Sex chromosomes affect gene expression of autoantigen specific CD4+ T cells in B6 gonadal males.

To determine the role of sex chromsomes in sex differences of autoimmune disease, we used high throughput RNA sequencing to analyze the transciptomes of autoantigen specific CD4+ T cells from XX and XY- mice using the “four core genotypes” mouse model. We found higher expression of several X genes in the XY- genotype compared to XX, suggesting a difference in DNA methylation of these genes between Xp and Xm. In a hypothesis driven targeted approach, we investigated two immunomodulatory X genes, Tlr7 and FoxP3 and found that the promoter regions of both genes had more DNA methylation on the Xp than Xm, and that both genes had higher expression in autoantigen stimulated CD4+ T cells from XY- compared to XX mice. This study provides new insights regarding how sex chromsomes affect gene expression and cause sex differences in autoimmune disease. Overall design: Male mice from the "four core genotypes" mouse model (XXSry and XY-Sry) were gonadectomized at 4-6 weeks old and subsequently immunized with MOG 35-55 peptide emulsified in complete fraunds adjuvant, suppplemented with myobacterium tuberculosis H27Ra for 10 days. Auxillary, brachial, and inguinal draining lymph nodes were collected and processed into single cell suspensions. Cells were stiumulated with MOG 35-55 and IL-12 for 36 hours. Stimulated cells were sorted for CD4+ T cells using the EasySep Mouse CD4+ T cell isolation kit (STEMCELL), and RNA was isolated for analysis by high throughput RNA sequencing.