Abstract 13370: Single-Cell RNA-seq Reveals Transcriptomic Modulation of Alzheimer’s Disease by Activated Protein C

Abstract

Introduction: Alzheimer’s Disease (AD) causes neuroinflammation characterized by degradation of neurological functions resulting in memory loss and confusion. Activated Protein C (APC), a plasma zymogen, has shown promising cytoprotection, anti-inflammation, and anti-apoptotic properties. ScRNA-seq allows for examining the underlying mechanisms by which APC therapy on AD at the cellular level. Hypothesis: APC treatment can ameliorate AD symptoms of 5xFAD transgenic mice. The scRNA Seq analysis could provide detailed responses of various cell populations to Alzheimer's disease pathogenesis and molecular aspects of APC therapy. Methods: Whole brain tissue were collected at 7 months, APC-treated 5xFAD mice received daily recombinant APC or saline injections. The 10x Genomics Next Gem kit was used to dissociate the tissue for sequencing. Bioinformatic analysis was performed using Seurat in R and an integrated dataset was used to compare multiple single-cell samples. Results: Bioinformatic analysis of 5xFAD versus wild type (WT) C57BL/6J mouse brain revealed much of the sample consists of microglial cells. Interestingly, 5xFAD versus WT brains have notable decreases in astrocyte and neuron populations. Administration of recombinant APC rebounds these populations to comparable levels as WT while dramatically reduces the microglial population in 5xFAD versus WT brain. The largest proportion of oligodendrocytes are also recorded after APC treatment. Differential expression testing conveys transcriptomic regulation of known AD critical genes such as Apoe , Ctsb , Trem2 , and Tyrobp by APC. Consequently, GO term enrichment uncovers inflammatory biological processes such as microglial activation to be downregulated by APC-treated 5xFAD. Additionally, recuperation of nervous system developmental processes was found in APC-treated 5xFAD mice. Conclusions: APC treatment drastically impacts the cellular pathophysiology of AD. Differential expression testing of APC treated 5xFAD versus WT mice revealed transcriptomic downregulation of AD implicated genes throughout multiple cell-types. Administration of APC significantly impacts AD implicated genes associated with AD pathogenesis through enrichment analysis.