Influences of menopause, aging, and gender on the cleavage of type II collagen in cartilage in relationship to bone turnover

Abstract

In Brief Objective: It is unclear whether there are changes in cartilage turnover after menopause, although these are well documented in bone. The aim of this study was to explore the possibility that menopause might change cartilage turnover as well as bone turnover. We also examined age and gender to estimate the independent influences of these parameters together with menopause on cartilage and bone turnover. Design: Serum samples were collected from 140 healthy volunteers, 69 men (mean age ± SD, 42.8 ± 13.8 y) and 71 women (44.4 ± 10.5 y) with self-reported pre- or postmenopausal status who had no swelling or pain in their spine and joints. Body mass index was also recorded. The serum concentration of a biomarker of cartilage type II collagen (C2C) degradation and concentrations of serum bone alkaline phosphatase and urine cross-linked type I collagen N-telopeptide, both accepted biomarkers of bone turnover, were measured together. Analyses of covariance were performed to test the mean differences of biomarkers by gender and by menopause status with age adjustment. Results: In men there were no significant correlations between age and the biomarkers. In women C2C concentration decreased with age. Cross-linked type I collagen N-telopeptide and bone alkaline phosphatase levels were both increased after menopause, whereas C2C showed no detectable changes. C2C was not significantly related to body mass index. Conclusions: This study suggests that there are fundamental differences in the degradation of uncalcified C2C and bone type I collagen degradation and bone assembly in response to menopause and aging. The advent of new protein biomarkers for the in vivo study of bone and cartilage turnover has provided us with an important new opportunity to investigate skeletal changes in cartilage that may occur with menopause. The results of this study suggest that there are fundamental differences in bone and cartilage turnover associated with the changes that take place with menopause and aging.