Synovial inducible costimulator is correlated with severity in knee osteoarthritis

Osteoarthritis (OA) is a joint disease characterized by articular cartilage loss, which afflicts many people worldwide. Knowing the disease severity can improve the recovery rate of OA. Antibody array technology was utilized for protein expression profiling of synovial fluid from eight mild knee OA patients, eight severe knee OA patients and 16 healthy persons. Subsequently, 48 mild OA patients, 56 severe OA patients and 24 healthy controls were utilized for validation by ELISA. In the protein expression profiling, inducible costimulator (ICOS) levels were markedly higher in OA patients compared with those in the healthy population, and were significantly higher in severe OA than those in mild OA. Furthermore, ICOS levels were shown to be significantly correlated with WOMAC, MRI-MOAKS and MRI-UTE-T2* scores. The multivariate logistic regression analysis indicated that higher levels of ICOS could significantly increase the risk of severe OA. Synovial ICOS levels were positively correlated with the radiographic severity of OA. ICOS may represent a biomarker for predicting the OA severity and may be involved in the development and progression of knee OA.