Targeting Autophagy with Carbon-monoxide Reprograms Anti-Tumor T Cells with Robust Immunometabolic Phenotype

Abstract

Abstract Mitochondria and Endoplasmic reticulum (ER) share structural and functional networks and activates well-orchestrated signaling processes to shape a cell’s fate and function. While persistent ER stress (ERS) response leads to mitochondrial collapse, moderate ERS condition promotes mitochondrial function. Strategies to boost anti-tumor T cell function by targeting ER-Mitochondria cross talk have not been exploited yet. Thus, we used carbon monoxide (CO), a short-lived gaseous molecule, to test if engaging moderate ERS conditions can improve T cells mitochondrial function and anti-tumor function. Using melanoma antigen specific T cells, we identify that CO induced transient activation of ERS sensor ‘protein kinase R-like endoplasmic reticulum kinase (PERK)’ dramatically increase anti-tumor T cell function. Furthermore, CO-induced PERK activation temporarily halts protein translation and induces protective autophagy (that includes mitophagy). To get further insight, we used LC3-GFP to differentiate between the cells that prepare themselves to undergo active autophagy (LC3-GFPpos) and those that fail to enter into the process (LC3-GFPneg). We found that LC3-GFPpos T cells show robust anti-tumor potential whereas, LC3-GFPneg cells show T regulatory-like phenotype, harbor dysfunctional mitochondria, and accumulate abnormal metabolite content. These anomalous ratios of metabolites render the cells with a hypermethylated state and distinct epigenetic profile limiting their anti-tumor activity. Overall, the study highlights that ERS activated autophagy pathways modify mitochondrial function and epigenetically reprogram the T cells towards a superior anti-tumor phenotype to achieve robust tumor control.