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Xiao R, Huang X, Gao S, Duan J, Zhang Y, Zhang M. Microglia in retinal diseases: From pathogenesis towards therapeutic strategies. Biochem Pharmacol 2024; 230:116550. [PMID: 39307318 DOI: 10.1016/j.bcp.2024.116550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2024] [Revised: 08/21/2024] [Accepted: 09/19/2024] [Indexed: 10/01/2024]
Abstract
Microglia, a widely dispersed cohort of immune cells in the retina, are intricately involved in a diverse range of pivotal biological processes, including inflammation, vascular development, complement activation, antigen presentation, and phagocytosis. Within the retinal milieu, microglia are crucial for the clearance of dead cells and cellular debris, release of anti-inflammatory agents, and orchestration of vascular network remodeling to maintain homeostasis. In addition, microglia are key mediators of neuroinflammation. Triggered by oxidative stress, elevated intraocular pressure, genetic anomalies, and immune dysregulation, microglia release numerous inflammatory cytokines, contributing to the pathogenesis of various retinal disorders. Recent studies on the ontogeny and broad functions of microglia in the retina have elucidated their characteristics during retinal development, homeostasis, and disease. Furthermore, therapeutic strategies that target microglia and their effector cytokines have been developed and shown positive results for some retinal diseases. Therefore, we systematically review the microglial ontogeny in the retina, elucidate their dual roles in retinal homeostasis and disease pathogenesis, and demonstrate microglia-based targeted therapeutic strategies for retinal diseases.
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Affiliation(s)
- Ruihan Xiao
- The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; The Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Xi Huang
- The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; The Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Sheng Gao
- The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; The Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Jianan Duan
- The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; The Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yun Zhang
- The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; The Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Meixia Zhang
- The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China; The Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, 610041, China.
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Motipally SI, Kolson DR, Guan T, Kolandaivelu S. Aberrant lipid accumulation and retinal pigment epithelium dysfunction in PRCD-deficient mice. Exp Eye Res 2024; 246:110016. [PMID: 39098587 PMCID: PMC11388538 DOI: 10.1016/j.exer.2024.110016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 07/24/2024] [Accepted: 07/30/2024] [Indexed: 08/06/2024]
Abstract
Progressive Rod-Cone Degeneration (PRCD) is an integral membrane protein found in photoreceptor outer segment (OS) disc membranes and its function remains unknown. Mutations in Prcd are implicated in Retinitis pigmentosa (RP) in humans and multiple dog breeds. PRCD-deficient models exhibit decreased levels of cholesterol in the plasma. However, potential changes in the retinal cholesterol remain unexplored. In addition, impaired phagocytosis observed in these animal models points to potential deficits in the retinal pigment epithelium (RPE). Here, using a Prcd-/- murine model we investigated the alterations in the retinal cholesterol levels and impairments in the structural and functional integrity of the RPE. Lipidomic and immunohistochemical analyses show a 5-fold increase in the levels of cholesteryl esters (C.Es) and lipid deposits in the PRCD-deficient retina, respectively, indicating alterations in total retinal cholesterol. Furthermore, the RPE of Prcd-/- mice exhibit a 1.7-fold increase in the expression of lipid transporter gene ATP-binding cassette transporter A1 (Abca1). Longitudinal fundus and spectral domain optical coherence tomography (SD-OCT) examinations showed focal lesions and RPE hyperreflectivity. Strikingly, the RPE of Prcd-/- mice exhibited age-related pathological features such as lipofuscin accumulation, Bruch's membrane (BrM) deposits and drusenoid focal deposits, mirroring an Age-related Macular Degeneration (AMD)-like phenotype. We propose that the extensive lipofuscin accumulation likely impairs lysosomal function, leading to the defective phagocytosis observed in Prcd-/- mice. Our findings support the dysregulation of retinal cholesterol homeostasis in the absence of PRCD. Further, we demonstrate that progressive photoreceptor degeneration in Prcd-/- mice is accompanied by progressive structural and functional deficits in the RPE, which likely exacerbates vision loss over time.
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Affiliation(s)
- Sree I Motipally
- Department of Neuroscience, Rockefeller Neuroscience Institute, 33 Medical Centre Drive, West Virginia University, Morgantown, WV, 26506, USA; Department of Ophthalmology and Visual Sciences, One Medical Center Drive, ERMA 2nd Floor, West Virginia University, Morgantown, WV, 26505-9193, USA
| | - Douglas R Kolson
- Department of Ophthalmology and Visual Sciences, One Medical Center Drive, ERMA 2nd Floor, West Virginia University, Morgantown, WV, 26505-9193, USA
| | - Tongju Guan
- Department of Ophthalmology and Visual Sciences, One Medical Center Drive, ERMA 2nd Floor, West Virginia University, Morgantown, WV, 26505-9193, USA; Department of Biochemistry and Molecular Medicine, 64 Medical Center Drive, West Virginia University, Morgantown, WV, 26505-9193, USA
| | - Saravanan Kolandaivelu
- Department of Ophthalmology and Visual Sciences, One Medical Center Drive, ERMA 2nd Floor, West Virginia University, Morgantown, WV, 26505-9193, USA; Department of Biochemistry and Molecular Medicine, 64 Medical Center Drive, West Virginia University, Morgantown, WV, 26505-9193, USA.
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Yang M, Yao J, Jia L, Kocab AJ, Zacks DN. Preservation of retinal structure and function in two mouse models of inherited retinal degeneration by ONL1204, an inhibitor of the Fas receptor. Cell Death Dis 2024; 15:576. [PMID: 39117629 PMCID: PMC11310419 DOI: 10.1038/s41419-024-06970-6] [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: 04/15/2024] [Revised: 07/30/2024] [Accepted: 08/01/2024] [Indexed: 08/10/2024]
Abstract
Due to the large number of genes and mutations that result in inherited retinal degenerations (IRD), there has been a paucity of therapeutic options for these patients. There is a large unmet need for therapeutic approaches targeting shared pathophysiologic pathways in a mutation-independent manner. The Fas receptor is a major activator and regulator of retinal cell death and inflammation in a variety of ocular diseases. We previously reported the activation of Fas-mediated photoreceptor (PR) cell death in two different IRD mouse models, rd10 and P23H, and demonstrated the protective effect of genetic Fas inhibition. The purpose of this study was to examine the effects of pharmacologic inhibition of Fas in these two models by intravitreal injection with a small peptide inhibitor of the Fas receptor, ONL1204. A single intravitreal injection of ONL1204 was given to one eye of rd10 mice at P14. Two intravitreal injections of ONL1204 were given to the P23H mice, once at P14 and again at 2-months of age. The fellow eyes were injected with vehicle alone. Fas activation, rate of PR cell death, retinal function, and the activation of immune cells in the retina were evaluated. In both rd10 and P23H mice, ONL1204 treatment resulted in decreased number of TUNEL (+) PRs, decreased caspase 8 activity, enhanced photoreceptor cell counts, and improved visual function compared with vehicle treated fellow eyes. Treatment with ONL1204 also reduced immune cell activation in the retinas of both rd10 and P23H mice. The protective effect of pharmacologic inhibition of Fas by ONL1204 in two distinct mouse models of retinal degeneration suggests that targeting this common pathophysiologic mechanism of cell death and inflammation represents a potential therapeutic approach to preserve the retina in patients with IRD, regardless of the genetic underpinning.
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Affiliation(s)
- Mengling Yang
- Department of Ophthalmology and Visual Sciences, University of Michigan, Kellogg Eye Center, Ann Arbor, MI, USA
- Eye Center of Xiangya Hospital, Xiangya School of medicine, Central South University, Changsha, Hunan, China
| | - Jingyu Yao
- Department of Ophthalmology and Visual Sciences, University of Michigan, Kellogg Eye Center, Ann Arbor, MI, USA
| | - Lin Jia
- Department of Ophthalmology and Visual Sciences, University of Michigan, Kellogg Eye Center, Ann Arbor, MI, USA
| | | | - David N Zacks
- Department of Ophthalmology and Visual Sciences, University of Michigan, Kellogg Eye Center, Ann Arbor, MI, USA.
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Ghosh S, Finnemann SC, Vollrath D, Rothlin CV. In the Eyes of the Beholder-New Mertk Knockout Mouse and Re-Evaluation of Phagocytosis versus Anti-Inflammatory Functions of MERTK. Int J Mol Sci 2024; 25:5299. [PMID: 38791338 PMCID: PMC11121519 DOI: 10.3390/ijms25105299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 04/26/2024] [Accepted: 04/26/2024] [Indexed: 05/26/2024] Open
Abstract
Greg Lemke's laboratory was one of the pioneers of research into the TAM family of receptor tyrosine kinases (RTKs). Not only was Tyro3 cloned in his laboratory, but his group also extensively studied mice knocked out for individual or various combinations of the TAM RTKs Tyro3, Axl, and Mertk. Here we primarily focus on one of the paralogs-MERTK. We provide a historical perspective on rodent models of loss of Mertk function and their association with retinal degeneration and blindness. We describe later studies employing mouse genetics and the generation of newer knockout models that point out incongruencies with the inference that loss of MERTK-dependent phagocytosis is sufficient for severe, early-onset photoreceptor degeneration in mice. This discussion is meant to raise awareness with regards to the limitations of the original Mertk knockout mouse model generated using 129 derived embryonic stem cells and carrying 129 derived alleles and the role of these alleles in modifying Mertk knockout phenotypes or even displaying Mertk-independent phenotypes. We also suggest molecular approaches that can further Greg Lemke's scintillating legacy of dissecting the molecular functions of MERTK-a protein that has been described to function in phagocytosis as well as in the negative regulation of inflammation.
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Affiliation(s)
- Sourav Ghosh
- Department of Neurology, School of Medicine, Yale University, New Haven, CT 06520, USA
- Department of Pharmacology, School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Silvia C. Finnemann
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY 10458, USA;
| | - Douglas Vollrath
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA;
| | - Carla V. Rothlin
- Department of Pharmacology, School of Medicine, Yale University, New Haven, CT 06520, USA
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT 06520, USA
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5
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Motipally SI, Kolson DR, Guan T, Kolandaivelu S. Aberrant lipid accumulation and retinal pigmental epithelium dysfunction in PRCD-deficient mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.08.584131. [PMID: 38558979 PMCID: PMC10979840 DOI: 10.1101/2024.03.08.584131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Progressive Rod-Cone Degeneration (PRCD) is an integral membrane protein found in photoreceptor outer segment (OS) disc membranes and its function remains unknown. Mutations in Prcd are implicated in Retinitis pigmentosa (RP) in humans and multiple dog breeds. PRCD-deficient models exhibit decreased levels of cholesterol in the plasma. However, potential changes in the retinal cholesterol remain unexplored. In addition, impaired phagocytosis observed in these animal models points to potential deficits in the retinal pigment epithelium (RPE). Here, using a Prcd -/- murine model we investigated the alterations in the retinal cholesterol levels and impairments in the structural and functional integrity of the RPE. Lipidomic and immunohistochemical analyses show a 5-fold increase in the levels of cholesteryl esters (C.Es) and accumulation of neutral lipids in the PRCD-deficient retina, respectively, indicating alterations in total retinal cholesterol. Longitudinal fundus and spectral domain optical coherence tomography (SD-OCT) examinations showed focal lesions and RPE hyperreflectivity. Strikingly, the RPE of Prcd -/- mice exhibited age-related pathological features such as neutral lipid deposits, lipofuscin accumulation, Bruch's membrane (BrM) thickening and drusenoid focal deposits, mirroring an Age-related Macular Degeneration (AMD)-like phenotype. We propose that the extensive lipofuscin accumulation likely impairs lysosomal function, leading to the defective phagocytosis observed in Prcd -/- mice. Our findings support the dysregulation of retinal cholesterol homeostasis in the absence of PRCD. Further, we demonstrate that progressive photoreceptor degeneration in Prcd -/- mice is accompanied by progressive structural and functional deficits in the RPE, which likely exacerbates vision loss over time.
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Enderlin J, Rieu Q, Réty S, Vanoni EM, Roux S, Dégardin J, César Q, Augustin S, Nous C, Cai B, Fontaine V, Sennlaub F, Nandrot EF. Retinal atrophy, inflammation, phagocytic and metabolic disruptions develop in the MerTK-cleavage-resistant mouse model. Front Neurosci 2024; 18:1256522. [PMID: 38680449 PMCID: PMC11047123 DOI: 10.3389/fnins.2024.1256522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 03/11/2024] [Indexed: 05/01/2024] Open
Abstract
In the eye, cells from the retinal pigment epithelium (RPE) facing the neurosensory retina exert several functions that are all crucial for long-term survival of photoreceptors (PRs) and vision. Among those, RPE cells phagocytose under a circadian rhythm photoreceptor outer segment (POS) tips that are constantly subjected to light rays and oxidative attacks. The MerTK tyrosine kinase receptor is a key element of this phagocytic machinery required for POS internalization. Recently, we showed that MerTK is subjected to the cleavage of its extracellular domain to finely control its function. In addition, monocytes in retinal blood vessels can migrate inside the inner retina and differentiate into macrophages expressing MerTK, but their role in this context has not been studied yet. We thus investigated the ocular phenotype of MerTK cleavage-resistant (MerTKCR) mice to understand the relevance of this characteristic on retinal homeostasis at the RPE and macrophage levels. MerTKCR retinae appear to develop and function normally, as observed in retinal sections, by electroretinogram recordings and optokinetic behavioral tests. Monitoring of MerTKCR and control mice between the ages of 3 and 18 months showed the development of large degenerative areas in the central retina as early as 4 months when followed monthly by optical coherence tomography (OCT) plus fundus photography (FP)/autofluorescence (AF) detection but not by OCT alone. The degenerative areas were associated with AF, which seems to be due to infiltrated macrophages, as observed by OCT and histology. MerTKCR RPE primary cultures phagocytosed less POS in vitro, while in vivo, the circadian rhythm of POS phagocytosis was deregulated. Mitochondrial function and energy production were reduced in freshly dissected RPE/choroid tissues at all ages, thus showing a metabolic impairment not present in macrophages. RPE anomalies were detected by electron microscopy, including phagosomes retained in the apical area and vacuoles. Altogether, this new mouse model displays a novel phenotype that could prove useful to understanding the interplay between RPE and PRs in inflammatory retinal degenerations and highlights new roles for MerTK in the regulation of the energetic metabolism and the maintenance of the immune privilege in the retina.
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Affiliation(s)
- Julie Enderlin
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Quentin Rieu
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Salomé Réty
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Elora M. Vanoni
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Solène Roux
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Julie Dégardin
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Quénol César
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Sébastien Augustin
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Caroline Nous
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Bishuang Cai
- Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Valérie Fontaine
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Florian Sennlaub
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
| | - Emeline F. Nandrot
- INSERM, CNRS, Institut de la Vision, Therapeutics Department, Sorbonne Université, Paris, France
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Yang P, Mustafi D, Pepple KL. Immunology of Retinitis Pigmentosa and Gene Therapy-Associated Uveitis. Cold Spring Harb Perspect Med 2024; 14:a041305. [PMID: 37037600 PMCID: PMC10562523 DOI: 10.1101/cshperspect.a041305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
The underlying immune state of inherited retinal degenerations (IRDs) and retinitis pigmentosa (RP) has been an emerging area of interest, wherein the consequences have never been greater given the widespread recognition of gene therapy-associated uveitis (GTU) in gene therapy clinical trials. Whereas some evidence suggests that the adaptive immune system may play a role, the majority of studies indicate that the innate immune system is likely the primary driver of neuroinflammation in RP. During retinal degeneration, discrete mechanisms activate resident microglia and promote infiltrating macrophages that can either be protective or detrimental to photoreceptor cell death. This persistent stimulation of innate immunity, overlaid by the introduction of viral antigens as part of gene therapy, has the potential to trigger a complex microglia/macrophage-driven proinflammatory state. A better understanding of the immune pathophysiology in IRD and GTU will be necessary to improve the success of developing novel treatments for IRDs.
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Affiliation(s)
- Paul Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregan 97239, USA
| | - Debarshi Mustafi
- Department of Ophthalmology, Roger and Karalis Johnson Retina Center, University of Washington, Seattle, Washington 98109, USA
- Brotman Baty Institute for Precision Medicine, Seattle, Washington 98109, USA
- Department of Ophthalmology, Seattle Children's Hospital, Seattle, Washington 98109, USA
| | - Kathryn L Pepple
- Department of Ophthalmology, Roger and Karalis Johnson Retina Center, University of Washington, Seattle, Washington 98109, USA
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Pérez-Fernández V, Thananjeyan AL, Ullah F, Münch G, Cameron M, Gyengesi E. The effects of a highly bioavailable curcumin Phytosome TM preparation on the retinal architecture and glial reactivity in the GFAP-IL6 mice. FRONTIERS IN OPHTHALMOLOGY 2023; 3:1205542. [PMID: 38983084 PMCID: PMC11182199 DOI: 10.3389/fopht.2023.1205542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 09/08/2023] [Indexed: 07/11/2024]
Abstract
Uncontrolled, chronic inflammation in the retina can disturb retinal structure and function leading to impaired visual function. For the first time, in a mouse model of chronic neuroinflammation (GFAP-IL6), we investigated the impact of chronic glial activation on the retinal microglia population and structure. In addition, we tested a curcumin PhytosomeTM preparation with enhanced bioavailability to investigate the effects of a cytokine-suppressing anti-inflammatory drug on retinal architecture. Curcumin PhytosomeTM was fed to 3-month old GFAP-IL6 mice for 4 weeks and compared to their untreated GFAP-IL6 counterparts as well as wild type mice on control diet. Microglial numbers and morphology together with neuronal numbers were characterized using immunohistochemistry and cell reconstruction in the retina, using retinal wholemount and slices. GFAP-IL6 mice showed a significant increase in Iba1-labelled mononuclear phagocytes, including microglia, and displayed altered glial morphology. This resulted in a reduction in cone density and a thinning of the retinal layers compared to wild type mice. Curcumin PhytosomeTM treatment contributed to decreased microglial density, significantly decreasing both soma and cell size compared to control diet, as well as preventing the thinning of the retinal layers. This study is the first to characterize the impact of chronic retinal inflammation in the GFAP-IL6 mouse and the therapeutic benefit of enhanced bioavailable curcumin PhytosomeTM to significantly reduce microglia density and prevent neuronal loss. These data suggest that curcumin could be used as a complementary therapy alongside traditional treatments to reduce associated retinal inflammation in a variety of retinal diseases.
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Affiliation(s)
- Víctor Pérez-Fernández
- Department of Anatomy and Cell Biology, Western Sydney University, Campbelltown, NSW, Australia
| | | | - Faheem Ullah
- Department of Pharmacology, Western Sydney University, Campbelltown, NSW, Australia
- Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States
| | - Gerald Münch
- Department of Pharmacology, Western Sydney University, Campbelltown, NSW, Australia
| | - Morven Cameron
- Department of Anatomy and Cell Biology, Western Sydney University, Campbelltown, NSW, Australia
| | - Erika Gyengesi
- Department of Pharmacology, Western Sydney University, Campbelltown, NSW, Australia
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Lieffrig SA, Gyimesi G, Mao Y, Finnemann SC. Clearance phagocytosis by the retinal pigment epithelial during photoreceptor outer segment renewal: Molecular mechanisms and relation to retinal inflammation. Immunol Rev 2023; 319:81-99. [PMID: 37555340 PMCID: PMC10615845 DOI: 10.1111/imr.13264] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/18/2023] [Indexed: 08/10/2023]
Abstract
Mammalian photoreceptor outer segment renewal is a highly coordinated process that hinges on timed cell signaling between photoreceptor neurons and the adjacent retinal pigment epithelial (RPE). It is a strictly rhythmic, synchronized process that underlies in part circadian regulation. We highlight findings from recently developed methods that quantify distinct phases of outer segment renewal in retinal tissue. At light onset, outer segments expose the conserved "eat-me" signal phosphatidylserine exclusively at their distal, most aged tip. A coordinated two-receptor efferocytosis process follows, in which ligands bridge outer segment phosphatidylserine with the RPE receptors αvβ5 integrin, inducing cytosolic signaling toward Rac1 and focal adhesion kinase/MERTK, and with MERTK directly, additionally inhibiting RhoA/ROCK and thus enabling F-actin dynamics favoring outer segment fragment engulfment. Photoreceptors and RPE persist for life with each RPE cell in the eye servicing dozens of overlying photoreceptors. Thus, RPE cells phagocytose more often and process more material than any other cell type. Mutant mice with impaired outer segment renewal largely retain functional photoreceptors and retinal integrity. However, when anti-inflammatory signaling in the RPE via MERTK or the related TYRO3 is lacking, catastrophic inflammation leads to immune cell infiltration that swiftly destroys the retina causing blindness.
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Affiliation(s)
- Stephanie A. Lieffrig
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY
| | - Gavin Gyimesi
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY
| | | | - Silvia C. Finnemann
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY
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Liang J, Fang D, Yao F, Chen L, Zou Z, Tang X, Feng L, Zhuang Y, Xie T, Wei P, Li P, Zheng H, Zhang S. Analysis of shared ceRNA networks and related-hub genes in rats with primary and secondary photoreceptor degeneration. Front Neurosci 2023; 17:1259622. [PMID: 37811327 PMCID: PMC10552924 DOI: 10.3389/fnins.2023.1259622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 09/06/2023] [Indexed: 10/10/2023] Open
Abstract
Introduction Photoreceptor degenerative diseases are characterized by the progressive death of photoreceptor cells, resulting in irreversible visual impairment. However, the role of competing endogenous RNA (ceRNA) in photoreceptor degeneration is unclear. We aimed to explore the shared ceRNA regulation network and potential molecular mechanisms between primary and secondary photoreceptor degenerations. Methods We established animal models for both types of photoreceptor degenerations and conducted retina RNA sequencing to identify shared differentially expressed long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and messenger RNAs (mRNAs). Using ceRNA regulatory principles, we constructed a shared ceRNA network and performed function enrichment and protein-protein interaction (PPI) analyses to identify hub genes and key pathways. Immune cell infiltration and drug-gene interaction analyses were conducted, and hub gene expression was validated by quantitative real-time polymerase chain reaction (qRT-PCR). Results We identified 37 shared differentially expressed lncRNAs, 34 miRNAs, and 247 mRNAs and constructed a ceRNA network consisting of 3 lncRNAs, 5 miRNAs, and 109 mRNAs. Furthermore, we examined 109 common differentially expressed genes (DEGs) through functional annotation, PPI analysis, and regulatory network analysis. We discovered that these diseases shared the complement and coagulation cascades pathway. Eight hub genes were identified and enriched in the immune system process. Immune infiltration analysis revealed increased T cells and decreased B cells in both photoreceptor degenerations. The expression of hub genes was closely associated with the quantities of immune cell types. Additionally, we identified 7 immune therapeutical drugs that target the hub genes. Discussion Our findings provide new insights and directions for understanding the common mechanisms underlying the development of photoreceptor degeneration. The hub genes and related ceRNA networks we identified may offer new perspectives for elucidating the mechanisms and hold promise for the development of innovative treatment strategies.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Shaochong Zhang
- Shenzhen Eye Hospital, Shenzhen Eye Institute, Jinan University, Shenzhen, Guangdong, China
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Miao J, Ma H, Yang Y, Liao Y, Lin C, Zheng J, Yu M, Lan J. Microglia in Alzheimer's disease: pathogenesis, mechanisms, and therapeutic potentials. Front Aging Neurosci 2023; 15:1201982. [PMID: 37396657 PMCID: PMC10309009 DOI: 10.3389/fnagi.2023.1201982] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/30/2023] [Indexed: 07/04/2023] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by protein aggregation in the brain. Recent studies have revealed the critical role of microglia in AD pathogenesis. This review provides a comprehensive summary of the current understanding of microglial involvement in AD, focusing on genetic determinants, phenotypic state, phagocytic capacity, neuroinflammatory response, and impact on synaptic plasticity and neuronal regulation. Furthermore, recent developments in drug discovery targeting microglia in AD are reviewed, highlighting potential avenues for therapeutic intervention. This review emphasizes the essential role of microglia in AD and provides insights into potential treatments.
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Affiliation(s)
- Jifei Miao
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Shenzhen, China
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Haixia Ma
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Yang Yang
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Yuanpin Liao
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Cui Lin
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Juanxia Zheng
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Muli Yu
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Jiao Lan
- Shenzhen Bao’an Traditional Chinese Medicine Hospital, Shenzhen, China
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Mercau ME, Akalu YT, Mazzoni F, Gyimesi G, Alberto EJ, Kong Y, Hafler BP, Finnemann SC, Rothlin CV, Ghosh S. Inflammation of the retinal pigment epithelium drives early-onset photoreceptor degeneration in Mertk-associated retinitis pigmentosa. SCIENCE ADVANCES 2023; 9:eade9459. [PMID: 36662852 PMCID: PMC9858494 DOI: 10.1126/sciadv.ade9459] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/19/2022] [Indexed: 05/17/2023]
Abstract
Severe, early-onset photoreceptor (PR) degeneration associated with MERTK mutations is thought to result from failed phagocytosis by retinal pigment epithelium (RPE). Notwithstanding, the severity and onset of PR degeneration in mouse models of Mertk ablation are determined by the hypomorphic expression or the loss of the Mertk paralog Tyro3. Here, we find that loss of Mertk and reduced expression/loss of Tyro3 led to RPE inflammation even before eye-opening. Incipient RPE inflammation cascaded to involve microglia activation and PR degeneration with monocyte infiltration. Inhibition of RPE inflammation with the JAK1/2 inhibitor ruxolitinib mitigated PR degeneration in Mertk-/- mice. Neither inflammation nor severe, early-onset PR degeneration was observed in mice with defective phagocytosis alone. Thus, inflammation drives severe, early-onset PR degeneration-associated with Mertk loss of function.
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Affiliation(s)
- Maria E. Mercau
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Yemsratch T. Akalu
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Francesca Mazzoni
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY 10458, USA
| | - Gavin Gyimesi
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY 10458, USA
| | - Emily J. Alberto
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Yong Kong
- Department of Molecular Biophysics and Biochemistry, W. M. Keck Foundation Biotechnology Resource Laboratory, School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Brian P. Hafler
- Department of Ophthalmology, School of Medicine, Yale University, New Haven, CT 06520, USA
- Department of Pathology, School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Silvia C. Finnemann
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY 10458, USA
| | - Carla V. Rothlin
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT 06520, USA
- Department of Pharmacology, School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Sourav Ghosh
- Department of Pharmacology, School of Medicine, Yale University, New Haven, CT 06520, USA
- Department of Neurology, School of Medicine, Yale University, New Haven, CT 06520, USA
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13
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Xu RC, Miao WT, Xu JY, Xu WX, Liu MR, Ding ST, Jian YX, Lei YH, Yan N, Liu HD. Neuroprotective Effects of Sodium Butyrate and Monomethyl Fumarate Treatment through GPR109A Modulation and Intestinal Barrier Restoration on PD Mice. Nutrients 2022; 14:nu14194163. [PMID: 36235813 PMCID: PMC9571500 DOI: 10.3390/nu14194163] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 09/30/2022] [Accepted: 10/04/2022] [Indexed: 11/16/2022] Open
Abstract
Research has connected Parkinson's disease (PD) with impaired intestinal barrier. The activation of G-protein-coupled receptor 109A (GPR109A) protects the intestinal barrier by inhibiting the NF-κB signaling pathway. Sodium butyrate (NaB), which is a GPR109A ligand, may have anti-PD effects. The current study's objective is to demonstrate that NaB or monomethyl fumarate (MMF, an agonist of the GPR109A) can treat PD mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) via repairing the intestinal barrier. Male C57BL/6J mice were divided into four groups randomly: control, MPTP + vehicle, MPTP + NaB, and MPTP + MMF. Modeling mice received MPTP (20 mg/kg/day, i.p.) for a week, while control mice received sterile PBS. Then, four groups each received two weeks of sterile PBS (10 mL/kg/day, i.g.), sterile PBS (10 mL/kg/day, i.g.), NaB (600 mg/kg/day, i.g.), or MMF (100 mg/kg/day, i.g.). We assessed the expression of tight junction (TJ) proteins (occludin and claudin-1), GPR109A, and p65 in the colon, performed microscopic examination via HE staining, quantified markers of intestinal permeability and proinflammatory cytokines in serum, and evaluated motor symptoms and pathological changes in the substantia nigra (SN) or striatum. According to our results, MPTP-induced defected motor function, decreased dopamine and 5-hydroxytryptamine levels in the striatum, decreased tyrosine hydroxylase-positive neurons and increased activated microglia in the SN, and systemic inflammation were ameliorated by NaB or MMF treatment. Additionally, the ruined intestinal barrier was also rebuilt and NF-κB was suppressed after the treatment, with higher levels of TJ proteins, GPR109A, and decreased intestinal permeability. These results show that NaB or MMF can remedy motor symptoms and pathological alterations in PD mice by restoring the intestinal barrier with activated GPR109A. We demonstrate the potential for repairing the compromised intestinal barrier and activating GPR109A as promising treatments for PD.
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Affiliation(s)
- Rui-Chen Xu
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- College of First Clinical, Chongqing Medical University, Chongqing 400016, China
| | - Wen-Teng Miao
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- College of Pediatrics, Chongqing Medical University, Chongqing 400016, China
| | - Jing-Yi Xu
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- College of First Clinical, Chongqing Medical University, Chongqing 400016, China
| | - Wen-Xin Xu
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- College of First Clinical, Chongqing Medical University, Chongqing 400016, China
| | - Ming-Ran Liu
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- College of First Clinical, Chongqing Medical University, Chongqing 400016, China
| | - Song-Tao Ding
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
| | - Yu-Xin Jian
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- College of First Clinical, Chongqing Medical University, Chongqing 400016, China
| | - Yi-Han Lei
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- College of First Clinical, Chongqing Medical University, Chongqing 400016, China
| | - Ning Yan
- Department of Neurology, University-Town Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Han-Deng Liu
- Laboratory of Tissue and Cell Biology, Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, China
- Molecular Medicine and Cancer Research Center, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing 400016, China
- Correspondence: ; Tel.: +86-23-65712090
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14
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Cheng Y, Cao P, Geng C, Chu X, Li Y, Cui J. The adenosine A (2A) receptor antagonist SCH58261 protects photoreceptors by inhibiting microglial activation and the inflammatory response. Int Immunopharmacol 2022; 112:109245. [PMID: 36150227 DOI: 10.1016/j.intimp.2022.109245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 08/18/2022] [Accepted: 09/09/2022] [Indexed: 11/05/2022]
Abstract
Photoreceptor degeneration is a principal event in a variety of human retinal diseases. Progressive apoptosis of photoreceptors leads to impaired vision and blindness, for which there is no curative treatment. Adenosine 2A receptors (A2AR) are expressed in microglia. Blockade of A2AR has been shown to protect neurons via suppression of inflammation. However, the therapeutic effects of A2AR antagonists on photoreceptor degeneration have not been characterized. In this study, adult zebrafish were exposed to short term high-intensity light to induce photoreceptor death. SCH58261, a selective A2AR antagonist, was immediately injected into the vitreous body. Photoreceptor degeneration and microglia-induced inflammation were evaluated using immunohistochemistry, quantitative real-time polymerase chain reaction, polarization sensitive optical coherence tomography, and optomotor response. Co-culture of BV2 and 661W cells was used to investigate the interaction between microglia and photoreceptors. The results showed that A2AR was over-expressed during photoreceptor degeneration. Following intraocular SCH58261 injection, microglial activation and release of inflammatory factors were inhibited, and photoreceptor survival increased. Inactivation of microglia prevented apoptosis and autophagy in photoreceptors. Our results showed that SCH58261 intervention at the early stage of photoreceptor degeneration protected photoreceptors through inhibition of the inflammatory response, apoptosis, and autophagy.
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Affiliation(s)
- Yajia Cheng
- Medical International Collaborative Innovation Center, Nankai University School of Medicine, Tianjin, China; Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, China
| | - Peipei Cao
- Medical International Collaborative Innovation Center, Nankai University School of Medicine, Tianjin, China
| | - Chao Geng
- Medical International Collaborative Innovation Center, Nankai University School of Medicine, Tianjin, China
| | - Xiaoqi Chu
- Medical International Collaborative Innovation Center, Nankai University School of Medicine, Tianjin, China
| | - Yuhao Li
- Beijing Geriatric Medical Research Center, Xuanwu Hospital, Capital Medical University, Beijing, China.
| | - Jianlin Cui
- Medical International Collaborative Innovation Center, Nankai University School of Medicine, Tianjin, China.
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15
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Yao J, Wang T, Jia L, Qiu Y, Zacks DN. Loss of Fas Receptor Function Preserves Photoreceptor Structure and Function in Two Mouse Models of Inherited Retinal Degeneration. Invest Ophthalmol Vis Sci 2022; 63:5. [PMID: 36083588 PMCID: PMC9469031 DOI: 10.1167/iovs.63.10.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The genetic heterogeneity of inherited retinal degeneration (IRD) has limited the development of mutation-specific therapies, necessitating the development of therapeutic approaches targeting broadly shared pathophysiologic pathways. The Fas receptor has been reported as a contributor to retinal cell death and inflammation in a wide variety of ocular diseases. The purpose of this study was to assess targeting the Fas pathway as a novel mutation-independent approach to improve photoreceptor survival in IRD. Methods We examined the effects of genetic inactivation of the Fas receptor on retinal degeneration in two distinct IRD mouse models, P23H and rd10. The Fas-lpr mouse, which contains a functionally inactive Fas receptor, was crossed with the P23H and rd10 mice to generate P23H/Fas-lpr and rd10/Fas-lpr mice. Fas activation, photoreceptor survival and retinal function were assessed. Results We detected elevated levels of Fas receptor and microglial activation in the retinas of both P23H and rd10 mice. Inactivation of Fas in these two IRD models (P23H/Fas-lpr and rd10/Fas-lpr mice) resulted in reduced cell death, increased photoreceptor survival, improved retinal function, and reduced microglial activation and inflammatory cytokine production. Conclusions The protective effect of a nonfunctional Fas receptor in two different mouse models of retinal degeneration suggests that whereas the individual IRD mutation may be specific, the retina's response to the different stressors appears to be shared and driven by Fas. Reducing Fas activity might represent a potential mutation-independent therapeutic approach to preserve retinal structure and function in patients with IRD.
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Affiliation(s)
- Jingyu Yao
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Kellogg Eye Center, Ann Arbor, Michigan, United States
| | - Tiantian Wang
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Kellogg Eye Center, Ann Arbor, Michigan, United States.,Department of Ophthalmology, Xiangya School of Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Lin Jia
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Kellogg Eye Center, Ann Arbor, Michigan, United States
| | - Yaoyan Qiu
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Kellogg Eye Center, Ann Arbor, Michigan, United States.,Department of Ophthalmology, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - David N Zacks
- Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Kellogg Eye Center, Ann Arbor, Michigan, United States
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16
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Drinking hydrogen water improves photoreceptor structure and function in retinal degeneration 6 mice. Sci Rep 2022; 12:13610. [PMID: 35948585 PMCID: PMC9365798 DOI: 10.1038/s41598-022-17903-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 08/02/2022] [Indexed: 11/08/2022] Open
Abstract
Retinitis pigmentosa (RP) is a genetically heterogeneous group of inherited retinal disorders involving the progressive dysfunction of photoreceptors and the retinal pigment epithelium, for which there is currently no treatment. The rd6 mouse is a natural model of autosomal recessive retinal degeneration. Given the known contributions of oxidative stress caused by reactive oxygen species (ROS) and selective inhibition of potent ROS peroxynitrite and OH·by H2 gas we have previously demonstrated, we hypothesized that ingestion of H2 water may delay the progression of photoreceptor death in rd6 mice. H2 mice showed significantly higher retinal thickness as compared to controls on optical coherence tomography. Histopathological and morphometric analyses revealed higher thickness of the outer nuclear layer for H2 mice than controls, as well as higher counts of opsin red/green-positive cells. RNA sequencing (RNA-seq) analysis of differentially expressed genes in the H2 group versus control group revealed 1996 genes with significantly different expressions. Gene and pathway ontology analysis showed substantial upregulation of genes responsible for phototransduction in H2 mice. Our results show that drinking water high in H2 (1.2-1.6 ppm) had neuroprotective effects and inhibited photoreceptor death in mice, and suggest the potential of H2 for the treatment of RP.
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17
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Lew DS, McGrath MJ, Finnemann SC. Galectin-3 Promotes Müller Glia Clearance Phagocytosis via MERTK and Reduces Harmful Müller Glia Activation in Inherited and Induced Retinal Degeneration. Front Cell Neurosci 2022; 16:878260. [PMID: 35711472 PMCID: PMC9194531 DOI: 10.3389/fncel.2022.878260] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
Clearance phagocytosis is a documented function of Müller glia in the retina. However, the molecular mechanisms of Müller glia phagocytosis remain largely undefined. Here, we show that extracellular galectin-3 and protein S promote clearance phagocytosis by immortalized human MIO-M1 Müller cells in an additive, saturable manner. Galectin-3 promotes phagocytosis by primary Müller glia from wild-type (WT) mice but not from mice that lack the engulfment receptor MERTK and therefore develop postnatal photoreceptor degeneration. Probing a possible functional link between Müller galectin-3 and MERTK, we discovered that mertk -/- Müller glia in situ show excess galectin-3 at postnatal day 20 (P20), an age prior to detectable photoreceptor degeneration. Moreover, double knockout (DKO) mice lacking both galectin-3 and MERTK show increased activation of Müller cells (but not of microglia) at P20 and more pronounced photoreceptor loss at P35 compared to mice lacking MERTK alone. Exploring the well-established sodium iodate injury model, we also found more severe activation specifically of Müller glia, and worse retinal damage in mice lacking galectin-3 compared to WT mice. Indeed, galectin-3 deficiency significantly increased sensitivity to injury, yielding Müller activation and retinal damage at a sodium iodate concentration that had no effect on the WT retina. Altogether, our results from both inherited and acutely induced models of retinal degeneration agree that eliminating galectin-3 exacerbates Müller cell activation and retinal degeneration. These data identify an important protective role for the MERTK ligand galectin-3 in the retina in restraining Müller glia activation.
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Affiliation(s)
- Deborah S. Lew
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY, United States
| | - Morgan J. McGrath
- Center for Cancer, Genetic Diseases and Gene Regulation, Department of Biological Sciences, Fordham University, Bronx, NY, United States
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18
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Vargas JA, Finnemann SC. Probing Photoreceptor Outer Segment Phagocytosis by the RPE In Vivo: Models and Methodologies. Int J Mol Sci 2022; 23:ijms23073661. [PMID: 35409021 PMCID: PMC8998817 DOI: 10.3390/ijms23073661] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 01/27/2023] Open
Abstract
In the vertebrate retina, the light-sensitive photoreceptor rods and cones constantly undergo renewal by generating new portions of the outer segment and shedding their distal, spent tips. The neighboring RPE provides the critical function of engulfing the spent material by phagocytosis. RPE phagocytosis of shed rod outer segment fragments is a circadian process that occurs in a burst of activity shortly after daily light onset with low activity at other times, a rhythm that has been reported for many species and over 50 years. In this review, we compare studies on the rhythm and quantity of RPE phagocytosis using different in vivo model systems and assessment methods. We discuss how measurement methodology impacts the observation and analysis of RPE phagocytosis. Published studies on RPE phagocytosis investigating mice further suggest that differences in genetic background and housing conditions may affect results. Altogether, a comparison between RPE phagocytosis studies performed using differing methodology and strains of the same species is not as straightforward as previously thought.
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19
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Brunet AA, Harvey AR, Carvalho LS. Primary and Secondary Cone Cell Death Mechanisms in Inherited Retinal Diseases and Potential Treatment Options. Int J Mol Sci 2022; 23:ijms23020726. [PMID: 35054919 PMCID: PMC8775779 DOI: 10.3390/ijms23020726] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/05/2022] [Accepted: 01/05/2022] [Indexed: 12/13/2022] Open
Abstract
Inherited retinal diseases (IRDs) are a leading cause of blindness. To date, 260 disease-causing genes have been identified, but there is currently a lack of available and effective treatment options. Cone photoreceptors are responsible for daylight vision but are highly susceptible to disease progression, the loss of cone-mediated vision having the highest impact on the quality of life of IRD patients. Cone degeneration can occur either directly via mutations in cone-specific genes (primary cone death), or indirectly via the primary degeneration of rods followed by subsequent degeneration of cones (secondary cone death). How cones degenerate as a result of pathological mutations remains unclear, hindering the development of effective therapies for IRDs. This review aims to highlight similarities and differences between primary and secondary cone cell death in inherited retinal diseases in order to better define cone death mechanisms and further identify potential treatment options.
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Affiliation(s)
- Alicia A. Brunet
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Lions Eye Institute Ltd., 2 Verdun St, Nedlands, WA 6009, Australia
- Correspondence: ; Tel.: +61-423-359-714
| | - Alan R. Harvey
- School of Human Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Perron Institute for Neurological and Translational Science, 8 Verdun St, Nedlands, WA 6009, Australia
| | - Livia S. Carvalho
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Lions Eye Institute Ltd., 2 Verdun St, Nedlands, WA 6009, Australia
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20
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Zhang Y, Wang Y, Ding J, Liu P. Efferocytosis in multisystem diseases (Review). Mol Med Rep 2022; 25:13. [PMID: 34779503 PMCID: PMC8600411 DOI: 10.3892/mmr.2021.12529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/15/2021] [Indexed: 01/22/2023] Open
Abstract
Efferocytosis, the phagocytosis of apoptotic cells performed by both specialized phagocytes (such as macrophages) and non‑specialized phagocytes (such as epithelial cells), is involved in tissue repair and homeostasis. Effective efferocytosis prevents secondary necrosis, terminates inflammatory responses, promotes self‑tolerance and activates pro‑resolving pathways to maintain homeostasis. When efferocytosis is impaired, apoptotic cells that could not be cleared in time aggregate, resulting in the necrosis of apoptotic cells and release of pro‑inflammatory factors. In addition, defective efferocytosis inhibits the intracellular cholesterol reverse transportation pathways, which may lead to atherosclerosis, lung damage, non‑alcoholic fatty liver disease and neurodegenerative diseases. The uncleared apoptotic cells can also release autoantigens, which can cause autoimmune diseases. Cancer cells escape from phagocytosis via efferocytosis. Therefore, new treatment strategies for diseases related to defective efferocytosis are proposed. This review illustrated the mechanisms of efferocytosis in multisystem diseases and organismal homeostasis and the pathophysiological consequences of defective efferocytosis. Several drugs and treatments available to enhance efferocytosis are also mentioned in the review, serving as new evidence for clinical application.
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Affiliation(s)
- Yifan Zhang
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, P.R. China
- Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Yiru Wang
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, P.R. China
- Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Jie Ding
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, P.R. China
- Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Ping Liu
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, P.R. China
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21
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Ozaki E, Delaney C, Campbell M, Doyle SL. Minocycline suppresses disease-associated microglia (DAM) in a model of photoreceptor cell degeneration. Exp Eye Res 2022; 217:108953. [DOI: 10.1016/j.exer.2022.108953] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 11/04/2022]
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22
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Jin N, Sha W, Gao L. Shaping the Microglia in Retinal Degenerative Diseases Using Stem Cell Therapy: Practice and Prospects. Front Cell Dev Biol 2021; 9:741368. [PMID: 34966736 PMCID: PMC8710684 DOI: 10.3389/fcell.2021.741368] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 11/29/2021] [Indexed: 12/11/2022] Open
Abstract
Retinal degenerative disease (RDD) refers to a group of diseases with retinal degeneration that cause vision loss and affect people's daily lives. Various therapies have been proposed, among which stem cell therapy (SCT) holds great promise for the treatment of RDDs. Microglia are immune cells in the retina that have two activation phenotypes, namely, pro-inflammatory M1 and anti-inflammatory M2 phenotypes. These cells play an important role in the pathological progression of RDDs, especially in terms of retinal inflammation. Recent studies have extensively investigated the therapeutic potential of stem cell therapy in treating RDDs, including the immunomodulatory effects targeting microglia. In this review, we substantially summarized the characteristics of RDDs and microglia, discussed the microglial changes and phenotypic transformation of M1 microglia to M2 microglia after SCT, and proposed future directions for SCT in treating RDDs.
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Affiliation(s)
- Ni Jin
- Senior Department of Ophthalmology, The Third Medical Center of Chinese People's Liberation Army General Hospital, Beijing, China.,Department of Endocrinology, The Second Medical Center and National Clinical Research Center for Geriatric Diseases, Chinese People's Liberation Army General Hospital, Beijing, China
| | - Weiwei Sha
- Department of Endocrinology, The Second Medical Center and National Clinical Research Center for Geriatric Diseases, Chinese People's Liberation Army General Hospital, Beijing, China
| | - Lixiong Gao
- Senior Department of Ophthalmology, The Third Medical Center of Chinese People's Liberation Army General Hospital, Beijing, China
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23
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Chen M, Ren C, Ren B, Fang Y, Li Q, Zeng Y, Li Y, Chen F, Bian B, Liu Y. Human Retinal Progenitor Cells Derived Small Extracellular Vesicles Delay Retinal Degeneration: A Paradigm for Cell-free Therapy. Front Pharmacol 2021; 12:748956. [PMID: 34912217 PMCID: PMC8667779 DOI: 10.3389/fphar.2021.748956] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 11/02/2021] [Indexed: 01/03/2023] Open
Abstract
Retinal degeneration is a leading cause of irreversible vision impairment and blindness worldwide. Previous studies indicate that subretinal injection of human retinal progenitor cells (hRPCs) can delay the progression of retinal degeneration, preserve retinal function, and protect photoreceptor cells from death, albeit the mechanism is not well understood. In this study, small extracellular vesicles derived from hRPCs (hRPC-sEVs) were injected into the subretinal space of retinal dystrophic RCS rats. We find that hRPC-sEVs significantly preserve the function of retina and thickness of the outer nuclear layer (ONL), reduce the apoptosis of photoreceptors in the ONL, and suppress the inflammatory response in the retina of RCS rats. In vitro, we have shown that hRPC-sEV treatment could significantly reserve the low-glucose preconditioned apoptosis of photoreceptors and reduce the expression of pro-inflammatory cytokines in microglia. Pathway analysis predicted the target genes of hRPC-sEV microRNAs involved in inflammation related biological processes and significantly enriched in processes autophagy, signal release, regulation of neuron death, and cell cycle. Collectively, our study suggests that hRPC-sEVs might be a favorable agent to delay retinal degeneration and highlights as a new paradigm for cell-free therapy.
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Affiliation(s)
- Min Chen
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Chunge Ren
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Bangqi Ren
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yajie Fang
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Qiyou Li
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yuxiao Zeng
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yijian Li
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Fang Chen
- Department of Medical Technology, Chongqing Medical and Pharmaceutical College, Chongqing, China
| | - Baishijiao Bian
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China.,Army 953 Hospital, Shigatse Branch of Xinqiao Hospital, Army Medical University, Shigatse, China
| | - Yong Liu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
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Acute RhoA/Rho Kinase Inhibition Is Sufficient to Restore Phagocytic Capacity to Retinal Pigment Epithelium Lacking the Engulfment Receptor MerTK. Cells 2021; 10:cells10081927. [PMID: 34440696 PMCID: PMC8394172 DOI: 10.3390/cells10081927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 12/27/2022] Open
Abstract
The diurnal phagocytosis of spent photoreceptor outer segment fragments (POS) by retinal pigment epithelial (RPE) cells is essential for visual function. POS internalization by RPE cells requires the assembly of F-actin phagocytic cups beneath surface-tethered POS and Mer tyrosine kinase (MerTK) signaling. The activation of the Rho family GTPase Rac1 is necessary for phagocytic cup formation, and Rac1 is activated normally in MerTK-deficient RPE. We show here that mutant RPE lacking MerTK and wild-type RPE deprived of MerTK ligand both fail to form phagocytic cups regardless of Rac1 activation. However, in wild-type RPE in vivo, a decrease in RhoA activity coincides with the daily phagocytosis burst, while RhoA activity in MerTK-deficient RPE is constant. Elevating RhoA activity blocks phagocytic cup formation and phagocytosis by wild-type RPE. Conversely, inhibiting RhoA effector Rho kinases (ROCKs) rescues both F-actin assembly and POS internalization of primary RPE if MerTK or its ligand are lacking. Most strikingly, acute ROCK inhibition is sufficient to induce the formation and acidification of endogenous POS phagosomes by MerTK-deficient RPE ex vivo. Altogether, RhoA pathway inactivation is a necessary and sufficient downstream effect of MerTK phagocytic signaling such that the acute manipulation of cytosolic ROCK activity suffices to restore phagocytic capacity to MerTK-deficient RPE.
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Krueger K, Boehme E, Klettner AK, Zille M. The potential of marine resources for retinal diseases: a systematic review of the molecular mechanisms. Crit Rev Food Sci Nutr 2021; 62:7518-7560. [PMID: 33970706 DOI: 10.1080/10408398.2021.1915242] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We rely on vision more than on any other sense to obtain information about our environment. Hence, the loss or even impairment of vision profoundly affects our quality of life. Diet or food components have already demonstrated beneficial effects on the development of retinal diseases. Recently, there has been a growing interest in resources from marine animals and plants for the prevention of retinal diseases through nutrition. Especially fish intake and omega-3 fatty acids have already led to promising results, including associations with a reduced incidence of retinal diseases. However, the underlying molecular mechanisms are insufficiently explained. The aim of this review was to summarize the known mechanistic effects of marine resources on the pathophysiological processes in retinal diseases. We performed a systematic literature review following the PRISMA guidelines and identified 107 studies investigating marine resources in the context of retinal diseases. Of these, 46 studies described the underlying mechanisms including anti-inflammatory, antioxidant, antiangiogenic/vasoprotective, cytoprotective, metabolic, and retinal function effects, which we critically summarize. We further discuss perspectives on the use of marine resources for human nutrition to prevent retinal diseases with a particular focus on regulatory aspects, health claims, safety, and bioavailability.
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Affiliation(s)
- Kristin Krueger
- Department of Marine Biotechnology, Fraunhofer Research and Development Center for Marine and Cellular Biotechnology EMB, Lübeck, Germany
| | - Elke Boehme
- Department of Marine Biotechnology, Fraunhofer Research and Development Center for Marine and Cellular Biotechnology EMB, Lübeck, Germany
| | - Alexa Karina Klettner
- Department of Ophthalmology, University Medical Center, University of Kiel, Quincke Research Center, Kiel, Germany
| | - Marietta Zille
- Department of Marine Biotechnology, Fraunhofer Research and Development Center for Marine and Cellular Biotechnology EMB, Lübeck, Germany.,Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
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26
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Williamson B, Pilla Reddy V. Blood retinal barrier and ocular pharmacokinetics: Considerations for the development of oncology drugs. Biopharm Drug Dispos 2021; 42:128-136. [PMID: 33759216 DOI: 10.1002/bdd.2276] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 03/09/2021] [Accepted: 03/14/2021] [Indexed: 12/12/2022]
Abstract
Tyrosine kinase inhibitors (TKIs) are an example of targeted drug therapy to treat cancer while minimizing damage to healthy tissue. In contrast to traditional oncology drugs, the toxicity profile of targeted therapies is less well understood and can include severe ocular adverse events, which are among the most common toxicity reported by these therapeutics. Inhibition of Mer receptor tyrosine kinase (MERTK) promotes innate tumor immunity by decreasing M2-macrophage polarization and efferocytosis. This mechanism offers the opportunity for targeted immunotherapy to treat cancer; however, the ocular expression of MERTK increases the difficulty for developing a targeted drug due to toxicity concerns. In this article we review the pharmacokinetic (PK) parameters and in vitro absorption, distribution, metabolism, and excretion (ADME) assays available to evaluate ocular disposition and assess the relationship between clinical PK and reported ocular events for TKIs to allow backtranslation to preclinical models. Understanding the ocular disposition in the context of PK and safety remains an evolving area and is likely to be a key aspect of developing safe and efficacious oncology drugs, devoid of ocular toxicity.
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Affiliation(s)
- Beth Williamson
- Drug Metabolism and Pharmacokinetics, Early Oncology, Oncology R&D, AstraZeneca, Cambridge, UK
| | - Venkatesh Pilla Reddy
- Modelling and Simulation, Early Oncology, Oncology R&D, AstraZeneca, Cambridge, UK.,Clinical Pharmacology and Quantitative Pharmacology, Biopharmaceuticals R&D, AstraZeneca, Cambridge, UK
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Lack of the antioxidant enzyme methionine sulfoxide reductase A in mice impairs RPE phagocytosis and causes photoreceptor cone dysfunction. Redox Biol 2021; 42:101918. [PMID: 33674251 PMCID: PMC8113033 DOI: 10.1016/j.redox.2021.101918] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/02/2021] [Accepted: 02/20/2021] [Indexed: 12/17/2022] Open
Abstract
Methionine sulfoxide reductase A (MsrA) is a widely expressed antioxidant enzyme that counteracts oxidative protein damage and contributes to protein regulation by reversing oxidation of protein methionine residues. In retinal pigment epithelial (RPE) cells in culture, MsrA overexpression increases phagocytic capacity by supporting mitochondrial ATP production. Here, we show elevated retinal protein carbonylation indicative of oxidation, decreased RPE mitochondrial membrane potential, and attenuated RPE phagocytosis in msra−/− mice. Moreover, electroretinogram recordings reveal decreased light responses specifically of cone photoreceptors despite normal expression and localization of cone opsins. Impairment in msra−/− cone-driven responses is similar from 6 weeks to 13 months of age. These functional changes match dramatic decreases in lectin-labeled cone sheaths and reduction in cone arrestin in msra−/− mice. Strikingly, cone defects in light response and in lectin-labeled cone sheath are completely prevented by dark rearing. Together, our data show that msra−/− mice provide a novel small animal model of preventable cone-specific photoreceptor dysfunction that may have future utility in analysis of cone dystrophy disease mechanisms and testing therapeutic approaches aiming to alleviate cone defects.
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Retinal Inflammation, Cell Death and Inherited Retinal Dystrophies. Int J Mol Sci 2021; 22:ijms22042096. [PMID: 33672611 PMCID: PMC7924201 DOI: 10.3390/ijms22042096] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/12/2021] [Accepted: 02/18/2021] [Indexed: 12/15/2022] Open
Abstract
Inherited retinal dystrophies (IRDs) are a group of retinal disorders that cause progressive and severe loss of vision because of retinal cell death, mainly photoreceptor cells. IRDs include retinitis pigmentosa (RP), the most common IRD. IRDs present a genetic and clinical heterogeneity that makes it difficult to achieve proper treatment. The progression of IRDs is influenced, among other factors, by the activation of the immune cells (microglia, macrophages, etc.) and the release of inflammatory molecules such as chemokines and cytokines. Upregulation of tumor necrosis factor alpha (TNFα), a pro-inflammatory cytokine, is found in IRDs. This cytokine may influence photoreceptor cell death. Different cell death mechanisms are proposed, including apoptosis, necroptosis, pyroptosis, autophagy, excessive activation of calpains, or parthanatos for photoreceptor cell death. Some of these cell death mechanisms are linked to TNFα upregulation and inflammation. Therapeutic approaches that reduce retinal inflammation have emerged as useful therapies for slowing down the progression of IRDs. We focused this review on the relationship between retinal inflammation and the different cell death mechanisms involved in RP. We also reviewed the main anti-inflammatory therapies for the treatment of IRDs.
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Raiders S, Han T, Scott-Hewitt N, Kucenas S, Lew D, Logan MA, Singhvi A. Engulfed by Glia: Glial Pruning in Development, Function, and Injury across Species. J Neurosci 2021; 41:823-833. [PMID: 33468571 PMCID: PMC7880271 DOI: 10.1523/jneurosci.1660-20.2020] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/20/2020] [Accepted: 10/26/2020] [Indexed: 02/07/2023] Open
Abstract
Phagocytic activity of glial cells is essential for proper nervous system sculpting, maintenance of circuitry, and long-term brain health. Glial engulfment of apoptotic cells and superfluous connections ensures that neuronal connections are appropriately refined, while clearance of damaged projections and neurotoxic proteins in the mature brain protects against inflammatory insults. Comparative work across species and cell types in recent years highlights the striking conservation of pathways that govern glial engulfment. Many signaling cascades used during developmental pruning are re-employed in the mature brain to "fine tune" synaptic architecture and even clear neuronal debris following traumatic events. Moreover, the neuron-glia signaling events required to trigger and perform phagocytic responses are impressively conserved between invertebrates and vertebrates. This review offers a compare-and-contrast portrayal of recent findings that underscore the value of investigating glial engulfment mechanisms in a wide range of species and contexts.
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Affiliation(s)
- Stephan Raiders
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington 98195
| | - Taeho Han
- UCSF Weill Institute for Neurosciences, University of California San Francisco, San Francisco, California 94158
| | - Nicole Scott-Hewitt
- F.M. Kirby Center for Neurobiology, Boston Children's Hospital, Boston, Massachusetts 02115
- Stanley Center for Psychiatric Research, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142
| | - Sarah Kucenas
- Department of Biology, University of Virginia, Charlottesville, Virginia 22904
| | - Deborah Lew
- Department of Biological Sciences, Fordham University, Bronx, New York 10458
| | - Mary A Logan
- Jungers Center, Department of Neurology, Oregon Health and Science University, Portland, Oregon 97239
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington 98195
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30
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Maguire AM, Bennett J, Aleman EM, Leroy BP, Aleman TS. Clinical Perspective: Treating RPE65-Associated Retinal Dystrophy. Mol Ther 2021; 29:442-463. [PMID: 33278565 PMCID: PMC7854308 DOI: 10.1016/j.ymthe.2020.11.029] [Citation(s) in RCA: 90] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/16/2020] [Accepted: 11/25/2020] [Indexed: 12/25/2022] Open
Abstract
Until recently, there was no approved treatment for a retinal degenerative disease. Subretinal injection of a recombinant adeno-associated virus (AAV) delivering the normal copy of the human RPE65 cDNA led to reversal of blindness first in animal models and then in humans. This led to the first US Food and Drug Administration (FDA)-approved gene therapy product for a genetic disease, voretigene neparvovec-rzyl (Luxturna). Luxturna was then approved by the European Medicines Association and is now available in the US through Spark Therapeutics and worldwide through Novartis. Not only has treatment with Luxturna changed the lives of people previously destined to live a life of blindness, but it has fueled interest in developing additional gene therapy reagents targeting numerous other genetic forms of inherited retinal disease. This review describes many of the considerations for administration of Luxturna and describes how lessons from experience with Luxturna could lead to additional gene-based treatments of blindness.
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Affiliation(s)
- Albert M Maguire
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; The Children's Hospital of Philadelphia (CHOP), Philadelphia, PA, USA
| | - Jean Bennett
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; The Children's Hospital of Philadelphia (CHOP), Philadelphia, PA, USA
| | - Elena M Aleman
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Bart P Leroy
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Ophthalmology and Center for Medical Genetics Ghent, Ghent University Hospital, Ghent, Belgium
| | - Tomas S Aleman
- Center for Advanced Retinal and Ocular Therapeutics (CAROT), Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; The Children's Hospital of Philadelphia (CHOP), Philadelphia, PA, USA.
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Greferath U, Huynh M, Jobling AI, Vessey KA, Venables G, Surrao D, O'Neill HC, Limnios IJ, Fletcher EL. Dorsal-Ventral Differences in Retinal Structure in the Pigmented Royal College of Surgeons Model of Retinal Degeneration. Front Cell Neurosci 2021; 14:553708. [PMID: 33536874 PMCID: PMC7848141 DOI: 10.3389/fncel.2020.553708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 12/17/2020] [Indexed: 11/29/2022] Open
Abstract
Retinitis pigmentosa is a family of inherited retinal degenerations associated with gradual loss of photoreceptors, that ultimately leads to irreversible vision loss. The Royal College of Surgeon's (RCS) rat carries a recessive mutation affecting mer proto-oncogene tyrosine kinase (merTK), that models autosomal recessive disease. The aim of this study was to understand the glial, microglial, and photoreceptor changes that occur in different retinal locations with advancing disease. Pigmented RCS rats (RCS-p+/LAV) and age-matched isogenic control rdy (RCS-rdy +p+/LAV) rats aged postnatal day 18 to 6 months were evaluated for in vivo retinal structure and function using optical coherence tomography and electroretinography. Retinal tissues were assessed using high resolution immunohistochemistry to evaluate changes in photoreceptors, glia and microglia in the dorsal, and ventral retina. Photoreceptor dysfunction and death occurred from 1 month of age. There was a striking difference in loss of photoreceptors between the dorsal and ventral retina, with a greater number of photoreceptors surviving in the dorsal retina, despite being adjacent a layer of photoreceptor debris within the subretinal space. Loss of photoreceptors in the ventral retina was associated with fragmentation of the outer limiting membrane, extension of glial processes into the subretinal space that was accompanied by possible adhesion and migration of mononuclear phagocytes in the subretinal space. Overall, these findings highlight that breakdown of the outer limiting membrane could play an important role in exacerbating photoreceptor loss in the ventral retina. Our results also highlight the value of using the RCS rat to model sectorial retinitis pigmentosa, a disease known to predominantly effect the inferior retina.
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Affiliation(s)
- Una Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Mario Huynh
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Andrew Ian Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Kirstan Anne Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Gene Venables
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Denver Surrao
- Clem Jones Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD, Australia
| | - Helen Christine O'Neill
- Clem Jones Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD, Australia
| | - Ioannis J Limnios
- Clem Jones Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD, Australia
| | - Erica Lucy Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
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Bagewadi S, Parameswaran S, Krishnakumar S, Sethuraman S, Subramanian A. Tissue engineering approaches towards the regeneration of biomimetic scaffolds for age-related macular degeneration. J Mater Chem B 2021; 9:5935-5953. [PMID: 34254105 DOI: 10.1039/d1tb00976a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Age-related macular degeneration (AMD) is the third major cause of blindness in people aged above 60 years. It causes dysfunction of the retinal pigment epithelium (RPE) and leads to an irreversible loss of central vision. The present clinical treatment options are more palliative in controlling the progression of the disease and do not functionally restore the degenerated RPE monolayer and photoreceptors. Currently, the clinical transplantation of RPE cells has shown poor engraftment potential due to the absence of an intact Bruch's membrane in AMD patients, thereby the vision is unable to be restored completely. Although tissue engineering strategies target the development of Bruch's membrane-mimetic substrates, the challenge still lies in the development of an ultrathin, biologically and mechanically equivalent membrane to restore visual acuity. Further, existing limitations such as cellular aggregation, surgical complications including retinal tissue damage, tissue rejection, disease transmission, inferior mechanical strength, and the loss of vision over time demand the search for an ideal strategy to restore the functional RPE. Hence, this review aims to provide insights into various approaches, from conventional cell therapy to 3D bioprinting, and their unmet challenges in treating AMD by outlining the pathophysiology of AMD and the host tissue response with respect to injury, treatment and preclinical animal models.
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Affiliation(s)
- Shambhavi Bagewadi
- Tissue Engineering & Additive Manufacturing (TEAM) Lab, Centre for Nanotechnology & Advanced Biomaterials, ABCDE Innovation Centre, School of Chemical & Biotechnology, SASTRA Deemed University, Thanjavur 613 401, Tamil Nadu, India.
| | - Sowmya Parameswaran
- Radheshyam Kanoi Stem Cell Laboratory, Kamalnayan Bajaj Institute for Research in Vision and Ophthalmology Vision Research Foundation, Chennai, India
| | - Subramanian Krishnakumar
- Radheshyam Kanoi Stem Cell Laboratory, Kamalnayan Bajaj Institute for Research in Vision and Ophthalmology Vision Research Foundation, Chennai, India
| | - Swaminathan Sethuraman
- Tissue Engineering & Additive Manufacturing (TEAM) Lab, Centre for Nanotechnology & Advanced Biomaterials, ABCDE Innovation Centre, School of Chemical & Biotechnology, SASTRA Deemed University, Thanjavur 613 401, Tamil Nadu, India.
| | - Anuradha Subramanian
- Tissue Engineering & Additive Manufacturing (TEAM) Lab, Centre for Nanotechnology & Advanced Biomaterials, ABCDE Innovation Centre, School of Chemical & Biotechnology, SASTRA Deemed University, Thanjavur 613 401, Tamil Nadu, India.
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Moriuchi Y, Iwagawa T, Tsuhako A, Koso H, Fujita Y, Watanabe S. RasV12 Expression in Microglia Initiates Retinal Inflammation and Induces Photoreceptor Degeneration. Invest Ophthalmol Vis Sci 2020; 61:34. [PMID: 33231622 PMCID: PMC7691791 DOI: 10.1167/iovs.61.13.34] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 11/05/2020] [Indexed: 12/04/2022] Open
Abstract
Purpose The role of activated retinal microglia in driving retinal degeneration has been implicated in a number of in vivo disease models. Here, we investigated the primary consequences of microglial activation by the specific expression of constitutively active Ras in microglia in a transgenic mouse model before the onset of any degenerative changes in the retina. Methods The double transgenic lines CAG-LSL-RasV12-IRES-EGFP; Cx3cr1CreER/+ (Cx3cr1-RasV12 mice) and CAG-LSL-EGFP; Cx3cr1CreER_+ (control mice) were generated. The expression of RasV12 was induced in microglia by tamoxifen administration, and the retinas were examined by immunohistochemistry of frozen sections, RT-qPCR, and live imaging. Results RasV12 expression in retinal microglial cells promoted cell proliferation, cytokine expression, and phagocytosis. RasV12-expressing microglia migrated toward the inner and outer layers of the retina. Examination of glial fibrillary acidic protein (GFAP) expression revealed activation of Müller glia in the retina. We also observed loss of the photoreceptors in the outer nuclear layer in close proximity to microglial cells. However, no significant neurodegeneration was detected in the inner nuclear layer (INL) or ganglion cell layer (GCL). The morphology of RasV12-expressing microglia in the GCL and INL retained more ramified features compared with the predominantly-ameboid morphology found in outer retinal microglia. Conclusions The expression of RasV12 is sufficient to activate microglia and lead to photoreceptor degeneration. Neurons in the inner side of the retina were not damaged by the RasV12-activated microglia, suggesting that microenvironment cues may modulate the microglial phenotypic features and effects of microglial activation.
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Affiliation(s)
- Yuta Moriuchi
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Toshiro Iwagawa
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Asano Tsuhako
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Hideto Koso
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Yasuyuki Fujita
- Department of Molecular Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Sumiko Watanabe
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
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