Cloning and characterization of a novel membrane-associated antigenic protein of Helicobacter pylori
M Yoshida1, Y Wakatsuki, Y Kobayashi
1Divisions of Clinical Bio-Regulatory Science, Graduate School of Medicine, Kyoto University, Japan.
Abstract:
Infection by Helicobacter pylori, a noninvasive bacterium, induces chronic leukocyte infiltration in the stomach by still largely unknown molecular mechanisms. We investigated the possibility that a membrane protein of H. pylori induces an inflammatory reaction in the subepithelial tissue of the stomach. By generating an expression library of H. pylori chromosomal DNA and screening with rabbit antiserum raised to a membrane fraction of H. pylori and sera of infected patients, we cloned a 16.0-kDa protein (HP-MP1) which appeared to attach to the inner membrane of the H. pylori in a homodimeric form. Anti-HP-MP1 antibodies were detected in the sera of infected patients but not in those of uninfected controls. Coincubation of monocytes with recombinant HP-MP1 led to cell activation and production of interleukin-1alpha (IL-1alpha), tumor necrosis factor alpha, IL-8, and macrophage inflammatory protein 1alpha. The results indicate that HP-MP1 is an antigenic membrane-associated protein of H. pylori which potentially activates monocytes. This suggests that HP-MP1 may play roles in the pathogenesis of perpetual tissue inflammation associated with H. pylori infection.
Insights
Helicobacter pylori infection causes stomach inflammation via a novel membrane protein, HP-MP1. This protein activates immune cells, suggesting its role in chronic inflammation pathogenesis.
Area of Science:
- Microbiology
- Immunology
- Gastroenterology
Background:
- Helicobacter pylori infection leads to chronic stomach inflammation through poorly understood mechanisms.
- Investigating the role of bacterial membrane proteins in initiating inflammatory responses.
Purpose of the Study:
- To identify and characterize a potential H. pylori membrane protein involved in inducing subepithelial inflammatory reactions in the stomach.
Main Methods:
- Generated an H. pylori expression library and screened using specific antisera.
- Cloned and identified a 16.0-kDa membrane protein, designated HP-MP1.
- Detected anti-HP-MP1 antibodies in infected patients' sera.
- Assessed monocyte activation and cytokine production upon exposure to recombinant HP-MP1.
Main Results:
- Identified HP-MP1, an antigenic, membrane-associated H. pylori protein.
- Confirmed the presence of anti-HP-MP1 antibodies in infected individuals.
- Demonstrated that HP-MP1 activates monocytes, inducing the release of key inflammatory cytokines (IL-1α, TNF-α, IL-8, MIP-1α).
Conclusions:
- HP-MP1 is a significant antigenic component of H. pylori.
- HP-MP1 has the potential to activate monocytes, contributing to the inflammatory cascade.
- HP-MP1 may play a crucial role in the pathogenesis of persistent inflammation during H. pylori infection.
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