Half the world's population carries a bacterium in their stomach that most people never know is there — yet it remains the leading infectious cause of gastric cancer. Understanding precisely how the immune system fails to clear Helicobacter pylori, and what cellular actors might be recruited to change that outcome, has become one of the more urgent questions in gastroenterology and cancer prevention.
This review in Frontiers in Immunology synthesizes current evidence on how the gastric mucosal immune system responds to H. pylori infection, with a notably specific focus on mucosa-associated invariant T (MAIT) cells — an innate-like T-cell population that has received comparatively little attention in the H. pylori literature. The authors detail how H. pylori circumvents host immunity through multiple mechanisms: the CagA oncoprotein disrupts epithelial junction integrity and hijacks intracellular signaling, while bacterial modulation of heat shock proteins dampens effective immune clearance. The result is a paradox in which robust inflammatory responses — featuring neutrophil and macrophage recruitment, plus elevated IL-8, TNF-α, and IL-17 — coexist with persistent bacterial colonization. The review also surveys therapeutic strategies that exploit mucosal immunity, spanning vaccine candidates to immunomodulatory approaches targeting downstream sequelae including MALT lymphoma and gastric adenocarcinoma.
The MAIT cell angle is the most analytically interesting contribution here. MAIT cells, which recognize bacterially derived riboflavin metabolites via the MR1 molecule, are abundant in gut mucosa and have demonstrated roles in antimicrobial surveillance in other contexts — but their specific functional dynamics in the H. pylori-infected stomach have been undercharacterized. Elevating them as orchestrators of host defense is a testable hypothesis with therapeutic implications. That said, as a narrative review rather than a meta-analysis or clinical trial, the causal weight of any individual claim remains limited. The practical significance lies in consolidating a mechanistic framework that could guide future vaccine or immunotherapy design targeting a pathogen responsible for roughly 89% of non-cardia gastric cancers globally. Incremental but directionally important.