Integrating metabolomics and lipidomics revealed a decrease in plasma fatty acids but an increase in triglycerides in children with drug-refractory epilepsy

Abstract

Objective: The drug-refractory epilepsy (DRE) in children is commonly observed but the underlying mechanisms remain elusive. We examined whether fatty acids (FAs) and lipids are potentially associated with the pharmacoresistance to valproic acid (VPA) therapy.

Methods: This single-center, retrospective cohort study was conducted using data from pediatric patients collected between May 2019 and December 2019 at the Children's Hospital of Nanjing Medical University. Ninety plasma samples from 53 responders with VPA monotherapy (RE group) and 37 non-responders with VPA polytherapy (NR group) were collected. Non-targeted metabolomics and lipidomics analysis for those plasma samples were performed to compare the potential differences of small metabolites and lipids between the two groups. Plasma metabolites and lipids passing the threshold of variable importance in projection value >1, fold change >1.2 or <0.8, and p-value <0.05 were regarded as statistically different substances.

Results: A total of 204 small metabolites and 433 lipids comprising 16 different lipid subclasses were identified. The well-established partial least squares-discriminant analysis (PLS-DA) revealed a good separation of the RE from the NR group. The FAs and glycerophospholipids status were significantly decreased in the NR group, but their triglycerides (TG) levels were significantly increased. The trend of TG levels in routine laboratory tests was in line with the lipidomics analysis. Meanwhile, cases from the NR group were characterized by a decreased level of citric acid and L-thyroxine, but with an increased level of glucose and 2-oxoglutarate. The top two enriched metabolic pathways involved in the DRE condition were biosynthesis of unsaturated FAs and linoleic acid metabolism.

Significance: The results of this study suggested an association between metabolism of FAs and the medically intractable epilepsy. Such novel findings might propose a potential mechanism linked to the energy metabolism. Ketogenic acid and FAs supplementation might therefore be high-priority strategies for DRE management.

Keywords: children; drug-refractory epilepsy; fatty acids; lipidomics; metabolomics.

FIGURE 1

Plasma metabolomic and lipidomic profiles. (A) PLS‐DA model constructed from metabolomic and lipidomic profiling separated NR and RE group. (B) Metabolites and lipids with VIPplsda > 2. (C) Heatmap showing significant TOP 50 features found in the NR and RE group.

FIGURE 2

The related pathways associated with the DRE. (A) All enrolled pathways by MetaboAnalyst 5.0 analysis. (B) The co‐occurrence network showed correlation among various small metabolites and lipids with statistical difference.

FIGURE 3

Plasma relative levels of the defined differential metabolites and lipids. (A) Relative FAs levels. (B) Relative TG levels. (C) Relative GP levels. (D) Changes of other small metabolites.

FIGURE 4

DRE‐associated metabolites and lipids in cellular metabolic pathways. Upregulated metabolites or lipids were colored in red and downregulated metabolites were colored in blue.