amyloid-beta-peptides and Cerebral-Amyloid-Angiopathy

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 (Aβ

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Antibodies, Monoclonal; Cerebral Amyloid Angiopathy; Humans; Immunization, Passive; Peptide Fragments

To perform a meta-analysis of 4 core CSF biomarkers (β-amyloid [Aβ]42, Aβ40, total tau [t-tau], and phosphorylated tau [p-tau]) to assess which of these are most altered in sporadic cerebral amyloid angiopathy (CAA).. We systematically searched PubMed for eligible studies reporting data on CSF biomarkers reflecting amyloid precursor protein metabolism (Aβ42, Aβ40), neurodegeneration (t-tau), and tangle pathology (p-tau) in symptomatic sporadic CAA cohorts vs controls and patients with Alzheimer disease (AD). Biomarker performance was assessed in random-effects meta-analysis based on ratio of mean (RoM) biomarker concentrations: (1) in patients with CAA vs healthy controls and (2) in patients with CAA vs patients with AD. RoM >1 indicates higher biomarker concentration in patients with CAA vs comparison population and RoM <1 indicates higher concentration in comparison groups.. Three studies met inclusion criteria. These comprised 5 CAA patient cohorts (n = 59 patients) vs healthy controls (n = 94 cases) and AD cohorts (n = 158). Three core biomarkers differentiated CAA from controls: CSF Aβ42 (RoM 0.49, 95% confidence interval [CI] 0.38-0.64,. Specific CSF patterns of Aβ42, Aβ40, t-tau, and p-tau might serve as molecular biomarkers of CAA, but analyses in larger CAA cohorts are needed.

Topics: Amyloid beta-Peptides; Biomarkers; Cerebral Amyloid Angiopathy; Humans; Peptide Fragments; tau Proteins

Cerebral amyloid angiopathy (CAA) is an age-associated disease characterized by amyloid deposition in cerebral and meningeal vessel walls. CAA is detected in the majority of the individuals with dementia and also in a large number of non-demented elderly individuals. In addition, CAA is strongly associated with Alzheimer's disease (AD) pathology. Mechanical consequences including intra-cerebral or subarachnoid hemorrhage remains CAA most feared complication, but only a small fraction of CAA results in severe bleeding. On the hand the non-mechanical consequences in cerebrovascular regulation are prevalent and may be even more deleterious. Studies of animal models have provided strong evidence linking the vasoactive Aβ 1-40, the main species found in CAA, to disturbances in endothelial-dependent factors, disrupting cerebrovascular regulation Here, we aimed to review experimental findings regarding the non-mechanical consequences of CAA for cerebrovascular regulation and discuss the implications of these results to clinical practice.

Topics: Amyloid beta-Peptides; Animals; Cerebral Amyloid Angiopathy; Cerebrovascular Circulation; Endothelium, Vascular; Humans; Peptide Fragments

Atraumatic convexal subarachnoid hemorrhage (cSAH) in elderly patients is a rare entity that has been associated with cerebral amyloid angiopathy (CAA) and intracerebral hematomas (ICH). To characterize this entity and to study these associations, 22 patients over 60 with cSAH were included in a multicenter ambispective cohort study. Clinical data, magnetic resonance imaging (MRI) studies, APOE genotyping, and cerebrospinal fluid (CSF) biomarkers were evaluated. Results were compared with data from healthy controls (HC), non-cSAH CAA patients (CAAo), and Alzheimer disease patients. Convexal subarachnoid hemorrhage presented with transient sensory or motor symptoms. At follow-up (median 30.7 months), 5 patients had died, 6 survivors showed functional disability (modified Rankins Scale (mRS)>2), and 12 cognitive impairment. Four patients had prior ICH and six had an ICH during follow-up. CSF-Aß40 and Aß42 levels were lower in cSAH and CAAo compared with HC. Convexal subarachnoid hemorrhage presented an APOE-ɛ2 overrepresentation and CAAo had an APOE-ɛ4 overrepresentation. On MRI, all patients fulfilled CAA-modified Boston criteria and 9 showed cortical ischemia in the surrounding cortex or the vicinity of superficial siderosis. The neuropathologic study, available in one patient, showed severe CAA and advanced Alzheimer-type pathology. Convexal subarachnoid hemorrhage in the elderly is associated with cognitive impairment and lobar ICH occurrence. Our findings support the existence of an underlying CAA pathology.

Topics: Aged; Aged, 80 and over; Amyloid beta-Peptides; Apolipoproteins E; Cerebral Amyloid Angiopathy; Disease-Free Survival; Female; Follow-Up Studies; Genotype; Humans; Magnetic Resonance Angiography; Male; Middle Aged; Peptide Fragments; Radiography; Subarachnoid Hemorrhage

Cerebral amyloid angiopathy with related inflammation (CAA-ri) is a rare age-associated disorder characterized by an inflammatory response to amyloid in cerebral blood vessels. CAA-ri is often treated with corticosteroids, but response to treatment is variable.. To assess the relationship between clinical and paraclinical measures and outcomes in patients with CAA-ri treated with high doses of methylprednisolone.. Longitudinal clinical course, and results from serum and cerebrospinal fluid (CSF) testing, electroencephalography, and neuroimaging were reviewed from 11 prospectively-accrued CAA-ri patients diagnosed, treated, and followed at Barnes Jewish Hospital (St. Louis, MO, USA). Magnetic resonance imaging (MRI) changes were quantified using a scoring system validated in cases of amyloid related imaging abnormality (ARIA-E). Clinical outcomes were assessed as change in modified Rankin Scale (ΔmRS) from baseline to final assessment (median 175 days from treatment with high doses of methylprednisolone; range, 31-513).. Worse outcomes following methylprednisolone treatment were associated with requirement for intensive care unit admission (median ΔmRS, 5 versus 1.5; p = 0.048), CSF pleocytosis (median ΔmRS 4.5 versus 1; p = 0.04), or lower CSF Aβ40 at presentation (rho = -0.83; p = 0.02), and diffusion restriction (median ΔmRS 4 versus 1.5; p = 0.03) or higher late ARIA-E scores (rho = 0.70; p = 0.02) on MRI, but not preexisting cognitive decline (median ΔmRS 2 versus 2; p = 0.66).. Clinical and paraclinical measures associated with outcomes may inform clinical counseling and treatment decisions in patients with CAA-ri. Baseline cognitive status was not associated with treatment responsiveness.

Topics: Aged; Aged, 80 and over; Amyloid beta-Peptides; Anti-Inflammatory Agents; Biomarkers; Cerebral Amyloid Angiopathy; Cognitive Dysfunction; Critical Care; Electroencephalography; Encephalitis; Female; Humans; Leukocytosis; Longitudinal Studies; Magnetic Resonance Imaging; Male; Methylprednisolone; Neuroimaging; Peptide Fragments; tau Proteins; Treatment Outcome

Topics: Alzheimer Disease; Amyloid beta-Peptides; Apolipoprotein E4; Biomarkers; Cerebral Amyloid Angiopathy; Humans; Peptide Fragments; Phenotype; Phosphorylation; Positron-Emission Tomography; tau Proteins

Topics: Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Biomarkers; Brain; Cerebral Amyloid Angiopathy; Disease Models, Animal; Humans; Magnetic Resonance Imaging; Microvessels; Peptide Fragments; Rats; Rats, Transgenic; Severity of Illness Index

The discovery of mutations associated with familial forms of Alzheimer's disease (AD), has brought imperative insights into basic mechanisms of disease pathogenesis and progression and has allowed researchers to create animal models that assist in the elucidation of the molecular pathways and development of therapeutic interventions. Position 717 in the amyloid precursor protein (APP) is a hotspot for mutations associated with autosomal dominant AD (ADAD) and the valine to isoleucine amino acid substitution (V717I) at this position was among the first ADAD mutations identified, spearheading the formulation of the amyloid cascade hypothesis of AD pathogenesis. While this mutation is well described in multiple kindreds and has served as the basis for the generation of widely used animal models of disease, neuropathologic data on patients carrying this mutation are scarce. Here we present the detailed clinical and neuropathologic characterization of an APP V717I carrier, which reveals important novel insights into the phenotypic variability of ADAD cases. While age at onset, clinical presentation and widespread parenchymal beta-amyloid (Aβ) deposition are in line with previous reports, our case also shows widespread and severe cerebral amyloid angiopathy (CAA). This patient also presented with TDP-43 pathology in the hippocampus and amygdala, consistent with limbic predominant age-related TDP-43 proteinopathy (LATE). The APOE ε2/ε3 genotype may have been a major driver of the prominent vascular pathology seen in our case. These findings highlight the importance of neuropathologic examinations of genetically determined AD cases and demonstrate striking phenotypic variability in ADAD cases.

Topics: Aged; Alzheimer Disease; Amygdala; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Apolipoprotein E2; Apolipoprotein E3; Brain; Cerebellum; Cerebral Amyloid Angiopathy; Female; Hippocampus; Humans; Mutation, Missense; Neurofibrillary Tangles; Peptide Fragments; Phenotype; Plaque, Amyloid; tau Proteins; TDP-43 Proteinopathies

There is limited data on cerebrospinal fluid (CSF) biomarkers in sporadic amyloid-β (Aβ) cerebral amyloid angiopathy (CAA).. To determine the profile of biomarkers relevant to neurodegenerative disease in the CSF of patients with CAA.. 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.. 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 Aβ38, Aβ40, Aβ42, sAβPPα, and sAβPPβ. 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 Aβ38, Aβ40, Aβ42, and sAβPPβ. 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 Aβ42, and higher total tau, phospho-tau, NFL, and neurogranin concentrations, consistent with an "AD-like" profile.. 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.

Topics: Aged; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Biomarkers; Case-Control Studies; Cerebral Amyloid Angiopathy; Female; Humans; Male; Middle Aged; Neurofilament Proteins; Peptide Fragments; tau Proteins

Cerebral amyloid angiopathy (CAA) is a vascular disorder that primarily involves deposition of the 40-residue-long β-amyloid peptide (Aβ40) in and along small blood vessels of the brain. CAA is often associated with Alzheimer's disease (AD), which is characterized by amyloid plaques in the brain parenchyma enriched in the Aβ42 peptide. Several recent studies have suggested a structural origin that underlies the differences between the vascular amyloid deposits in CAA and the parenchymal plaques in AD. We previously have found that amyloid fibrils in vascular amyloid contain antiparallel β-sheet, whereas previous studies by other researchers have reported parallel β-sheet in fibrils from parenchymal amyloid. Using X-ray fluorescence microscopy, here we found that copper strongly co-localizes with vascular amyloid in human sporadic CAA and familial Iowa-type CAA brains compared with control brain blood vessels lacking amyloid deposits. We show that binding of Cu(II) ions to antiparallel fibrils can block the conversion of these fibrils to the more stable parallel, in-register conformation and enhances their ability to serve as templates for seeded growth. These results provide an explanation for how thermodynamically less stable antiparallel fibrils may form amyloid in or on cerebral vessels by using Cu(II) as a structural cofactor.

Topics: Alzheimer Disease; Amyloid; Amyloid beta-Peptides; Brain; Cerebral Amyloid Angiopathy; Copper; Humans; Magnetic Resonance Spectroscopy; Microscopy, Atomic Force; Molecular Conformation; Peptide Fragments; Plaque, Amyloid; Protein Conformation, beta-Strand

Fibrillar aggregates of amyloid-β (Aβ) are the main component of plaques lining the cerebrovasculature in cerebral amyloid angiopathy. As the predominant Aβ isoform in vascular deposits, Aβ40 is a valuable target in cerebral amyloid angiopathy research. However, the slow process of Aβ40 aggregation in vitro is a bottleneck in the search for Aβ-targeting molecules. In this study, we sought a method to accelerate the aggregation of Aβ40 in vitro, to improve experimental screening procedures. We evaluated the aggregating ability of bicine, a biological buffer, using various in vitro methods. Our data suggest that bicine promotes the aggregation of Aβ40 with high speed and reproducibility, yielding a mixture of aggregates with significant β-sheet-rich fibril formation and toxicity.

Topics: Amyloid beta-Peptides; Animals; Cell Line; Cell Survival; Cerebral Amyloid Angiopathy; Glycine; Humans; Mice; Neurons; Peptide Fragments; Protein Aggregates; Protein Conformation, beta-Strand

Predicting recurrent intracerebral hemorrhage (ICH) related to cerebral amyloid angiopathy (CAA) currently relies on brain images. We aimed to investigate whether blood neurodegenerative biomarkers predict disease severity and ICH recurrence in CAA. We recruited 68 first probable CAA-ICH cases from a Chinese prospective cohort, and 95 controls. We used the single-molecule array to measure acute phase blood amyloid-40, amyloid-42, total tau and neurofilament light chain (NfL). We used multivariable Cox regression models to assess the association between blood biomarkers and CAA-ICH recurrence, and used the concordance (c-) index to assess prediction models. Blood amyloid-42/40, total tau, and NfL levels changed in CAA-ICH cases than controls. During a median follow-up of 2.4 years, NfL was associated with CAA-ICH recurrence (adjusted hazard ratio 2.14, 95% CI 1.57-2.93) independent of MRI burden of small vessel disease (SVD). The performance of a model to predict CAA-ICH recurrence using MRI burden of SVD alone (c-index 0.77) increased with the addition of NfL (c-index 0.88, 95% CI 0.73-1.00, p=0.019). Further, NfL was associated with baseline ICH volume, NIHSS and 6-month mRS score. Blood NfL is associated with severity and prognosis of CAA-ICH and is a promising addition to MRI burden of SVD to predict CAA-ICH recurrence.

Topics: Aged; Aged, 80 and over; Amyloid beta-Peptides; Biomarkers; Case-Control Studies; Cerebral Amyloid Angiopathy; Cerebral Hemorrhage; China; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Neurofilament Proteins; Peptide Fragments; Predictive Value of Tests; Prognosis; Prospective Studies; Recurrence; Risk Assessment; Risk Factors; Severity of Illness Index; tau Proteins

Cerebral amyloid angiopathy (CAA) is present in over half of the elderly population and in 80-90% of Alzheimer's disease (AD) patients. CAA is defined by the deposition of beta amyloid (Aβ) in small cerebral arteries and capillaries. Cardiovascular risk factors are associated with an increased incidence of CAA. We utilized 18-month-old endothelial nitric oxide synthase (eNOS) heterozygous knockout (

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Cerebral Amyloid Angiopathy; Endothelium, Vascular; Mice; Mice, Knockout; Nitric Oxide; Nitric Oxide Synthase Type III; Peptide Fragments

Neuropathological follow-up of patients with Alzheimer's disease (AD) who participated in the first clinical trial of Amyloid-β 42 (Aβ42) immunization (AN1792, Elan Pharmaceuticals) has shown that immunization can induce removal of Aβ42 and Aβ40 from plaques, whereas analysis of the cerebral vessels has shown increased levels of these Aβ peptides in cerebral amyloid angiopathy (CAA). Aβ43 has been less frequently studied in AD, but its aggregation propensity and neurotoxic properties suggest it may have an important pathogenic role. In the current study we show by using immunohistochemistry that in unimmunized AD patients Aβ43 is a frequent constituent of plaques (6.0% immunostained area), similar to Aβ42 (3.9% immunostained area). Aβ43 immunostained area was significantly higher than that of Aβ40 (2.3%, p = 0.006). In addition, we show that Aβ43 is only a minor component of CAA in both parenchymal vessels (1.5 Aβ43-positive vessels per cm

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Brain; Cerebral Amyloid Angiopathy; Female; Humans; Immunization; Male; Peptide Fragments; Plaque, Amyloid

Cerebrovascular pathology is a significant mediator in Alzheimer's disease (AD) in the general population. In people with Down syndrome (DS), the contribution of vascular pathology to dementia may play a similar role in age of onset and/or the rate of progression of AD. In the current study, we explored the extent of microbleeds (MBs) and the link between cerebral amyloid angiopathy (CAA) and MBs in the frontal cortex (FCTX) and occipital cortex (OCTX) in an autopsy series from individuals with DS (<40 years), DS with AD pathology (DSAD), sporadic AD, and control cases (2-83 years). Sections were immunostained against Aβ1 - 40 and an adjacent section stained using Prussian blue for MBs. MBs were both counted and averaged in each case and CAA was scored based on previously published methods. MBs were more frequent in DS cases relative to controls but present to a similar extent as sporadic AD. This aligned with CAA scores, with more extensive CAA in DS relative to controls in both brain regions. CAA was also more frequent in DSAD cases relative to sporadic AD. We found CAA to be associated with MBs and that MBs increased with age in DS after 30 years of age in the OCTX and after 40 years of age in the FCTX. MB and CAA appear to be a significant contributors to the development of dementia in people with DS and are important targets for future clinical trials.

Topics: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Autopsy; Case-Control Studies; Cerebral Amyloid Angiopathy; Child; Child, Preschool; Down Syndrome; Female; Frontal Lobe; Humans; Image Processing, Computer-Assisted; Intracranial Hemorrhages; Male; Middle Aged; Occipital Lobe; Peptide Fragments; Young Adult

Sporadic cerebral amyloid angiopathy (CAA) is characterized by cerebrovascular amyloid-β (Aβ) deposition, which leads to lobar hemorrhage and dementia. Biological molecules affecting the development of CAA have not been fully characterized. In this study, we performed proteome analysis of biopsied leptomeningeal and cortical vessels obtained from 6 CAA patients and 5 non-CAA patients who underwent surgery for large lobar hemorrhages. We found that 6 proteins, including Aβ, apolipoprotein E (apoE), clusterin (CLU), albumin, complement C4 and vitronectin were significantly upregulated in the vessels of CAA patients as compared to non-CAA patients. ApoE and CLU were found in all CAA patients. We next examined the effects of apoE and CLU on the early phase of Aβ aggregation, using a simple yet powerful in vitro model of CAA, which recapitulates the intramural periarterial drainage pathway model. We found that physiological concentrations of apoE and CLU delayed the initiation time of amyloid growth kinetics in a concentration-dependent manner. These data indicate that apoE and CLU may act as extracellular chaperones to inhibit Aβ amyloid deposition in CAA.

Topics: Aged; Aged, 80 and over; Amyloid beta-Peptides; Apolipoproteins E; Brain; Cerebral Amyloid Angiopathy; Clusterin; Female; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Peptide Fragments; Protein Aggregation, Pathological; Proteome

Cerebral amyloid angiopathy (CAA) is caused by cerebrovascular deposition of. Thirty-six participants aged 55-80 years with probable CAA received intravenous placebo (. The mean change from baseline to Day 90 was 0.817 (ponezumab) and 0.958 (placebo): a mean ratio of 0.852 (90% CI 0.735-0.989) representing a trend towards. Ponezumab was safe and well-tolerated. The ponezumab group showed a trend towards treatment effect at Day 90 that was opposite to the hypothesized direction. The prespecified efficacy criteria were thus not met.

Topics: Adult; Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Antibodies, Monoclonal, Humanized; Cerebral Amyloid Angiopathy; Cerebral Hemorrhage; Double-Blind Method; Female; Humans; Immunologic Factors; Immunotherapy; Magnetic Resonance Imaging; Male; Middle Aged; Peptide Fragments; Treatment Outcome

Topics: Adult; Amyloid beta-Peptides; Brain; Brain Injuries, Traumatic; Cerebral Amyloid Angiopathy; Humans; Iatrogenic Disease; Male; Neurosurgical Procedures; Peptide Fragments

ApoJ/clusterin is a multifunctional protein highly expressed in the brain. The implication of ApoJ in β-amyloid (Aβ) fibrillization and clearance in the context of Alzheimer's disease has been widely studied, although the source and concentration of ApoJ that promotes or inhibits Aβ cerebral accumulation is not clear yet. ApoJ is abundant in plasma and approximately 20% can appear bound to HDL-particles. In this regard, the impact of plasmatic ApoJ and its lipidation status on cerebral β-amyloidosis is still not known. Hence, our main objective was to study the effect of a peripheral increase of free ApoJ or reconstituted HDL particles containing ApoJ in an experimental model of cerebral β-amyloidosis.. Fourteen-month-old APP23 transgenic mice were subjected to subchronic intravenous treatment with rHDL-rApoJ nanodiscs or free rApoJ for 1 month. Aβ concentration and distribution in the brain, as well as Aβ levels in plasma and CSF, were determined after treatments. Other features associated to AD pathology, such as neuronal loss and neuroinflammation, were also evaluated.. Both ApoJ-based treatments prevented the Aβ accumulation in cerebral arteries and induced a decrease in total brain insoluble Aβ. Our results demonstrate that an increase in circulating human rApoJ induces a reduction of insoluble Aβ and CAA load in the brain of APP23 mice. Thus, our study suggests that peripheral interventions, based on treatments with multifunctional physiological chaperones, offer therapeutic opportunities to regulate the cerebral Aβ load.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Brain; Cerebral Amyloid Angiopathy; Clusterin; Encephalitis; HEK293 Cells; Humans; Lipoproteins, HDL; Mice, Transgenic; Peptide Fragments; Recombinant Proteins

Clinical trials targeting β-amyloid peptides (Aβ) for Alzheimer disease (AD) failed for arguable reasons that include selecting the wrong stages of AD pathophysiology or Aβ being the wrong target. Targeting Aβ to prevent cerebral amyloid angiopathy (CAA) has not been rigorously followed, although the causal role of Aβ for CAA and related hemorrhages is undisputed. CAA occurs with normal aging and to various degrees in AD, where its impact and treatment is confounded by the presence of parenchymal Aβ deposition.. APPDutch mice develop CAA in the absence of parenchymal amyloid, mimicking hereditary cerebral hemorrhage with amyloidosis Dutch type (HCHWA-D). Mice were treated with a β-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitor. We used 3-dimensional ultramicroscopy and immunoassays for visualizing CAA and assessing Aβ in cerebrospinal fluid (CSF) and brain.. CAA onset in mice was at 22 to 24 months, first in frontal leptomeningeal and superficial cortical vessels followed by vessels penetrating the cortical layers. CSF Aβ increased with aging followed by a decrease of both Aβ40 and Aβ42 upon CAA onset, supporting the idea that combined reduction of CSF Aβ40 and Aβ42 is a specific biomarker for vascular amyloid. BACE1 inhibitor treatment starting at CAA onset and continuing for 4 months revealed a 90% Aβ reduction in CSF and largely prevented CAA progression and associated pathologies.. This is the first study showing that Aβ reduction at early disease time points largely prevents CAA in the absence of parenchymal amyloid. Our observation provides a preclinical basis for Aβ-reducing treatments in patients at risk of CAA and in presymptomatic HCHWA-D. ANN NEUROL 2019;86:561-571.

Topics: Amyloid beta-Peptides; Amyloid Precursor Protein Secretases; Animals; Aspartic Acid Endopeptidases; Biomarkers; Brain; Cerebral Amyloid Angiopathy; Disease Progression; Female; Humans; Mice; Mice, Transgenic; Peptide Fragments; Picolinic Acids; Thiazines

The Caribbean vervet monkey (. To characterize biomarkers associated with neurodegeneration, we measured cerebrospinal fluid (CSF) concentrations of Aβ. Aβ. Overall, these results support the vervet as a non-human primate model of amyloid-related neurodegeneration, such as Alzheimer's disease and cerebral amyloid angiopathy, and highlight Aβ

Topics: Aging; Alzheimer Disease; Amyloid beta-Peptides; Animals; Biomarkers; Brain; Cerebral Amyloid Angiopathy; Chlorocebus aethiops; Chromosomes, Mammalian; Female; Genetic Linkage; Genome-Wide Association Study; Male; Models, Animal; Monkey Diseases; Neurodegenerative Diseases; Neuroimaging; Organ Size; Pedigree; Peptide Fragments; tau Proteins

Transgenic rat models of Alzheimer's disease were used to examine differences in memory and brain histology. Double transgenic female rats (APP+PS1) over-expressing human amyloid precursor protein (APP) and presenilin 1 (PS1) and single transgenic rats (APP21) over-expressing human APP were compared with wild type Fischer rats (WT). The Barnes maze assessed learning and memory and showed that both APP21 and APP+PS1 rats made significantly more errors than the WT rats during the acquisition phase, signifying slower learning. Additionally, the APP+PS1 rats made significantly more errors following a retention interval, indicating impaired memory compared to both the APP21 and WT rats. Immunohistochemistry using an antibody against amyloid-β (Aβ) showed extensive and mostly diffuse Aβ plaques in the hippocampus and dense plaques that contained tau in the cortex of the brains of the APP+PS1 rats. Furthermore, the APP+PS1 rats also showed vascular changes, including cerebral amyloid angiopathy with extensive Aβ deposits in cortical and leptomeningeal blood vessel walls and venous collagenosis. In addition to the Aβ accumulation observed in arterial, venous, and capillary walls, APP+PS1 rats also displayed enlarged blood vessels and perivascular space. Overall, the brain histopathology and behavioral assessment showed that the APP+PS1 rats demonstrated behavioral characteristics and vascular changes similar to those commonly observed in patients with Alzheimer's disease.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Cerebral Amyloid Angiopathy; Disease Models, Animal; Humans; Memory; Peptide Fragments; Plaque, Amyloid; Presenilin-1; Rats; Rats, Transgenic

Cerebral amyloid angiopathy (CAA) can be associated with primary vasculitis of small/medium-sized leptomeningeal and cortical arteries, called CAA-related inflammation (CAA-ri).. To compare hemorrhagic and diffusion-weighted imaging (DWI) MRI features in CAA and CAA-ri.. We prospectively scored in a consecutive CAA and CAA-ri cohort: presence/number of chronic intracerebral hemorrhage (ICH), cerebral microbleeds (CMB), and cortical superficial siderosis (CSS) on initial T2*-weighted imaging, and DWI lesions on both initial and follow-up imaging. In a subgroup, ApoE, CSF, and 18F-florbetaben-positron emission tomography (FBB-PET) were also analyzed.. In CAA-ri, CMB presence was more frequent (100% versus 40%, p < 0.001) and CMB numbers higher (mean 137 versus 8, p < 0.001). No difference was observed for chronic ICH or CSS. DWI lesions were more frequent in acute compared to chronic CAA-ri (p = 0.025), whereas no such difference was observed between acute and chronic CAA (p = 0.18). Both ApoE4 (genotyping available in 22 CAA-ri and 48 CAA patients) carriers and homozygosity were more frequent in CAA-ri (48% versus 19% [p = 0.014] and 32% versus 2% [p < 0.001] respectively). CSF biomarker analyses (performed in 20 CAA-ri and 45 CAA patients) showed lower Aβ42 levels in CAA-ri compared to CAA (median 312 versus 422 pg/mL, p = 0.0032). FBB-PET (performed in 11 CAA-ri and 20 CAA patients) showed higher standardized uptake value ratios in CAA-ri compared with CAA, only significant when the pons was used as reference (p = 0.037).. Compared to CAA, CAA-ri was associated with higher CMB numbers, more frequent ApoE4 carriers and homozygotes, lower CSF Aβ42 levels, and more severe amyloid load on FBB-PET.

Topics: Aged; Aged, 80 and over; Amyloid beta-Peptides; Apolipoproteins E; Cerebral Amyloid Angiopathy; Cerebral Hemorrhage; Cohort Studies; Diffusion Magnetic Resonance Imaging; Female; Fluorodeoxyglucose F18; Humans; Image Processing, Computer-Assisted; Male; Middle Aged; Peptide Fragments; Positron-Emission Tomography; ROC Curve; tau Proteins; Vasculitis

We aimed to investigate if cerebral amyloid angiopathy (CAA) is more frequent in genetically determined than in sporadic early-onset forms of Alzheimer's disease (AD) (early-onset AD [EOAD]).. Neuroimaging features of CAA, apolipoprotein (APOE), and cerebrospinal fluid amyloid β (Aβ) 40 levels were studied in subjects with Down syndrome (DS, n = 117), autosomal-dominant AD (ADAD, n = 29), sporadic EOAD (n = 42), and healthy controls (n = 68).. CAA was present in 31%, 38%, and 12% of cognitively impaired DS, symptomatic ADAD, and sporadic EOAD subjects and in 13% and 4% of cognitively unimpaired DS individuals and healthy controls, respectively. APOE ε4 genotype was borderline significantly associated with CAA in sporadic EOAD (P = .06) but not with DS or ADAD. There were no differences in Aβ040 levels between groups or between subjects with and without CAA.. CAA is more frequently found in genetically determined AD than in sporadic EOAD. Cerebrospinal fluid Aβ40 levels are not a useful biomarker for CAA in AD.

Topics: Adult; Aged; Alzheimer Disease; Amyloid beta-Peptides; Apolipoprotein E4; Cerebral Amyloid Angiopathy; Down Syndrome; Female; Gene Frequency; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Peptide Fragments

Sporadic cerebral amyloid angiopathy (CAA) is characterized by cerebrovascular amyloid beta (Aβ) deposits and causes cerebral hemorrhage and dementia. The exact molecules that co-accumulate with cerebrovascular Aβ deposits are still not fully known. In our study here, we performed proteomic analyses with microdissected leptomeningeal arteries and cerebral neocortical arterioles from 8 cases with severe CAA, 12 cases with mild CAA, and 10 control cases without CAA, and we determined the levels of highly expressed proteins in cerebral blood vessels in CAA. We focused on sushi repeat-containing protein 1 (SRPX1), which is specifically expressed in CAA-affected cerebral blood vessels. Because SRPX1, which is known as a tumor suppressor gene, reportedly induced apoptosis in tumor cells, we hypothesized that SRPX1 may play an important role in Aβ-induced apoptosis in CAA. Immunohistochemical studies revealed that SRPX1 co-accumulated with Aβ deposits in cerebral blood vessels of all autopsied cases with severe CAA. In contrast, no SRPX1 co-accumulated with Aβ deposits in senile plaques. Furthermore, we demonstrated that both Aβ40 and Aβ42 bound to SRPX1 in vitro and enhanced SRPX1 expression in primary cultures of cerebrovascular smooth muscle cells. SRPX1 enhanced caspase activity induced by Aβ40. Knockdown of SRPX1, in contrast, reduced the formation of Aβ40 accumulations and the activity of caspase in cultured cerebrovascular smooth muscle cells. SRPX1 may thus be a novel molecule that is up-regulated in cerebrovascular Aβ deposits and that may increase Aβ-induced cerebrovascular degeneration in CAA.

Topics: Aged; Aged, 80 and over; Amyloid beta-Peptides; Animals; Apolipoproteins E; Brain; Cells, Cultured; Cerebral Amyloid Angiopathy; Female; Humans; Male; Membrane Proteins; Mice, Inbred C57BL; Middle Aged; Myocytes, Smooth Muscle; Neurofibrillary Tangles; Peptide Fragments; Protein Binding; Proteome; RNA, Small Interfering

Clusterin, also known as apoJ, is a lipoprotein abundantly expressed within the CNS. It regulates Aβ fibril formation and toxicity and facilitates amyloid-β (Aβ) transport across the blood-brain barrier. Genome-wide association studies have shown variations in the clusterin gene (CLU) to influence the risk of developing sporadic Alzheimer's disease (AD). To explore whether clusterin modulates the regional deposition of Aβ, we measured levels of soluble (NP40-extracted) and insoluble (guanidine-HCl-extracted) clusterin, Aβ40 and Aβ42 by sandwich ELISA in brain regions with a predilection for amyloid pathology-mid-frontal cortex (MF), cingulate cortex (CC), parahippocampal cortex (PH), and regions with little or no pathology-thalamus (TH) and white matter (WM). Clusterin level was highest in regions with plaque pathology (MF, CC, PH and PC), approximately mirroring the regional distribution of Aβ. It was significantly higher in AD than controls, and correlated positively with Aβ42 and insoluble Aβ40. Soluble clusterin level rose significantly with severity of cerebral amyloid angiopathy, and in MF and PC regions was highest in APOE ɛ4 homozygotes. In the TH and WM (areas with little amyloid pathology) clusterin was unaltered in AD and did not correlate with Aβ level. There was a significant positive correlation between the concentration of clusterin and the regional levels of insoluble Aβ42; however, the molar ratio of clusterin : Aβ42 declined with insoluble Aβ42 level in a region-dependent manner, being lowest in regions with predilection for Aβ plaque pathology. Under physiological conditions, clusterin reduces aggregation and promotes clearance of Aβ. Our findings indicate that in AD, clusterin increases, particularly in regions with most abundant Aβ, but because the increase does not match the rising level of Aβ42, the molar ratio of clusterin : Aβ42 in those regions falls, probably contributing to Aβ deposition within the tissue.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Apolipoproteins E; Brain; Cerebral Amyloid Angiopathy; Clusterin; Enzyme-Linked Immunosorbent Assay; Humans; Peptide Fragments; Plaque, Amyloid

Alzheimer's disease (AD) commonly accompanies cerebral amyloid angiopathy (CAA).. We aimed to reveal associations between CAA-related brain microbleeds and cerebrospinal fluid (CSF) markers in AD patients.. Patients with probable AD (n = 88) from consecutive patients in our memory clinic were evaluated for patient demographics, vascular risk factors, neuropsychological tests, apolipoprotein E phenotype, MRI including T2*-weighted image and fluid attenuated inversion recovery sequence, and CSF amyloid and tau markers.. The 88 patients with AD included 15 with microbleeds only in cortical/subcortical regions (cortical microbleeds) that could be CAA-related, 16 with microbleeds only in deep locations (deep microbleeds), 3 with microbleeds in both cortical and deep locations (mixed microbleeds), and 54 without microbleeds. The CSF levels of amyloid β-protein 1-40 (Aβ40) and amyloid β-protein 1-42 (Aβ42) were significantly lower in patients with cortical microbleeds than in those without microbleeds (p = 0.001 and p = 0.027, respectively). The result remained unchanged after adjustment for age, sex, apolipoprotein E E4 presence, and leukoaraiosis.. CAA-related cortical microbleeds would be associated with lower CSF levels of Aβ40 and Aβ42 in AD, reflecting the deposition of both Aβ40 and Aβ42 in the cerebrovasculature.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Apolipoproteins E; Cerebral Amyloid Angiopathy; Female; Humans; Intracranial Hemorrhages; Leukoaraiosis; Magnetic Resonance Imaging; Male; Mental Status Schedule; Middle Aged; Neuropsychological Tests; Peptide Fragments; Retrospective Studies; Risk Factors

We report a biomarker and genetic evaluation of four patients with cerebral amyloid angiopathy-related inflammation (CAA-ri) treated with corticosteroids. Patients presented with focal symptomatology and cognitive impairment. MRI revealed cortical microbleeds and asymmetrical hyperintense white matter lesions (WML). Cerebrospinal fluid (CSF) biomarker analyses showed increased anti-Aβ autoantibodies, t-Tau, and p-Tau and decreased Aβ40 and Aβ42. After treatment, focal symptomatology disappeared, and WML and anti-Aβ autoantibodies decreased. The APOEɛ4 allele was overrepresented. Florbetapir-PET showed cortical deposition with lower retention in swollen areas. In the case of suspected CAA-ri, both CSF anti-Aβ autoantibodies levels and Florbetapir-PET could provide highly useful data to guide the correct diagnosis.

Topics: Aged; Amyloid beta-Peptides; Aniline Compounds; Apolipoproteins E; Autoantibodies; Cerebral Amyloid Angiopathy; Ethylene Glycols; Female; Humans; Magnetic Resonance Imaging; Male; Meningoencephalitis; Peptide Fragments; Positron-Emission Tomography; Statistics, Nonparametric; tau Proteins

Cerebral amyloid angiopathy (CAA), characterized by the deposition of amyloid aggregates in the walls of cerebral vasculature, is a major factor in intracerebral hemorrhage and vascular cognitive impairment and is also associated closely with Alzheimer's disease (AD). We previously reported (99m)Tc-hydroxamamide ((99m)Tc-Ham) complexes with a bivalent amyloid ligand showing high binding affinity for β-amyloid peptide (Aβ(1-42)) aggregates present frequently in the form in AD. In this article, we applied them to CAA-specific imaging probes, and evaluated their utility for CAA-specific imaging. In vitro inhibition assay using Aβ(1-40) aggregates deposited mainly in CAA and a brain uptake study were performed for (99m)Tc-Ham complexes, and all (99m)Tc-Ham complexes with an amyloid ligand showed binding affinity for Aβ(1-40) aggregates and very low brain uptake. In vitro autoradiography of human CAA brain sections and ex vivo autoradiography of Tg2576 mice were carried out for bivalent (99m)Tc-Ham complexes ([(99m)Tc]SB2A and [(99m)Tc]BT2B), and they displayed excellent labeling of Aβ depositions in human CAA brain sections and high affinity and selectivity to CAA in transgenic mice. These results may offer new possibilities for the development of clinically useful CAA-specific imaging probes based on the (99m)Tc-Ham complex.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Animals; Autoradiography; Brain; Cerebral Amyloid Angiopathy; Diagnostic Imaging; Female; Humans; Male; Mice; Mice, Transgenic; Peptide Fragments; Protein Binding; Sensitivity and Specificity; Technetium Tc 99m Aggregated Albumin

Convexal subarachnoid hemorrhage (cSAH) is sometimes experienced in cerebral amyloid angiopathy (CAA), but ones that are repeated within a brief time period are not common. Also, it is often difficult to diagnose CAA when you experience a case of cSAH.. We examined the clinical course of 2 cases that showed cSAH repeatedly. We examined cerebrospinal fluid (CSF) concentrations of amyloid β protein (Aβ) 40 and 42 and tau protein as additional evidence for a diagnosis of CAA.. Case 1 presented with transient motor paresis of the left hand and case 2 with transient sensory disturbance of the left hand. CT scans showed cSAH on the right central sulcus in both patients. Case 1 showed development of intracerebral hemorrhage on the frontal lobe near the right central sulcus. Case 2 showed relapse of cSAH with recurrence of the same symptoms. These cases could not be diagnosed by image analysis, but were considered CAA by Aβ40, Aβ42 and tau protein in CSF.. Aβ in CSF can be presented here as support for the diagnosis of CAA that is difficult to diagnose by Boston criteria.

Topics: Aged; Amyloid beta-Peptides; Brain; Cerebral Amyloid Angiopathy; Diagnosis, Differential; Female; Humans; Middle Aged; Peptide Fragments; Subarachnoid Hemorrhage; tau Proteins; Tomography, X-Ray Computed

Senile plaques (SPs) and cerebral amyloid angiopathy (CAA) consisting of β-amyloid (Aβ) are major features in the brain of Alzheimer's disease (AD) patients and elderly humans and animals. In this study, we report the finding of SPs and CAA in an aged sea lion (30 years), which is the first demonstration of AD-related pathological changes in a marine animal. Histologically, SPs were observed at the cerebral cortex, most frequently at the frontal lobe, with two morphologically different types: the small round type and the large granular type. Only the small round SPs were positive for Congo red staining. The SPs were equally immunoreactive to Aβ40 and Aβ42 and were mainly composed of Aβ with an N-terminal pyroglutamate residue at position 3. Amyloid depositions at vessel walls were noted at the meninges and within the parenchyma. Interestingly, double immunofluorescence staining for Aβ40 and Aβ42 showed that the two subtypes were deposited segmentally in different parts of the vessel walls. The lesions observed in the sea lion suggest that Aβ deposition is widely present in various animal species, including marine mammals; however, the peculiar deposits similar to cotton wool plaques and the specific pattern of CAA are characteristic features of this animal.

Topics: Age Factors; Amyloid beta-Peptides; Animals; Blood Vessels; Cerebral Amyloid Angiopathy; Frontal Lobe; Immunohistochemistry; Male; Meninges; Peptide Fragments; Plaque, Amyloid; Sea Lions

Several studies have shown that the accumulation of β-amyloid peptides in the brain parenchyma or vessel wall generates an inflammatory environment. Some even suggest that there is a cause-and-effect relationship between inflammation and the development of Alzheimer's disease and/or cerebral amyloid angiopathy (CAA). Here, we studied the ability of wild-type Aβ1-40 -peptide (the main amyloid peptide that accumulates in the vessel wall in sporadic forms of CAA) to modulate the phenotypic transition of vascular smooth muscle cells (VSMCs) toward an inflammatory/de-differentiated state. We found that Aβ1-40 -peptide alone neither induces an inflammatory response, nor decreases the expression of contractile markers; however, the inflammatory response of VSMCs exposed to Aβ1-40 -peptide prior to the addition of the pro-inflammatory cytokine IL-1β is greatly intensified compared with IL-1β-treated VSMCs previously un-exposed to Aβ1-40 -peptide. Similar conclusions could be drawn when tracking the decline of contractile markers. Furthermore, we found that the mechanism of this potentiation highly depends on an Aβ1-40 preactivation of the PI3 Kinase and possibly NFκB pathway; indeed, blocking the activation of these pathways during Aβ1-40 -peptide treatment completely suppressed the observed potentiation. Finally, strengthening the possible in vivo relevance of our findings, we evidenced that endothelial cells exposed to Aβ1-40 -peptide generate an inflammatory context and have similar effects than the ones described with IL-1β. These results reinforce the idea that intraparietal amyloid deposits triggering adhesion molecules in endothelial cells, contribute to the transition of VSMCs to an inflammatory/de-differentiated phenotype. Therefore, we suggest that acute inflammatory episodes may increase vascular alterations and contribute to the ontogenesis of CAA.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Cell Dedifferentiation; Cells, Cultured; Cerebral Amyloid Angiopathy; Culture Media, Conditioned; Enzyme Activation; Inflammation; Interleukin-1beta; Mice; Muscle, Smooth, Vascular; NF-kappa B; Peptide Fragments; Phosphatidylinositol 3-Kinases

We studied longitudinal changes of the levels of anti-amyloid β (anti-Aβ) antibody, amyloid β (Aβ) protein, and interleukin 8 (IL-8) in cerebrospinal fluid (CSF) of a patient with cerebral amyloid angiopathy-related inflammation (CAA-ri) in whom steroid treatment resulted in clinical improvement. The diagnosis of CAA-ri was established with brain biopsy. Levels of anti-Aβ 42 antibody, Aβ 40, Aβ 42 and IL-8 in CSF were measured in the CAA-ri patient at 23 time points in the 8-month clinical course. These CSF samples were divided into 2 groups: those obtained before (n = 12) and those after (n = 11) oral corticosteroid therapy was started. We compared these levels between CSF samples obtained before and after therapy. The mean levels of anti-Aβ 42 antibody and IL-8 were significantly higher in CSF samples of the CAA-ri patient before oral corticosteroid therapy than those after therapy. A positive correlation was noted between levels of anti-Aβ 42 antibodies and IL-8 in CSF of this patient. There were no significant differences of mean levels of Aβ 40 and Aβ 42 between CSF samples obtained before and after oral corticosteroid therapy. It was possible that the autoinflammatory process with anti-Aβ 42 antibodies and IL-8 may have been involved in the pathogenesis of CAA-ri, and that corticosteroid therapy directly affected levels of anti-Aβ 42 antibody and IL-8. In summary, CAA-ri encephalopathy is a relapsing or progressive disorder and may be treatable by adequate immunosuppressive therapy. The anti-Aβ 42 antibody in CSF is a useful biological marker for therapeutic monitoring of CAA-ri.

Topics: Adrenal Cortex Hormones; Aged; Aged, 80 and over; Amyloid beta-Peptides; Antibodies; Biopsy; Brain; Cell Count; Cerebral Amyloid Angiopathy; Female; Humans; Inflammation; Interleukin-8; Magnetic Resonance Imaging; Peptide Fragments; Polymerase Chain Reaction

The characteristic neuropathological changes associated with Alzheimer's disease (AD) and other lines of evidence support the amyloid cascade hypothesis. Viewing amyloid deposits as the prime instigator of dementia has now led to clinical trials of multiple strategies to remove or prevent their formation. We performed neuropathological and biochemical assessments of 3 subjects treated with bapineuzumab infusions. Histological analyses were conducted to quantify amyloid plaque densities, Braak stages and the extent of cerebral amyloid angiopathy (CAA). Amyloid-β (Aβ) species in frontal and temporal lobe samples were quantified by ELISA. Western blots of amyloid-β precursor protein (AβPP) and its C-terminal (CT) fragments as well as tau species were performed. Bapineuzumab-treated (Bapi-AD) subjects were compared to non-immunized age-matched subjects with AD (NI-AD) and non-demented control (NDC) cases. Our study revealed that Bapi-AD subjects exhibited overall amyloid plaque densities similar to those of NI-AD cases. In addition, CAA was moderate to severe in NI-AD and Bapi-AD patients. Although histologically-demonstrable leptomeningeal, cerebrovascular and neuroparenchymal-amyloid densities all appeared unaffected by treatment, Aβ peptide profiles were significantly altered in Bapi-AD subjects. There was a trend for reduction in total Aβ42 levels as well as an increase in Aβ40 which led to a corresponding significant decrease in Aβ42:Aβ40 ratio in comparison to NI-AD subjects. There were no differences in the levels of AβPP, CT99 and CT83 or tau species between Bapi-AD and NI-AD subjects. The remarkable alteration in Aβ profiles reveals a dynamic amyloid production in which removal and depositional processes were apparently perturbed by bapineuzumab therapy. Despite the alteration in biochemical composition, all 3 immunized subjects exhibited continued cognitive decline.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Antibodies, Monoclonal, Humanized; Brain; Cerebral Amyloid Angiopathy; Cognition Disorders; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunotherapy; Male; Peptide Fragments; tau Proteins; Tomography, X-Ray Computed

Cerebral amyloid angiopathy-related inflammation (CAA-ri) is characterized by vasogenic edema and multiple cortical/subcortical microbleeds, sharing several aspects with the recently defined amyloid-related imaging abnormalities (ARIA) reported in Alzheimer's disease (AD) passive immunization therapies. Herein, we investigated the role of anti-amyloid β (Aβ) autoantibodies in the acute and remission phases of CAA-ri.. We used a novel ultrasensitive technique on patients from a retrospective multicenter case-control study, and evaluated the anti-Aβ autoantibody concentration in the cerebrospinal fluid (CSF) of 10 CAA-ri, 8 CAA, 14 multiple sclerosis, and 25 control subjects. Levels of soluble Aβ40, Aβ42, tau, P-181 tau, and APOE genotype were also investigated.. During the acute phase of CAA-ri, anti-Aβ autoantibodies were specifically increased and directly correlated with Aβ mobilization, together with augmented tau and P-181 tau. Following clinical and radiological remission, autoantibodies progressively returned to control levels, and both soluble Aβ and axonal degeneration markers decreased in parallel.. Our data support the hypothesis that the pathogenesis of CAA-ri may be mediated by a selective autoimmune reaction against cerebrovascular Aβ, directly related to autoantibody concentration and soluble Aβ. The CSF dosage of anti-Aβ autoantibodies with the technique here described can thus be proposed as a valid alternative tool for the diagnosis of CAA-ri. Moreover, given the similarities between ARIA developing spontaneously and those observed during immunization trials, anti-Aβ autoantibodies can be considered as novel potential biomarkers in future amyloid-modifying therapies for the treatment of AD and CAA.

Topics: Adult; Aged; Amyloid beta-Peptides; Apolipoproteins E; Autoantibodies; Brain; Case-Control Studies; Cerebral Amyloid Angiopathy; Female; Humans; Inflammation; Male; Middle Aged; Peptide Fragments; Phosphorylation; Retrospective Studies; Steroids; tau Proteins

Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA) are two common pathologies associated with β-amyloid (Aβ) accumulation and inflammation in the brain; neither is well understood. The objective of this study was to evaluate human post-mortem brains from AD subjects with purely parenchymal pathology, and those with concomitant CAA (and age-matched controls) for differential expression of microglia-associated Aβ ligands thought to mediate Aβ clearance and the association of these receptors with complement activation. Homogenates of brain parenchyma and enriched microvessel fractions from occipital cortex were probed for levels of C3b, membrane attack complex (MAC), CD11b and α-2-macroglobulin and immunoprecipitation was used to immunoprecipitate (IP) CD11b complexed with C3b and Aβ. Both C3b and MAC were significantly increased in CAA compared to AD-only and controls and IP showed significantly increased CD11b/C3b complexes with Aβ in AD/CAA subjects. Confocal microscopy was used to visualize these interactions. MAC was remarkably associated with CAA-affected blood vessels compared to AD-only and control vessels. These findings are consistent with an Aβ clearance mechanism via microglial CD11b that delivers Aβ and C3b to blood vessels in AD/CAA, which leads to Aβ deposition and propagation of complement to the cytolytic MAC, possibly leading to vascular fragility.

Topics: Actins; Adult; Aged; Aged, 80 and over; Alzheimer Disease; Amyloid; Amyloid beta-Peptides; Analysis of Variance; Antigens, CD; Brain; CD11b Antigen; Cerebral Amyloid Angiopathy; Complement Membrane Attack Complex; Female; Humans; Immunoprecipitation; Male; Microglia; Microvessels; Middle Aged; Peptide Fragments; Receptors, Complement

Cerebral microbleeds (MBs) may relate to amyloid in dementia. We selected 26 probable Alzheimer's disease (AD) patients with MBs, 26 age- and sex-matched AD patients without MBs, 11 vascular dementia (VaD) patients, and 22 patients with subjective complaints. We measured amyloid beta 1-42 (Aβ42) and 1-40 (Aβ40) in cerebrospinal fluid (CSF) and plasma, and blood-brain barrier (BBB) function using albumin ratios. CSF Aβ42 was lowest in AD with MBs, whereas Aβ40 was selectively decreased in VaD. In plasma, amyloid-beta was nonsignificantly elevated in VaD compared with controls. Higher albumin ratios in VaD suggested blood-brain barrier dysfunction. A MB pattern suggestive of cerebral amyloid angiopathy (CAA) related to lower CSF Aβ42, while a non-cerebral amyloid angiopathy specific MB distribution related to higher plasma Aβ40. Amyloid-beta is differentially implicated in AD with MBs and VaD. MB distribution related to different amyloid profiles, supporting distinct etiologies. Our results suggest that Aβ42 is retained in cerebrovasculature of AD patients with MBs, while in contrast, VaD patients may possibly drain amyloid.

Topics: Aged; Alzheimer Disease; Amyloid beta-Peptides; Blood-Brain Barrier; Cerebral Amyloid Angiopathy; Cerebral Hemorrhage; Dementia, Vascular; Female; Humans; Male; Middle Aged; Peptide Fragments

Amyloid precursor protein (APP) proteolysis is essential for production of amyloid-β (Aβ) peptides that form β-amyloid plaques in brains of Alzheimer disease (AD) patients. Recent focus has been directed toward a group of naturally occurring anti-amyloidogenic polyphenols known as flavonoids. We orally administered the flavonoid tannic acid (TA) to the transgenic PSAPP mouse model of cerebral amyloidosis (bearing mutant human APP and presenilin-1 transgenes) and evaluated cognitive function and AD-like pathology. Consumption of TA for 6 months prevented transgene-associated behavioral impairment including hyperactivity, decreased object recognition, and defective spatial reference memory, but did not alter nontransgenic mouse behavior. Accordingly, brain parenchymal and cerebral vascular β-amyloid deposits and abundance of various Aβ species including oligomers were mitigated in TA-treated PSAPP mice. These effects occurred with decreased cleavage of the β-carboxyl-terminal APP fragment, lowered soluble APP-β production, reduced β-site APP cleaving enzyme 1 protein stability and activity, and attenuated neuroinflammation. As in vitro validation, we treated well characterized mutant human APP-overexpressing murine neuron-like cells with TA and found significantly reduced Aβ production associated with less amyloidogenic APP proteolysis. Taken together, these results raise the possibility that dietary supplementation with TA may be prophylactic for AD by inhibiting β-secretase activity and neuroinflammation and thereby mitigating AD pathology.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid Precursor Protein Secretases; Animals; Aspartic Acid Endopeptidases; Cell Line; Cerebral Amyloid Angiopathy; Cognition Disorders; Disease Models, Animal; Encephalitis; Female; Gliosis; Humans; Male; Maze Learning; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Transgenic; Neurons; Peptide Fragments; Tannins

Cerebral amyloid angiopathy (CAA) is an important cause of intracerebral hemorrhages in the elderly, characterized by amyloid-β (Aβ) peptide accumulating in central nervous system blood vessels. Within the vessel walls, Aβ-peptide deposits [composed mainly of wild-type (WT) Aβ(1-40) peptide in sporadic forms] induce impaired adhesion of vascular smooth muscle cells (VSMCs) to the extracellular matrix (ECM) associated with their degeneration. This process often results in a loss of blood vessel wall integrity and ultimately translates into cerebral ischemia and microhemorrhages, both clinical features of CAA. In this study, we decipher the molecular mechanism of matrix metalloprotease (MMP)-2 activation in WT-Aβ(1-40) -treated VSMC and provide evidence that MMP activity, although playing a critical role in cell detachment disrupting ECM components, is not involved in the WT-Aβ(1-40) -induced degeneration of VSMCs. Indeed, whereas this peptide clearly induced VSMC apoptosis, neither preventing MMP-2 activity nor hampering the expression of membrane type1-MMP, or preventing tissue inhibitors of MMPs-2 (TIMP-2) recruitment (two proteins evidenced here as involved in MMP-2 activation), reduced the number of dead cells. Even the use of broad-range MMP inhibitors (GM6001 and Batimastat) did not affect WT-Aβ(1-40) -induced cell apoptosis. Our results, in contrast to those obtained using the Aβ(1-40) Dutch variant suggesting a link between MMP-2 activity, VSMC mortality and degradation of specific matrix components, indicate that the ontogenesis of the Dutch familial and sporadic forms of CAAs is different. ECM degradation and VSMC degeneration would be tightly connected in the Dutch familial form while being two independent processes in sporadic forms of CAA.

Topics: Amino Acid Sequence; Amyloid beta-Peptides; Animals; Apoptosis; Cell Death; Cell Survival; Cells, Cultured; Cerebral Amyloid Angiopathy; Humans; Male; Matrix Metalloproteinases; Molecular Sequence Data; Muscle, Smooth, Vascular; Peptide Fragments; Rats; Rats, Wistar; Transfection

According to the modified Boston criteria, cerebral amyloid angiopathy (CAA) can present with lobar hematoma (LH) or superficial siderosis (SS). Recently, decreased CSF β-amyloid peptide 40 and 42 (Aβ40; Aβ42) and increased total and phosphorylated tau (t-tau; p-tau) concentrations have been described in CAA presenting with LH. Our aim was to analyze CSF biomarkers as a diagnostic tool for CAA according to the modified Boston criteria. We prospectively included patients with possible or probable CAA according to the modified Boston criteria. CSF was analyzed for t-tau, p-tau, Aβ42, and Aβ40. Data were compared with AD patients (n = 42) and controls (n = 14). Thirteen CAA patients were included, nine presenting with LH and four with SS. T-tau and p-tau levels in CAA were higher than controls, but lower than in AD. Differences in t-tau and p-tau levels between CAA versus controls and AD were all significant apart of the CAA p-tau levels comparison with controls. Aβ42 levels in CAA were significantly lower than in controls, and slightly higher than in AD, though non-significantly. Aβ40 levels in CAA were non-significantly lower than in controls, and significantly lower than in AD. Combining the findings of our study and the earlier report, we confirm that patients with suspected CAA have significantly different values for t-tau, Aβ42, Aβ42/t-tau, and Aβ40. Especially Aβ40 levels seem to be of clinical interest to differentiate CAA from AD. CSF biomarkers have to be analyzed in a larger number of CAA patients, and compared to patients with other disorders causing LH or SS.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Biomarkers; Cerebral Amyloid Angiopathy; Female; Humans; Male; Middle Aged; Peptide Fragments; Prospective Studies; tau Proteins

Senile plaques (SPs) containing amyloid β peptide (Aβ) 1-42 are the major species present in Alzheimer disease (AD), whereas Aβ1-40 is the major constituent of arteriolar walls affected by cerebral amyloid angiopathy. The water channel proteins astrocytic aquaporin 1 (AQP1) and aquaporin 4 (AQP4) are known to be abnormally expressed in AD brains, but the expression of AQPs surrounding SPs and cerebral amyloid angiopathy has not been described in detail. Here, we investigated whether AQP expression is associated with each species of Aβ deposited in human brains affected by either sporadic or familial AD. Immunohistochemical analysis demonstrated more numerous AQP1-positive reactive astrocytes in the AD cerebral cortex than in controls, located close to Aβ42- or Aβ40-positive SPs. In AD cases, however, AQP1-positive astrocytes were not often observed in Aβ-rich areas, and there was a significant negative correlation between the levels of AQP1 and Aβ42 assessed semiquantitatively. We also found that Aβ plaque-like AQP4 was distributed in association with Aβ42- or Aβ40-positive SPs and that the degree of AQP4 expression around Aβ40-positive vessels was variable. These findings suggest that a defined population of AQP1-positive reactive astrocytes may modify Aβ deposition in the AD brain, whereas the Aβ deposition process might alter astrocytic expression of AQP4.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Aquaporin 1; Aquaporin 4; Aquaporins; Cerebral Amyloid Angiopathy; Female; Fluorescent Antibody Technique; Humans; Immunohistochemistry; Male; Middle Aged; Organ Size; Paraffin Embedding; Peptide Fragments; Plaque, Amyloid

A middle-aged male suffering from encephalopathy with cerebral amyloid angiopathy (CAA) with amyloid beta (Aβ) presented with initial symptoms of transient consciousness disturbance and left visual field photophobia. Lesions with aberrantly high signal on T2-weighted magnetic resonance imaging (MRI) of the brain appeared in the right temporal lobe posterior to the occipital lobe and spread to other areas. Brain biopsy revealed Aβ deposits in vascular walls and numerous diffuse plaques in parenchymal areas. Based on MRI findings, Initial corticosteroid therapy with beta methasone effectively improved the neurological symptoms of consciousness disturbance and motor deficits. After corticosteroid therapy was stopped at 4 weeks, recurrence occurred. Additional corticosteroids did not improve clinical symptoms and the patient progressed to a bed-ridden state with a severe consciousness disturbance. Notably, CSF Aβ1-42 and CSF Aβ1-40 decreased while the recurrent encephalopathy worsened. After intense deterioration, the patient became stable. CSF Aβ1-42 increased but remained at a very low level. This case of CAA encephalopathy with apolipoprotein E ϵ4/ϵ4 homozygosity showed Aβ deposits in vascular walls and numerous diffuse plaques in parenchymal areas. The clinical course suggests that reduction of CSF Aβ1-42 and Aβ1-40 might be related to clinical deterioration in cases of encephalopathy.

Topics: Amyloid beta-Peptides; Apolipoproteins E; Biopsy; Brain Diseases, Metabolic; Cerebral Amyloid Angiopathy; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Occipital Lobe; Peptide Fragments; Plaque, Amyloid; Temporal Lobe

Alzheimer's disease (AD) is characterized by amyloid beta (A beta) accumulation in the brain and is classified as familial early-onset (FAD) or sporadic late-onset (SAD). Evidences suggest that deficits in the brain expression of insulin degrading enzyme (IDE) and neprilysin (NEP), both proteases involved in amyloid degradation, may promote A beta deposition in SAD. We studied by immunohistochemistry IDE and NEP cortical expression in SAD and FAD samples carrying the E280A presenilin-1 missense mutation. We showed that IDE, a soluble peptidase, is linked with aggregated A beta 40 isoform while NEP, a membrane-bound protease, negatively correlates with amyloid angiopathy and its expression in the senile plaques is independent of aggregated amyloid and restricted to SAD cases. NEP, but not IDE, is over-expressed in dystrophic neurites, both proteases are immunoreactive in activated astrocytes but not in microglia and IDE was the only one detected in astrocytes of white matter from FAD cases. Collectively, our results support the notion that gross conformational changes involved in the modification from "natively folded-active" to "aggregated-inactive" IDE and NEP may be a relevant pathogenic mechanism in SAD.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Astrocytes; Cerebral Amyloid Angiopathy; Cerebral Cortex; Female; Humans; Insulysin; Male; Microglia; Middle Aged; Neprilysin; Peptide Fragments; Plaque, Amyloid; Presenilin-1; Protein Conformation

Despite accumulating evidence of a central role for oligomeric amyloid beta (Abeta) in the pathogenesis of Alzheimer's Disease (AD), there is scant information on the relationship between the levels and distribution of oligomeric Abeta and those of other neurodegenerative abnormalities in AD. In the present study, we have found oligomeric Abeta to be associated with both diffuse and neuritic plaques (mostly co-localized with Abeta(1-42)) and with cerebrovascular deposits of Abeta in paraffin sections of formalin-fixed human brain tissue. The amount of oligomeric Abeta that was labeled in the sections correlated with total Abeta plaque load, but not phospho-tau load, cerebral amyloid angiopathy (CAA) severity or APOE genotype. Although soluble, oligomeric and insoluble Abeta levels were all significantly increased in AD brain homogenates, case-to-case variation and overlap between AD and controls were considerable. Over the age-range studied (43-98 years), the levels of soluble Abeta, oligomeric Abeta(42), oligomeric Abeta(40) and insoluble Abeta did not vary significantly with age. Oligomeric Abeta(1-42) and insoluble Abeta levels were significantly higher in women. Overall, the level of insoluble Abeta, but neither oligomeric nor soluble Abeta, was associated with Braak stage, CAA severity and APOEepsilon4 frequency, raising questions as to the role of soluble and oligomeric Abeta in the progression of AD.

Topics: Adult; Age Factors; Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Apolipoproteins E; Brain; Cerebral Amyloid Angiopathy; Cohort Studies; Female; Humans; Male; Middle Aged; Neurofibrillary Tangles; Peptide Fragments; Plaque, Amyloid; Sex Factors; tau Proteins

Alzheimer's disease is associated to a cerebral amyloid angiopathy with dysregulation of cerebral blood flow (CBF). In vitro studies have shown that short-term application of beta-amyloid (Abeta) peptides to isolated vessels affects vascular tone within 1h, but no studies have examined the effect of long-term incubation with Abeta. Here we evaluate the effect of Abeta((1-40)) and Abeta((25-35)) in rat basilar artery for up to 24h. Basilar artery segments were incubated with 25microeta((1-40)) or Abeta((25-35)), for 6 or 24h. After treatment, arteries were mounted in a wire myograph, in physiological salt solution gassed with O(2)/CO(2), in the absence of Abeta, and challenged with vasoconstrictors and vasodilators. Vasomotor responses were not significantly changed by 6h treatment with Abeta peptides whereas 24h treatment with either Abeta((25-35)) or Abeta((1-40)) increased vasoconstriction to 5-hydroxytryptamine (5-HT) and reduced endothelium-dependent vasodilatation to acetylcholine (ACh). Analysis of endothelial cells did not show apoptotic changes associated to endothelial dysfunction, as assessed by TUNEL immunostaining and examination of nuclear morphology, but basal phosphorylation of endothelial nitric oxide synthase (at serine 1177) appeared reduced. These data suggest that long incubation with Abeta peptides induces an alteration of endothelial function in isolated basilar artery, involving eNOS activity without changing cell morphology. This endothelial dysfunction may play a role in the pathogenesis of CBF dysregulation occurring in cerebral amyloid angiopathy and Alzheimer's disease.

Topics: Acetylcholine; Amyloid beta-Peptides; Animals; Basilar Artery; Cerebral Amyloid Angiopathy; Dose-Response Relationship, Drug; Endothelium, Vascular; Male; Nitric Oxide Synthase Type III; Peptide Fragments; Phosphorylation; Rats; Rats, Sprague-Dawley; Serotonin; Time Factors; Tissue Culture Techniques; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

Cerebral amyloid angiopathy (CAA) is a common pathological finding in Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis of the Dutch type; in this latter condition it is caused by deposition of mutated amyloid beta protein (Abeta Glu22Gln; D-Abeta(1-40)). Previously, we found a dependence of the Abeta-mediated toxicity and apolipoprotein E (apoE) production by cultured pericytes on apoE genotype. Given their close association with the cerebrovascular wall both astrocytes and pericytes may be involved in CAA development, a process that includes Abeta deposition and clearance and that may be affected by interaction with locally produced apolipoprotein E (apoE). Although astrocytes are regarded as the major source of apolipoprotein E (apoE) in the brain, also pericytes produce apoE. In this study we compared the apoE production capacity, the effects of apoE on D-Abeta(1-40) internalization, D-Abeta(1-40) cell surface accumulation and the vulnerability for D-Abeta(1-40)-induced toxicity of either cell type in order to quantify the relative contributions of astrocytes and pericytes in the various processes that contribute to CAA formation. Strikingly, cultured astrocytes produced only 3-10% of the apoE amounts produced by pericytes. Furthermore, pericytes with the apoE epsilon4 allele produced three times less apoE and were more vulnerable to D-Abeta(1-40) treatment than pericytes without an epsilon4 allele. Such relations were not observed with astrocytes in vitro. Both pericytes and astrocytes, however, were protected from Abeta-induced cytotoxicity by high levels of pericyte-derived apoE, but not recombinant apoE. In addition, pericyte-derived apoE dose-dependently decreased both internalization of Abeta and Abeta accumulation at the cell surface in either cell type. The present data suggest that apoE produced by pericytes, rather than astrocyte-produced apoE, modulates Abeta cytotoxicity and Abeta removal near the vasculature in the brain. Furthermore, since apoE production in pericytes is genotype dependent, this may contribute to the apoE genotype-dependent development of CAA in vivo.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Apolipoprotein E3; Apolipoprotein E4; Apolipoproteins E; Astrocytes; Brain; Cell Death; Cell Membrane; Cells, Cultured; Cerebral Amyloid Angiopathy; Culture Media, Conditioned; Female; Genotype; Humans; Male; Middle Aged; Mutation; Peptide Fragments; Pericytes; Recombinant Proteins

Glycosaminoglycans (GAGs), in particular as part of heparan sulfate proteoglycans, are associated with cerebral amyloid angiopathy (CAA). Similarly, GAGs are also associated with the severe CAA found in patients suffering from hereditary cerebral hemorrhage with amyloidosis of the Dutch type (HCHWA-D), where the amyloid beta (Abeta) peptide contains the Dutch mutation (DAbeta(1-40)). This suggests a role for GAGs in vascular Abeta aggregation. It was the aim of this study to investigate the effect of different GAGs (heparin, chondroitin sulfate, heparan sulfate), the macromolecule dextran sulfate and, using desulfated heparins, the role of GAG sulfate moieties on the in vitro aggregation of CAA-associated DAbeta(1-40) and on DAbeta(1-40)-induced toxicity of cultured cerebrovascular cells. We also aimed to study the in vivo distribution of various sulfated heparan sulfate GAG epitopes in CAA. Of all GAGs tested, heparin was the strongest inducer of aggregation of DAbeta(1-40) in the different aggregation assays, with both heparin and heparan sulfate reducing Abeta-induced cellular toxicity. Furthermore, (partial) removal of the sulfate moieties of heparin partially abolished the effects of heparin on aggregation and cellular toxicity, suggesting an essential role for the sulfate moieties in heparin. Finally, we demonstrated the in vivo association of sulfated heparan sulfate (HS) GAGs with CAA. We conclude that sulfate moieties within GAGs, like heparin and HS, have an important role in Abeta aggregation in CAA and in Abeta-mediated toxicity of cerebrovascular cells.

Topics: Aged; Alzheimer Disease; Amyloid beta-Peptides; Cell Death; Cells, Cultured; Cerebral Amyloid Angiopathy; Chondroitin Sulfates; Female; Heparin; Heparitin Sulfate; Humans; Mutation; Occipital Lobe; Peptide Fragments; Pericytes

The occurrence and progression of cerebral β-amyloid angiopathy and β-amyloid plaques in sporadic Alzheimer's disease may be attributed to aging-related deficiencies in β-amyloid drainage along cerebral perivascular pathways. To elucidate high-definition characteristics of cerebral β-amyloid deposition, we performed immunogold silver staining for β-amyloid-40 and β-amyloid-42 on semithin LR White-embedded tissue sections from 7 Alzheimer's disease/severe cerebral β-amyloid angiopathy, 9 Alzheimer's disease/mild cerebral β-amyloid angiopathy, 5 old control, and 4 young control autopsy brains. In vessel walls, β-amyloid-40 and β-amyloid-42 deposits were unevenly distributed along the adventitia and among the medial smooth muscle cells. β-Amyloid-40 immunoreactivity appeared greater than that of β-amyloid-42 in vessel walls, with β-amyloid-42 being preferentially located on their abluminal regions. In capillary walls, either β-amyloid-40 or β-amyloid-42 deposits or both were present in 6 of 7 severe cerebral β-amyloid angiopathy and in 1 of 9 mild cerebral β-amyloid angiopathy cases, with a marked variation in thickness and focally abluminal excrescences. In 5 of 7 severe cerebral β-amyloid angiopathy cases, a subset of β-amyloid-laden capillaries revealed either β-amyloid-40 or β-amyloid-42 deposits or both radiating from their walls into the surrounding neuropil ("pericapillary deposits"). No vascular β-amyloid-40 or β-amyloid-42 deposits were observed in any of the controls. In conclusion, the patterns of β-amyloid-42 and β-amyloid-40 immunoreactivity in vessel walls suggest that β-amyloid deposits occur in the vascular basement membranes along cerebral perivascular drainage pathways, extending from cortical capillaries to leptomeningeal arteries. The presence of pericapillary β-amyloid deposits suggests that a subset of β-amyloid plaques originate from β-amyloid-laden capillaries, particularly in Alzheimer's disease brains that exhibit preferential capillary involvement by cerebral β-amyloid angiopathy.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Brain; Capillaries; Cerebral Amyloid Angiopathy; Female; Humans; Male; Middle Aged; Muscle, Smooth, Vascular; Peptide Fragments; Staining and Labeling; Young Adult

The only recognized genetic determinant of the common forms of Alzheimer's disease (AD) is the epsilon 4 allele of the apolipoprotein E gene (APOE). To identify new candidate genes, we recently performed transcriptomic analysis of 2741 genes in chromosomal regions of interest using brain tissue of AD cases and controls. From 82 differentially expressed genes, 1156 polymorphisms were genotyped in two independent discovery subsamples (n=945). Seventeen genes exhibited at least one polymorphism associated with AD risk, and following correction for multiple testing, we retained the interleukin (IL)-33 gene. We first confirmed that the IL-33 expression was decreased in the brain of AD cases compared with that of controls. Further genetic analysis led us to select three polymorphisms within this gene, which we analyzed in three independent case-control studies. These polymorphisms and a resulting protective haplotype were systematically associated with AD risk in non-APOE epsilon 4 carriers. Using a large prospective study, these associations were also detected when analyzing the prevalent and incident AD cases together or the incident AD cases alone. These polymorphisms were also associated with less cerebral amyloid angiopathy (CAA) in the brain of non-APOE epsilon 4 AD cases. Immunohistochemistry experiments finally indicated that the IL-33 expression was consistently restricted to vascular capillaries in the brain. Moreover, IL-33 overexpression in cellular models led to a specific decrease in secretion of the A beta(40) peptides, the main CAA component. In conclusion, our data suggest that genetic variants in IL-33 gene may be associated with a decrease in AD risk potentially in modulating CAA formation.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Apolipoprotein E4; Brain; Case-Control Studies; Cell Line, Transformed; Cerebral Amyloid Angiopathy; Chlorocebus aethiops; COS Cells; Female; Follow-Up Studies; Genetic Load; Genetic Predisposition to Disease; Genome-Wide Association Study; Genotype; Humans; Interleukin-33; Interleukins; International Cooperation; Male; Neuroblastoma; Oligonucleotide Array Sequence Analysis; Peptide Fragments; Polymorphism, Single Nucleotide; Proportional Hazards Models; Retrospective Studies; RNA, Messenger; Transfection

Alzheimer's disease (AD) is characterized by accumulation and deposition of Abeta peptides in the brain. Abeta deposition in cerebrovessels occurs in many AD patients and results in cerebral amyloid angiopathy (AD/CAA). Since Abeta can be transported across blood-brain barrier (BBB), aberrant Abeta trafficking across BBB may contribute to Abeta accumulation in the brain and CAA development. Expression analyses of 273 BBB-related genes performed in this study showed that the drug transporter, ABCG2, was significantly upregulated in the brains of AD/CAA compared with age-matched controls. Increased ABCG2 expression was confirmed by Q-PCR, Western blot, and immunohistochemistry. Abcg2 was also increased in mouse AD models, Tg-SwDI and 3XTg. Abeta alone or in combination with hypoxia/ischemia failed to stimulate ABCG2 expression in BBB endothelial cells; however, conditioned media from Abeta-activated microglia strongly induced ABCG2 expression. ABCG2 protein in AD/CAA brains interacted and coimmunoprecipitated with Abeta. Overexpression of hABCG2 reduced drug uptake in cells; however, interaction of Abeta(1-40) with ABCG2 impaired ABCG2-mediated drug efflux. The role of Abcg2 in Abeta transport at the BBB was investigated in Abcg2-null and wild-type mice after intravenous injection of Cy5.5-labeled Abeta(1-40) or scrambled Abeta(40-1). Optical imaging analyses of live animals and their brains showed that Abcg2-null mice accumulated significantly more Abeta in their brains than wild-type mice. The finding was confirmed by immunohistochemistry. These results suggest that ABCG2 may act as a gatekeeper at the BBB to prevent blood Abeta from entering into brain. ABCG2 upregulation may serve as a biomarker of CAA vascular pathology in AD patients.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Animals; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Blood-Brain Barrier; Cell Line; Cells, Cultured; Cerebral Amyloid Angiopathy; Drug Resistance, Multiple; Humans; Mice; Mice, Knockout; Mice, Transgenic; Neoplasm Proteins; Peptide Fragments; Up-Regulation

Cerebral amyloid angiopathy is caused by deposition of the amyloid beta protein in the cerebral vasculature. In analogy to previous observations in Alzheimer disease, we hypothesized that analysis of amyloid beta(40) and beta(42) proteins in the cerebrospinal fluid might serve as a molecular biomarker. We observed strongly decreased cerebrospinal fluid amyloid beta(40) (p < 0.01 vs controls or Alzheimer disease) and amyloid beta(42) concentrations (p < 0.001 vs controls and p < 0.05 vs Alzheimer disease) in cerebral amyloid angiopathy patients. The combination of amyloid beta(42) and total tau discriminated cerebral amyloid angiopathy from controls, with an area under the receiver operator curve of 0.98. Our data are consistent with neuropathological evidence that amyloid beta(40) as well as amyloid beta(42) protein are selectively trapped in the cerebral vasculature from interstitial fluid drainage pathways that otherwise transport amyloid beta proteins toward the cerebrospinal fluid.

Topics: Aged; Alzheimer Disease; Amyloid beta-Peptides; Area Under Curve; Biomarkers; Cerebral Amyloid Angiopathy; Diagnosis, Differential; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Mutation; Peptide Fragments; Phosphorylation; ROC Curve; tau Proteins

New pre-clinical trials in AD mouse models may help to develop novel immunogen-adjuvant configurations with the potential to avoid the adverse responses that occurred during the clinical trials with AN-1792 vaccine formulation. Recently, we have pursued an alternative immunization strategy that replaces QS21 the Th1 type adjuvant used in the AN-1792 clinical trial with a molecular adjuvant, mannan that can promote a Th2-polarized immune response through interactions with mannose-binding and CD35/CD21 receptors of the innate immune system. Previously we established that immunization of wild-type mice with mannan-Abeta28 conjugate promoted Th2-mediated humoral and cellular immune responses. In the current study, we tested the efficacy of this vaccine configuration in amyloid precursor protein (APP) transgenic mice (Tg2576).. Mannan was purified, activated and chemically conjugated to Abeta28 peptide. Humoral immune responses induced by the immunization of mice with mannan-Abeta28 conjugate were analyzed using a standard ELISA. Abeta42 and Abeta40 amyloid burden, cerebral amyloid angiopathy (CAA), astrocytosis, and microgliosis in the brain of immunized and control mice were detected using immunohistochemistry. Additionally, cored plaques and cerebral vascular microhemorrhages in the brains of vaccinated mice were detected by standard histochemistry.. Immunizations with low doses of mannan-Abeta28 induced potent and long-lasting anti-Abeta humoral responses in Tg2576 mice. Even 11 months after the last injection, the immunized mice were still producing low levels of anti-Abeta antibodies, predominantly of the IgG1 isotype, indicative of a Th2 immune response. Vaccination with mannan-Abeta28 prevented Abeta plaque deposition, but unexpectedly increased the level of microhemorrhages in the brains of aged immunized mice compared to two groups of control animals of the same age either injected with molecular adjuvant fused with an irrelevant antigen, BSA (mannan-BSA) or non-immunized mice. Of note, mice immunized with mannan-Abeta28 showed a trend toward elevated levels of CAA in the neocortex and in the leptomeninges compared to that in mice of both control groups.. Mannan conjugated to Abeta28 provided sufficient adjuvant activity to induce potent anti-Abeta antibodies in APP transgenic mice, which have been shown to be hyporesponsive to immunization with Abeta self-antigen. However, in old Tg2576 mice there were increased levels of cerebral microhemorrhages in mannan-Abeta28 immunized mice. This effect was likely unrelated to the anti-mannan antibodies induced by the immunoconjugate, because control mice immunized with mannan-BSA also induced antibodies specific to mannan, but did not have increased levels of cerebral microhemorrhages compared with non-immunized mice. Whether these anti-mannan antibodies increased the permeability of the blood brain barrier thus allowing elevated levels of anti-Abeta antibodies entry into cerebral perivascular or brain parenchymal spaces and contributed to the increased incidence of microhemorrhages remains to be investigated in the future studies.

Topics: Adjuvants, Immunologic; Alzheimer Disease; Amyloid beta-Peptides; Animals; Antibody Formation; Blood-Brain Barrier; Cerebral Amyloid Angiopathy; Cerebral Arteries; Disease Models, Animal; Dose-Response Relationship, Drug; Intracranial Hemorrhages; Mannans; Mice; Mice, Transgenic; Peptide Fragments; Plaque, Amyloid; Treatment Outcome; Vaccination; Vaccines, Conjugate

APPDutch transgenic (tg) mice develop cerebral amyloid angiopathy (CAA) that consists mainly of AbetaDutch40, with virtually no parenchymal amyloid plaques. To modulate cerebral amyloidosis, we crossbred APPDutch mice with either BACE1 tg mice to increase total AbetaDutch, or with G384A-mutated PS1 tg mice to elevate the ratio of AbetaDutch42 to AbetaDutch40. We analyzed all mice at 22 months of age. Compared to APPDutch mice, double-tg APPDutch/BACE1 mice revealed increased CAA mainly due to extensive vascular amyloid accumulation in the thalamus. In addition, they developed parenchymal amyloid in cortex and subiculum. In contrast, APPDutch/G384A-PS1 mice showed extensive, predominantly parenchymal amyloid throughout the entire brain, interestingly, even in the thalamus. The amyloid, composed largely of AbetaDutch42, was different compared to that in APPDutch/BACE1 mice which was composed mainly of AbetaDutch40. In summary, these mouse models reveal a broad variety and region-specificity of parenchymal versus vascular cerebral amyloid. This is partially explained by the absolute amount of neuronally produced AbetaDutch42 and AbetaDutch40 and ratio between the two. We conclude that the absolute levels of Abeta in combination with the ratio of Abeta42 to Abeta40 play a key role in determining the cerebral compartment and brain region in which Abeta is deposited.

Topics: Alanine; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloid Precursor Protein Secretases; Animals; Aspartic Acid Endopeptidases; Brain; Cerebral Amyloid Angiopathy; Disease Models, Animal; Glycine; Humans; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mutation; Peptide Fragments; Presenilin-1

Topics: Alzheimer Disease; Amyloid beta-Peptides; Biomarkers; Brain; Causality; Cerebral Amyloid Angiopathy; Cerebral Arteries; Cerebrovascular Disorders; Humans; Microcirculation; Nerve Fibers, Myelinated; Peptide Fragments; Predictive Value of Tests

Microvascular brain injury, typically measured by extent of white matter hyperintensity (WMH) on MRI, is an important contributor to cognitive impairment in the elderly. Recent studies suggest a role for circulating beta-amyloid peptide in microvascular dysfunction and white matter disease.. The authors performed a cross-sectional study of clinical, biochemical, and genetic factors associated with WMH in 54 subjects with Alzheimer disease (AD) or mild cognitive impairment (AD/MCI) and an independent group of 42 subjects with cerebral amyloid angiopathy (CAA). Extent of WMH was determined by computer-assisted volumetric measurement normalized to intracranial size (nWMH). Biochemical measurements included plasma concentrations of the 40- and 42-amino acid species of beta-amyloid (Abeta40 and Abeta42) detected by specific enzyme-linked immunosorbent assays.. Plasma Abeta40 concentrations were associated with nWMH in both groups (correlation coefficient = 0.48 in AD/MCI, 0.42 in CAA, p < or = 0.005). Plasma Abeta40 remained independently associated with nWMH after adjustment for potential confounders among age, hypertension, diabetes, homocysteine, creatinine, folate, vitamin B12, and APOE genotype. The presence of lacunar infarctions was also associated with increased Abeta40 in both groups. nWMH was greater in CAA (19.8 cm3) than AD (11.1 cm3) or MCI (10.0 cm3; p < 0.05 for both comparisons).. Plasma beta-amyloid 40 concentration is independently associated with extent of white matter hyperintensity in subjects with Alzheimer disease, mild cognitive impairment, or cerebral amyloid angiopathy. If confirmed in longitudinal studies, these data would suggest circulating beta-amyloid peptide as a novel biomarker or risk factor for microvascular damage in these common diseases of the elderly.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Biomarkers; Brain; Brain Infarction; Cerebral Amyloid Angiopathy; Cerebral Arteries; Cerebrovascular Disorders; Cognition Disorders; Cross-Sectional Studies; Female; Humans; Male; Microcirculation; Middle Aged; Nerve Fibers, Myelinated; Peptide Fragments; Predictive Value of Tests; Prognosis

Alzheimer's disease (AD) is characterized by pathological lesions, such as senile plaques (SPs) and cerebral amyloid angiopathy (CAA), both predominantly consisting of a proteolytic cleavage product of the amyloid-beta precursor protein (APP), the amyloid-beta peptide (Abeta). CAA is also the major pathological lesion in hereditary cerebral hemorrhage with amyloidosis of the Dutch type (HCHWA-D), caused by a mutation in the gene coding for the Abeta peptide. Several members of the small heat shock protein (sHsp) family, such as alphaB-crystallin, Hsp27, Hsp20 and HspB2, are associated with the pathological lesions of AD, and the direct interaction between sHsps and Abeta has been demonstrated in vitro. HspB8, also named Hsp22 of H11, is a recently discovered member of the sHsp family, which has chaperone activity and is observed in neuronal tissue. Furthermore, HspB8 affects protein aggregation, which has been shown by its ability to prevent formation of mutant huntingtin aggregates. The aim of this study was to investigate whether HspB8 is associated with the pathological lesions of AD and HCHWA-D and whether there are effects of HspB8 on Abeta aggregation and Abeta-mediated cytotoxicity. We observed the expression of HspB8 in classic SPs in AD brains. In addition, HspB8 was found in CAA in HCHWA-D brains, but not in AD brains. Direct interaction of HspB8 with Abeta(1-42), Abeta(1-40) and Abeta(1-40) with the Dutch mutation was demonstrated by surface plasmon resonance. Furthermore, co-incubation of HspB8 with D-Abeta(1-40) resulted in the complete inhibition of D-Abeta(1-40)-mediated death of cerebrovascular cells, likely mediated by a reduction in both the beta-sheet formation of D-Abeta(1-40) and its accumulation at the cell surface. In contrast, however, with Abeta(1-42), HspB8 neither affected beta-sheet formation nor Abeta-mediated cell death. We conclude that HspB8 might play an important role in regulating Abeta aggregation and, therefore, the development of classic SPs in AD and CAA in HCHWA-D.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Amyloidosis; Brain; Cell Death; Cerebral Amyloid Angiopathy; Cerebral Hemorrhage; Heat-Shock Proteins; Humans; Molecular Chaperones; Mutation; Peptide Fragments; Plaque, Amyloid; Protein Serine-Threonine Kinases; Surface Plasmon Resonance; Tissue Distribution

Small heat shock proteins Hsp20 and HspB2/B3 co-localize with Abeta deposition in senile plaques and cerebral amyloid angiopathy in Alzheimer's disease brains, respectively. It was the aim of our study to investigate if these and other sHsps bind to wild-type Abeta1-42 or the more toxic Abeta1-40 carrying the 'Dutch' mutation (22Glu-->Gln) (D-Abeta1-40), affect Abeta aggregation and thereby influence Abeta cytotoxicity. Binding affinity between sHsps and Abeta was investigated by surface plasmon resonance. Abeta aggregation was studied by using circular dichroism spectroscopy and electron microscopy. Furthermore, we used cultured cerebrovascular cells to investigate the effects of sHsps on Abeta-mediated cytotoxicity. Hsp20, Hsp27 and alphaB-crystallin, but not HspB2/B3, bound to Abeta (both D-Abeta1-40 and Abeta1-42) and reduced or completely inhibited aggregation of D-Abeta1-40 into mature fibrils but did not affect Abeta1-42 aggregation. Furthermore, these sHsps were effective inhibitors of the cerebrovascular toxicity of Abeta (both D-Abeta1-40 and Abeta1-42) in vitro. Binding affinity of the sHsps to D-Abeta1-40 correlated to the degree of inhibition of Abeta-mediated cytotoxicity and the potential to reduce Abeta beta-sheet and fibril formation. With Abeta1-42, a similar correlation between binding affinity and cytotoxicity was observed, but not with its aggregation state. In conclusion, sHsps may regulate Abeta aggregation and serve as antagonists of the biological action of Abeta, but the extent of their interaction depends on the type of sHsp and Abeta peptide.

Topics: alpha-Crystallins; Alzheimer Disease; Amyloid beta-Peptides; Cells, Cultured; Cerebral Amyloid Angiopathy; Cerebral Arteries; Heat-Shock Proteins; HSP20 Heat-Shock Proteins; HSP27 Heat-Shock Proteins; Humans; Molecular Chaperones; Mutation; Neoplasm Proteins; Neuroprotective Agents; Peptide Fragments; Plaque, Amyloid; Protein Binding

Alzheimer's disease (AD) is characterized by the aggregation and deposition of the normally soluble amyloid-beta (Abeta) peptide in the extracellular spaces of the brain as parenchymal plaques and in the walls of cerebral vessels as cerebral amyloid angiopathy (CAA). CAA is a common cause of brain hemorrhage and is found in most patients with AD. As in AD, the epsilon4 allele of the apolipoprotein E (apoE) gene (APOE) is a risk factor for CAA. To determine the effect of human apoE on CAA in vivo, we bred human APOE3 and APOE4 "knock-in" mice to a transgenic mouse model (Tg2576) that develops amyloid plaques as well as CAA. The expression of both human apoE isoforms resulted in a delay in Abeta deposition of several months relative to murine apoE. Tg2576 mice expressing the more fibrillogenic murine apoE develop parenchymal amyloid plaques and CAA by 9 months of age. At 15 months of age, the expression of human apoE4 led to substantial CAA with very few parenchymal plaques, whereas the expression of human apoE3 resulted in almost no CAA or parenchymal plaques. Additionally, young apoE4-expressing mice had an elevated ratio of Abeta 40:42 in brain extracellular pools and a lower 40:42 ratio in CSF, suggesting that apoE4 results in altered clearance and transport of Abeta species within different brain compartments. These findings demonstrate that, once Abeta fibrillogenesis occurs, apoE4 favors the formation of CAA over parenchymal plaques and suggest that molecules or treatments that increase the ratio of Abeta 40:42 may favor the formation of CAA versus parenchymal plaques.

Topics: Alkenes; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Apolipoprotein E3; Apolipoprotein E4; Apolipoproteins E; Benzoates; Blood Vessels; Cerebral Amyloid Angiopathy; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation; Humans; Mice; Mice, Inbred C57BL; Mice, Transgenic; Peptide Fragments; Plaque, Amyloid

Considerable circumstantial evidence suggests that Abeta42 is the initiating molecule in Alzheimer's disease (AD) pathogenesis. However, the absolute requirement for Abeta42 for amyloid deposition has never been demonstrated in vivo. We have addressed this by developing transgenic models that express Abeta1-40 or Abeta1-42 in the absence of human amyloid beta protein precursor (APP) overexpression. Mice expressing high levels of Abeta1-40 do not develop overt amyloid pathology. In contrast, mice expressing lower levels of Abeta1-42 accumulate insoluble Abeta1-42 and develop compact amyloid plaques, congophilic amyloid angiopathy (CAA), and diffuse Abeta deposits. When mice expressing Abeta1-42 are crossed with mutant APP (Tg2576) mice, there is also a massive increase in amyloid deposition. These data establish that Abeta1-42 is essential for amyloid deposition in the parenchyma and also in vessels.

Topics: Age Factors; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Benzothiazoles; Blood Vessels; Blotting, Northern; Blotting, Western; Brain; Cerebral Amyloid Angiopathy; Enzyme-Linked Immunosorbent Assay; Female; Glial Fibrillary Acidic Protein; Humans; Immunohistochemistry; Immunoprecipitation; In Situ Hybridization; Male; Mass Spectrometry; Mice; Mice, Transgenic; Microscopy, Electron, Transmission; Mutation; Peptide Fragments; Pia Mater; Plaque, Amyloid; Thiazoles

Recent studies reported both positive [Thal et al. (2003) J Neuropathol Exp Neurol 62:1287-1301] and negative [Tian et al. (2003) Neurosci Lett 352:137-140] correlations between cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD) pathology. We have recently shown high correlations between neuritic AD pathology and amyloid beta peptide (Abeta) deposits in the capillary/pericapillary compartment (CapCAA) with only low correlations to general CAA (non-capillary). We have now studied the relationship between CapCAA and AD pathology with respect to the distribution of Abeta40 and 42 in the frontal cortex of 100 human postmortem brains from both male and female, demented and non-demented patients (mean age +/- SD 84.3 +/- 9.3 years). Using polyclonal antibodies to Abeta40 and 42, capillary and plaques positivity were assessed semiquantiatively on a four-point scale. Abeta42 deposits in capillaries correlated highly with both Abeta42 deposits in plaques and morphological AD criteria (CERAD, Braak stages, and NIA-Reagan-Institute criteria), while only a low correlation with CAA was observed. Abeta40 deposits in capillaries differed morphologically from Abeta42 ones: they were limited to capillary walls, were significantly less frequent in both capillaries and plaques compared to Abeta42 ( P < 0.01), and showed a low correlation with morphological AD criteria ( P < 0.05) and general CAA ( P < 0.01). By contrast, Abeta42 deposits were seen in the glia limitans rather than in capillary walls themselves, and showed high correlation with morphological AD criteria ( P < 0.01). These data indicate that CapCAA is characterized by Abeta42 deposits in pericapillary spaces or in the glia limitans. A low correlation between CAA and CapCAA, but high correlations between morphological AD criteria and CapCAA suggest different pathomechanisms for both types of CAA, and a close relation between CapCAA and AD pathology (both neuritic and plaque type). These data support the concept of a neuronal origin of Abeta via drainage from interstitial fluid from the central nervous system along basement membranes to capillaries.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Brain; Capillaries; Cerebral Amyloid Angiopathy; Female; Humans; Immunohistochemistry; Male; Middle Aged; Neurofibrillary Tangles; Neuropsychological Tests; Peptide Fragments; Plaque, Amyloid; Postmortem Changes; Statistics as Topic; Statistics, Nonparametric

Although the amyloid beta protein (Abeta) E693Q mutation enhances Abeta fibrillization in vitro and cerebral amyloid angiopathy (CAA) in vivo, brain parenchymal Abeta deposition and tau pathology in hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D) are limited. To evaluate whether clearance of Abeta by glial cells may play a role in this regard, this immunohistochemical study of frontal cortex of 14 HCHWA-D autopsy brains was performed using double staining with glial markers and end-specific antibodies to Abetax-42 (Abeta42) and Abetax-40 (Abeta40). Tau pathology was also assessed. Numerous microglia and/or astrocytes carrying cytoplasmic Abeta42(+)40(-) granules were scattered among non-fibrillar (Congo red-negative) Abeta deposits, i.e., clouds, fine diffuse plaques, and Abeta42(+)40(-) dense diffuse plaques. On the other hand, activated microglia and reactive astrocytes associated with fibrillar (Congo red-positive) Abeta deposition, i.e., Abeta42(+)40(+) dense diffuse plaques and CAA invading the parenchyma, were virtually devoid of Abeta granules. Tau pathology was scant and most frequently associated with CAA. These results suggest that relatively non-fibrillar parenchymal Abeta deposits may be liable to glial clearance. Abeta sequestration by glial cells may be a factor limiting the levels of neurotoxic soluble Abeta oligomers in HCHWA-D brain.

Topics: Aged; Aged, 80 and over; Amyloid beta-Peptides; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Cerebral Amyloid Angiopathy; Cerebral Amyloid Angiopathy, Familial; Cerebral Hemorrhage; Female; Frontal Lobe; Glial Fibrillary Acidic Protein; Glucose Transporter Type 5; Humans; Immunohistochemistry; Male; Middle Aged; Monosaccharide Transport Proteins; Neuroglia; Peptide Fragments; Plaque, Amyloid; Postmortem Changes; tau Proteins

Cerebral amyloid angiopathy (CAA) is a major pathological feature of Alzheimer's disease and related disorders. Human cerebrovascular smooth muscle (HCSM) cells, which are intimately associated with CAA, have been used as an in vitro model system to investigate pathologic interactions with amyloid beta protein (A beta). Previously we have shown that pathogenic forms of A beta induce several pathologic responses in HCSM cells including fibril assembly at the cell surface, increase in the levels of A beta precursor, and apoptotic cell death. Here we show that pathogenic A beta stimulates the expression and activation of matrix metalloproteinase-2 (MMP-2). Furthermore, we demonstrate that the increase in MMP-2 activation is largely caused by increased expression of membrane type-1 (MT1)-MMP expression, the primary MMP-2 activator. Finally, treatment with MMP-2 inhibitors resulted in increased HCSM cell viability in the presence of pathogenic A beta. Our findings suggest that increased expression and activation of MMP-2 may contribute to HCSM cell death in response to pathogenic A beta. In addition, these activities may also contribute to loss of vessel wall integrity in CAA resulting in hemorrhagic stroke. Therefore, further understanding into the role of MMPs in HCSM cell degeneration may facilitate designing therapeutic strategies to treat CAA found in AD and related disorders.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Cell Survival; Cells, Cultured; Cerebral Amyloid Angiopathy; Cerebrovascular Circulation; Enzyme Activation; Enzyme Inhibitors; Humans; Matrix Metalloproteinase 2; Muscle, Smooth, Vascular; Mutation; Peptide Fragments; RNA, Messenger

Cerebral amyloid angiopathy (CAA) is a common cause of brain hemorrhage in the elderly. It is found in the majority of patients with Alzheimer's disease (AD). The most common form of CAA is characterized by the deposition of the amyloid-beta (Abeta) peptide in the walls of cerebral vessels, and this deposition can lead to hemorrhage and infarction. As in AD, the epsilon4 allele of apolipoprotein E (APOE) is a risk factor for CAA. To determine the effect of apoE on CAA and associated hemorrhage in vivo, we used two amyloid precursor protein (APP) transgenic mouse models that develop age-dependent Abeta deposition: PDAPP and APPsw mice. We found that both models developed an age-dependent increase in CAA and associated microhemorrhage, with the APPsw model having an earlier and more severe phenotype; however, when APPsw and PDAPP mice were bred onto an Apoe-/- background, no CAA was detected through 24 months of age, and there was little to no evidence of microhemorrhage. Biochemical analysis of isolated cerebral vessels from both PDAPP and APPsw mice with CAA revealed that, as in human CAA, the ratio of Abeta 40:42 was elevated relative to brain parenchyma. In contrast, the ratio of Abeta 40:42 from cerebral vessels isolated from old PDAPP, Apoe-/- mice was extremely low. These findings demonstrate that murine apoE markedly promotes the formation of CAA and associated vessel damage and that the effect of apoE combined with the level of Abeta40 or the ratio of Abeta 40:42 facilitates this process.

Topics: Age Factors; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Apolipoproteins E; Cerebral Amyloid Angiopathy; Cerebral Cortex; Cerebral Hemorrhage; Mice; Mice, Knockout; Mice, Transgenic; Peptide Fragments

Vascular dysfunction and inflammatory processes may be early events in the pathology of Alzheimer's disease (AD). Even though amyloid beta-peptides (Abeta) play a prominent role in the initiation and progression of cellular dysfunction in AD, the precise in vivo actions of various Abeta-peptides has not been established. The cerebrovascular actions of the major Abeta-peptides (1-40) and (1-42) in live animals were investigated using an open cranial window technique. We show here that the Abeta-peptides cause vascular lesions, especially in the arterioles. In one set of experiments, leukocytes and platelets were tagged with Rhodamine 6G, soluble Abeta(1-40) infused intravenously for 2 minutes, and the vasculature video recorded for 90 minutes. In a second set of experiments, soluble Abeta(1-40) infusion was followed 30 minutes later by an infusion of soluble Abeta(1-42) and the vasculature recorded for 90 minutes. Fluorescent and transmission electron microscopic examinations demonstrated the following cerebrovascular action of Abeta-peptides: endothelial cell damage, leukocyte adhesion, platelet activation, thrombus formation, impeded blood flow, and smooth muscle cell damage. The vascular disruption observed were similar to those observed in the brains of some AD patients and may represent the initial phase of a vascular inflammatory response associated with cerebral amyloid angiopathy. The combination of Abeta(1-40) and (1-42) produced significantly more vascular disruption than Abeta(1-40) alone. Oral administration of conjugated estrogens in ovariectomized female rats protected them from the deleterious actions of Abeta-peptides. The reported protective effect of estrogen against AD may be mediated in part through prevention of cerebrovascular Abeta toxicity.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Blood-Brain Barrier; Cell Adhesion; Cerebral Amyloid Angiopathy; Dementia, Vascular; Endothelium, Vascular; Estrogens, Conjugated (USP); Female; Humans; Intracranial Embolism; Leukocytes; Microscopy, Electron; Peptide Fragments; Platelet Activation; Rats

Squirrel monkey is a valuable model to study pathogenesis of cerebrovascular amyloid angiopathy (CAA). Previous studies suggested that circulating amyloid-beta40 peptide (Abeta40) crosses the blood-brain barrier (BBB) and may therefore enhance cerebrovascular amyloidosis in aged squirrel monkeys. In the present study, we used single photon emission computed tomography (SPECT) to determine elimination of 123I-Abeta40 and 99mTc-DTPA, an extracellular marker, from the brain in squirrel monkeys at different age. Following intracerebral microinfusions, the time-activity brain clearance curves indicated bi-exponential removal of 123I-Abeta40 with an initial rapid washout (1.1 < or = t 1/2 < or = 2.7 h). This, plus the observed appearance of 123I-radioactivity in plasma suggest significant brain-to-blood transport. In contrast, 99mTc-DTPA was removed slowly by brain interstitial fluid bulk flow (monoexponential decay with 6.8 < or = t 1/2 < or = 16.8 h). A comparison of three middle aged (11-16 years old) vs. two old (22 yrs old) monkeys was consistent with an age-related decline in the BBB capacity to remove 123I-Abeta from the brain. This correlated with an age-dependent increase in A1beta40/42 cerebrovascular immunoreactivity and amyloid deposition. Thus, vascular clearance plays an important role in reducing Abeta levels in the squirrel monkey brain and impaired Abeta40 elimination across the BBB may contribute to the development of CAA.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Cerebral Amyloid Angiopathy; Disease Models, Animal; Peptide Fragments; Saimiri; Tomography, Emission-Computed, Single-Photon

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Antibodies, Monoclonal; Capillary Permeability; Cerebral Amyloid Angiopathy; Cerebral Hemorrhage; Humans; Immunization, Passive; Immunoglobulin G; Male; Mice; Mice, Transgenic; Neocortex; Peptide Fragments

1. We studied cerebrovascular sequestration and blood-brain barrier (BBB) permeability to [125I]- or [123I]-labeled amyloid-beta peptides (A beta) in aged rhesus and aged squirrel monkey, the nonhuman primate models of cerebral beta-amyloidosis and cerebrovascular amyloid angiopathy (CAA), respectively. 2. In aged rhesus, the half-time of elimination of [125I]A beta 1-40, t1/2e, was faster by 1.34 h, the systemic clearance, Clss, increased by 4.21 ml/min/kg and the mean residence time of intact peptide in the circulation shortened by 2 h. 3. Cerebrovascular sequestration of [125I]A beta 1-40 was significant in aged squirrel monkey (20.8 ml/g x 10(2)), but undetectable in the rhesus. 4. The permeability surface area product, PS, for [14C]inulin was low in both species (0.11-0.18 ml/g/s x 10(6)) indicating an intact barrier. 5. The BBB permeability to A beta 1-40 was 34.8- and 13.7-fold higher than for [14C]inulin in aged squirrel and rhesus, respectively, suggesting a specialized A beta transport across the BBB. 6. The single photon computed emission tomography studies confirmed a saturable [123I]A beta 1-40 transport at the BBB in primates (Km = 40 nM). 7. Brain autoradiographic analysis of [125I]A beta 1-42 or [125I]A beta 1-40 after intracarotid infusions of radiotracers confirmed co-localization of the signal with A beta-immunoreactive plaques in rhesus monkeys. 8. Metabolism of [125I]A beta 1-40 in brain and plasma was slower in aged squirrel compared to aged rhesus, by 2.9- and 2.6-fold, respectively. 9. Thus, transport of circulating A beta across the BBB contributes to brain parenchymal accumulation of amyloid in aged nonhuman primates. Negligible capillary binding, rapid systemic and brain degradation, and accelerated body elimination of blood-borne A beta, may prevent the development of CAA in rhesus in contrast to squirrel monkeys.

Topics: Adolescent; Aging; Alzheimer Disease; Amyloid beta-Peptides; Amyloidosis; Animals; Blood-Brain Barrier; Cerebral Amyloid Angiopathy; Cerebrovascular Circulation; Disease Models, Animal; Humans; Immunohistochemistry; Macaca mulatta; Microcirculation; Peptide Fragments; Saimiri; Tomography, Emission-Computed, Single-Photon

The presenilins (PSs) are components of large molecular complexes that contain beta-catenin and function as gamma-secretase. We report here a striking correlation between amyloid angiopathy and the location of mutation in PS-1 linked Alzheimer's disease. The amount of amyloid beta protein, Abeta(42(43)), but not Abeta(40,) deposited in the frontal cortex of the brain is increased in 54 cases of early-onset familial Alzheimer's disease, encompassing 25 mutations in the presenilin-1 (PS-1) gene, compared to sporadic Alzheimer's disease. The amount of Abeta(40) in PS-1 Alzheimer's disease varied according to the copy number of epsilon4 alleles of the Apolipoprotein E gene. Although the amounts of Abeta(40) and Abeta(42(43)) deposited did not correlate with the genetic location of the mutation in a strict linear sense, the histological profile did so vary. Cases with mutations between codon 1 and 200 showed, in frontal cortex, many diffuse plaques, few cored plaques, and mild or moderate amyloid angiopathy. Cases with mutations occurring after codon 200 also showed many diffuse plaques, but the number and size of cored plaques were increased (even when epsilon4 allele was not present) and these were often clustered around blood vessels severely affected by amyloid angiopathy. Similarly, diverging histological profiles, mainly according to the degree of amyloid angiopathy, were seen in the cerebellum. Mutations in the PS-1 gene may therefore alter the topology of the PS-1 protein so as to favor Abeta formation and deposition, generally, but also to facilitate amyloid angiopathy particularly in cases in which the mutation lies beyond codon 200. Finally we report that the amount of Abeta(42(43)) deposited in the brain correlated with the amount of this produced in culture by cells bearing the equivalent mutations.

Topics: Adult; Alzheimer Disease; Amyloid beta-Peptides; Animals; Apolipoproteins E; Cerebellum; Cerebral Amyloid Angiopathy; COS Cells; Female; Frontal Lobe; Genetic Variation; Genotype; Humans; Male; Membrane Proteins; Middle Aged; Mutation; Peptide Fragments; Presenilin-1

Despite the documented association between apolipoprotein E genotype and cerebral amyloid angiopathy (CAA), a substantial proportion of CAA-related hemorrhages occur in patients without known risks for this disorder. Two other factors implicated in the pathogenesis of CAA are the amyloid-beta peptide (preferentially deposited in vessels as a 40-amino acid species) and the multifunctional cytokine transforming growth factor-beta 1 (a specific promoter of vascular amyloid deposition in transgenic models). We measured plasma concentrations of these factors in a series of 25 patients diagnosed with probable or definite CAA-related hemorrhage and compared them with 21 patients with hemorrhage due to probable hypertensive vasculopathy and 42 elderly control subjects without hemorrhage. We found no differences among the groups in concentrations of the 40- or 42-amino acid species of beta-amyloid or either the active or latent form of transforming growth factor-beta 1. While the data do not exclude important roles for these molecules as risks for CAA, they indicate that plasma measurements are not useful in its diagnosis.

Topics: Aged; Amyloid beta-Peptides; Biomarkers; Cerebral Amyloid Angiopathy; Cerebral Hemorrhage; Female; Humans; Hypertension; Male; Peptide Fragments; Reference Values; Risk Factors; Transforming Growth Factor beta

The apolipoprotein Eepsilon4 allele (ApoEepsilon4) is associated with a selective increase in deposition of the 40-amino acid form of the beta-amyloid peptide (Abeta40) in endstage Alzheimer's disease. To determine how apoE genotype affects the early events in beta-amyloid pathogenesis, we analyzed the medial temporal lobes of 244 elderly persons who were not clinically demented using antibodies selective for the C termini of Abeta40 and Abeta42. We found that: (1) the number of both Abeta42- and Abeta40-positive senile plaques increase with age; (2) Abeta42 appears at younger ages, and in more amyloid deposits, than does Abeta40 in all ApoE groups; (3) when compared at similar ages, older persons with ApoEepsilon4 are more likely to have Abeta42- and Abeta40-immunoreactive deposits than are persons without ApoEepsilon4; (4) Abeta40-containing plaques arise at least a decade later than do Abeta42 plaques, and are seldom found in the medial temporal lobe of older persons lacking ApoEepsilon4; and (5) in the absence of overt Alzheimer's disease, cerebral amyloid angiopathy is rare in the elderly, but in our sample was significantly augmented in ApoEepsilon4 homozygotes. We conclude that ApoEepsilon4 hastens the onset of Abeta42 deposition in the senescent brain, which in turn fosters the earlier evolution of fibrillar, Abeta40-positive plaques, thereby increasing the risk of Alzheimer's disease.

Topics: Age Factors; Age of Onset; Aged; Aged, 80 and over; Aging; Alzheimer Disease; Amyloid beta-Peptides; Apolipoprotein E4; Apolipoproteins E; Cerebral Amyloid Angiopathy; Female; Genotype; Humans; Male; Middle Aged; Neurofibrillary Tangles; Neurons; Peptide Fragments; Plaque, Amyloid; Sex Factors; Temporal Lobe

The binding mechanism of Congo red (CR) to Alzheimer's disease (AD) amyloid fibrils (A beta) in terms of binding affinity and number of sites was quantitated from absorption spectroscopy (at 200-700 nm) by measuring the concentration of CR bound (CR-B) to AD A beta assemblies as a function of CR concentration and pH in 80% ethanol. The rationale for the use of this high concentration of ethanol derives from its use in histological screens for amyloid in tissue sections. Moreover, free CR can be separated from bound CR by filtration in ethanolic but not aqueous medium. The A beta analogs studied here included: (1) peptides having different lengths: A beta1-40, A beta11-28, A beta13-28, A beta19-28, A beta11-25; (2) wildtype, control sequences of A beta1-40 and sequences having different natural amino acid substitutions: primate Pr1-40, rodent Ro1-40, hereditary cerebral haemorrhage with amyloidosis, Dutch type (HCHWA-D) Du1-40, primate reverse sequence Pr40-1; and (3) A beta11-25 sequences having different substitutions: H13D, H14D, and D23K. Negative-staining showed that A beta1-40 fibrils in buffer were indistinguishable from those in buffered ethanolic medium. For all amyloid analogs except A beta19-28, which has no histidine residues and showed no CR binding over the entire pH range 4.0-9.5, CR-B decreased as a function of increasing pH. The decrease was steepest at about pH 5 and became zero above pH 7. For analogs having the same number of histidines, CR-B fell on the same binding curve, indicating that histidine residues are the likely binding sites for CR in this medium. The pH titration of the binding was parameterized by the stoichiometry of dye to the sites, the number of histidines per molecule, the binding dissociation constant Kd, and the apparent proton dissociation constant pK of the histidine; and the calculated pH-titration curves were found to fit the observed ones. For the peptides having 1-3 histidines the average pK was 5.0-5.5, which was similar to the expected pK of histidine in low dielectric medium (80% ethanol), and the Kd's were 2.8-5.9 microM. That histidine residues underlie CR binding in A beta amyloid is consistent with previous findings that A beta peptides sediment as fibrillar assemblies at pH-3-7 and bind Congo red over the same pH range in aqueous medium. Further, the conformation near the binding motif His13-His14-Gln15-Lys16 in A beta assemblies is not greatly altered in 80% ethanol.

Topics: Amino Acid Sequence; Amino Acid Substitution; Amyloid beta-Peptides; Animals; Binding Sites; Cerebral Amyloid Angiopathy; Chemical Phenomena; Chemistry, Physical; Coloring Agents; Congo Red; Filtration; Histidine; Humans; Hydrogen-Ion Concentration; Kinetics; Microscopy, Electron; Molecular Sequence Data; Negative Staining; Peptide Fragments; Primates; Protein Binding; Protons; Rodentia; Species Specificity; Static Electricity; Structure-Activity Relationship

We have characterized amyloid beta peptide (Abeta) concentration, Abeta deposition, paired helical filament formation, cerebrovascular amyloid angiopathy, apolipoprotein E (ApoE) allotype, and synaptophysin concentration in entorhinal cortex and superior frontal gyrus of normal elderly control (ND) patients, Alzheimer's disease (AD) patients, and high pathology control (HPC) patients who meet pathological criteria for AD but show no synapse loss or overt antemortem symptoms of dementia. The measures of Abeta deposition, Abeta-immunoreactive plaques with and without cores, thioflavin histofluorescent plaques, and concentrations of insoluble Abeta, failed to distinguish HPC from AD patients and were poor correlates of synaptic change. By contrast, concentrations of soluble Abeta clearly distinguished HPC from AD patients and were a strong inverse correlate of synapse loss. Further investigation revealed that Abeta40, whether in soluble or insoluble form, was a particularly useful measure for classifying ND, HPC, and AD patients compared with Abeta42. Abeta40 is known to be elevated in cerebrovascular amyloid deposits, and Abeta40 (but not Abeta42) levels, cerebrovascular amyloid angiopathy, and ApoE4 allele frequency were all highly correlated with each other. Although paired helical filaments in the form of neurofibrillary tangles or a penumbra of neurites surrounding amyloid cores also distinguished HPC from AD patients, they were less robust predictors of synapse change compared with soluble Abeta, particularly soluble Abeta40. Previous experiments attempting to relate Abeta deposition to the neurodegeneration that underlies AD dementia may have failed because they assayed the classical, visible forms of the molecule, insoluble neuropil plaques, rather than the soluble, unseen forms of the molecule.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Apolipoproteins E; Brain; Cerebral Amyloid Angiopathy; Diagnosis, Differential; Female; Gene Frequency; Humans; Immunohistochemistry; Male; Neurofibrillary Tangles; Peptide Fragments; Plaque, Amyloid; Predictive Value of Tests; Synapses

Senescent squirrel monkey is a valuable model to study pathogenesis of cerebrovascular amyloid angiopathy (CAA). Cerebrovascular sequestration and blood-brain barrier (BBB) permeability to 121I-amyloid beta(1-40) synthetic peptide (sA beta(1-40)) were studied in adult versus aged squirrel monkey 1 h after a single intravenous injection. In aged monkey, the half-time of elimination of sA beta(1-40), t(1/2)e, was prolonged by 0.6 h, the systemic clearance, ClSS, was reduced from 1.8 to 1.1 ml/min/kg, and the mean residence time of intact peptide in the circulation was increased by 1 h (45%). In adult monkey, cerebrovascular sequestration of intact sA beta(1-40) was significant, and the BBB permeability was 18.6-fold higher than for inulin. In aged monkey, the sequestration of intact sA beta(1-40) by cortical and leptomeningeal microvessels and the BBB permeability were increased by 5.9, 1.8-, and 2.1-fold, respectively, in the presence of an unchanged barrier to inulin. In brain parenchyma of aged animals, 76.1% of circulating sA beta(1-40) remained intact versus 45.7% in adult. We conclude that multiple age-related systemic effects, i.e., reduced body elimination and systemic clearance of sA beta(1-40), and reduced peripheral metabolism, may act in concert with BBB mechanisms, i.e., increased transendothelial transport and microvascular accumulation of blood-borne sA beta(1-40), and reduced brain metabolism to enhance the development of CAA.

Topics: Aging; Alzheimer Disease; Amyloid beta-Peptides; Animals; Blood-Brain Barrier; Capillary Permeability; Cerebral Amyloid Angiopathy; Cerebrovascular Circulation; Chemical Precipitation; Peptide Fragments; Saimiri; Tissue Distribution; Trichloroacetic Acid

The beta-amyloid (A beta 1-40) peptide has previously been shown to enhance phenylephrine contraction of aortic rings in vitro. We have employed a novel observation, that A beta peptides enhance endothelin-1 (ET-1) contraction, to examine the relationship between vasoactivity and potential amyloidogenicity of A beta peptides, the role played by free radicals and calcium in the vasoactive mechanism, and the requirement of an intact endothelial layer for enhancement of vasoactivity. Rings of rat aortae were constricted with ET-1 before and after addition of amyloid peptide and/or other compounds, and a comparison was made between post- and pre-treatment contractions. In this system, vessel constriction is consistently dramatically enhanced by A beta 1-40, is enhanced less so by A beta 1-42, and is not enhanced by A beta 25-35. The endothelium is not required for A beta vasoactivity, and calcium channel blockers have a greater effect than antioxidants in blocking enhancement of vasoconstriction by A beta peptides. In contrast to A beta-induced cytotoxicity, A beta-induced vasoactivity is immediate, occurs in response to low doses of freshly solubilized peptide, and appears to be inversely related to the amyloidogenic potential of the A beta peptides. We conclude that the mechanism of A beta vasoactivity is distinct from that of A beta cytotoxicity. Although free radicals appear to modulate the vasoactive effects, the lack of requirement for endothelium suggests that loss of the free radical balance (between NO and O2-) may be a secondary influence on A beta enhancement of vasoconstriction. These effects of A beta on isolated vessels, and reported effects of A beta in cells of the vasculature, suggest that A beta-induced disruption of vascular tone may be a factor in the pathogenesis of cerebral amyloid angiopathy and Alzheimer's disease. Although the mechanism of enhanced vasoconstriction is unknown, it is reasonable to propose that in vivo contact of A beta peptides with small cerebral vessels may increase their tendency to constrict and oppose their tendency to relax. The subclinical ischemia resulting from this would be expected to up-regulate beta APP production in and around the vasculature with further increase in A beta formation and deposition. The disruptive and degenerative effects of such a cycle would lead to the complete destruction of cerebral vessels and consequently neuronal degeneration in the affected areas.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Aorta; Calcimycin; Calcium Channel Blockers; Calcium Channels; Calcium Channels, L-Type; Cerebral Amyloid Angiopathy; Drug Synergism; Endothelin-1; Endothelium, Vascular; Ionophores; Male; Peptide Fragments; Rats; Rats, Sprague-Dawley; Vasoconstriction; Vasoconstrictor Agents; Verapamil

Cerebrovascular deposits of amyloid (cerebral amyloid angiopathy, or CAA) are generally asymptomatic, but in advanced cases, they can lead to vessel rupture and hemorrhage. The process of progression in CAA was studied by comparison of postmortem brains with asymptomatic ("mild") CAA to brains with the form of the disease associated with hemorrhage ("severe CAA"). Cortical and meningeal vessels were immunostained for beta-amyloid and examined by confocal microscopy and by systematic quantitative sampling. We focused on 2 quantitative parameters: the proportion of vessels affected by amyloid (a measure of amyloid seeding of vessels) and the amount of amyloid per affected vessel (a measure of growth of existing lesions). Surprisingly, there was no difference between the proportion of affected cortical vessels in mild and severe CAA (0.29 vs 0.32, p = 0.65), but rather an increase in the area of the 40 amino acid form of beta-amyloid per affected cortical vessel (198.5 +/- 38.7 vs 455.8 +/- 100.9 microm2/vessel, p < 0.007). Increasing doses (from 0 to 1 to 2 copies) of the apolipoprotein E epsilon4 allele were also associated with greater amyloid per vessel without change in the proportion of affected vessels within each class of CAA severity. These findings suggest that progression from asymptomatic to advanced CAA reflects progressive accumulation of amyloid in vessels previously seeded with amyloid, and that this process is selectively enhanced by apolipoprotein E epsilon4.

Topics: Aging; Amyloid beta-Peptides; Apolipoproteins E; Blood Vessels; Cerebral Amyloid Angiopathy; Cerebral Cortex; Disease Progression; Fluorescent Antibody Technique, Indirect; Humans; Meninges; Microscopy, Confocal; Peptide Fragments; Polymerase Chain Reaction

To clarify the immunohistochemical features of canine senile plaques (SPs) and cerebral amyloid angiopathy (CAA), the distribution of the amyloid beta protein (A beta) subtypes A beta 40 and A beta 42(43), A beta precursor protein (APP), and glial cell reaction were examined in the brains of seven aged dogs (12-18 years). A beta 42(43) was found to be deposited in all types of SPs, whereas A beta 40 was deposited only in mature (classical and primitive) plaques. CAA, which was located along parenchymal and meningeal arterioles and capillaries, consisted of both subtypes of A beta. APP was exhibited in normal and degenerative neurons and swollen neurites of mature plaques. It was, therefore, considered that A beta 42(43) in diffuse plaques might be derived from APP in neurons, while A beta 40 and A beta 42(43) in mature plaques might be generated from APP in swollen neurites in the plaque. In contrast to the case in humans, in whom deposition of A beta 40 and A beta 42(43) in the mature plaques is predominantly associated with microglial reaction, in dogs we found that it was closely associated with astroglial reaction. The present findings showed characteristics of canine SPs which are different from those of humans.

Topics: Aging; Amyloid beta-Peptides; Animals; Brain; Cerebral Amyloid Angiopathy; Dogs; Histocytochemistry; Immunohistochemistry; Muscle, Smooth, Vascular; Neurons; Peptide Fragments; Plaque, Amyloid

In Alzheimer's disease (AD), the main histological lesion is a proteinaceous deposit, the senile plaque, which is mainly composed of a peptide called A beta. The aggregation process is thought to occur through enhanced concentration of A beta 40 or increased production of the more readily aggregating 42 amino acid-long A beta 42 species.. Specificity of the antibodies was assessed by dot blot, Western blot, ELISA, and immunoprecipitation procedures on synthetic and endogenous A beta produced by secreted HK293 cells. A beta and p3 production by wild-type and mutated presenilin 1-expressing cells transiently transfected with beta APP751 was monitored after metabolic labeling and immunoprecipitation procedures. Immunohistochemical analysis was performed on brains of sporadic and typical cerebrovascular amyloid angiopathy (CAA) cases.. Dot and Western blot analyses indicate that IgG-purified fractions of antisera recognize native and denaturated A beta s. FCA3340 and FCA 3542 display full specificity for A beta 40 and A beta 42, respectively. Antibodies immunoprecipitate their respective synthetic A beta species but also A beta s and their related p3 counterparts endogenously secreted by transfected human kidney 293 cells. This allowed us to show that mutations on presenilin 1 triggered similar increased ratios of A beta 42 and its p 342 counterpart over total A beta and p3. ELISA assays allow detection of about 25-50 pg/ml of A beta s and remain linear up to 750 to 1500 pg/ml without any cross-reactivity. FCA18 and FCA3542 label diffuse and mature plaques of a sporadic AD case whereas FCA3340 only reveals the mature lesions and particularly labels their central dense core. In a CAA case, FCA18 and FCA3340 reveal leptomeningeal and cortical arterioles whereas FCA3542 only faintly labels such structures.. Polyclonal antibodies exclusively recognizing A beta 40 (FCA 3340) or A beta 42 (FCA3542) were obtained. These demonstrated that FAD-linked presenilins similarly affect both p342 and A beta 42, suggesting that these mutations misroute the beta APP to a compartment where gamma-secretase, but not alpha-secretase, cleavages are modified. Overall, these antibodies should prove useful for fundamental and diagnostic approaches, as suggested by their usefulness for biochemical, cell biological, and immunohistochemical techniques.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Antibody Specificity; Cerebral Amyloid Angiopathy; Enzyme-Linked Immunosorbent Assay; Humans; Immunoblotting; Membrane Proteins; Peptide Fragments; Precipitin Tests; Presenilin-1

Aggregation and deposition of the 40-42-residue amyloid beta-protein (Abeta) are early and necessary neuropathological events in Alzheimer's disease. An understanding of the molecular interactions that trigger these events is important for therapeutic strategies aimed at blocking Abeta plaque formation at the earliest stages. Heparan sulfate proteoglycans may play a fundamental role since they are invariably associated with Abeta and other amyloid deposits at all stages. However, the nature of the Abeta-heparan sulfate proteoglycan binding has been difficult to elucidate because of the strong tendency of Abeta to self-aggregate. Affinity co-electrophoresis can measure the binding of proteoglycans or glycosaminoglycans to proteins without altering the physical state of the protein during the assay. We used affinity co-electrophoresis to study the interaction between Abeta and the glycosaminoglycan heparin and found that the aggregation state of Abeta governs its heparin-binding properties: heparin binds to fibrillar but not nonfibrillar Abeta. The amyloid binding dye, Congo red, inhibited the interaction in a specific and dose-dependent manner. The "Dutch" mutant AbetaE22Q peptide formed fibrils more readily than wild type Abeta and it also attained a heparin-binding state more readily, but, once formed, mutant and wild type fibrils bound heparin with similar affinities. The heparin-binding ability of aggregated AbetaE22Q was reversible with incubation in a solvent that promotes alpha-helical conformation, further suggesting that conformation of the peptide is important. Studies with another human amyloidogenic protein, amylin, suggested that its heparin-binding properties were also dependent on aggregation state. These results demonstrate the dependence of the Abeta-heparin interaction on the conformation and aggregation state of Abeta rather than primary sequence alone, and suggest methods of interfering with this association.

Topics: Amino Acid Sequence; Amyloid; Amyloid beta-Peptides; Animals; Cerebral Amyloid Angiopathy; Coloring Agents; Congo Red; Electrophoresis; Heparin; Humans; Islet Amyloid Polypeptide; Kinetics; Molecular Sequence Data; Peptide Fragments; Protein Binding; Rats

Cerebral amyloid angiopathy (CAA) is known to be associated with intracerebral hemorrhage in the elderly. In this study we demonstrated that, among 101 cases with intracerebral hemorrhages found in 1000 consecutive autopsied cases (average age, 82.9 years) at a geriatric hospital, CAA accounted for 10.9% of them (31.0% of lobar and 14.3% of cerebellar hemorrhages). Immunohistochemically, the cerebrovascular amyloid was positive for beta/A4 peptide, and less intensely for cystatin C. The CAA-related hemorrhages were characteristically located near the cortical surface and ruptured into the subarachnoid space. No mutation of the amyloid precursor protein gene or the cystatin C gene was detected in these cases. From the observation of 500 serial sections containing amyloid-laden vessels of a patient with CAA-related hemorrhage, it was suggested that the hemorrhage occurred at microaneurysms with fibrinoid necrosis, which were found in small arteries in the cerebral cortex. The spatial distribution of CAA was closely associated with that of subpial beta/A4 peptide deposits in the brain, raising the possibility that the cerebrovascular amyloid originates from the brain parenchyma. Finally, the severity of CAA did not seem to be influenced by the inheritance of the epsilon 4 allele of the apolipoprotein E gene, which is known as a risk factor for dementia of the Alzheimer type.

Topics: Aged; Aged, 80 and over; Alleles; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Aneurysm, Ruptured; Apolipoproteins E; Cerebellar Diseases; Cerebral Amyloid Angiopathy; Cerebral Arteries; Cerebral Cortex; Cerebral Hemorrhage; Cerebrospinal Fluid Proteins; Cystatin C; Cystatins; Cysteine Proteinase Inhibitors; Fibrin; Humans; Immunohistochemistry; Intracranial Aneurysm; Middle Aged; Mutation; Necrosis; Peptide Fragments; Pia Mater; Risk Factors; Subarachnoid Space

We developed two highly sensitive enzyme immunoassays for beta-protein with different specificities. One is specific for beta 1-40, while the other is equally sensitive to beta 1-38, beta 1-39, beta 1-40, and beta 1-42. With the enzyme immunoassays we investigated whether the soluble fraction from brain tissue contains beta 1-40 or other species of beta-protein. Aged control and Alzheimer's diseased brains showed highly variable values of beta 1-40, which was found to be the major beta species in their extracts. High tissue content of soluble beta 1-40 was not correlated to the abundance of senile plaques but was invariably associated with cerebral amyloid angiopathy. Thus, the tissue level of soluble beta 1-40 should be useful for the quantification of cerebral amyloid angiopathy.

Topics: Adult; Aged; Aged, 80 and over; Amyloid beta-Peptides; Brain; Cerebral Amyloid Angiopathy; Female; Humans; Immunoenzyme Techniques; Immunohistochemistry; Male; Middle Aged; Peptide Fragments; Tissue Extracts