Abstracts

Rationale: 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 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 blocks monocyte brain entry, dampens brain inflammation, and provides neuroprotection three days after SE.

Methods: Ccr2^+/rfp heterozygous mice were subject to intraperitoneal injection of kainic acid (KA), 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- hours post-SE via oral gavage, and mice were sacrificed three days post-SE. Histochemical analysis was performed for markers of glial activation and neuronal damage; qRT-PCR was used to examine inflammatory and glial transcripts in the hippocampus.

Results: Mice subject to the CCR2 antagonist displayed faster weight recovery between one- and three-days post-SE and enhanced ability to build a nest on the third day after SE when compared to their vehicle-treated controls. The mRNA levels of inflammatory mediators were depressed by 47%, and the glial markers were reduced by 30% in mice treated with the CCR2 antagonist compared to controls. Astrocytosis (as assessed by GFAP staining), but not microgliosis, was reduced in four brain regions, and neuroprotection was observed in the hippocampus.

Conclusions: Our findings provide proof-of-concept that CCR2 antagonism after SE can alleviate multiple adverse effects, and identify CCR2+ monocytes as a viable therapeutic target. CCR2 antagonism enhances weight regain, restores behavioral impairments, reduces neuroinflammation and astrocytosis, and is neuroprotective. Ongoing studies will examine the impact of CCR2 antagonism on cognitive impairments in the epileptogenic phase after SE.

Funding: Please list any funding that was received in support of this abstract.: This work was supported by Citizens United for Research in Epilepsy (CURE) and the National Institute of Neurological Disorders and Stroke Grants R01 NS101167 (NHV) and R01 NS097776 and R01 NS112308 (RD).