Project 2: Protection of Blood-Brain Barrier Function

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Project Summary – Project 2 Organophosphates (OPs) such as diisopropylfluorophosphate (DFP) are convulsant chemical threat agents that can trigger seizures that progress to life-threatening status epilepticus (SE). The current standard of care (SOC) for acute exposure focuses on the termination of SE but not necessarily on the protection against long-term adverse neurological consequences often observed in survivors. Blood-brain barrier (BBB) dysfunction as a consequence of acute OP intoxication has not been rigorously evaluated despite the possible relevance of BBB integrity in preventing neurological pathologies that can arise following various brain insults including chemical toxicosis. Moreover, the efficacy of therapeutic strategies that prevent or reverse BBB disruption to mitigate spontaneous recurrent seizures (SRS) and cognitive dysfunction following OP-induced cholinergic crisis has not been explored, even though there is a dire need to find new therapies that can address the limitations of the current SOC. To tackle these major gaps, Project 2 will use a well-established rat model of DFP intoxication to test the hypothesis that therapies that reverse BBB dysfunction when administered as adjuncts to SOC will mitigate the long-term, adverse neurological consequences of OP intoxication. The scientific premise supporting this hypothesis includes preliminary evidence demonstrating: (1) BBB leakage and the presence of microhemorrhages in brains of rats acutely intoxicated with DFP as measured by gadolinium-contrast MRI; (2) increased activity of known mediators of BBB disruption following acute DFP intoxication, consistent with the hypothesis that TGFβ signaling could be involved in the long-term adverse neurological effects triggered by DFP intoxication; and (3) blocking calpain proteolytic activity may prevent epileptogenesis. Our goals are to characterize the spatiotemporal progression of BBB dysfunction following acute OP intoxication, identify the mechanisms and engagement of therapeutic targets contributing to OP-induced BBB/neurovascular dysfunction and determine the efficacy, safety and broad-spectrum activity of the therapeutic candidates (compound 10357 - promotes cell death of PAI-1-tPA+GFAP-astrocytes, IPW-5371 - TGFβ receptor 1 & 2 inhibitor, and MDL-28170 - calpain inhibitor). If successful, this Project could be a game-changer, since it will determine translational biomarkers for identifying individuals at risk of developing chronic adverse neurological effects and identify therapeutic candidates to improve long-term neurological outcome(s) when used as adjunctive therapy to SOC. Moreover, given the similarities between the OP intoxication model and other general models of epilepsy, the possible targets and/or therapies discovered could have broader application toward other epileptogenic injuries. The exceptional integration of the experimental design, including the DFP model and the behavorial readouts, across all three Projects will generate meaningful interactions and foster data sharing for greater impact.