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Promoting Astrocyte-Neuron Triiodothyronine Shuttling Attenuates Brain Damage in Neonatal Hypoxic-Ischemic Encephalopathy

ABSTRACT: Background: Neonatal Hypoxic-Ischemic Encephalopathy (HIE) is a critical lifelong disabling neonatal disease with insufficient effective therapies. Signaling molecules derived from astrocyte-neuron crosstalk have the potential to improve improve the prognosis, but relevant HIE research is limited. Methods: Rice-Vannucci model-induced hypoxic-ischemic brain damage (HIBD) in postnatal day 7 (P7) rat pups was confirmed by Pathological staining and laser speckle imaging. P10 whole brains underwent single-cell RNA sequencing, astrocytes after oxygen-glucose deprivation had proteomic sequencing. Multiplex immunofluorescence identified astrocyte subtypes; Enzyme-linked immunosorbent assay and Western blotting detected thyroid hormones and signaling pathways. Therapeutic efficacy was evaluated by Pathological staining and Morris Water Maze. Results: Utilizing a comprehensive single-cell transcriptomic atlas of the entire brain, this study elucidates a significant transcriptional association between astrocytes and neurons. We identified five distinct astrocyte subpopulations and characterized the Dio2⁺Slc1a2⁺subpopulation as "Metabo-neuroprotective Astrocytes" through multi-dimensional evidence. Notably, the abundance of this subpopulation was markedly diminished in the HIBD model. Pseudotime analysis further demonstrated that astrocytic proinflammatory activity is temporally regulated. Both in vivo and in vitro experiments corroborated that enhancing Dio2 expression in astrocytes or the exogenous administration of triiodothyronine (T3) can facilitate neural repair and ameliorate behavioral outcomes during both the acute and long-term phases following HIBD. Conclusions: A novel astrocyte subpopulation with neuroprotective effects was identified in the HIE model, and the temporal heterogeneity of its proinflammatory response was revealed. Meanwhile, a new crosstalk mechanism mediated by T3 shuttling between astrocytes and neurons was discovered, which can alleviate HIBD.

ORGANISM(S): Rattus Norvegicus

SUBMITTER: ZhenLang Lin

PROVIDER: PXD068917 | iProX | Sat Sep 27 00:00:00 BST 2025

REPOSITORIES: iProX

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Project description:MartínJiménez2017 - Genome-scale reconstruction of the human astrocyte metabolic network This model is described in the article: Genome-Scale Reconstruction of the Human Astrocyte Metabolic Network. Martín-Jiménez CA, Salazar-Barreto D, Barreto GE, González J. Front Aging Neurosci 2017; 9: 23 Abstract: Astrocytes are the most abundant cells of the central nervous system; they have a predominant role in maintaining brain metabolism. In this sense, abnormal metabolic states have been found in different neuropathological diseases. Determination of metabolic states of astrocytes is difficult to model using current experimental approaches given the high number of reactions and metabolites present. Thus, genome-scale metabolic networks derived from transcriptomic data can be used as a framework to elucidate how astrocytes modulate human brain metabolic states during normal conditions and in neurodegenerative diseases. We performed a Genome-Scale Reconstruction of the Human Astrocyte Metabolic Network with the purpose of elucidating a significant portion of the metabolic map of the astrocyte. This is the first global high-quality, manually curated metabolic reconstruction network of a human astrocyte. It includes 5,007 metabolites and 5,659 reactions distributed among 8 cell compartments, (extracellular, cytoplasm, mitochondria, endoplasmic reticle, Golgi apparatus, lysosome, peroxisome and nucleus). Using the reconstructed network, the metabolic capabilities of human astrocytes were calculated and compared both in normal and ischemic conditions. We identified reactions activated in these two states, which can be useful for understanding the astrocytic pathways that are affected during brain disease. Additionally, we also showed that the obtained flux distributions in the model, are in accordance with literature-based findings. Up to date, this is the most complete representation of the human astrocyte in terms of inclusion of genes, proteins, reactions and metabolic pathways, being a useful guide for in-silico analysis of several metabolic behaviors of the astrocyte during normal and pathologic states. This model is hosted on BioModels Database and identified by: MODEL1608180000. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Background: Neonatal hypoxic-ischemic (HI) brain injury, is one of the leading causes of mortality and long-term neurological morbidity in newborns. Current treatment options for HI brain injury are very limited, but mesenchymal stem cell (MSC) therapy is a promising strategy to boost neuroregeneration after injury. Optimization strategies to further enhance the potential of MSCs are in development. In the current study we aimed to test the potency of hypoxic preconditioning (HP) to enhance the therapeutic efficacy of MSCs in a mouse model for neonatal HI injury. Methods: HI was induced on postnatal day 9 in C57Bl/6 mouse pups. MSCs were cultured at 1% oxygen levels for 24 hours prior to use (HP-MSCs) or under normoxic (21% O2) control conditions (NP-MSCs). At 10 days after induction of HI brain injury, HP-MSCs or NP-MSCs were intranasally administered. Lesion size, sensorimotor outcome, MSC migration and neuroinflammation were assessed by HE staining, cylinder rearing task, gold nanoparticle-labeled MSC tracing and IBA1 staining, respectively. In vitro, the effect of hypoxic preconditioning on MSC migration, potency and proteome profile was studied using assays for transwell-migration, neural stem cell differentiation and neuroinflammation, and LC-MS/MS, respectively. Results: HP-MSCs were superior to NP-MSCs in reducing lesion size and improving sensorimotor outcome after HI. Moreover, hypoxic preconditioning enhanced MSC migration specifically to the HI lesion after intranasal application and in vitro. Additionally, HP-MSCs enhanced neural stem cell (NSC) differentiation into more complex neurons in vitro but did not enhance anti-inflammatory effects compared to NP-MSCs. Lastly, hypoxic preconditioning enriched the expression of pathways mainly related to glucose metabolism and extracellular matrix remodeling in MSCs. Conclusions: Overall, this study showed for the first time that intranasal HP-MSC therapy is a promising optimization strategy to superiorly reduce lesion size and improve neurodevelopmental outcome in a mouse model of neonatal HI brain injury.

Project description:Hypoxic-ischemic (HI) injury in the developing brain is a common cause of disability in children, and there are no effective treatments at this time. Erythropoietin (EPO) has recently gained interest as a neuroprotective drug, and EPO and its receptor are expressed within the central nervous system. We have recently shown that pretreatment with EPO markedly reduced brain injury caused by unilateral hypoxic-ischemic insult in 7 day old mice. EPO did not reduce early signs of neuronal injury at 6 hours, but significantly protected the neonatal brain when assessed 24 hours and 7 days after HI. The mechanism of this delayed protection is unclear, but is thought to involve transcription of neuroprotective genes, possibly subsequent to activation of NFkB. By comparing gene expression in EPO- and vehicle- (VEH) treated mice after HI, we should gain insight into the mechanisms underlying the neuroprotective effects of EPO and may identify additional targets for therapeutic interventions. We will compare gene expression patterns in 7-day old mouse forebrain after 1) VEH pretreatment plus sham surgery, 2) VEH pretreatment plus HI, and 3) EPO pretreatment plus HI. We will thus identify genes induced by HI in the developing brain and characterize changes in gene expression caused by EPO pretreatment. We will use the model of neonatal hypoxic-ischemic injury and EPO treatment parameters that were used in our prior studies demonstrating neuroprotection. Based on the time-course of neuroprotection defined in our prior study and the pharmacokinetic profile of EPO, we will examine gene expression 18 hours after HI. We hypothesize that changes in gene expression after EPO pretreatment underlie the neuroprotective effects of this cytokine after neonatal hypoxic ischemic injury. We will examine gene expression in 3 groups: 1) 1) VEH pretreatment + sham surgery, 2) VEH pretreatment + HI, and 3) EPO pretreatment + HI. EPO (5U/g, i.p.) or VEH was injected in 7 day old mice, drawn from 4 litters, with 3 to 4 pups per treatment group in each litter. One hour later, the right common carotid artery was ligated under isoflurane anesthesia, animals were allowed to recover for 90 min and were then placed in hypoxic chambers (10% oxygen, balance nitrogen) for 50 min. The animals subjected to sham surgery received isoflurane anesthesia for a comparable period, incision and dissection to visualize the common carotid artery, but no ligation and no hypoxia. Eighteen hrs later, animals were anesthetized with isoflurane and the right hemisphere was rapidly dissected and placed in RNA Later (Qiagen) at 4C. Total RNA was isolated using an RNeasy lipid tissue mini kit (QIAzol lysis and RNeasy purification, Qiagen). RNA concentrations were determined spectrophotometrically and an aliquot of each sample was examined by gel electrophoresis to screen for degradation. Samples were stored at -80C. After quality control screening, we selected 5 male and 5 female samples per treatment group (extra samples were reserved). We plan to pool 1 male and 1 female for each microarray sample and we plan to run 5 microarrays from each treatment group, for a total of 15 microarrays. We would like to have Agilent Bioanalyzer quality control assays on the individual samples carried out by the consortium before pooling. We will send 10 micrograms of each sample for Agilent QC and subsequent pooling of equimolar amounts. We would like to use Affymetrix mouse gene chips (please advise which specific chips are available; are you using the GeneChip Mouse Expression array 430A or the GeneChip Mouse Genome 430 2.0 Array?).

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Promoting Astrocyte-Neuron Triiodothyronine Shuttling Attenuates Brain Damage in Neonatal Hypoxic-Ischemic Encephalopathy

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