Publications

Background Autoimmune bullous diseases/dermatoses (AIBDs) are severe autoantibody-mediated skin diseases. The pathogenic relevance of autoreactive CD4+ T cells for the induction of autoantibody production remains to be fully evaluated. Scurfy mice lack functional regulatory T (Treg) cells, experience spontaneous activation of autoreactive CD4+ T cells, and display severe erosive skin lesions suggestive of AIBDs. Objective We sought to determine whether AIBDs develop in Treg cell–deficient scurfy mice. Methods Histology, indirect immunofluorescence (IF) microscopy, direct IF, and ELISA were used to prove the presence of AIBDs in scurfy mice. Monoclonal autoantibodies from sera of scurfy mice were screened by using indirect IF on murine skin, and immunoprecipitation and mass spectrometry were used for target antigen identification, followed by confirmation in modified human embryonic kidney cells and murine keratinocytes. Pathogenicity was determined by injecting the autoantibody into neonatal mice and transferring scurfy CD4+ T cells into nu/nu mice. Results Autoantibodies against different known autoantigens of AIBDs spontaneously develop in scurfy mice. Histology reveals subepidermal blisters, and direct IF of skin of scurfy mice shows a predominant linear staining pattern. The mAb 20B12 shows a linear staining pattern in indirect IF, recognizes the murine hemidesmosomal protein bullous pemphigoid antigen 230 (BP230) as the target antigen, and cross-reacts with human BP230. Purified mAb 20B12 induces subepidermal blisters in neonatal mice. Transfer of scurfy CD4+ T cells is sufficient to induce antibodies with reactivity to AIBD autoantigens and subepidermal blisters in the skin of recipient T cell–deficient nu/nu mice. Conclusion We show that the absence of Treg cells leads to AIBDs by pathogenic autoantibodies targeting BP230.

We have reported on a murine model of autoimmune cholangitis, generated by altering the AU-rich element (ARE) by deletion of the interferon gamma (IFN-γ) 3′ untranslated region (coined ARE-Del−/−), that has striking similarities to human primary biliary cholangitis (PBC) with female predominance. Previously, we suggested that the sex bias of autoimmune cholangitis was secondary to intense and sustained type I and II IFN signaling. Based on this thesis, and to define the mechanisms that lead to portal inflammation, we specifically addressed the hypothesis that type I IFNs are the driver of this disease. To accomplish these goals, we crossed ARE-Del−/− mice with IFN type I receptor alpha chain (Ifnar1) knockout mice. We report herein that loss of type I IFN receptor signaling in the double construct of ARE-Del−/− Ifnar1−/− mice dramatically reduces liver pathology and abrogated sex bias. More importantly, female ARE-Del−/− mice have an increased number of germinal center (GC) B cells as well as abnormal follicular formation, sites which have been implicated in loss of tolerance. Deletion of type I IFN signaling in ARE-Del−/− Ifnar1−/− mice corrects these GC abnormalities, including abnormal follicular structure. Conclusion: Our data implicate type I IFN signaling as a necessary component of the sex bias of this murine model of autoimmune cholangitis. Importantly these data suggest that drugs that target the type I IFN signaling pathway would have potential benefit in the earlier stages of PBC. (Hepatology 2018;67:1408-1419)