Notch Signaling Ligand Jagged1 Enhances Macrophage-Mediated Response to Helicobacter pylori

Area of Science:

• Immunology
• Microbiology
• Cell Biology

Background:

• Helicobacter pylori (H. pylori) infection causes significant gastrointestinal diseases.
• Macrophages are crucial for clearing H. pylori, and Notch signaling influences macrophage function.
• The specific role of Notch signaling in macrophage response to H. pylori is not well understood.

Purpose of the Study:

• To investigate the role of Notch signaling in macrophage-mediated H. pylori eradication.
• To identify specific components of the Notch pathway involved in this interaction.
• To explore Jagged1 as a potential therapeutic target.

Main Methods:

• Co-culture model of macrophages and H. pylori.
• Inhibition of Notch signaling using γ-secretase inhibitor.
• Analysis of inducible nitric oxide synthase (iNOS), nitric oxide (NO), and pro-inflammatory cytokines.
• Assessment of macrophage phagocytosis and bactericidal activity.
• Investigation of Jagged1 expression and function using overexpression and siRNA knockdown.
• Analysis of clinical specimens from H. pylori-infected patients.

Main Results:

• Inhibition of Notch signaling impaired macrophage bactericidal activity against H. pylori, reducing iNOS, NO, and pro-inflammatory cytokine secretion.
• H. pylori infection upregulated Jagged1 expression in macrophages.
• Jagged1 overexpression enhanced macrophage bactericidal activity, while Jagged1 knockdown impaired it.
• Increased Jagged1+ macrophages were observed in H. pylori-infected gastric mucosa.
• Exogenous Jagged1 promoted anti-H. pylori responses, while neutralizing antibodies attenuated them.

Conclusions:

• Jagged1 is a key molecule that promotes macrophage-mediated clearance of H. pylori.
• The Jagged1-Notch signaling pathway plays a critical role in the host's immune response to H. pylori.
• Jagged1 represents a promising therapeutic target for controlling H. pylori infections.