948 resultados para lymphocyte T CD8
Resumo:
Thse numrise par la Direction des bibliothques de l'Universit de Montral.
Resumo:
Thse numrise par la Direction des bibliothques de l'Universit de Montral.
Resumo:
Backgrond: Muscular dystrophies consist of a number of juvenile and adult forms of complex disorders which generally cause weakness or efficiency defects affecting skeletal muscles or, in some kinds, other types of tissues in all parts of the body are vastly affected. In previous studies, it was observed that along with muscular dystrophy, immune inflammation was caused by inflammatory cells invasion - like T lymphocyte markers (CD8+/CD4+). Inflammatory processes play a major part in muscular fibrosis in muscular dystrophy patients. Additionally, a significant decrease in amounts of two myogenic recovery factors (myogenic differentation 1 MyoD] and myogenin) in animal models was observed. The drug glatiramer acetate causes anti-inflammatory cytokines to increase and T helper (Th) cells to induce, in an as yet unknown mechanism. MyoD recovery activity in muscular cells justifies using it alongside this drug. Methods: In this study, a nanolipodendrosome carrier as a drug delivery system was designed. The purpose of the system was to maximize the delivery and efficiency of the two drug factors, MyoD and myogenin, and introduce them as novel therapeutic agents in muscular dystrophy phenotypic mice. The generation of new muscular cells was analyzed in SW1 mice. Then, immune system changes and probable side effects after injecting the nanodrug formulations were investigated. Results: The loaded lipodendrimer nanocarrier with the candidate drug, in comparison with the nandrolone control drug, caused a significant increase in muscular mass, a reduction in CD4+/CD8+ inflammation markers, and no significant toxicity was observed. The results support the hypothesis that the nanolipodendrimer containing the two candidate drugs will probably be an efficient means to ameliorate muscular degeneration, and warrants further investigation.
Resumo:
Le contrle immunitaire des infections virales est effectu, en grande partie, par les lymphocytes T CD8+ cytotoxiques. Pour y parvenir, les lymphocytes T CD8+ doivent tre en mesure de reconnatre les cellules infectes et de les liminer. Cette reconnaissance des cellules infectes seffectue par linteraction du rcepteur T (TCR) des lymphocytes T CD8+ et des peptides viraux associs au complexe majeur dhistocompatibilit (CMH) de classe I la surface des cellules htes. Cette interaction constitue llment dclencheur permettant llimination de la cellule infecte. On comprend donc toute limportance des mcanismes cellulaires menant la gnration des peptides antigniques partir des protines virales produites au cours dune infection. La vision traditionnelle de cet apprtement protique menant la prsentation dantignes par les molcules du CMH propose deux voies cataboliques distinctes. En effet, il est largement admis que les antignes endognes sont apprts par la voie dite classique de prsentation antignique par les CMH de classe I. Cette voie implique la dgradation des antignes intracellulaires par le protasome dans le cytoplasme, le transport des peptides rsultant de cette dgradation lintrieur du rticulum endoplasmique, leur chargement sur les molcules du CMH de classe I et finalement le transport des complexes peptide-CMH la surface de la cellule o ils pourront activer les lymphocytes T CD8+. Dans la seconde voie impliquant des antignes exognes, le dogme veut que ceux-ci soient apprts par les protases du compartiment endovacuolaire. Les peptides ainsi gnrs sont directement chargs sur les molcules de CMH de classe II lintrieur de ce compartiment. Par la suite, des mcanismes de recyclage vsiculaire assurent le transport des complexes peptide-CMH de classe II la surface de la cellule afin de stimuler les lymphocytes T CD4+. Cependant, cette stricte sgrgation des voies dapprtement antignique a t durement prouve par la capacit des cellules prsentatrices dantignes effectuer lapprtement dantignes exognes et permettre leur prsentation sur des molcules de CMH de classe I. De plus, lidentification rcente de peptides dorigine intracellulaire associs des molcules de CMH de classe II a clairement indiqu la prsence dinteractions entre les deux voies dapprtement antignique permettant de transgresser le dogme pralablement tabli. Lobjectif du travail prsent ici tait de caractriser les voies dapprtement antignique menant la prsentation dantignes viraux par les molcules du CMH de classe I lors dune infection par le virus de lHerps simplex de type I (HSV-1). Dans les rsultats rapports ici, nous dcrivons une nouvelle voie dapprtement antignique rsultant de la formation dautophagosomes dans les cellules infectes. Cette nouvelle voie permet le transfert dantignes viraux vers un compartiment vacuolaire dgradatif dans la phase tardive de linfection par le virus HSV-1. Cette mise en branle dune seconde voie dapprtement antignique permet daugmenter le niveau de prsentation de la glycoprotine B (gB) virale utilise comme modle dans cette tude. De plus, nos rsultats dcrivent la formation dune nouvelle forme dautophagosomes drivs de lenveloppe nuclaire en rponse linfection par le virus HSV-1. Ces nouveaux autophagosomes permettent le transfert dantignes viraux vers un compartiment vacuolaire lytique, action galement assure par les autophagosomes dits classiques. Dans la deuxime partie du travail prsent ici, nous utilisons linfection par le virus HSV-1 et la production de la gB qui en rsulte pour tudier le trafic membranaire permettant le transfert de la gB vers un compartiment vacuolaire dgradatif. Nos rsultats mettent en valeur limportance du rticulum endoplasmique, et des compartiments autophagiques qui en drivent, dans ces mcanismes de transfert antignique permettant damplifier la prsentation antignique de la protine virale gB sur des CMH de classe I via une voie vacuolaire. Lensemble de nos rsultats dmontrent galement une troite collaboration entre la voie classique de prsentation antignique par les CMH de classe I et la voie vacuolaire soulignant, encore une fois, la prsence dinteraction entre les deux voies.
Resumo:
Les maladies autoimmunes sont des affections chroniques, le plus souvent invalidantes, qui touchent plus de 5% de la population dans les pays dvelopps. Lautoimmunit rsulte de la rupture des mcanismes de tolrance du systme immunitaire vis--vis des autoantignes exprims par les tissus de lorganisme, entranant la destruction dun ou de plusieurs organes-cibles par les lymphocytes T et/ou B. Lhpatite autoimmune et le diabte autoimmun se caractrisent par la destruction slective des hpatocytes et des cellules beta pancratiques, respectivement. De plus en plus darguments suggrent une implication des lymphocytes T CD8+ dans le dclenchement, la progression et la rgulation des rponses associes plusieurs maladies autoimmunes. Dans ce projet, nous avons suivi lvolution de clones de lymphocytes T CD8+ spcifiques un antigne particulier dont le site dexpression diffrait. Pour ce faire, nous avons dvelopp deux nouveaux modles murins double transgniques par croisement entre une ligne de souris exprimant un TCR transgnique spcifique la nucloprotine (NP) du virus de la choriomningite lymphocytaire (LCMV), et une souris exprimant cette NP-LCMV : 1) uniquement dans les hpatocytes (modle dhpatite autoimmune), ou 2) simultanment dans le thymus et le pancras (modle de diabte autoimmun). Lavidit fonctionnelle des lymphocytes T CD8+ spcifiques la NP chez les souris TCR transgniques tait inversement proportionnelle au niveau dexpression du TCR. Le rpertoire lymphocytaire dans le thymus, la rate, les ganglions et le sang priphrique a t caractris pour chacune des lignes de souris double transgniques, de mme que la capacit fonctionnelle et le phnotype (marqueurs dactivation/mmoire) des lymphocytes T CD8+ autoractifs. Chacun des deux nouveaux modles prsents dans cette tude ont montr que les lymphocytes T CD8+ spcifiques la NP sont aptes briser la tolrance centrale et priphrique et provoquer une raction dautoimmunit spontane. Dans le modle dhpatite autoimmune, o lexpression de lautoantigne tait restreinte au foie, la surexpression du TCR transgnique a entran une dltion thymique quasi-totale des lymphocytes T CD8+ spcifiques la NP prvenant le dveloppement dune hpatite spontane. alors quun niveau de TCR comparable celui dune souris de type sauvage a permis une slection positive des lymphocytes autoractifs qui se sont accumuls dans le foie o ils se sont activs pour provoquer une hpatite autoimmune spontane. Dans le modle de diabte autoimmun, o lautoantigne tait exprim dans le pancras et le thymus, les souris des deux lignes double transgniques ont montr une dltion thymique partielle, peu importe le niveau dexpression du TCR. Seuls les mles adultes dveloppaient un diabte spontan et une partie de leurs lymphocytes T CD8+ exprimaient une combinaison particulire de marqueurs dactivation/mmoire (CD44, CD122, PD-1). Cette population lymphocytaire tait absente chez les souris femelles et les mles sains. Ltude de la tolrance des lymphocytes T CD8+ autoractifs dans nos deux nouveaux modles murins double transgniques a permis didentifier des mcanismes alternatifs possiblement impliqus dans la tolrance et lactivation, et de mieux comprendre le rle des lymphocytes T CD8+ autoractifs dans le processus autoimmun menant lhpatite autoimmune et au diabte autoimmun. Ces dcouvertes seront utiles pour dvelopper de nouvelles approches thrapeutiques ciblant les lymphocytes T CD8+ autoractifs.
Resumo:
La transplantation allognique de cellules souches hmatopotiques (ASCT) est couramment utilise pour traiter diffrents cancers hmatologiques. Malheureusement, leffet bnfique de cette technique est limit par la raction du greffon contre lhte (GVHD) qui demeure la cause principale de mortalit post-greffe. La GVHD endommage diffrents organes et retarde la reconstitution immunitaire des lymphocytes T (LT) ce qui augmente les risques dinfection et de rechute. Le dveloppement de nouveaux traitements permettant dacclrer la reconstitution immunitaire augmenterait donc les chances de survie des patients greffs. Il existe deux faons de rgnrer des LT: via la thymopose qui consiste produire de nouveaux LT, ou par la prolifration homostatique (PH) qui implique lexpansion rapide des LT matures retrouvs dans le greffon. La PH requiert deux signaux essentiels: linterleukine-7 (IL-7) et la prsentation dantignes du soi par les cellules dendritiques (DC) via le complexe majeur dhistocompatibilit (CMH) I pour les LT CD8+ et le CMH II pour les LT CD4+. Dans un contexte dASCT, la chimiothrapie et la GVHD endommagent le thymus rendant la thymopose inefficace. Par consquent, la reconstitution immunitaire repose presque entirement sur la PH des LT. Lobjectif de cette thse tait de comprendre comment la GVHD affecte la reconstitution des LT. Grce un modle murin, nous avons dmontr que la PH des LT CD4+ est absente durant la GVHD et ce, d de faibles niveaux dIL-7 et une diminution du nombre de DC. La perte des DC est en grande partie cause par des niveaux rduits de stromal derived factor-1 (SDF-1) et par labsence de progniteurs de DC dans la moelle osseuse des souris en GVHD. Le traitement des souris en GVHD avec du SDF-1 permet daugmenter le nombre de DC, et lorsquadministr avec lIL-7, amliore significativement la PH des LT CD4+. Contrairement aux LT CD4+, ladministration dIL-7 seule est suffisante pour restaurer la PH des LT CD8+ durant la GVHD et ce, mme en absence des DC. Ces diffrences sexpliquent pour deux raisons : 1) lexpression du CMH I, contrairement au CMH II, nest pas limite aux DC mais est galement exprime par les cellules stromales du receveur ce qui est suffisant pour induire la PH des LT CD8+ et 2) les LT CD8+ rpondent des concentrations plus faibles dIL-7 systmique comparativement aux LT CD4+. En conclusion, lensemble de ces rsultats permettra de mettre en place des tudes translationnelles sur le potentiel thrapeutique du SDF-1 et de lIL-7 dans la reconstitution immunitaire des patients greffs.
Resumo:
Histoplasmosis is a systemic mycosis endemic in extensive areas of the Americas. The authors report on an urban adult male patient with uncommon oral-cutaneous lesions proven to be histoplasmosis. Additional investigation revealed unnoticed HIV infection with CD4+ cell count of 7/mm3. The treatment was performed with amphotericin B, a 2065 mg total dose followed by itraconazole 200mg/daily plus antiretroviral therapy with apparent cure. Histoplasmosis is an AIDS-defining opportunistic disease process; therefore, its clinical diagnosis must drive full laboratory investigation looking for unnoted HIV-infection. 2013 by Anais Brasileiros de Dermatologia.
Resumo:
Abnormal expansion or depletion of particular lymphocyte subsets is associated with clinical manifestations such as HIV progression to AIDS and autoimmune disease. We sought to identify genetic predictors of lymphocyte levels and reasoned that these may play a role in immune-related diseases. We tested 2.3 million variants for association with five lymphocyte subsets, measured in 2538 individuals from the general population, including CD4+ T cells, CD8+ T cells, CD56+ natural killer (NK) cells, and the derived measure CD4:CD8 ratio. We identified two regions of strong association. The first was located in the major histocompatibility complex (MHC), with multiple SNPs strongly associated with CD4:CD8 ratio (rs2524054, p = 2.1 1028). The second region was centered within a cluster of genes from the Schlafen family and was associated with NK cell levels (rs1838149, p = 6.1 1014). The MHC association with CD4:CD8 replicated convincingly (p = 1.4 109) in an independent panel of 988 individuals. Conditional analyses indicate that there are two major independent quantitative trait loci (QTL) in the MHC region that regulate CD4:CD8 ratio: one is located in the class I cluster and influences CD8 levels, whereas the second is located in the class II cluster and regulates CD4 levels. Jointly, both QTL explained 8% of the variance in CD4:CD8 ratio. The class I variants are also strongly associated with durable host control of HIV, and class II variants are associated with type-1 diabetes, suggesting that genetic variation at the MHC may predispose one to immune-related diseases partly through disregulation of T cell homeostasis.
Resumo:
T cell-mediated cytotoxicity against Mycobacterium tuberculosis (MTB)-infected macrophages may be a major mechanism of specific host defense, but little is known about such activities in the lung. Thus, the capacity of alveolar lymphocyte MTB-specific cell lines (AL) and alveolar macrophages (AM) from tuberculin skin test-positive healthy subjects to serve as CTL and target cells, respectively, in response to MTB (H37Ra) or purified protein derivative (PPD) was investigated. Mycobacterial Ag-pulsed AM were targets of blood CTL activity at E:T ratios of > or = 30:1 (51Cr release assay), but were significantly more resistant to cytotoxicity than autologous blood monocytes. PPD- plus IL-2-expanded AL and blood lymphocytes were cytotoxic for autologous mycobacterium-stimulated monocytes at E:T ratios of > or = 10:1. The CTL activity of lymphocytes expanded with PPD was predominantly class II MHC restricted, whereas the CTL activity of lymphocytes expanded with PPD plus IL-2 was both class I and class II MHC restricted. Both CD4+ and CD8+ T cells were enriched in BL and AL expanded with PPD and IL-2, and both subsets had mycobacterium-specific CTL activity. Such novel cytotoxic responses by CD4+ and CD8+ T cells may be a major mechanism of defense against MTB at the site of disease activity.
Resumo:
B and T lymphocyte attenuator (BTLA) is a negative regulator of T cell activation, but its function in vivo is not well characterized. Here we show that mice deficient in full-length BTLA or its ligand, herpesvirus entry mediator, had increased number of memory CD8(+) T cells. The memory CD8(+) T cell phenotype resulted from a T cell-intrinsic perturbation of the CD8(+) T cell pool. Naive BTLA-deficient CD8(+) T cells were more efficient than wild-type cells at generating memory in a competitive antigen-specific system. This effect was independent of the initial expansion of the responding antigen-specific T cell population. In addition, BTLA negatively regulated antigen-independent homeostatic expansion of CD4(+) and CD8(+) T cells. These results emphasize two central functions of BTLA in limiting T cell activity in vivo.
Resumo:
Infiltration of cytotoxic T-lymphocytes in ovarian cancer is a favorable prognostic factor. Employing a differential expression approach, we have recently identified a number of genes associated with CD8+ T-cell infiltration in early stage ovarian tumors. In the present study, we validated by qPCR the expression of two genes encoding the transmembrane proteins GPC6 and TMEM132D in a cohort of early stage ovarian cancer patients. The expression of both genes correlated positively with the mRNA levels of CD8A, a marker of T-lymphocyte infiltration [Pearson coefficient: 0.427 (p = 0.0067) and 0.861 (p < 0.0001), resp.]. GPC6 and TMEM132D expression was also documented in a variety of ovarian cancer cell lines. Importantly, Kaplan-Meier survival analysis revealed that high mRNA levels of GPC6 and/or TMEM132D correlated significantly with increased overall survival of early stage ovarian cancer patients (p = 0.032). Thus, GPC6 and TMEM132D may serve as predictors of CD8+ T-lymphocyte infiltration and as favorable prognostic markers in early stage ovarian cancer with important consequences for diagnosis, prognosis, and tumor immunobattling.
Resumo:
Donor-derived CD8+ cytotoxic T lymphocytes (CTLs) eliminating host leukemic cells mediate curative graft-versus-leukemia (GVL) reactions after allogeneic hematopoietic stem cell transplantation (HSCT). The leukemia-reactive CTLs recognize hematopoiesis-restricted or broadly expressed minor histocompatibility and leukemia-associated peptide antigens that are presented by human leukocyte antigen (HLA) class I molecules on recipient cells. The development of allogeneic CTL therapy in acute myeloid leukemia (AML) is hampered by the poor efficiency of current techniques for generating leukemia-reactive CTLs from unprimed healthy donors in vitro. In this work, a novel allogeneic mini-mixed lymphocyte/leukemia culture (mini-MLLC) approach was established by stimulating CD8+ T cells isolated from peripheral blood of healthy donors at comparably low numbers (i.e. 10e4/well) with HLA class I-matched primary AML blasts in 96-well microtiter plates. Before culture, CD8+ T cells were immunomagnetically separated into CD62L(high)+ and CD62L(low)+/neg subsets enriched for naive/central memory and effector memory cells, respectively. The application of 96-well microtiter plates aimed at creating multiple different responder-stimulator cell compositions in order to provide for the growth of leukemia-reactive CTLs optimized culture conditions by chance. The culture medium was supplemented with interleukin (IL)-7, IL-12, and IL-15. On day 14, IL-12 was replaced by IL-2. In eight different related and unrelated donor/AML pairs with complete HLA class I match, numerous CTL populations were isolated that specifically lysed myeloid leukemias in association with various HLA-A, -B, or -C alleles. These CTLs recognized neither lymphoblastoid B cell lines of donor and patient origin nor primary B cell leukemias expressing the corresponding HLA restriction element. CTLs expressed T cell receptors of single V-beta chain families, indicating their clonality. The vast majority of CTL clones were obtained from mini-MLLCs initiated with CD8+ CD62L(high)+ cells. Using antigen-specific stimulation, multiple CTL populations were amplified to 10e8-10e10 cells within six to eight weeks. The capability of mini-MLLC derived AML-reactive CTL clones to inhibit the engraftment of human primary AML blasts was investigated in the immunodeficient nonobese diabetic/severe combined immune deficient IL-2 receptor common -chain deficient (NOD/SCID IL2Rnull) mouse model. The leukemic engraftment in NOD/SCID IL2Rnull was specifically prevented if inoculated AML blasts had been pre-incubated in vitro with AML-reactive CTLs, but not with anti-melanoma control CTLs. These results demonstrate that myeloid leukemia-specific CTL clones capable of preventing AML engraftment in mice can be rapidly isolated from CD8+ CD62L(high)+ T cells of healthy donors in vitro. The efficient generation and expansion of these CTLs by the newly established mini-MLLC approach opens the door for several potential applications. First, CTLs can be used within T cell-driven antigen identification strategies to extend the panel of molecularly defined AML antigens that are recognizable by T cells of healthy donors. Second, because these CTLs can be isolated from the stem cell donor by mini-MLLC prior to transplantation, they could be infused into AML patients as a part of the stem cell allograft, or early after transplantation when the leukemia burden is low. The capability of these T cells to expand and function in vivo might require the simultaneous administration of AML-reactive CD4+ T cells generated by a similar in vitro strategy or, less complex, the co-transfer of CD8-depleted donor lymphocytes. To prepare clinical testing, the mini-MLLC approach should now be translated into a protocol that is compatible with good manufacturing practice guidelines.
Resumo:
The specific mechanisms underlying the varied susceptibility of HIV-infected (HIV+) individuals to opportunistic infections (OI) are still incompletely understood. One hypothesis is that quantitative differences in specific T cell responses to a colonizing organism determine the development of an AIDS-defining OI. We evaluated this hypothesis for herpes simplex virus (HSV) infection, a common OI in HIV+ patients. Using limiting dilution analyses, the frequency of HSV-specific CD8+ cytotoxic T lymphocyte precursors (pCTL) and proliferative precursors were quantitated in peripheral blood mononuclear cells from 20 patients coinfected with HIV and HSV-2. The frequency of HSV-specific CD8+ pCTL in HSV+HIV+ individuals was significantly lower than in HSV+HIV individuals (1 in 77,000 vs. 1 in 6,000, P = .0005) and was not different than in HSV-HIV individuals (1 in 100,000, P = .24). HIV+ patients who suffered more severe genital herpes recurrences had significantly lower HSV-specific CD8+ pCTL frequencies than those patients with mild recurrences (1 in 170,000 vs. 1 in 26,000, P = .03). In contrast, no significant difference was seen in proliferative precursor frequencies between those patients with mild vs. severe genital herpes (1 in 3,800 vs. 1 in 6,600, P > .5). Quantitative differences in pCTL frequency to HSV appear to be the most important host factor influencing the frequency and severity of HSV reactivation in HIV+ patients. Studies to reconstitute such immunity, especially in people with acyclovir-resistant HSV, appear warranted.
Resumo:
Defining the rate at which T cells turn over has important implications for our understanding of T lymphocyte homeostasis and AIDS pathogenesis, yet little information on T cell turnover is available. We used the nucleoside analogue bromodeoxyuridine (BrdUrd) in combination with five-color flow cytometric analysis to evaluate T lymphocyte turnover rates in normal and simian immunodeficiency virus (SIV)-infected rhesus macaques. T cells in normal animals turned over at relatively rapid rates, with memory cells turning over more quickly than naive cells. In SIV-infected animals, the labeling and elimination rates of both CD4+ and CD8+ BrdUrd-labeled cells were increased by 2- to 3-fold as compared with normal controls. In normal and SIV-infected animals, the rates of CD4+ T cell BrdUrd-labeling and decay were closely correlated with those of CD8+ T cells. The elimination rate of BrdUrd-labeled cells was accelerated in both naive and memory T lymphocytes in SIV-infected animals. Our results provide direct evidence for increased rates of both CD4+ and CD8+ T cell turnover in AIDS virus infection and have important implications for our understanding of T cell homeostasis and the mechanisms responsible for CD4+ T cell depletion in AIDS.
