α-Phenyl-N-tert-Butylnitrone Provides Protection from Dextran Sulfate Sodium-Induced Colitis in Mice

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Abstract
Nuclear factor-κB (NF-κB)-dependent up-regulation of inflammatory cytokines and inducible nitric oxide (iNOS) occurs in inflammatory bowel disease. We investigated the effect of α-phenylN-tert-butylnitrone (PBN), a spin-trapping agent that inhibits NF-κB activity, on dextran sulfate sodium (DSS)-induced colonic mucosal injury and inflammation in mice. Acute colitis was induced with DSS in female BALB/c mice receiving 0, 0.3, 3, and 30 mg/kg i.p. PBN daily. Colonic mucosal inflammation was evaluated biochemically and histologically. Nitric oxide was evaluated as luminal nitrite/nitrite concentration by the Griess reaction and as immunoreactive nitrotyrosine in mucosal cells. Mucosal tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were determined by immunoassay. Colonic mRNA expression for iNOS, TNF-α, and IFN-γ was measured by reverse transcription-polymerase chain reaction, and NF-κB activation was evaluated by electrophoretic mobility shift assay. After DSS administration, mice showed increased luminal nitrite/nitrate, mucosal TNF-α and IFN-γ, and mRNA for iNOS and these cytokines, in addition to decreased colonic length and increased inflammatory score, luminal hemoglobin, and colonic myeloperoxidase activity. PBN inhibited increases in luminal nitric oxide production, nitrotyrosine immunoreactivity, and mucosal TNF-α and IFN-γ. Colonic iNOS, TNF-α, and IFN-γ mRNA were suppressed by PBN, as was a DSS-induced increase in colonic NF-κB DNA-binding activity. NF-κB is essential to DSS-induced colitis, suggesting molecular approach targeting of NF-κB for treatment of inflammatory bowel disease.