Activation of nuclear factor kappa B in inflammatory bowel disease

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Abstract
Background—Expression of pro-inflammatory cytokines is increased in the intestinal lamina propria of patients with inflammatory bowel disease (IBD). Nuclear factor κB (NFκB) controls transcription of inflammation genes. On activation, NFκB is rapidly released from its cytoplasmic inhibitor (IκB), transmigrates into the nucleus, and binds to DNA response elements in gene promoter regions. Aims—To investigate whether increased activation of NFκB is important in IBD and may be down-regulated by anti-inflammatory treatment. Methods—Activation of NFκB was determined by western blot assessment and electrophoretic mobility shift assay in nuclear extracts of colonic biopsy samples as well as lamina propria mononuclear cells. Results—Nuclear levels of NFκB p65 are increased in lamina propria biopsy specimens from patients with Crohn’s disease in comparison with patients with ulcerative colitis and controls. Increased activation of NFκB was detected in lamina propria mononuclear cells from patients with active IBD. Corticosteroids strongly inhibit intestinal NFκB activation in IBD in vivo and in vitro by stabilising the cytosolic inhibitor IκBα against activation induced degradation. Conclusions—In both IBDs, but particularly Crohn’s disease, increased activation of NFκB may be involved in the regulation of the inflammatory response. Inhibition of NFκB activation may represent a mechanism by which steroids exert an anti-inflammatory effect in IBD.