To

test for other factors influencing the expression of known liver autoantigens in the thymus and their relationship with the observed sex difference in AIH susceptibility, B6.129S2-Airetm1.1Doi/J HSP inhibitor transgenic Aire knockout mice were studied. Aire, which stands for Autoimmune Regulator, is a transcription factor responsible for the ectopic expression of peripheral antigens in the thymus to allow deletion of self-reactive T cells. FTCD but not CYP2D9 is, as insulin,16 under control of the Aire transcription factor (Fig. 3C). The invalidation of one copy of the Aire gene in heterozygous mice (+/0) lowers the expression of FTCD in the thymus (Fig. 3C). Therefore, heterozygous Aire mice offers a model in which the importance of partial failure in T cell–negative selection for specific liver autoantigens on AIH development can be studied. After xenoimmunization, male and female Aire heterozygous mice showed the same sex-bias as observed in C57BL/6 mice (Figs. 1B, 3D). Therefore, the invalidation of one copy of the Aire gene in heterozygous mice (+/0) did not modulate the grade of liver inflammation compared with wild-type mice (+/+) (Fig. 3D). Peripheral tolerance by regulatory T cells could influence the development of BI 6727 cost an autoimmune hepatitis in mice. Xenoimmunized 7-week-old C57BL/6 male mice show a statistically significant higher percentage of Tregs

in the spleen, blood, and liver than vaccinated females of the same age (Fig. 4A). The same difference is observed in vaccinated heterozygous Aire mice. Male mice show higher levels of regulatory T cells in the spleen, blood, and liver when compared with females (Fig. 4B). Significantly higher levels of regulatory T cells are found 上海皓元医药股份有限公司 in liver infiltrates of male mice compared with female where regulatory T cells were virtually absent (Fig. 4B). Testes are an immunological privileged site, and as such, provide an environment able to suppress and control immune responses. In C57BL/6 mice, ectopic expression of

FTCD and CYP2D9 was found in testes (Fig. 5A), and their expression was independent of the Aire transcription factor in this organ (Fig. 5B). This finding suggests that testes could influence susceptibility to AIH through peripheral conversion of autoreactive naïve T cells to FoxP3+ regulatory T cells. Sexual hormones can also directly modulate immune responses locally and systemically, and in doing so, alter the development of an autoimmune disease. Therefore, to assess the role of testes and sexual hormones on AIH susceptibility, we xenoimmunized castrated male C57BL/6 mice, supplemented or not with physiological levels of 17β-estradiol. After an 8-month follow-up, castrated male C57BL/6, supplemented or not with 17β-estradiol, showed a similar grade of liver inflammation after xenoimmunization than vaccinated male C57BL/6 mice (Fig. 6A).