Compared with non-PCOS women, the immune cells such as macrophages, lymphocytes, and natural killer (NK) cells in PCOS patients were increased, and the levels of inflammatory factors such as C-reactive protein, interleukin (IL) 6, IL-18, tumor necrosis factor-α and monocyte chemotactic protein-1 in peripheral blood were significantly increased, which makes the ovary and peripheral blood in a state of chronic inflammation (56). Here, CCL2 is linked to polycystic ovary syndrome.