Effect of melittin on iNOS and NF-κB expression induced by IL-1βin C518 cells.

Melittin (Mel), a natural detergent, is a major component of bee venom. Mel exhibits favorable clinical effects on the treatment of rheumatoid osteoarthritis, myositis, lumbar muscle strain, and peripheral neurological disorders. Interleukin-1β (IL-1β) contributes to the progression of osteoarthritis and is one of the key proinflammatory cytokines. However, the effect of Mel on IL-1β-induced osteoarthritis has not been reported. We examined the effects of Mel on the expressions of inducible NO synthase (iNOS), nuclear transcription factor κB (NF-κB), and I kappa B (I-κB) in the knee joint cells of C518 rats induced by IL-1β. Western blot and qPCR results showed that Mel at 0.1µg/mL or higher significantly inhibited iNOS expression. Similarly, 1µg/mL of Mel prevented IL-β-induced I-κB degradation in the cytoplasm and NF-κB migration from cytoplasm to nucleus. Mel exerts an inhibitory effect on IL-β-induced NF-κB activation by inhibiting both I-κB degradation and NF-κB migration and can potentially be developed as a new anti-osteoarthritis drug. Further research is needed to clarify the detailed mechanism.