Helicobacter pullorum induces nitric oxide release in murine macrophages that promotes phagocytosis and killing

Area of Science:

• Microbiology
• Immunology
• Cell Biology

Background:

• Helicobacter pullorum, an avian enterohepatic species, is increasingly identified in mammalian infections, including gastrointestinal and hepatobiliary diseases in humans.
• Murine macrophages play a crucial role in innate immunity against bacterial pathogens.

Purpose of the Study:

• To investigate the interaction between Helicobacter pullorum and murine macrophages.
• To determine the effect of nitric oxide on H. pullorum viability and morphology.
• To elucidate the host immune response triggered by H. pullorum infection in macrophages.

Main Methods:

• Colony-forming assays and light microscopy were used to assess the impact of nitric oxide on H. pullorum.
• Confocal microscopy was employed to visualize macrophage-pathogen interactions.
• Cytokine secretion (TNF-α, IL-1β, IL-6, MIP-2) was measured following co-culture.

Main Results:

• Nitric oxide exposure reduced H. pullorum viability in a growth-phase-dependent manner and decreased cell size.
• Murine macrophages internalized H. pullorum, leading to nitric oxide production, phagocytosis, and pathogen killing.
• H. pullorum infection stimulated the secretion of pro-inflammatory cytokines from macrophages.

Conclusions:

• Helicobacter pullorum can infect murine macrophages, initiating an innate immune response.
• Nitric oxide is a key mediator in the macrophage's defense against H. pullorum.
• The interaction highlights H. pullorum's potential to cause disease in mammalian hosts through immune modulation.