Rapamycin Plays an Anti-Epileptic Role by Restoring Blood-Brain Barrier Dysfunction, Balancing T Cell Subsets and Inhibiting Neuronal Apoptosis

Abstract

Background: Rapamycin (RAP), as a Mammalian Target of Rapamycin (mTOR) inhibitor, has a certain antiepileptic effect. The blood-brain barrier (BBB), neuroinflammation, lymphocyte immune cells, and neuronal apoptosis play an obligatory role in the course of a seizure. The aim of this study is to probe whether the antiepileptic mechanism of RAP involves the blood-brain barrier, neuroinflammation, lymphocytes, and neuronal apoptosis.

Methods: First, we established a rat epilepsy model by injecting lithium chloride and pilocarpine into the rats (intraperitoneal injection). Then the epileptic rats were treated with different doses of RAP (1 mg/kg.d, 2 mg/kg.d, 4 mg/kg.d). Peripheral blood, brain tissue, and temporal lobe tissue were collected. The levels of blood-brain barrier-related proteins and inflammatory cytokines in the peripheral blood of rats were measured by enzyme-linked immunosorbent assay (ELISA). The effect of RAP on T cell subsets in epileptic rats was analyzed by flow cytometry. The apoptosis of neurons and glial cells in the temporal lobe of rats was analyzed by immunohistochemistry.

Results: This study found that RAP reduces the levels of BBB-interrelated proteins (matrix metallopeptidase 9 (MMP-9), MMP-2, tissue inhibitor of metalloproteinases 1 (TIMP-1), TIMP-2) and inflammatory cytokines (interleukin-2 (IL-2), interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α)) in epileptic rats compared to the model group (p < 0.05). RAP increases the level of total T cells (CD3⁺CD45⁺) and T helper cells (CD3⁺CD4⁺), decreases the level of cytotoxic T lymphocytes (CD3⁺CD8⁺), and inhibits the apoptosis of neurons and glial cells in the temporal lobe compared to the model group (p < 0.05).

Conclusions: The antiepileptic mechanism of RAP may be to restore BBB dysfunction, reduce the inflammatory response, balance T cell subsets, and inhibit neuronal and glial cell apoptosis in temporal lobe epilepsy lesions.

Keywords: BBB; T cell subsets; epilepsy; glia; inflammatory cytokines; neurons; rapamycin.