Tk2 deficiency-mediated mitochondrial dysfunction drives neuroinflammation and seizure frequency in epilepsy

Seizure frequency is a key indicator of disease severity and treatment response in epilepsy, yet its molecular determinants remain unclear. We performed proteomic profiling of resected epileptogenic brain tissue from patients, stratified by seizure frequency and by temporal versus extratemporal origin, and functionally validated candidate differentially expressed proteins (DEPs). Seizure foci of high and low frequencies in distinct brain regions displayed region-specific proteomic profiles. However, bioinformatic analyses of both temporal and extratemporal cohorts consistently showed that the down-regulated proteins converge on mitochondrial localization and function. Among these, mitochondrial thymidine kinase 2 (Tk2) exhibited a robust inverse correlation with seizure frequency, a finding confirmed in patient tissues across different frequency groups. Consistently, Tk2 expression was reduced across multiple brain regions in two seizure models induced by pilocarpine or ferric chloride. Mechanistically, loss of Tk2 activated the cGAS-STING pathway, upregulated inflammatory genes, and then increased seizure susceptibility. These findings identify Tk2 as a mitochondrial kinase that couples energetic failure to neuroinflammation, and provide a mechanistic basis for targeting the Tk2-mitochondria-inflammation axis in epilepsy.