Querying LA and OA synovial expression profiles with the co-expressed genes from fibroblast subpopulations described in human RA and OA synovium10, we found that two resident synovial sublining fibroblast populations, CD34+ and DKK3+, were significantly increased in the OA samples over LA (Fig. 4b; p = 0.00148 and 0.00213, respectively). Here, DKK3 is linked to rheumatoid arthritis.