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López-Valencia L, Moya M, Escudero B, García-Bueno B, Orio L. Bacterial lipopolysaccharide forms aggregates with apolipoproteins in male and female rat brains after ethanol binges. J Lipid Res 2024; 65:100509. [PMID: 38295984 PMCID: PMC10907226 DOI: 10.1016/j.jlr.2024.100509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 01/05/2024] [Accepted: 01/11/2024] [Indexed: 03/01/2024] Open
Abstract
Alcohol binge drinking allows the translocation of bacterial lipopolysaccharide (LPS) from the gut to the blood, which activates the peripheral immune system with consequences in neuroinflammation. A possible access/direct signaling of LPS to/in the brain has not yet been described under alcohol abuse conditions. Apolipoproteins are compounds altered by alcohol with high affinity to LPS which may be involved in its transport to the brain or in its elimination. Here, we explored the expression of small components of LPS, in its free form or bound to apolipoproteins, in the brain of female and male rats exposed to alcohol binges. Animals received ethanol oral gavages (3 g/kg every 8 h) for 4 days. LPS or its components (Lipid A and core), LPS-binding protein, corticosterone, lipoproteins (HDL, LDL), apolipoproteins (ApoAI, ApoB, and ApoE), and their receptors were measured in plasma and/or in nonperfused prefrontal cortex (PFC) and cerebellum. Brain LipidA-apolipoprotein aggregates were determined by Western blotting and confirmed by co-immunoprecipitation. In animals exposed to alcohol binges: 1) plasma LPS-binding protein was elevated in both sexes; 2) females showed elevations in plasma ApoAI and corticosterone levels; 3) Lipid A formed aggregates with ApoAI in the female PFC and with ApoB in males, the latter showing Toll-like receptor 4 upregulation in PFC but not females. These results suggest that small bacterial components are present within the brain, forming aggregates with different apolipoproteins, depending on the sex, after alcohol binge intoxications. Results may have implications for the crosstalk between alcohol, LPS, and neuroinflammation.
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Affiliation(s)
- L López-Valencia
- Department of Psychobiology and Behavioral Sciences Methods, Faculty of Psychology, Complutense University of Madrid, Pozuelo de Alarcón, Spain; Instituto de Investigación Sanitaria Hospital Universitario 12 de Octubre (imas12), Neuroscience and Mental Health, Madrid, Spain
| | - M Moya
- Department of Psychobiology and Behavioral Sciences Methods, Faculty of Psychology, Complutense University of Madrid, Pozuelo de Alarcón, Spain
| | - B Escudero
- Department of Psychobiology and Behavioral Sciences Methods, Faculty of Psychology, Complutense University of Madrid, Pozuelo de Alarcón, Spain; Instituto de Investigación Sanitaria Hospital Universitario 12 de Octubre (imas12), Neuroscience and Mental Health, Madrid, Spain
| | - B García-Bueno
- Instituto de Investigación Sanitaria Hospital Universitario 12 de Octubre (imas12), Neuroscience and Mental Health, Madrid, Spain; Department of Pharmacology and Toxicology, Faculty of Medicine, Complutense University of Madrid (UCM), Neurochemistry Research Institute UCM (IUIN), Madrid, Spain; Biomedical Network Research Center of Mental Health (CIBERSAM), Institute of Health Carlos III, Madrid, Spain
| | - L Orio
- Department of Psychobiology and Behavioral Sciences Methods, Faculty of Psychology, Complutense University of Madrid, Pozuelo de Alarcón, Spain; Instituto de Investigación Sanitaria Hospital Universitario 12 de Octubre (imas12), Neuroscience and Mental Health, Madrid, Spain; RIAPAd: Research network in primary care in addictions ('Red de investigación en atención primaria en adicciones'), Spain.
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2
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Sharif A, Mamo J, Lam V, Al-Salami H, Mooranian A, Watts GF, Clarnette R, Luna G, Takechi R. The therapeutic potential of probucol and probucol analogues in neurodegenerative diseases. Transl Neurodegener 2024; 13:6. [PMID: 38247000 PMCID: PMC10802046 DOI: 10.1186/s40035-024-00398-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 01/07/2024] [Indexed: 01/23/2024] Open
Abstract
Neurodegenerative disorders present complex pathologies characterized by various interconnected factors, including the aggregation of misfolded proteins, oxidative stress, neuroinflammation and compromised blood-brain barrier (BBB) integrity. Addressing such multifaceted pathways necessitates the development of multi-target therapeutic strategies. Emerging research indicates that probucol, a historic lipid-lowering medication, offers substantial potential in the realm of neurodegenerative disease prevention and treatment. Preclinical investigations have unveiled multifaceted cellular effects of probucol, showcasing its remarkable antioxidative and anti-inflammatory properties, its ability to fortify the BBB and its direct influence on neural preservation and adaptability. These diverse effects collectively translate into enhancements in both motor and cognitive functions. This review provides a comprehensive overview of recent findings highlighting the efficacy of probucol and probucol-related compounds in the context of various neurodegenerative conditions, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and cognitive impairment associated with diabetes.
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Affiliation(s)
- Arazu Sharif
- Curtin Health Innovation Research Institute, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
| | - John Mamo
- Curtin Health Innovation Research Institute, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
- Perron Institute for Neurological and Translational Research, Perth, WA, Australia
| | - Virginie Lam
- Curtin Health Innovation Research Institute, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
| | - Hani Al-Salami
- Curtin Health Innovation Research Institute, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
| | - Armin Mooranian
- Curtin Health Innovation Research Institute, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
| | - Gerald F Watts
- School of Medicine, Faculty of Health and Medical Sciences, University of Western Australia, Perth, WA, Australia
| | - Roger Clarnette
- School of Medicine, Faculty of Health and Medical Sciences, University of Western Australia, Perth, WA, Australia
| | - Giuseppe Luna
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, WA, Australia
| | - Ryu Takechi
- Curtin Health Innovation Research Institute, Faculty of Health Sciences, Curtin University, Perth, WA, Australia.
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth, WA, Australia.
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3
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Espinosa JM, Quintero-Flórez A, Carrasquilla N, Montero E, Rodríguez-Rodríguez A, Castellano JM, Perona JS. Bioactive compounds in pomace olive oil modulate the inflammatory response elicited by postprandial triglyceride-rich lipoproteins in BV-2 cells. Food Funct 2023; 14:8987-8999. [PMID: 37740318 DOI: 10.1039/d3fo02460a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
Modulation of microglial response could be a target to reduce neuroinflammation associated with Alzheimer's disease. In this study, we propose that lipophilic bioactive molecules present in pomace olive oil (POO), transported in triglyceride-rich lipoproteins (TRLs), are able to modulate microglial high-oleic sunflower oil (HOSO, points) or pomace olive oil (POO, stripes). In order to prove this hypothesis, a randomized crossover postprandial trial was performed in 18 healthy young women. POO was assayed in opposition to high-oleic sunflower oil (HOSO), a common dietary oil which shares with POO an almost identical fatty acid composition but lacks certain biomolecules with recognized antioxidant and anti-inflammatory activities. TRLs were isolated from blood at the baseline and 2 and 4 hours postprandially and used to treat BV-2 cells to assess their ability to modulate the microglial function. We found that the intake of POO leads to the constitution of postprandial TRLs that are able to modulate the inflammatory response in microglia compared to HOSO. TRL-derived POO reduced the release of pro-inflammatory cytokines (tumor necrosis factor-α, and interleukins 1β and 6) and nitric oxide and downregulated genes codifying for these cytokines and inducible nitric oxide synthase (iNOS) in BV-2 cells. Moreover, the ingestion of POO by healthy women slightly improved glycemic control and TRL clearance throughout the postprandial phase compared to HOSO. In conclusion, we demonstrated that consuming POO results in postprandial TRLs containing lipophilic bioactive compounds capable of regulating the inflammatory response prompted by microglial activation.
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Affiliation(s)
- Juan Manuel Espinosa
- Instituto de la Grasa, Department of Food and Health, Spanish National Research Council (CSIC), Campus University Pablo de Olavide, 41013, Seville, Spain.
| | | | - Natalia Carrasquilla
- Instituto de la Grasa, Department of Food and Health, Spanish National Research Council (CSIC), Campus University Pablo de Olavide, 41013, Seville, Spain.
| | - Emilio Montero
- University Hospital Virgen del Rocío, Andalusian Regional Health Service, Seville, Spain
| | | | - José María Castellano
- Instituto de la Grasa, Department of Food and Health, Spanish National Research Council (CSIC), Campus University Pablo de Olavide, 41013, Seville, Spain.
| | - Javier S Perona
- Instituto de la Grasa, Department of Food and Health, Spanish National Research Council (CSIC), Campus University Pablo de Olavide, 41013, Seville, Spain.
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Rudge JD. The Lipid Invasion Model: Growing Evidence for This New Explanation of Alzheimer's Disease. J Alzheimers Dis 2023:JAD221175. [PMID: 37302030 PMCID: PMC10357195 DOI: 10.3233/jad-221175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The Lipid Invasion Model (LIM) is a new hypothesis for Alzheimer's disease (AD) which argues that AD is a result of external lipid invasion to the brain, following damage to the blood-brain barrier (BBB). The LIM provides a comprehensive explanation of the observed neuropathologies associated with the disease, including the lipid irregularities first described by Alois Alzheimer himself, and accounts for the wide range of risk factors now identified with AD, all of which are also associated with damage to the BBB. This article summarizes the main arguments of the LIM, and new evidence and arguments in support of it. The LIM incorporates and extends the amyloid hypothesis, the current main explanation of the disease, but argues that the greatest cause of late-onset AD is not amyloid-β (Aβ) but bad cholesterol and free fatty acids, let into the brain by a damaged BBB. It suggests that the focus on Aβ is the reason why we have made so little progress in treating the disease in the last 30 years. As well as offering new perspectives for further research into the diagnosis, prevention, and treatment of AD, based on protecting and repairing the BBB, the LIM provides potential new insights into other neurodegenerative diseases such as Parkinson's disease and amyotrophic lateral sclerosis/motor neuron disease.
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Espinosa JM, Castellano JM, Garcia-Rodriguez S, Quintero-Flórez A, Carrasquilla N, Perona JS. Lipophilic Bioactive Compounds Transported in Triglyceride-Rich Lipoproteins Modulate Microglial Inflammatory Response. Int J Mol Sci 2022; 23:ijms23147706. [PMID: 35887052 PMCID: PMC9321013 DOI: 10.3390/ijms23147706] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/30/2022] [Accepted: 07/09/2022] [Indexed: 11/16/2022] Open
Abstract
Microglial cells can contribute to Alzheimer’s disease by triggering an inflammatory response that leads to neuronal death. In addition, the presence of amyloid-β in the brain is consistent with alterations in the blood–brain barrier integrity and triglyceride-rich lipoproteins (TRL) permeation. In the present work, we used lab-made TRL as carriers of lipophilic bioactive compounds that are commonly present in dietary oils, namely oleanolic acid (OA), α-tocopherol (AT) and β-sitosterol (BS), to assess their ability to modulate the inflammatory response of microglial BV-2 cells. We show that treatment with lab-made TRL increases the release and gene-expression of IL-1β, IL-6, and TNF-α, as well as NO and iNOS in microglia. On the other hand, TRL revealed bioactive compounds α-tocopherol and β-sitosterol as suitable carriers for oleanolic acid. The inclusion of these biomolecules in TRL reduced the release of proinflammatory cytokines. The inclusion of these biomolecules in TRL reduced the release of proinflammatory cytokines. AT reduced IL-6 release by 72%, OA reduced TNF-α release by approximately 50%, and all three biomolecules together (M) reduced IL-1β release by 35% and TNF-α release by more than 70%. In addition, NO generation was reduced, with the inclusion of OA by 45%, BS by 80% and the presence of M by 88%. Finally, a recovery of the basal glutathione content was observed with the inclusion of OA and M in the TRL. Our results open the way to exploiting the neuro-pharmacological potential of these lipophilic bioactive compounds through their delivery to the brain as part of TRL.
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6
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Rudge JD. A New Hypothesis for Alzheimer's Disease: The Lipid Invasion Model. J Alzheimers Dis Rep 2022; 6:129-161. [PMID: 35530118 PMCID: PMC9028744 DOI: 10.3233/adr-210299] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/05/2022] [Indexed: 02/07/2023] Open
Abstract
This paper proposes a new hypothesis for Alzheimer's disease (AD)-the lipid invasion model. It argues that AD results from external influx of free fatty acids (FFAs) and lipid-rich lipoproteins into the brain, following disruption of the blood-brain barrier (BBB). The lipid invasion model explains how the influx of albumin-bound FFAs via a disrupted BBB induces bioenergetic changes and oxidative stress, stimulates microglia-driven neuroinflammation, and causes anterograde amnesia. It also explains how the influx of external lipoproteins, which are much larger and more lipid-rich, especially more cholesterol-rich, than those normally present in the brain, causes endosomal-lysosomal abnormalities and overproduction of the peptide amyloid-β (Aβ). This leads to the formation of amyloid plaques and neurofibrillary tangles, the most well-known hallmarks of AD. The lipid invasion model argues that a key role of the BBB is protecting the brain from external lipid access. It shows how the BBB can be damaged by excess Aβ, as well as by most other known risk factors for AD, including aging, apolipoprotein E4 (APOE4), and lifestyle factors such as hypertension, smoking, obesity, diabetes, chronic sleep deprivation, stress, and head injury. The lipid invasion model gives a new rationale for what we already know about AD, explaining its many associated risk factors and neuropathologies, including some that are less well-accounted for in other explanations of AD. It offers new insights and suggests new ways to prevent, detect, and treat this destructive disease and potentially other neurodegenerative diseases.
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Affiliation(s)
- Jonathan D’Arcy Rudge
- School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom
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Huang SY, Yang YX, Zhang YR, Kuo K, Li HQ, Shen XN, Chen SD, Chen KL, Dong Q, Tan L, Yu JT. Investigating Causal Relations Between Circulating Metabolites and Alzheimer's Disease: A Mendelian Randomization Study. J Alzheimers Dis 2022; 87:463-477. [PMID: 35275550 DOI: 10.3233/jad-220050] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Metabolomics is a promising approach that can be used to understand pathophysiological pathways of Alzheimer's disease (AD). However, the causal relationships between metabolism and AD are poorly understood. OBJECTIVE We aimed to investigate the causal association between circulating metabolites and risk of AD through two-sample Mendelian randomization (MR) approach. METHODS Genetic associations with 123 circulating metabolic traits were utilized as exposures. Summary statistics data from International Genomics of Alzheimer's Project was used in primary analysis, including 21,982 AD cases and 41,944 controls. Validation was performed using family history of AD data from UK Biobank (27,696 cases of maternal AD, 14,338 cases of paternal AD, and 272,244 controls). We utilized inverse-variance weighted method as primary method. RESULTS We found significantly increased risks of developing AD per standard deviation increase in the levels of circulating ApoB (odd ratio[OR] = 3.18; 95% confidence interval[CI]: 1.52-6.66, p = 0.0022), glycoprotein acetyls (OR = 1.21; 95% CI: 1.05-1.39, p = 0.0093), total cholesterol (OR = 2.73; 95% CI: 1.41-5.30, p = 0.0030), and low-density lipoprotein (LDL) cholesterol (OR = 2.34; 95% CI: 1.53-3.57, p = 0.0001). Whereas glutamine (OR = 0.81; 95% CI: 0.71-0.92, p = 0.0011) were significantly associated with lower risk of AD. We also detected causal effects of several different composition of LDL fractions on increased AD risk, which has been verified in validation. However, we found no association between circulating high-density lipoprotein cholesterol and AD. CONCLUSION Our findings suggest causal effects of circulating glycoprotein acetyls, ApoB, LDL cholesterol, and serum total cholesterol on higher risk of AD, whereas glutamine showed the protective effect.
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Affiliation(s)
- Shu-Yi Huang
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Yu-Xiang Yang
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Ya-Ru Zhang
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Kevin Kuo
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Hong-Qi Li
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Xue-Ning Shen
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Shi-Dong Chen
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Ke-Liang Chen
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Qiang Dong
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
| | - Lan Tan
- Department of Neurology, Qingdao Municipal Hospital, Qingdao University, China
| | - Jin-Tai Yu
- Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, China
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8
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Synthesis of human amyloid restricted to liver results in an Alzheimer disease-like neurodegenerative phenotype. PLoS Biol 2021; 19:e3001358. [PMID: 34520451 PMCID: PMC8439475 DOI: 10.1371/journal.pbio.3001358] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 07/08/2021] [Indexed: 02/07/2023] Open
Abstract
Several lines of study suggest that peripheral metabolism of amyloid beta (Aß) is associated with risk for Alzheimer disease (AD). In blood, greater than 90% of Aß is complexed as an apolipoprotein, raising the possibility of a lipoprotein-mediated axis for AD risk. In this study, we report that genetic modification of C57BL/6J mice engineered to synthesise human Aß only in liver (hepatocyte-specific human amyloid (HSHA) strain) has marked neurodegeneration concomitant with capillary dysfunction, parenchymal extravasation of lipoprotein-Aß, and neurovascular inflammation. Moreover, the HSHA mice showed impaired performance in the passive avoidance test, suggesting impairment in hippocampal-dependent learning. Transmission electron microscopy shows marked neurovascular disruption in HSHA mice. This study provides causal evidence of a lipoprotein-Aß /capillary axis for onset and progression of a neurodegenerative process. It has been suggested that peripheral metabolism of amyloid-beta is associated with risk for Alzheimer’s disease. This study reveals that the expression of human amyloid exclusively in the liver induces Alzheimer’s disease-like pathologies in mice, potentially indicating a completely novel pathway of Alzheimer’s disease aetiology and therapies.
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9
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Pickering J, Wong R, Al-Salami H, Lam V, Takechi R. Cognitive Deficits in Type-1 Diabetes: Aspects of Glucose, Cerebrovascular and Amyloid Involvement. Pharm Res 2021; 38:1477-1484. [PMID: 34480263 DOI: 10.1007/s11095-021-03100-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 08/24/2021] [Indexed: 11/28/2022]
Abstract
The evidence shows that individuals with type-1 diabetes mellitus (T1DM) are at greater risk of accelerated cognitive impairment and dementia. Although, to date the mechanisms are largely unknown. An emerging body of literature indicates that dysfunction of cerebral neurovascular network and plasma dyshomeostasis of soluble amyloid-β in association with impaired lipid metabolism are central to the onset and progression of cognitive deficits and dementia. However, the latter has not been extensively considered in T1DM. Therefore, in this review, we summarised the literature concerning altered lipid metabolism and cerebrovascular function in T1DM as an implication for potential pathways leading to cognitive decline and dementia.
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Affiliation(s)
- Justin Pickering
- School of Population Health, Faculty of Health Sciences, Curtin University, Perth, WA, 6845, Australia
| | - Rachel Wong
- Institute for Resilient Regions, University of Southern Queensland, Springfield Central, QLD, 4300, Australia
| | - Hani Al-Salami
- Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, WA, 6845, Australia.,Curtin Health Innovation Research Institute, Curtin University, Perth, WA, 6845, Australia
| | - Virginie Lam
- School of Population Health, Faculty of Health Sciences, Curtin University, Perth, WA, 6845, Australia.,Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, WA, 6845, Australia
| | - Ryu Takechi
- School of Population Health, Faculty of Health Sciences, Curtin University, Perth, WA, 6845, Australia. .,Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, WA, 6845, Australia.
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10
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Tóth ME, Dukay B, Hoyk Z, Sántha M. Cerebrovascular Changes and Neurodegeneration Related to Hyperlipidemia: Characteristics of the Human ApoB-100 Transgenic Mice. Curr Pharm Des 2020; 26:1486-1494. [PMID: 32067608 PMCID: PMC7403644 DOI: 10.2174/1381612826666200218101818] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 11/27/2019] [Indexed: 01/07/2023]
Abstract
Serum lipid levels are closely related to the structure and function of blood vessels. Chronic hyperlipidemia may lead to damage in both the cardio- and the cerebrovascular systems. Vascular dysfunctions, including impairments of the blood-brain barrier, are known to be associated with neurodegenerative diseases. A growing number of evidence suggests that cardiovascular risk factors, such as hyperlipidemia, may increase the likelihood of developing dementia. Due to differences in lipoprotein metabolism, wild-type mice are protected against diet-induced hypercholesterolemia, and their serum lipid profile is different from that observed in humans. Therefore, several transgenic mouse models have been established to study the role of different apolipoproteins and their receptors in lipid metabolism, as well as the complications related to pathological lipoprotein levels. This mini-review focused on a transgenic mouse model overexpressing an apolipoprotein, the human ApoB-100. We discussed literature data and current advancements on the understanding of ApoB-100 induced cardio- and cerebrovascular lesions in order to demonstrate the involvement of this type of apolipoprotein in a wide range of pathologies, and a link between hyperlipidemia and neurodegeneration.
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Affiliation(s)
- Melinda E Tóth
- Institute of Biochemistry, Biological Research Centre, Sezeged, Hungary
| | - Brigitta Dukay
- Institute of Biochemistry, Biological Research Centre, Sezeged, Hungary.,Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Zsófia Hoyk
- Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Temesvári krt. 62., Hungary
| | - Miklós Sántha
- Institute of Biochemistry, Biological Research Centre, Sezeged, Hungary
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11
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Rawlings S, Takechi R, Lavender AP. Effects of sub-concussion on neuropsychological performance and its potential mechanisms: A narrative review. Brain Res Bull 2020; 165:56-62. [PMID: 33011196 DOI: 10.1016/j.brainresbull.2020.09.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/12/2020] [Accepted: 09/25/2020] [Indexed: 12/12/2022]
Abstract
Concussion and mild traumatic brain injury (mTBI) are recognised as serious medical events that are relatively common in contact sports. Recently, the seemingly non-injurious phenomenon of sub-concussion has gained interest among neuroscience researchers and early studies are showing that there may be some acute and chronic effects on brain health and function with repeated sub-concussive events of the type seen in soccer, where players strike the ball with the head, and collision sports like the rugby codes. The aim of this narrative review is to describe sub-concussion and the current understanding of short and long term effects of repeated minor impacts that have been found to occur in human and animal models. Here, potential mechanisms for cognitive dysfunction following sub-concussion and recommend directions for future research are discussed. The Potential mechanisms of injuries resulting from sub-concussion such as changes in blood brain barrier integrity, neuroinflammation, cognitive impairment, and oxidative stress damage, among other changes in central nervous system function vary considerably making understanding of the underlying causative mechanism challenging for researchers. Some evidence suggests a link between impaired cerebrovascular function and cognitive impairment which poses a potential mechanism linking the two. It is hoped that this review helps guide researchers toward a potential direction of investigations.
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Affiliation(s)
- Samuel Rawlings
- School of Physiotherapy and Exercise Science, Faculty of Health Sciences, Curtin University, Perth, Australia
| | - Ryusuke Takechi
- Curtin Health Innovation Research Institute, Curtin University, Perth, Australia; School of Public Health, Faculty of Health Sciences, Curtin University, Perth, Australia
| | - Andrew P Lavender
- School of Physiotherapy and Exercise Science, Faculty of Health Sciences, Curtin University, Perth, Australia; School of Science, Psychology and Sport, Federation University Australia, Ballarat, Australia.
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12
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Hui L, Soliman ML, Geiger NH, Miller NM, Afghah Z, Lakpa KL, Chen X, Geiger JD. Acidifying Endolysosomes Prevented Low-Density Lipoprotein-Induced Amyloidogenesis. J Alzheimers Dis 2020; 67:393-410. [PMID: 30594929 DOI: 10.3233/jad-180941] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cholesterol dyshomeostasis has been linked to the pathogenesis of sporadic Alzheimer's disease (AD). In furthering the understanding of mechanisms by which increased levels of circulating cholesterol augments the risk of developing sporadic AD, others and we have reported that low-density lipoprotein (LDL) enters brain parenchyma by disrupting the blood-brain barrier and that endolysosome de-acidification plays a role in LDL-induced amyloidogenesis in neurons. Here, we tested the hypothesis that endolysosome de-acidification was central to amyloid-β (Aβ) generation and that acidifying endolysosomes protects against LDL-induced increases in Aβ levels in neurons. We demonstrated that LDL, but not HDL, de-acidified endolysosomes and increased intraneuronal and secreted levels of Aβ. ML-SA1, an agonist of endolysosome-resident TRPML1 channels, acidified endolysosomes, and TRPML1 knockdown attenuated ML-SA1-induced endolysosome acidification. ML-SA1 blocked LDL-induced increases in intraneuronal and secreted levels of Aβ as well as Aβ accumulation in endolysosomes, prevented BACE1 accumulation in endolysosomes, and decreased BACE1 activity levels. LDL downregulated TRPML1 protein levels, and TRPML1 knockdown worsens LDL-induced increases in Aβ. Our findings suggest that endolysosome acidification by activating TRPML1 may represent a protective strategy against sporadic AD.
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Affiliation(s)
- Liang Hui
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Mahmoud L Soliman
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Nicholas H Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Nicole M Miller
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Zahra Afghah
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Koffi L Lakpa
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Xuesong Chen
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Jonathan D Geiger
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
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13
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Galloway S, Takechi R, Nesbit M, Pallebage-Gamarallage MM, Lam V, Mamo JCL. The differential effects of fatty acids on enterocytic abundance of amyloid-beta. Lipids Health Dis 2019; 18:209. [PMID: 31796080 PMCID: PMC6889564 DOI: 10.1186/s12944-019-1162-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/29/2019] [Indexed: 12/30/2022] Open
Abstract
Background Consumption of a Western-styled diet enriched in saturated fatty acids (SFA) relative to polyunsaturated fatty acids is positively associated with risk for Alzheimer’s disease. Whilst potential causal mechanism are unclear, there is increasing evidence that chronic ingestion of SFA enriched diets promote increase the plasma levels of lipoprotein-associated amyloid-β (Aβ). However, the effects of dietary mono- and poly-unsaturated fats (MUFA/PUFA) on nascent lipoprotein Aβ abundance have not been previously reported. Methods Wild-type C57BL/6 J mice were maintained on low-fat control chow (LF) or diets enriched in either SFA, MUFA, or PUFA for 9 months. Enterocytic abundance of Aβ was determined with quantitative immunofluorescent microscopy and plasma Aβ was measured by ELISA. Results The chronic ingestion of SFA-enriched diet increased the enterocytic abundance and plasma concentration of Aβ compared to LF control mice. The mice maintained on MUFA or PUFA diet showed comparable enterocytic and plasma Aβ levels to the LF control mice. Conclusions The data indicates that a diet enriched in SFA significantly increases the enterocytic Aβ production and secretion into the circulation, whilst MUFA and PUFA enriched diet do not exert such effects.
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Affiliation(s)
- Susan Galloway
- Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.,School of Public Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
| | - Ryusuke Takechi
- Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia. .,School of Public Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.
| | - Michael Nesbit
- Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.,School of Public Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
| | - Menuka M Pallebage-Gamarallage
- Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.,School of Public Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
| | - Virginie Lam
- Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.,School of Public Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
| | - John C L Mamo
- Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.,School of Public Health, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
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14
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D'Argenio V, Sarnataro D. Microbiome Influence in the Pathogenesis of Prion and Alzheimer's Diseases. Int J Mol Sci 2019; 20:E4704. [PMID: 31547531 PMCID: PMC6801937 DOI: 10.3390/ijms20194704] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/20/2019] [Accepted: 09/21/2019] [Indexed: 12/14/2022] Open
Abstract
Misfolded and abnormal β-sheets forms of wild-type proteins, such as cellular prion protein (PrPC) and amyloid beta (Aβ), are believed to be the vectors of neurodegenerative diseases, prion and Alzheimer's disease (AD), respectively. Increasing evidence highlights the "prion-like" seeding of protein aggregates as a mechanism for pathological spread in AD, tauopathy, as well as in other neurodegenerative diseases, such as Parkinson's. Mutations in both PrPC and Aβ precursor protein (APP), have been associated with the pathogenesis of these fatal disorders with clear evidence for their pathogenic significance. In addition, a critical role for the gut microbiota is emerging; indeed, as a consequence of gut-brain axis alterations, the gut microbiota has been involved in the regulation of Aβ production in AD and, through the microglial inflammation, in the amyloid fibril formation, in prion diseases. Here, we aim to review the role of microbiome ("the other human genome") alterations in AD and prion disease pathogenesis.
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Affiliation(s)
- Valeria D'Argenio
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, via Pansini 5, 80131 Naples, Italy.
- CEINGE-Biotecnologie Avanzate, via G. Salvatore 486, 80145 Naples, Italy.
- Task Force on Microbiome Studies, University of Naples Federico II, 80131 Naples, Italy.
| | - Daniela Sarnataro
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, via Pansini 5, 80131 Naples, Italy.
- CEINGE-Biotecnologie Avanzate, via G. Salvatore 486, 80145 Naples, Italy.
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15
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Spielman LJ, Gibson DL, Klegeris A. Unhealthy gut, unhealthy brain: The role of the intestinal microbiota in neurodegenerative diseases. Neurochem Int 2018; 120:149-163. [PMID: 30114473 DOI: 10.1016/j.neuint.2018.08.005] [Citation(s) in RCA: 173] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/09/2018] [Accepted: 08/13/2018] [Indexed: 02/08/2023]
Abstract
The number of bacterial cells living within the human body is approximately equal to, or greater than, the total number of human cells. This dynamic population of microorganisms, termed the human microbiota, resides mainly within the gastrointestinal tract. It is widely accepted that highly diverse and stable microbiota promote overall human health. Colonization of the gut with maladaptive and pathogenic microbiota, a state also known as dysbiosis, is associated with a variety of peripheral diseases ranging from type 2 diabetes mellitus to cardiovascular and inflammatory bowel disease. More recently, microbial dysbiosis has been associated with a number of brain pathologies, including autism spectrum disorder, Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), suggesting a direct or indirect communication between intestinal bacteria and the central nervous system (CNS). In this review, we illustrate two pathways implicated in the crosstalk between gut microbiota and CNS involving 1) the vagus nerve and 2) transmission of signaling molecules through the circulatory system and across the blood-brain barrier (BBB). We summarize the available evidence of the specific changes in the intestinal microbiota, as well as microorganism-induced modifications to intestinal and BBB permeability, which have been linked to several neurodegenerative disorders including ALS, AD, and PD. Even though each of these diseases arises from unique pathogenetic mechanisms, all are characterized, at least in part, by chronic neuroinflammation. We provide an interpretation for the substantial evidence that healthy intestinal microbiota have the ability to positively regulate the neuroimmune responses in the CNS. Even though the evidence is mainly associative, it has been suggested that bacterial dysbiosis could contribute to an adverse neuroinflammatory state leading to increased risk of neurodegenerative diseases. Thus, developing strategies for regulating and maintaining healthy intestinal microbiota could be a valid approach for lowering individual risk and prevalence of neurodegenerative diseases.
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Affiliation(s)
| | - Deanna Lynn Gibson
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, Canada
| | - Andis Klegeris
- Department of Biology, University of British Columbia Okanagan Campus, Kelowna, Canada
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16
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Electronegative Low-Density Lipoprotein L5 Impairs Viability and NGF-Induced Neuronal Differentiation of PC12 Cells via LOX-1. Int J Mol Sci 2017; 18:ijms18081744. [PMID: 28800073 PMCID: PMC5578134 DOI: 10.3390/ijms18081744] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 08/05/2017] [Accepted: 08/07/2017] [Indexed: 12/30/2022] Open
Abstract
There have been striking associations of cardiovascular diseases (e.g., atherosclerosis) and hypercholesterolemia with increased risk of neurodegeneration including Alzheimer's disease (AD). Low-density lipoprotein (LDL), a cardiovascular risk factor, plays a crucial role in AD pathogenesis; further, L5, a human plasma LDL fraction with high electronegativity, may be a factor contributing to AD-type dementia. Although L5 contributing to atherosclerosis progression has been studied, its role in inducing neurodegeneration remains unclear. Here, PC12 cell culture was used for treatments with human LDLs (L1, L5, or oxLDL), and subsequently cell viability and nerve growth factor (NGF)-induced neuronal differentiation were assessed. We identified L5 as a neurotoxic LDL, as demonstrated by decreased cell viability in a time- and concentration-dependent manner. Contrarily, L1 had no such effect. L5 caused cell damage by inducing ATM/H2AX-associated DNA breakage as well as by activating apoptosis via lectin-like oxidized LDL receptor-1 (LOX-1) signaling to p53 and ensuring cleavage of caspase-3. Additionally, sublethal L5 long-termly inhibited neurite outgrowth in NGF-treated PC12 cells, as evidenced by downregulation of early growth response factor-1 and neurofilament-M. This inhibitory effect was mediated via an interaction between L5 and LOX-1 to suppress NGF-induced activation of PI3k/Akt cascade, but not NGF receptor TrkA and downstream MAPK pathways. Together, our data suggest that L5 creates a neurotoxic stress via LOX-1 in PC12 cells, thereby leading to impairment of viability and NGF-induced differentiation. Atherogenic L5 likely contributes to neurodegenerative disorders.
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17
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Lam V, Hackett M, Takechi R. Antioxidants and Dementia Risk: Consideration through a Cerebrovascular Perspective. Nutrients 2016; 8:nu8120828. [PMID: 27999412 PMCID: PMC5188481 DOI: 10.3390/nu8120828] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/16/2016] [Accepted: 12/16/2016] [Indexed: 12/16/2022] Open
Abstract
A number of natural and chemical compounds that exert anti-oxidative properties are demonstrated to be beneficial for brain and cognitive function, and some are reported to reduce the risk of dementia. However, the detailed mechanisms by which those anti-oxidative compounds show positive effects on cognition and dementia are still unclear. An emerging body of evidence suggests that the integrity of the cerebrovascular blood-brain barrier (BBB) is centrally involved in the onset and progression of cognitive impairment and dementia. While recent studies revealed that some anti-oxidative agents appear to be protective against the disruption of BBB integrity and structure, few studies considered the neuroprotective effects of antioxidants in the context of cerebrovascular integrity. Therefore, in this review, we examine the mechanistic insights of antioxidants as a pleiotropic agent for cognitive impairment and dementia through a cerebrovascular axis by primarily focusing on the current available data from physiological studies. Conclusively, there is a compelling body of evidence that suggest antioxidants may prevent cognitive decline and dementia by protecting the integrity and function of BBB and, indeed, further studies are needed to directly examine these effects in addition to underlying molecular mechanisms.
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Affiliation(s)
- Virginie Lam
- Curtin Health Innovation Research Institute, Curtin University, Perth WA 6845, Australia.
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth WA 6845, Australia.
| | - Mark Hackett
- Curtin Health Innovation Research Institute, Curtin University, Perth WA 6845, Australia.
- Department of Chemistry, Faculty of Science and Engineering, Curtin University, Perth WA 6845, Australia.
| | - Ryusuke Takechi
- Curtin Health Innovation Research Institute, Curtin University, Perth WA 6845, Australia.
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth WA 6845, Australia.
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18
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Choi HJ, Byun MS, Yi D, Choe YM, Sohn BK, Baek HW, Lee JH, Kim HJ, Han JY, Yoon EJ, Kim YK, Woo JI, Lee DY. Association Between Serum Triglycerides and Cerebral Amyloidosis in Cognitively Normal Elderly. Am J Geriatr Psychiatry 2016; 24:604-612. [PMID: 27311886 DOI: 10.1016/j.jagp.2016.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 02/22/2016] [Accepted: 03/07/2016] [Indexed: 01/07/2023]
Abstract
OBJECTIVES Although many preclinical studies have suggested the possible linkage between dyslipidemia and cerebral amyloid deposition, the association between serum lipid measures and cerebral amyloid-beta (Aβ) deposition in human brain is still poorly known. We aimed to investigate the association in cognitively normal (CN) elderly individuals. DESIGN Cross-sectional study. SETTING University hospital dementia clinic. PARTICIPANTS 59 CN elderly. MEASUREMENTS The study measures included comprehensive clinical and neuropsychological assessment based on the CERAD protocol, magnetic resonance imaging and (11)C-labelled Pittsburgh Compound B positron emission tomography scans, and quantification for serum lipid biomarkers. RESULTS Multiple linear regression analyses showed that a higher serum triglycerides level was associated with heavier global cerebral Aβ deposition even after controlling age, sex, and apolipoprotein E ε4 genotype. Serum apolipoprotein B also showed significant positive association with global cerebral Aβ deposition, but the significance disappeared after controlling serum triglycerides level. No association was found between other lipid measures and global cerebral Aβ deposition. CONCLUSIONS The findings suggest that serum triglycerides are closely associated with cerebral amyloidosis, although population-based prospective studies are needed to provide further evidence of the causative effect of triglycerides on cerebral amyloidosis.
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Affiliation(s)
- Hyo Jung Choi
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Min Soo Byun
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Dahyun Yi
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Young Min Choe
- Department of Neuropsychiatry, Ulsan University Hospital, Ulsan, Republic of Korea
| | - Bo Kyung Sohn
- Department of Neuropsychiatry, Seoul National University Boramae Medical Center, Seoul, Republic of Korea
| | - Hye Won Baek
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jun Ho Lee
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Hyun Jung Kim
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Ji Young Han
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Eun Jin Yoon
- Department of Nuclear Medicine, Seoul National University Boramae Medical Center, Seoul, Republic of Korea
| | - Yu Kyeong Kim
- Department of Nuclear Medicine, Seoul National University Boramae Medical Center, Seoul, Republic of Korea
| | - Jong Inn Woo
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Dong Young Lee
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea.
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19
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Li S, Geiger NH, Soliman ML, Hui L, Geiger JD, Chen X. Caffeine, Through Adenosine A3 Receptor-Mediated Actions, Suppresses Amyloid-β Protein Precursor Internalization and Amyloid-β Generation. J Alzheimers Dis 2016; 47:73-83. [PMID: 26402756 DOI: 10.3233/jad-142223] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Intraneuronal accumulation and extracellular deposition of amyloid-β (Aβ) protein continues to be implicated in the pathogenesis of Alzheimer's disease (AD), be it familial in origin or sporadic in nature. Aβ is generated intracellularly following endocytosis of amyloid-β protein precursor (AβPP), and, consequently, factors that suppress AβPP internalization may decrease amyloidogenic processing of AβPP. Here we tested the hypothesis that caffeine decreases Aβ generation by suppressing AβPP internalization in primary cultured neurons. Caffeine concentration-dependently blocked low-density lipoprotein (LDL) cholesterol internalization and a specific adenosine A3 receptor (A3R) antagonist as well as siRNA knockdown of A3Rs mimicked the effects of caffeine on neuronal internalization of LDL cholesterol. Further implicating A3Rs were findings that a specific A3R agonist increased neuronal internalization of LDL cholesterol. In addition, caffeine as well as siRNA knockdown of A3Rs blocked the ability of LDL cholesterol to increase Aβ levels. Furthermore, caffeine blocked LDL cholesterol-induced decreases in AβPP protein levels in neuronal plasma membranes, increased surface expression of AβPP on neurons, and the A3R antagonist as well as siRNA knockdown of A3Rs mimicked the effects of caffeine on AβPP surface expression. Moreover, the A3R agonist decreased neuronal surface expression of AβPP. Our findings suggest that caffeine exerts protective effects against amyloidogenic processing of AβPP at least in part by suppressing A3R-mediated internalization of AβPP.
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20
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Pallebage-Gamarallage M, Takechi R, Lam V, Elahy M, Mamo J. Pharmacological modulation of dietary lipid-induced cerebral capillary dysfunction: Considerations for reducing risk for Alzheimer's disease. Crit Rev Clin Lab Sci 2015; 53:166-83. [PMID: 26678521 DOI: 10.3109/10408363.2015.1115820] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
An increasing body of evidence suggests that cerebrovascular dysfunction and microvessel disease precede the evolution of hallmark pathological features that characterise Alzheimer's disease (AD), consistent with a causal association for onset or progression. Recent studies, principally in genetically unmanipulated animal models, suggest that chronic ingestion of diets enriched in saturated fats and cholesterol may compromise blood-brain barrier (BBB) integrity resulting in inappropriate blood-to-brain extravasation of plasma proteins, including lipid macromolecules that may be enriched in amyloid-β (Aβ). Brain parenchymal retention of blood proteins and lipoprotein bound Aβ is associated with heightened neurovascular inflammation, altered redox homeostasis and nitric oxide (NO) metabolism. Therefore, it is a reasonable proposition that lipid-lowering agents may positively modulate BBB integrity and by extension attenuate risk or progression of AD. In addition to their robust lipid lowering properties, reported beneficial effects of lipid-lowering agents were attributed to their pleiotropic properties via modulation of inflammation, oxidative stress, NO and Aβ metabolism. The review is a contemporary consideration of a complex body of literature intended to synthesise focussed consideration of mechanisms central to regulation of BBB function and integrity. Emphasis is given to dietary fat driven significant epidemiological evidence consistent with heightened risk amongst populations consuming greater amounts of saturated fats and cholesterol. In addition, potential neurovascular benefits associated with the use of hypolipidemic statins, probucol and fenofibrate are also presented in the context of lipid-lowering and pleiotropic properties.
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Affiliation(s)
- Menuka Pallebage-Gamarallage
- a Faculty of Health Sciences , School of Public Health Curtin University , Perth , WA , Australia and.,b Curtin Health Innovation Research Institute of Aging and Chronic Disease, Curtin University , Perth , WA , Australia
| | - Ryusuke Takechi
- a Faculty of Health Sciences , School of Public Health Curtin University , Perth , WA , Australia and.,b Curtin Health Innovation Research Institute of Aging and Chronic Disease, Curtin University , Perth , WA , Australia
| | - Virginie Lam
- a Faculty of Health Sciences , School of Public Health Curtin University , Perth , WA , Australia and.,b Curtin Health Innovation Research Institute of Aging and Chronic Disease, Curtin University , Perth , WA , Australia
| | - Mina Elahy
- a Faculty of Health Sciences , School of Public Health Curtin University , Perth , WA , Australia and.,b Curtin Health Innovation Research Institute of Aging and Chronic Disease, Curtin University , Perth , WA , Australia
| | - John Mamo
- a Faculty of Health Sciences , School of Public Health Curtin University , Perth , WA , Australia and.,b Curtin Health Innovation Research Institute of Aging and Chronic Disease, Curtin University , Perth , WA , Australia
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21
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Puig KL, Lutz BM, Urquhart SA, Rebel AA, Zhou X, Manocha GD, Sens M, Tuteja AK, Foster NL, Combs CK. Overexpression of mutant amyloid-β protein precursor and presenilin 1 modulates enteric nervous system. J Alzheimers Dis 2015; 44:1263-78. [PMID: 25408221 PMCID: PMC6295343 DOI: 10.3233/jad-142259] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder histologically characterized by amyloid-β (Aβ) protein accumulation and activation of associated microglia. Although these features are well described in the central nervous system, the process and consequences of Aβ accumulation in the enteric nervous system have not been extensively studied. We hypothesized that Aβ also may accumulate in the enteric nervous system and lead to immune cell activation and neuronal dysfunction in the digestive tract not unlike that observed in diseased brain. To test this hypothesis, ileums of the small intestine of thirteen month old AβPP/PS1 and C57BL/6 (wild type) mice were collected and analyzed using immunohistochemistry, western blot analysis, cytokine arrays, and ELISA. AβPP/PS1 mice demonstrated no differences in intestinal motility or water absorption but elevated luminal IgA levels compared to wild type mice. They also had increased protein levels of AβPP and the proteolytic enzyme, BACE, corresponding to an increase in Aβ1-40 in the intestinal lysate as well as an increase in both Aβ1-40 and Aβ1-42 in the stool. This correlated with increased protein markers of proinflammatory and immune cell activation. Histologic analysis localized AβPP within enteric neurons but also intestinal epithelial cells with elevated Aβ immunoreactivity in the AβPP/PS1 mice. The presence of AβPP, Aβ, and CD68 immunoreactivity in the intestines of some patients with neuropathologically-confirmed AD are consistent with the findings in this mouse model. These data support the hypothesis that in AD the intestine, much like the brain, may develop proinflammatory and immune changes related to AβPP and Aβ.
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Affiliation(s)
- Kendra L. Puig
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Brianna M. Lutz
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Siri A. Urquhart
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Andrew A. Rebel
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Xudong Zhou
- Department of Pathology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Gunjan D. Manocha
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - MaryAnn Sens
- Department of Pathology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Ashok K. Tuteja
- Division of Gastroenterology, University of Utah, Salt Lake City, UT, USA
| | - Norman L. Foster
- Center for Alzheimer’s Care, Imaging and Research, Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Colin K. Combs
- Department of Basic Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
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22
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Chen X, Hui L, Geiger JD. Role of LDL cholesterol and endolysosomes in amyloidogenesis and Alzheimer's disease. ACTA ACUST UNITED AC 2014; 5. [PMID: 26413387 DOI: 10.4172/2155-9562.1000236] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The pathogenesis of late-onset sporadic Alzheimer's disease (AD) is believed to result from complex interactions between nutritional, environmental, epigenetic and genetic factors. Among those factors, altered circulating cholesterol homeostasis, independent of the APOE genotype, continues to be implicated in brain deposition of amyloid beta protein (Aβ) and the pathogenesis of AD. It is believed that trafficking of amyloid beta precursor protein (AβPP) into endolysosomes appears to play a critical role in determining amyloidogenic processing of AβPP because this is precisely where two enzymes critically important in AβPP metabolism are located; beta amyloid converting enzyme (BACE-1) and gamma secretase enzyme. We have shown that elevated levels of LDL cholesterol promote AβPP internalization, disturb neuronal endolysosome structure and function, and increase Aβ accumulation in neuronal endolysosomes. Here, we will further discuss the linkage between elevated levels of LDL cholesterol and AD pathogenesis, and explore the underlying mechanisms whereby elevated levels of plasma LDL cholesterol promote amyloidogenesis.
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Affiliation(s)
- Xuesong Chen
- Department of Basic Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203
| | - Liang Hui
- Department of Basic Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203
| | - Jonathan D Geiger
- Department of Basic Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203
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23
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Takechi R, Galloway S, Pallebage-Gamarallage MM, Lam V, Dhaliwal SS, Mamo JC. Probucol prevents blood-brain barrier dysfunction in wild-type mice induced by saturated fat or cholesterol feeding. Clin Exp Pharmacol Physiol 2013; 40:45-52. [PMID: 23167559 DOI: 10.1111/1440-1681.12032] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 10/24/2012] [Accepted: 11/15/2012] [Indexed: 01/08/2023]
Abstract
Dysfunction of the blood-brain barrier (BBB) is an early pathological feature of vascular dementia and Alzheimer's disease (AD) and is triggered by inflammatory stimuli. Probucol is a lipid-lowering agent with potent anti-oxidant properties once commonly used for the treatment of cardiovascular disease. Probucol therapy was found to stabilize cognitive symptoms in elderly AD patients, whereas in amyloid transgenic mice probucol was shown to attenuate amyloidosis. However, the mechanisms underlying the effects of probucol have note been determined. In the present study we investigated whether probucol can prevent BBB disturbances induced by chronic ingestion of proinflammatory diets enriched with either 20% (w/w) saturated fats (SFA) or 1% (w/w) cholesterol. Mice were fed the diets for 12 weeks before they were killed and BBB integrity was measured. Mice maintained on either the SFA- or cholesterol-supplemented diets were found to have a 30- and sevenfold greater likelihood of BBB dysfunction, respectively, as determined by the parenchymal extravasation of plasma-derived immunoglobulins and endogenous lipoprotein enrichment with β-amyloid. In contrast, mice fed the SFA- or cholesterol-enriched diets that also contained 1% (w/w) probucol showed no evidence of BBB disturbance. The parenchymal expression of glial fibrillary acidic protein, a marker of cerebrovascular inflammation, was significantly greater in mice fed the SFA-enriched diet. Plasma lipid, β-amyloid and apolipoprotein B levels were not increased by feeding of the SFA- or cholesterol-enriched diets. However, mice fed the SFA- or cholesterol-enriched diets did exhibit increased plasma non-esterified fatty acid levels that were not reduced by probucol. The data suggest that probucol prevents disturbances of BBB induced by chronic ingestion of diets enriched in SFA or cholesterol by suppressing inflammatory pathways rather than by modulating plasma lipid homeostasis.
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Affiliation(s)
- Ryusuke Takechi
- Faculty of Health Sciences, School of Public Health, Curtin Health Innovation Research Institute Biosciences Research Precinct, Curtin University, Bentley, WA, Australia
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24
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Woods AG, Sokolowska I, Taurines R, Gerlach M, Dudley E, Thome J, Darie CC. Potential biomarkers in psychiatry: focus on the cholesterol system. J Cell Mol Med 2012; 16:1184-95. [PMID: 22304330 PMCID: PMC3823072 DOI: 10.1111/j.1582-4934.2012.01543.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Measuring biomarkers to identify and assess illness is a strategy growing in popularity and relevance. Although already in clinical use for treating and predicting cancer, no biological measurement is used clinically for any psychiatric disorder. Biomarkers could predict the course of a medical problem, and aid in determining how and when to treat. Several studies have indicated that of candidate psychiatric biomarkers detected using proteomic techniques, cholesterol and associated proteins, specifically apolipoproteins (Apos), may be of interest. Cholesterol is necessary for brain development and its synthesis continues at a lower rate in the adult brain. Apos are the protein component of lipoproteins responsible for lipid transport. There is extensive evidence that the levels of cholesterol and Apos may be disturbed in psychiatric disorders, including autistic spectrum disorders (ASD). Here, we describe putative serum biomarkers for psychiatric disorders, and the role of cholesterol and Apos in central nervous system (CNS) disorders.
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Affiliation(s)
- Alisa G Woods
- Department of Chemistry & Biomolecular Science, Biochemistry & Proteomics Group, Clarkson University, Potsdam, NY 13699, USA.
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Song F, Poljak A, Crawford J, Kochan NA, Wen W, Cameron B, Lux O, Brodaty H, Mather K, Smythe GA, Sachdev PS. Plasma apolipoprotein levels are associated with cognitive status and decline in a community cohort of older individuals. PLoS One 2012; 7:e34078. [PMID: 22701550 PMCID: PMC3372509 DOI: 10.1371/journal.pone.0034078] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 02/21/2012] [Indexed: 11/29/2022] Open
Abstract
Objectives Apolipoproteins have recently been implicated in the etiology of Alzheimer’s disease (AD). In particular, Apolipoprotein J (ApoJ or clusterin) has been proposed as a biomarker of the disease at the pre-dementia stage. We examined a group of apolipoproteins, including ApoA1, ApoA2, ApoB, ApoC3, ApoE, ApoH and ApoJ, in the plasma of a longitudinal community based cohort. Methods 664 subjects (257 with Mild Cognitive Impairment [MCI] and 407 with normal cognition), mean age 78 years, from the Sydney Memory and Aging Study (MAS) were followed up over two years. Plasma apolipoprotein levels at baseline (Wave 1) were measured using a multiplex bead fluorescence immunoassay technique. Results At Wave 1, MCI subjects had lower levels of ApoA1, ApoA2 and ApoH, and higher levels of ApoE and ApoJ, and a higher ApoB/ApoA1 ratio. Carriers of the apolipoprotein E ε4 allele had significantly lower levels of plasma ApoE, ApoC3 and ApoH and a significantly higher level of ApoB. Global cognitive scores were correlated positively with ApoH and negatively with ApoJ levels. ApoJ and ApoE levels were correlated negatively with grey matter volume and positively with cerebrospinal fluid (CSF) volume on MRI. Lower ApoA1, ApoA2 and ApoH levels, and higher ApoB/ApoA1 ratio, increased the risk of cognitive decline over two years in cognitively normal individuals. ApoA1 was the most significant predictor of decline. These associations remained after statistically controlling for lipid profile. Higher ApoJ levels predicted white matter atrophy over two years. Conclusions Elderly individuals with MCI have abnormal apolipoprotein levels, which are related to cognitive function and volumetric MRI measures cross-sectionally and are predictive of cognitive impairment in cognitively normal subjects. ApoA1, ApoH and ApoJ are potential plasma biomarkers of cognitive decline in non-demented elderly individuals.
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Affiliation(s)
- Fei Song
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
- Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, Australia
| | - Anne Poljak
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, Australia
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - John Crawford
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Nicole A. Kochan
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Wei Wen
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Barbara Cameron
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Ora Lux
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
| | - Henry Brodaty
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
- Dementia Collaborative Research Centre, University of New South Wales, Sydney, Australia
| | - Karen Mather
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
| | - George A. Smythe
- Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, Australia
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Perminder S. Sachdev
- Brain and Aging Research Program, University of New South Wales, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
- * E-mail:
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Endolysosome involvement in LDL cholesterol-induced Alzheimer's disease-like pathology in primary cultured neurons. Life Sci 2012; 91:1159-68. [PMID: 22580286 DOI: 10.1016/j.lfs.2012.04.039] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 04/19/2012] [Accepted: 04/24/2012] [Indexed: 12/26/2022]
Abstract
AIMS Elevated levels of circulating cholesterol are extrinsic factors contributing to the pathogenesis of sporadic Alzheimer's disease (AD). We showed previously that rabbits fed a cholesterol-enriched diet exhibited blood-brain barrier (BBB) dysfunction, increased accumulation of apolipoprotein B (ApoB) in brain neurons, and endolysosomes in brain had disturbed structures and functions. These effects were linked to increased amyloid beta (Aβ) production, increased tau-pathology, and disrupted synaptic integrity. Because pathological changes to endolysosomes represent a very early event in sporadic AD, we determined here the extent to which ApoB-containing LDL cholesterol altered the structure and function of endolysosomes and contributed to the development of AD-like pathology in primary cultured neurons. MAIN METHODS Cholesterol distribution and endolysosome morphology were determined histologically. Endolysosome pH was measured ratio-metrically with LysoSensor dye. Endolysosome enzyme activity was measured for acid phosphatase, cathepsins B and D, and beta-site APP cleaving enzyme 1 (BACE-1). AD-like pathologies, including increased production of Aβ, increased tau-pathology, and disrupted synaptic integrity were determined using ELISA, immunoblotting, and immunostaining techniques. KEY FINDINGS Treatment of neurons with ApoB-containing LDL cholesterol increased endolysosome accumulation of cholesterol, enlarged endolysosomes, and elevated endolysosome pH. In addition, ApoB-containing LDL cholesterol increased endolysosome accumulation of BACE-1, enhanced BACE-1 activity, increased Aβ levels, increased levels of phosphorylated tau, and decreased levels of synaptophysin. SIGNIFICANCE Our findings suggest strongly that alterations in the structure and function of endolysosomes play a key role in the exhibition of pathological features of AD that result from neuronal exposure to ApoB-containing LDL cholesterol.
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Amyloid precursor protein expression modulates intestine immune phenotype. J Neuroimmune Pharmacol 2011; 7:215-30. [PMID: 22124967 DOI: 10.1007/s11481-011-9327-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/14/2011] [Indexed: 12/16/2022]
Abstract
Amyloid precursor protein (APP) is widely expressed across many tissue and cell types. Proteolytic processing of the protein gives rise to a plethora of protein fragments with varied biological activities. Although a large amount of data has been generated describing the metabolism of the protein in neurons, its role in regulating the phenotype of other cells remains unclear. Based upon prior work demonstrating that APP regulates the activation phenotype of monocytic lineage cells, we hypothesized that APP can regulate macrophage activation phenotype in tissues other than brain. Ileums of the small intestines from C57BL6/J wild type and APP(-/-) mice were compared as a representative tissue normally associated with abundant macrophage infiltration. APP(-/-) intestines demonstrated diminished CD68 immunoreactivity compared to wild type mice. This correlated with significantly less cyclooxygenase-2 (cox-2), CD68, CD40, CD11c, and βIII-tubulin protein levels. Peritoneal macrophages from APP(-/-) mice demonstrated decreased in vitro migratory ability compared to wild type cells and diminished basal KC cytokine secretion. Whereas, APP(-/-) intestinal macrophages had an increase in basal KC cytokine secretion compared to wild type cells. Conversely, there was a significant decrease in multiple cytokine levels in APP(-/-) compared to wild type ileums. Finally, APP(-/-) mice demonstrated impaired absorption and increased motility compared to wild type mice. These data demonstrate the APP expression regulates immune cell secretions and phenotype and intestinal function. This data set describes a novel function for this protein or its metabolites that may be relevant not only for Alzheimer's disease but a range of immune-related disorders.
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Chen X, Wagener JF, Morgan DH, Hui L, Ghribi O, Geiger JD. Endolysosome mechanisms associated with Alzheimer's disease-like pathology in rabbits ingesting cholesterol-enriched diet. J Alzheimers Dis 2011; 22:1289-303. [PMID: 20930277 DOI: 10.3233/jad-2010-101323] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Alzheimer's disease (AD) is characterized clinically by progressive disturbances in memory, judgment, reasoning, and olfaction, and pathologically by loss of synaptic integrity, extracellular accumulations of amyloid-β (Aβ) containing plaques, and intraneuronal tangles composed of hyperphosphorylated tau. Endolysosome dysfunction is one of the earliest pathological features of AD and cholesterol, a known risk factor for sporadic AD, is up-taken into neurons via receptor-mediated endocytosis. Accordingly, we determined the extent to which endolysosome dysfunction is associated with pathological features observed in rabbits fed cholesterol-enriched diet; a well-characterized model of sporadic AD. Olfactory bulbs were taken from rabbits fed for 12 weeks a diet enriched with 2% cholesterol and endolysosome morphology and function as well as AD-like pathology were investigated using enzyme activity measurements, immunoblotting and immunostaining techniques. In olfactory bulbs of rabbits fed cholesterol-enriched diet, we observed enlarged endolysosomes containing increased accumulations of ApoB containing cholesterol and increased accumulations of synaptophysin, Aβ, and phosphorylated tau. The cholesterol-enriched diet also significantly decreased specific enzyme activities of the endolysosome enzymes acid phosphatase and cathepsin D. Decreased synaptic area was present in olfactory bulbs of cholesterol-fed rabbits as indicated by significant decreases in protein expression levels of the synaptic area marker protein synaptophysin. Our results suggest strongly that elevated circulating cholesterol plays an important role in the pathogenesis of AD, and that alterations in endolysosome structure and function are associated with cholesterol diet-induced AD-like pathology.
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Affiliation(s)
- Xuesong Chen
- Department of Pharmacology, Physiology and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
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Lam V, Takechi R, Pallebage-Gamarallage MMS, Galloway S, Mamo JCL. Colocalisation of plasma derived apo B lipoproteins with cerebral proteoglycans in a transgenic-amyloid model of Alzheimer's disease. Neurosci Lett 2011; 492:160-4. [PMID: 21310214 DOI: 10.1016/j.neulet.2011.02.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 01/28/2011] [Accepted: 02/01/2011] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD) is characterized by cerebral proteinaceous deposits comprised of amyloid beta (Aβ). Evidence suggests that enhanced blood-to-brain delivery of Aβ occurs when plasma concentration is increased, exacerbating amyloidosis. In blood, significant Aβ is associated with apolipoprotein (apo) B lipoproteins. In this study, immunofluorescent microscopy was utilised to explore if there is an association between apo B lipoproteins and proteoglycan expression within Aβ-rich plaques in transgenic-amyloid mice. Focal accumulation of apo B was found with Aβ-plaque in APP/PS1 mice. There was enrichment in the proteoglycans, agrin, perlecan, biglycan and decorin within the core of dense Aβ-plaque. Perlecan, biglycan and decorin were positively associated with apo B lipoprotein abundance within amyloid plaque consistent with a cause-for-retention effect. These findings show that proteoglycans are an integral component of Aβ deposits in APP/PS1 mice. This study suggests that some proteoglycans contribute to Aβ retention, whilst other proteoglycans have different functions in the aetiology of AD.
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Affiliation(s)
- Virginie Lam
- Curtin Health Innovation Research Institute, and The Australian Technology Network Centre for Metabolic Fitness, Curtin University, Bentley Campus, Kent Street, Perth 6102, Australia
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Hoh Kam J, Lenassi E, Jeffery G. Viewing ageing eyes: diverse sites of amyloid Beta accumulation in the ageing mouse retina and the up-regulation of macrophages. PLoS One 2010; 5. [PMID: 20957206 PMCID: PMC2948519 DOI: 10.1371/journal.pone.0013127] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 09/01/2010] [Indexed: 12/03/2022] Open
Abstract
Background Amyloid beta (Aβ) accumulates in the ageing central nervous system and is associated with a number of age-related diseases, including age-related macular degeneration (AMD) in the eye. AMD is characterised by accumulation of extracellular deposits called drusen in which Aβ is a key constituent. Aβ activates the complement cascade and its deposition is associated with activated macrophages. So far, little is known about the quantitative measurements of Aβ accumulation and definitions of its relative sites of ocular deposition in the normal ageing mouse. Methodology/Principal Findings We have traced Aβ accumulation quantitatively in the ageing mouse retina using immunohistochemistry and Western blot analysis. We reveal that it is not only deposited at Bruch's membrane and along blood vessels, but unexpectedly, it also coats photoreceptor outer segments. While Aβ is present at all sites of deposition from 3 months of age, it increases markedly from 6 months onward. Progressive accumulation of deposits on outer segments was confirmed with scanning electron microscopy, revealing age-related changes in their morphology. Such progress of accumulation of Aβ on photoreceptor outer segments with age was also confirmed in human retinae using immunohistochemistry. We also chart the macrophage response to increases in Aβ showing up-regulation in their numbers using both confocal laser imaging of the eye in vivo followed by in vitro immunostaining. With age macrophages become bloated with cellular debris including Aβ, however, their increasing numbers fail to stop Aβ accumulation. Conclusions Increasing Aβ deposition in blood vessels and Bruch's membrane will impact upon retinal perfusion and clearance of cellular waste products from the outer retina, a region of very high metabolic activity. This accumulation of Aβ may contribute to the 30% reduction of photoreceptors found throughout life and the shortening of those that remain. The coating of Aβ on outer segments may also have an impact upon visual function with age.
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Affiliation(s)
- Jaimie Hoh Kam
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Eva Lenassi
- Institute of Ophthalmology, University College London, London, United Kingdom
- Eye Hospital, University Medical Centre, Ljubljana, Slovenia
| | - Glen Jeffery
- Institute of Ophthalmology, University College London, London, United Kingdom
- * E-mail:
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Martins IJ, Berger T, Sharman MJ, Verdile G, Fuller SJ, Martins RN. Cholesterol metabolism and transport in the pathogenesis of Alzheimer's disease. J Neurochem 2010; 111:1275-308. [PMID: 20050287 DOI: 10.1111/j.1471-4159.2009.06408.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting millions of people worldwide. Apart from age, the major risk factor identified so far for the sporadic form of AD is possession of the epsilon4 allele of apolipoprotein E (APOE), which is also a risk factor for coronary artery disease (CAD). Other apolipoproteins known to play an important role in CAD such as apolipoprotein B are now gaining attention for their role in AD as well. AD and CAD share other risk factors, such as altered cholesterol levels, particularly high levels of low density lipoproteins together with low levels of high density lipoproteins. Statins--drugs that have been used to lower cholesterol levels in CAD, have been shown to protect against AD, although the protective mechanism(s) involved are still under debate. Enzymatic production of the beta amyloid peptide, the peptide thought to play a major role in AD pathogenesis, is affected by membrane cholesterol levels. In addition, polymorphisms in several proteins and enzymes involved in cholesterol and lipoprotein transport and metabolism have been linked to risk of AD. Taken together, these findings provide strong evidence that changes in cholesterol metabolism are intimately involved in AD pathogenic processes. This paper reviews cholesterol metabolism and transport, as well as those aspects of cholesterol metabolism that have been linked with AD.
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Affiliation(s)
- Ian J Martins
- Centre of Excellence for Alzheimer's Disease Research and Care, Edith Cowan University, Joondalup, Australia.
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Extending the knowledge in histochemistry and cell biology. Histochem Cell Biol 2009; 133:1-40. [PMID: 19946696 DOI: 10.1007/s00418-009-0665-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2009] [Indexed: 01/21/2023]
Abstract
Central to modern Histochemistry and Cell Biology stands the need for visualization of cellular and molecular processes. In the past several years, a variety of techniques has been achieved bridging traditional light microscopy, fluorescence microscopy and electron microscopy with powerful software-based post-processing and computer modeling. Researchers now have various tools available to investigate problems of interest from bird's- up to worm's-eye of view, focusing on tissues, cells, proteins or finally single molecules. Applications of new approaches in combination with well-established traditional techniques of mRNA, DNA or protein analysis have led to enlightening and prudent studies which have paved the way toward a better understanding of not only physiological but also pathological processes in the field of cell biology. This review is intended to summarize articles standing for the progress made in "histo-biochemical" techniques and their manifold applications.
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Dietary fats, cerebrovasculature integrity and Alzheimer's disease risk. Prog Lipid Res 2009; 49:159-70. [PMID: 19896503 DOI: 10.1016/j.plipres.2009.10.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 10/30/2009] [Accepted: 10/30/2009] [Indexed: 01/08/2023]
Abstract
An emerging body of evidence is consistent with the hypothesis that dietary fats influence Alzheimer's disease (AD) risk, but less clear is the mechanisms by which this occurs. Alzheimer's is an inflammatory disorder, many consider in response to fibrillar formation and extracellular deposition of amyloid-beta (Abeta). Alternatively, amyloidosis could notionally be a secondary phenomenon to inflammation, because some studies suggest that cerebrovascular disturbances precede amyloid plaque formation. Hence, dietary fats may influence AD risk by either modulating Abeta metabolism, or via Abeta independent pathways. This review explores these two possibilities taking into consideration; (i) the substantial affinity of Abeta for lipids and its ordinary metabolism as an apolipoprotein; (ii) evidence that Abeta has potent vasoactive properties and (iii) studies which show that dietary fats modulate Abeta biogenesis and secretion. We discuss accumulating evidence that dietary fats significantly influence cerebrovascular integrity and as a consequence altered Abeta kinetics across the blood-brain barrier (BBB). Specifically, chronic ingestion of saturated fats or cholesterol appears to results in BBB dysfunction and exaggerated delivery from blood-to-brain of peripheral Abeta associated with lipoproteins of intestinal and hepatic origin. Interestingly, the pattern of saturated fat/cholesterol induced cerebrovascular disturbances in otherwise normal wild-type animal strains is analogous to established models of AD genetically modified to overproduce Abeta, consistent with a causal association. Saturated fats and cholesterol may exacerbate Abeta induced cerebrovascular disturbances by enhancing exposure of vessels of circulating Abeta. However, presently there is no evidence to support this contention. Rather, SFA and cholesterol appear to more broadly compromise BBB integrity with the consequence of plasma protein leakage into brain, including lipoprotein associated Abeta. The latter findings are consistent with the concept that AD is a dietary-fat induced phenotype of vascular dementia, reflecting the extraordinary entrapment of peripherally derived lipoproteins endogenously enriched in Abeta. Rather than being the initiating trigger for inflammation in AD, accumulation of extracellular lipoprotein-Abeta may be a secondary amplifier of dietary induced inflammation, or possibly, simply be consequential. Clearly, delineating the mechanisms by which dietary fats increase AD risk may be informative in developing new strategies for prevention and treatment of AD.
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Differential effects of dietary fatty acids on the cerebral distribution of plasma-derived apo B lipoproteins with amyloid-beta. Br J Nutr 2009; 103:652-62. [PMID: 19860996 DOI: 10.1017/s0007114509992194] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Some dietary fats are a risk factor for Alzheimer's disease (AD) but the mechanisms for this association are presently unknown. In the present study we showed in wild-type mice that chronic ingestion of SFA results in blood-brain barrier (BBB) dysfunction and significant delivery into the brain of plasma proteins, including apo B lipoproteins that are endogenously enriched in amyloid-beta (Abeta). Conversely, the plasma concentration of S100B was used as a marker of brain-to-blood leakage and was found to be increased two-fold because of SFA feeding. Consistent with a deterioration in BBB integrity in SFA-fed mice was a diminished cerebrovascular expression of occludin, an endothelial tight junction protein. In contrast to SFA-fed mice, chronic ingestion of MUFA or PUFA had no detrimental effect on BBB integrity. Utilising highly sensitive three-dimensional immunomicroscopy, we also showed that the cerebral distribution and co-localisation of Abeta with apo B lipoproteins in SFA-fed mice are similar to those found in amyloid precursor protein/presenilin-1 (APP/PS1) amyloid transgenic mice, an established murine model of AD. Moreover, there was a strong positive association of plasma-derived apo B lipoproteins with cerebral Abeta deposits. Collectively, the findings of the present study provide a plausible explanation of how dietary fats may influence AD risk. Ingestion of SFA could enhance peripheral delivery to the brain of circulating lipoprotein-Abeta and exacerbate the amyloidogenic cascade.
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Galloway S, Takechi R, Pallebage-Gamarallage MMS, Dhaliwal SS, Mamo JCL. Amyloid-beta colocalizes with apolipoprotein B in absorptive cells of the small intestine. Lipids Health Dis 2009; 8:46. [PMID: 19845970 PMCID: PMC2771012 DOI: 10.1186/1476-511x-8-46] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 10/22/2009] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Amyloid-beta is recognized as the major constituent of senile plaque found in subjects with Alzheimer's disease. However, there is increasing evidence that in a physiological context amyloid-beta may serve as regulating apolipoprotein, primarily of the triglyceride enriched lipoproteins. To consider this hypothesis further, this study utilized an in vivo immunological approach to explore in lipogenic tissue whether amyloid-beta colocalizes with nascent triglyceride-rich lipoproteins. RESULTS In murine absorptive epithelial cells of the small intestine, amyloid-beta had remarkable colocalization with chylomicrons (Manders overlap coefficient = 0.73 +/- 0.03 (SEM)), the latter identified as immunoreactive apolipoprotein B. A diet enriched in saturated fats doubled the abundance of both amyloid-beta and apo B and increased the overlap coefficient of the two proteins (0.87 +/- 0.02). However, there was no evidence that abundance of the two proteins was interdependent within the enterocytes (Pearson's Coefficient < 0.02 +/- 0.03), or in plasma (Pearson's Coefficient < 0.01). CONCLUSION The findings of this study are consistent with the possibility that amyloid-beta is secreted by enterocytes as an apolipoprotein component of chylomicrons. However, secretion of amyloid-beta appears to be independent of chylomicron biogenesis.
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Affiliation(s)
- Susan Galloway
- The Australian Technology Network Centre for Metabolic Fitness, School of Public Health, Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia, Australia
| | - Ryusuke Takechi
- The Australian Technology Network Centre for Metabolic Fitness, School of Public Health, Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia, Australia
| | - Menuka MS Pallebage-Gamarallage
- The Australian Technology Network Centre for Metabolic Fitness, School of Public Health, Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia, Australia
| | - Satvinder S Dhaliwal
- The Australian Technology Network Centre for Metabolic Fitness, School of Public Health, Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia, Australia
| | - John CL Mamo
- The Australian Technology Network Centre for Metabolic Fitness, School of Public Health, Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia, Australia
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