TRPV2 has a pivotal role in macrophage particle binding and phagocytosis

Area of Science:

• Immunology
• Cell Biology
• Ion Channel Physiology

Background:

• Macrophage phagocytosis is crucial for host defense against pathogens.
• Ionic flux plays a role in phagocytosis, but the specific ion channels involved are not well understood.

Purpose of the Study:

• To investigate the role of the cation channel TRPV2 in macrophage phagocytosis and innate immune responses.

Main Methods:

• Utilized macrophages deficient in TRPV2 to assess particle binding and phagocytosis mediated by zymosan, IgG, and complement.
• Examined TRPV2 recruitment to phagosomes and its effect on plasma membrane depolarization.
• Assessed the impact of TRPV2 deficiency on phosphatidylinositol-4,5-bisphosphate synthesis, actin depolymerization, and chemoattractant-elicited motility.
• Evaluated the in vivo consequences of TRPV2 deficiency in a mouse model challenged with Listeria monocytogenes.

Main Results:

• Macrophages lacking TRPV2 exhibited impaired zymosan-, IgG-, and complement-mediated phagocytosis.
• TRPV2 was recruited to nascent phagosomes and induced plasma membrane depolarization.
• Depolarization by TRPV2 enhanced phosphatidylinositol-4,5-bisphosphate synthesis, facilitating actin dynamics and receptor clustering.
• TRPV2-deficient macrophages showed reduced chemoattractant-induced motility.
• TRPV2-deficient mice displayed increased mortality and bacterial load upon Listeria monocytogenes infection.

Conclusions:

• TRPV2 is a critical cation channel involved in the early stages of macrophage phagocytosis.
• TRPV2 plays a fundamental role in innate immunity by facilitating phagocytosis and macrophage motility.
• TRPV2-mediated signaling is essential for effective host defense against bacterial pathogens.