Innate immune activation and modulatory factors of Helicobacter pylori towards phagocytic and nonphagocytic cells.

Helicobacter pylori is an intriguing obligate host-associated human pathogen with a specific host interaction biology, which has been shaped by thousands of years of host-pathogen coevolution. Molecular mechanisms of interaction of H. pylori with the local immune cells in the human system are less well defined than epithelial cell interactions, although various myeloid cells, including neutrophils and other phagocytes, are locally present or attracted to the sites of infection and interact with H. pylori. We have recently addressed the question of novel bacterial innate immune stimuli, including bacterial cell envelope metabolites, that can activate and modulate cell responses via the H. pylori Cag type IV secretion system. This review article gives an overview of what is currently known about the interaction modes and mechanisms of H. pylori with diverse human cell types, with a focus on bacterial metabolites and cells of the myeloid lineage including phagocytic and antigen-presenting cells. • H. pylori is a master influencer of the cell-autonomous immune response. • The H. pylori Cag type 4 secretion system injects proteins and metabolites. • Bacterial heptose metabolites act as pattern recognition receptor ligands in epithelial and myeloid cells. • Bacterial heptose metabolites contribute to procancerogenic signaling. • Macrophages and neutrophils react very sensitively to heptose metabolites. [ABSTRACT FROM AUTHOR]