Silica–ceramic suppresses the expression of proinflammatory cytokines induced by lipopolysaccharide in macrophages

Bioactive materials have previously been used to coat implants. In a new development for bioactive materials, a silica-ceramic mixture was found to alleviate pain (Lee, Poster presented at the Ninth World Congress of Gynecological Endocrinology, Hongkong, 2001. Poster session (p47)). Here, we hypothesized that silica-ceramic can reduce the expression and activity of cyclooxygenase 2 (COX2) or cytokines associated with inflammation. The production of COX2 and proinflammatory cytokines was investigated by reverse transcriptase (RT)-PCR and ELISA assay in macrophages stimulated by lipopolysaccharide (LPS). Silica-ceramic had no effect of COX2 expression and prostaglandin production in macrophages. However, silica-ceramic suppressed the synthesis of cytokines involved in inflammation, in particular, the expression of IL-1beta and IL-6 was reduced at the transcriptional and translational levels. The involvement of NF-kappaB in the suppression of cytokines by silica-ceramic was examined by luciferase reporter assay. The NF-kappaB activity stimulated by LPS was inhibited by 20-60% with silica-ceramic compared with treatment with LPS alone. We suggest that inhibition of NF-kappaB activity by silica-ceramic might cause the attenuation of proinflammatory cytokine expression in macrophages. In conclusion, silica-ceramic could be an alternative approach to regulate the inflammation process.