Memory CD8(+) T cells use cell-intrinsic lipolysis to support the metabolic programming necessary for development

Area of Science:

• Immunology
• Cellular Metabolism
• Molecular Biology

Background:

• CD8(+) memory T cell generation depends on metabolic reprogramming, specifically enhanced mitochondrial fatty-acid oxidation (FAO).
• The source of fatty acids (FA) fueling FAO in memory T cells is not fully understood.
• Memory T cells exhibit higher FAO rates compared to effector T cells, but internalize fewer external long-chain FA.

Purpose of the Study:

• To elucidate the source of fatty acids utilized by CD8(+) memory T cells for FAO.
• To investigate the metabolic pathways supporting oxidative phosphorylation (OXPHOS) in memory T cells.
• To determine the role of lysosomal acid lipase (LAL) in memory T cell development and metabolism.

Main Methods:

• Comparative analysis of fatty acid uptake in CD8(+) memory T cells versus effector T (Teff) cells.
• Metabolic flux analysis to assess fatty acid oxidation and oxidative phosphorylation.
• Investigation of cell-intrinsic lysosomal acid lipase (LAL) expression and function in T cells.

Main Results:

• CD8(+) memory T cells internalize significantly fewer extracellular long-chain FA compared to Teff cells.
• Memory T cells utilize extracellular glucose to support FAO and OXPHOS, indicating de novo lipid synthesis.
• Cell-intrinsic expression of lysosomal acid lipase (LAL) is essential for mobilizing FA for FAO and memory T cell development.

Conclusions:

• Memory T cells rely on intracellularly synthesized lipids, not direct uptake of extracellular FA, to fuel FAO.
• Lysosomal acid lipase (LAL) plays a critical cell-intrinsic role in lipid metabolism for memory T cell fate.
• This study links LAL to lymphocyte metabolic reprogramming and highlights cell-intrinsic lipolysis as a determinant of memory T cell development.