Irf5 Knockdown in Bone Marrow-Derived Macrophages Favors M1-to-M2 Transition

Area of Science:

• Immunology
• Cell Biology

Background:

• Macrophages are key immune cells with distinct polarization states (M1 and M2).
• The transcription factor Interferon Regulatory Factor 5 (IRF5) is known to maintain the pro-inflammatory M1 macrophage state.

Purpose of the Study:

• To investigate the role of IRF5 in macrophage polarization.
• To assess the effects of IRF5 knockdown on M0, M1, and M2 murine bone marrow-derived macrophages (BMDM).

Main Methods:

• siRNA-mediated knockdown of Irf5 in BMDM.
• Phenotypic analysis of macrophage states.
• Measurement of M1 (iNOS) and M2 (CD206) marker expression.
• Assessment of mitochondrial content and morphology.
• Atomic Force Microscopy (AFM) for plasma membrane roughness and stiffness measurements.

Main Results:

• IRF5 knockdown in M1 macrophages induced an M2-like phenotype, characterized by decreased iNOS and increased CD206 expression.
• IRF5 reduction also affected the M2 macrophage phenotype.
• IRF5 knockdown increased plasma membrane roughness and altered macrophage elasticity, particularly in M2 cells.
• IRF5 plays a complex role in regulating macrophage polarization and associated functional properties.

Conclusions:

• IRF5 has a dual role in macrophage polarization, acting as both a transcriptional activator and repressor.
• IRF5 is essential for maintaining the metabolic and functional characteristics of macrophages in both M1 and M2 states.