CD4 T cell autophagy is integral to memory maintenance.

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Autophagy is vital for T cell homeostasis, but its role in mature T cells during immune responses is unclear.
• Previous models with T cell-specific autophagy deficiency since thymic development had limitations in studying mature T cell function.
• Understanding autophagy's role in T cell memory is critical for adaptive immunity.

Purpose of the Study:

• To investigate the specific role of autophagy in mature T cells, particularly CD8+ and CD4+ T cells, during immune responses and memory formation.
• To characterize the functional and survival defects of autophagy-deficient memory CD4+ T cells.
• To elucidate the mechanisms by which autophagy supports memory CD4+ T cell survival.

Main Methods:

• Generated conditional knockout mice (Atg5f/f dLck-cre) to delete autophagy specifically in mature T cells.
• Assessed CD8+ and CD4+ T cell survival, proliferation, and function in vivo and in vitro.
• Analyzed humoral immune responses, including antibody production and memory transfer.
• Differentiated memory CD4+ T cells in vitro to examine cellular defects.

Main Results:

• Autophagy deficiency impaired CD8+ T cell survival but not CD4+ T cell number or short-term activation.
• Autophagy was dispensable for early humoral response but critical for long-term antibody production and memory transfer.
• Autophagy-deficient memory CD4+ T cells exhibited mitochondrial and lipid load defects, leading to compromised survival without affecting energy production.

Conclusions:

• Autophagy is essential for mature CD8+ T cell survival and the development of robust, long-term humoral immunity.
• Memory CD4+ T cells depend on autophagy to maintain survival by managing mitochondrial activity and lipid accumulation.
• Targeting autophagy may offer therapeutic strategies for enhancing T cell memory and adaptive immunity.