CCL2 and polycystic ovary syndrome: The systemic/circulating proinflammatory milieu in PCOS is suggested in several studies, including elevated plasma levels of C-reactive protein (CRP) (11, 13, 18, 19), interleukin 18 (IL-18) (14, 16), monocyte chemoattractant protein-1 (MCP-1) (17, 32), and macrophage inflammatory protein-1α (MIP-1α) (17, 33).