Immunodéficience | EPFL Graph Search

Un déficit immunitaire, une immunodéficience (IMD) ou une immunodépression, sont une situation pathologique liée à l'insuffisance d'une ou de plusieurs fonctions immunologiques. On parle aussi de « dysfonctionnement immunitaire ». La pandémie de SIDA est à l'origine d'une augmentation du nombre de cas d'immunodépression (en Afrique du Sud notamment). Dans les pays riches, dont en France, le nombre de patients immunodéprimés ou « immunosupprimés » est également en hausse régulière, d’une part en raison de l’amélioration du pronostic global du cancer, et d’autre part de l’utilisation croissante d’immunosuppresseurs pour d’autres maladies (auto-immunes), ainsi qu’en raison d’un nombre croissant de transplantations d’organes. Ces patients ont comme première cause d’admission en réanimation des infections sévères (atteintes respiratoires le plus souvent). Le déficit immunitaire est dit « primitif » quand le patient le présente dès sa naissance ou l’a acquis dans l’enfance, il est dit « se

Long-Term Engraftment of Primary Bone Marrow Stromal Cells Repairs Niche Damage and Improves Hematopoietic Stem Cell Transplantation

Zuzana Tatárová

Hematopoietic stem cell (HSC) transplantation represents a curative treatment for various hematological disorders. However, delayed reconstitution of innate and adaptive immunity often causes fatal complications. HSC maintenance and lineage differentiation are supported by stromal niches, and we now find that bone marrow stroma cells (BMSCs) are severely and permanently damaged by the pre-conditioning irradiation required for efficient HSC transplantation. Using mouse models, we show that stromal insufficiency limits the number of donor-derived HSCs and B lymphopoiesis. Intra-bone transplantation of primary, but not cultured, BMSCs quantitatively reconstitutes stroma function in vivo, which is mediated by a multipotent NT5E(+) (CD73)(+) ENG(-) (CD105)(-) LY6A(+) (SCA1)(+) BMSC subpopulation. BMSC co-transplantation doubles the number of functional, donor-derived HSCs and significantly reduces clinically relevant side effects associated with HSC transplantation including neutropenia and humoral immunodeficiency. These data demonstrate the potential of stroma recovery to improve HSC transplantation.

Cell Press2017

Evolution of longevity improves immunity in Drosophila

Bruno Lemaitre

Much has been learned about the genetics of aging from studies in model organisms, but still little is known about naturally occurring alleles that contribute to variation in longevity. For example, analysis of mutants and transgenes has identified insulin signaling as a major regulator of longevity, yet whether standing variation in this pathway underlies microevolutionary changes in lifespan and correlated fitness traits remains largely unclear. Here, we have analyzed the genomes of a set of Drosophila melanogaster lines that have been maintained under direct selection for postponed reproduction and indirect selection for longevity, relative to unselected control lines, for over 35 years. We identified many candidate loci shaped by selection for longevity and late-life fertility, but - contrary to expectation - we did not find overrepresentation of canonical longevity genes. Instead, we found an enrichment of immunity genes, particularly in the Toll pathway, suggesting that evolutionary changes in immune function might underpin - in part - the evolution of late-life fertility and longevity. To test whether this genomic signature is causative, we performed functional experiments. In contrast to control flies, long-lived flies tended to downregulate the expression of antimicrobial peptides upon infection with age yet survived fungal, bacterial, and viral infections significantly better, consistent with alleviated immunosenescence. To examine whether genes of the Toll pathway directly affect longevity, we employed conditional knockdown using in vivo RNAi. In adults, RNAi against the Toll receptor extended lifespan, whereas silencing the pathway antagonist cactus--causing immune hyperactivation - dramatically shortened lifespan. Together, our results suggest that genetic changes in the age-dependent regulation of immune homeostasis might contribute to the evolution of longer life.

JOHN WILEY & SONS LTD2018

Epiblast-specific loss of HCF-1 leads to failure in anterior-posterior axis specification

Sylvain Frédéric Bessonnard, Daniel Constam, Winship Herr

Mammalian Host-Cell Factor 1 (HCF-1), a transcriptional co-regulator, plays important roles during the cell-division cycle in cell culture, embryogenesis as well as adult tissue. In mice, HCF-1 is encoded by the X-chromosome-linked Hcfc1 gene. Induced Hcfc1(cKO/+) heterozygosity with a conditional knockout (cKO) allele in the epiblast of female embryos leads to a mixture of HCF-1-positive and -deficient cells owing to random X-chromosome inactivation. These embryos survive owing to the replacement of all HCF-1-deficient cells by HCF-1-positive cells during E5.5 to E8.5 of development. In contrast, complete epiblast-specific loss of HCF-1 in male embryos, Hcfc1(epiko/Y), leads to embryonic lethality. Here, we characterize this lethality. We show that male epiblast-specific loss of Hcfc1 leads to a developmental arrest at E6.5 with a rapid progressive cell-cycle exit and an associated failure of anterior visceral endoderm migration and primitive streak formation. Subsequently, gastrulation does not take place. We note that the pattern of Hcfc1(epiKO/y) lethality displays many similarities to loss of beta-catenin function. These results reveal essential new roles for HCF-1 in early embryonic cell proliferation and development. (C) 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license.

Academic Press Inc Elsevier Science2016

Evolution of longevity improves immunity in Drosophila

Bruno Lemaitre

JOHN WILEY & SONS LTD2018