scholarly journals The Role of Basement Membranes in Cerebral Amyloid Angiopathy

2020 ◽  
Vol 11 ◽  
Author(s):  
Matthew D. Howe ◽  
Louise D. McCullough ◽  
Akihiko Urayama
Keyword(s):  
Risk Factors ◽  
Cognitive Decline ◽  
Cerebral Amyloid Angiopathy ◽  
Functional Impairment ◽  
Amyloid Β ◽  
Basement Membranes ◽  
Amyloid Angiopathy ◽  
Transport Pathways ◽  
Cerebral Amyloid ◽  
The Brain

Dementia is a neuropsychiatric syndrome characterized by cognitive decline in multiple domains, often leading to functional impairment in activities of daily living, disability, and death. The most common causes of age-related progressive dementia include Alzheimer’s disease (AD) and vascular cognitive impairment (VCI), however, mixed disease pathologies commonly occur, as epitomized by a type of small vessel pathology called cerebral amyloid angiopathy (CAA). In CAA patients, the small vessels of the brain become hardened and vulnerable to rupture, leading to impaired neurovascular coupling, multiple microhemorrhage, microinfarction, neurological emergencies, and cognitive decline across multiple functional domains. While the pathogenesis of CAA is not well understood, it has long been thought to be initiated in thickened basement membrane (BM) segments, which contain abnormal protein deposits and amyloid-β (Aβ). Recent advances in our understanding of CAA pathogenesis link BM remodeling to functional impairment of perivascular transport pathways that are key to removing Aβ from the brain. Dysregulation of this process may drive CAA pathogenesis and provides an important link between vascular risk factors and disease phenotype. The present review summarizes how the structure and composition of the BM allows for perivascular transport pathways to operate in the healthy brain, and then outlines multiple mechanisms by which specific dementia risk factors may promote dysfunction of perivascular transport pathways and increase Aβ deposition during CAA pathogenesis. A better understanding of how BM remodeling alters perivascular transport could lead to novel diagnostic and therapeutic strategies for CAA patients.

scholarly journals The Pattern of AQP4 Expression in the Ageing Human Brain and in Cerebral Amyloid Angiopathy

2020 ◽  
Vol 21 (4) ◽  
pp. 1225
Author(s):  
Raisah Owasil ◽  
Ronan O’Neill ◽  
Abby Keable ◽  
Jacqui Nimmo ◽  
Matthew MacGregor Sharp ◽  
...  
Keyword(s):  
White Matter ◽  
Cerebral Amyloid Angiopathy ◽  
Amyloid Β ◽  
Basement Membranes ◽  
Amyloid Angiopathy ◽  
Aqp4 Expression ◽  
Fluid Uptake ◽  
Arterial Drainage ◽  
Cerebral Amyloid ◽  
The Brain

In the absence of lymphatics, fluid and solutes such as amyloid-β (Aβ) are eliminated from the brain along basement membranes in the walls of cerebral capillaries and arteries—the Intramural Peri-Arterial Drainage (IPAD) pathway. IPAD fails with age and insoluble Aβ is deposited as plaques in the brain and in IPAD pathways as cerebral amyloid angiopathy (CAA); fluid accumulates in the white matter as reflected by hyperintensities (WMH) on MRI. Within the brain, fluid uptake by astrocytes is regulated by aquaporin 4 (AQP4). We test the hypothesis that expression of astrocytic AQP4 increases in grey matter and decreases in white matter with onset of CAA. AQP4 expression was quantitated by immunocytochemistry and confocal microscopy in post-mortem occipital grey and white matter from young and old non-demented human brains, in CAA and in WMH. Results: AQP4 expression tended to increase with normal ageing but AQP4 expression in severe CAA was significantly reduced when compared to moderate CAA (p = 0.018). AQP4 expression tended to decline in the white matter with CAA and WMH, both of which are associated with impaired IPAD. Adjusting the level of AQP4 activity may be a valid therapeutic target for restoring homoeostasis in the brain as IPAD fails with age and CAA.

scholarly journals Endothelial expression of human APP leads to cerebral amyloid angiopathy in mice

2020 ◽  
Author(s):  
Yuriko Tachida ◽  
Saori Miura ◽  
Rie Imamaki ◽  
Naomi Ogasawara ◽  
Hiroyuki Takuwa ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Blood Vessels ◽  
Cerebral Amyloid Angiopathy ◽  
Amyloid Β ◽  
Blood Levels ◽  
Amyloid Angiopathy ◽  
Disease Mechanisms ◽  
Age Dependent ◽  
Cerebral Amyloid ◽  
The Brain

AbstractThe deposition of amyloid β (Aβ) in blood vessels of the brain, known as cerebral amyloid angiopathy (CAA), is observed in more than 90% of Alzheimer’s disease (AD) patients. The presence of such CAA pathology is not as evident, however, in most mouse models of AD, thereby making it difficult to examine the contribution of CAA to the pathogenesis of AD. Since blood levels of soluble amyloid precursor protein (sAPP) in rodents are less than 1% of those in humans, we hypothesized that endothelial APP expression would be markedly lower in rodents, thus providing a reason for the poorly expressed CAA pathology. Here we generated mice that specifically express human APP770 in endothelial cells. These mice exhibited an age-dependent robust deposition of Aβ in brain blood vessels but not in the parenchyma. Crossing these animals with APP knock-in mice led to an expanded CAA pathology as evidenced by increased amounts of amyloid accumulated in the cortical blood vessels. These results show that both neuronal and endothelial APP contribute cooperatively to vascular Aβ deposition, and suggest that this mouse model will be useful for studying disease mechanisms underlying CAA and for developing novel AD therapeutics.

083 Response to immunosuppressive therapy in cerebral amyloid angiopathy-related inflammation

2018 ◽  
Vol 89 (6) ◽  
pp. A33.3-A34
Author(s):  
Jasmin Tilling ◽  
Benjamin Trewin ◽  
Stanley Levy
Keyword(s):  
White Matter ◽  
Cognitive Decline ◽  
Cerebral Amyloid Angiopathy ◽  
White Matter Hyperintensities ◽  
Neurological Deficits ◽  
Amyloid Angiopathy ◽  
Dramatic Improvement ◽  
Age Related ◽  
Cerebral Amyloid ◽  
The Brain

IntroductionCerebral amyloid angiopathy (CAA) is a common age-related condition characterised by amyloid beta-peptide deposition affecting the medium sized cortical and leptomeningeal arteries, arterioles and capillaries. CAA-related Inflammation (CAA-I) is an increasingly recognised variant of CAA, which is thought to be due to perivascular auto-inflammation in response to amyloid deposition. We describe the clinical course of two cases of probable CAA-I.CasesA 71 year old man presented with new-onset seizures, headaches and subacute cognitive decline. MRI of the brain demonstrated confluent subcortical T2 white matter hyperintensities and cerebral oedema, with predominantly superimposed widespread cortico-subcortical micro-haemorrhages, in keeping with the diagnosis of CAA-I. A course of immunosuppresive therapy was commenced with five days of intravenous methylprednisolone, resulting in marked radiological and clinical improvement within two weeks.A 76 year old female presented with subacute cognitive dysfunction and apraxia, and transient left-sided weakness. MRI scan of the brain initially demonstrated a right temporo-occipital infarct, leading to primary treatment for stroke, but subsequently evolved to reveal diffuse multi-lobar T2 white matter hyperintensities with leptomeningeal involvement. A provisional diagnosis of CAA-I was made and following a poor clinical response to a trial of corticosteroid therapy, treatment with intravenous cyclophosphamide was commenced.ConclusionThese cases emphasise the importance of CAA-I as part of the differential diagnosis in patients presenting with symptoms of subacute cognitive decline, seizures, headaches and focal neurological deficits, given the potential for dramatic improvement with readily accessible immunosuppressive therapies.

scholarly journals ApoE4 Astrocytes Secrete Basement Membranes Rich in Fibronectin and Poor in Laminin Compared to ApoE3 Astrocytes

2020 ◽  
Vol 21 (12) ◽  
pp. 4371
Author(s):  
Abby Keable ◽  
Ronan O’Neill ◽  
Matthew MacGregor Sharp ◽  
Maureen Gatherer ◽  
Ho Ming Yuen ◽  
...  
Keyword(s):  
Cerebral Amyloid Angiopathy ◽  
Small Vessel Disease ◽  
Light And Electron Microscopy ◽  
Amyloid Β ◽  
Basement Membranes ◽  
Amyloid Angiopathy ◽  
Disease Spectrum ◽  
Arterial Drainage ◽  
Capillary Endothelial Cells ◽  
Cerebral Amyloid

The accumulation of amyloid-β (Aβ) in the walls of capillaries and arteries as cerebral amyloid angiopathy (CAA) is part of the small vessel disease spectrum, related to a failure of elimination of Aβ from the brain. Aβ is eliminated along basement membranes in walls of cerebral capillaries and arteries (Intramural Peri-Arterial Drainage—IPAD), a pathway that fails with age and ApolipoproteinEε4 (ApoE4) genotype. IPAD is along basement membranes formed by capillary endothelial cells and surrounding astrocytes. Here, we examine (1) the composition of basement membranes synthesised by ApoE4 astrocytes; (2) structural differences between ApoE4 and ApoE3 astrocytes, and (3) how flow of Aβ affects Apo3/4 astrocytes. Using cultured astrocytes expressing ApoE3 or ApoE4, immunofluorescence, confocal, correlative light and electron microscopy (CLEM), and a millifluidic flow system, we show that ApoE4 astrocytes synthesise more fibronectin, possess smaller processes, and become rarefied when Aβ flows over them, as compared to ApoE3 astrocytes. Our results suggest that basement membranes synthesised by ApoE4 astrocytes favour the aggregation of Aβ, its reduced clearance via IPAD, thus promoting cerebral amyloid angiopathy.

scholarly journals Advances in our Understanding of the Pathophysiology, Detection and Management of Cerebral Amyloid Angiopathy

2012 ◽  
Vol 7 (2) ◽  
pp. 134 ◽  
Author(s):  
Octavio M Pontes-Neto ◽  
Eitan Auriel ◽  
Steven M Greenberg ◽  
◽  
◽  
...  
Keyword(s):  
Cerebral Amyloid Angiopathy ◽  
Small Vessel Disease ◽  
Specific Treatment ◽  
Amyloid Β ◽  
Amyloid Angiopathy ◽  
Amyloid Β Peptide ◽  
Small Vessels ◽  
The Media ◽  
Cerebral Amyloid ◽  
The Brain

Cerebral amyloid angiopathy (CAA) is pathologically defined as the deposition of amyloid protein, most commonly the amyloid β peptide (Aβ), primarily within the media and adventitia of small and medium-sized arteries of the leptomeninges, cerebral and cerebellar cortex. This deposition likely reflects an imbalance between Aβ production and clearance within the brain and leads to weakening of the overall structure of brain small vessels, predisposing patients tolobar intracerebral haemorrhage (ICH), brain ischaemia and cognitive decline. CAA is associated with markers of small vessel disease, like lobar microbleeds and white matter hyperintensities on magnetic resonance imaging. Therefore, it can be now be diagnosed during life with reasonable accuracy by clinical and neuroimaging criteria. Despite the lack of a specific treatment for this condition, the detection of CAA may help in the management of patients, regarding the prevention of major haemorrhagic complications and genetic counselling. This review discusses recent advances in our understanding of the pathophysiology, detection and management of CAA.

scholarly journals Pleiotropic neuroprotective effects of taxifolin in cerebral amyloid angiopathy

2019 ◽  
Vol 116 (20) ◽  
pp. 10031-10038 ◽  
Author(s):  
Takayuki Inoue ◽  
Satoshi Saito ◽  
Masashi Tanaka ◽  
Hajime Yamakage ◽  
Toru Kusakabe ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Amyloid Angiopathy ◽  
Apoptotic Cell ◽  
Amyloid Β ◽  
Myeloid Cell ◽  
Low Permeability ◽  
Amyloid Angiopathy ◽  
Neuroprotective Effects ◽  
Cerebral Amyloid ◽  
The Brain

Cerebral amyloid angiopathy (CAA) results from amyloid-β deposition in the cerebrovasculature. It is frequently accompanied by Alzheimer’s disease and causes dementia. We recently demonstrated that in a mouse model of CAA, taxifolin improved cerebral blood flow, promoted amyloid-β removal from the brain, and prevented cognitive dysfunction when administered orally. Here we showed that taxifolin inhibited the intracerebral production of amyloid-β through suppressing the ApoE–ERK1/2–amyloid-β precursor protein axis, despite the low permeability of the blood–brain barrier to taxifolin. Higher expression levels of triggering receptor expressed on myeloid cell 2 (TREM2) were associated with the exacerbation of inflammation in the brain. Taxifolin suppressed inflammation, alleviating the accumulation of TREM2-expressing cells in the brain. It also mitigated glutamate levels and oxidative tissue damage and reduced brain levels of active caspases, indicative of apoptotic cell death. Thus, the oral administration of taxifolin had intracerebral pleiotropic neuroprotective effects on CAA through suppressing amyloid-β production and beneficially modulating proinflammatory microglial phenotypes.

Cerebral amyloid angiopathy: an underdiagnosed cause of recurrent neurological symptoms

2021 ◽  
Vol 14 (4) ◽  
pp. e235949
Author(s):  
Fakharunisa Shah ◽  
Shayda Yazdani ◽  
Mark I'anson ◽  
Tahir Nazir
Keyword(s):  
Cerebral Amyloid Angiopathy ◽  
Brain Injuries ◽  
Hospital Admissions ◽  
Treatment Options ◽  
Functional Limitation ◽  
Amyloid Β ◽  
Neurological Symptoms ◽  
Amyloid Angiopathy ◽  
Cerebral Amyloid ◽  
The Brain

Cerebral amyloid angiopathy (CAA) is a common, yet frequently underdiagnosed pathology characterised by accumulation of amyloid β proteins in the small blood vessels of the brain. As a result, cerebrovascular dysregulation follows, leading to cerebral microbleeds, lobar intracerebral haematomas and sulcal subarachnoid haemorrhages. Gradual motor and cognitive decline due to these brain injuries leads to significant functional limitation in patients. We describe the case of a 69-year-old man requiring multiple hospital admissions with a variety of neurological symptoms. Following imaging of the brain, he was eventually diagnosed with CAA. We present a brief up-to-date literature review on epidemiology, pathophysiology, clinical features, diagnosis and treatment options for CAA.

scholarly journals Cerebral amyloid angiopathy severity is linked to dilation of juxtacortical perivascular spaces

2015 ◽  
Vol 36 (3) ◽  
pp. 576-580 ◽  
Author(s):  
Susanne J van Veluw ◽  
Geert Jan Biessels ◽  
Willem H Bouvy ◽  
Wim GM Spliet ◽  
Jaco JM Zwanenburg ◽  
...  
Keyword(s):  
Cerebral Amyloid Angiopathy ◽  
Small Vessel Disease ◽  
Amyloid Β ◽  
Amyloid Angiopathy ◽  
Perivascular Spaces ◽  
Resonance Imaging ◽  
Centrum Semiovale ◽  
Tissue Sections ◽  
Cortical Areas ◽  
Cerebral Amyloid

Perivascular spaces are an emerging marker of small vessel disease. Perivascular spaces in the centrum semiovale have been associated with cerebral amyloid angiopathy. However, a direct topographical relationship between dilated perivascular spaces and cerebral amyloid angiopathy severity has not been established. We examined this association using post-mortem magnetic resonance imaging in five cases with evidence of cerebral amyloid angiopathy pathology. Juxtacortical perivascular spaces dilation was evaluated on T2 images and related to cerebral amyloid angiopathy severity in overlying cortical areas on 34 tissue sections stained for Amyloid β. Degree of perivascular spaces dilation was significantly associated with cerebral amyloid angiopathy severity (odds ratio = 3.3, 95% confidence interval 1.3–7.9, p = 0.011). Thus, dilated juxtacortical perivascular spaces are a promising neuroimaging marker of cerebral amyloid angiopathy severity.

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