Single-Cell RNA and TCR Sequencing Reveals Novel Immune Cell Networks in Poorly Controlled Epilepsy (S35.001)

Objective:

To perform a deep dissection of the role and regulation of innate and adaptive immunity in poorly controlled (PC) and well controlled (WC) focal epilepsy.

Background:

The role of the immune system in the pathophysiology of epilepsy has been underappreciated. There is mounting evidence that surgical epilepsy samples contain infiltrating immune cells. However, their phenotype and the mechanism of their recruitment are not well understood.

Design/Methods:

Individuals with focal epilepsy were prospectively recruited from Brigham and Women's Hospital outpatient epilepsy clinics. Epilepsy subjects were divided into a WC or PC group based on whether they had seizures within the 6 months prior to study enrollment. Age-and sex-matched healthy controls were also included. Using peripheral blood mononuclear cells (PBMCs), we performed a detailed analysis of ~84,000 PBMCs using single-cell RNA and T-cell receptor sequencing (scRNA/TCR-seq).

Results:

A total of 107 subjects were recruited including 87 epilepsy subjects and 20 healthy controls. 49.5% of epilepsy subjects had a seizure within 6 months of recruitment, and 52% had an MRI abnormality. scRNA/TCR-seq data highlighted differences in the composition of adaptive and innate immune cells in well-controlled and poorly-controlled subjects. In particular, memory CD4+ and CD8+ T-cells as well as NK T-cells that express cytotoxic cytokines such as granzyme and perforin, constitute a higher proportion of T-cells in PC epilepsy subjects, whereas CD14+ and CD16+ monocytes, and B memory cells show depletion. Moreover, ligand/receptor network analyses using the CellChat computational tool identified several statistically significant intercellular interactions such as the Selectin cell adhesion pathway that is involved in the recruitment of leukocytes to the site of injury in the brain.

Conclusions:

We identified disrupted adaptive and innate immune homeostasis in poorly controlled focal epilepsy. Network analyses revealed ligand/receptor pairs with well-known roles in lymphocyte trafficking that may be targeted for immunomodulatory interventions to treat epilepsy. Disclosure: Dr. Sarkis has nothing to disclose. Ms. Amer has nothing to disclose. Mr. Mares has nothing to disclose. Mr. Hobson has nothing to disclose. The institution of Vilas Menon has received research support from Chan Zuckerberg Initiative. The institution of Vilas Menon has received research support from National Institute of Aging. Vilas Menon has received personal compensation in the range of $0-$499 for serving as a Grant Reviewer with National Institutes of Health. Dr. Pennell has received personal compensation in the range of $0-$499 for serving as an officer or member of the Board of Directors for American Epilepsy Society. The institution of Dr. Pennell has received research support from NIH. The institution of an immediate family member of Dr. Pennell has received research support from Department of Defense. The institution of an immediate family member of Dr. Pennell has received research support from Environmental Protection Agency. The institution of an immediate family member of Dr. Pennell has received research support from NIH. The institution of an immediate family member of Dr. Pennell has received research support from Advanced Energy Consortium. Dr. Pennell has received publishing royalties from a publication relating to health care. Dr. Elyaman has nothing to disclose.