The G2A Receptor Controls Polarization of Macrophage by Determining Their Localization Within the Inflamed Tissue.

Area of Science:

• Immunology
• Cell Biology
• G-protein coupled receptors

Background:

• Macrophages are key immune cells with versatile M1 (pro-inflammatory) and M2 (anti-inflammatory) phenotypes.
• The G-protein coupled receptor G2A (GPR132) role in macrophage migration and polarization remains incompletely understood.
• Acute inflammation models are essential for studying immune cell dynamics and therapeutic targets.

Purpose of the Study:

• To investigate the function of G-protein coupled receptor G2A (GPR132) in macrophage chemotactic migration and polarization during acute inflammation.
• To elucidate the role of G2A in modulating the inflammatory microenvironment and macrophage phenotype.
• To assess the impact of G2A deficiency on pain perception and immune cell infiltration in an acute inflammation model.

Main Methods:

• Utilized a zymosan-induced acute inflammation model in G2A-deficient mice.
• Quantified macrophage phenotypes (M1-like and M2-like) in inflamed tissues.
• Assessed neutrophil accumulation, efferocytosis, and lipid mediator levels.
• Evaluated thermal hyperalgesia and macrophage localization relative to inflammatory foci.

Main Results:

• G2A-deficient mice exhibited reduced zymosan-induced thermal hyperalgesia, which was dependent on macrophages.
• A decrease in M1-like macrophages was observed in the inflamed tissue of G2A-deficient mice.
• While monocyte numbers were unchanged, macrophages were less localized to the zymosan-rich inflammatory center in G2A-deficient mice, with impaired neutrophil efferocytosis.
• Increased levels of neutrophil-derived lipids that promote G2A-mediated chemotaxis were found in G2A-deficient inflamed tissues.

Conclusions:

• G-protein coupled receptor G2A (GPR132) is essential for directing macrophages to the pro-inflammatory core of acute inflammation.
• Absence of G2A leads to macrophage mislocalization to anti-inflammatory areas and a shift towards M2-like polarization.
• G2A plays a critical role in integrating inflammatory signals for proper macrophage positioning and function during acute inflammation.