IRF5 Is Required for Bacterial Clearance in Human M1-Polarized Macrophages, and IRF5 Immune-Mediated Disease Risk...

Area of Science:

• Immunology
• Genetics
• Microbiology

Background:

• Common Interferon regulatory factor 5 (IRF5) variants are linked to immune-mediated diseases.
• IRF5 influences pattern recognition receptor (PRR)-induced cytokine production in macrophages.
• The role of IRF5 in macrophage-mediated bacterial clearance is not well understood.

Purpose of the Study:

• To investigate the role of IRF5 in macrophage bacterial clearance.
• To determine if low IRF5 expression, associated with protection from immune-mediated diseases, impairs bacterial clearance.
• To elucidate the mechanisms by which IRF5 regulates bacterial clearance.

Main Methods:

• Utilized M1-differentiated human macrophages.
• Assessed bacterial clearance in IRF5-deficient and wild-type macrophages.
• Analyzed the induction of reactive oxygen species (ROS), nitric oxide synthase 2 (NOS2), and autophagy.
• Investigated the role of IRF5-dependent signaling pathways (MAPK, NF-κB, Akt2).
• Compared bacterial clearance and pathway induction in macrophages with different IRF5 genetic variants (rs2004640/rs2280714 TT/TT vs. GG/CC).

Main Results:

• IRF5 is essential for optimal bacterial clearance in PRR-stimulated M1 macrophages.
• IRF5 induces ROS (via p40phox, p47phox, p67phox), NOS2, and autophagy (via ATG5).
• IRF5-deficient macrophages exhibit reduced bacterial clearance, which can be restored by complementing these pathways.
• IRF5-dependent MAPK, NF-κB, and Akt2 pathways are required for antimicrobial functions.
• Macrophages with low IRF5 expression (GG/CC variant carriers) show diminished ROS, NOS2, and autophagy induction, leading to reduced bacterial clearance compared to high IRF5 expressers (TT/TT variant carriers).

Conclusions:

• IRF5 plays a critical role in macrophage-mediated bacterial clearance through ROS, NOS2, and autophagy induction.
• Common IRF5 genetic variants modulate bacterial clearance capacity.
• Individuals carrying immune-mediated disease-associated IRF5 variants with lower expression may have impaired bacterial clearance, potentially influencing susceptibility to microbial-associated diseases.