Combined detection of serum CTX-II and C2C in a rat model of ACLT-induced osteoarthritis.

Osteoarthritis (OA) is a chronic degenerative bone and joint disease that often occurs in aging animals. Currently, there are still no biomarkers that can effectively diagnose OA in the early stage. To identify possible biomarkers, here we examined changes in the expression of C-telopeptide fragments of type II collagen (CTX-II) and collagenase generated carboxy-terminal neoepitope of type II collagen (C2C) in serum at different time points in an anterior cruciate ligament transection (ACLT)-induced rat OA model. The serum levels of CTX-II and C2C, and the OARSI score in the ACLT group were increased from week two until the end of the experiment. The AUC of the combined biomarkers was higher than that of CTX-II or C2C alone. Moreover, serum levels of CTX-II and C2C were positively correlated with the OARSI score. The results suggest that the combined detection of serum CTX-II and C2C concentrations may have potential for assessing and diagnosing OA at early stages.