Dissertation

Optical Control of CD8+ T Cell Mitochondrial Metabolism

Amitrano, Andrea M

2021

Overview

Despite all the progress that has been made in cancer therapies, cancer continues to be one of the leading causes of death. While immunotherapy has emerged as an extremely effective treatment option for hematologic malignancies, it is largely ineffective against solid tumors due in part to significant metabolic challenges present in the tumor microenvironment (TME). Tumor infiltrated CD8+ T cells face fierce competition with cancer cells for limited nutrients. The strong metabolic suppression in the TME often leads to impaired T cell recruitment to the tumor site and hypo-responsive effector functions via T cell exhaustion. Growing evidence suggests that mitochondria play a key role in CD8+ T cell activation, effector functions, and persistence in tumors. In this thesis, we show that overall mitochondrial functions, including mitochondrial mass and membrane potential, are increased during both mouse and human CD8+ T cell activation. CD8+ T cell mitochondrial membrane potential is closely correlated with production of Granzyme B and IFN-, demonstrating the significance of mitochondria in T cell effector functions. Additionally, migrating CD8+ T cells consumed significantly more oxygen than stationary CD8+ T cells, indicating the importance of mitochondrial metabolism in CD8+ T cell migration. Remote optical stimulation of CD8+ T cells that express our newly developed “OptoMito-On” can successfully enhance mitochondrial ATP production and improve overall CD8+ T cell migration, as well as Granzyme B production. OptoMito-On could hypothetically improve the function of effector CD8+ T cells in the TME. In addition to the OptoMito-On construct, we have also developed another optogenetic tool, “OptoMito-Off,” which decreases the mitochondrial membrane potential upon light activation. The goal for the application of OptoMito-Off in CD8+ T cells is to decrease over-activation of mitochondrial function, which could prevent T cell exhaustion while also promoting T cell persistence. Our studies provide new insight into the impact of the mitochondrial membrane potential on CD8+ T cell effector functions and demonstrates the development of a novel optogenetic technique to remotely control T cell metabolism with outstanding specificity and temporospatial resolution, which could improve the success of adoptive T cell immunotherapies.

• Publisher: ProQuest Dissertations & Theses
• Subject: Cellular biology / Immunology
• ISBN: 9798759999102