CCL2 and polycystic ovary syndrome: Chronic inflammation also develops with increased levels of tumor necrosis factor α (TNF-α), monocyte chemotactic protein-1 (MCP-1), C-reactive protein (CRP), interleukin-1 (IL-1), interleukin-6 (IL-6), and other pro-inflammatory cytokines, which have been found elevated in PCOS.