Bone marrow-derived progenitor cells in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy

ER stress induced immunopathology involving complement in CADASIL: implications for therapeutics

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by NOTCH3 mutations. Typical CADASIL is characterised by subcortical ischemic strokes due to severe arteriopathy and fibrotic thickening of small arteries. Arteriolar vascular smooth muscle cells (VSMCs) are the key target in CADASIL, but the potential mechanisms involved in their degeneration are still unclear. Focusing on cerebral microvessels in the frontal and anterior temporal lobes and the basal ganglia, we used advanced proteomic and immunohistochemical methods to explore the extent of inflammatory and immune responses in CADASIL subjects compared to similar age normal and other disease controls. There was variable loss of VSMC in medial layers of arteries in white matter as well as the cortex, that could not be distinguished whether NOTCH3 mutations were in the epidermal growth factor (EGFr) domains 1-6 or EGFr7-34. Proteomics of isolated cerebral microvessels showed alterations in several proteins, many associated with endoplasmic reticulum (ER) stress including heat shock proteins. Cerebral vessels with sparsely populated VSMCs also attracted robust accrual of perivascular microglia/macrophages in order CD45+ > CD163+ > CD68+cells, with > 60% of vessel walls exhibiting intercellular adhesion molecule-1 (ICAM-1) immunoreactivity. Functional VSMC cultures bearing the NOTCH3 Arg133Cys mutation showed increased gene expression of the pro-inflammatory cytokine interleukin 6 and ICAM-1 by 16- and 50-fold, respectively. We further found evidence for activation of the alternative pathway of complement. Immunolocalisation of complement Factor B, C3d and C5-9 terminal complex but not C1q was apparent in ~ 70% of cerebral vessels. Increased complement expression was corroborated in > 70% of cultured VSMCs bearing the Arg133Cys mutation independent of N3ECD immunoreactivity. Our observations suggest that ER stress and other cellular features associated with arteriolar VSMC damage instigate robust localized inflammatory and immune responses in CADASIL. Our study has important implications for immunomodulation approaches to counter the characteristic arteriopathy of CADASIL.

Vascular Dementia and Crosstalk Between the Complement and Coagulation Systems

Vascular Dementia (VaD) is a neurocognitive disorder caused by reduced blood flow to the brain tissue, resulting in infarction, and is the second most common type of dementia. The complement and coagulation systems are evolutionary host defence mechanisms activated by acute tissue injury to induce inflammation, clot formation and lysis; recent studies have revealed that these systems are closely interlinked. Overactivation of these systems has been recognised to play a key role in the pathogenesis of neurological disorders such as Alzheimer's disease and multiple sclerosis, however their role in VaD has not yet been extensively reviewed. This review aims to bridge the gap in knowledge by collating current understanding of VaD to enable identification of complement and coagulation components involved in the pathogenesis of this disorder that may have their effects amplified or supressed by crosstalk. Exploration of these mechanisms may unveil novel therapeutic targets or biomarkers that would improve current treatment strategies for VaD.

CADASIL from Bench to Bedside: Disease Models and Novel Therapeutic Approaches

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic disease caused by NOTCH3 mutations and characterized by typical clinical, neuroradiological, and pathological features. NOTCH3 belongs to a family of highly conserved transmembrane receptors rich of epidermal growth factor repeats, mostly expressed in vascular smooth muscle cells and pericytes, which perform essential developmental functions and are involved in tissues maintenance and renewal. To date, no therapeutic option for CADASIL is available except for few symptomatic treatments. Novel in vitro and in vivo models are continuously explored with the aim to investigate underlying pathogenic mechanisms and to test novel therapeutic approaches. In this scenario, knock-out, knock-in, and transgenic mice studies have generated a large amount of information on molecular and biological aspects of CADASIL, despite that they incompletely reproduce the human phenotype. Moreover, the field of in vitro models has been revolutionized in the last two decades by the introduction of induced pluripotent stem cells (iPSCs) technology. As a consequence, novel therapeutic approaches, including immunotherapy, growth factors administration, and antisense oligonucleotides, are currently under investigation. While waiting that further studies confirm the promising results obtained, the data reviewed suggest that our therapeutic approach to the disease could be transformed, generating new hope for the future.

Pathophysiological Mechanisms and Potential Therapeutic Targets in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), is a hereditary small-vessels angiopathy caused by mutations in the NOTCH 3 gene, located on chromosome 19, usually affecting middle-ages adults, whose clinical manifestations include migraine with aura, recurrent strokes, mood disorders, and cognitive impairment leading to dementia and disability. In this review, we provide an overview of the current knowledge on the pathogenic mechanisms underlying the disease, focus on the corresponding therapeutic targets, and discuss the most promising treatment strategies currently under investigations. The hypothesis that CADASIL is an appropriate model to explore the pathogenesis of sporadic cerebral small vessel disease is also reviewed.

Emerging Biomarkers in Vascular Cognitive Impairment and Dementia: From Pathophysiological Pathways to Clinical Application

Vascular pathology is the second most common neuropathology of dementia after Alzheimer’s disease (AD), with small vessels disease (SVD) being considered the major cause of vascular cognitive impairment and dementia (VCID). This review aims to evaluate pathophysiological pathways underlying a diagnosis of VCID. Firstly, we will discuss the role of endothelial dysfunction, blood-brain barrier disruption and neuroinflammation in its pathogenesis. Then, we will analyse different biomarkers including the ones of inflammatory responses to central nervous system tissue injuries, of coagulation and thrombosis and of circulating microRNA. Evidences on peripheral biomarkers for VCID are still poor and large-scale, prospectively designed studies are needed to translate these findings into clinical practice, in order to set different combinations of biomarkers to use for differential diagnosis among types of dementia.

Cerebral Small Vessel Disease: A Review Focusing on Pathophysiology, Biomarkers, and Machine Learning Strategies

Cerebral small vessel disease (cSVD) has a crucial role in lacunar stroke and brain hemorrhages and is a leading cause of cognitive decline and functional loss in elderly patients. Based on underlying pathophysiology, cSVD can be subdivided into amyloidal and non-amyloidal subtypes. Genetic factors of cSVD play a pivotal role in terms of unraveling molecular mechanism. An important pathophysiological mechanism of cSVD is blood-brain barrier leakage and endothelium dysfunction which gives a clue in identification of the disease through circulating biological markers. Detection of cSVD is routinely carried out by key neuroimaging markers including white matter hyperintensities, lacunes, small subcortical infarcts, perivascular spaces, cerebral microbleeds, and brain atrophy. Application of neural networking, machine learning and deep learning in image processing have increased significantly for correct severity of cSVD. A linkage between cSVD and other neurological disorder, such as Alzheimer's and Parkinson's disease and non-cerebral disease, has also been investigated recently. This review draws a broad picture of cSVD, aiming to inculcate new insights into its pathogenesis and biomarkers. It also focuses on the role of deep machine strategies and other dimensions of cSVD by linking it with several cerebral and non-cerebral diseases as well as recent advances in the field to achieve sensitive detection, effective prevention and disease management.

Vitamin D levels in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Besides its well known function on bone metabolism, vitamin D role in cerebrovascular pathologies including cerebral small vessel disease has been confirmed by recent meta-analysis. In this study, we measured vitamin D levels in 56 Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) patients (mean age 49.9) with no or minimal disability (modified Ranking Score, mRS ≤2) and in 56 age, sex and seasonality matched healthy controls. History of ischemic events was recorded and cognitive functions were assessed using the Mini-Mental State Examination. White matter hyperintensities on brain T2-weighted magnetic resonance images were classified according to a modified Fazekas scale. Comparison of vitamin D levels between patients and controls showed significant lower values (p < 0.05) in no-to-mild CADASIL patients and a higher number of subjects with severe deficiency [25(OH)D <10 ng/ml]. Vitamin D levels did not correlate with vascular risk factors, clinical data or Fazekas score. The role of vitamin D is worth to be further explored in prospective studies.

Circulating Biomarkers in Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy Patients

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebral microangiopathy presenting with variable features, including migraine, psychiatric disorders, stroke, and cognitive decline and variable disability. On neuroimaging, CADASIL is characterized by leukoencephalopathy, multiple lacunar infarcts, and microbleeds. Previous studies suggest a possible role of endothelial impairment in the pathogenesis of the disease.

METHODS

We assessed plasma levels of von Willebrand factor (vWF) and thrombomodulin (TM) and the blood levels of endothelial progenitor cells (EPCs) and circulating progenitor cells (CPCs) in 49 CADASIL patients and 49 age-matched controls and their association with clinical/functional and neuroimaging features.

RESULTS

In multivariate analysis, CADASIL patients had significantly higher vWF and lower EPC levels. TM levels were similar in the 2 groups. CADASIL patients with a more severe clinical phenotype (history of stroke or dementia) presented lower CPC levels in comparison with patients with a milder phenotype. On correlation analysis, lower CPC levels were associated with worse performances on neuropsychological, motor and functional tests, and with higher lesion load on brain magnetic resonance imaging (degree of leukoencephalopathy and number of lacunar infarcts).

CONCLUSIONS

This is the first CADASIL series in which multiple circulating biomarkers have been studied. Our findings support previous studies on the presence and the possible modulating effect of endothelial impairment in the disease. Furthermore, our research data suggest that blood CPCs may be markers of disease severity.

Circulating Progenitor Cells is Linked to Cognitive Decline in Healthy Adults

OBJECTIVE

Cognitive and cardiovascular disorders share many risk factors. Higher bone-marrow derived progenitor cells (PC) in blood are associated with lower rates of cardiovascular events but the association of PC with cognitive function is unclear. The objective of this study was to assess the association between PC and cognition in a sample of healthy adults enrolled in a cohort study.

MATERIALS AND METHODS

A random sample of employees at Emory University and Georgia Institute of Technology were followed for 4 years and underwent yearly vascular and cognitive assessment (N = 430, mean age = 49.2 years, 70% women, and 27% African-American). Cognition was assessed using computerized versions of 15 cognitive tests and principal component analysis was used for deriving cognitive scores: executive function, memory and working memory. PC were defined as mononuclear cells with specific surface markers (7 phenotypes). Decreased cognition in a domain was defined as performing below the lowest quartile for the corresponding domain at baseline. Generalized estimating equations were used to investigate associations between PC and cognition.

RESULTS

Higher PC levels at baseline were associated with lower risk of cognitive decline in the executive and working memory domains during the follow-up period (P < 0.002 for all PC phenotypes). Further, the degree of decline in PC over the follow-up period was correlated with a corresponding decline in performances in all 3 cognitive domains over the same period (All P < 0.002).

CONCLUSION

Lower PC and greater yearly declines in PC are associated with greater cognitive decline. These findings suggest the role for PC in neurocognitive aging.

Circulating biologic markers of endothelial dysfunction in cerebral small vessel disease: A review

The term cerebral small vessel disease (SVD) refers to a group of pathologic processes with various etiologies that affect small arteries, arterioles, venules, and capillaries of the brain. Magnetic resonance imaging (MRI) correlates of SVD are lacunes, recent small subcortical infarcts, white-matter hyperintensities, enlarged perivascular spaces, microbleeds, and brain atrophy. Endothelial dysfunction is thought to have a role in the mechanisms leading to SVD-related brain changes, and the study of endothelial dysfunction has been proposed as an important step for a better comprehension of cerebral SVD. Among available methods to assess endothelial function in vivo, measurement of molecules of endothelial origin in peripheral blood is currently receiving selective attention. These molecules include products of endothelial cells that change when the endothelium is activated, as well as molecules that reflect endothelial damage and repair. This review examines the main molecular factors involved in both endothelial function and dysfunction, and the evidence linking endothelial dysfunction with cerebral SVD, and gives an overview of clinical studies that have investigated the possible association between endothelial circulating biomarkers and SVD-related brain changes.

Effects of sapropterin on endothelium-dependent vasodilation in patients with CADASIL: a randomized controlled trial

BACKGROUND AND PURPOSE

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a rare autosomal dominant disorder caused by NOTCH3 mutations, is characterized by vascular smooth muscle and endothelial cells abnormalities, altered vasoreactivity, and recurrent lacunar infarcts. Vasomotor function may represent a key factor for disease progression. Tetrahydrobiopterin, essential cofactor for nitric oxide synthesis in endothelial cells, ameliorates endothelial function. We assessed whether supplementation with sapropterin, a synthetic tetrahydrobiopterin analog, improves endothelium-dependent vasodilation in CADASIL patients.

METHODS

In a 24-month, multicenter randomized, double-blind, placebo-controlled trial, CADASIL patients aged 30 to 65 years were randomly assigned to receive placebo or sapropterin 200 to 400 mg BID. The primary end point was change in the reactive hyperemia index by peripheral arterial tonometry at 24 months. We also assessed the safety and tolerability of sapropterin. Analysis was done by intention-to-treat.

RESULTS

The intention-to-treat population included 61 patients. We found no significant difference between sapropterin (n=32) and placebo (n=29) in the primary end point (mean difference in reactive hyperemia index by peripheral arterial tonometry changes 0.19 [95% confidence interval, -0.18, 0.56]). Reactive hyperemia index by peripheral arterial tonometry increased after 24 months in 37% of patients on sapropterin and in 28% on placebo; however, after adjustment for age, sex, and clinical characteristics, improvement was not associated with treatment arm. The proportion of patients with adverse events was similar on sapropterin and on placebo (50% versus 48.3%); serious adverse events occurred in 6.3% versus 13.8%, respectively.

CONCLUSIONS

Sapropterin was safe and well-tolerated at the average dose of 5 mg/kg/day, but did not affect endothelium-dependent vasodilation in CADASIL patients.

CLINICAL TRIAL REGISTRATION URL

https://www.clinicaltrialsregister.eu. Unique identifier: 2007-004370-55.

Novel pathological features and potential therapeutic approaches for CADASIL: insights obtained from a mouse model of CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common condition of hereditary stroke and vascular dementia. CADASIL is caused by Notch3 mutation, leading to progressive degeneration of vascular smooth muscle cells (vSMCs) of the small arteries in the brain. However, the pathogenesis of CADASIL remains largely unknown, and treatment that can stop or delay the progression of CADASIL is not yet available. Using both wild type mice and transgenic mice carrying the human mutant Notch3 gene (CADASIL mice), we have recently characterized the pathological features of CADASIL and determined the therapeutic efficacy of two hematopoietic growth factors, stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) in CADASIL. Our findings have revealed novel pathological changes in the endothelium of cerebral capillaries and in the neural stem cells (NSCs). We have also observed the impairment of cognitive function in CADASIL mice. Moreover, SCF+G-CSF treatment improves cognitive function, inhibits Notch3 mutation-induced vSMC degeneration, cerebral blood bed reduction, cerebral capillary damage, and NSC loss, and increases neurogenesis and angiogenesis. Here we compile an overview of our recently published studies, which provide new insights into understanding the pathogenesis of CADASIL and developing therapeutic strategies for this devastating neurological disease.

Diabetes-associated macrovascular complications: cell-based therapy a new tool?

Diabetes mellitus and its ongoing macrovascular complications represent one of the major health problems around the world. Rise in obesity and population ages correlate with the increased incidence of diabetes. This highlights the need for novel approaches to prevent and treat this pandemic. The discovery of a reservoir of stem/progenitors in bone marrow and in mesenchymal tissue has attracted interest of both biologists and clinicians. A number of preclinical and clinical trials were developed to explore their potential clinical impact, as target or vehicle, in different clinical settings, including diabetes complications. Currently, bone marrow, peripheral blood, mesenchymal, and adipose tissues have been used as stem/progenitor cell sources. However, evidences have been provided that both bone marrow and circulating progenitor cells are dysfunctional in diabetes. These observations along with the growing advantages in genetic manipulation have spurred researchers to exploit ex vivo manipulated cells to overcome these hurdles. In this article, we provide an overview of data relevant to stem-progenitors potential clinical application in revascularization and/or vascular repair. Moreover, the hurdles at using progenitor cells in diabetic patients will be also discussed.

Endothelial progenitor cells in acute ischemic stroke

OBJECTIVES

The levels of circulating endothelial progenitor cells (EPCs) in ischemic stroke have not been studied extensively and reported results are inconsistent. We aimed to investigate the time course, the prognostic relevance, and the variables associated with EPC counts in patients with ischemic stroke at different time points.

MATERIAL AND METHODS

We studied prospectively 146 consecutive patients with ischemic stroke within the first 48 h from the onset of symptoms (baseline). We evaluated demographic data, classical vascular risk factors, treatment with thrombolysis and statins, stroke etiology, National Institute of Health and Stroke Scale score and outcome (favorable when Rankin scale score 0-2). Blood samples were collected at baseline, at day 7 after stroke (n = 121) and at 3 months (n = 92). The EPC were measured by flow cytometry.

RESULTS

We included 146 patients with a mean age of 70.8 ± 12.2 years. The circulating EPC levels were higher on day 7 than at baseline or at 3 months (P = 0.045). Pretreatment with statins (odds ratio [OR] 3.11, P = 0.008) and stroke etiology (P = 0.032) were predictive of EPC counts in the baseline sample. EPC counts were not associated with stroke severity or functional outcome in all the patients. However, using multivariate analyses, a better functional outcome was found in patients with higher EPC counts in large-artery atherosclerosis and small-vessel disease etiologic subtypes.

CONCLUSIONS

After acute ischemic stroke, circulating EPC counts peaked at day 7. Pretreatment with statins increased the levels of EPC. In patients with large-artery atherosclerosis and small-vessel disease subtypes, higher counts were related to better outcome at 3 months.

Influence of vascular risk factors and neuropsychological profile on functional performances in CADASIL: results from the MIcrovascular LEukoencephalopathy Study (MILES)

BACKGROUND AND PURPOSE

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebral small vessel disease that may lead to disability and whose phenotype modulators are still unknown.

METHODS

In the MIcrovascular LEukoencephalopathy Study (MILES), we assessed the influence of vascular risk factors and the effect of different cognitive domains (memory, psychomotor speed and executive functions) performances on functional abilities in CADASIL in comparison with age-related leukoencephalopathy (ARL).

RESULTS

We evaluated 51 CADASIL patients (mean age 50.3 ± 13.8 years, 47.1% males) and 68 ARL patients (70.6 ± 7.4 years, 58.8% males). Considering vascular risk factors, after adjustment for age, CADASIL patients had higher mean BMI values than ARL patients. Stroke history frequency was similar in the two groups. After adjustment for age, more CADASIL patients were disabled (impaired on ≥ 2 items of the Instrumental Activities of Daily Living scale) in comparison with ARL patients, and CADASIL patients had worse functional performances evaluated with the Disability Assessment for Dementia (DAD) scale. In CADASIL patients, hypertension was related to both DAD score and disability. The cognitive profile of CADASIL and ARL patients was similar, but on a stepwise linear regression analysis functional performances were mainly associated with the memory index (β = -0.418, P < 0.003) in CADASIL patients and the executive function index (β = -0.321, P = 0.028) in ARL.

CONCLUSIONS

This study suggests that hypertension may contribute to functional impairment in CADASIL and that memory impairment has a large influence on functional decline in contrast with that observed in a sample of subjects with ARL.

Astragaloside IV attenuates Toll-like receptor 4 expression via NF-κB pathway under high glucose condition in mesenchymal stem cells

Diabetic hyperglycemia causes a variety of pathological changes. Astragaloside IV (AS-IV) was widely used for the treatment of cardiovascular diseases in China. The aim of this study was to determine the effect of AS-IV on bone marrow mesenchymal stem cells (MSCs) and the underlying mechanism in diabetes. We used reverse transcription polymerase chain reaction and western blotting to determine the expression of Toll-like receptor 4 (TLR4), matrix metalloproteinase-2 (MMP-2) and NF-κB p65 in MSCs under high glucose (HG) with or without pretreatment with AS-IV. The surface expression of TLR4 was checked by flow cytometry and the expression of TNF-α and MCP-1 were detected by ELISA in diabetes patients treated with AS-IV. AS-IV promoted the proliferation of MSCs and attenuated the increased expression of TLR4 induced by HG. In addition, AS-IV decreased the HG-induced translocation of NF-κB p65 and increased the MMP-2 expression in MSCs. AS-IV decreased the TLR4, TNF-α and MCP-1 expression in patients. Collectively,our data revealed that AS-IV attenuated TLR4 expression through the NF-κB signaling pathway in MSCs.

The Cerebral Autosomal-Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy (CADASIL) Scale: a screening tool to select patients for NOTCH3 gene analysis

BACKGROUND AND PURPOSE

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) phenotype is highly variable, and, although the full clinical-neuroimaging picture may be suggestive of the disease, no characteristic is pathognomonic. Thus, a genetic test remains the diagnostic gold standard, but because it is costly and time-consuming, a pregenetic screening appears desirable. We aimed at developing the CADASIL scale, a screening tool to be applied in the clinical setting.

METHODS

A preliminary scale was created assigning weighted scores to common disease features based on their frequencies obtained in a pooled analysis of selected international CADASIL series. The accuracy of the scale versus the genetic diagnosis was tested with receiver operating characteristic analysis after the application of this scale to 61 CADASIL and 54 NOTCH3-negative patients (no pathogenic mutation on exons 2-23 of the NOTCH3 gene). To improve the scale accuracy, we then developed an ad hoc optimization algorithm to detect the definitive scale. A third group of 39 patients affected by sporadic small-vessel disease was finally included in the algorithm to evaluate the stability of the scale.

RESULTS

The cutoff score of the definitive CADASIL scale had a sensitivity of 96.7% and a specificity of 74.2%. This scale was robust to contamination of patients with sporadic small-vessel disease.

CONCLUSIONS

The CADASIL scale is a simple and sufficiently accurate screening tool to select patients with a high probability to be affected by the disease and therefore to be subjected to the genetic testing.

New vessels after stroke: postischemic neovascularization and regeneration

The formation of new blood vessels after acute ischemic stroke is one of the most promising approaches to future therapies in the emerging field of stroke medicine. Angiogenesis and postnatal vasculogenesis are the underlying mechanisms of the formation of new blood vessels. Bone marrow-derived endothelial progenitor cells (EPCs) are thought to play an important role in neovascularization and during the regenerative processes after a vascular injury as well as in the maintenance of endothelial integrity. This review summarizes possible mechanisms of angiogenesis, postischemic neovascularization and regeneration with a focus on the potential role of EPCs as a risk marker and as a therapeutic target in stroke medicine.