A. Ferreira Mendes, A. Pato Carvalho, M. Margarida Caramona, M. Celeste Lopes, "Diphenyleneiodonium inhibits NF-κB activation and iNOS expression induced by IL-1β: involvement of reactive oxygen species", Mediators of Inflammation, vol. 10, Article ID 379585, 7 pages, 2001. https://doi.org/10.1080/09629350120080401
Diphenyleneiodonium inhibits NF-κB activation and iNOS expression induced by IL-1β: involvement of reactive oxygen species
Aims: In this work, we studied the mechanisms by which diphenyleneiodonium chloride (DPI) inhibits nitric oxide (NO) synthesis induced by the pro-inflammatory cytokine interleukin-1β (IL-1) in bovine articular chondrocytes. To achieve this, we evaluated the ability of DPI to inhibit the expression and activity of the inducible isoform of the NO synthase (iNOS) induced by IL-1. We also studied the ability of DPI to prevent IL-1-induced NF-κB activation and reactive oxygen species (ROS) production.Results: Northern and Western blot analysis, respectively, showed that DPI dose-dependently inhibited IL-1-induced iNOS mRNA and protein synthesis in primary cultures of bovine articular chondrocytes. DPI effectively inhibited NO production (IC50 = 0.03 Ī 0.004 μ M), as evaluated by the method of Griess. Nuclear factor-kappa B (NF- κB) activation, as evaluated by electrophoretic mobility shift assay, was inhibited by DPI (1-10 μ M) in a dose-dependent manner. IL-1-induced ROS production, as evaluated by measurement of dichlorofluorescein fluorescence, was inhibited by DPI at concentrations that also prevented NF-κB activation and iNOS expression.Conclusions: DPI inhibits IL-1-induced NO production in chondrocytes by two distinct mechanisms: (i) by inhibiting NOS activity, and (ii) by preventing iNOS expression through the blockade of NF-κB activation. These results also support the involvement of reactive oxygen species in IL-1-induced NF-κB activation and expression of NF-κB-dependent genes, such as iNOS.
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