Selective JAK Inhibition Ameliorates Aire Deficiency–Driven Autoimmunity

Background Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is an autosomal recessive monogenic autoimmune disease caused by deficiency in the autoimmune regulator (AIRE) gene that manifests with multiple life-threatening autoimmune manifestations. Deficiency in AIRE results in self-reactive T cells that escape into the periphery and infiltrate organs causing injury. We recently showed that APECED is an interferon-gammopathy, as deletion of IFNg or treatment with the FDA-approved JAK1/2 inhibitor, ruxolitinib, improved autoimmunity in Aire KO mice and APECED patients. Methods We aimed to evaluate the efficacy of selective JAK1, JAK2, and JAK3 inhibitors relative to that of ruxolitinib to delineate the mechanistic roles of the different Janus kinase pathways in the context of APECED. Aire KO mice underwent treatment with three selective JAK inhibitors: JAK1i (itacitinib), JAK2i (CEP-33779), and JAK3i (ritlecitinib). To evaluate the efficacy of these JAK inhibitors in ameliorating autoimmunity, we performed ELISA, qPCR, immunoblot, flow cytometric, and histological analyses. Results JAK1-, JAK2-, and JAK3-selective inhibitors significantly decreased the accumulation of pathogenic CD4 and CD8 T cells in Aire KO mouse lungs at levels comparable with ruxolitinib. Ruxolitinib and JAK1- and JAK2-selective inhibitors resulted in more pronounced decreases in IFNg and Cxcl9 transcripts and levels of STAT1 and pSTAT1 by immunoblot analyses relative to the JAK3-selective inhibitor in Aire KO mouse lung. Concordantly, ruxolitinib and JAK1- and JAK2-selective inhibitors exhibited greater efficacy in ameliorating tissue injury in autoimmunity-affected organs as assessed by histological analysis compared with the JAK3-selective inhibitor in Aire KO mice. Conclusion We show that JAK1- and JAK2-selective inhibition led to a similarly effective amelioration of IFNg-driven inflammation and tissue injury compared with the JAK1/2 inhibitor, ruxolitinib, in Aire KO mice. By contrast, although JAK3 inhibition markedly decreased lymphocytic accumulation in Aire KO mice, it appeared less effective in reducing IFNg-driven inflammation and tissue injury compared with all other tested JAK inhibitors. Our study sheds light on the differential roles of JAK inhibitors in the context of APECED-associated autoimmunity and informs future work that may help develop more selective JAK inhibitor-based treatments in APECED patients with the goal to achieve maximal efficacy and long-term safety.