The expression of SIRT1 in articular cartilage of patients with knee osteoarthritis and its correlation with disease severity

Background: The study aims to investigate the expression of SIRT1 in articular cartilage of patients with primary knee osteoarthritis (OA) and its relationship with disease severity. Methods: Cartilage tissue samples were collected from 38 knee OA patients and 9 normal healthy controls and then ascribed to normal, mild, moderate, and severe groups on the basis of the improved Mankin grading system. The expression of SIRT1 in articular cartilage was detected by immunohistochemistry and western blots. The expression of p53 and acetylated p53 (Ac-p53) was also measured by western blots. Results: The mutual comparisons of the SIRT1 expression levels in all groups have statistical significance except the one between the mild and moderate groups. Moreover, western blot results showed that the SIRT1 was decreased and p53/Ac-p53 were increased in the OA group. The average gray level of SIRT1 increases with the improving grade of the improved Mankin grading system scorers. Conclusions: The expression of SIRT1 in articular cartilage is negatively associated with severity of knee OA, indicating that SIRT1 may act as a monitoring indicator for determining development and progression of knee OA.