Pharmacological inhibition of the inflammatory receptor CCR2 relieves the early deleterious consequences of status epilepticus.

Generalized status epilepticus (SE) triggers a robust neuroinflammatory response involving reactive astrocytosis, activation of brain-resident microglia, and brain infiltration of CCR2+ monocytes. Multiple lines of evidence indicate that quenching SE-induced neuroinflammation can alleviate the adverse consequences of SE, including neuronal damage and cognitive impairments. Our recent findings show that blocking monocyte brain entry after SE, via global Ccr2 KO, rescues several SE-induced adverse effects including blood-brain barrier (BBB) erosion, microgliosis and neuronal damage while enhancing weight regain. The goals of the present study were to determine if CCR2 antagonism with a small molecule after SE replicates the effects of the CCR2 knockout. Male Ccr2+/rfp heterozygous mice were subject to intraperitoneal injection of kainic acid, scored for seizure severity, weight recovery, and nest building capability. Surviving mice were randomized into CCR2 antagonist and vehicle groups. The CCR2 antagonist, or vehicle, was administered 24- and 48-h post-SE via oral gavage, and mice were sacrificed three days post-SE. Mice subject to the CCR2 antagonist displayed faster weight recovery between one- and three-days post-SE and modestly enhanced ability to build a nest on the third day after SE when compared to vehicle-treated controls. CCR2 antagonism limited monocyte recruitment to the hippocampus and reduced numbers of Iba1+ macrophages. The mRNA levels of inflammatory mediators were depressed by 47%, and glial markers were reduced by 30% in mice treated with the CCR2 antagonist compared to controls. Astrocytosis was reduced in four brain regions. Neuroprotection was observed in the hippocampus, and erosion of the BBB was lessened in mice subject to the antagonist. Our findings provide proof-of-concept that brief CCR2 antagonism beginning one day after SE can alleviate multiple adverse SE-induced effects, including functional impairment, and identify circulating CCR2+ monocytes as a viable therapeutic target.

Preclinical development of an EP2 antagonist for post-seizure cognitive deficits.

Cognitive comorbidities can substantially reduce quality of life in people with epilepsy. Inflammation is a component of all chronic diseases including epilepsy, as well as acute events like status epilepticus (SE). Neuroinflammation is the consequence of several broad signaling cascades including cyclooxygenase-2 (COX-2)-associated pathways. Activation of the EP2 receptor for prostaglandin E2 appears responsible for blood-brain barrier leakage and much of the inflammatory reaction, neuronal injury and cognitive deficit that follows seizure-provoked COX-2 induction in brain. Here we show that brief exposure of mice to TG11-77, a potent, selective, orally available and brain permeant EP2 antagonist, eliminates the profound cognitive deficit in Y-maze performance after SE and reduces delayed mortality and microgliosis, with a minimum effective i.p. dose (as free base) of 8.8 mg/kg. All in vitro studies required to submit an investigational new drug (IND) application for TG11-77 have been completed, and non-GLP dose range-finding toxicology in the rat identified no overt, organ or histopathology signs of toxicity after 7 days of oral administration at 1000 mg/kg/day. Plasma exposure in the rat was dose-linear between 15 and 1000 mg/kg dosing. TG11-77 thus appears poised to continue development towards the initial clinical test of the hypothesis that EP2 receptor modulation after SE can provide the first preventive treatment for one of the chief comorbidities of epilepsy.