Absent in Melanoma (AIM)2 Promotes the Outcome of Islet Transplantation by Repressing Ischemia-Induced Interferon (IFN) Signaling.

Clinical islet transplantation is limited by ischemia-induced islet cell death. Recently, it has been reported that the absent in melanoma (AIM)2 inflammasome is upregulated by ischemic cell death due to recognition of aberrant cytoplasmic self-dsDNA. However, it is unknown whether AIM2 determines the outcome of islet transplantation. To investigate this, isolated wild type (WT) and -deficient () islets were exposed to oxygen-glucose deprivation to mimic ischemia, and their viability, endocrine function, and interferon (IFN) signaling were assessed. Moreover, the revascularization and endocrine function of grafted WT and islets were analyzed in the mouse dorsal skinfold chamber model and the diabetic kidney capsule model. Ischemic WT and islets did not differ in their viability. However, islets exhibited a higher protein level of p202, a transcriptional regulator of IFN-β and IFN-γ gene expression. Accordingly, these cytokines were upregulated in islets, resulting in a suppressed gene expression and secretion of insulin. Moreover, the revascularization of islet grafts was deteriorated when compared to WT controls. Furthermore, transplantation of islets in diabetic mice failed to restore physiological blood glucose levels. These findings indicate that AIM2 crucially determines the engraftment and endocrine function of transplanted islets by repressing IFN signaling.