TNFα-Mediated Necroptosis in BBB Endothelia as a Potential Mechanism of Increased Seizure Susceptibility in Mice Following Systemic Inflammation

Abstract BackgroundSystemic inflammation is a potent contributor to increased seizure susceptibility. However, less is known about the effects of systemic inflammation on blood-brain barrier (BBB) that affect neuron excitability. Necroptosis and inflammation are intimately associated in various neurological diseases. We hypothesized that necroptosis is involved in the mechanism underlying sepsis-associated neuronal excitability in BBB components.MethodsSystemic inflammation was induced by LPS. Seizure susceptibility of mice was measured by kainic acid intraperitoneal injection. Pharmacological inhibitors (C87 and GSK872) were used to block signaling of TNFα receptors and necroptosis. To identify the features of sepsis-associated response in the BBB and CNS, brain tissues of mice were obtained for assays of the necroptosis-related protein expression, and immunofluorescence staining for morphological changes of endothelia and glia. Microdialysis assay was also used to evaluate the changes of extracellular potassium and glutamate levels in brain.ResultsSignificant findings including induced increased seizure susceptibility and BBB endothelia necroptosis and leakage, Kir4.1 dysfunction, and microglia activation were observed in mice following LPS injection. Inhibition of TNFa receptor inhibitor C87 significantly attenuated increased kainic acid-induced seizure susceptibility and endothelia necroptosis and microglia activation, and restored kir4.1 protein expression, compared with those in controls. GSK872 (a RIP3 inhibitor) treatment, like C87, had consistent effects on these changes following LPS.ConclusionsOur results showed that TNFα-mediated necroptosis in BBB endothelia damage contributes to the development of increased seizure susceptibility in mice after systemic inflammation. Pharmacologic inhibition targeting this necroptosis pathway may provide a promising therapeutic approach to reduce sepsis-associated BBB dysfunction, astrocyte ion channel dysfunction, and subsequent neuronal excitability.