Implications of microRNA 21 and its involvement in the treatment of different type of arthritis.

Arthritis is a kind of autoimmune disease, which includes many circumstances that affect joints, the tissues surrounding the joints, and other connective tissues. Osteoarthritis (OA) and rheumatoid arthritis (RA) are the common arthritis seen in many populations. Researchers have made extensive studies on all types of arthritis, novel drugs are being developed by many laboratories, but yet no treatment option is available for these diseases and need new insight into the molecular pathways and pathophysiology of all types of arthritis. MicroRNAs (miRNAs), a class of non-coding RNAs, have shown to be played a plenty of roles in both a suppressive and a promoting role in disease pathogenesis and progression. Among the classes of microRNAs, miR-21 is a widespread miRNA commonly upregulated in many diseases and suggesting that it plays an important role in cell proliferation, apoptosis, and invasion. It is highly expressed in osteoclast precursors and the pro-osteoclastogenic nature of miR-21 makes it a promising candidate as a therapeutic target to treat bone-related disorders. Up to now, there are few papers that demonstrate the role of miR-21 in arthritis and related bone disorders and the number of studies related to different types of arthritis is sparse. Therefore, the main thrust of this paper is to provide an overview of the current clinical evidence and significance of miR-21 in arthritis and bone-related inflammation disorders. We summarize the important research findings surrounding the role of miR-21 and its involvement in the treatment of different types of arthritis.