Neutrophil infiltration in the synovium of RA releases IL-17A to stimulate synoviocyte production of CCL20, which attracts monocytes/macrophages to secrete pro-inflammatory factors, including TNF-α and IL-1β, affecting osteoclast differentiation and causing bone destruction (Katayama, 2021). Here, CCL20 is linked to rheumatoid arthritis.