The epigenetic role of vitamin C in lung-resident memory CD8 T cell differentiation and function - PROJECT SUMMARY/ABSTRACT Vitamin C (VC) insufficiency is surprisingly common, affecting approximately 42% of people (about 139 million individuals) in the United States, and it is likely a hidden factor contributing to lung disease. Previous clinical trials have linked VC deficiency to increased severity of respiratory disease and pneumonia. However, the exact molecular mechanism behind VC's role in the lung remains incompletely known. Understanding the impact of VC deficiency is critical for mitigating respiratory disease severity; further, revealing the molecular mechanism behind VC’s function may lead to identification of novel therapeutic targets in the lung. Previous work from our lab and others showed that VC levels can alter cell fate decisions by functioning as a cofactor for the Ten-Eleven Translocation (TET) family, enzymes responsible for DNA demethylation. We previously demonstrated that VC promotes B cell differentiation by increasing the expression of transcription factor BLIMP1 through TET-mediated enhancer demethylation. In T cells, BLIMP1 is required to establish lung- specific tissue resident memory CD8 cytotoxic T cells (CD8 TRM) essential for immunity against respiratory pathogens, including influenza A virus. Thus, we hypothesize that VC is required for the differentiation and homeostasis of lung TRM by promoting TET-dependent BLIMP1 expression. We will restrict VC deficiency or TET deficiency to CD8 T cells and assess their ability to differentiate into CD8 TRM and to provide lung immune protection against influenza rechallenge. We will profile DNA methylation patterns to define TET activity involved in establishment of lung CD8 TRM. Further, we will determine if VC and TET regulate BLIMP1 expression and if BLIMP1 expression can rescue TRM phenotypes observed in the VC- or TET-deficient CD8 T cells. The completion of this proposal may reveal factors that help mitigate lung damage associated with severe respiratory diseases. It may also identify specific genes and DNA elements that can be targeted to potentiate lung CD8 TRM responses for vaccine design. These research goals will be accomplished by the applicant, Ms. Bella Lee, in the context of an individualized training plan developed by the applicant and her mentorship team. Specifically, her training plan places special emphasis on bridging lung physiology, epigenetics, and immunology; scientific communication with both peer and public audiences; and ethics training tailored to the era of artificial intelligence to form the foundation of her physician-scientist career. Taken together, the proposed work will 1) demonstrate one of the elusive cellular and molecular mechanisms of how VC mediates lung protection and 2) advance Ms. Lee’s scientific acumen, technical expertise, and professional network as she pursues an independent physician-scientist research career in barrier immunology.
