Bilateral carotid artery stenosis causes unexpected early changes in brain extracellular matrix and blood-brain barrier integrity in mice
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ABSTRACT: This study demonstrates for the first time that changes in the BBB/ECM occur shortly after bilateral carotid artery stenosis (BCAS) and within multiple brain regions and suggests such changes might underlie the gradual development of BCAS non-white matter pathology.
Project description:Bilateral carotid artery stenosis (BCAS) is one experimental model of vascular dementia thought to preferentially impact brain white matter. Indeed, few studies report hippocampal and cortical pathology prior to 30 days post-stenosis; though it is unclear whether those studies examined regions outside the white matter. Since changes in the blood-brain barrier (BBB) permeability precede more overt brain pathology in various diseases, we hypothesized that changes within the BBB and/or BBB-associated extracellular matrix (ECM) could occur earlier after BCAS in the hippocampus, cortex and striatum and be a precursor of longer term pathology. Here, C57Bl/6 mice underwent BCAS or sham surgeries and changes in the BBB and ECM were analyzed by collagen IV (vascular basement membrane component), α5 integrin (marker of endothelial activation), claudin-5 and occludin (tight junction proteins), Evans blue (permeability marker), Ki-67 (cell proliferation marker), and GFAP and CD11b (glial cell markers) immunohistochemistry after 14 days. Significant changes in markers of cerebrovascular integrity and glial activation were detected, not only in the striatum, but also in the hippocampus and cortex. In conclusion, this study demonstrates for the first time that changes in the BBB/ECM occur shortly after BCAS and within multiple brain regions and suggests such changes might underlie the gradual development of BCAS non-white matter pathology.
Project description:Failure of the blood-brain barrier (BBB) is a critical event in the development and progression of diseases such as acute ischemic stroke, chronic ischemia or small vessels disease that affect the central nervous system. It is not known whether BBB breakdown in subjects with chronic carotid artery stenosis can be restrained with postoperative recovery of cerebral perfusion. The aim of the study was to assess the short-term effect of internal carotid artery stenting on basic perfusion parameters and permeability surface area-product (PS) in such a population. Forty subjects (23 males) with stenosis of >70% within a single internal carotid artery and neurological symptoms who underwent a carotid artery stenting procedure were investigated. Differences in the following computed tomography perfusion (CTP) parameters were compared before and after surgery: global cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP) and PS. PS acquired by CTP is used to measure the permeability of the BBB to contrast material. In all baseline cases, the CBF and CBV values were low, while MTT and TTP were high on both the ipsi- and contralateral sides compared to reference values. PS was approximately twice the normal value. CBF was higher (+6.14%), while MTT was lower (-9.34%) on the contralateral than on the ipsilateral side. All perfusion parameters improved after stenting on both the ipsilateral (CBF +22.66%; CBV +18.98%; MTT -16.09%, TTP -7.62%) and contralateral (CBF +22.27%, CBV +19.72%, MTT -14.65%, TTP -7.46%) sides. PS decreased by almost half: ipsilateral -48.11%, contralateral -45.19%. The decline in BBB permeability was symmetrical on the ipsi- and contralateral sides to the stenosis. Augmented BBB permeability can be controlled by surgical intervention in humans.
Project description:BackgroundThe choroid plexus (ChP) helps maintain the homeostasis of the brain by forming the blood-CSF barrier via tight junctions (TJ) at the choroid plexus epithelial cells, and subsequently preventing neuroinflammation by restricting immune cells infiltration into the central nervous system. However, whether chronic cerebral hypoperfusion causes ChP structural damage and blood-CSF barrier impairment remains understudied.MethodsThe bilateral carotid stenosis (BCAS) model in adult male C57BL/6 J mice was used to induce cerebral hypoperfusion, a model for vascular contributions to cognitive impairment and dementia (VCID). BCAS-mediated changes of the blood-CSF barrier TJ proteins, apical secretory Na+-K+-Cl- cotransporter isoform 1 (NKCC1) protein and regulatory serine-threonine kinases SPAK, and brain infiltration of myeloid-derived immune cells were assessed.ResultsBCAS triggered dynamic changes of TJ proteins (claudin 1, claudin 5) accompanied with stimulation of SPAK-NKCC1 complex and NF-κB in the ChP epithelial cells. These changes impacted the integrity of the blood-CSF barrier, as evidenced by ChP infiltration of macrophages/microglia, neutrophils and T cells. Importantly, pharmacological blockade of SPAK with its potent inhibitor ZT1a in BCAS mice attenuated brain immune cell infiltration and improved cognitive neurological function.ConclusionsBCAS causes chronic ChP blood-CSF damage and immune cell infiltration. Our study sheds light on the SPAK-NKCC1 complex as a therapeutic target in neuroinflammation.
Project description:AMP-activated protein kinase (AMPK) is a regulator of cellular energy metabolism. Long-term use of metformin, an AMPK activator, was previously reported to be neuroprotective, as it promotes behavioral improvement and angiogenesis following an acute ischemic injury of the brain. However, only a few studies have demonstrated the role of AMPK in alleviating chronic cerebral ischemia (CCI) in mice models in the long-term (over 3 months). Therefore, we established a mouse model of CCI via bilateral carotid artery stenosis (BCAS) to explore the effect of AMPK on CCI. We used four groups of 3-month-old male C57BL/6 mice labeled as Sham, BCAS, BCAS + metformin treatment (BCAS + Met) and BCAS + AMPKα2 gene knockout (BCAS + KO). Three months after BCAS, we measured the AMPK protein expression, spatial learning and memory, Nissl bodies, cell apoptosis, astrocyte activation, and oligodendrocyte maturation. Additionally, we observed the brain tissues for changes in cell morphology. We observed that mice in the BCAS group had impaired spatial learning and memory compared with those in the sham group. The brain tissues of mice with CCI injury showed altered cell morphology, fewer Nissl bodies, cerebral cells apoptosis, and astrocyte activation. Interestingly, compared with mice from the BCAS group, the brains of mice from BCAS + Met group suffered lesser damage, whereas those of mice from the BCAS + KO group suffered more damage. The activation of AMPK, especially AMPKα2, plays a neuroprotective role during CCI in a mouse model of BCAS.
Project description:Background: Cardiac function is associated with cognitive function. Previously, we found that stroke and traumatic brain injury evoke cardiac dysfunction in mice. In this study, we investigate whether bilateral common carotid artery stenosis (BCAS), a model that induces vascular dementia (VaD) in mice, induces cardiac dysfunction. Methods: Late-adult (6-8 months) C57BL/6J mice were subjected to sham surgery (n = 6) or BCAS (n = 8). BCAS was performed by applying microcoils (0.16 mm internal diameter) around both common carotid arteries. Cerebral blood flow and cognitive function tests were performed 21-28 days post-BCAS. Echocardiography was conducted in conscious mice 29 days after BCAS. Mice were sacrificed 30 days after BCAS. Heart tissues were isolated for immunohistochemical evaluation and real-time PCR assay. Results: Compared to sham mice, BCAS in mice significantly induced cerebral hypoperfusion and cognitive dysfunction, increased cardiac hypertrophy, as indicated by the increased heart weight and the ratio of heart weight/body weight, and induced cardiac dysfunction and left ventricular (LV) enlargement, indicated by a decreased LV ejection fraction (LVEF) and LV fractional shortening (LVFS), increased LV dimension (LVD), and increased LV mass. Cognitive deficits significantly correlated with cardiac deficits. BCAS mice also exhibited significantly increased cardiac fibrosis, increased oxidative stress, as indicated by 4-hydroxynonenal and NADPH oxidase-2, increased leukocyte and macrophage infiltration into the heart, and increased cardiac interleukin-6 and thrombin gene expression. Conclusions: BCAS in mice without primary cardiac disease provokes cardiac dysfunction, which, in part, may be mediated by increased inflammation and oxidative stress.
Project description:The bilateral common carotid artery stenosis (BCAS) mouse model, which replicates chronic cerebral hypoperfusion and white matter ischemic lesions, is considered to model some aspects of vascular cognitive impairment. Cerebral blood flow (CBF) changes in the brain surface post-BCAS have been demonstrated by laser speckle flowmetry, but CBF levels in the brain parenchyma remain unknown. Adult C57BL/6J male mice were subjected to BCAS using external microcoils. Brain magnetic resonance angiography (MRA) was conducted to visualize the intracranial main arteries while arterial spin labeling (ASL) was used to measure cortical and subcortical parenchymal CBF levels before and after BCAS. Brain MRA showed anterior circulation flow was substantially decreased until 14 days post-BCAS, which gradually but incompletely recovered over the following 14 days, with probable growth of collaterals from the posterior cerebral artery. ASL showed that cortical and subcortical parenchymal CBF remained decreased at approximately 50% of the baseline level during 1 and 14 days post-BCAS, recovering to approximately 70% at day 28. CBF levels in the parenchyma were lower than the cortical superficial region in the BCAS model and remained decreased without recovery during the first 2 weeks post-BCAS. These results suggest that the BCAS model reliably replicates chronic cerebral hypoperfusion.
Project description:Among geriatric diseases, cerebrovascular disease ranks fourth according to the Causes of Death Statistics in 2019, Korea, and is the most common cause of acquired disorders in adults. Daehwang-Hwanglyoun-Sasim-Tang (DHST), a herbal prescription consisting of two herbal medicines, Rhei Rhizoma and Coptidis Rhizoma, has been reported to have anti-inflammatory, antioxidant, and anticancer effects. This study was conducted to confirm the anti-inflammatory mechanism of DHST treatment in ischemic brain injury and to confirm the role of DHST in cognitive function improvement. C57BL/6 male mice were randomly divided into four groups (sham operation, bilateral common carotid artery stenosis (BCAS) control, experimental group administered 5 mL/kg DHST, experimental group administered 50 mL/kg DHST), with each group containing five mice. After 1 week, DHST was orally administered for 4 weeks, 5 days a week, and then behavioral evaluation of learning and memory was performed. In addition, morphological changes in the neurons in the CA1 region of the hippocampus were observed. Inflammation-related factors were evaluated using western blot analysis. In the 50 mL/kg DHST (H-DHST) group, the expression of apoptosis-related proteins was reduced and neuronal damage was suppressed in the hippocampal CA1 region. However, cognitive improvement was observed in the H-DHST group that was attributable to anti-inflammatory and antiapoptotic pathways. In the 5 mL/kg DHST group, no significant effect was observed compared with the control group.
Project description:Vascular dementia (VD) is the second most prevalent dementia type, with no drugs approved for its treatment. Here, the effects of Banhabaekchulcheonma-Tang (BBCT) on ischemic brain injury and cognitive function impairment were investigated in a bilateral carotid artery stenosis (BCAS) mouse model. Mice were divided into sham-operated, BCAS control, L-BBCT (40 ml/kg), and H-BBCT (80 ml/kg) groups. BBCT's effects were characterized using the Y-maze test, novel object recognition test (NORT), immunofluorescence staining, RNA sequencing, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) analyses. The NORT revealed cognitive function improvement in the H-BBCT group, while the Y-maze test revealed no significant difference among the four groups. The CD68+ microglia and GFAP+ astrocyte numbers were reduced in the H-BBCT group. Furthermore, H-BBCT treatment restored the dysregulation of gene expression caused by BCAS. The major BBCT targets were predicted to be cell division cycle protein 20 (CDC20), Epidermal growth factor (EGF), and tumor necrosis factor receptor-associated factor 1 (TRAF1). BBCT regulates the neuroactive ligand-receptor interaction and neuropeptide signaling pathways, as predicted by KEGG and GO analyses, respectively. BBCT significantly improved cognitive impairment in a BCAS mouse model by inhibiting microglial and astrocyte activation and regulating the expression of CDC20, EGF, TRAF1, and key proteins in the neuroactive ligand-receptor interaction and neuropeptide signaling pathways.