Bone changes in early rheumatoid arthritis

Bone disease in rheumatoid arthritis affects the peri-articular and axial skeleton and is a major cause of disability. Recent studies have shown that pro-inflammatory cytokines stimulate the expression of osteoprotegerin ligand, a transmembrane protein of the tumour necrosis factor ligand superfamily, on synoviocytes and activated T cells. Osteoprotegerin ligand stimulates osteoclast formation and activation, membrane-bound and soluble osteoprotegerin ligand leading to osteoporosis as well as erosions. Bone densitometry using dual energy X-ray absorptiometry is an objective and precise method for monitoring this bone disease. Bone loss is more rapid in patients with early rheumatoid arthritis and correlates well with measures of inflammation and function. Data are emerging that monitoring bone loss of the hands in early rheumatoid arthritis could be an outcome measure and a prognostic indicator of future functional disability. Suppressing inflammation effectively and the use of bone active agents can reduce the rate of loss. In animal models, osteoprotegerin—a decoy receptor of osteoprotegerin ligand—blocks osteoporosis and erosions without affecting inflammation. The use of new biological agents could in future effectively prevent and treat rheumatoid bone disease.