Abstracts

Rationale: Recurrent or prolonged seizures lead to activation of immune responses, which can further precipitate seizures and create a deleterious positive feedback loop. Ample evidence has shown effectiveness of immune-modulatory agents in treating certain epileptic encephalopathies. Anti-inflammatory therapy may also have a role in treating refractory status epileptics. We have previously reported detection of brain-infiltrating innate and adaptive immune cells in the resected brain of patients with intractable epilepsy and mice subjected to two-hit induced status epilepticus. In murine models of experimental autoimmune encephalomyelitis and West Nile virus encephalitis, we have documented the efficacy of immune modulating nanoparticles to significantly reduce inflammatory tissue damages. The goal of this project is to adopt a similar approach to treat childhood epilepsy using biodegradable nanoparticles capable of dampening the inflammation in the brain parenchyma through inhibition of peripheral immune cell infiltration. Methods: Young C57Bl/6 mice were injected intraperitoneally with proconvulsant kainic acid (KA) to induced status epilepticus (SE). High negatively charged nanoparticles derived from poly (lactic-co-glycolic acid) (PLGA) were intravenously delivered to these mice immediately after KA injection. Additional 5 doses of the nanoparticle were given to the mice up to day 6 post seizure induction. Mice were perfused with cold PBS on day 7 and brain tissues devoid of cerebellum and brain stem were processed to generate single cell suspension suitable for flow cytometric analyses. The cell preparation was then stained with fluorescently labeled cell markers for identification of different populations of immune cells. Results: We detected brain-infiltrating monocytes, macrophages, dendritic cells, B lymphocytes, T lymphocytes, and natural killer cells in control mice that had KA-SE. Significant reduction of antigen presenting cells, including inflammatory monocytes, macrophage, and dendritic cells, and lymphocytes were observed in the brain of mice treated with nanoparticles after KA-SE. Selective retention of some antigen presenting cell and lymphocytes in the spleen was detected, closely corresponding to a decrease in brain-infiltrating populations of immune cells. Additionally, the blood-derived immune cells detected in the brain parenchyma were poorly activated compared to the untreated control animals with KA-SE. Conclusions: Our preliminary data demonstrated for the first time that the control of peripheral leukocytes infiltration into the brain of mice with status epilepticus can be achieved using biodegradable immune-modulatory nanoparticles. This treatment altered the migratory behavior of major innate and adaptive immune cells and can potentially be used therapeutically to reduce immune-mediated seizure pathology and perhaps promote repair cascade. Whether early intervention in brain-specific inflammatory can reduce clinical manifestation of status epilepticus and diminish subsequent seizure needs to be determined.