title: Nitric oxide and indoleamine 2,3-dioxygenase mediate CTLA4Ig-induced survival in heart allografts in rats.
abstract: Cytotoxic T lymphocyte-associated antigen 4 immunoglobulin (CTLA4Ig) leads to transplantation tolerance in mice depending on indoleamine 2,3-dioxygenase (IDO). We have shown that CTLA4Ig induces indefinite heart allograft survival in rats and that nitric oxide (NO) was implicated in the in vitro active tolerogenic mechanisms mediated by dendritic cells (DCs). Here we studied the in vivo tolerogenic mechanisms by which CTLA4Ig induces graft survival in rats receiving a cardiac allograft. Treatment of recipients with the IDO inhibitor 1-methyltryptophan (1-MT) did not abrogate the indefinite graft survival observed with CTLA4Ig alone. This was also the case after administration of the inducible nitric oxide synthase inhibitor aminoguanidine when again, indefinite allograft survival was maintained. However, administration of both inhibitors led to acute rejection. We show that IDO and NO are responsible for the impaired capacity of DCs from CTLA4Ig-treated rats to stimulate allogeneic T cells. In conclusion, we show that NO and IDO mediate CTLA4Ig-induced tolerance in rat allograft recipients.
authors.affiliation: INSERM, U643, Nantes, F44000, France.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Hill
authors.forename: Rachid
authors.initials: R
authors.lastname: Zagani
authors.forename: Cécile
authors.initials: C
authors.lastname: Voisine
authors.forename: Claire
authors.initials: C
authors.lastname: Usal
authors.forename: Ignacio
authors.initials: I
authors.lastname: Anegon
mesh_terms: D000069594:Abatacept; D000818:Animals; D003713:Dendritic Cells / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006085:Graft Survival; D016027:Heart Transplantation; D018796:Immunoconjugates / Q000494:pharmacology*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism*; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors; D051381:Rats; D011917:Rats, Inbred Lew; D014184:Transplantation, Homologous; D014364:Tryptophan / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D018796:Immunoconjugates; D007166:Immunosuppressive Agents; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D009569:Nitric Oxide; D000069594:Abatacept; D014364:Tryptophan; D052247:Nitric Oxide Synthase Type II; C525396:1-methyltryptophan