Helicobacter pylori induces type 4 secretion system-dependent, but CagA-independent activation of IκBs and NF-κB/RelA at early time points

Colonization of the gastric epithelium by Helicobacterpylori induces the transcription factor nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-kappa B) and the innate immune response. Virulent strains of H. pylori carry a cog pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS). Recent publications have shown controversial data regarding the role of the T4SS and the effector protein cytotoxin associated gene A (CagA), which becomes translocated by the T4SS into the eukaryotic epithelial cell, in H. pylori-induced NF-kappa B activation. Thus, this study analyses by using three different H. pylori strains (P1, B128 and G27) whether CagA is required to initiate activation of different molecules of inhibitors of kappa B (I kappa B) and the NF-kappa B transcription factor RelA. We provide experimental evidence that H. pylori induces phosphorylation of NF-KB inhibitors I kappa Bot, I kappa Bp and I kappa Bs, and degradation of IKBcz. Further, H. pylori stimulates phosphorylation of RelA at amino acids S536, S468 and S276, promotes DNA binding of RelA, and interleukin 8 (IL-8) gene expression in a T4SS-, but CagA-independent manner at early time points. (C) 2013 Elsevier GmbH. All rights reserved.