Arthropod steroid hormone (20-Hydroxyecdysone) suppresses IL-1β-induced catabolic gene expression in cartilage.

BACKGROUND: In osteoarthritis (OA), the imbalance of chondrocytes' anabolic and catabolic factors can induce cartilage destruction. Interleukin-1 beta (IL-1β) is a potent pro-inflammatory cytokine that is capable of inducing chondrocytes and synovial cells to synthesize MMPs. The hypoxia-inducible factor-2alpha (HIF-2alpha, encoded by Epas1) is the catabolic transcription factor in the osteoarthritic process. The purpose of this study is to validate the effects of ecdysteroids (Ecd) on IL-1β-induced cartilage catabolism and the possible role of Ecd in treatment or prevention of early OA.

METHODS: Chondrocytes and articular cartilage was harvested from newborn ICR mice. Ecd effect on chondrocytes viability was tested and the optimal concentration was determined by MTT assay. The effect of HIF-2α (EPAS1) in cartilage catabolism simulated by IL-1β (5 ng/ml) was evaluated by articular cartilage explants culture. The effects of Ecd on IL-1β-induced inflammatory conditions and their related catabolic genes expression were analyzed.

RESULTS: Interleukin-1β (IL-1β) treatment on primary mouse articular cartilage explants enhanced their Epas1, matrix metalloproteinases (MMP-3, MMP-13) and ADAMTS-5 genes expression and down-regulated collagen type II (Col2a1) gene expression. With the pre-treatment of 10(-8) M Ecd, the catabolic effects of IL-1β on articular cartilage were scavenged.

CONCLUSION: In conclusions, Ecd can reduce the IL-1β-induced inflammatory effect of the cartilage. Ecd may suppress IL-1β-induced cartilage catabolism via HIF-2α pathway.