Adverse Effect on Syngeneic Islet Transplantation by Transgenic Coexpression of Decoy Receptor 3 and Heme Oxygenase-1 in the Islet of NOD Mice

Decoy receptor 3 (DcR3) blocks both Fas ligand- and LIGHT-induced pancreatic β-cell damage in autoimmune diabetes. Heme oxygenase 1 (HO-1) possesses antiapoptotic, anti-inflammatory, and antioxidative effects that protect cells against various forms of attack by the immune system. Previously, we have demonstrated that transgenic islets overexpressing DcR3 or murine HO-1 (mHO-1) exhibit longer survival times than nontransgenic islets in syngeneic islet transplantation. In this study, we evaluated whether DcR3 and mHO-1 double-transgenic islets of NOD mice could provide better protective effects and achieve longer islet graft survival than DcR3 or mHO-1 single-transgenic islets after islet transplantation. We generated DcR3 and mHO-1 double-transgenic NOD mice that specifically overexpress DcR3 and HO-1 in islets. Seven hundred islets isolated from double-transgenic, single-transgenic, or nontransgenic NOD mice were syngeneically transplanted into the kidney capsules of newly diabetic female recipients. Unexpectedly, there was no significant difference in the survival time between double-transgenic or nontransgenic NOD islet grafts, and the survival times of double-transgenic NOD islet grafts were even shorter than those of DcR3 or mHO-1 single-transgenic islets. Our data indicate that transplantation of double-transgenic islets that coexpress HO-1 and DcR3 did not result in a better outcome. On the contrary, this strategy even caused an adverse effect in syngeneic islet transplantation.