The altered urine metabolome induced by DOTS therapy in pulmonary tuberculosis patients

Abstract

Metabolomics holds great promise for studying complex diseases like tuberculosis (TB), where treatment outcomes are influenced by a combination of biological, environmental, and social factors. This study aimed to gain a deeper understanding of the host's response to standardised TB treatment through a multi-platform metabolomics approach. The urinary metabolome profiles of 46 culture-confirmed TB patients (29 who were eventually cured and 17 who failed treatment) were studied at various time intervals during therapy (before treatment, after one, two and four weeks, as well as two weeks after treatment completion). To determine the impact of treatment on the host metabolome, the urine of TB patients who underwent intensive phase TB treatment for four weeks was analysed using untargeted, two-dimensional gas chromatography-mass spectrometry (GC-MS). Results pointed towards a reduction in overall oxidative stress levels, alterations in insulin secretion, urea cycle variations, and time-dependent drug-induced induction and inhibition of several enzymes during treatment. These findings provide new insights into the mechanisms of TB drug metabolism, action, and side effects. Next, the urinary acylcarnitine (detected via liquid chromatography-mass spectrometry) and amino acid profiles (detected via GC-MS) of TB patients with cured and failed treatment outcomes were compared at different treatment intervals. The results showed similar drug-induced metabolome variations in both patient groups, but with a delayed or shifted onset in the cured patients. The latter occurrence was ascribed to potential variations in drug-metabolising enzymes or variations in oxidative stress and vitamin B6 levels between these two groups. These outcomes indicate that TB drugs may not be metabolised similarly in all patients and suggest that more focus should be placed on the development of personalised TB treatment, which includes enzyme phenotyping and monitoring of oxidative stress and vitamin B6 levels, for example. To build on these findings, which include host metabolome variations induced by treatment, a subset of TB drugs and their metabolites were analysed in the urine of cured and failed treatment groups using proton nuclear magnetic resonance (1H-NMR). Results showed that, although the median concentrations of most TB drug metabolites were comparable between the two groups at various time points during treatment, isoniazid (INH)-related metabolites were comparatively higher in the failed patients throughout treatment. This variation could not be ascribed to the acetylator genotypes of this cohort, suggesting that treatment failure may be due to other factors, such as environmental conditions or individual variations in other parts of the INH metabolic pathways. Finally, the potential lasting effects of TB treatment on the host metabolome of cured and failed treatment groups were studied. Results showed that several metabolites, identified through semi-targeted 1H-NMR and amino acid GC-MS analysis, differentiated between the pre-and post-therapy samples in both patient subgroups. The cured group's post-metabolome profiles revealed a lasting drug-induced effect two weeks after the last treatment dosage, owing to differences in amino acid metabolism, one-carbon metabolism, and gut microbiome composition. The failed patient group, however, appeared to have a less severe effect of the parent drugs (particularly INH) but a significantly higher effect induced by the INH metabolites. This further supports our suggestion that INH metabolism varies between individuals, potentially leading to treatment failure. In conclusion, this study demonstrates the value of metabolomics for understanding the relationship between drugs, metabolites, and disease states. The results provide new insights into the host's response to TB treatment and highlight the complex biological factors which can influence treatment outcomes. This study warrants the need for further investigations into individual variations in TB drug metabolism and emphasises the importance of the development of personalised treatment regimens to reduce the incidence of TB treatment failure.