Potent immunosuppressive drugs have significantly improved early patient survival after liver transplantation (LT). However, long-term results remain unsatisfactory because of adverse events that are largely associated with lifelong immunosuppression. To solve this problem, different strategies have been undertaken to induce operational tolerance, for example, maintenance of normal graft function and histology without immunosuppressive therapy, but have achieved limited success. In this pilot study, we aimed to induce tolerance using a novel regulatory T-cell-based cell therapy in living donor LT. Adoptive transfer of an ex vivo-generated regulatory T-cell-enriched cell product was conducted in 10 consecutive adult patients early post-LT. Cells were generated using a 2-week coculture of recipient lymphocytes with irradiated donor cells in the presence of anti-CD80/86 monoclonal antibodies. Immunosuppressive agents were tapered from 6 months, reduced every 3 months, and completely discontinued by 18 months. After the culture, the generated cells displayed cell-number-dependent donor-specific inhibition in the mixed lymphocyte reaction. Infusion of these cells caused no significant adverse events. Currently, all patients are well with normal graft function and histology. Seven patients have completed successful weaning and cessation of immunosuppressive agents. At present, they have been drug free for 16-33 months; 4 patients have been drug free for more than 24 months. The other 3 recipients with autoimmune liver diseases developed mild rejection during weaning and then resumed conventional low-dose immunotherapy. Conclusions: A cell therapy using an ex vivo-generated regulatory T-cell-enriched cell product is safe and effective for drug minimization and operational tolerance induction in living donor liver recipients with nonimmunological liver diseases. (HEPATOLOGY 2016;64:632-643) SEE EDITORIAL ON PAGE 347 E arly results after liver transplantation (LT) have been greatly improved by the evolution of potent antirejection agents. However, unfortunately, late outcomes remain unsatisfactory because of immunological and nonimmunological complications that are largely associated with lifelong immunosuppression (IS). They are infection, de novo malignancy, chronic rejection, and kidney, cardiovascular, and
We have previously reported successful induction of renal allograft tolerance via a mixed chimerism approach in nonhuman primates (NHP). In those studies, we found that costimulatory blockade with anti-CD154 mAb was an effective adjunctive therapy for induction of renal allograft tolerance. However, since anti-CD154 mAb is not clinically available, we have evaluated CTLA4Ig as an alternative agent for effecting costimulation blockade in this treatment protocol. Two CTLA4-Igs, Abatacept and Belatacept, were substituted for anti-CD154 mAb in the conditioning regimen (low dose total body irradiation, thymic irradiation, ATG and a one month post-transplant course of cyclosporine (CyA)). Three recipients treated with the Abatacept regimen failed to develop comparable lymphoid chimerism to that achieved with anti-CD154 mAb treatment and these recipients rejected their kidney allografts early. With the Belatacept regimen, four of five recipients developed chimerism and three of these achieved long-term renal allograft survival (>861, >796 and >378 days) without maintenance immunosuppression. Neither chimerism nor long-term allograft survival were achieved in two recipients treated with the Belatacept regimen but with a lower, subtherapeutic dose of CyA. This study indicates that CD28/B7 blockade with Belatacept can provide a clinically applicable alternative to anti-CD154 mAb for promoting chimerism and renal allograft tolerance.
Blockade of the CD40-CD154 costimulatory signal is an attractive strategy for immunosuppression and tolerance induction in organ transplantation. Treatment with anti-CD154 monoclonal antibodies (mAbs) results in potent immunosuppression in nonhuman primates (NHPs). Despite plans for future clinical use, further development of these treatments was halted by complications. As an alternative approach, we have been focusing on the inhibition of the counter receptor, CD40 and have shown that a novel human anti-CD40 mAb, ASKP1240, markedly prolongs renal allograft survival in NHPs, although allografts eventually underwent chronic allograft nephropathy. On the basis of our previous findings that a CD40-CD154 costimulation blockade induces tolerance to hepatic, but not cardiac, allografts in rodents, we tested here our hypothesis that a blockade of CD40 by ASKP1240 allows acceptance of hepatic allografts in NHPs. A 2-week ASKP1240 induction treatment prolonged liver allograft survival in NHPs; however, the graft function deteriorated due to chronic rejection. In contrast, a 6-month ASKP1240 maintenance monotherapy efficiently suppressed both cellular and humoral alloimmune responses and prevented rejection on the hepatic allograft. No serious side effects, including thromboembolic complications, were noted in the ASKP1240-treated monkeys. We conclude that CD40 blockade by ASKP1240 would be a desirable immunosuppressant for clinical liver transplantation.
DHMEQ ameliorated experimental colitis in mice. These results indicate that DHMEQ appears to be an attractive therapeutic agent for IBD.
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