Authors :
Presenting Author: MINGNAN CHEN, PHD – UNIVERSITY OF UTAH
YUJIA ZHAI, B.A. – UNIVERSITY OF UATH
IRELAND KEARNS, B.A. – UNIVERSITY OF UTAH
SHUYUN DONG, PhD – UNIVERSITY OF UTAH
TIANXIAO ZHANG, MS – UNIVERSITY OF UTAH
BRIANNA MILES, BA – UNVIERSITY OF UTAH
SHERVIN RAHIMPOUR, MD – UNIVERSITY OF UTAH
CAMERON METCALF, PHD – UNIVERSITY OF UTAH
KAREN WILCOX, PHD – UNIVERSITY OF UTAH
Rationale:
Neuroinflammation and immune cell involvement are critical factors in the development of temporal lobe epilepsy (TLE). Current anti-inflammatory therapies lack specificity, leading to broad immune suppression without effectively preventing or reducing seizures. This highlights the need for precision therapies targeting pathogenic neuroinflammation. Programmed cell death protein 1 (PD-1), expressed on activated lymphocytes but not on naive lymphocytes, emerges as a promising target for such precision therapies. This study aims to delineate the role of different immune cell populations in epileptogenesis and evaluate the therapeutic potential of targeting PD-1+ cells.
Methods:
We employed Theiler’s Murine Encephalomyelitis Virus (TMEV)-infected mice as a model for TLE. Hippocampal tissues were collected at various time points post-infection. We used single-cell RNA sequencing (scRNA-seq) and flow cytometry to profile CD45+ immune cells. Additionally, resected brain tissues from patients with refractory epilepsy were analyzed using flow cytometry to assess immune cell activation. We also investigated the ability of an anti-PD-1 immunotoxin to cross the blood-brain barrier and reach the hippocampus using ELISA.
Results:
scRNA-seq data revealed significant immune cell infiltration in the hippocampi of TMEV-infected mice during the acute phase, regardless of seizure presence. Immune cell numbers significantly decreased during the recovery phase. Notably, macrophages, dendritic cells (DCs), and NK-T cells were the most reduced immune cell subpopulations in non-seizure mice, while macrophages, neutrophils, and DCs were most reduced in recovered mice. PD-1+ cells were most abundant in the hippocampi of seizured mice, followed by non-seizured and recovered mice. Meanwhile, flow cytometry showed an increase in PD-1+ immune cells, including CD4 T cells, CD8 T cells, macrophages, and microglia, during the acute seizure phase. In TMEV-infected mice, there was a notable increase in hippocampal macrophages at both eight and fifteen days post-infection. Human samples demonstrated an increase in CD4 T cells, macrophages, and inflammatory glia in diseased hippocampal tissue compared to healthy cortical tissue, along with a rise in PD-1+ CD4 T cells. Moreover, we confirmed that the PD-1 immunotoxin could cross the blood-brain barrier, and treatment with the toxin reduced both total and PD-1+ immune cell infiltration in the hippocampus of TMEV-infected mice.
Conclusions: These findings underscore the significant role of PD-1+ immune cells in neuroinflammation and epileptogenesis. The use of PD-1 immunotoxin shows promise as a targeted therapeutic strategy for modulating neuroinflammation and preventing epileptogenesis in TLE.
Funding: University of Utah SEED grant. University of Utah the 3i Initiative Program Project Planning Grant