The Transcriptional Landscape of Pericytes in Acute Ischemic Stroke

Single-nucleus RNA sequencing reveals glial cell type-specific responses to ischemic stroke in male rodents

Neuroglia critically shape the brain´s response to ischemic stroke. However, their phenotypic heterogeneity impedes a holistic understanding of the cellular composition of the early ischemic lesion. Here we present a single cell resolution transcriptomics dataset of the brain´s acute response to infarction. Oligodendrocyte lineage cells and astrocytes range among the most transcriptionally perturbed populations and exhibit infarction- and subtype-specific molecular signatures. Specifically, we find infarction restricted proliferating oligodendrocyte precursor cells (OPCs), mature oligodendrocytes and reactive astrocytes, exhibiting transcriptional commonalities in response to ischemic injury. OPCs and reactive astrocytes are involved in a shared immuno-glial cross talk with stroke-specific myeloid cells. Within the perilesional zone, osteopontin positive myeloid cells accumulate in close proximity to CD44+ proliferating OPCs and reactive astrocytes. In vitro, osteopontin increases the migratory capacity of OPCs. Collectively, our study highlights molecular cross talk events which might govern the cellular composition of acutely infarcted brain tissue.

Molecular mechanisms underlying the therapeutic effects of Linggui Zhugan decoction in stroke: Insights from network pharmacology and single-cell transcriptomics analysis

Linggui Zhugan decoction (LZD), a traditional Chinese medicine formula, has demonstrated significant therapeutic effects in managing poststroke cognitive impairment and hemiplegia. However, the precise molecular mechanisms underlying its efficacy remain incompletely elucidated. The active ingredients and target proteins of LZD were retrieved from the traditional Chinese medicine systems pharmacology database and analysis platform database, which is specifically designed for traditional Chinese medicine research. The stroke-related genes were obtained from publicly available databases. Protein-protein interaction, enrichment analysis, and single-cell data analysis were conducted to identify key cells, targets, and pathways. Molecular docking was employed to assess the binding affinity between key components and targets. Network pharmacology analysis identified 190 active ingredients and 248 targets in LZD. These targets were significantly enriched in processes and pathways such as cellular response to lipid, orexin receptor pathway, and were significantly associated with Cerebral infarction and Middle Cerebral Artery Occlusion. Intersection analysis with 2035 stroke-related genes revealed 144 potential targets, which exhibited 2870 interactions and were significantly enriched in signaling pathways such as PI3K-AKT single pathway, MAPK single pathway, and tumor necrosis factor single pathway. Gene set variation analysis showed that the targets of LZD exhibited higher enrichment scores in microglia, M2 macrophages, endothelial cells, and neutrophils, while lower enrichment scores were observed in oligodendrocytes. Furthermore, molecular docking demonstrated a strong binding affinity between key active ingredients and targets. Network pharmacology and single-cell sequencing analysis elucidated the key cells, pathways, targets, and components involved in the therapeutic mechanism of LZD for the treatment of stroke.

Pericyte Microvesicles as Plasma Biomarkers Reflecting Brain Microvascular Signaling in Patients With Acute Ischemic Stroke

BACKGROUND

Blood-based biomarkers have the potential to reflect cerebrovascular signaling after microvascular injury; yet, the detection of cell-specific signaling has proven challenging. Microvesicles retain parental cell surface antigens allowing detection of cell-specific signaling encoded in their cargo. In ischemic stroke, the progression of pathology involves changes in microvascular signaling whereby brain pericytes, perivascular cells wrapping the microcapillaries, are one of the early responders to the ischemic insult. Intercepting the pericyte signaling response peripherally by isolating pericyte-derived microvesicles may provide not only diagnostic information on microvascular injury but also enable monitoring of important pathophysiological mechanisms.

METHODS

Plasma samples were collected from patients with acute ischemic stroke (n=39) at 3 time points after stroke onset: 0 to 6 hours, 12 to 24 hours, and 2 to 6 days, and compared with controls (n=39). Pericyte-derived microvesicles were isolated based on cluster of differentiation 140b expression and quantified by flow cytometry. The protein content was evaluated using a proximity extension assay, and vascular signaling pathways were examined using molecular signature hallmarks and gene ontology.

RESULTS

In this case-control study, patients with acute ischemic stroke showed significantly increased numbers of pericyte-derived microvesicles (median, stroke versus controls) at 12 to 24 hours (1554 versus 660 microvesicles/μL; P=0.0041) and 2 to 6 days after stroke (1346 versus 660 microvesicles/μL; P=0.0237). Their proteome revealed anti-inflammatory properties mediated via downregulation of Kirsten rat sarcoma virus and IL (interleukin)-6/JAK/STAT3 signaling at 0 to 6 hours, but proangiogenic as well as proinflammatory signals at 12 to 24 hours. Between 2 and 6 days, proteins were mainly associated with vascular remodeling as indicated by activation of Hedgehog signaling in addition to proangiogenic signals.

CONCLUSIONS

We demonstrate that the plasma of patients with acute ischemic stroke reflects (1) an early and time-dependent increase of pericyte-derived microvesicles and (2) changes in the protein cargo of microvesicles over time indicating cell signaling specifically related to inflammation and vascular remodeling.

Single nucleus RNA sequencing reveals glial cell type-specific responses to ischemic stroke

Reactive neuroglia critically shape the braińs response to ischemic stroke. However, their phenotypic heterogeneity impedes a holistic understanding of the cellular composition and microenvironment of the early ischemic lesion. Here we generated a single cell resolution transcriptomics dataset of the injured brain during the acute recovery from permanent middle cerebral artery occlusion. This approach unveiled infarction and subtype specific molecular signatures in oligodendrocyte lineage cells and astrocytes, which ranged among the most transcriptionally perturbed cell types in our dataset. Specifically, we characterized and compared infarction restricted proliferating oligodendrocyte precursor cells (OPCs), mature oligodendrocytes and heterogeneous reactive astrocyte populations. Our analyses unveiled unexpected commonalities in the transcriptional response of oligodendrocyte lineage cells and astrocytes to ischemic injury. Moreover, OPCs and reactive astrocytes were involved in a shared immuno-glial cross talk with stroke specific myeloid cells. In situ, osteopontin positive myeloid cells accumulated in close proximity to proliferating OPCs and reactive astrocytes, which expressed the osteopontin receptor CD44, within the perilesional zone specifically. In vitro, osteopontin increased the migratory capacity of OPCs. Collectively, our study highlights molecular cross talk events which might govern the cellular composition and microenvironment of infarcted brain tissue in the early stages of recovery.