Background: Defining the remission criteria of rheumatoid arthritis (RA) remains a critical issue. Markers of synovium activity -urinary glucosyl-galactosyl-pyridinoline (Glc-Gal-PYD)- and of cartilage destruction -urinary C-terminal crosslinking telopeptide of type II collagen (CTX-II)- have been shown previously to reflect disease activity and joint damage progression in RA.
Methods: The prospective study cohort was comprised of 66 RA patients treated with infliximab and methotrexate and 76 healthy controls. Measurements of Glc-Gal-PYD and CTX-II were performed on urines collected at baseline and at one year of infliximab therapy.
Results: At baseline, urinary Glc-Gal-PYD and CTX-II levels were significantly higher in RA patients than in controls. The baseline level of urinary Glc-Gal-PYD and CTX-II significantly correlated to bone erosion, joint space narrowing, the total Sharp score, and progression of joint damage. Infliximab therapy reduced Glc-Gal-PYD in patients only with high baseline levels. Patients with more progressive joint destruction had higher Glc-Gly-PYD and CTX-II baseline levels.
Conclusion: These markers of synovial and cartilage were modulated by infliximab therapy. They reflected bone erosion evolution and might be useful for treatment monitoring and evaluation of RA. However, markers also remained high even in clinical responders after infliximab, thus suggesting there is an active persistence of synovitis.