Use of plasma metabolomics at diagnosis to identify metabolic pathways associated with pulmonary tuberculosis (TB) clearance: A pilot study
Authors: Chong Elizabeth , Frediani Jennifer K. , Alvarez Jessica A , Tangpricha Vin , Blumberg Henry M , Jones Dean P. , Yu Tianwei , Ziegler Thomas R. 
Published: November 2023

Background

Knowledge of metabolic pathways associated with clearance of Mycobacterium tuberculosis (Mtb) in TB disease may provide pathophysiologic insight and identify potential biomarkers. We used plasma metabolomics to identify metabolic pathways associated with pulmonary TB clearance.

Methods

We studied 66 adults with pulmonary TB disease (18 with multidrug‐resistant TB [MDR‐TB]) enrolled in a double blind, controlled, randomized trial of high‐dose vitamin D supplementationt (Vit D, 1.4M IU over 16 weeks) in Tbilisi, Georgia. Subjects entered the trial within 7 days of initiation of conventional anti‐TB drug therapy. Mtb clearance from sputum cultures (LJ solid media) obtained 8 weeks after entry was determined. Plasma was obtained at study entry (before initiation of vitamin D3 or placebo) and metabolomics analysis was performed using high‐resolution liquid chromatography mass spectrometry (LC‐MS). Individual regression models were analyzed for each detected metabolite with sputum culture conversion at 8 weeks as the independent variable and metabolite intensity as the dependent variable, adjusted for multidrug‐resistant‐TB (MDR‐TB) status, diabetes status, BMI, sex, age, treatment group (vit D3 vs placebo), and entry plasma 25‐hydroxyvitamin D level. Statistically significant (p< 0.05) metabolites were subsequently analyzed with a high‐throughput metabolomics pathway analysis program (Mummichog) to match metabolites to know metabolic pathways.

Results

After 8 wks of anti‐TB drug treatment, 52 subjects (85%) had a negative sputum culture and 9 (15 %) remained culture‐positive. Of 5,736 metabolites detected and entering downstream analysis, 267 differed (p<0.05) between subjects who had achieved sputum culture conversion to negative versus those that remained culture positive (155 metabolites were down‐regulated and 112 metabolites were up‐regulated in those who cleared sputum vs those who remained culture positive. A total of 24 specific metabolic pathways were significantly different (P<0.05) between the two groups, including urea cycle/amino group metabolism, lysine metabolism, fatty acid metabolism, unsaturated fatty acids beta‐oxidation, tryptophan metabolism, thiamine metabolism, glutathione metabolism, TCA cycle, prostaglandin formation, alanine and aspirate metabolism and leukotriene metabolism.

Conclusions

High‐resolution plasma metabolomics identified the propensity for sputum Mtb clearance in adults with newly diagnosed pulmonary TB. Numerous nutrient‐related metabolic pathways (including amino acid‐, lipid‐ and B‐vitamin‐related) and pathways involved in redox/inflammation differentiated patients who cleared sputum Mtb at 8‐weeks vs those that remained culture positive. Targeted metabolomics studies are needed to further define the metabolic pathways linking clinical TB outcomes, high‐dose vitamin D administration, and MDR‐TB status and clinical outcomes.

Support or Funding Information

This study was supported by the National Institutes of Health grants [K01 DK102851 (JAA), K24 DK096574 (TRZ), R01 ES016731 (DPJ)], D43 TW007124 (HMB), K23 AR054334 (VT), K23 AI103044 (RRK)] and the Emory Global Health institute (TRZ, VT, HMB).