Long-term antigen exposure irreversibly modifies metabolic requirements for T cell function

Area of Science:

• Immunology
• Cellular Metabolism
• T cell biology

Background:

• T cell energy metabolism is crucial for function.
• The impact of chronic antigenic stimulation on T cell metabolism remains unclear.

Purpose of the Study:

• To investigate the metabolic changes in T cells under long-term antigenic exposure.
• To determine the effect of PD-1 blockade on the metabolism and function of chronically stimulated T cells.

Main Methods:

• In vivo studies of T cells with persistent antigenic exposure.
• Analysis of T cell metabolic flux, respiratory capacity, and enzyme activity.
• Assessment of IFNγ production and cell viability following PD-1 blockade.

Main Results:

• Chronic antigenic exposure led to deficits in metabolic enzymes, reduced glycolytic flux, and limited respiratory capacity.
• PD-1 blockade in chronic T cells stimulated IFNγ production but did not induce aerobic glycolysis.
• Chronic T cells utilized oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) for ATP production; PD-1 blockade increased mitochondrial superoxide and decreased viability.

Conclusions:

• PD-1-mediated inhibition is vital for limiting oxidative metabolism in chronic T cells, supporting their survival and functional fitness.
• The absence of a glycolytic switch in chronic T cells highlights a distinct metabolic adaptation.
• Targeting PD-1 in chronic T cell states requires careful consideration of metabolic consequences and oxidative stress.