IL17A and synovial sarcoma: Different to the abovementioned targets, PPARγ has anti-inflammatory effects by degrading intrinsic NF-κB. Other aspects of PPARγ in immunity are that PPARγ can inhibit the expression of Th1 and Th2 cytokines to control the progression of SS in NOD mice and suppress the proliferation and differentiation of Th17 cells, which mainly release IL-17 [58].