Increased risk of cognitive impairment and more severe brain lesions in hypertensive compared to non-hypertensive patients with cerebral small vessel disease

Endothelial cells as key players in cerebral small vessel disease

Cerebral small vessel disease (SVD) is a vascular disorder that increases the risk of stroke and dementia and is diagnosed through brain MRI. Current primary prevention and secondary treatment of SVD are focused on lifestyle interventions and vascular risk factor control, including blood pressure reduction. However, these interventions have limited effects, a proportion of individuals with sporadic SVD do not have hypertension, and SVD shows strong familial and genetic underpinnings. Here, we describe the increasing evidence that cerebral endothelial cell dysfunction is a key mechanism of SVD. Dysfunctional endothelial cells can cause cerebral blood vessel dysfunction, alter blood-brain barrier integrity and interfere with cell-cell interactions in the neuro-glial-vascular unit, thereby causing damage to adjacent brain tissue. Endothelial cells in SVD may become dysfunctional through intrinsic mechanisms via genetic vulnerability to SVD and/or via extrinsic factors such as hypertension, smoking and diabetes. Drugs that act on endothelial pathways are already looking promising in clinical trials, and understanding their action on endothelial cells and the surrounding brain may lead to the development of other therapies to limit disease progression and improve outcomes for individuals with SVD.

Exosomal miR-320e through wnt2targeted inhibition of the Wnt/β-catenin pathway allevisate cerebral small vessel disease and cognitive impairment

BACKGROUND

Exosomal miRNAs play crucial roles in many central nervous system diseases. Cerebral small vessel disease (CVSD) is a small vessel disease that is affected by various factors. This study aimed to investigate the role of exosomal miR-320e in the Wnt/β-catenin pathway stimulated by oxidative stress and assess its clinical correlation with psychiatric symptoms in patients with CVSD.

AIM

To explore whether exosomal miR-320e could suppress the Wnt/β-catenin pathway and play a protective role in CVSD progression, as well as examine its potential correlation with cognitive impairment and depression in patients with CVSD.

METHODS

Differentially expressed exosomal miRNAs were filtered by sequencing plasma exosomes from patients with CVSD and healthy controls. Bioinformatics and dual luciferase analyses were used to confirm the binding of miR-320e to Wnt2, and the mRNA and protein levels of downstream components in the Wnt/β-catenin pathway were evaluated when overexpressed or with knockdown of miR-320e under H2O2-induced oxidative stress. In addition, Wnt2-targeting siRNA was used to confirm the role of miR-320e in the Wnt2-mediated inhibition of the Wnt/β-catenin pathway. A retrospective analysis was conducted among patients with CVSD to confirm the correlation between miR-320e expression and the severity of cognitive impairment and depression, which were quantified using the Montreal Cognitive Assessment (MoCA)/Executive Function Assessment (EFA), and the Hamilton Depression Scale (HAMD)/Beck Depression Inventory (BDI), respectively.

RESULTS

High-throughput sequencing revealed that exosomal miR-320e was downregulated in patients with CVSD. Bioinformatics analysis and dual-luciferase reporter gene experiments showed that exosomal miR-320e inhibited the Wnt/β-catenin pathway in response to oxidative stress by targeting the 3' noncoding region of Wnt2. Uptake of exosomes carrying miR-320e into endothelial cells could also target Wnt2 and inhibit the Wnt2/β-catenin pathway. Elevated miR-320e expression may protect patients with CVSD from relatively severe cognitive impairment and depression, as it was found to have a positive correlation with the MoCA/EFA and HAMD/BDI scores.

CONCLUSION

Our results suggest that exosomal miR-320e suppresses the Wnt/β-catenin pathway and may play a protective role in CVSD progression.

Myosin light chain phosphorylation exhibits a gradient across the wall of cerebellar arteries under sustained ex vivo vascular tone

Small blood vessel diseases are often associated with impaired regulation of vascular tone. The current understanding of resistance arteries often focuses on how a level of vascular tone is achieved in the acute phase, while less emphasis is placed on mechanisms that maintain vascular tone. In this study, cannulated rat superior cerebellar arteries (SCA) developed spontaneous myogenic tone and showed a marked and sustained constriction in the presence of diluted serum (10%), a stimulus relevant to cerebrovascular disease. Both phosphorylated myosin light chain (MLC-p) and smooth muscle alpha actin (SM-α-actin) aligned with phalloidin-stained actin filaments in the vessel wall, while exhibiting a 'high to low' gradient across the layers of vascular smooth muscle cells (VSMC), peaking in the outer layer. The MLC-p distribution profile shifted towards the adventitia in serum treated vessels, while removal of the serum reversed it. Furthermore, a positive correlation between the MLC-p signal and vessel wall tension was also evident. The gradients of phosphorylated MLC and SM-α-actin are consistent with a spatial regulation of the myosin-actin apparatus in the vessel wall during the maintenance of vascular tone. Further, the changing profiles of MLC-p and SM-α-actin are consistent with SCA vasoconstriction being accompanied by VSMC cytoskeletal reorganization.

Deep-learning retinal vessel calibre measurements and risk of cognitive decline and dementia

Previous studies have explored the associations of retinal vessel calibre, measured from retinal photographs or fundus images using semi-automated computer programs, with cognitive impairment and dementia, supporting the concept that retinal blood vessels reflect microvascular changes in the brain. Recently, artificial intelligence deep-learning algorithms have been developed for the fully automated assessment of retinal vessel calibres. Therefore, we aimed to determine whether deep-learning-based retinal vessel calibre measurements are predictive of risk of cognitive decline and dementia. We conducted a prospective study recruiting participants from memory clinics at the National University Hospital and St. Luke's Hospital in Singapore; all participants had comprehensive clinical and neuropsychological examinations at baseline and annually for up to 5 years. Fully automated measurements of retinal arteriolar and venular calibres from retinal fundus images were estimated using a deep-learning system. Cox regression models were then used to assess the relationship between baseline retinal vessel calibre and the risk of cognitive decline and developing dementia, adjusting for age, gender, ethnicity, education, cerebrovascular disease status, hypertension, hyperlipidemia, diabetes, and smoking. A total of 491 participants were included in this study, of whom 254 developed cognitive decline over 5 years. In multivariable models, narrower retinal arteriolar calibre (hazard ratio per standard deviation decrease = 1.258, P = 0.008) and wider retinal venular calibre (hazard ratio per standard deviation increase = 1.204, P = 0.037) were associated with increased risk of cognitive decline. Among participants with cognitive impairment but no dementia at baseline (n = 212), 44 progressed to have incident dementia; narrower retinal arteriolar calibre was also associated with incident dementia (hazard ratio per standard deviation decrease = 1.624, P = 0.021). In summary, deep-learning-based measurement of retinal vessel calibre was associated with risk of cognitive decline and dementia.

Advances in the Role of Endothelial Cells in Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) poses a serious socio-economic burden due to its high prevalence and severe impact on the quality of life of elderly patients. Pathological changes in CSVD mainly influence small cerebral arteries, microarteries, capillaries, and small veins, which are usually caused by multiple vascular risk factors. CSVD is often identified on brain magnetic resonance imaging (MRI) by recent small subcortical infarcts, white matter hyperintensities, lacune, cerebral microbleeds (CMBs), enlarged perivascular spaces (ePVSs), and brain atrophy. Endothelial cell (EC) dysfunction is earlier than clinical symptoms. Immune activation, inflammation, and oxidative stress may be potential mechanisms of EC injury. ECs of the blood–brain–barrier (BBB) are the most important part of the neurovascular unit (NVU) that ensures constant blood flow to the brain. Impaired cerebral vascular autoregulation and disrupted BBB cause cumulative brain damage. This review will focus on the role of EC injury in CSVD. Furthermore, several specific biomarkers will be discussed, which may be useful for us to assess the endothelial dysfunction and explore new therapeutic directions.

A Novel Imaging Biomarker for Cerebral Small Vessel Disease Associated With Cognitive Impairment: The Deep-Medullary-Veins Score

Objective: To explore the biomarkers of cerebral small vessel disease (CSVD) associated with cognitive impairment.

Methods: A total of 69 patients with CSVD were enrolled in the study, and baseline clinical and imaging data were reviewed retrospectively. The following neuroimaging biomarkers of CSVD were identified: high-grade white matter hyperintensity (HWMH), cerebral microbleeds (CMB), enlarged perivascular space (PVS), and lacunar infarct (LI). A total score for CSVD was calculated. The deep medullary veins (DMVs) were divided into six segments according to the regional anatomy. The total DMV score (0–18) was derived from the sum of the scores of the six individual segments, the scores of which ranged from 0 to 3, for a semiquantitative assessment of the DMV that was based on segmental continuity and visibility.

Results: The DMV score, patient age, and total CSVD score were independently associated with the presence or absence of cognitive impairment in patients with CSVD (P < 0.05). By integrating patient age and the total CSVD and DMV scores, the area under the curve of the receiver operating characteristic curve (AUROC) for predicting CSVD associated with cognitive impairment was 0.885, and the sensitivity and specificity were 64.71 and 94.23%, respectively.

Conclusions: The DMV score may be a novel imaging biomarker for CSVD associated with cognitive impairment. The integration of the DMV score with age and total CSVD score should increase the predictive value of the DMV score for CSVD associated with cognitive impairment.

Carotid revascularization and cognitive impairment: the neglected role of cerebral small vessel disease

Carotid atherosclerosis is a pathological process that leads to narrowing of the vessel lumen and a consequent risk of stroke. Revascularization procedures such as carotid endarterectomy (CEA) and carotid stenting aim to reduce occurrence of stroke in selected patients. Due to the proven benefit and low intraoperative risk, CEA is currently the preferred choice in candidates for carotid revascularization. However, the risk of cognitive impairment subsequent to CEA has not been fully elucidated and is unclear whether certain conditions, such as frailty, may increase this risk. There is consistent evidence that shows that frail patients have higher risk of cognitive impairment after surgical procedure. Moreover, brain pre-existing conditions may play a role in cognitive impairment after CEA. Cerebral small vessel disease (SVD) is a pathology that involves microcirculation and is detectable with computed tomography or magnetic resonance. SVD shares common vascular risk factors with carotid atherosclerosis, is a major contributor to vascular cognitive impairment and vascular dementia, and has been proposed as a marker of brain frailty. In this review, we discuss the current evidence about the link between carotid revascularization and cognitive impairment and advance the hypothesis that SVD may play a relevant role in development of cognitive impairment after carotid revascularization.

Volume of white matter hyperintensities increases with blood pressure in patients with hypertension

Objective

Hypertension is a risk factor for development of white matter hyperintensities (WMHs). However, the relationship between hypertension and WMHs remains obscure. We sought to clarify this relationship using clinical data from different regions of China.

Methods

We analyzed the data of 333 patients with WMHs in this study. All included patients underwent conventional magnetic resonance imaging (MRI) examination. A primary diagnosis of WMHs was made according to MRI findings. The volume burden of WMHs was investigated using the Fazekas scale, which is widely used to rate the degree of WMHs. We conducted retrospective clinical analysis of the data in this study.

Results

Our findings showed that WMHs in patients with hypertension were associated with diabetes, cardiovascular diseases, history of cerebral infarct, and plasma glucose and triglyceride levels. Fazekas scale scores for WMHs increased with increased blood pressure values in patients with hypertension.

Conclusion

This analysis indicates that hypertension is an independent contributor to the prevalence and severity of WMHs.