PTGS2 and rheumatoid arthritis: The gastrointestinal side effects of nonselective COX inhibitors and the cardiovascular side effects of selective COX-2 inhibitors limit their application, and the lowest dose and shortest term are recommended for clinical use.33 We demonstrated that high levels of COX-2 expression in osteocytes induce abnormal bone formation in subchondral bone, therefore accelerating cartilage degeneration in the onset of spontaneous OA and RA.