Collagen deficiency may develop osteoarthritis

Researchers at Duke University Medical Center, under a grant from the National Institutes of Health (NIH), conducted a study of mice to determine the effect of Type IX collagen (Col9a1) deficiency on functional ability. The authors found that mice with the Col9a1 gene inactivated prematurely develop Osteoarthritis and degenerative disc disease. Findings of this study appear in the September issue of Arthritis & Rheumatism, a journal of the American College of Rheumatology, published by Wiley-Blackwell.

Duke University researchers led by Kyle Allen, Ph.D. compared the behavioral abilities of Col9a1 deficient mice to wild-type (WT) mice. Mice of advanced age (9-11 months) were selected because they represent an age at which there is histological evidence of Osteoarthritis and DDD. Functional tests of reflexes, posture, strength, coordination, balance, sensorimotor skills, and gait were conducted to measure physical capabilities that could be impaired due to Osteoarthritis or degenerative disc disease. Symptomatic pain was assessed through mechanical and thermal withdrawal thresholds.

"We observed a pattern of behavioral changes in the collagen deficient mice that suggests a relationship to Osteoarthritis- and DDD-like degeneration," stated Dr. Allen. The data shows that mice deficient in Type IX collagen clearly displayed behavioral characteristics of pain and functional loss. These mice had delayed righting reflex (ability to regain footing from a back position), decreased sensorimotor skills, and altered gait compared with WT mice. Collagen deficient mice also had elevated levels of knee and intervertebral disc structural changes.

According to the study, collagen deficient mice chose movements that limited peak joint forces and behaviors that reduced pain sensations. "In future work, these measures may help track signs and symptoms as degeneration progresses," added Dr. Allen. "Further studies of the mouse model could provide useful data for evaluating the efficacy of therapeutic interventions for musculoskeletal disorders."

By Wiley-Blackwell