Matrix Metalloproteinase-3 induces proteoglycan degradation in gouty arthritis model

Gout is an inflammatory arthritis resulting from precipitation of monosodium urate (MSU) crystals in joints and surrounding tissues. However, the mechanism underlying high levels of uric acid inducing gouty arthritis has not been clarified.

The purpose was to investigate the role of Matrix Metalloproteinase-3 (MMP-3) in the development of gouty arthritis from hyperuricemia.

MSU crystal-induced gouty arthritis model and chondrocytes were used to evaluate changes of MMP-3 levels. Western blot, qPCR and ELISA were performed to detect MMP-3, Tissue Inhibitors of Metalloproteinase-1 (TIMP-1) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs-4 (ADAMTS-4) expressions in rabbit chondrocytes. Expression of proteoglycan was determined through toluidine blue staining. Concentrations of glycosaminoglycan, Interleukin-6 (IL-6), Interleukin-1β (IL-1β) and Tumor Necrosis Factor-α (TNF-α) in chondrocytes were assessed via ELISA kits. Concentration of uric acid in supernate was tested by Automatic Analyzer.

MMP-3 was significantly increased in rat serum, synovial fluid, cartilages and chondrocytes treated with high-level uric acid. Increased concentration of glycosaminoglycancould be observed in chondrocytes incubated with MMP-3, as well as the remarkable downregulation of proteoglycan expression. Furthermore, high-level uric acid contributed to the degradation of proteoglycan via the activation of MMP-3. IL-6, IL-1β and TNF-α concentrations were increased significantly in 35 °C compared to 37 °C with MMP-3 and high-level uric acid.

Our study showed that MMP-3 was enhanced by high levels of uric acid, which promoted proteoglycan degradation, and induced MSU crystallization in turn. A low temperature environment is an important factor in the development of gout.