Post-doctoral scientist Tulane New Orleans, Louisiana, United States
Disclosure(s):
Nivedita Tiwari, PhD: No financial relationships to disclose
Introduction/Rationale: Natural killer (NK) cells are innate cytotoxic lymphocytes that provide defense against infections. However, the mechanisms by which NK cells adapt metabolically during infection remain poorly understood. Here, we investigated metabolic regulation in NK cells during Mycobacterium tuberculosis (Mtb) infection.
Methods: Peripheral blood mononuclear cells were stimulated with live Mtb H37Rv or γ-irradiated Mtb, and expression of nutrient transporters was analyzed. Functional and metabolic properties of 4F2hc⁺ versus 4F2hc⁻ NK cells were evaluated by measuring cytokine expression, cytotoxic markers, and glycolytic gene signatures. Pharmacological blockade of 4F2hc-mediated amino acid transport was performed during co-culture of NK cells with Mtb-infected macrophages. Transcriptomic analysis was conducted to identify gene signatures.
Results: Stimulation with live or γ-irradiated Mtb upregulated the amino acid transporter 4F2hc, but not CD71, Glut1, or CD36. 4F2hc⁺ NK cells exhibited higher expression of IFN-γ, TNF-α, IL-18R, granzyme B, and glycolytic genes compared with 4F2hc⁻ NK cells. Inhibition of 4F2hc-mediated amino acid transport reduced glycolytic flux, impaired IFN-γ production, and decreased NK cell-mediated control of Mtb growth. NK cells cultured in the presence of plasma from TB patients displayed diminished 4F2hc expression, spare respiratory capacity, glycolytic ATP production, and basal glycolytic activity. Importantly, treatment with 4-hydroxypyridine increased expression of 4F2hc, LAMP-1, and granzyme A. Transcriptomic profiling revealed upregulation of amino acid metabolic pathways, including phenylalanine, tyrosine, glycine, serine, and threonine metabolism.
Conclusion: These findings identify 4F2hc as a regulator of NK cell metabolic adaptation and effector function during Mtb infection. Moreover, 4-hydroxypyridine emerges as a potential immunometabolic modulator capable of enhancing NK cell activity through the upregulation of amino acid transport and metabolic reprogramming.
