Polymorphic estrogen receptor binding site causes Cd2-dependent sex bias in the susceptibility to autoimmune diseases

Complex autoimmune diseases are sexually dimorphic. An interplay between predisposing genetics and sex-related factors probably controls the sex discrepancy in the immune response, but the underlying mechanisms are unclear. Here we positionally identify a polymorphic estrogen receptor binding site that regulates Cd2 expression, leading to female-specific differences in T cell-dependent mouse models of autoimmunity. Female mice with reduced Cd2 expression have impaired autoreactive T cell responses. T cells lacking Cd2 costimulation upregulate inhibitory Lag-3. These findings help explain sexual dimorphism in human autoimmunity, as we find that CD2 polymorphisms are associated with rheumatoid arthritis and 17-β-estradiol-regulation of CD2 is conserved in human T cells. Hormonal regulation of CD2 might have implications for CD2-targeted therapy, as anti-Cd2 treatment more potently affects T cells in female mice. These results demonstrate the relevance of sex-genotype interactions, providing strong evidence for CD2 as a sex-sensitive predisposing factor in autoimmunity.

Polymorphic estrogen receptor binding site causes CD2-dependent sex bias in the susceptibility to autoimmune diseases

Complex autoimmune diseases are sexually dimorphic. An interplay between predisposing genetics and sex-related factors likely determines the sex discrepancy in the immune response, but conclusive evidence is lacking regarding the underlying molecular mechanisms. Using forward genetics, we positionally identified a polymorphic estrogen receptor binding site that regulates CD2 expression, leading to female-specific differences in mouse models of T cell-dependent autoimmunity. Female mice with reduced CD2 levels displayed diminished expansion of autoreactive T cells. Mechanistically, CD2 affected T cell activation by inhibiting LAG-3 expression. Our findings explain the sexual dimorphism in human autoimmunity, as CD2 associated with rheumatoid arthritis and its regulation through 17-β-estradiol was conserved in human T cells. Hormonal regulation of CD2 has implications for CD2-targeted therapy. Indeed, anti-CD2 treatment was more potent in female mice. In conclusion, our results demonstrate the relevance of sex-genotype interactions and provide strong evidence for CD2 as a sex-sensitive predisposing factor in autoimmunity.