Dissertations / Theses on the topic 'Low t cell symptoms'

Abstract Cutaneous T cell lymphoma (CTCL) is a rare, incurable, chronic disease accounting for approximately 3% of non-Hodgkin's lymphoma diagnoses every year. Patients with CTCL have skin lesions that can vary in severity putting patients at risk for developing symptoms that may impair their quality of life (QOL). The disease burden can lead to increased depressive symptoms, fatigue distress, and anxiety that the disease may be worsening. Seventy-five participants agreed to take part in an exploratory, prospective study to evaluate depressive symptoms, anxiety, fatigue distress, and spirituality as predictors of QOL in CTCL patients. Demographic variables including stage of disease, ethnicity, age, gender, marital status, level of education, and time since diagnosis, were also included in the analyses to assess for relationships. Bivariate correlations, t-tests, and regression analyses were conducted to assess for relationships among the predictor variables and QOL. The analyses revealed that the proposed model explained 64% of the variance, and depressive symptoms (t= -2.4, p= 0.020) and stage of disease (t= -3.0, p= 0.004) significantly predicted the QOL of CTCL patients. Evaluating for predictors that influence the QOL helps us to better understand the needs of the patients afflicted with CTCL. The importance of studying the QOL of the CTCL patients lies in the fact that nurses can assist in helping patients alleviate some of the symptoms they experience, thereby improving their QOL. Further study is warranted in developing interventions to assist in the preservation of QOL.

Les LAL-T sont des proliférations malignes de précurseurs lymphoïdes T bloqués à un stade précis de leur maturation. Si les anomalies génétiques impliquées dans la leucémogenèse T sont de mieux en mieux connues, les modifications de la régulation épigénétique sont beaucoup moins étudiées. Mon travail de thèse a consisté à étudier la dérégulation épigénétique intervenant dans les LAL-T au travers de 3 projets principaux. Dans le premier travail, nous avons identifié un mécanisme original de dérégulation de l’oncogène TAL1 consistant en la création d’un « neo-enhancer » oncogénique. TAL1 est l’un des oncogènes les plus fréquemment dérégulés dans les LAL-T. Cette dérégulation résulte principalement de translocations avec le locus du TCR ou des micro-délétions interstitielles SIL-TAL1, anomalies chromosomiques altérant des éléments de cis-régulation engendrant une expression ectopique monoallélique de TAL1. Mais dans une proportion importante de cas (environ 50%) de LAL-T TAL1+, une expression aberrante de TAL1 est observée sans que le mécanisme en cause ne soit identifié suggérant l’existence de mécanismes génétiques ou épigénétiques non connus. Nous avons découvert une nouvelle anomalie somatique consistant en une micro-insertion focale et récurrente 7 kpb en amont de TAL1, dans une région intergénique non-codante, responsable de la création d’un « neo-enhancer » oncogénique accompagné d’une modification des marques épigénétiques d’histones i.e. une substitution des marques répressives H3H27me3 par des marques activatrices H3K27ac. Ces micro-insertions sont un événement récurrent dans les LAL-T et ont été retrouvées dans 20% des LAL-T TAL1+ inexpliquées. Au travers du deuxième projet, j’ai tenté de mieux comprendre les bases biologiques à l’origine de différences de réponse au traitement. En effet, considérant deux groupes oncogéniques proches, le pronostic des patients TLX1+, déjà plutôt favorable dans le protocole LALA-94, n’a pas été significativement amélioré dans le protocole thérapeutique intensifié d’inspiration pédiatrique GRAALL 2003-2005 alors que les patients TLX3+ semblent avoir particulièrement bénéficié de ce dernier; les deux protocoles différant majoritairement par les doses de L-asparaginase. Nous avons montré que les patients TLX1+ exprimaient moins d’ASNS (Asparagine synthétase) que les patients TLX3+ et TLX- et que cette moindre expression résultait d’une inhibition épigénétique d’ASNS, à la fois par méthylation du promoteur et diminution des marques histones activatrices. Un niveau de méthylation d’ASNS bas est par ailleurs associé à une moindre sensibilité in vitro à la L-asparaginase. Enfin, la méthylation d’ASNS est un facteur pronostic indépendant pour les patients inclus dans le protocole GRAALL 2003-2005 suggérant que le statut de la méthylation d’ASNS au diagnostic pourrait intervenir dans l’adaptation des doses de L-asparaginase. Dans le troisième projet, je me suis intéressée à la méthylation globale de l’ADN. L’étude de la méthylation par MeDIP-array d’une série de 24 LAL-T nous a permis d’identifier des signatures de méthylation différentielle et de définir un panel minimum de 9 promoteurs de gènes dont l’étude de la méthylation par MS-MLPA a permis de déterminer un ratio de méthylation pour une large série de LAL-T adultes du GRAALL 2003-2005. Le statut de méthylation semble dicté par l’oncogène dérégulé avec en particulier les LAL-T TLX1+ ou TLX3+ associées à une signature d’hyperméthylation et les LAL-T SIL-TAL1+ à une signature d’hypométhylation. Ce statut de méthylation est par ailleurs un facteur pronostique indépendant. Ainsi, les patients hypométhylés ont un pronostic significativement plus défavorable que les patients hyperméthylés. Ensemble, ces résultats illustrent comment des perturbations de la régulation épigénétique peuvent intervenir à la fois dans l’oncogénèse des LAL-T mais aussi dans la réponse au traitement
T-ALLs are rare lymphoid neoplasms characterized by the proliferation of immature T precursors arrested at specific stages of maturation. While the genetic abnormalities involved in T-ALL leukemogenesis are becoming better known, alterations in epigenetic regulation, a very important component of the cellular homeostasis, are much less studied. My work was to tsudy the epigenetic deregulation in T-ALL through 3 main projects. In the first project, we identified an original mechanism of TAL1 oncogene deregulation. TAL1 is one of the most frequently deregulated oncogenes in T-ALL. This deregulation results mainly from translocations with the TCRδ locus or micro-deletions SIL-TAL1, two chromosomal abnormalities altering cis-regulatory elements leading to monoallelic TAL1 expression. But in a significant proportion of cases (about 50%) of TAL1+ T-ALL, an aberrant expression of TAL1 is observed without recognized mechanism suggesting unknown genetic or epigenetic mechanisms. We discovered a new somatic alteration consisting of a focal and recurrent microinsertion 7 kbp upstream of TAL1, in a non-coding intergenic region, responsible for the creation of an oncogenic "neo-enhancer" accompanied by a modification of epigenetic histone marks i.e. a “switch” from H3H27me3 repressive marks to H3K27ac activating marks. These microinsertions are a recurrent event in T-ALL and have been found in 20% of “unresolved” TAL1+ T-ALL. Through the second project, I tried to better understand the biological bases for discrepancies in patients related response to treatment. Indeed, considering two close oncogenic groups, the prognosis of TLX1+ patients, already rather favourable in the LALA-94 protocol, has not been significantly improved in the paediatric-inspired GRAALL2003-2005 trial , whereas TLX3+ patients seem to have benefited particularly from the latter; the two protocols differing mainly by L-asparaginase doses. We showed that TLX1+ patients expressed less ASNS (Asparagine synthetase) than TLX3+ and TLX- patients and that this lower expression resulted from ASNS epigenetic silencing, both by methylation of the promoter and reduction of active histone marks. A low level of ASNS methylation is also associated with lower in vitro sensitivity to L-asparaginase. Finally, ASNS methylation is an independent prognostic factor for patients included in the 2003-2005 GRAALL trial suggesting that the ASNS methylation status may be relevant for the adaptation of L-asparaginase doses. In the third project, I was interested in the global DNA methylation. MeDIP-array methylation data of a series of 24 T-ALLs allowed us to identify differential methylation signatures. We then studied the methylation status in a large series of adult T-ALL by MS-MLPA using a predictor containing 9 gene promoters. We observed that main driver oncogenes dictated methylation status. TLX1+ and TLX3+ T-ALLs displayed a hypermethylated profile and conversely, SIL-TAL1+ cases were associated with a hypomethylated profile. This methylation status is also an independent prognostic factor and hypomethylated patients have a significantly unfavorable prognosis compared to hypomethylated patients. Together, these results illustrate how disruptions in epigenetic regulation can be involved both in the T-ALL oncogenesis and in the response to treatment

Thesis (S.M. in Health Sciences and Technology)--Harvard-MIT Program in Health Sciences and Technology, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 92-95).
Disruptive models of innovation are starting to appear in healthcare. In the US, for instance, retail medicine clinics are changing the way in which patients satisfy their basic medical needs. In Mexico, similar retail medicine models (e.g. Farmacias Similares) are also disrupting healthcare delivery for basic medical needs. Disruptive innovations, however, are not limited to healthcare delivery, but also change the face of devices and diagnostics markets. A low CD4+ T cell count is the primary clinical indicator for HIV/AIDS disease progression, and thus is used as the primary trigger to initiate antiretroviral therapy. An entire diagnostic industry has emerged around CD4+ T cell counts for the management and treatment of HIV/AIDS patients. The diagnostic gold standards of CD4+ counts are flow cytometers. These large, capital intensive devices are commonly located in central laboratory settings, typically in urban areas. In developing nations, particularly, suburban and rural regions have no access to flow cytometers and typically face logistical problems of blood sample transportation and loss to follow-up of patients. Point-of-Care (POC) diagnostics promise disruptive models in diagnostics that will increase access, enhance care, and help better allocate healthcare resources. The concept of POC embodies the trade-off of lower "quality" (usually in the form of lower specificity and sensitivity) in exchange for higher "convenience" (i.e. better accessibility and portability, and significantly lower cost). POC diagnostics promise typical low-end and new-market disruptions in medical diagnostics and devices. Cambridge-based Daktari Diagnostics is one of such companies focused in POC diagnostics. It has developed a CD4+ T cell count diagnostic device for the management and treatment of HIV/AIDS patients. It is hypothesized in this thesis that there exists a relevant unmet medical need for POC CD4 count diagnostics in the Mexican HIV/AIDS market. In order to evaluate this hypothesis, secondary sources were reviewed, as well as primary interviews conducted across the Mexican HIV/AIDS healthcare landscape. While this hypothesis was evaluated on a preliminary basis only, responses suggested a relevant, albeit not urgent, medical need for POC CD4 count diagnostics. This primary hypothesis evaluation is extended by and complemented with market size estimations, and competitive dynamic discussions, that arrive at the following preliminary conclusions: the current market opportunity in Mexico ranges from baseline of ~100,000 tests per year to an upper bound potential of ~200,000 tests per year. In the context of this potential opportunity, Daktari's CD4 count diagnostic device is well positioned, as defined by diagnostic quality, technological characteristics, and competitive offering, to obtain a portion of this estimated market opportunity in Mexico.
by Mauricio Camargo Támara.
S.M.in Health Sciences and Technology

Les tumeurs sont composées de cellules malignes et d'une grande variété de cellules non-tumorales, en particulier des cellules immunitaires qui forment le micro-environnement tumoral (MET). Il a été démontré que la composition du MET était associée au devenir clinique des patients, en termes de survie et de réponses thérapeutiques. Avec le développement récent des immunothérapies qui ciblent des éléments spécifiques du MET, l'immunité anti-tumorale a soulevé un intérêt majeur. Plusieurs méthodologies ont été mises au point afin d'étudier la composition du MET, avec une précision toujours plus grande. En particulier, des méthodes comme MCP-counter permettent d'exploiter les données transcriptomiques de la tumeur entière afin de quantifier les différentes populations qui composent le MET. Le volet méthodologique de ce travail de thèse a ainsi consisté à proposer une amélioration de MCP-counter, en particulier pour l'analyse de données RNA-Seq. Une adaptation de la méthode pour des données issues de modèles murins (mMCP-counter) est également proposée. MCP-counter permet d'analyser rapidement le MET de larges séries de tumeurs. Un second volet de cette thèse consiste en l'application de cette méthode pour établir une classification immunitaire des sarcomes des tissus mous, un type de cancer rare, hétérogène et agressif. Cette classification immunitaire a permis de mettre en évidence des groupes de tumeurs faiblement ou fortement infiltrés, ainsi qu'un groupe marqué par une forte vascularisation. De manière intéressante, la classification immunitaire permet de prédire la réponse des patients aux immunothérapies. Ce travail a aussi démontré un rôle important des structures lymphoïdes tertiaires (SLT). Les SLT sont des structures de type noeud lymphatique composées de lymphocytes B et T qui se forment dans la tumeur ou à proximité de celle-ci. Au sein des SLT, une réponse immunitaire anti-tumorale peut se former et maturer. L'intérêt porté aux SLT est de plus en plus important pour de nombreux types de cancers. Dans la plupart des types de cancer, une forte infiltration de la tumeur par des lymphocytes T, en particulier CD8+, est associée à une meilleure survie des patients. Cependant, le carcinome rénal à cellules claires et le cancer de la prostate sont des exceptions à cette règle. En effet, dans ces deux cancers urologiques, la présence dans la tumeur de lymphocytes T est associée à une survie plus courte des patients, ainsi qu'à une rechute et une progression plus précoce. Ces exceptions sont détaillées dans une troisième partie de cette thèse, par une description minutieuse du MET, ainsi que par l'analyse de l'implication du système du complément. Dans leur ensemble, les résultats présentés dans cette thèse démontrent qu'en combinant différentes méthodes d'analyse, in silico, in situ et in vivo, il est possible d'obtenir une vision extrêmement complète du MET. La connaissance des types cellulaires présents dans la tumeur ainsi que leur orientation fonctionnelle permet de guider le soin apporté aux patients et d'améliorer leur devenir clinique. La description complète du MET ouvre la voie à une médecine personnalisée pour les patients atteints de cancer
Tumors are composed not only of malignant cells but also contain a vast variety of non-malignant cells, notably immune cells forming the tumor microenvironment (TME). The composition of the TME was shown to be associated with clinical outcome for cancer patients, in terms of survival and therapeutic responses. With the relatively recent development of immunotherapies targeting specific elements of the TME, tumor immunology has risen a strong interest and holds a strong therapeutic potential. Several methodologies have been developed to study the composition of the TME with an increased precision. Notably, some methods such as MCP-counter enable the use of the tumor bulk transcriptome to quantify cell populations composing the TME. The methodological aspect of this PhD project consisted in setting up an enhanced version of MCP-counter that can be readily applied to RNA-Seq data, as well as propose an adaptation of the method for mouse models. Using MCP-counter, the TME of large series of tumors can be easily analyzed. The application part of this PhD work consisted of applying MCP-counter to establish an immune-based classification of soft-tissue sarcoma, a rare, aggressive and heterogeneous cancer type. The immune classification notably allowed to identify immune low and high groups, and a group characterized by a strong vasculature. Interestingly, the classification was notably found to be predictive of the patients' response to immunotherapies. It also highlighted an important role of tertiary lymphoid structures (TLS). TLS are lymph-node-like structures composed of T and B cells that form within the tumor or in close proximity. They are a site of formation and maturation of antitumoral immune responses. TLS are raising a growing interest in many malignancies. In most cancer types, a strong infiltration by T cells, in particular CD8+ T cells, is associated with a favorable clinical outcome. However, clear-cell renal cell carcinoma and prostate cancer are exceptions to this general rule. Indeed, in these urological cancers, an increased infiltration by T cells is associated with a decreased patient survival and with earlier relapse and disease progression. In a third part of this thesis, these exceptions are investigated with more details by scrutinizing the TME, and questioning the implication of the complement system. Overall, this thesis presents how the combination of several analysis methods, in silico, in situ and in vivo, can help achieve an extremely precise description of the TME. Knowing accurately what cell populations and what their functional orientation can help guide patients care and improve clinical outcome. Complete description of the TME opens the way towards personalized medicine for cancer patients

博士
國立陽明大學
微生物暨免疫學研究所
83
T細胞辨認主要組織相容性複合體(major histocompatibility complex，簡稱MHc)所呈獻的抗原胜月太。MHC與抗原胜胜月太的相互作用有如受體(receptor)與配體(ligand)一樣。胜月太可以穩定MHC的構造，以免變性及失去活性。最近的研究報告指出即使是低親合性胜月太也有穩定MHC構造的功能。在本研究裡，我們以一個對I-Ad有低親合性的胜月太PBl來探討它對抗原胜月太與I-Ad結合的影響。結果顯示PB1對I-Ad-限制型T細胞的反應有加強作用。cI 12-26變異胜月太對I-Ad-限制型及IEk-限制型T細胞的影響進一步證實了這種加強作用的可能機制。 PB1首次被發現對所有抗原專一性的I-Ad-限制型T細胞的反應都有加強作用。對I-Ad-及I-Ek-限制型T細胞的反應，或是對不經由T細胞受體(T cell receptor，TCR)辨認抗原之免疫反應，如超抗原SEB及有絲分裂原ConA，則沒有加強作用。雖然它對I-Ad只有很低的親合力，但PB1與高親合力之胜月太一樣可以穩定I-Ad的表現。此外，PBl也可增加抗原胜月太與I-Ad的結合。因此，PBl的特殊加成作用很可能是由於PBl可以穩定I-Ad的構造。而它的低親合力卻可使它易被其他高親合力的抗原胜月太取代，使抗原胜月太呈獻量增加而加強對T細胞的刺激作用。另一低親合性的胜月太TFR442-453，也藉由同樣機制而有強化T細胞反應之功能。 由上述的可能機制推測，有穩定MHC功能的低親合性胜月太就能加強其他抗原胜月太與此一MHC的結合。此一想法可由 cI 12-26變異胜月太在I-Ad的研究得到證實。用不同的cI 12-26變異胜月太做競爭結合測試，我們找到cI 12-26與I-Ad作用時所可能使用的固定殘基。雖然在固定位置做改變會顯著地降低cI 12-26與I-Ad的親合力，這些變異胜月太 (R16E,R17E及L18S)仍可以穩定I-Ad的構造，也會加強I-Ad-限制型T細胞的反應，而其他胜月太則無此功能。 我們以更進一步的實驗設計，探討cl12-26變異胜月太與 I-Ek專一性的T細胞反應的閥係，證實了此種強化機制。由於I-Ek與DR1分子有極高相似性，利用DR1的已知結構，我們成功地模擬 I-Ek的構造；並且利用競爭結合測試，確認cI 12-26與I-Ek作用的固定殘基是18S,21I,23E和26K。所有位置的變異胜月太與cI 12-26一樣可以穩定I-Ek的表現。但是只有在固定殘基做改變的變異胜月太，才能加強 I-Ek-限制型T細胞的反應。更進一步的分析顯示並非在固定殘基做改變的所有變異胜都有加強作用。類似性質的月安基酸替換(I21L,I21A,E23Y與K26R)並不會改變胜月太與I-Ek之親合力，而使這些胜月太對T細胞有競爭性的抑制作用。只有親合力顯著降低的變異胜月太(L18S,I21E,K26A,K26D及K26L)才會增加抗原胜月太與I-Ek之結合及加強T細胞之反應。 這些結果顯示了一個強化T細胞反應的新方法。低親合性胜月太可增加穩定的MHC使其兔於變性及失去活性。這些胜月太會被高親合性抗原胜月太所取代，進而增加抗原呈獻及刺激T細胞。本文的研究也說明了強化胜月太之設計可根據MHC之結合序譜而得到。在高親合性胜月太約主要固定殘基上做性質迥異的月安基酸替換，就可得到低親合性胜月太，其PBl一樣有效地加強T細胞反應。有關強化胜月太在加強免疫反應的實際運用上，正有待進一步評估。 T cells recognize antigenic peptides presented by a major histocompatibility complex (MHC). There is an intricate interplay between MHC and peptide in this ligand-receptor interaction, peptides are essential for stabilizing the MHC molecules and prevent MHC from denaturation or inactivation. Recent studies indicate that even the interaction with low-affinity peptides can stabilize MHC conformation, In this study, an I-Ad-binding peptide PBl was used to modulate the binding of antigenic peptides to I-Ad , and was found to increase T cell response restricted by I-Ad. The proposed mechanism was further confirmed by using variant peptides of cI 12-26 in both I-Ad- and I-Ek-specific T cell immunity. FBl was first found to enhance the reactivity of I-Ad restricted T cells, irrespective of the antigenic specificity. PBl had no effect on T cells specific for I-Ad and I-Ek nor did PBl increase the T cell responses to concanavalin A and staphylococcal enterotoxin B. Despite the weak affinity of PBl for I-Ad, PBl was effective as high-affinity peptide in stabilizing I-Ad expression. In addition, the binding of antigenic peptide to I-Ad was increased in the presence of PBl. Therefore, the unusual addition effect of PBl was likely due to that PBI could stabilize the I-Ad structure, and its low affinity would allow displacement by high-affinity antigenic peptides. The net result is an increased binding of antignic peptide and enhanced stimulation of T cells. A similar effect was demonstrated on a synthetic transferrin receptor peptide with minimum affinity for I-Ad. Based on the proposed mechanism, a low-peptide which retains the MHC-stabilizing ability should enhance the binding of other antigenic peptide to the given MHC. This was confirmed by using cI 12-26 with substitution at its I-Ad anchor sites. The potential I-Ad anchor sites of cl 12-26 were mapped by using competitive binding assay on site-specific mutants of cI 12-26. Despite that mutation at potential I-Ad anchor sites significantly reduced that I-Ad binding affinity, these peptides (R16E, R17E, and L18S) were able to stabilize I-Ad conformation. I-Ad-restricted T cell responses were specifically enhanced by the presence of these low-affinity peptides, but not by most other cI 12-26 variants. The augmentative mechanism was further elaborated by using cI 12-26 variants on I-Ek-specific T cells. The high homology of I-Ek with DRl enable us to simulate the structure of I-Ek based on known crystal structure of DRI. Together with competitive binding assay, the exact I-Ek anchor sites for cI 12-26 were identified as 18S, 21I, 23E, and 26K. cI 12-26 and all its site-specific mutants similarly stabilized I-EK expression, but only variant peptides with substitution at I-Ek anchor sites increased I-Ek-restricted T cell responses. Furthermore, not all mutations at anchor residues generated augmentation peptides. Substitution of anchor with a similar type of amino acid (I21L, I21A, E23A, and K26R) did not alter the I-Ek binding affinity, and the peptide competitively inhibited T cell responses. Only the mutation at anchor residues that remarkably reduced the binding affinity (L18S, 121E, K26A, K26D, and K26L) resulted in peptides which enhanced the binding of other antgenic peptides to I-Ek and increased I-Ek-specific T cell reactivity. The results support a novel approach to increase T cell immunity. Specific low-affinity peptides can be used to increase the pool of biochernically stable MHC by preventing MHC from denaturation or inactivation. The peptides can then be displaced by high-affinity antigenic peptide and resulted in enhanced antigen presentation and T cell recognition. The present study also suggest enhancing peptide can be designed according to the motif for any MHC molecule. Substitution of a major anchor site for a hgih-affinity peptide by dissimilar residues would produce peptides as effective as PBl to increase T cell response. Application of enhancing peptides in the modulation of immune response awaits further characterization.

博士
國立陽明大學
生物醫學影像暨放射科學系
103
Adoptive T cells therapy (ACT) has been reported to be effective for the treatment of several types of cancers. However, ACT is not widely used in clinic mainly due to two reasons: the requirements of large numbers of transferred T cells and the hindrance of immunosuppressive tumor microenvironment. Accumulating evidences reveal that chemotherapeutic drugs could act as immune supportive rather than immunosuppressive agents when proper dosage is used, and the combination with immunotherapy often results in better outcomes than monotherapy. Immunomodulation effects of sorafenib, a multi-kinase inhibitor, have been reported in several types of cancers; however, the results are controversial at high- and low-dose. Up to present, the best dosage window of sorafenib augmenting responses of ACT while not altering host immunity is still ambiguous. Here we used a well-established E.G7/OT-1 mouse model to investigate the effects of serial low-doses of sorafenib on tumor microenvironment and therapeutic efficacy of ACT as well as the related underlying mechanisms. Sorafenib lowers the expressions of immunosuppressive factors and enhances functions and migrations of transferred cytotoxic T lymphocytes (CTLs) through inhibiting the STAT3 signaling pathway. Granzyme B promoter driven dual imaging reporters was transduced into CTLs to visualize the activation of transferred CTLs prior to ACT. Better activations of CTLs and tumor inhibitions are found in the combination group compared with both CTLs and sorafenib alone groups. Sorafenib treatment reverses the immunosuppressive microenvironment through reduction of immunosuppressive factors and immunosuppressive cells such as myeloid derived suppressive cells (MDSCs) and regulatory T cells (Tregs), and boosts the functions of transferred CTLs. These results suggest that sorafenib inhibits tumor growth not only through eradicating tumor cells but also modifying tumor microenvironment. Both contribute to the better outcomes of ACT. The findings obtained from the study may make the ACT becomes easy to apply and facilitate its progression in clinical applications.

Chez les vertébrés adultes, le nombre de cellules T périphériques est soumis à un contrôle strict. Bien qu'un grand nombre de cellules T soient produites chaque jour, le nombre de cellules T à la périphérie reste constant. Chaque nouveau lymphocyte T produit ne pourra donc s'établir à la périphérie qu'après la mort d'un lymphocyte déjà établi. Dans cette optique, la sélection du répertoire des cellules T périphériques n'est pas uniquement dépendant des interactions entre une cellule et son antigène, mais elle est également dépendante d'interactions entre différentes sous-populations cellulaires (Freitas and Rocha, 2000). Dans le but de comprendre comment l'homéostasie des cellules T périphériques est atteinte, et afin de comprendre pourquoi l'homéostasie parvient à un certain niveau d'équilibre, il est important de déterminer chaque facteur intervenant dans ce processus et la contribution de chacun d'entre eux.
Les cellules T sont générées dans le thymus. La production thymique de cellules T est responsable, chaque jour, de l'export de nouvelles cellules T. Cependant la taille du thymus n'est pas constante, puisque le thymus involue avec l'âge, ce qui peut avoir des conséquences sur l'homéostasie des cellules T périphériques. Il faut donc tenir compte du compartiment T central, le thymus, lorsque l'on étudie l'homéostasie des compartiments périphériques.
Le compartiment T périphérique est composé d'un certain nombre de sous-compartiments, puisque chaque cellule T n'est pas identique, et de nombreuses cellules vont se différencier à la périphérie en des sous-populations spécifiques, possédant des fonctions et des propriétés différentes. Par exemple, les sous-populations CD4+ et CD8+ devront être considérées séparément puisqu'elles sont impliquées dans différents types de réponses immunitaires et ont des mécanismes d'action différents. De la même façon, les compartiments naïfs, effecteurs et mémoires contribuent différemment à l'immuno-compétence de chaque individu. Les mécanismes impliqués dans le contrôle du nombre de chacune de ces sous-populations sont également importants pour la compréhension de l'homéostasie cellulaire T totale.
L'objectif de cette thèse a été de comprendre les mécanismes responsables de l'homéostasie périphérique T en général, et de l'homéostasie des cellules T CD4+ périphériques en particulier. Ce travail a été divisé en trois parties.
Dans la première partie de cette thèse, nous avons évalué le rôle du thymus dans la maintenance du nombre de cellules T. Nous avons développé un nouveau système expérimental nous permettant d'obtenir une estimation quantitative de la fraction des cellules précurseures pré-T compétentes, nécessaire pour assurer la fonction thymique mais aussi d'évaluer la contribution thymique à l'établissement du compartiment T périphérique. Nous avons montré qu'il n'existe pas de mécanismes homéostatiques compensatoires au cours du développement thymique. Ce résultat nous a ensuite conduit à évaluer l'effet d'un export thymique réduit sur l'établissement du compartiment T périphérique. Nous avons montré que la taille du compartiment T périphérique est indépendante du thymus, suggérant que des mécanismes compensatoires se mettent en place à la périphérie. Lorsque nous avons étudié les compartiments naïfs et activées/mémoires séparément, nous avons observé que les mécanismes compensatoires sont plus efficaces pour les sous-populations activées/mémoires.
Dans la seconde partie de cette thèse, nous avons étudié le rôle des interactions entre les cellules T périphériques dans l'établissement de l'homéostasie T périphérique. Nous avons analysé l'interaction entre les cellules T CD4+CD25+CD45RBlow (également appelées cellules T CD4+ régulatrices) et les cellules CD4+CD25-CD45RBhigh, dans des expériences de transfert chez la souris. Nous avons observé que le ratio entre les cellules CD4+CD25+CD45RBlow et les cellules CD4+CD25-CD45RBhigh transférées était déterminant pour le nombre de cellules recouvrées suggérant donc que l'interaction entre ces deux populations pourrait être déterminante pour l'homéostasie périphérique T. Nous avons testé cette hypothèse en transférant des cellules T CD4+CD25+ dans un modèle murin (les chimères de moelle osseuse CD25-/-) où l'homéostasie périphérique est perturbée et où cette sous-population CD25+ est absente. Nous avons observé que la présence de ces cellules T CD4+CD25+ dans ces chimères de moelle osseuse a pour conséquence la normalisation du compartiment T périphérique. Nous avons montré donc que l'homéostasie des cellules T périphériques est atteinte aussi grâce à la structure des sous-populations qui la constitue.
Dans la troisiéme partie de cette thèse, nous avons étudié l'importance des ressources pour la maintenance de la structure des sous-populations T périphériques. Il a été montré que le nombre de cellules T CD4+CD25+ est réduit chez les souris invalidées pour le gène de l'IL-2. Il a aussi été montré que ces souris développent des maladies auto-immunes avec des caractéristiques communes à celles développées par les souris CD25-/-. Nous avons fait l'hypothèse que le manque d'IL-2 serait responsable de la diminution de la survie des cellules T régulatrices CD4+CD25+ dans le compartiment T périphérique, et que donc les manifestations auto-immunes seraient la conséquence de la perturbation de la structure des sous-populations périphériques, puisque ces animaux ne contiennent pas cette sous-population spécifique. Nous avons testé cette hypothèse en triant les quelques cellules T CD4+CD25+ présentes chez les animaux IL2-/- et en testant leur fonction de cellules suppressives in vivo. Ces cellules ont montré leur capacité à exercer une fonction suppressive, suggérant que les souris IL-2-/- sont capable de produire des cellules régulatrices T CD4+CD25+. Nous avons confirmé ces résultats en établissant des chimères de moelle osseuse, avec des cellules provenant de la moelle osseuse d'animaux IL-2-/- et d'animaux CD25-/-. Ces animaux chimériques ne développent pas de maladies auto-immunes et le compartiment T périphérique est constitué d'une proportion normale des différentes sous-populations CD4+, notamment les CD4+CD25+. Les précurseurs issus de la moelle osseuse des animaux IL-2-/- ont donc été capables de générer une population viable de cellules T régulatrices, capable d'utiliser pour leur survie l'IL-2 produite de façon paracrine. Ces résultats illustrent bien le rôle des cytokines comme ressources majeures, notamment pour l'établissement de la structure des populations périphériques.
L'ensemble des résultats obtenus au cours de cette thèse nous a conduit à formuler que l'homéostasie des cellules T périphériques est le résultat, non seulement de l'impact thymique, mais aussi de mécanismes périphériques. Les populations sous représentées, comme la population de cellules T régulatrices CD4+CD25+, pourraient exercer un rôle important dans la maintenance de l'homéostasie des cellules T à la périphérie.

碩士
國立中正大學
分子生物研究所
99
In immune system, regulatory T (Treg) cells are the cells to maintain immune homeostasis, but also major contributors in the establishment and persistence of cancer-induced immune tolerance. Transitional cell carcinoma (TCC) is the most common tumor of the urinary system. According to previous data, the percentage of natural killer (NK) cells in PBMC from TCC patients are lower than control, however, the percentage of CD4+CD25+ T cells are higher. Base on the above results, we want to investigate the interaction between Treg cells and NK cytotoxic functions in TCC by mouse model through subcutaneously injection of MB-49, a bladder cancer cell line, in C57BL/6JNarl mice; and whether enhance antitumor ability by using cyclophosphamide (CTX), an anti-cancer drug can suppress Treg function in vivo. The proliferation and survival rate of MB-49 treated in different dosage of CTX did not show difference in vitro, but, in vivo, the tumor volume in low dose CTX treatment was inhibited. CTX also decreased the percentage, absolute cell number and suppressive function of Treg cells in dose dependent, lower dose was much more dominant. Moreover, the suppressive ability of Treg cells of CTX treated mice was decreased than untreated mice from day 10 to day 15. We also found that CTX treatment decreased CD11b+Gr-1+macrophage, but increased CD11c+ dendritic cells. Conversely, the expression of functional surface molecules of NK cells and the cytotoxic function of NK cells was increased in CTX treated mice and the apoptosis of NK cells was decreased compared with untreated mice. Not as mouse model, regulatory T cells isolated from human peripheral blood were not suppressed the cytotoxicity or increase the apoptosis of NK cells directly. According to our data, we found that Treg cells might suppress the expression of functional surface molecules of NK cells and the cytotoxicity but enhance apoptosis of NK cells in mice model; CTX treatment can deplete Treg suppressive function and decrease tumor size in urothelial carcinoma. Furthermore, we also found that CTX treatment decreased CD11b+Gr-1+macrophage, but increased CD11c+ dendritic cells.

博士
中國文化大學
體育學系運動教練碩博士班
104
Aging results in biological changes in body composition. Especially, it is associated with decreases in the performance and function of muscle. Sarcopenia refers to the loss of skeletal muscle mass and decline in associated muscle strength. In addition, it will also affect the normal functioning of the immune function and chronic low-grade inflammation with advancing age, thus increasing the risk of disease incidence. Purpose: This study was to investigate the effects of kettlebell training ( KT ) on changes in body composition, muscle strength, pulmonary function, T helper cell and chronic low-grade inflammation in sarcopenia elderly. Methods: Thirty-three elderly patients ( aged 65-75 years) that fulfilled the sarcopenia index inclusion criteria. Participants were randomly assigned to an kettlebell training ( KT ) or control ( CON ) group. The KT group was performed for 60 min, two times per week for 8 weeks. The CON group were asked maintain daily activity and avoid participating in any exercise program. All participants were evaluated on body composition, muscle strength, pulmonary function, T helper cell and chronic low-grade inflammation at before ( Week 0) and after 8-week ( Week 8 ) and 4-week detraining ( Week 12 ). Data were analyzed using a two-way mixed design ANOVA analysis of variance. Results: After 8 weeks of kettlebell training program and 4 weeks detraining, appendicular skeletal muscle mass (ASM) and sarcopenia index were significantly improved in the KT group. And sarcopenia index were significantly increased in the KT group compared to the CON group. In contrast, visceral fat area (VFA) and body fat mass (BFM) in the CON at Week 8 significantly higher than Week 0; For muscle performance, the results demonstrated that left hand grip (LG), back muscle strength (BS) and peak expiratory flow (PEF) at Week 8 and Week 12 significantly improved in the KT group compared to the CON group, and right hand grip (RG) at Week 8 significantly increased in KT compared to CON. In addition, the BS andd PEF at Week 8 and Week 12 significantly higher than Week 0, and the both hand grip at Week8 higher than Week 0. In contrast, the both hand grip and PEF in CON at Week 8 and Week 12 significantly lower than Week 0; For cytokines, the IFN-γ、IL-17、IFN-γ/ IL-4 ratio concentrations at Week 8 and Week 12 significantly reduced in the KT group compared to the CON group, and IL-4 concentrations at Week 8 significantly increased in KT compared to CON. In addition, the IFN-γ, IFN-γ/ IL-4 ratio and hs-CRP concentrations at Week 8 and Week 12 significantly reduced than Week 0. Conclusions: The kettlebell training program were significantly increased in appendicular skeletal muscle mass, thus to improved sarcopenia index, as well as enhance grip, back muscle strength and peak expiratory flow, and the effect is reserved to the Week 12. In addition, it can effectively reduce blood pro-inflammatory cytokines, while increasing the concentration of anti-inflammatory, but also reduce the relative ratio of Th1 / Th2 of. Moreover, significantly reduced the concentration of low-grade chronic inflammation indicators of hs-CRP.

碩士
國立臺灣大學
免疫學研究所
96
MHC class II molecules are important in positive and negative selections of CD4 T cells in the thymus and are specialized in presenting antigenic peptides to CD4 T cells in the periphery. Engagement of MHCII-peptide complex and TCR is important to CD4 T cell activation. It has been reported that MHC class II deficiency leads to defective CD4 T cell development which in turn results in severe immunodeficiency. Studies on the role of MHC II in immune response have relied mainly on MHC II knockout mice. The question of whether low MHC II expression affects peripheral T cell responses has never been addressed. The availability of ENU-mutagenized mice P235 presents an opportunity to study how low MHC class II expression affects T cell responses to infection. In the present study, I found that T cell responses were reduced in P235 mice after infection with Histoplasma capsulatum (Hc), including both the numbers of activated CD4 and CD8 T cells and the cytokine producing ability of CD4 T cells. The TCR Vβ repertoire in naïve P235 mice was not different from that in WT mice. Upon infection by Histoplasma capsulatum, all CD4 and CD8 T cell Vβ populations expanded in P235 mice as well as in WT mice, but the expansion was limited in P235 mice. Interestingly, with lower T cell responses in P235 mice, their ability to clear the fungus at 1/100 of lethal dose was as efficient as in WT mice. Based on the results, it was clear that low MHC II expression reduces T cell responses to infection by Histoplasma capsulatum. The mechanism by which lower T cell responses not affecting fungal clearance still awaits to be investigated.

碩士
國立中山大學
電機工程學系研究所
90
Two different topics associated with their respective applications are proposed in this thesis. The first topic is the implementation of a 6-T SRAM cell using dual threshold voltage transistors and low power quenchers. We proposed a SRAM cell with dual threshold voltage transistors. The advantages of such a design is to reduce the access time and maintain data retention at the same time. Besides, the unwanted oscillation of the output data lines caused by large currents is reduced by adding two back-to-back quenchers. The second topic is focused on the implementation of a programmable PLL-based frequency multiplier. Using the method of a phase-locked loop and a programmable divisor to implement a frequency multiplier. Ａ synchronous clock signal can be generated by the proposed design. It can also be used in wireless communication systems, e.g. local oscillators.