Project description:Brain pericytes are important to maintain vascular integrity of the neurovascular unit under both, physiological and ischemic conditions. Ischemic stroke is known to induce an inflammatory and hypoxic response due to the lack of oxygen and glucose in the brain tissue. How this early response to ischemia is molecularly regulated in pericytes is largely unknown but may be of importance for future therapeutic targets .Here we evaluate the transcriptional responses in in vitro cultured human brain pericytes after oxygen and/or glucose deprivation. Hypoxia has been widely known to stabilise the transcription factor hypoxia inducible factor 1-alpha (HIF1alpha) and mediate the induction of hypoxic transcriptional programs after ischemia. However, we find that the transcription factors Jun Proto-Oncogene (c-JUN), Nuclear Factor Of Kappa Light Polypeptide Gene Enhancer In B-Cells (NFkappaB) and signal transducer and activator of transcription 3 (STAT3) bind genes regulated after 2 hours of omitted glucose and oxygen before HIF1alpha. Potent HIF1alpha responses require 6 hours of hypoxia to substantiate transcriptional regulation comparable to either c-JUN or STAT3. We show that STAT3 and c-JUN are regulating their bound genes before HIF1alpha after 2 hours of hypoxia or omitted glucose and oxygen, suggesting that HIF1alpha is not the initiating trans-acting factor in the response of pericytes to ischemia.
Project description:The current treatment options for ischemic stroke aim to achieve reperfusion but are time critical. Novel therapeutic approaches that can be given beyond the limited time window of 3 - 4.5 hours are still an unmet need to be addressed to improve stroke outcome. The lack of oxygen and glucose in the area of ischemic injury initiates a pathological cascade leading to blood-brain barrier (BBB) breakdown, inflammation and neuronal cell death, a process that may be intercepted to limit stroke progression. Pericytes located at the blood/brain interface are one of the first responders to hypoxia in stroke and therefore a potential target cell for early stroke interventions. Using single-cell RNA sequencing in a mouse model of permanent middle cerebral artery occlusion, we investigated the temporal differences in transcriptomic signatures in pericytes at 1, 12, and 24 hours after stroke compared to the contralateral hemisphere. Our results reveal a stroke-specific subcluster of pericytes that is present at 12 and 24 hours and characterized by the upregulation of genes mainly related to cytokine signalling and immune response. This study identifies temporal transcriptional changes in the acute phase of ischemic stroke that reflect the early response of pericytes to the ischemic insult and its secondary consequences and may constitute potential future therapeutic targets.
Project description:Background While the role of pericytes in blood-brain barrier (BBB) disruption and neuroinflammation is well-established in adult neurological disorders, their contribution to neonatal brain injury is largely unexplored. Here, we investigated the role of brain pericytes in hypoxic-ischemic (HI) brain injury in the developing brain, with a particular focus on the regulatory role of pericyte-derived microRNA210 (miR210) in pericyte dysfunction. Methods HI brain injury was induced on postnatal day 9 transgenic mice, including Atp13a5-tdTomato brain pericyte reporter mice, pericyte-specific diphtheria toxin receptor mice, miR210 knockout mice, and wild-type controls. Post-injury assessments include brain infarct, brain edema, BBB permeability, ELISA, western blotting, immunostaining, and neurological function test. BBB-associated cells, including pericytes and endothelial cells, were isolated from mouse brain using an immunomagnetic approach. RNA sequencing analysis was conducted to examine transcriptomic changes in pericytes after HI. To investigate the regulatory role of miR210 in pericyte dysfunction and its underlying mechanisms, primary pericytes were transfected with miR210 mimic or negative control, followed by oxygen-glucose deprivation. Transfected cells were also treated with either interleukin 1 type 1 receptor neutralizing antibody or recombinant interleukin 1 type 2 receptor chimera protein. Post-assays included RT-qPCR, immunostaining and cell viability assay. Student’s t test or one-way ANOVA followed by Bonferroni test was used, as appropriate. Results HI resulted in a time-dependent loss of pericytes in pericyte reporter mouse pups. Ablation of brain pericytes exacerbated BBB disruption and HI brain injury in neonatal brain. miR210 deletion mitigated brain pericyte loss and BBB leakage post-HI. Transcriptomic analysis revealed that HI-induced pericyte dysfunction was associated with upregulated genes enriched in biological processes such as “cellular response to interleukin 1”. miR210 knockout suppressed the expression of proinflammatory markers such as Il1r1. Mechanistically, miR210 overexpression increased proinflammatory cytokine levels and promoted pericyte cell death under oxygen-glucose deprivation, effects that were reversed by IL1R1 blockade. Importantly, brain pericyte-specific miR210 deletion preserved pericyte viability and BBB integrity, and provided neuroprotection after HI. Conclusions These findings underscore the critical role of brain pericytes in BBB function in the developing brain and identify miR210 as a central regulator of pericyte dysfunction following neonatal HI brain injury.
Project description:Hypoxic ischemic encephalopathy (HIE) is a primary cause of neonatal death and disabilities resulting from perinatal hypoxia. The progression of HI injury is closely associated with neuroinflammation. Therefore, suppressing inflammatory pathways is a promising therapeutic strategy for treating HIE. Echinatin (Ech) is a principal active component of glycyrrhiza, with anti-inflammatory and anti-oxidative effects, often combined with other herbs to exert effects of clearing heat and detoxifying. This study aimed to investigate the anti-inflammatory and neuroprotective effects of Ech on neonatal rats with hypoxic-ischemic brain damage and on PC12 cells induced by oxygen-glucose deprivation (OGD).
Project description:The integrity and function of the blood-brain barrier (BBB) are largely regulated by pericytes. Pericyte deficiency leads to BBB breakdown and neurological dysfunction in major neurological disorders including stroke and Alzheimer’s disease (AD). Transplantation of pericytes derived from induced pluripotent stem cells (iPSC-PC) has been shown to restore the BBB and improve functional recovery in mouse models of stroke and pericyte deficiency. However, the molecular profile and functional properties of iPSC-PC under hypoxic conditions, similar to those found in ischemic and neurodegenerative diseases remain largely unexplored. Here, we demonstrate that iPSC-PC under severe hypoxia retain essential functional properties, including key molecular markers, proliferation rates, and the ability to migrate to host brain vessels via function-associated PDGFRB-PDGF-BB signaling. Additionally, we show that iPSC-PC exhibit similar clearance of amyloid beta (Aβ) neurotoxins from AD mouse brain sections under both normoxic and hypoxic conditions. These findings suggest that iPSC-PC functions are largely resilient to hypoxia, highlighting their potential as a promising cell source for treating ischemic and neurodegenerative disorders.
Project description:We report the miRNA-Seq and Nanostring mRNA data from regional brain samples after neonatal hypoxic-ischemic brain injury (induced by unilateral carotid artery ligation and 30 minutes at 8% oxygen in CD1 mice at postnatal day 9). Analyses are perfomed in the cerebellum, striatum/thalamus, and whole cortex. Examination of regional small RNA expression between four postnatal day 9 mouse pups after hypoxic-ischemic brain injury versus four sham surgery controls
Project description:Our results revealed that hypoxic-ischemic brain injury decreased the overall 5hmC abundance in rat temporal cortex, and these results suggest that 5hmC modifications are involved in the cerebral palsy pathogenesis.