Candidate Serum Biomarkers of Neural Injury and Neuroinflammation in Childhood Epilepsy: Comparison Between Controlled and Drug-Resistant Phenotypes

Abstract

Highlights What are the main findings? Serum NO-related metabolite levels, GFAP, and ubiquitin levels did not differ significantly between controlled and drug-resistant epilepsy groups in children. Serum NO-related metabolite levels showed a significant positive association with age exclusively in the drug-resistant epilepsy group, surviving Bonferroni correction. What are the implications of the main findings? No statistically significant between-group differences were detected in single time-point measurements of the three candidate biomarkers. The age-related increase in NO-related metabolites in drug-resistant epilepsy may reflect differences in NO metabolism associated with disease-related factors; however, this finding requires confirmation in longitudinal studies. Abstract Background: This study aimed to compare serum levels of nitric oxide (NO) related metabolites, glial fibrillary acidic protein (GFAP), and ubiquitin (UBI) between children with controlled epilepsy (CE) and drug-resistant epilepsy (DRE) of unknown etiology, and to investigate the associations between these biomarkers and electroclinical features. Methods: Eighty-five children aged 2–18 years with epilepsy of unknown etiology who had been receiving antiseizure treatment for at least six months were enrolled; 58 were classified as CE and 27 as DRE. Serum GFAP and UBI concentrations were measured using enzyme-linked immunosorbent assay, and serum NO-related metabolites were assessed using a Griess-based colorimetric assay. Between-group comparisons were performed using the Mann–Whitney U test, and associations between biomarkers and clinical variables were evaluated using Spearman rank correlation analysis. Bonferroni correction was applied for multiple comparisons. Results: Historical seizure frequency, comorbidity rate, and seizure detection on initial video-EEG differed significantly between the CE and DRE groups. However, serum NO-related metabolite, GFAP, and UBI levels did not differ significantly between the CE and DRE groups. Correlation analyses revealed a significant positive correlation between serum NO-related metabolite levels and age exclusively in the DRE group (ρ = 0.594, p = 0.001), which remained significant after Bonferroni correction. No such association was observed in the CE group. Conclusions: No statistically significant differences in the measured peripheral serum biomarkers were detected between the CE and DRE groups in this sample. The age-related increase in NO-related metabolites observed in the DRE group should be interpreted cautiously and does not establish progressive NO upregulation or cumulative neuroinflammatory burden. Studies incorporating a healthy control group, standardized sampling intervals, and longitudinal designs are needed to clarify the clinical utility of these biomarkers in childhood epilepsy.