CCL2 and arthritic joint disease: Chemotactic cytokine ligand 2 (CCL2), also known as monocyte chemoattractant protein 1 (MCP-1), is well-known to mediate the migration and infiltration of monocytes and macrophages by signaling through chemokine (C–C motif) receptor 2 (CCR2).173 In arthritis, CCL2 promotes inflammation of the joint.174 Evidence also suggests that CCL2 is an important mediator of neuroinflammation.175,176 In neuropathic pain, CCL2 expression is increased in microglia and in sensory neurons in the dorsal root ganglia (DRGs), where CCL2 can be further transported and released into central spinal nerve terminals.