IL4 and metabolic syndrome: Acting on DP receptors expressed by resident cells in adipose tissue, leptin-induced PGD2 can down-regulate production of leptin (45), trigger secretion of Th2 cytokines IL-5 as well as IL-4 by ILC2s (46, 47), or polarize macrophages toward a M2 anti-inflammatory state in an autocrine fashion (40)—all adipose housekeeping mechanisms of metabolic syndrome evasion.