Pathogenesis Of Cerebral Amyloid Angiopathy Research Articles

Lead Acetate Exposure and Cerebral Amyloid Accumulation: Mechanistic Evaluations in APP/PS1 Mice.

The role of environmental factors in Alzheimer's disease (AD) pathogenesis remains elusive. Mounting evidence suggests that acute and past exposure to the environmental toxicant lead (Pb) is associated with longitudinal decline in cognitive function, brain atrophy, and greater brain -amyloid () deposition. However, the nature of Pb-induced amyloid deposition and how it contributes to AD development remain unclear. This study investigates the role of Pb in the pathogenesis of cerebral amyloid angiopathy (CAA) and whether plasminogen activator inhibitor-1 (PAI-1) contributes to this process in the APP/PS1 mouse model. Female APP/PS1 mice at 8 wk of age were administered either Pb-acetate (PbAc) (i.e., ) or an equivalent molar concentration of sodium acetate (NaAc) via oral gavage once daily for 8 wk. Amyloid deposition and vascular amyloid were determined by immunostaining. In addition, perivascular drainage, vascular binding assay, and microglial endocytosis were examined to determine underlying mechanisms. Furthermore, magnetic resonance imaging demyelination imaging was performed invivo measure the level of demyelination. Finally, Y-maze and Morris water maze tests were assessed to evaluate the cognitive function of mice. APP/PS1 mice (an AD mice model) exposed to PbAc demonstrated more vascular amyloid deposition less neocortical myelination, and lower cognitive function, as well as greater vascular binding to , higher ratios, strikingly lower levels in the perivascular drainage, and microglial endocytosis. Importantly, exposure to a specific PAI-1 inhibitor, tiplaxtinin, which previously was reported to lower CAA pathology in mice, resulted in less CAA-related outcomes following PbAc exposure. Our findings suggest that PbAc induced CAA/AD pathogenesis via the PAI-1 signaling in the APP/PS1 mouse model, and the inhibition of PAI-1 could be a potential therapeutic target for PbAc-mediated CAA/AD disorders. https://doi.org/10.1289/EHP14384.

Cerebral Proteomic Changes in the rTg-D Rat Model of Cerebral Amyloid Angiopathy Type-2 With Cortical Microhemorrhages and Cognitive Impairments.

Cerebral amyloid angiopathy (CAA) is a common disorder of the elderly, a prominent comorbidity of Alzheimer's disease, and causes vascular cognitive impairment and dementia. Previously, we generated a novel transgenic rat model (rTg-D) that produces human familial CAA Dutch E22Q mutant amyloid β-protein (Aβ) in brain and develops arteriolar CAA type-2. Here, we show that deposition of fibrillar Aβ promotes arteriolar smooth muscle cell loss and cerebral microhemorrhages that can be detected by magnetic resonance imaging and confirmed by histopathology. Aged rTg-D rats also present with cognitive deficits. Cerebral proteomic analyses revealed 241 proteins that were significantly elevated with an increase of >50% in rTg-D rats presenting with CAA compared to wild-type rats. Fewer proteins were significantly decreased in rTg-D rats. Of note, high temperature requirement peptidase A (HTRA1), a proteinase linked to transforming growth factor beta 1 (TGF-β1) signaling, was elevated and found to accumulate in cerebral vessels harboring amyloid deposits. Pathway analysis indicated elevation of the TGF-β1 pathway and increased TGF-β1 levels were detected in rTg-D rats. In conclusion, the present findings provide new molecular insights into the pathogenesis of CAA and suggest a role for interactions between HTRA1 and TGF-β1 in the disease process.

Comorbidity of cerebral amyloid angiopathy and Alzheimer's disease. Clinical case analysis

The development of cognitive impairment in old age is often caused by overlapping neurodegenerative and cerebrovascular changes which have a mutually aggravating clinical effect. In recent years, the problem of cerebral amyloid angiopathy (CAA), which is one of the variants of such an interaction, has gained importance. Despite the frequent occurrence of this pathology in the elderly, a unified approach to the treatment of these patients has not yet been developed, especially taking into account the frequent combination with other nosological forms. CAA is a disease associated with both Alzheimer's type neurodegeneration and cerebrovascular pathology. The article presents a clinical case illustrating this situation and discusses the diagnostic algorithm in detail. The characteristics of the pathogenesis and clinical manifestations of CAA and the link between neurodegenerative and cerebrovascular pathologies are discussed.

Association between systolic blood pressure variability and severity of cerebral amyloid angiopathy in incident intracerebral hemorrhage

IntroductionThe role of systolic blood pressure (SBP) variability in the pathogenesis of cerebral amyloid angiopathy (CAA) as an underlying cause of intracerebral hemorrhage (ICH) is unknown. We studied SBP variability before ICH according to CAA severity at autopsy.MethodsWe collected office (primary care or hospital clinic) BP readings during 10 years before first-ever ICH onset in adults who died and had brain research autopsy in the Lothian IntraCerebral Hemorrhage, Pathology, Imaging, and Neurological Outcome (LINCHPIN), prospective, population-based, inception cohort study. A neuropathologist assessed CAA severity using a histopathological rating scale, masked to BP readings. Functional principal component analysis was used to model SBP levels by time before ICH, and logistic regression models assessed associations of SBP variability indices with CAA severity (moderate-severe vs. absent-mild) adjusted for age, gender, and mean SBP.ResultsAmong 72 adults (median age 81 [interquartile range 76–86], 56% female, median number of SBP readings 11 [3–19]), patients with moderate-severe CAA had similar mean SBP (143 vs. 145 mmHg, P = 0.588) but lower SBP variability (SBP standard deviation [SD] 14 vs. 17 mmHg, P = 0.033) compared with patients with absent-mild CAA, and their SBP trajectories seemed to differ over 10 years before ICH. The odds of moderate-severe CAA were higher with lower maximum SBP (adjusted OR per 10 mmHg lower: 1.53, 95% confidence interval [CI] 1.09–2.15; P = 0.015) and lower SBP range (1.29 [1.03–1.61]; P = 0.028), but not SBP SD (1.95 [0.87–4.38]; P = 0.11).DiscussionCompared with absent-mild autopsy-verified CAA, moderate-severe CAA is associated with lower maximum and range of pre-morbid SBP.

Inhibitor of DNA Binding Protein 3 (ID3) and Nuclear Respiratory Factor 1 (NRF1) Mediated Transcriptional Gene Signatures are Associated with the Severity of Cerebral Amyloid Angiopathy.

Cerebral amyloid angiopathy (CAA) is a degenerative vasculopathy. We have previously shown that transcription regulating proteins- inhibitor of DNA binding protein 3 (ID3) and the nuclear respiratory factor 1 (NRF1) contribute to vascular dysregulation. In this study, we have identified sex specific ID3 and NRF1-mediated gene networks in CAA patients diagnosed with Alzheimer's Disease (AD). High expression of ID3 mRNA coupled with low NRF1 mRNA levels was observed in the temporal cortex of men and women CAA patients. Low NRF1 mRNA expression in the temporal cortex was found in men with severe CAA. High ID3 expression was found in women with the genetic risk factor APOE4. Low NRF1 expression was also associated with APOE4 in women with CAA. Genome wide transcriptional activity of both ID3 and NRF1 paralleled their mRNA expression levels. Sex specific differences in transcriptional gene signatures of both ID3 and NRF1 were observed. These findings were further corroborated by Bayesian machine learning and the GeNIe simulation models. Dynamic machine learning using a Monte Carlo Markov Chain (MCMC) gene ordering approach revealed that ID3 was associated with disease severity in women. NRF1 was associated with CAA and severity of this disease in men. These findings suggest that aberrant ID3 and NRF1 activity presumably plays a major role in the pathogenesis and severity of CAA. Further analyses of ID3- and NRF1-regulated molecular drivers of CAA may provide new targets for personalized medicine and/or prevention strategies against CAA.

Advances in Amyloid-β Clearance in the Brain and Periphery: Implications for Neurodegenerative Diseases.

This review examines the role of impaired amyloid-β clearance in the accumulation of amyloid-β in the brain and the periphery, which is closely associated with Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA). The molecular mechanism underlying amyloid-β accumulation is largely unknown, but recent evidence suggests that impaired amyloid-β clearance plays a critical role in its accumulation. The review provides an overview of recent research and proposes strategies for efficient amyloid-β clearance in both the brain and periphery. The clearance of amyloid-β can occur through enzymatic or non-enzymatic pathways in the brain, including neuronal and glial cells, blood-brain barrier, interstitial fluid bulk flow, perivascular drainage, and cerebrospinal fluid absorption-mediated pathways. In the periphery, various mechanisms, including peripheral organs, immunomodulation/immune cells, enzymes, amyloid-β-binding proteins, and amyloid-β-binding cells, are involved in amyloid-β clearance. Although recent findings have shed light on amyloid-β clearance in both regions, opportunities remain in areas where limited data is available. Therefore, future strategies that enhance amyloid-β clearance in the brain and/or periphery, either through central or peripheral clearance approaches or in combination, are highly encouraged. These strategies will provide new insight into the disease pathogenesis at the molecular level and explore new targets for inhibiting amyloid-β deposition, which is central to the pathogenesis of sporadic AD (amyloid-β in parenchyma) and CAA (amyloid-β in blood vessels).

Pathogenesis of cerebral amyloid angiopathy caused by chaotic glymphatics-Mini-review.

Cerebral amyloid angiopathy (CAA) is a common cause of lobar intracerebral hemorrhage in the elderly. It is also associated pathologically with Alzheimer's disease (AD). Both CAA and AD share similar pathology of deposition amyloid beta fibrils (Aβ). Aβ is deposited mainly in the neurites in AD and vascular walls in CAA. Aβ is formed inside the brain parenchyma from the amyloid precursor protein. It is easier to understand how Aβ is deposited in the cerebral neurites in AD. However, the pathogenesis of CAA is still largely unknown. It is difficult to understand or visualize how Aβ fibrils formed inside the brain can be deposited against the cerebral perfusion pressure to be deposited in the cerebral and meningeal arterial walls. We encountered an unusual clinical case of acute aneurysmal subarachnoid hemorrhage which was followed after a few years with localized CAA involving mainly the sites of the subarachnoid hemorrhage. We reviewed the formation of Aβ and postulated how the Aβ fibrils are transported retrogradely toward the cerebral arteries and deposited in the arterial walls resulting in the final pathology of CAA. There is a clear disturbance of the glymphatic system, the aquaporin-4 channel, and the parenchymal border macrophages.

Mitochondrial calcium uptake 3 mitigates cerebral amyloid angiopathy-related neuronal death and glial inflammation by reducing mitochondrial dysfunction.

Cerebral amyloid angiopathy (CAA) is characterized by the cerebrovascular amyloid-β (Aβ) accumulation, and always accompanied by Alzheimer's disease (AD). Mitochondrial dysfunction-associated cellular events including cell death, inflammation and oxidative stress are implicated in the progression of CAA. Unfortunately, the molecular mechanisms revealing CAA pathogenesis are still obscure, thus requiring further studies. Mitochondrial calcium uptake 3 (MICU3), a regulator of the mitochondrial Ca2+ uniporter (MCU), mediates various biological functions, but its expression and influence on CAA are largely unknown. In the present study, we found that MICU3 expression was gradually declined in cortex and hippocampus of Tg-SwDI transgenic mice. Using stereotaxic operation with AAV9 encoding MICU3, we showed that AAV-MICU3 improved the behavioral performances and cerebral blood flow (CBF) in Tg-SwDI mice, along with markedly reduced Aβ deposition through mediating Aβ metabolism process. Importantly, we found that AAV-MICU3 remarkably improved neuronal death and mitigated glial activation and neuroinflammation in cortex and hippocampus of Tg-SwDI mice. Furthermore, excessive oxidative stress, mitochondrial impairment and dysfunction, decreased ATP and mitochondrial DNA (mtDNA) were detected in Tg-SwDI mice, while being considerably ameliorated upon MICU3 over-expression. More importantly, our in vitro experiments suggested that MICU3-attenuated neuronal death, activation of glial cells and oxidative stress were completely abrogated upon PTEN induced putative kinase 1 (PINK1) knockdown, indicating that PINK1 was required for MICU3 to perform its protective effects against CAA. Mechanistic experiment confirmed an interaction between MICU3 and PINK1. Together, these findings demonstrated that MICU3-PINK1 axis may serve as a key target for CAA treatment mainly through improving mitochondrial dysfunction.

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-β (Aβ) 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 Aβ 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 Aβ1-40 and Aβ1-42 burden in cortex and hippocampus of Tg-SwDI mice through regulating Aβ metabolism process. Congo red staining confirmed Aβ 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 Aβ deposition, inflammation and neuron death via suppressing VEGF/VEGFR-1,-2 signaling.

Chronic Treatment Study Using Class C CpG ODN in Aged Non‐Human Primate Model of Sporadic CAA (Saimiri boliviensis boliviensis).

AbstractBackgroundTherapeutics that target innate immunity present promising avenues for the treatment of Alzheimer’s disease (AD) neuropathology. Our recently published study using squirrel monkeys (SQMs), a non‐human primate model of sporadic AD with extensive cerebral amyloid angiopathy (CAA), demonstrated that treatment with TLR9 agonist, Class B CpG ODN, safely reduces cognitive deficits and pathological features including parenchymal amyloid deposits, tau pathology, and CAA. Subsequently, we initiated the first chronic treatment study using Class C CpG ODN, and demonstrated its safety and efficacy in eliciting an immune response in a geriatric SQM population. Here, we assess the efficacy of Class C CpG ODN by evaluating plasma biomarkers of neurodegeneration and cognitive status using an innovative computerized testing system.MethodGeriatric SQMs received monthly injections of Class C CpG ODN or saline. Plasma biomarkers of neurodegeneration (NfL, GFAP), neuroinflammation (YKL‐40/CHI3L1), and Aβ40/42 autoantibodies were detected longitudinally using Luminex, SIMOA, or ELISA assays. Furthermore, we have implemented an innovative, touchscreen‐based Automated Cognitive Testing System (ACTS) among socially living SQMs to monitor behavioral changes. Actical® activity monitors recorded general activity parameters (step count, activity count, energy expenditure, and intensity level).ResultPlasma levels of NfL, GFAP, and YKL‐40 were significantly increased in saline‐administered monkeys compared to CpG ODN‐treated cohort. No changes were observed in both treatment groups in general activity parameters. Longitudinal plasma hematological/biochemical parameters and Aβ40/42 IgG and IgM titers revealed no differences between treatment groups, further validating the safety of our immunomodulatory approach. Geriatric SQMs completed the ACTS SHAPE training tasks to a 95% criterion of success within 10 days and are progressing through advanced cognitive tests [Match‐to‐Sample (MTS) and Two‐Choice Discrimination]. Preliminary MTS testing revealed that CpG ODN‐treated group performed with a greater response accuracy than saline controls over the last 1000 trials. Additional biofluid biomarkers and cognitive assessments are being finalized. Longitudinal gene expression profiles (RNA‐seq and NanoString analyses) involved in CpG ODN pathways using PBMCs are underway.ConclusionOur findings enhance the translational value of the SQM model for preclinical research on AD and CAA pathogenesis, as we continue to demonstrate Class C CpG ODN’s safety and therapeutic efficacy in geriatric SQMs.

α-Enolase reduces cerebrovascular Aβ deposits by protecting Aβ amyloid formation.

Cerebral amyloid angiopathy (CAA) is characterized by cerebrovascular amyloid β (Aβ) deposits and causes dementia and cerebral hemorrhage. Although α-enolase (ENO1) was shown to possess multifunctional roles, its exact functions in CAA pathogenesis have not been determined. In this study, we focused on ENO1, a well-known glycolytic enzyme, which was previously identified via a proteomic approach as an upregulated protein in brain samples from patients with Alzheimer's disease (AD). We utilized the thioflavin T fluorescence assay and transmission electron microscopy to monitor the effects of ENO1 on amyloid formation by Aβ peptides. We also cultured murine primary cerebrovascular smooth muscle cells to determine the effects of ENO1 on Aβ cytotoxicity. To investigate the effects of ENO1 in vivo, we infused ENO1 or a vehicle control into the brains of APP23 mice, atransgenicmodelofAD/CAA, using a continuous infusion system, followed by a cognitive test and pathological and biochemical analyses. We found that novel functions of ENO1 included interacting with Aβ and inhibiting its fibril formation, disrupting Aβ fibrils, and weakening the cytotoxic effects of these fibrils via proteolytic degradation of Aβ peptide. We also demonstrated that infusion of ENO1 into APP23 mouse brains reduced cerebrovascular Aβ deposits and improved cognitive impairment. In addition, we found that enzymatically inactivated ENO1 failed to inhibit Aβ fibril formation and fibril disruption. The proteolytic activity of ENO1 may thus underlie the enzyme's cytoprotective effect and clearance of Aβ from the brain, and ENO1 may be a therapeutic target in CAA.

In Vivo Dynamic Movement of Polymerized Amyloid β in the Perivascular Space of the Cerebral Cortex in Mice.

Disposition of amyloid β (Aβ) into the perivascular space of the cerebral cortex has been recently suggested as a major source of its clearance, and its disturbance may be involved in the pathogenesis of cerebral amyloid angiopathy and Alzheimer’s disease. Here, we explored the in vivo dynamics of Aβ in the perivascular space of anesthetized mice. Live images were obtained with two-photon microscopy through a closed cranial window. Either fluorescent-dye-labeled Aβ oligomers prepared freshly or Aβ fibrils after 6 days of incubation at 37 °C were placed over the cerebral cortex. Accumulation of Aβ was observed in the localized perivascular space of the penetrating arteries and veins. Transportation of the accumulated Aβ along the vessels was slow and associated with changes in shape. Aβ oligomers were transported smoothly and separately, whereas Aβ fibrils formed a mass and moved slowly. Parenchymal accumulation of Aβ oligomers, as well as Aβ fibrils along capillaries, increased gradually. In conclusion, we confirmed Aβ transportation between the cortical surface and the deeper parenchyma through the perivascular space that may be affected by the peptide polymerization. Facilitation of Aβ excretion through the system can be a key target in treating Alzheimer’s disease.

Main features of hereditary cerebral amyloid angiopathies: A systematic review

The term Cerebral Amyloid Angiopathy (CAA) refers to a group of neurovascular disorders characterized by amyloid deposition within the walls of leptomeningeal and cortical blood vessels of the brain, with specific predilection for arterioles, and (less often) capillaries and veins. Most CAA cases in the general population are sporadic in nature, and represent primarily an age-related condition affecting individuals in the fifth decade of life and beyond. Sporadic CAA is caused by deposition of amyloid-β (Aβ), originating from proteolytic cleavage of the Amyloid Precursor Protein (APP), within the walls of cerebral small caliber vessels. However, hereditary forms of CAA have also been described, generally presenting as rare familial disorder with monogenic (predominantly autosomal dominant) inheritance patterns. Hereditary CAA forms tend to affect younger individuals, and their course and clinical progression is more severe. Studies to date primarily focused on the vascular manifestations of sporadic and hereditary CAA, chiefly symptomatic lobar Intracerebral Hemorrhage (ICH). However, in the past decade sporadic CAA has also been consistently linked to progressive neurocognitive, neurobehavioral, and neuropsychiatric symptoms. This systematic review focuses on the genetics, pathogenesis, neuroimaging, neuropathology, and clinical manifestations of hereditary CAA with specific emphasis on previously overlooked cognitive, behavioral, and psychiatric symptoms.

Current Management and Therapeutic Strategies for Cerebral Amyloid Angiopathy.

Cerebral amyloid angiopathy (CAA) is characterized by accumulation of amyloid β (Aβ) in walls of leptomeningeal vessels and cortical capillaries in the brain. The loss of integrity of these vessels caused by cerebrovascular Aβ deposits results in fragile vessels and lobar intracerebral hemorrhages. CAA also manifests with progressive cognitive impairment or transient focal neurological symptoms. Although development of therapeutics for CAA is urgently needed, the pathogenesis of CAA remains to be fully elucidated. In this review, we summarize the epidemiology, pathology, clinical and radiological features, and perspectives for future research directions in CAA therapeutics. Recent advances in mass spectrometric methodology combined with vascular isolation techniques have aided understanding of the cerebrovascular proteome. In this paper, we describe several potential key CAA-associated molecules that have been identified by proteomic analyses (apolipoprotein E, clusterin, SRPX1 (sushi repeat-containing protein X-linked 1), TIMP3 (tissue inhibitor of metalloproteinases 3), and HTRA1 (HtrA serine peptidase 1)), and their pivotal roles in Aβ cytotoxicity, Aβ fibril formation, and vessel wall remodeling. Understanding the interactions between cerebrovascular Aβ deposits and molecules that accumulate with Aβ may lead to discovery of effective CAA therapeutics and to the identification of biomarkers for early diagnosis.

Amyloid β (Aβ) ELISA of Human iPSC-Derived Neuronal Cultures.

Amyloid β (Aβ) peptides are the main component of the characteristic insoluble deposits in brain parenchyma and small blood vessels in the patients afflicted with Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA). These small peptides are attributed to the pathogenesis of both AD and CAA, suggesting an important index for disease stage and progression. In the brain tissue, Aβs are released mainly from neuronal cells into extracellular space. Here, we describe a step-by-step protocol to measure Aβs secreted from human pluripotent stem cell-derived neuronal cells.

Roles of amyloid-β in the pathogenesis of cerebral amyloid angiopathy and Alzheimer's disease should be clarified

脑淀粉样血管病和阿尔茨海默病常常共存，二者在临床表现上存在着很多相似之处，β淀粉样蛋白在这两种疾病的发病机制中都起到了关键的作用。明确Aβ的作用有助于认清疾病的本质，从而更好地把握这两种疾病不同的临床特征，更好地作出诊断和治疗。.

New Insights Into Blood-Brain Barrier Maintenance: The Homeostatic Role of β-Amyloid Precursor Protein in Cerebral Vasculature.

Cerebrovascular homeostasis is maintained by the blood-brain barrier (BBB), a highly selective structure that separates the peripheral blood circulation from the brain and protects the central nervous system (CNS). Dysregulation of BBB function is the precursor of several neurodegenerative diseases including Alzheimer’s disease (AD) and cerebral amyloid angiopathy (CAA), both related to β-amyloid (Aβ) accumulation and deposition. The origin of BBB dysfunction before and/or during CAA and AD onset is not known. Several studies raise the possibility that vascular dysfunction could be an early step in these diseases and could even precede significant Aβ deposition. Though accumulation of neuron-derived Aβ peptides is considered the primary influence driving AD and CAA pathogenesis, recent studies highlighted the importance of the physiological role of the β-amyloid precursor protein (APP) in endothelial cell homeostasis, suggesting a potential role of this protein in maintaining vascular stability. In this review, we will discuss the physiological function of APP and its cleavage products in the vascular endothelium. We further suggest how loss of APP homeostatic regulation in the brain vasculature could lead toward pathological outcomes in neurodegenerative disorders.

Platelet and Plasma Phosphatidylcholines as Biomarkers to Diagnose Cerebral Amyloid Angiopathy.

Alzheimer's disease is a severe neurodegenerative brain disorder and characterized by deposition of extracellular toxic β-amyloid (42) plaques and the formation of intracellular tau neurofibrillary tangles. In addition, β-amyloid peptide deposits are found in the walls of small to medium blood vessels termed cerebral amyloid angiopathy (CAA). However, the pathogenesis of CAA appears to differ from that of senile plaques in several aspects. The aim of the present study was to analyze different lipids [phosphatidylcholines (PCs) and lysoPCs] in platelets and plasma of a novel mouse model of sporadic CAA (1). Our data show that lipids are significantly altered in plasma of the CAA mice. Levels of eight diacyl PCs, two acyl-alkyl PCs, and five lysoPCs were significantly increased. In extracts of mouse blood platelets, four diacyl and two acyl-alkyl PCs (but not lysoPCs) were significantly altered. Our data show that lipids are changed in CAA with a specific pattern, and we provide for the first time evidence that selected platelet and plasma PCs may help to characterize CAA.

Abstract WP136: Peripheral Activation of Gut-Immune-Brain Axis in Cerebral Amyloid Angiopathy

Cerebral Amyloid Angiopathy (CAA) is an emerging cause of vascular cognitive impairment in the elderly. CAA is characterized by amyloid-β (Aβ) deposition in the central nervous system (CNS) vasculature and is associated with increased neuroinflammation. Aging is risk factor for CAA and is accompanied by low-grade inflammation and gut dysbiosis (a pathological imbalance of microbial organisms in the gut). Activation of peripheral immunity by a dysfunctional gut-immune axis may contribute to CAA progression. We hypothesize that CAA-induced gut dysbiosis leads to activation of a peripheral immune response which can accelerate CAA progression. We used the Tg-SwDI mouse (harboring Swedish, Dutch, and Iowa mutations of human amyloid precursor protein (APP), “CAA mice”) model that develops cerebral Aβ deposits and cognitive deficits around 3-4 months. We used 2mo mice as pre-onset and 10mo mice as post-onset groups. Results: Our preliminary fecal 16S rRNA sequencing data showed higher microbiome alpha- (or “within-sample”) diversity in CAA mice (n=207, Inverse-Simpson diversity score, p=0.036). Upon visualization of beta- (or “between samples”) diversity in CAA and WT animals, with weighted-UniFrac-distances by principal coordinate analysis (PCoA), we found a notable clustering by strain (34.6% and 26.4% PCoA axes, p=0.001). Immunophenotyping of liver showed significant decrease in the B:T cell ratios when comparing the pre- to post-onset CAA mice (0.53 vs. 0.19, p = 0.005). Additionally, we observed a significant increase in the relative frequency of MHC-II (high) non-myeloid cells, when comparing the pre- to post-onset CAA (11.5% vs. 41.8%, p = 0.027). Conclusion: Our findings suggest that gut dysbiosis occur early in CAA pathogenesis and may be responsible for ongoing increased peripheral and CNS inflammation. This work is significant if follow-up studies confirm that manipulation of the gut microbiota can modulate the peripheral immune response to reduce neuroinflammation in CAA and improve CAA-associated cognitive phenotype.

Amyloid angiitis and progressive cortical superficial siderosis as aggressive phenotypes of cerebral amyloid angiopathy: principles of rational management

Cerebral amyloid angiopathy (CAA) is a common disease in the older age group with high clinical and neurovisual heterogeneity. A literature review and two clinical cases reflecting different phenotypes of CAA are presented — amyloid angiitis (CAA-related inflammation) and “hemorrhagic phenotype” (CAA associated with intracerebral hemorrhage and progressive cortical superficial siderosis). In each case, in relation to the clinical and neuroimaging picture, the directions of the disputed vectors of secondary prevention and therapy of CAA are considered: antithrombotic, antihypertensive and lipid-lowering therapy. The issues of epidemiology, pathogenesis, diagnosis and treatment of CAA are discussed.