Oxidized Lipids and CD36-Mediated Lipid Peroxidation in CD8 T Cells Suppress Anti-Tumor Immune Responses

T cell metabolic fitness plays a pivotal role in anti-tumor immunity and metabolic deregulation causes T cell dysfunction in cancer. We identify that CD36 limits anti-tumor CD8+ T cell effector functions through lipid peroxidation. In murine tumors, oxidized phospholipids (OxPLs) were highly abundant and CD8+ TILs increased uptake and accumulation of lipids and lipid peroxidation. Functionally 'exhausted' CD8+ TILs increased CD36 expression and CD36-deficient CD8+ TILs had more robust anti-tumor activity and cytokine production than wild-type cells. We further show that CD36 promotes uptake of oxidized low-density lipoproteins (OxLDL), induces lipid peroxidation in CD8+ TILs, and enhances p38 kinase phosphorylation. Moreover, we found that OxLDL inhibits CD8+ T cell functions in a CD36/p38-dependent manner. Furthermore, glutathione peroxidase 4 (GPX4) over-expression lowers lipid peroxidation and restores functionalities in CD8+ TILs. These results define a key role for an oxidized lipid-CD36-p38 axis in promoting intratumoral CD8+ T cell dysfunction. Overall design: Single cell RNA sequencing was performed on Cd36+/+ WT or Cd36-/- KO T cells (CD4+ T cells, CD8+ T cells ) FACS-sorted from B16 tumors (21 days post implantation).