SAT-274 Ketone Bodies Impact Immune Cell Metabolism

Abstract Disclosure: R.J. Klein: None. Background: Dietary metabolites such as ketone bodies play a crucial role in modulating human health. Diets that elevate ketone levels, such as time-restricted eating (TRE) and very low-carbohydrate diets, have historically been used to treat refractory epilepsy due to their anti-inflammatory properties. More recently, these dietary interventions are being investigated for their potential anti-inflammatory effects in metabolic diseases, where inflammation is both a consequence and driver of dysfunction. Although ketones are known to influence immune cells, their specific impact on CD4+ T cells—key regulators of autoimmune responses—remains poorly understood. Among CD4+ subsets, Th17 cells secrete IL-17 cytokine, which is linked to various inflammatory diseases. Understanding how ketones affect Th17 cell function and IL-17 production may uncover novel therapeutic strategies for autoimmune and metabolic conditions. Methods: Peripheral blood mononuclear cells (PBMCs) were obtained from buffy coats (leukocyte-enriched peripheral blood) of healthy volunteers (N=6). CD4+ T cells were purified via negative selection using column separation. These cells were activated for 3 days using aCD3/aCD28 (TCR) stimulation and co-cultured with physiological concentrations of ketone bodies—beta-hydroxybutyrate (BHB) and acetoacetate (AcAc)-at control (NaCl), 2mM, and 5mM. Cytokine levels were quantified using ELISA, cellular metabolism was assessed with a Seahorse extracellular flux analyzer, and protein expression related to ketone metabolism was evaluated via Western blot (WB). Results: Patient demographics: median age 58 years, 66% female. Following TCR activation, TH0 cells cultured with BHB and AcAc exhibited significantly reduced secretion of IFNg (Th1) and IL-17 (Th17), while IL-5 and IL-10 levels remained unchanged. Seahorse analysis indicated a metabolic shift in 75% of subjects’ T cells from glycolysis towards oxidative phosphorylation. WB analysis showed downregulation of phosphorylated STAT1/3 and mTOR pathway proteins, including p70S6K and S6. Conclusions: These findings suggest that ketone bodies directly impact the human adaptive immune system by promoting a metabolic shift towards oxidative phosphorylation in activated CD4+T cells. This shift is associated with reduced pro-inflammatory cytokine release, potentially due to lower ATP production limiting T cell proliferation and effector function. Downregulation of the mTOR pathway, a central regulator of nutrient sensing and cell growth-may underlie this effect. These results imply that ketones may dampen CD4+T cell responses, offering therapeutic potential for inflammatory disorders such as metabolic syndrome and autoimmune disease. Ongoing research in our lab aims to further elucidate the metabolic profiles of these T cells and their interactions with other immune populations. Presentation: Saturday, July 12, 2025