Fatty acid binding protein 4 initiates cartilage degeneration through inducing the cytokine expressions of macrophage - an in-vitro study

Abstract

INTRODUCTION: Adipokine-induced inflammation plays roles in the pathogenesis of osteoarthritis (OA). Fatty acid binding protein 4 (FABP-4) is a novel adipokine that has been found to influence both metabolic and inflammatory pathways via the interaction with macrophage. METHODS: Murine macrophage (RAW 264.7) and primary murine chondrocyte (isolated from C57/Bl6 mice) were cultured. In all, 5 concentrations of murine FABP-4 (0, 16, 80, 400, and 2000 ng/mL) were supplemented to the macrophage culture medium and interacted for 24 hours. The conditioned medium was subsequently incubated with chondrocyte for another 24 hours. Gene expressions of cytokines interleukin (IL)-1β, IL-6, and tumour necrosis factor–alpha (TNF-α) of macrophage, and matrix metalloproteinase (MMP)–2, MMP-3, and MMP-13 of chondrocytes were detected using real-time polymerase chain reaction. RESULTS: The mRNA expressions of all targets showed an increasing trend with the rise of FABP-4 concentration, with the expression folds of control (0 ng/mL FABP-4) being 1.62, 1.87, 2.80, 9.15 for IL-1β; 2.62, 4.25, 12.99, 83.71 for IL-6; 1.84, 2.07, 2.35, 2.27 for TNF-α; 0.88, 1.07, 1.40, 2.13 for MMP-2; 1.15, 1.57, 1.75, 2.21 for MMP-3; and 1.03, 1.66, 1.73, 4.63 for MMP-13 under the concentrations of 16, 80, 400 and 2000 ng/mL FABP-4, respectively. CONCLUSIONS: The FABP-4 initiates cartilage degeneration through inducing the cytokine expressions of macrophage.