Metabolic insights into the pathophysiology of tuberculous meningitis in FFPE postmortem human brain tissue

Tuberculous meningitis (TBM), caused by Mycobacterium tuberculosis, is the most severe form of extrapulmonary tuberculosis and isassociated with high morbidity and mortality, particularly when diagnosis is delayed. Improved understanding of the metabolic alterations associated withTBM may support the development of novel diagnostic biomarkers and provide insights into disease pathophysiology.

In this study, we applied anuntargeted two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) metabolomics approach to formalin-fixed, paraffin-embedded (FFPE) postmortem human brain tissue from 41 TBM cases and 36 tissue sections from 6 non-TBM control cases. Metabolomics data wereprocessed, normalized, and analyzed using multivariate and univariate statistical approaches, including principal component analysis (PCA) and partialleast squares-discriminant analysis (PLS-DA), with variable importance in projection (VIP) scores. These results were further correlated with patient clinical data.

Distinct metabolic profiles were observed between TBM and control tissues. Several metabolites were significantly reduced in TBM samples, particularly within the alkane and alkene classes, with additional decreases observed in metabolites associated with alcohols, fatty acids, lipids, carbohydrates, and amino acids. These metabolic alterations suggest substantial perturbations, primarily in the host lysine degradation pathway (linked to the kynurenine pathway), in TBM-affected brain tissue.

Collectively, these findings provide insight into the metabolic landscape of terminalTBM and suggest potential metabolic pathways that may contribute to disease pathophysiology. Further investigation of these metabolic signatures in accessible patient tissue and biofluids may support the development of biomarkers and inform future therapeutic strategies for TBM.