Prevention of bone mineral density loss in patients with rheumatoid arthritis treated with anti-TNFα therapy

This review focuses on recent advances in the effect of anti-TNFα therapy on bone metabolism and bone mineral density (BMD) in rheumatoid arthritis (RA). RA is a chronic disease characterized by inflammation of the synovial joint, cartilage degradation, and subsequent bone destruction. Bone damage is often manifested as erosions, localized juxta-articular bone loss, or generalized bone loss. Thus, blockade of TNFa not only serves to block inflammation, but also halts the erosive nature of RA and generalized/localized juxta-articular bone loss. Here, we review recent findings showing that anti-TNFa therapy is also effective on halting systemic bone loss. In vitro, TNFa reduces osteoblast activity and increases osteoclast activity through RANKL-RANK pathway. In arthritis animal models, an imbalance between bone formation and resorption is observed. In humans, this coupling of destruction is restored by anti-TNFα therapy early on, but only for a few months. Thus, anti-TNFα prevents the BMD loss in RA patients. In summary, TNFa blockade is not only able to prevent joint destruction, but it is also able to prevent bone loss in RA patients. Future studies are needed to address if TNFa blockers have an effect on bone fractures.