Transcription factors of the nuclear factor κB (NF-κB) family play an important role in the regulation of genes involved in inflammation. In inflammatory bowel diseases, proinflammatory cytokines known to be regulated by NF-κB are involved. The aim of this study was to investigate the role of NF-κB activation during mucosal inflammation in situ.

A monoclonal antibody, α-p65mAb, was applied for immunofluorescence and immunohistochemical analysis that recognizes activated NF-κB. Electrophoretic mobility shift assay was used to directly demonstrate the presence of active DNA-binding NF-κB.

Using the α-p65mAb antibody, activated NF-κB could be found in biopsy specimens from inflamed mucosa but was almost absent in uninflamed mucosa. The number of cells showing NF-κB activation correlated with the degree of mucosal inflammation but was not significantly different between inflamed mucosa from patients with Crohn's disease, ulcerative colitis, and nonspecific colitis or diverticulitis. NF-κB activation was localized in macrophages and in epithelial cells as identified by double-labeling techniques. Electrophoretic mobility shift assay with isolated lamina propria mononuclear cells and epithelial cells confirmed these results.

This study shows for the first time the activation of NF-κB during human mucosal inflammation in situ. In addition to macrophages, epithelial cells contained activated NF-κB, indicating an involvement in the inflammatory process. GASTROENTEROLOGY 1998;115:357-369