Evaluation of serum irisin and meteorin-like (METRNL) levels in people with drug-resistant and drug-responsive temporal lobe epilepsy

Abstract

Objective: Temporal lobe epilepsy (TLE) is associated with significant comorbidities, including cognitive decline and psychiatric disorders. Myokines, such as irisin and meteorin-like (METRNL) hormone, are secreted during physical activity and possess neuroprotective and anti-inflammatory properties. This study aimed to evaluate serum irisin and METRNL concentrations in people with TLE (drug-resistant and drug-responsive) compared to healthy controls and to analyze their correlation with depression, anxiety, cognitive function, and physical activity. Materials and Methods: This cross-sectional study included adult participants divided into three groups: drug-resistant TLE, drug-responsive TLE, and healthy controls. Serum irisin and METRNL levels were quantified using ELISA. Neuropsychological status was assessed using the Beck Depression Inventory (BDI), Spielberger State-Trait Anxiety Inventory (STAI), and Mini-Mental State Examination (MMSE). Physical activity was evaluated using the International Physical Activity Questionnaire (IPAQ). Results: Serum METRNL levels were significantly lower in both the drug-resistant and drug-responsive TLE groups compared to the control group (p = .001). Multivariable regression analysis confirmed that epilepsy status was independently associated with lower METRNL levels (p = .039). Conversely, serum irisin levels did not differ significantly among the groups (p = .124). Participants with TLE exhibited significantly lower physical activity and MMSE scores compared to controls. Additionally, the drug-resistant TLE group showed significantly higher depression and state anxiety scores. A positive correlation was observed between physical activity levels and serum METRNL concentrations. Conclusion: Serum METRNL levels are significantly reduced in people with TLE regardless of drug resistance, whereas irisin levels remain unchanged. The reduction in METRNL may reflect underlying neuroinflammatory or metabolic dysfunctions associated with epilepsy. Given the association between physical activity and METRNL, lifestyle interventions may offer therapeutic potential. METRNL warrants further investigation as a candidate biomarker for TLE.