title: Diclofenac enhances proinflammatory cytokine-induced nitric oxide production through NF-kappaB signaling in cultured astrocytes.
abstract: Recently, the number of reports of encephalitis/encephalopathy associated with influenza virus has increased. In addition, the use of a non-steroidal anti-inflammatory drug, diclofenac sodium (DCF), is associated with a significant increase in the mortality rate of influenza-associated encephalopathy. Activated astrocytes are a source of nitric oxide (NO), which is largely produced by inducible NO synthase (iNOS) in response to proinflammatory cytokines. Therefore, we investigated whether DCF enhances nitric oxide production in astrocytes stimulated with proinflammatory cytokines. We stimulated cultured rat astrocytes with three cytokines, interleukin-1beta, tumor necrosis factor-alpha and interferon-gamma, and then treated the astrocytes with DCF or acetaminophen (N-acetyl-p-aminophenol: APAP). iNOS and NO production in astrocyte cultures were induced by proinflammatory cytokines. The addition of DCF augmented NO production, but the addition of APAP did not. NF-kappaB inhibitors SN50 and MG132 inhibited iNOS gene expression in cytokine-stimulated astrocytes with or without DCF. Similarly, NF-kappaB p65 Stealth small interfering RNA suppressed iNOS gene expression in cytokine-stimulated astrocytes with or without DCF. LDH activity and DAPI staining showed that DCF induces cell damage in cytokine-stimulated astrocytes. An iNOS inhibitor, L-NMMA, inhibited the cytokine- and DCF-induced cell damage. In conclusion, this study demonstrates that iNOS and NO are induced in astrocyte cultures by proinflammatory cytokines. Addition of DCF further augments NO production. This effect is mediated via NF-kappaB signaling and leads to cell damage. The enhancement of DCF on NO production may explain the significant increase in the mortality rate of influenza-associated encephalopathy in patients treated with DCF.
authors.affiliation: Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kakita
authors.forename: Mineyoshi
authors.initials: M
authors.lastname: Aoyama
authors.forename: Mohamed Hamed
authors.initials: MH
authors.lastname: Hussein
authors.forename: Shin
authors.initials: S
authors.lastname: Kato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Suzuki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ito
authors.forename: Hajime
authors.initials: H
authors.lastname: Togari
authors.forename: Kiyofumi
authors.initials: K
authors.lastname: Asai
mesh_terms: D000082:Acetaminophen / Q000494:pharmacology; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000633:toxicity*; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D004008:Diclofenac / Q000633:toxicity*; D004660:Encephalitis / Q000209:etiology / Q000401:mortality; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D007371:Interferon-gamma / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D053583:Interleukin-1beta; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D004008:Diclofenac; D009569:Nitric Oxide; D000082:Acetaminophen; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II