[Assay of cross-linking molecules of collagen (pyridinolines) in the study of the degradation of bone tissue and articular cartilage].

Recent studies aimed at studying the degradation of the fibrillar collagens of bone and articular cartilage have lead to the discovery of naturally fluorescent crosslinking compounds derived from lysine and hydroxylysine. These small molecules characterized by an aromatic 3-hydroxypyridinium ring are present in significant amounts only in bone (pyridinoline and deoxy-pyridinoline) and cartilage (pyridinoline). Diseases characterized by an increased degradation of the fibrillar collagenous network are associated with an increased urinary excretion of both compounds: Pyridinoline and deoxypyridinoline are currently the most sensitive and specific markers of bone resorption. The purpose of this paper is to review current knowledge in the area of collagen crosslinking molecules with special emphasis on the pyridinium crosslinking amino acids and their potential clinical application as a marker of bone and cartilage degradation.