CCL13 and rheumatoid arthritis: Although synovial fibroblasts are the primary source of CCL13 in the context of RA, several studies have demonstrated that CCL13 can be produced in response to different stimuli by other types of fibroblasts, such as dermal fibroblasts, colonic subepithelial myofibroblasts, and nasal polyp fibroblasts (51–53).