Mouse Model Of Stroke Research Articles

Mesenchymal stem cells with p38 mitogen-activated protein kinase interference ameliorate mouse ischemic stroke.

Mesenchymal stem cells (MSCs) have been widely used in the treatment of ischemic stroke. However, factors such as high glucose, oxidative stress, and aging can lead to the reduced function of donor MSCs. The p38 mitogen-activated protein kinase (MAPK) signaling pathway is associated with various functions, such as cell proliferation, apoptosis, senescence, differentiation, and paracrine secretion. This study examined the hypothesis that the downregulation of p38 MAPK expression in MSCs improves the prognosis of mice with ischemic stroke. Lentiviral vector-mediated short hairpin RNA (shRNA) was constructed to downregulate the expression level of p38 MAPK in mouse bone marrow-derived MSCs. The growth cycle, apoptosis, and senescence of MSCs after infection were examined. A mouse model of ischemic stroke was constructed. After MSC transplantation, the recovery of neurological function in the mice was evaluated. Lentivirus-mediated shRNA significantly downregulated the mRNA and protein expression levels of p38 MAPK. The senescence of MSCs in the p38 MAPK downregulation group was significantly reduced, but the growth cycle and apoptosis did not significantly change. Compared with the control group, the infarct volume was reduced, and the neurological function and the axonal remodeling were improved in mice with ischemic stroke after transplantation of MSCs with downregulated p38 MAPK. Immunohistochemistry confirmed that in the p38 MAPK downregulation group, apoptotic cells were reduced, and the number of neuronal precursors and the formation of white matter myelin were increased. In conclusion, downregulation of p38 MAPK expression in MSCs improves the therapeutic effect in mice with ischemic stroke, an effect that may be related to a reduction in MSC senescence. This method is expected to improve the efficacy of MSCs in patients, especially in patients with underlying diseases such as diabetes, thus providing a basis for clinical individualized treatment for cerebral infarction.

MMP-2-mediated Scube2 degradation promotes blood-brain barrier disruption by blocking the interaction between astrocytes and endothelial cells via inhibiting Sonic hedgehog pathway during early cerebral ischemia.

We have previously demonstrated a rapid secretion of matrix metalloproteinase-2 (MMP-2) in the ischemic brain. Since Scube2 can interact with Sonic hedgehog (Shh) to maintain blood-brain barrier (BBB) integrity via regulating the interaction between brain capillary endothelial cells (ECs) and perivascular astrocytes, and it is also a substrate of MMP-2, we hypothesized that the secreted MMP-2 could degrade Scube2 and contribute to ischemic BBB disruption. Using an invitro ischemic model of 90-min oxygen-glucose deprivation/3-h reoxygenation (OGD/R) and an invivo mouse stroke model of 90-min middle cerebral artery occlusion (MCAO) with 3-h reperfusion, we established an important role of MMP-2-mediated Scube2 degradation in early ischemic BBB disruption. Exposure of C8-D1A cells and bEnd.3 cells to OGD/R increased MMP secretion in both cells, and C8-D1A cells appeared to secrete more MMPs than bEnd.3 cells. Co-IP and double-immunostaining revealed that Scube2 co-localized well with MMP-2 in C8-D1A cells and could be pulled down by MMP-2 antibodies. In MCAO mice, Scube2 protein showed a drastic reduction in ischemic brain tissue, which was accompanied by suppressed expression of Shh and its downstream molecules. Of note, specific knockdown of astrocytic Scube2 with AAV-shScube2 augmented MCAO-induced Shh suppression and exacerbated BBB leakage and inflammatory reactions in the ischemic brain. Last, incubation of bEnd.3 cells with conditioned medium derived from OGD-treated C8-D1A cells led to a significant inhibition of the Shh pathway in bEnd.3 cells and degradation of VE-cadherin and ZO-1. Inhibition of MMP-2 with SB-3CT or over-expression of Scube2 with plasmids in C8-D1A cells alleviated the above effect of C8-D1A cells-derived conditioned medium. Taken together, our data indicate that ischemia-induced secretion of MMP-2 may contribute to early BBB disruption in ischemic stroke via interrupting the shared Scube2-Shh pathway between brain capillary ECs and perivascular astrocytes.

Phase-Change Based Oxygen Carriers Improve Acute Cerebral Hypoxia.

Stroke is the second leading cause of death worldwide, and hypoxia is a major crisis of the brain after stroke. Therefore, providing oxygen to the brain microenvironment can effectively protect neurons from damage caused by cerebral hypoxia. However, there is a lack of timely and effective means of oxygen delivery clinically to the brain for acute cerebral hypoxia. Here, a phase-change based nano oxygen carrier is reported, which can undergo a phase change in response to increasing temperature in the brain, leading to oxygen release. The nano oxygen carrier demonstrate intracerebral oxygen delivery capacity and is able to release oxygen in the hypoxic and inflammatory region of the brain. In the acute ischemic stroke mouse model, the nano oxygen carrier can effectively reduce the area of cerebral infarction and decrease the level of inflammation triggered by cerebral hypoxia. By taking advantage of the increase in temperature during cerebral hypoxia, phase-change oxygen carrier proposes a new intracerebral oxygen delivery strategy for reducing acute cerebral hypoxia.

Shexiang Tongxin dropping pills protect against ischemic stroke-induced cerebral microvascular dysfunction via suppressing TXNIP/NLRP3 signaling pathway

Ethnopharmacological relevancePatients with ischemic stroke (IS) often continue to exhibit cerebral microcirculatory dysfunction even after receiving thrombolytic therapy. Enhancing the function of cerebral microvascular endothelia represents a pivotal advancement in the therapeutic strategy for ischemic microcirculatory disturbances. A traditional Chinese medicinal formulation named Shexiang Tongxin Dropping Pills (STDP), has been clinically employed to ameliorate microcirculatory abnormalities. Existing literature attests to the beneficial role of STDP on endothelial cells (ECs). Nevertheless, specific impacts and underlying mechanisms of STDP in rectifying IS-induced cerebral microvascular dysfunction warrant further exploration. Aim of the studyThis investigation seeks to delineate the effects of STDP on cerebral microvascular endothelial damage induced by ischemic stroke and to elucidate the underlying mechanism involved. Materials and methodsMiddle cerebral artery occlusion and reperfusion (MCAO/R) technique was employed to established ischemic stroke model in mice. The therapeutic efficacy of STDP on cerebral microvascular function was assessed through laser speckle contrast imaging, behavioral assays, and histological evaluations. Biochemical markers in the brain tissue, including GSH, SOD, MDA, and ROS, were quantified using specific assay kits. In vitro study, oxygen-glucose deprivation and reperfusion (OGD/R) was performed in bEnd.3 cells. The cytoprotective potential of STDP was then evaluated by measuring cell viability, LDH activity, endothelial permeability, and oxidative stress parameters. Important targets in critical pathway were verified by immunoblotting and immunofluorescence both in mice brain slices and bEnd.3 cells. ResultsSTDP decrease brain infarct size, repaired microvascular cerebral blood flow and attenuated neurological deficiency in MCAO/R mice. Moreover, STDP abolished MCAO/R-induced oxidative stress which was reflected by rescuing GSH content, restoration of SOD activity and T-AOC, reduction of MDA and ROS. Ex vivo, STDP increased cerebral microvascular endothelial cells viability, abolished oxidative stress and decreased their permeability after ODG/R. Mechanistically, STDP significantly suppressed endothelial ROS-TXNIP mediated the activation of NLRP3 inflammasome in vivo and in vitro. ConclusionSTDP improves ischemic stroke-induced cerebral microcirculatory deficits by regulating cerebral microvascular endothelial ROS/TXNIP/NLRP3 signaling pathway.

Natural Fatty Acid Guards against Brain Endothelial Cell Death and Microvascular Pathology following Ischemic Insult in the Presence of Acute Hyperglycemia.

Ischemic stroke is worsened by the presence of sudden high blood sugar levels, even in individuals without pre-existing diabetes. This elevated glucose concentration hampers the ability of energy-starved brain cells to efficiently use it as a source of energy. Consequently, this leads to the production of abundant amounts of toxic glucose metabolites, which trigger oxidative stress in the brain milieu, particularly in the microvasculature of the brain. A prominent feature of this oxidative stress is the demise of endothelial cells, causing detrimental changes in blood vessels, including a reduction in their vascular diameter, a decreased efficiency of vessel proliferation, and the impaired integrity of tight junctions. These vascular pathologies contributed to an increase in the volume of damaged tissues (infarct), an exacerbation of brain swelling (edema), and a decline in cognitive and motor functions. In a mouse model of ischemic stroke with induced acute hyperglycemia, a naturally occurring saturated fatty acid provides protective cover to the microvasculature by preventing damage related to oxidative stress. Our current research revealed that lauric acid (LA) attenuated infarct volume and reduced brain edema by reducing endothelial cell death, enhancing vessels' diameter, promoting vascular angiogenesis, and stabilizing barrier functions. Animals administered with this natural compound showed a significant reduction in 4-HNE-positive vessels. In conclusion, natural saturated fatty acids help to preserve brain microvascular functions following ischemic insults in the presence of acute hyperglycemia.

In situ direct reprogramming of astrocytes to neurons via polypyrimidine tract-binding protein 1 knockdown in a mouse model of ischemic stroke.

JOURNAL/nrgr/04.03/01300535-202410000-00025/figure1/v/2024-02-06T055622Z/r/image-tiff In situ direct reprogramming technology can directly convert endogenous glial cells into functional neurons in vivo for central nervous system repair. Polypyrimidine tract-binding protein 1 (PTB) knockdown has been shown to reprogram astrocytes to functional neurons in situ. In this study, we used AAV-PHP.eB-GFAP-shPTB to knockdown PTB in a mouse model of ischemic stroke induced by endothelin-1, and investigated the effects of GFAP-shPTB-mediated direct reprogramming to neurons. Our results showed that in the mouse model of ischemic stroke, PTB knockdown effectively reprogrammed GFAP-positive cells to neurons in ischemic foci, restored neural tissue structure, reduced inflammatory response, and improved behavioral function. These findings validate the effectiveness of in situ transdifferentiation of astrocytes, and suggest that the approach may be a promising strategy for stroke treatment.

The Photothrombotic Model of Ischemic Stroke.

Stroke is a major cause of morbidity worldwide; yet, there is a lack of treatment options to address post-stroke cognitive and motor impairment, thus there is an urgency for developing neuroprotective and restorative therapies. Much of our fundamental understanding of stroke pathology has been derived from animal models. The photothrombotic model of ischemic stroke is commonly used to study cellular and molecular mechanisms of neurodegeneration, test functional/cognitive outcomes, identify important biomarkers, and assess the effectiveness of novel therapies. It allows for the precise targeting of an infarct to a specific region of the brain, has a low mortality rate, low seizure rate, and is relatively easy to perform. This chapter outlines materials and methods for the photothrombotic model of ischemic stroke in mice, its limitations, and some considerations needed when using this model.

IL-10 protects against OPC ferroptosis by regulating lipid reactive oxygen species levels post stroke

Accumulation of reactive oxygen species (ROS), especially on lipids, induces massive cell death in neurons and oligodendrocyte progenitor cells (OPCs) and causes severe neurologic deficits post stroke. While small compounds, such as deferoxamine, lipostatin-1, and ferrostatin-1, have been shown to be effective in reducing lipid ROS, the mechanisms by which endogenously protective molecules act against lipid ROS accumulation and subsequent cell death are still unclear, especially in OPCs, which are critical for maintaining white matter integrity and improving long-term outcomes after stroke. Here, using mouse primary OPC cultures, we demonstrate that interleukin-10 (IL-10), a cytokine playing roles in reducing neuroinflammation and promoting hematoma clearance, significantly reduced hemorrhage-induced lipid ROS accumulation and subsequent ferroptosis in OPCs. Mechanistically, IL-10 activated the IL-10R/STAT3 signaling pathway and upregulated the DLK1/AMPK/ACC axis. Subsequently, IL-10 reprogrammed lipid metabolism and reduced lipid ROS accumulation. In addition, in an autologous blood injection intracerebral hemorrhagic stroke (ICH) mouse model, deficiency of the endogenous Il-10, specific knocking out Il10r or Dlk1 in OPCs, or administration of ACC inhibitor was associated with increased OPC cell death, demyelination, axonal sprouting, and the cognitive deficits during the chronic phase of ICH and vice versa. These data suggest that IL-10 protects against OPC loss and white matter injury by reducing lipid ROS, supporting further development of potential clinical applications to benefit patients with stroke and related disorders.

A cell-penetrating peptide exerts therapeutic effects against ischemic stroke by mediating the lysosomal degradation of sirtuin 5.

Stroke is a major public health concern worldwide. The lack of effective therapies heightens the need for new therapeutic agents. Previous study identified sirtuin 5 (SIRT5) as a positive regulator of microglia-induced excessive neuroinflammation following ischemic stroke. Interventions targeting SIRT5 should therefore alleviate neuroinflammation and protect against ischemic stroke. Here, we synthesized a membrane-permeable peptide specifically bound to SIRT5 through a chaperone-mediated autophagy targeting motif (Tat-SIRT5-CTM) and examined its therapeutic effect in vitro and in vivo. First, in primary microglia, Tat-SIRT5-CTM suppressed the binding of SIRT5 with annexin-A1 (ANXA1), leading to SIRT5 degradation and thus inhibition of SIRT5-mediated desuccinylation of ANXA1, followed by increased membrane accumulation and secretion of ANXA1. These changes, in turn, alleviated microglia-induced neuroinflammation. Moreover, following intravenous injection, Tat-SIRT5-CTM could efficiently pass through the blood‒brain barrier. Importantly, systemic administration of Tat-SIRT5-CTM reduced the brain infarct area and neuronal loss, mitigated neurological deficit scores, and improved long-term neurological functions in a mouse model of ischemic stroke. Furthermore, no toxicity was observed when high doses Tat-SIRT5-CTM were injected into nonischemic mice. Collectively, our study reveals the promising efficacy of the peptide-directed lysosomal degradation of SIRT5 and suggests it as an effective therapeutic approach for the treatment of ischemic stroke.

Structural changes of CA1 pyramidal neurons after stroke in the contralesional hippocampus.

Significant progress has been made with regard to understanding how the adult brain responds after a stroke. However, a large number of patients continue to suffer lifelong disabilities without adequate treatment. In the present study, we have analyzed possible microanatomical alterations in the contralesional hippocampus from the ischemic stroke mouse model tMCAo 12-14 weeks after transient middle cerebral artery occlusion. After individually injecting Lucifer yellow into pyramidal neurons from the CA1 field of the hippocampus, we performed a detailed three-dimensional analysis of the neuronal complexity, dendritic spine density, and morphology. We found that, in both apical (stratum radiatum) and basal (stratum oriens) arbors, CA1 pyramidal neurons in the contralesional hippocampus of tMCAo mice have a significantly higher neuronal complexity, as well as reduced spine density and alterations in spine volume and spine length. Our results show that when the ipsilateral hippocampus is dramatically damaged, the contralesional hippocampus exhibits several statistically significant selective alterations. However, these alterations are not as significant as expected, which may help to explain the recovery of hippocampal function after stroke. Further anatomical and physiological studies are necessary to better understand the modifications in the "intact" contralesional lesioned brain regions, which are probably fundamental to recover functions after stroke.

O-GlcNAcylation is essential for therapeutic mitochondrial transplantation

BackgroundTransplantation of mitochondria is increasingly explored as a novel therapy in central nervous system (CNS) injury and disease. However, there are limitations in safety and efficacy because mitochondria are vulnerable in extracellular environments and damaged mitochondria can induce unfavorable danger signals.MethodsMitochondrial O-GlcNAc-modification was amplified by recombinant O-GlcNAc transferase (OGT) and UDP-GlcNAc. O-GlcNAcylated mitochondrial proteins were identified by mass spectrometry and the antiglycation ability of O-GlcNAcylated DJ1 was determined by loss-of-function via mutagenesis. Therapeutic efficacy of O-GlcNAcylated mitochondria was assessed in a mouse model of transient focal cerebral ischemia-reperfusion. To explore translational potential, we evaluated O-GlcNAcylated DJ1 in CSF collected from patients with subarachnoid hemorrhagic stroke (SAH).ResultsWe show that isolated mitochondria are susceptible to advanced glycation end product (AGE) modification, and these glycated mitochondria induce the receptor for advanced glycation end product (RAGE)-mediated autophagy and oxidative stress when transferred into neurons. However, modifying mitochondria with O-GlcNAcylation counteracts glycation, diminishes RAGE-mediated effects, and improves viability of mitochondria recipient neurons. In a mouse model of stroke, treatment with extracellular mitochondria modified by O-GlcNAcylation reduces neuronal injury and improves neurologic deficits. In cerebrospinal fluid (CSF) samples from SAH patients, levels of O-GlcNAcylation in extracellular mitochondria correlate with better clinical outcomes.ConclusionsThese findings suggest that AGE-modification in extracellular mitochondria may induce danger signals, but O-GlcNAcylation can prevent glycation and improve the therapeutic efficacy of transplanted mitochondria in the CNS.

Heat stress suppresses MnSOD expression via p53-Sp1 interaction and induces oxidative stress damage in endothelial cells: Protective effects of MitoQ10 and Pifithrin-α

AimTo investigate the mechanism of p53-mediated suppression of heat stress-induced oxidative stress damage by manganese superoxide dismutase (MnSOD) in endothelial cells (ECs). MethodsPrimary ECs isolated from mouse aortas were used to examine the effects of heat stress on vascular ECs viability and apoptosis. We measured MnSOD expression, reactive oxygen species (ROS) production, p53 expression, viability, and apoptosis of heat stress-induced ECs. We also tested the protective effects of MitoQ10, a mitochondrial-targeted antioxidant, and Pifithrin-α, a p53 inhibitor, in ECs from a mouse model of heat stroke. ResultsHeat stress increased cellular apoptosis, ROS production, and p53 expression, while reducing cellular viability and MnSOD expression in ECs. We also showed that the suppression of MnSOD expression by heat stress in ECs was mediated by interactions between p53 and Sp1. Furthermore, MitoQ10 and Pifithrin-α alleviated heat stress-induced oxidative stress and apoptosis in ECs. ConclusionOur results revealed that p53-mediated MnSOD downregulation is a key mechanism for heat stress-induced oxidative stress damage in ECs and indicated that MitoQ10 and Pifithrin-α could be potential therapeutic agents for heat stroke.

CNSC-41. DOES ISCHEMIC STROKE DRIVE BRAIN TUMOR PROGRESSION?

Abstract Glioblastoma multiforme is the most common and lethal primary brain tumor, with a 5-year survival rate of less than 5%. Its complex pathophysiology, highlighted by massive inflammatory responses, enhances tumor progression and impedes therapeutic interventions, leading to its dismal prognosis. Inflammatory responses are also a cardinal feature of brain injury and remarkably, clinical evidence from large-scale patient cohort studies indicates a link between glioma and cerebral ischemic stroke, where approximately 10% of ischemic stroke patients develop glioma. This observation suggests that brain injury may be a risk factor for the development of brain tumors; however, whether and how stroke occurrence promotes brain tumor progression is unknown. To address this knowledge gap, we employed a photothrombotic stroke mouse model in conjunction with established glioma models. In these models, we observed a significant increase in tumor cell proliferation and infiltration towards the infarct region and blood-brain barrier disruption. Intriguingly, spatial transcriptomic analysis in stroke-glioma models highlighted altered pH regulation in the microenvironment at the leading edge of tumor cells near stroke lesions. Further analysis revealed that the astrocytic pH regulator, Slc4a4, is significantly downregulated in the infiltrating tumor cells near infarct lesions, and that Slc4a4 inhibits tumor progression in our glioma models. Based on patient cohort studies that link glioma occurrence with cerebral ischemia and our new mouse model results, our data demonstrates that exposure to cortical ischemia-induced-hypoxia during tumorigenesis, promotes malignant glioma progression by altering the brain microenvironment via pH modulation. These conceptually innovative studies will integrate our new stroke-glioma models and advanced methodologies to investigate the stroke-glioma interaction via hypoxia and pH modulation, potentially identifying new therapy targets.

Abstract 15651: Astrocytic Chordin-Like 1 Regulates AMPAR Synaptic Content and Motor Recovery in a Mouse Model of Ischemic Stroke

Introduction: Ischemic stroke triggers a series of molecular events that impairs receptor levels at excitatory synapses. AMPA receptors (AMPARs), the main excitatory receptors in the mammalian brain, are crucial in maintaining proper brain function. In response to ischemic stroke, their subunit composition and location at the synapse are deeply altered and trigger apoptotic cell death cascades. We previously found that Chordin-like 1 (Chrdl1), an astrocyte-derived protein that regulates AMPARs, is highly upregulated in the peri-infarct region at early stages after stroke (1 and 7 days post-stroke, dps). When Chrdl1 was absent, neurons were protected from stroke-induced structural degeneration. Hypothesis: Elimination of Chrdl1 prevents stroke-induced aberrant AMPAR synaptic levels, limits AMPAR-mediated apoptotic cascades and alleviates behavioral deficits. Methods: We used photothrombosis to model ischemic stroke in the motor cortex of adult male and female WT and Chrdl1 KO mice and performed analyses at 1 and 7 dps in the peri-infarct area. We used fluorescent in situ hybridization to analyze mRNA levels of Chrdl1, immunohistochemistry to determine synaptic AMPAR levels and subunit composition, TUNEL to determine apoptotic cell death, MRI to monitor the progression of injury volume, and adhesive removal and grid walk tests to assess sensorimotor and motor behaviors. Results: WT mice, after photothrombotic injury showed important impairments in the AMPAR synaptic distribution and composition. This aberrant AMPAR subunit composition and location at synapses was abolished in Chrdl1 KO mice. This resulted in reduced apoptotic cell death and faster motor recovery in Chrdl1 KO mice compared to WT in both male and female mice. Conclusions: This study shows that targeting Chrdl1 has therapeutic potential to reduce apoptotic cell death and aid motor recovery after ischemic stroke via synaptic regulation of AMPARs. Astrocyte-derived proteins, such as Chrdl1, may represent new molecular targets that can restore synapses to favor functional recovery after ischemic stroke.

Conditioned Medium Derived From the Human Amniotic Membrane Prevents Brain Damage Against Cerebral Ischemia/Reperfusion in Subacute, Acute, and Chronic Phases in a Rat Model of Stroke.

Stem cells isolated from the amniotic membrane can produce and release substances that can regenerate damaged tissues and contain proteins and other factors that via numerous major and minor mechanisms lead to increasing angiogenesis and tissue survival. This research was conducted to prove the defensive characteristics of the secretome in the face of temporary focal cerebral ischemia in mouse stroke models. Cerebral ischemia protocol in a specific area was implemented in rats with middle cerebral artery occlusion for 60 minutes and then reperfusion was given for 6, 20, and 30 minutes. Within 30 minutes after the start of reperfusion, conditioned medium derived from the human amniotic membrane (AMSC-CM) was poured into the right ventricle (ICV) at a dose of 0.5 μL. Finally, the volume of the injury, cerebral tissue water, sensorimotor activity, and the strength of the blood-brain barrier integrity were evaluated 24 hours after drug injection. ICV injection of conditioned medium at the start of reperfusion phase considerably decreased the volume of the injury 6, 20, and 30 hours after reperfusion compared to the MCAO-operated group (P<0.01). Cerebral tissue water in the treatment group decreased considerably after the intervention in comparison with the MCAO group in the core and penumbral area not in the subcortical area (P<0.05). Also, the amount of Evans blue infiltration at all times in the core and half-foot area in the AMSC-CM group was significantly reduced in parallel with the MCAO group (P<0.05). Treatment with AMSC-CM during 6-30 h after ischemia-reperfusion insult exerts some beneficial effects against ischemia-reperfusion injury. These findings provide an important vision for more complementary research and treatment of stroke. During ischemia, the brain undergoes a series of harmful pathological events.Mesenchymal stem cells culture medium is called condition medium (CM).CM contains substances that have neuroprotective properties.The use of CM reduces the damage caused by cerebral ischemia. The stem cell culture medium is called condition medium (CM). CM contains substances that have neuroprotective properties. This study aims to investigate the effect of CM on injuries caused by stroke. After causing a stroke in rats by closing the artery, the CM was injected into the injury site. The results showed that CM reduced the severity of the injury.

Immune pathway activation in neurons triggers neural damage after stroke

Ischemic brain injury is a severe medical condition with high incidences in elderly people without effective treatment for the resulting neural damages. Using a unilateral mouse stroke model, we analyze single-cell transcriptomes of ipsilateral and contralateral cortical penumbra regions to objectively reveal molecular events with single-cell resolution at 4h and 1, 3, and 7days post-injury. Here, we report that neurons are among the first cells that sense the lack of blood supplies by elevated expression of CCAAT/enhancer-binding protein β (C/EBPβ). To our surprise, the canonical inflammatory cytokine gene targets for C/EBPβ, including interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α), are subsequently induced also in neuronal cells. Neuronal-specific silencing of C/EBPβ or IL-1β and TNF-α substantially alleviates downstream inflammatory injury responses and is profoundly neural protective. Taken together, our findings reveal a neuronal inflammatory mechanism underlying early pathological triggers of ischemic brain injury.

Targeting Pro-Oxidant Iron with Exogenously Administered Apotransferrin Provides Benefits Associated with Changes in Crucial Cellular Iron Gate Protein TfR in a Model of Intracerebral Hemorrhagic Stroke in Mice.

We have previously demonstrated that the post-stroke administration of iron-free transferrin (apotransferrin, ATf) is beneficial in different models of ischemic stroke (IS) through the inhibition of the neuronal uptake of pro-oxidant iron. In the present study, we asked whether ATf is safe and also beneficial when given after the induction of intracerebral hemorrhage (ICH) in mice, and investigated the underlying mechanisms. We first compared the main iron actors in the brain of IS- or collagenase-induced ICH mice and then obtained insight into these iron-related proteins in ICH 72 h after the administration of ATf. The infarct size of the IS mice was double that of hemorrhage in ICH mice, but both groups showed similar body weight loss, edema, and increased ferritin and transferrin levels in the ipsilateral brain hemisphere. Although the administration of human ATf (hATf) to ICH mice did not alter the hemorrhage volume or levels of the classical ferroptosis GPX4/system xc- pathways, hATf induced better neurobehavioral performance, decreased 4-hydroxynonenal levels and those of the second-generation ferroptosis marker transferrin receptor (TfR), and restored the mRNA levels of the recently recognized cytosolic iron chaperone poly(RC) binding protein 2. In addition, hATf treatment lowered the ICH-induced increase in both endogenous mouse transferrin mRNA levels and the activation of caspase-2. In conclusion, hATf treatment provides neurobehavioral benefits post-ICH associated with the modulation of iron/oxidative players.

Subventricular zone cytogenesis provides trophic support for neural repair in a mouse model of stroke

Stroke enhances proliferation of neural precursor cells within the subventricular zone (SVZ) and induces ectopic migration of newborn cells towards the site of injury. Here, we characterize the identity of cells arising from the SVZ after stroke and uncover a mechanism through which they facilitate neural repair and functional recovery. With genetic lineage tracing, we show that SVZ-derived cells that migrate towards cortical photothrombotic stroke in mice are predominantly undifferentiated precursors. We find that ablation of neural precursor cells or conditional knockout of VEGF impairs neuronal and vascular reparative responses and worsens recovery. Replacement of VEGF is sufficient to induce neural repair and recovery. We also provide evidence that CXCL12 from peri-infarct vasculature signals to CXCR4-expressing cells arising from the SVZ to direct their ectopic migration. These results support a model in which vasculature surrounding the site of injury attracts cells from the SVZ, and these cells subsequently provide trophic support that drives neural repair and recovery.

Direct neuronal conversion of microglia/macrophages reinstates neurological function after stroke

Although generating new neurons in the ischemic injured brain would be an ideal approach to replenish the lost neurons for repairing the damage, the adult mammalian brain retains only limited neurogenic capability. Here, we show that direct conversion of microglia/macrophages into neurons in the brain has great potential as a therapeutic strategy for ischemic brain injury. After transient middle cerebral artery occlusion in adult mice, microglia/macrophages converge at the lesion core of the striatum, where neuronal loss is prominent. Targeted expression of a neurogenic transcription factor, NeuroD1, in microglia/macrophages in the injured striatum enables their conversion into induced neuronal cells that functionally integrate into the existing neuronal circuits. Furthermore, NeuroD1-mediated induced neuronal cell generation significantly improves neurological function in the mouse stroke model, and ablation of these cells abolishes the gained functional recovery. Our findings thus demonstrate that neuronal conversion contributes directly to functional recovery after stroke.

Delayed metabolic disturbances in the myocardium after exertional heat stroke: contrasting effects of exertion and thermal load.

Epidemiological studies report higher risks of cardiovascular disease in humans exposed to heat stroke earlier in life. Previously, we explored mechanistic links between heat stroke and developing cardiac abnormalities using a preclinical mouse model of exertional heat stroke (EHS). Profound metabolic abnormalities developed in the ventricles of females but not males after 2 wk of recovery. Here we tested whether this lack of response in males could be attributed to the lower exercise performances or reduced thermal loads they experienced with the same running protocol. We systematically altered environmental temperature (Te) during EHS to manipulate heat exposure and exercise performance in the males. Three groups of adult C57BL/6 male mice were studied: "EHS-34" (Te = 34°C), "EHS-41" (Te = 41°C), and "EHS-39.5" (Te = 39.5°C). Mice ran until symptom limitation (unconsciousness), reaching max core temperature (Tc,max). After a 2-wk recovery, the mice were euthanized, and the ventricles were removed for untargeted metabolomics. Results were compared against age-matched nonexercise controls. The EHS-34 mice greatly elevated their exercise performance but reached lower Tc,max and lower thermal loads. The EHS-41 mice exhibited equivalent thermal loads, exercise times, and Tc,max compared with EHS-39.5. The ventricles from EHS-34 mice exhibited the greatest metabolic disturbances in the heart, characterized by shifts toward glucose metabolism, reductions in acylcarnitines, increased amino acid metabolites, elevations in antioxidants, altered TCA cycle flux, and increased xenobiotics. In conclusion, delayed metabolic disturbances following EHS in male myocardium appear to be greatly amplified by higher levels of exertion in the heat, even with lower thermal loads and max core temperatures.NEW & NOTEWORTHY Epidemiological data demonstrate greater cardiovascular risk in patients with previous heat stroke exposure. Using a preclinical mouse model of exertional heat stroke, male mice were exposed to one of three environmental temperatures (Te) during exercise. Paradoxically, after 2 wk, the mice in the lowest Te, exhibiting the largest exercise response and lowest heat load, had the greatest ventricular metabolic disturbances. Metabolic outcomes resemble developing left ventricular hypertrophy or stress-induced heart disease.