OXPHOS promotes apoptotic resistance and cellular persistence in T H 17 cells in the periphery and tumor microenvironment.

T cell proliferation and cytokine production are bioenergetically and biosynthetically costly. The inability to meet these metabolic demands results in altered differentiation, accompanied by impaired effector function, and attrition of the immune response. Interleukin-17-producing CD4 T cells (T17s) are mediators of host defense, autoimmunity, and antitumor immunity in the setting of adoptive T cell therapy. T17s are long-lived cells that require mitochondrial oxidative phosphorylation (OXPHOS) for effector function in vivo. Considering that T17s polarized under standardized culture conditions are predominately glycolytic, little is known about how OXPHOS regulates T17 processes, such as their ability to persist and thus contribute to protracted immune responses. Here, we modified standardized culture medium and identified a culture system that reliably induces OXPHOS dependence in T17s. We found that T17s cultured under OXPHOS conditions metabolically resembled their in vivo counterparts, whereas glycolytic cultures were dissimilar. OXPHOS T17s exhibited increased mitochondrial fitness, glutamine anaplerosis, and an antiapoptotic phenotype marked by high BCL-XL and low BIM. Limited mitophagy, mediated by mitochondrial fusion regulator OPA-1, was critical to apoptotic resistance in OXPHOS T17s. By contrast, glycolytic T17s exhibited more mitophagy and an imbalance in BCL-XL to BIM, thereby priming them for apoptosis. In addition, through adoptive transfer experiments, we demonstrated that OXPHOS protected T17s from apoptosis while enhancing their persistence in the periphery and tumor microenvironment in a murine model of melanoma. Together, our work demonstrates how metabolism regulates T17 cell fate and highlights the potential for therapies that target OXPHOS in T17-driven diseases.