Differential expression of adipokines in the synovium and infrapatellar fat pad of osteoarthritis patients with and without metabolic syndrome

Abstract

Objective: To evaluate the expression levels of adipokines in the synovium and infrapatellar fat pad (IPFP) in osteoarthritis (OA) patients with and without metabolic syndrome (MetS).Methods: 120 female patients with OA were enrolled, and 60 healthy women matched body mass index, age, and sex, served as controls. Adipokines levels were measured using a sandwich enzyme-linked immunosorbent assay of the serum of all participants and synovial fluid (SF) of OA patients. Local expression levels of adipokines in the synovium and IPFP were examined by immunohistochemical analysis. The amount of adipokine proteins was analyzed using Western blot, and adipokine mRNA expressions were determined via quantitative real-time polymerase chain reaction (qRT-PCR).Results: Serum leptin levels were significantly higher in the non-MetS-OA group than those in controls (7.97 vs. 4.24 ng/ml, p< 0.001), and even higher leptin levels were found in the MetS-OA group (19.05 ng/ml; p< 0.001 for both). Serum adiponectin levels were significantly lower in the MetS-OA group than those in controls (8.09 vs. 10.07 μg/ml, respectively; p= 0.001). The synovium and IPFP in the MetS-OA group secreted more leptin and less adiponectin than those in the non-MetS-OA group (Leptin: 5.32 vs. 1.28 in synovium, respectively; p= 0.028; 6.44 vs. 0.88 in IPFP, respectively; p= 0.017. Adiponectin: 1.12 vs. 0.12 in synovium, respectively; p= 0.042; 1.07 vs. 0.09 in IPFP, respectively; p= 0.027). Resistin expression levels in the serum, SF, and articular tissues were similar among the groups.Conclusions: Expressions of adipokines were different in the synovium and IPFP of OA patients with and without MetS.