Sex-Based Selectivity of PPARγ Regulation in Th1, Th2, and Th17 Differentiation

Peroxisome proliferator-activated receptor gamma (PPAR gamma) has recently been recognized to regulate adaptive immunity through Th17 differentiation, Treg functions, and T-FH responses. However, its role in adaptive immunity and autoimmune disease is still not clear, possibly due to sexual differences. Here, we investigated in vitro treatment study with the PPAR gamma agonist pioglitazone to compare Th1, Th2, and Th17 differentiation in male and female mouse splenic T cells. Pioglitazone treatment significantly inhibited various effector T cell differentiations including Th1, Th2, and Th17 cells from female naive T cells, but it selectively reduced IL-17 production in male Th17 differentiation. Interestingly, pioglitazone and estradiol (E2) co-treatment of T cells in males inhibited differentiation of Th1, Th2, and Th17 cells, suggesting a mechanism for the greater sensitivity of PPAR gamma to ligand treatment in the regulation of effector T cell differentiation in females. Collectively, these results demonstrate that PPAR gamma selectively inhibits Th17 differentiation only in male T cells and modulates Th1, Th2, and Th17 differentiation in female T cells based on different level of estrogen exposure. Accordingly, PPAR gamma could be an important immune regulator of sexual differences in adaptive immunity.