Abstract TMP32: Transcriptome Changes of Brain Myeloid Cells After Ischemic Stroke in Type 2 Diabetic Mice

Abstract

Introduction: Type 2 diabetes mellitus (T2DM) is associated with poor outcome after stroke. Brain myeloid cells are considered to play a pivotal role in modulating brain damage and recovery after stroke, but how myeloid response to stroke under diabetic condition is largely unclear. We used single-cell RNA sequencing (scRNA seq) to determine the transcriptome profiles of brain myeloid cells under diabetic and ischemic conditions using T2DM mouse model. Hypothesis: The altered gene expression in the brain myeloid cells under diabetic condition leads to the aggravation of ischemic brain injury. Methods: We performed scRNA seq in Percoll gradient-isolated brain mononuclear cells from middle-aged db/db and db/+ mice three days after direct middle cerebral artery occlusion (MCAO) or sham-operation. Clusters of brain myeloid cells were predominantly annotated as macrophages (mp) or microglia (mg) according to the expression of marker genes in each cell type. We identified DM-unique differentially expressed genes (DEGs) and stroke-unique DEGs, and assessed the biological role of these DEGs by enrichment analysis. Results: Myeloid cell population was increased in DM ( db/db without MCAO; mp 37.3% mg 10.6%) and stroke ( db/+ with MCAO; mp 26.2% mg 33.2%) group compared to control ( db/+ without MCAO; mp 3.4% mg 0.8%) group. In macrophages, 91 DM-unique (64 up- and 27 down-regulated) and 464 stroke-unique (458 up- and 6 down-regulated) DEGs were identified, whereas 258 stroke-unique (254 up- and 4 down-regulated) DEGs were identified in microglia. Enrichment analysis revealed that DM-unique down-regulated DEGs in macrophages were related to MHC class II antigen processing involved in Staphylococcus aureus infection pathway, indicating a possible relationship between immunosuppression and stroke aggravation in diabetes. DM-unique and stroke-unique up-regulated DEGs were related to oxidative phosphorylation, phagocytosis, and protein metabolism. Conclusions: The present study demonstrated altered gene expression profile and molecular network of brain myeloid cells in response to diabetic and ischemic conditions by scRNA seq, providing a clue to the underlying mechanism of the adverse effect of T2DM on stroke.