The Rat Diabetes Susceptibility Locus Iddm4 And At Least One Additional Gene Are Required For Autoimmune Diabetes Induced By Viral Infection

摘要

BBDR rats develop autoimmune diabetes mellitus only after challenge with environmental perturbants. These include polyinosinic:polycytidylic acid (poly I:C, a ligand of toll-like receptor 3), agents that deplete regulatory T cell populations (Tregs), and a non-beta-cell-cytopathic parvovirus (Kilham rat virus, KRV). The dominant diabetes susceptibility locus Iddm4 is required for diabetes induced by treatment with poly I:C plus Treg depletion. Iddm4 is penetrant in congenic heterozygote rats on the resistant WF background, and is 79% sensitive and 80% specific as a predictor of induced diabetes. Surprisingly, an analysis of 190 (BBDR × WF)F2 rats treated with KRV after brief exposure to poly I:C revealed that the BBDR origin allele of Iddm4 is necessary but not entirely sufficient for diabetes expression. A genome scan identified a locus on chromosome 17, designated Iddm20, that is also required for susceptibility to diabetes after exposure to KRV and poly I:C (LOD score 3.7). These data suggest that the expression of autoimmune diabetes is a complex process that requires both major histocompatibility complex (MHC) genes that confer susceptibility and additional genes like Iddm4 and Iddm20 that operate only in the context of specific environmental perturbants, amplifying the immune response and the rate of disease progression.