CCL2 and autoimmune disease: The signaling pathways involved in regulating CCL2 gene expression include cytokine receptor, NOD-like receptor, and chemokine receptor pathways. CCL2 is specifically expressed on the surface of monocytes but not on that of neutrophils and eosinophils, and its expression is associated with autoimmune diseases such as psoriasis and rheumatoid diseases (Kabala et al., 2020). Studies have shown that the 2518G/A polymorphism of CCL2 is associated with tuberculosis and pancreatitis (Chen et al., 2015; Fang et al., 2015).