Is RANKL inhibition both anti-resorptive and anabolic in rheumatoid arthritis?

A small peptide, OP3-4, blocks receptor activator of NF-κB from binding to its ligand, receptor activator of NF-κB ligand (RANKL), and was reported recently to inhibit bone resorption, promote bone formation and protect cartilage in a preclinical rheumatoid arthritis model. The latter effects may result from inhibition of RANKL reverse signalling in osteoblasts and chondrocytes. Whether other RANKL inhibitors, such as denosumab, share this action is not known, but OP3-4 at least has potential to provide anabolic treatment for both systemic and focal bone loss in inflammatory arthritis.