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Ahmed H, Wang Y, Griffiths WJ, Levey AI, Pikuleva I, Liang SH, Haider A. Brain cholesterol and Alzheimer's disease: challenges and opportunities in probe and drug development. Brain 2024; 147:1622-1635. [PMID: 38301270 PMCID: PMC11068113 DOI: 10.1093/brain/awae028] [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: 03/04/2023] [Revised: 12/20/2023] [Accepted: 01/13/2024] [Indexed: 02/03/2024] Open
Abstract
Cholesterol homeostasis is impaired in Alzheimer's disease; however, attempts to modulate brain cholesterol biology have not translated into tangible clinical benefits for patients to date. Several recent milestone developments have substantially improved our understanding of how excess neuronal cholesterol contributes to the pathophysiology of Alzheimer's disease. Indeed, neuronal cholesterol was linked to the formation of amyloid-β and neurofibrillary tangles through molecular pathways that were recently delineated in mechanistic studies. Furthermore, remarkable advances in translational molecular imaging have now made it possible to probe cholesterol metabolism in the living human brain with PET, which is an important prerequisite for future clinical trials that target the brain cholesterol machinery in Alzheimer's disease patients-with the ultimate aim being to develop disease-modifying treatments. This work summarizes current concepts of how the biosynthesis, transport and clearance of brain cholesterol are affected in Alzheimer's disease. Further, current strategies to reverse these alterations by pharmacotherapy are critically discussed in the wake of emerging translational research tools that support the assessment of brain cholesterol biology not only in animal models but also in patients with Alzheimer's disease.
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Affiliation(s)
- Hazem Ahmed
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, CT 06510, USA
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Institute of Pharmaceutical Sciences ETH, 8093 Zurich, Switzerland
| | - Yuqin Wang
- Institute of Life Science, Swansea University Medical School, Swansea SA2 8PP, UK
| | - William J Griffiths
- Institute of Life Science, Swansea University Medical School, Swansea SA2 8PP, UK
| | - Allan I Levey
- Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Irina Pikuleva
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Steven H Liang
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ahmed Haider
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
- Department of Nuclear Medicine, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland
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2
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He Q, Shu H, Peng Y, Xu Y, Liu L, Zhou J, Zhao J, Xiong X, Li C. Untargeted metabolomics analysis of plasma metabolic characteristics in patients with acne and insulin resistance. Amino Acids 2023; 55:1417-1428. [PMID: 37726574 DOI: 10.1007/s00726-023-03320-2] [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: 05/24/2023] [Accepted: 08/21/2023] [Indexed: 09/21/2023]
Abstract
Acne vulgaris is a chronic inflammatory disease with high incidence, diverse clinical manifestations, poor clinical efficacy, and easy recurrence. Recent studies have found that the occurrence of acne is related to metabolic factors such as insulin resistance; however, the specific mechanism of action remains unclear. This study aimed to identify significantly different metabolites and related metabolic pathways in the serum of acne vulgaris patients with or without insulin resistance. LC-MS/MS was used to analyze serum samples from patients about acne with insulin resistance (n = 51) and acne without insulin resistance (n = 69) to identify significant metabolites and metabolic pathways. In this study, 18 significant differential metabolites were screened for the first time. In the positive-ion mode, the upregulated substances were creatine, sarcosine, D-proline, uracil, Phe-Phe, L-pipecolic acid, and DL-phenylalanine; the downregulated substances were tridecanoic acid (tridecylic acid), L-lysine, cyclohexylamine, sphingomyelin (d18:1/18:0), gamma-L-Glu-epsilon-L-Lys, and 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine. In the negative-ion mode, the upregulated substance was cholesterol sulfate, and the downregulated substances were D(-)-beta-hydroxybutyric acid, myristic acid, D-galacturonic acid, and dihydrothymine. Cholesterol sulfate showed the most significant expression among all differential metabolites (VIP = 7.3411). Based on the KEGG database, necroptosis and ABC transporters were the most significantly enriched metabolic pathways in this experiment. The differential metabolites and pathways identified in this study may provide new possibilities for the clinical diagnosis and development of targeted drugs for acne patients with insulin resistance.
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Affiliation(s)
- Qingqing He
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Huiling Shu
- Department of Dermatology, The People's Hospital of Chongzhou, Chengdu, Sichuan, China
| | - Yu Peng
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Yang Xu
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Li Liu
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Jie Zhou
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Juan Zhao
- Department of Dermatology, The Hejiang People's Hospital, Luzhou, Sichuan, China
| | - Xia Xiong
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China.
| | - Changqiang Li
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China.
- Department of Dermatology, The Hejiang People's Hospital, Luzhou, Sichuan, China.
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Fakhoury HMA, Elahi MA, Al Sarheed S, Al Dubayee M, Alshahrani A, Zhra M, Almassri A, Aljada A. Gene Expression Profiling of Peripheral Blood Mononuclear Cells in Type 2 Diabetes: An Exploratory Study. Medicina (B Aires) 2022; 58:medicina58121829. [PMID: 36557031 PMCID: PMC9787392 DOI: 10.3390/medicina58121829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/28/2022] [Accepted: 12/06/2022] [Indexed: 12/15/2022] Open
Abstract
Background and Objectives: Visceral obesity is associated with chronic low-grade inflammation that predisposes to metabolic syndrome. Indeed, infiltration of adipose tissue with immune-inflammatory cells, including 'classical' inflammatory M1 and anti-inflammatory 'alternative' M2 macrophages, causes the release of a variety of bioactive molecules, resulting in the metabolic complications of obesity. This study examined the relative expression of macrophage phenotypic surface markers, cholesterol efflux proteins, scavenger receptors, and adenosine receptors in human circulating peripheral blood mononuclear cells (PBMCs), isolated from patients with type 2 diabetes mellitus (T2DM), with the aim to phenotypically characterize and identify biomarkers for these ill-defined cells. Materials and Methodology: PBMCs were isolated from four groups of adults: Normal-weight non-diabetic, obese non-diabetic, newly diagnosed with T2DM, and T2DM on metformin. The mRNA expression levels of macrophage phenotypic surface markers (interleukin-12 (IL-12), C-X-C motif chemokine ligand 10 (CXCL10), C-C motif chemokine ligand 17 (CCL17), and C-C motif receptor 7 (CCR7)), cholesterol efflux proteins (ATP-binding cassette transporter-1 (ABCA1), ATP binding cassette subfamily G member 1 (ABCG1), and sterol 27-hydroxylase (CYP27A)), scavenger receptors (scavenger receptor-A (SR-A), C-X-C motif ligand 16 (CXCL16), and lectin-like oxidized LDL receptor-1 (LOX-1)), and adenosine receptors (adenosine A2A receptor (A2AR) and adenosine A3 receptor (A3R)) were measured using qRT-PCR. Results: In PBMCs from T2DM patients, the expression of IL-12, CCR7, ABCA1, and SR-A1 was increased, whereas the expression of CXCL10, CCL17, ABCG1,27-hydroxylase, LOX-1, A2AR and A3R was decreased. On the other hand, treatment with the antidiabetic drug, metformin, reduced the expression of IL-12 and increased the expression of 27-hydroxylase, LOX-1, CXCL16 and A2AR. Conclusions: PBMCs in the circulation of patients with T2DM express phenotypic markers that are different from those typically present in adipose tissue M1 and M2 macrophages and could be representative of metabolically activated macrophages (MMe)-like cells. Our findings suggest that metformin alters phenotypic markers of MMe-like cells in circulation.
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Affiliation(s)
- Hana M. A. Fakhoury
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
- Correspondence: (H.M.A.F.); (A.A.)
| | - Muhammad Affan Elahi
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Saud Al Sarheed
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia
| | - Mohammed Al Dubayee
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia
- King Abdullah International Medical Research Center (KAIMRC), Riyadh 11481, Saudi Arabia
- Department of Medicine, Ministry of National Guard Health Affairs (MNG-HA), Riyadh 11426, Saudi Arabia
| | - Awad Alshahrani
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh 11481, Saudi Arabia
- King Abdullah International Medical Research Center (KAIMRC), Riyadh 11481, Saudi Arabia
- Department of Medicine, Ministry of National Guard Health Affairs (MNG-HA), Riyadh 11426, Saudi Arabia
| | - Mahmoud Zhra
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Arwa Almassri
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Ahmad Aljada
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
- Correspondence: (H.M.A.F.); (A.A.)
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4
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GPSM1 impairs metabolic homeostasis by controlling a pro-inflammatory pathway in macrophages. Nat Commun 2022; 13:7260. [PMID: 36434066 PMCID: PMC9700814 DOI: 10.1038/s41467-022-34998-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 11/15/2022] [Indexed: 11/27/2022] Open
Abstract
G-protein-signaling modulator 1 (GPSM1) exhibits strong genetic association with Type 2 diabetes (T2D) and Body Mass Index in population studies. However, how GPSM1 carries out such control and in which types of cells are poorly understood. Here, we demonstrate that myeloid GPSM1 promotes metabolic inflammation to accelerate T2D and obesity development. Mice with myeloid-specific GPSM1 ablation are protected against high fat diet-induced insulin resistance, glucose dysregulation, and liver steatosis via repression of adipose tissue pro-inflammatory states. Mechanistically, GPSM1 deficiency mainly promotes TNFAIP3 transcription via the Gαi3/cAMP/PKA/CREB axis, thus inhibiting TLR4-induced NF-κB signaling in macrophages. In addition, we identify a small-molecule compound, AN-465/42243987, which suppresses the pro-inflammatory phenotype by inhibiting GPSM1 function, which could make it a candidate for metabolic therapy. Furthermore, GPSM1 expression is upregulated in visceral fat of individuals with obesity and is correlated with clinical metabolic traits. Overall, our findings identify macrophage GPSM1 as a link between metabolic inflammation and systemic homeostasis.
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Xue M, Yao T, Xue M, Francis F, Qin Y, Jia M, Li J, Gu X. Mechanism Analysis of Metabolic Fatty Liver on Largemouth bass (Micropterus salmoides) Based on Integrated Lipidomics and Proteomics. Metabolites 2022; 12:metabo12080759. [PMID: 36005631 PMCID: PMC9415018 DOI: 10.3390/metabo12080759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/12/2022] [Accepted: 08/14/2022] [Indexed: 11/26/2022] Open
Abstract
Metabolic fatty liver disease caused by high-starch diet restricted the intensive and sustainable development of carnivorous fish such as largemouth bass. In this study, the combination liver proteomic and lipidomic approach was employed to investigate the key signaling pathways and identify the critical biomarkers of fatty liver in largemouth bass. Joint analysis of the correlated differential proteins and lipids revealed nine common metabolic pathways; it was determined that FABP1 were significantly up-regulated in terms of transporting more triglycerides into the liver, while ABCA1 and VDAC1 proteins were significantly down-regulated in terms of preventing the transport of lipids and cholesterol out of the liver, leading to triglyceride accumulation in hepatocyte, eventually resulting in metabolic fatty liver disease. The results indicate that FABP1, ABCA1 and VDAC1 could be potential biomarkers for treating metabolic fatty liver disease of largemouth bass.
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Affiliation(s)
- Moyong Xue
- Feed Research Institute, Chinese Academy of Agricultural Science, Beijing 100081, China
- Functional & Evolutionary Entomology, Agro-Bio-Tech Gembloux, University of Liege, 5030 Gembloux, Belgium
- Institute of Animal Science, Chinese Academy of Agriculture Sciences, Beijing 100193, China
| | - Ting Yao
- Beijing Institute of Feed Control, Beijing 110108, China
| | - Min Xue
- Feed Research Institute, Chinese Academy of Agricultural Science, Beijing 100081, China
| | - Frédéric Francis
- Functional & Evolutionary Entomology, Agro-Bio-Tech Gembloux, University of Liege, 5030 Gembloux, Belgium
| | - Yuchang Qin
- Institute of Animal Science, Chinese Academy of Agriculture Sciences, Beijing 100193, China
| | - Ming Jia
- Feed Research Institute, Chinese Academy of Agricultural Science, Beijing 100081, China
| | - Junguo Li
- Feed Research Institute, Chinese Academy of Agricultural Science, Beijing 100081, China
| | - Xu Gu
- Feed Research Institute, Chinese Academy of Agricultural Science, Beijing 100081, China
- Correspondence:
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Lewandowski CT, Laham MS, Thatcher GR. Remembering your A, B, C's: Alzheimer's disease and ABCA1. Acta Pharm Sin B 2022; 12:995-1018. [PMID: 35530134 PMCID: PMC9072248 DOI: 10.1016/j.apsb.2022.01.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/27/2021] [Accepted: 01/07/2022] [Indexed: 12/24/2022] Open
Abstract
The function of ATP binding cassette protein A1 (ABCA1) is central to cholesterol mobilization. Reduced ABCA1 expression or activity is implicated in Alzheimer's disease (AD) and other disorders. Therapeutic approaches to boost ABCA1 activity have yet to be translated successfully to the clinic. The risk factors for AD development and progression, including comorbid disorders such as type 2 diabetes and cardiovascular disease, highlight the intersection of cholesterol transport and inflammation. Upregulation of ABCA1 can positively impact APOE lipidation, insulin sensitivity, peripheral vascular and blood–brain barrier integrity, and anti-inflammatory signaling. Various strategies towards ABCA1-boosting compounds have been described, with a bias toward nuclear hormone receptor (NHR) agonists. These agonists display beneficial preclinical effects; however, important side effects have limited development. In particular, ligands that bind liver X receptor (LXR), the primary NHR that controls ABCA1 expression, have shown positive effects in AD mouse models; however, lipogenesis and unwanted increases in triglyceride production are often observed. The longstanding approach, focusing on LXRβ vs. LXRα selectivity, is over-simplistic and has failed. Novel approaches such as phenotypic screening may lead to small molecule NHR modulators that elevate ABCA1 function without inducing lipogenesis and are clinically translatable.
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7
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Magalhaes MS, Smith P, Portman JR, Jackson-Jones LH, Bain CC, Ramachandran P, Michailidou Z, Stimson RH, Dweck MR, Denby L, Henderson NC, Jenkins SJ, Bénézech C. Role of Tim4 in the regulation of ABCA1 + adipose tissue macrophages and post-prandial cholesterol levels. Nat Commun 2021; 12:4434. [PMID: 34290249 PMCID: PMC8295389 DOI: 10.1038/s41467-021-24684-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/01/2021] [Indexed: 12/13/2022] Open
Abstract
Dyslipidemia is a main driver of cardiovascular diseases. The ability of macrophages to scavenge excess lipids implicate them as mediators in this process and understanding the mechanisms underlying macrophage lipid metabolism is key to the development of new treatments. Here, we investigated how adipose tissue macrophages regulate post-prandial cholesterol transport. Single-cell RNA sequencing and protected bone marrow chimeras demonstrated that ingestion of lipids led to specific transcriptional activation of a population of resident macrophages expressing Lyve1, Tim4, and ABCA1. Blocking the phosphatidylserine receptor Tim4 inhibited lysosomal activation and the release of post-prandial high density lipoprotein cholesterol following a high fat meal. Both effects were recapitulated by chloroquine, an inhibitor of lysosomal function. Moreover, clodronate-mediated cell-depletion implicated Tim4+ resident adipose tissue macrophages in this process. Thus, these data indicate that Tim4 is a key regulator of post-prandial cholesterol transport and adipose tissue macrophage function and may represent a novel pathway to treat dyslipidemia.
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Affiliation(s)
- M S Magalhaes
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - P Smith
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - J R Portman
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK
| | - L H Jackson-Jones
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster, UK
| | - C C Bain
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK
| | - P Ramachandran
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK
| | - Z Michailidou
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - R H Stimson
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - M R Dweck
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - L Denby
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - N C Henderson
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - S J Jenkins
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, UK
| | - C Bénézech
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
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8
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Dahik VD, Frisdal E, Le Goff W. Rewiring of Lipid Metabolism in Adipose Tissue Macrophages in Obesity: Impact on Insulin Resistance and Type 2 Diabetes. Int J Mol Sci 2020; 21:ijms21155505. [PMID: 32752107 PMCID: PMC7432680 DOI: 10.3390/ijms21155505] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 07/28/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022] Open
Abstract
Obesity and its two major comorbidities, insulin resistance and type 2 diabetes, represent worldwide health issues whose incidence is predicted to steadily rise in the coming years. Obesity is characterized by an accumulation of fat in metabolic tissues resulting in chronic inflammation. It is now largely accepted that adipose tissue inflammation underlies the etiology of these disorders. Adipose tissue macrophages (ATMs) represent the most enriched immune fraction in hypertrophic, chronically inflamed adipose tissue, and these cells play a key role in diet-induced type 2 diabetes and insulin resistance. ATMs are triggered by the continuous influx of dietary lipids, among other stimuli; however, how these lipids metabolically activate ATM depends on their nature, composition and localization. This review will discuss the fate and molecular programs elicited within obese ATMs by both exogenous and endogenous lipids, as they mediate the inflammatory response and promote or hamper the development of obesity-associated insulin resistance and type 2 diabetes.
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Hoekstra M, Van Eck M. Probucol-induced hypocholesterolemia is not associated with exacerbated foam cell formation in ABCG1 knockout mice. Atherosclerosis 2020; 296:91-92. [PMID: 32033777 DOI: 10.1016/j.atherosclerosis.2020.01.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 01/24/2020] [Indexed: 10/25/2022]
Affiliation(s)
- Menno Hoekstra
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Gorlaeus Laboratories, Einsteinweg 55, 2333CC, Leiden, the Netherlands.
| | - Miranda Van Eck
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Gorlaeus Laboratories, Einsteinweg 55, 2333CC, Leiden, the Netherlands
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Vincent V, Thakkar H, Aggarwal S, Mridha AR, Ramakrishnan L, Singh A. ATP-binding cassette transporter A1 (ABCA1) expression in adipose tissue and its modulation with insulin resistance in obesity. Diabetes Metab Syndr Obes 2019; 12:275-284. [PMID: 30881070 PMCID: PMC6395069 DOI: 10.2147/dmso.s186565] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
PURPOSE Adipose tissue dysfunction is at the center of metabolic dysfunctions associated with obesity. Through studies in isolated adipocytes and mouse models, ATP-binding cassette transporter A1 (ABCA1) expression in the adipose tissue has been shown to regulate high-density lipoprotein (HDL) cholesterol levels in the circulation and insulin sensitivity at both adipose tissue and whole-body levels. We aimed to explore the possible link between ABCA1 expression in the adipose tissue and metabolic derangements associated with obesity in humans. PATIENTS AND METHODS This exploratory study among individuals who were lean (body mass index [BMI]: 22.3±0.34 kg/m2, n=28) and obese (BMI: 44.48±5.3 kg/m2, n=34) compared the expression of ABCA1, adiponectin and GLUT4 (SLC2A4) in visceral and subcutaneous adipose tissue using quantitative real-time PCR and immunohistochemistry. Homeostatic model assessment for insulin resistance (HOMA-IR) and adipose tissue insulin resistance (adipo-IR) were used as insulin resistance markers. RESULTS Visceral adipose tissue from individuals who were obese had significantly lower ABCA1 (P=0.04 for mRNA and protein) and adiponectin (P=0.001 for mRNA) expression compared to that from lean individuals. Subcutaneous adipose tissue did not show any significant difference in the expression. When individuals were divided into insulin-sensitive (IS) and insulin-resistant (IR) groups based on HOMA-IR, IR individuals had lower ABCA1 (P=0.0001 for mRNA and P=0.009 for protein) expression compared to IS individuals in visceral adipose tissue, but not in subcutaneous adipose tissue. The difference was significant after adjusting for age, gender and BMI. ABCA1 mRNA expression in visceral adipose tissue correlated negatively with both HOMA-IR (r=-0.44, P=0.0003) and adipo-IR (r=-0.35, P=0.005) after adjusting for age, gender and BMI. ABCA1 expression in either visceral or subcutaneous adipose tissue did not have any significant correlation with HDL cholesterol levels or mean adipocyte area. CONCLUSION Obesity and insulin resistance are associated with lower expression of ABCA1 in visceral adipose tissue in humans.
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Affiliation(s)
- Vinnyfred Vincent
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India,
| | - Himani Thakkar
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India,
| | - Sandeep Aggarwal
- Department of Surgical Disciplines, All India Institute of Medical Sciences, New Delhi, India
| | - Asit Ranjan Mridha
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | - Lakshmy Ramakrishnan
- Department of Cardiac Biochemistry, All India Institute of Medical Sciences, New Delhi, India
| | - Archna Singh
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India,
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11
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Abstract
PURPOSE OF REVIEW Type 2 diabetes is associated with a characteristic dyslipidemia that may exacerbate cardiovascular risk. The causes of, and the effects of new antihyperglycemia medications on, this dyslipidemia, are under investigation. In an unexpected reciprocal manner, lowering LDL-cholesterol with statins slightly increases the risk of diabetes. Here we review the latest findings. RECENT FINDINGS The inverse relationship between LDL-cholesterol and diabetes has now been confirmed by multiple lines of evidence. This includes clinical trials, genetic instruments using aggregate single nucleotide polymorphisms, as well as at least eight individual genes - HMGCR, NPC1L1, HNF4A, GCKR, APOE, PCKS9, TM6SF2, and PNPLA3 - support this inverse association. Genetic and pharmacologic evidence suggest that HDL-cholesterol may also be inversely associated with diabetes risk. Regarding the effects of diabetes on lipoproteins, new evidence suggests that insulin resistance but not diabetes per se may explain impaired secretion and clearance of VLDL-triglycerides. Weight loss, bariatric surgery, and incretin-based therapies all lower triglycerides, whereas SGLT2 inhibitors may slightly increase HDL-cholesterol and LDL-cholesterol. SUMMARY Diabetes and lipoproteins are highly interregulated. Further research is expected to uncover new mechanisms governing the metabolism of glucose, fat, and cholesterol. This topic has important implications for treating type 2 diabetes and cardiovascular disease.
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MESH Headings
- Animals
- Cholesterol, HDL/genetics
- Cholesterol, HDL/metabolism
- Cholesterol, LDL/genetics
- Cholesterol, LDL/metabolism
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/therapy
- Dyslipidemias/genetics
- Dyslipidemias/metabolism
- Dyslipidemias/therapy
- Humans
- Lipoproteins, VLDL/genetics
- Lipoproteins, VLDL/metabolism
- Polymorphism, Single Nucleotide
- Triglycerides/genetics
- Triglycerides/metabolism
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Affiliation(s)
- Sei Higuchi
- Columbia University College of Physicians & Surgeons, Naomi Berrie Diabetes Center
- Department of Pathology and Cell Biology, New York, NY
| | - M Concepción Izquierdo
- Columbia University College of Physicians & Surgeons, Naomi Berrie Diabetes Center
- Department of Pathology and Cell Biology, New York, NY
| | - Rebecca A Haeusler
- Columbia University College of Physicians & Surgeons, Naomi Berrie Diabetes Center
- Department of Pathology and Cell Biology, New York, NY
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