PTGS2 and osteoarthritis: Meloxicam (MLX), one of the non-steroidal anti-inflammatory drugs (NSAIDs), is clinically used for the treatment of TMJ osteoarthritis based on the mechanism of selectively blocking cyclooxygenase-2 (COX-2) and meanwhile inhibiting synthesis of inflammatory factor prostaglandin-E2 (PGE2), which are considered to play a major role in the development of osteoarthritis [9,10].