Tuberculosis hijacks lung mitochondria to weaken immunity

Tuberculosis remains a major global health threat, in part because we still do not fully understand how the immune environment in the lung decides between protective and harmful responses to infection. In work led by Jyothi Rengarajan, researchers set out to map what happens in the lung very early after exposure to Mycobacterium tuberculosis (Mtb), before clear protection or disease has developed. To do this they used a combination of high-dimensional flow cytometry, single-cell transcriptomics, and untargeted metabolomics to profile immune cells, their gene activity, and small-molecule metabolism. The team followed these changes after aerosolized Mtb infection of mice, focusing on metabolic pathways and cell interactions that might predict whether the infection would be controlled or would progress. By looking at multiple types of measurements at once, the study aimed to capture how cellular metabolism and immune signaling interact in the lung environment, and to find common features that distinguish protective responses from pathogenic ones.

The technical approach combined high-dimensional flow cytometry to define cell populations, single-cell transcriptomics to read gene activity in individual cells, and untargeted metabolomics to measure shifts in small molecules. These multimodal data showed that Mtb infection caused a sustained increase in glycolysis in the lung while simultaneously restricting oxidative phosphorylation (OXPHOS) and impairing mitochondria. The paper reports that this mitochondrial impairment is mediated in part by the Mtb serine protease Hip1, and that the resulting low energy output led to weaker macrophage-T cell interactions that favored pathogenic immunity. By contrast, lung environments that mounted a strong early induction of mitochondrial OXPHOS, amino acid metabolism, and fatty acid oxidation generated high ATP output and reinforced innate-T cell signaling networks, which correlated with protective immune responses. From these comparisons the authors identified a novel mitochondrial immunometabolic lung signature that associated with protective outcomes in both animal models and humans.

Taken together, the findings point to induction of mitochondrial dysfunction as a deliberate mechanism Mtb uses to manipulate lung immunometabolism to its advantage. The study suggests that keeping mitochondrial metabolism intact in the early lung is pivotal for steering immunity toward protection rather than disease. Because the researchers identified a reproducible mitochondrial immunometabolic signature linked to favorable outcomes, this work raises the possibility of new ways to evaluate risk and guide interventions: for example, biomarkers based on mitochondrial metabolism could help identify patients who need different treatments, and therapies that preserve or restore mitochondrial OXPHOS and related pathways might improve vaccine efficacy or host-directed treatments. The results emphasize that the metabolic state of lung immune cells is not a bystander but a central player in the outcome of Mtb infection.