Urinary excretion of glucosyl‐galactosyl pyridinoline: a specific biochemical marker of synovium degradation

Abstract

Objective. Glucosyl‐galactosyl pyridinoline (Glc‐Gal‐PYD), which has been identified in urine, is a glycosylated analogue of pyridinoline. The tissue distribution of this molecule has not been yet determined and its utility as a potential biochemical marker of joint degradation in patients with joint diseases has not been investigated. Methods and results. In this study, we demonstrate that Glc‐Gal‐PYD is abundant in human synovium tissue, absent from bone and present in minute amounts in cartilage and other soft tissues, such as muscle and liver. Using an ex vivo model of human joint tissue degradation, we found that Glc‐Gal‐PYD is released from synovium tissue, but not from bone and cartilage. The urinary level of Glc‐Gal‐PYD was increased by 109% in patients with rheumatoid arthritis (RA) compared with healthy adults, but was normal in patients with Paget's disease of bone. In addition, Glc‐Gal‐PYD was higher in those patients with destructive disease, as assessed by X‐rays of the joints, than in those with non‐destructive RA. Conclusion. Glc‐Gal‐PYD may be useful for the clinical investigation of patients with joint disease.