Abstracts

Rationale: It is well established – though relatively unknown – that cerebral malaria (CM) leads to epilepsy. Worldwide CM leads to approximately 300,000 new cases of potentially preventable epilepsy per year. We investigated murine models of CM for evidence of post-malarial epilepsy (PoME). A PoME model would serve to both identify critical mechanisms of damage and provide a platform to investigate adjunctive therapiesMethods: We investigated combinations of different mouse strains (C57BL/6, CBA, Swiss-Webster SW) and Plasmodium-berghei (Pb) parasites (NK65 and ANKA). Cohorts of three-week old littermates were inoculated with parasitized (or non-parasitized) erythrocytes (controls). We investigated patterns of sequestration and focal ischemia in these combinations during the infectious phase (day 6 or 7 when they displayed signs of severe CM) to compare with human CM brain pathology. Stereological methods were used to quantify densities of infected and non-infected red blood cells, white blood cells, and hemorrhages in subdivisions of the hippocampus and entorhinal cortex. In four mouse/parasite combinations, mice were rescued from CM and video-EEG monitored for signs of epilepsy: Eight cohorts were rescued with Artesunate when they demonstrated signs of advanced CM. Controls received identical drug treatment as infected animals. Animals were implanted with EEG, EMG and ECG electrodes ≥14 days post treatment, and video-EEG monitored continuously for up to 8 months per animal. EEG data was analyzed for focal and generalized seizures, and quantified for latency to first seizure, semiology, and seizure rate.Results: Histological Findings: Brains from all infected animals showed signs of severe edema, including tissue separation around blood vessels not seen in controls. White blood cell densities were elevated 5-10 times over the controls throughout the brain for all models, reflective of a severe inflammatory response. Total blood cell densities were as much as 4 times higher in infected SW models compared to SW controls. Although hemorrhages were observed, they did not account for more than a few percent of this increase. Ratios of white to red blood cells were abnormally high in CBA‑PbNK65 and C57BL/6‑PbNK65 compared with human CM pathologies. Seizure Findings: Spontaneous recurrent seizures were observed in a large fraction of animals from all infected model combinations studied (SW‑PbNK65, SW‑PbANKA, C57BL/6‑PbANKA, CBA‑PbANKA) as summarized in table1, while no seizures were observed from the control animals. Seizure frequencies varied both in times per animal, among animals per combination, and among model combinations from one-per week to twenty per dayConclusions: We have developed the first models of PoME. These mouse models display various characteristics seen in human epilepsy. These models have high potential to enable us to explore physiological mechanisms that underlie epileptogenesis in humans that survive CM, and to develop rational adjunctive therapies based on these mechanisms to reduce this incidence.