Regulatory T Cells Expanded from Hiv-1-Infected Individuals Maintain Phenotype, Tcr Repertoire and Suppressive Capacity

While modulation of regulatory T cell (Treg) function and adoptive Treg transfer are being explored as therapeutic modalities in the context of autoimmune diseases, transplantation and cancer, their role in HIV-1 pathogenesis remains less well defined. Controversy persists regarding their beneficial or detrimental effects in HIV-1 disease, which warrants further detailed exploration. Our objectives were to investigate if functional CD4+ Tregs can be isolated and expanded from HIV-1-infected individuals for experimental or potential future therapeutic use and to determine phenotype and suppressive capacity of expanded Tregs from HIV-1 positive blood and tissue. Tregs and conventional T cell controls were isolated from blood and gut-associated lymphoid tissue of individuals with HIV-1 infection and healthy donors using flow-based cell-sorting. The phenotype of expanded Tregs was assessed by flow-cytometry and quantitative PCR. T-cell receptor ß-chain (TCR-β) repertoire diversity was investigated by deep sequencing. Flow-based T-cell proliferation and chromium release cytotoxicity assays were used to determine Treg suppressive function. Tregs from HIV-1 positive individuals, including infants, were successfully expanded from PBMC and GALT. Expanded Tregs expressed high levels of FOXP3, CTLA4, CD39 and HELIOS and exhibited a highly demethylated TSDR (Treg-specific demethylated region), characteristic of Treg lineage. The TCRß repertoire was maintained following Treg expansion and expanded Tregs remained highly suppressive in vitro. Our data demonstrate that Tregs can be expanded from blood and tissue compartments of HIV-1+ donors with preservation of Treg phenotype, function and TCR repertoire. These results are highly relevant for the investigation of potential future therapeutic use, as currently investigated for other disease states and hold great promise for detailed studies on the role of Tregs in HIV-1 infection.Elizabeth Glaser Pediatric AIDS Foundation (Pediatric HIV Vaccine Program Award MV-00-9-900-1429-0-00)Massachusetts General Hospital. Executive Committee on Research (MGH/ECOR Physician Scientist Development Award)National Institutes of Health (U.S.) (NIH NIAID (KO8 AI074405))National Institutes of Health (U.S.) (NIH NIAID AI074405-03S1)Massachusetts General Hospital (William F. Milton Fund)Harvard University. Center for AIDS Research (CFAR Scholar Award)Massachusetts General Hospital. Center for the Study Inflammatory Bowel Disease (P30DK043351)Harvard University. Center for AIDS Research (NIH funded program (5P30AI060354-09

Induction de tolérance en transplantation par blocage de la voie CD40/CD40L (caractérisation des cellules tolérogènes induites chez le rat et évaluation chez le primate)

Le blocage de la voie de costimulation CD40/CD40L par injection d'un adénovirus codant pour CD40Ig génère des lymphocytes T régulateurs CD8+CD45RClo capables d'induire une tolérance indéfinie d'une allogreffe cardiaque chez le rat. L'étude du transcriptome de ces lymphocytes TCD8+ tolérogènes par puce à ADN a permis d'établir des hypothèses quant aux mécanismes impliqués. Le rôle de l'IFNg est retrouvé et pourrait induire l expression d'une protéine immuno-régulatrice Fgl2. La présence des molécules du CMH de classe II semble également importante. De nombreuses molécules observées dans des analyses de lymphocytes Treg par puces à ADN sont également surexprimées. D autres hypothèses, sont également discutées. Cette stratégie d induction de la tolérance a été évaluée chez le primate en faisant exprimer par des AAV recombinants le CD40Ig humain associé à sc28AT, un inhibiteur de la voie de costimulation CD28/B7. Les molécules sont fonctionnelles in vitro et l injection des animaux par AAV permet une expression prolongée de CD40Ig, mais plus faible et transitoire du sc28AT, qui semble immunogène. Le CD40Ig ne prolonge pas la survie de la greffe contrairement au sc28AT. La survie du greffon d un animal recevant les deux transgènes a été prolongée et d autres animaux sont prévus. L'expression de molécules d intérêt thérapeutique par vecteurs viraux permet de disposer d'un modèle d'évaluation de bioréactifs pour l'induction de la tolérance chez le primate dans des conditions de faisabilité satisfaisantes. L'efficacité des molécules CD40Ig et sc28AT dans ce modèle de transplantation montre les limites de la transposition des modèles rongeurs aux primates.Inhibition of the CD40/CD40L costimulation pathway using an adenovirus coding for CD40Ig can generate CD8+CD45RClo T regulatory cells that induce indefinite graft tolerance in a rat cardiac allograft model. A gene expression study of tolerogenic cells by DNA microarray allowed us to explore the mechanisms involved. As expected, IFNg seems to be a key player and might induce the expression of the immuno-regulatory protein Fgl2. MHC-II molecules seem to be important too. Other molecules observed in other Treg microarray analyses are also over-expressed. Other hypothesis are also discussed.This tolerance induction strategy was evaluated in primates using recombinant AAV coding for the human CD40Ig molecule and/or sc28AT, an inhibitor of the CD28/B7 costimulation pathway. These molecules were functional in vitro. The AAV injection led to a prolonged expression of CD40Ig whereas sc28AT molecule was produced transiently, as it seemed to be immunogenic. Unlike CD40Ig, sc28AT appeared to be efficient in vivo. The animal receiving both transgenes had delayed graft rejection, and other experiments are now scheduled. The expression of therapeutic molecules through viral vectors to evaluate the tolerance induction efficiency in primates is feasible. However the efficiency of the CD40Ig and sc28AT molecules in our model is still debatable and raises the issue of the relevance of rodent models compared to primate pre-clinical strategies.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

A LAG-3–Specific Agonist Antibody for the Treatment of T Cell–Induced Autoimmune Diseases

Abstract T cells chronically stimulated with the same peptide tend to express exhaustion markers such as PD-1 or LAG-3. Deficiencies in the PD-1 and LAG-3 pathways have been linked to the development of autoimmune diseases. IMP761 is a LAG-3–specific humanized agonist Ab with immunosuppressive properties both in vitro and in vivo in an Ag-specific delayed-type hypersensitivity (DTH) model in the cynomolgus macaque (Macaca fascicularis). IMP761 inhibits TCR-mediated NFAT activation and Ag-induced human T cell proliferation and activation. In the DTH model, assessment of T cell infiltration and gene expression profile at the DTH biopsy site corresponds to immunosuppression of an Ag-induced T cell response. IMP761 is the first LAG-3–specific agonist product candidate, acting upstream on activated T cells, the root cause of self-Ag–specific T cell–induced autoimmune diseases.</jats:p

Low genetic diversity in a widespread whistling alien: A comparison of Eleutherodactylus johnstonei Barbour, 1914 (Eleutherodactylidae) and congeners in native and introduced ranges

There is no clear empirical evidence to support the general assumption that genetic diversity favours successful invasions. Many invading species disperse and establish successfully despite low genetic diversity, a phenomenon known as the genetic paradox of biological invasion. Model systems that allow comparison of genetic patterns between exotic and native source populations are still scarce. This is particularly true for amphibians. Here we compare genetic patterns of the widely introduced Johnstone’s Whistling Frog, Eleutherodactylus johnstonei, with its successful alien congener E. antillensis and the single island endemic E. portoricensis. Genetic diversity and population differentiation in native and introduced populations of the three taxa were inferred from mitochondrial D-loop sequences (235 bp). Our results reveal that exotic populations of the two alien taxa, E. johnstonei and E. antillensis, are not only genetically impoverished due to founder effects, but that, moreover, their native range source-populations exhibit low genetic diversity and inter-population differentiation in the first place. Populations of the endemic E. portoricensis, on the other hand, are genetically more diverse and show marked inter-population differentiation. These observed genetic patterns are consistent with geological processes and invasion histories. We argue that the establishment success of the alien taxa in our model system is better explained by ecological factors and anthropogenic drivers than by genetic diversity. As these factors provide more parsimonious explanations, they should be given priority in management decisions. However, molecular studies with higher resolution are needed to fully test possible genetic and epigenetic components that could promote the invasion process.</jats:p