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Helicobacter pylori stimulates inducible nitric oxide synthase expression and activity in a murine macrophage cell

K T Wilson1, K S Ramanujam, H L Mobley

  • 1Department of Medicine, University of Maryland School of Medicine, Baltimore, USA. kwilson@umabnet.ab.umd.edu

Gastroenterology
|December 1, 1996
PubMed
Abstract

Insights

Helicobacter pylori infection activates inducible nitric oxide synthase (iNOS) in macrophages. This immune response, driven by bacterial products, contributes to gastric inflammation and tissue injury in H. pylori-associated disease.

Area of Science:

  • Immunology
  • Microbiology
  • Gastroenterology

Background:

  • Helicobacter pylori infection causes gastric inflammation.
  • Inducible nitric oxide synthase (iNOS) produces high levels of nitric oxide (NO), linked to immune activation and tissue damage.
  • Macrophages are key inflammatory cells in H. pylori infection.

Purpose of the Study:

  • To investigate the capacity of H. pylori to induce iNOS expression in macrophages.
  • To understand the role of iNOS in H. pylori-induced gastric mucosal inflammation.

Main Methods:

  • RAW 264.7 murine macrophages were exposed to H. pylori preparations.
  • iNOS expression was measured using Northern blot analysis, enzyme activity assays, and nitrite (NO2-) release.
  • Lipopolysaccharide (LPS) involvement was assessed using polymyxin B.

Main Results:

  • H. pylori induced concentration-dependent NO2- production and increased iNOS messenger RNA and enzyme activity.
  • iNOS expression was synergistically enhanced by interferon gamma.
  • H. pylori-induced iNOS expression involved both LPS-dependent and LPS-independent mechanisms.

Conclusions:

  • Stable H. pylori products activate iNOS expression in macrophages.
  • iNOS activation by H. pylori may significantly contribute to the pathogenesis of H. pylori-associated gastric mucosal disease.

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