Immunometabolite L-2-Hydroxyglutarate in Natural Killer Cell Antiviral Immunity

Natural Killer (NK) cells are a major component of host immunity against viral infections, rapidly responding to infected cells by secreting cytokines and lytic granules. NK cells are particularly important for controlling infections by herpesviruses, such as cytomegalovirus, which can cause significant clinical consequences in immunocompromised patients and neonates. Using a well-established mouse cytomegalovirus (MCMV) infection model, our lab and others have demonstrated that NK cells undergo dynamic metabolic and epigenetic shifts during antiviral responses to fuel their activation and effector functions. However, the mechanisms by which NK cells coordinate these metabolic and epigenetic changes are not well understood. Growing evidence indicates that central metabolites play important roles in immune cell activation by acting not only as energy sources but also as substrates for growth signaling pathways, epigenetic regulation, and effector differentiation. L-2-hydroxyglutarate (L-2HG) is an immunometabolite that has been shown to play a role in coordinating metabolic and epigenetic shifts in activated CD8+ T cells, dendritic cells, and macrophages. During activation, L-2HG accumulates and acts as a potent competitive inhibitor of ⍺KG-dependent enzymes, including histone lysine demethylases and hypoxia inducible factor prolyl hydroxylases, altering the epigenetic and metabolic state of these cells. While L-2HG is clearly important for immune cell function, the role of L-2HG in NK cells is unknown. My preliminary data indicates that NK cells limit levels of L-2HG during infection by increasing the expression of L-2HG dehydrogenase. Excess accumulation of L-2HG resulted in impaired NK cell antiviral functions. Given the impact of L-2HG on epigenetics and metabolism, I hypothesize that L-2HG accumulation is detrimental to the NK cell antiviral response by disrupting highly coordinated changes in histone methylation and by skewing the balance between glycolytic and oxidative metabolism. Using the novel mouse models of NK- specific L-2HG accumulation and depletion that I generated in collaboration with the lab of Dr. Andrew Intlekofer, I will pursue the following aims. In Aim 1, I will use in vivo and in vitro epigenetic assays to assess the impact of L-2HG accumulation on activating H3K4me3 and repressive H3K27me3 levels during NK cell responses to MCMV. In Aim 2, I will use metabolic assays to elucidate the HIF-1⍺-dependent and -independent metabolic perturbations by L-2HG in NK cells during MCMV infection. This study will define a novel metabolic-epigenetic axis in NK cells that will inform the development of improved NK cell-based antiviral therapies. Project Number: 1F30AI194434-01 | Fiscal Year: 2025 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Sherry Fan | Institution: WEILL MEDICAL COLL OF CORNELL UNIV, NEW YORK, NY | Award Amount: $54,538 | Activity Code: F30 | Study Section: Special Emphasis Panel[ZRG1 F07C-H (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1F30AI19443401