[6-8] A major obstacle in dissecting the molecular basis of PBC has been the absence of suitable animal models. We have previously reported that mice transgenic for directed expression of a dominant negative form of transforming growth factor beta Bcl-2 inhibitor receptor type II (dnTGFβRII), under the control

of the CD4 promoter lacking the CD8 silencer, spontaneously developed an autoimmune biliary ductular disease similar to human PBC, including development of AMA.[9-13] This observation is critical because our previous work on PDC-E2 specific CD4+ and CD8+ T cells in human PBC suggests that autoimmune cholangitis in patients is mediated by autoantigen-specific T cells.[14-17] Earlier work has demonstrated that adoptive transfer of CD8+ T cells from dnTGFβRII mice induces autoimmune cholangitis in recipients.[11, 18] However, both in humans and in the murine models there has always been the question as to whether the multilineage response to mitochondrial autoantigens

and, in particular, PDC-E2, is specifically involved in tissue damage or whether it is part of a nonspecific loss of tolerance and therefore an epiphenomenon. To address this issue, we took advantage of our dnTGFβRII Akt inhibitor model and developed unique murine constructs in which we introduced the dnTGFβRII gene, along with either OT-I T-cell receptor (TCR) or OT-II TCR transgenes into Rag1−/− mice. In other words, we developed two dnTGFβRII strains in which medchemexpress the T-cell repertoire was replaced with either ovalbumin (OVA)-specific CD8+ T cells (OT-I) or OVA-specific CD4+ T cells (OT-II). We report herein that autoimmune cholangitis requires T cell antigen specificity for the development of autoimmune

cholangitis. These data have importance not only for this mouse model, but highlight the significance of breach of tolerance to PDC-E2 in humans with PBC. Our colony of dnTGFβRII mice on a C57/BL/6J (B6) background was maintained at the University of California at Davis animal facility (Davis, CA).[9] C57BL/6-Tg (TcrαTcrβ) 1100Mjb/J (OT-I), C57BL/6-Tg (TcrαTcrβ) 425Cbn/J (OT-II) and B6.129S7-Rag1tm1Mom/J (Rag1−/−) mice were purchased from the Jackson Laboratory (Bar Harbor, ME). To generate OT-I/dnTGFβRII/Rag1−/− mice, male dnTGFβRII mice and OT-I mice were mated with female Rag1−/− mice to obtain dnTGFβRII/Rag1+/− mice and OT-I/Rag1+/− mice, which were subsequently backcrossed with female Rag1−/− mice to obtain dnTGFβRII/Rag1−/− mice and OT-I/Rag1−/− mice, respectively. Male dnTGFβRII/Rag1−/− mice were then mated with female OT-I/Rag1−/− mice to obtain OT-I/Rag1−/− and OT-I/dnTGFβRII/Rag1−/− mice. OT-II/dnTGFβRII/Rag1−/− mice were similarly generated. In all cases, genotypes were confirmed via the polymerase chain reaction.

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