[Roles of collagen enzymatic and advanced glycation end products associated crosslinking as a determinant of bone quality].

Recently, data have accumulated that collagen cross-link formation in bone affect bone strength. In fact, impaired enzymatic cross-linking and/or an increase in non-enzymatic cross-links, pentosidine (Pen), which is a surrogate marker of advanced glycation end products (AGEs), in bone collagen have been proposed as a major cause of bone fragility in aging, osteoporosis and diabetes mellitus. This review will summarize the mechanism of formation of cross-linking in bone collagen and important aspects of alterations in collagen enzymatic immature and mature cross-links and non-enzymatic senescent type of cross-link (AGEs), in aging, osteoporosis, and diabetes mellitus. We also review recent developments in bone quality-related markers such as serum or urine pentosidine levels and serum homocysteine levels for fracture assessment in patients with osteoporosis and diabetes mellitus.