A novel rat model of cerebral small vessel disease based on vascular risk factors of hypertension, aging, and cerebral hypoperfusion.

Cerebral small vessel disease (CSVD) is a major cause of vascular cognitive impairment and functional loss in elderly patients. Progressive remodeling of cerebral microvessels due to arterial hypertension or other vascular risk factors, such as aging, can cause dementia or stroke. Typical imaging characteristics of CSVD include cerebral microbleeds (CMB), brain atrophy, small subcortical infarctions, white matter hyperintensities (WMH), and enlarged perivascular spaces (EPVS). Nevertheless, no animal models that reflect all the different aspects of CSVD have been identified. Here, we generated a new CSVD animal model using D-galactose (D-gal) combined with cerebral hypoperfusion in spontaneously hypertensive rats (SHR), which showed all the hallmark pathological features of CSVD and was based on vascular risk factors. SHR were hypodermically injected with D-gal (400 mg/kg/d) and underwent modified microcoil bilateral common carotid artery stenosis surgery. Subsequently, neurological assessments and behavioral tests were performed, followed by vascular ultrasonography, electron microscopy, flow cytometry, and histological analyses. Our rat model showed multiple cerebrovascular pathologies, such as CMB, brain atrophy, subcortical small infarction, WMH, and EPVS, as well as the underlying causes of CSVD pathology, including oxidative stress injury, decreased cerebral blood flow, structural and functional damage to endothelial cells, increased blood-brain barrier permeability, and inflammation. The use of this animal model will help identify new therapeutic targets and subsequently aid the development and testing of novel therapeutic interventions. Main process of the study: Firstly, we screened for optimal conditions for mimicking aging by injecting D-gal into rats for 4 and 8 weeks. Subsequently, we performed modified microcoil BCAS intervention for 4 and 8 weeks in rats to screen for optimal hypoperfusion conditions. Finally, based on these results, we combined D-gal for 8 weeks and modified microcoil BCAS for 4 weeks to explore the changes in SHR.

Activation of NLRP3 inflammasome in a rat model of cerebral small vessel disease.

Cerebral small vessel disease (CSVD) is increasingly being recognized as a leading contributor to cognitive impairment in the elderly. However, there is a lack of effective preventative or therapeutic options for CSVD. In this exploratory study, we investigated the interplay between neuroinflammation and CSVD pathogenesis as well as the cognitive performance, focusing on NLRP3 signaling as a new therapeutic target. Spontaneously hypertensive stroke-prone (SHRSP) rats served as a CSVD model. We found that SHRSP rats showed decline in learning and memory abilities using morris water maze test. Activated NLRP3 signaling and an increased expression of the downstream pro-inflammatory factors, including IL (interleukin)-6 and tumor necrosis factor α were determined. We also observed a remarkable increase in the production of pyroptosis executive protein gasdermin D, and elevated astrocytic and microglial activation. In addition, we identify several neuropathological hallmarks of CSVD, including blood-brain barrier breakdown, white matter damage, and endothelial dysfunction. These results were in correlation with the activation of NLRP3 inflammasome. Thus, our findings reveal that the NLRP3-mediated inflammatory pathway could play a central role in the pathogenesis of CSVD, presenting a novel target for potential CSVD treatment.

Cerebral arterial stiffness is linked to white matter hyperintensities and perivascular spaces in older adults - A 4D flow MRI study.

White matter hyperintensities (WMH), perivascular spaces (PVS) and lacunes are common MRI features of small vessel disease (SVD). However, no shared underlying pathological mechanism has been identified. We investigated whether SVD burden, in terms of WMH, PVS and lacune status, was related to changes in the cerebral arterial wall by applying global cerebral pulse wave velocity (gcPWV) measurements, a newly described marker of cerebral vascular stiffness. In a population-based cohort of 190 individuals, 66-85 years old, SVD features were estimated from T1-weighted and FLAIR images while gcPWV was estimated from 4D flow MRI data. Additionally, the gcPWV's stability to variations in field-of-view was analyzed. The gcPWV was 10.82 (3.94) m/s and displayed a significant correlation to WMH and white matter PVS volume (r = 0.29, p < 0.001; r = 0.21, p = 0.004 respectively from nonparametric tests) that persisted after adjusting for age, blood pressure variables, body mass index, ApoB/A1 ratio, smoking as well as cerebral pulsatility index, a previously suggested early marker of SVD. The gcPWV displayed satisfactory stability to field-of-view variations. Our results suggest that SVD is accompanied by changes in the cerebral arterial wall that can be captured by considering the velocity of the pulse wave transmission through the cerebral arterial network.

Effect of high-fat diet on cerebral pathological changes of cerebral small vessel disease in SHR/SP rats.

Cerebral small vessel diseases (CSVD) are neurological disorders associated with microvessels, manifested pathologically as white matter (WM) changes and cortical microbleeds, with hypertension as a risk factor. Additionally, a high-fat diet (HFD) can affect peripheral vessel health. Our study explored how HFD affects cerebral small vessels in normotensive WKY, hypertensive SHR, and SHR/SP rats. The MRI results revealed that HFD specifically increased WM hyperintensity in SHR/SP rats. Pathologically, it increased WM pallor and vacuolation in SHR and SHR/SP rats. Levels of blood-brain barrier (BBB) protein claudin 5 were decreased in SHR and SHR/SP compared to WKY, with HFD having minimal impact on these levels. Conversely, collagen IV levels remained consistent among the rat strains, which were increased by HFD. Consequently, HFD caused vessel leakage in all rat strains, particularly within the corpus callosum of SHR/SP rats. To understand the underlying mechanisms, we assessed the levels of hypoxia-inducible factor-1α (HIF-1α), Gp91-phox, and neuroinflammatory markers astrocytes, and microglia were increased in SHR and SHR/SP compared to WKY and were further elevated by HFD in all rat strains. Gp91-phox was also increased in SHR and SHR/SP compared to WKY, with HFD causing an increase in WKY but little effect in SHR and SHR/SP. In conclusion, our study demonstrates that HFD, in combined with hypertension, intensifies cerebral pathological alterations in CSVD rats. This exacerbation involves increased oxidative stress and HIF-1α in cerebral vessels, triggering neuroinflammation, vascular basement membrane remodeling, IgG leakage, and ultimately WM damage.

Understanding the relationship between type-2 diabetes, MRI markers of neurodegeneration and small vessel disease, and dementia risk: a mediation analysis.

To explore to which extent neurodegeneration and cerebral small vessel disease (SVD) could mediate the association between type-2 diabetes and higher dementia risk. The analytical sample consisted in 2228 participants, out of the Three-City study, aged 65 and older, free of dementia at baseline who underwent brain MRI. Diabetes was defined by medication intake or fasting or non-fasting elevated glucose levels. Dementia status was assessed every 2 to 3 years, during up to 12 years of follow-up. Brain parenchymal fraction (BPF) and white matter hyperintensities volume (WMHV) were selected as markers of neurodegeneration and cerebral SVD respectively. We performed a mediation analysis of the effect of baseline BPF and WMHV (mediators) on the association between diabetes and dementia risk using linear and Cox models adjusted for age, sex, education level, hypertension, hypercholesterolemia, BMI, smoking and alcohol drinking status, APOE-ε4 status, and study site. At baseline, 8.8% of the participants had diabetes. Diabetes (yes vs. no) was associated with higher WMHV (ßdiab = 0.193, 95% CI 0.040; 0.346) and lower BPF (ßdiab = -0.342, 95% CI -0.474; -0.210), as well as with an increased risk of dementia over 12 years of follow-up (HRdiab = 1.65, 95% CI 1.04; 2.60). The association between diabetes status and dementia risk was statistically mediated by higher WMHV (HRdiab=1.05, 95% CI 1.01; 1.11, mediated part = 10.8%) and lower BPF (HRdiab = 1.12, 95% CI 1.05; 1.20, mediated part = 22.9%). This study showed that both neurodegeneration and cerebral SVD statistically explained almost 30% of the association between diabetes and dementia.

Abnormal brain activities of cognitive processes in cerebral small vessel disease: A systematic review of task fMRI studies.

Cerebral small vessel disease (CSVD) is characterized by widespread functional changes in the brain, as evident from abnormal brain activations during cognitive tasks. However, the existing findings in this area are not yet conclusive. We systematically reviewed 25 studies reporting task-related fMRI in five cognitive domains in CSVD, namely executive function, working memory, processing speed, motor, and affective processing. The findings highlighted: (1) CSVD affects cognitive processes in a domain-specific manner; (2) Compensatory and regulatory effects were observed simultaneously in CSVD, which may reflect the interplay between the negative impact of brain lesion and the positive impact of cognitive reserve. Combined with behavioral and functional findings in CSVD, we proposed an integrated model to illustrate the relationship between altered activations and behavioral performance in different stages of CSVD: functional brain changes may precede and be more sensitive than behavioral impairments in the early pre-symptomatic stage; Meanwhile, compensatory and regulatory mechanisms often occur in the early stages of the disease, while dysfunction/decompensation and dysregulation often occur in the late stages. Overall, abnormal hyper-/hypo-activations are crucial for understanding the mechanisms of small vessel lesion-induced behavioral dysfunction, identifying potential neuromarker and developing interventions to mitigate the impact of CSVD on cognitive function.

Hypoxic oligodendrocyte precursor cell-derived VEGFA is associated with blood-brain barrier impairment.

Cerebral small vessel disease is characterised by decreased cerebral blood flow and blood-brain barrier impairments which play a key role in the development of white matter lesions. We hypothesised that cerebral hypoperfusion causes local hypoxia, affecting oligodendrocyte precursor cell-endothelial cell signalling leading to blood-brain barrier dysfunction as an early mechanism for the development of white matter lesions. Bilateral carotid artery stenosis was used as a mouse model for cerebral hypoperfusion. Pimonidazole, a hypoxic cell marker, was injected prior to humane sacrifice at day 7. Myelin content, vascular density, blood-brain barrier leakages, and hypoxic cell density were quantified. Primary mouse oligodendrocyte precursor cells were exposed to hypoxia and RNA sequencing was performed. Vegfa gene expression and protein secretion was examined in an oligodendrocyte precursor cell line exposed to hypoxia. Additionally, human blood plasma VEGFA levels were measured and correlated to blood-brain barrier permeability in normal-appearing white matter and white matter lesions of cerebral small vessel disease patients and controls. Cerebral blood flow was reduced in the stenosis mice, with an increase in hypoxic cell number and blood-brain barrier leakages in the cortical areas but no changes in myelin content or vascular density. Vegfa upregulation was identified in hypoxic oligodendrocyte precursor cells, which was mediated via Hif1α and Epas1. In humans, VEGFA plasma levels were increased in patients versus controls. VEGFA plasma levels were associated with increased blood-brain barrier permeability in normal appearing white matter of patients. Cerebral hypoperfusion mediates hypoxia induced VEGFA expression in oligodendrocyte precursor cells through Hif1α/Epas1 signalling. VEGFA could in turn increase BBB permeability. In humans, increased VEGFA plasma levels in cerebral small vessel disease patients were associated with increased blood-brain barrier permeability in the normal appearing white matter. Our results support a role of VEGFA expression in cerebral hypoperfusion as seen in cerebral small vessel disease.

Paranasal sinuses opacification on magnetic resonance imaging in relation to brain health in sporadic small vessel disease - Systematic review and pilot analysis.

BACKGROUND: The paranasal sinus mucosal thickening, visible in magnetic resonance imaging (MRI), maybe a source of inflammation in microvessels, but its relationship with small vessel disease (SVD) is unclear. We reviewed the literature and analysed a sample of patients with sporadic SVD to identify any association between paranasal sinus opacification severity and SVD neuroimaging markers. METHODS: We systematically reviewed MEDLINE and EMBASE databases up to April 2020 for studies on paranasal sinus mucosal changes in patients with SVD, cerebrovascular disease (CVD), and age-related neurodegenerative diseases. We analysed clinical and MRI data from 100 participants in a prospective study, the Mild Stroke Study 3 (ISRCTN 12113543) at 1-3, 6 and 12 months following a minor stroke to test key outcomes from the literature review. We used multivariate linear regression to explore associations between modified Lund-Mackay (LM) scores and brain, white matter hyperintensities (WMH), enlarged perivascular spaces (PVS) volumes at each time point, adjusted for baseline age, sex, diabetes, hypercholesterolaemia, hypertension and smoking. RESULTS: The literature review, after screening 3652 publications, yielded 11 primary studies, for qualitative synthesis with contradictory results, as positive associations/higher risk from 5/7 CVD studies were contradicted by the two studies with largest samples, and data from dementia studies was equally split in their outcome. From the pilot sample of patients analysed (female N = 33, mean age 67.42 (9.70) years), total LM scores had a borderline negative association with PVS in the centrum semiovale at baseline and 6 months (B = -0.25, SE = 0.14, p = 0.06) but were not associated with average brain tissue, WMH or normal-appearing white matter volumes. CONCLUSION: The inconclusive results from the literature review and empirical study justify larger studies between PVS volume and paranasal sinuses opacification in patients with sporadic SVD.

Inflammatory biomarkers and MRI visible perivascular spaces: The Framingham Heart Study.

We studied the association between inflammatory biomarkers and magnetic resonance imaging (MRI) visible perivascular spaces (PVS) in Framingham Heart Study participants free of stroke and dementia. PVS in the basal ganglia (BG) and centrum semiovale (CSO) were rated with validated methods and categorized based on counts. A mixed score of high PVS burden in neither, one or both regions was also evaluated. We related biomarkers representing various inflammatory mechanisms to PVS burden using multivariable ordinal logistic regression analysis accounting for vascular risk factors and other MRI markers of cerebral small vessel disease. Among 3604 participants (mean age 58±13 years, 47% males), significant associations were observed for intercellular adhesion molecule1, fibrinogen, osteoprotegerin, and P-selectin in relation to BG PVS, P-selectin for CSO PVS, and tumor necrosis factor receptor 2, osteoprotegerin and cluster of differentiation 40 ligand for mixed topography PVS. Therefore, inflammation may have a role in the pathogenesis of cerebral small vessel disease and perivascular drainage dysfunction represented by PVS, with different and shared inflammatory biomarkers depending on PVS topography.

Genetic analysis of the ATP11B gene in Chinese Han population with cerebral small vessel disease.

BACKGROUND: A loss-of-function mutation in ATPase phospholipid transporting 11-B (putative) (ATP11B) gene causing cerebral small vessel disease (SVD) in vivo, and a single intronic nucleotide polymorphism in ATP11B: rs148771930 that was associated with white matter hyperintensities burden in European patients with SVD, was recently identified. Our results suggest that ATP11B may not play an essential role in SVD in the Chinese population. RESULTS: We performed target region sequencing including ATP11B gene in 182 patients with sporadic SVD, and identified five rare variants and two novel variants of ATP11B. A case-control study was then performed in 524 patients and matched 550 controls to investigate the relationship between ATP11B and sporadic SVD in the Chinese Han population. Although none of these variants were significantly associated with SVD in our samples, it is important to mention that we identified a novel variant, p. G238W, which was predicted to be pathogenic in silico. This variant was present in our cohort of patients with an extremely low frequency and was absent in the controls. CONCLUSION: Our results suggest that ATP11B may not play an essential role in SVD in the Chinese population.

[Clinical practice recommendations for hereditary cerebral small vessel disease in China].

Hereditary cerebral small vessel disease (hCVSD) is a group of rare cerebrovascular diseases caused by monogenic mutation. Although there is great variability in the age of onset of hCSVD patients, the age of onset younger than 45 years old is an important indicator. The primary clinical manifestations exhibit cognitive impairment, movement disorder, psychological disturbance, and most of which are accompanied by impairment of extra-neurological systems. The main radiological and pathological features of hCVSD include lacunar infarcts, white matter hyperdensities, cerebral microbleeds and enlargement of Virchow-Robin spaces. Current representative diseases include autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy, HTRA1 related autosomal dominant cerebellar small vessel disease, collagen 4A1/2 microangiopathy, retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations, hereditary cerebral amyloidosis angiopathy, and Fabry disease. In recent years, Chinese scholars have summarized diagnostic, and treatment processes in hCSVD patients. Therefore, we organize experts engaged in the studies of hCVSD, based on the Chinese reports and referring to the relevant foreign literatures, to put forward clinical working recommendations for clinical and imaging characteristics, as well as diagnosis and treatment workflows of different types of hCVSD. The aim of this recommendation is to guide physicians to recognize hCVSD patients from those of stroke in order to obtain timely diagnosis and standard treatment.

Loss of the heterogeneous expression of flippase ATP11B leads to cerebral small vessel disease in a normotensive rat model.

Cerebral small vessel disease (SVD) is the leading cause of vascular dementia, causes a quarter of strokes, and worsens stroke outcomes. The disease is characterised by patchy cerebral small vessel and white matter pathology, but the underlying mechanisms are poorly understood. This microvascular and tissue damage has been classically considered secondary to extrinsic factors, such as hypertension, but this fails to explain the patchy nature of the disease, the link to endothelial cell (EC) dysfunction even when hypertension is absent, and the increasing evidence of high heritability to SVD-related brain damage. We have previously shown the link between deletion of the phospholipase flippase Atp11b and EC dysfunction in an inbred hypertensive rat model with SVD-like pathology and a single nucleotide polymorphism (SNP) in ATP11B associated with human sporadic SVD. Here, we generated a novel normotensive transgenic rat model, where Atp11b is deleted, and show pathological, imaging and behavioural changes typical of those in human SVD, but that occur without hypertension. Atp11bKO rat brain and retinal small vessels show ECs with molecular and morphological changes of dysfunction, with myelin disruption in a patchy pattern around some but not all brain small vessels, similar to the human brain. We show that ATP11B/ATP11B is heterogeneously expressed in ECs in normal rat and human brain even in the same transverse section of the same blood vessel, suggesting variable effects of the loss of ATP11B on each vessel and an explanation for the patchy nature of the disease. This work highlights a link between inherent EC dysfunction and vulnerability to SVD white matter damage with a marked heterogeneity of ECs in vivo which modulates this response, occurring even in the absence of hypertension. These findings refocus our strategies for therapeutics away from antihypertensive (and vascular risk factor) control alone and towards ECs in the effort to provide alternative targets to prevent a major cause of stroke and dementia.

Cerebral Microbleeds Are Associated With Increased Brain Iron and Cognitive Impairment in Patients With Cerebral Small Vessel Disease: A Quantitative Susceptibility Mapping Study.

BACKGROUND: Cerebral microbleeds (CMBs) have been recognized to play an important role in cognitive impairment of cerebral small vessel disease (CSVD) patients. However, the mechanism of this effect is still unclear. PURPOSE: Comparing the susceptibility values in the selected subcortical gray matter structures of CSVD patients without CMBs (CSVD-N) and with CMBs (CSVD-C) as well as healthy controls (HCs). STUDY TYPE: Prospective. SUBJECTS: Sixty-nine CSVD patients and 28 HCs were included; 24 CSVD patients (34.78%) had CMBs and 45 CSVD patients (65.22%) had no CMBs. FIELD STRENGTH/SEQUENCE: All subjects were imaged on a 3.0 T MR scanner. The protocol consisted of a three-dimensional (3D) T1-weighted sequence and a 3D multi-echo gradient echo (mGRE) sequence. Brain QSM maps were computed from mGRE data using the morphology-enabled dipole inversion with automatic uniform cerebrospinal fluid zero reference algorithm (MEDI+0). ASSESSMENT: The mean susceptibility value within each region of interest was recorded. All participants underwent the cognitive assessment. Brain iron deposition burden of CMB lesions of every CSVD-C patient was computed. STATISTICAL TESTS: One-way analysis of variance test followed by Tukey's honest significance test and Kruskal-Wallis test were used with significance level of 0.05. Stepwise multivariate linear analysis was used to explore the factors influencing cognitive scores. RESULTS: Montreal cognitive assessment (MoCA), trail-making test (TMT)-A and TMT-B scores in the three groups were significantly different (all P < 0.05). Stepwise multivariate linear regression analysis revealed that the factors influenced MoCA scores were having CMBs (P < 0.05), white matter hyperintensities (P < 0.05), lacunes (P < 0.05) in brain, and the brain iron deposition burden of CMB lesions (P < 0.05) and for TMT scores (TMT-A + TMT-B), the influencing factors were age (P < 0.05), education years (P < 0.05), and the brain iron deposition burden of CMB lesions (P < 0.05). DATA CONCLUSION: The higher iron deposition burden of CMB lesions in brain may be an imaging quantitative marker of cognitive decline in patients with CSVD-C. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 2.

Mizagliflozin, a selective SGLT1 inhibitor, improves vascular cognitive impairment in a mouse model of small vessel disease.

Previously, we showed that sodium/glucose cotransporter 1 (SGLT1) participates in vascular cognitive impairment in small vessel disease. We hypothesized that SGLT1 inhibitors can improve the small vessel disease induced-vascular cognitive impairment. We examined the effects of mizagliflozin, a selective SGLT1 inhibitor, and phlorizin, a non-selective SGLT inhibitor, on vascular cognitive impairment in a mouse model of small vessel disease. Small vessel disease was created using a mouse model of asymmetric common carotid artery surgery (ACAS). Two and/or 4 weeks after ACAS, all experiments were performed. Cerebral blood flow (CBF) was decreased in ACAS compared with sham-operated mice. Phlorizin but not mizagliflozin reversed the decreased CBF of ACAS mice. Both mizagliflozin and phlorizin reversed the ACAS-induced decrease in the latency to fall in a wire hang test of ACAS mice. Moreover, they reversed the ACAS-induced longer escape latencies in the Morris water maze test of ACAS mice. ACAS increased SGLT1 and proinflammatory cytokine gene expressions in mouse brains and phlorizin but not mizagliflozin normalized all gene expressions in ACAS mice. Hematoxylin/eosin staining demonstrated that they inhibited pyknotic cell death in the ACAS mouse hippocampus. In PC12HS cells, IL-1ß increased SGLT1 expression and decreased survival rates of cells. Both mizagliflozin and phlorizin increased the survival rates of IL-1ß-treated PC12HS cells. These results suggest that mizagliflozin and phlorizin can improve vascular cognitive impairment through the inhibition of neural SGLT1 and phlorizin also does so through the improvement of CBF in a mouse model of small vessel disease.

Role of Purinergic Signalling in Endothelial Dysfunction and Thrombo-Inflammation in Ischaemic Stroke and Cerebral Small Vessel Disease.

The cerebral endothelium is an active interface between blood and the central nervous system. In addition to being a physical barrier between the blood and the brain, the endothelium also actively regulates metabolic homeostasis, vascular tone and permeability, coagulation, and movement of immune cells. Being part of the blood-brain barrier, endothelial cells of the brain have specialized morphology, physiology, and phenotypes due to their unique microenvironment. Known cardiovascular risk factors facilitate cerebral endothelial dysfunction, leading to impaired vasodilation, an aggravated inflammatory response, as well as increased oxidative stress and vascular proliferation. This culminates in the thrombo-inflammatory response, an underlying cause of ischemic stroke and cerebral small vessel disease (CSVD). These events are further exacerbated when blood flow is returned to the brain after a period of ischemia, a phenomenon termed ischemia-reperfusion injury. Purinergic signaling is an endogenous molecular pathway in which the enzymes CD39 and CD73 catabolize extracellular adenosine triphosphate (eATP) to adenosine. After ischemia and CSVD, eATP is released from dying neurons as a damage molecule, triggering thrombosis and inflammation. In contrast, adenosine is anti-thrombotic, protects against oxidative stress, and suppresses the immune response. Evidently, therapies that promote adenosine generation or boost CD39 activity at the site of endothelial injury have promising benefits in the context of atherothrombotic stroke and can be extended to current CSVD known pathomechanisms. Here, we have reviewed the rationale and benefits of CD39 and CD39 therapies to treat endothelial dysfunction in the brain.

Intracranial arteriosclerosis is related to cerebral small vessel disease: a prospective cohort study.

Intracranial arteriosclerosis has been increasingly recognized as a risk factor for cognitive impairment and even dementia. A possible mechanism linking intracranial arteriosclerosis to cognitive impairment and dementia involves structural brain changes including cerebral small vessel disease (CSVD). To assess whether intracranial carotid artery calcification (ICAC) and vertebrobasilar artery calcification (VBAC), as proxies for intracranial arteriosclerosis, are related to CSVD. Within the population-based Rotterdam Study, between 2003 and 2006 a computed tomography (CT)-based measurement of ICAC and VBAC and at least one magnetic resonance imaging (MRI) measurement of structural brain changes were performed from 2005 onwards in 1,489 participants. To estimate the burden of calcification independent of age, we computed age-adjusted percentile curves for ICAC and VBAC separately, based on the calcification volumes. Using the longitudinal MRI data, we assessed whether a larger calcification burden accelerates structural brain changes using appropriate statistical models for repeated outcome measures. A larger burden of ICAC and VBAC was associated with an increase of CSVD markers accelerating over time. A larger burden of ICAC and VBAC was not significantly (p > 0.05) associated with accelerated brain atrophy. Arteriosclerosis is related to accelerating structural brain changes over time.

Notch3 Signaling and Aggregation as Targets for the Treatment of CADASIL and Other NOTCH3-Associated Small-Vessel Diseases.

Mutations in the NOTCH3 gene can lead to small-vessel disease in humans, including the well-characterized cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a condition caused by NOTCH3 mutations altering the number of cysteine residues in the extracellular domain of Notch3. Growing evidence indicates that other types of mutations in NOTCH3, including cysteine-sparing missense mutations or frameshift and premature stop codons, can lead to small-vessel disease phenotypes of variable severity or penetrance. There are currently no disease-modifying therapies for small-vessel disease, including those associated with NOTCH3 mutations. A deeper understanding of underlying molecular mechanisms and clearly defined targets are needed to promote the development of therapies. This review discusses two key pathophysiological mechanisms believed to contribute to the emergence and progression of small-vessel disease associated with NOTCH3 mutations: abnormal Notch3 aggregation and aberrant Notch3 signaling. This review offers a summary of the literature supporting and challenging the relevance of these mechanisms, together with an overview of available preclinical experiments derived from these mechanisms. It highlights knowledge gaps and future research directions. In view of recent evidence demonstrating the relatively high frequency of NOTCH3 mutations in the population, and their potential role in promoting small-vessel disease, progress in the development of therapies for NOTCH3-associated small-vessel disease is urgently needed.

Neuropathologic Findings in Chronic Kidney Disease (CKD).

Studying the neuropathologic autopsy findings in subjects with chronic kidney disease (CKD) or chronic renal failure (CRF) is difficult for several reasons: etiology of the CKD may be heterogeneous, affected patients may have one or more major co-morbidities that themselves can cause significant neurologic disease, and agonal events may result in significant findings that were of minimal significance earlier in a patient's life. We studied the constellation of neuropathologic abnormalities in 40 autopsy brains originating from subjects of ages 34-95 years (no children in the study). The most common pathologic change was that of ischemic infarcts (cystic, lacunar and/or microinfarcts), which were seen in over half of subjects. These were associated with both large artery atherosclerosis and arteriolosclerosis (A/S), the latter finding being present in 29/40 subjects. Charcot-Bouchard microaneurysms were present in the brains of three subjects, in one case associated with severe amyloid angiopathy. Microvascular calcinosis (medial sclerosis in the case of arterioles) was seen in the basal ganglia (n=8) and/or endplate region of the hippocampus (n=7) and occasional ischemic infarcts in one brain showed severe calcification. Sequelae of cerebrovascular disease (especially A/S or microvascular disease) are a common neuropathologic substrate for neurologic disability and brain lesions in this complex group of patients. Regulation of calcium metabolism within brain microvessel walls may be worthy of further research in both human brain specimens and animal models.

Cerebral Microangiopathy in Leukoencephalopathy With Cerebral Calcifications and Cysts: A Pathological Description.

Leukoencephalopathy with calcifications and cysts (LCC) is a neurological syndrome recently associated with pathogenic variants in SNORD118. We report autopsy neuropathological findings from an individual with genetically confirmed LCC. Histologic studies included staining of formalin-fixed paraffin-embedded tissue sections by hematoxylin and eosin, elastic van Gieson, and luxol fast blue. Immunohistochemistry stains against glial fibrillary acidic protein, proteolipid protein, phosphorylated neurofilament, CD31, alpha-interferon, LN3, and inflammatory markers were performed. Gross examination revealed dark tan/gray appearing white matter with widespread calcifications. Microscopy revealed a diffuse destructive process due to a vasculopathy with secondary ischemic lesions and mineralization. The vasculopathy involved clustered small vessels, resembling vascular malformations, and sporadic lymphocytic infiltration of vessel walls. The white matter was also diffusely abnormal, with concurrent loss of myelin and axons, tissue rarefaction with multifocal cystic degeneration, and the presence of foamy macrophages, secondary calcifications, and astrogliosis. The midbrain, pons, and cerebellum were diffusely involved. It is not understood why variants in SNORD118 result in a disorder that predominantly causes neurological disease and significantly disrupts the cerebral vasculature. Clinical and radiological benefit was recently reported in an LCC patient treated with Bevacizumab; it is important that these patients are rapidly diagnosed and trial of this treatment modality is considered in appropriate circumstances.

An Iatrogenic Model of Brain Small-Vessel Disease: Post-Radiation Encephalopathy.

We studied 114 primitive cerebral neoplasia, that were surgically treated, and underwent radiotherapy (RT), and compared their results to those obtained by 190 patients diagnosed with subcortical vascular dementia (sVAD). Patients with any form of primitive cerebral neoplasia underwent whole-brain radiotherapy. All the tumor patients had regional field partial brain RT, which encompassed each tumor, with an average margin of 2.6 cm from the initial target tumor volume. We observed in our patients who have been exposed to a higher dose of RT (30-65 Gy) a cognitive and behavior decline similar to that observed in sVAD, with the frontal dysexecutive syndrome, apathy, and gait alterations, but with a more rapid onset and with an overwhelming effect. Multiple mechanisms are likely to be involved in radiation-induced cognitive impairment. The active site of RT brain damage is the white matter areas, particularly the internal capsule, basal ganglia, caudate, hippocampus, and subventricular zone. In all cases, radiation damage inside the brain mainly focuses on the cortical-subcortical frontal loops, which integrate and process the flow of information from the cortical areas, where executive functions are "elaborated" and prepared, towards the thalamus, subthalamus, and cerebellum, where they are continuously refined and executed. The active mechanisms that RT drives are similar to those observed in cerebral small vessel disease (SVD), leading to sVAD. The RT's primary targets, outside the tumor mass, are the blood-brain barrier (BBB), the small vessels, and putative mechanisms that can be taken into account are oxidative stress and neuro-inflammation, strongly associated with the alteration of NMDA receptor subunit composition.