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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] [What about the content of this article? (0)] [Affiliation(s)] [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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