Increased serum fibroblast growth factor-23 (FGF-23) and bone turnover in patients with osteoarthritis of knee

Objective: This study aimed to investigate the serum fibroblast growth factor-23 (FGF-23) of patients with knee osteoarthritis (OA) and to elaborate its correlation with radiographic and symptomatic severity of OA. Methods: Sixty-three subjects were divided into three groups, including healthy controls group (n = 15), patients with rheumatoid arthritis (RA, n = 23) and OA (n = 25). Serum FGF-23 levels were examined by ELISA, and other clinical biochemical parameters were tested based on standard methods. Results: First, we found a significant increase in FGF-23 level in the serum of patients with knee OA compared to healthy controls. Next, an increased trabecular bone formation in subchondral bone was confirmed in the patients with knee OA. In addition, FGF-23 levels were positively correlated with radiographic grading and symptomatic severity of knee OA, and this observation indicated a significant elevation in the systemic levels of FGF-23 correlation with WOMAC scores in patients with knee OA. Furthermore, the results showed that the mRNA and protein expression of FGF-23 were significantly increased in synovial fluid from OA patients as compared to those in healthy control, and the upregulation of FGF-23 could inhibit the apoptosis of mononuclear cell in synovial fluid from OA patients. Conclusions: Serum FGF-23 level was significantly higher and was a significant determinant of increased bone turnover in knee OA patients. FGF-23 might be a potential biomarker for diagnosing and evaluating the onset and development of knee OA.