PPARD and keratoconus: On the basis of our findings that macrophages were the most infiltrating immunosuppressive inflammatory cells in pancreata of KC/Pd mice with PPARδ hyperactivation (Fig. 5) and that CCL2 expression was directly regulated by PPARD alterations in human and mouse pancreatic epithelial cells (Figs. 6, 7), we examined whether PPARδ upregulation of Ccl2 secretion by pancreatic epithelial cells increased Ccr2+ immune cells in the pancreata of KC/Pd mice fed the GW diet, given that Ccr2 is the primary Ccl2 receptor and commonly present in immune cells such as macrophages and MDSCs43,44.