Mycobacterium tuberculosis inactivates host oxysterols to impair macrophage cholesterol homeostasis

Host oxysterols coordinate macrophage cholesterol homeostasis and antimicrobial defense, but whether pathogens directly target oxysterol signaling was previously unknown. This study identifies pathogen-mediated enzymatic oxysterol inactivation as a mechanism by which Mycobacterium tuberculosis (Mtb) subverts host cholesterol metabolism.

Mtb oxidizes the endogenous oxysterols 27-hydroxycholesterol (27-HC) and 3β-hydroxycholest-5-enoic acid (3β-HCA) into 3-oxo-Δ4 metabolites. Sputum lipidomics across TB cohorts on three continents revealed an active-disease signature characterized by 27-HC depletion and accumulation of 27-hydroxycholest-4-en-3-one (27-HCO) and 3-oxocholest-4-enoic acid (3O-CA), which normalized with treatment. In infected human macrophages, Mtb 3β-hydroxysteroid dehydrogenase (3β-Hsd) generated 27-HCO.

Unlike their parent oxysterols, 27-HCO and 3O-CA did not activate liver X receptor (LXR), and 3O-CA failed to suppress sterol regulatory element-binding protein 2 (SREBP2) target genes. Accordingly, 3β-Hsd-deficient Mtb did not induce macrophage cholesterol retention, a phenotype restored by LXR antagonism.

Thus, Mtb enzymatically inactivates host oxysterols, disrupting macrophage cholesterol homeostasis and generating treatment-responsive metabolic signatures in human TB.