218 research outputs found
Genetic and Environmental Determination of Thymic Function in Healthy Immune Response
No full textLe thymus est un organe clé de l’immunité, permettant tout au long de la vie la production de cellules T naïves. L'involution thymique associée à l'âge est liée à une réduction de la masse tissulaire et de la cellularité thymique, ainsi que la perte de la structure tissulaire et de l’architecture normale conduisant à une baisse de la production de cellules T naïfs. Cependant, à l'exception de l'âge, les facteurs environnementaux ou génétiques susceptibles de régir la fonction thymique chez l'Homme restent mal connus. Nous avons caractérisé la variabilité de la fonction thymique chez 1000 adultes sains stratifiés par l’âge et par sexe sur la cohorte Milieu Intérieur, en utilisant la quantification des cercles d’excision (TRECs) dans le sang périphérique comme marqueur de la thymopoïèse. L'âge et le sexe sont les seuls facteurs non héritables identifiés qui affectent la fonction thymique. Les quantités de TREC diminuent avec l'âge étant plus élevée chez les femmes de tout âge. Surtout, une étude d'association pangénomique a révélé l’existence d’un variant génétique (rs2204985) dans le locus TCRA-TCRD, situé entre les segments géniques DD2 et DD3, l’allèle G étant associé à un niveau de TRECs supérieur à l’allèle A. Cette association a été validée dans une cohorte de réplication (cohorte MARTHA). La transplantation de cellules souches hématopoïétiques humaines de foie fetal avec le génotype GG dans des souris immunodéficientes est associée à une thymopoïèse accrue avec des TRECs plus élevés, une augmentation du nombre de thymocytes et aussi une plus grande diversité du répertoire TCRA-TCRD. Notre approche d’immunologie des populations a mis en évidence un variant génétique influençant la thymopoïèse l’adulte sain. Ceci pourrait avoir un impact direct en médecine dite de précision dans les domaines du vieillissement et de la vaccination, en transplantation de cellules souches hématopoïétiques, ainsi qu’en autoimmunité. Ces travaux conduisent également à étudier plus en détail les mécanismes de la thymopoïèse précoce et des réarrangements du locus TCRATCRD.The thymus is a vital organ for homeostatic maintenance of the peripheral immune system. Age-associated thymic involution is associated with a reduction in tissue mass and thymic cellularity, loss of tissue structure and abnormal architecture leading to a decline in naïve T cell output. However, with the exception of age, the underlying parameters that govern thymic function in healthy humans remain to be defined. We characterized the variability of thymic function among 1000 age- and sex-stratified healthy adults of the Milieu Intérieur cohort, using quantification of TRECs in peripheral blood T cells as a surrogate marker of thymopoiesis. Age and sex were the only nonheritable factors identified that affect thymic function. TREC amounts decreased with age and were higher in women compared to men of all ages. In addition, a genome-wide association study revealed a common variant (rs2204985) within the T cell receptor TCRA-TCRD locus, between the DD2 and DD3 gene segments, which associated with TREC amounts. This association was validated in a replication cohort (MARTHA cohort). Strikingly, transplantation of human hematopoietic stem cells with the rs2204985 GG genotype into immunodeficient mice led to thymopoiesis with higher TRECs, increased thymocyte counts, and a higher TCR repertoire diversity. Our population immunology approach revealed a genetic locus that influences thymopoiesis in healthy children and adults, with potentially broad implications in precision medicine, especially in aging and vaccines, hematopoietic stem cell transplantation and autoimmunity. This study leads also to further study the precise mechanisms of TCRA-TCRD rearrangements at early steps of thymopoiesis
Immune Profile after Autologous Hematopoietic Stem Cell Transplantation for Autoimmune Diseases: Where Do We Stand?
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Contributions a l'etude structurale et fonctionnelle des antigenes HLA de la classe I: l'exemple de l'antigene HLA-B27
No full textSIGLEINIST T 73157 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Thymic function recovery after unrelated donor cord blood or T-cell depleted HLA-haploidentical stem cell transplantation correlates with leukemia relapse
No full textUse of alternative donors/sources of hematopoietic stem cells (HSC), such as cord blood (CB) or HLA-haploidentical (Haplo) related donors, is associated with a significant delay in immune reconstitution after transplantation. Long-term T-cell immune reconstitution largely relies on the generation of new T cells in the recipient thymus, which can be evaluated through signal joint (sj) and beta T-cell-Receptor Excision Circles (TREC) quantification. We studied two groups of 33 and 24 children receiving, respectively, HSC Transplantation (HSCT) from an HLA-haploidentical family donor or an unrelated CB donor, for both malignant (46) and non-malignant disorders (11). Relative and absolute sj and beta-TREC values indicated comparable thymic function reconstitution at 3 and 6 months after the allograft in both groups. Compared to children with non-malignant disorders, those with hematological malignancies had significantly lower pre-transplantation TREC counts. Patients who relapsed after HSCT had a significantly less efficient thymic function both before and 6 months after HSCT with especially low beta-TREC values, this finding suggesting an impact of early intra-thymic T-cell differentiation on the occurrence of leukemia relapse
Immunité anti-tumorale à l'heure de l'imatinib dans la leucémie myéloïde chronique
No full textPARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF
Molécules du CMH, bactéries et auto-immunité (contributions à l'étude des arthrites associées à HLA-B27)
No full textPARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF
How to improve immune reconstitution in allogeneic hematopoietic stem cell transplantation?
No full textAllogeneic haematopoietic stem cell transplantation (allo-HSCT) is widely used in the treatment of haematological malignancies as a form of immunotherapy acting through a graft-versus-leukemia (GvL) reaction. This curative allogeneic response can be associated with severe drawbacks, such as frequent and severe graft-versus-host disease (GvHD) and a long-lasting immunodeficiency, especially now with the development of innovative strategies such as umbilical cord blood transplantation or transplants from haplo-identical family donors (Haplo-HSCT). In the long-term follow-up of these patients, severe post-transplant infections, relapse or secondary malignancies may be directly related to persistent immune defects.Reconstitution of the different lymphocyte populations (B, T, NK, NKT) and antigen presenting cells of myeloid origin (monocytes, macrophages and dendritic cells) should be considered not only quantitatively but especially qualitatively, in terms of functional subsets. Immune deficiency leading to an increased susceptibility to infections lasts for more than a year. Although infections that occur in the first month mostly result from a deficiency in both granulocytes and mononuclear cells (MNC), later post-engraftment infections are due to a deficiency in MNC subsets, primarily CD4 T-cells and B-cells. T-cell reconstitution has been extensively studied because of the central role of T-cells in mediating both GvHD, evidenced by the reduced incidence of this complication following T-Cell depletion, and a GvL effect as shown by DLI. In the recent years there has been renewed interest in the role of NK-cells, especially in the context of Haplo-HSCT, and in B-cell reconstitution.This Frontiers Research Topic will provide state of the art knowledge of the mechanisms of immune reconstitution in an allogeneic environment, in order to improve monitoring and therapeutic intervention in allo-HSCT patients
Immune reconstitution after hematopoietic stem cell transplantation: gaining experience without losing naivety
No full textMécanismes de la reconstitution lymphocytaire natural killer après allogreffe de cellules souches hématopoïétiques chez l'homme
No full textPARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF
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