title: Dendritic cells secrete the immunosuppressive HLA-G molecule upon CTLA4-Ig treatment: implication in human renal transplant acceptance.
abstract: CTLA4-Ig (Belatacept) is a new recombinant molecule that interferes with the signal of T lymphocyte activation and prevents acute rejection after renal transplantation. HLA-G acts as a naturally tolerogenic molecule in humans. In this study, we analyzed whether HLA-G contributes to CTLA4-Ig-mediated graft acceptance. Our results demonstrate that patients treated with CTLA4-Ig displayed significantly higher soluble HLA-G (sHLA-G) plasma concentrations (72 +/- 14 ng/ml) than patients treated with calcineurin inhibitors (5 +/- 1 ng/ml) or healthy donors (5 +/- 5 ng/ml). Notably, sHLA-G purified from plasma of CTLA4-Ig-treated patients was biologically active as it inhibited allogeneic T cell proliferation in vitro. Dendritic cells (DC) were identified as one of the cellular sources of sHLA-G in CTLA4-Ig-treated patients. Supporting this observation, we showed that DC generated in vitro in presence of CTLA4-Ig released sHLA-G in response to allostimulation. These CTLA4-Ig-treated DC acted as tolerogenic APC through sHLA-G secretion as they suppressed T cell alloproliferation, which could be restored by using a neutralizing anti-HLA-G Ab. These data define a novel pathway by which CTLA4-Ig immunomodulates allogenic response through posttranscriptional regulation of HLA-G expression in DC. CTLA4-Ig-mediated HLA-G release appears as a critical factor in T cell alloresponse inhibition, thereby contributing to the immunosuppressive effect and graft acceptance.
authors.affiliation: INSERM Unité 542, Villejuif, France.
authors.forename: Rajia
authors.initials: R
authors.lastname: Bahri
authors.forename: Abderrahim
authors.initials: A
authors.lastname: Naji
authors.forename: Catherine
authors.initials: C
authors.lastname: Menier
authors.forename: Bernard
authors.initials: B
authors.lastname: Charpentier
authors.forename: Edgardo D
authors.initials: ED
authors.lastname: Carosella
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rouas-Freiss
authors.forename: Antoine
authors.initials: A
authors.lastname: Durrbach
mesh_terms: D000069594:Abatacept; D000328:Adult; D015153:Blotting, Western; D003713:Dendritic Cells / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control; D006680:HLA Antigens / Q000276:immunology / Q000378:metabolism*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D018796:Immunoconjugates / Q000494:pharmacology*; D007150:Immunohistochemistry; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D016030:Kidney Transplantation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012323:RNA Processing, Post-Transcriptional; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D018796:Immunoconjugates; D007166:Immunosuppressive Agents; D000069594:Abatacept