Cerebral amyloid angiopathy: an overview

Amyloid accumulation in cases of suspected comorbid cerebral amyloid angiopathy and isolated cortical venous thrombosis

BACKGROUND AND AIM

The differentiation of isolated cortical venous thrombosis (ICVT) from cerebral amyloid angiopathy (CAA) can be difficult because both diseases share similar neurological symptoms and imaging findings. N-methyl-11C-2-(4'-methylaminophenyl)-6-hydroxybenzo-thiazole (11C-PiB) positron emission tomography (PET) functions as a diagnostic modality for CAA by detecting amyloid deposition. The present prospective study evaluated amyloid deposition using 11C-PiB-PET in consecutive patients with suspected ICVT.

METHOD

This study was a prospective observational study. Patients who attended or were hospitalized between May 2019 and March 2020 were included in the analysis. Consecutive patients who met the criteria for suspicion of ICVT were enrolled in the study, and the clinical course, symptoms, imaging findings (including magnetic resonance imaging), and the 11C-PiB-PET findings of each case were analyzed.

RESULTS

The study cohort included four patients (64-82 years of age, all women). In one younger patient, 11C-PiB-PET afforded no findings suggestive of CAA, whereas the remaining three patients exhibited 11C-PiB-PET findings suggestive of CAA.

CONCLUSION

Although 11C-PiB-PET would be a reasonable modality for distinguishing ICVT from CAA, especially in younger patients, it might be difficult to differentiate ICVT from CAA in elderly patients because of the potential deposition of amyloid.

CLINICAL TRIAL REGISTRATION

URL: https://www.umin.ac.jp/ctr/ Unique identifier: UMIN 000037101.

When Atrial Fibrillation Meets Cerebral Amyloid Angiopathy: Current Evidence and Strategies

Non-valvular atrial fibrillation (AF) and cerebral amyloid angiopathy (CAA) are two common diseases in elderly populations. Despite the effectiveness of oral anticoagulant therapy in cardioembolic stroke prevention, intracranial hemorrhage represents the most serious complication of these therapies. Cerebral amyloid angiopathy is one of the main risk factors for spontaneous intracranial bleeding, and this risk is highly increased by age and concomitant antithrombotic therapies. Cerebral amyloid angiopathy can be silent for years and then manifest with clinical features simulating TIA (TIA-mimics) or stroke in AF patients, pushing clinicians to rapidly start VKAs or DOACs, thus increasing the risk of intracranial bleeding if the diagnosis of CAA was unknown. Because the cerebral amyloid angiopathy is easily diagnosed with non-contrast MRI, suspecting the disease can avoid catastrophic complications. In this review, we will provide physicians managing anticoagulant therapies with key tips to familiarize themselves with cerebral amyloid angiopathy, with a focus on the possible clinical presentations and on the diagnostic criteria.

Dissecting Polygenic Etiology of Ischemic Stroke in the Era of Precision Medicine

Ischemic stroke (IS), the leading cause of death and disability worldwide, is caused by many modifiable and non-modifiable risk factors. This complex disease is also known for its multiple etiologies with moderate heritability. Polygenic risk scores (PRSs), which have been used to establish a common genetic basis for IS, may contribute to IS risk stratification for disease/outcome prediction and personalized management. Statistical modeling and machine learning algorithms have contributed significantly to this field. For instance, multiple algorithms have been successfully applied to PRS construction and integration of genetic and non-genetic features for outcome prediction to aid in risk stratification for personalized management and prevention measures. PRS derived from variants with effect size estimated based on the summary statistics of a specific subtype shows a stronger association with the matched subtype. The disruption of the extracellular matrix and amyloidosis account for the pathogenesis of cerebral small vessel disease (CSVD). Pathway-specific PRS analyses confirm known and identify novel etiologies related to IS. Some of these specific PRSs (e.g., derived from endothelial cell apoptosis pathway) individually contribute to post-IS mortality and, together with clinical risk factors, better predict post-IS mortality. In this review, we summarize the genetic basis of IS, emphasizing the application of methodologies and algorithms used to construct PRSs and integrate genetics into risk models.

Arterial vasodilation drives convective fluid flow in the brain: a poroelastic model

The movement of fluid into, through, and out of the brain plays an important role in clearing metabolic waste. However, there is controversy regarding the mechanisms driving fluid movement in the fluid-filled paravascular spaces (PVS), and whether the movement of metabolic waste in the brain extracellular space (ECS) is primarily driven by diffusion or convection. The dilation of penetrating arterioles in the brain in response to increases in neural activity (neurovascular coupling) is an attractive candidate for driving fluid circulation, as it drives deformation of the brain tissue and of the PVS around arteries, resulting in fluid movement. We simulated the effects of vasodilation on fluid movement into and out of the brain ECS using a novel poroelastic model of brain tissue. We found that arteriolar dilations could drive convective flow through the ECS radially outward from the arteriole, and that this flow is sensitive to the dynamics of the dilation. Simulations of sleep-like conditions, with larger vasodilations and increased extracellular volume in the brain showed enhanced movement of fluid from the PVS into the ECS. Our simulations suggest that both sensory-evoked and sleep-related arteriolar dilations can drive convective flow of cerebrospinal fluid not just in the PVS, but also into the ECS through the PVS around arterioles.

Cerebrospinal Fluid Biomarkers in Cerebral Amyloid Angiopathy: New Data and Quantitative Meta-Analysis

Background

To evaluate the diagnostic accuracy of cerebrospinal fluid (CSF) biomarkers in patients with probable cerebral amyloid angiopathy (CAA) according to the modified Boston criteria in a retrospective multicentric cohort.

Methods

Beta-amyloid 1-40 (Aβ40), beta-amyloid 1-42 (Aβ42), total tau (t-tau), and phosphorylated tau 181 (p-tau¹⁸¹) were measured in 31 patients with probable CAA, 28 patients with Alzheimer’s disease (AD), and 30 controls. Receiver-operating characteristics (ROC) analyses were performed for the measured parameters as well as the Aβ42/40 ratio to estimate diagnostic parameters. A meta-analysis of all amenable published studies was conducted.

Results

In our data Aβ42/40 (AUC 0.88) discriminated best between CAA and controls while Aβ40 did not perform well (AUC 0.63). Differentiating between CAA and AD, p-tau¹⁸¹ (AUC 0.75) discriminated best in this study while Aβ40 (AUC 0.58) and Aβ42 (AUC 0.54) provided no discrimination. In the meta-analysis, Aβ42/40 (AUC 0.90) showed the best discrimination between CAA and controls followed by t-tau (AUC 0.79), Aβ40 (AUC 0.76), and p-tau¹⁸¹ (AUC 0.71). P-tau¹⁸¹ (AUC 0.76), Aβ40 (AUC 0.73), and t-tau (AUC 0.71) differentiated comparably between AD and CAA while Aβ42 (AUC 0.54) did not. In agreement with studies examining AD biomarkers, Aβ42/40 discriminated excellently between AD and controls (AUC 0.92–0.96) in this study as well as the meta-analysis.

Conclusion

The analyzed parameters differentiate between controls and CAA with clinically useful accuracy (AUC > ∼0.85) but not between CAA and AD. Since there is a neuropathological, clinical and diagnostic continuum between CAA and AD, other diagnostic markers, e.g., novel CSF biomarkers or other parameters might be more successful.

Noninvasive Antemortem Detection of Retinal Prions by a Fluorescent Tracer

BACKGROUND

Neurodegenerative diseases are widespread yet challenging to diagnose and stage antemortem. As an extension of the central nervous system, the eye harbors retina ganglion cells vulnerable to degeneration, and visual symptoms are often an early manifestation of neurodegenerative disease.

OBJECTIVE

Here we test whether prion protein aggregates could be detected in the eyes of live mice using an amyloid-binding fluorescent probe and high-resolution retinal microscopy.

METHODS

We performed retinal imaging on an experimental mouse model of prion-associated cerebral amyloid angiopathy in a longitudinal study. An amyloid-binding fluorophore was intravenously administered, and retinal imaging was performed at timepoints corresponding to early, mid-, and terminal prion disease. Retinal amyloid deposits were quantified and compared to the amyloid load in the brain.

RESULTS

We report that by early prion disease (50% timepoint), discrete fluorescent foci appeared adjacent to the optic disc. By later timepoints, the fluorescent foci surrounded the optic disc and tracked along retinal vasculature.

CONCLUSION

The progression of perivascular amyloid can be directly monitored in the eye by live imaging, illustrating the utility of this technology for diagnosing and monitoring the progression of cerebral amyloid angiopathy.

Vascular endothelial growth factor associated dissimilar cerebrovascular phenotypes in two different mouse models of Alzheimer's Disease

Vascular perturbations and cerebral hypometabolism are emerging as important components of Alzheimer's disease (AD). While various in vivo imaging modalities have been designed to detect changes of cerebral perfusion and metabolism in AD patients and animal models, study results were often heterogenous with respect to imaging techniques and animal models. We therefore evaluated cerebral perfusion and glucose metabolism of two popular transgenic AD mouse strains, TgCRND8 and 5xFAD, at 7 and 12 months-of-age under identical conditions and analyzed possible molecular mechanisms underlying heterogeneous cerebrovascular phenotypes. Results revealed disparate findings in these two strains, displaying important aspects of AD progression. TgCRND8 mice showed significantly decreased cerebral blood flow and glucose metabolism with unchanged cerebral blood volume (CBV) at 12 months-of-age whereas 5xFAD mice showed unaltered glucose metabolism with significant increase in CBV at 12 months-of-age and a biphasic pattern of early hypoperfusion followed by a rebound to normal cerebral blood flow in late disease. Finally, immunoblotting assays suggested that VEGF dependent vascular tone change may restore normoperfusion and increase CBV in 5xFAD.

Selective extension of cerebral vascular calcification in an autopsy case of Fahr's syndrome associated with asymptomatic hypoparathyroidism

We report an autopsy case of Fahr's syndrome in an 85-year-old woman associated with asymptomatic hypoparathyroidism. The patient was diagnosed as having brain calcification at 65 years of age. She developed mild dementia at 75, parkinsonism at 76, and severe dementia at 82. Computed tomography revealed extensive, symmetric intracranial calcification, involving both sides of the basal ganglia and cerebellar dentate nuclei, and severe cerebral atrophy that developed afterwards. A neuropathological examination revealed intracranial calcification, particularly in the wall of the arterioles and capillaries having numerous calcium deposits. Severe vascular calcification and severe neuronal loss without α-synuclein accumulation were found in the substantia nigra. There were high-level neuropathological changes indicative of Alzheimer's disease. Although the colocalization of calcium and amyloid-β deposits in the same arterial wall was rare, both of them were located in a similar layer of the arterial wall. The vascular calcification in the basal ganglia spread continuously through the corona radiata into the selective cerebral areas along the medullary arteries, but did not involve the corpus callosum or insular region. Stone formation was observed at the corona radiata adjacent to the superolateral angles of the lateral ventricles. We hypothesized that there would be a stereotypical extension pattern of vascular calcification related to the arrangement of penetrating arteries in Fahr's syndrome.

Clinical and radiological evolution of cerebral amyloid angiopathy-related inflammation in the context of anti-PD-1 immunotherapy

Immune-related adverse events (irAEs) are a frequent complication of immunotherapy, but neurological irAEs are rare and varied. Here, we present a case of cerebral amyloid angiopathy-related inflammation (CAA-ri) attributable to nivolumab monotherapy, which has not been previously reported. The context of immunotherapy and availability of serial imaging also provide unique insights into the pathogenesis and evolution of CAA-ri. Routine surveillance neuroimaging in a patient with metastatic melanoma, in remission after treatment with nivolumab, demonstrated progressive microhaemorrhages and associated oedema, suspicious for CAA-ri. These changes progressed despite cessation of nivolumab. The patient was initially asymptomatic, but later developed an acute confusional state, warranting brain biopsy, which confirmed the diagnosis of CAA-ri. Treatment with methylprednisolone resulted in resolution of the oedema, and a marked decrease in the subsequent accumulation of microhaemorrhages. The temporal evolution prior to symptom development and subsequently related to treatment suggests that inflammation may be an important component of the pathogenesis of CAA-ri, rather than simply a secondary response. Given that immunotherapy is in its relative infancy, it is important to consider rare irAEs in patients exhibiting unusual imaging findings.

Risk of intracranial haemorrhage and ischaemic stroke after convexity subarachnoid haemorrhage in cerebral amyloid angiopathy: international individual patient data pooled analysis

Objective

To investigate the frequency, time-course and predictors of intracerebral haemorrhage (ICH), recurrent convexity subarachnoid haemorrhage (cSAH), and ischemic stroke after cSAH associated with cerebral amyloid angiopathy (CAA).

Methods

We performed a systematic review and international individual patient-data pooled analysis in patients with cSAH associated with probable or possible CAA diagnosed on baseline MRI using the modified Boston criteria. We used Cox proportional hazards models with a frailty term to account for between-cohort differences.

Results

We included 190 patients (mean age 74.5 years; 45.3% female) from 13 centers with 385 patient-years of follow-up (median 1.4 years). The risks of each outcome (per patient-year) were: ICH 13.2% (95% CI 9.9–17.4); recurrent cSAH 11.1% (95% CI 7.9–15.2); combined ICH, cSAH, or both 21.4% (95% CI 16.7–26.9), ischemic stroke 5.1% (95% CI 3.1–8) and death 8.3% (95% CI 5.6–11.8). In multivariable models, there is evidence that patients with probable CAA (compared to possible CAA) had a higher risk of ICH (HR 8.45, 95% CI 1.13–75.5, p = 0.02) and cSAH (HR 3.66, 95% CI 0.84–15.9, p = 0.08) but not ischemic stroke (HR 0.56, 95% CI 0.17–1.82, p = 0.33) or mortality (HR 0.54, 95% CI 0.16–1.78, p = 0.31).

Conclusions

Patients with cSAH associated with probable or possible CAA have high risk of future ICH and recurrent cSAH. Convexity SAH associated with probable (vs possible) CAA is associated with increased risk of ICH, and cSAH but not ischemic stroke. Our data provide precise risk estimates for key vascular events after cSAH associated with CAA which can inform management decisions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10706-3.

Cerebral amyloid angiopathy related inflammation: A little known but not to be underestimated disease

Cerebral amyloid angiopathy related inflammation (CAA-ri) is a rare encephalopathy resulting from perivascular inflammation after β-βamyloid (A) deposition in cerebral vessels leading to progressive dementia, focal neurological signs, seizures and intracerebral hemorrhages. This condition is characterized on magnetic resonance imaging (MRI) by patchy or confluent T2/fluid attenuation inversion recovery (FLAIR) hyperintensities in the cortex and subcortical white matter located mainly in the same areas of pre-existing multiple microhemorrhages. In this report of 2 cases of “probable” CAA-ri women aged 71 and 68, we propose a review on the pathophysiological, clinical, radiological, therapeutic and prognostic aspects of this little-known and poor outcome condition.

Even though an apparently favorable initial evolution after steroid and/or immunosuppressive treatment, CAA-ri course is unpredictable and often associated with low survival rates. We suggest the importance of timely and proper clinico-radiological evaluation in suspected CAA-ri cases, in order to start an appropriate treatment even without the brain biopsy.

Case of recurrent cerebral haemorrhage in an older adult man who uses dimethylsulfoxide (DMSO) for self-management of low mood and pain

We present the case of a man in his 70s who had suffered two separate frontal lobe haemorrhages in the context of using dimethylsulfoxide (DMSO) to manage his low mood. The known pathophysiology of DMSO renders it a likely causative agent of the recurrent intracerebral haemorrhages. This case highlights the need for clinicians to robustly enquire about a patient's use of over-the-counter medications, of non-prescribed supplements and other substances, as part of the history. In addition, the case highlights the potential for highly debilitating adverse effects from using DMSO.

Evaluating the use of gradient echo imaging for the detection of cerebral microbleeds in acute stroke cases: A retrospective data analysis in a UK stroke unit

INTRODUCTION

Imaging in stroke, allows its classification into ischaemic stroke (IS) or intracranial haemorrhagic stroke (ICH), ensuring time-sensitive treatment to be administered. Imaging can also allow detection of cerebral microbleeds (CMBs), which may further determine pharmacological intervention in acute stroke. True gradient echo (T2∗GRE) or susceptibility weighted imaging (SWI) have high sensitivity for the detection of CMBs. These two sequences are included in the national guidelines; however, the implementation of these guidelines can vary depending on local interpretation and scanner capabilities.

AIM

To explore the use and application of blood sensitive MRI sequences in a specialist UK stroke unit for the detection of CMBs, to improve local practice.

METHODS

A retrospective data analysis of the native database, spanning a 6-month period, was used. The data of 281 acute stroke patients with an MRI were reviewed and analysed. The MRI sequences applied, and the final diagnosis were noted for each case.

RESULTS

Of the 281 acute stroke patients with MRI, 259 (92.1%) had an IS, 16 (5.68%) an ICH and 6 (2.14%) had both. Overall, 13 (4.63%) had a CMB diagnosis. All of these 13 patients had a true T2∗GRE sequence. CMBs were not detected in the absence of a T2∗GRE sequence.

CONCLUSION

T2∗GRE imaging is essential for detecting CMBs. When omitted, CMB incidence can be considerably lower than that suggested in the literature. Missing CMB diagnoses in stroke patients may result in suboptimal treatment pathways, compromising the patients' standard of care.

IMPLICATIONS FOR PRACTICE

When SWI is not available, it is imperative to always include a true T2∗GRE sequence to detect microbleeds in suspected acute stroke cases.

Transthyretin-stabilising mutation T119M is not associated with protection against vascular disease or death in the UK Biobank

Background: Destabilised transthyretin (TTR) can result in the progressive, fatal disease transthyretin-mediated (ATTR) amyloidosis. A stabilising TTR mutation, T119M, is the basis for a therapeutic strategy to reduce destabilised TTR. Recently, T119M was associated with extended lifespan and lower risk of cerebrovascular disease in a Danish cohort. We aimed to determine whether this finding could be replicated in the UK Biobank.Methods: TTR T119M carriers were identified in the UK Biobank, a large prospective cohort of ∼500,000 individuals. Association between T119M genotype and inpatient diagnosis of vascular disease, cardiovascular disease, cerebrovascular disease, and mortality was analysed.Results: Frequency of T119M within the white UK Biobank population (n = 337,148) was 0.4%. Logistic regression comparing T119M carriers to non-carriers found no association between T119M and vascular disease (odds ratio [OR] = 1.08; p = .27), cardiovascular disease (OR = 1.08; p = .31), cerebrovascular disease (OR = 1.1; p = .42), or death (OR = 1.2; p = .06). Cox proportional hazards regression showed similar results (hazard ratio >1, p>.05). Age at death and vascular disease diagnosis were similar between T119M carriers and non-carriers (p = .12 and p = .38, respectively).Conclusions: There was no association between the TTR T119M genotype and risk of vascular disease or death in a large prospective cohort study, indicating that TTR tetramer stabilisation through T119M is not protective in this setting.

Interhemispheric distribution of amyloid and small vessel disease burden in cerebral amyloid angiopathy-related intracerebral hemorrhage

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) is a devastating presentation of cerebral amyloid angiopathy (CAA), but the mechanisms leading from vascular amyloid deposition to ICH are not well known. Whether amyloid burden and magnetic resonance imaging (MRI) markers of small vessel disease (SVD) are increased in the ICH-affected hemisphere compared to the ICH-free hemisphere in patients with a symptomatic CAA-related ICH was investigated.

METHODS

Eighteen patients with CAA-related ICH and 18 controls with deep ICH who underwent brain MRI and amyloid positron emission tomography using ¹⁸ F-florbetapir were prospectively enrolled. In each hemisphere amyloid uptake using the standardized uptake value ratio and the burden of MRI markers of SVD including cerebral microbleeds, chronic ICH, cortical superficial siderosis, white matter hyperintensities and lacunes were evaluated. Interhemispheric comparisons were assessed by non-parametric matched-pair tests within each patient group.

RESULTS

Amyloid burden was similarly distributed across the brain hemispheres in patients with CAA-related ICH (standardized uptake value ratio 1.11 vs. 1.12; P = 0.74). Cortical superficial siderosis tended to be more common in the ICH-affected hemisphere compared to the ICH-free hemisphere (61% vs. 33%; P = 0.063). Other MRI markers of SVD did not differ across brain hemispheres. In controls with deep ICH, no interhemispheric difference was observed either for amyloid burden or for MRI markers of SVD.

CONCLUSIONS

Brain hemorrhage does not appear to be directly linked to amyloid burden in patients with CAA-related ICH. These findings provide new insights into the mechanisms leading to hemorrhage in CAA.

Rapid Cognitive Decline and Recurrent Falls in a 71 Year-Old Man Due to Cerebral Amyloidangiopathy-Related Inflammation (CAA-RI)

Cognitive decline and falls in the elderly are common and are often accepted as natural and inevitable by relatives and health care professionals, but frequently there are specific and treatable diseases that should be revealed. In our case, cerebral amyloid angiopathy-related inflammation (CAA-RI) was causative for neuro-psychiatric symptoms and worsening of gait in a 71 year-old man with recurrent falls and decline of gait and cognition. Cerebral amyloidangiopathy (CAA) is an important cause of cerebrovascular disorders in the elderly, characterized by leukoencephalopathy combined with lobar or small cortical hemorrhage due to amyloid deposition in cortical and leptomeningeal vessels. In several conditions, amyloid deposition can provoke inflammation or edema that lead to -normally reversible- encephalopathy. CAA-RI is then characterized by subacute neurobehavioral symptoms, headache, seizures or stroke-like signs. The first therapeutic option after confirming the diagnosis is treatment with glucocorticoids. Despite treatment with prednisolone, our patient could not regain his unrestricted mobility and self-help competence. Our report aims to sharpen awareness for CAA and its inflammatory form (CAA-RI) in healthcare professionals involved in medical care of the elderly and provide a short summary of this disease.

Pericytes in Alzheimer's Disease: Novel Clues to Cerebral Amyloid Angiopathy Pathogenesis

Pericytes in the central nervous system attract growing attention of neurobiologists because of obvious opportunities to use them as target cells in numerous brain diseases. Functional activity of pericytes includes control of integrity of the endothelial cell layer, regeneration of vascular cells, and regulation of microcirculation. Pericytes are well integrated in the so-called neurovascular unit (NVU) serving as a platform for effective communications of neurons, astrocytes, endothelial cells, and pericytes. Contribution of pericytes to the establishment and maintaining the structural and functional integrity of blood-brain barrier is confirmed in numerous experimental and clinical studies. The review covers current understandings on the role of pericytes in molecular pathogenesis of NVU/BBB dysfunction in Alzheimer's disease with the special focus on the development of cerebral amyloid angiopathy, deregulation of cerebral angiogenesis, and progression of BBB breakdown seen in Alzheimer's type neurodegeneration.

Structural and functional analysis of cystatin E reveals enzymologically relevant dimer and amyloid fibril states

Protein activity is often regulated by altering the oligomerization state. One mechanism of multimerization involves domain swapping, wherein proteins exchange parts of their structures and thereby form long-lived dimers or multimers. Domain swapping has been specifically observed in amyloidogenic proteins, for example the cystatin superfamily of cysteine protease inhibitors. Cystatins are twin-headed inhibitors, simultaneously targeting the lysosomal cathepsins and legumain, with important roles in cancer progression and Alzheimer's disease. Although cystatin E is the most potent legumain inhibitor identified so far, nothing is known about its propensity to oligomerize. In this study, we show that conformational destabilization of cystatin E leads to the formation of a domain-swapped dimer with increased conformational stability. This dimer was active as a legumain inhibitor by forming a trimeric complex. By contrast, the binding sites toward papain-like proteases were buried within the cystatin E dimer. We also showed that the dimers could further convert to amyloid fibrils. Unexpectedly, cystatin E amyloid fibrils contained functional protein, which inhibited both legumain and papain-like enzymes. Fibril formation was further regulated by glycosylation. We speculate that cystatin amyloid fibrils might serve as a binding platform to stabilize the pH-sensitive legumain and cathepsins in the extracellular environment, contributing to their physiological and pathological functions.

Cerebrospinal fluid and blood biomarkers for neurodegenerative dementias: An update of the Consensus of the Task Force on Biological Markers in Psychiatry of the World Federation of Societies of Biological Psychiatry

In the 12 years since the publication of the first Consensus Paper of the WFSBP on biomarkers of neurodegenerative dementias, enormous advancement has taken place in the field, and the Task Force takes now the opportunity to extend and update the original paper. New concepts of Alzheimer's disease (AD) and the conceptual interactions between AD and dementia due to AD were developed, resulting in two sets for diagnostic/research criteria. Procedures for pre-analytical sample handling, biobanking, analyses and post-analytical interpretation of the results were intensively studied and optimised. A global quality control project was introduced to evaluate and monitor the inter-centre variability in measurements with the goal of harmonisation of results. Contexts of use and how to approach candidate biomarkers in biological specimens other than cerebrospinal fluid (CSF), e.g. blood, were precisely defined. Important development was achieved in neuroimaging techniques, including studies comparing amyloid-β positron emission tomography results to fluid-based modalities. Similarly, development in research laboratory technologies, such as ultra-sensitive methods, raises our hopes to further improve analytical and diagnostic accuracy of classic and novel candidate biomarkers. Synergistically, advancement in clinical trials of anti-dementia therapies energises and motivates the efforts to find and optimise the most reliable early diagnostic modalities. Finally, the first studies were published addressing the potential of cost-effectiveness of the biomarkers-based diagnosis of neurodegenerative disorders.

Modulation of Amyloid-β1-40 Transport by ApoA1 and ApoJ Across an in vitro Model of the Blood-Brain Barrier

Amyloid-β (Aβ) accumulation in Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA) is likely caused by the impairment of its brain clearance that partly occurs through the blood-brain barrier (BBB). In this context, an in vitro BBB model is a valuable tool for studying the molecular mechanisms that regulate this process. This study assessed brain Aβ elimination across the BBB and its modulation by the natural chaperones Apolipoprotein A1 (ApoA1) and Apolipoprotein J/Clusterin (ApoJ). The model was based on primary cerebral endothelial cells that were cultured on Matrigel-coated Transwells and treated with fluorescently labeled-Aβ1-40 to track its efflux across the BBB, which corresponds to trafficking from the basolateral (brain) to apical (blood) compartments. We observed that the transport of basolateral Aβ1-40 was enhanced when it was complexed to rApoJ, whereas the complex formed with rApoA1 did not influence Aβ1-40 efflux. However, the presence of rApoA1 in the apical compartment was able to mobilize Aβ1-40 from the basolateral side. We also observed that both rApoA1 and rApoJ moderately crossed the monolayer (from blood to brain) through a mechanism involving the LDL receptor-related protein family. In contrast to the increased rApoJ efflux when complexed to Aβ1-40, rApoA1 trafficking was restricted when it was bound to the Aβ peptide. In summary, the present study highlights the role of ApoJ and ApoA1 in the in vitro modulation of Aβ elimination across the BBB.

Pathological examination of cerebral amyloid angiopathy in patients who underwent removal of lobar hemorrhages

Cerebral amyloid angiopathy (CAA) is a degenerative disorder characterized by amyloid-β (Aβ) deposition in the brain microvessels. CAA is also known to contribute not only to cortical microbleeds but also lobar hemorrhages. This retrospective study examined CAA pathologically in patients who underwent direct surgeries for lobar hemorrhage. Thirty-three patients with lobar hemorrhage underwent open surgery with biopsy from 2007 to 2016 in our hospital. Cortical tissues over hematomas obtained surgically were pathologically examined using hematoxylin, eosin stain, and anti-Aβ antibody to diagnose CAA. We also investigated the advanced degree of CAA and clinical features of each patient with lobar hemorrhage. In the 33 patients, 4 yielded specimens that were insufficient to evaluate CAA pathologically. Twenty-four of the remaining 29 patients (82.8%) were pathologically diagnosed with CAA. The majority of CAA-positive patients had moderate or severe CAA based on a grading scale to estimate the advanced degree of CAA. About half of the CAA-positive patients had hypertension, and four took anticoagulant or antiplatelet agents. In five patients who were not pathologically diagnosed with CAA, one had severe liver function disorder, three had uncontrollable hypertension, and one had no obvious risk factor. Our pathological findings suggest that severe CAA with vasculopathic change markedly contributes to lobar hemorrhage. The coexistence of severe CAA and risk factors such as hypertension, anticoagulants or antiplatelets may readily induce lobar hemorrhage.

[Cerebral amyloid angiopathy associated with inflammation]

Cerebral amyloid angiopathy (CAA) associated with inflammation is a rare form of a potentially reversible encephalopathy in a subgroup of patients with CAA. The cerebral amyloid deposition can in isolated cases induce an inflammation predominantly of the cerebral blood vessels and a multifocal edema of the cerebral white matter. The courses can occur as monophasic, relapsing remitting and primarily progressive forms. We present seven cases with different courses of the disease and give an overview of the pathophysiology, clinical aspects and treatment of the disease with reference to the current literature. The cases presented show a very different and often difficult differential diagnostic clinical picture and all showed a significant improvement under steroid medication without signs of recurrence of the disease during the course. The recognition and early consistent treatment of inflammatory forms of CAA with and without direct inflammatory involvement of vessels can be decisive for successful treatment.

Cerebral Amyloid Angiopathy: Diagnosis, Clinical Implications, and Management Strategies in Atrial Fibrillation

With an aging population, clinicians are more frequently encountering patients with atrial fibrillation who are also at risk of intracerebral hemorrhage due to cerebral amyloid angiopathy, the result of β-amyloid deposition in cerebral vessels. Cerebral amyloid angiopathy is common among elderly patients, and is associated with an increased risk of intracerebral bleeding, especially with the use of anticoagulation. Despite this association, this entity is absent in current risk-benefit analysis models, which may result in underestimation of the chance of bleeding in the subset of patients with this disease. Determining the presence and burden of cerebral amyloid angiopathy is particularly important when planning to start or restart anticoagulation after an intracerebral hemorrhage. Given the lack of randomized trial data to guide management strategies, we discuss a heart-brain team approach that includes clinician-patient shared decision making for the use of pharmacologic and nonpharmacologic approaches to diminish stroke risk.

Journey of cystatins from being mere thiol protease inhibitors to at heart of many pathological conditions

Cystatins are thiol proteinase inhibitors (TPI), present ubiquitously in animals, plants and micro-organisms. These are not merely inhibitors rather they are at heart of many pathological conditions ranging from diabetes to renal failure. These are essential for maintenance of protein balance of the cell; once this balance gets disturbed, it may lead to cell death. Thus, cystatins cannot be merely regarded as TPI's as these have been found to play a pivotal role in tumorigenesis and neurodegenerative diseases. Many studies have reported the variation in cystatin level in incidences of different types of cancer; highlighting an important role played by these inhibitors in cancer development and progression. Cystatin C is increasingly replacing creatinine as a biomarker of glomerular filtration rate (GFR) thereby highlighting the importance of this important inhibitor. Some recent studies have also reported the interaction pattern of various anti-cancer drugs with cystatins in a bid to find how these drugs affect this important inhibitors and whether these drugs have any side effect on cystatins. Thus, in this growing disease era it can be said that cystatins are no more just inhibitors blocking the activity of thiol proteases rather they play a pivotal role in variety of pathological conditions.

Amorphous protein aggregates stimulate plasminogen activation, leading to release of cytotoxic fragments that are clients for extracellular chaperones

The misfolding of proteins and their accumulation in extracellular tissue compartments as insoluble amyloid or amorphous protein aggregates are a hallmark feature of many debilitating protein deposition diseases such as Alzheimer's disease, prion diseases, and type II diabetes. The plasminogen activation system is best known as an extracellular fibrinolytic system but was previously reported to also be capable of degrading amyloid fibrils. Here we show that amorphous protein aggregates interact with tissue-type plasminogen activator and plasminogen, via an exposed lysine-dependent mechanism, to efficiently generate plasmin. The insoluble aggregate-bound plasmin is shielded from inhibition by α₂-antiplasmin and degrades amorphous protein aggregates to release smaller, soluble but relatively hydrophobic fragments of protein (plasmin-generated protein fragments (PGPFs)) that are cytotoxic. In vitro, both endothelial and microglial cells bound and internalized PGPFs before trafficking them to lysosomes. Clusterin and α₂-macroglobulin bound to PGPFs to significantly ameliorate their toxicity. On the basis of these findings, we hypothesize that, as part of the in vivo extracellular proteostasis system, the plasminogen activation system may work synergistically with extracellular chaperones to safely clear large and otherwise pathological protein aggregates from the body.

Insights into the mechanism of cystatin C oligomer and amyloid formation and its interaction with β-amyloid

Cystatin C (CysC) is a versatile and ubiquitously-expressed member of the cysteine protease inhibitor family that is present at notably high concentrations in cerebrospinal fluid. Under mildly denaturing conditions, CysC forms inactive domain-swapped dimers. A destabilizing mutation, L68Q, increases the rate of domain-swapping and causes a fatal amyloid disease, hereditary cystatin C amyloid angiopathy. Wild-type (wt) CysC will also aggregate into amyloid fibrils under some conditions. Propagated domain-swapping has been proposed as the mechanism by which CysC fibrils grow. We present evidence that a CysC mutant, V57N, stabilized against domain-swapping, readily forms fibrils, contradicting the propagated domain-swapping hypothesis. Furthermore, in physiological buffer, wt CysC can form oligomers without undergoing domain-swapping. These non-swapped oligomers are identical in secondary structure to CysC monomers and completely retain protease inhibitory activity. However, unlike monomers or dimers, the oligomers bind fluorescent dyes that indicate they have characteristics of pre-amyloid aggregates. Although these oligomers appear to be a pre-amyloid assembly, they are slower than CysC monomers to form fibrils. Fibrillation of CysC therefore likely initiates from the monomer and does not require domain-swapping. The non-swapped oligomers likely represent a dead-end offshoot of the amyloid pathway and must dissociate to monomers prior to rearranging to amyloid fibrils. These prefibrillar CysC oligomers were potent inhibitors of aggregation of the Alzheimer's-related peptide, β-amyloid. This result illustrates an example where heterotypic interactions between pre-amyloid oligomers prevent the homotypic interactions that would lead to mature amyloid fibrils.

Metabolic Syndrome as a Risk Factor for Alzheimer's Disease: Is Aβ a Crucial Factor in Both Pathologies?

SIGNIFICANCE

Recently, chronic degenerative diseases have become one of the main health problems worldwide. That is the case of Alzheimer's disease (AD) and metabolic syndrome (MetS), whose expression can be influenced by different risk factors. Recent Advances: In recent decades, it has been widely described that MetS increases the risk of cognitive impairment and dementia. MetS pathogenesis involves several vascular risk factors such as diabetes, dyslipidemia, hypertension, and insulin resistance (I/R).

CRITICAL ISSUES

Reported evidence shows that vascular risk factors are associated with AD, particularly in the development of protein aggregation, inflammation, oxidative stress, neuronal dysfunction, and disturbances in signaling pathways, with insulin receptor signaling being a common alteration between MetS and AD.

FUTURE DIRECTIONS

Insulin signaling has been involved in tau phosphorylation and amyloid β (Aβ) metabolism. However, it has also been demonstrated that Aβ oligomers can bind to insulin receptors, triggering their internalization, decreasing neuron responsiveness to insulin, and promoting insulin I/R. Thus, it could be argued that Aβ could be a convergent factor in the development of both pathologies. Antioxid. Redox Signal. 26, 542-560.

Multimodality Review of Amyloid-related Diseases of the Central Nervous System

Amyloid-β (Aβ) is ubiquitous in the central nervous system (CNS), but pathologic accumulation of Aβ results in four distinct neurologic disorders that affect middle-aged and elderly adults, with diverse clinical presentations ranging from chronic debilitating dementia to acute life-threatening intracranial hemorrhage. The characteristic imaging patterns of Aβ-related CNS diseases reflect the pathophysiology of Aβ deposition in the CNS. Aβ is recognized as a key component in the neuronal damage that characterizes the pathophysiology of Alzheimer disease, the most common form of dementia. Targeted molecular imaging shows pathologic accumulation of Aβ and tau protein, and fluorine 18 fluorodeoxyglucose positron emission tomography and anatomic imaging allow differentiation of typical patterns of neuronal dysfunction and loss in patients with Alzheimer disease from those seen in patients with other types of dementia. Cerebral amyloid angiopathy (CAA) is an important cause of cognitive impairment and spontaneous intracerebral hemorrhage in the elderly. Hemorrhage and white matter injury seen at imaging reflect vascular damage caused by the accumulation of Aβ in vessel walls. The rare forms of inflammatory angiopathy attributed to Aβ, Aβ-related angiitis and CAA-related inflammation, cause debilitating neurologic symptoms that improve with corticosteroid therapy. Imaging shows marked subcortical and cortical inflammation due to perivascular inflammation, which is incited by vascular Aβ accumulation. In the rarest of the four disorders, cerebral amyloidoma, the macroscopic accumulation of Aβ mimics the imaging appearance of tumors. Knowledge of the imaging patterns and pathophysiology is essential for accurate diagnosis of Aβ-related diseases of the CNS. (©)RSNA, 2016.

Cerebral Amyloid Angiopathy in Stroke Medicine

BACKGROUND

Cerebral amyloid angiopathy (CAA) is a degenerative vasculopathy that is classically associated with lobar intracerebral or sulcal hemorrhage. Its prevalence is estimated at 30% in the seventh decade and 50% in the eighth and ninth decades. In this review, we summarize the risks linked to CAA with respect to the treatment and prevention of stroke.

METHODS

This review is based on pertinent publications retrieved by a selective search employing the terms "amyloid cerebral angiopathy," "stroke," "intra - cerebral bleeding," and "acute stroke therapy."

RESULTS

Among patients given systemic lytic treatment for stroke, those who have microhemorrhages tend to have a higher risk of treatment-associated brain hemorrhage. In a meta-analysis, 70% of patients who sustained a hemorrhage after thrombolytic therapy were found to have CAA, compared to only 22% in a control population. Patients with cerebral hemorrhages have microhemorrhages more commonly than patients with transient ischemic attacks (TIA) or infarcts. This was observed among persons under treatment with vitamin K antagonists (odds ratio, 2.7) or platelet aggregation inhibitors (odds ratio, 1.7). Moreover, the apolipoprotein E2 allele is associated with a higher incidence of intracerebral hemorrhage (ICH) under oral anticoagulation. Strict treatment of arterial hypertension can lower the risk of ICH in persons with probable CAA by 77%. On the other hand, the use of statins after a lobar ICH increases the risk for a clinically manifest recurrent hemorrhage from 14% to 22%.

CONCLUSION

In patients with CAA, arterial hypertension should be tightly controlled. On the other hand, caution should be exercised in prescribing oral anticoagulants or platelet aggregation inhibitors for patients with CAA, or statins for patients who have already sustained a lobar ICH.

Cerebral amyloid angiopathy in a young man with a history of traumatic brain injury: a case report and review of the literature

Cerebral amyloid angiopathy (CAA), a cause of recurrent and multiple lobar hemorrhages, characteristically occurs in persons aged ≥55 years. We report a case of a 32-year-old male who had recurrent hemorrhage in the left multiple lobes, with a history of traumatic brain injury and hematoma evacuation at the age of 1 year. He underwent surgical treatment and was histopathologically diagnosed as having CAA. The literature review yielded six CAA cases, including ours, aged less than 55 years. All were male and four had histories of severe TBI, suggesting that male sex and TBI may be associated with CAA in young persons.

Close Correlation of Monoamine Oxidase Activity with Progress of Alzheimer's Disease in Mice, Observed by in Vivo Two-Photon Imaging

Monoamine oxidases (MAOs) play an important role in Alzheimer's disease (AD) pathology. We report in vivo comonitoring of MAO activity and amyloid-β (Aβ) plaques dependent on the aging of live mice with AD, using a two-photon fluorescence probe. The probe under the catalytic action of MAO produces a dipolar fluorophore that senses Aβ plaques, a general AD biomarker, enabling us to comonitor the enzyme activity and the progress of AD indicated by Aβ plaques. The results show that the progress of AD has a close correlation with MAO activity, which can be categorized into three stages: slow initiation stage up to three months, an aggressive stage, and a saturation stage from nine months. Histological analysis also reveals elevation of MAO activity around Aβ plaques in aged mice. The close correlation between the MAO activity and AD progress observed by in vivo monitoring for the first time prompts us to investigate the enzyme as a potential biomarker of AD.

Comparison of cerebrospinal fluid profiles in Alzheimer's disease with multiple cerebral microbleeds and cerebral amyloid angiopathy-related inflammation

Brain magnetic resonance imaging (MRI) of patients with Alzheimer's disease (AD) sometimes reveals multiple cerebral microbleeds (CMBs) and confluent white matter hyperintensities (WMHs) similar to those observed in cerebral amyloid angiopathy-related inflammation (CAA-I). To determine whether there might be common pathophysiological mechanisms underlying the MRI findings of multiple CMBs and confluent WMHs, we investigated the cerebrospinal fluid (CSF) profiles of 38 AD, five amnestic mild cognitive impairment (MCI), and six CAA-I patients. The AD and MCI patients were divided into groups of patients with (n = 10) or without (n = 33) multiple CMBs (n ≥ 2) on T2*-gradient echo sequences of brain MRI. We compared the CSF profiles of AD and MCI patients with or without multiple CMBs, and CAA-I patients. The brain MRIs of the patients with multiple CMBs revealed severe degrees of WMHs compared with the patients without multiple CMBs. The levels of CSF anti-amyloid β autoantibody and interleukin 8, and CSF/serum albumin ratios and immunoglobulin G indexes, were significantly higher in CAA-I patients than the other groups. However, there were no significant differences in the CSF profiles of patients with or without multiple CMBs. Our study provides evidence for different pathophysiological mechanisms underlying these differential MRI findings in AD and CAA-I.

Pre-critical MRI findings of an Alzheimer's disease patient with pathologically proven cerebral amyloid angiopathy related lobar hemorrhage

An 85-year-old woman with untreated hypertension was admitted with a disturbance of consciousness. On admission, brain CT revealed a lobar intracerebral hemorrhage with a midline shift. An intracranial hematoma was evacuated via a life-saving craniotomy. Definite pathological findings of amyloid-β deposition in the excised hematoma (strong in anti-amyloid β40 immunostain, but weak in anti- amyloid β42) indicated cerebral amyloid angiopathy (CAA). She had been diagnosed with Alzheimer's disease at a regional memory clinic one month before symptom onset based on MRI findings of medial temporal lobe atrophy as well as CAA-related features of multiple strictly lobar cerebral microbleeds in the occipital lobe, cortical superficial siderosis and >20 enlarged perivascular spaces in the centrum semiovale. This experience suggests that comprehensive interpretation of such CAA-related findings on MRI might help to improve the management of cardiovascular risk factors for Alzheimer's disease.

Microinfarcts are common and strongly related to dementia in the oldest-old: The 90+ study

INTRODUCTION

We estimated the prevalence of microinfarcts and their association with dementia in a cohort of oldest-old participants.

METHODS

Participants were from The 90+ Study, a population-based study of people 90 years and older. Dementia diagnoses were assigned postmortem during a consensus conference. Microinfarcts were evaluated in six brain regions.

RESULTS

At death, the 213 participants were on average 97 years old, 69% were women, and 52% had dementia. Of the participants, 51% had microinfarcts and 17% had 3+ microinfarcts. The odds ratio (OR) for dementia was similar for 3+ microinfarcts (OR = 4.75, P < .01) and tangle stage V-VI (OR = 4.70, P < .001). Only microinfarcts in cortical regions (other than occipital) were associated to dementia.

DISCUSSION

In this oldest-old cohort, microinfarcts are common and contribute independently and similarly in magnitude to dementia as tangles. As risk factors for microinfarcts and other dementing pathologies are likely to differ, identifying these factors is crucial to developing prevention strategies for dementia in the oldest-old.

Longitudinal noninvasive magnetic resonance imaging of brain microhemorrhages in BACE inhibitor-treated APP transgenic mice

Currently, several immunotherapies and BACE (Beta Site APP Cleaving Enzyme) inhibitor approaches are being tested in the clinic for the treatment of Alzheimer's disease. A crucial mechanism-related safety concern is the exacerbation of microhemorrhages, which are already present in the majority of Alzheimer patients. To investigate potential safety liabilities of long-term BACE inhibitor therapy, we used aged amyloid precursor protein (APP) transgenic mice (APP23), which robustly develop cerebral amyloid angiopathy. T2*-weighted magnetic resonance imaging (MRI), a translational method applicable in preclinical and clinical studies, was used for the detection of microhemorrhages throughout the entire brain, with subsequent histological validation. Three-dimensional reconstruction based on in vivo MRI and serial Perls' stained sections demonstrated a one-to-one matching of the lesions thus allowing for their histopathological characterization. MRI detected small Perls' positive areas with a high spatial resolution. Our data demonstrate that volumetric assessment by noninvasive MRI is well suited to monitor cerebral microhemorrhages in vivo. Furthermore, 3 months treatment of aged APP23 with the potent BACE-inhibitor NB-360 did not exacerbate microhemorrhages in contrast to Aβ-antibody β1. These results substantiate the safe use of BACE inhibitors regarding microhemorrhages in long-term clinical studies for the treatment of Alzheimer's disease.

Clinico-Radiological Characteristics and Pathological Diagnosis of Cerebral Amyloid Angiopathy-Related Intracerebral Hemorrhage

OBJECTIVE

We aim to clarify the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage and to investigate the efficacy of pathological diagnosis using biopsy specimens.

METHOD

We retrospectively reviewed 253 consecutive patients with cortico-subcortical hemorrhage who had been admitted to Aizawa Hospital between January 2006 and July 2013. We had performed craniotomy and hematoma evacuation in 48 patients, as well as biopsy of the evacuated hematoma, cerebral parenchyma adjacent to the hematoma, or both, and they were classified according to the histological results (positive or negative for vascular amyloid deposition) and to the Boston criteria. We compared the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage. We also investigated the detection rate of cerebral amyloid angiopathy with respect to the origins of the specimens.

RESULTS

Pathological examination revealed that 22 subjects were positive for vascular amyloid. The number of the cerebral microbleeds located in the deep or infratentorial region was significantly larger in the negative group than in the positive group (P <.05). There was no significant difference in the distribution of lobar cerebral microbleeds and in the prevalence of hypertension. In the probable cerebral amyloid angiopathy-related intracerebral hemorrhage patients, the probability of having vascular amyloid detected by biopsy of both hematoma and parenchyma was 100%. Rebleeding in the postoperative periods was observed in 2 cases (9.1%) of the positive group.

CONCLUSIONS

Our results demonstrate the importance and safety of biopsy simultaneously performed with hematoma evacuation. Deep or infratentorial microbleeds are less correlated with cerebral amyloid angiopathy-related intracerebral hemorrhage than with noncerebral amyloid angiopathy-related intracerebral hemorrhage.

Amyloid properties of the leader peptide of variant B cystatin C: implications for Alzheimer and macular degeneration

Variant B (VB) of cystatin C has a mutation in its signal peptide (A25T), which interferes with its processing leading to reduced secretion and partial retention in the vicinity of the mitochondria. There are genetic evidences of the association of VB with Alzheimer's disease (AD) and age-related macular degeneration (AMD). Here, we investigated aggregation and amyloid propensities of unprocessed VB combining computational and in vitro studies. Aggregation predictors revealed the presence of four aggregation-prone regions, with a strong one at the level of the signal peptide, which indeed formed toxic aggregates and mature amyloid fibrils in solution. In light of these results, we propose for the first time the role of the signal peptide in pathogenesis of AD and AMD.

ApoA1, ApoJ and ApoE Plasma Levels and Genotype Frequencies in Cerebral Amyloid Angiopathy

The involvement of apolipoproteins, such as the ApoE4 isoform, in Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA) highlights the fact that certain lipid carriers may participate in soluble β-amyloid (Aβ) transport. Our general aim was to characterize the soluble levels of the apolipoproteins apoE, apoA1 and apoJ/clusterin and their genotype status in patients with CAA. We analyzed the genotypes frequency of APOA1 (rs5069, rs670), CLU (rs11136000, rs1532278, rs7012010, rs9331888) and APOE (rs429358, rs7412) in a cohort of patients with CAA-associated intracerebral hemorrhage (ICH) (n = 59) and compared the results with those from hypertension-associated ICH (n = 42), AD patients (n = 73) and controls (n = 88). In a subgroup of patients, we also determined the plasma concentrations of apoE, apoA1 and apoJ/clusterin. We found increased plasma apoJ/clusterin levels in CAA patients compared to AD patients or controls after adjusting for sex and age (CAA vs. controls, p = 0.033; CAA vs. AD, p = 0.013). ApoA1 levels were not altered between groups, although a strong correlation was observed between plasma Aβ(1-40) and apoA1 among CAA patients (r = 0.583, p = 0.007). Regarding plasma apoE concentration, a robust association between circulating levels and genotype status was confirmed (p < 0.001). Whereas the APOE4 frequency was higher in AD (p < 0.001) and CAA (p = 0.013), the APOA1 and CLU genotypes were not different among groups. In the CAA cohort, the risk-linked CLU variant (C) rs11136000 was associated with white matter hyperintensities (p = 0.045) and the presence of lobar microbleeds (p = 0.023) on MRI. In summary, our findings suggest that apoA1 may act as a physiological transporter of Aβ(1-40) and that apoJ/clusterin appears to be a chaperone related to distinctive lesions in CAA brains.

Amyloid spells and high blood pressure: imminent danger?

We present the case of a 71-year-old male, admitted after a generalized tonic-clonic seizure, with a history of recurrent left arm and face paresthesias, associated with sulcal cortical subarachnoid hemorrhages. During the next 48 h, he remained agitated with a high blood pressure profile; he also suffered a cardiac arrest in relation to a severe left fronto-parietal and a smaller right parietal parenchymal hemorrhage that developed over the subarachnoid hemorrhage locations. There were no intracranial vascular abnormalities. Three months later, an MRI revealed disseminated superficial siderosis. He was discharged with a modified Rankin scale of 4. He died 1 month later of unknown cause. A diagnosis of probable cerebral amyloid angiopathy was assumed. Patients with pathologically proven cerebral amyloid angiopathy that present with transient focal neurological symptoms in relation to cortical bleeds, the so-called ‘myloid spells’ seem to be at an increased risk of future parenchymal hemorrhages. Avoiding antiplatelet agents in these cases has been proposed. Our case suggests that these patients should be monitored closely in the hyperacute phase, and tight blood pressure control should be considered as the immediate risk of bleeding may be high, even without a definitive diagnosis of cerebral amyloid angiopathy.

Potential role of blood biomarkers in the management of nontraumatic intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH), a subtype of stroke associated with high mortality and disability, accounts for 13% of all strokes. Basic and clinical research has contributed to our understanding of the complex pathophysiology of neuronal injury in ICH. Outcome rates, however, remain stable, and questions regarding acute management of ICH remain unanswered. Newer research is aiming at matching measured levels of serum proteins, enzymes, or cells to different stages of brain damage, suggesting that blood biomarkers may assist in acute diagnosis, therapeutic decisions, and prognostication. This paper provides an overview on the most promising blood biomarkers and their potential role in the diagnosis and management of spontaneous ICH.

SUMMARY

Information was collected from studies, reviews, and guidelines listed in PubMed up to November 2013 on blood biomarkers of nontraumatic ICH in humans. We describe the potential role and limitations of GFAP, S100B/RAGE, and ApoC-III as diagnostic biomarkers, β-​Amyloid as a biomarker for etiological classification, and 27 biomarkers for prognosis of mortality and functional outcome. Within the group of prognostic markers we discuss markers involved in coagulation processes (e.g., D-Dimers), neuroendocrine markers (e.g., copeptin), systemic metabolic markers (e.g., blood glucose levels), markers of inflammation (e.g., IL-6), as well as growth factors (e.g., VEGF), and others (e.g., glutamate). Some of those blood biomarkers are agents of pathologic processes associated with hemorrhagic stroke but also other diseases, whereas others play more distinct pathophysiological roles and help in understanding the basic mechanisms of brain damage and/or recovery in ICH.

KEY MESSAGES

Numerous blood biomarkers are associated with different pathophysiological pathways in ICH, and some of them promise to be useful in the management of ICH, eventually contributing additional information to current tools for diagnosis, therapy monitoring, risk stratification, or intervention. Up to date, however, no blood biomarker of ICH has been studied sufficiently to find its way into clinical routine yet; well-designed, large-scale, clinical studies addressing relevant clinical questions are needed. We suggest that the effectiveness of biomarker research in ICH might be improved by international cooperation and shared resources for large validation studies, such as provided by the consortium on stroke biomarker research (http://stroke-biomarkers.​com/page.php?title=Resources).

Pinocembrin protects human brain microvascular endothelial cells against fibrillar amyloid-β(1-40) injury by suppressing the MAPK/NF-κB inflammatory pathways

Cerebrovascular accumulation of amyloid-β (Aβ) peptides in Alzheimer's disease (AD) may contribute to disease progression through Aβ-induced microvascular endothelial pathogenesis. Pinocembrin has been shown to have therapeutic effects in AD models. These effects correlate with preservation of microvascular function, but the effect on endothelial cells under Aβ-damaged conditions is unclear. The present study focuses on the in vitro protective effect of pinocembrin on fibrillar Aβ₁₋₄₀ (fAβ₁₋₄₀) injured human brain microvascular endothelial cells (hBMECs) and explores potential mechanisms. The results demonstrate that fAβ₁₋₄₀-induced cytotoxicity in hBMECs can be rescued by pinocembrin treatment. Pinocembrin increases cell viability, reduces the release of LDH, and relieves nuclear condensation. The mechanisms of this reversal from Aβ may be associated with the inhibition of inflammatory response, involving inhibition of MAPK activation, downregulation of phosphor-IKK level, relief of IκBα degradation, blockage of NF-κB p65 nuclear translocation, and reduction of the release of proinflammatory cytokines. Pinocembrin does not show obvious effects on regulating the redox imbalance after exposure to fAβ₁₋₄₀. Together, the suppression of MAPK and the NF-κB signaling pathways play a significant role in the anti-inflammation of pinocembrin in hBMECs subjected to fAβ₁₋₄₀. This may serve as a therapeutic agent for BMEC protection in Alzheimer's-related deficits.

Subtle neuropsychiatric and neurocognitive changes in hereditary gelsolin amyloidosis (AGel amyloidosis)

Hereditary gelsolin amyloidosis (AGel amyloidosis) is an autosomal dominant form of systemic amyloidosis caused by a c.640G>A or c.640G>T mutation in the gene coding for gelsolin. Principal clinical manifestations include corneal lattice dystrophy, cranial neuropathy and cutis laxa with vascular fragility. Signs of minor CNS involvement have also been observed, possibly related to cerebral amyloid angiopathy (CAA). To investigate further if AGel amyloidosis carries a risk for a specific neuropsychological or psychiatric symptomatology we studied 35 AGel patients and 29 control subjects. Neuropsychological tests showed abnormalities in visuocontructional and -spatial performance in AGel patients, also some indication of problems in processing efficacy was found. At psychiatric evaluation the patient group showed more psychiatric symptomatology, mainly depression. In brain MRI, available in 16 patients and 14 controls, we found microhemorrhages or microcalcifications only in the patient group, although the number of findings was small. Our study shows that AGel amyloidosis can be associated with visuoconstructional problems and depression, but severe neuropsychiatric involvement is not characteristic. The gelsolin mutation may even induce cerebrovascular fragility, but further epidemiological and histopathological as well as longitudinal follow-up studies are needed to clarify gelsolin-related vascular pathology and its clinical consequences.