CCR2 and rheumatoid arthritis: Chemokine C‐C motif ligand 2 (CCL2) is an inflammatory chemoattractant belonging to the CC chemokine superfamily encoded by the CCL2 gene located on chromosome 17q11.2.[16] In rheumatoid arthritis, monocytes are recruited to the synovium by the interaction of CCL2 with chemokine receptor CCR2 and differentiate into macrophages and osteoclasts.[17] In addition, the activation of the CCL2/CCR2 signaling has been shown to recruit macrophages, exacerbate synovitis, and damage cartilage in mouse osteoarthritis.[18]