Autophagy proteins stabilize pathogen-containing phagosomes for prolonged MHC II antigen processing.

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Antigen presentation by antigen-presenting cells is vital for adaptive immunity.
• Macrophages and dendritic cells are key antigen-presenting cells.
• The mechanisms for prolonged antigen preservation are not fully understood.

Purpose of the Study:

• To investigate the role of macroautophagy in antigen preservation for prolonged presentation.
• To identify the molecular components and signaling pathways involved in antigen storage phagosomes.

Main Methods:

• Analysis of human macrophages and dendritic cells.
• Immunofluorescence staining for Atg8/LC3.
• Investigation of Toll-like receptor 2 (TLR2) agonists.
• Assessment of reactive oxygen species (ROS) production by NOX2.

Main Results:

• A subset of phagosomes in human macrophages and dendritic cells is coated with Atg8/LC3.
• These Atg8/LC3-positive phagosomes maintain phagocytosed antigens for extended presentation on MHC class II molecules.
• Formation of these phagosomes requires TLR2 agonists and NOX2-dependent ROS production.
• Deficiency in NOX2-dependent phagosome formation may impair antifungal immunity.

Conclusions:

• Atg8/LC3-coated phagosomes represent a mechanism for prolonged antigen storage and presentation.
• NOX2-derived ROS are essential for the formation of these antigen-retaining phagosomes.
• Impaired formation of these phagosomes could underlie immune deficiencies like chronic granulomatous disease.