Increasing SUR1-related pathway activity with increasing injury severity in immune and neurovascular cells after murine TBI (P8-1.006)

Abstract

<h3>Objective:</h3> To evaluate cell-specific changes in sulfonylurea-receptor-1 (SUR1)-transient receptor melastatin-4 (TRPM4) related pathway gene expression activity and biological processes by single-cell RNA sequencing (scRNA-Seq) across increasing severity of murine traumatic brain injury (TBI). <h3>Background:</h3> SUR1-TRPM4 inhibition is being evaluated in a phase-II TBI trial, however genes upstream/downstream of this channel may also be impacted differentially across cell types at the injury site. We hypothesized that SUR1-TRPM4 pathway gene expression and biological processes vary with severity, particularly in immune-cells subtypes. <h3>Design/Methods:</h3> Murine TBI models of increasing severity included naïve, mild-repetitive-TBI (mrTBI), Controlled-Cortical Impact (CCI). Dissociated single-cell suspensions from peri-injured tissue 24h post-TBI underwent scRNA-Seq (10X-Genomics, Illumina), pre-processing (CellRanger) and quality-control (Seurat). A network of 202 SUR1-related genes was developed and used to evaluate SUR1-pathway activity (AUCell). Gene expression, biological pathways, gene-ontology network, cell-communication and pseudotime analyses were assessed (R-packages). <h3>Results:</h3> 79,764 cells were sequenced (naïve=26,851, mrTBI=27,380, CCI=25,533), consisting of 11 cell-types and several subtypes. SUR1-pathway activity was absent in naïve myeloid cells, mildly increased in some cells after mrTBI, and markedly increased after CCI particularly in monocyte, microglia, macrophage and neutrophil subtypes. In B- and T-cells, SUR1-pathway activity was only noted after CCI. Increased SUR1-pathway activity was seen in several astrocyte- and endothelial-subtypes (limited to CCI). Only one neuronal subtype demonstrated increased SUR1-pathway activity after CCI. In immune cells S100a8, S100a9, Cxcl2, and Il1b displayed the highest correlation to SUR1-pathway activity. In astrocytes this was AQP4. Pseudotime analysis identified lineages specific for higher SUR1-pathway activity in several cell types. Biological processes associated with SUR1-pathway activity (chemotaxis, differentiation, apoptosis) were highly variable between cell types. <h3>Conclusions:</h3> SUR1-pathway activity and associated biological processes varied greatly with TBI severity (maximal in severe TBI), and cell type. These differences should be leveraged to develop cell-specific biomarkers and targeted pathway modulation/treatment. <b>Disclosure:</b> Mr. Sneiderman has nothing to disclose. Dr. Xiong has nothing to disclose. Dr. Rajasundaram has nothing to disclose. Dr. Simon has nothing to disclose. Dr. Catapano has nothing to disclose. Mrs. Mihaljevic has nothing to disclose. Dr. Shahjouei has nothing to disclose. Dr. Raikwar has nothing to disclose. Dr. Rani has nothing to disclose. Miss Trivedi has nothing to disclose. Mr. Rulney has nothing to disclose. Dr. Winkler has nothing to disclose. Ms. Miller has nothing to disclose. Mr. Lim has nothing to disclose. Ms. Feldman has nothing to disclose. Vincent Vagni has nothing to disclose. The institution of Dr. Kohanbash has received research support from NIH. Patrick M. Kochanek, MD, MCCM has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Johns Hopkins Health System. The institution of Patrick M. Kochanek, MD, MCCM has received research support from Chuck Noll Foundation. The institution of Patrick M. Kochanek, MD, MCCM has received research support from NIH. Patrick M. Kochanek, MD, MCCM has received publishing royalties from a publication relating to health care. Dr. Jha has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Biogen. An immediate family member of Dr. Jha has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for Legal fees. The institution of Dr. Jha has received research support from NIH/NINDS, Chuck Noll Foundation, University of Pittsburgh, Barrow Neurological Foundation.