1
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Chen J, Curcio CA, Crosson JN. Shotgun lipidomics of human subretinal fluids under rod-dominant retina reveals cone-dominated lipids. Exp Eye Res 2024; 240:109807. [PMID: 38278468 DOI: 10.1016/j.exer.2024.109807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 01/08/2024] [Accepted: 01/22/2024] [Indexed: 01/28/2024]
Abstract
Subretinal fluid (SRF) accumulates between photoreceptor outer segments and retinal pigment epithelium during rhegmatogenous retinal detachment. Biomolecular components such as lipids originate from cells surrounding the SRF. Knowledge of the composition of these molecules in SRF potentially provides mechanistic insight into the physiologic transfer of lipids between retinal tissue compartments. Using mass spectrometry and tandem mass spectrometry analysis on an electrospray ionization quadrupole-time-of-flight mass spectrometer, we identified a total of 115 lipid molecular species of 11 subclasses and 9 classes in two samples from two patients with rhegmatogenous retinal detachment. These included 47 glycerophosphocholines, 6 glycerophosphoethanolamines, 1 glycerophosphoinositol, 18 sphingomyelins, 9 cholesteryl esters, free cholesterol, 3 ceramides, 22 triacylglycerols and 8 free fatty acids. Glycerophosphocholines were of the highest intensity. By minimizing the formation of different adduct forms or clustering ions of different adducts, we determined the relative intensity of lipid molecular species within the same subclasses. The profiles were compared with those of retinal cells available in the published literature. The glycerophosphocholine profile of SRF was similar to that of cone outer segments, suggesting that outer segment degradation products are constitutively released into the interphotoreceptor matrix, appearing in SRF during detachment. This hypothesis was supported by the retinal distributions of corresponding lipid synthases' mRNA expression obtained from an online resource based on publicly available single-cell sequencing data. In contrast, based on lipid profiles and relevant gene expression in this study, the sources of free cholesterol and cholesteryl esters in SRF appeared more ambiguous, possibly reflecting that outer retina takes up plasma lipoproteins. Further studies to identify and quantify lipids in SRF will help better understand etiology of diseases relevant to outer retina.
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Affiliation(s)
- Jianzhong Chen
- Center for Biotechnology & Genomic Medicine, Medical College of Georgia, Augusta University, GA, United States; Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, GA, United States; Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States.
| | - Christine A Curcio
- Department of Ophthalmology and Visual Sciences, The University of Alabama at Birmingham, Birmingham, AL, United States.
| | - Jason N Crosson
- Department of Ophthalmology and Visual Sciences, The University of Alabama at Birmingham, Birmingham, AL, United States
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2
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El-Darzi N, Mast N, Li Y, Pikuleva IA. APOB100 transgenic mice exemplify how the systemic circulation content may affect the retina without altering retinal cholesterol input. Cell Mol Life Sci 2024; 81:52. [PMID: 38253888 PMCID: PMC10803575 DOI: 10.1007/s00018-023-05056-4] [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: 09/08/2023] [Revised: 10/24/2023] [Accepted: 11/17/2023] [Indexed: 01/24/2024]
Abstract
Apolipoprotein B (APOB) is a constituent of unique lipoprotein particles (LPPs) produced in the retinal pigment epithelium (RPE), which separates the neural retina from Bruch's membrane (BrM) and choroidal circulation. These LPPs accumulate with age in BrM and contribute to the development of age-related macular degeneration, a major blinding disease. The APOB100 transgenic expression in mice, which unlike humans lack the full-length APOB100, leads to lipid deposits in BrM. Herein, we further characterized APOB100 transgenic mice. We imaged mouse retina in vivo and assessed chorioretinal lipid distribution, retinal sterol levels, retinal cholesterol input, and serum content as well as tracked indocyanine green-bound LPPs in mouse plasma and retina after an intraperitoneal injection. Retinal function and differentially expressed proteins were also investigated. APOB100 transgenic mice had increased serum LDL content and an additional higher density HDL subpopulation; their retinal cholesterol levels (initially decreased) became normal with age. The LPP cycling between the RPE and choroidal circulation was increased. Yet, LPP trafficking from the RPE to the neural retina was limited, and total retinal cholesterol input did not change. There were lipid deposits in the RPE and BrM, and retinal function was impaired. Retinal proteomics provided mechanistic insights. Collectively, our data suggested that the serum LDL/HDL ratio may not affect retinal pathways of cholesterol input as serum LPP load is mainly handled by the RPE, which offloads LPP excess to the choroidal circulation rather than neural retina. Different HDL subpopulations should be considered in studies linking serum LPPs and age-related macular degeneration.
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Affiliation(s)
- Nicole El-Darzi
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Natalia Mast
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Yong Li
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA.
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3
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El-Darzi N, Mast N, Li Y, Dailey B, Kang M, Rhee DJ, Pikuleva IA. The normalizing effects of the CYP46A1 activator efavirenz on retinal sterol levels and risk factors for glaucoma in Apoj -/- mice. Cell Mol Life Sci 2023; 80:194. [PMID: 37392222 PMCID: PMC10314885 DOI: 10.1007/s00018-023-04848-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 07/03/2023]
Abstract
Apolipoprotein J (APOJ) is a multifunctional protein with genetic evidence suggesting an association between APOJ polymorphisms and Alzheimer's disease as well as exfoliation glaucoma. Herein we conducted ocular characterizations of Apoj-/- mice and found that their retinal cholesterol levels were decreased and that this genotype had several risk factors for glaucoma: increased intraocular pressure and cup-to-disk ratio and impaired retinal ganglion cell (RGC) function. The latter was not due to RGC degeneration or activation of retinal Muller cells and microglia/macrophages. There was also a decrease in retinal levels of 24-hydroxycholesterol, a suggested neuroprotectant under glaucomatous conditions and a positive allosteric modulator of N-methyl-D-aspartate receptors mediating the light-evoked response of the RGC. Therefore, Apoj-/- mice were treated with low-dose efavirenz, an allosteric activator of CYP46A1 which converts cholesterol into 24-hydroxycholesterol. Efavirenz treatment increased retinal cholesterol and 24-hydroxycholesterol levels, normalized intraocular pressure and cup-to-disk ratio, and rescued in part RGC function. Retinal expression of Abcg1 (a cholesterol efflux transporter), Apoa1 (a constituent of lipoprotein particles), and Scarb1 (a lipoprotein particle receptor) was increased in EVF-treated Apoj-/- mice, indicating increased retinal cholesterol transport on lipoprotein particles. Ocular characterizations of Cyp46a1-/- mice supported the beneficial efavirenz treatment effects via CYP46A1 activation. The data obtained demonstrate an important APOJ role in retinal cholesterol homeostasis and link this apolipoprotein to the glaucoma risk factors and retinal 24-hydroxycholesterol production by CYP46A1. As the CYP46A1 activator efavirenz is an FDA-approved anti-HIV drug, our studies suggest a new therapeutic approach for treatment of glaucomatous conditions.
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Affiliation(s)
- Nicole El-Darzi
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Natalia Mast
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Yong Li
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Brian Dailey
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Min Kang
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Douglas J Rhee
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Science, Case Western Reserve University, Cleveland, OH, 44106, USA.
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4
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Zaidi SAH, Lemtalsi T, Xu Z, Santana I, Sandow P, Labazi L, Caldwell RW, Caldwell RB, Rojas MA. Role of acyl-coenzyme A: cholesterol transferase 1 (ACAT1) in retinal neovascularization. J Neuroinflammation 2023; 20:14. [PMID: 36691048 PMCID: PMC9869542 DOI: 10.1186/s12974-023-02700-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 01/13/2023] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND We have investigated the efficacy of a new strategy to limit pathological retinal neovascularization (RNV) during ischemic retinopathy by targeting the cholesterol metabolizing enzyme acyl-coenzyme A: cholesterol transferase 1 (ACAT1). Dyslipidemia and cholesterol accumulation have been strongly implicated in promoting subretinal NV. However, little is known about the role of cholesterol metabolism in RNV. Here, we tested the effects of inhibiting ACAT1 on pathological RNV in the mouse model of oxygen-induced retinopathy (OIR). METHODS In vivo studies used knockout mice that lack the receptor for LDL cholesterol (LDLR-/-) and wild-type mice. The wild-type mice were treated with a specific inhibitor of ACAT1, K604 (10 mg/kg, i.p) or vehicle (PBS) during OIR. In vitro studies used human microglia exposed to oxygen-glucose deprivation (OGD) and treated with the ACAT1 inhibitor (1 μM) or PBS. RESULTS Analysis of OIR retinas showed that increased expression of inflammatory mediators and pathological RNV were associated with significant increases in expression of the LDLR, increased accumulation of neutral lipids, and formation of toxic levels of cholesterol ester (CE). Deletion of the LDLR completely blocked OIR-induced RNV and significantly reduced the AVA. The OIR-induced increase in CE formation was accompanied by significant increases in expression of ACAT1, VEGF and inflammatory factors (TREM1 and MCSF) (p < 0.05). ACAT1 was co-localized with TREM1, MCSF, and macrophage/microglia makers (F4/80 and Iba1) in areas of RNV. Treatment with K604 prevented retinal accumulation of neutral lipids and CE formation, inhibited RNV, and decreased the AVA as compared to controls (p < 0.05). The treatment also blocked upregulation of LDLR, ACAT1, TREM1, MCSF, and inflammatory cytokines but did not alter VEGF expression. K604 treatment of microglia cells also blocked the effects of OGD in increasing expression of ACAT1, TREM1, and MCSF without altering VEGF expression. CONCLUSIONS OIR-induced RNV is closely associated with increases in lipid accumulation and CE formation along with increased expression of LDLR, ACAT1, TREM1, and MCSF. Inhibiting ACAT1 blocked these effects and limited RNV independently of alterations in VEGF expression. This pathway offers a novel strategy to limit vascular injury during ischemic retinopathy.
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Affiliation(s)
- Syed A H Zaidi
- Vascular Biology Center, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912-2500, USA.,Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Tahira Lemtalsi
- Vascular Biology Center, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912-2500, USA.,Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Zhimin Xu
- Vascular Biology Center, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912-2500, USA.,Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
| | - Isabella Santana
- Vascular Biology Center, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912-2500, USA
| | - Porsche Sandow
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA.,Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, USA
| | - Leila Labazi
- Vascular Biology Center, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912-2500, USA
| | - Robert W Caldwell
- Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA.,Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, USA
| | - Ruth B Caldwell
- Vascular Biology Center, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912-2500, USA. .,Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA. .,Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA.
| | - Modesto A Rojas
- Vascular Biology Center, Augusta University, 1460 Laney Walker Blvd, Augusta, GA, 30912-2500, USA. .,Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA. .,Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, USA.
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5
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El-Darzi N, Mast N, Hammer SS, Dorweiler TF, Busik JV, Pikuleva IA. 2-Hydroxypropyl-β-cyclodextrin mitigates pathological changes in a mouse model of retinal cholesterol dyshomeostasis. J Lipid Res 2022; 64:100323. [PMID: 36586438 PMCID: PMC9883287 DOI: 10.1016/j.jlr.2022.100323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/22/2022] [Accepted: 12/12/2022] [Indexed: 12/30/2022] Open
Abstract
CYP46A1 is a CNS-specific enzyme, which eliminates cholesterol from the brain and retina by metabolism to 24-hydroxycholesterol, thus contributing to cholesterol homeostasis in both organs. 2-Hydroxypropyl-β-cyclodextrin (HPCD), a Food and Drug Administration-approved formulation vehicle, is currently being investigated off-label for treatment of various diseases, including retinal diseases. HPCD was shown to lower retinal cholesterol content in mice but had not yet been evaluated for its therapeutic benefits. Herein, we put Cyp46a1-/- mice on high fat cholesterol-enriched diet from 1 to 14 months of age (control group) and at 12 months of age, started to treat a group of these animals with HPCD until the age of 14 months. We found that as compared with mature and regular chow-fed Cyp46a1-/- mice, control group had about 6-fold increase in the retinal total cholesterol content, focal cholesterol and lipid deposition in the photoreceptor-Bruch's membrane region, and retinal macrophage activation. In addition, aged animals had cholesterol crystals at the photoreceptor-retinal pigment epithelium interface and changes in the Bruch's membrane ultrastructure. HPCD treatment mitigated all these manifestations of retinal cholesterol dyshomeostasis and altered the abundance of six groups of proteins (genetic information transfer, vesicular transport, and cytoskeletal organization, endocytosis and lysosomal processing, unfolded protein removal, lipid homeostasis, and Wnt signaling). Thus, aged Cyp46a1-/- mice on high fat cholesterol-enriched diet revealed pathological changes secondary to retinal cholesterol overload and supported further studies of HPCD as a potential therapeutic for age-related macular degeneration and diabetic retinopathy associated with retinal cholesterol dyshomeostasis.
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Affiliation(s)
- Nicole El-Darzi
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Natalia Mast
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Sandra S. Hammer
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Tim F. Dorweiler
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Julia V. Busik
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Irina A. Pikuleva
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, USA,For correspondence: Irina A. Pikuleva
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6
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Choudhary M, Tayyari F, Handa JT, Malek G. Characterization and identification of measurable endpoints in a mouse model featuring age-related retinal pathologies: a platform to test therapies. J Transl Med 2022; 102:1132-1142. [PMID: 36775353 PMCID: PMC10041606 DOI: 10.1038/s41374-022-00795-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/13/2022] [Accepted: 04/18/2022] [Indexed: 11/09/2022] Open
Abstract
Apolipoprotein B100 (apoB100) is the structural protein of cholesterol carriers including low-density lipoproteins. It is a constituent of sub-retinal pigment epithelial (sub-RPE) deposits and pro-atherogenic plaques, hallmarks of early dry age-related macular degeneration (AMD), an ocular neurodegenerative blinding disease, and cardiovascular disease, respectively. Herein, we characterized the retinal pathology of transgenic mice expressing mouse apoB100 in order to catalog their functional and morphological ocular phenotypes as a function of age and establish measurable endpoints for their use as a mouse model to test potential therapies. ApoB100 mice were found to exhibit an age-related decline in retinal function, as measured by electroretinogram (ERG) recordings of their scotopic a-wave, scotopic b-wave; and c-wave amplitudes. ApoB100 mice also displayed a buildup of the cholesterol carrier, apolipoprotein E (apoE) within and below the supporting extracellular matrix, Bruch's membrane (BrM), along with BrM thickening, and accumulation of thin diffuse electron-dense sub-RPE deposits, the severity of which increased with age. Moreover, the combination of apoB100 and advanced age were found to be associated with RPE morphological changes and the presence of sub-retinal immune cells as visualized in RPE-choroid flatmounts. Finally, aged apoB100 mice showed higher levels of circulating and ocular pro-inflammatory cytokines, supporting a link between age and increased local and systemic inflammation. Collectively, the data support the use of aged apoB100 mice as a platform to evaluate potential therapies for retinal degeneration, specifically drugs intended to target removal of lipids from Bruch's membrane and/or alleviate ocular inflammation.
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Affiliation(s)
- Mayur Choudhary
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Faryan Tayyari
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - James T Handa
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Goldis Malek
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA; Department of Pathology, Duke University School of Medicine, Durham, NC, USA.
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7
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Molins B, Mesquida M, Adan A. Bioengineering approaches for modelling retinal pathologies of the outer blood-retinal barrier. Prog Retin Eye Res 2022:101097. [PMID: 35840488 DOI: 10.1016/j.preteyeres.2022.101097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 05/31/2022] [Accepted: 06/29/2022] [Indexed: 11/18/2022]
Abstract
Alterations of the junctional complex of the outer blood-retinal barrier (oBRB), which is integrated by the close interaction of the retinal pigment epithelium, the Bruch's membrane, and the choriocapillaris, contribute to the loss of neuronal signalling and subsequent vision impairment in several retinal inflammatory disorders such as age-related macular degeneration and diabetic retinopathy. Reductionist approaches into the mechanisms that underlie such diseases have been hindered by the absence of adequate in vitro models using human cells to provide the 3D dynamic architecture that enables expression of the in vivo phenotype of the oBRB. Conventional in vitro cell models are based on 2D monolayer cellular cultures, unable to properly recapitulate the complexity of living systems. The main drawbacks of conventional oBRB models also emerge from the cell sourcing, the lack of an appropriate Bruch's membrane analogue, and the lack of choroidal microvasculature with flow. In the last years, the advent of organ-on-a-chip, bioengineering, and stem cell technologies is providing more advanced 3D models with flow, multicellularity, and external control over microenvironmental properties. By incorporating additional biological complexity, organ-on-a-chip devices can mirror physiologically relevant properties of the native tissue while offering additional set ups to model and study disease. In this review we first examine the current understanding of oBRB biology as a functional unit, highlighting the coordinated contribution of the different components to barrier function in health and disease. Then we describe recent advances in the use of pluripotent stem cells-derived retinal cells, Bruch's membrane analogues, and co-culture techniques to recapitulate the oBRB. We finally discuss current advances and challenges of oBRB-on-a-chip technologies for disease modelling.
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Affiliation(s)
- Blanca Molins
- Group of Ocular Inflammation: Clinical and Experimental Studies, Institut d'Investigacions Biomèdiques Agustí Pi I Sunyer (IDIBAPS), C/ Sabino de Arana 1, 08028, Barcelona, Spain.
| | - Marina Mesquida
- Group of Ocular Inflammation: Clinical and Experimental Studies, Institut d'Investigacions Biomèdiques Agustí Pi I Sunyer (IDIBAPS), C/ Sabino de Arana 1, 08028, Barcelona, Spain; Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Alfredo Adan
- Group of Ocular Inflammation: Clinical and Experimental Studies, Institut d'Investigacions Biomèdiques Agustí Pi I Sunyer (IDIBAPS), C/ Sabino de Arana 1, 08028, Barcelona, Spain; Instituto Clínic de Oftalmología, Hospital Clínic Barcelona, C/ Sabino de Arana 1, 08028, Barcelona, Spain
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8
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Lewandowski D, Sander CL, Tworak A, Gao F, Xu Q, Skowronska-Krawczyk D. Dynamic lipid turnover in photoreceptors and retinal pigment epithelium throughout life. Prog Retin Eye Res 2022; 89:101037. [PMID: 34971765 PMCID: PMC10361839 DOI: 10.1016/j.preteyeres.2021.101037] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/13/2022]
Abstract
The retinal pigment epithelium-photoreceptor interphase is renewed each day in a stunning display of cellular interdependence. While photoreceptors use photosensitive pigments to convert light into electrical signals, the RPE supports photoreceptors in their function by phagocytizing shed photoreceptor tips, regulating the blood retina barrier, and modulating inflammatory responses, as well as regenerating the 11-cis-retinal chromophore via the classical visual cycle. These processes involve multiple protein complexes, tightly regulated ligand-receptors interactions, and a plethora of lipids and protein-lipids interactions. The role of lipids in maintaining a healthy interplay between the RPE and photoreceptors has not been fully delineated. In recent years, novel technologies have resulted in major advancements in understanding several facets of this interplay, including the involvement of lipids in phagocytosis and phagolysosome function, nutrient recycling, and the metabolic dependence between the two cell types. In this review, we aim to integrate the complex role of lipids in photoreceptor and RPE function, emphasizing the dynamic exchange between the cells as well as discuss how these processes are affected in aging and retinal diseases.
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Affiliation(s)
- Dominik Lewandowski
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Christopher L Sander
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Aleksander Tworak
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Fangyuan Gao
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Qianlan Xu
- Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Dorota Skowronska-Krawczyk
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA.
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9
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Keeling E, Lynn SA, Koh YM, Scott JA, Kendall A, Gatherer M, Page A, Cagampang FR, Lotery AJ, Ratnayaka JA. A High Fat "Western-style" Diet Induces AMD-Like Features in Wildtype Mice. Mol Nutr Food Res 2022; 66:e2100823. [PMID: 35306732 PMCID: PMC9287010 DOI: 10.1002/mnfr.202100823] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 03/01/2022] [Indexed: 12/20/2022]
Abstract
Scope The intake of a “Western‐style” diet rich in fats is linked with developing retinopathies including age‐related macular degeneration (AMD). Wildtype mice are given a high fat diet (HFD) to determine how unhealthy foods can bring about retinal degeneration. Methods and results Following weaning, female C57BL/6 mice are maintained on standard chow (7% kcal fat, n = 29) or a HFD (45% kcal fat, n = 27) for 12 months. Animals were sacrificed following electroretinography (ERG) and their eyes analyzed by histology, confocal immunofluorescence, and transmission electron microscopy. HFD mice become obese, but showed normal retinal function compared to chow‐fed controls. However, diminished β3tubulin labeling of retinal cross‐sections indicated fewer/damaged neuronal processes in the inner plexiform layer. AMD‐linked proteins clusterin and TIMP3 accumulated in the retinal pigment epithelium (RPE) and Bruch's membrane (BrM). Neutral lipids also deposited in the outer retinae of HFD mice. Ultrastructural analysis revealed disorganized photoreceptor outer segments, collapsed/misaligned RPE microvilli, vacuoles, convoluted basolateral RPE infolds and BrM changes. Basal laminar‐like deposits were also present alongside abnormal choroidal endothelial cells. Conclusions We show that prolonged exposure to an unhealthy “Western‐style” diet alone can recapitulate early‐intermediate AMD‐like features in wildtype mice, highlighting the importance of diet and nutrition in the etiology of sight‐loss.
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Affiliation(s)
- Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK
| | - Savannah A Lynn
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK
| | - Yen Min Koh
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK
| | - Jenny A Scott
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK
| | - Aaron Kendall
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK
| | - Maureen Gatherer
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK
| | - Anton Page
- Biomedical Imaging Unit, University of Southampton, MP12, Tremona Road, Southampton, SO16 6YD, UK
| | - Felino R Cagampang
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD, UK
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK.,Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, MP806, Tremona Road, Southampton, SO16 6YD, UK
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10
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Ioannou GN, Lee SP, Linsley PS, Gersuk V, Yeh MM, Chen Y, Peng Y, Dutta M, Mascarinas G, Molla B, Cui JY, Savard C. Pcsk9 Deletion Promotes Murine Nonalcoholic Steatohepatitis and Hepatic Carcinogenesis: Role of Cholesterol. Hepatol Commun 2022; 6:780-794. [PMID: 34816633 PMCID: PMC8948564 DOI: 10.1002/hep4.1858] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 09/24/2021] [Accepted: 10/14/2021] [Indexed: 01/02/2023] Open
Abstract
Proprotein convertase subtilisin/kexin type 9 (Pcsk9) binds to hepatic low-density lipoprotein receptor (LDLR) and induces its internalization and degradation. Pcsk9 inhibition increases LDLR expression by hepatocytes, which causes increased uptake of circulating LDL, thereby reducing plasma LDL-cholesterol. However, by increasing the uptake of LDL by the liver, Pcsk9 inhibition increases the exposure of the liver to cholesterol, which may result in higher risk of steatohepatitis and ever carcinogenesis. We compared Pcsk9-/- knockout (KO) mice and appropriate wild-type (WT) controls of the same strain assigned to a high-fat (15%, wt/wt) diet for 9 months supplemented with 0.25%, 0.5%, or 0.75% dietary cholesterol. Pcsk9 KO mice on a high-fat, high-cholesterol diet exhibited higher levels of hepatic free cholesterol loading and hepatic cholesterol crystallization than their WT counterparts. Pcsk9 KO mice developed crown-like structures of macrophages surrounding cholesterol crystal-containing lipid droplets and hepatocytes, exhibited higher levels of apoptosis, and developed significantly more hepatic inflammation and fibrosis consistent with fibrosing steatohepatitis, including 5-fold and 11-fold more fibrosis at 0.5% and 0.75% dietary cholesterol, respectively. When injected with diethylnitrosamine, a hepatic carcinogen, early-in-life Pcsk9 KO mice were more likely to develop liver cancer than WT mice. Conclusion: Pcsk9 KO mice on high-cholesterol diets developed increased hepatic free cholesterol and cholesterol crystals and fibrosing steatohepatitis with a higher predisposition to liver cancer compared with WT mice. Future studies should evaluate whether patients on long-term treatment with anti-PSCK9 monoclonal antibodies are at increased risk of hepatic steatosis, steatohepatitis or liver cancer, while accounting for concurrent use of statins.
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Affiliation(s)
- George N. Ioannou
- Division of GastroenterologyDepartment of MedicineVeterans Affairs Puget Sound Health Care SystemSeattleWAUSA
- Division of GastroenterologyDepartment of MedicineUniversity of WashingtonSeattleWAUSA
- Research and DevelopmentVeterans Affairs Puget Sound Health Care SystemSeattleWAUSA
| | - Sum P. Lee
- Division of GastroenterologyDepartment of MedicineUniversity of WashingtonSeattleWAUSA
| | | | - Vivian Gersuk
- Systems ImmunologyBenaroya Research InstituteSeattleWAUSA
| | - Matthew M. Yeh
- Division of GastroenterologyDepartment of MedicineUniversity of WashingtonSeattleWAUSA
- Department of Laboratory Medicine and PathologyUniversity of WashingtonSeattleWAUSA
| | - Yen‐Ying Chen
- Department of Laboratory Medicine and PathologyUniversity of WashingtonSeattleWAUSA
- Department of Pathology and Laboratory MedicineSchool of MedicineTaipei Veterans General HospitalNational Yang‐Ming UniversityTaipeiTaiwan
- Present address:
Department of PathologyShuang Ho Hospital and School of MedicineCollege of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Yi‐Jen Peng
- Department of Laboratory Medicine and PathologyUniversity of WashingtonSeattleWAUSA
- Department of PathologyTri‐Service General HospitalNational Defense Medical CenterTaipeiTaiwan
| | - Moumita Dutta
- Department of Environmental and Occupational Health SciencesUniversity of WashingtonSeattleWAUSA
| | - Gabby Mascarinas
- Department of Environmental and Occupational Health SciencesUniversity of WashingtonSeattleWAUSA
| | - Bruk Molla
- Department of Environmental and Occupational Health SciencesUniversity of WashingtonSeattleWAUSA
| | - Julia Yue Cui
- Department of Environmental and Occupational Health SciencesUniversity of WashingtonSeattleWAUSA
| | - Christopher Savard
- Division of GastroenterologyDepartment of MedicineVeterans Affairs Puget Sound Health Care SystemSeattleWAUSA
- Division of GastroenterologyDepartment of MedicineUniversity of WashingtonSeattleWAUSA
- Research and DevelopmentVeterans Affairs Puget Sound Health Care SystemSeattleWAUSA
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11
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Yako T, Otsu W, Nakamura S, Shimazawa M, Hara H. Lipid Droplet Accumulation Promotes RPE Dysfunction. Int J Mol Sci 2022; 23:ijms23031790. [PMID: 35163712 PMCID: PMC8836556 DOI: 10.3390/ijms23031790] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/01/2022] [Accepted: 02/03/2022] [Indexed: 01/27/2023] Open
Abstract
Non-exudative age-related macular degeneration (AMD) is an irreversibly progressive retinal degenerative disease characterized by dysfunction and loss of retinal pigment epithelium (RPE). It has been suggested that impaired phagocytosis of the RPE is involved in the progression of non-exudative AMD, but the mechanism is not fully clear. In this study, we investigated the effect of lipid droplet accumulation on RPE function. Compared to young mice, the expression of lipid droplet-associated proteins increased in the RPE-choroidal complex, and lipid droplet in the RPE was observed in aged pigmented mice (12-month-old). Repeated treatment of the photoreceptor outer segment against ARPE-19 resulted in lipid droplets in ARPE-19 cells in vitro. Oleic acid treatment for ARPE-19 cells to form intracellular lipid droplet reduced the POS uptake into the ARPE-19 cells without causing a decrease in cell viability. The suppression of the POS uptake by lipid droplet formation improved by inhibiting lipid droplet formation using triacsin C. Moreover, the amount of intracellular reactive oxygen species was suppressed by the triacsin C treatment. These results indicate that lipid droplet is involved in the RPE dysfunction, and inhibiting lipid droplet formation may be a target for preventing and treating non-exudative AMD.
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Affiliation(s)
- Tomohiro Yako
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan; (T.Y.); (S.N.); (H.H.)
| | - Wataru Otsu
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan;
| | - Shinsuke Nakamura
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan; (T.Y.); (S.N.); (H.H.)
| | - Masamitsu Shimazawa
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan; (T.Y.); (S.N.); (H.H.)
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan;
- Laboratory of Collaborative Research for Innovative Drug Discovery, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
- Correspondence:
| | - Hideaki Hara
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan; (T.Y.); (S.N.); (H.H.)
- Laboratory of Collaborative Research for Innovative Drug Discovery, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
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12
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Coronado BNL, da Cunha FBS, de Oliveira RM, Nóbrega ODT, Ricart CAO, Fontes W, de Sousa MV, de Ávila MP, Martins AMA. Novel Possible Protein Targets in Neovascular Age-Related Macular Degeneration: A Pilot Study Experiment. Front Med (Lausanne) 2022; 8:692272. [PMID: 35155457 PMCID: PMC8828634 DOI: 10.3389/fmed.2021.692272] [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: 04/08/2021] [Accepted: 12/14/2021] [Indexed: 11/29/2022] Open
Abstract
Age-related macular degeneration (AMD) is among the world's leading causes of blindness. In its neovascular form (nAMD), around 25% of patients present further anatomical and visual deterioration due to persistence of neovascular activity, despite gold-standard treatment protocols using intravitreal anti-VEGF medications. Thus, to comprehend, the molecular pathways that drive choroidal neoangiogenesis, associated with the vascular endothelial growth factor (VEGF), are important steps to elucidate the mechanistic events underneath the disease development. This is a pilot study, a prospective, translational experiment, in a real-life context aiming to evaluate the protein profiles of the aqueous humor of 15 patients divided into three groups: group 1, composed of patients with nAMD, who demonstrated a good response to anti-VEGF intravitreal injections during follow-up (good responsive); group 2, composed of patients with anti-VEGF-resistant nAMD, who demonstrated choroidal neovascularization activity during follow-up (poor/non-responsive); and group 3, composed of control patients without systemic diseases or signs of retinopathy. For proteomic characterization of the groups, mass spectrometry (label-free LC-MS/MS) was used. A total of 2,336 proteins were identified, of which 185 were distinctly regulated and allowed the differentiation of the clinical conditions analyzed. Among those, 39 proteins, including some novel ones, were analyzed as potential disease effectors through their pathophysiological implications in lipid metabolism, oxidative stress, complement system, inflammatory pathways, and angiogenesis. So, this study suggests the participation of other promising biomarkers in neovascular AMD, in addition to the known VEGF.
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Affiliation(s)
- Bruno Nobre Lins Coronado
- Department of Medical Science, Faculty of Medicine, University of Brasilia, Brasilia, Brazil
- Faculty of Medicine, CESMAC University Center, Maceio, Brazil
- *Correspondence: Bruno Nobre Lins Coronado
| | | | - Raphaela Menezes de Oliveira
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | | | - Carlos André Ornelas Ricart
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - Wagner Fontes
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | - Marcelo Valle de Sousa
- Laboratory of Protein Chemistry and Biochemistry, Department of Cell Biology, Institute of Biological Sciences, University of Brasilia, Brasilia, Brazil
| | | | - Aline Maria Araújo Martins
- Department of Medical Science, Faculty of Medicine, University of Brasilia, Brasilia, Brazil
- Department of Health Science, School of Medicine, University Center of Brasilia (UniCEUB), Brasilia, Brazil
- Aline Maria Araújo Martins
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13
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Chuang JZ, Yang N, Nakajima N, Otsu W, Fu C, Yang HH, Lee MP, Akbar AF, Badea TC, Guo Z, Nuruzzaman A, Hsu KS, Dunaief JL, Sung CH. Retinal pigment epithelium-specific CLIC4 mutant is a mouse model of dry age-related macular degeneration. Nat Commun 2022; 13:374. [PMID: 35042858 PMCID: PMC8766482 DOI: 10.1038/s41467-021-27935-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 12/21/2021] [Indexed: 12/12/2022] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly. Dry AMD has unclear etiology and no treatment. Lipid-rich drusen are the hallmark of dry AMD. An AMD mouse model and insights into drusenogenesis are keys to better understanding of this disease. Chloride intracellular channel 4 (CLIC4) is a pleomorphic protein regulating diverse biological functions. Here we show that retinal pigment epithelium (RPE)-specific Clic4 knockout mice exhibit a full spectrum of functional and pathological hallmarks of dry AMD. Multidisciplinary longitudinal studies of disease progression in these mice support a mechanistic model that links RPE cell-autonomous aberrant lipid metabolism and transport to drusen formation.
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Affiliation(s)
- Jen-Zen Chuang
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
| | - Nan Yang
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Nobuyuki Nakajima
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
- Department of Urology, Tokai University, Kanagawa, Japan
| | - Wataru Otsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan
| | - Cheng Fu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Howard Hua Yang
- The Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Maxwell Ping Lee
- The Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | | | - Tudor Constantin Badea
- National Eye Institute, National institute of Health, Bethesda, MD, USA
- Research and Development Institute, Transilvania University of Brasov, School of Medicine, Brasov, Romania
| | - Ziqi Guo
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Afnan Nuruzzaman
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Kuo-Shun Hsu
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
- Sloan Kettering Cancer Institute, New York, NY, USA
| | - Joshua L Dunaief
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ching-Hwa Sung
- Department of Ophthalmology, Margaret M. Dyson Vision Research Institute, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
- Department of Cell and Developmental Biology, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
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14
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Sen M, Al-Amin M, Kicková E, Sadeghi A, Puranen J, Urtti A, Caliceti P, Salmaso S, Arango-Gonzalez B, Ueffing M. Retinal neuroprotection by controlled release of a VCP inhibitor from self-assembled nanoparticles. J Control Release 2021; 339:307-320. [PMID: 34606936 DOI: 10.1016/j.jconrel.2021.09.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/26/2021] [Accepted: 09/29/2021] [Indexed: 12/11/2022]
Abstract
Mutations in rhodopsin lead to its misfolding resulting in autosomal dominant retinitis pigmentosa (adRP). Pharmacological inhibition of the ATP-driven chaperone valosin-containing protein (VCP), a molecular checkpoint for protein quality control, slows down retinal degeneration in animal models. However, poor water-solubility of VCP inhibitors poses a challenge to their clinical translation as intravitreal injections for retinal treatment. In order to enable the delivery of VCP inhibitors, we have developed and investigated two formulations for the VCP inhibitor ML240. Nanoformulations of ML240 were obtained by using amphiphilic polymers methoxy-poly (ethylene glycol)5kDa-cholane (mPEG5kDa-cholane) and methoxy-poly (ethylene glycol)5kDa-cholesterol (mPEG5kDa-cholesterol). Both formulations increased the water-solubility of ML240 by two orders of magnitude and prolonged the drug released over ten days. In addition, encapsulation of ML240 in mPEG5kDa-cholane showed superior photoreceptor protection at lower drug concentrations, normalized rhodopsin localization, and alleviated inflammatory microglial responses in an ex vivo rat model of retinal degeneration. The study demonstrates the potential of VCP inhibitor nanoformulations to treat adRP, a pharmacologically orphan disease.
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Affiliation(s)
- Merve Sen
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany; Graduate Training Centre of Neuroscience, University of Tübingen, Tübingen, Germany
| | - Md Al-Amin
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Eva Kicková
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Amir Sadeghi
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Jooseppi Puranen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Arto Urtti
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland; Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Paolo Caliceti
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Stefano Salmaso
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Blanca Arango-Gonzalez
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
| | - Marius Ueffing
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
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15
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Farhan F, Almarhoun M, Wong A, Findlay AS, Bartholomew C, Williams MTS, Hurd TW, Shu X. Deletion of TSPO Causes Dysregulation of Cholesterol Metabolism in Mouse Retina. Cells 2021; 10:3066. [PMID: 34831289 PMCID: PMC8621976 DOI: 10.3390/cells10113066] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 12/22/2022] Open
Abstract
Cholesterol dysregulation has been implicated in age-related macular degeneration (AMD), the most common cause of visual impairment in the elderly. The 18 KDa translocator protein (TSPO) is a mitochondrial outer membrane protein responsible for transporting cholesterol from the mitochondrial outer membrane to the inner membrane. TSPO is highly expressed in retinal pigment epithelial (RPE) cells, and TSPO ligands have shown therapeutic potential for the treatment of AMD. Here, we characterized retinal pathology of Tspo knockout (KO) mice using histological, immunohistochemical, biochemical and molecular biological approaches. We found that Tspo KO mice had normal retinal morphology (by light microscopy) but showed elevated levels of cholesterol, triglycerides and phospholipids with perturbed cholesterol efflux in the RPE cells of Tspo KO mice. Expression of cholesterol-associated genes (Nr1h3, Abca1, Abcg1, Cyp27a1 and Cyp46a1) was significantly downregulated, and production of pro-inflammatory cytokines was markedly increased in Tspo KO retinas. Furthermore, microglial activation was also observed in Tspo KO mouse retinas. These findings provide new insights into the function of TSPO in the retina and may aid in the design of new therapeutic strategies for the treatment of AMD.
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Affiliation(s)
- Fahad Farhan
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (F.F.); (M.A.); (A.W.); (C.B.); (M.T.S.W.)
| | - Mohammad Almarhoun
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (F.F.); (M.A.); (A.W.); (C.B.); (M.T.S.W.)
| | - Aileen Wong
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (F.F.); (M.A.); (A.W.); (C.B.); (M.T.S.W.)
| | - Amy S. Findlay
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.S.F.); (T.W.H.)
| | - Chris Bartholomew
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (F.F.); (M.A.); (A.W.); (C.B.); (M.T.S.W.)
| | - Mark T. S. Williams
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (F.F.); (M.A.); (A.W.); (C.B.); (M.T.S.W.)
| | - Toby W. Hurd
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.S.F.); (T.W.H.)
| | - Xinhua Shu
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (F.F.); (M.A.); (A.W.); (C.B.); (M.T.S.W.)
- School of Basic Medical Sciences, Shaoyang University, Shaoyang 422000, China
- Department of Vision Science, Glasgow Caledonian University, Glasgow G4 0BA, UK
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16
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Biswas L, Ibrahim KS, Li X, Zhou X, Zeng Z, Craft J, Shu X. Effect of a TSPO ligand on retinal pigment epithelial cholesterol homeostasis in high-fat fed mice, implication for age-related macular degeneration. Exp Eye Res 2021; 208:108625. [PMID: 34022174 DOI: 10.1016/j.exer.2021.108625] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/19/2021] [Accepted: 05/11/2021] [Indexed: 02/07/2023]
Abstract
Age-related Macular Degeneration (AMD) is a major cause of sight impairment in the elderly with complex aetiology involving genetics and environment and with limited therapeutic options which have limited efficacy. We have previously shown in a mouse-model of the condition, induced by feeding a high fat diet, that adverse effects of the diet can be reversed by co-administration of the TSPO activator, etifoxine. We extend those observations showing improvements in retinal pigment epithelial (RPE) cells with decreased lipids and enhanced expression of cholesterol metabolism and transport enzymes. Further, etifoxine decreased levels of reactive oxygen species (ROS) in RPE and inflammatory cytokines in RPE and serum. With respect to gut microbiome, we found that organisms abundant in the high fat condition (e.g. in the genus Anaerotruncus and Oscillospira) and implicated in AMD, were much less abundant after etifoxine treatment. The changes in gut flora were associated with the predicted production of metabolites of benefit to the retina including tryptophan and other amino acids and taurine, an essential component of the retina necessary to counteract ROS. These novel observations strengthen earlier conclusions that the mechanisms behind improvements in etifoxine-induced retinal physiology involve an interaction between effects on the host and the gut microbiome.
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Affiliation(s)
- Lincoln Biswas
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, UK
| | - Khalid Subhi Ibrahim
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, UK; Department of Biology, Faculty of Science, University of Zakho, Kurdistan Region, Iraq
| | - Xing Li
- School of Basic Medical Sciences, Shaoyang University, Shaoyang, 422000, China
| | - Xinzhi Zhou
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, UK
| | - Zhihong Zeng
- College of Biological and Environmental Engineering, Changsha University, Changsha, Hunan, 410022, PR China
| | - John Craft
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, UK
| | - Xinhua Shu
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, UK; Department of Vision Science, Glasgow Caledonian University, UK; School of Basic Medical Sciences, Shaoyang University, Shaoyang, 422000, China.
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17
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Pouw AE, Greiner MA, Coussa RG, Jiao C, Han IC, Skeie JM, Fingert JH, Mullins RF, Sohn EH. Cell-Matrix Interactions in the Eye: From Cornea to Choroid. Cells 2021; 10:687. [PMID: 33804633 PMCID: PMC8003714 DOI: 10.3390/cells10030687] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/03/2021] [Accepted: 03/16/2021] [Indexed: 02/07/2023] Open
Abstract
The extracellular matrix (ECM) plays a crucial role in all parts of the eye, from maintaining clarity and hydration of the cornea and vitreous to regulating angiogenesis, intraocular pressure maintenance, and vascular signaling. This review focuses on the interactions of the ECM for homeostasis of normal physiologic functions of the cornea, vitreous, retina, retinal pigment epithelium, Bruch's membrane, and choroid as well as trabecular meshwork, optic nerve, conjunctiva and tenon's layer as it relates to glaucoma. A variety of pathways and key factors related to ECM in the eye are discussed, including but not limited to those related to transforming growth factor-β, vascular endothelial growth factor, basic-fibroblastic growth factor, connective tissue growth factor, matrix metalloproteinases (including MMP-2 and MMP-9, and MMP-14), collagen IV, fibronectin, elastin, canonical signaling, integrins, and endothelial morphogenesis consistent of cellular activation-tubulogenesis and cellular differentiation-stabilization. Alterations contributing to disease states such as wound healing, diabetes-related complications, Fuchs endothelial corneal dystrophy, angiogenesis, fibrosis, age-related macular degeneration, retinal detachment, and posteriorly inserted vitreous base are also reviewed.
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Affiliation(s)
- Andrew E. Pouw
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Mark A. Greiner
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Razek G. Coussa
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Chunhua Jiao
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Ian C. Han
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Jessica M. Skeie
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
| | - John H. Fingert
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Robert F. Mullins
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Elliott H. Sohn
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA 52242, USA; (A.E.P.); (M.A.G.); (R.G.C.); (C.J.); (I.C.H.); (J.M.S.); (J.H.F.); (R.F.M.)
- Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
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18
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Zhang X, Sivaprasad S. Drusen and pachydrusen: the definition, pathogenesis, and clinical significance. Eye (Lond) 2020; 35:121-133. [PMID: 33208847 DOI: 10.1038/s41433-020-01265-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 10/20/2020] [Accepted: 10/28/2020] [Indexed: 12/22/2022] Open
Abstract
The pachychoroid disease spectrum encompasses seven major retinal conditions including central serous chorioretinopathy (CSC), polypoidal choroidal vasculopathy (PCV), and pachychoroid neovasculopathy or type I macular neovascularisation (MNV) secondary to chronic persistent thickening and dysfunction of the choroidal vasculature. Drusen are focal yellow-white deposits of extracellular debris, which consist of complement proteins, esterified and nonesterified cholesterol, apolipoproteins, carbohydrates, and trace elements, above the retinal pigment epithelium (RPE) or between the RPE and Bruch's membrane. Although drusen are an essential disease precursor of advanced age-related macular degeneration (AMD), a new entity "pachydrusen" has been identified to be associated with some of the enitites that constitute the pachychoroid spectrum. It remains to be determined what the exact differences are between soft drusen, pseudodrusen, and pachydrusen in terms of phenotype, genotype, and pathogenesis. Improving our knowledge in these areas will inevitably improve our understanding of their clinical significance especially as in disease prediction in AMD and the pachychroid spectrum disorders. It remains controversial whether PCV is a subtype of AMD. Understanding the pathogenesis of different types of drusen may also help in addressing if phenotype and/or genotype of type 1 MNV associated with pachychoroid are similar to type 1 MNV related to AMD. Furthermore, because pachydrusen links two pachychoroid diseases, CSC and PCV, it is also of great interest to investigate if CSC is an early stage or a predictor of PCV in future research. In this review, we share our experience in clinical practice and the latest published evidence-based literature to emphasize the differences and similarities in morphology, pathogenesis, and clinical significance of drusen and pachydrusen, a new member of the pachychoroid spectrum disorders.
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Affiliation(s)
- Xinyuan Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, PR China.
| | - Sobha Sivaprasad
- NIHR Moorfields Biomedical Research Centre, Moorfields Eye Hospital, London, UK
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19
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Nie J, Yang J, Wei Y, Wei X. The role of oxidized phospholipids in the development of disease. Mol Aspects Med 2020; 76:100909. [PMID: 33023753 DOI: 10.1016/j.mam.2020.100909] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/29/2020] [Accepted: 09/21/2020] [Indexed: 02/05/2023]
Abstract
Oxidized phospholipids (OxPLs), complex mixtures of phospholipid oxidation products generated during normal or pathological processes, are increasingly recognized to show bioactive effects on many cellular signalling pathways. There is a growing body of evidence showing that OxPLs play an important role in many diseases, so it is essential to define the specific role of OxPLs in different diseases for the design of disease therapies. In vastly diverse pathological processes, OxPLs act as pro-inflammatory agents and contribute to the progression of many diseases; in addition, they play a role in anti-inflammatory processes, promoting the dissipation of inflammation and inhibiting the progression of some diseases. In addition to participating in the regulation of inflammatory responses, OxPLs affect the occurrence and development of diseases through other pathways, such as apoptosis promotion. In this review, the different and even opposite effects of different OxPL molecular species are discussed. Furthermore, the specific effects of OxPLs in various diseases, as well as the receptor and cellular mechanisms involved, are summarized.
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Affiliation(s)
- Ji Nie
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China; Department of Respiration, First People's Hospital of Yunnan Province, Yunnan, 650032, China; The Affiliated Hospital of Kunming University of Science and Technology, Kunming, Yunnan, 650032, China
| | - Jing Yang
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China; Melanoma and Sarcoma Medical Oncology Unit, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 651 Dongfeng Road East, Guangzhou, 510060, China; State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
| | - Yuquan Wei
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiawei Wei
- Laboratory of Aging Research and Cancer Drug Target, State Key Laboratory of Biotherapy, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China.
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20
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Go YM, Zhang J, Fernandes J, Litwin C, Chen R, Wensel TG, Jones DP, Cai J, Chen Y. MTOR-initiated metabolic switch and degeneration in the retinal pigment epithelium. FASEB J 2020; 34:12502-12520. [PMID: 32721041 DOI: 10.1096/fj.202000612r] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 06/23/2020] [Accepted: 07/07/2020] [Indexed: 02/06/2023]
Abstract
The retinal pigment epithelium (RPE) is a particularly vulnerable tissue to age-dependent degeneration. Over the life span, the RPE develops an expanded endo-lysosomal compartment to maintain the high efficiency of phagocytosis and degradation of photoreceptor outer segments (POS) necessary for photoreceptor survival. As the assembly and activation of the mechanistic target of rapamycin complex 1 (mTORC1) occur on the lysosome surface, increased lysosome mass with aging leads to higher mTORC1 activity. The functional consequences of hyperactive mTORC1 in the RPE are unclear. In the current study, we used integrated high-resolution metabolomic and genomic approaches to examine mice with RPE-specific deletion of the tuberous sclerosis 1 (Tsc1) gene which encodes an upstream suppressor of mTORC1. Our data show that RPE cells with constitutively high mTORC1 activity were reprogramed to be hyperactive in glucose and lipid metabolism. Lipolysis was suppressed, mitochondrial carnitine shuttle was inhibited, while genes involved in fatty acid (FA) biosynthesis were upregulated. The metabolic changes occurred prior to structural changes of RPE and retinal degeneration. These findings have revealed cellular events and intrinsic mechanisms that contribute to lipid accumulation in the RPE cells during aging and age-related degeneration.
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Affiliation(s)
- Young-Mi Go
- Department of Medicine, Emory University, Atlanta, GA, USA
| | - Jing Zhang
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, USA
| | - Jolyn Fernandes
- Department of Medicine, Emory University, Atlanta, GA, USA.,Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Christopher Litwin
- Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Rui Chen
- Department of Genetics, Baylor College of Medicine, Houston, TX, USA.,Department of Biochemistry, Baylor College of Medicine, Houston, TX, USA
| | - Theodore G Wensel
- Department of Biochemistry, Baylor College of Medicine, Houston, TX, USA
| | - Dean P Jones
- Department of Medicine, Emory University, Atlanta, GA, USA
| | - Jiyang Cai
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, USA.,Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Yan Chen
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, USA.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.,Department of Biochemistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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21
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Oxidative stress in the retina and retinal pigment epithelium (RPE): Role of aging, and DJ-1. Redox Biol 2020; 37:101623. [PMID: 32826201 PMCID: PMC7767746 DOI: 10.1016/j.redox.2020.101623] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 12/15/2022] Open
Abstract
High levels of oxidative radicals generated by daily light exposure and high metabolic rate suggest that the antioxidant machinery of the retina and retinal pigment epithelium (RPE) is crucial for their survival. DJ-1 is a redox-sensitive protein that has been shown to have neuroprotective function in the brain in Parkinson's disease and other neurodegenerative diseases. Here, we analyzed the role of DJ-1 in the retina during oxidative stress and aging. We induced low-level oxidative stress in young (3-month-old) and old (15-month-old) C57BL/6J (WT) and DJ-1 knockout (KO) mice and evaluated effects in the RPE and retina. Absence of DJ-1 resulted in increased retinal dysfunction in response to low levels of oxidative stress. Our findings suggest that loss of DJ-1 affects the RPE antioxidant machinery, rendering it unable to combat and neutralize low-level oxidative stress, irrespective of age. Moreover, they draw a parallel to the retinal degeneration observed in AMD, where the occurrence of genetic variants may leave the retina and RPE unable to fight sustained, low-levels of oxidative stress. Antioxidants are upregulated in young DJ-1 KO RPE but downregulated in the retina. DJ-1 KO retinas are degenerated under low-level oxidative stress, regardless of age. Retinas of both young C57BL and DJ-1 KO were able to regulate antioxidant genes upon low-level oxidative stress. Retinas of both aged C57BL and DJ-1 KO were unable to regulate antioxidant genes upon low-level oxidative stress. RPE of aged C57BLl mice upregulated some antioxidant genes.
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22
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Choudhary M, Ismail EN, Yao PL, Tayyari F, Radu RA, Nusinowitz S, Boulton ME, Apte RS, Ruberti JW, Handa JT, Tontonoz P, Malek G. LXRs regulate features of age-related macular degeneration and may be a potential therapeutic target. JCI Insight 2020; 5:131928. [PMID: 31829999 DOI: 10.1172/jci.insight.131928] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 12/05/2019] [Indexed: 12/11/2022] Open
Abstract
Effective treatments and animal models for the most prevalent neurodegenerative form of blindness in elderly people, called age-related macular degeneration (AMD), are lacking. Genome-wide association studies have identified lipid metabolism and inflammation as AMD-associated pathogenic pathways. Given liver X receptors (LXRs), encoded by the nuclear receptor subfamily 1 group H members 2 and 3 (NR1H3 and NR1H2), are master regulators of these pathways, herein we investigated the role of LXR in human and mouse eyes as a function of age and disease and tested the therapeutic potential of targeting LXR. We identified immunopositive LXR fragments in human extracellular early dry AMD lesions and a decrease in LXR expression within the retinal pigment epithelium (RPE) as a function of age. Aged mice lacking LXR presented with isoform-dependent ocular pathologies. Specifically, loss of the Nr1h3 isoform resulted in pathobiologies aligned with AMD, supported by compromised visual function, accumulation of native and oxidized lipids in the outer retina, and upregulation of ocular inflammatory cytokines, while absence of Nr1h2 was associated with ocular lipoidal degeneration. LXR activation not only ameliorated lipid accumulation and oxidant-induced injury in RPE cells but also decreased ocular inflammatory markers and lipid deposition in a mouse model, thereby providing translational support for pursuing LXR-active pharmaceuticals as potential therapies for dry AMD.
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Affiliation(s)
- Mayur Choudhary
- Duke Eye Center, Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Ebraheim N Ismail
- Department of Bioengineering, Northeastern University, Boston, Massachusetts, USA
| | - Pei-Li Yao
- Duke Eye Center, Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Faryan Tayyari
- Duke Eye Center, Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Roxana A Radu
- Stein Eye Institute, Department of Ophthalmology, UCLA, Los Angeles, California, USA
| | - Steven Nusinowitz
- Stein Eye Institute, Department of Ophthalmology, UCLA, Los Angeles, California, USA
| | - Michael E Boulton
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Rajendra S Apte
- Department of Ophthalmology and Visual Sciences, Washington University in Saint Louis School of Medicine, Saint Louis, Missouri, USA
| | - Jeffrey W Ruberti
- Department of Bioengineering, Northeastern University, Boston, Massachusetts, USA
| | - James T Handa
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
| | - Goldis Malek
- Duke Eye Center, Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, USA.,Department of Pathology, Duke University School of Medicine, Durham, North Carolina, USA
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23
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Ioannou GN, Landis CS, Jin GY, Haigh WG, Farrell GC, Kuver R, Lee SP, Savard C. Cholesterol Crystals in Hepatocyte Lipid Droplets Are Strongly Associated With Human Nonalcoholic Steatohepatitis. Hepatol Commun 2019; 3:776-791. [PMID: 31168512 PMCID: PMC6545865 DOI: 10.1002/hep4.1348] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 03/04/2019] [Indexed: 12/19/2022] Open
Abstract
It is unclear what drives the development of fibrosing nonalcoholic steatohepatitis (NASH). We aimed to determine whether cholesterol crystallization within hepatocyte lipid droplets (LDs) distinguishes patients with fibrosing NASH from patients with isolated hepatic steatosis and to study pathways leading to cholesterol accumulation in hepatocyte LDs. Patients with fibrosing NASH (n = 16) were compared to patients with isolated steatosis (n = 14). Almost all patients with fibrosing NASH had free cholesterol staining by filipin (16/16) and cholesterol crystals (15/16) in hepatocyte LDs, mostly in association with the LD membrane, compared to only 3/14 with cholesterol crystals and 3/14 with faint filipin staining in patients with isolated steatosis (P < 0.05). We were unable to identify significant differences in the expression of genes in liver tissue related to cholesterol homeostasis or LD proteins between patients with fibrosing NASH and isolated steatosis. Human hepatoma cell line (HepG2) cells were supplemented with low-density lipoprotein (LDL)-cholesterol and oleic acid to develop large LDs, similar to those observed in patients with NASH. Fluorescent markers were used to track the uptake and intracellular trafficking of LDL-cholesterol. LDL-cholesterol was taken up by HepG2 cells and transported through the endosomal-lysosomal compartment directly to LDs, suggesting direct contact sites between late endosomes and LDs. Exposure of HepG2 cells to LDL-cholesterol resulted in a high concentration of cholesterol and cholesterol crystallization in LDs. Conclusion: Excess cholesterol is stored in the liver primarily within hepatocyte LDs where it can crystallize. Our findings are best explained by direct transport of cholesterol from late endosomes/lysosomes to LDs in hepatocytes. We found a strong association between the presence of LD cholesterol crystals and the development of fibrosing NASH in humans, suggesting a causal relationship.
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Affiliation(s)
- George N Ioannou
- Division of Gastroenterology, Department of Medicine Veterans Affairs Puget Sound Health Care System Seattle WA.,Division of Gastroenterology, Department of Medicine University of Washington Seattle WA.,Research and Development Veterans Affairs Puget Sound Health Care System Seattle WA
| | - Charles S Landis
- Division of Gastroenterology, Department of Medicine University of Washington Seattle WA
| | - Ga-Young Jin
- Research and Development Veterans Affairs Puget Sound Health Care System Seattle WA
| | - W Geoffrey Haigh
- Research and Development Veterans Affairs Puget Sound Health Care System Seattle WA
| | - Geoffrey C Farrell
- Liver Research Group Australian National University Medical School at the Canberra Hospital Garran Australia
| | - Rahul Kuver
- Division of Gastroenterology, Department of Medicine University of Washington Seattle WA
| | - Sum P Lee
- Division of Gastroenterology, Department of Medicine University of Washington Seattle WA
| | - Christopher Savard
- Division of Gastroenterology, Department of Medicine Veterans Affairs Puget Sound Health Care System Seattle WA.,Division of Gastroenterology, Department of Medicine University of Washington Seattle WA.,Research and Development Veterans Affairs Puget Sound Health Care System Seattle WA
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24
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Rudolf M, Curcio CA, Schlötzer-Schrehardt U, Sefat AMM, Tura A, Aherrahrou Z, Brinkmann M, Grisanti S, Miura Y, Ranjbar M. Apolipoprotein A-I Mimetic Peptide L-4F Removes Bruch's Membrane Lipids in Aged Nonhuman Primates. ACTA ACUST UNITED AC 2019; 60:461-472. [DOI: 10.1167/iovs.18-25786] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Martin Rudolf
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | | | - Armin Mir Mohi Sefat
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
| | - Aysegül Tura
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
| | - Zouhair Aherrahrou
- Institute for Cardiogenetics, University of Lübeck, Lübeck, Germany
- German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany
- University Heart Centre Lübeck, Lübeck, Germany
| | - Max Brinkmann
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Laboratory for Angiogenesis & Ocular Cell Transplantation, University of Lübeck, Lübeck, Germany
| | | | - Yoko Miura
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Translational AMD Research Group Lübeck, University of Lübeck, Lübeck, Germany
- Institute of Biomedical Optics, University of Lübeck, Lübeck, Germany
| | - Mahdy Ranjbar
- Department of Ophthalmology, University of Lübeck, Lübeck, Germany
- Laboratory for Angiogenesis & Ocular Cell Transplantation, University of Lübeck, Lübeck, Germany
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25
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Brown CN, Green BD, Thompson RB, den Hollander AI, Lengyel I. Metabolomics and Age-Related Macular Degeneration. Metabolites 2018; 9:metabo9010004. [PMID: 30591665 PMCID: PMC6358913 DOI: 10.3390/metabo9010004] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 12/11/2022] Open
Abstract
Age-related macular degeneration (AMD) leads to irreversible visual loss, therefore, early intervention is desirable, but due to its multifactorial nature, diagnosis of early disease might be challenging. Identification of early markers for disease development and progression is key for disease diagnosis. Suitable biomarkers can potentially provide opportunities for clinical intervention at a stage of the disease when irreversible changes are yet to take place. One of the most metabolically active tissues in the human body is the retina, making the use of hypothesis-free techniques, like metabolomics, to measure molecular changes in AMD appealing. Indeed, there is increasing evidence that metabolic dysfunction has an important role in the development and progression of AMD. Therefore, metabolomics appears to be an appropriate platform to investigate disease-associated biomarkers. In this review, we explored what is known about metabolic changes in the retina, in conjunction with the emerging literature in AMD metabolomics research. Methods for metabolic biomarker identification in the eye have also been discussed, including the use of tears, vitreous, and aqueous humor, as well as imaging methods, like fluorescence lifetime imaging, that could be translated into a clinical diagnostic tool with molecular level resolution.
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Affiliation(s)
- Connor N Brown
- Wellcome-Wolfson Institute for Experimental Medicine (WWIEM), Queen's University Belfast, Belfast BT9 7BL, UK.
| | - Brian D Green
- Institute for Global Food Security (IGFS), Queen's University Belfast, Belfast BT9 6AG, UK.
| | - Richard B Thompson
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA.
| | - Anneke I den Hollander
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen 6525 EX, The Netherlands.
| | - Imre Lengyel
- Wellcome-Wolfson Institute for Experimental Medicine (WWIEM), Queen's University Belfast, Belfast BT9 7BL, UK.
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26
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Curcio CA. Soft Drusen in Age-Related Macular Degeneration: Biology and Targeting Via the Oil Spill Strategies. Invest Ophthalmol Vis Sci 2018; 59:AMD160-AMD181. [PMID: 30357336 PMCID: PMC6733535 DOI: 10.1167/iovs.18-24882] [Citation(s) in RCA: 188] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AMD is a major cause of legal blindness in older adults approachable through multidisciplinary research involving human tissues and patients. AMD is a vascular-metabolic-inflammatory disease, in which two sets of extracellular deposits, soft drusen/basal linear deposit (BLinD) and subretinal drusenoid deposit (SDD), confer risk for end-stages of atrophy and neovascularization. Understanding how deposits form can lead to insights for new preventions and therapy. The topographic correspondence of BLinD and SDD with cones and rods, respectively, suggest newly realized exchange pathways among outer retinal cells and across Bruch's membrane and the subretinal space, in service of highly evolved, eye-specific physiology. This review focuses on soft drusen/BLinD, summarizing evidence that a major ultrastructural component is large apolipoprotein B,E-containing, cholesterol-rich lipoproteins secreted by the retinal pigment epithelium (RPE) that offload unneeded lipids of dietary and outer segment origin to create an atherosclerosis-like progression in the subRPE-basal lamina space. Clinical observations and an RPE cell culture system combine to suggest that soft drusen/BLinD form when secretions of functional RPE back up in the subRPE-basal lamina space by impaired egress across aged Bruch's membrane-choriocapillary endothelium. The soft drusen lifecycle includes growth, anterior migration of RPE atop drusen, then collapse, and atrophy. Proof-of-concept studies in humans and animal models suggest that targeting the “Oil Spill in Bruch's membrane” offers promise of treating a process in early AMD that underlies progression to both end-stages. A companion article addresses the antecedents of soft drusen within the biology of the macula.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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27
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Rajapakse D, Peterson K, Mishra S, Wistow G. Serum starvation of ARPE-19 changes the cellular distribution of cholesterol and Fibulin3 in patterns reminiscent of age-related macular degeneration. Exp Cell Res 2017; 361:333-341. [PMID: 29097185 PMCID: PMC5701823 DOI: 10.1016/j.yexcr.2017.10.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 10/25/2017] [Accepted: 10/28/2017] [Indexed: 11/29/2022]
Abstract
Retinal pigment epithelium (RPE) has been implicated as key source of cholesterol-rich deposits at Bruch's membrane (BrM) and in drusen in aging human eye. We have shown that serum-deprivation of confluent RPE cells is associated with upregulation of cholesterol synthesis and accumulation of unesterified cholesterol (UC). Here we investigate the cellular processes involved in this response. We compared the distribution and localization of UC and esterified cholesterol (EC); the age-related macular degeneration (AMD) associated EFEMP1/Fibulin3 (Fib3); and levels of acyl-coenzyme A (CoA): cholesterol acyltransferases (ACAT) ACAT1, ACAT2 and Apolipoprotein B (ApoB) in ARPE-19 cells cultured in serum-supplemented and serum-free media. The results were compared with distributions of these lipids and proteins in human donor eyes with AMD. Serum deprivation of ARPE-19 was associated with increased formation of FM dye-positive membrane vesicles, many of which co-labeled for UC. Additionally, UC colocalized with Fib3 in distinct granules. By day 5, serum-deprived cells grown on transwells secreted Fib3 basally into the matrix. While mRNA and protein levels of ACTA1 were constant over several days of serum-deprivation, ACAT2 levels increased significantly after serum-deprivation, suggesting increased formation of EC. The lower levels of intracellular EC observed under serum-deprivation were associated with increased formation and secretion of ApoB. The responses to serum-deprivation in RPE-derived cells: accumulation and secretion of lipids, lipoproteins, and Fib3 are very similar to patterns seen in human donor eyes with AMD and suggest that this model mimics processes relevant to disease progression.
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Affiliation(s)
- Dinusha Rajapakse
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Building 6 Room 106, Bethesda, MD, USA.
| | - Katherine Peterson
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Building 6 Room 106, Bethesda, MD, USA.
| | - Sanghamitra Mishra
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Building 6 Room 106, Bethesda, MD, USA.
| | - Graeme Wistow
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Building 6 Room 106, Bethesda, MD, USA.
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28
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Bhuiyan DB, Middleton JC, Tannenbaum R, Wick TM. Bone regeneration from human mesenchymal stem cells on porous hydroxyapatite-PLGA-collagen bioactive polymer scaffolds. Biomed Mater Eng 2017; 28:671-685. [DOI: 10.3233/bme-171703] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Didarul B. Bhuiyan
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | | | - Rina Tannenbaum
- Department of Materials Science and Engineering, Program in Chemical and Molecular Engineering, Stony Brook University, Stony Brook, NY 11794, USA
| | - Timothy M. Wick
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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29
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Rudolf M, Mir Mohi Sefat A, Miura Y, Tura A, Raasch W, Ranjbar M, Grisanti S, Aherrahrou Z, Wagner A, Messinger JD, Garber DW, Anantharamaiah GM, Curcio CA. ApoA-I Mimetic Peptide 4F Reduces Age-Related Lipid Deposition in Murine Bruch's Membrane and Causes Its Structural Remodeling. Curr Eye Res 2017; 43:135-146. [PMID: 28972410 DOI: 10.1080/02713683.2017.1370118] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE Accumulation of lipoprotein-derived lipids including esterified and unesterified cholesterol in Bruch's membrane of human eyes is a major age-related change involved in initiating and sustaining soft drusen in age-related macular degeneration (AMD). The apolipoprotein (apo) A-I mimetic peptide 4F is a small anti-inflammatory and anti-atherogenic agent, and potent modifier of plasma membranes. We evaluated the effect of intravitreally-injected 4F on murine Bruch's membrane. METHODS We tested single intravitreal injections of 4F doses (0.6 µg, 1.2 µg, 2.4 µg, and placebo scrambled peptide) in ApoEnull mice ≥10 months of age. After 30 days, mice were euthanized. Eyes were processed for either direct immunofluorescence detection of esterified cholesterol (EC) in Bruch's membrane whole mounts via a perfringolysin O-based marker linked to green fluorescent protein or by transmission electron microscopic visualization of Bruch's membrane integrity. Fluorescein isothiocyanate-conjugated 4F was traced after injection. RESULTS All injected eyes showed a dose-dependent reduction of Bruch's membrane EC with a concomitant ultrastructural improvement compared to placebo treated eyes. At a 2.4 µg dose of 4F, EC was reduced on average by ~60% and Bruch's membrane returned to a regular pentalaminar structure and thickness. Tracer studies confirmed that injected 4F reached intraocular targets. CONCLUSION We demonstrated a highly effective pharmacological reduction of EC and restoration of Bruch's membrane ultrastructure. The apoA-I mimetic peptide 4F is a novel way to treat a critical AMD disease process and thus represents a new candidate for treating the underlying cause of AMD.
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Affiliation(s)
- Martin Rudolf
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | | | - Yoko Miura
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | - Aysegül Tura
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | - Walter Raasch
- b Department of Experimental and Clinical Pharmacology and Toxicology , University of Lübeck , Lübeck , Germany
| | - Mahdy Ranjbar
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany.,c Laboratory for Angiogenesis & Ocular Cell Transplantation , University of Lübeck , Lübeck , Germany
| | | | - Zouhair Aherrahrou
- d Institute of Integrative and Experimental Genomics , University of Lübeck , Lübeck , Germany
| | - Anna Wagner
- a Department of Ophthalmology , University of Lübeck , Lübeck , Germany
| | - Jeffrey D Messinger
- e Department of Ophthalmology , University of Alabama at Birmingham , Birmingham , AL , USA
| | - David W Garber
- f Atherosclerosis Research Unit , University of Alabama at Birmingham , Birmingham , AL , USA
| | - G M Anantharamaiah
- f Atherosclerosis Research Unit , University of Alabama at Birmingham , Birmingham , AL , USA.,g Department of Medicine, Biochemistry and Molecular Genetics , University of Alabama at Birmingham , Birmingham , AL , USA
| | - Christine A Curcio
- e Department of Ophthalmology , University of Alabama at Birmingham , Birmingham , AL , USA
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Lim FT, Lim SM, Ramasamy K. Cholesterol lowering by Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 in adult zebrafish is associated with improved memory and involves an interplay between npc1l1 and abca1. Food Funct 2017; 8:2817-2828. [PMID: 28725889 DOI: 10.1039/c7fo00764g] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study assessed the cholesterol lowering effect of Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 using adult zebrafish. Animals were fed with a high cholesterol diet (HCD) with/without LAB for seven weeks. Serum and liver cholesterol was quantified using colorimetric and dye staining methods. Expressions of npc1l1 and abca1 in the liver and intestine and appa in the brain were quantified using RT-PCR. Serum and liver cholesterol was significantly lowered in LAB4- and LAB12-fed zebrafish (≤64% and ≤71%, respectively), with reduced liver cholesterol deposition. The cholesterol lowering effect was accompanied by down-regulation of npc1l1 in intestines (≤28.7%), up-regulation of abca1 in the liver (≥30.5%) and down-regulation of appa in the brain (≤24.5%). A moderately strong positive Pearson correlation (r = 0.617, p < 0.01) was found between appa and serum cholesterol. LAB-fed zebrafish exhibited improved spatial learning and memory. LAB4 and LAB12 can be potentially used in preventing hypercholesterolaemia and Alzheimer's diseases.
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Affiliation(s)
- Fei Tieng Lim
- Collaborative Drug Discovery Research (CDDR) Group, Faculty of Pharmacy, University Teknologi MARA (UiTM), 42300 Bandar Puncak Alam, Selangor Darul Ehsan, Malaysia.
| | - Siong Meng Lim
- Collaborative Drug Discovery Research (CDDR) Group, Faculty of Pharmacy, University Teknologi MARA (UiTM), 42300 Bandar Puncak Alam, Selangor Darul Ehsan, Malaysia.
| | - Kalavathy Ramasamy
- Collaborative Drug Discovery Research (CDDR) Group, Faculty of Pharmacy, University Teknologi MARA (UiTM), 42300 Bandar Puncak Alam, Selangor Darul Ehsan, Malaysia.
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Zayas-Santiago A, Cross SD, Stanton JB, Marmorstein AD, Marmorstein LY. Mutant Fibulin-3 Causes Proteoglycan Accumulation and Impaired Diffusion Across Bruch's Membrane. Invest Ophthalmol Vis Sci 2017. [PMID: 28622396 PMCID: PMC5477800 DOI: 10.1167/iovs.17-21720] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Purpose The mutation R345W in EFEMP1 (fibulin-3) causes macular degeneration. This study sought to determine whether proteoglycan content and diffusion across Bruch's membrane are altered in Efemp1ki/ki mice carrying this mutation or in Efemp1−/− mice. Methods Proteoglycans in mouse Bruch's membranes were stained with Cupromeronic Blue (CB). Heparan sulfated proteoglycan (HSPG) and chondroitin/dermatan sulfate proteoglycan (C/DSPG) distributions were visualized following treatments with chondroitinase ABC (C-ABC) or nitrous acid. Total sulfated glycosaminoglycans (sGAGs) in Bruch's membrane/choroid (BrM/Ch) were measured with dimethylmethylene blue (DMMB). Matrix metalloprotease (MMP)-2, MMP-9, and tissue inhibitor of metalloproteinase (TIMP)-3 were examined by immunofluorescence and quantified using Image J. Molecules with different Stokes radius (Rs) were allowed simultaneously to diffuse through mouse BrM/Ch mounted in a modified Ussing chamber. Samples were quantified using gel exclusion chromatography. Results HSPGs and C/DSPGs were markedly increased in Efemp1ki/ki Bruch's membrane, and MMP-2 and MMP-9 were decreased, but TIMP-3 was increased. Diffusion across Efemp1ki/ki Bruch's membrane was impaired. In contrast, the proteoglycan amount in Efemp1−/− Bruch's membrane was not significantly different, but the size of proteoglycans was much larger. MMP-2, MMP-3, and TIMP-3 levels were similar to that of Efemp1+/+ mice, but they were localized diffusely in retinal pigment epithelium (RPE) cells instead of Bruch's membrane. Diffusion across Efemp1−/− Bruch's membrane was enhanced. Conclusions Mutant fibulin-3 causes proteoglycan accumulation, reduction of MMP-2 and MMP-9, but increase of TIMP-3, and impairs diffusion across Bruch's membrane. Fibulin-3 ablation results in altered sizes of proteoglycans, altered distributions of MMP-2, MMP-9, and TIMP-3, and enhances diffusion across Bruch's membrane.
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Affiliation(s)
- Astrid Zayas-Santiago
- Department of Pathology & Laboratory Medicine, Universidad Central del Caribe, Bayamón, Puerto Rico
| | - Samuel D Cross
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - James B Stanton
- Department of Ophthalmology & Vision Science, University of Arizona, Tucson, Arizona, United States
| | - Alan D Marmorstein
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Lihua Y Marmorstein
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
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Zhao B, Wang M, Xu J, Li M, Yu Y. Identification of pathogenic genes and upstream regulators in age-related macular degeneration. BMC Ophthalmol 2017. [PMID: 28651595 PMCID: PMC5485582 DOI: 10.1186/s12886-017-0498-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in older individuals. Our study aims to identify the key genes and upstream regulators in AMD. Methods To screen pathogenic genes of AMD, an integrated analysis was performed by using the microarray datasets in AMD derived from the Gene Expression Omnibus (GEO) database. The functional annotation and potential pathways of differentially expressed genes (DEGs) were further discovered by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. We constructed the AMD-specific transcriptional regulatory network to find the crucial transcriptional factors (TFs) which target the DEGs in AMD. Quantitative real time polymerase chain reaction (qRT-PCR) was performed to verify the DEGs and TFs obtained by integrated analysis. Results From two GEO datasets obtained, we identified 1280 DEGs (730 up-regulated and 550 down-regulated genes) between AMD and normal control (NC). After KEGG analysis, steroid biosynthesis is a significantly enriched pathway for DEGs. The expression of 8 genes (TNC, GRP, TRAF6, ADAMTS5, GPX3, FAP, DHCR7 and FDFT1) was detected. Except for TNC and GPX3, the other 6 genes in qRT-PCR played the same pattern with that in our integrated analysis. Conclusions The dysregulation of these eight genes may involve with the process of AMD. Two crucial transcription factors (c-rel and myogenin) were concluded to play a role in AMD. Especially, myogenin was associated with AMD by regulating TNC, GRP and FAP. Our finding can contribute to developing new potential biomarkers, revealing the underlying pathogenesis, and further raising new therapeutic targets for AMD. Electronic supplementary material The online version of this article (doi:10.1186/s12886-017-0498-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bin Zhao
- Department of Ophthlmology, Affiliated Hospital of Taishan Medical College, No.706 Taishan street, Taian, 271000, China
| | - Mengya Wang
- Department of Ophthlmology, Peoples Hospital of Feicheng, No. 108 Xincheng Road, Feicheng, 271699, China
| | - Jing Xu
- Department of Ophthlmology, The First Peoples Hospital of Jining, Shandong, No.6 Jiankang Road, Jining, 272011, China.
| | - Min Li
- Department of Ophthlmology, The Third Peoples Hospital of Xintai, No.127 Cuyang street, Taian, 271212, China
| | - Yuhui Yu
- Department of Ophthlmology, Affiliated Hospital of Taishan Medical College, No.706 Taishan street, Taian, 271000, China
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Gnanaguru G, Choi AR, Amarnani D, D'Amore PA. Oxidized Lipoprotein Uptake Through the CD36 Receptor Activates the NLRP3 Inflammasome in Human Retinal Pigment Epithelial Cells. Invest Ophthalmol Vis Sci 2017; 57:4704-12. [PMID: 27607416 PMCID: PMC5024668 DOI: 10.1167/iovs.15-18663] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Purpose Accumulation of oxidized phospholipids/lipoproteins with age is suggested to contribute to the pathogenesis of AMD. We investigated the effect of oxidized LDL (ox-LDL) on human RPE cells. Methods Primary human fetal RPE (hf-RPE) and ARPE-19 cells were treated with different doses of LDL or ox-LDL. Assessment of cell death was measured by lactate dehydrogenase release into the conditioned media. Barrier function of RPE was assayed by measuring transepithelial resistance. Lysosomal accumulation of ox-LDL was determined by immunostaining. Expression of CD36 was determined by RT-PCR; protein blot and function was examined by receptor blocking. NLRP3 inflammasome activation was assessed by RT-PCR, protein blot, caspase-1 fluorescent probe assay, and inhibitor assays. Results Treatment with ox-LDL, but not LDL, for 48 hours caused significant increase in hf-RPE and ARPE-19 (P < 0.001) cell death. Oxidized LDL treatment of hf-RPE cells resulted in a significant decrease in transepithelial resistance (P < 0.001 at 24 hours and P < 0.01 at 48 hours) relative to LDL-treated and control cells. Internalized ox-LDL was targeted to RPE lysosomes. Uptake of ox-LDL but not LDL significantly increased CD36 protein and mRNA levels by more than 2-fold. Reverse transcription PCR, protein blot, and caspase-1 fluorescent probe assay revealed that ox-LDL treatment induced NLRP3 inflammasome when compared with LDL treatment and control. Inhibition of NLRP3 activation using 10 μM isoliquiritigenin significantly (P < 0.001) inhibited ox-LDL induced cytotoxicity. Conclusions These data are consistent with the concept that ox-LDL play a role in the pathogenesis of AMD by NLRP3 inflammasome activation. Suppression of NLRP3 inflammasome activation could attenuate RPE degeneration and AMD progression.
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Affiliation(s)
- Gopalan Gnanaguru
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Boston, Massachusetts, United States 2Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
| | - Ariel R Choi
- Program in Liberal Medical Education, Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States
| | - Dhanesh Amarnani
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Boston, Massachusetts, United States 2Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
| | - Patricia A D'Amore
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Boston, Massachusetts, United States 2Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States 4Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States
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Guziewicz KE, Sinha D, Gómez NM, Zorych K, Dutrow EV, Dhingra A, Mullins RF, Stone EM, Gamm DM, Boesze-Battaglia K, Aguirre GD. Bestrophinopathy: An RPE-photoreceptor interface disease. Prog Retin Eye Res 2017; 58:70-88. [PMID: 28111324 PMCID: PMC5441932 DOI: 10.1016/j.preteyeres.2017.01.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/16/2017] [Accepted: 01/18/2017] [Indexed: 11/17/2022]
Abstract
Bestrophinopathies, one of the most common forms of inherited macular degenerations, are caused by mutations in the BEST1 gene expressed in the retinal pigment epithelium (RPE). Both human and canine BEST1-linked maculopathies are characterized by abnormal accumulation of autofluorescent material within RPE cells and bilateral macular or multifocal lesions; however, the specific mechanism leading to the formation of these lesions remains unclear. We now provide an overview of the current state of knowledge on the molecular pathology of bestrophinopathies, and explore factors promoting formation of RPE-neuroretinal separations, using the first spontaneous animal model of BEST1-associated retinopathies, canine Best (cBest). Here, we characterize the nature of the autofluorescent RPE cell inclusions and report matching spectral signatures of RPE-associated fluorophores between human and canine retinae, indicating an analogous composition of endogenous RPE deposits in Best Vitelliform Macular Dystrophy (BVMD) patients and its canine disease model. This study also exposes a range of biochemical and structural abnormalities at the RPE-photoreceptor interface related to the impaired cone-associated microvillar ensheathment and compromised insoluble interphotoreceptor matrix (IPM), the major pathological culprits responsible for weakening of the RPE-neuroretina interactions, and consequently, formation of vitelliform lesions. These salient alterations detected at the RPE apical domain in cBest as well as in BVMD- and ARB-hiPSC-RPE model systems provide novel insights into the pathological mechanism of BEST1-linked disorders that will allow for development of critical outcome measures guiding therapeutic strategies for bestrophinopathies.
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Affiliation(s)
- Karina E Guziewicz
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA.
| | - Divya Sinha
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Néstor M Gómez
- Department of Anatomy & Cell Biology, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Kathryn Zorych
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
| | - Emily V Dutrow
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
| | - Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Robert F Mullins
- Department of Ophthalmology & Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Edwin M Stone
- Department of Ophthalmology & Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - David M Gamm
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Ophthalmology & Visual Sciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | | | - Gustavo D Aguirre
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
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Ioannou GN, Subramanian S, Chait A, Haigh WG, Yeh MM, Farrell GC, Lee SP, Savard C. Cholesterol crystallization within hepatocyte lipid droplets and its role in murine NASH. J Lipid Res 2017; 58:1067-1079. [PMID: 28404639 DOI: 10.1194/jlr.m072454] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 04/03/2017] [Indexed: 12/21/2022] Open
Abstract
We recently reported that cholesterol crystals form in hepatocyte lipid droplets (LDs) in human and experimental nonalcoholic steatohepatitis. Herein, we assigned WT C57BL/6J mice to a high-fat (15%) diet for 6 months, supplemented with 0%, 0.25%, 0.5%, 0.75%, or 1% dietary cholesterol. Increasing dietary cholesterol led to cholesterol loading of the liver, but not of adipose tissue, resulting in fibrosing steatohepatitis at a dietary cholesterol concentration of ≥0.5%, whereas mice on lower-cholesterol diets developed only simple steatosis. Hepatic cholesterol crystals and crown-like structures also developed at a dietary cholesterol concentration ≥0.5%. Crown-like structures consisted of activated Kupffer cells (KCs) staining positive for NLRP3 and activated caspase 1, which surrounded and processed cholesterol crystal-containing remnant LDs of dead hepatocytes. The KCs processed LDs at the center of crown-like structures in the extracellular space by lysosomal enzymes, ultimately transforming into lipid-laden foam cells. When HepG2 cells were exposed to LDL cholesterol, they developed cholesterol crystals in LD membranes, which caused activation of THP1 cells (macrophages) grown in coculture; upregulation of TNF-alpha, NLRP3, and interleukin 1beta (IL1β) mRNA; and secretion of IL-1beta. In conclusion, cholesterol crystals form on the LD membrane of hepatocytes and cause activation and cholesterol loading of KCs that surround and process these LDs by lysosomal enzymes.
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Affiliation(s)
- George N Ioannou
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA .,Division of Gastroenterology, University of Washington, Seattle, WA
| | - Savitha Subramanian
- Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, WA
| | - Alan Chait
- Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, WA
| | - W Geoffrey Haigh
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA
| | - Matthew M Yeh
- Department of Pathology, University of Washington, Seattle, WA
| | - Geoffrey C Farrell
- Liver Research Group, Australian National University Medical School at the Canberra Hospital, Garran, ACT, Australia
| | - Sum P Lee
- Division of Gastroenterology, University of Washington, Seattle, WA
| | - Christopher Savard
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA.,Division of Gastroenterology, University of Washington, Seattle, WA
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Lynn SA, Keeling E, Munday R, Gabha G, Griffiths H, Lotery AJ, Ratnayaka JA. The complexities underlying age-related macular degeneration: could amyloid beta play an important role? Neural Regen Res 2017; 12:538-548. [PMID: 28553324 PMCID: PMC5436342 DOI: 10.4103/1673-5374.205083] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Age-related macular degeneration (AMD) causes irreversible loss of central vision for which there is no effective treatment. Incipient pathology is thought to occur in the retina for many years before AMD manifests from midlife onwards to affect a large proportion of the elderly. Although genetic as well as non-genetic/environmental risks are recognized, its complex aetiology makes it difficult to identify susceptibility, or indeed what type of AMD develops or how quickly it progresses in different individuals. Here we summarize the literature describing how the Alzheimer's-linked amyloid beta (Aβ) group of misfolding proteins accumulate in the retina. The discovery of this key driver of Alzheimer's disease in the senescent retina was unexpected and surprising, enabling an altogether different perspective of AMD. We argue that Aβ fundamentally differs from other substances which accumulate in the ageing retina, and discuss our latest findings from a mouse model in which physiological amounts of Aβ were subretinally-injected to recapitulate salient features of early AMD within a short period. Our discoveries as well as those of others suggest the pattern of Aβ accumulation and pathology in donor aged/AMD tissues are closely reproduced in mice, including late-stage AMD phenotypes, which makes them highly attractive to study dynamic aspects of Aβ-mediated retinopathy. Furthermore, we discuss our findings revealing how Aβ behaves at single-cell resolution, and consider the long-term implications for neuroretinal function. We propose Aβ as a key element in switching to a diseased retinal phenotype, which is now being used as a biomarker for late-stage AMD.
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Affiliation(s)
- Savannah A Lynn
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Eloise Keeling
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Rosie Munday
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Gagandeep Gabha
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Helen Griffiths
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.,Eye Unit, University Southampton NHS Trust, Southampton, United Kingdom
| | - J Arjuna Ratnayaka
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
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Chirco KR, Sohn EH, Stone EM, Tucker BA, Mullins RF. Structural and molecular changes in the aging choroid: implications for age-related macular degeneration. Eye (Lond) 2017; 31:10-25. [PMID: 27716746 PMCID: PMC5233940 DOI: 10.1038/eye.2016.216] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/06/2016] [Indexed: 12/27/2022] Open
Abstract
Age-related macular degeneration (AMD) is a devastating disease-causing vision loss in millions of people around the world. In advanced stages of disease, death of photoreceptor cells, retinal pigment epithelial cells, and choroidal endothelial cells (CECs) are common. Loss of endothelial cells of the choriocapillaris is one of the earliest detectable events in AMD, and, because the outer retina relies on the choriocapillaris for metabolic support, this loss may be the trigger for progression to more advanced stages. Here we highlight evidence for loss of CECs, including changes to vascular density within the choriocapillaris, altered abundance of CEC markers, and changes to overall thickness of the choroid. Furthermore, we review the key components and functions of the choroid, as well as Bruch's membrane, both of which are vital for healthy vision. We discuss changes to the structure and molecular composition of these tissues, many of which develop with age and may contribute to AMD pathogenesis. For example, a crucial event that occurs in the aging choriocapillaris is accumulation of the membrane attack complex, which may result in complement-mediated CEC lysis, and may be a primary cause for AMD-associated choriocapillaris degeneration. The actions of elevated monomeric C-reactive protein in the choriocapillaris in at-risk individuals may also contribute to the inflammatory environment in the choroid and promote disease progression. Finally, we discuss the progress that has been made in the development of AMD therapies, with a focus on cell replacement.
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Affiliation(s)
- K R Chirco
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, IA, USA
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA
| | - E H Sohn
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, IA, USA
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA
| | - E M Stone
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, IA, USA
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA
| | - B A Tucker
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, IA, USA
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA
| | - R F Mullins
- The Stephen A. Wynn Institute for Vision Research, The University of Iowa, Iowa City, IA, USA
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, IA, USA
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Lim FT, Lim SM, Ramasamy K. Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 assimilate cholesterol and modulate ABCA1, CD36, NPC1L1 and SCARB1 in vitro. Benef Microbes 2016; 8:97-109. [PMID: 27903090 DOI: 10.3920/bm2016.0048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There is growing interest in the use of probiotic lactic acid bacteria (LAB) for prevention of hypercholesterolaemia. This study assessed the cholesterol lowering ability of Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 in growth media. Both LAB yielded >98% (39.2 μg/ml) cholesterol lowering in growth media. Nile Red staining indicated direct assimilation of cholesterol by the LAB. The LAB were then explored for their prophylactic (pre-treatment of HT29 cells with LAB prior to cholesterol exposure) and biotherapeutic (treatment of HT29 cells with LAB after exposure to cholesterol) use against short and prolonged exposure of HT29 cells to cholesterol, respectively. For HT29 cells pre-treated with LAB, cholesterol lowering was accompanied by down-regulation of ATP-binding cassette family transporter-type A1 (ABCA1), cluster of differentiation 36 (CD36) and scavenger receptor class B member 1 (SCARB1). HT29 cells treated with LAB after prolonged exposure to cholesterol source, on the other hand, was associated with up-regulation of ABCA1, restoration of CD36 to basal level and down-regulation of Neimann-Pick C1-Like 1 (NPC1L1). The present findings implied the potential use of LAB4 and LAB12 as part of the strategies in prevention and management of hypercholesterolaemia.
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Affiliation(s)
- F T Lim
- 1 Faculty of Pharmacy, Universiti Teknologi MARA (UiTM), 42300 Bandar Puncak Alam, Selangor Darul Ehsan, Malaysia.,2 Collaborative Drug Discovery Research (CDDR) Group, Pharmaceutical and Life Sciences Community of Research, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor Darul Ehsan, Malaysia
| | - S M Lim
- 1 Faculty of Pharmacy, Universiti Teknologi MARA (UiTM), 42300 Bandar Puncak Alam, Selangor Darul Ehsan, Malaysia.,2 Collaborative Drug Discovery Research (CDDR) Group, Pharmaceutical and Life Sciences Community of Research, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor Darul Ehsan, Malaysia
| | - K Ramasamy
- 1 Faculty of Pharmacy, Universiti Teknologi MARA (UiTM), 42300 Bandar Puncak Alam, Selangor Darul Ehsan, Malaysia.,2 Collaborative Drug Discovery Research (CDDR) Group, Pharmaceutical and Life Sciences Community of Research, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor Darul Ehsan, Malaysia
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Bader CA, Shandala T, Carter EA, Ivask A, Guinan T, Hickey SM, Werrett MV, Wright PJ, Simpson PV, Stagni S, Voelcker NH, Lay PA, Massi M, Plush SE, Brooks DA. A Molecular Probe for the Detection of Polar Lipids in Live Cells. PLoS One 2016; 11:e0161557. [PMID: 27551717 PMCID: PMC4994960 DOI: 10.1371/journal.pone.0161557] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 08/07/2016] [Indexed: 01/08/2023] Open
Abstract
Lipids have an important role in many aspects of cell biology, including membrane architecture/compartment formation, intracellular traffic, signalling, hormone regulation, inflammation, energy storage and metabolism. Lipid biology is therefore integrally involved in major human diseases, including metabolic disorders, neurodegenerative diseases, obesity, heart disease, immune disorders and cancers, which commonly display altered lipid transport and metabolism. However, the investigation of these important cellular processes has been limited by the availability of specific tools to visualise lipids in live cells. Here we describe the potential for ReZolve-L1™ to localise to intracellular compartments containing polar lipids, such as for example sphingomyelin and phosphatidylethanolamine. In live Drosophila fat body tissue from third instar larvae, ReZolve-L1™ interacted mainly with lipid droplets, including the core region of these organelles. The presence of polar lipids in the core of these lipid droplets was confirmed by Raman mapping and while this was consistent with the distribution of ReZolve-L1™ it did not exclude that the molecular probe might be detecting other lipid species. In response to complete starvation conditions, ReZolve-L1™ was detected mainly in Atg8-GFP autophagic compartments, and showed reduced staining in the lipid droplets of fat body cells. The induction of autophagy by Tor inhibition also increased ReZolve-L1™ detection in autophagic compartments, whereas Atg9 knock down impaired autophagosome formation and altered the distribution of ReZolve-L1™. Finally, during Drosophila metamorphosis fat body tissues showed increased ReZolve-L1™ staining in autophagic compartments at two hours post puparium formation, when compared to earlier developmental time points. We concluded that ReZolve-L1™ is a new live cell imaging tool, which can be used as an imaging reagent for the detection of polar lipids in different intracellular compartments.
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Affiliation(s)
- Christie A. Bader
- School of Pharmacy and Medical Science, University of South Australia, Adelaide, South Australia, Australia
| | - Tetyana Shandala
- School of Pharmacy and Medical Science, University of South Australia, Adelaide, South Australia, Australia
| | - Elizabeth A. Carter
- Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales, Australia
| | - Angela Ivask
- Future Industries Institute, University of South Australia, Mawson Lakes, South Australia, Australia
| | - Taryn Guinan
- Future Industries Institute, University of South Australia, Mawson Lakes, South Australia, Australia
| | - Shane M. Hickey
- School of Pharmacy and Medical Science, University of South Australia, Adelaide, South Australia, Australia
| | - Melissa V. Werrett
- Department of Chemistry and Nanochemistry Research Institute, Curtin University, Bentley, Western Australia, Australia
| | - Phillip J. Wright
- Department of Chemistry and Nanochemistry Research Institute, Curtin University, Bentley, Western Australia, Australia
| | - Peter V. Simpson
- Department of Chemistry and Nanochemistry Research Institute, Curtin University, Bentley, Western Australia, Australia
| | - Stefano Stagni
- Department of Industrial Chemistry “Toso Montanari”, University of Bologna, Bologna, Italy
| | - Nicolas H. Voelcker
- Future Industries Institute, University of South Australia, Mawson Lakes, South Australia, Australia
| | - Peter A. Lay
- Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales, Australia
| | - Massimiliano Massi
- Department of Chemistry and Nanochemistry Research Institute, Curtin University, Bentley, Western Australia, Australia
| | - Sally E. Plush
- School of Pharmacy and Medical Science, University of South Australia, Adelaide, South Australia, Australia
| | - Douglas A. Brooks
- School of Pharmacy and Medical Science, University of South Australia, Adelaide, South Australia, Australia
- * E-mail:
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Saadane A, Mast N, Dao T, Ahmad B, Pikuleva IA. Retinal Hypercholesterolemia Triggers Cholesterol Accumulation and Esterification in Photoreceptor Cells. J Biol Chem 2016; 291:20427-39. [PMID: 27514747 DOI: 10.1074/jbc.m116.744656] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Indexed: 01/01/2023] Open
Abstract
The process of vision is impossible without the photoreceptor cells, which have a unique structure and specific maintenance of cholesterol. Herein we report on the previously unrecognized cholesterol-related pathway in the retina discovered during follow-up characterizations of Cyp27a1(-/-)Cyp46a1(-/-) mice. These animals have retinal hypercholesterolemia and convert excess retinal cholesterol into cholesterol esters, normally present in the retina in very small amounts. We established that in the Cyp27a1(-/-)Cyp46a1(-/-) retina, cholesterol esters are generated by and accumulate in the photoreceptor outer segments (OS), which is the retinal layer with the lowest cholesterol content. Mouse OS were also found to express the cholesterol-esterifying enzyme acyl-coenzyme A:cholesterol acyltransferase (ACAT1), but not lecithin-cholesterol acyltransferase (LCAT), and to differ from humans in retinal expression of ACAT1. Nevertheless, cholesterol esters were discovered to be abundant in human OS. We suggest a mechanism for cholesterol ester accumulation in the OS and that activity impairment of ACAT1 in humans may underlie the development of subretinal drusenoid deposits, a hallmark of age-related macular degeneration, which is a common blinding disease. We generated Cyp27a1(-/-)Cyp46a1(-/-)Acat1(-/-) mice, characterized their retina by different imaging modalities, and confirmed that unesterified cholesterol does accumulate in their OS and that there is photoreceptor apoptosis and OS degeneration in this line. Our results provide insights into the retinal response to local hypercholesterolemia and the retinal significance of cholesterol esterification, which could be cell-specific and both beneficial and detrimental for retinal structure and function.
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Affiliation(s)
- Aicha Saadane
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
| | - Natalia Mast
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
| | - Tung Dao
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
| | - Baseer Ahmad
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and the University Hospitals, Cleveland, Ohio 44106
| | - Irina A Pikuleva
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
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The Unfolded Protein Response and Cholesterol Biosynthesis Link Luman/CREB3 to Regenerative Axon Growth in Sensory Neurons. J Neurosci 2016; 35:14557-70. [PMID: 26511246 DOI: 10.1523/jneurosci.0012-15.2015] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We recently revealed that the axon endoplasmic reticulum resident transcription factor Luman/CREB3 (herein called Luman) serves as a unique retrograde injury signal in regulation of the intrinsic elongating form of sensory axon regeneration. Here, evidence supports that Luman contributes to axonal regeneration through regulation of the unfolded protein response (UPR) and cholesterol biosynthesis in adult rat sensory neurons. One day sciatic nerve crush injury triggered a robust increase in UPR-associated mRNA and protein expression in both neuronal cell bodies and the injured axons. Knockdown of Luman expression in 1 d injury-conditioned neurons by siRNA attenuated axonal outgrowth to 48% of control injured neurons and was concomitant with reduced UPR- and cholesterol biosynthesis-associated gene expression. UPR PCR-array analysis coupled with qRT-PCR identified and confirmed that four transcripts involved in cholesterol regulation were downregulated >2-fold by the Luman siRNA treatment of the injury-conditioned neurons. Further, the Luman siRNA-attenuated outgrowth could be significantly rescued by either cholesterol supplementation or 2 ng/ml of the UPR inducer tunicamycin, an amount determined to elevate the depressed UPR gene expression to a level equivalent of that observed with crush injury. Using these approaches, outgrowth increased significantly to 74% or 69% that of injury-conditioned controls, respectively. The identification of Luman as a regulator of the injury-induced UPR and cholesterol at levels that benefit the intrinsic ability of axotomized adult rat sensory neurons to undergo axonal regeneration reveals new therapeutic targets to bolster nerve repair.
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Lynn DA, Dalton HM, Sowa JN, Wang MC, Soukas AA, Curran SP. Omega-3 and -6 fatty acids allocate somatic and germline lipids to ensure fitness during nutrient and oxidative stress in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2015; 112:15378-83. [PMID: 26621724 PMCID: PMC4687584 DOI: 10.1073/pnas.1514012112] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Animals in nature are continually challenged by periods of feast and famine as resources inevitably fluctuate, and must allocate somatic reserves for reproduction to abate evolutionary pressures. We identify an age-dependent lipid homeostasis pathway in Caenorhabditis elegans that regulates the mobilization of lipids from the soma to the germline, which supports fecundity but at the cost of survival in nutrient-poor and oxidative stress environments. This trade-off is responsive to the levels of dietary carbohydrates and organismal oleic acid and is coupled to activation of the cytoprotective transcription factor SKN-1 in both laboratory-derived and natural isolates of C. elegans. The homeostatic balance of lipid stores between the somatic and germ cells is mediated by arachidonic acid (omega-6) and eicosapentaenoic acid (omega-3) precursors of eicosanoid signaling molecules. Our results describe a mechanism for resource reallocation within intact animals that influences reproductive fitness at the cost of somatic resilience.
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Affiliation(s)
- Dana A Lynn
- Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089; Dornsife College of Letters, Arts, and Sciences, Department of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089
| | - Hans M Dalton
- Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089; Dornsife College of Letters, Arts, and Sciences, Department of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089
| | - Jessica N Sowa
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030
| | - Meng C Wang
- Department of Molecular and Human Genetics, Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030
| | - Alexander A Soukas
- Center for Human Genetic Research and Diabetes Unit, Department of Medicine, Massachusetts General Hospital, Boston, MA 02114
| | - Sean P Curran
- Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089; Dornsife College of Letters, Arts, and Sciences, Department of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089;
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Grassmann F, Ach T, Brandl C, Heid IM, Weber BH. What Does Genetics Tell Us About Age-Related Macular Degeneration? Annu Rev Vis Sci 2015; 1:73-96. [DOI: 10.1146/annurev-vision-082114-035609] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Thomas Ach
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama 35294
- Department of Ophthalmology, University Hospital Würzburg, Würzburg, D-97080, Germany
| | - Caroline Brandl
- Institute of Human Genetics and
- Department of Genetic Epidemiology, University of Regensburg, Regensburg, D-93053, Germany;
- Department of Ophthalmology, University Hospital Regensburg, Regensburg, D-93042, Germany
| | - Iris M. Heid
- Department of Genetic Epidemiology, University of Regensburg, Regensburg, D-93053, Germany;
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Fu Q, Inankur B, Yin J, Striker R, Lan Q. Sterol Carrier Protein 2, a Critical Host Factor for Dengue Virus Infection, Alters the Cholesterol Distribution in Mosquito Aag2 Cells. JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:1124-1134. [PMID: 26336241 DOI: 10.1093/jme/tjv101] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 06/24/2015] [Indexed: 06/05/2023]
Abstract
Host factors that enable dengue virus (DENV) to propagate in the mosquito host cells are unclear. It is known that cellular cholesterol plays an important role in the life cycle of DENV in human host cells but unknown if the lipid requirements differ for mosquito versus mammalian. In mosquito Aedes aegypti, sterol carrier protein 2 (SCP-2) is critical for cellular cholesterol homeostasis. In this study, we identified SCP-2 as a critical host factor for DENV production in mosquito Aag2 cells. Treatment with a small molecule commonly referred to as SCPI-1, (N-(4-{[4-(3,4-dichlorophenyl)-1,3-thiazol-2-yl]amino}phenyl)acetamide hydrobromide, a known inhibitor of SCP-2, or knockdown of SCP-2 dramatically repressed the virus production in mosquito but not mammalian cells. We showed that the intracellular cholesterol distribution in mosquito cells was altered by SCP-2 inhibitor treatment, suggesting that SCP-2-mediated cholesterol trafficking pathway is important for DENV viral production. A comparison of the effect of SCP-2 on mosquito and human cells suggests that SCPI-1 treatment decreases cholesterol in both cell lines, but this decrease in cholesterol only leads to a decline in viral titer in mosquito host cells, perhaps, owing to a more drastic effect on perinuclear cholesterol storages in mosquito cells that was absent in human cells. SCP-2 had no inhibitory effect on another enveloped RNA virus grown in mosquito cells, suggesting that SCP-2 does not have a generalized anti-cellular or antiviral effect. Our cell culture results imply that SCP-2 may play a limiting role in mosquito-dengue vector competence.
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Affiliation(s)
- Qiang Fu
- Department of Entomology, University of Wisconsin-Madison, WI.
| | - Bahar Inankur
- Chemical and Biological Engineering Department, University of Wisconsin-Madison, WI
| | - John Yin
- Chemical and Biological Engineering Department, University of Wisconsin-Madison, WI
| | - Rob Striker
- Department of Medicine, University of Wisconsin-Madison, WI
| | - Que Lan
- Department of Entomology, University of Wisconsin-Madison, WI. Deceased
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45
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Barisch C, Paschke P, Hagedorn M, Maniak M, Soldati T. Lipid droplet dynamics at early stages of Mycobacterium marinum infection in Dictyostelium. Cell Microbiol 2015; 17:1332-49. [PMID: 25772333 DOI: 10.1111/cmi.12437] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 02/17/2015] [Accepted: 03/03/2015] [Indexed: 01/15/2023]
Abstract
Lipid droplets exist in virtually every cell type, ranging not only from mammals to plants, but also to eukaryotic and prokaryotic unicellular organisms such as Dictyostelium and bacteria. They serve among other roles as energy reservoir that cells consume in times of starvation. Mycobacteria and some other intracellular pathogens hijack these organelles as a nutrient source and to build up their own lipid inclusions. The mechanisms by which host lipid droplets are captured by the pathogenic bacteria are extremely poorly understood. Using the powerful Dictyostelium discoideum/Mycobacterium marinum infection model, we observed that, immediately after their uptake, lipid droplets translocate to the vicinity of the vacuole containing live but not dead mycobacteria. Induction of lipid droplets in Dictyostelium prior to infection resulted in a vast accumulation of neutral lipids and sterols inside the bacterium-containing compartment. Subsequently, under these conditions, mycobacteria accumulated much larger lipid inclusions. Strikingly, the Dictyostelium homologue of perilipin and the murine perilipin 2 surrounded bacteria that had escaped to the cytosol of Dictyostelium or microglial BV-2 cells respectively. Moreover, bacterial growth was inhibited in Dictyostelium plnA knockout cells. In summary, our results provide evidence that mycobacteria actively manipulate the lipid metabolism of the host from very early infection stages.
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Affiliation(s)
- Caroline Barisch
- Department of Biochemistry, Science II, University of Geneva, Geneva, Switzerland
| | - Peggy Paschke
- Department of Cell Biology, University of Kassel, Kassel, Germany
| | - Monica Hagedorn
- Section Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Markus Maniak
- Department of Cell Biology, University of Kassel, Kassel, Germany
| | - Thierry Soldati
- Department of Biochemistry, Science II, University of Geneva, Geneva, Switzerland
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46
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Identification of hydroxyapatite spherules provides new insight into subretinal pigment epithelial deposit formation in the aging eye. Proc Natl Acad Sci U S A 2015; 112:1565-70. [PMID: 25605911 DOI: 10.1073/pnas.1413347112] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Accumulation of protein- and lipid-containing deposits external to the retinal pigment epithelium (RPE) is common in the aging eye, and has long been viewed as the hallmark of age-related macular degeneration (AMD). The cause for the accumulation and retention of molecules in the sub-RPE space, however, remains an enigma. Here, we present fluorescence microscopy and X-ray diffraction evidence for the formation of small (0.5-20 μm in diameter), hollow, hydroxyapatite (HAP) spherules in Bruch's membrane in human eyes. These spherules are distinct in form, placement, and staining from the well-known calcification of the elastin layer of the aging Bruch's membrane. Secondary ion mass spectrometry (SIMS) imaging confirmed the presence of calcium phosphate in the spherules and identified cholesterol enrichment in their core. Using HAP-selective fluorescent dyes, we show that all types of sub-RPE deposits in the macula, as well as in the periphery, contain numerous HAP spherules. Immunohistochemical labeling for proteins characteristic of sub-RPE deposits, such as complement factor H, vitronectin, and amyloid beta, revealed that HAP spherules were coated with these proteins. HAP spherules were also found outside the sub-RPE deposits, ready to bind proteins at the RPE/choroid interface. Based on these results, we propose a novel mechanism for the growth, and possibly even the formation, of sub-RPE deposits, namely, that the deposit growth and formation begin with the deposition of insoluble HAP shells around naturally occurring, cholesterol-containing extracellular lipid droplets at the RPE/choroid interface; proteins and lipids then attach to these shells, initiating or supporting the growth of sub-RPE deposits.
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Ioannou GN, Van Rooyen DM, Savard C, Haigh WG, Yeh MM, Teoh NC, Farrell GC. Cholesterol-lowering drugs cause dissolution of cholesterol crystals and disperse Kupffer cell crown-like structures during resolution of NASH. J Lipid Res 2014; 56:277-85. [PMID: 25520429 DOI: 10.1194/jlr.m053785] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cholesterol crystals form within hepatocyte lipid droplets in human and experimental nonalcoholic steatohepatitis (NASH) and are the focus of crown-like structures (CLSs) of activated Kupffer cells (KCs). Obese, diabetic Alms1 mutant (foz/foz) mice were a fed high-fat (23%) diet containing 0.2% cholesterol for 16 weeks and then assigned to four intervention groups for 8 weeks: a) vehicle control, b) ezetimibe (5 mg/kg/day), c) atorvastatin (20 mg/kg/day), or d) ezetimibe and atorvastatin. Livers of vehicle-treated mice developed fibrosing NASH with abundant cholesterol crystallization within lipid droplets calculated to extend over 3.3% (SD, 2.2%) of liver surface area. Hepatocyte lipid droplets with prominent cholesterol crystallization were surrounded by TNFα-positive (activated) KCs forming CLSs (≥ 3 per high-power field). KCs that formed CLSs stained positive for NLRP3, implicating activation of the NLRP3 inflammasome in response to cholesterol crystals. In contrast, foz/foz mice treated with ezetimibe and atorvastatin showed near-complete resolution of cholesterol crystals [0.01% (SD, 0.02%) of surface area] and CLSs (0 per high-power field), with amelioration of fibrotic NASH. Ezetimibe or atorvastatin alone had intermediate effects on cholesterol crystallization, CLSs, and NASH. These findings are consistent with a causative link between exposure of hepatocytes and KCs to cholesterol crystals and with the development of NASH possibly mediated by NLRP3 activation.
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Affiliation(s)
- George N Ioannou
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System and University of Washington, Seattle, WA
| | - Derrick M Van Rooyen
- Liver Research Group, Australian National University Medical School at the Canberra Hospital, Garran, ACT, Australia
| | - Christopher Savard
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System and University of Washington, Seattle, WA
| | - W Geoffrey Haigh
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System and University of Washington, Seattle, WA
| | - Matthew M Yeh
- Department of Pathology, University of Washington, Seattle, WA
| | - Narci C Teoh
- Liver Research Group, Australian National University Medical School at the Canberra Hospital, Garran, ACT, Australia
| | - Geoffrey C Farrell
- Liver Research Group, Australian National University Medical School at the Canberra Hospital, Garran, ACT, Australia
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Zarrouk A, Vejux A, Mackrill J, O’Callaghan Y, Hammami M, O’Brien N, Lizard G. Involvement of oxysterols in age-related diseases and ageing processes. Ageing Res Rev 2014; 18:148-62. [PMID: 25305550 DOI: 10.1016/j.arr.2014.09.006] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/23/2014] [Accepted: 09/30/2014] [Indexed: 12/15/2022]
Abstract
Ageing is accompanied by increasing vulnerability to major pathologies (atherosclerosis, Alzheimer's disease, age-related macular degeneration, cataract, and osteoporosis) which can have similar underlying pathoetiologies. All of these diseases involve oxidative stress, inflammation and/or cell death processes, which are triggered by cholesterol oxide derivatives, also named oxysterols. These oxidized lipids result either from spontaneous and/or enzymatic oxidation of cholesterol on the steroid nucleus or on the side chain. The ability of oxysterols to induce severe dysfunctions in organelles (especially mitochondria) plays key roles in RedOx homeostasis, inflammatory status, lipid metabolism, and in the control of cell death induction, which may at least in part contribute to explain the potential participation of these molecules in ageing processes and in age related diseases. As no efficient treatments are currently available for most of these diseases, which are predicted to become more prevalent due to the increasing life expectancy and average age, a better knowledge of the biological activities of the different oxysterols is of interest, and constitutes an important step toward identification of pharmacological targets for the development of new therapeutic strategies.
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Kunchithapautham K, Atkinson C, Rohrer B. Smoke exposure causes endoplasmic reticulum stress and lipid accumulation in retinal pigment epithelium through oxidative stress and complement activation. J Biol Chem 2014; 289:14534-46. [PMID: 24711457 PMCID: PMC4031511 DOI: 10.1074/jbc.m114.564674] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 04/02/2014] [Indexed: 01/02/2023] Open
Abstract
Age-related macular degeneration (AMD) is a complex disease caused by genetic and environmental factors, including genetic variants in complement components and smoking. Smoke exposure leads to oxidative stress, complement activation, endoplasmic reticulum (ER) stress, and lipid dysregulation, which have all been proposed to be associated with AMD pathogenesis. Here we examine the effects of smoke exposure on the retinal pigment epithelium (RPE). Mice were exposed to cigarette smoke or filtered air for 6 months. RPE cells grown as stable monolayers were exposed to 5% cigarette smoke extract (CSE). Effects of smoke were determined by biochemical, molecular, and histological measures. Effects of the alternative pathway (AP) of complement and complement C3a anaphylatoxin receptor signaling were analyzed using knock-out mice or specific inhibitors. ER stress markers were elevated after smoke exposure in RPE of intact mice, which was eliminated in AP-deficient mice. To examine this relationship further, RPE monolayers were exposed to CSE. Short term smoke exposure resulted in production and release of complement C3, the generation of C3a, oxidative stress, complement activation on the cell membrane, and ER stress. Long term exposure to CSE resulted in lipid accumulation, and secretion. All measures were reversed by blocking C3a complement receptor (C3aR), alternative complement pathway signaling, and antioxidant therapy. Taken together, our results provide clear evidence that smoke exposure results in oxidative stress and complement activation via the AP, resulting in ER stress-mediated lipid accumulation, and further suggesting that oxidative stress and complement act synergistically in the pathogenesis of AMD.
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Affiliation(s)
| | - Carl Atkinson
- Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina 29425 and
| | - Bärbel Rohrer
- From the Departments of Ophthalmology and the Research Service, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401
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50
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Cholesterol in the retina: the best is yet to come. Prog Retin Eye Res 2014; 41:64-89. [PMID: 24704580 DOI: 10.1016/j.preteyeres.2014.03.002] [Citation(s) in RCA: 196] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 01/09/2023]
Abstract
Historically understudied, cholesterol in the retina is receiving more attention now because of genetic studies showing that several cholesterol-related genes are risk factors for age-related macular degeneration (AMD) and because of eye pathology studies showing high cholesterol content of drusen, aging Bruch's membrane, and newly found subretinal lesions. The challenge before us is determining how the cholesterol-AMD link is realized. Meeting this challenge will require an excellent understanding these genes' roles in retinal physiology and how chorioretinal cholesterol is maintained. In the first half of this review, we will succinctly summarize physico-chemical properties of cholesterol, its distribution in the human body, general principles of maintenance and metabolism, and differences in cholesterol handling in human and mouse that impact on experimental approaches. This information will provide a backdrop to the second part of the review focusing on unique aspects of chorioretinal cholesterol homeostasis, aging in Bruch's membrane, cholesterol in AMD lesions, a model for lesion biogenesis, a model for macular vulnerability based on vascular biology, and alignment of AMD-related genes and pathobiology using cholesterol and an atherosclerosis-like progression as unifying features. We conclude with recommendations for the most important research steps we can take towards delineating the cholesterol-AMD link.
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