Mitochondrial complex II orchestrates divergent effects in CD4+ and CD8+ T cells

Area of Science:

• Immunology
• Cellular Metabolism
• Mitochondrial Biology

Background:

• T cell functions are regulated by mitochondrial metabolism.
• The specific roles of mitochondrial components in distinct T cell subsets are not well understood.
• Mitochondrial Complex II (MC II) is crucial for both electron transport chain (ETC) and cellular metabolism.

Purpose of the Study:

• To investigate the role of MC II in regulating CD4+ and CD8+ T cell activation and function.
• To elucidate the divergent effects of MC II on different T cell subsets.

Main Methods:

• Utilized T cell-specific MC II subunit, succinate dehydrogenase A-deficient (SDHA-deficient) mice.
• Integrated single-cell RNA-seq and metabolic profiling.
• Performed in vitro and in vivo T cell functional assays.

Main Results:

• SDHA deficiency induced metabolic and gene expression changes exclusively in activated T cells.
• In CD4+ T cells, SDHA loss impaired oxidative phosphorylation (OXPHOS), glycolysis, cytokine production, proliferation, and graft-versus-host disease.
• In CD8+ T cells, SDHA deficiency reduced OXPHOS, upregulated glycolysis, and enhanced cytotoxic functions, leading to superior anti-tumor efficacy.

Conclusions:

• MC II plays a divergent role in CD4+ and CD8+ T cell function.
• MC II acts as a bifurcation point for metabolic and functional specialization in T cells.
• Targeting MC II could enhance anti-tumor immunity mediated by CD8+ T cells.