Project description:Group 2 innate lymphoid cells (ILC2s) are key players in immune regulation and tissue repair in barrier immunity, but they are rarely seen in the brain. We investigated whether ILC2s in the peripheral circulation during the acute phase could infiltrate the brain parenchyma. We first transfer ILC2s intravenously into the MCAO mice and performed RNA sequencing of ILC2s isolated from the blood and the brain at different time points after MCAO.
Project description:Group 2 innate lymphoid cells (ILC2s) are key players in immune regulation and tissue repair in barrier immunity, but they are rarely seen in the brain. Since ILC2s can be intrinsically expanded by IL2/IL2 antibody complex, we investigated the transcriptomic changes induced by IL2/IL2 antibody complex (IL2-JES6-1) after ischemic stroke, we performed single-cell RNA sequencing of the CD45high immune cells from the infarcted hemisphere at day 14 after MCAO using 10x Genomics scRNAseq. To investigate the key mechanism of ILC2s-mediated long-term recovery after ischemic stroke, we performed single-cell RNA sequencing of the infarcted hemisphere at day 14 after MCAO using 10x Genomics scRNAseq.
Project description:Dysregulated long non-coding RNAs (lncRNAs) have been shown to contribute to the pathogenesis of ischemic stroke. However, the potential role of lncRNAs in post-stroke microglial reactivation remains largely unknown. Here, we uncovered that lncRNA-U90926 was significantly increased in the microglia exposed to ischemia/reperfusion in vivo and in vitro. In addition, adenovirus associated virus (AAV)-mediated microglial U90926 silencing alleviated neurological deficits and reduced infarct volume in experimental stroke mice. Microglial U90926 knockdown could reduce the infiltration of neutrophils into ischemic lesion site, which might be attributed to the downregulation of C-X-C motif ligand 2 (CXCL2). Mechanistically, U90926 directly bound to malate dehydrogenase (MDH2) and competitively inhibited MDH2-mediated decay of CXCL2 mRNA. Taken together, our study demonstrated that microglial U90926 aggravated ischemic brain injury via facilitating neutrophil infiltration, suggesting that U90926 might be a potential biomarker and therapeutic target for ischemic stroke.
Project description:Reactive astrocytes play critical roles after brain injury, but their precise function is not well defined, particularly in humans and nonhuman primates (NHPs). Here, we utilized single nuclei transcriptomics to characterize astrocytes after ischemic stroke in the primary visual cortex (V1) of the marmoset monkey. We observed nearly complete segregation between stroke and control astrocyte clusters. Screening the top 30 differentially expressed genes to identify candidates that might limit stroke recovery, we discovered that RTN4A/ NogoA, a neurite-outgrowth inhibitory protein previously associated specifically with oligodendrocytes but not astrocytes, was expressed in a majority of reactive astrocytes. Robust NogoA upregulation on reactive astrocytes following stroke was confirmed in both the marmoset and human brain, whereas rodents exhibited only a marginal change in NogoA expression following stroke. Further, in vivo and in vitro studies determined that NogoA mediated an anti-inflammatory response which likely contributes to limiting deeper infiltration of peripheral macrophages into the surviving parenchyma during the subacute post-stroke period. These findings are directly relevant to the development of NogoA-targeting therapies designed for clinical use shortly after ischemic stroke. In addition, our data have uncovered the complexity of astrocyte responses in primates, which highlights the importance of preclinical model selection for discovery research designed to identify novel therapeutics for brain injury.
Project description:Background: Previous study showed that stroke may be a potential first sign of neoplasia. But the relationship between them remains unclear. Besides, ischemic stroke is a complex brain disease, which involves cell death or complex immune regulation. Thus, it is necessary to reveal the association of tumor immune microenvironment and cell death with ischemic stroke. Methods: Here, a photothrombosis-induced ischemic injury models of brain and skull was established. We compared and analyzed the pattern of gene expression profile between brain and skull after ischemic injury by transcriptome analysis. Further, we investigated the enrichment of relevant differential genes in cancer pathways and cell death pathways, and analyzed changes in the immune microenvironment after ischemic injury. Moreover, the pan-cancer genomic and prognosis analysis of ischemic injury related gene set were performed. Results: The results showed that the gene expression patterns were different in temporal and spatial locations after ischemic injury. We found that the effect on the transcriptome of the brain after skull ischemic injury was particularly large, but it could be recovered in a short period, while the effect on the skull after brain ischemic injury was long-lasting. The expression of genes related to ischemic injury is also associated with cell death and cancer hallmark pathways. In addition, changes in the abundance of immune cells indicate that brain ischemic injury may disrupt its immune microenvironment for a longer time, while skull can better balance the stability of immune microenvironment. Moreover, the brain ischemic injury-related gene sets are highly correlated with a variety of tumors, especially GBM, KIRC, LGG and UVM after stroke have a greater risk of death. Conclusion: This study gives us a new understanding of the role of the skull in brain ischemic injury, and reveals the association of tumor immune microenvironment and cell death with ischemic stroke.
Project description:Cluster analysis using nonlinear dimensionality reduction ([tSNE]) revealed the differences in global gene expression profiles of healthy and injured striatum, and identified clusters of cells with unique genetic signatures in both ischemic brain and hemorrhagic brain. Genes with p-value < 0.05 and fold change ≥1.5 were regarded as differentially expressed genes (DEGs). For astrocytes, 135 DEGs were downregulated in hemorrhagic stroke compared to ischemic stroke. The secondary profiling of astrocytic subtypes yielded 10 different subtypes with distinct functional cell identities. For microglia, tSNE map indicated the distribution and proportion of microglia/macrophage were very similar in in the ischemic and hemorrhagic stroke models. We obtained 75 DEGs in total (hemorrhagic stroke vs. ischemic stroke, 54 were upregulated, 21 were downregulated) .
Project description:Macrophages play an important role in the pathological process of stroke. We used single cell RNA sequencing (scRNA-seq) to analyze the diversity of infiltrated macrophages from ischemic brain after stroke.
Project description:Blood monocytes/macrophages infiltrate the brain after ischemic stroke and critically influence brain injury and regeneration. We investigated stroke-induced transcriptomic changes of monocytes/macrophages by RNA sequencing profiling, using a mouse model of permanent focal cerebral ischemia. Compared to non-ischemic conditions, brain ischemia induced only moderate genomic changes in blood monocytes, but triggered robust genomic reprogramming in monocytes/macrophages invading the brain. Surprisingly, functional enrichment analysis of the transcriptome of brain macrophages revealed significant overrepresentation of biological processes linked to neurovascular remodeling, such as angiogenesis and axonal regeneration, as early as 5 days after stroke, suggesting a previously underappreciated role for macrophages in initiating post-stroke brain repair. Upstream Regulator analysis predicted peroxisome proliferator-activated receptor gamma (PPARγ) as a master regulator driving the transcriptional reprogramming in post-stroke brain macrophages. Importantly, myeloid cell-specific PPARγ knockout (mKO) mice demonstrated lower post-stroke angiogenesis and neurogenesis than wild-type mice, which correlated significantly with the exacerbation of post-stroke neurological deficits in mKO mice. Collectively, our findings reveal a novel repair-enhancing transcriptome in brain macrophages during post-stroke neurovascular remodeling. As a master switch controlling genomic reprogramming, PPARγ is a rational therapeutic target for promoting and maintaining beneficial macrophage functions, facilitating neurorestoration, and improving long-term functional recovery after ischemic stroke.
Project description:Identification of genetic aberrations in stroke, the second leading cause of death worldwide, is of paramount importance for understanding the disease pathogenesis and generating new therapies. Whole-genome sequencing from 10,241 ischemic stroke patients identified eight patients carrying gain-of-function mutations on coding variants in protein phosphatase magnesium-dependent 1 δ (PPM1D) gene. Patients carrying PPM1D mutations exhibit better stroke-related clinical phenotypes, including improvements in systolic blood pressure, fibrinogen level, low-density lipoprotein, and plateletcrit level. Experimental brain ischemia in Ppm1d-deficient (Ppm1d-/-) mice resulted in enlarged lesions and pronounced neurological impairments. Spatial transcriptomics revealed a distinct Ppm1d-associated gene expression pattern, indicating disrupted endothelial homeostasis during ischemic brain injury. Proteomic analysis demonstrated that differentially expressed proteins in primary brain endothelial cells from Ppm1d-/- mice were significantly enriched in the peroxisome proliferator-activated receptors (PPARs)-mediated metabolic signaling. Mechanistically, Ppm1d deficiency promoted aberrant fatty acid β-oxidation and increased oxidative stress, which impair endothelial cell function through the PPARα pathway. A small molecule, T2755, was identified to engage Trp427 and stabilize PPM1D protein, thereby mitigating ischemic brain injury in mice. Collectively, we found that PPM1D protects against ischemic brain injury and validates its pharmacological stabilizer T2755 as a promising therapy for ischemic stroke.
Project description:The purpose of this project was to elucidate gene expression in the peripheral whole blood of acute ischemic stroke patients to identify a panel of genes for the diagnosis of acute ischemic stroke. Peripheral blood samples were collected in Paxgene Blood RNA tubes from stroke patients who were >18 years of age with MRI diagnosed ischemic stroke and controls who were non-stroke neurologically healthy. The results suggest a panel of genes can be used to diagnose ischemic stroke, and provide information about the biological pathways involved in the response to acute ischemic stroke in humans. Total RNA extracted from whole blood in n=39 ischemic stroke patients compared to n=24 healthy control subjects.