ATGs help MHC class II, but inhibit MHC class I antigen presentation

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Macroautophagy, a cellular degradation process, utilizes the LC3/Atg8 machinery.
• This machinery has been implicated in the regulation of cell surface molecules.

Purpose of the Study:

• To investigate the role of macroautophagy in MHC class I and MHC class II antigen presentation.
• To elucidate how autophagic pathways impact immune responses during viral infections.

Main Methods:

• Investigated the internalization of MHC class I molecules in the presence and absence of key autophagy genes (ATG5, ATG7).
• Analyzed the surface expression of MHC class I on dendritic cells and macrophages.
• Assessed CD8(+) T cell responses and immune control in viral infection models.

Main Results:

• Absence of ATG5 or ATG7 impaired MHC class I internalization, leading to surface stabilization.
• Stabilized MHC class I enhanced CD8(+) T cell responses and improved immune control during viral infections.
• Autophagic machinery was found to support MHC class II presentation while hindering MHC class I presentation.

Conclusions:

• The LC3/Atg8 lipidation machinery of macroautophagy plays a dual role in antigen presentation.
• Autophagy enhances MHC class II presentation but compromises MHC class I presentation through internalization and degradation.
• Targeting autophagy could be a strategy to modulate adaptive immune responses.