Familial cerebral amyloid disorders with prominent white matter involvement.

Familial cerebral amyloid disorders are characterized by the accumulation of fibrillar protein aggregates, which deposit in the parenchyma as plaques and in the vasculature as cerebral amyloid angiopathy (CAA). Amyloid ß (Aß) is the most common of these amyloid proteins, accumulating in familial and sporadic forms of Alzheimer's disease and CAA. However, there are also a number of rare, hereditary, non-Aß cerebral amyloidosis. The clinical manifestations of these familial cerebral amyloid disorders are diverse, including cognitive or neuropsychiatric presentations, intracerebral hemorrhage, seizures, myoclonus, headache, ataxia, and spasticity. Some mutations are associated with extensive white matter hyperintensities on imaging, which may or may not be accompanied by hemorrhagic imaging markers of CAA; others are associated with occipital calcification. We describe the clinical, imaging, and pathologic features of these disorders and discuss putative disease mechanisms. Familial disorders of cerebral amyloid accumulation offer unique insights into the contributions of vascular and parenchymal amyloid to pathogenesis and the pathways underlying white matter involvement in neurodegeneration. With Aß immunotherapies now entering the clinical realm, gaining a deeper understanding of these processes and the relationships between genotype and phenotype has never been more relevant.

Temporal Characterization of the Amyloidogenic APPswe/PS1dE9;hAPOE4 Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is a devastating disorder with a global prevalence estimated at 55 million people. In clinical studies administering certain anti-beta-amyloid (Aß) antibodies, amyloid-related imaging abnormalities (ARIAs) have emerged as major adverse events. The frequency of these events is higher among apolipoprotein ε4 allele carriers (APOE4) compared to non-carriers. To reflect patients most at risk for vascular complications of anti-Aß immunotherapy, we selected an APPswe/PS1dE9 transgenic mouse model bearing the human APOE4 gene (APPPS1:E4) and compared it with the same APP/PS1 mouse model bearing the human APOE3 gene (APOE ε3 allele; APPPS1:E3). Using histological and biochemical analyses, we characterized mice at three ages: 8, 12, and 16 months. Female and male mice were assayed for general cerebral fibrillar and pyroglutamate (pGlu-3) Aß deposition, cerebral amyloid angiopathy (CAA), microhemorrhages, apoE and cholesterol composition, astrocytes, microglia, inflammation, lysosomal dysfunction, and neuritic dystrophy. Amyloidosis, lipid deposition, and astrogliosis increased with age in APPPS1:E4 mice, while inflammation did not reveal significant changes with age. In general, APOE4 carriers showed elevated Aß, apoE, reactive astrocytes, pro-inflammatory cytokines, microglial response, and neuritic dystrophy compared to APOE3 carriers at different ages. These results highlight the potential of the APPPS1:E4 mouse model as a valuable tool in investigating the vascular side effects associated with anti-amyloid immunotherapy.

Dominant CST3 variants cause adult onset leukodystrophy without amyloid angiopathy.

Leukodystrophies are rare genetic white matter disorders that have been regarded as mainly occurring in childhood. This perception has been altered in recent years, as a growing number of leukodystrophies have been described as having an onset in adulthood. Still, many adult patients presenting with white matter changes remain without a specific molecular diagnosis. We describe a novel adult onset leukodystrophy in 16 patients from eight families carrying one of four different stop-gain or frameshift dominant variants in the CST3 gene. Clinical and radiological features differ markedly from the previously described Icelandic cerebral amyloid angiopathy found in patients carrying p.Leu68Asn substitution in CST3. The clinical phenotype consists of recurrent episodes of hemiplegic migraine associated with transient unilateral focal deficits and slowly progressing motor symptoms and cognitive decline in mid to older adult ages. In addition, in some cases acute onset clinical deterioration led to a prolonged episode with reduced consciousness and even early death. Radiologically, pathognomonic changes are found at typical predilection sites involving the deep cerebral white matter sparing a periventricular and directly subcortical rim, the middle blade of corpus callosum, posterior limb of the internal capsule, middle cerebellar peduncles, cerebral peduncles and specifically the globus pallidus. Histopathologic characterization in two autopsy cases did not reveal angiopathy, but instead micro- to macrocystic degeneration of the white matter. Astrocytes were activated at early stages and later displayed severe degeneration and loss. In addition, despite the loss of myelin, elevated numbers of partly apoptotic oligodendrocytes were observed. A structural comparison of the variants in CST3 suggests that specific truncations of cystatin C result in an abnormal function, possibly by rendering the protein more prone to aggregation. Future studies are required to confirm the assumed effect on the protein and to determine pathophysiologic downstream events at the cellular level.

Distribution and progression of cerebral amyloid angiopathy in early-onset V30M (p.V50M) hereditary ATTR amyloidosis.

BACKGROUND: Cerebral amyloid angiopathy (CAA) is becoming the most common and serious complications in long-lived hereditary ATTR amyloidosis patients. It is therefore imperative to elucidate the characteristics of ATTR-type CAA and develop useful biomarkers. METHODS: We enrolled 34 ATTRv amyloidosis patients with the V30M (p.V50M) variant for analysis with three-dimensional stereotactic surface projection z score imaging of Pittsburgh compound B (PiB)-PET. RESULTS: Eight patients exhibited central nervous system (CNS) symptoms. Seven patients suffered transient focal neurologic episodes, and 2 patients each experienced cerebellar haemorrhages or cognitive decline. The amount of 11C-PiB accumulation increased as a function of disease duration. 11C-PiB-PET abnormalities were seen at 8 years from onset and were associated with CNS manifestations from 12 years. The annual increase rate of the standardised uptake value ratio (SUVR) in female patients was significantly higher than in male patients. CNS amyloid deposition started in the upper middle surface of the cerebellar cortex, and then spread out over the entire surface of the cerebellum, Sylvian fissure, and anterior part of the longitudinal fissure of the cerebrum. CONCLUSIONS: PiB-PET is a useful biomarker for the early detection and treatment evaluation of ATTR-type CAA. Female gender is associated with more rapid progression of ATTR-type CAA.

Fruquintinib/HMPL-013 ameliorates cognitive impairments and pathology in a mouse model of cerebral amyloid angiopathy (CAA).

Cerebral amyloid angiopathy (CAA) is characterized by the cerebrovascular amyloid-ß (Aß) accumulation, and always accompanied by Alzheimer's disease (AD). The mechanisms revealing CAA pathogenesis are still unclear, and it is challenging to develop an efficient therapeutic strategy for its treatment. Vascular endothelial growth factor (VEGF) and its receptors including VEGFR-1,-2,-3 activation are involved in Aß processing, and modulate numerous cellular events associated with central nervous system (CNS) diseases. In the present study, we attempted to explore the regulatory function of fruquintinib (also named as HMPL-013), a highly selective inhibitor of VEGFR-1,-2,-3 tyrosine kinases, on CAA progression in Tg-SwDI mice. Here, we found that HMPL-013-rich diet consumption for 12 months significantly improved the behavioral performances and cerebral blood flow (CBF) of Tg-SwDI mice compared with the vehicle group. Importantly, HMPL-013 administration considerably reduced Aß1-40 and Aß1-42 burden in cortex and hippocampus of Tg-SwDI mice through regulating Aß metabolism process. Congo red staining confirmed Aß deposition in vessel walls, reflecting CAA formation, which was, however, strongly ameliorated after HMPL-013 treatment. Neuron death, aberrant glial activation and pro-inflammatory response in brain tissues of Tg-SwDI mice were dramatically alleviated after HMPL-013 consumption. More studies showed that the protective effects of HMPL-013 against CAA might be partially attributed to its regulation on the expression of genes associated with blood vasculature. Intriguingly, VEGF and phosphorylated VEGFR-1,-2 protein expression levels were remarkably decreased by HMPL-013 in cortex and hippocampus of Tg-SwDI mice, which were validated in HMPL-013-treated brain vascular endothelial cells (BVECs) under hypoxia. Finally, we found that VEGF-induced human umbilical vein endothelial cells (HUVEC) proliferation and tube formation were strongly abolished upon HMPL-013 exposure. Collectively, all these findings demonstrated that oral administration of HMPL-013 had therapeutic potential against CAA by reducing Aß deposition, inflammation and neuron death via suppressing VEGF/VEGFR-1,-2 signaling.

Clinical, Neuroimaging, and Genetic Markers in Cerebral Amyloid Angiopathy-Related Inflammation: A Systematic Review and Meta-Analysis.

BACKGROUND: There are limited data regarding the prevalence of distinct clinical, neuroimaging and genetic markers among patients diagnosed with cerebral amyloid angiopathy-related inflammation (CAA-ri). We sought to determine the prevalence of clinical, radiological, genetic and cerebrospinal fluid biomarker findings in patients with CAA-ri. METHODS: A systematic review and meta-analysis of published studies including patients with CAA-ri was conducted to determine the prevalence of clinical, neuroimaging, genetic and cerebrospinal fluid biomarker findings. Subgroup analyses were performed based on (1) prospective or retrospective study design and (2) CAA-ri diagnosis with or without available biopsy. We pooled the prevalence rates using random-effects models and assessed the heterogeneity using Cochran-Q and I2-statistics. RESULTS: We identified 4 prospective and 17 retrospective cohort studies comprising 378 patients with CAA-ri (mean age, 71.5 years; women, 52%). The pooled prevalence rates were as follows: cognitive decline at presentation 70% ([95% CI, 54%-84%]; I2=82%), focal neurological deficits 55% ([95% CI, 40%-70%]; I2=82%), encephalopathy 54% ([95% CI, 39%-68%]; I2=43%), seizures 37% ([95% CI, 27%-49%]; I2=65%), headache 31% ([95% CI, 22%-42%]; I2=58%), T2/fluid-attenuated inversion recovery-hyperintense white matter lesions 98% ([95% CI, 93%-100%]; I2=44%), lobar cerebral microbleeds 96% ([95% CI, 92%-99%]; I2=25%), gadolinium enhancing lesions 54% ([95% CI, 42%-66%]; I2=62%), cortical superficial siderosis 51% ([95% CI, 34%-68%]; I2=77%) and lobar macrohemorrhage 40% ([95% CI, 11%-73%]; I2=88%). The prevalence rate of the ApoE (Apolipoprotein E) ε4/ε4 genotype was 34% ([95% CI, 17%-53%]; I2=76%). Subgroup analyses demonstrated no differences in these prevalence rates based on study design and diagnostic strategy. CONCLUSIONS: Cognitive decline was the most common clinical feature. Hyperintense T2/fluid-attenuated inversion recovery white matter lesions and lobar cerebral microbleeds were by far the most prevalent neuroimaging findings. Thirty-four percent of patients with CAA-ri have homozygous ApoE ε4/ε4 genotype and scarce data exist regarding the cerebrospinal fluid biomarkers and its significance in these patients.

Brain Deep Medullary Veins on 7T MRI in Dutch-Type Hereditary Cerebral Amyloid Angiopathy.

BACKGROUND: Deep medullary vein (DMV) changes occur in cerebral small vessel diseases (SVD) and in Alzheimer's disease. Cerebral amyloid angiopathy (CAA) is a common SVD that has a high co-morbidity with Alzheimer's disease. So far, DMVs have not been evaluated in CAA. OBJECTIVE: To evaluate DMVs in Dutch-type hereditary CAA (D-CAA) mutation carriers and controls, in relation to MRI markers associated with D-CAA. METHODS: Quantitative DMV parameters length, tortuosity, inhomogeneity, and density were quantified on 7 Tesla 3D susceptibility weighted MRI in pre-symptomatic D-CAA mutation carriers (n = 8), symptomatic D-CAA mutation carriers (n = 8), and controls (n = 25). Hemorrhagic MRI markers (cerebral microbleeds, intracerebral hemorrhages, cortical superficial siderosis, convexity subarachnoid hemorrhage), non-hemorrhagic MRI markers (white matter hyperintensities, enlarged perivascular spaces, lacunar infarcts, cortical microinfarcts), cortical grey matter perfusion, and diffusion tensor imaging parameters were assessed in D-CAA mutation carriers. Univariate general linear analysis was used to determine associations between DMV parameters and MRI markers. RESULTS: Quantitative DMV parameters length, tortuosity, inhomogeneity, and density did not differ between pre-symptomatic D-CAA mutation carriers, symptomatic D-CAA mutation carriers, and controls. No associations were found between DMV parameters and MRI markers associated with D-CAA. CONCLUSION: This study indicates that vascular amyloid-ß deposition does not affect DMV parameters. In patients with CAA, DMVs do not seem to play a role in the pathogenesis of MRI markers associated with CAA.

Chemical traits of cerebral amyloid angiopathy in familial British-, Danish-, and non-Alzheimer's dementias.

Familial British dementia (FBD) and familial Danish dementia (FDD) are autosomal dominant forms of dementia caused by mutations in the integral membrane protein 2B (ITM2B, also known as BRI2) gene. Secretase processing of mutant BRI2 leads to secretion and deposition of BRI2-derived amyloidogenic peptides, ABri and ADan that resemble APP/ß-amyloid (Aß) pathology, which is characteristic of Alzheimer's disease (AD). Amyloid pathology in FBD/FDD manifests itself predominantly in the microvasculature by ABri/ADan containing cerebral amyloid angiopathy (CAA). While ABri and ADan peptide sequences differ only in a few C-terminal amino acids, CAA in FDD is characterized by co-aggregation of ADan with Aß, while in contrast no Aß deposition is observed in FBD. The fact that FDD patients display an earlier and more severe disease onset than FBD suggests a potential role of ADan and Aß co-aggregation that promotes a more rapid disease progression in FDD compared to FBD. It is therefore critical to delineate the chemical signatures of amyloid aggregation in these two vascular dementias. This in turn will increase the knowledge on the pathophysiology of these diseases and the pathogenic role of heterogenous amyloid peptide interactions and deposition, respectively. Herein, we used matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) in combination with hyperspectral, confocal microscopy based on luminescent conjugated oligothiophene probes (LCO) to delineate the structural traits and associated amyloid peptide patterns of single CAA in postmortem brain tissue of patients with FBD, FDD as well as sporadic CAA without AD (CAA+) that show pronounced CAA without parenchymal plaques. The results show that CAA in both FBD and FDD consist of N-terminally truncated- and pyroglutamate-modified amyloid peptide species (ADan and ABri), but that ADan peptides in FDD are also extensively C-terminally truncated as compared to ABri in FBD, which contributes to hydrophobicity of ADan species. Further, CAA in FDD showed co-deposition with Aß x-42 and Aß x-40 species. CAA+ vessels were structurally more mature than FDD/FBD CAA and contained significant amounts of pyroglutamated Aß. When compared with FDD, Aß in CAA+ showed more C-terminal and less N-terminally truncations. In FDD, ADan showed spatial co-localization with Aß3pE-40 and Aß3-40 but not with Aßx-42 species. This suggests an increased aggregation propensity of Aß in FDD that promotes co-aggregation of both Aß and ADan. Further, CAA maturity appears to be mainly governed by Aß content based on the significantly higher 500/580 patterns observed in CAA+ than in FDD and FBD, respectively. Together this is the first study of its kind on comprehensive delineation of Bri2 and APP-derived amyloid peptides in single vascular plaques in both FDD/FBD and sporadic CAA that provides new insight in non-AD-related vascular amyloid pathology. Cover Image for this issue: https://doi.org/10.1111/jnc.15424.

Impact of Cerebral Amyloid Angiopathy in Two Transgenic Mouse Models of Cerebral ß-Amyloidosis: A Neuropathological Study.

The pathological accumulation of parenchymal and vascular amyloid-beta (Aß) are the main hallmarks of Alzheimer's disease (AD) and Cerebral Amyloid Angiopathy (CAA), respectively. Emerging evidence raises an important contribution of vascular dysfunction in AD pathology that could partially explain the failure of anti-Aß therapies in this field. Transgenic mice models of cerebral ß-amyloidosis are essential to a better understanding of the mechanisms underlying amyloid accumulation in the cerebrovasculature and its interactions with neuritic plaque deposition. Here, our main objective was to evaluate the progression of both parenchymal and vascular deposition in APP23 and 5xFAD transgenic mice in relation to age and sex. We first showed a significant age-dependent accumulation of extracellular Aß deposits in both transgenic models, with a greater increase in APP23 females. We confirmed that CAA pathology was more prominent in the APP23 mice, demonstrating a higher progression of Aß-positive vessels with age, but not linked to sex, and detecting a pronounced burden of cerebral microbleeds (cMBs) by magnetic resonance imaging (MRI). In contrast, 5xFAD mice did not present CAA, as shown by the negligible Aß presence in cerebral vessels and the occurrence of occasional cMBs comparable to WT mice. In conclusion, the APP23 mouse model is an interesting tool to study the overlap between vascular and parenchymal Aß deposition and to evaluate future disease-modifying therapy before its translation to the clinic.

Longitudinal Progression of Magnetic Resonance Imaging Markers and Cognition in Dutch-Type Hereditary Cerebral Amyloid Angiopathy.

BACKGROUND: Hemorrhagic and ischemic magnetic resonance imaging lesions as well as the more recently described decrease in vasomotor reactivity have been suggested as possible biomarkers for cerebral amyloid angiopathy (CAA). Analyses of these markers have been primarily cross-sectional during the symptomatic phase of the disease, with little data on their longitudinal progression, particularly in the presymptomatic phase of the disease when it may be most responsive to treatment. We used the unique opportunity provided by studying Dutch-type hereditary cerebral amyloid angiopathy (D-CAA) to determine longitudinal progression of CAA biomarkers during the presymptomatic as well as the symptomatic phase of the disease. METHODS: In this longitudinal case-control study, magnetic resonance imaging markers and cognitive performance were assessed at baseline and after ≈4 years in 10 presymptomatic and 6 symptomatic D-CAA mutation carriers and 20 control subjects. These magnetic resonance imaging markers included hemorrhagic and ischemic manifestations, measurements of cerebral blood flow, and vasomotor reactivity to visual stimulation. RESULTS: In presymptomatic D-CAA mutations carriers, vasomotor reactivity showed a decline over time for blood-oxygen-level-dependent amplitude (P=0.011) and prolongation of time to peak (P<0.001). In contrast, no significant changes in hemorrhagic markers, ischemic markers, cerebral blood flow, and cognition were found. In symptomatic D-CAA mutation carriers, the number of intracerebral hemorrhages increased over the 4-year period (P=0.007). CONCLUSIONS: Our findings indicate that in the presymptomatic phase of D-CAA, cerebrovascular reactivity measured by the blood-oxygen-level-dependent amplitude and time to peak to visual stimulation progressively worsens and can thus be regarded as a disease progression marker. In the symptomatic phase, the most salient marker of progression appears to be recurrent intracerebral hemorrhage.

A case of transthyretin-related cerebral amyloid angiopathy. The other side of hereditary transthyretin amyloidosis.

The target organs for familial transthyretin amyloidosis are typically the nerves, the heart or even the eyes due to the accumulation of amyloid deposits. Less frequently, these deposits can occur within the central nervous system and drive a specific phenotype of cerebral amyloid angiopathy. We report the case of a 72-year-old woman showing evidence of cerebral amyloid angiopathy, in a context of hereditary transthyretin amyloidosis (hATTR) due to p.(Ser77Tyr) mutation of the TTR gene. Her cognitive assessment on a two-year follow-up was remarkably steady. A very limited number of patients with hereditary transthyretin amyloidosis associated with a cerebral amyloid angiopathy have been reported. Few characteristics could distinguish them from classic cerebral amyloid angiopathy, and more data are needed to highlight specific features. Screening for peripheral neuropathy should be considered for patients referred to memory clinic for atypical cerebral amyloid angiopathy.

Spatial and temporal intracerebral hemorrhage patterns in Dutch-type hereditary cerebral amyloid angiopathy.

AIM: To investigate whether there is a topographical and temporal pattern of index and recurrent intracerebral hemorrhages (ICH) in Dutch-type hereditary Cerebral Amyloid Angiopathy (D-CAA) to increase our understanding on CAA-related ICH development. METHODS: We included patients with DNA confirmed D-CAA or a history with ≥1 lobar ICH and ≥1 first-degree relative with D-CAA. Topographical pattern was studied by location (proportion frontal/parietal/temporal/occipital; infra/supratentorial and occurrence ratios relative to lobe volume) and volume of index and recurrent ICHs were determined on CT. Temporal pattern was examined by time between recurrent ICHs was retrieved from medical records. RESULTS: We included 72 patients with D-CAA (mean age at index ICH 55 years) with in total 214 ICH. The median follow-up time was 7 years (range 0.8 to 28 years). All ICH were lobar and supratentorial. The index ICH was most frequently located in the occipital lobe (34% vs. 22% in the other three lobes; with index ICH occurrence ratios relative to lobe volume of 1.9 for occipital, 1.0 for temporal, 1.2 for parietal, and 0.5 for frontal, p = 0.001). In 16/47 (34%) patients with multiple ICH, the second ICH was located in the same lobe as the index ICH. The median time-interval between subsequent ICH was #1-2 ICH 27 months, #2-3 ICH 14 months, and #3-4 ICH 7 months (p = 0.6) There was no difference in volume between index and recurrent ICHs. CONCLUSIONS: We found that index and recurrent ICHs in D-CAA have a preference for the occipital lobe and are least frequent in the frontal lobe, which adds to the existing knowledge of histopathological studies on amyloid load in CAA. Surprisingly, there was no acceleration in time nor gradual increase of hematoma volume between subsequent ICHs.

Cerebellar hemorrhages in patients with Dutch-type hereditary cerebral amyloid angiopathy.

BACKGROUND: Recent studies suggest that superficially located cerebellar intracerebral hemorrhage (ICH) and microbleeds might point towards sporadic cerebral amyloid angiopathy (CAA). AIMS: We investigated the proportion of cerebellar ICH and asymptomatic macro- and microbleeds in Dutch-type hereditary CAA (D-CAA), a severe and essentially pure form of CAA. METHODS: Symptomatic patients with D-CAA (defined as ≥1 symptomatic ICH) and presymptomatic D-CAA mutation-carriers were included. We assessed magnetic resonance imaging scans for symptomatic (cerebellar) ICH and asymptomatic cerebellar macro- and microbleeds according to the STRIVE-criteria. Location was assessed as superficial-cerebellar (cortex, vermis or juxta-cortical) or deep-cerebellar (white matter, pedunculi cerebelli and gray nuclei). RESULTS: We included 63 participants (mean age 58 years, 60% women, 42 symptomatic). In total, the 42 symptomatic patients with D-CAA had 107 symptomatic ICH (range 1-7). None of these ICH were located in the cerebellum. Six of 42 (14%, 95%CI 4-25%) symptomatic patients and none of the 21 (0%, 95%CI 0-0%) presymptomatic carriers had ≥ 1 asymptomatic cerebellar macrobleed(s). All macrobleeds were superficially located. Cerebellar microbleeds were found in 40 of 63 (64%, 95%CI 52-76) participants (median 1.0, range 0-159), 81% in symptomatic patients and 29% in presymptomatic carriers. All microbleeds were strictly or predominantly superficially (ratio superficial versus deep 15:1) located. CONCLUSIONS: Superficially located asymptomatic cerebellar macrobleeds and microbleeds are common in D-CAA. Cerebellar microbleeds are already present in the presymptomatic stage. Despite the high frequency of cerebellar micro and macrobleeds, CAA pathology did not result in symptomatic cerebellar ICH in patients with D-CAA.

MFG-E8 (LACTADHERIN): a novel marker associated with cerebral amyloid angiopathy.

Brain accumulation of amyloid-beta (Aß) is a crucial feature in Alzheimer´s disease (AD) and cerebral amyloid angiopathy (CAA), although the pathophysiological relationship between these diseases remains unclear. Numerous proteins are associated with Aß deposited in parenchymal plaques and/or cerebral vessels. We hypothesized that the study of these proteins would increase our understanding of the overlap and biological differences between these two pathologies and may yield new diagnostic tools and specific therapeutic targets. We used a laser capture microdissection approach combined with mass spectrometry in the APP23 transgenic mouse model of cerebral-ß-amyloidosis to specifically identify vascular Aß-associated proteins. We focused on one of the main proteins detected in the Aß-affected cerebrovasculature: MFG-E8 (milk fat globule-EGF factor 8), also known as lactadherin. We first validated the presence of MFG-E8 in mouse and human brains. Immunofluorescence and immunoblotting studies revealed that MFG-E8 brain levels were higher in APP23 mice than in WT mice. Furthermore, MFG-E8 was strongly detected in Aß-positive vessels in human postmortem CAA brains, whereas MFG-E8 was not present in parenchymal Aß deposits. Levels of MFG-E8 were additionally analysed in serum and cerebrospinal fluid (CSF) from patients diagnosed with CAA, patients with AD and control subjects. Whereas no differences were found in MFG-E8 serum levels between groups, MFG-E8 concentration was significantly lower in the CSF of CAA patients compared to controls and AD patients. Finally, in human vascular smooth muscle cells MFG-E8 was protective against the toxic effects of the treatment with the Aß40 peptide containing the Dutch mutation. In summary, our study shows that MFG-E8 is highly associated with CAA pathology and highlights MFG-E8 as a new CSF biomarker that could potentially be used to differentiate cerebrovascular Aß pathology from parenchymal Aß deposition.

Distinct brain regional proteome changes in the rTg-DI rat model of cerebral amyloid angiopathy.

Cerebral amyloid angiopathy (CAA), a prevalent cerebral small vessel disease in the elderly and a common comorbidity of Alzheimer's disease, is characterized by cerebral vascular amyloid accumulation, cerebral infarction, microbleeds, and intracerebral hemorrhages and is a prominent contributor to vascular cognitive impairment and dementia. Here, we investigate proteome changes associated with specific pathological features in several brain regions of rTg-DI rats, a preclinical model of CAA. Whereas varying degrees of microvascular amyloid and associated neuroinflammation are found in several brain regions, the presence of microbleeds and occluded small vessels is largely restricted to the thalamic region of rTg-DI rats, indicating different levels of CAA and associated pathologies occur in distinct brain regions in this model. Here, using SWATHLC-MS/MS, we report specific proteomic analysis of isolated brain regions and employ pathway analysis to correlate regionally specific proteomic changes with uniquely implicated molecular pathways. Pathway analysis suggested common activation of tumor necrosis factor α (TNFα), abnormal nervous system morphology, and neutrophil degranulation in all three regions. Activation of transforming growth factor-ß1 (TGF-ß1) was common to the hippocampus and thalamus, which share high CAA loads, while the thalamus, which uniquely exhibits thrombotic events, additionally displayed activation of thrombin and aggregation of blood cells. Thus, we present significant and new insight into the cerebral proteome changes found in distinct brain regions with differential CAA-related pathologies of rTg-DI rats and provide new information on potential pathogenic mechanisms associated with these regional disease processes.

Occipital Cortical Calcifications in Cerebral Amyloid Angiopathy.

Background and Purpose: Cortical calcifications have been reported in patients with cerebral amyloid angiopathy (CAA), although their prevalence and pathophysiology are unknown. We investigated the frequency of calcifications on computed tomography, their association with intracerebral hemorrhage (ICH) and their coexistence with a striped pattern of the occipital cortex reflecting microcalcifications on ultra-high-field 7T-magnetic resonance imaging in Dutch-type hereditary CAA (D-CAA) and sporadic CAA. Methods: We included D-CAA mutation carriers with a proven APP (amyloid precursor protein) mutation or ≥1 lobar ICH and ≥1 first-degree relative with D-CAA and sporadic CAA patients with probable CAA according to the modified Boston criteria. D-CAA carriers were regarded symptomatic when they had a history of symptomatic ICH. We assessed the presence, location, and progression of calcifications and their association with ICH and the striped occipital cortex. Results: We found cortical calcifications in 15/81 (19% [95% CI, 11­29]) D-CAA mutation carriers (15/69 symptomatic and 0/12 presymptomatic) and in 1/59 (2% [95% CI, 0­9]) sporadic CAA patients. Calcifications were all bilateral located in the occipital lobes. In 3/15 (20%) of the symptomatic D-CAA patients the calcifications progressed over a period up to 10 years. There was evidence of an association between cortical calcifications and new ICH development (hazard ratio, 7.1 [95% CI, 0.9­54.9], log-rank P=0.03). In 7/25 D-CAA symptomatic carriers in whom a 7T-magnetic resonance imaging was performed, a striped pattern of the occipital cortex was present; in 3/3 (100%) of those with calcifications on computed tomography and 4/22 (18%) of those without calcifications. Conclusions: Occipital cortical calcifications are frequent in D-CAA but seem to be rare in sporadic CAA. Their absence in presymptomatic carriers and their association with ICH might suggest that they are a marker for advanced CAA. Cortical calcifications on computed tomography seem to be associated with the striped occipital cortex on 7T-magnetic resonance imaging which may possibly represent an early stage of calcification.

[A case of inflammatory cerebral amyloid angiopathy with white matter lesions appearing after brain biopsy].

A 76-year-old woman with a 7-year history of dementia presented to our hospital with generalized convulsive seizure for the first time. Contrast-enhanced brain magnetic resonance imaging revealed leptomeningeal enhancement mainly in the right occipital lobe and multiple lobar microbleeds in the bilateral cerebral and cerebellar subcortex. No white matter lesions were observed. A brain biopsy of the right parieto-occipital lobe revealed cerebral amyloid angiopathy (CAA). White matter lesions appeared in the right parieto-occipital lobe three days after the biopsy, and we considered inflammatory CAA. Three courses of methylprednisolone pulse followed by oral prednisolone therapy gradually reduced leptomeningeal and white matter lesions. An apolipoprotein E genotype investigation identified the ε2/ε3 genotype. In patients with inflammatory CAA, a risk of exacerbation should be considered after brain biopsy, in which the ε2 allele might play a role.

Cerebral amyloid angiopathy is associated with decreased functional brain connectivity.

Cerebral amyloid angiopathy (CAA) is a major cause of intracerebral hemorrhage and neurological decline in the elderly. CAA results in focal brain lesions, but the influence on global brain functioning needs further investigation. Here we study functional brain connectivity in patients with Dutch type hereditary CAA using resting state functional MRI. Twenty-four DNA-proven Dutch CAA mutation carriers (11 presymptomatic, 13 symptomatic) and 29 age-matched control subjects were included. Using a set of standardized networks covering the entire cortex, we assessed both within- and between-network functional connectivity. We investigated group differences using general linear models corrected for age, sex and gray matter volume. First, all mutation carriers were contrasted against control subjects and subsequently presymptomatic- and symptomatic mutation carriers against control subjects separately, to assess in which stage of the disease differences could be found. All mutation carriers grouped together showed decreased connectivity in the medial and lateral visual networks, default mode network, executive control and bilateral frontoparietal networks. Symptomatic carriers showed diminished connectivity in all but one network, and between the left and right frontoparietal networks. Presymptomatic carriers also showed diminished connectivity, but only in the frontoparietal left network. In conclusion, global brain functioning is diminished in patients with CAA, predominantly in symptomatic CAA and can therefore be considered to be a late consequence of the disease.

Amylin and pramlintide modulate γ-secretase level and APP processing in lipid rafts.

A major characteristic of Alzheimer's disease (AD) is the accumulation of misfolded amyloid-ß (Aß) peptide. Several studies linked AD with type 2 diabetes due to similarities between Aß and human amylin. This study investigates the effect of amylin and pramlintide on Aß pathogenesis and the predisposing molecular mechanism(s) behind the observed effects in TgSwDI mouse, a cerebral amyloid angiopathy (CAA) and AD model. Our findings showed that thirty days of intraperitoneal injection with amylin or pramlintide increased Aß burden in mice brains. Mechanistic studies revealed both peptides altered the amyloidogenic pathway and increased Aß production by modulating amyloid precursor protein (APP) and γ-secretase levels in lipid rafts. In addition, both peptides increased levels of B4GALNT1 enzyme and GM1 ganglioside, and only pramlintide increased the level of GM2 ganglioside. Increased levels of GM1 and GM2 gangliosides play an important role in regulating amyloidogenic pathway proteins in lipid rafts. Increased brain Aß burden by amylin and pramlintide was associated with synaptic loss, apoptosis, and microglia activation. In conclusion, our findings showed amylin or pramlintide increase Aß levels and related pathology in TgSwDI mice brains, and suggest that increased amylin levels or the therapeutic use of pramlintide could increase the risk of AD.