Leveraging Preclinical Repeated Blast Traumatic Brain Injury to Model Military-Relevant Post-Traumatic Epilepsy

This is a pre-application for a Level I Idea Development Award for FY23 Epilepsy Research Program (ERP) focused on generating a new model of military-relevant post-traumatic epilepsy (PTE). The title of our proposal is “Leveraging preclinical repeated blast traumatic brain injury to model military-relevant post-traumatic epilepsy.” Using a validated blast overpressure device, our team will systemically use varying peak overpressure severities to examine incidence of long-term spontaneous seizure activity. The goal of this proposal is to model PTE using blast traumatic brain injury (bTBI), including continuous monitoring of seizure activity, a focus on blood-brain barrier pathology, and using the FDA-approved LOX/COX inhibitors zileuton/celecoxib to modulate outcomes. Proposed research will utilize expertise of the PI, Dr. Brad Hubbard, who is an expert on bTBI modeling in addition to pathology and behavioral outcomes. The research mentor for this project is Dr. Bjoern Bauer, who has extensive expertise in epilepsy and blood-brain barrier investigations. This proposal meets several criteria of the FY23 ERP Focus Area: “Markers and Mechanisms: Identifying biomarkers or mechanisms of PTE, including predictive biomarkers of epileptogenesis and research into the prevention of epilepsy and/or seizures. Additionally, the ERP Focus Area: “Innovative Research: tools intended to better inform PTE research and care, including strategies that will improve seizure detection, characterization, visualization, and diagnosis and development of new models or better characterization of existing etiologically relevant models for PTE. Background/Research Problem: Between 1.9 and 3.8 million TBIs are estimated to occur every year in the U.S. 1, resulting in upwards of 300,000 hospitalizations 2 and $60 billion in direct healthcare costs 3. The vast majority of TBIs fall within the mild category 4 and do not require hospitalization. For military personnel, traumatic brain injury (TBI) can result directly from blast exposure, without any blunt impact. Low levels of blast, with any diagnosed concussion, can lead to long-term neuropsychological deficits and neurological disease, such as epilepsy [7-9]. While the exact prevalence of PTE in the military is unknown, the significance of this growing problem is underscored by the creation of Epilepsy Centers of Excellence within the Veterans Health Administration. These centers serve Veterans, who experience new-onset epilepsy from TBI 5. In a small cohort study of Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) Veterans, who suffer from both epilepsy and TBI, blast exposure was the most frequent cause of TBI 6. Further, PTE was clinically diagnosed in almost twenty percent 6. Given this evidence of brain pathology following blast exposure7 and the link between seizure disorders and blood-brain barrier (BBB) dysfunction8, further investigation of blast-induced PTE is warranted 9. The current proposal is built upon the idea that bTBI generates PTE, which leads to blood-brain barrier dysfunction. To investigate this idea, a series of Aims will be conducted. Specific Aims and Study Design: Aim 1: Determine model severity by monitoring long-term seizure activity in a model of repeated blast traumatic brain injury (bTBI). Our group has found that bTBI repeated twice with a 24hr interval can result in on-going secondary blood-brain barrier dysfunction. Based on these findings, we will repeat bTBI at three different peak overpressure levels (11psi, 16psi, and 21psi) using the McMillan Blast Device. Male and female Sprague Dawley rats will be divided into four groups: 1) Sham, 2) mild bTBI (11psi), 3) moderate bTBI (16psi), 4) severe bTBI (21 psi). After two months, animals will be introduced to piezo cages with video monitoring and tracked over the course of a month for the development of seizure activity and PTE. Piezo cages track animal movement and convulsions and are a non-invasive alternative to EEG monitoring. At three months after bTBI, animals will be euthanized and brains will be removed to investigate BBB pathology. Aim 2: Determine the effect of LOX/COX inhibition on BBB pathology and seizure burden in PTE. bTBI severity will be chosen based on Aim 1. Sprague Dawley rats will be divided in 4 groups: 1) Sham + Vehicle, 2) bTBI + Vehicle, 3) Sham + Zileuton/Celecoxib and 4) bTBI + Zileuton/Celecoxib. This Aim will utilize both male and female rats to assess the effect of inhibiting LOX/COX with the FDA-approved drugs zileuton/celecoxib on BBB pathology and seizure burden (see Aim 1) in PTE animals. Military Relevance: Military personnel and Veterans of the armed forces can suffer from seizure activity and PTE. There are currently a lack of blast TBI models to investigate the pathological underpinnings or blast-induced PTE and evaluate efficacy of therapeutic options. This proposal will meet this need.