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Role of lipopolysaccharide and related cytokines in Helicobacter pylori infection
1Dipartimento di Clinica Medica, Immunologia e Malattie Infettive, Università, Bari.
Abstract:
Helicobacter pylori is a gram-negative bacterium which accounts for the development of chronic gastritis and peptic ulcer in man. In this review, emphasis has been laid on the role of lipopolysaccharide (LPS) of the H. pylori cellular wall in the pathogenesis of gastroduodenal disease. H. pylori LPS exhibits a reduced endotoxic potency in terms of pyrogenicity, lethality, toxicity, mitogenicity, cytokine (CK) release and chromogenic limulus amebocyte lysate assay. This low biological activity of the LPS could be ascribed to the underacylation and underphosphorylation pattern of the lipid A backbone. However, also LPS core structures seem to contribute to the biological activity of the molecule. Despite this low immunological potential, an array of proinflammatory CKs are produced both in vitro and in vivo following stimulation of mucosal cells with H. pylori organisms. It is likely that LPS plays a major role in triggering interleukin (IL)-8, IL-1 and tumor necrosis factor-alpha production from both epithelial cells and macrophages. Finally, the lower immune response elicited by H. pylori LPS in comparison with other enterobacterial LPS may represent an escape mechanism from the host immunosurveillance exerted by this bacterium, thus allowing its survival and persistence in the gastric niche.
Insights
Helicobacter pylori lipopolysaccharide (LPS) has low endotoxic activity, contributing to chronic gastritis and peptic ulcers. This reduced immune response may allow H. pylori persistence in the stomach.
Area of Science:
- Microbiology
- Immunology
- Gastroenterology
Background:
- Helicobacter pylori is a gram-negative bacterium linked to chronic gastritis and peptic ulcers.
- Lipopolysaccharide (LPS) in the H. pylori cell wall plays a role in disease development.
- H. pylori LPS shows reduced endotoxic potency compared to other enterobacterial LPS.
Purpose of the Study:
- To review the role of H. pylori LPS in gastroduodenal disease pathogenesis.
- To investigate the structural basis for H. pylori LPS's low biological activity.
- To understand how H. pylori LPS influences host immune responses.
Main Methods:
- Review of existing literature on H. pylori LPS structure and function.
- Analysis of studies on H. pylori LPS endotoxicity (pyrogenicity, lethality, cytokine release).
- Comparison of H. pylori LPS immunological potential with other bacterial LPS.
Main Results:
- H. pylori LPS exhibits significantly lower pyrogenicity, lethality, toxicity, mitogenicity, and cytokine release.
- Underacylation and underphosphorylation of the lipid A backbone contribute to reduced LPS activity.
- Despite low endotoxicity, H. pylori LPS can stimulate proinflammatory cytokine production (IL-8, IL-1, TNF-alpha).
Conclusions:
- The low endotoxic potential of H. pylori LPS is linked to its unique lipid A and core structures.
- H. pylori LPS contributes to gastroduodenal disease pathogenesis by modulating host immune responses.
- Reduced immune recognition of H. pylori LPS may facilitate bacterial survival and persistence in the gastric niche.