Role of nuclear factor-κB in the regulation of intercellular adhesion molecule 1 after infection of human bronchial epithelial cells by Bordetella pertussis

Previous work has demonstrated that infection of human bronchial epithelial cells by Bordetella pertussis up-regulates intercellular adhesion molecule-1 (ICAM-1) gene and protein expression. It has also been shown that interaction of the Arg-Gly-Asp (RGD) site of filamentous hemagglutinin (FHA) with host cell very late antigen (VLA)-5 (alpha5beta1 integrin) is required for the up-regulation of epithelial ICAM-1 expression, and that pertussis toxin (PT) impairs this response. We therefore examined the molecular mechanisms leading to B. pertussis-induced ICAM-1 up-regulation in BEAS-2B human bronchial epithelial cells. A colorimetric nuclear factor kappaB (NF-kappaB) activation assay demonstrated that NF-kappaB was activated in response to infection of these cells with B. pertussis. This activation occurred in an FHA(RGD)-dependent manner, and was blocked by an antibody against VLA-5, implying that binding of the RGD to VLA-5 integrin is involved in NF-kappaB activation. Western blot analysis revealed that the activation of NF-kappaB by B. pertussis was preceded by degradation of IkappaBalpha, a major cytoplasmic inhibitor of NF-kappaB. Pretreatment of the BEAS-2B cells with the NF-kappaB inhibitors pyrrolidine dithiocarbamate (PDTC), MG-132, and SN50 resulted in a marked decrease in B. pertussis-induced ICAM-1 expression, implying the involvement of NF-kappaB in ICAM-1 expression. Purified PT abrogated both NF-kappaB activation and IkappaBalpha degradation. These results suggest that ligation of VLA-5 integrin by FHA induces RGD-dependent NF-kappaB activation, thus leading to the up-regulation of epithelial ICAM-1 expression, and that a PT-sensitive G protein may be involved in this signaling pathway. (C) 2003 Elsevier Ltd. All rights reserved.