Sex chromsomes affect gene expression of healthy 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 CD4+ T cells stimuated with antiCD3/CD28 from XXSry and XY-Sry 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. Male mice from the "four core genotypes" mouse model (XXSry and XY-Sry) were gonadectomized at 4-6 weeks old. At 8-12 weeks old, auxillary, brachial, and inguinal draining lymph nodes were collected and processed into single cell suspensions and sorted for CD4+ T cells using the EasySep Mouse CD4+ T cell isolation kit (STEMCELL). Cells were stiumulated with anti-CD3/CD28 Dyna Beads for 36 hours and RNA was isolated for analysis by high throughput RNA sequencing.