Life in the human stomach: persistence strategies of the bacterial pathogen Helicobacter pylori

Abstract

The bacterial pathogen Helicobacter pylori has co-evolved with humans and colonizes roughly one half of the human population, but only causes overt gastric disease in a subset of infected hosts. In this Review, we discuss the pathogenesis of this bacterium and the mechanisms it uses to promote persistent colonization of the gastric mucosa, with a focus on recent insights into the role of the virulence factors VacA, CagA and CagL. We also describe the immunobiology of H. pylori infection and highlight how this bacterium manipulates the innate and adaptive immune systems of the host to promote its own persistence.

Cytokine BAFF Released byHelicobacter pylori–Infected Macrophages Triggers the Th17 Response in Human Chronic Gastritis

“…Because LPS is capable of inducing BAFF expression in APCs (26), we addressed the role of the endotoxin in the induction of BAFF by H. pylori. The receptor involved in the detection of H. pylori LPS remains a matter of debate: indeed, although several studies have implicated the classical LPS sensor TLR4, others support the idea that TLR2 is the main receptor of H. pylori LPS (27). Therefore, we evaluated the release of BAFF by macrophages exposed to H. pylori in the presence of either a TLR2 or a TLR4 blocking Ab.…”

Worldwide Population Structure, Long-Term Demography, and Local Adaptation of Helicobacter pylori

“…The long, intimate association of H. pylori with humans suggests a history of bacterial adaptation. Considerable attention has focused on specific genes involved in modulating adaptive immunity of the host (for a review see Yamaoka 2010 andSalama et al 2013) and on genomic changes occurring during acute and chronic H. pylori infection (Kennemann et al 2011;Linz et al 2014) as well as during H. pylori transmission between human hosts (Linz et al 2013). However, bacterial genome adaptation has not been investigated at the global level.…”

“…It was first described in the 1980s, when it was initially identified in association with chronic gastritis and later causally linked to serious gastric pathologies such as gastric cancer and ulcers (Marshall and Warren 1984;Suerbaum and Michetti 2002). It infects .80% of humans in developing countries and, although its prevalence is lower in developed countries, nearly 50% of the worldwide human population is infected (Ghose et al 2005;Salih 2009;Salama et al 2013).Due to its clinical and evolutionary importance, there has been considerable research on mechanisms of H. pylori transmission, as well as on the population genetics and phylogenetic relationships among global isolates. Thus far, population genetic analyses have mainly focused on seven housekeeping genes (usually referred to as multilocus sequence typing or MLST), with the primary conclusions being that H. pylori strains appear highly structured, and their phylogeographic patterns correlate consistently with that of their human hosts.…”

“…It was first described in the 1980s, when it was initially identified in association with chronic gastritis and later causally linked to serious gastric pathologies such as gastric cancer and ulcers (Marshall and Warren 1984;Suerbaum and Michetti 2002). It infects .80% of humans in developing countries and, although its prevalence is lower in developed countries, nearly 50% of the worldwide human population is infected (Ghose et al 2005;Salih 2009;Salama et al 2013).…”

Antimicrobial and anti-inflammatory activities of Apis mellifera honey on the Helicobacter pylori infection of Wistar rats gastric mucosa

“…The bacterium called Helicobacter pylori is a Gram-negative spirillum which colonizes the upper gastrointestinal tractspecifically the stomach, of approximately 50% of the world's population (Salama et al, 2013). Infection with H. pylori causes chronic inflammation and significantly increases the risk of developing duodenal and gastric ulcers, being the strongest known factor to initiate gastric cancer, which is the second type of cancer that kills more worldwide (Wroblewski et al, 2010;Graham, 2015).…”