Fatty acid metabolism in neutrophils promotes lung damage and bacterial replication during tuberculosis

Abstract

Mycobacterium tuberculosis(Mtb) infection triggers a significant influx of neutrophils to the lungs, which is linked to tuberculosis (TB) severity. The mechanism by which Mtb infection induces neutrophillic inflammation remains unclear. Using a clinically relevant and hypervirulent Mtb strain from the W-Beijing family, HN878, we found that genes related to both glycolysis and fatty acid metabolism are upregulated in the lung neutrophils of susceptible mice. Similar effects in gene expression were observed in rabbits, and humans with pulmonary TB compared to healthy controls. Inhibiting glycolysis with 2-deoxy D-glucose (2-DG) exacerbated disease pathology, while fatty acid oxidation (FAO) inhibitor Etomoxir (ETO) improved outcomes by reducing weight loss, immunopathology, and bacterial replication within neutrophils in genetically susceptible mice. Notably, ETO reduced neutrophil production in the bone marrow and their recruitment to the lungs. ETO specifically restrained the recruitment of Ly6Glow/dimimmature neutrophil population, which is elevated during disease progression and harbors the bulk of bacilli. In a transwell setup, we demonstrated that ETO dose-dependently inhibited neutrophil chemotaxis towards infected macrophages. In summary, our research highlights the crucial role of fatty acid metabolism in regulating neutrophilic inflammation during TB and provides a rationale for targeting immunometabolism of neutrophils for potential TB treatment.