Neprilysin protects against cerebral amyloid angiopathy and Aβ-induced degeneration of cerebrovascular smooth muscle cells.
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ABSTRACT:
SUBMITTER: Miners JS
PROVIDER: S-EPMC8094282 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Cerebral amyloid angiopathy (CAA) corresponds to the deposition of amyloid material in the cerebral vasculature, leading to structural modifications of blood vessel walls. The most frequent form of sporadic CAA involves fibrillar β-amyloid peptide (Aβ) deposits, mainly the 40 amino acid form (Aβ1-40), which are commonly found in the elderly with or without Alzheimer's disease. Sporadic CAA usually remains clinically silent. However, in some cases, acute complications either hemorrhagic or inflammatory can occur. Similar complications occurred after active or passive immunization against Aβ in experimental animal models exhibiting CAA, and in subjects with Alzheimer's disease during clinical trials. The triggering of these adverse events by active immunization and monoclonal antibody administration in CAA-bearing individuals suggests that analogous mechanisms could be involved during spontaneous CAA complications, drawing particular attention to the role of anti-Aβ antibodies. However, antibodies that react with several monomeric and aggregated forms of Aβ spontaneously occur in virtually all human individuals, hence being part of the "natural antibody" repertoire. Natural antibodies are usually described as having low-affinity and high cross-reactivity toward microbial components and autoantigens. Although frequently of the IgM class, they also belong to IgG and IgA isotypes. They likely display homeostatic functions and protective roles in aging. Until recently, the peculiar properties of these natural antibodies have hindered proper analysis of the Aβ-reactive antibody repertoire and the study of their implication in CAA complications. Herein, we review and comment the evidences of an auto-immune nature of spontaneous CAA complications, and discuss implications for forthcoming research and clinical practice.
| S-EPMC6620823 | biostudies-literature
Project description:There is a growing recognition of cerebrovascular contribution to neurodegenerative diseases. Cerebral amyloid angiopathy (CAA), characterised by amyloid-beta (AM-NM-2) deposits in the walls of intracerebral and leptomeningeal arteries, is evident in a majority of AlzheimerM-bM-^@M-^Ys disease patients and aged people. Here, we leverage on human pluripotent stem cells to generate vascular smooth muscle cells (SMCs) from neural crest progenitors, recapitulating brain vasculature-specific attributes in AM-NM-2 metabolism. We confirm that the lipoprotein receptor, LRP1, functions in our neural crest-derived SMCs to mediate AM-NM-2 uptake and intracellular proteasomal degradation. Hypoxia significantly compromises the ability of SMCs in AM-NM-2 clearance by suppressing LRP1 expression. This enables us to develop an assay of AM-NM-2 uptake using the neural crest-derived SMCs with hypoxia as a stress paradigm. We then tested several vascular protective compounds in a high throughput format, demonstrating the value of stem cell-based phenotypic screening for novel CAA therapeutics and drug repurposing. We adopted our previous SMC differentiation protocol (Cheung et al., 2012) to differentiate this intermediate neural crest population using platelet-derived growth factor BB (PDGF-BB, 10 ng/ml) and transforming growth factor-beta 1 (TGF-M-NM-21, 2ng/ml) for another 12 days. The resultant neural crest-derived SMCs (NCSMC) were then characterised in comparison to neuroectoderm-derived SMCs (NESMC) (Cheung et al., 2012) and positive control, human brain vascular SMCs (BVSMC).
2015-01-21 | E-GEOD-55173 | biostudies-arrayexpress
Project description:There is a growing recognition of cerebrovascular contribution to neurodegenerative diseases. Cerebral amyloid angiopathy (CAA), characterised by amyloid-beta (Aβ) deposits in the walls of intracerebral and leptomeningeal arteries, is evident in a majority of Alzheimer’s disease patients and aged people. Here, we leverage on human pluripotent stem cells to generate vascular smooth muscle cells (SMCs) from neural crest progenitors, recapitulating brain vasculature-specific attributes in Aβ metabolism. We confirm that the lipoprotein receptor, LRP1, functions in our neural crest-derived SMCs to mediate Aβ uptake and intracellular proteasomal degradation. Hypoxia significantly compromises the ability of SMCs in Aβ clearance by suppressing LRP1 expression. This enables us to develop an assay of Aβ uptake using the neural crest-derived SMCs with hypoxia as a stress paradigm. We then tested several vascular protective compounds in a high throughput format, demonstrating the value of stem cell-based phenotypic screening for novel CAA therapeutics and drug repurposing.
2015-01-21 | GSE55173 | GEO
Project description:In this study, we synthesized four novel Al18/19F-labeled 2-phenylbenzothiazole derivatives conjugated to 1,4,7-triazacyclononane-1,4-diacetic acid via alkyl linkers and evaluated them as imaging agent targets to amyloid-β (Aβ) plaques deposited in the blood vessels of cerebral amyloid angiopathy (CAA) brain. The four ligands exhibited moderate-to-high binding ability to Aβ1-42 aggregates, of which complex 17 possessing the most potent affinity (K i = 11.3 nM) was selected for further biological evaluations. In vitro fluorescent staining and in vitro autoradiography studies on brain sections from CAA patients proved that this ligand could label Aβ deposits in blood vessels selectively. In biodistribution study, [18F]17 can hardly penetrate the blood-brain barrier (brain2 min = 0.3% ID/g) and displayed a rapid blood washout rate (blood2 min/blood60 min = 25.2), which is favorable as CAA imaging agents. In conclusion, this Al18F-labeled 2-phenylbenzothiazole complex was developed and proved to be a promising CAA positron emission tomography agent.
| S-EPMC6217595 | biostudies-literature
Project description:Cerebral amyloid angiopathy (CAA) involves cerebrovascular amyloid deposition and is classified into several types according to the amyloid protein involved. Of these, sporadic amyloid β-protein (Aβ)-type CAA is most commonly found in older individuals and in patients with Alzheimer's disease (AD). Cerebrovascular Aβ deposits accompany functional and pathological changes in cerebral blood vessels (CAA-associated vasculopathies). CAA-associated vasculopathies lead to development of hemorrhagic lesions [lobar intracerebral macrohemorrhage, cortical microhemorrhage, and cortical superficial siderosis (cSS)/focal convexity subarachnoid hemorrhage (SAH)], ischemic lesions (cortical infarction and ischemic changes of the white matter), and encephalopathies that include subacute leukoencephalopathy caused by CAA-associated inflammation/angiitis. Thus, CAA is related to dementia, stroke, and encephalopathies. Recent advances in diagnostic procedures, particularly neuroimaging, have enabled us to establish a clinical diagnosis of CAA without brain biopsies. Sensitive magnetic resonance imaging (MRI) methods, such as gradient-echo T2(*) imaging and susceptibility-weighted imaging, are useful for detecting cortical microhemorrhages and cSS. Amyloid imaging with amyloid-binding positron emission tomography (PET) ligands, such as Pittsburgh Compound B, can detect CAA, although they cannot discriminate vascular from parenchymal amyloid deposits. In addition, cerebrospinal fluid markers may be useful, including levels of Aβ40 for CAA and anti-Aβ antibody for CAA-related inflammation. Moreover, cSS is closely associated with transient focal neurological episodes (TFNE). CAA-related inflammation/angiitis shares pathophysiology with amyloid-related imaging abnormalities (ARIA) induced by Aβ immunotherapies in AD patients. This article reviews CAA and CAA-related disorders with respect to their epidemiology, pathology, pathophysiology, clinical features, biomarkers, diagnosis, treatment, risk factors, and future perspectives.
| S-EPMC4325636 | biostudies-literature
Project description:IntroductionCerebrovascular pathologies including cerebral amyloid angiopathy (CAA) and blood-brain barrier (BBB) dysregulation are prominent features in the majority of Alzheimer's disease (AD) cases.MethodsWe performed neuropathologic and biochemical studies on a large, neuropathologically confirmed human AD cohort (N = 469). Amounts of endothelial tight junction proteins claudin-5 (CLDN5) and occludin (OCLN), and major AD-related molecules (amyloid beta [Aβ40], Aβ42, tau, p-tau, and apolipoprotein E) in the temporal cortex were assessed by ELISA.ResultsHigher levels of soluble tau, insoluble p-tau, and apolipoprotein E (apoE) were independently correlated with lower levels of endothelial tight junction proteins CLDN5 and OCLN in AD brains. Although high Aβ40 levels, APOE ε4, and male sex were predominantly associated with exacerbated CAA severity, those factors did not influence tight junction protein levels.DiscussionRefining the molecular mechanisms connecting tau, Aβ, and apoE with cerebrovascular pathologies is critical for greater understanding of AD pathogenesis and establishing effective therapeutic interventions for the disease.
| S-EPMC8103951 | biostudies-literature
Project description:Cerebral amyloid angiopathy (CAA) is a degenerative vasculopathy that is classically associated with lobar intracerebral or sulcal hemorrhage. Its prevalence is estimated at 30% in the seventh decade and 50% in the eighth and ninth decades. In this review, we summarize the risks linked to CAA with respect to the treatment and prevention of stroke.This review is based on pertinent publications retrieved by a selective search employing the terms "amyloid cerebral angiopathy," "stroke," "intra - cerebral bleeding," and "acute stroke therapy."Among patients given systemic lytic treatment for stroke, those who have microhemorrhages tend to have a higher risk of treatment-associated brain hemorrhage. In a meta-analysis, 70% of patients who sustained a hemorrhage after thrombolytic therapy were found to have CAA, compared to only 22% in a control population. Patients with cerebral hemorrhages have microhemorrhages more commonly than patients with transient ischemic attacks (TIA) or infarcts. This was observed among persons under treatment with vitamin K antagonists (odds ratio, 2.7) or platelet aggregation inhibitors (odds ratio, 1.7). Moreover, the apolipoprotein E2 allele is associated with a higher incidence of intracerebral hemorrhage (ICH) under oral anticoagulation. Strict treatment of arterial hypertension can lower the risk of ICH in persons with probable CAA by 77%. On the other hand, the use of statins after a lobar ICH increases the risk for a clinically manifest recurrent hemorrhage from 14% to 22%.In patients with CAA, arterial hypertension should be tightly controlled. On the other hand, caution should be exercised in prescribing oral anticoagulants or platelet aggregation inhibitors for patients with CAA, or statins for patients who have already sustained a lobar ICH.
| S-EPMC5541242 | biostudies-other
Project description:Amyloid-? (A?) is a peptide deposited in the brain parenchyma in Alzheimer's disease and in cerebral blood vessels, causing cerebral amyloid angiopathy (CAA). A? pathology is transmissible experimentally in animals and through medical procedures in humans, such as contaminated growth hormone or dura mater transplantation in the context of iatrogenic prion disease. Here, we present four patients who underwent neurosurgical procedures during childhood or teenage years and presented with intracerebral haemorrhage approximately three decades later, caused by severe CAA. None of these patients carried pathogenic mutations associated with early A? pathology development. In addition, we identified in the literature four patients with a history of neurosurgical intervention and subsequent development of CAA. These findings raise the possibility that A? pathology may be transmissible, as prion disease is, through neurosurgical procedures.
| S-EPMC5904220 | biostudies-literature
Project description:BackgroundCerebral amyloid angiopathy (CAA) occurs in 80% of patients with Alzheimer's disease (AD) and is mainly caused by the abnormal deposition of Aβ in the walls of cerebral blood vessels. Cerebrovascular molecular mechanisms in CAA were investigated by using comprehensive and accurate quantitative proteomics.MethodsConcerning the molecular mechanisms specific to CAA, formalin-fixed paraffin-embedded (FFPE) sections were prepared from patients having AD neuropathologic change (ADNC) with severe cortical Aβ vascular deposition (ADNC +/CAA +), and from patients having ADNC without vascular deposition of Aβ (ADNC +/CAA -; so called, AD). Cerebral cortical vessels were isolated from FFPE sections using laser microdissection (LMD), processed by pressure cycling technology (PCT), and applied to SWATH (sequential window acquisition of all theoretical fragment ion spectra) proteomics.ResultsThe protein expression levels of 17 proteins in ADNC +/CAA +/H donors (ADNC +/CAA + donors with highly abundant Aβ in capillaries) were significantly different from those in ADNC +/CAA - and ADNC -/CAA - donors. Furthermore, we identified 56 proteins showing more than a 1.5-fold difference in average expression levels between ADNC +/CAA + and ADNC -/CAA - donors, and were significantly correlated with the levels of Aβ or Collagen alpha-2(VI) chain (COL6A2) (CAA markers) in 11 donors (6 ADNC +/CAA + and 5 ADNC -/CAA -). Over 70% of the 56 proteins showed ADNC +/CAA + specific changes in protein expression. The comparative analysis with brain parenchyma showed that more than 90% of the 56 proteins were vascular-specific pathological changes. A literature-based pathway analysis showed that 42 proteins are associated with fibrosis, oxidative stress and apoptosis. This included the increased expression of Heat shock protein HSP 90-alpha, CD44 antigen and Carbonic anhydrase 1 which are inhibited by potential drugs against CAA.ConclusionsThe combination of LMD-based isolation of vessels from FFPE sections, PCT-assisted sample processing and SWATH analysis (FFPE-LMD-PCT-SWATH method) revealed for the first time the changes in the expression of many proteins that are involved in fibrosis, ROS production and cell death in ADNC +/CAA + (CAA patients) vessels. The findings reported herein would be useful for developing a better understanding of the pathology of CAA and for promoting the discovery and development of drugs and biomarkers for CAA.
| S-EPMC9250250 | biostudies-literature
Project description:BACKGROUND:There is limited data on cerebrospinal fluid (CSF) biomarkers in sporadic amyloid-? (A?) cerebral amyloid angiopathy (CAA). OBJECTIVE:To determine the profile of biomarkers relevant to neurodegenerative disease in the CSF of patients with CAA. METHODS:We performed a detailed comparison of CSF markers, comparing patients with CAA, Alzheimer's disease (AD), and control (CS) participants, recruited from the Biomarkers and Outcomes in CAA (BOCAA) study, and a Specialist Cognitive Disorders Service. RESULTS:We included 10 CAA, 20 AD, and 10 CS participants (mean age 68.6, 62.5, and 62.2 years, respectively). In unadjusted analyses, CAA patients had a distinctive CSF biomarker profile, with significantly lower (p?<?0.01) median concentrations of A?38, A?40, A?42, sA?PP?, and sA?PP?. CAA patients had higher levels of neurofilament light (NFL) than the CS group (p?<?0.01), but there were no significant differences in CSF total tau, phospho-tau, soluble TREM2 (sTREM2), or neurogranin concentrations. AD patients had higher total tau, phospho-tau and neurogranin than CS and CAA groups. In age-adjusted analyses, differences for the CAA group remained for A?38, A?40, A?42, and sA?PP?. Comparing CAA patients with amyloid-PET positive (n?=?5) and negative (n?=?5) scans, PET positive individuals had lower (p?<?0.05) concentrations of CSF A?42, and higher total tau, phospho-tau, NFL, and neurogranin concentrations, consistent with an "AD-like" profile. CONCLUSION:CAA has a characteristic biomarker profile, suggestive of a global, rather than selective, accumulation of amyloid species; we also provide evidence of different phenotypes according to amyloid-PET positivity. Further replication and validation of these preliminary findings in larger cohorts is needed.
| S-EPMC7242825 | biostudies-literature