The urinary excretion of pyridinoline and deoxypyridinoline during rheumatoid arthritis therapy with infliximab

Rheumatoid arthritis is a systemic disease that causes inflammation and joint destruction. As a result of pathological destruction in bone and cartilage, crosslinks in collagen are resorbed more rapidly. This causes a rise in circulating collagen crosslink levels and their urinary excretion. In RA, apart from the crosslink resorption at the site of inflamed joints, there may be increased resorption due to general bone loss associated with disease activity. The aim of this study was to evaluate the influence of therapy with infliximab on urinary excretion of pyridinoline (PYD) and deoxypyridinoline (DPYR) as a markers of collagen degradation and its correlation with clinical and biochemical parameters of disease activity. Seventeen patients with active rheumatoid arthritis treated with infliximab were recruited into the study. The therapy resulted in the reduction in the symptoms of RA and urinary excretion of PYD and DPYR. The urinary excretion of PYD correlated with a number of swollen joints, morning stiffness, CRP and ESR. The urinary excretion of DPYR correlated during infliximab therapy with the number of swollen and tender joints and morning stiffness. The measurement of urinary excretion of PYR and DPYR may give insight into bone metabolism and help us to better understand the actual changes in bone and cartilage caused by RA and its treatment.