Janus kinase inhibition prevents autoimmune diabetes in LEW.1WR1 rats

Numerous studies highlight the essential role of type I interferon (IFN) responses in type 1 diabetes. The absence of type I IFN signaling is associated with a partial reduction of autoimmune diabetes incidence in LEW.1WR1 rats. We sought to delineate type I IFN-independent mechanisms that drive diabetes using type I IFN α/β receptor (IFNAR) knockout rats. Rats were treated with polyinosinic:polycytidylic acid plus Kilham rat virus to induce diabetes. Single-cell RNA-sequencing of islets and cytokine measurements in blood and spleen from prediabetic Ifnar1^−/− rats were employed to identify factors driving insulitis in the global absence of IFNAR signaling. Islet immune cells were enriched for Ccl4, Ccl5, and Ifng. In addition, interleukin-1 (IL-1) was increased in spleen, and IFN-γ was increased in serum from prediabetic Ifnar1^−/− rats. Based on these findings, rats were treated with a C-C chemokine receptor type 5 inhibitor, an IL-1 receptor antagonist, or a nucleotide-binding oligomerization domain-like receptor family pyrin-domain containing 3 inhibitor, none of which prevented diabetes. The Janus kinase inhibitor ruxolitinib, which blocks both type I and II interferon-driven signaling, completely prevented diabetes, but only when given for a sustained period starting from the time of induction. The tyrosine kinase 2 inhibitor deucravacitinib also prevented diabetes to a significant degree. We conclude that type I and II IFNs act in concert as the main drivers of autoimmune diabetes and that inhibition of downstream signaling events for both is required for disease prevention.