Colitis susceptibility in mice with reactive oxygen species deficiency is mediated by mucus barrier and immune...

Area of Science:

• Immunology
• Gastroenterology
• Genetics

Background:

• Reactive oxygen species (ROS), produced by NADPH oxidases (NOX/DUOX), are crucial for antimicrobial defense, redox signaling, and maintaining gut barrier integrity.
• Inactivating mutations in NOX variants are linked to intestinal inflammation in chronic granulomatous disease (CGD; NOX2) and pediatric inflammatory bowel disease (IBD; NOX1).

Purpose of the Study:

• To investigate if a patient-relevant hypomorphic mutation in Cyba (p22^phox) increases susceptibility to intestinal inflammation in a mouse model.
• To understand the role of reduced intestinal ROS in the pathogenesis of gut inflammation.

Main Methods:

• Generation of Cyba (p22^phox) mutant mice with low intestinal ROS production, while preserving Nox4 function.
• Assessment of mucus layer integrity, bacterial translocation, gut microbiota composition (dysbiosis), and innate immune responses in mutant mice.
• Evaluation of therapeutic interventions including bone marrow transplantation and oral antibiotic treatment.

Main Results:

• Cyba mutant mice exhibited significantly disrupted mucus layers with bacterial penetration into intestinal crypts.
• These mice developed gut dysbiosis and showed a compromised innate immune response to microbial invasion, leading to mortality.
• Bone marrow transplantation and oral antibiotic treatment effectively ameliorated or prevented the disease phenotype.

Conclusions:

• The Cyba mutant mouse phenotype highlights the critical role of ROS in maintaining both the mucus barrier and effective innate immune defense in the gut.
• This study supports a combined-hit model where a single genetic variant compromises multiple cellular functions, leading to intestinal inflammation.
• The findings suggest potential therapeutic strategies for ROS-deficient intestinal inflammation, drawing parallels with treatments for CGD and IBD.