiinflammatory mechanisms in CAD via phenotypic assessments of immune cell subsets, in particular CD56+ T cells, and exploration of AnxA1. The long-term goal is to reveal basic mechanisms that will lead to the development of biomarkers, which may be used for individualized treatment and monitoring. The AnxA1 protein was constitutively expressed in both neutrophils and peripheral blood mononuclear cells (PBMCs). However, it varied considerably across PBMC subsets, being most abundantly expressed in monocytes. The AnxA1 expression was also higher in CD56+ T cells than in CD56- T cells. The expression of total AnxA1 protein in neutrophils was higher in patients with stable angina (SA) compared with controls. However, this was not accompanied by altered neutrophil activation status. Instead, the neutrophils from patients exhibited an enhanced anti-inflammatory response to exogenous AnxA1, emphasizing the potential of AnxA1 as an inhibitor of neutrophil activity. Only patients with acute coronary syndrome (ACS) showed an increase in cell surface-associated AnxA1. CAD patients, independent of clinical presentation, had increased proportions of CD56+ T cells compared with controls, a phenomenon likely to represent immunological aging. The CD56+ T cells were found to exhibit a distinct proinflammatory phenotype compared with CD56- T cells. In all T cell subsets, the expression of cell surface-associated AnxA1 was significantly increased in ACS patients, while it tended to be increased in post-ACS patients. In addition, dexamethasone clearly inhibited activation of CD56+ T cells in in vitro assays, whereas AnxA1 did not. The findings highlight the need to clarify whether the role of AnxA1 is different in T cells than in innate immune cells. In PBMCs, the mRNA levels of AnxA1 were increased in CAD patients, particularly in ACS patients. Correspondingly, the monocytes in ACS patients exhibited increased AnxA1 protein levels, both totally and on the cell surface. However, only cell surface-associated AnxA1 in monocytes correlated with the glucocorticoid sensitivity of PBMCs ex vivo. We propose the expression of cell surfaceassociated AnxA1 to be a promising candidate marker of glucocorticoid sensitivity, which needs further investigations in larger cohorts and intervention trials. Furthermore, the fact that PBMCs in post-ACS patients exhibited pro-inflammatory activity but no increase in cell surface-associated AnxA1 allow us to speculate that the glucocorticoid action and/or availability might be insufficient in these patients.
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Shannon, Michael James. "Integrin nano-adhesions, the molecular clutch and actin dynamics in high speed T cell migration." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/integrin-nanoadhesions-the-molecular-clutch-and-actin-dynamics-in-high-speed-t-cell-migration(284b8c39-f80c-42ac-8135-0b8afeeb5eb3).html.
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T cells navigate the body using constant actin flow, which transiently engages with a spatially and mechanically controlled ‘molecular clutch’ to produce torque and forward cell movement. The clutch is composed of affinity regulated integrin, actin linkers and phospho-regulators, modulated on the nanoscale as T cells move through blood vessels, tissues and lymph nodes. Cells with a point mutation in a gene linked to integrin signalling (PTPN22) exhibit increased adhesion and migration, and in humans the same mutation predisposes for seven different autoimmune diseases. Here, super resolution localisation microscopy (SLM) in 2D and 3D is used to investigate nano-clustering behaviour in primary effector T cells, while live-TIRF microscopy is used to measure actin flow and engagement. Analysis tools that allow for precise interrogation of clustering in pointillist SLM data and flow/engagement in intensity based TIRF data were developed concomitantly. Using these tools, it is apparent that integrin based “nano-adhesions” adopt regionally specific nanoclustering patterns upon cell migration, becoming smaller and denser in the focal zone/lamella as compared to the leading edge/lamellipodia. Nano-adhesion re-organisation is coupled to > 70% cortical actin engagement, with a degree of slippage where retrograde flow speed is always greater than cell speed. T cell migration can be slowed by use of cations or actin inhibitors, or sped by dosing with chemokines or deleting PTPN22. Upon migration speed increase, integrin nano-adhesions become larger in the cell membrane and reduce their engagement with actin. PTPN22 deficient cells also display an increase in the nanoscale colocalization of LFA-1 with pY397 FAK and pY416 Src family kinases, which occur in adhesions smaller than nascent adhesions in non-leukocytes. The local control of integrin LFA-1 nano-adhesions in migrating T cells is a new area of research that will improve our base framework for understanding immune cell migration, which may contribute to better understanding of migration defects that lead to autoimmune disease.
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Tonon, Sandrine. "La toxine de Bordetella pertussis active les cellules dendritiques et les lymphocytes T CD4 naïfs chez l'homme." Doctoral thesis, Universite Libre de Bruxelles, 2006. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210749.
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La toxine de pertussis (PTX) est une A-B protéine considérée comme l’un des principaux facteurs de virulence de Bordetella pertussis, l’agent bactérien responsable de la coqueluche. Aujourd’hui, cette maladie représente encore un réel danger pour les nouveaux-nés et les<p>nourrissons non ou partiellement immunisés. Actuellement, la coqueluche provoque encore la<p>mort d’environ 350.000 individus par an. La toxicité de la PTX est liée à l’activité<p>enzymatique de sa sous-unité A capable d’inhiber les voies de signalisation associées aux<p>protéines Gi. La partie B, quant à elle, permet l’entrée de cette sous-unité A dans le<p>cytoplasme des cellules cibles en se liant spécifiquement à son ou ses récepteurs<p>membranaires toujours inconnus de nos jours.<p><p>Des études réalisées chez la souris et chez l’homme ont montré que les vaccins anticoquelucheux combinés à différents antigènes vaccinaux étaient capables de moduler<p>leurs réponses humorales spécifiques. Par ailleurs, la PTX est couramment qualifiée d’agent<p>immunostimulant. En effet, des modèles murins de vaccination permirent d’identifier des<p>propriétés adjuvantes de la PTX coadministrée avec des antigènes non relevants.<p><p>Le travail développé dans ce manuscrit étudie les effets de la PTX sur 2 types cellulaires<p>primordiaux sollicités lors d’une vaccination :la cellule dendritique (DC) et le lymphocyte T<p>CD4+ naïf.<p><p>Les DC sont les seules cellules présentatrices d’antigènes aptes à initier une réponse immune<p>primaire. Dans un premier temps, nous avons montré que la PTX était capable d’activer des<p>DC générées in vitro à partir de monocytes. En effet, elles acquièrent un phénotype mature<p>caractérisé par une augmentation de l’expression membranaire des molécules costimulatrices<p>et du CMH de classe II, démontrant un effet direct et spécifique de la PTX sur les DC<p>myéloïdes. Parallèlement, ces DC produisent du TNF-a, de l’IL-12p40 et de l’IL-12p70 et<p>activent NF-kappaB, un facteur de transcription essentiel au processus de maturation. Nous<p>avons obtenu des résultats similaires avec une toxine génétiquement modifiée qui est<p>enzymatiquement inactive. A partir de sang total incubé avec la PTX, nous avons par ailleurs<p>observé que les DC circulantes du nouveau-né étaient déficientes dans leur maturation et leur<p>sécrétion d’IL-12p70 comparées aux DC de l’adulte.<p><p>D’autre part, il a été décrit précédemment que la PTX exerçait des effets mitogènes sur les<p>lymphocytes T humains et murins. Cependant, le rôle qu’elle joue sur la population des<p>lymphocytes T CD4 naïfs reste peu connu. A l’issue de notre second travail, nous pouvons<p>dès lors affirmer que la PTX est également capable d’activer des lymphocytes T<p>CD4+CD45RA+ naïfs isolés à partir des cellules mononuclées du sang périphérique, et ce<p>indépendamment de son activité enzymatique. En effet, ces lymphocytes T CD4+ naïfs stimulés par la PTX prolifèrent, synthétisent des quantités non négligeables d'ARN messagers<p>codant pour l’IL-2 et le TNF-a, augmentent l’expression membranaire des molécules CD40L,<p>CD69 et CD25 et expriment la protéine Foxp3. Cette activation s’accompagne de la translocation nucléaire de NF-kappaB et NFAT. Parallèlement à l’adulte, la PTX active les lymphocytes T CD4 néonataux. Néanmoins, ceux-ci prolifèrent moins bien et expriment plus faiblement le CD40L à leur surface.<p><p>Enfin, la PTX induit la sécrétion de taux importants d’IFN-g par des T CD4+CD45RA+ naïfs<p>adultes mis en présence de DC autologues.<p><p>Nous terminerons en proposant l’hypothèse suivante :La PTX pourrait exercer ses propriétés<p>adjuvantes par l’intermédiaire de différents mécanismes comprenant notamment la maturation<p>des DC d’origine myéloïde et l’activation des lymphocytes T CD4+CD45RA+ naïfs. Ces 2 populations cellulaires sont en effet les principaux protagonistes impliqués dans la réponse<p>immune primaire.<br>Doctorat en sciences pharmaceutiques<br>info:eu-repo/semantics/nonPublished
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Del, Río Iñiguez Iratxe. "Intracellular vesicle traffic, immunological synapse and T cell activation. Modulation by Human Immunodeficiency Virus type 1 Rac1-Rab11-FIP3 regulatory hub coordinates vesicle traffic with actin remodeling and T cell activation Rab11-FIP3 regulation of Lck endosomal traffic controls TCR signal transduction." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS561.
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La formation et les fonctions de la synapse immunologique sont le résultat d’un processus de polarisation cellulaire du lymphocyte T. Ce processus dépend de l’action coordonnée du cytosquelette d’actine et de microtubules, et du trafic vésiculaire intracellulaire. Le récepteur T ainsi que des protéines impliquées dans sa signalisation intracellulaire sont associés à la membrane plasmique et à des compartiments vésiculaires endosomiaux, et circulent en continu entre ces deux localisations. Je montre dans cette thèse que la tyrosine kinase Lck et la GTPase Rac1 sont associés aux endosomes exprimant Rab11. Leur localisation intracellulaire et leurs fonctions dans la formation de la synapse immune, l’activation des lymphocytes T et les remaniements du cytosquelette d’actine dépendent de Rab11 et de son effecteur FIP3. Je me suis intéressée également à la protéine Nef du VIH-1, importante pour la réplication du virus et pour la pathogénèse associée au SIDA. Nef affecte le trafic endosomial, l’activation et le cytosquelette des lymphocytes T infectés. Nous avons mis en évidence que Nef concentre de façon spécifique des formes actives des protéines de signalisation dans le compartiment endosomial Rab11. Ceci conduit à une activation de certains gènes associés aux réponses précoces et tardives des lymphocytes T. Ce processus est contrecarré par la déplétion de FIP3, qui disperse le compartiment concentrant ces protéines. En conclusion, nos données révèlent de nouveaux mécanismes impliquant le trafic vésiculaire intracellulaire dans le contrôle de l’activation et du cytosquelette des lymphocytes T et leur détournement par le virus du SIDA<br>The immunological synapse is the result of a T cell polarization process that depends on the orchestrated action of the actin and microtubule cytoskeleton and of intracellular vesicle traffic. The T cell antigen receptor (TCR) and various components of its proximal signaling machinery are associated with the plasma membrane and vesicular endosomal compartments, continuously trafficking between the two locations. I show in this thesis that the subcellular localization and function of the tyrosine kinase Lck and the actin cytoskeleton regulator Rac1, depend on the Rab11 recycling endosomal compartment, and more in particular, on the Rab11 effector FIP3. Importantly, FIP3-dependent Lck and Rac1 localization controls early TCR signaling, intracellular calcium concentration, IL-2 gene expression and morphological events, like T cell spreading and synapse symmetry. Moreover, I investigated how the HIV-1 accessory protein Nef, which is crucial for virus replication in vivo and AIDS pathogenesis, specifically hijacks several active signaling molecules, concentrating them in the Rab11 endosomal compartment, and concomitantly inducing the upregulation of some early and late T cell activation genes. Interestingly, dispersion of this concentration by depleting Rab11-FIP3, counteracted Nef-induced gene expression upregulation. Therefore, by modifying their endosomal traffic, Nef hijacks signaling and actin cytoskeleton regulators to dually modulate their functional outputs. In conclusion, our data shed new light into the molecular mechanisms orchestrating endosomal traffic with T cell activation and cytoskeletal rearrangements, and their subversion during HIV-1 infection
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Okwor, Chisom Ifeoma Adaeze. "Understanding Immune Suppression in Patients with Chronic Hepatitis C Virus Infections." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41856.
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Hepatitis C Virus (HCV) is a small RNA virus that progresses to chronicity in 50-80% of infected individuals. Direct-acting antivirals (DAAs) are revolutionary treatments for HCV with 90-98% cure rates. However, over time, chronic HCV infections can result in advanced liver disease, including cirrhosis. Patients with advanced fibrosis experience a poor response to vaccination, recurrent infections and increased risk for hepatocellular carcinoma (HCC). These outcomes are, in part, a consequence of immune dysfunction. Increased inhibitory receptor and Galectin-9 (GAL-9) expression is a possible mechanism promoting lymphocyte dysfunction.
In this study, blood samples were collected from chronic HCV patients with different degrees of liver fibrosis. I conducted a 13-parameter flow stain on the peripheral blood mononuclear cells (PBMC) of these patients. Next, I measured the expression of inhibitory receptors (PD-1, CTLA-4, LAG-3, TIGIT and TIM-3) and GAL-9 on bulk T cell and NK cells of 15 chronic HCV patients with no to moderate fibrosis (F0-F2) and 15 with advanced fibrosis (F3-F4). To analyze receptor co-expression, I employed t-distributed stochastic neighbor embedding (t-SNE) analysis to dimensionally reduce the multi-parametric data.
Notably, I found that F3-F4 patients had higher frequencies of >3 inhibitory receptor co-expression on NK cells. Moreover, t-SNE analysis of bulk T cells revealed that F3-F4 patients manifest a higher frequency of cells in the clusters with CD25+TIGITmed-hi CD4+ T cells and PD-1medLAG-3med-hiGAL-9med-hi CD4+ T cells. t-SNE analysis of NK cells also showed that F3-F4 patients manifest a higher frequency of cells in the cluster with CD25+TIGITmed-hiTIM-3med-hi CD56Dim NK cells and CCR7+ PD-1medLAG-3med-hiGAL-9med-hi CD56Dim NK cells. Lastly, the frequency of cells in these clusters was found to positively correlate with patient’s extent of liver damage. In conclusion, I identified phenotypes of immune dysregulation that could explain the increased susceptibility to infection and HCC in chronic HCV patients with advanced fibrosis. These phenotypes could identify targets for combinatorial checkpoint blockade therapy to potentially improve immune function in these patients.
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Müller, Philipp. "Studies on the role of Coronin 1 and the actin cytoskeleton in T cell signaling and survival /." Basel : [s.n.], 2009. http://edoc.unibas.ch/diss/DissB_8908.
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Singh, Noopur. "Mechanism of action and recruitment of antigen-presenting cells in a mouse model of multiple sclerosis." Doctoral thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/68073.
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La sclérose en plaques (SEP) est largement acceptée comme étant une maladie auto-immune du système nerveux central (SNC) dirigée par les cellules T auto-réactives. Cette maladie est très répandue au Canada. L'encéphalomyélite auto-immune expérimentale (EAE) est le modèle animal le plus utilisé pour l’étude de la SEP. Malgré l’importance des cellules T dans cette pathologie, il est important de souligner que ce sont les cellules présentatrices d'antigènes (CPA) myéloïdes, et surtout les cellules dendritiques (CD), qui amorcent l’activation des cellules T auto-réactives dans les organes lymphoïdes secondaires ainsi que leur éventuelle réactivation dans le compartiment du SNC plus tard au cours de la maladie. Cependant, il existe une disparité dans l'identification des différentes sous-populations de CPA myéloïdes en raison de l'absence de marqueurs fiables et spécifiques, ce qui constitue une entrave dans le domaine de l'immunothérapie cellulaire. Par ailleurs, les mécanismes moléculaires responsables de la régulation du recrutement des CPA myéloïdes au niveau de la vasculature cérébrale suite à l'activation de l'endothélium du SNC sont encore mal connus. L'interleukine-6 (IL-6) est une cytokine pro-inflammatoire essentielle à la différenciation des lymphocytes TH17 auto-réactifs. Ces derniers sont des régulateurs clés de l'EAE et jouent un rôle important dans la SEP. Ainsi, le premier objectif de ma thèse était de démontrer que l'IL-6 joue un second rôle dans l'EAE en stimulant l'endothélium du SNC à exprimer les molécules nécessaires au recrutement des CPA myéloïdes. Nous démontrons que : (1) les cellules endothéliales du SNC expriment le récepteur de l’IL-6 (IL-6R) ; (2) l’ablation génétique de l’IL-6R spécifiquement dans l'endothélium atténue le recrutement des neutrophiles, des macrophages et des CDs, et prévient le développement de l'EAE ; et (3) l'IL-6 stimule les cellules endothéliales à produire CXCL1 et PTGS2, des protéines impliquées dans le recrutement et l'activation des cellules myéloïdes. Le deuxième objectif général de mon étude était d'obtenir une vue d'ensemble phénotypique et fonctionnelle des sous-populations de CD présentes pendant la phase initiale d'induction de l'EAE. À cette fin, nous avons utilisé la technologie de séquençage de l'ARN unicellulaire (scRNAseq) pour comparer la signature transcriptionnelle des cellules CD11c+ issues des nœuds lymphatiques au cours de la phase préclinique de l'EAE. Nous montrons que : (1) quatre grandes sous-populations de CD sont présentes, soit les CD115+ monocytaires (mDC), les SiglecH+ plasmacytoïdes (pDC), les XCR1+ conventionnelles de type 1 (cDC1) et les CCR7+ conventionnelles de type 2 (cDC2) ; (2) les cDC2, une sous-population spécifique de CPA, présentent des niveaux transcriptonnels élevés de cytokines pro-inflammatoires (IL-6, IL-12) et de marqueurs de maturation et de co-stimulation pour la présentation des antigènes (CD80, CD83, CD86, OX40L) ; (3) miR155, un microARN connu pour son rôle dans l'EAE, est principalement exprimé dans les cDC2 ; et (4) que l'enzyme D-aminoacide oxydase (Dao), qui produit du peroxyde d'hydrogène (H2O2) à partir d’acides aminés D, est régulée à la hausse dans les cDC2 des souris miR155-/- . En résumé, mon travail de thèse met l'accent sur le rôle critique des CPA myéloïdes lors des premiers événements précliniques de l'EAE et il suggère un nouveau rôle important de la signalisation classique de l'IL-6 dans le développement de l'EAE et le recrutement des leucocytes. Finalement, il identifie en outre des cibles et des biomarqueurs potentiels à des fins diagnostiques et thérapeutiques.<br>Multiple sclerosis (MS) is widely accepted as an autoreactive T cells driven autoimmune disorder of the central nervous system (CNS), highly prevalent in Canada. Experimental autoimmune encephalomyelitis (EAE) is the established animal model for studying MS. Antigen-presenting cells (APCs) of myeloid origin, most importantly, dendritic cells initiate the priming of autoreactive T cells in the secondary lymphoid organs, and their eventual reactivation in the CNS compartment later in the disease course. However, a disparity exists in identifying myeloid APCs subsets with accuracy due to absence of reliable and specific markers, causing a hindrance in the field of cellbased immunotherapy. In addition, more needs to be deciphered on the molecular mechanisms that regulate activation of CNS endothelium for recruitment of myeloid APCs. Interleukin-6 (IL-6) is a pro-inflammatory cytokine, essential for differentiation of self-reactive TH17 lymphocytes, which are key regulators of EAE and play an important role in MS. The first objective of my thesis was to demonstrate that IL-6 plays another role in EAE by stimulating the CNS endothelium to express molecules required for the recruitment of myeloid antigen-presenting cells. We show that: (1) endothelial cells in the CNS express IL-6 receptor (IL-6R); (2) genetic deletion of IL-6R specifically in the endothelium blocks neutrophils, macrophages and dendritic cells recruitment as well as EAE development; (3) ICAM1-expressing extravascular myeloid APCs are reduced in number during the pre-onset stage of EAE; and (4) IL-6 stimulates endothelial cells to produce CXCL1 and PTGS2, which are involved in recruitment and activation of myeloid cells. The second general objective of my study was to get a phenotypic and functional overview of DC subsets present during the initial induction phase of EAE. For that purpose, we used the single-cell RNA sequencing (scRNAseq) technology to compare the transcriptional signature of CD11c+ cells from lymph nodes during the pre-clinical phase of EAE. We show that: (1) four major subsets of DCs are present: CD115+ monocytic DC (mDC), SiglecH+ plasmacytoid DC (pDC), XCR1+ conventional DCs type-1 (cDC1) and CCR7+ conventional DCs type-2 (cDC2); (2) cDC2 exhibit elevated expression of pro-inflammatory cytokines (IL-6, IL-12), maturation marker (CD83) and costimulatory molecules for antigen presentation (CD80, CD86, OX40L); (3) miR155, a microRNA known to have a role in EAE, is predominantly expressed in cDC2; (4) the enzyme D-amino acid oxidase (Dao), that produces hydrogen peroxide (H2O2) from D-amino acids, is upregulated in cDC2 of miR155-/- mice. In summary, my thesis work emphasizes on the critical role of myeloid APCs during initial pre-clinical events of EAE. Moreover, it suggests additional important role of classical IL-6 signaling in EAE development and leukocyte recruitment. It further identifies potential targets and biomarkers for diagnostics and therapeutic purposes.
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Read, Simon. "The role of CD4'+' regulatory T cells in protection from inflammatory bowel disease : phenotype, ontogeny and mechanism of action." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365754.
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Sardar, Harjinder Singh. "Molecular Interactions of Arabinogalactan-Proteins (AGPs) in Tobacco Bright Yellow-2 Cultured Cells and Functional Identification of Four Classical AGPs in Arabidopsis." Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1187112623.
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Liu, Yuk-Fun. "Mechanisms of action of peptide immunotherapy for type 1 diabetes : characterising T-cells induced or modified by proinsulin C19-A3." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/mechanisms-of-action-of-peptide-immunotherapy-for-type-1-diabetes(4da69e4e-6a2b-4f55-bad3-5c95f5cda38f).html.
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Peptide immunotherapy (PIT) is a specific immunomodulatory treatment aiming to tip the balance from pro8inflammatory attack to restoration of immune tolerance. It has been successfully translated into clinical practice in the field of allergy, stimulating ongoing research in autoimmune diseases including type 1 diabetes. The safety and mechanistic effects of proinsulin C198A3 (PI C198A3), a HLA8DR4 restricted, naturally processed and presented peptide, was assessed through a multicentre placebo controlled double8blind clinical trial of 2 or 4 weekly intradermal doses of 10µg peptide for 6 months, with a 6 month follow8up period. Overall, treatment was well tolerated with no evidence of local or systemic hypersensitivity or disease acceleration. In some PIT8treated subjects there was retention of C8peptide. To address the question of whether and how PIT impacts upon immune function, over the 6 month treatment period, T cell receptor (TCR) clonotyping and gene expression analysis were performed on peptide8specific activated CD4 T8cells. TCR β8chain clonotyping revealed shared β8chain clonotypes between patients; however, these were not apparently linked to peptide immunotherapy. Gene expression changes were explored but no antigen8 specific changes related to treatment identified. This study concludes that peptide immunotherapy using PI C198A3 is a safe and well8 tolerated treatment in newly8diagnosed adults with type 1 diabetes; deployment of novel mechanistic studies to examine alterations in antigen8specific effector CD4 T cells do not reveal any linked changes in TCR or gene expression.
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Dinic, Jelena. "Plasma membrane order; the role of cholesterol and links to actin filaments." Doctoral thesis, Stockholms universitet, Wenner-Grens institut, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-62279.
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The connection between T cell activation, plasma membrane order and actin filament dynamics was the main focus of this study. Laurdan and di-4-ANEPPDHQ, membrane order sensing probes, were shown to report only on lipid packing rather than being influenced by the presence of membrane-inserted peptides justifying their use in membrane order studies. These dyes were used to follow plasma membrane order in live cells at 37°C. Disrupting actin filaments had a disordering effect while stabilizing actin filaments had an ordering effect on the plasma membrane, indicating there is a basal level of ordered domains in resting cells. Lowering PI(4,5)P2 levels decreased the proportion of ordered domains strongly suggesting that the connection of actin filaments to the plasma membrane is responsible for the maintaining the level of ordered membrane domains. Membrane blebs, which are detached from the underlying actin filaments, contained a low fraction of ordered domains. Aggregation of membrane components resulted in a higher proportion of ordered plasma membrane domains and an increase in cell peripheral actin polymerization. This strongly suggests that the attachment of actin filaments to the plasma membrane induces the formation of ordered domains. Limited cholesterol depletion with methyl-beta-cyclodextrin triggered peripheral actin polymerization. Cholesterol depleted cells showed an increase in plasma membrane order as a result of actin filament accumulation underneath the membrane. Moderate cholesterol depletion also induced membrane domain aggregation and activation of T cell signaling events. The T cell receptor (TCR) aggregation caused redistribution of domains resulting in TCR patches of higher order and the bulk membrane correspondingly depleted of ordered domains. This suggests the preexistence of small ordered membrane domains in resting T cells that aggregate upon cell activation. Increased actin polymerization at the TCR aggregation sites showed that actin polymerization is strongly correlated with the changes in the distribution of ordered domains. The distribution of the TCR in resting cells and its colocalization with actin filaments is cell cycle dependent. We conclude that actin filament attachment to the plasma membrane, which is regulated via PI(4,5)P2, plays a crucial role in the formation of ordered domains.<br>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: Manuscript.
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Brundula, Sodja Veronika. "Inhibiting T cell migration as a therapeutic strategy for Multiple Sclerosis, minocycline and its mechanisms of action." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/MQ55198.pdf.
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Huang, Kuan-Hsiang Gary. "The impact of host and therapy mediated selection on HIV-1 evolution." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:b49d0d79-75c9-4314-92ae-1f1789ac7d42.
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The Human immunodeficiency virus (HIV) pandemic has resulted in a heavy global disease burden, and clinically causes Acquired Immuno-Deficiency Syndrome (AIDS). The development of highly active antiretroviral therapy (HAART) has achieved remarkable control of the rapidly evolving HIV. However, HIV remains neither curable nor preventable by vaccine, and in the developing regions worst affected by HIV, HAART remains inaccessible to most patients. Furthermore, the change in both immunology and viral evolution during chronic HIV infection and its relation to AIDS pathogenesis remains unknown. Following the failure of recent HIV vaccines, it is believed that a better understanding of host-pathogen interaction is vital to advance therapeutic (vaccine and drug) design. In this thesis, I have performed an investigation of viral adaptation in response to different selection forces during advanced HIV infection and AIDS. The thesis first examined a case study that reveals the potential role of B cell-mediated neutralising antibody (NAb) in chronic HIV infection through the unexpected effect of B cell depletion agent, anti-CD20 (Rituximab). Here, longitudinal results have shown that viral load (VL), env gene diversity, and NAb sensitive strains increased during B cell and NAb depletion as a result of Rituximab administration, and reversed as B cells recovered. The study provides preliminary evidence to support the idea that NAb may be effective at suppressing HIV. The rest of the thesis focused on the cross-sectional cohort at Bloemfontein, South Africa (n=1491), a resource-limited region affected by the pandemic. Here, we used methods that include molecular and pretherapy drug resistance epidemiology, mathematical modelling, phylogenetically adjusted bioinformatics analysis and in vitro viral replication capacity (VRC) assay to study materials including cohort demography, plasma samples, CD4 cell count, VL, viral genetic sequences and host human leukocyte antigen (HLA) tissue types. Our analysis was further augmented by the additional data kindly contributed by our neighbouring Durban cohort collaborators (n=775), which also includes an IFN! ELISPOT assay that measures cytotoxic T lymphocyte (CTL) responses. Using the HIV pol sequencing data and phylogenetic analysis we confirmed that the local molecular epidemiology is similar to the circulating strains documented in the regional database. However, the pretherapy drug resistance mutation screening results have revealed an unexpected high incidence of drug-induced viral mutants in the AIDS patients with CD4 counts <100 cells/μl. According to mathematical modelling, this finding is attributable to additional sources of antiretroviral therapy exposure, which warrants public health caution. The investigation then focused on studying the changes in HLA class I mediated CTL selection and viral evolution as CD4 counts are reduced in AIDS. Interestingly we have noted evidence that suggest weakening CTL immune selection against gag during AIDS is associated with increased viral fitness (measured by VRC) and reversion of previous immune-escape mutations which conferred high fitness costs. In conclusion, this thesis compared different sources of host and drug mediated HIV selection and its implication for viral evolution. The identification of more bottleneck sites conferring high fitness costs to the selection of escape mutants is expected to be helpful in the design of future therapeutics (via vaccine, drug, immune therapy, or public health strategy). As we have learnt from the principle of combinational ARV, it would be desirable for a vaccine to select HIV at multiple sites of high escape-mutation fitness cost, hence offering protective effect.
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Winter, Sarah. "Identification and characterization of new genetic defects involved in Epstein-Barr virus immune response and T-cell proliferation Loss of RASGRP1 in humans impairs T-cell expansion leading to Epstein-Barr virus susceptibility RASGRP1 is a negative factor of EOMES expression in T cells in association with an exhausted phenotype IL-27RA deficiency in humans, a new cause of susceptibility to Epstein-Barr virus infection Association of bi-allelic loss-of-function mutations in PIK3CD and TNFRSF9 causes fatal chronic active Epstein-Barr virus infection with T-cell lymphoproliferation." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCB180.
Full textAbstract:
L'infection par le virus d'Epstein-Barr (EBV) touche plus de 90% de la population mondiale et est dans la majorité des cas asymptomatique dans l'enfance. Certains individus, souvent à l'adolescence, développent une primo-infection symptomatique appelée mononucléose infectieuse. L'EBV peut également entraîner chez des individus immunodéprimés des désordres lymphoprolifératifs, des lymphomes ou syndromes d'activation lymphohistiocytaire. Depuis une trentaine d'années plusieurs déficits immunitaires primitifs entraînant une susceptibilité particulière à l'infection par l'EBV ont été identifiés ; parmi ceux-ci figurent les déficits en SAP, XIAP, ITK, MAGT1, CTPS1, CD27 ou CD70. Leur caractérisation a permis de mettre en évidence de nouveaux mécanismes immunitaires impliqués dans la réponse anti-EBV. L'objectif de ce travail a donc été d'identifier de nouveaux défauts génétiques entraînant une susceptibilité particulière à l'infection par l'EBV. Au sein de deux familles consanguines, trois patients ont développé des lymphomes B liés à l'EBV ainsi que des épisodes de lymphoproliférations également liées à ce virus. Deux mutations homozygotes dans RASGRP1 entraînant un stop prématuré, A638GfsStoXp16 et S314X ont été respectivement identifiées par séquençage d'exome (WES) chez ces deux familles. Sur le plan immunologique ces patients sont caractérisés par une lymphopénie CD4+, un défaut de cellules T naïves, une accumulation de cellules T effectrices mémoires et une absence de cellules MAIT et iNKT. RASGRP1 est une protéine de la famille des facteurs d'échange nucléotidiques fortement exprimée dans les lymphocytes T et NK. Elle active la petite protéine G Ras qui elle-même va activer la cascade des kinases Raf-MEK-ERK (ou cascade des MAP kinases). L'analyse des cellules du patient ou de cellules de contrôles sains dans lesquelles l'expression de RASGRP1 a été inhibée par RNA interférents a permis de mettre en évidence le rôle fondamental de RASGRP1 dans la prolifération lymphocytaire T et l'expression de gènes impliqués dans cette prolifération tels que CTPS1, PCNA ou RECQL4. A l'inverse, RASGRP1 semble être un régulateur négatif du facteur de transcription EOMES impliqué dans la différenciation des lymphocytes T. EOMES est retrouvé surexprimé dans les lymphocytes T en l'absence de RASGRP1, pouvant expliquer le phénotype effecteur mémoire et sénescent des lymphocytes des patients déficients en RASGRP1. Au sein d'une autre famille consanguine, chez deux patients ayant développé une primo-infection à l'EBV symptomatique, dont l'un a nécessité un traitement par anti-CD20 et corticoïdes, a été identifiée une mutation homozygote non-sens dans IL27RA entraînant un codon stop précoce (G96X) et une absence d'expression protéique dans les cellules T des patients. IL-27RA code pour la sous-unité alpha du récepteur à l'IL-27 impliqué dans la prolifération des lymphocytes T et le développement Th1 des lymphocytes CD4+ via la cascade des JAKs/STATs. Dans les lymphocytes T des patients, l'activation de la voie JAK/STAT par l'IL-27 est complètement abolie et l'IL-27 n'augmente pas leur prolifération en réponse à une stimulation anti-CD3 (au contraire des cellules contrôles issues de donneurs sains). De plus, un défaut fonctionnel de la voie Th1 est retrouvé chez un des deux patients. Ces résultats démontrent que la voie dépendante de l'IL-27RA est déficiente chez ces deux patients et que ce défaut génétique rend vraisemblablement compte de leur immunodéficience. La description de ces deux nouveaux déficits immunitaires caractérisés par une susceptibilité à l'EBV a permis de confirmer le rôle fondamental dans l'étape de prolifération et d'expansion des lymphocytes T au cours de la réponse immune anti-EBV, mais également de mettre en évidence de nouveaux mécanismes et facteurs impliqués dans cette étape<br>Epstein-Barr virus (EBV) is a gamma-herpes virus that infects 90% of humans without any symptoms in most cases. Some individuals, mostly adolescents, can develop infectious mononucleosis. In immunocompromised individuals, EBV can lead to lymphoproliferative disorders, lymphomas or virus-associated hemophagocytic syndrome. In the past 30 years, several primary immunodeficiencies associated with a high risk to develop EBV-associated disorders have been identified, including SAP, XIAP, ITK, MAGT1, CTPS1, CD27 or CD70 deficiencies. Their characterization has highlighted specific pathways required for efficient immunity to EBV. The objective of this work was to identify new genetic defects associated to a peculiar susceptibility to EBV infection. In two consanguineous families 3 patients developed EBV-associated B cell lymphomas and other EBV-associated lymphoproliferative disorders. By while exome sequencing (WES) we identified two homozygous mutations in RASGRP1 leading to a premature stop codon (A638GfsX16 and S314X). Immunologically these patients presented with CD4+ lymphopenia, low number of naïve T cells and absence of MAIT and iNKT cells. RASGRP1 codes for a diacylglycerol-regulated exchange factor preferentially expressed in T and NK cells, which acts as an activator of the small G protein RAS and the downstream RAF-MEK-ERK kinases cascade (or MAP kinases pathway). Analysis of patients' T cells or control T cells in which RASGRP1 expression was downregulated by short-hairpin RNA technique has highlighted the crucial role of RASGRP1 in T cell proliferation and in the expression of genes known to be involved in cell proliferation or replication such as CTPS1, PCNA or RECQL4. Furthermore, RASGRP1 seems to be a negative regulator of the transcription factor EOMES involved in T cell differentiation. EOMES was found overexpressed in T cells in the absence of RASGRP1. This might explain the skewed effector-memory and exhausted phenotype observed in RASGRP1-deficient patients. In another large consanguineous family two patients developed symptomatic EBV primary infection requiring for one or them anti-CD20 and corticosteroids treatment. Homozygous nonsense mutation leading to a premature stop codon in IL-27RA (G96X) was identified by exome sequencing. No protein expression could be detected in patients' cells. IL-27RA codes for the subunit of IL-27 receptor involved T cell proliferation and Th1 CD4+ development through JAKs/STATs pathway. Stimulation of patients' T cells with IL-27 led to absent JAK/STAT activation pathway and did not enhance their proliferation after anti-CD3 stimulation (contrary to healthy control T cells). Furthermore, Th1 functional defect was found in one patient. These results demonstrate that IL-27RA pathway is deficient is these two patients and that this genetic defect causes their immunodeficiency. Characterization of these two new primary immunodeficiencies associated with a high susceptibility to EBV infection has confirmed the crucial role of T cell proliferation and activation in EBV immune response but has also highlighted new pathways involved in T cell expansion
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Auma, Ann Winniefred Nangobi. "THE IMPACT OF DIRECT-ACTING ANTI-VIRAL THERAPY ON NAIVE CD4+ T CELL LYMPHOPENIA AND CELLULAR IMMUNE ACTIVATION IN HCV INFECTION AND HCV/HIV CO-INFECTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1625764728651756.
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Schuck, Sebastian D. [Verfasser], Hans-Dieter [Gutachter] Volk, Stefan [Gutachter] Kaufmann, and Florian [Gutachter] Kern. "Mycobacterium tuberculosis-specific T-cell responses in latent infection and active disease / Sebastian D. Schuck ; Gutachter: Hans-Dieter Volk, Stefan Kaufmann, Florian Kern." Berlin : Humboldt-Universität zu Berlin, 2009. http://d-nb.info/1208078542/34.
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Karches, Clara [Verfasser], and Sebastian [Akademischer Betreuer] Kobold. "Characterization of the influence of antibody valency on murine synthetic agonistic receptor-transduced T cell activation and action / Clara Karches ; Betreuer: Sebastian Kobold." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1202011861/34.
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Chebel, Amel. "Influence de la stimulation et de la sénescence réplicative des lymphocytes T sur le métabolisme des télomères." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10008.
Full textAbstract:
Les lymphocytes constituent un modèle original de cellules somatiques puisqu’ils sont capables de réactiver la télomérase lorsqu’ils sont stimulés. Nous avons montré que les lymphocytes, en culture prolongée et soumis à des stimulations itératives par la PHA, présentent une diminution progressive de l’activité télomérasique interrompue à chaque stimulation par une augmentation transitoire. Ces variations sont corrélées positivement aux variations de hTERT et de la longueur des télomères. Les foyers γ-H2AX et 53BP1 et leur localisation au niveau des télomères augmentent lors du vieillissement cellulaire. Nous montrons un dysfonctionnement des télomères au cours de la sénescence lymphocytaire in vitro résultant d’une érosion accrue des télomères et d’une diminution de l’expression des protéines qui les coiffent. Le mécanisme des variations précoces de l’expression de hTERT lors de l’activation lymphocytaire restaient à comprendre. Les conséquences du traitement des lymphocytes par différents immunosuppresseurs agissant tous de façon directe ou indirecte sur l’activation de NFAT suggéraient le rôle de NFAT dans la régulation transcriptionnelle de hTERT. Nous avons montré i) 5 éléments de réponse potentiels pour NFAT au niveau du promoteur de hTERT, ii) l’activation in vitro du promoteur de hTERT par NFAT essentiellement via un site consensus localisé dans le coeur du promoteur de hTERT en position -40 et une synergie fonctionnelle entre NFAT et SP1, iii) la liaison directe de NFAT sur le promoteur de hTERT via ce site consensus in vivo. Ainsi, NFAT1 régule la transcription de hTERT et est impliqué dans l’activation de la télomérase lors de la stimulation lymphocytaire<br>Lymphocytes are an example of somatic cells capable to induce telomerase activity when stimulated. We showed that lymphocytes, during long-term culture and repeated PHA stimulations, present a progressive drop in telomerase activity interrupted at each stimulation by a transitory increase. These variations are positively correlated with hTERT and telomere length variations. γ-H2AX and 53BP1 foci and their localization on telomeres increase with cell aging. We show a telomere dysfunction during in vitro lymphocyte senescence resulting from an excessive telomere shortening and a decrease in shelterin content. The mechanism involved in early variations of hTERT expression during lymphocyte activation remained to be understood. Consequences of lymphocyte treatment with different immunosuppressors, all acting directly or indirectly on NFAT activation, suggested a role for NFAT in the regulation of hTERT transcription. Five putative responsive elements for NFAT were identified in the hTERT promoter. We showed that NFAT activates in vitro the hTERT promoter mainly via a consensus site localized in the promoter core at position -40 and a functional synergy between NFAT and SP1. Furthermore, NFAT1 binds directly to the endogenous hTERT promoter via this consensus site in vivo. Thus, NFAT positively regulates the hTERT transcription and we propose its implication in telomerase activation during lymphocyte stimulation
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Moisan, Jean-Paul. "Etude et caracterisation de marqueurs genetiques specifiques du chromosome x humain (suivi de) etude des rearrangements du recepteur a l'antigene, sur des lymphocites t actives in vivo." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13231.
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Othmane, Omar. "Mecanisme d'action d'un immunomodulateur, le lf 1695 : effets in vitro et in vivo sur les lymphocytes t et sur l'autoimmunite." Limoges, 1986. http://www.theses.fr/1986LIMO0027.
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Yang, Hongbing. "Characterisation of CD8+T cell responses induced by therapeutic vaccination with HIV-1 clade A gag DNA- and recombinant modified vaccinia virus Ankara (MVA)-vectored vaccines in HIV-1 infected individuals recieving highly active antiretroviaral therapy." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442987.
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Rivas, Fabiola Vania. "Regulation of T cell activation by map kinases and the actin cytoskeleton /." 2003. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3097153.
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Mayne, Elizabeth Sarah. "The role of regulatory T cells in adults in South Africa with active tuberculosis." Thesis, 2010. http://hdl.handle.net/10539/7484.
Full textAbstract:
Thesis (M.Med.(Haematology)), Faculty of Health Sciences, University of the Witwatersrand, 2009<br>Introduction
Regulatory T cells (Tregs) are increasingly being recognized as key immunological
players in immunosuppression and have been seen to be permissive for certain infections.
Aim
This study aimed to elucidate the role that Tregs play in symptomatic infection with
Mycobacterium tuberculosis (TB), both with and without co-infection with human
immunodeficiency virus type 1 (HIV 1) by quantification of these cells at ex vivo. It was
then attempted to characterise the behaviour of FoxP3 positive cells in culture with
stimulation.
Methods
Peripheral blood mononuclear cells were purified from uninfected controls, patients with
active TB, patients with HIV infection and patients with HIV infection and active TB.
The frequencies of Tregs were assessed by flow cytometry at ex vivo and again after four
days of culture with stimulation with anti-CD3, Purified protein derivative, tetanus toxoid
and HIV peptide superpools (gag and nef). These frequencies were compared between
the four groups of patients. The ability of Tregs and effector T cells to proliferate was
also assessed. Interferon-γ secretion was used as a measure of effector T cell response to
stimulation.
vi
Results
Frequencies of Tregs were significantly reduced in patients with active TB as compared
with HIV infected patients and uninfected controls. Co-infected individuals showed a
broad range of frequencies which were not significantly different from controls. These
frequencies remained stable in culture with the exception of those individuals infected
with HIV who showed a decline in the frequency of those cells expressing FoxP3 over
the period. Cells expressing FoxP3 were not anergic and responded to stimulation. HIV
specific proteins, in addition, resulted in specific effects on the Tregs with a positive
interferon response to gag correlating with increased Treg frequencies and FoxP3
expression in CD4+ T cells correlated with the proliferative response of CD4+ T cells to
Nef in HIV infected individuals.
Conclusions
This study shows significant differences of frequencies of FoxP3 positive producing cells
in the peripheral blood at ex vivo in patients with active TB. The function of these cells in
this population is uncertain and further functional data and long-term clinical follow-up is
required. In addition, the frequencies of these cells remained constant over time and
showed proliferative response to stimuli (most notably CD3) suggesting that these cells
may be generated in the periphery.
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Palmer, Ellen Marie. "Regulation of human T helper cell differentiation by the combined action of accessory molecules and cytokines /." 2000. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9965134.
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Sedick, Qanita. "Analysis of gamma-delta T cells in black South African patients with active tuberculosis." Thesis, 2014. http://hdl.handle.net/10539/15477.
Full textAbstract:
A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree, Master of Medicine in Haematopathology. Johannesburg, 2014<br>Mycobacterium Tuberculosis is the leading cause of morbidity and mortality due to infectious diseases worldwide. South Africa has ~20% of the world’s HIV associated Tuberculosis and has the second largest reported numbers of multidrug resistant (MDR) Tuberculosis in the world.
Given the complexity of the mycobacterium and its ability to evade the immune system, there is a need for dissecting the immunological response to Tuberculosis including innate like lymphocytes such as gamma-delta T cells. Gamma-delta T cells are of particular relevance as they react to phospho-proteins of mycobacteria. Gamma-delta T cells can be divided into two subsets. Gamma-delta T cells using the Vdelta2 (VD2) segment as the variable segment in their T cell receptor and gamma-delta T cells using an alternative variable segment (non VD2 T cells).
We aimed to enumerate both subsets of gamma-delta T cells in the immunological response to Tuberculosis. We collected samples from three patient populations at the Charlotte Maxeke Johannesburg Academic Hospital for comparison: HIV positive patients with no evidence of Tuberculosis disease, HIV positive patients with active pulmonary Tuberculosis and a healthy control group. We used a nine colour flow cytometric panel to enumerate the frequency of gamma-delta T cells in these participant groups.
We found that the VD2 T cell subset was reduced in the HIV positive group and the dual HIV positive TB positive group compared with healthy controls, which mirrored the loss of CD4 T cells in these patients. Conversely, the non VD2 subset of gamma-delta T cells showed a statistically significant increased frequency in HIV positive patients and dual HIV positive TB positive patients compared to healthy controls. The frequency of gamma-delta T cells, expressed as a percentage of total T cells, was significantly increased in HIV positive patients and not non- significantly increased in the HIV positive TB positive groups compared to healthy controls.
This skewing of the gamma-delta T cell repertoire in HIV positive patients and HIV positive patients with active Tuberculosis may have specific immune implications. The mechanism of the loss of VD2 T cells in HIV and HIV associated Tuberculosis has not been elucidated. The loss of VD2 gamma-delta T cells in HIV and HIV associated Tuberculosis may underlie susceptibility to Tuberculosis disease.
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Koh, Byunghee. "Transcription factors and cis-acting elements in T helper cell cytokine expression." Diss., 2017. https://doi.org/10.7912/C2WD3S.
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Indiana University-Purdue University Indianapolis (IUPUI)<br>The immune system provides resistance to the myriad of pathogens in the
environment, but can also respond inappropriately causing allergic inflammation and
autoimmune disease. CD4+ T cells, which play a crucial role in adaptive immune system,
can be divided into several subsets based on their effector functions. T helper 9 (Th9)
cells, derived by the IL-4/STAT6 and TGF-β signaling pathways, produce IL-9 as a
hallmark cytokine, as well as IL-10. Through IL-9 production, Th9 cells protect against
parasite infection but are also involved in allergic inflammation and autoimmune diseases.
Transcription factors that promote Th9 development include STATs, PU.1, BATF, and
IRF4. In this study, we identify ETV5 as a factor that promotes IL-9 and IL-10 production
by binding to cis-acting regulatory elements in the respective genes. At the Il9 gene, ETV5
cooperates with PU.1 in regulating gene expression. At the Il10 gene, ETV5 facilitates
binding of other transcription factors to the locus. These studies and others suggested that
there may be additional cis-acting regulatory elements in the Il9 gene. We demonstrate
that a conserved noncoding sequence (CNS) located 25 kb upstream of the Il9
transcription start site, termed Il9 CNS-25, is critical for regulating Il9 expression in Th cell
subsets. Th9 cells derived from Il9 CNS-25 mutant (Il9 ΔCNS-25) mice produce significantly
less IL-9. Il9 CNS-25 promoted chromatin modifications at the promoter and accessibility
of the locus. Il9 ΔCNS-25 mice showed attenuated airway inflammation compared to control
mice. The Il9 CNS-25 region in mice is conserved with an IL9 CNS-18 region in the human
genome. We deleted CNS-18 in primary human Th9 cells and observed diminished IL-9
production. Thus, we have identified transcription factors that regulate multiple cytokines in Th cell lineages and have demonstrated that the Il9 CNS-25/IL9 CNS-18 elements are
respectively critical for Il9/IL9 gene expression.
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Zhang, Wen. "Identification and characterization of Zfp206, a transcription factor active in ES cells." 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=742452&T=F.
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JeBailey, Lellean. "The role of Rho GTPases in insulin-induced actin remodelling and GLUT4 mobilization in L6 muscle cells." 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=478876&T=F.
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Hauff, Cornelia. "Aspects of the mode of action of bispecific T cell engager (BiTE) antibodies." Doctoral thesis, 2009. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-48369.
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Bispecific T cell engager (BiTE) display a novel design among the class of bispecific antibodies and hold great promise to fight diverse cancers. BiTE molecules consist of two different binding entities derived from two human IgG antibodies connected by a short peptide linker. Their binding arms are directed against the CD3e chain of the T cell receptor on T cells and against an antigen that is specific for (e.g., CD19 for lymphoma in MT103) or over-expressed on (e.g., EpCAM for epithelial cancer in MT110) tumor cells. Without requirement for pre- or co-stimulation, BiTE molecules efficiently redirect CD3+ T cells towards tumor cells expressing the relevant target antigen. Only a BiTE molecule simultaneously bound to both tumor cell and T cell activates the T cell to exert its cytolytic function resulting in tumor cell death. In T cells stimulated with both BiTE and target cells, elevated levels of caspase activation and increased expression of cytotoxic and signaling proteins are observed. These include cytolytic proteins granzyme B and perforin, activation markers CD69 and CD25 and adhesion molecules CD2 and LFA-1. Activated T cells secrete the usual mix of cytokines, among them pro-inflammatory cytokines IFN-g and TNF-a. The membrane of tumor cells expressing the relevant target antigen is perforated during the attack of BiTE-stimulated effector cells as can be concluded from adenylate kinase release from the cytosol of tumor cells. Ca2+-chelator EGTA completely blocked BiTE-mediated activation of caspases and tumor cell lysis. As perforin is strictly Ca2+-dependent, a major role for this pore-forming protein is assumed for the elimination of tumor cells via BiTE-stimulated T cells. Granzyme B and caspases are main players in BiTE-mediated elimination of tumor cells. Inhibitors of granzyme B or caspases reduce or block, respectively the activation of caspases. However, other signals of apoptosis (cleavage of PARP and fragmentation of DNA) were only reduced by granzyme B inhibitor or caspase inhibitor. Most interestingly, the lytic capacity of BiTE molecules was not impaired by granzyme B inhibitor or caspase inhibitor. It seems that there is no requirement for granzyme B and caspases to be present simultaneously. Instead the data presented provide evidence that they can be replaced one at a time by related proteins. Pre-incubation of effector cells with the glucocorticoids dexamethasone or methylprednisolone resulted in markedly decreased secretion of cytokines by T cells yet only a small reduction in the expression of activation markers and adhesion molecules on T cells and specific lysis of tumor cells upon BiTE stimulation. Soluble factors secreted in an undirected manner by BiTE-stimulated T cells do not mediate tumor cell death by themselves. Bystander cells negative for the antigen that is recognized by the BiTE molecule will not be compromised by BiTE activity. The cytokine TGF-b reduced proliferation as well as granzyme B and perforin expression of BiTE-stimulated T cells. Redirected lysis by BiTE-activated T cells was also decreased under the influence of TGF-b, however lysis was still performed at a reasonable rate (72 % of target cells). TGF-b does not exert a deleterious effect on lytic potential of BiTE-stimulated T cells. The minimal anticipated biological effect level for the BiTE MT110 was determined for the entry of MT110 into phase I clinical studies. Experiments analyzing redirected lysis of tumor cells, expression of activation marker CD25 and cytokine release by T cells revealed a MABEL value of 50 pg/ml for MT110<br>Bispecific T cell engager stellen mit ihrem neuartigen Design eine eigene Gruppe unter den bispezifischen Antikörpern dar und zeigen sich vielversprechend im Kampf gegen unter-schiedliche Krebsarten. BiTE Moleküle bestehen aus zwei unterschiedlichen Bindungsstellen, die von zwei humanen IgG Antikörpern abgeleitet sind und durch einen kurzen Peptidlinker verbunden sind. Die Bindungsstellen sind gerichtet gegen die CD3e Kette des T-Zell-Rezeptors auf T-Zellen und gegen ein Antigen, das auf den Tumorzellen ausschließlich (CD19 bei Lymphomen in MT103) oder in erhöhtem Maße (EpCAM bei epithelialem Krebs in MT110) exprimiert wird. BiTE Moleküle richten CD3+ T-Zellen gegen Tumorzellen, die das relevante Zielantigen präsentieren. Dabei sind sie nicht auf Vor- oder Kostimulation angewiesen. Nur wenn das BiTE Molekül gleichzeitig an Tumorzelle und T-Zelle gebunden ist, aktiviert es die T-Zelle zytolytisch zu wirken und die Tumorzelle zu töten. T-Zellen, die mit BiTE und zugleich Targetzellen stimuliert wurden, zeigen erhöhte Raten von Caspaseaktivierung und vermehrte Expression von zytotoxischen und Signalproteinen. Diese beinhalten die zytolytischen Proteine Granzyme B und Perforin, die Aktivierungs-marker CD69 und CD25 und die Adhäsionsmoleküle CD2 und LFA-1. Aktivierte T-Zellen sezernieren die übliche Mischung an Zytokinen, darunter die pro-inflammatorischen Zytokine IFN-g und TNF-a. Die Freisetzung von Adenylatkinase aus dem Zytosol von Tumorzellen lässt darauf schließen, dass die Membran von Tumorzellen, die das relevante Zielantigen exprimieren, während dem Angriff von BiTE-stimulierten Effektorzellen durchlöchert wird. Der Ca2+ Chelator EGTA verhinderte die BiTE-vermittelte Aktivierung von Caspasen und Lyse von Tumorzellen vollständig. Da Perforin in Abhängigkeit von Ca2+ wirkt, wird für dieses porenbildende Protein eine entscheidende Rolle in der Beseitigung von Tumorzellen mittels BiTE-stimulierter T-Zellen angenommen. Granzyme B und Caspasen sind die Hauptakteure in der BiTE-vermittelten Beseitigung von Tumorzellen. Inhibitoren von Granzyme B oder den Caspasen vermindern bzw. hemmen die Aktivierung von Caspasen. Andere Apoptosesignale (PARP-Spaltung und DNA-Fragmentierung) werden von Granzyme B- oder Caspase-Inhibitoren jedoch lediglich reduziert. Bemerkenswerterweise wurde die lytische Kapazität von BiTE Molekülen durch einen Granzyme B- oder Caspase-Inhibitor nicht beeinträchtigt. Es scheint, dass keine Notwendigkeit für die gleichzeitige Anwesenheit von Granzyme B und Caspasen besteht. Stattdessen erbringen die vorgestellten Ergebnisse einen Hinweis dafür, dass diese Proteine jeweils einzeln durch verwandte Proteine ersetzt werden können. Präinkubation von Effektorzellen mit den Glucocorticoiden Dexamethason oder Methylpred-nisolon bewirkte eine deutlich verminderte Zytokinsekretion von T-Zellen, jedoch nur eine geringe Abnahme der Expression von Aktivierungsmarkern und Adhäsionsmolekülen auf T-Zellen und der spezifischen Lyse von Tumorzellen in Folge von BiTE-Stimulierung. Lösliche Faktoren, die von BiTE-stimulierten T-Zellen nicht zielgerichtet abgegeben werden, vermitteln keine Lyse von Tumorzellen. Zellen, die sich in der Nachbarschaft des Tumors befinden, aber das Antigen nicht exprimieren, das vom BiTE Moleküle erkannt wird, werden daher durch BiTE Aktivität nicht in Mitleidenschaft gezogen. Das Zytokin TGF-b verminderte die Proliferation von BiTE-stimulierten T-Zellen sowie deren Expression von Granzyme B und Perforin. Die gerichtete Lyse von BiTE-aktivierten T-Zellen war unter dem Einflusss von TGF-b ebenfalls vermindert. Trotzdem erreichten die Lysisraten Werte von 72 %. TGF-b übt keinen schädlichen Effekt auf das lytische Potential von BiTE-stimulierten T-Zellen aus. Die MT110-Konzentration, bei der der geringste biologische Effekt erwartet wird, wurde für den Eintritt von MT110 in klinische Studien der Phase I bestimmt. Auf Grundlage von Experimenten zur gerichteten Lyse von Tumorzellen, zur Expression des Aktivierungsmarker CD25 auf T-Zellen und zu Freisetzung von Zytokinen aus T-Zellen, ergab sich ein MABEL-Wert von 50 pg/ml für MT110
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Talaei, Nafiseh. "Abelson family kinases regulate actin cytoskeleton dynamics in immunological synapse formation and T cell migration." 2009. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=958041&T=F.
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Badour, Karen Elizabeth. "The Wiskott-Aldrich syndrome protein : forging a link between actin polymerization and T cell activation." 2005. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=232849&T=F.
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Nelson, Kimberlea Lynne. "Elucidation of the mode of action of the pore-forming toxin aerolysin on T lymphomas." Thesis, 2000. https://dspace.library.uvic.ca//handle/1828/9673.
Full textAbstract:
Aerolysin is a channel-forming protein toxin secreted by virulent Aeromonas species. The toxin binds to receptors on cells, is proteolytically activated, and then assembles into a heptameric oligomer, which inserts into the plasma membrane forming a functional channel, resulting in cell death. To further characterize these steps receptor identification, the effect of membrane domains on channel formation and the mode of cell death were investigated on T lymphomas. Screening of cell lysates for proaerolysin-binding proteins N-glycosidase and phosphatidylinositol specific phospholipase C treatment and/or purification of these proteins resulted in the identification of a group of glycosylphosphatidylinositol (GPI)-anchored proteins, which included contactin, Thy-1, and placental alkaline phosphatase. Liposomes were used to show that these proteins were receptors for aerolysin as those containing Thy1 or placental alkaline phosphatase in their membranes were at least 100-fold more sensitive to aerolysin than those without protein. Similarly, cells expressing GPI-anchored proteins were 10⁴-fold more sensitive to aerolysin than cells lacking them. This is likely the result of these proteins concentrating aerolysin on the cell surface and thus promoting oligomerization. The fact that these proteins can be localized to membrane domains known as rafts, which are enriched in sphingomyelin and cholesterol has the potential to affect oligomerization. To investigate this possibility erythrocytes and T lymphomas were treated with methyl-β-cyclodextrin, which destroys rafts by sequestering cholesterol. Raft disruption did not decrease the sensitivity of these cells to aerolysin. Similarly, aerolysin was no more active against liposomes containing placental alkaline phosphatase in raft domains than those in which the receptor was in non-raft domains. Thus raft domains do not promote channel formation by aerolysin. The mechanism of cell death was next investigated. At high toxin concentrations cell death was shown to proceed by necrosis, whereas at subnanomolar concentrations aerolysin triggers apoptosis. Using inactive aerolysin variants it was determined that apoptosis was not a result of binding to GPI-anchored proteins nor was it triggered by receptor clustering induced by oligomerization. Instead the formation of a small number of channels was shown to trigger apoptosis. Taken together these studies have helped to clarify the mode of action of aerolysin.<br>Graduate
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Föger, Niko [Verfasser]. "Costimulatory function of CD44 : acting in unison with the T cell receptor / vorgelegt von Niko Föger." 2002. http://d-nb.info/968343716/34.
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Master, Zubin. "Identification and characterization of the signaling mechanisms downstream of Dok-R that mediate cell migration and actin reorganization." 2004. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=94726&T=F.
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Schuck, Sebastian D. [Verfasser]. "Mycobacterium tuberculosis specific T-cell responses in latent infection and active disease / von Sebastian D. Schuck." 2009. http://d-nb.info/994897367/34.
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Hauff, Cornelia [Verfasser]. "Aspects of the mode of action of bispecific T cell engager (BiTE) antibodies / vorgelegt von Cornelia Hauff." 2009. http://d-nb.info/1003240143/34.
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Momin, Mohamed. "Atomistic Insights into Binding Pocket Dynamics and Regulation in the Interleukin-2 T-Cell Kinase SH2 Domain." 2017. http://scholarworks.gsu.edu/chemistry_theses/102.
Full textAbstract:
Although the regulation of proteins functions by allosteric interactions has been identified in many subcellular processes, long-range conformational changes in proteins are also known to be induced by molecular switches. A molecular switch based on the cis-trans isomerization of a peptidyl-prolyl bond is capable of inducing a conformational change directly to the protein backbone, which is then propagated throughout the system. However, these switches are elusive and difficult to identify due to their intrinsic dynamics in the biomolecules where they are found. Herein, we explore the conformational dynamics and free energy landscape of the SH2 domain of Interleukin-2-inducible T-Cell Kinase (ITK) to fully understand the conformational coupling between the distal cis-trans molecular switch, and its phosphotyrosine binding pocket. Using multiple microsecond-long all-atom molecular dynamics simulations in explicit water for over a total of 60 μs, we show that the cis-trans isomerization of the Asn286-Pro287 peptidyl-prolyl bond is directly correlated to the dynamics of the phosphotyrosine binding pocket, in agreement with previous NMR studies. While the cis state is localized to a single free energy basin and less dynamic, the trans state samples two distinct conformations of its binding pocket – one that recognizes the phosphotyrosine motif, and another that is similar the cis state. These results provide an atomic-level description of a less-well understood allosteric regulation by a peptidyl-prolyl cis-trans molecular switch that could aid in the understanding of normal and aberrant sub-cellular process and the identification of these elusive molecular switches in other proteins.