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Liu X, Liu M, Chen L. Bone morphogenetic protein 6 (BMP6) antagonises experimental proliferative vitreoretinopathy established by TGF-β2 stimulation in retinal pigment epithelial cells through modulation of the p38 and JNK MAPK pathways. Cell Tissue Res 2024; 396:103-117. [PMID: 38403744 DOI: 10.1007/s00441-024-03870-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 01/22/2024] [Indexed: 02/27/2024]
Abstract
The formation of the epiretinal fibrotic membrane by retinal pigment epithelial (RPE) cells is a primary pathological change for proliferative vitreoretinopathy (PVR). Bone morphogenetic protein 6 (BMP6) is an antifibrogenic factor in various cells. To date, it is still unknown whether BMP6 can interfere with the fibrogenesis of RPE cells during the progression of PVR. This work aimed to address the relationship between BMP6 and transforming growth factor-β2 (TGF-β2)-elicited fibrogenesis of RPE cells, an experimental model for studying PVR in vitro. The BMP6 level was down-regulated, while the TGF-β2 level was up-regulated in the vitreous humor of PVR patients. The BMP6 level was down-regulated in human RPE cells challenged with TGF-β2. The treatment of RPE cells with TGF-β2 resulted in significant increases in proliferation, migration, epithelial-to-mesenchymal transition (EMT), and extracellular matrix (ECM) remodelling. These effects were found to be inhibited by the overexpression of BMP6 or exacerbated by the knockdown of BMP6. BMP6 overexpression reduced the phosphorylation of p38 and JNK in TGF-β2-stimulated RPE cells, while BMP6 knockdown showed the opposite effects. The inhibition of p38 or JNK partially reversed the BMP6-silencing-induced promoting effects on TGF-β2-elicited fibrogenesis in RPE cells. Taken together, BMP6 demonstrates the ability to counteract the proliferation, migration, EMT, and ECM remodelling of RPE cells induced by TGF-β2. This is achieved through the regulation of the p38 and JNK MAPK pathways. These findings imply a potential connection between BMP6 and PVR, and highlight the potential application of BMP6 in therapeutic interventions for PVR.
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Affiliation(s)
- Xuan Liu
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277 Yanta West Road, Xi'an, 710061, China
| | - Ming Liu
- Department of Ophthalmology, Xi'an No. 1 Hospital, Xi'an, 710002, China
- Shaanxi Institute of Ophthalmology, Xi'an, 710002, China
| | - Li Chen
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277 Yanta West Road, Xi'an, 710061, China.
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2
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Ouyang J, Zhou L, Wang Q. Spotlight on iron and ferroptosis: research progress in diabetic retinopathy. Front Endocrinol (Lausanne) 2023; 14:1234824. [PMID: 37772084 PMCID: PMC10525335 DOI: 10.3389/fendo.2023.1234824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/21/2023] [Indexed: 09/30/2023] Open
Abstract
Iron, as the most abundant metallic element within the human organism, is an indispensable ion for sustaining life and assumes a pivotal role in governing glucose and lipid metabolism, along with orchestrating inflammatory responses. The presence of diabetes mellitus (DM) can induce aberrant iron accumulation within the corporeal system. Consequentially, iron overload precipitates a sequence of important adversities, subsequently setting in motion a domino effect wherein ferroptosis emerges as the utmost pernicious outcome. Ferroptosis, an emerging variant of non-apoptotic regulated cell death, operates independently of caspases and GSDMD. It distinguishes itself from alternative forms of controlled cell death through distinctive morphological and biochemical attributes. Its principal hallmark resides in the pathological accrual of intracellular iron and the concomitant generation of iron-driven lipid peroxides. Diabetic retinopathy (DR), established as the predominant cause of adult blindness, wields profound influence over the well-being and psychosocial strain experienced by afflicted individuals. Presently, an abundance of research endeavors has ascertained the pervasive engagement of iron and ferroptosis in the microangiopathy inherent to DR. Evidently, judicious management of iron overload and ferroptosis in the early stages of DR bears the potential to considerably decelerate disease progression. Within this discourse, we undertake a comprehensive exploration of the regulatory mechanisms governing iron homeostasis and ferroptosis. Furthermore, we expound upon the subsequent detriments induced by their dysregulation. Concurrently, we elucidate the intricate interplay linking iron overload, ferroptosis, and DR. Delving deeper, we engage in a comprehensive deliberation regarding strategies to modulate their influence, thereby effecting prospective interventions in the trajectory of DR's advancement or employing them as therapeutic modalities.
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Affiliation(s)
- Junlin Ouyang
- Department of Endocrinology, China–Japan Union Hospital of Jilin University, Changchun, Jilin, China
| | - Ling Zhou
- Department of Obstetrics and Gynecology, China–Japan Union Hospital of Jilin University, Changchun, Jilin, China
| | - Qing Wang
- Department of Endocrinology, China–Japan Union Hospital of Jilin University, Changchun, Jilin, China
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3
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Li C, Xiao C, Tao H, Tang X. Research progress of iron metabolism in retinal diseases. ADVANCES IN OPHTHALMOLOGY PRACTICE AND RESEARCH 2023; 3:93-100. [PMID: 37846377 PMCID: PMC10577842 DOI: 10.1016/j.aopr.2023.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 10/18/2023]
Abstract
Background Retinal diseases can lead to severe visual impairment and even blindness, but current treatments are limited. For precise targeted therapy, the pathophysiological mechanisms of the diseases still need to be further explored. Iron serves an essential role in many biological activities and helps maintain the function and morphology of the retina. The vision problems caused by retinal diseases are affecting more and more people, the study of iron metabolism in retinal diseases possesses great potential for clinical application. Main text Iron maintains a dynamic balance in the retina but in excess is toxic to the retina. Iron overload can lead to various pathological changes in the retina through oxidative stress, inflammation, cell death, angiogenesis and other pathways. It is therefore involved in the progression of retinal diseases such as age-related macular degeneration, glaucoma, diabetic retinopathy, retinitis pigmentosa, and hereditary iron overload. In recent years, iron chelators have been shown to be effective in the treatment of retinal diseases, but the exact mechanism is not yet fully understood. This question prompted further investigation into the specific mechanisms by which iron metabolism is involved in retinal disease. Conclusions This review summarizes iron metabolism processes in the retina and mechanistic studies of iron metabolism in the progression of retinal disease. It also highlights the therapeutic potential of iron chelators in retinal diseases.
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Affiliation(s)
- Cunzi Li
- Department of Ophthalmology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Chunyu Xiao
- Department of Ophthalmology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Hui Tao
- Department of Ophthalmology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Xianling Tang
- Department of Ophthalmology, Shenzhen Third People's Hospital, Shenzhen, China
- The First Affiliated Hospital of Harbin Medical University, Harbin, China
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4
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Zhang X, Xu J, Marshall B, Dong Z, Liu Y, Espinosa-Heidmann DG, Zhang M. Transcriptome Analysis of Retinal and Choroidal Pathologies in Aged BALB/c Mice Following Systemic Neonatal Murine Cytomegalovirus Infection. Int J Mol Sci 2023; 24:4322. [PMID: 36901754 PMCID: PMC10001583 DOI: 10.3390/ijms24054322] [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: 01/25/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Our previous studies have shown that systemic neonatal murine cytomegalovirus (MCMV) infection of BALB/c mice spread to the eye with subsequent establishment of latency in choroid/RPE. In this study, RNA sequencing (RNA-Seq) analysis was used to determine the molecular genetic changes and pathways affected by ocular MCMV latency. MCMV (50 pfu per mouse) or medium as control were injected intra-peritoneally (i.p.) into BALB/c mice at <3 days after birth. At 18 months post injection, the mice were euthanized, and the eyes were collected and prepared for RNA-Seq. Compared to three uninfected control eyes, we identified 321 differentially expressed genes (DEGs) in six infected eyes. Using the QIAGEN Ingenuity Pathway Analysis (QIAGEN IPA), we identified 17 affected canonical pathways, 10 of which function in neuroretinal signaling, with the majority of DEGs being downregulated, while 7 pathways function in upregulated immune/inflammatory responses. Retinal and epithelial cell death pathways involving both apoptosis and necroptosis were also activated. MCMV ocular latency is associated with upregulation of immune and inflammatory responses and downregulation of multiple neuroretinal signaling pathways. Cell death signaling pathways are also activated and contribute to the degeneration of photoreceptors, RPE, and choroidal capillaries.
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Affiliation(s)
- Xinyan Zhang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- James and Jean Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Jinxian Xu
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- James and Jean Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Brendan Marshall
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Zheng Dong
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- James and Jean Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Diego G. Espinosa-Heidmann
- James and Jean Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Department of Ophthamology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Ming Zhang
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- James and Jean Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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5
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Gupta U, Ghosh S, Wallace CT, Shang P, Xin Y, Nair AP, Yazdankhah M, Strizhakova A, Ross MA, Liu H, Hose S, Stepicheva NA, Chowdhury O, Nemani M, Maddipatla V, Grebe R, Das M, Lathrop KL, Sahel JA, Zigler JS, Qian J, Ghosh A, Sergeev Y, Handa JT, St Croix CM, Sinha D. Increased LCN2 (lipocalin 2) in the RPE decreases autophagy and activates inflammasome-ferroptosis processes in a mouse model of dry AMD. Autophagy 2023; 19:92-111. [PMID: 35473441 PMCID: PMC9809950 DOI: 10.1080/15548627.2022.2062887] [Citation(s) in RCA: 62] [Impact Index Per Article: 62.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 03/30/2022] [Accepted: 04/01/2022] [Indexed: 01/09/2023] Open
Abstract
In dry age-related macular degeneration (AMD), LCN2 (lipocalin 2) is upregulated. Whereas LCN2 has been implicated in AMD pathogenesis, the mechanism remains unknown. Here, we report that in retinal pigmented epithelial (RPE) cells, LCN2 regulates macroautophagy/autophagy, in addition to maintaining iron homeostasis. LCN2 binds to ATG4B to form an LCN2-ATG4B-LC3-II complex, thereby regulating ATG4B activity and LC3-II lipidation. Thus, increased LCN2 reduced autophagy flux. Moreover, RPE cells from cryba1 KO, as well as sting1 KO and Sting1Gt mutant mice (models with abnormal iron chelation), showed decreased autophagy flux and increased LCN2, indicative of CGAS- and STING1-mediated inflammasome activation. Live cell imaging of RPE cells with elevated LCN2 also showed a correlation between inflammasome activation and increased fluorescence intensity of the Liperfluo dye, indicative of oxidative stress-induced ferroptosis. Interestingly, both in human AMD patients and in mouse models with a dry AMD-like phenotype (cryba1 cKO and KO), the LCN2 homodimer variant is increased significantly compared to the monomer. Sub-retinal injection of the LCN2 homodimer secreted by RPE cells into NOD-SCID mice leads to retinal degeneration. In addition, we generated an LCN2 monoclonal antibody that neutralizes both the monomer and homodimer variants and rescued autophagy and ferroptosis activities in cryba1 cKO mice. Furthermore, the antibody rescued retinal function in cryba1 cKO mice as assessed by electroretinography. Here, we identify a molecular pathway whereby increased LCN2 elicits pathophysiology in the RPE, cells known to drive dry AMD pathology, thus providing a possible therapeutic strategy for a disease with no current treatment options.Abbreviations: ACTB: actin, beta; Ad-GFP: adenovirus-green fluorescent protein; Ad-LCN2: adenovirus-lipocalin 2; Ad-LCN2-GFP: adenovirus-LCN2-green fluorescent protein; LCN2AKT2: AKT serine/threonine kinase 2; AMBRA1: autophagy and beclin 1 regulator 1; AMD: age-related macular degeneration; ARPE19: adult retinal pigment epithelial cell line-19; Asp278: aspartate 278; ATG4B: autophagy related 4B cysteine peptidase; ATG4C: autophagy related 4C cysteine peptidase; ATG7: autophagy related 7; ATG9B: autophagy related 9B; BLOC-1: biogenesis of lysosomal organelles complex 1; BLOC1S1: biogenesis of lysosomal organelles complex 1 subunit 1; C57BL/6J: C57 black 6J; CGAS: cyclic GMP-AMP synthase; ChQ: chloroquine; cKO: conditional knockout; Cys74: cysteine 74; Dab2: DAB adaptor protein 2; Def: deferoxamine; DHE: dihydroethidium; DMSO: dimethyl sulfoxide; ERG: electroretinography; FAC: ferric ammonium citrate; Fe2+: ferrous; FTH1: ferritin heavy chain 1; GPX: glutathione peroxidase; GST: glutathione S-transferase; H2O2: hydrogen peroxide; His280: histidine 280; IFNL/IFNλ: interferon lambda; IL1B/IL-1β: interleukin 1 beta; IS: Inner segment; ITGB1/integrin β1: integrin subunit beta 1; KO: knockout; LC3-GST: microtubule associated protein 1 light chain 3-GST; C-terminal fusion; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; LCN2: lipocalin 2; mAb: monoclonal antibody; MDA: malondialdehyde; MMP9: matrix metallopeptidase 9; NLRP3: NLR family pyrin domain containing 3; NOD-SCID: nonobese diabetic-severe combined immunodeficiency; OS: outer segment; PBS: phosphate-buffered saline; PMEL/PMEL17: premelanosome protein; RFP: red fluorescent protein; rLCN2: recombinant LCN2; ROS: reactive oxygen species; RPE SM: retinal pigmented epithelium spent medium; RPE: retinal pigment epithelium; RSL3: RAS-selective lethal; scRNAseq: single-cell ribonucleic acid sequencing; SD-OCT: spectral domain optical coherence tomography; shRNA: small hairpin ribonucleic acid; SM: spent medium; SOD1: superoxide dismutase 1; SQSTM1/p62: sequestosome 1; STAT1: signal transducer and activator of transcription 1; STING1: stimulator of interferon response cGAMP interactor 1; TYR: tyrosinase; VCL: vinculin; WT: wild type.
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Affiliation(s)
- Urvi Gupta
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sayan Ghosh
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Callen T Wallace
- Department of Cell Biology and Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Peng Shang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ying Xin
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Meysam Yazdankhah
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Anastasia Strizhakova
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Mark A Ross
- Department of Cell Biology and Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Haitao Liu
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Stacey Hose
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Nadezda A Stepicheva
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Olivia Chowdhury
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Mihir Nemani
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Vishnu Maddipatla
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Rhonda Grebe
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Manjula Das
- Molecular Immunology, Mazumdar Shaw Medical Foundation, Bengaluru, India
| | - Kira L Lathrop
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA, USA
| | - José-Alain Sahel
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Institut De La Vision, INSERM, CNRS, Sorbonne Université, Paris, France
| | - J Samuel Zigler
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jiang Qian
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Arkasubhra Ghosh
- GROW Laboratory, Narayana Nethralaya Foundation, Bengaluru, India
| | - Yuri Sergeev
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - James T Handa
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Claudette M St Croix
- Department of Cell Biology and Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Debasish Sinha
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Cell Biology and Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Song YS, Annalora AJ, Marcus CB, Jefcoate CR, Sorenson CM, Sheibani N. Cytochrome P450 1B1: A Key Regulator of Ocular Iron Homeostasis and Oxidative Stress. Cells 2022; 11:2930. [PMID: 36230892 PMCID: PMC9563809 DOI: 10.3390/cells11192930] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/12/2022] [Accepted: 09/18/2022] [Indexed: 11/22/2022] Open
Abstract
Cytochrome P450 (CYP) 1B1 belongs to the superfamily of heme-containing monooxygenases. Unlike other CYP enzymes, which are highly expressed in the liver, CYP1B1 is predominantly found in extrahepatic tissues, such as the brain, and ocular tissues including retina and trabecular meshwork. CYP1B1 metabolizes exogenous chemicals such as polycyclic aromatic hydrocarbons. CYP1B1 also metabolizes endogenous bioactive compounds including estradiol and arachidonic acid. These metabolites impact various cellular and physiological processes during development and pathological processes. We previously showed that CYP1B1 deficiency mitigates ischemia-mediated retinal neovascularization and drives the trabecular meshwork dysgenesis through increased levels of oxidative stress. However, the underlying mechanisms responsible for CYP1B1-deficiency-mediated increased oxidative stress remain largely unresolved. Iron is an essential element and utilized as a cofactor in a variety of enzymes. However, excess iron promotes the production of hydroxyl radicals, lipid peroxidation, increased oxidative stress, and cell damage. The retinal endothelium is recognized as a major component of the blood-retinal barrier, which controls ocular iron levels through the modulation of proteins involved in iron regulation present in retinal endothelial cells, as well as other ocular cell types including trabecular meshwork cells. We previously showed increased levels of reactive oxygen species and lipid peroxidation in the absence of CYP1B1, and in the retinal vasculature and trabecular meshwork, which was reversed by administration of antioxidant N-acetylcysteine. Here, we review the important role CYP1B1 expression and activity play in maintaining retinal redox homeostasis through the modulation of iron levels by retinal endothelial cells. The relationship between CYP1B1 expression and activity and iron levels has not been previously delineated. We review the potential significance of CYP1B1 expression, estrogen metabolism, and hepcidin-ferroportin regulatory axis in the local regulation of ocular iron levels.
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Affiliation(s)
- Yong-Seok Song
- Departments of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Andrew J. Annalora
- Department of Environmental and Molecular Toxicology, Organ State University, Corvallis, OR 97331, USA
| | - Craig B. Marcus
- Department of Environmental and Molecular Toxicology, Organ State University, Corvallis, OR 97331, USA
| | - Colin R. Jefcoate
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Christine M. Sorenson
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Nader Sheibani
- Departments of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53705, USA
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7
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Sterling JK, Baumann B, Foshe S, Voigt A, Guttha S, Alnemri A, McCright SJ, Li M, Zauhar RJ, Montezuma SR, Kapphahn RJ, Chavali VRM, Hill DA, Ferrington DA, Stambolian D, Mullins RF, Merrick D, Dunaief JL. Inflammatory adipose activates a nutritional immunity pathway leading to retinal dysfunction. Cell Rep 2022; 39:110942. [PMID: 35705048 PMCID: PMC9248858 DOI: 10.1016/j.celrep.2022.110942] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 01/24/2022] [Accepted: 05/20/2022] [Indexed: 11/21/2022] Open
Abstract
Age-related macular degeneration (AMD), the leading cause of irreversible blindness among Americans over 50, is characterized by dysfunction and death of retinal pigment epithelial (RPE) cells. The RPE accumulates iron in AMD, and iron overload triggers RPE cell death in vitro and in vivo. However, the mechanism of RPE iron accumulation in AMD is unknown. We show that high-fat-diet-induced obesity, a risk factor for AMD, drives systemic and local inflammatory circuits upregulating interleukin-1β (IL-1β). IL-1β upregulates RPE iron importers and downregulates iron exporters, causing iron accumulation, oxidative stress, and dysfunction. We term this maladaptive, chronic activation of a nutritional immunity pathway the cellular iron sequestration response (CISR). RNA sequencing (RNA-seq) analysis of choroid and retina from human donors revealed that hallmarks of this pathway are present in AMD microglia and macrophages. Together, these data suggest that inflamed adipose tissue, through the CISR, can lead to RPE pathology in AMD.
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Affiliation(s)
- Jacob K Sterling
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Bailey Baumann
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Sierra Foshe
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Andrew Voigt
- Institute for Vision Research, The University of Iowa, Iowa City, IA 52242, USA; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Samyuktha Guttha
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ahab Alnemri
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Sam J McCright
- Medical Scientist Training Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Division of Allergy and Immunology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Mingyao Li
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Randy J Zauhar
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, PA 19104, USA
| | - Sandra R Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Rebecca J Kapphahn
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Venkata R M Chavali
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - David A Hill
- Division of Allergy and Immunology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Institute of Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Deborah A Ferrington
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Dwight Stambolian
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Robert F Mullins
- Institute for Vision Research, The University of Iowa, Iowa City, IA 52242, USA; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - David Merrick
- Department of Medicine, Division of Endocrinology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Institute of Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Joshua L Dunaief
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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8
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Zhang KR, Baumann B, Song Y, Sterling J, Erler EA, Guttha S, Kozmik Z, Dunaief JL. Conditional knockout of hephaestin in the neural retina disrupts retinal iron homeostasis. Exp Eye Res 2022; 218:109028. [PMID: 35271829 PMCID: PMC9050911 DOI: 10.1016/j.exer.2022.109028] [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: 01/10/2022] [Revised: 02/24/2022] [Accepted: 03/02/2022] [Indexed: 11/18/2022]
Abstract
Iron accumulation has been implicated in degenerative retinal diseases. It can catalyze the production of damaging reactive oxygen species. Previous work has demonstrated iron accumulation in multiple retinal diseases, including age-related macular degeneration and diabetic retinopathy. In mice, systemic knockout of the ferroxidases ceruloplasmin (Cp) and hephaestin (Heph), which oxidize iron, results in retinal iron accumulation and iron-induced degeneration. To determine the role of Heph in the retina, we generated a neural retina-specific Heph knockout on a background of systemic Cp knockout. This resulted in elevated neural retina iron. Conversely, retinal ganglion cells had elevated transferrin receptor and decreased ferritin, suggesting diminished iron levels. The retinal degeneration observed in systemic Cp-/-, Heph-/- mice did not occur. These findings indicate that Heph has a local role in regulating neural retina iron homeostasis, but also suggest that preserved Heph function in either the RPE or systemically mitigates the degeneration phenotype observed in the systemic Cp-/-, Heph-/- mice.
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Affiliation(s)
- Kevin R Zhang
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd., Philadelphia, PA, 19104, USA.
| | - Bailey Baumann
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd., Philadelphia, PA, 19104, USA.
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd., Philadelphia, PA, 19104, USA.
| | - Jacob Sterling
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd., Philadelphia, PA, 19104, USA.
| | - Elizabeth A Erler
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd., Philadelphia, PA, 19104, USA.
| | - Samyuktha Guttha
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd., Philadelphia, PA, 19104, USA.
| | - Zbynek Kozmik
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, ASCR, v. v. i. Vídeňská 1083, 142 20, Prague 4, Czech Republic.
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd., Philadelphia, PA, 19104, USA.
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9
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Shahandeh A, Bui BV, Finkelstein DI, Nguyen CTO. Effects of Excess Iron on the Retina: Insights From Clinical Cases and Animal Models of Iron Disorders. Front Neurosci 2022; 15:794809. [PMID: 35185447 PMCID: PMC8851357 DOI: 10.3389/fnins.2021.794809] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/17/2021] [Indexed: 01/19/2023] Open
Abstract
Iron plays an important role in a wide range of metabolic pathways that are important for neuronal health. Excessive levels of iron, however, can promote toxicity and cell death. An example of an iron overload disorder is hemochromatosis (HH) which is a genetic disorder of iron metabolism in which the body’s ability to regulate iron absorption is altered, resulting in iron build-up and injury in several organs. The retina was traditionally assumed to be protected from high levels of systemic iron overload by the blood-retina barrier. However, recent data shows that expression of genes that are associated with HH can disrupt retinal iron metabolism. Thus, the effects of iron overload on the retina have become an area of research interest, as excessively high levels of iron are implicated in several retinal disorders, most notably age–related macular degeneration. This review is an effort to highlight risk factors for excessive levels of systemic iron build-up in the retina and its potential impact on the eye health. Information is integrated across clinical and preclinical animal studies to provide insights into the effects of systemic iron loading on the retina.
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Affiliation(s)
- Ali Shahandeh
- Department of Optometry and Vision Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Bang V. Bui
- Department of Optometry and Vision Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - David I. Finkelstein
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Christine T. O. Nguyen
- Department of Optometry and Vision Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
- *Correspondence: Christine T. O. Nguyen,
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10
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Liu Y, Bell BA, Song Y, Kim HJ, Sterling JK, Kim BJ, Poli M, Guo M, Zhang K, Rao A, Sparrow JR, Su G, Dunaief JL. Intraocular iron injection induces oxidative stress followed by elements of geographic atrophy and sympathetic ophthalmia. Aging Cell 2021; 20:e13490. [PMID: 34626070 PMCID: PMC8590099 DOI: 10.1111/acel.13490] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/24/2021] [Accepted: 09/14/2021] [Indexed: 01/24/2023] Open
Abstract
Iron has been implicated in the pathogenesis of age‐related retinal diseases, including age‐related macular degeneration (AMD). Previous work showed that intravitreal (IVT) injection of iron induces acute photoreceptor death, lipid peroxidation, and autofluorescence (AF). Herein, we extend this work, finding surprising chronic features of the model: geographic atrophy and sympathetic ophthalmia. We provide new mechanistic insights derived from focal AF in the photoreceptors, quantification of bisretinoids, and localization of carboxyethyl pyrrole, an oxidized adduct of docosahexaenoic acid associated with AMD. In mice given IVT ferric ammonium citrate (FAC), RPE died in patches that slowly expanded at their borders, like human geographic atrophy. There was green AF in the photoreceptor ellipsoid, a mitochondria‐rich region, 4 h after injection, followed later by gold AF in rod outer segments, RPE and subretinal myeloid cells. The green AF signature is consistent with flavin adenine dinucleotide, while measured increases in the bisretinoid all‐trans‐retinal dimer are consistent with the gold AF. FAC induced formation carboxyethyl pyrrole accumulation first in photoreceptors, then in RPE and myeloid cells. Quantitative PCR on neural retina and RPE indicated antioxidant upregulation and inflammation. Unexpectedly, reminiscent of sympathetic ophthalmia, autofluorescent myeloid cells containing abundant iron infiltrated the saline‐injected fellow eyes only if the contralateral eye had received IVT FAC. These findings provide mechanistic insights into the potential toxicity caused by AMD‐associated retinal iron accumulation. The mouse model will be useful for testing antioxidants, iron chelators, ferroptosis inhibitors, anti‐inflammatory medications, and choroidal neovascularization inhibitors.
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Affiliation(s)
- Yingrui Liu
- Department of Ophthalmology The Second Hospital of Jilin University Changchun China
- F.M. Kirby Center for Molecular Ophthalmology Scheie Eye Institute Perelman School of Medicine at the University of Pennsylvania Philadelphia Pennsylvania USA
| | - Brent A. Bell
- F.M. Kirby Center for Molecular Ophthalmology Scheie Eye Institute Perelman School of Medicine at the University of Pennsylvania Philadelphia Pennsylvania USA
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology Scheie Eye Institute Perelman School of Medicine at the University of Pennsylvania Philadelphia Pennsylvania USA
| | - Hye J. Kim
- Department of Ophthalmology Harkness Eye Institute Columbia University Medical Center New York New York USA
| | - Jacob K. Sterling
- F.M. Kirby Center for Molecular Ophthalmology Scheie Eye Institute Perelman School of Medicine at the University of Pennsylvania Philadelphia Pennsylvania USA
| | - Benjamin J. Kim
- Department of Ophthalmology Scheie Eye Institute University of Pennsylvania Philadelphia Pennsylvania USA
| | - Maura Poli
- Department of Molecular and Translational Medicine University of Brescia Brescia Italy
| | - Michelle Guo
- F.M. Kirby Center for Molecular Ophthalmology Scheie Eye Institute Perelman School of Medicine at the University of Pennsylvania Philadelphia Pennsylvania USA
| | - Kevin Zhang
- F.M. Kirby Center for Molecular Ophthalmology Scheie Eye Institute Perelman School of Medicine at the University of Pennsylvania Philadelphia Pennsylvania USA
| | - Aditya Rao
- Department of Molecular Life Science University of Pennsylvania Philadelphia Pennsylvania USA
| | - Janet R. Sparrow
- Department of Ophthalmology Harkness Eye Institute Columbia University Medical Center New York New York USA
| | - Guanfang Su
- Department of Ophthalmology The Second Hospital of Jilin University Changchun China
| | - Joshua L. Dunaief
- F.M. Kirby Center for Molecular Ophthalmology Scheie Eye Institute Perelman School of Medicine at the University of Pennsylvania Philadelphia Pennsylvania USA
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11
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Camarena V, Huff TC, Wang G. Epigenomic regulation by labile iron. Free Radic Biol Med 2021; 170:44-49. [PMID: 33493555 PMCID: PMC8217092 DOI: 10.1016/j.freeradbiomed.2021.01.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/17/2020] [Accepted: 01/11/2021] [Indexed: 12/21/2022]
Abstract
Iron is an essential micronutrient metal for cellular functions but can generate highly reactive oxygen species resulting in oxidative damage. For these reasons its uptake and metabolism is highly regulated. A small but dynamic fraction of ferrous iron inside the cell, termed intracellular labile iron, is redox-reactive and ready to participate multiples reactions of intracellular enzymes. Due to its nature its determination and precise quantification has been a roadblock. However, recent progress in the development of intracellular labile iron probes are allowing the reevaluation of our current understanding and unmasking new functions. The role of intracellular labile iron in regulating the epigenome was recently discovered. This chapter examine how intracellular labile iron can modulate histone and DNA demethylation and how its pool can mediate a signaling pathway from cAMP serving as a sensor of the metabolic needs of the cells.
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Affiliation(s)
- Vladimir Camarena
- John P. Hussman Institute for Human Genomics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Tyler C Huff
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Gaofeng Wang
- John P. Hussman Institute for Human Genomics, Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
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12
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Zhao T, Guo X, Sun Y. Iron Accumulation and Lipid Peroxidation in the Aging Retina: Implication of Ferroptosis in Age-Related Macular Degeneration. Aging Dis 2021; 12:529-551. [PMID: 33815881 PMCID: PMC7990372 DOI: 10.14336/ad.2020.0912] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 09/12/2020] [Indexed: 01/19/2023] Open
Abstract
Iron is an essential component in many biological processes in the human body. It is critical for the visual phototransduction cascade in the retina. However, excess iron can be toxic. Iron accumulation and reduced efficiency of intracellular antioxidative defense systems predispose the aging retina to oxidative stress-induced cell death. Age-related macular degeneration (AMD) is characterized by retinal iron accumulation and lipid peroxidation. The mechanisms underlying AMD include oxidative stress-mediated death of retinal pigment epithelium (RPE) cells and subsequent death of retinal photoreceptors. Understanding the mechanism of the disruption of iron and redox homeostasis in the aging retina and AMD is crucial to decipher these mechanisms of cell death and AMD pathogenesis. The mechanisms of retinal cell death in AMD are an area of active investigation; previous studies have proposed several types of cell death as major mechanisms. Ferroptosis, a newly discovered programmed cell death pathway, has been associated with the pathogenesis of several neurodegenerative diseases. Ferroptosis is initiated by lipid peroxidation and is characterized by iron-dependent accumulation. In this review, we provide an overview of the mechanisms of iron accumulation and lipid peroxidation in the aging retina and AMD, with an emphasis on ferroptosis.
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Affiliation(s)
- Tantai Zhao
- 1Department of Ophthalmology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China.,2Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, China
| | - Xiaojian Guo
- 1Department of Ophthalmology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China.,2Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, China
| | - Yun Sun
- 1Department of Ophthalmology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China.,2Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, China
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13
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Kondkar AA, Azad TA, Sultan T, Osman EA, Almobarak FA, Al-Obeidan SA. Association of rs12997 variant in the ACVR1 gene: a member of bone morphogenic protein signaling pathway with primary open-angle glaucoma in a Saudi cohort. J Investig Med 2021; 69:402-407. [PMID: 33443061 DOI: 10.1136/jim-2020-001596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2020] [Indexed: 12/18/2022]
Abstract
We investigated the association between variants rs12997 in activin A receptor type I (ACVR1) and rs1043784 in BMP6 located in the 3' untranslated region, and primary open-angle glaucoma (POAG). The retrospective case-control study used TaqMan real-time PCR assay to genotype 400 subjects, including 150 patients with POAG and 250 controls. The minor 'G' allele of rs12997 in ACVR1 showed significant association with POAG (p=0.027, OR=1.39, 95% CI=1.03 to 1.87). Likewise, rs12997 genotypes showed moderate association with POAG in recessive (p=0.048, OR=1.80, 95% CI=1.01 to 3.20) and log-additive models (p=0.030, OR=1.39, 95% CI=1.03 to 1.87), but did not survive Bonferroni correction. Rs1043784 in BMP6 showed no associations. Furthermore, rs12997 G/G genotype significantly (p=0.033) increased the risk of POAG (twofolds) independent of age, sex and rs1043784 genotypes in regression analysis. However, clinical variables such as intraocular pressure and cup/disc ratio showed no association with both the polymorphisms. To conclude, the study shows a modest association between rs12997 in the ACVR1 gene, a member of the bone morphogenic protein signaling pathway and POAG. However, the results need further replication in large population-based cohorts and different ethnicities to validate its role as an important genetic biomarker.
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Affiliation(s)
- Altaf A Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia .,Glaucoma Research Chair in Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.,King Saud University Medical City, King Saud University, Riyadh, Saudi Arabia
| | - Taif A Azad
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Tahira Sultan
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Essam A Osman
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Faisal A Almobarak
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.,Glaucoma Research Chair in Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Saleh A Al-Obeidan
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.,Glaucoma Research Chair in Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
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14
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Retinal Degeneration and Alzheimer's Disease: An Evolving Link. Int J Mol Sci 2020; 21:ijms21197290. [PMID: 33023198 PMCID: PMC7582766 DOI: 10.3390/ijms21197290] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 09/15/2020] [Accepted: 09/25/2020] [Indexed: 12/13/2022] Open
Abstract
Age-related macular degeneration (AMD) and glaucoma are degenerative conditions of the retina and a significant cause of irreversible blindness in developed countries. Alzheimer’s disease (AD), the most common dementia of the elderly, is often associated with AMD and glaucoma. The cardinal features of AD include extracellular accumulation of amyloid β (Aβ) and intracellular deposits of hyper-phosphorylated tau (p-tau). Neuroinflammation and brain iron dyshomeostasis accompany Aβ and p-tau deposits and, together, lead to progressive neuronal death and dementia. The accumulation of Aβ and iron in drusen, the hallmark of AMD, and Aβ and p-tau in retinal ganglion cells (RGC), the main retinal cell type implicated in glaucoma, and accompanying inflammation suggest overlapping pathology. Visual abnormalities are prominent in AD and are believed to develop before cognitive decline. Some are caused by degeneration of the visual cortex, while others are due to RGC loss or AMD-associated retinal degeneration. Here, we review recent information on Aβ, p-tau, chronic inflammation, and iron dyshomeostasis as common pathogenic mechanisms linking the three degenerative conditions, and iron chelation as a common therapeutic option for these disorders. Additionally discussed is the role of prion protein, infamous for prion disorders, in Aβ-mediated toxicity and, paradoxically, in neuroprotection.
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15
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Kondkar AA, Sultan T, Azad TA, Osman EA, Almobarak FA, Al-Obeidan SA. Association analysis of polymorphisms rs12997 in ACVR1 and rs1043784 in BMP6 genes involved in bone morphogenic protein signaling pathway in primary angle-closure and pseudoexfoliation glaucoma patients of Saudi origin. BMC MEDICAL GENETICS 2020; 21:145. [PMID: 32641001 PMCID: PMC7346469 DOI: 10.1186/s12881-020-01076-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/24/2020] [Indexed: 01/08/2023]
Abstract
Background Glaucoma is a polygenic neurodegenerative disease and the second most common cause of blindness in Saudi Arabia. To test the hypothesis that genetic variants in the genes involved in the bone morphogenic protein (BMP) signaling pathway may be associated with glaucoma, we investigated the association between 3′ untranslated region variants, rs12997 in ACVR1 and rs1043784 in BMP6, and primary angle-closure glaucoma (PACG) and pseudoexfoliation glaucoma (PXG). Methods In a case-control study, TaqMan® real-time PCR-based genotyping was done in 444 subjects consisting of 250 controls, 101 PACG and 95 PXG cases, and tested for genetic association with glaucoma-types and other clinical phenotypes. Results Rs12997[G] allele in ACVR1 exhibited significant 2-fold increased risk of PACG (p = 0.005) in women but not in men. Similarly, genotype analysis also showed that subjects carrying rs12997[G/G] genotype were at > 2-fold risk of PACG that remained significant after adjustment for age, sex, and Bonferroni correction in the recessive model. Furthermore, this effect was also significant in women only. In PXG, the rs12997[G/G] genotype showed a significant trend towards increased risk of the disease (OR = 2.04, 95% CI = 0.99–4.18, p = 0.049) but did not survive the Bonferroni correction. Regression analysis showed that rs12997[G/G] genotype was a significant predictor of PACG independent of age, sex, and rs1043784 genotypes. Likewise, age and rs12997[G/G] genotype showed significant effect on PXG outcome. The rs12997[A/G] genotype showed significant association with cup/disc ratio as compared to wild-type (p = 0.005) in PXG. Genotype and allele frequencies of rs1043784 in BMP6 did not show any significant association either with PACG or PXG. Conclusions Our results suggest that the polymorphism rs12997 in the ACVR1 gene involved in the BMP signaling pathway is significantly associated with PACG and PXG in a Saudi cohort. This is the first study to associate this variant/gene with PACG and PXG. However, further studies would be needed to replicate these findings in a large population-based cohort.
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Affiliation(s)
- Altaf A Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, P.O. Box 245, Riyadh, 11411, Saudi Arabia. .,Glaucoma Research Chair in Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
| | - Tahira Sultan
- Department of Ophthalmology, College of Medicine, King Saud University, P.O. Box 245, Riyadh, 11411, Saudi Arabia
| | - Taif A Azad
- Department of Ophthalmology, College of Medicine, King Saud University, P.O. Box 245, Riyadh, 11411, Saudi Arabia
| | - Essam A Osman
- Department of Ophthalmology, College of Medicine, King Saud University, P.O. Box 245, Riyadh, 11411, Saudi Arabia
| | - Faisal A Almobarak
- Department of Ophthalmology, College of Medicine, King Saud University, P.O. Box 245, Riyadh, 11411, Saudi Arabia.,Glaucoma Research Chair in Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Saleh A Al-Obeidan
- Department of Ophthalmology, College of Medicine, King Saud University, P.O. Box 245, Riyadh, 11411, Saudi Arabia.,Glaucoma Research Chair in Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
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16
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Courtois Y, Youale J, Behar-Cohen F, Picard É. [Iron and age-related macular degeneration: a new track]. Med Sci (Paris) 2020; 36:616-625. [PMID: 32614313 DOI: 10.1051/medsci/2020096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Iron has a fundamental role for cell physiology and especially in retina as a cofactor of many pathways of the visual transduction. A tightly regulated homeostasis avoids the accumulation of prooxidant and proinflammatory free iron. A dysfunction of iron retinal homeostasis is associated with many genetic or age-related degenerative diseases such as age-related macular degeneration (AMD). Here, we describe various mechanisms reported during AMD, enhanced by iron accumulation and its homeostasis dysregulation. We have investigated a local treatment with transferrin, the natural iron carrier, to control these pathological pathways and iron dysfunction, without side effects. Iron has a central role in pathogenesis of AMD and is a target for futures therapies.
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Affiliation(s)
- Yves Courtois
- Centre de Recherche des Cordeliers, Inserm, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, UMRS1138, 15 rue de l'École de Médecine, F-75006 Paris, France
| | - Jenny Youale
- Centre de Recherche des Cordeliers, Inserm, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, UMRS1138, 15 rue de l'École de Médecine, F-75006 Paris, France
| | - Francine Behar-Cohen
- Hôpital Cochin, AP-HP, Assistance Publique-Hôpitaux de Paris, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France
| | - Émilie Picard
- Centre de Recherche des Cordeliers, Inserm, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, UMRS1138, 15 rue de l'École de Médecine, F-75006 Paris, France
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17
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Shu W, Baumann BH, Song Y, Liu Y, Wu X, Dunaief JL. Ferrous but not ferric iron sulfate kills photoreceptors and induces photoreceptor-dependent RPE autofluorescence. Redox Biol 2020; 34:101469. [PMID: 32362442 PMCID: PMC7327978 DOI: 10.1016/j.redox.2020.101469] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/28/2020] [Accepted: 02/16/2020] [Indexed: 11/18/2022] Open
Abstract
Iron has been implicated in the pathogenesis of retinal degenerative diseases, including ocular siderosis. However, the mechanisms of iron-induced retinal toxicity are incompletely understood. Previous work shows that intravitreal injection of Fe2+ leads to photoreceptor (PR) oxidative stress, resulting in PR death within 14 days, and cones are more susceptible than rods to iron-induced oxidative damage. In order to further investigate the mechanism of intravitreal iron-induced retinal toxicity and shed light on mechanisms of iron-induced retinopathy in other mouse models, Fe2+, Fe3+, or saline were injected into the vitreous of adult wild-type mice. Pre-treatment with Ferrostatin-1 was used to investigate whether iron-induced retinal toxicity resulted from ferroptosis. Color and autofluorescence in vivo retinal imaging and optical coherence tomography were performed on day 2 and day 7 post-injection. Eyes were collected for quantitative PCR and Western analysis on day 1 and for immunofluorescence on both day 2 and 7. In vivo imaging and immunofluorescence revealed that Fe2+, but not Fe3+, induced PR oxidative damage and autofluorescence on day 2, resulting in PR death and retinal pigment epithelial cell (RPE) autofluorescence on day 7. Quantitative PCR and Western analysis on day 1 indicated that both Fe2+ and Fe3+ induced iron accumulation in the retina. However, only Fe2+ elevated levels of oxidative stress markers and components of ferroptosis in the retina, and killed PRs. Ferrostatin-1 failed to protect the retina from Fe2+-induced oxidative damage. To investigate the mechanism of Fe2+-induced RPE autofluorescence, rd10 mutant mice aged 6 weeks, with almost total loss of PRs, were given intravitreal Fe2+ or Fe3+ injections: neither induced RPE autofluorescence. This result suggests Fe2+-induced RPE autofluorescence in wild-type mice resulted from phagocytosed, oxidized outer segments. Together these data suggest that intraretinal Fe2+ causes PR oxidative stress, leading to PR death and RPE autofluorescence. Intravitreal ferrous but not ferric sulfate induces photoreceptor oxidative stress. Ferrous sulfate causes photoreceptor death within 7 days. Ferrous sulfate causes outer segment and RPE autofluorescence. RPE autofluorescence does not develop in retinas lacking photoreceptors. Ferrous sulfate activates a subset of ferroptosis genes.
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Affiliation(s)
- Wanting Shu
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, No. 100 Haining Road, Shanghai, 200080, China; F.M.Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA.
| | - Bailey H Baumann
- F.M.Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA.
| | - Ying Song
- F.M.Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA.
| | - Yingrui Liu
- F.M.Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA; Department of Ophthalmology, The Second Hospital of Jilin University, No. 218 Ziqiang Street, Changchun, Jilin, 130041, China.
| | - Xingwei Wu
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, No. 100 Haining Road, Shanghai, 200080, China.
| | - Joshua L Dunaief
- F.M.Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA.
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18
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Picard E, Daruich A, Youale J, Courtois Y, Behar-Cohen F. From Rust to Quantum Biology: The Role of Iron in Retina Physiopathology. Cells 2020; 9:cells9030705. [PMID: 32183063 PMCID: PMC7140613 DOI: 10.3390/cells9030705] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/07/2020] [Accepted: 03/09/2020] [Indexed: 12/24/2022] Open
Abstract
Iron is essential for cell survival and function. It is a transition metal, that could change its oxidation state from Fe2+ to Fe3+ involving an electron transfer, the key of vital functions but also organ dysfunctions. The goal of this review is to illustrate the primordial role of iron and local iron homeostasis in retinal physiology and vision, as well as the pathological consequences of iron excess in animal models of retinal degeneration and in human retinal diseases. We summarize evidence of the potential therapeutic effect of iron chelation in retinal diseases and especially the interest of transferrin, a ubiquitous endogenous iron-binding protein, having the ability to treat or delay degenerative retinal diseases.
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Affiliation(s)
- Emilie Picard
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Team 17, F-75006 Paris, France; (A.D.); (J.Y.); (Y.C.); (F.B.-C.)
- Correspondence: ; Tel.: +331-44-27-81-82
| | - Alejandra Daruich
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Team 17, F-75006 Paris, France; (A.D.); (J.Y.); (Y.C.); (F.B.-C.)
- Ophthalmology Department, Necker-Enfants Malades University Hospital, APHP, 75015 Paris, France
| | - Jenny Youale
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Team 17, F-75006 Paris, France; (A.D.); (J.Y.); (Y.C.); (F.B.-C.)
| | - Yves Courtois
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Team 17, F-75006 Paris, France; (A.D.); (J.Y.); (Y.C.); (F.B.-C.)
| | - Francine Behar-Cohen
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Team 17, F-75006 Paris, France; (A.D.); (J.Y.); (Y.C.); (F.B.-C.)
- Ophtalmopole, Cochin Hospital, AP-HP, Assistance Publique Hôpitaux de Paris, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France
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Chen L, Ma B, Liu X, Hao Y, Yang X, Liu M. H 2 O 2 induces oxidative stress damage through the BMP-6/SMAD/hepcidin axis. Dev Growth Differ 2020; 62:139-146. [PMID: 32012242 DOI: 10.1111/dgd.12650] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/03/2019] [Accepted: 01/07/2020] [Indexed: 12/13/2022]
Abstract
Age-related macular degeneration (AMD) is one of the leading causes of blindness in elderly individuals worldwide. Oxidative stress injury to retinal pigment epithelial (RPE) cells plays a major role in the pathogenesis of AMD. The purpose of this study was to observe the correlation between Hepcidin and neovascular age-related macular degeneration (nAMD) and to further observe whether oxidative stress can inhibit Hepcidin expression through relevant signaling pathways to produce oxidative damage. We compared the concentrations of Hepcidin in the aqueous humor of nAMD patients and a control group and found that the concentration of Hepcidin was lower in nAMD patients. Through PCR and western blotting, we observed that H2 O2 can significantly inhibit the expression of Bone morphogenetic protein-6 (BMP-6) and Hepcidin and increase the intracellular iron concentration in RPE cells, while BMP-6 can reverse the inhibition of Hepcidin and the increase in iron concentration caused by H2 O2 . In addition, alterations in smad1 and smad5 expression were examined, and pretreatment with BMP-6 was demonstrated to reduce H2 O2 -induced activation of smad1 and smad5. The effects of BMP-6 were attenuated by smad1 and smad5 siRNA, further verifying that oxidative stress inhibits the expression of Hepcidin by inhibiting activation of the BMP/SMAD signaling pathway. To some extent, this study verified that oxidative stress injury plays a role in nAMD by affecting the level of hepcidin, which lays a foundation for exploring new methods to treat nAMD.
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Affiliation(s)
- Li Chen
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Bo Ma
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xuan Liu
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yang Hao
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiaogang Yang
- Department of Ophthalmology, Xi'an No. 1 Hospital, Xi'an, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Ming Liu
- Department of Ophthalmology, Xi'an No. 1 Hospital, Xi'an, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
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Shu W, Baumann BH, Song Y, Liu Y, Wu X, Dunaief JL. Iron Accumulates in Retinal Vascular Endothelial Cells But Has Minimal Retinal Penetration After IP Iron Dextran Injection in Mice. Invest Ophthalmol Vis Sci 2020; 60:4378-4387. [PMID: 31634395 PMCID: PMC6798310 DOI: 10.1167/iovs.19-28250] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Purpose Iron supplementation therapy is used for iron-deficiency anemia but has been associated with macular degeneration in a 43-year-old patient. Iron entry into the neurosensory retina (NSR) can be toxic. It is important to determine conditions under which serum iron might cross the blood retinal barrier (BRB) into the NSR. Herein, an established mouse model of systemic iron overload using high-dose intraperitoneal iron dextran (IP FeDex) was studied. In addition, because the NSR expresses the iron regulatory hormone hepcidin, which could limit iron influx into the NSR, we gave retina-specific hepcidin knockout (RS-HepcKO) mice IP FeDex to test this possibility. Methods Wild-type (WT) and RS-HepcKO mice were given IP FeDex. In vivo retina imaging was performed. Blood and tissues were analyzed for iron levels. Quantitative PCR was used to measure levels of mRNAs encoding iron regulatory and photoreceptor-specific genes. Ferritin and albumin were localized in the retina by immunofluorescence. Results IP FeDex in both WT and RS-HepcKO mice induced high levels of iron in the liver, serum, retinal vascular endothelial cells (rVECs), and RPE, but not the NSR. The BRB remained intact. Retinal degeneration did not occur. Conclusions Following injection of high-dose IP FeDex, iron accumulated in the BRB, but not the NSR. Thus, the BRB can shield the NSR from iron delivered in this manner. This ability is not dependent on NSR hepcidin production.
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Affiliation(s)
- Wanting Shu
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai, China.,F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Bailey H Baumann
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Yingrui Liu
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States.,Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, Jilin, China
| | - Xingwei Wu
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai, China
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States
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Baumann BH, Shu W, Song Y, Simpson EM, Lakhal-Littleton S, Dunaief JL. Ferroportin-mediated iron export from vascular endothelial cells in retina and brain. Exp Eye Res 2019; 187:107728. [PMID: 31323276 PMCID: PMC6759385 DOI: 10.1016/j.exer.2019.107728] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/05/2019] [Accepted: 07/15/2019] [Indexed: 12/29/2022]
Abstract
Retinal iron accumulation has been implicated in the pathogenesis of age-related macular degeneration (AMD) and other neurodegenerative diseases. The retina and the brain are protected from the systemic circulation by the blood retinal barrier (BRB) and blood brain barrier (BBB), respectively. Iron levels within the retina and brain need to be tightly regulated to prevent oxidative injury. The method of iron entry through the retina and brain vascular endothelial cells (r&bVECs), an essential component of the BRB and BBB, is not fully understood. However, localization of the cellular iron exporter, ferroportin (Fpn), to the abluminal membrane of these cells, leads to the hypothesis that Fpn may play an important role in the import of iron across the BRB and BBB. To test this hypothesis, a mouse model with deletion of Fpn within the VECs in both the retina and the brain was developed through tail vein injection of AAV9-Ple261(CLDN5)-icre to both experimental Fpnf/f, and control Fpn+/+ mice at P21. Mice were aged to 9 mo and changes in retinal and brain iron distribution were observed. In vivo fundus imaging and quantitative serum iron detection were used for model validation. Eyes and brains were collected for immunofluorescence. Deletion of Fpn from the retinal and brain VECs leads to ferritin-L accumulation, an indicator of elevated iron levels, in the retinal and brain VECs. This occurred despite lower serum iron levels in the experimental mice. This result suggests that Fpn normally transfers iron from retinal and brain VECs into the retina and brain. These results help to better define the method of retina and brain iron import and will increase understanding of neurodegenerative diseases involving iron accumulation.
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Affiliation(s)
- Bailey H Baumann
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA.
| | - Wanting Shu
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA; Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, No. 100 Haining Road, Shanghai, 200080, China.
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA.
| | - Elizabeth M Simpson
- Centre for Molecular Medicine and Therapeutics at the Child & Family Research Institute, University of British Columbia, 950 W 28 Ave, Vancouver, BC, V5Z 4H4, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6H 3N1, Canada.
| | - Samira Lakhal-Littleton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, 305 Stellar-Chance Laboratory, 422 Curie Blvd, Philadelphia, PA, 19104, USA.
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22
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Zhang L, Wang YC, Okada Y, Zhang S, Anderson M, Liu CY, Zhang Y. Aberrant expression of a stabilized β-catenin mutant in keratocytes inhibits mouse corneal epithelial stratification. Sci Rep 2019; 9:1919. [PMID: 30760729 PMCID: PMC6374483 DOI: 10.1038/s41598-018-36392-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 11/16/2018] [Indexed: 12/25/2022] Open
Abstract
We previously reported that genetic deletion of β-catenin in mouse corneal keratocytes resulted in precocious corneal epithelial stratification. In this study, to strengthen the notion that corneal keratocyte-derived Wnt/β-catenin signaling regulates corneal epithelial stratification during mouse development, we examined the consequence of conditional overexpression of a stabilized β-catenin mutant (Ctnnb1ΔE3) in corneal keratocytes via a doxycycline (Dox)-inducible compound transgenic mouse strain. Histological analysis showed that conditional overexpression of Ctnnb1ΔE3 in keratocytes inhibited corneal epithelial stratification during postnatal development. Unlike the corneal epithelium of the littermate controls, which consisted of 5-6 cell layers at postnatal day 21 (P21), the mutant corneal epithelium contained 1-2 or 2-3 cell layers after Dox induction from embryonic day 0 (E0) to P21 and from E9 to P21, respectively. X-gal staining revealed that Wnt/β-catenin signaling activity was significantly elevated in the corneal keratocytes of the Dox-induced mutant mice, compared to the littermate controls. Furthermore, RT-qPCR and immunostaining data indicated that the expression of Bmp4 and ΔNp63 was downregulated in the mutant corneas, which was associated with reduced corneal epithelial proliferation in mutant epithelium, as revealed by immunofluorescent staining. However, the expression of Krt12, Krt14 and Pax6 in the mutant corneas was not altered after overexpression of Ctnnb1ΔE3 mutant protein in corneal keratocytes. Overall, mutant β-catenin accumulation in the corneal keratocytes inhibited corneal epithelial stratification probably through downregulation of Bmp4 and ΔNp63 in the corneal epithelium.
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Affiliation(s)
- Lingling Zhang
- School of Optometry, Indiana University, Bloomington, IN, 47405, USA
| | - Yen-Chiao Wang
- School of Optometry, Indiana University, Bloomington, IN, 47405, USA
| | - Yuka Okada
- School of Optometry, Indiana University, Bloomington, IN, 47405, USA
- Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan
| | - Suohui Zhang
- Comprehensive Cancer Center-Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, School of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Matthew Anderson
- School of Optometry, Indiana University, Bloomington, IN, 47405, USA
| | - Chia-Yang Liu
- School of Optometry, Indiana University, Bloomington, IN, 47405, USA.
| | - Yujin Zhang
- School of Optometry, Indiana University, Bloomington, IN, 47405, USA.
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23
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Chen L, Liu M, Luan Y, Liu Y, Zhang Z, Ma B, Liu X, Liu Y. BMP‑6 protects retinal pigment epithelial cells from oxidative stress‑induced injury by inhibiting the MAPK signaling pathways. Int J Mol Med 2018; 42:1096-1105. [PMID: 29767257 DOI: 10.3892/ijmm.2018.3675] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 05/10/2018] [Indexed: 11/06/2022] Open
Abstract
Worldwide, neovascular age‑related macular degeneration (nAMD) is one of the most common causes of blindness in the elderly. In particular, degeneration of retinal pigment epithelial (RPE) cells represents the main pathological process in the development of nAMD, and oxidative stress serves a major role. The present study aimed to investigate the association between bone morphogenetic protein 6 (BMP‑6) and nAMD. BMP‑6 concentration was significantly reduced in patients with wet nAMD compared with in the control group. Furthermore, the present study investigated the protective effects of BMP‑6 on RPE cells following oxidative stress‑induced injury. Cell Counting Kit‑8 assay and terminal deoxynucleotidyl transferase dUTP nick‑end labeling staining demonstrated that BMP‑6 increased RPE cell viability, which was decreased following treatment with hydrogen peroxide (H2O2), and reduced H2O2‑induced apoptosis. In addition, western blotting revealed that BMP‑6 reversed the decrease in pro‑caspase‑3 levels and the dysregulation of the B‑cell lymphoma 2 (Bcl‑2)/Bcl‑2‑associated X protein (Bax) balance caused by H2O2. In addition, alterations in c‑Jun N‑terminal protein kinase (JNK) and p38 mitogen‑activated protein kinase (MAPK) expression were examined, and pretreatment with BMP‑6 was demonstrated to reduce H2O2‑induced activation of JNK and p38 MAPK. Conversely, the effects of BMP‑6 were attenuated by its inhibitor noggin. In conclusion, the present study demonstrated that BMP‑6 may protect RPE cells from oxidative stress injury to a certain extent, which may be associated with alterations in the MAPK signaling pathway. However, the specific mechanism of action underlying this effect requires further investigation. Overall, the present study laid a foundation for exploring novel nAMD treatment methods.
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Affiliation(s)
- Li Chen
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Ming Liu
- Department of Ophthalmology, The First Hospital of Xi'an, Xi'an, Shaanxi 710002, P.R. China
| | - Yan Luan
- Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, P.R. China
| | - Yingfei Liu
- Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, P.R. China
| | - Zhichao Zhang
- Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, P.R. China
| | - Bo Ma
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Xuan Liu
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yong Liu
- Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, P.R. China
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24
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Vela D. Hepcidin, an emerging and important player in brain iron homeostasis. J Transl Med 2018; 16:25. [PMID: 29415739 PMCID: PMC5803919 DOI: 10.1186/s12967-018-1399-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/31/2018] [Indexed: 02/08/2023] Open
Abstract
Hepcidin is emerging as a new important factor in brain iron homeostasis. Studies suggest that there are two sources of hepcidin in the brain; one is local and the other comes from the circulation. Little is known about the molecular mediators of local hepcidin expression, but inflammation and iron-load have been shown to induce hepcidin expression in the brain. The most important source of hepcidin in the brain are glial cells. Role of hepcidin in brain functions has been observed during neuronal iron-load and brain hemorrhage, where secretion of abundant hepcidin is related with the severity of brain damage. This damage can be reversed by blocking systemic and local hepcidin secretion. Studies have yet to unveil its role in other brain conditions, but the rationale exists, since these conditions are characterized by overexpression of the factors that stimulate brain hepcidin expression, such as inflammation, hypoxia and iron-overload.
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Affiliation(s)
- Driton Vela
- Department of Physiology, Faculty of Medicine, University of Prishtina, Martyr's Boulevard n.n., 10000, Prishtina, Kosova.
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25
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Wu D, Wen X, Liu W, Xu L, Ye B, Zhou Y. A composite mouse model of aplastic anemia complicated with iron overload. Exp Ther Med 2017; 15:1449-1455. [PMID: 29434729 PMCID: PMC5776174 DOI: 10.3892/etm.2017.5523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/19/2017] [Indexed: 11/06/2022] Open
Abstract
Iron overload is commonly encountered during the course of aplastic anemia (AA), but no composite animal model has been developed yet, which hinders drug research. In the present study, the optimal dosage and duration of intraperitoneal iron dextran injection for the development of an iron overload model in mice were explored. A composite model of AA was successfully established on the principle of immune-mediated bone marrow failure. Liver volume, peripheral hemogram, bone marrow pathology, serum iron, serum ferritin, pathological iron deposition in multiple organs (liver, bone marrow, spleen), liver hepcidin, and bone morphogenetic protein 6 (BMP6), SMAD family member 4 (SMAD4) and transferrin receptor 2 (TfR2) mRNA expression levels were compared among the normal control, AA, iron overload and composite model groups to validate the composite model, and explore the pathogenesis and features of iron overload in this model. The results indicated marked increases in iron deposits, with significantly increased liver/body weight ratios as well as serum iron and ferritin in the iron overload and composite model groups as compared with the normal control and AA groups (P<0.05). There were marked abnormalities in iron regulation gene expression between the AA and composite model groups, as seen by the significant decrease of hepcidin expression in the liver (P<0.01) that paralleled the changes in BMP6, SMAD4, and TfR2. In summary, a composite mouse model with iron overload and AA was successfully established, and AA was indicated to possibly have a critical role in abnormal iron metabolism, which promoted the development of iron deposits.
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Affiliation(s)
- Dijiong Wu
- Department of Hematology, First Affiliated Hospital of Zhejiang Chinese Medical University, National Clinical Research Base of Traditional Chinese Medicine, Hangzhou, Zhejiang 310006, P.R. China
| | - Xiaowen Wen
- Department of Internal Medicine, Central Hospital of Jinhua Affiliated to Zhejiang University, Jinhua, Zhejiang 321001, P.R. China
| | - Wenbin Liu
- Department of Hematology, First Affiliated Hospital of Zhejiang Chinese Medical University, National Clinical Research Base of Traditional Chinese Medicine, Hangzhou, Zhejiang 310006, P.R. China
| | - Linlong Xu
- First Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, Zhejiang 310053, P.R. China
| | - Baodong Ye
- Department of Hematology, First Affiliated Hospital of Zhejiang Chinese Medical University, National Clinical Research Base of Traditional Chinese Medicine, Hangzhou, Zhejiang 310006, P.R. China
| | - Yuhong Zhou
- Department of Hematology, First Affiliated Hospital of Zhejiang Chinese Medical University, National Clinical Research Base of Traditional Chinese Medicine, Hangzhou, Zhejiang 310006, P.R. China
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26
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Arjunan P, Gnanaprakasam JP, Ananth S, Romej MA, Rajalakshmi VK, Prasad PD, Martin PM, Gurusamy M, Thangaraju M, Bhutia YD, Ganapathy V. Increased Retinal Expression of the Pro-Angiogenic Receptor GPR91 via BMP6 in a Mouse Model of Juvenile Hemochromatosis. Invest Ophthalmol Vis Sci 2016; 57:1612-9. [PMID: 27046124 PMCID: PMC4824383 DOI: 10.1167/iovs.15-17437] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Hemochromatosis, an iron-overload disease, occurs as adult and juvenile types. Mutations in hemojuvelin (HJV), an iron-regulatory protein and a bone morphogenetic protein (BMP) coreceptor, underlie most of the juvenile type. Hjv(-/-) mice accumulate excess iron in retina and exhibit aberrant vascularization and angiomas. A succinate receptor, GPR91, is pro-angiogenic in retina. We hypothesized that Hjv(-/-) retinas have increased BMP signaling and increased GPR91 expression as the basis of angiomas. METHODS Expression of GPR91 was examined by qPCR, immunofluorescence, and Western blot in wild-type and Hjv(-/-) mouse retinas and pRPE cells. Influence of excess iron and BMP6 on GPR91 expression was investigated in ARPE-19 cells, and wild-type and Hjv(-/-) pRPE cells. Succinate was used to activate GPR91 and determine the effects of GPR91 signaling on VEGF expression. Signaling of BMP6 was studied by the expression of Smad1/5/8 and pSmad4, and the BMP-target gene Id1. The interaction of pSmad4 with GPR91 promoter was studied by ChIP. RESULTS Expression of GPR91 was higher in Hjv(-/-) retinas and RPE than in wild-type counterparts. Unexpectedly, BMP signaling was increased, not decreased, in Hjv(-/-) retinas and RPE. Bone morphogenetic protein 6 induced GPR91 in RPE, suggesting that increased BMP signaling in Hjv(-/-) retinas was likely responsible for GPR91 upregulation. Exposure of RPE to excess iron and succinate as well as BMP6 and succinate increased VEGF expression. Bone morphogenetic protein 6 promoted the interaction of pSmad4 with GPR91 promoter in RPE. CONCLUSIONS G-protein-coupled receptor 91 is a BMP6 target and Hjv deletion enhances BMP signaling in retina, thus underscoring a role for excess iron and hemochromatosis in abnormal retinal vascularization.
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Affiliation(s)
- Pachiappan Arjunan
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States 2Department of Periodontics, Georgia Regents University, Augusta, Georgia, United States
| | - Jaya P Gnanaprakasam
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Sudha Ananth
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Michelle A Romej
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | | | - Puttur D Prasad
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Pamela M Martin
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Mariappan Gurusamy
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Muthusamy Thangaraju
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States
| | - Yangzom D Bhutia
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States 3Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States
| | - Vadivel Ganapathy
- Department of Biochemistry and Molecular Biology, Georgia Regents University, Augusta, Georgia, United States 3Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, United States
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27
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Lewis AM, Croughan WD, Aranibar N, Lee AG, Warrack B, Abu-Absi NR, Patel R, Drew B, Borys MC, Reily MD, Li ZJ. Understanding and Controlling Sialylation in a CHO Fc-Fusion Process. PLoS One 2016; 11:e0157111. [PMID: 27310468 PMCID: PMC4911072 DOI: 10.1371/journal.pone.0157111] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Accepted: 05/24/2016] [Indexed: 12/13/2022] Open
Abstract
A Chinese hamster ovary (CHO) bioprocess, where the product is a sialylated Fc-fusion protein, was operated at pilot and manufacturing scale and significant variation of sialylation level was observed. In order to more tightly control glycosylation profiles, we sought to identify the cause of variability. Untargeted metabolomics and transcriptomics methods were applied to select samples from the large scale runs. Lower sialylation was correlated with elevated mannose levels, a shift in glucose metabolism, and increased oxidative stress response. Using a 5-L scale model operated with a reduced dissolved oxygen set point, we were able to reproduce the phenotypic profiles observed at manufacturing scale including lower sialylation, higher lactate and lower ammonia levels. Targeted transcriptomics and metabolomics confirmed that reduced oxygen levels resulted in increased mannose levels, a shift towards glycolysis, and increased oxidative stress response similar to the manufacturing scale. Finally, we propose a biological mechanism linking large scale operation and sialylation variation. Oxidative stress results from gas transfer limitations at large scale and the presence of oxygen dead-zones inducing upregulation of glycolysis and mannose biosynthesis, and downregulation of hexosamine biosynthesis and acetyl-CoA formation. The lower flux through the hexosamine pathway and reduced intracellular pools of acetyl-CoA led to reduced formation of N-acetylglucosamine and N-acetylneuraminic acid, both key building blocks of N-glycan structures. This study reports for the first time a link between oxidative stress and mammalian protein sialyation. In this study, process, analytical, metabolomic, and transcriptomic data at manufacturing, pilot, and laboratory scales were taken together to develop a systems level understanding of the process and identify oxygen limitation as the root cause of glycosylation variability.
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Affiliation(s)
- Amanda M. Lewis
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
- * E-mail:
| | - William D. Croughan
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
| | - Nelly Aranibar
- Research and Development, Bristol-Myers Squibb Company, Princeton, NJ, United States of America
| | - Alison G. Lee
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
| | - Bethanne Warrack
- Research and Development, Bristol-Myers Squibb Company, Princeton, NJ, United States of America
| | - Nicholas R. Abu-Absi
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
| | - Rutva Patel
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
| | - Barry Drew
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
| | - Michael C. Borys
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
| | - Michael D. Reily
- Research and Development, Bristol-Myers Squibb Company, Princeton, NJ, United States of America
| | - Zheng Jian Li
- Biologics Development, Global Manufacturing and Supply, Bristol-Myers Squibb Company, Devens, MA, United States of America
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Picard E, Le Rouzic Q, Oudar A, Berdugo M, El Sanharawi M, Andrieu-Soler C, Naud MC, Jonet L, Latour C, Klein C, Galiacy S, Malecaze F, Coppin H, Roth MP, Jeanny JC, Courtois Y, Behar-Cohen F. Targeting iron-mediated retinal degeneration by local delivery of transferrin. Free Radic Biol Med 2015; 89:1105-21. [PMID: 26454080 DOI: 10.1016/j.freeradbiomed.2015.08.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 08/07/2015] [Accepted: 08/10/2015] [Indexed: 12/11/2022]
Abstract
Iron is essential for retinal function but contributes to oxidative stress-mediated degeneration. Iron retinal homeostasis is highly regulated and transferrin (Tf), a potent iron chelator, is endogenously secreted by retinal cells. In this study, therapeutic potential of a local Tf delivery was evaluated in animal models of retinal degeneration. After intravitreal injection, Tf spread rapidly within the retina and accumulated in photoreceptors and retinal pigment epithelium, before reaching the blood circulation. Tf injected in the vitreous prior and, to a lesser extent, after light-induced retinal degeneration, efficiently protected the retina histology and function. We found an association between Tf treatment and the modulation of iron homeostasis resulting in a decrease of iron content and oxidative stress marker. The immunomodulation function of Tf could be seen through a reduction in macrophage/microglial activation as well as modulated inflammation responses. In a mouse model of hemochromatosis, Tf had the capacity to clear abnormal iron accumulation from retinas. And in the slow P23H rat model of retinal degeneration, a sustained release of Tf in the vitreous via non-viral gene therapy efficently slowed-down the photoreceptors death and preserved their function. These results clearly demonstrate the synergistic neuroprotective roles of Tf against retinal degeneration and allow identify Tf as an innovative and not toxic therapy for retinal diseases associated with oxidative stress.
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Affiliation(s)
- Emilie Picard
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France.
| | - Quentin Le Rouzic
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Antonin Oudar
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Marianne Berdugo
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Mohamed El Sanharawi
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Charlotte Andrieu-Soler
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Marie-Christine Naud
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Laurent Jonet
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Chloé Latour
- INSERM, U1043, Toulouse, France; CNRS, U5282, Toulouse, France; Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France
| | - Christophe Klein
- INSERM, U1138, CICC, Université René Descartes Sorbonne Paris Cité, Université Pierre et Marie Curie Paris, Centre de Recherche des Cordeliers, Paris, France
| | - Stéphane Galiacy
- INSERM U563, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France; Department of Ophthalmology, Purpan Hospital, Toulouse, France
| | - François Malecaze
- INSERM U563, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France; Department of Ophthalmology, Purpan Hospital, Toulouse, France
| | - Hélène Coppin
- INSERM, U1043, Toulouse, France; CNRS, U5282, Toulouse, France; Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France
| | - Marie-Paule Roth
- INSERM, U1043, Toulouse, France; CNRS, U5282, Toulouse, France; Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France
| | - Jean-Claude Jeanny
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Yves Courtois
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France
| | - Francine Behar-Cohen
- INSERM, UMRS 1138, team Behar-Cohen, From physiopathology of ocular diseases to clinical development, Centre de Recherche des Cordeliers, Paris, France; Université Pierre et Marie Curie-Paris 6, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Université René Descartes, Centre de Recherche des Cordeliers UMRS 1138, Paris, France; Jules Gonin Ophthalmic Hospital, Lausanne, Switzerland
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29
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Theurl M, Song D, Clark E, Sterling J, Grieco S, Altamura S, Galy B, Hentze M, Muckenthaler MU, Dunaief JL. Mice with hepcidin-resistant ferroportin accumulate iron in the retina. FASEB J 2015; 30:813-23. [PMID: 26506980 DOI: 10.1096/fj.15-276758] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/13/2015] [Indexed: 12/13/2022]
Abstract
Because ferroportin (Fpn) is the only known mammalian cellular iron exporter, understanding its localization and regulation within the retina would shed light on the direction of retinal iron flux. The hormone hepcidin may regulate retinal Fpn, as it triggers Fpn degradation in the gut. Immunofluorescence was used to label Fpn in retinas of mice with 4 different genotypes (wild type; Fpn C326S, a hepcidin-resistant Fpn; hepcidin knockout; and ceruloplasmin/hephaestin double knockout). No significant difference in Fpn levels was observed in these retinas. Fpn localized to the abluminal side of the outer plexiform vascular endothelial cells, Müller glia cells, and the basolateral side of the retinal pigment epithelium. Adeno-associated virus (AAV)-hepcidin was injected into the eyes of hepcidin knockout mice, while AAV-lacZ was injected into the contralateral eyes as a control. AAV-hepcidin injected eyes had increased ferritin immunolabeling in retinal vascular endothelial cells. Fpn C326S mice had systemic iron overload compared to wild type and had the fastest retinal iron accumulation of any hereditary model studied to date. The results suggest that physiologic hepcidin levels are insufficient to alter Fpn levels within the retinal pigment epithelium and Müller cells, but may limit iron transport into the retina from vascular endothelial cells.
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Affiliation(s)
- Milan Theurl
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Delu Song
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Esther Clark
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jacob Sterling
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Steve Grieco
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Sandro Altamura
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Bruno Galy
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Matthias Hentze
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Martina U Muckenthaler
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
| | - Joshua L Dunaief
- *F. M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Ophthalmology and Optometry, Innsbruck Medical University, Innsbruck, Austria; Department of Psychiatry and Behavioral Sciences, and Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA; Department of Pediatric Hematology, Oncology, and Immunology, University of Heidelberg, Heidelberg, Germany; Molecular Medicine Partnership Unit, Heidelberg, Germany; and European Molecular Biology Laboratory, Heidelberg, Germany
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30
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Minhas G, Modgil S, Anand A. Role of iron in ischemia-induced neurodegeneration: mechanisms and insights. Metab Brain Dis 2014; 29:583-91. [PMID: 24615430 DOI: 10.1007/s11011-014-9522-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 02/26/2014] [Indexed: 12/31/2022]
Abstract
Iron is an important micronutrient for neuronal function and survival. It plays an essential role in DNA and protein synthesis, neurotransmission and electron transport chain due to its dual redox states. On the contrary, iron also catalyses the production of free radicals and hence, causes oxidative stress. Therefore, maintenance of iron homeostasis is very crucial and it involves a number of proteins in iron metabolism and transport that maintain the balance. In ischemic conditions large amount of iron is released and this free iron catalyzes production of more free radicals and hence, causing more damage. In this review we have focused on the iron transport and maintenance of iron homeostasis at large and also the effect of imbalance in iron homeostasis on retinal and brain tissue under ischemic conditions. The understanding of the proteins involved in the homeostasis imbalance will help in developing therapeutic strategies for cerebral as well retinal ischemia.
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Affiliation(s)
- Gillipsie Minhas
- Neuroscience Research Laboratory, Department of Neurology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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31
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Zhao L, Li Y, Song D, Song Y, Theurl M, Wang C, Cwanger A, Su G, Dunaief JL. A high serum iron level causes mouse retinal iron accumulation despite an intact blood-retinal barrier. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:2862-7. [PMID: 25174877 DOI: 10.1016/j.ajpath.2014.07.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 06/23/2014] [Accepted: 07/17/2014] [Indexed: 12/31/2022]
Abstract
The retina can be shielded by the blood-retinal barrier. Because photoreceptors are damaged by excess iron, it is important to understand whether the blood-retinal barrier protects against high serum iron levels. Bone morphogenic protein 6 (Bmp6) knockout mice have serum iron overload. Herein, we tested whether the previously documented retinal iron accumulation in Bmp6 knockout mice might result from the high serum iron levels or, alternatively, low levels of retinal hepcidin, an iron regulatory hormone whose transcription can be up-regulated by Bmp6. Furthermore, to determine whether increases in serum iron can elevate retinal iron levels, we i.v. injected iron into wild-type mice. Retinas were analyzed by real-time quantitative PCR and immunofluorescence to assess the levels of iron-regulated genes/proteins and oxidative stress. Retinal hepcidin mRNA levels in Bmp6 knockout retinas were the same as, or greater than, those in age-matched wild-type retinas, indicating that Bmp6 knockout does not cause retinal hepcidin deficiency. Changes in mRNA levels of L ferritin and transferrin receptor indicated increased retinal iron levels in i.v. iron-injected wild-type mice. Oxidative stress markers were elevated in photoreceptors of mice receiving i.v. iron. These findings suggest that elevated serum iron levels can overwhelm local retinal iron regulatory mechanisms.
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Affiliation(s)
- Liangliang Zhao
- Department of Ophthalmology, The Second Hospital of Jilin University, Jilin, China; F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yafeng Li
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Delu Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Milan Theurl
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Chenguang Wang
- Department of Ophthalmology, The Second Hospital of Jilin University, Jilin, China; F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Alyssa Cwanger
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Guanfang Su
- Department of Ophthalmology, The Second Hospital of Jilin University, Jilin, China
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania.
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Tawfik A, Gnana-Prakasam JP, Smith SB, Ganapathy V. Deletion of hemojuvelin, an iron-regulatory protein, in mice results in abnormal angiogenesis and vasculogenesis in retina along with reactive gliosis. Invest Ophthalmol Vis Sci 2014; 55:3616-25. [PMID: 24812553 DOI: 10.1167/iovs.13-13677] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE Loss-of-function mutations in hemojuvelin (HJV) cause juvenile hemochromatosis, an iron-overload disease. Deletion of Hjv in mice results in excessive iron accumulation and morphologic changes in the retina. Here, we studied the retinal vasculature in Hjv(-/-) mice. METHODS Age-matched wild-type and Hjv(-/-) mice were used for fluorescein angiography and preparation of retinal cryosections, flat-mounts, and trypsin-digested blood vessels. Retinal angiogenesis was monitored by immunofluorescent detection of isolectin-B4, endoglin, and VEGF. Retinal vasculogenesis was monitored by immunofluorescent detection of collagen IV. Reactive gliosis was assessed based on the expression of glial fibrillary acidic protein and vimentin and CD11b/c as markers for Müller cells and microglia. RESULTS Between 18 and 24 months of age, retinas of Hjv(-/-) mice displayed marked disruptions in angiogenesis and vasculogenesis. Blood vessels in Hjv(-/-) mice were tortuous and dilated, with a decrease in the tight-junction protein occludin. There was also evidence of neovascularization in Hjv(-/-) mice with blood vessels appearing in the vitreous, which were leaky. There was reactive gliosis in these mice involving both Müller cells and microglia. Such changes were not detected at 2 weeks of age. Even at the age of 4 months, retinas of Hjv(-/-) mice were almost normal with changes just beginning to appear. Thus, the vascular changes in Hjv(-/-) mouse retinas represent an age-dependent phenomenon. CONCLUSIONS Deletion of Hjv in mice leads to abnormal retinal angiogenesis/vasculogenesis, with proliferation of new, leaky blood vessels in the vitreous. These changes are accompanied with reactive gliosis involving Müller cells and microglia.
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Affiliation(s)
- Amany Tawfik
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
| | - Jaya P Gnana-Prakasam
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
| | - Sylvia B Smith
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
| | - Vadivel Ganapathy
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States
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33
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Latour C, Kautz L, Besson-Fournier C, Island ML, Canonne-Hergaux F, Loréal O, Ganz T, Coppin H, Roth MP. Testosterone perturbs systemic iron balance through activation of epidermal growth factor receptor signaling in the liver and repression of hepcidin. Hepatology 2014; 59:683-94. [PMID: 23907767 DOI: 10.1002/hep.26648] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 07/18/2013] [Indexed: 12/14/2022]
Abstract
UNLABELLED Gender-related disparities in the regulation of iron metabolism may contribute to the differences exhibited by men and women in the progression of chronic liver diseases associated with reduced hepcidin expression, e.g., chronic hepatitis C, alcoholic liver disease, or hereditary hemochromatosis. However, their mechanisms remain poorly understood. In this study we took advantage of the major differences in hepcidin expression and tissue iron loading observed between Bmp6-deficient male and female mice to investigate the mechanisms underlying this sexual dimorphism. We found that testosterone robustly represses hepcidin transcription by enhancing Egfr signaling in the liver and that selective epidermal growth factor receptor (Egfr) inhibition by gefitinib (Iressa) in males markedly increases hepcidin expression. In males, where the suppressive effects of testosterone and Bmp6-deficiency on hepcidin expression are combined, hepcidin is more strongly repressed than in females and iron accumulates massively not only in the liver but also in the pancreas, heart, and kidneys. CONCLUSION Testosterone-induced repression of hepcidin expression becomes functionally important during homeostatic stress from disorders that result in iron loading and/or reduced capacity for hepcidin synthesis. These findings suggest that novel therapeutic strategies targeting the testosterone/EGF/EGFR axis may be useful for inducing hepcidin expression in patients with iron overload and/or chronic liver diseases.
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Affiliation(s)
- Chloé Latour
- Inserm, U1043, Toulouse, France; CNRS, U5282, Toulouse, France; Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France
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Ugarte M, Osborne NN, Brown LA, Bishop PN. Iron, zinc, and copper in retinal physiology and disease. Surv Ophthalmol 2013; 58:585-609. [DOI: 10.1016/j.survophthal.2012.12.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 12/09/2012] [Accepted: 12/11/2012] [Indexed: 12/26/2022]
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35
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Rodríguez Diez G, Sánchez Campos S, Giusto N, Salvador G. Specific roles for Group V secretory PLA2 in retinal iron-induced oxidative stress. Implications for age-related macular degeneration. Exp Eye Res 2013; 113:172-81. [DOI: 10.1016/j.exer.2013.05.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 05/14/2013] [Accepted: 05/21/2013] [Indexed: 11/15/2022]
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36
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Song D, Dunaief JL. Retinal iron homeostasis in health and disease. Front Aging Neurosci 2013; 5:24. [PMID: 23825457 PMCID: PMC3695389 DOI: 10.3389/fnagi.2013.00024] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/11/2013] [Indexed: 12/21/2022] Open
Abstract
Iron is essential for life, but excess iron can be toxic. As a potent free radical creator, iron generates hydroxyl radicals leading to significant oxidative stress. Since iron is not excreted from the body, it accumulates with age in tissues, including the retina, predisposing to age-related oxidative insult. Both hereditary and acquired retinal diseases are associated with increased iron levels. For example, retinal degenerations have been found in hereditary iron overload disorders, like aceruloplasminemia, Friedreich's ataxia, and pantothenate kinase-associated neurodegeneration. Similarly, mice with targeted mutation of the iron exporter ceruloplasmin and its homolog hephaestin showed age-related retinal iron accumulation and retinal degeneration with features resembling human age-related macular degeneration (AMD). Post mortem AMD eyes have increased levels of iron in retina compared to age-matched healthy donors. Iron accumulation in AMD is likely to result, in part, from inflammation, hypoxia, and oxidative stress, all of which can cause iron dysregulation. Fortunately, it has been demonstrated by in vitro and in vivo studies that iron in the retinal pigment epithelium (RPE) and retina is chelatable. Iron chelation protects photoreceptors and retinal pigment epithelial cells (RPE) in a variety of mouse models. This has therapeutic potential for diminishing iron-induced oxidative damage to prevent or treat AMD.
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Affiliation(s)
- Delu Song
- The F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine at University of Pennsylvania Philadelphia, PA, USA
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37
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Gnana-Prakasam JP, Veeranan-Karmegam R, Coothankandaswamy V, Reddy SK, Martin PM, Thangaraju M, Smith SB, Ganapathy V. Loss of Hfe leads to progression of tumor phenotype in primary retinal pigment epithelial cells. Invest Ophthalmol Vis Sci 2013; 54:63-71. [PMID: 23169885 DOI: 10.1167/iovs.12-10312] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE Hemochromatosis is a disorder of iron overload arising mostly from mutations in HFE. HFE is expressed in retinal pigment epithelium (RPE), and Hfe(-/-) mice develop age-related iron accumulation and retinal degeneration associated with RPE hyperproliferation. Here, the mechanism underlying the hyperproliferative phenotype in RPE was investigated. METHODS Cellular senescence was monitored by β-galactosidase activity. Gene expression was monitored by real-time PCR. Survivin was analyzed by Western blot and immunofluorescence. Migration and invasion were monitored using appropriate kits. Glucose transporters (GLUTs) were monitored by 3-O-methyl-D-glucose uptake. Histone deacetylases (HDACs) were studied by monitoring catalytic activity and acetylation status of histones H3/H4. RESULTS Hfe(-/-) RPE cells exhibited slower senescence rate and higher survivin expression than wild type cells. Hfe(-/-) cells migrated faster and showed greater glucose uptake and increased expression of GLUTs. The expression of HDACs and DNA methyltransferase (DNMTs) also was increased. Similarly, RPE cells from hemojuvelin (Hjv)-knockout mice, another model of hemochromatosis, also had increased expression of GLUTs, HDACs, and DNMTs. The expression of Slc5a8 was decreased in Hfe(-/-) RPE cells, but treatment with a DNA methylation inhibitor restored the transporter expression, indicating involvement of DNA methylation in the silencing of Slc5a8 in Hfe(-/-) cells. CONCLUSIONS RPE cells from iron-overloaded mice exhibit several features of tumor cells: decreased senescence, enhanced migration, increased glucose uptake, and elevated levels of HDACs and DNMTs. These features are seen in Hfe(-/-) RPE cells as well as in Hjv(-/-) RPE cells, providing a molecular basis for the hyperproliferative phenotype of Hfe(-/-) and Hjv(-/-) RPE cells.
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Affiliation(s)
- Jaya P Gnana-Prakasam
- Department of Biochemistry and Molecular Biology, Georgia Health Sciences University, Augusta, Georgia 30912, USA.
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Abstract
Iron is a redox active metal which is abundant in the Earth's crust. It has played a key role in the evolution of living systems and as such is an essential element in a wide range of biological phenomena, being critical for the function of an enormous array of enzymes, energy transduction mechanisms, and oxygen carriers. The redox nature of iron renders the metal toxic in excess and consequently all biological organisms carefully control iron levels. In this overview the mechanisms adopted by man to control body iron levels are described.Low body iron levels are related to anemia which can be treated by various forms of iron fortification and supplementation. Elevated iron levels can occur systemically or locally, each giving rise to specific symptoms. Systemic iron overload results from either the hyperabsorption of iron or regular blood transfusion and can be treated by the use of a selection of iron chelating molecules. The symptoms of many forms of neurodegeneration are associated with elevated levels of iron in certain regions of the brain and iron chelation therapy is beginning to find an application in the treatment of such diseases. Iron chelators have also been widely investigated for the treatment of cancer, tuberculosis, and malaria. In these latter studies, selective removal of iron from key enzymes or iron binding proteins is sought. Sufficient selectivity between the invading organism and the host has yet to be established for such chelators to find application in the clinic.Iron chelation for systemic iron overload and iron supplementation therapy for the treatment of various forms of anemia are now established procedures in clinical medicine. Chelation therapy may find an important role in the treatment of various neurodegenerative diseases in the near future.
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Hadziahmetovic M, Kumar U, Song Y, Grieco S, Song D, Li Y, Tobias JW, Dunaief JL. Microarray analysis of murine retinal light damage reveals changes in iron regulatory, complement, and antioxidant genes in the neurosensory retina and isolated RPE. Invest Ophthalmol Vis Sci 2012; 53:5231-41. [PMID: 22736611 DOI: 10.1167/iovs.12-10204] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
PURPOSE The purpose of this study was to investigate light damage-induced transcript changes within neurosensory retina (NSR) and isolated retinal pigment epithelium (RPE). Similar studies have been conducted previously, but were usually limited to the NSR and only a portion of the transcriptome. Herein most of the transcriptome, not just in the NSR but also in isolated RPE, was queried. METHODS Mice were exposed to 10,000 lux cool white fluorescent light for 18 hours and euthanized 4 hours after photic injury. NSR and isolated RPE were collected, and RNA was isolated. DNA microarray hybridization was conducted as described in the Affymetrix GeneChip Expression Analysis Technical Manual. Microarray analysis was performed using probe intensity data derived from the Mouse Gene 1.0 ST Array. For the genes of interest, confirmation of gene expression was done using quantitative real-time PCR. Immunofluorescence assessed protein levels and localization. RESULTS Numerous iron regulatory genes were significantly changed in the light-exposed NSR and RPE. Several of these gene expression changes favored an iron-overloaded state. For example, the transferrin receptor was upregulated in both light-exposed NSR and RPE. Consistent with this, there was stronger transferrin receptor immunoreactivity in the light-exposed retinas. Significant changes in gene expression following light damage were also observed in oxidative stress and complement system genes. CONCLUSIONS The concept of a photooxidative stress-induced vicious cycle of increased iron uptake leading to further oxidative stress was introduced.
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Affiliation(s)
- Majda Hadziahmetovic
- FM Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Wolkow N, Song D, Song Y, Chu S, Hadziahmetovic M, Lee JC, Iacovelli J, Grieco S, Dunaief JL. Ferroxidase hephaestin's cell-autonomous role in the retinal pigment epithelium. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:1614-24. [PMID: 22342521 DOI: 10.1016/j.ajpath.2011.12.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 12/11/2011] [Accepted: 12/20/2011] [Indexed: 01/04/2023]
Abstract
Hephaestin (Heph) is a ferroxidase protein that converts ferrous to ferric iron to facilitate cellular iron export by ferroportin. Many tissues express either Heph or its homologue, ceruloplasmin (Cp), but the retina expresses both. In mice, a combined systemic mutation of Heph and systemic knockout of Cp (Cp(-/-), Heph(sla/sla)) causes retinal iron accumulation and retinal degeneration, with features of human age-related macular degeneration; however, the role of Heph and Cp in the individual retinal cells is unclear. Herein, we used conditional knockout mice to study Heph's role in retinal pigment epithelial (RPE) and photoreceptor cells. Loss of both Heph and Cp from RPE cells alone results in RPE cell iron accumulation and degeneration. We found, however, that RPE iron accumulation in these conditional knockout mice is not as great as in systemic knockout mice. Photoreceptor-specific Heph knockout indicates that the additional iron in the RPE cells does not result from loss of ferroxidases in the photoreceptors, and Cp and Heph play minor roles in photoreceptors. Instead, loss of ferroxidases in other retinal cells causes retinal iron accumulation and transfer of iron to the RPE cells. Cp and Heph are necessary for iron export from the retina but are not essential for iron import into the retina. Thus, our studies, revise how we think about iron import and export from the retina.
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Affiliation(s)
- Natalie Wolkow
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Abstract
Haemochromatosis is a genetic disorder of iron overload resulting from loss-of-function mutations in genes coding for the iron-regulatory proteins HFE (human leucocyte antigen-like protein involved in iron homoeostasis), transferrin receptor 2, ferroportin, hepcidin and HJV (haemojuvelin). Recent studies have established the expression of all of the five genes in the retina, indicating their importance in retinal iron homoeostasis. Previously, we demonstrated that HJV is expressed in RPE (retinal pigment epithelium), the outer and inner nuclear layers and the ganglion cell layer. In the present paper, we report on the consequences of Hjv deletion on the retina in mice. Hjv-/- mice at ≥18 months of age had increased iron accumulation in the retina with marked morphological damage compared with age-matched controls; these changes were not found in younger mice. The retinal phenotype in Hjv-/- mice included hyperplasia of RPE. We isolated RPE cells from wild-type and Hjv-/- mice and examined their growth patterns. Hjv-/- RPE cells were less senescent and exhibited a hyperproliferative phenotype. Hjv-/- RPE cells also showed up-regulation of Slc7a11 (solute carrier family 7 member 11 gene), which encodes the 'transporter proper' subunit xCT in the heterodimeric amino acid transporter xCT/4F2hc (cystine/glutamate exchanger). BMP6 (bone morphogenetic protein 6) could not induce hepcidin expression in Hjv-/- RPE cells, confirming that retinal cells require HJV for induction of hepcidin via BMP6 signalling. HJV is a glycosylphosphatidylinositol-anchored protein, and the membrane-associated HJV is necessary for BMP6-mediated activation of hepcidin promoter in RPE cells. Taken together, these results confirm the biological importance of HJV in the regulation of iron homoeostasis in the retina and in RPE.
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