Le syndrome de Sézary (SS) est un variant leucémique et érythrodermique de lymphomes T cutanés épidermotropes. Son diagnostic repose à la fois sur des critères cliniques, la présence de lymphocytes T à noyau atypique cérébriforme sur un frottis sanguin et la mise en évidence dans la peau, les ganglions et le sang d’un clone lymphocytaire T CD4+. Notre laboratoire a identifié KIR3DL2 comme premier marqueur membranaire spécifique des cellules tumorales de Sézary. KIR3DL2 peut ainsi être utilisé pour le diagnostic et le suivi des patients atteints du SS. Toutefois, aucune étude n’a démontré de lien entre sa structure de récepteur inhibiteur et sa fonction dans les lymphocytes tumoraux de Sézary, et plus particulièrement son implication possible dans les mécanismes régulant la prolifération et/ou la résistance à l’apoptose des cellules tumorales.Au cours de ce travail deux axes ont été développés :- Un premier axe visant à mieux comprendre la fonction de KIR3DL2 et les mécanismes de signalisation intracellulaire initiés lors de son engagement par l’anticorps AZ158 dans les lymphocytes T tumoraux de Sézary. Nos résultats mettent en évidence un rôle de corécepteur inhibiteur pour KIR3DL2 dans les cellules tumorales de Sézary. En effet, l’engagement de KIR3DL2 inhibe la prolifération et l’AICD induites par la stimulation CD3, cette inhibition étant corrélée à une modulation négative des signaux médiés par le TCR. Ainsi, KIR3DL2 ne se comporte pas comme une unité de signalisation indépendante dans les cellules tumorales de Sézary, contrairement à ce qui est observé dans les cellules NK.- Un second axe portant sur l’évaluation d’une nouvelle fonction de KIR3DL2 comme récepteur pour les ODN CpG. Ainsi, nous rapportons pour la première fois un effet direct de l’ODN CpG sur les cellules tumorales T CD4+ de Sézary. En effet, nous avons observé un effet apoptotique de l’ODN CpG-C caspases-dépendant sur les lignées et les cellules tumorales circulantes. De plus, le traitement des cellules tumorales de patients Sézary avec l’ODN CpG-C conduit à une inhibition de l’activation constitutive du facteur de transcription STAT3.La réalisation de cette étude a permis de mieux comprendre la fonction et les mécanismes initiés à partir de KIR3DL2 dans les cellules tumorales T CD4+ de Sézary. De plus, ce travail ouvre de nouvelles perspectives thérapeutiques basées sur le ciblage direct et spécifique des cellules tumorales de Sézary pouvant être associé à une stimulation des acteurs immuns grâce à l’action des ODN CpG. / Sézary syndrome (SS) is an aggressive leukemic and erythrodermic variant of cutaneous T-cell lymphoma. It is characterized by the presence of a clonal CD4+ T lymphocyte population in the skin, lymph nodes and peripheral blood. Our laboratory has previously identified the NK cell receptor KIR3DL2 as a valuable diagnostic and prognostic marker for the detection of the tumoral T cell burden of Sézary syndrome patients. However, the function of this receptor on the malignant T lymphocyte population remained unexplored. The specific expression of KIR3DL2 by SS patients malignant cells prompted us to investigate its possible influence on mechanisms regulating the tumoral cells outgrowth and apoptosis process.To this aim, two axes were developed. The first axis aimed to highlight the function of KIR3DL2 on the malignant T lymphocyte population and to elucidate the intracellular signaling mechanisms initiated by engagement of the receptor with the monoclonal antibody AZ158. Our results show that KIR3DL2 can exert an inhibitory co-receptor function in malignant Sézary cells. Indeed, triggering of KIR3DL2 inhibits the CD3-mediated proliferation and cell death of the CD4+ KIR3DL2+ cells, this inhibition being correlated to a down-modulation of the TCR-mediated signals. Thus, KIR3DL2 does not behave as an independent signaling unit in Sézary cells, unlike NK cells.The second axis aimed to evaluate a new function of KIR3DL2 as CpG ODN receptor. We show for the first time a direct effect of CpG ODN on tumoral CD4+ T Sézary cells. Thus, we observed a caspase-dependent apoptotic effect of CpG ODN-C on Sézary cell lines and circulating malignant T cells. This process of cellular death is correlated to a dephosphorylation of the transcription factor STAT3, which is found constitutively phosphorylated and activated in Sézary cells.This study has provided new insights into the function and the intracellular signaling pathways initiated by KIR3DL2 in malignant Sézary T cells. Furthermore, this work opens new therapeutic perspectives based on the direct and specific targeting of tumor cells that could be associated to immune cell stimulation through the use of ODN CpG.

Thesis advisor: Thomas Chiles / Thesis advisor: James Kim / The purpose of this thesis is to describe some of the research I conducted in Dr. Markmann’s laboratory at Massachusetts General Hospital in the field of transplantation immunology. The first portion provides background information on the immune system and its different components, eventually providing an in-depth look at regulatory T cells, and their role in transplant immunology. The second portion of the thesis is dedicated to my experiments. This part presents the materials and methods used, the previous findings that led to my experiments, the data analysis and results, and a conclusive discussion. The research I did that is included in this thesis pertains to regulatory T cells. It is believed that a potential pathway to prolonging allograft survival is to drive antigen-specific CD4+Foxp3- T cells to convert to CD4+Foxp3+ T cells. I studied the effects of retinoic acid (RA) and anti-CD45RB treatment on Foxp3 expression in CD4+ T cells. These studies were done using different lines of transgenic mice that provided models of antigen-specificity. My in vitro data demonstrated that RA is capable of boosting TGF-β-mediated Foxp3 upregulation in a synergistic manner and that anti-CD45RB is also able to increase Foxp3 expression. In vivo RA experiments were inconclusive, and due to some misfortune and time constraints in vivo anti-CD45RB experiments were not conducted. Research funded by the following sources: 2R56AI048820, 5R01AI057851, and 5K01DK079207. / Thesis (BS) — Boston College, 2011. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: College Honors Program. / Discipline: Biology.

The core of the doctoral thesis "Regulation of signal transduction by leukocyte surface proteins" consists of three publications in international peer-reviewed journals dealing with leukocyte signaling both at the level of individual signaling pathways and in the context of a multicellular organism. Most attention is paid to signaling via the T cell receptor (TCR), which plays a central role in the development and function of T cells and represents a key signaling pathway for proper function of the adaptive component of the immune system. Transmembrane protein tyrosine phosphatase CD148 was considered a negative regulator of TCR signaling through dephosphorylation of LAT and PLCγ1 proteins. This study brings evidence that CD148 is able to modulate signaling also at the level of Lck, both positively and negatively. The net effect of CD148 activity on the TCR signaling is determined by the intracellular biochemical context, notably, the presence of another tyrosine phosphatase CD45. The second project dealt with the characterization of a transmembrane adaptor protein PRR7. This adapter inhibits TCR signaling via down-regulation of the intracellular Lck and cell surface TCR levels. The research concerning the signaling in the environment of a multicellular organism is represented by the analysis of...

Acredita-se que a placa dento-bacteriana seja primordial na iniciação do processo de inflamação periodontal. Entretanto, os mecanismos exatos responsáveis pela progressão da doença periodontal ainda não foram completamente elucidados. Além disso, as bases biológicas que ditam a susceptibilidade do hospedeiro ainda permanecem desconhecidas. Portanto, o presente estudo procurou investigar diferenças na expressão gênica de sítios com periodontite. Para tanto, foi utilizada a tecnologia de microarray focado para examinar a expressão de 288 genes relacionados à apoptose, resposta de células T e inflamação. RNA total foi extraído de amostras de tecido gengival e sangue de indivíduos com periodontite crônica (N=10) e de indivíduos periodontalmente saudáveis (N=4). RNA total foi então convertido em cRNA, marcado e hibridizado em lâminas de microarray. Após a exposição, os genes marcados foram quantificados e o nível de expressão genética nas amostras gengivais dos pacientes periodontais foi comparado com o nível de expressão observado no sangue desses mesmos indivíduos, e também com o nível da expressão genética no tecido gengival dos indivíduos sem doença periodontal. Para validação dos resultados dos genes selecionados (p< ou = 0,05 e no mínimo mudança de 2 vezes na expressão) foram submetidos à análise pela técnica de PCR em tempo real. O valor de p das comparações foi calculado por meio do teste t bicaudal. Os dados do microarray, confirmados por PCR em tempo real, demonstraram um total de 8 genes com baixa expressão (log2 < ou= -1 e p<ou= 0,05) e 4 genes com elevada expressão (log2 < +1 e p<ou= 0,05). Entre eles foram detectados 4 genes anti-apoptose (BCL-2, BCL2L1, BAG3 e BAFAR), 2 receptores de citocinas (IL12RB1 e IL17RA), receptor de proteína G (GPR44) e o fator nuclear de células T ativadas (NFATC1). Adicionalmente, os resultados demonstraram 3 genes com expressão elevada, uma citocina (IL-6), uma quimiocina (IL-8) e um membro da família FOS (FOSL-1). As análises da expressão genética por microarray e PCR em tempo real realizadas no presente estudo identificaram uma série de genes candidatos que podem estar relacionados à doença periodontal. A desregulação da expressão desses genes pode contribuir para a severidade desta doença. / It is widely believed that pathogenic bacteria provide the initial trigger in periodontal disease. However, the exact pathogenic mechanisms responsible for the progression of periodontal disease remain unclear. Moreover, the biologic basis dictating the susceptibility to disease has not been elucidated. Therefore, the present study sought to investigate the expression of genes altered in periodontal disease sites. To that aim, a focused microarray system was utilized to examine the expression of 288 genes related to apoptosis, T cell response and inflammation. Total RNA was extracted from gingival tissue and peripheral blood of periodontitis (N=10) and nonperiodontitis (N=4) subjects. The RNA was converted to cRNA, labeled and hybridized to oligonucleotide microarray plates. Following exposure, the positively labeled genes were quantified and the level of expression within periodontitis gingival was compared to the PB of the same subjects, as well as with GT of NP subjects. To validate the results the selected genes (p<or = 0.05 and at least 2 fold change) were subjected to real-time PCR. The p-value of the comparisons was calculated using a 2-tailed T-test. The microarray results and real-time PCR validation showed that 8 genes were downregulated (p<0.05 and log2 <or = -1). Among these, 4 anti-apoptotic genes (BCL-2, BCL2L1, BAG3 and BAFAR), 2 cytokine receptors (IL12RB1 and IL17RA), a G-protein-coupled receptors (GPR44) and a nuclear factor of activated T cells (NFATC1) were detected. In addition, the results showed 3 upregulated genes (p<0.05 and log2 < or = +1), one cytokine (IL-6), one chemokine (IL-8) and one FOS family member (FOSL1). The combined use of oligonucleotide microarrays and realtime PCR identified a number of candidates genes that can be related to the pathogenesis of periodontal disease, and dysregulation in the expression of these genes may contribute to the progression of periodontal disease.

Notre équipe s’intéresse à la différenciation des cellules souches hématopoïétiques (CSH) vers la lignée des lymphocytes T. Contrairement aux autres lignées sanguines, qui se développent dans la MO, les progéniteurs des lymphocytes T doivent terminer leur différenciation dans le thymus. Ma thèse a un double objectif: 1) caractériser les progéniteurs candidats à la reconstitution T pour établir leur contribution à celle-ci et 2) identifier les stades initiaux de la reconstitution T. Nous avons mis en évidence que seul le progéniteur multipotent au stade 3 (MPP3 : Lin- Sca1+ c-Kit+ VCAM1- Flt3+) et le progéniteur commun lymphoïde (CLP : Lin- Sca1lo c-Kitlo IL7Ra+ Flt3-) circulent dans le sang. De plus, nos résultats montrent que les gènes impliqués dans l’engagement T et dans la migration thymique sont uniquement exprimées par la population MPP3 circulante. Cette population est la plus compétente pour générer des précurseurs T (pré-T). Au contraire, les CLPs sont plus efficaces pour la production de différents types de cellules B de la rate. Par la suite, mon projet a consisté à déterminer la proportion de progéniteurs contribuant à la reconstitution T. En effet, le thymus peut être colonisé par différents progéniteurs (LMPP, Lymphoid-primed Multipotent Progenitors, et CLP), mais leur contribution dans la différenciation T reste inconnue et est sujet à controverse. Nous avons utilisé une stratégie innovante pour suivre les progéniteurs avec une séquence d’ADN ou Code Barre (CB) intégrée dans le génome par un vecteur viral. Les résultats préliminaires indiquent qu'une forte fréquence de CBs en provenance de la population LMPP est retrouvée dans le compartiment T thymique. Dans la dernière partie, nous nous sommes intéressés à élucider le premier stade de différenciation T dans le thymus et l’identité cellulaire et moléculaire des premiers migrants thymiques pour comprendre le délai de génération de ce compartiment. La population thymique la plus immature (TN1 : Lin- CD44+ CD25+) présente différentes sous-population selon l’expression de c-Kit et de CD24 chacune de ces différentes populations TN1 pourrait participer à cette reconstitution T. Leur analyse moléculaire montre deux lignées cellulaire selon l’expression de Pu1, dans les TN1 c-Kit+, et de Cd3e, dans la sous-population TN1e (CD24- c-Kit-). En parallèle, pour éclaircir le processus d’engagement des cellules T, ces sous-populations de TN1 ont été étudiées dans différentes conditions de reconstitution : une reconstitution endogène suite à une irradiation sub-létale et une exogène après greffe de MO. Nos résultats permettent de préciser les caractéristiques, propres aux progéniteurs thymiques au stade TN1, qui leur confèrent des compétences à se différencier et à proliférer plus efficacement. Après irradiation ou greffe de MO, le compartiment TN1 est constitué de cellules à faible capacité proliférative. Le thymus en état de reconstitution génère tout d’abord des cellules présentatrice d’antigène (APC) puis les cellules T. Ces deux points suggèrent que les cellules à faible capacité proliférative seront plus aptes à générer des cellules APC plutôt que des cellules T. Il reste à déterminer quel environnement thymique permet le maintien des cellules à faible capacité proliférative, notamment, par rapport à l’expression de Delta-4, de l’IL7 et du ligand c-Kit. Cela va permettre l'identification de facteurs favorisant leur induction et leur expansion. Il nous semble aussi intéressant d’étudier la contribution de la population à faible capacité proliférative, TN1 CD24- c-Kit-, dans la différenciation T. / Within the hematopoietic system, hematopoietic stem cells (HSCs) are the only cells with the functional capacity to give rise to all blood lineages and to self-renew for life. These properties and the ability of HSCs to engraft conditioned recipients permitted to apply these cells in regenerative medicine. Like all blood lineages, T cells develop from bone marrow HSC. However, T lineage development requires many weeks, three separate anatomical sites (bone marrow, blood and thymus), many environments and the loss of multiple alternative lineage potentials. Many questions remain to be clarified during this process: do all progenitors have an intrinsic feature of T cell development ? How does this intrinsic potential express ? How the bloodstream contributes to the T cell development ? Which BM progenitor contributes to T cell reconstitution ? What are the characteristics of T cell reconstitution ? We have shown that only the multipotent progenitor in stage 3 (MPP3: Lin- Sca1+ c-Kit+ VCAM1- Flt3+) and a subset of the common lymphoid progenitor (CLP Flt3-: Lin- Sca1lo c-Kitlo IL7Ra+ Flt3-) circulate in the blood. Moreover, our results show that T cell engagement and thymic migration genes are modulated in the circulation, especially up-regulated in the MPP3 circulating subset. This population present a T cell intrinsic potential and is the most competent to generate precursors T (pre-T). On the contrary, CLPs subsets are more efficient for the production of different B cells. Lymphoid primed multipotent progenitor (LMPP, MPP Flt3+) and CLP subsets' respective contributions to the T cell pathway are still being hotly debated. Multiple progenitors in BM have been shown to possess T lineage potential when placed in the thymus. However, it is unlikely that all of them contribute physiologically to thymopoiesis. It was claimed that CLPs are the earliest lymphoid committed progenitor from which B and T lineage cells arise. However, the concept that the CLP is the progenitor population through which all T lymphocytes are derived has been challenged. More specifically, which BM progenitor contribute to the T cell reconstitution ? In order to answer this question, we used an innovative strategy to follow the progenitors with a DNA sequence or Barcode (BC) integrated into the genome by a viral vector. Preliminary results indicate that a high frequency of BCs from the LMPP population is found in the T cell lineage. Finally, we characterized the first stage of T cell differentiation in the thymus by a cellular and molecular asses. We show that the most immature thymic population (TN1: Lin- CD44+ CD25+), at the molecular level, contain two separate lineages, detected by Pu1 (TN1a and b) or CD3e (TN1e) gene expression. In order to clarify the process of T-cell involvement, these TN1 subsets have been studied under different reconstitution conditions: endogenous reconstruction following sub-lethal irradiation and exogenous after bone marrow (BM) graft. In these conditions, the TN1 compartment presents cells with low proliferative capacity and that antigen presenting cells (APC) are the first mature population and thus T cells are generated in second place. These two points suggest that cells with low proliferative capacity will be more apt to generate APC cells rather than T cells. It remains to be determined which thymic environment permits the maintenance of cells with a low proliferative capacity, in particular, with respect to the expression of Delta-4, IL7 and the c-Kit ligand. This will allow the identification of factors favoring their induction and their expansion. It also seems interesting to study the contribution of the population with low proliferative capacity, TN1 CD24- c-Kit-, in the T cell differentiation.

Les lymphomes T périphériques (ou PTCL) sont des lymphomes malins non Hodgkiniens ayant pour cellules d’origine des lymphocytes T (LT) ou Natural Killer matures. Ces lymphomes sont rares, hétérogènes et méconnus. Des arguments issus de la littérature suggérant l’implication de la stimulation chronique du récepteur T à l’antigène (TCR) dans la transformation des LT, nous ont conduits à développer un modèle murin basé sur la stimulation chronique du TCR pour adresser spécifiquement cette question. Dans ce modèle, le transfert de LT p53-/- dans des souris CD3e-/- entraine l’apparition de lymphomes T périphériques (PTCL) clonaux dans 60% des cas avec une médiane de survenue de 230 jours alors que les souris transférées avec des LT wt ne développent pas de lymphomes. Ces PTCL présentent un phénotype T effecteur-mémoire CD62LLo-CD44hi-CD122lo-CD25lo ainsi qu’une profonde downrégulation de l’expression des gènes impliqués dans la voie du TCR illustrant l’impact de la stimulation chronique dans la lymphomagénèse. L’étude de ces lymphomes a révélé qu’ils ne dépendent plus, pour la plupart, de l’engagement du TCR pour leur survie et qu’ils acquièrent des caractéristiques « innate-like » avec notamment l’expression de récepteurs NK inhibiteurs (NKiR) et de récepteurs NK activateurs (NKaR) ainsi que des protéines adaptatrices DAP12 et FceRIg. Cette expression est associée à celle de Syk et PLC?2, impliquées dans la signalisation des NKaR. Nous montrons que les NKaR et leurs voies de signalisation associées sont fonctionnelles et participent à la survie des cellules lymphomateuses, le blocage de certains NKaR retardant notamment le développement lymphomateux in vivo. Nous avons par la suite exploré l’expression des NKR, de Syk et de PLCg2 au sein des PTCL humains et nous montrons ou confirmons que certaines entités expriment des panels variés de NKR ainsi que les effecteurs Syk et PLCg2 suggérant l’existence de mécanismes de lymphomagénèse similaires à ceux identifiés dans notre modèle au sein d’un certain nombres de PTCL humains / Peripheral T-cell lymphomas (PTCL) are rare non Hodgkin malignant lymphomas emerging from mature T or NK cells. PTCL are highly heterogeneous and mainly misunderstood. As several evidences pointed the potential role of TCR chronic stimulation in human T-cell lymphomagenesis, we developed a murine model based on chronic TCR stimulation to address this question. In this model, transfer of p53-/- T-cells into T-cell deficient mice (CD3e-/-) triggered PTCL development in 60% of cases with a median survival of 230 days while transfer of wt T-cells in CD3e-/- mice did not lead to PTCL development. These PTCL exhibited an effector-memory phenotype CD62LLo-CD44hi-CD122lo-CD25lo associated with a dramatic downregulation of TCR pathway genes expression consistent with a chronic TCR stimulation highlighting it’s implication in lymphomagenesis. The analysis of these PTCL revealed that a large majority of cases (80%) do not depend anymore on TCR stimulation for their growth and survival and that they acquire innate-like features with expression of inhibitory NKR (NKiR) and activating NK receptors (NKaR) as well as the adaptor proteins DAP12 or FceRIg. Expression of these receptors is associated with the expression of SYK and PLC?2, which are classical key effectors downstream of NKaR. We show that these NKaR are functional and can mediate TCR-independent activation in mPTCL and that this signaling is involved in cell survival/proliferation as in vivo blockade of NKG2D and NKp46 delays PTCL development in PTCL transplantation experiments. In parallel, we studied NKR, Syk and PLCg2 expression in human PTCL and found that some entities express a large range of these receptors as well as Syk and PLCg2, suggesting similar lymphomagenesis mechanisms in some human PTCL

As infecções humanas com a filaria Mansonella ozzardi ocorrem em focos situados em regiões tropicais e subtropicais da América Central e do Sul e frequentemente coexistem com outras doenças endêmicas tropicais. Na Amazônia brasileira, as infecções são geralmente assintomáticas e a maior parte delas, consequentemente, deixam de ser diagnosticada. As filarioses crônicas, geralmente não tratadas, podem criar um ambiente imunorregulador, caracterizado pela expansão de linfócitos T produtores de IL-10, que mediam a supressão de respostas proliferativas de células T frente a antígenos específicos bem como a antígenos não-relacionados. Neste trabalho, utilizamos marcadores de ativação celular (CD69 e HLA-DR) e de atividade reguladora (CD39, CTLA-4, OX40, GITR, LAG3, PD-1, LAP-TGF-&#946; e TNFRII) para caracterizar populações de células mononucleares de sangue periférico (PBMCs) em indivíduos infectados por M. ozzardi bem como em controles saudáveis de uma área endêmica deste parasito na Amazônia Brasileira. A análise de PBMCs, por citometria de fluxo multiparamétrica de 49 pacientes infectados por M. ozzardi, mostrou que pacientes e controles apresentam proporções similares de Treg clássicas circulantes, no entanto, indivíduos infectados apresentam um aumento da proporção de células CD4+ e células T reguladoras (Tregs) que expressam a molécula CD39. Células Treg CD39+ parecem definir uma população distinta entre as Treg, pois ao compararmos os marcadores de regulação e ativação entre Tregs CD39+ e CD39- encontramos proporções aumentas destes marcadores nas Treg CD39+. O bloqueio dessa molécula em condições de reestimulo celular aumenta a produção de citocinas inflamatórias e diminui a produção de IL-10 confirmando seu papel regulador. / Human infections with the filarial parasite Mansonella ozzardi are common in areas of tropical and subtropical Central and South America and often coexist with other endemic tropical diseases, such as malaria. In the Amazonian Basin of Brazil, infections are typically asymptomatic; most of them will remain undiagnosed. These chronic, untreated filarial infections are potentially associated with a regulatory immune environment, dominated by IL-10-producing T-cells, which mediate the suppression of T-cell proliferation in response to filarial and non-related antigens. Here, we used markers of cell activation (CD69 and HLA-DR) and regulatory activity (CD39, CTLA-4, OX40, GITR, and TNFRII) to characterize peripheral-blood mononuclear cell (PBMCs) subpopulations in individuals infected with |M. ozzardi and in healthy controls living in an area of M. ozzardi endemicity in the Brazilian Amazon. Multiparameter flow cytometry analysis of PBMCs from 49 malaria patients showed that patients and controls have similar proportions of classic circulating Tregs, however, the proportion of CD4 + cells and Tregs expressing the CD39 (an ectonucleotidase that regulates the balance of immune responses through Phosphohydrolysis of ATP, an inflammatory molecule in adenosine, an anti-inflammatory molecule), is increased in infected patients. CD39+Treg cells seem to define a distinct population among Tregs, compare activation and regulatory markers between CD39+ and CD39- Tregs - we found increased proportions of these markers in the CD39+ Tregs. Blocking this molecule under cellular restimulation conditions increases production of inflammatory cytokines and decreases IL-10 production, improving its regulatory role.

"Sin Nombre virus is a hantavirus first recognized in New Mexico in 1993. This virus is responsible for causing Hantavirus Pulmonary Syndrome, an acute, life threatening illness characterized by pulmonary edema, capillary leaking, and extreme respiratory distress. CD8+ cytotoxic T-cell lines specific for Sin Nombre virus were isolated from the peripheral blood mononuclear cells (PBMC) of a donor (NM3) who was naturally infected with the Sin Nombre virus, and has survived hantavirus pulmonary syndrome (HPS). Cytotoxic T lymphocyte (CTL) assays showed that one of these cell lines, 10K, specifically recognizes a nine amino acid epitope, TAHGVGIIP (amino acids 664-672 of the precursor GPC protein), which is located in the G2 protein after cleavage. Another cell line, 10c27, specifically recognized an eight amino acid epitope, AHGVGIIP (amino acids 665-672 of the precursor GPC protein), located in the G2 protein after cleavage. Using polymerase chain reaction (PCR) and CTL assays, the recognition of these epitopes was shown to be restricted by the B35.01 Class 1 human leukocyte associated antigen (HLA) allele. This information will be useful in creating a vaccine for use in immunizing people against the Sin Nombre hantavirus, as well as elucidating the pathogenesis of this disease. "

RNA binding proteins (RBPs) have been found to be frequently involved in neurodegenerative diseases (Ash 2014). Mutations in RBPs cause amyotrophic lateral sclerosis (ALS), spinocerebellar ataxia, frontotemporal dementia (FTD) and myopathies (Ash 2014), and recent studies suggest that aggregation of RBPs are a pathological feature frequently encountered in tauopathies (Vanderweyde 2016). Emerging studies on neurodegenerative diseases are now showing an increasingly important role for tau in regulating the biology of RBPs. In this study, we examine findings that show that reducing the RBP T-cell intracellular antigen 1 (TIA1) in vivo not only protects against neurodegeneration, but also prolongs the survival rate in transgenic P301S tau mice. Furthermore, the reduction of TIA1 decreases the number and size of granules co-localizing with stress granule markers, and inhibits the accumulation of tau oligomers, although at the expense of an increased number of neurofibrillary tangles. However, despite the observed increase in neurofibrillary tangles, this TIA1 reduction still manages to increase neuronal survival, rescue behavioral deficits and prolong lifespan. The in vivo data presented in this study suggests an important role for TIA1 in mediating toxicity and provides evidence that RBPs orchestrate a pathway to tau aggregation and the resulting neurodegeneration.

Les leucémies aiguës lymphoblastiques T (LAL-T) sont caractérisées par la prolifération maligneincontrôlée de précurseurs lymphoïdes T bloqués dans la différenciation. Les stades d’arrêt dematuration observés dans les LAL-T reproduisent fidèlement les différentes étapes de la maturationthymique humaine. Ainsi nous avons montré que le facteur de transcription myéloïde CEBPA, expriméuniquement dans les précurseurs thymiques les plus immatures (ETP), est réprimé par un mécanismed’hyperméthylation dans les LAL-T à l’exception des formes les plus immatures. Il est aujourd’huicommunément admis que les LAL-T constituent une pathologie dite « multi-hits » où les oncogènesde type A affectent la différenciation tandis les oncogènes de type B sont impliqués dans la régulationdu cycle cellulaire, l’auto-renouvellement et/ou l’engagement dans la lignée T. La voie de signalisationde NOTCH, cruciale pour le développement lymphoïde T, est constitutivement activée par la survenuede mutations des gènes NOTCH1 et/ou FBXW7 (N/F) dans environ 60% des LAL-T. La valeurpronostique de ces mutations est controversée. Dans notre travail, nous avons montré que lesmutations de N/F sont plus fréquentes dans les LAL-T arrêtées à un stade de maturation cortical etconfèrent un bon pronostic qui semble toutefois dépendre de la chimiothérapie administrée. Grâce àl’étude de cette large cohorte de LAL-T nous avons pu également établir la fréquence de l’anomalieoncogénique CALM-AF10. Cette dernière est très fréquente dans les LAL-T qui se développent àpartir des ETP dites de mauvais pronostic. Nous avons montré que c’est la présence de l’anomalieCALM-AF10 qui confère le pronostic défavorable à ce sous-type de LAL-T. Contrairement à lalittérature nous n’avons pas retrouvé de valeur pronostique liée à la surexpression des gènes ERG etBAALC. L’étude des anomalies génétiques des LAL-T permet de mieux comprendre l’oncogénèse etd’identifier les anomalies avec une valeur pronostique. L’intérêt de ces travaux est d’apporter une aideaux cliniciens pour une stratification thérapeutique adaptée afin de donner les meilleures chances desurvie aux patients. / T-cell acute lymphoblastic leukemia (T-ALL) are lymphoid neoplasms characterized by theproliferation of malignant T lymphoblasts arrested at early stages of maturation. Maturation arrest in TALLmirrors normal lymphopoiesis. Thus we have shown that the myeloid transcription factor CEBPA,expressed only in the most immature thymic precursors (ETP), is commonly repressed byhypermethylation in T-ALL with the exception of the most immature subset. It is now widely acceptedthat T-ALL is a “multi-hits” disease where the type A oncogenes affect the differentiation while type Boncogenes are involved in cell cycle regulation, self-renewal and T-cell commitment. The Notchsignaling pathway, crucial for T cell development, is constitutively activated by the occurrence ofmutations in NOTCH1 and /or FBXW7 (N / F) genes in approximately 60% of T-ALL. The prognosticvalue of these mutations is controversial. In our study, we showed that N/F mutations are morefrequently observed in T-ALL arrested at a cortical stage of maturation and confer a good prognosiswhich seems to be influenced by the therapeutic regimen. In this large cohort of T-ALL we could alsodetermine the frequency of the CALM-AF10 oncogenic abnormality. The latter is very common in TALLdeveloped from ETP wich are of very poor prognosis. We have shown that this is the presence ofCALM-AF10 which confers the poor prognosis in this subtype of T-ALL. Contrary to the litterature wedid not find any prognostic value associated with the overexpression of ERG and BAALC genes. Thestudy of genetic abnormalities in T-ALL provides a better understanding of oncogenesis and identifyabnormalities with prognostic value. The interest of this work is to assist clinicians for an efficienttherapeutic stratification to overcome the poor outcome of T-ALL patients.