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Pandit H, Jones NS, Rebeck GW. Obesity affects brain cortex gene expression in an APOE genotype and sex dependent manner. Int J Obes (Lond) 2024; 48:841-848. [PMID: 38454009 DOI: 10.1038/s41366-024-01481-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 01/07/2024] [Accepted: 01/19/2024] [Indexed: 03/09/2024]
Abstract
OBJECTIVE Obesity is the top modifiable risk factor for Alzheimer's disease. We hypothesized that high fat diet (HFD)-induced obesity alters brain transcriptomics in APOE-genotype and sex dependent manners. Here, we investigated interactions between HFD, APOE, and sex, using a knock-in mouse model of the human APOE3 and APOE4 alleles. METHODS Six-month-old APOE3-TR and APOE4-TR mice were treated with either HFD or control chow. After 4 months, total RNA was extracted from the cerebral cortices and analyzed by poly-A enriched RNA sequencing on the Illumina platform. RESULTS Female mice demonstrated profound HFD-induced transcriptomic changes while there was little to no effect in males. In females, APOE3 brains demonstrated about five times more HFD-induced transcriptomic changes (399 up-regulated and 107 down-regulated genes) compared to APOE4 brains (30 up-regulated and 60 down-regulated). Unsupervised clustering analysis revealed two gene sets that responded to HFD in APOE3 mice but not in APOE4 mice. Pathway analysis demonstrated that HFD in APOE3 mice affected cortical pathways related to feeding behavior, blood circulation, circadian rhythms, extracellular matrix, and cell adhesion. CONCLUSIONS Female mice and APOE3 mice have the strongest cortical transcriptomic responses to HFD related to feeding behavior and extracellular matrix remodeling. The relative lack of response of the APOE4 brain to stress associated with obesity may leave it more susceptible to additional stresses that occur with aging and in AD.
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Affiliation(s)
- Harshul Pandit
- Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Road N.W., Washington, DC, 20007, USA
| | - Nahdia S Jones
- Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Road N.W., Washington, DC, 20007, USA
| | - G William Rebeck
- Department of Neuroscience, Georgetown University Medical Center, 3970 Reservoir Road N.W., Washington, DC, 20007, USA.
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Lai AY, Almanza DLV, Ribeiro JA, Hill ME, Mandrozos M, Koletar MM, Stefanovic B, McLaurin J. Obesity Facilitates Sex-Specific Improvement In Cognition And Neuronal Function In A Rat Model Of Alzheimer's Disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.11.575200. [PMID: 38328066 PMCID: PMC10849478 DOI: 10.1101/2024.01.11.575200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Obesity reduces or increases the risk of developing Alzheimer's disease (AD) depending on whether it is assessed in mid-life or late-life. There is currently no consensus on the relationship between obesity and AD or the mechanism or their interaction. Here, we aim to differentiate the cause-and-effect relationship between obesity and AD in a controlled rat model of AD. We induced obesity in 9-month-old TgF344-AD rats, that is pathology-load wise similar to early symptomatic phase of human AD. To more accurately model human obesity, we fed both TgF344-AD and non-transgenic littermates a varied high-carbohydrate-high-fat diet consisting of human food for 3 months. Obesity increased overall glucose metabolism and slowed cognitive decline in TgF344-AD rats, specifically executive function, without affecting non-transgenic rats. Pathological analyses of prefrontal cortex and hippocampus showed that obesity in TgF344-AD rats produced varied effects, with increased density of myelin and oligodendrocytes, lowered density and activation of microglia that we propose contributes to the cognitive improvement. However, obesity also decreased neuronal density, and promoted deposition of amyloid-beta plaques and tau inclusions. After 6 months on the high-carbohydrate-high-fat diet, detrimental effects on density of neurons, amyloid-beta plaques, and tau inclusions persisted while the beneficial effects on myelin, microglia, and cognitive functions remained albeit with a lower effect size. By examining the effect of sex, we found that both beneficial and detrimental effects of obesity were stronger in female TgF344-AD rats indicating that obesity during early symptomatic phase of AD is protective in females.
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Fitz NF, Sahu A, Lu Y, Ambrosio F, Lefterov I, Koldamova R. Extracellular Vesicles in Young Serum Contribute to the Restoration of Age-Related Brain Transcriptomes and Cognition in Old Mice. Int J Mol Sci 2023; 24:12550. [PMID: 37628730 PMCID: PMC10454174 DOI: 10.3390/ijms241612550] [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: 07/10/2023] [Revised: 08/01/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
We have previously demonstrated that circulating extracellular vesicles (EVs) are essential to the beneficial effect of young serum on the skeletal muscle regenerative cascade. Here, we show that infusions of young serum significantly improve age-associated memory deficits, and that these effects are abolished after serum depletion of EVs. RNA-seq analysis of the choroid plexus demonstrates EV-mediated effects on genes involved in barrier function and trans-barrier transport. Comparing the differentially expressed genes to recently published chronological aging clock genes reveals a reversal of transcriptomic aging in the choroid plexus. Following young serum treatment, the hippocampal transcriptome demonstrates significant upregulation of the anti-aging gene Klotho, along with an abrogated effect after EV depletion. Transcriptomic profiling of Klotho knockout and heterozygous mice shows the downregulation of genes associated with transport, exocytosis, and lipid transport, while upregulated genes are associated with activated microglia. The results of our study indicate the significance of EVs as vehicles to deliver signals from the periphery to the brain and the importance of Klotho in maintaining brain homeostasis.
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Affiliation(s)
- Nicholas F. Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Amrita Sahu
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Yi Lu
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Fabrisia Ambrosio
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA 02115, USA
- Discovery Center for Musculoskeletal Recovery, Schoen Adams Research Institute at Spaulding, Charlestown, MA 02129, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15260, USA
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4
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Christensen A, Pike CJ. Effects of APOE Genotype and Western Diet on Metabolic Phenotypes in Female Mice. Metabolites 2023; 13:metabo13020287. [PMID: 36837905 PMCID: PMC9959618 DOI: 10.3390/metabo13020287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/18/2023] Open
Abstract
Western diets high in sugars and saturated fats have been reported to induce metabolic and inflammatory impairments that are associated with several age-related disorders, including Alzheimer's disease (AD) and type 2 diabetes (T2D). The apolipoprotein E (APOE) genotype is associated with metabolic and inflammatory outcomes that contribute to risks for AD and T2D, with the APOE4 genotype increasing risks relative to the more common APOE3 allele. In this study, we investigated the impacts of the APOE genotype on systemic and neural effects of the Western diet. Female mice with knock-in of human APOE3 or APOE4 were exposed to control or Western diet for 13 weeks. In the control diet, we observed that APOE4 mice presented with impaired metabolic phenotypes, exhibiting greater adiposity, higher plasma leptin and insulin levels, and poorer glucose clearance than APOE3 mice. Behaviorally, APOE4 mice exhibited worse performance in a hippocampal-dependent learning task. In visceral adipose tissue, APOE4 mice exhibited generally higher expression levels of macrophage- and inflammation-related genes. The cerebral cortex showed a similar pattern, with higher expression of macrophage- and inflammation-related genes in APOE4 than APOE3 mice. Exposure to the Western diet yielded modest, statistically non-significant effects on most metabolic, behavioral, and gene expression measures in both APOE genotypes. Interestingly, the Western diet resulted in reduced gene expression of a few macrophage markers, specifically in APOE4 mice. The observed relative resistance to the Western diet suggests protective roles of both female sex and young adult age. Further, the data demonstrate that APOE4 is associated with deleterious systemic and neural phenotypes and an altered response to a metabolic stressor, findings relevant to the understanding of interactions between the APOE genotype and risks for metabolic disorders.
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5
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Valencia-Olvera AC, Maldonado Weng J, Christensen A, LaDu MJ, Pike CJ. Role of estrogen in women's Alzheimer's disease risk as modified by APOE. J Neuroendocrinol 2023; 35:e13209. [PMID: 36420620 PMCID: PMC10049970 DOI: 10.1111/jne.13209] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 09/29/2022] [Accepted: 10/13/2022] [Indexed: 12/15/2022]
Abstract
Alzheimer's disease (AD) is characterized by numerous sexual dimorphisms that impact the development, progression, and probably the strategies to prevent and treat the most common form of dementia. In this review, we consider this topic from a female perspective with a specific focus on how women's vulnerability to the disease is affected by the individual and interactive effects of estrogens and apolipoprotein E (APOE) genotype. Importantly, APOE appears to modulate systemic and neural outcomes of both menopause and estrogen-based hormone therapy. In the brain, dementia risk is greater in APOE4 carriers, and the impacts of hormone therapy on cognitive decline and dementia risk vary according to both outcome measure and APOE genotype. Beyond the CNS, estrogen and APOE genotype affect vulnerability to menopause-associated bone loss, dyslipidemia and cardiovascular disease risk. An emerging concept that may link these relationships is the possibility that the effects of APOE in women interact with estrogen status by mechanisms that may include modulation of estrogen responsiveness. This review highlights the need to consider the key AD risk factors of advancing age in a sex-specific manner to optimize development of therapeutic approaches for AD, a view aligned with the principle of personalized medicine.
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Affiliation(s)
- AC Valencia-Olvera
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - J Maldonado Weng
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - A Christensen
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089 USA
| | - MJ LaDu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - CJ Pike
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089 USA
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Amelianchik A, Sweetland-Martin L, Norris EH. The effect of dietary fat consumption on Alzheimer's disease pathogenesis in mouse models. Transl Psychiatry 2022; 12:293. [PMID: 35869065 PMCID: PMC9307654 DOI: 10.1038/s41398-022-02067-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 11/25/2022] Open
Abstract
Alzheimer's disease (AD) is a fatal cognitive disorder with proteinaceous brain deposits, neuroinflammation, cerebrovascular dysfunction, and extensive neuronal loss over time. AD is a multifactorial disease, and lifestyle factors, including diet, are likely associated with the development of AD pathology. Since obesity and diabetes are recognized as risk factors for AD, it might be predicted that a high-fat diet (HFD) would worsen AD pathology. However, modeling HFD-induced obesity in AD animal models has yielded inconclusive results. Some studies report a deleterious effect of HFD on Aβ accumulation, neuroinflammation, and cognitive function, while others report that HFD worsens memory without affecting AD brain pathology. Moreover, several studies report no major effect of HFD on AD-related phenotypes in mice, while other studies show that HFD might, in fact, be protective. The lack of a clear association between dietary fat consumption and AD-related pathology and cognitive function in AD mouse models might be explained by experimental variations, including AD mouse model, sex and age of the animals, composition of the HFD, and timeline of HFD consumption. In this review, we summarize recent studies that aimed at elucidating the effect of HFD-induced obesity on AD-related pathology in mice and provide an overview of the factors that may have contributed to the results reported in these studies. Based on the heterogeneity of these animal model studies and given that the human population itself is quite disparate, it is likely that people will benefit most from individualized nutritional plans based on their medical history and clinical profiles.
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Affiliation(s)
- Anna Amelianchik
- Patricia and John Rosenwald Laboratory of Neurobiology & Genetics, The Rockefeller University, 1230 York Avenue, New York, NY, USA
| | - Lauren Sweetland-Martin
- Patricia and John Rosenwald Laboratory of Neurobiology & Genetics, The Rockefeller University, 1230 York Avenue, New York, NY, USA
| | - Erin H Norris
- Patricia and John Rosenwald Laboratory of Neurobiology & Genetics, The Rockefeller University, 1230 York Avenue, New York, NY, USA.
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7
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Lynch MA. Exploring Sex-Related Differences in Microglia May Be a Game-Changer in Precision Medicine. Front Aging Neurosci 2022; 14:868448. [PMID: 35431903 PMCID: PMC9009390 DOI: 10.3389/fnagi.2022.868448] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/08/2022] [Indexed: 12/16/2022] Open
Abstract
One area of microglial biology that has been relatively neglected until recently is sex differences and this is in spite of the fact that sex is a risk factor in several diseases that are characterized by neuroinflammation and, by extension, microglial activation. Why these sex differences exist is not known but the panoply of differences extend to microglial number, genotype and phenotype. Significantly, several of these sex-related differences are also evident in health and change during life emphasizing the dynamic and plastic nature of microglia. This review will consider how age impacts on sex-related differences in microglia and ask whether the advancement of personalized medicine demands that a greater focus is placed on studying sex-related differences in microglia in Alzheimer's disease, Parkinson's disease and models of inflammatory stress and trauma in order to make true progress in dealing with these conditions.
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Affiliation(s)
- Marina A. Lynch
- Trinity College Institute of Neuroscience, Trinity College, Dublin, Ireland
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8
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Jones NS, Watson KQ, Rebeck GW. High-fat diet increases gliosis and immediate early gene expression in APOE3 mice, but not APOE4 mice. J Neuroinflammation 2021; 18:214. [PMID: 34537055 PMCID: PMC8449905 DOI: 10.1186/s12974-021-02256-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/26/2021] [Indexed: 01/12/2023] Open
Abstract
Background APOE4 is the strongest genetic risk factor for Alzheimer’s disease (AD), and obesity is a strong environmental risk factor for AD. These factors result in multiple central nervous system (CNS) disturbances and significantly increase chances of AD. Since over 20% of the US population carry the APOE4 allele and over 40% are obese, it is important to understand how these risk factors interact to affect neurons and glia in the CNS. Methods We fed male and female APOE3 and APOE4 knock-in mice a high-fat diet (HFD-45% kcal fat) or a "control" diet (CD-10% kcal fat) for 12 weeks beginning at 6 months of age. At the end of the 12 weeks, brains were collected and analyzed for gliosis, neuroinflammatory genes, and neuronal integrity. Results APOE3 mice on HFD, but not APOE4 mice, experienced increases in gliosis as measured by GFAP and Iba1 immunostaining. APOE4 mice on HFD showed a stronger increase in the expression of Adora2a than APOE3 mice. Finally, APOE3 mice on HFD, but not APOE4 mice, also showed increased neuronal expression of immediate early genes cFos and Arc. Conclusions These findings demonstrate that APOE genotype and obesity interact in their effects on important processes particularly related to inflammation and neuronal plasticity in the CNS. During the early stages of obesity, the APOE3 genotype modulates a response to HFD while the APOE4 genotype does not. This supports a model where early dysregulation of inflammation in APOE4 brains could predispose to CNS damages from various insults and later result in the increased CNS damage normally associated with the APOE4 genotype.
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Affiliation(s)
- Nahdia S Jones
- Department of Neuroscience, Georgetown University, Washington, DC, 20007, USA
| | - Katarina Q Watson
- Department of Neuroscience, Georgetown University, Washington, DC, 20007, USA
| | - G William Rebeck
- Department of Neuroscience, Georgetown University, Washington, DC, 20007, USA.
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9
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Fitz NF, Nam KN, Wolfe CM, Letronne F, Playso BE, Iordanova BE, Kozai TDY, Biedrzycki RJ, Kagan VE, Tyurina YY, Han X, Lefterov I, Koldamova R. Phospholipids of APOE lipoproteins activate microglia in an isoform-specific manner in preclinical models of Alzheimer's disease. Nat Commun 2021; 12:3416. [PMID: 34099706 PMCID: PMC8184801 DOI: 10.1038/s41467-021-23762-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 05/14/2021] [Indexed: 12/12/2022] Open
Abstract
APOE and Trem2 are major genetic risk factors for Alzheimer's disease (AD), but how they affect microglia response to Aβ remains unclear. Here we report an APOE isoform-specific phospholipid signature with correlation between human APOEε3/3 and APOEε4/4 AD brain and lipoproteins from astrocyte conditioned media of APOE3 and APOE4 mice. Using preclinical AD mouse models, we show that APOE3 lipoproteins, unlike APOE4, induce faster microglial migration towards injected Aβ, facilitate Aβ uptake, and ameliorate Aβ effects on cognition. Bulk and single-cell RNA-seq demonstrate that, compared to APOE4, cortical infusion of APOE3 lipoproteins upregulates a higher proportion of genes linked to an activated microglia response, and this trend is augmented by TREM2 deficiency. In vitro, lack of TREM2 decreases Aβ uptake by APOE4-treated microglia only, suggesting TREM2-APOE interaction. Our study elucidates phenotypic and transcriptional differences in microglial response to Aβ mediated by APOE3 or APOE4 lipoproteins in preclinical models of AD.
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Affiliation(s)
- Nicholas F Fitz
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kyong Nyon Nam
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Cody M Wolfe
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Florent Letronne
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Brittany E Playso
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bistra E Iordanova
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Takashi D Y Kozai
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Richard J Biedrzycki
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Valerian E Kagan
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yulia Y Tyurina
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xianlin Han
- Barshop Institute for Longevity and Aging Studies, San Antonio, TX, USA
| | - Iliya Lefterov
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Radosveta Koldamova
- Deparment of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA.
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10
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Liu RM, Chong Z, Chen JC. Ozone and Particulate Matter Exposure and Alzheimer's Disease: A Review of Human and Animal Studies. J Alzheimers Dis 2021; 76:807-824. [PMID: 32568209 DOI: 10.3233/jad-200435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD), an aging-related neurodegenerative disease, is a major cause of dementia in the elderly. Although the early-onset (familial) AD is attributed to mutations in the genes coding for amyloid-β protein precursor (AβPP) and presenilin1/presenilin 2 (PS1/PS2), the cause for the late-onset AD (LOAD), which accounts for more than 95% of AD cases, remains unclear. Aging is the greatest risk factor for LOAD, whereas the apolipo protein E4 allele (APOEɛ4) is believed to be a major genetic risk factor in acquiring LOAD, with female APOEɛ4 carriers at highest risk. Nonetheless, not all the elderly, even older female APOEɛ4 carriers, develop LOAD, suggesting that other factors, including environmental exposure, must play a role. This review summarizes recent studies that show a potential role of environmental exposure, especially ozone and particulate matter exposure, in the development of AD. Interactions between environmental exposure, genetic risk factor (APOEɛ4), and sex in AD pathophysiology are also discussed briefly. Identification of environmental risk factor(s) and elucidation of the complex interactions between genetic and environmental risk factors plus aging and female sex in the onset of AD will be a key to our understanding of the etiology and pathogenesis of AD and the development of the strategies for its prevention and treatment.
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Affiliation(s)
- Rui-Ming Liu
- Division of Pulmonary, Allergy, and Critical Care, Department of Medicine, the University of Alabama at Birmingham, Birmingham, AL, USA
| | - Zechen Chong
- Department of Genetics, the University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jiu-Chiuan Chen
- Department of Biostatistics and Data Science, The University of Southern California, Los Angeles, CA, USA
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11
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Mapping of Microglial Brain Region, Sex and Age Heterogeneity in Obesity. Int J Mol Sci 2021; 22:ijms22063141. [PMID: 33808700 PMCID: PMC8003547 DOI: 10.3390/ijms22063141] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 12/27/2022] Open
Abstract
The prevalence of obesity has increased rapidly in recent years and has put a huge burden on healthcare worldwide. Obesity is associated with an increased risk for many comorbidities, such as cardiovascular diseases, type 2 diabetes and hypertension. The hypothalamus is a key brain region involved in the regulation of food intake and energy expenditure. Research on experimental animals has shown neuronal loss, as well as microglial activation in the hypothalamus, due to dietary-induced obesity. Microglia, the resident immune cells in the brain, are responsible for maintaining the brain homeostasis and, thus, providing an optimal environment for neuronal function. Interestingly, in obesity, microglial cells not only get activated in the hypothalamus but in other brain regions as well. Obesity is also highly associated with changes in hippocampal function, which could ultimately result in cognitive decline and dementia. Moreover, changes have also been reported in the striatum and cortex. Microglial heterogeneity is still poorly understood, not only in the context of brain region but, also, age and sex. This review will provide an overview of the currently available data on the phenotypic differences of microglial innate immunity in obesity, dependent on brain region, sex and age.
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12
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Sullivan P. Influence of Western diet and APOE genotype on Alzheimer's disease risk. Neurobiol Dis 2020; 138:104790. [DOI: 10.1016/j.nbd.2020.104790] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/28/2020] [Accepted: 02/03/2020] [Indexed: 10/25/2022] Open
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13
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Lewandowski CT, Maldonado Weng J, LaDu MJ. Alzheimer's disease pathology in APOE transgenic mouse models: The Who, What, When, Where, Why, and How. Neurobiol Dis 2020; 139:104811. [PMID: 32087290 DOI: 10.1016/j.nbd.2020.104811] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/01/2020] [Accepted: 02/18/2020] [Indexed: 02/07/2023] Open
Abstract
The focus on amyloid plaques and neurofibrillary tangles has yielded no Alzheimer's disease (AD) modifying treatments in the past several decades, despite successful studies in preclinical mouse models. This inconsistency has caused a renewed focus on improving the fidelity and reliability of AD mouse models, with disparate views on how this improvement can be accomplished. However, the interactive effects of the universal biological variables of AD, which include age, APOE genotype, and sex, are often overlooked. Age is the greatest risk factor for AD, while the ε4 allele of the human APOE gene, encoding apolipoprotein E, is the greatest genetic risk factor. Sex is the final universal biological variable of AD, as females develop AD at almost twice the rate of males and, importantly, female sex exacerbates the effects of APOE4 on AD risk and rate of cognitive decline. Therefore, this review evaluates the importance of context for understanding the role of APOE in preclinical mouse models. Specifically, we detail how human AD pathology is mirrored in current transgenic mouse models ("What") and describe the critical need for introducing human APOE into these mouse models ("Who"). We next outline different methods for introducing human APOE into mice ("How") and highlight efforts to develop temporally defined and location-specific human apoE expression models ("When" and "Where"). We conclude with the importance of choosing the human APOE mouse model relevant to the question being addressed, using the selection of transgenic models for testing apoE-targeted therapeutics as an example ("Why").
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Affiliation(s)
- Cutler T Lewandowski
- Department of Pharmaceutical Sciences, University of Illinois at Chicago, 833 S. Wood St., Chicago, IL 60612, USA.
| | - Juan Maldonado Weng
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Chicago, IL 60612, USA.
| | - Mary Jo LaDu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, 808 S. Wood St., Chicago, IL 60612, USA.
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14
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Salih DA, Bayram S, Guelfi S, Reynolds RH, Shoai M, Ryten M, Brenton JW, Zhang D, Matarin M, Botia JA, Shah R, Brookes KJ, Guetta-Baranes T, Morgan K, Bellou E, Cummings DM, Escott-Price V, Hardy J. Genetic variability in response to amyloid beta deposition influences Alzheimer's disease risk. Brain Commun 2019; 1:fcz022. [PMID: 32274467 PMCID: PMC7145452 DOI: 10.1093/braincomms/fcz022] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 12/18/2022] Open
Abstract
Genome-wide association studies of late-onset Alzheimer's disease risk have previously identified genes primarily expressed in microglia that form a transcriptional network. Using transgenic mouse models of amyloid deposition, we previously showed that many of the mouse orthologues of these risk genes are co-expressed and associated with amyloid pathology. In this new study, we generate an improved RNA-seq-derived network that is expressed in amyloid-responsive mouse microglia and we statistically compare this with gene-level variation in previous human Alzheimer's disease genome-wide association studies to predict at least four new risk genes for the disease (OAS1, LAPTM5, ITGAM/CD11b and LILRB4). Of the mouse orthologues of these genes Oas1a is likely to respond directly to amyloid at the transcriptional level, similarly to established risk gene Trem2, because the increase in Oas1a and Trem2 transcripts in response to amyloid deposition in transgenic mice is significantly higher than both the increase of the average microglial transcript and the increase in microglial number. In contrast, the mouse orthologues of LAPTM5, ITGAM/CD11b and LILRB4 (Laptm5, Itgam/CD11b and Lilra5) show increased transcripts in the presence of amyloid plaques similar in magnitude to the increase of the average microglial transcript and the increase in microglia number, except that Laptm5 and Lilra5 transcripts increase significantly quicker than the average microglial transcript as the plaque load becomes dense. This work suggests that genetic variability in the microglial response to amyloid deposition is a major determinant for Alzheimer's disease risk, and identification of these genes may help to predict the risk of developing Alzheimer's disease. These findings also provide further insights into the mechanisms underlying Alzheimer's disease for potential drug discovery.
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Affiliation(s)
- Dervis A Salih
- Department of Neuroscience, Physiology and Pharmacology, UCL, Gower Street, London WC1E 6BT, UK
- UK Dementia Research Institute at UCL, Gower Street, London WC1E 6BT, UK
| | | | - Sebastian Guelfi
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Regina H Reynolds
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Maryam Shoai
- UK Dementia Research Institute at UCL, Gower Street, London WC1E 6BT, UK
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Mina Ryten
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Jonathan W Brenton
- Department of Neuroscience, Physiology and Pharmacology, UCL, Gower Street, London WC1E 6BT, UK
| | - David Zhang
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Mar Matarin
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Juan A Botia
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
- Department of Information and Communications Engineering, Universidad de Murcia, Spain
| | - Runil Shah
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
| | - Keeley J Brookes
- Human Genetics, School of Life Sciences, Life Sciences Building, University Park, University of Nottingham, Nottingham NG7 2RD, UK
| | - Tamar Guetta-Baranes
- Human Genetics, School of Life Sciences, Life Sciences Building, University Park, University of Nottingham, Nottingham NG7 2RD, UK
| | - Kevin Morgan
- Human Genetics, School of Life Sciences, Life Sciences Building, University Park, University of Nottingham, Nottingham NG7 2RD, UK
| | - Eftychia Bellou
- Dementia Research Institute, MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Damian M Cummings
- Department of Neuroscience, Physiology and Pharmacology, UCL, Gower Street, London WC1E 6BT, UK
| | - Valentina Escott-Price
- Dementia Research Institute, MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - John Hardy
- UK Dementia Research Institute at UCL, Gower Street, London WC1E 6BT, UK
- Department of Neurodegenerative Diseases, Institute of Neurology, UCL, 1 Wakefield Street, London WC1N 1PJ, UK
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15
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Balu D, Karstens AJ, Loukenas E, Maldonado Weng J, York JM, Valencia-Olvera AC, LaDu MJ. The role of APOE in transgenic mouse models of AD. Neurosci Lett 2019; 707:134285. [PMID: 31150730 PMCID: PMC6717006 DOI: 10.1016/j.neulet.2019.134285] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/18/2019] [Accepted: 05/21/2019] [Indexed: 12/17/2022]
Abstract
Identified in 1993, APOE4 is the greatest genetic risk factor for Alzheimer's disease (AD), increasing risk up to 15-fold compared to the common variant APOE3. Since the mid 1990's, transgenic (Tg) mice have been developed to model AD pathology and progression, primarily via expression of the familial AD (FAD) mutations in the presence of mouse-APOE (m-APOE). APOE4, associated with enhanced amyloid-β (Aβ) accumulation, has rarely been the focus in designing FAD-Tg mouse models. Initially, FAD-Tg mice were crossed with human (h)-APOE driven by heterologous promoters to identify an APOE genotype-specific AD phenotype. These models were later supplemented with FAD-Tg mice crossed with APOE-knockouts (APOE-/- or APOE-KO) and h-APOE-targeted replacement (h-APOE-TR) mice, originally generated to study the role of APOE genotype in peripheral lipid metabolism and atherosclerotic lesion development. Herein, we compare the m- and h-APOE multi-gene clusters, and then critically review the relevant history and approaches to developing a Tg mouse model to characterize APOE-dependent AD pathology, in combination with genetic (sex, age) and modifiable (e.g., inflammation, obesity) risk factors. Finally, we present recent data from the EFAD mice, which express 5xFAD mutations with the expression of the human apoE isoforms (E2FAD, E3FAD and E4FAD). This includes a study of 6- and 18-month-old male and female E3FAD and E4FAD, a comparison that enables examination of the interaction among the main AD risk factors: age, APOE genotype and sex. While no single transgenic mouse can capture the effects of all modifiable and genetic risk factors, going forward, a conscious effort needs to be made to include the factors that most significantly modulate AD pathology.
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Affiliation(s)
- Deebika Balu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Aimee James Karstens
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA; Department of Psychology, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Efstathia Loukenas
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Juan Maldonado Weng
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Jason M York
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | | | - Mary Jo LaDu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA.
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16
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Moir RD, Tanzi RE. Low Evolutionary Selection Pressure in Senescence Does Not Explain the Persistence of Aβ in the Vertebrate Genome. Front Aging Neurosci 2019; 11:70. [PMID: 30983989 PMCID: PMC6447958 DOI: 10.3389/fnagi.2019.00070] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 03/12/2019] [Indexed: 01/08/2023] Open
Abstract
The argument is frequently made that the amyloid-β protein (Aβ) persists in the human genome because Alzheimer's disease (AD) primarily afflicts individuals over reproductive age and, therefore, there is low selective pressure for the peptide's elimination or modification. This argument is an important premise for AD amyloidosis models and therapeutic strategies that characterize Aβ as a functionless and intrinsically pathological protein. Here, we review if evolutionary theory and data on the genetics and biology of Aβ are consistent with low selective pressure for the peptide's expression in senescence. Aβ is an ancient neuropeptide expressed across vertebrates. Consistent with unusually high evolutionary selection constraint, the human Aβ sequence is shared by a majority of vertebrate species and has been conserved across at least 400 million years. Unlike humans, the overwhelming majority of vertebrate species do not cease reproduction in senescence and selection pressure is maintained into old age. Hence, low selective pressure in senescence does not explain the persistence of Aβ across the vertebrate genome. The "Grandmother hypothesis" (GMH) is the prevailing model explaining the unusual extended postfertile period of humans. In the GMH, high risk associated with birthing in old age has lead to early cessation of reproduction and a shift to intergenerational care of descendants. The rechanneling of resources to grandchildren by postreproductive individuals increases reproductive success of descendants. In the GMH model, selection pressure does not end following menopause. Thus, evolutionary models and phylogenetic data are not consistent with the absence of reproductive selection pressure for Aβ among aged vertebrates, including humans. Our analysis suggests an alternative evolutionary model for the persistence of Aβ in the vertebrate genome. Aβ has recently been identified as an antimicrobial effector molecule of innate immunity. High conservation across the Chordata phylum is consistent with strong positive selection pressure driving human Aβ's remarkable evolutionary longevity. Ancient origins and widespread conservation suggest the human Aβ sequence is highly optimized for its immune role. We detail our analysis and discuss how the emerging "Antimicrobial Protection Hypothesis" of AD may provide insights into possible evolutionary roles for Aβ in infection, aging, and disease etiology.
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Affiliation(s)
- Robert D. Moir
- Genetics and Aging Research Unit, Department of Neurology, MassGeneral Institute for Neurodegenerative Disease, Harvard Medical School – Massachusetts General Hospital, Boston, MA, United States
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17
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Christensen A, Pike CJ. APOE genotype affects metabolic and Alzheimer-related outcomes induced by Western diet in female EFAD mice. FASEB J 2019; 33:4054-4066. [PMID: 30509127 PMCID: PMC6404574 DOI: 10.1096/fj.201801756r] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/05/2018] [Indexed: 01/24/2023]
Abstract
Development of Alzheimer's disease (AD) is regulated by interactive effects of genetic and environmental risk factors. The most significant genetic risk factor for AD is the ε4 allele of apolipoprotein E ( APOE4), which has been shown to exert greater AD risk in women. An important modifiable AD risk factor is obesity and its associated metabolic dysfunctions. Whether APOE genotype might interact with obesity in females to regulate AD pathogenesis is unclear. To investigate this issue, we studied the effects of Western diet (WD) on female EFAD mice, a transgenic mouse model of AD that includes human APOE alleles ε3 (E3FAD) and ε4 (E4FAD). EFAD mice were fed either control (10% fat, 7% sugar) or WD (45% fat, 17% sugar), and both metabolic and neuropathologic outcomes were determined. Although E4FAD mice generally exhibited poorer metabolic status at baseline, E3FAD mice showed greater diet-induced metabolic impairments. Similarly, E4FAD mice exhibited higher levels of AD-related pathology overall, but only E3FAD showed significant increases on select measures of β-amyloid pathology after exposure to WD. These data demonstrate a gene-environment interaction between APOE and obesogenic diets in females. Understanding how AD-promoting effects of obesity are modulated by genetic factors will foster the identification of at-risk populations and development of preventive interventions.-Christensen, A., Pike, C. J. APOE genotype affects metabolic and Alzheimer-related outcomes induced by Western diet in female EFAD mice.
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Affiliation(s)
- Amy Christensen
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
| | - Christian J. Pike
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
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18
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Abstract
PURPOSE OF REVIEW Various groups have explored the effect of apolipoprotein E (APOE) on neurodegeneration through nutritional and metabolic alterations. In this review, we hope to summarize recent findings in humans as well as preclinical APOE models. RECENT FINDINGS Metabolic pathways including lipid metabolism appear to play a large role in the pathophysiology of Alzheimer's disease. Carrier status of the E4 variant of the APOE gene is the strongest genetic risk factor for Alzheimer's disease, and increasing evidence suggests that E4 carriers may respond differently to a host of dietary and metabolic-related treatments. A new appreciation is forming for the role of APOE in cerebral metabolism, and how nutritional factors may impact this role. SUMMARY Considering the role dietary factors play in APOE-associated cognitive decline will help us to understand how nutritional interventions may facilitate or mitigate disease progression.
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Affiliation(s)
- Brandon C. Farmer
- Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Lance A. Johnson
- Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Angela J. Hanson
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Puget Sound Healthcare System, Department of Medicine, University of Washington School of Medicine, Seattle, Washington, USA
- Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, Washington, USA
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19
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Castranio EL, Wolfe CM, Nam KN, Letronne F, Fitz NF, Lefterov I, Koldamova R. ABCA1 haplodeficiency affects the brain transcriptome following traumatic brain injury in mice expressing human APOE isoforms. Acta Neuropathol Commun 2018; 6:69. [PMID: 30049279 PMCID: PMC6062955 DOI: 10.1186/s40478-018-0569-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 07/12/2018] [Indexed: 02/07/2023] Open
Abstract
Expression of human Apolipoprotein E (APOE) modulates the inflammatory response in an isoform specific manner, with APOE4 isoform eliciting a stronger pro-inflammatory response, suggesting a possible mechanism for worse outcome following traumatic brain injury (TBI). APOE lipidation and stability is modulated by ATP-binding cassette transporter A1 (ABCA1), a transmembrane protein that transports lipids and cholesterol onto APOE. We examined the impact of Abca1 deficiency and APOE isoform expression on the response to TBI using 3-months-old, human APOE3+/+ (E3/Abca1+/+) and APOE4+/+ (E4/Abca1+/+) targeted replacement mice, and APOE3+/+ and APOE4+/+ mice with only one functional copy of the Abca1 gene (E3/Abca1+/-; E4/Abca1+/-). TBI-treated mice received a craniotomy followed by a controlled cortical impact (CCI) brain injury in the left hemisphere; sham-treated mice received the same surgical procedure without the impact. We performed RNA-seq using samples from cortices and hippocampi followed by genome-wide differential gene expression analysis. We found that TBI significantly impacted unique transcripts within each group, however, the proportion of unique transcripts was highest in E4/Abca1+/- mice. Additionally, we found that Abca1 haplodeficiency increased the expression of microglia sensome genes among only APOE4 injured mice, a response not seen in injured APOE3 mice, nor in either group of sham-treated mice. To identify gene networks, or modules, correlated to TBI, APOE isoform and Abca1 haplodeficiency, we used weighted gene co-expression network analysis (WGCNA). The module that positively correlated to TBI groups was associated with immune response and featured hub genes that were microglia-specific, including Trem2, Tyrobp, Cd68 and Hexb. The modules positively correlated with APOE4 isoform and negatively to Abca1 haplodeficient mice represented "protein translation" and "oxidation-reduction process", respectively. Our results reveal E4/Abca1+/- TBI mice have a distinct response to injury, and unique gene networks are associated with APOE isoform, Abca1 insufficiency and injury.
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Affiliation(s)
- Emilie L Castranio
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Cody M Wolfe
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Kyong Nyon Nam
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Florent Letronne
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Nicholas F Fitz
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Iliya Lefterov
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
| | - Radosveta Koldamova
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
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