White Matter Lesions and Glial Activation in a Novel Mouse Model of Chronic Cerebral Hypoperfusion

Beraprost sodium ameliorates cognitive impairment by promoting oligodendrocyte precursor cell proliferation and differentiation in vascular cognitive impairment mouse model

Chronic cerebral hypoperfusion (CCH) leads to white matter injury (WMI), a key contributor to the development of vascular cognitive impairment (VCI). Beraprost sodium (BPS) is a chemically stable and orally active prostaglandin I2 (PGI2) analog, while the role and mechanism of BPS in VCI have not been well understood. In this study, we used a mouse model of bilateral carotid artery stenosis (BCAS mice) and demonstrated that BPS treatment facilitated the proliferation and differentiation of oligodendrocyte precursor cells (OPCs), potentially via PDGFR-α pathway modulation. This intervention promoted remyelination and attenuated WMI and cognitive dysfunction in BCAS mice. Collectively, our results suggested that BPS mitigates chronic ischemic WMI by targeting OPC development, providing a potential therapeutic avenue for VCI.

Toll-Like Receptor 4-Mediated Neuroinflammation: Updates on Pathological Roles and Therapeutic Strategies in Chronic Cerebral Hypoperfusion

Neuroinflammation has been acknowledged as being one of the main pathologies that occur following chronic cerebral hypoperfusion (CCH). Since it significantly contributes to neuronal cell damage and thereby leads to cognitive impairment, the signals related to inflammation in hypoperfusion injury have been extensively investigated over the past few years. Toll-like receptor 4 (TLR4) is the key receptor responsible for immune and inflammatory reactions. It has been reported that TLR4 is involved in the pathology of several diseases and has emerged as a therapeutic target for developing a variety of anti-inflammatory compounds. This study explored the pathological roles of TLR4 that potentially cause the promotion of neuroinflammation in CCH damage. The evidence pertinent to the activation of TLR4 and its downstream inflammatory cascades following CCH are also summarized. This study also demonstrated the therapeutic potential of TLR4 inhibition, whether through drugs, substances, or other treatment strategies, in models of CCH-induced neurological dysfunction. The limitations of the accumulated evidence are addressed and discussed in this study. A deeper understanding of the roles of TLR4 in neuroinflammation following CCH damage may help inform the machinery behind pathological processes for advancing further neuroscientific research and developing therapeutic strategies for vascular dementia.

Experimental Ischemic Stroke Induces Secondary Bihemispheric White Matter Degeneration and Long-Term Cognitive Impairment

Clinical studies have identified widespread white matter degeneration in ischemic stroke patients. However, contemporary research in stroke has predominately focused on the infarct and periinfarct penumbra regions. The involvement of white matter degeneration after ischemic stroke and its contribution to post-stroke cognitive impairment and dementia (PSCID) has remained less explored in experimental models. In this study, we examined the progression of locomotor and cognitive function up to 4 months after inducing ischemic stroke by middle cerebral artery occlusion in young adult rats. Despite evident ongoing locomotor recovery, long-term cognitive and affective impairments persisted after ischemic stroke, as indicated by Morris water maze, elevated plus maze, and open field performance. At 4 months after stroke, multimodal MRI was conducted to assess white matter degeneration. T2-weighted MRI (T2WI) unveiled bilateral cerebroventricular enlargement after ischemic stroke. Fluid Attenuated Inversion Recovery MRI (FLAIR) revealed white matter hyperintensities in the corpus callosum and fornix across bilateral hemispheres. A positive association between the volume of white matter hyperintensities and total cerebroventricular volume was noted in stroke rats. Further evidence of bilateral white matter degeneration was indicated by the reduction of fractional anisotropy and quantitative anisotropy at bilateral corpus callosum in diffusion-weighted MRI (DWI) analysis. Additionally, microglia and astrocyte activation were identified in the bilateral corpus callosum after stroke. Our study suggests that experimental ischemic stroke induced by MCAO in young rat replicate long-term cognitive impairment and bihemispheric white matter degeneration observed in ischemic stroke patients. This model provides an invaluable tool for unraveling the mechanisms underlying post-stroke secondary white matter degeneration and its contribution to PSCID.

Multilineage-differentiating stress-enduring cells attenuate the cognitive impairment caused by chronic cerebral hypoperfusion in rats

Multilineage-differentiating stress-enduring (Muse) cells are non-tumorigenic pluripotent- like stem cells that can migrate to damaged sites and contribute to tissue repair. Chronic cerebral hypoperfusion (CCH), which mimics vascular dementia, causes hippocampal neuronal degeneration and white matter (WM) damage, which lead to cognitive dysfunction. Currently, there are no effective treatments for it. We evaluated the efficiency of the human-Muse cell-based product CL2020 in treating CCH in rats. A bilateral common carotid artery occlusion was used to induce cognitive dysfunction. Six-weeks after carotid artery occlusion, CL2020 were injected intravenously. Cognitive function was assessed using a Barnes circular maze (BCM) at 3 weeks after CL2020 administration. Histological findings and western blots were assessed at 4 weeks after CL2020 administration. BCM assessment indicated recovery in cognitive function in the CL2020-treated group. Compared with the vehicle, CL2020 targeted the hippocampus, where it decreased neuronal loss and WM damage. CL2020 also promoted angiogenesis and suppressed apoptotic cell death. Western blotting of hippocampal samples revealed the downregulation of pro- apoptotic and the upregulation of anti-apoptotic proteins in the CL2020-treated group. In conclusion, intravenous administration of CL2020 improved the cognitive deficits caused by CCH, partly because of decreased hippocampal neuronal loss and WM damage, and increased angiogenesis in the hippocampus.

Lipocalin 2 Facilitates the Initial Compromise of the Blood-Brain Barrier Integrity in Chronic Cerebral Hypoperfusion

AIMS

Vascular cognitive impairment (VCI) is primarily attributed to vascular risk factors and cerebrovascular disease. Chronic cerebral hypoperfusion (CCH) initiates in the early stages of VCI and contributes to blood-brain barrier (BBB) disruption. Nevertheless, the precise molecular mechanisms underlying this process remain elusive and warrant further investigation.

METHODS

The Bilateral Carotid Artery Stenosis (BCAS) model was employed to simulate CCH, and the permeability of the BBB in the mouse frontal cortex was assessed at various time points post-operation. Transcriptome sequencing was conducted to identify differentially expressed genes (DEGs), which were then intersected with cortical gene chip data from human vascular dementia cases. Key genes identified through this analysis were subsequently measured in the serum of VCI patients and correlated with cognitive performance scores. Additionally, in vivo experiments were conducted to validate the influence of these key genes on BBB endothelial-mesenchymal transition (EndMT) and peripheral neutrophil infiltration.

RESULTS

Time-course studies investigating BBB disruption revealed an increase in BBB permeability in the frontal cortex of mice on day 14 following BCAS, a stage at which the mice had not yet exhibited cognitive impairment. Subsequent sequencing analyses, integrated with human cortical gene expression profiles, identified Lipocalin 2 (LCN2) as a pivotal gene involved in mediating inflammatory responses and cell migration. Clinical studies have demonstrated that LCN2 is upregulated in the serum of patients with VCI and exhibits a significant negative correlation with Montreal Cognitive Assessment (MOCA) scores. Downregulation of LCN2 leads to a reduction in EndMT markers and peripheral neutrophil infiltration, as well as significant enhancements in learning and memory in BCAS mice through modulation of the MEK/ERK signaling pathway.

CONCLUSION

This study elucidates the temporal characteristics and key molecular mechanisms underlying BBB disruption in the frontal cortex during CCH, thereby identifying novel potential targets for the early diagnosis and treatment of VCI.

Efficacy of Human-Induced Pluripotent Stem Cell-Derived Neural Progenitor Cell Replacement Therapy in a Vascular Dementia Animal Model

BACKGROUND

Cell replacement therapy is the only treatment that restores or repairs the function of impaired tissues in neurodegenerative diseases, including vascular dementia (VaD); however, current VaD treatments focus on slowing or mitigating the underlying small vessel disease progression. We aimed to verify the improvement in neurocognition after administering human-induced pluripotent stem cell (hiPSC)-derived neural progenitor cells (NPCs) from in a VaD animal model.

METHODS

After anesthesia, 10-12-week-old male C5BL/6 mice underwent sham or bilateral carotid artery stenosis (BCAS) surgeries. For BCAS, 0.18-mm micro-coils were wound around the bilateral common carotid arteries to induce chronic vascular insufficiency in the global brain. One day after surgery, the mice were administered phosphate buffer solution or NPC from hiPSCs via the tail vein for 15 d, and divided into sham (n = 6), VEH (n = 6), and NPC (n = 7) groups. Three months after the surgery, neurobehavioral tests including the Y-maze test (YMT), passive avoidance test (PAT), and novel object recognition test (NORT) were performed. Finally, mice brains were sectioned for evaluating microglia (Iba-1), astrocyte (GFAP) activation, and myelin (MBP) degeneration through immunohistochemistry (IHC).

RESULTS

PAT latency (p = 0.01) and discrimination index in the NORT (p = 0.043) increased considerably in the NPC group than in the VEH group. However, alterations in YMT were not considerably higher in the NPC group than in the VEH group (p = 0.65). IHC tests revealed that the GFAP- and IBA-1-positive cell number was remarkably lower in the NPC group than in the VEH group (p < 0.05). Moreover, MBP density was higher in the NPC group.

CONCLUSION

hiPSC-derived NPCs have therapeutic potential in cerebral hypoperfusion VaD mice; it improves the working memory of VaD animals by diminishing inflammatory reactions and protecting them from demyelination.

Oxidative stress and chronic cerebral hypoperfusion: An overview from preclinical rodent models

Chronic cerebral hypoperfusion (CCH) is an important clinical condition characterized by a prolonged reduction in cerebral blood flow that contributes to several neurodegenerative diseases, including vascular dementia and Alzheimer's disease. A number of rodent models of CCH have been developed that mimic the human pathological conditions of reduced cerebral perfusion. These models have been instrumental in elucidating the molecular and cellular mechanisms involved in CCH-induced brain damage. Oxidative stress is induced by perturbations in cellular pathways caused by CCH, including mitochondrial dysfunction, ion pump dysfunction, and adenosine triphosphate (ATP) depletion. The deleterious stress leads to the accumulation of reactive oxygen species (ROS) and exacerbates damage to neuronal structures, significantly impairing cognitive function. Among the various therapeutic strategies being evaluated, edaravone, a potent antioxidant, is emerging as a promising drug due to its neuroprotective properties against oxidative stress. Initially approved for use in ischemic stroke, research using rodent CCH models has shown that edaravone has significant efficacy in scavenging free radicals and ameliorating oxidative stress-induced neuronal damage under CCH conditions. This mini-review summarizes the current literature on the rodent models of CCH and then discusses the therapeutic potential of edaravone to reduce neuronal and vascular damage caused by CCH-induced oxidative stress.

Anti-RGMa neutralizing antibody ameliorates vascular cognitive impairment in mice

Repulsive Guidance Molecule A (RGMa) is well-recognized for its role in axon guidance. Recent studies have unveiled its diverse functions under pathological conditions within the central nervous system, such as spinal cord injury, multiple sclerosis, and Parkinson's disease. In this study, we explored the involvement of RGMa and the therapeutic effects of an anti-RGMa neutralizing antibody in a mouse model of vascular dementia (VaD). The VaD mouse model was established using the bilateral common carotid artery stenosis (BCAS) method. Immunohistochemical analysis revealed that these mice exhibited increased RGMa expression in the hippocampus, which coincided with reduced neurogenesis and impaired cholinergic innervation. These alterations manifested as cognitive impairments in the BCAS mice. Significantly, treatment with anti-RGMa neutralizing antibody reversed these pathological changes and cognitive deficits. Our findings suggest that RGMa plays a pivotal role in VaD pathology within the hippocampus and propose the anti-RGMa antibody as a promising therapeutic avenue for treating VaD.

Glial 'omics in ischemia: Acute stroke and chronic cerebral small vessel disease

Vascular injury and pathologies underlie common diseases including ischemic stroke and cerebral small vessel disease (CSVD). Prior work has identified a key role for glial cells, including microglia, in the multifaceted and temporally evolving neuroimmune response to both stroke and CSVD. Transcriptional profiling has led to important advances including identification of distinct gene expression signatures in ischemia-exposed, flow cytometrically sorted microglia and more recently single cell RNA sequencing-identified microglial subpopulations or clusters. There is a reassuring degree of overlap in the results from these two distinct methodologies with both identifying a proliferative and a separate type I interferon responsive microglial element. Similar patterns were later seen using multimodal and spatial transcriptomal profiling in ischemia-exposed microglia and astrocytes. Methodological advances including enrichment of specific neuroanatomic/functional regions (such as the neurovascular unit) prior to single cell RNA sequencing has led to identification of novel cellular subtypes and generation of new credible hypotheses as to cellular function based on the enhanced cell sub-type specific gene expression patterns. A ribosomal tagging strategy focusing on the cellular translatome analyses carried out in the acute phases post stroke has revealed distinct inflammation-regulating roles for microglia and astrocytes in this setting. Early spatial transcriptomics experiments using cerebral ischemia models have identified regionally distinct microglial cell clusters in ischemic core versus penumbra. There is great potential for combination of these methods for multi-omics approaches to further elucidate glial responses in the context of both acute ischemic stroke and chronic CSVD.

Integrated analysis of chromatin and transcriptomic profiling of the striatum after cerebral hypoperfusion in mice

BACKGROUND

Vascular cognitive impairment (VCI) is a significant contributor to dementia, yet the precise mechanisms underlying the cognitive decline associated with chronic cerebral hypoperfusion (CCH) remain unclear. This study investigated the molecular and epigenetic changes in the striatum, a brain region critical for motor function and cognition, following chronic hypoperfusion using a bilateral common carotid artery stenosis (BCAS) model in mice.

METHODS

RNA-seq was utilized to identify differentially expressed genes (DEGs) associated with hypoperfusion. In parallel, ATAC-seq was used to assess changes in chromatin accessibility within the striatum, providing insight into the epigenome and potential regulatory mechanisms. The integration of these datasets allowed us to correlate chromatin accessibility with transcriptional activity and to identify key transcription factors driving the observed gene expression changes.

RESULTS

Analysis of striatum-specific transcriptome revealed significant upregulation of immune response genes, particularly type II interferon signaling, and downregulation of neural activation pathways. Analysis of striatum-specific epigenome showed increased chromatin accessibility at promoters of immune-related genes. Integrated analysis highlighted PU.1 as a key transcription factor in upregulated pathways, while neural pathways lacked epigenetic regulation, revealing distinct molecular responses in the striatum following chronic hypoperfusion.

CONCLUSIONS

Our findings indicate that upregulated pathways in the striatum following BCAS-induced CCH are driven by epigenetic changes, while downregulated pathways occur independently of these modifications. Additionally, PU.1 plays a critical role in mediating immune responses, offering a potential target for therapeutic intervention.

Early functional and structural hippocampal impairment in a bilateral common carotid artery stenosis mouse model

BACKGROUND

Subcortical ischemic vascular dementia (SIVD) is a common subtype of vascular dementia. Currently, the bilateral common carotid artery stenosis (BCAS) mouse model is the most suitable SIVD rodent model. In this study, we investigated the functional and structural impairments in the hippocampus 1 month after BCAS.

METHODS

We used behavioral tests, laser speckle flowmetry, long-term potentiation, histochemical staining, molecular experiments, and voxel-based morphometry to evaluate the hippocampal impairments.

RESULTS

Behavioral studies revealed that BCAS mice exhibited worse performance. Laser speckle flowmetry detected an obvious decrease in cerebral blood flow. The synaptic plasticity of the perforant path-dentate gyrus pathway was inhibited. Decreased fractional anisotropy and increased mean diffusivity were detected in the hippocampus via diffusion tensor imaging data. A reduction in gray matter volume, which was most prominent in the hippocampus and its surrounding areas, was detected via voxel-based morphometry analysis. Impairments in cell morphology and myelin integrity were validated using histochemical staining and molecular biology techniques. In addition, the numbers of GFAP+ astrocytes and Iba1+ microglia increased in the hippocampus.

CONCLUSIONS

Overall, our study demonstrates early functional and structural impairments in the hippocampus contributing to learning and memory deficits after 1 month of BCAS, indicating that the hippocampus is vulnerable to chronic cerebral ischemia.

Cerebral hypoperfusion reduces tau accumulation

OBJECTIVE

Alzheimer's disease (AD) often coexists with cerebrovascular diseases. However, the impact of cerebrovascular diseases such as stroke on AD pathology remains poorly understood.

METHODS

This study examines the correlation between cerebrovascular diseases and AD pathology. The research was carried out using clinical and neuropathological data collected from the National Alzheimer's Coordinating Center (NACC) database and an animal model in which bilateral common carotid artery stenosis surgery was performed, following the injection of tau seeds into the brains of wild-type mice.

RESULTS

Analysis of the NACC database suggests that clinical stroke history and lacunar infarcts are associated with lower neurofibrillary tangle pathology. An animal model demonstrates that chronic cerebral hypoperfusion reduces tau pathology, which was observed in not only neurons but also astrocytes, microglia, and oligodendrocytes. Furthermore, we found that astrocytes and microglia were activated in response to tau pathology and chronic cerebral hypoperfusion. Additionally, cerebral hypoperfusion increased a lysosomal enzyme, cathepsin D.

INTERPRETATION

These data together indicate that cerebral hypoperfusion reduces tau accumulation likely through an increase in microglial phagocytic activity towards tau and an elevation in degradation through cathepsin D. This study contributes to understanding the relationship between tau pathology and cerebrovascular diseases in older people with multimorbidity.

Spiral volumetric optoacoustic tomography of reduced oxygen saturation in the spinal cord of M83 mouse model of Parkinson's disease

PURPOSE

Metabolism and bioenergetics in the central nervous system play important roles in the pathophysiology of Parkinson's disease (PD). Here, we employed a multimodal imaging approach to assess oxygenation changes in the spinal cord of the transgenic M83 murine model of PD overexpressing the mutated A53T alpha-synuclein form in comparison with non-transgenic littermates.

METHODS

In vivo spiral volumetric optoacoustic tomography (SVOT) was performed to assess oxygen saturation (sO2) in the spinal cords of M83 mice and non-transgenic littermates. Ex vivo high-field T1-weighted (T1w) magnetic resonance imaging (MRI) at 9.4T was used to assess volumetric alterations in the spinal cord. 3D SVOT analysis and deep learning-based automatic segmentation of T1w MRI data for the mouse spinal cord were developed for quantification. Immunostaining for phosphorylated alpha-synuclein (pS129 α-syn), as well as vascular organization (CD31 and GLUT1), was performed after MRI scan.

RESULTS

In vivo SVOT imaging revealed a lower sO2SVOT in the spinal cord of M83 mice compared to non-transgenic littermates at sub-100 μm spatial resolution. Ex vivo MRI-assisted by in-house developed deep learning-based automatic segmentation (validated by manual analysis) revealed no volumetric atrophy in the spinal cord of M83 mice compared to non-transgenic littermates at 50 μm spatial resolution. The vascular network was not impaired in the spinal cord of M83 mice in the presence of pS129 α-syn accumulation.

CONCLUSION

We developed tools for deep-learning-based analysis for the segmentation of mouse spinal cord structural MRI data, and volumetric analysis of sO2SVOT data. We demonstrated non-invasive high-resolution imaging of reduced sO2SVOT in the absence of volumetric structural changes in the spinal cord of PD M83 mouse model.

[Animal experimental models in the study of age-dependent cerebral microangiopathy]

The modeling of age-dependent cerebral microangiopathy (CMA) is highly relevant due to its high prevalence and the heavy burden of clinical manifestations - strokes and cognitive disorders in the elderly, as well as the lack of effective pathogenetic treatment. Experimental modeling of CMA is a promising area of preclinical scientific research that contributes to the study of the disease pathogenesis at the genetic, molecular, and cellular levels and the search for optimal methods of its treatment and prevention. This review aimed to analyze, systematize, and compare data on current experimental models of CMA. The review analyzed the results of various studies on experimental models published in journals indexed in the PubMed, Scopus, and eLibrary databases. Available CMA models reflect different CMA attributes and mechanisms. The choice of research model should be based on the experiment's objectives. Understanding available models, combining them, and developing new models should be aimed at choosing the most relevant ones, reproducing the features of modern CMA, characterized by the control of classical risk factors, to assess pathological mechanisms and develop pathogenetic treatment.

Single-nucleus RNA sequencing of human periventricular white matter in vascular dementia

Vascular dementia (VaD) refers to a variety of dementias driven by cerebrovascular disease and is the second leading cause of dementia globally. VaD may be caused by ischemic strokes, intracerebral hemorrhage, and/or cerebral small vessel disease, commonly identified as white matter hyperintensities on MRI. The mechanisms underlying these white matter lesions in the periventricular brain are poorly understood. In this study we perform an extensive transcriptomic analysis on human postmortem periventricular white matter lesions in patients with VaD with the goal of identifying molecular pathways in the disease. We find increased cellular stress responses in astrocytes, oligodendrocytes, and oligodendrocyte precursor cells as well as transcriptional and translational repression in microglia in our dataset. We show that several genes identified by GWAS as being associated with white matter disease are differentially expressed in cells in VaD. Finally, we compare our dataset to an independent snRNAseq dataset of PVWM in VaD and a scRNAseq dataset on human iPSC-derived microglia exposed to oxygen glucose deprivation (OGD). We identify the increase of the heat shock protein response as a conserved feature of VaD across celltypes and show that this increase is not linked to OGD exposure. Overall, our study is the first to show that increased heat shock protein responses are a common feature of lesioned PVWM in VaD and may represent a potential therapeutic target.

A rat model of cerebral small vascular disease induced by ultrasound and protoporphyrin

Cerebral small vascular disease (CSVD) has a high incidence worldwide, but its pathological mechanisms remain poorly understood due to the lack of proper animal models. The current animal models of CSVD have several limitations such as high mortality rates and large-sized lesions, and thus it is urgent to develop new animal models of CSVD. Ultrasound can activate protoporphyrin to produce reactive oxygen species in a liquid environment. Here we delivered protoporphyrin into cerebral small vessels of rat brain through polystyrene microspheres with a diameter of 15 μm, and then performed transcranial ultrasound stimulation (TUS) on the model rats. We found that TUS did not affect the large vessels or cause large infarctions in the brain of model rats. The mortality rates were also comparable between the sham and model rats. Strikingly, TUS induced several CSVD-like phenotypes such as cerebral microinfarction, white matter injuries and impaired integrity of endothelial cells in the model rats. Additionally, these effects could be alleviated by antioxidant treatment with N-acetylcysteine (NAC). As control experiments, TUS did not lead to cerebral microinfarction in the rat brain when injected with the polystyrene microspheres not conjugated with protoporphyrin. In sum, we generated a rat model of CSVD that may be useful for the mechanistic study and drug development for CSVD.

Theta-burst transcranial magnetic stimulation attenuates chronic ischemic demyelination and vascular cognitive impairment in mice

Vascular cognitive impairment and dementia (VCID) is mainly caused by chronic cerebral hypoperfusion and subsequent white matter lesions. Noninvasive transcranial magnetic stimulation has been utilized in treating various neurological disorders. However, the function of theta-burst transcranial magnetic stimulation on VCID remains to be defined. We utilized 4-week bilateral carotid artery stenosis model of male mice to mimic VCID. Intermittent theta-burst stimulation (iTBS) or consecutive theta-burst stimulation (cTBS) was administered for 14 consecutive days. Through luxol fast blue staining, electron microscopy and immunofluorescence, we found that iTBS, not cTBS, significantly improved demyelination, axonal damage and β-amyloid deposition, without affecting cerebral blood flow in VCID mice. At cellular levels, iTBS rescued the loss of mature oligodendrocytes, promoted precursor cell differentiation, and inhibited pro-inflammatory activation of astrocytes and microglia. Notably, iTBS attenuated cognitive deterioration in both short-term retention and long-term spatial memory of VCID mice as indicated by serial neurobehavioral tests. To explore the molecular involvement of iTBS, mRNA sequencing was carried out. By real-time PCR and combined RNA fluorescence in situ hybridization with immunofluorescence, iTBS was confirmed to increase Rxrg expression specifically in mature oligodendrocytes. Collectively, iTBS could ameliorate vascular cognitive dysfunction, probably via mitigating white matter lesions and neuroinflammation in the corpus callosum. Rxrg signaling in mature oligodendrocytes, which was increased by iTBS, might be a potential target for VCID treatment.

Cerebral hypoperfusion exacerbates vascular dysfunction after traumatic brain injury

Traumatic brain injuries are extremely common, and although most patients recover from their injuries many TBI patients suffer prolonged symptoms and remain at a higher risk for developing cardiovascular disease and neurodegeneration. Moreover, it remains challenging to identify predictors of poor long-term outcomes. Here, we tested the hypothesis that preexisting cerebrovascular impairment exacerbates metabolic and vascular dysfunction and leads to worse outcomes after TBI. Male mice underwent a mild surgical reduction in cerebral blood flow using a model of bilateral carotid artery stenosis (BCAS) wherein steel microcoils were implanted around the carotid arteries. Then, 30 days post coil implantation, mice underwent TBI or sham surgery. Gene expression profiles, cerebral blood flow, metabolic function, oxidative damage, vascular health and angiogenesis were assessed. Single nuclei RNA sequencing of endothelial cells isolated from mice after TBI showed differential gene expression profiles after TBI and BCAS, that were further altered when mice underwent both challenges. TBI but not BCAS increased mitochondrial oxidative metabolism. Both BCAS and TBI decreased cerebrovascular responses to repeated whisker stimulation. BCAS induced oxidative damage and inflammation in the vasculature as well as loss of vascular density, and reduced the numbers of angiogenic tip cells. Finally, intravascular protein accumulation was increased among mice that experienced both BCAS and TBI. Overall, our findings reveal that a prior vascular impairment significantly alters the profile of vascular health and function of the cerebrovasculature, and when combined with TBI may result in worsened outcomes.

MRI hypoperfusion as a determinant of cognitive impairment in adults with Moyamoya angiopathy

INTRODUCTION

In Moyamoya angiopathy (MMA), mechanisms underlying cognitive impairment remain debated. We aimed to assess the association of cognitive impairment with the degree and the topography of cerebral hypoperfusion in MMA.

METHODS

A retrospective analysis of neuropsychological and perfusion MRI data from adults with MMA was performed. Ischemic and haemorrhagic lesion masks were created to account for cerebral lesions in the analysis of cerebral perfusion. Whole brain volume of hypoperfused parenchyma was outlined on perfusion maps using different Tmax thresholds from 4 to 12 s. Regional analysis produced mean Tmax values at different regions of interest. Analyses compared perfusion ratios in patients with and without cognitive impairment, with multivariable logistic regression analysis to identify predictive factors.

RESULTS

Cognitive impairment was found in 20/48 (41.7%) patients. Attention/processing speed and memory were equally impaired (24%) followed by executive domain (23%). After adjustment, especially for lesion volume, hypoperfused parenchyma volume outlined by Tmax > 4 s or Tmax > 5 s thresholds was an independent factor of cognitive impairment (OR for Tmax > 4 s = 1.06 [CI 95% 1.008-1.123]) as well as attention/processing speed (OR for Tmax > 4 s = 1.07 [CI 95% 1.003-1.133]) and executive domains (OR for Tmax > 5 s = 1.08 [CI 95% 1.004-1.158]). Regarding cognitive functions, patients with processing speed and flexibility impairment had higher frontal Tmax compared to other ROIs and to patients with normal test scores.

DISCUSSION

Cerebral hypoperfusion emerged as an independent factor of cognitive impairment in MMA particularly in attention/processing speed and executive domains, with a strong contribution of frontal areas.

CONCLUSION

Considering this association, revascularization surgery could improve cognitive impairment.

Neuroprotective effect of GJ-4 against cognitive impairments in vascular dementia by improving white matter damage

BACKGROUND

White matter lesions (WMLs) are increasingly linked to the pathological process of chronic vascular dementia (VaD). An effective crocins fraction extracted from Gardenia Fructus, GJ-4, has been shown to improve cognitive function in several Alzheimer's disease models and VaD models.

OBJECTIVES

To explore the potential mechanisms of GJ-4 on WMLs in a chronic VaD mouse model.

METHODS

The chronic VaD mouse model was established, and WMLs were characterized by cerebral blood flow (CBF), behavioral tests, LFB staining, and immunohistochemistry. The anti-oxidative effect of GJ-4 was validated by examining biochemical parameters (SOD, MDA, and GSH) and the Keap1-Nrf2/HO-1 pathway. The impact of GJ-4 on lipid metabolism in WM was further investigated through lipidomic analysis.

RESULTS

GJ-4 significantly attenuated cognitive impairments and improved the CBF of BCAS (bilateral common carotid artery stenosis)-induced mice. Mechanism research showed that GJ-4 could enhance cognition by promoting the repair of WMLs by inhibiting oxidative stress. Furthermore, GJ-4 treatment significantly reduced chronic cerebral hypoperfusion (CCH)-induced WMLs via improving lipid metabolism disorder in the WM.

CONCLUSION

This research has provided valuable insights into the significance of WMLs in CCH-induced VaD and underscored the potential of GJ-4 as a therapeutic agent for improving cognitive function by targeting WMLs. These findings suggest that GJ-4 is a promising candidate for the treatment of VaD.

Resveratrol Mitigates Cognitive Impairments and Cholinergic Cell Loss in the Medial Septum in a Mouse Model of Gradual Cerebral Hypoperfusion

Vascular cognitive impairment and dementia (VCID) is the second leading cause of dementia. There is currently no effective treatment for VCID. Resveratrol (RSV) is considered an antioxidant; however, our group has observed pleiotropic effects in stroke paradigms, suggesting more effects may contribute to mechanistic changes beyond antioxidative properties. The main goal of this study was to investigate if administering RSV twice a week could alleviate cognitive declines following the induction of a VCID model. Additionally, our aim was to further describe whether this treatment regimen could decrease cell death in brain areas vulnerable to changes in cerebral blood flow, such as the hippocampus and medial septum. We hypothesized RSV treatments in a mouse model of gradual cerebral hypoperfusion protect against cognitive impairment. We utilized gradual bilateral common carotid artery stenosis (GBCCAS) via the surgical implantation of ameroid constrictor devices. RSV treatment was administered on the day of implantation and twice a week thereafter. Cerebral perfusion was measured by laser speckle contrast imaging, and cognitive functions, including the recognition memory, the spatial working memory, and associative learning, were assessed by novel object recognition (NOR), Y-maze testing, and contextual fear conditioning (CFC), respectively. RSV treatment did not alleviate cerebral perfusion deficits but mitigated cognitive deficits in CFC and NOR after GBCCAS. Despite these deficits, no hippocampal pathology was observed; however, cholinergic cell loss in the medial septum was significantly increased after GBCCAS. This cholinergic cell loss was mitigated by RSV. This study describes a novel mechanism by which chronic RSV treatments protect against a VCID-induced cognitive decline through the preservation of cholinergic cell viability to improve memory performance.

Bruton's tyrosine kinase inhibition ameliorated neuroinflammation during chronic white matter ischemia

Chronic cerebral hypoperfusion (CCH), a disease afflicting numerous individuals worldwide, is a primary cause of cognitive deficits, the pathogenesis of which remains poorly understood. Bruton's tyrosine kinase inhibition (BTKi) is considered a promising strategy to regulate inflammatory responses within the brain, a crucial process that is assumed to drive ischemic demyelination progression. However, the potential role of BTKi in CCH has not been investigated so far. In the present study, we elucidated potential therapeutic roles of BTK in both in vitro hypoxia and in vivo ischemic demyelination model. We found that cerebral hypoperfusion induced white matter injury, cognitive impairments, microglial BTK activation, along with a series of microglia responses associated with inflammation, oxidative stress, mitochondrial dysfunction, and ferroptosis. Tolebrutinib treatment suppressed both the activation of microglia and microglial BTK expression. Meanwhile, microglia-related inflammation and ferroptosis processes were attenuated evidently, contributing to lower levels of disease severity. Taken together, BTKi ameliorated white matter injury and cognitive impairments induced by CCH, possibly via skewing microglia polarization towards anti-inflammatory and homeostatic phenotypes, as well as decreasing microglial oxidative stress damage and ferroptosis, which exhibits promising therapeutic potential in chronic cerebral hypoperfusion-induced demyelination.

Identification of toll-like receptor 2 as a key regulator of neuronal apoptosis in vascular dementia by bioinformatics analysis and experimental validation

BACKGROUND

Vascular dementia (VaD), the second most prevalent type of dementia, lacks a well-defined cause and effective treatment. Our objective was to utilize bioinformatics analysis to discover the fundamental disease-causing genes and pathological mechanisms in individuals diagnosed with VaD.

METHODS

To identify potential pathogenic genes associated with VaD, we conducted weighted gene co-expression network analysis (WGCNA), differential expression analysis, and protein-protein interaction (PPI) analysis. The exploration of potential biological mechanisms involved the utilization of Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis. Moreover, a bilateral common carotid artery stenosis (BCAS) mouse model of VaD was established, and the expression of the hub gene, its relationship with cognitive function and its potential pathogenic mechanism were verified by cognitive behavior tests, cerebral blood flow measurement, Western blotting, and immunofluorescence experiments.

RESULTS

This study identified 293 DEGs from the brain cortex of VaD patients and healthy controls, among these genes, the Toll-like receptor 2 (TLR2) gene was identified as hub gene, and it was associated with the apoptosis-related pathway PI3K/AKT.The BCAS model demonstrated that the use of TLR2 inhibitors greatly enhanced the cognitive function of the mice (p < 0.05). Additionally, there was a notable decrease in the number of apoptotic cells in the brain cortex of the mice (p < 0.01). Moreover, significant alterations in the levels of proteins related to the PI3K/AKT pathway and cleaved-caspase3 proteins were detected (p < 0.05).

CONCLUSIONS

TLR2 plays a role in the pathophysiology of VaD by enhancing the neuronal apoptotic pathway, suggesting it could be a promising therapeutic target.

Cerebral hypoperfusion exacerbates traumatic brain injury in male but not female mice

Mild-moderate traumatic brain injuries (TBIs) are prevalent, and while many individuals recover, there is evidence that a significant number experience long-term health impacts, including increased vulnerability to neurodegenerative diseases. These effects are influenced by other risk factors, such as cardiovascular disease. Our study tested the hypothesis that a pre-injury reduction in cerebral blood flow (CBF), mimicking cardiovascular disease, worsens TBI recovery. We induced bilateral carotid artery stenosis (BCAS) and a mild-moderate closed-head TBI in male and female mice, either alone or in combination, and analyzed CBF, spatial learning, memory, axonal damage, and gene expression. Findings showed that BCAS and TBI independently caused a ~10% decrease in CBF. Mice subjected to both BCAS and TBI experienced more significant CBF reductions, notably affecting spatial learning and memory, particularly in males. Additionally, male mice showed increased axonal damage with both BCAS and TBI compared to either condition alone. Females exhibited spatial memory deficits due to BCAS, but these were not worsened by subsequent TBI. Gene expression analysis in male mice highlighted that TBI and BCAS individually altered neuronal and glial profiles. However, the combination of BCAS and TBI resulted in markedly different transcriptional patterns. Our results suggest that mild cerebrovascular impairments, serving as a stand-in for preexisting cardiovascular conditions, can significantly worsen TBI outcomes in males. This highlights the potential for mild comorbidities to modify TBI outcomes and increase the risk of secondary diseases.

Treatment of vascular dementia in female rats with AV-001, an Angiopoietin-1 mimetic peptide, improves cognitive function

Background

Vascular dementia (VaD) is a complex neurodegenerative disorder. We previously found that treatment of VaD in middle-aged male rats subjected to multiple microinfarction (MMI) with AV-001, a Tie2 receptor agonist, significantly improves cognitive function. Age and sex affect the development and response of VaD to therapeutic intervention. Thus, the present study investigated the therapeutic effect of AV-001 on VaD in aged female rats subjected to MMI.

Methods

Female 18-month-old Wistar rats were subjected to MMI by injecting either 1,000 (low dose, LD-MMI) or 6,000 (high dose, HD-MMI) cholesterol crystals of size 70-100 μm into the right internal carotid artery. AV-001 (1 μg/Kg, i.p.) was administered once daily after MMI for 1 month, with treatment initiated 1 day after MMI. A battery of behavioral tests to examine sensorimotor and cognitive functions was performed at 21-28 days after MMI. All rats were sacrificed at 1 month after MMI.

Results

Aged female rats subjected to LD-MMI exhibit severe neurological deficits, memory impairment, and significant white matter (WM) and oligodendrogenesis injury in the corpus callosum compared with control rats. HD-MMI in aged female rats induces significant anxiety- and depression-like behaviors, which were not detected in LD-MMI aged female rats. Also, HD-MMI induces significantly increased WM injury compared to LD-MMI. AV-001 treatment of LD-MMI and HD-MMI increases oligodendrogenesis, myelin and axon density in the corpus callosum and striatal WM bundles, promotes WM integrity and attenuates neurological and cognitive deficits. Additionally, both LD-MMI and HD-MMI rats exhibit a significant increase, while AV-001 significantly decreases the levels of inflammatory factors in the cerebrospinal fluid (CSF).

Conclusion

MMI reduces oligodendrogenesis, and induces demyelination, axonal injury and WM injury, and causes memory impairment, while HD-MMI induces increased WM injury and further depression-like behaviors compared to LD-MMI rats. AV-001 has a therapeutic effect on aged female rats with MMI by reducing WM damage and improving neuro-cognitive outcomes.

Construction of a screening system for lipid-derived radical inhibitors and validation of hit compounds to target retinal and cerebrovascular diseases

Recent studies have highlighted the indispensable role of oxidized lipids in inflammatory responses, cell death, and disease pathogenesis. Consequently, inhibitors targeting oxidized lipids, particularly lipid-derived radicals critical in lipid peroxidation, which are known as radical-trapping antioxidants (RTAs), have been actively pursued. We focused our investigation on nitroxide compounds that have rapid second-order reaction rate constants for reaction with lipid-derived radicals. A novel screening system was developed by employing competitive reactions between library compounds and a newly developed profluorescence nitroxide probe with lipid-derived radicals to identify RTA compounds. A PubMed search of the top hit compounds revealed their wide application as repositioned drugs. Notably, the inhibitory efficacy of methyldopa, selected from these compounds, against retinal damage and bilateral common carotid artery stenosis was confirmed in animal models. These findings underscore the efficacy of our screening system and suggest that it is an effective approach for the discovery of RTA compounds.

Nicotinamide riboside alleviates brain dysfunction induced by chronic cerebral hypoperfusion via protecting mitochondria

Chronic cerebral hypoperfusion (CCH) is an enduring inadequate blood flow to the brain, resulting in vascular dementia (VaD). However, the effective treatment strategies are lacking. Supplementing with nicotinamide adenine dinucleotide (NAD+) has shown neuroprotective benefits in other neurodegenerative disorders. Nicotinamide riboside (NR), as a precursor of NAD+, is believed to hold promise in improving mitochondrial health, autophagy, and cognitive function. Meanwhile, NR has unique oral bioavailability, good tolerability, and minimal side effects, and it is the most promising for clinical translation. However, the effectiveness of NR in treating CCH-related VaD is still uncertain. The present study examined the neuroprotective effects of NR supplementation and its underlying mechanisms in a CCH rat model. The rats with CCH were given NR at a daily dosage of 400 mg/kg for 3 months. NR supplementation increased blood and brain NAD+ levels and improved brain function in CCH rats, including cognitive function and oxygenation capacity. It also reduced hippocampal neuronal loss and abnormalities and mitigated the decrease in dendritic spine density. The analysis of RNA sequencing in hippocampal tissue supports these findings. Electron microscopy and protein detection results suggest that NR may maintain mitochondrial structural integrity and exert a protective role by attenuating mitochondrial fission and impaired autophagy flux caused by CCH. In conclusion, these findings offer evidence for the neuroprotective potential of NR supplementation in ameliorating cognitive impairment induced by CCH.

miR-30a-5p mediates ferroptosis of hippocampal neurons in chronic cerebral hypoperfusion-induced cognitive dysfunction by modulating the SIRT1/NRF2 pathway

OBJECTIVE

Chronic cerebral hypoperfusion (CCH) is a common cause of brain dysfunction. As a microRNA (also known as miRNAs or miRs), miR-30a-5p participates in neuronal damage and relates to ferroptosis. We explored the in vivo and in vitro effects and functional mechanism of miR-30a-5p in CCH-triggered cognitive impairment through the silent information regulator 1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway.

METHODS

After 1 month of CCH modeling through bilateral common carotid artery stenosis, mice were injected with 2 μL antagomir (also known as anti-miRNAs) miR-30a-5p, with cognitive function evaluated by Morris water maze and novel object recognition tests. In vitro HT-22 cell oxygen glucose deprivation (OGD) model was established, followed by miR-30a-5p inhibitor and/or si-SIRT1 transfections, with Fe2+ concentration, malonaldehyde (MDA) and glutathione (GSH) contents, reactive oxygen species (ROS), miR-30a-5p and SIRT1 and glutathione peroxidase 4 (GPX4) protein levels, NRF2 nuclear translocation, and miR-30a-5p-SIRT1 targeting relationship assessed.

RESULTS

CCH-induced mice showed obvious cognitive impairment, up-regulated miR-30a-5p, and down-regulated SIRT1. Ferroptosis occurred in hippocampal neurons, manifested by elevated Fe2+ concentration and ROS and MDA levels, mitochondrial atrophy, and diminished GSH content. Antagomir miR-30a-5p or miR-30a-5p inhibitor promoted SIRT1 expression and NRF2 nuclear translocation, increased GPX4, cell viability and GSH content, and reduced Fe2+ concentration and ROS and MDA levels. miR-30a-5p negatively regulated SIRT1. In vitro, miR-30a-5p knockout increased NRF2 nuclear translocation by up-regulating SIRT1, inhibiting OGD-induced ferroptosis in HT-22 cells.

CONCLUSION

miR-30a-5p induces hippocampal neuronal ferroptosis and exacerbates post-CCH cognitive dysfunction by targeting SIRT1 and reducing NRF2 nuclear translocation.

MYPT1SMKO Mice Function as a Novel Spontaneous Age- and Hypertension-Dependent Animal Model of CSVD

Cerebral small vessel disease (CSVD) is the most common progressive vascular disease that causes vascular dementia. Aging and hypertension are major contributors to CSVD, but the pathophysiological mechanism remains unclear, mainly due to the lack of an ideal animal model. Our previous study revealed that vascular smooth muscle cell (VSMC)-specific myosin phosphatase target subunit 1 (MYPT1) knockout (MYPT1SMKO) leads to constant hypertension, prompting us to explore whether hypertensive MYPT1SMKO mice can be considered a novel CSVD animal model. Here, we found that MYPT1SMKO mice displayed age-dependent CSVD-like neurobehaviors, including decreased motion speed, anxiety, and cognitive decline. MYPT1SMKO mice exhibited remarkable white matter injury compared with control mice, as shown by the more prominent loss of myelin at 12 months of age. Additionally, MYPT1SMKO mice were found to exhibit CSVD-like small vessel impairment, including intravascular hyalinization, perivascular space enlargement, and microbleed and blood-brain barrier (BBB) disruption. Last, our results revealed that the brain of MYPT1SMKO mice was characterized by an exacerbated inflammatory microenvironment, which is similar to patients with CSVD. In light of the above structural and functional phenotypes that closely mimic the conditions of human CSVD, we suggest that MYPT1SMKO mice are a novel age- and hypertension-dependent animal model of CSVD.

3D Visualization of Whole Brain Vessels and Quantification of Vascular Pathology in a Chronic Hypoperfusion Model Causing White Matter Damage

Chronic cerebral hypoperfusion is an important pathological factor in many neurodegenerative diseases, such as cerebral small vessel disease (CSVD). One of the most used animal models for chronic cerebral hypoperfusion is the bilateral common carotid artery stenosis (BCAS) mouse. For the therapy of CSVD and other diseases, it will be beneficial to understand the pathological alterations of the BCAS mouse, particularly vascular pathological changes. A mouse model of BCAS was used, and 8 weeks later, cognitive function of the mice was examined by using novel object recognition test and eight-arm radial maze test. 11.7 T magnetic resonance imaging (MRI) and luxol fast blue staining were used to evaluate the injury of the corpus callosum (CC), anterior commissure (AC), internal capsule (IC), and optic tract (Opt) in the cerebral white matter of mice. Three-dimensional vascular images of the whole brain of mice were acquired using fluorescence micro-optical sectioning tomography (fMOST) with a high resolution of 0.32 × 0.32 × 1.00 μm3. Then, the damaged white matter regions were further extracted to analyze the vessel length density, volume fraction, tortuosity, and the number of vessels of different internal diameters. The mouse cerebral caudal rhinal vein was also extracted and analyzed for its branch number and divergent angle in this study. BCAS modeling for 8 weeks resulted in impaired spatial working memory, reduced brain white matter integrity, and myelin degradation in mice, and CC showed the most severe white matter damage. 3D revascularization of the whole mouse brain showed that the number of large vessels was reduced and the number of small vessels was increased in BCAS mice. Further analysis revealed that the vessel length density and volume fraction in the damaged white matter region of BCAS mice were significantly reduced, and the vascular lesions were most noticeable in the CC. At the same time, the number of small vessels in the above white matter regions was significantly reduced, while the number of microvessels was significantly increased in BCAS mice, and the vascular tortuosity was also significantly increased. In addition, the analysis of caudal rhinal vein extraction revealed that the number of branches and the average divergent angle in BCAS mice were significantly reduced. The BCAS modeling for 8 weeks will lead to vascular lesions in whole brain of mice, and the caudal nasal vein was also damaged, while BCAS mice mainly mitigated the damages by increasing microvessels. What is more, the vascular lesions in white matter of mouse brain can cause white matter damage and spatial working memory deficit. These results provide evidence for the vascular pathological alterations caused by chronic hypoperfusion.

Pathophysiology of cerebral small vessel disease: a journey through recent discoveries

Cerebral small vessel disease (cSVD) encompasses a heterogeneous group of age-related small vessel pathologies that affect multiple regions. Disease manifestations range from lesions incidentally detected on neuroimaging (white matter hyperintensities, small deep infarcts, microbleeds, or enlarged perivascular spaces) to severe disability and cognitive impairment. cSVD accounts for approximately 25% of ischemic strokes and the vast majority of spontaneous intracerebral hemorrhage and is also the most important vascular contributor to dementia. Despite its high prevalence and potentially long therapeutic window, there are still no mechanism-based treatments. Here, we provide an overview of the recent advances in this field. We summarize recent data highlighting the remarkable continuum between monogenic and multifactorial cSVDs involving NOTCH3, HTRA1, and COL4A1/A2 genes. Taking a vessel-centric view, we discuss possible cause-and-effect relationships between risk factors, structural and functional vessel changes, and disease manifestations, underscoring some major knowledge gaps. Although endothelial dysfunction is rightly considered a central feature of cSVD, the contributions of smooth muscle cells, pericytes, and other perivascular cells warrant continued investigation.

Increased Expression of VCAM1 on Brain Endothelial Cells Drives Blood-Brain Barrier Impairment Following Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion (CCH)-triggered blood-brain barrier (BBB) dysfunction is a core pathological change occurring in vascular dementia (VD). Despite the recent advances in the exploration of the structural basis of BBB impairment and the routes of entry of harmful compounds after a BBB leakage, the molecular mechanisms inducing BBB impairment remain largely unknown in terms of VD. Here, we employed a CCH-induced VD model and discovered increased vascular cell adhesion molecule 1 (VCAM1) expression on the brain endothelial cells (ECs). The expression of VCAM1 was directly correlated with the severity of BBB impairment. Moreover, the VCAM1 expression was associated with different regional white matter lesions. Furthermore, a compound that could block VCAM1 activation, K-7174, was also found to alleviate BBB leakage and protect the white matter integrity, whereas pharmacological manipulation of the BBB leakage did not affect the VCAM1 expression. Thus, our results demonstrated that VCAM1 is an important regulator that leads to BBB dysfunction following CCH. Blocking VCAM1-mediated BBB impairment may thus offer a new strategy to treat CCH-related neurodegenerative diseases.

Integrated Analysis of Chromatin and Transcriptomic Profiling Identifies PU.1 as a Core Regulatory Factor in Microglial Activation Induced by Chronic Cerebral Hypoperfusion

In addition to causing white matter lesions, chronic cerebral hypoperfusion (CCH) can also cause damage to gray matter, but the underlying molecular mechanisms remain largely unknown. In order to obtain a better understanding of the relationship between gene expression and transcriptional regulation alterations, novel upstream regulators could be identified using integration analysis of the transcriptome and epigenetic approaches. Here, a bilateral common carotid artery stenosis (BCAS) model was established for inducing CCH in mice. The spatial cognitive function of mice was evaluated, and changes in cortical microglia morphology were observed. RNA-sequencing (RNA-seq) and the assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) were performed on isolated mouse cortical brain tissue. Then, a systematic joint analysis of BCAS hypoperfusion-induced cortex-specific RNA-seq and ATAC-seq was conducted in order to assess the extent of the correlation between the two, and PU.1 was found to be greatly enriched through motif analysis and transcription factor annotation. Also, the core regulatory factor PU.1 induced by BCAS hypoperfusion was shown to be colocalized with microglia. Based on the above analysis, PU.1 plays a key regulatory role in microglial activation induced by CCH. And the transcriptome and epigenomic data presented in this study can help identify potential targets for future research exploring chronic hypoperfusion-induced brain injury.

Metabolomics-Based Effects of a Natural Product on Remyelination After Cerebral Ischemia Injury Via GABABR-pCREB-BDNF Pathway

BACKGROUND

Yi-Qi-Tong-Luo Granules (YQTLs) is a natural compound of Traditional Chinese Medicine authorized by China Food and Drug Administration (CFDA). These granules are employed in the convalescent stage of cerebral infarction and render notable clinical efficacy. This study aims to uncover the underlying mechanisms of YQTLs on remyelination after cerebral ischemia injury.

MATERIALS AND METHODS

We established cerebral ischemia model in rats using microsphere-induced multiple cerebral infarction (MCI). We evaluated the pharmacological effects of YQTLs on MCI rats, through Morri's water maze test, open field test, hematoxylin and eosin staining, and glycine silver immersion. We employed liquid chromatography mass spectrometry metabolomics to identify differential metabolites. Enzyme-linked immunosorbent assay was utilized to measure the release of neurotrophins, while immunofluorescence staining was used to assess oligodendrocyte precursor cells differences and myelin regeneration. We used Western blotting to validate the protein expression of remyelination-associated signaling pathways.

RESULTS

YQTLs significantly improves cognitive function following cerebral ischemia injury. Pathological tissue staining revealed that YQTLs administration inhibits neuronal denaturation and neurofibrillary tangles. We identified 141 differential metabolites among the sham, MCI, and YQTLs-treated MCI groups. Among these metabolites, neurotransmitters were identified, and notably, gamma-aminobutyric acid (GABA) showed marked improvement in the YQTLs group. The induction of neurotrophins, such as brain-derived neurotrophic factor (BDNF) and PDGFAA, upregulation of olig2 and MBP expression, and promotion of remyelination were evident in YQTLs-treated MCI groups. Gamma-aminobutyric acid B receptors (GABABR), pERK/extracellular regulated MAP kinase, pAKT/protein kinase B, and pCREB/cAMP response element-binding were upregulated following YQTLs treatment.

CONCLUSION

YQTLs enhance the binding of GABA to GABABR, thereby activating the pCREB/BDNF signaling pathway, which in turn increases the expression of downstream myelin-associated proteins and promotes remyelination and cognitive function.

Hope for vascular cognitive impairment: Ac-YVAD-cmk as a novel treatment against white matter rarefaction

Vascular cognitive impairment (VCI) is the second leading cause of dementia with limited treatment options, characterised by cerebral hypoperfusion-induced white matter rarefaction (WMR). Subcortical VCI is the most common form of VCI, but the underlying reasons for region susceptibility remain elusive. Recent studies employing the bilateral cortical artery stenosis (BCAS) method demonstrate that various inflammasomes regulate white matter injury and blood-brain barrier dysfunction but whether caspase-1 inhibition will be beneficial remains unclear. To address this, we performed BCAS on C57/BL6 mice to study the effects of Ac-YVAD-cmk, a caspase-1 inhibitor, on the subcortical and cortical regions. Cerebral blood flow (CBF), WMR, neuroinflammation and the expression of tight junction-related proteins associated with blood-brain barrier integrity were assessed 15 days post BCAS. We observed that Ac-YVAD-cmk restored CBF, attenuated BCAS-induced WMR and restored subcortical myelin expression. Within the subcortical region, BCAS activated the NLRP3/caspase-1/interleukin-1beta axis only within the subcortical region, which was attenuated by Ac-YVAD-cmk. Although we observed that BCAS induced significant increases in VCAM-1 expression in both brain regions that were attenuated with Ac-YVAD-cmk, only ZO-1 and occludin were observed to be significantly altered in the subcortical region. Here we show that caspase-1 may contribute to subcortical regional susceptibility in a mouse model of VCI. In addition, our results support further investigations into the potential of Ac-YVAD-cmk as a novel treatment strategy against subcortical VCI and other conditions exhibiting cerebral hypoperfusion-induced WMR.

The role of the Pin1-cis P-tau axis in the development and treatment of vascular contribution to cognitive impairment and dementia and preeclampsia

Tauopathies are neurodegenerative diseases characterized by deposits of abnormal Tau protein in the brain. Conventional tauopathies are often defined by a limited number of Tau epitopes, notably neurofibrillary tangles, but emerging evidence suggests structural heterogeneity among tauopathies. The prolyl isomerase Pin1 isomerizes cis P-tau to inhibit the development of oligomers, tangles and neurodegeneration in multiple neurodegenerative diseases such as Alzheimer's disease, traumatic brain injury, vascular contribution to cognitive impairment and dementia (VCID) and preeclampsia (PE). Thus, cis P-tau has emerged as an early etiological driver, blood marker and therapeutic target for multiple neurodegenerative diseases, with clinical trials ongoing. The discovery of cis P-tau and other tau pathologies in VCID and PE calls attention for simplistic classification of tauopathy in neurodegenerative diseases. These recent advances have revealed the exciting novel role of the Pin1-cis P-tau axis in the development and treatment of vascular contribution to cognitive impairment and dementia and preeclampsia.

Exercise Improves Cerebral Blood Flow and Functional Outcomes in an Experimental Mouse Model of Vascular Cognitive Impairment and Dementia (VCID)

Vascular cognitive impairment and dementia (VCID) are a growing threat to public health without any known treatment. The bilateral common carotid artery stenosis (BCAS) mouse model is valid for VCID. Previously, we have reported that remote ischemic postconditioning (RIPostC) during chronic cerebral hypoperfusion (CCH) induced by BCAS increases cerebral blood flow (CBF), improves cognitive function, and reduces white matter damage. We hypothesized that physical exercise (EXR) would augment CBF during CCH and prevent cognitive impairment in the BCAS model. BCAS was performed in C57/B6 mice of both sexes to establish CCH. One week after the BCAS surgery, mice were randomized to treadmill exercise once daily or no EXR for four weeks. CBF was monitored with an LSCI pre-, post, and 4 weeks post-BCAS. Cognitive testing was performed for post-BCAS after exercise training, and brain tissue was harvested for histopathology and biochemical test. BCAS led to chronic hypoperfusion resulting in impaired cognitive function and other functional outcomes. Histological examination revealed that BCAS caused changes in neuronal morphology and cell death in the cortex and hippocampus. Immunoblotting showed that BCAS was associated with a significant downregulate of AMPK and pAMPK and NOS3 and pNOS3. BCAS also decreased red blood cell (RBC) deformability. EXR therapy increased and sustained improved CBF and cognitive function, muscular strength, reduced cell death, and loss of white matter. EXR is effective in the BCAS model, improving CBF and cognitive function, reducing white matter damage, improving RBC deformability, and increasing RBC NOS3 and AMPK. The mechanisms by which EXR improves CBF and attenuates tissue damage need further investigation.

MFG-E8 Alleviates Cognitive Impairments Induced by Chronic Cerebral Hypoperfusion by Phagocytosing Myelin Debris and Promoting Remyelination

Chronic cerebral hypoperfusion is one of the pathophysiological mechanisms contributing to cognitive decline by causing white matter injury. Microglia phagocytosing myelin debris in a timely manner can promote remyelination and contribute to the repair of white matter. However, milk fat globule-epidermal growth factor-factor 8 (MFG-E8), a microglial phagocytosis-related protein, has not been well studied in hypoperfusion-related cognitive dysfunction. We found that the expression of MFG-E8 was significantly decreased in the brain of mice after bilateral carotid artery stenosis (BCAS). MFG-E8 knockout mice demonstrated more severe BCAS-induced cognitive impairments in the behavioral tests. In addition, we discovered that the deletion of MFG-E8 aggravated white matter damage and the destruction of myelin microstructure through fluorescent staining and electron microscopy. Meanwhile, MFG-E8 overexpression by AAV improved white matter injury and increased the number of mature oligodendrocytes after BCAS. Moreover, in vitro and in vivo experiments showed that MFG-E8 could enhance the phagocytic function of microglia via the αVβ3/αVβ5/Rac1 pathway and IGF-1 production to promote the differentiation of oligodendrocyte progenitor cells into mature oligodendrocytes. Interestingly, we found that MFG-E8 was mainly derived from astrocytes, not microglia. Our findings suggest that MFG-E8 is a potential therapeutic target for cognitive impairments following cerebral hypoperfusion.

Brain-derived endothelial cells are neuroprotective in a chronic cerebral hypoperfusion mouse model

Whether organ-specific regeneration is induced by organ-specific endothelial cells (ECs) remains unelucidated. The formation of white matter lesions due to chronic cerebral hypoperfusion causes cognitive decline, depression, motor dysfunction, and even acute ischemic stroke. Vascular ECs are an important target for treating chronic cerebral hypoperfusion. Brain-derived ECs transplanted into a mouse chronic cerebral hypoperfusion model showed excellent angiogenic potential. They were also associated with reducing both white matter lesions and brain dysfunction possibly due to the high expression of neuroprotective humoral factors. The in vitro coculture of brain cells with ECs from several diverse organs suggested the function of brain-derived endothelium is affected within a brain environment due to netrin-1 and Unc 5B systems. We found brain CD157-positive ECs were more proliferative and beneficial in a mouse model of chronic cerebral hypoperfusion than CD157-negative ECs upon inoculation. We propose novel methods to improve the symptoms of chronic cerebral hypoperfusion using CD157-positive ECs.

Establishment of a novel mouse model of renal artery coiling-based chronic hypoperfusion-related kidney injury

Renal artery stenosis-induced chronic renal ischemia is an important cause of renal dysfunction, especially in older adults, and its incidence is currently increasing. To elucidate the mechanisms underlying chronic renal hypoperfusion-induced kidney damage, we developed a novel mouse model of renal artery coiling-based chronic hypoperfusion-related kidney injury. This model exhibits decreased renal blood flow and function, atrophy, and parenchymal injury in the coiled kidney, along with compensatory hypertrophy in the non-coiled kidney, without chronic hypertension. The availability of this mouse model, which can develop renal ischemia without genetic modification, will enhance kidney disease research by serving as a new tool to investigate the effects of acquired factors (e.g., obesity and aging) and genetic factors on renal artery stenosis-related renal parenchymal damage.

Xinshubao tablet rescues cognitive dysfunction in a mouse model of vascular dementia: Involvement of neurogenesis and neuroinflammation

Vascular dementia (VaD) represents a severe cognitive dysfunction syndrome closed linked to cardiovascular function. In the present study, we assessed the potential of Xinshubao tablet (XSB), a traditional Chinese prescription widely used for cardiovascular diseases, to mitigate neuropathological damage in a mouse model of VaD and elucidated the underlying mechanisms. Our findings revealed that oral administration of XSB rescued the cardiac dysfunction resulting from bilateral common carotid artery stenosis (BCAS), improved the cerebral blood flow (CBF) and cognitive function, reduced white matter injury, inhibited excessive microglial and astrocytic activation, stimulated hippocampal neurogenesis, and reduced neural apoptosis in the brains of BCAS mice. Mechanistically, RNA-seq analysis indicated that XSB treatment was significantly associated with neuroinflammation, vasculature development, and synaptic transmission, which were further confirmed by q-PCR assays. Western blot results revealed that XSB treatment hindered the nuclear translocation of nuclear factor-κB (NF-κB), thereby suppressing the NF-κB signaling pathway. These results collectively demonstrated that XSB could ameliorate cognitive dysfunction caused by BCAS through regulating CBF, reducing white matter lesions, suppressing glial activation, promoting neurogenesis, and mitigating neuroinflammation. Notably, the NF-κB signaling pathway emerged as a pivotal player in this mechanism.

Hippocampal capillary pericytes in post-stroke and vascular dementias and Alzheimer's disease and experimental chronic cerebral hypoperfusion

Neurovascular unit mural cells called 'pericytes' maintain the blood-brain barrier and local cerebral blood flow. Pathological changes in the hippocampus predispose to cognitive impairment and dementia. The role of hippocampal pericytes in dementia is largely unknown. We investigated hippocampal pericytes in 90 post-mortem brains from post-stroke dementia (PSD), vascular dementia (VaD), Alzheimer's disease (AD), and AD-VaD (Mixed) subjects, and post-stroke non-demented survivors as well as similar age controls. We used collagen IV immunohistochemistry to determine pericyte densities and a mouse model of VaD to validate the effects of chronic cerebral hypoperfusion. Despite increased trends in hippocampal microvascular densities across all dementias, mean pericyte densities were reduced by ~25-40% in PSD, VaD and AD subjects compared to those in controls, which calculated to 14.1 ± 0.7 per mm capillary length, specifically in the cornu ammonis (CA) 1 region (P = 0.01). In mice with chronic bilateral carotid artery occlusion, hippocampal pericyte loss was ~60% relative to controls (P < 0.001). Pericyte densities were correlated with CA1 volumes (r = 0.54, P = 0.006) but not in any other sub-region. However, mice subjected to the full-time environmental enrichment (EE) paradigm showed remarkable attenuation of hippocampal CA1 pericyte loss in tandem with CA1 atrophy. Our results suggest loss of hippocampal microvascular pericytes across common dementias is explained by a vascular aetiology, whilst the EE paradigm offers significant protection.

A multicenter, single-arm, phase II clinical trial of adrenomedullin in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy

Background

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), the most common form of hereditary cerebral small vessel disease (SVD), currently lacks disease-modifying treatments. Adrenomedullin (AM), a vasoactive peptide with angiogenic, vasodilatory, anti-inflammatory, and anti-oxidative properties, shows potential effects on the neuro-glial-vascular unit.

Objective

The AdrenoMedullin for CADASIL (AMCAD) study aims to assess the efficacy and safety of AM in patients with CADASIL.

Sample size

Overall, 60 patients will be recruited.

Methods

The AMCAD is a multicenter, investigator-initiated, single-arm phase II trial. Patients with a confirmed CADASIL diagnosis, based on NOTCH3 genetic testing, will receive an 8-h AM treatment (15 ng/kg/min) for 14 days following a baseline assessment (from day 1 to day 14). Follow-up evaluations will be performed on days 15, 28, 90, and 180.

Study outcomes

The primary endpoint is the cerebral blood flow change rate in the frontal cortex, evaluated using arterial spin labeling magnetic resonance imaging, from baseline to day 28. Summary statistics, 95% confidence intervals, and a one-sample t-test will be used for analysis.

Conclusion

The AMCAD study aims to represent the therapeutic potential of AM in patients with CADASIL, addressing an unmet medical need in this challenging condition.

Clinical Trial Registration

jRCT 2,051,210,117 (https://jrct.niph.go.jp/en-latest-detail/jRCT2051210117).

Inhibiting CSF1R alleviates cerebrovascular white matter disease and cognitive impairment

White matter abnormalities, related to poor cerebral perfusion, are a core feature of small vessel cerebrovascular disease, and critical determinants of vascular cognitive impairment and dementia. Despite this importance there is a lack of treatment options. Proliferation of microglia producing an expanded, reactive population and associated neuroinflammatory alterations have been implicated in the onset and progression of cerebrovascular white matter disease, in patients and in animal models, suggesting that targeting microglial proliferation may exert protection. Colony-stimulating factor-1 receptor (CSF1R) is a key regulator of microglial proliferation. We found that the expression of CSF1R/Csf1r and other markers indicative of increased microglial abundance are significantly elevated in damaged white matter in human cerebrovascular disease and in a clinically relevant mouse model of chronic cerebral hypoperfusion and vascular cognitive impairment. Using the mouse model, we investigated long-term pharmacological CSF1R inhibition, via GW2580, and demonstrated that the expansion of microglial numbers in chronic hypoperfused white matter is prevented. Transcriptomic analysis of hypoperfused white matter tissue showed enrichment of microglial and inflammatory gene sets, including phagocytic genes that were the predominant expression modules modified by CSF1R inhibition. Further, CSF1R inhibition attenuated hypoperfusion-induced white matter pathology and rescued spatial learning impairments and to a lesser extent cognitive flexibility. Overall, this work suggests that inhibition of CSF1R and microglial proliferation mediates protection against chronic cerebrovascular white matter pathology and cognitive deficits. Our study nominates CSF1R as a target for the treatment of vascular cognitive disorders with broader implications for treatment of other chronic white matter diseases.

Transforming growth factor-β1 protects against white matter injury and reactive astrogliosis via the p38 MAPK pathway in rodent demyelinating model

In central nervous system (CNS), demyelination is a pathological process featured with a loss of myelin sheaths around axons, which is responsible for the diseases of multiple sclerosis, neuromyelitis optica, and so on. Transforming growth factor-beta1 (TGF-β1) is a multifunctional cytokine participating in abundant physiological and pathological processes in CNS. However, the effects of TGF-β1 on CNS demyelinating disease and its underlying mechanisms are controversial and not well understood. Herein, we evaluated the protective potential of TGF-β1 in a rodent demyelinating model established by lysophosphatidylcholine (LPC) injection. It was identified that supplement of TGF-β1 evidently rescued the cognitive deficit and motor dysfunction in LPC modeling mice assessed by novel object recognition and balance beam behavioral tests. Besides, quantified by luxol fast blue staining, immunofluorescence, and western blot, administration of TGF-β1 was found to significantly ameliorate the demyelinating lesion and reactive astrogliosis by suppressing p38 MAPK pathway. Mechanistically, the results of in vitro experiments indicated that treatment of TGF-β1 could directly promote the differentiation and migration of cultured oligodendrocytes. Our study revealed that modulating TGF-β1 activity might serve as a promising and innovative therapeutic strategy in CNS demyelinating diseases.

Neddylation in the chronically hypoperfused corpus callosum: MLN4924 reduces blood-brain barrier injury via ERK5/KLF2 signaling

Blood-brain barrier (BBB) breakdown and cerebrovascular dysfunction may contribute to the pathology in white matter lesions and consequent cognitive decline caused by cerebral hypoperfusion. Neddylation is the process of attaching a ubiquitin-like molecule NEDD8 (neuronal precursor cell-expressed developmentally downregulated protein 8) to specific targets. By modifying protein substrates, neddylation plays critical roles in various important biological processes. However, whether neddylation influences the pathogenesis of hypoperfused brain remains unclear. In the present study, cerebral hypoperfusion-induced white matter lesions were produced by bilateral common carotid artery stenosis in mice. The function of the neddylation pathway, BBB integrity, cerebrovascular dysfunction, myelin density in the corpus callosum and cognitive function were determined. We show that NEDD8 conjugation aberrantly amplified in microvascular endothelium in the corpus callosum following cerebral hypoperfusion. MLN4924, a small-molecule inhibitor of NEDD8-activating enzyme currently in clinical trials, preserved BBB integrity, attenuated glial activation and enhanced oligodendrocyte differentiation, and reduced hypoperfusion-induced white matter lesions in the corpus callosum and thus improved cognitive performance via inactivating cullin-RING E3 ligase (CRL). Administration of MLN4924 caused the accumulation of ERK5 and KLF2. The ERK5 inhibitor BIX 02189, down-regulated MLN4924-induced activation of KLF2 and reversed MLN4924-mediated increase in pericyte coverage and junctional proteins. Furthermore, BIX 02189 blocked MLN4924-afforded protection against BBB disruption and white matter lesions in the corpus callosum. Collectively, our results revealed that neddylation impairs vascular function and thus exacerbated the pathology of hypoperfused brain and that inhibition of neddylation with MLN4924 may offer novel therapeutic opportunities for cerebral hypoperfusion-associated cognitive impairment.

The Bilateral Carotid Artery Stenosis (BCAS) Model of Vascular Dementia

Vascular dementia is the second most common form of dementia after Alzheimer's disease. Chronic cerebral hypoperfusion is a key contributor to the development of vascular dementia. In this chapter, we describe the surgical procedures used for bilateral carotid artery stenosis (BCAS) surgery to induce chronic cerebral hypoperfusion. Mice that undergo BCAS surgery develop the hallmarks of vascular dementia including white matter lesions, neuroinflammation, and cognitive impairment. This technique may be used for studies of chronic cerebral hypoperfusion and vascular dementia in mice.

Neurotropin alleviates cognitive impairment by inhibiting TLR4/MyD88/NF-κB inflammation signaling pathway in mice with vascular dementia

Vascular dementia (VD) is the second most common cause of dementia after Alzheimer's disease. Neuroinflammation contributes to pathogenesis of VD. Neurotropin (NTP) is an analgesic that has been shown to suppress inflammation and neural repair. But its effects on VD are still unclear. Therefore, this study aimed to investigate the therapeutic effects and potential mechanisms of NTP in the VD model mice established by bilateral common carotid artery stenosis method. In VD mice, we found that NTP treatment increased cerebral blood flow by Laser speckle imaging, reduced neuron loss by Nissl, HE and immunochemistry staining, attenuated white matter damage by magnetic resonance imaging and ultrastructural damage by transmission electron microscope, improved cognitive functions by new object recognition test and three-chamber test, Y maze test and Morris water maze test, inhibited significantly glial activation by immunofluorescence methods, reduced the expression of TLR4, down-regulated expression of MyD88 and phosphorylation of NF-κB P65, decreased the levels of pro-inflammatory cytokines IL-1β, IL-6 and TNFα. Further, we showed that administration of a TLR4 inhibitor TAK242 had a similar effect to NTP, while the TLR4 agonist CRX-527 attenuated the effect of NTP in the VD mice. Collectively, our study suggested that NTP alleviates cognitive impairment by inhibiting TLR4/MyD88/NF-κB inflammation signaling pathway in the VD mice. Thus, NTP may be a promising therapeutic approach and a potential TLR4 inhibitor for VD.

Tetramethylpyrazine promotes axonal remodeling and modulates microglial polarization via JAK2-STAT1/3 and GSK3-NFκB pathways in ischemic stroke

Ischemic stroke results in demyelination that underlies neurological disfunction. Promoting oligodendrogenesis will rescue the injured axons and accelerate remyelination after stroke. Microglia react to ischemia/hypoxia and polarize to M1/M2 phenotypes influencing myelin injury and repair. Tetramethylpyrazine (TMP) has neuroprotective effects in treating cerebrovascular disorders. This study aims to evaluate whether TMP promotes the renovation of damaged brain tissues especially on remyelination and modulates microglia phenotypes following ischemic stroke. Here magnetic resonance imaging (MRI)-diffusion tensor imaging (DTI) and histopathological evaluation are performed to characterize the process of demyelination and remyelination. Immunofluorescence staining is used to prove oligodendrogenesis and microglial polarization. Western blotting is conducted to examine interleukin (IL)-6, IL-10, transforming growth factor β (TGF-β) and Janus protein tyrosine kinase (JAK) 2-signal transducer and activator of transcription (STAT) 1/3-glycogen synthase kinase (GSK) 3-nuclear transcription factor κB (NFκB) signals. Results show TMP alleviates the injury of axons and myelin sheath, increases NG2+, Ki67+/NG2+, CNPase+, Ki67+/CNPase+, Iba1+/Arg-1+ cells and decreases Iba1+ and Iba1+/CD16+ cells in periinfarctions of rats. Particularly, TMP downregulates IL-6 and upregulates IL-10 and TGF-β expressions, besides, enhances JAK2-STAT3 and suppresses STAT1-GSK3-NFκB activation in middle cerebral artery occlusion (MCAo) rats. Then we demonstrate that TMP reverses M1/M2 phenotype via JAK2-STAT1/3 and GSK3-NFκB pathways in lipopolysaccharide (LPS) plus interferon-γ (IFN-γ)-stimulated BV2 microglia. Blocking JAK2 with AG490 counteracts TMP's facilitation on M2 polarization of microglia. This study warrants the promising therapy for stroke with TMP treatment.