MMP12 and rheumatoid arthritis: Similar to active established RA (21), activin A, TNFα, and MMP12 were readily found in CD163+ macrophages within the synovial sublining of UA, either evolving or not (Figure 3A), and essentially the same results were obtained in PsA, where ST CD163+ macrophages expressed GM-CSF-dependent polarization markers (Figure 3A).