Abstract Details

Title Paired Regional Electrophysiologic Mapping and Single-nucleus RNA Sequencing in Focal Epilepsies Reveal Distinct Cellular and Molecular Characteristics in the Seizure Focus and Penumbra

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S29 - Epilepsy: Basic Science and Mechanisms (3:30 PM-3:42 PM)

Poster/Presentation
Number 001

Objective To determine cellular and transcriptional features of the seizure focus and penumbra in patients undergoing surgical resection for intractable focal epilepsy.

Background While the electrophysiologic features of focal epilepsy are actively used clinically to guide surgical resections, studies have yet to probe underlying tissue features. The seizure focus is defined by homogenous synchronous neuronal bursting, whereas the penumbra exhibits excitatory synaptic spread without local neuronal bursting due to intact inhibition. Directly probing tissue-based alterations in these distinct regions may provide advances in understanding ictogenesis and refining therapeutic approaches for focal epilepsies.

Design/Methods We developed a novel electrographically-guided, MRI-localized approach to sample paired biopsies from 12 patients with diverse focal epilepsy etiologies undergoing resective surgery as epilepsy treatment. Regions were defined using pre-operative invasive stereo-EEG, and tissue was analyzed with single-nucleus RNA sequencing (snRNASeq) and immunohistochemistry (IHC). Differential gene expression, gene set enrichment analysis (GSEA), and single-cell hierarchical Poisson factorization (scHPF) analyses were used to identify region-specific cellular and transcriptional features.

Results snRNAseq revealed differentially increased microglial abundance and reduced proportion of PV+ interneurons within the seizure focus without a corresponding change in total neuronal abundance, findings which were validated via IHC. We also identified a relative decrease in RORB+ pyramidal neurons and VIP+ interneurons in the seizure focus. GSEA and scHPF analyses revealed elevated expression of gene signatures associated with neuronal plasticity, synapse formation, and axonogenesis in both excitatory and inhibitory neurons within the penumbra, relative to the focus.

Conclusions Our findings demonstrate distinct features in cellular composition and transcriptional programs present in the seizure focus and ictal penumbra across focal epilepsy etiologies. The enrichment of plasticity-associated gene signatures in the penumbra suggests region-specific neuronal alterations that play a role in ictogenesis and seizure spread. These findings provide grounds for future work targeting alterations to synaptic plasticity as a strategy to treat focal epilepsies.

Authors/Disclosures
Ashwin Viswanathan, BA PRESENTER	Mr. Viswanathan has nothing to disclose.
Molly Murch	Ms. Murch has nothing to disclose.
Abby Brand	The institution of Miss Brand has received research support from NIH.
Julia Furnari (Columbia University Irving Medical Center)	No disclosure on file
Divya Yadav, MD	Dr. Yadav has nothing to disclose.
Nathaniel Rolfe, BA	Mr. Rolfe has nothing to disclose.
Clara Stucke, Technician	Miss Stucke has nothing to disclose.
Anadi Mahajan, MPharm	Mr. Mahajan has nothing to disclose.
Juncheng Li (Columbia University Irving Medical Center)	No disclosure on file
Osama Al-Dalahmah (Columbia University Irving Medical Center)	No disclosure on file
Jeffrey N. Bruce, MD	The institution of Dr. Bruce has received research support from NIH. Dr. Bruce has received intellectual property interests from a discovery or technology relating to health care.
Brian J. Gill, MD	Dr. Gill has received personal compensation in the range of $500-$4,999 for serving as a Consultant for BrainLab.
Brett Youngerman, MD, MS (Columbia University)	Brett Youngerman, MD, MS has nothing to disclose.
Neil Feldstein, MD	No disclosure on file
Guy M. McKhann, MD (Columbia University)	No disclosure on file
Peter Canoll, MD, PhD	The institution of Dr. Canoll has received research support from NIH.
Catherine Schevon, MD (Columbia University Medical Center)	The institution of Dr. Schevon has received research support from NIH/NINDS. Dr. Schevon has received personal compensation in the range of $500-$4,999 for serving as a Study Section Regular Member with NIH.
Medha Menon, MBBS	Dr. Menon has nothing to disclose.
Melodie R. Winawer, MD, MS (Columbia Univ)	Dr. Winawer has nothing to disclose.

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