Th1/Th2 Imbalance in Peripheral Blood Echoes Microglia State Dynamics in CNS During TLE Progression

Central and systemic inflammation play pivotal roles in epileptogenesis and proepileptogenesis in temporal lobe epilepsy (TLE). The interplay between peripheral CD4⁺ T cells and central microglia orchestrates the "systemic-central" immune response in TLE. However, the precise molecular mechanisms linking central and systemic inflammation in TLE remain unknown. This preliminary findings revealed an imbalance in Th1/Th2 subsets in the periphery，accompanied by related cytokines release in TLE patients. they proposed that this peripheral Th1/Th2 imbalance may influence central inflammation by mediating microglial state dynamics within epileptic foci and distant brain regions. In Li-pilocarpine-induced TLE rats, a peripheral Th1/Th2 imbalance and observed corresponding central and systemic responses is confirmed. Notably, CD4⁺ T cells infiltrated through the compromised blood-brain barrierand are spatially close to microglia around epileptic foci. Intravenous depletion and reinfusion of CD4⁺ T cells modulated microglia state dynamics and altered neuroinflammatory cytokines secretion. Moreover, mRNA sequencing of the human hippocampus identified Notch1 as a key regulator of Th1/Th2 differentiation, CD4⁺ T cell recruitment to brain infiltration sites, and the regulation of microglial responses, seizure frequency, and cognition. This study underscores the significance of Th1/Th2 imbalance in modulating the "systemic-central" response in TLE, highlighting Notch1 as a potential therapeutic target.