BabA-mediated Adherence Is a Potentiator of the Helicobacter pylori Type IV Secretion System Activity.

Chronic infection of Helicobacter pylori in the stomach mucosa with translocation of the bacterial cytotoxin-associated gene A (CagA) effector protein via the cag-Type IV secretion system (TESS) into host epithelial cells are major risk factors for gastritis, gastric ulcers, and cancer. The blood group antigenbinding adhesin BabA mediates the adherence of H. pylori to ABO/Lewis b (Leb) blood group antigens in the gastric pit region of the human stomach mucosa. Here, we show both in vitro and in vivo that BabA-mediated binding of H. pylori to Leb on the epithelial surface augments TESS-dependent H. pylori pathogenicity by triggering the production of proinflammatory cytokines and precancer-related factors. We successfully generated Leb-positive cell lineages by transfecting Leb-negative cells with several glycosyltransferase genes. Using these established cell lines, we found increased mRNA levels of proinflammatory cytokines (CCLS and IL-8) as well as precancer-related factors (CDX2 and MUC2) after the infection of Leb-positive cells with WT H. pylon but not with babA or TFSS deletion mutants. This increased mRNA expression was abrogated when Leb-negative cells were infected with WT H. pylori. Thus, H. pylori can exploit BabA-Leb binding to trigger TFSS-dependent host cell signaling to induce the transcription of genes that enhance inflammation, development of intestinal metaplasia, and associated precancerous transformations. [ABSTRACT FROM AUTHOR]