Activation of the transcription factor NF-κB by Campylobacter jejuni

Campylobacter jejuni is a food-borne pathogen responsible for infectious enterocolitis. The early-response transcription factor NF-kappaB triggers the expression of genes associated with cellular immune and inflammatory responses. Co-incubation of HeLa cells with viable C jejuni leads to the activation of the transcription factor NF-kappaB as determined by specific induction of a cellular luciferase-based reporter. Boiled cell-free extracts of C jejuni are also potent dose-dependent stimulators of NF-kappaB-dependent transcription, the levels of which can reach up to 1000-fold as compared with independent controls. Using both cultured HeLa cells and human colonic epithelial (HCA-7) cells, the activation of NF-kappaB by C. jejuni boiled extract has been monitored through the degradation of IKBalpha and DNA binding of the nuclear translocated p50/p65 heterodimer of NF-kappaB. These events are co-ordinated with elaboration of the pro-inflammatory cytokine interleukin-8. Fractionation of the boiled C jejuni extract suggests that the majority of the bioactive component has a molecular mass of 3 kDa or less, which is insensitive to proteinase K treatment.