title: Synergistic activity of malononitrilamides with cyclosporine to control and reverse xenograft rejection.
abstract: Several studies in xenotransplantation have stressed the role of humoral mechanisms of graft rejection and have emphasized the role of xenophile antibodies as well as T-cell activation in the rejection of xenografts. Malononitrilamides (MNAs), derivatives of the primary metabolite of leflunomide, were found to be potent inhibitors of the IgM and IgG antibody response in vitro and were able to reduce auto- and allo-antibody formation in vivo. Here we tested the immunosuppressive activities of MNA 279 and MNA 715 in a concordant mouse-to-rat skin xenotransplantation model. Mouse skin xenograft survival in untreated Lewis rats (5.4 +/- 1.1 days) and those given a vehicle solution only by gavage (6.1 +/- 0.9 days) were statistically indistinguishable. In our model treatment with cyclosporine (10 mg/kg/day) as a single drug showed no significant prolongation of xenograft survival (6.4 +/- 0.9 days) as compared to controls. When MNAs were given alone to xenograft recipients, they were able to demonstrate a significant and dose-dependent prolongation of graft survival time. Even a short-term application of these new immunosuppressive agents showed efficacy in the prevention of hyperacute xenograft rejection. Both MNA 279 and MNA 715 also have therapeutic activity and can reverse ongoing acute skin xenograft rejection. With these drugs a remarkable suppression of donor-specific IgM and IgG xenoantibody production in vivo was also clearly demonstrated by flow cytometry. Interestingly, whereas cyclosporine alone was unable to prolong xenograft survival, MNA-combination therapy, even a short-term application with an ineffective dose of CyA, was synergistically effective and significantly prolonged xenograft survival. This synergistic effect of MNAs with CyA was seen also when they were given therapeutically on days 5 to 9 and they reversed hyperacute skin xenograft rejection in this mouse-to-rat model.
authors.affiliation: Research Laboratories Hoechst Marion Roussel (HMR), Marburg, Germany.
authors.forename: H U
authors.initials: HU
authors.lastname: Schorlemmer
authors.forename: R
authors.initials: R
authors.lastname: Kurrle
mesh_terms: D000480:Alkynes; D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology*; D004357:Drug Synergism; D006084:Graft Rejection / Q000188:drug therapy* / Q000517:prevention & control*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007555:Isoxazoles; D051379:Mice; D008807:Mice, Inbred BALB C; D009570:Nitriles / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew; D016038:Skin Transplantation; D014183:Transplantation, Heterologous / Q000276:immunology
chemical_list: D000480:Alkynes; D007166:Immunosuppressive Agents; D007555:Isoxazoles; D009570:Nitriles; C102911:X 910279; C115284:2-cyano-3-hydroxy-N-(4-(trifluoromethyl)phenyl)-2-hepten-6-ynamide; D016572:Cyclosporine