StEPing "EP2" to Prevent Status Epilepticus-Induced Mortality and Inflammation

Pharmacological modulation of cytokines correlating neuroinflammatory cascades in epileptogenesis

Epileptic seizure-induced brain injuries include activation of neuroimmune response with activation of microglia, astrocytes cells releasing neurotoxic inflammatory mediators underlies the pathophysiology of epilepsy. A wide spectrum of neuroinflammatory pathways is involved in neurodegeneration along with elevated levels of inflammatory mediators indicating the neuroinflammation in the epileptic brain. Therefore, the neuroimmune response is commonly observed in the epileptic brain, indicating elevated cytokine levels, providing an understanding of the neuroinflammatory mechanism contributing to seizures recurrence. Clinical and experimental-based evidence suggested the elevated levels of cytokines responsible for neuronal excitation and blood-brain barrier (BBB) dysfunctioning causing the drug resistance in epilepsy. Therefore, the understanding of the pathogenesis of neuroinflammation in epilepsy, including migration of microglial cells releasing the inflammatory cytokines indicating the correlation of elevated levels of inflammatory mediators (interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) triggering the generation or recurrence of seizures. The current review summarized the knowledge regarding elevated inflammatory mediators as immunomodulatory response correlating multiple neuroinflammatory NF-kB, RIPK, MAPK, ERK, JNK, JAK-STAT signaling cascades in epileptogenesis. Further selective targeting of inflammatory mediators provides beneficial therapeutic strategies for epilepsy.

Targeting prostaglandin receptor EP2 for adjunctive treatment of status epilepticus

Status epilepticus (SE) is an emergency condition that can cause permanent brain damage or even death when generalized convulsive seizures last longer than 30 min. Controlling the escalation and propagation of seizures quickly and properly is crucial to the prevention of irreversible neuronal death and the associated morbidity. However, SE often becomes refractory to current anticonvulsant medications, which primarily act on ion channels and commonly impose undesired effects. Identifying new molecular targets for SE might lead to adjunctive treatments that can be delivered even when SE is well established. Recent preclinical studies suggest that prostaglandin E2 (PGE₂) is an essential inflammatory mediator for the brain injury and morbidity following prolonged seizures via activating four G protein-coupled receptors, namely, EP1-EP4. Given that EP2 receptor activation has been identified as a common culprit in several inflammation-associated neurological conditions, such as strokes and neurodegenerative diseases, selective small-molecule antagonists targeting EP2 have been recently developed and utilized to suppress PGE₂-mediated neuroinflammation. Transient inhibition of the EP2 receptor by these bioavailable and brain-permeable antagonists consistently showed marked anti-inflammatory and neuroprotective effects in several rodent models of SE yet had no noticeable effect on seizures per se. This review provides overviews and perspectives of the EP2 receptor as an emerging target for adjunctive treatment, together with the current first-line anti-seizure drugs, to prevent acute brain inflammation and damage following SE.