scholarly journals Inhibition of the Immunoproteasome Subunit LMP7 Ameliorates Cerebral White Matter Demyelination Possibly via TGFβ/Smad Signaling

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xingyong Chen ◽  
Nannan Yao ◽  
Zejing Lin ◽  
Yinzhou Wang
Keyword(s):  
Cognitive Impairment ◽  
Cognitive Function ◽  
White Matter ◽  
Growth Factor ◽  
Ischemic Injury ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Cerebral White Matter ◽  
Smad Signaling ◽  
Bilateral Carotid

Objectives. Chronic cerebral hypoperfusion induces white matter ischemic injury and cognitive impairment, whereas the mechanism remains unclear. Immunoproteasomes have been implicated in the pathogenesis of acute ischemia stroke and multiple sclerosis. However, the expression and role of immunoproteasomes in the brain of chronic cerebral hypoperfusion remain to be clarified. Methods. Chronic white matter ischemic injury mice models were induced by bilateral carotid artery stenosis (BCAS). A selective immunoproteasome subunit low-molecular-mass peptide-7 (LMP7) inhibitor PR957 was administered to mice. Cognitive function, white matter integrity, and potential pathways were assessed after BCAS. Results. The present study found that chronic cerebral hypoperfusion following BCAS induced cerebral white matter demyelination and cognitive impairment, accompanied with elevated expression of the immunoproteasomes LMP2 and LMP7, activation of astrocytes and microglia, and increased production of inflammatory cytokines (e.g., interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-10, transforming growth factor-β1 (TGFβ1), and insulin-like growth factor-1 (IGF-1)). However, inhibition of LMP7 with the specific proteasome inhibitor PR957 significantly mitigated the histological damage of the white matter, suppressed inflammatory response, and paralleled by an improvement of cognitive function. Furthermore, treatment of PR957 significantly upregulated the level of TGFβ1, the total expression level, and the phosphorylation level of Smad2/3 and promoted brain remyelination. Surprisingly, PR957 alone had no effects on the neuroinflammation response and the activation of TGFβ/Smad signaling in the sham-operated (BCAS-nonoperated) mice. Conclusions. The possible mechanism underlying this was attributed to that the immunoproteasome regulates TGFβ/Smad signaling-mediated neuroinflammation and oligodendrocyte remyelination.

scholarly journals Attenuating vascular stenosis-induced astrogliosis preserves white matter integrity and cognitive function

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Qian Liu ◽  
Mohammad Iqbal H. Bhuiyan ◽  
Ruijia Liu ◽  
Shanshan Song ◽  
Gulnaz Begum ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Cognitive Impairment ◽  
Cognitive Function ◽  
White Matter ◽  
Spatial Working Memory ◽  
Ex Vivo ◽  
Cerebral Hypoperfusion ◽  
Cellular Mechanisms ◽  
Bilateral Carotid

Abstract Background Chronic cerebral hypoperfusion (CCH) causes white matter damage and cognitive impairment, in which astrogliosis is the major pathology. However, underlying cellular mechanisms are not well defined. Activation of Na+/H+ exchanger-1 (NHE1) in reactive astrocytes causes astrocytic hypertrophy and swelling. In this study, we examined the role of NHE1 protein in astrogliosis, white matter demyelination, and cognitive function in a murine CCH model with bilateral carotid artery stenosis (BCAS). Methods Sham, BCAS, or BCAS mice receiving vehicle or a selective NHE1 inhibitor HOE642 were monitored for changes of the regional cerebral blood flow and behavioral performance for 28 days. Ex vivo MRI-DTI was subsequently conducted to detect brain injury and demyelination. Astrogliosis and demyelination were further examined by immunofluorescence staining. Astrocytic transcriptional profiles were analyzed with bulk RNA-sequencing and RT-qPCR. Results Chronic cerebral blood flow reduction and spatial working memory deficits were detected in the BCAS mice, along with significantly reduced mean fractional anisotropy (FA) values in the corpus callosum, external capsule, and hippocampus in MRI DTI analysis. Compared with the sham control mice, the BCAS mice displayed demyelination and axonal damage and increased GFAP+ astrocytes and Iba1+ microglia. Pharmacological inhibition of NHE1 protein with its inhibitor HOE642 prevented the BCAS-induced gliosis, damage of white matter tracts and hippocampus, and significantly improved cognitive performance. Transcriptome and immunostaining analysis further revealed that NHE1 inhibition specifically attenuated pro-inflammatory pathways and NADPH oxidase activation. Conclusion Our study demonstrates that NHE1 protein is involved in astrogliosis with pro-inflammatory transformation induced by CCH, and its blockade has potentials for reducing astrogliosis, demyelination, and cognitive impairment.

scholarly journals Nicotinamide Improves Cognitive Function in Mice With Chronic Cerebral Hypoperfusion

2021 ◽  
Vol 12 ◽  
Author(s):  
Bin Liu ◽  
Guifeng Zhao ◽  
Ling Jin ◽  
Jingping Shi
Keyword(s):  
Cognitive Impairment ◽  
Cognitive Function ◽  
White Matter ◽  
Western Blotting ◽  
Blood Supply ◽  
Sham Group ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Morris Water Maze Test ◽  
White Matter Damage

Normal brain function requires steady blood supply to maintain stable energy state. When blood supply to the brain becomes suboptimal for a long period of time, chronic cerebral hypoperfusion (CCH) and a variety of brain changes may occur. CCH causes white matter injury and cognitive impairment. The present study investigated the effect of nicotinamide (NAM) on CCH-induced cognitive impairment and white matter damage in mice. Male C57Bl/6J mice aged 10–12 weeks (mean age = 11 ± 1 weeks) and weighing 24 - 29 g (mean weight = 26.5 ± 2.5 g) were randomly assigned to three groups (eight mice/group): sham group, CCH group and NAM group. Chronic cerebral hypoperfusion (CCH) was induced using standard methods. The treatment group mice received intraperitoneal injection of NAM at a dose of 200 mg/kg body weight (bwt) daily for 30 days. Learning, memory, anxiety, and depression-like behaviors were measured using Morris water maze test (MWMT), open field test (OFT), sucrose preference test (SPT), and forced swim test (FST), respectively. White matter damage and remodeling were determined via histological/ immunohistochemical analyses, and western blotting, respectively. The results showed that the time spent in target quadrant, number of crossings and escape latency were significantly lower in CCH group than in sham group, but they were significantly increased by NAM (p < 0.05). Mice in NAM group moved significantly faster and covered longer distances, when compared with those in CCH group (p < 0.05). The percentage of time spent in open arms and the number of entries to the open arms were significantly lower in CCH group than in NAM group (p < 0.05). Moreover, anhedonia and histologic scores (index of myelin injury) were significantly higher in CCH group than in sham group, but they were significantly reduced by NAM (p < 0.05). The results of immunohistochemical staining and Western blotting showed that the protein expressions of 2′, 3′-cyclic-nucleotide 3′-phosphodiesterase (CNPase) and synaptophysin were significantly downregulated in CCH group, relative to sham group, but they were significantly upregulated by NAM (p < 0.05). These results indicate that NAM improves cognitive function in mice with CCH.

scholarly journals The Association between Cerebral White Matter Lesions and Plasma Omega-3 to Omega-6 Polyunsaturated Fatty Acids Ratio to Cognitive Impairment Development

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Michihiro Suwa ◽  
Shigeru Yamaguchi ◽  
Tsuyoshi Komori ◽  
Sachiko Kajimoto ◽  
Masaya Kino
Keyword(s):  
Risk Factors ◽  
Cognitive Impairment ◽  
Cognitive Function ◽  
White Matter ◽  
White Matter Lesions ◽  
White Matter Hyperintensity ◽  
Cerebral White Matter ◽  
Omega 3 ◽  
Arachidonic Acids ◽  
Low Serum

Objective. Cerebral white matter hyperintensity (WMH) with magnetic resonance imaging (MRI) has a potential for predicting cognitive impairment. Serum polyunsaturated fatty acid (PUFA) levels are important for evaluating the extent of atherosclerosis. We investigated whether abnormal PUFA levels affected WMH grading and cognitive function in patients without significant cognitive impairment.Methods. Atherosclerotic risk factors, the internal carotid artery (ICA) plaque, and serum ratios of eicosapentaenoic to arachidonic acids (EPA/AA) and docosahexaenoic to arachidonic acids (DHA/AA) were assessed in 286 patients. The relationship among these risk factors, WMH, and cognitive function was evaluated using WMH grading and the Mini-Mental State Examination (MMSE).Results. The development of WMH was associated with aging, hypertension, ICA plaques, and a low serum EPA/AA ratio (<0.38, obtained as the median value) but was not related to dyslipidemia, diabetes, smoking, and a low serum DHA/AA ratio (<0.84, obtained as the median value). In addition, the MMSE score deteriorated slightly with the progression of WMH (29.7 ± 1.0 compared to 28.4 ± 2.1,P<0.0001).Conclusions. The progression of WMH was associated with a low serum EPA/AA ratio and accompanied minimal deterioration in cognitive function. Sufficient omega-3 PUFA intake may be effective in preventing the development of cognitive impairment.

scholarly journals Chronic cerebral hypoperfusion: a key mechanism leading to vascular cognitive impairment and dementia. Closing the translational gap between rodent models and human vascular cognitive impairment and dementia

2017 ◽  
Vol 131 (19) ◽  
pp. 2451-2468 ◽  
Author(s):  
Jessica Duncombe ◽  
Akihiro Kitamura ◽  
Yoshiki Hase ◽  
Masafumi Ihara ◽  
Raj N. Kalaria ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
White Matter ◽  
Small Vessel Disease ◽  
Amyloid Β ◽  
Vascular Cognitive Impairment ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Pathophysiological Mechanism ◽  
Rodent Models ◽  
Recent Refinement

Increasing evidence suggests that vascular risk factors contribute to neurodegeneration, cognitive impairment and dementia. While there is considerable overlap between features of vascular cognitive impairment and dementia (VCID) and Alzheimer’s disease (AD), it appears that cerebral hypoperfusion is the common underlying pathophysiological mechanism which is a major contributor to cognitive decline and degenerative processes leading to dementia. Sustained cerebral hypoperfusion is suggested to be the cause of white matter attenuation, a key feature common to both AD and dementia associated with cerebral small vessel disease (SVD). White matter changes increase the risk for stroke, dementia and disability. A major gap has been the lack of mechanistic insights into the evolution and progress of VCID. However, this gap is closing with the recent refinement of rodent models which replicate chronic cerebral hypoperfusion. In this review, we discuss the relevance and advantages of these models in elucidating the pathogenesis of VCID and explore the interplay between hypoperfusion and the deposition of amyloid β (Aβ) protein, as it relates to AD. We use examples of our recent investigations to illustrate the utility of the model in preclinical testing of candidate drugs and lifestyle factors. We propose that the use of such models is necessary for tackling the urgently needed translational gap from preclinical models to clinical treatments.

scholarly journals Comprehensive Evaluation of White Matter Damage and Neuron Death and Whole-Transcriptome Analysis of Rats With Chronic Cerebral Hypoperfusion

2019 ◽  
Vol 13 ◽  
Author(s):  
Wenxian Li ◽  
Di Wei ◽  
Jianye Liang ◽  
Xiaomei Xie ◽  
Kangping Song ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
White Matter ◽  
Neuronal Death ◽  
Chronic Cerebral Hypoperfusion ◽  
Differentially Expressed ◽  
Cerebral Hypoperfusion ◽  
Neuron Death ◽  
White Matter Damage ◽  
Morris Water Maze Task ◽  
Whole Transcriptome

Background/AimsChronic cerebral hypoperfusion (CCH) is induced by chronic deficit of brain perfusion, contributes to a persistent or progressive cognitive dysfunction, which is characterized by diverse neuropathological manifestations. There are currently no effective medications available. White matter damage (WMD) and cortical neuron death may be caused by CCH, which are related to cognitive impairment, while the underlying molecular mechanisms remain unclear. In the study, a database of the transcriptome level was built to determine potential biomarkers in cortex of CCH.MethodsCCH was induced in male Sprague-Dawley rats by permanent occlusion of the bilateral common carotid arteries. Rats were randomly divided into three groups: Sham-operated group (n = 24), the 4th and 8th week of CCH groups (total = 56, n = 28 for each group). Cognitive function was evaluated using the Morris water maze task. WMD and neuron damage were detected using diffusion tensor imaging and histological analysis, respectively. Western blotting analysis of various markers was used to examine neuronal death. Whole-transcriptome microarray was performed to assess mRNA, circRNA, and lncRNA expression profiles at 4th and 8th weeks after CCH. Diversified bioinformatic tools were performed to analyze and predict the key biological processes and signaling pathways of differentially expressed RNAs and co-expressed potential target genes. Co-expression networks of mRNA–circRNA–miRNA and lncRNA–mRNA were constructed.ResultsCompared to the sham group, cognitive impairment, disintegration of white matter, blood-brain barrier damage and neuron death were induced by CCH. Neuron death including apoptosis and necroptosis might occur in the cortex of CCH. We constructed the regulatory networks of whole-transcriptomic including differentially expressed mRNAs, circRNAs, and lncRNAs, and related biological functions and pathways involved in neurological disease, cell death and survival, energy and metabolism, et al. Our results also indicated that Cyr61 mRNA may play a role in the CCH-related cortical neuronal death.ConclusionWMD and cortical neuronal death are worthy of attention in the pathogenesis of CCH. Additionally, the present results provide potential evidence at the whole-transcription level for CCH, offering candidate biomarkers and therapeutic targets.

Abstract 11558: Sitagliptin Attenuated Brain Damage and Cognitive Impairment in Mice With Chronic Cerebral Hypo-Perfusion Through Suppressing Oxidative Stress and Inflammatory Reaction

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Tzu -Hsien Tsai ◽  
Sarah Chua ◽  
Jiunn-Jye Sheu ◽  
Steve Leu ◽  
Hon Kan Yip
Keyword(s):  
Oxidative Stress ◽  
Working Memory ◽  
Cognitive Impairment ◽  
Brain Damage ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Receptor Protein ◽  
Opposite Pattern ◽  
Tnf Α ◽  
Bilateral Carotid

Background: Sitagliptin, a new anti-diabetic drug that inhibits dipeptidyl peptidase (DPP)-4 enzyme activity, has been reported to possess neuroprotective property. We tested the protective effect of sitagliptin against chronic cerebral hypoperfusion (CHP) in mice after bilateral carotid artery stenosis (BCAS). Methods: Thirty C57BL/6 mice were divided into three groups: Sham control (SC) (n=10), CHP (n=10), CHP-sitagliptin (orally 600mg/kg/day) (n=10). Working memory was assessed with novel-object recognition test. Magnetic resonance imaging (MRI) was performed at day 0 and day 90 after BCAS procedure prior to sacrifice. Results: Immunohistochemical (IHC) staining showed significantly enhanced microglia activation, astrocytosis, and demyelinating change of white matter in CHP group than in SC but the changes were significantly suppressed after sitagliptin treatment (all p<0.01). The mRNA expressions of inflammatory (TNF-α, MCP-1and MMP-2) and apoptotic (Bax) biomarkers showed an identical pattern, whereas the anti-inflammatory (IL-10) and anti-apoptotic (Bcl-2) biomarkers showed an opposite pattern compared to that of IHC among all groups (all p<0.01). The protein expressions of oxidative stress (NOX-I, NOX-II, nitrotyrosin, oxidized protein), inflammatory (NF-κB, TNF-α and MMP-2), apoptotic (mitochondrial Bax, cleaved PARP), and DNA-damage (γ-H2AX) markers showed an identical pattern, while expression pattern of anti-apoptotic marker (Bcl-2) was opposite to that of IHC (all p<0.01). Glycogen-like peptide-1 receptor protein expression progressively increased from SC to CHP-sitagliptin (p<0.01). The short-term working-memory loss and cortical-matter reduction on MRI-T2 showed a pattern identical to that of IHC in all groups (all p<0.01). Conclusion: Sitagliptin protected against cognitive impairment and brain damage in a murine CHP model. Key words: chronic cerebral hypoperfusion, sitagliptin, oxidative stress inflammation

scholarly journals Bilateral common carotid artery stenosis in normotensive rats impairs endothelium-dependent dilation of parenchymal arterioles

2016 ◽  
Vol 310 (10) ◽  
pp. H1321-H1329 ◽  
Author(s):  
Nusrat Matin ◽  
Courtney Fisher ◽  
William F. Jackson ◽  
Anne M. Dorrance
Keyword(s):  
Cognitive Impairment ◽  
Carotid Artery ◽  
Endothelial Function ◽  
Carotid Artery Stenosis ◽  
Short Term Memory ◽  
Artery Stenosis ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Cyclooxygenase Inhibitors ◽  
Bilateral Carotid

Chronic cerebral hypoperfusion is a risk factor for cognitive impairment. Reduced blood flow through the common carotid arteries induced by bilateral carotid artery stenosis (BCAS) is a physiologically relevant model of chronic cerebral hypoperfusion. We hypothesized that BCAS in 20-wk-old Wistar-Kyoto (WKY) rats would impair cognitive function and lead to reduced endothelium-dependent dilation and outward remodeling in the parenchymal arterioles (PAs). After 8 wk of BCAS, both short-term memory and spatial discrimination abilities were impaired. In vivo assessment of cerebrovascular reserve capacity showed a severe impairment after BCAS. PA endothelial function and structure were assessed by pressure myography. BCAS impaired endothelial function in PAs, as evidenced by reduced dilation to carbachol. Addition of nitric oxide synthase and cyclooxygenase inhibitors did not change carbachol-mediated dilation in either group. Inhibiting CYP epoxygenase, the enzyme that produces epoxyeicosatrienoic acid (EETs), a key determinant of endothelium-derived hyperpolarizing factor (EDHF)-mediated dilation, abolished dilation in PAs from Sham rats, but had no effect in PAs from BCAS rats. Expression of TRPV4 channels, a target for EETs, was decreased and maximal dilation to a TRPV4 agonist was attenuated after BCAS. Together these data suggest that EET-mediated dilation is impaired in PAs after BCAS. Thus impaired endothelium-dependent dilation in the PAs may be one of the contributing factors to the cognitive impairment observed after BCAS.

scholarly journals Epigenetic Conditioning Induces Intergenerational Resilience to Dementia in a Mouse Model of Vascular Cognitive Impairment

2021 ◽  
Author(s):  
Krystal Courtney D Belmonte ◽  
Eleanor B Holmgrem ◽  
Tiffany A Wills ◽  
Jeff M Gidday
Keyword(s):  
Cognitive Impairment ◽  
Recognition Memory ◽  
First Generation ◽  
Ex Vivo ◽  
Long Term Potentiation ◽  
Vascular Cognitive Impairment ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Generation Adult ◽  
Bilateral Carotid

Background: Vascular cognitive impairment and dementia (VCID), which occurs immediately or in delayed fashion in 25-30% of stroke survivors, or secondary to chronic cerebral hypoperfusion, is the second leading cause of dementia following Alzheimers disease. To date, efficacious therapies are unavailable. We have shown previously in mice that repetitive hypoxic preconditioning (RHC) induces a long-lasting resilience to acute stroke (Stowe et al., 2011). More recently, we documented that untreated, first-generation adult progeny of mice exposed to RHC prior to mating are protected from retinal ischemic injury (Harman et al., 2020), consistent with accumulating evidence supporting the concept that long-lasting phenotypes induced epigenetically by intermittent stressors may be heritable. We undertook the present study to test the hypothesis that RHC will induce resilience to VCID, and that such RHC-induced resilience can also be inherited. Methods: Chronic cerebral hypoperfusion (CCH) was induced in C57BL/6J mice secondary to bilateral carotid artery stenosis with microcoils in both the parental (F0) generation, and in their untreated first-generation (F1) offspring. Cohorts of F0 mice were directly exposed to either 8 wks of RHC (1 h of systemic hypoxia 11% oxygen, 3x/week) or normoxia prior to CCH. Cohorts of F1 mice were derived from F0 mice treated with RHC prior to mating, and untreated, normoxic controls that were age-matched at the time of stenosis induction. Demyelination in the corpus callosum of F0 mice was assessed following 3 months of CCH by immunohistochemistry. Mice from both generations were assessed for short-term recognition memory in vivo by novel object preference (NOP) testing following 3 months of CCH, and a month thereafter, ex vivo measurements of CA1 hippocampal long-term potentiation (LTP) were recorded from the same animals as a metric of long-lasting changes in synaptic plasticity. Results: Three months of CCH caused demyelination and concomitant impairments in recognition memory in control mice from both generations. However, these CCH-induced memory impairments were prevented in F0 animals directly treated with RHC, as well as in their untreated adult F1 progeny. Similarly, hippocampal LTP was preserved in the 4-month CCH cohorts of mice directly treated with RHC, and in their untreated offspring with CCH. Conclusions: Our findings demonstrate that RHC or other repetitively-presented, epigenetic-based therapeutics may hold promise for inducing a long-lasting resilience to VCID in treated individuals, and in their first-generation adult progeny.

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