Untargeted metabolomics reveals key metabolic alterations in pediatric epilepsy with insights into Tryptophan metabolism and the gut–brain axis
Karol Chojnowski, Mikołaj Opiełka, Krzysztof Urbanowicz, Marta Zawadzka, Karolina Wangin, Ryszard T. Smoleński, Maria Mazurkiewicz‐Bełdzińska
Abstract
The biochemical processes of childhood-onset epilepsy remain unclear, with no reliable biomarkers for prognosis or management. Untargeted plasma metabolomics offers a valuable approach to uncover underlying pathomechanisms and identify actionable biomarkers. In this study, plasma samples from 18 pediatric patients with epilepsy and 11 age-matched healthy controls were analyzed using liquid chromatography-mass spectrometry. Data were analyzed using univariate and multivariate statistical methods and pathway enrichment analysis. Multivariate analyses demonstrated separation between the patient and control groups. A total of 19 endogenous metabolites (VIP > 1, adjusted p < 0.05) emerged as key differentiators. Compared with controls, patients exhibited significant reductions in tryptophan (Trp), 5-Hydroxyindoleacetic acid (5-HIAA), several gut microbiota-derived metabolites, including indole, indoxyl sulfate, and p-cresyl sulfate, as well as in niacin metabolism end-products - N1-Methyl-2-pyridone-5-carboxamide (Met2PY) and N1-Methyl-4-pyridone-3-carboxamide (Met4PY). In addition, patients showed decreased levels of tricarboxylic acid (TCA) cycle intermediates, concomitant with an increase in fatty acid derivatives and N-acetylneuraminic acid (Neu5Ac). The most substantially altered metabolic pathways in epilepsy patients involved the TCA cycle, vitamin A and C metabolism, prostaglandin synthesis, and D4/E4-neuroprostane formation. Observed alterations in tryptophan and microbiota-derived metabolites suggest gut dysbiosis may contribute to epilepsy development through the gut-brain axis. Moreover, the circulatory metabolic markers indicating an energy deficit and oxidative stress underscore the systemic impact of seizure activity.