Objective Heat shock proteins are molecules rapidly produced under conditions of environmental stress, and involve in protecting the cells structural integrity and function. Osteoarthritis (OA) is a chronic destructive disorder of the joints manifested by the ongoing deterioration and loss of articular cartilage. The present study aimed to analyze circulating and synovial heat shock protein (Hsp70) values in knee osteoarthritis patients and healthy controls and to determine their relationship with the radiographic grading of the severity of knee OA. Design Seventy-two subjects with knee OA and 30 control participants were recruited. Circulating and joint fluid Hsp70 values were quantified by commercially available enzyme-linked immunosorbent assay. Results Circulating Hsp70 was markedly higher in knee OA patients compared with that of healthy volunteers ( P = 0.01). Correspondingly, synovial fluid Hsp70 was 3-fold greater than paired circulating Hsp70 samples ( P < 0.001). Further analysis revealed that circulating and joint fluid Hsp70 values were significantly related with the radiographic severity of knee OA ( r = 0.413, P < 0.001 and r = 0.658, P < 0.001, respectively). Subsequently, circulating Hsp70 value was directly associated with joint fluid Hsp70 value ( r = 0.704, P < 0.001). Conclusions Circulating and synovial Hsp70 levels were positively correlated with the radiographic severity of knee OA. Hsp70 could represent a potential biochemical marker for predicting the severity and may play a fundamental part in the pathogenic mechanism of knee OA.

Objective Glypican-3 possesses a possible action in regulation of bone growth and development implicated in osteoarthritis (OA) pathology. Therefore, this study aimed to investigate glypican-3 in plasma and synovial fluid of knee OA patients and to determine the possible association between glypican-3 levels and radiographic severity. Design A total of 80 knee OA patients and 80 healthy controls were recruited. Glypican-3 levels in plasma and synovial fluid were measured using enzyme-linked immunosorbent assay. The severity of knee OA was assessed by radiographic grading according to the Kellgren-Lawrence classification. Relative mRNA expression of glypican-3 in 10 inflamed synovial tissues from OA patients and 10 noninflamed synovial controls was quantified using real-time polymerase chain reaction. Results Plasma glypican-3 levels were significantly lower in OA patients than in healthy controls ( P = 0.03), whereas synovial fluid glypican-3 levels were remarkably greater than in paired plasma samples of OA patients ( P < 0.001). Subsequent analysis demonstrated that plasma and synovial fluid glypican-3 levels were inversely associated with the radiographic severity of knee OA ( r = −0.691, P < 0.001; r = −0.646, P < 0.001, respectively). Furthermore, there was a positive relationship between plasma and synovial fluid glypican-3 levels in knee OA patients ( r = 0.515, P < 0.001). Additionally, overexpression of glypican-3 mRNA was observed in inflamed synovium of OA patients ( P = 0.021). Conclusions The present study revealed that plasma and synovial glypican-3 levels were negatively associated with radiographic severity of knee OA. Glypican-3 could emerge as a potential biomarker for reflecting the severity of knee OA and might play a plausible role in the pathophysiology of degenerative joint disease.