Cross-Disease Bioinformatics Analysis to Elucidate Roles of Astrocytic Pathways Regulating Neuroinflammation in Autism Spectrum Disorder

Abstract

While neuroinflammation has been implicated as a significant component in autism spectrum disorder (ASD) and its etiology [5], the molecular mechanism in the disease is not well understood. Astrocytes are the most abundant glial cell type in the central nervous system (CNS). They respond to inflammatory signals and can themselves promote inflammation, which makes them important players in neurologic diseases [19]. Advances in single-cell genomics and transcriptomics have fueled the identification of novel pathways that control astrocyte functions associated with chronic neuroinflammatory disorders such as multiple sclerosis (MS) [2]. These advances present an opportunity to study the common molecular mechanisms underlying neuroinflammation in both ASD and MS. In this paper, we analyze and characterize the common astrocytes subpopulations shared in both ASD and MS using the large-scale single-cell RNA-seq expression data collected from postmortem brain samples of subjects diagnosed with ASD (PRJNA434002) and MS (PRJNA544731). Batch correction [11] was implemented using Harmony [10] to strengthen the unbiased analysis. Seurat and SC3 were used for the identification of common astrocyte clusters and their marker genes; DESeq2 for disease-specific differentially expressed gene (DEG) analysis; Monocle and Enrichr for trajectory, enrichment, and ingenuity pathway analysis (IPA) of DEGs. Finally, GSEA was performed on IPSC bulk-RNA sequencing data to further characterize the common pro-inflammatory astrocytes subpopulations using transcriptional signatures of secondary progressive MS. This research revealed that oxidative stress-induced ferroptosis plays a pronounced role in the pathological astrocyte subpopulations common to both diseases. The discovery enables us to hypothesize that FTH1, SLC7A11, SAT1, CP, FTL and MAPK signaling are potentially involved in ASD pathophysiology, which could be further explored as novel targets for disease intervention.