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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. [ABSTRACT FROM AUTHOR]

Background: Major reports have suggested that bone mineral density (BMD) is higher in patients with osteoarthritis (OA), while other studies do not agree. Our aim was to examine the cross-sectional association between phalangeal BMD and radiographic knee OA.Methods: A total of 2855 participants were included in this study. Radiographic knee OA was defined as Kellgren-Lawrence (K-L) Grade ≥ 2 in at least one leg. BMD scans of the middle phalanges of the second, third and fourth digits of the nondominant hand were performed with a compact radiographic absorptiometry system (Alara MetriScan®). A multivariable logistic analysis model was applied to test the relation between phalangeal BMD with radiographic knee OA, the presence of knee osteophytes (OSTs), and knee joint space narrowing (JSN) after adjusting for a number of potential confounding factors.Results: The multivariable-adjusted odds ratios with 95 % confidence intervals [ORs (95 % CI)] of radiographic knee OA across phalangeal BMDs were 1.08 (95 % CI 0.89-1.32) and 0.62 (95 % CI 0.45-0.86), respectively. The P for trend was 0.09. For the female population, the multivariable-adjusted ORs (95 % CI) of radiographic knee OA across phalangeal BMD were 1.01 (95 % CI 0.73-1.37) and 0.58 (95 % CI 0.38 - 0.87), respectively. The P for trend was 0.02. This positive finding, however, did not exist in the male subgroup. There was a significantly lower prevalence of OST in the osteoporosis (OP) group than in the normal group (OR = 0.59, 95 % CI 0.40-0.88; P for trend was 0.01). In contrast, the prevalence of JSN was significantly higher in the osteopenia group (OR = 1.22, 95 % CI 1.00-1.48) and the OP group (OR = 1.35, 95 % CI 1.00-1.84) than in the normal group. The P for trend was 0.02.Conclusions: This study observed lower odds for the presence of radiographic knee OA and OST in OP patients than in normal subjects. The prevalence of JSN was higher in the osteopenia and OP groups than in normal subjects. [ABSTRACT FROM AUTHOR]