OBJECTIVE: To study whether the induction of mRNA for interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and collagenase by tumor necrosis factor-alpha (TNF-alpha) is suppressed by antioxidants in human synovial cells. TNF-alpha has been shown to exert some of its effects by stimulating production of reactive oxygen intermediates in some cell lines other than synovial cells. METHODS: Amounts of mRNA for IL-8, MCP-1, and collagenase were determined by Northern blot analysis. Electrophoretic mobility shift assays were performed for the detection of a transcription factor, nuclear factor-kappa B(NF-kappa B). The concentration of IL-8 in the medium was determined by ELISA. RESULTS: TNF-alpha increased the expression of IL-8, MCP-1, and collagenase mRNA in human synovial cells. NF-KB known to induce IL-8 gene transcription was also increased in nuclear extracts from the synovial cells treated with TNF-alpha. Prior addition of antioxidant, N-acetyl-L-cysteine (NAC) or 2-oxothiazolidine-4-carboxylate (OTC), suppressed TNF-alpha stimulated expressions of IL-8, MCP-1, and collagenase mRNA in a dose dependent manner. Treatment with NAC also suppressed TNF-alpha induced increase in NF-kappa B. The changes of IL-8 in the medium reflected the mRNA levels. Hydrogen peroxide (H2O2) induced the expression of mRNA for the cytokines but not collagenase mRNA, and NAC suppressed the effect of H2O2. CONCLUSION: Our data suggest that TNF-alpha induces expression of proinflammatory cytokines such as IL-8 and MCP-1 through generation of reactive oxygen intermediates and subsequent activation of NF-kappa B in human synovial cells, and the antioxidants may inhibit, at least in part, the activation of NF-kappa B by TNF-alpha. These results indicate that antioxidants such as NAC may be useful in treating rheumatoid arthritis.
OBJECTIVE: To study whether the induction of mRNA for interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and collagenase by tumor necrosis factor-alpha (TNF-alpha) is suppressed by antioxidants in human synovial cells. TNF-alpha has been shown to exert some of its effects by stimulating production of reactive oxygen intermediates in some cell lines other than synovial cells. METHODS: Amounts of mRNA for IL-8, MCP-1, and collagenase were determined by Northern blot analysis. Electrophoretic mobility shift assays were performed for the detection of a transcription factor, nuclear factor-kappa B(NF-kappa B). The concentration of IL-8 in the medium was determined by ELISA. RESULTS:TNF-alpha increased the expression of IL-8, MCP-1, and collagenase mRNA in human synovial cells. NF-KB known to induce IL-8 gene transcription was also increased in nuclear extracts from the synovial cells treated with TNF-alpha. Prior addition of antioxidant, N-acetyl-L-cysteine (NAC) or 2-oxothiazolidine-4-carboxylate (OTC), suppressed TNF-alpha stimulated expressions of IL-8, MCP-1, and collagenase mRNA in a dose dependent manner. Treatment with NAC also suppressed TNF-alpha induced increase in NF-kappa B. The changes of IL-8 in the medium reflected the mRNA levels. Hydrogen peroxide (H2O2) induced the expression of mRNA for the cytokines but not collagenase mRNA, and NAC suppressed the effect of H2O2. CONCLUSION: Our data suggest that TNF-alpha induces expression of proinflammatory cytokines such as IL-8 and MCP-1 through generation of reactive oxygen intermediates and subsequent activation of NF-kappa B in human synovial cells, and the antioxidants may inhibit, at least in part, the activation of NF-kappa B by TNF-alpha. These results indicate that antioxidants such as NAC may be useful in treating rheumatoid arthritis.