51
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Wei C, Fan J, Sun X, Yao J, Guo Y, Zhou B, Shang Y. Acetyl-11-keto-β-boswellic acid ameliorates cognitive deficits and reduces amyloid-β levels in APPswe/PS1dE9 mice through antioxidant and anti-inflammatory pathways. Free Radic Biol Med 2020; 150:96-108. [PMID: 32109514 DOI: 10.1016/j.freeradbiomed.2020.02.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/16/2020] [Accepted: 02/20/2020] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is a complex disease involved oxidative stress and inflammation in its pathogenesis. Acetyl-11-keto-β-boswellic acid (AKBA) is an active triterpenoid compound from extracts of Boswellia serrata, which has been widely used as an antioxidant and anti-inflammatory agent. The present study was to determine whether AKBA, a novel candidate, could protect against cognitive and neuropathological impairments in AD. We found that AKBA treatment resulted in a significant improvement of learning and memory deficits, a dramatic decrease in cerebral amyloid-β (Aβ) levels and plaque burden, a profound alleviation in oxidative stress and inflammation, and a marked reduction in activated glial cells and synaptic defects in the APPswe/PS1dE9 mice. Furthermore, amyloid precursor protein (APP) processing was remarkably suppressed with AKBA treatment by inhibiting beta-site APP cleaving enzyme 1 (BACE1) protein expression to produce Aβ in the APPswe/PS1dE9 mice brains. Mechanistically, AKBA modulated antioxidant and anti-inflammatory pathways via increasing nuclear erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression, and via declining phosphorylation of inhibitor of nuclear factor-kappa B alpha (IκBα) and p65. Collectively, our findings provide evidence that AKBA protects neurons against oxidative stress and inflammation in AD, and this neuroprotective effect involves the Nrf2/HO-1 and nuclear factor-kappa B (NF-κB) signaling pathways.
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Affiliation(s)
- Chao Wei
- Department of Neurology, The Second Medical Center, Chinese PLA General Hospital, Beijing, 100853, China.
| | - Jiao Fan
- Institute of Geriatrics, National Clinical Research Center of Geriatrics Disease, Chinese PLA General Hospital, Beijing, 100853, China
| | - Xuan Sun
- Department of Neurology, The Second Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
| | - Jiarui Yao
- Department of Neurology, The Second Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
| | - Yane Guo
- Department of Neurology, The Second Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
| | - Bo Zhou
- Department of Neurology, The Second Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
| | - Yanchang Shang
- Department of Neurology, The Second Medical Center, Chinese PLA General Hospital, Beijing, 100853, China
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52
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Leigh SJ, Morris MJ. Diet, inflammation and the gut microbiome: Mechanisms for obesity-associated cognitive impairment. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165767. [PMID: 32171891 DOI: 10.1016/j.bbadis.2020.165767] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 02/18/2020] [Accepted: 03/09/2020] [Indexed: 12/11/2022]
Abstract
Poor diet and obesity are associated with cognitive impairment throughout adulthood, and increased dementia risk in aging. Here we review the current literature interrogating the mechanisms by which diets high in fat, or fat and sugar lead to cognitive impairment, focusing on changes to gut microbiome composition, inflammatory signalling and blood-brain barrier integrity. Preclinical studies indicate weight gain is not necessary for diet-induced cognitive impairment. Rather, gut microbiome composition, and systemic and central inflammatory processes appear to contribute to diet-induced cognitive impairment. While both obese humans and rodents exhibit reduced blood-brain barrier integrity, cognitive impairments precede these changes, suggesting other mechanisms may underly diet-induced cognitive changes. Other potential candidates include hormone, glucoregulatory and cardiovascular changes. Poor diet and obesity act through multiple mechanisms to affect cognitive health and the challenge for future research is to identify key processes that can be reversed to improve cognition and quality of life.
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53
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Alnefeesi Y, Siegel A, Lui LMW, Teopiz KM, Ho RCM, Lee Y, Nasri F, Gill H, Lin K, Cao B, Rosenblat JD, McIntyre RS. Impact of SARS-CoV-2 Infection on Cognitive Function: A Systematic Review. Front Psychiatry 2020; 11:621773. [PMID: 33643083 PMCID: PMC7902710 DOI: 10.3389/fpsyt.2020.621773] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/22/2020] [Indexed: 12/29/2022] Open
Abstract
The prevalence and etiology of COVID-19's impact on brain health and cognitive function is poorly characterized. With mounting reports of delirium, systemic inflammation, and evidence of neurotropism, a statement on cognitive impairment among COVID-19 cases is needed. A substantial literature has demonstrated that inflammation can severely disrupt brain function, suggesting an immune response, a cytokine storm, as a possible cause of neurocognitive impairments. In this light, the aim of the present study was to summarize the available knowledge of the impact of COVID-19 on cognition (i.e., herein, we broadly define cognition reflecting the reporting on this topic in the literature) during the acute and recovery phases of the disease, in hospitalized patients and outpatients with confirmed COVID-19 status. A systematic review of the literature identified six studies which document the prevalence of cognitive impairment, and one which quantifies deficits after recovery. Pooling the samples of the included studies (total sample n = 644) at three standards of quality produced conservative estimates of cognitive impairment ranging from 43.0 to 66.8% prevalence in hospitalized COVID-19 patients only, as no studies which report on outpatients met criteria for inclusion in the main synthesis. The most common impairment reported was delirium and frequent reports of elevated inflammatory markers suggest etiology. Other studies have demonstrated that the disease involves marked increases in IL-6, TNFα, and IL-1β; cytokines known to have a profound impact on working memory and attention. Impairment of these cognitive functions is a characteristic aspect of delirium, which suggests these cytokines as key mediators in the etiology of COVID-19 induced cognitive impairments. Researchers are encouraged to assay inflammatory markers to determine the potential role of inflammation in mediating the disturbance of cognitive function in individuals affected by COVID-19.
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Affiliation(s)
- Yazen Alnefeesi
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada
| | - Ashley Siegel
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada
| | - Leanna M W Lui
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada
| | - Kayla M Teopiz
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada
| | - Roger C M Ho
- Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Yena Lee
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada
| | - Flora Nasri
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada
| | - Hartej Gill
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada
| | - Kangguang Lin
- Department of Affective Disorder, the Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou Medical University, Guangzhou, China.,Laboratory of Emotion and Cognition, the Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou Medical University, Guangzhou, China
| | - Bing Cao
- Key Laboratory of Cognition and Personality, Faculty of Psychology, Ministry of Education, Southwest University, Chongqing, China
| | - Joshua D Rosenblat
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Roger S McIntyre
- Mood Disorders Psychopharmacology Unit, University Health Network, Toronto, ON, Canada.,Department of Psychiatry, University of Toronto, Toronto, ON, Canada.,Department of Pharmacology, University of Toronto, Toronto, ON, Canada.,Brain and Cognition Discovery Foundation, Toronto, ON, Canada
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54
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Forner S, Martini AC, Prieto GA, Dang CT, Rodriguez-Ortiz CJ, Reyes-Ruiz JM, Trujillo-Estrada L, da Cunha C, Andrews EJ, Phan J, Vu Ha J, Chang AVZD, Levites Y, Cruz PE, Ager R, Medeiros R, Kitazawa M, Glabe CG, Cotman CW, Golde T, Baglietto-Vargas D, LaFerla FM. Intra- and extracellular β-amyloid overexpression via adeno-associated virus-mediated gene transfer impairs memory and synaptic plasticity in the hippocampus. Sci Rep 2019; 9:15936. [PMID: 31685865 PMCID: PMC6828807 DOI: 10.1038/s41598-019-52324-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 10/11/2019] [Indexed: 12/19/2022] Open
Abstract
Alzheimer's disease (AD), the most common age-related neurodegenerative disorder, is currently conceptualized as a disease of synaptic failure. Synaptic impairments are robust within the AD brain and better correlate with dementia severity when compared with other pathological features of the disease. Nevertheless, the series of events that promote synaptic failure still remain under debate, as potential triggers such as β-amyloid (Aβ) can vary in size, configuration and cellular location, challenging data interpretation in causation studies. Here we present data obtained using adeno-associated viral (AAV) constructs that drive the expression of oligomeric Aβ either intra or extracellularly. We observed that expression of Aβ in both cellular compartments affect learning and memory, reduce the number of synapses and the expression of synaptic-related proteins, and disrupt chemical long-term potentiation (cLTP). Together, these findings indicate that during the progression AD the early accumulation of Aβ inside neurons is sufficient to promote morphological and functional cellular toxicity, a phenomenon that can be exacerbated by the buildup of Aβ in the brain parenchyma. Moreover, our AAV constructs represent a valuable tool in the investigation of the pathological properties of Aβ oligomers both in vivo and in vitro.
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Affiliation(s)
- Stefania Forner
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Alessandra C Martini
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - G Aleph Prieto
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Cindy T Dang
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | | | - Jorge Mauricio Reyes-Ruiz
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697, USA
| | - Laura Trujillo-Estrada
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Celia da Cunha
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Elizabeth J Andrews
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Jimmy Phan
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Jordan Vu Ha
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Allissa V Z D Chang
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Yona Levites
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA
| | - Pedro E Cruz
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA
| | - Rahasson Ager
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
| | - Rodrigo Medeiros
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Masashi Kitazawa
- Department of Medicine, University of California, Irvine, Irvine, CA, 92697, USA
| | - Charles G Glabe
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, 92697, USA
| | - Carl W Cotman
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697, USA
- Department of Neurology, School of Medicine, University of California, Irvine, Irvine, CA, 92697, USA
| | - Todd Golde
- Department of Neuroscience, University of Florida, Gainesville, FL, 32610, USA
| | - David Baglietto-Vargas
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697, USA
| | - Frank M LaFerla
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, 92697, USA.
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, 92697, USA.
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55
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Ano Y, Yoshino Y, Kutsukake T, Ohya R, Fukuda T, Uchida K, Takashima A, Nakayama H. Tryptophan-related dipeptides in fermented dairy products suppress microglial activation and prevent cognitive decline. Aging (Albany NY) 2019; 11:2949-2967. [PMID: 31121563 PMCID: PMC6555451 DOI: 10.18632/aging.101909] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/03/2019] [Indexed: 01/08/2023]
Abstract
The rapid growth in aging populations has made prevention of age-related memory decline and dementia a high priority. Several epidemiological and clinical studies have concluded that fermented dairy products can help prevent cognitive decline; furthermore, intake of Camembert cheese prevents microglial inflammation and Alzheimer's pathology in mouse models. To elucidate the molecular mechanisms underlying the preventive effects of fermented dairy products, we screened peptides from digested milk protein for their potential to regulate the activation of microglia. We identified dipeptides of tryptophan-tyrosine (WY) and tryptophan-methionine that suppressed the microglial inflammatory response and enhanced the phagocytosis of amyloid-β (Aβ). Various fermented dairy products and food materials contain the WY peptide. Orally administered WY peptide was smoothly absorbed into blood, delivered to the brain, and improved the cognitive decline induced by lipopolysaccharide via the suppression of inflammation. Intake of the WY peptide prevented microglial inflammation, hippocampal long-term potential deficit, and memory impairment in aged mice. In an Alzheimer's model using 5×FAD mice, intake of the WY peptide also suppressed microglial inflammation and accumulation of Aβ, which improved cognitive decline. The identified dipeptides regulating microglial activity could potentially be used to prevent cognitive decline and dementia related to inflammation.
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Affiliation(s)
- Yasuhisa Ano
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
- Research Laboratories for Health Science & Food Technologies, Kirin Company Ltd., Yokohama-shi, Kanagawa 236-0004, Japan
| | - Yuka Yoshino
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
| | - Toshiko Kutsukake
- Research Laboratories for Health Science & Food Technologies, Kirin Company Ltd., Yokohama-shi, Kanagawa 236-0004, Japan
| | - Rena Ohya
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
- Research Laboratories for Health Science & Food Technologies, Kirin Company Ltd., Yokohama-shi, Kanagawa 236-0004, Japan
| | - Takafumi Fukuda
- Research Laboratories for Health Science & Food Technologies, Kirin Company Ltd., Yokohama-shi, Kanagawa 236-0004, Japan
| | - Kazuyuki Uchida
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
| | - Akihiko Takashima
- Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Hiroyuki Nakayama
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
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56
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Prieto GA, Smith ED, Tong L, Nguyen M, Cotman CW. Inhibition of LTP-Induced Translation by IL-1β Reduces the Level of Newly Synthesized Proteins in Hippocampal Dendrites. ACS Chem Neurosci 2019; 10:1197-1203. [PMID: 30695637 DOI: 10.1021/acschemneuro.8b00511] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
In rodent hippocampus, the inflammatory cytokine interleukin-1β (IL-1β) impairs memory and long-term potentiation (LTP), a major form of plasticity that depends on protein synthesis. A better understanding of the mechanisms by which IL-1β impairs LTP may help identify targets for preventing cognitive deterioration. We tested whether IL-1β inhibits protein synthesis in hippocampal neuron cultures following chemically induced LTP (cLTP). Fluorescent-tagging using click-chemistry showed that IL-1β reduces the level of newly synthesized proteins in proximal dendrites of cLTP stimulated neurons. Relative to controls, in cLTP stimulated neurons, IL-1β inhibited Akt/mTOR signaling, as well as the upregulation of GluA1, an AMPA receptor subunit, and LIMK1, a kinase that promotes actin polymerization. Notably, a novel TIR domain peptidomimetic (EM163) blocked both the activation of p38 and the suppression of cLTP-dependent protein synthesis by IL-1β. Our data support a model where IL-1β suppresses LTP directly in neurons by inhibiting mTOR-dependent translation.
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Affiliation(s)
- G. Aleph Prieto
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697, United States
| | - Erica D. Smith
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697, United States
| | - Liqi Tong
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697, United States
| | - Michelle Nguyen
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697, United States
| | - Carl W. Cotman
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, California 92697, United States
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697, United States
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57
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Ding Y, Bao X, Lao L, Ling Y, Wang Q, Xu S. p-Hydroxybenzyl Alcohol Prevents Memory Deficits by Increasing Neurotrophic Factors and Decreasing Inflammatory Factors in a Mice Model of Alzheimer’s Disease. J Alzheimers Dis 2019; 67:1007-1019. [DOI: 10.3233/jad-180910] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Yanfei Ding
- Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo, Zhejiang, China
| | | | - Lifeng Lao
- Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo, Zhejiang, China
| | - Yunxiang Ling
- Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo, Zhejiang, China
| | - Qinwen Wang
- Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo, Zhejiang, China
| | - Shujun Xu
- Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo, Zhejiang, China
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58
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A comparison of hippocampal microglial responses in aged and young rodents following dependent and non-dependent binge drinking. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2019; 148:305-343. [PMID: 31733666 PMCID: PMC9875180 DOI: 10.1016/bs.irn.2019.10.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Alcoholism is a highly visible and prevalent issue in the United States. Although binge-drinking is assumed to be a college-age problem, older adults (ages 65+) consume binge amounts of alcohol and have alcohol use disorders (AUDs). Moreover, individuals with alcohol dependence in their youth often continue to drink as they age. As such, this study tested the hypothesis that the effects of alcohol on hippocampal microglia are exacerbated in aged versus younger rodents in two AUD models. Briefly, adult (2-3 months) and aged (15+ months) Sprague-Dawley rats were administered alcohol or control diet using the Majchrowicz model to study alcohol-induced neurodegeneration. To study the effects of non-dependent binge consumption on microglia, adolescent (6-8 weeks) and aged (18+ months) C57/BL6N were subjected to the Drinking in the Dark paradigm. Microglia number and densitometry were assessed using immunohistochemistry. Hippocampal subregional and model/species-specific effects of alcohol were observed, but overall, aging did not appear to increase the alcohol-induced microglia reactivity as measured by Iba-1 densitometry. However, analysis of microglial counts revealed a significant decrease in the number microglia cells in both the alcohol-induced neurodegeneration and DID model across age groups. In the dentate gyrus, the loss of microglia was exacerbated by aging, particularly in mice after DID, non-dependent model. Using qRT-PCR, the persistence of alcohol and aging effects was assessed following the DID model. Allograft Inflammatory Factor 1 mRNA was increased in both young and aged mice by alcohol exposure; however, only in the aged mice did the alcohol effect persist. Overall, these data imply that the microglial response to alcohol is complex with evidence of depressed numbers of microglia but also increased reactivity with advanced age.
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59
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Denver P, McClean PL. Distinguishing normal brain aging from the development of Alzheimer's disease: inflammation, insulin signaling and cognition. Neural Regen Res 2018; 13:1719-1730. [PMID: 30136683 PMCID: PMC6128051 DOI: 10.4103/1673-5374.238608] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/16/2018] [Indexed: 12/21/2022] Open
Abstract
As populations age, prevalence of Alzheimer's disease (AD) is rising. Over 100 years of research has provided valuable insights into the pathophysiology of the disease, for which age is the principal risk factor. However, in recent years, a multitude of clinical trial failures has led to pharmaceutical corporations becoming more and more unwilling to support drug development in AD. It is possible that dependence on the amyloid cascade hypothesis as a guide for preclinical research and drug discovery is part of the problem. Accumulating evidence suggests that amyloid plaques and tau tangles are evident in non-demented individuals and that reducing or clearing these lesions does not always result in clinical improvement. Normal aging is associated with pathologies and cognitive decline that are similar to those observed in AD, making differentiation of AD-related cognitive decline and neuropathology challenging. In this mini-review, we discuss the difficulties with discerning normal, age-related cognitive decline with that related to AD. We also discuss some neuropathological features of AD and aging, including amyloid and tau pathology, synapse loss, inflammation and insulin signaling in the brain, with a view to highlighting cognitive or neuropathological markers that distinguish AD from normal aging. It is hoped that this review will help to bolster future preclinical research and support the development of clinical tools and therapeutics for AD.
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Affiliation(s)
- Paul Denver
- Greater Los Angeles Veterans Affairs Healthcare System, West Los Angeles Medical Center and Department of Neurology, University of California, Los Angeles, CA, USA
- Centre for Molecular Biosciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Paula L. McClean
- Northern Ireland Centre for Stratified Medicine, Clinical, Translational and Research Innovation Centre (C-TRIC), University of Ulster, Derry/Londonderry, Northern Ireland, UK
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60
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Newcombe EA, Camats-Perna J, Silva ML, Valmas N, Huat TJ, Medeiros R. Inflammation: the link between comorbidities, genetics, and Alzheimer's disease. J Neuroinflammation 2018; 15:276. [PMID: 30249283 PMCID: PMC6154824 DOI: 10.1186/s12974-018-1313-3] [Citation(s) in RCA: 321] [Impact Index Per Article: 53.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 09/11/2018] [Indexed: 12/21/2022] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disorder, most cases of which lack a clear causative event. This has made the disease difficult to characterize and, thus, diagnose. Although some cases are genetically linked, there are many diseases and lifestyle factors that can lead to an increased risk of developing AD, including traumatic brain injury, diabetes, hypertension, obesity, and other metabolic syndromes, in addition to aging. Identifying common factors and trends between these conditions could enhance our understanding of AD and lead to the development of more effective treatments. Although the immune system is one of the body’s key defense mechanisms, chronic inflammation has been increasingly linked with several age-related diseases. Moreover, it is now well accepted that chronic inflammation has an important role in the onset and progression of AD. In this review, the different inflammatory signals associated with AD and its risk factors will be outlined to demonstrate how chronic inflammation may be influencing individual susceptibility to AD. Our goal is to bring attention to potential shared signals presented by the immune system during different conditions that could lead to the development of successful treatments.
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Affiliation(s)
- Estella A Newcombe
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia.
| | - Judith Camats-Perna
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia
| | - Mallone L Silva
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia
| | - Nicholas Valmas
- Queensland Brain Institute, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Tee Jong Huat
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia.,Centre for Stem Cell Ageing and Regenerative Engineering, The University of Queensland, Brisbane, 4072, QLD, Australia
| | - Rodrigo Medeiros
- Neurula Laboratory, Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Building 79, Brisbane, 4072, QLD, Australia.
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