Increased cartilage type II collagen degradation in patients with osteogenesis imperfecta used as a human model of bone type I collagen alterations

Abstract

Objective We investigated whether cartilage degradation is altered in adult patients with mild osteogenesis imperfecta (OI) used as a human model of bone type I collagen-related osteoarthritis (OA). Patients and methods Sixty-four adult patients with OI (39% women, mean age ± SD: 37 ± 12 years) and 64 healthy age-matched controls (54% women, 39 ± 7 years) were included. We also compared data in 87 patients with knee OA (73% women, 63 ± 8 years, mean disease duration: 6 years) and 291 age-matched controls (80% women, 62 ± 10 years). Urinary C-terminal cross-linked telopeptide of type II collagen (CTX-II), a marker of cartilage degradation, urinary helical peptide of type I collagen (Helix-I), a marker of bone resorption, and the urinary ratio between non-isomerised/isomerised (α/β CTX-I) type I collagen C-telopeptide, a marker of type I collagen maturation, were measured. Results Patients with OI had CTX-II levels similar to those of subjects with knee OA ( p = 0.89; mean ± SEM; 460 ± 57 ng/mmol Cr for OI group and 547 ± 32 ng/mmol Cr for OA group) and significantly higher than both young (144 ± 7.8 ng/mmol Cr, p < 0.0001) and old controls (247 ± 7 ng/mmol Cr, p < 0.0001). In patients with OI, increased Helix-I ( p < 0.0001) and α/β CTX-I ( p = 0.0067) were independently associated with increased CTX-II and together explained 26% of its variance ( p < 0.0001). In patients with knee OA, increased levels of α/β CTX-I ratio were also associated with higher CTX-II levels. Conclusion Adult patients with OI or knee OA are characterized by increased cartilage type II collagen degradation, which is associated with increased type I collagen degradation for OI and lower type I collagen maturation for both OI and OA. These data suggest that both quantitative and qualitative alterations of bone type I collagen metabolism are involved in increased cartilage degradation in patients with OI or knee OA.