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Elsayed OA, Cai J, Liu Y. Exfoliation syndrome genetics in the era of post-GWAS. Vision Res 2025; 226:108518. [PMID: 39549468 PMCID: PMC11624108 DOI: 10.1016/j.visres.2024.108518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2024] [Revised: 11/05/2024] [Accepted: 11/05/2024] [Indexed: 11/18/2024]
Abstract
Exfoliation syndrome (XFS), or pseudoexfoliation syndrome, is considered a systemic disorder that leads to glaucoma with progressive visual field loss. A better insight into the underlying pathogenic mechanism will help diagnose the disease and prevent and slow progression. Here, we provide an overview of disease pathogenesis in the light of GWAS and multi-omics research. We discuss possible environmental interactions related to XFS. We investigate the potential interactions in differentially expressed genes from RNA-Seq by using Ingenuity Pathway Analysis. MAPK pathway was identified as the top network of these genes. Further investigation is needed to verify our results in vivo. It is necessary to establish an animal model mimicking exfoliation syndrome phenotypes.
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Affiliation(s)
- Ola A Elsayed
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Jingwen Cai
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA; Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, USA.
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Venkatesan A, Ridilla M, Castro N, Wolosin JM, Henty-Ridilla JL, Knox BE, Ganapathy PS, Brown JS, DeVincentis AF, Sieminski S, Bernstein AM. Mitochondrial and Microtubule Defects in Exfoliation Glaucoma. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.11.25.625249. [PMID: 39651300 PMCID: PMC11623661 DOI: 10.1101/2024.11.25.625249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2024]
Abstract
Exfoliation Syndrome (XFS) is an age-related systemic condition characterized by large aggregated fibrillar material deposition in the anterior eye tissues. This aggregate formation and deposition on the aqueous humor outflow pathway are significant risk factors for developing Exfoliation Glaucoma (XFG), a secondary open-angle glaucoma. XFG is a complex, multifactorial late-onset disease that shares common features of neurodegenerative diseases, such as altered cellular processes with increased protein aggregation, impaired protein degradation, and oxidative and cellular stress. XFG patients display decreased mitochondrial membrane potential and mitochondrial DNA deletions. Here, using Tenon Capsule Fibroblasts (TFs) from Normal (No Glaucoma) and XFG patients, we found that XFG TFs have impaired mitochondrial bioenergetics and increased reactive oxygen species (ROS) accumulation. These defects are associated with mitochondrial abnormalities as XFG TFs exhibit smaller mitochondria that contain dysmorphic cristae, with an increase in mitochondrial localization to lysosomes and slowed mitophagy flux. Mitochondrial dysfunction in the XFG TFs was associated with an increase in the dynamics of the microtubule cytoskeleton, decreased acetylated tubulin, and increased HDAC6 activity. Treatment of XFG TFs with a mitophagy inducer, Urolithin A, and a mitochondrial biogenesis inducer, NAD + precursor, Nicotinamide Ribose, improved mitochondrial bioenergetics and reduced ROS accumulation. Our results demonstrate abnormal mitochondria in XFG TFs and suggest that mitophagy inducers may represent a potential class of therapeutics for reversing mitochondrial dysfunction in XFG patients.
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Kuchtey RW, Insignares S, Yang TS, Kuchtey J. In Search of Mouse Models for Exfoliation Syndrome. Am J Ophthalmol 2024; 267:271-285. [PMID: 38909741 PMCID: PMC11486597 DOI: 10.1016/j.ajo.2024.06.015] [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] [Received: 12/19/2023] [Revised: 06/04/2024] [Accepted: 06/12/2024] [Indexed: 06/25/2024]
Abstract
PURPOSE Exfoliation syndrome (XFS) is a systemic connective tissue disorder with elusive pathophysiology. We hypothesize that a mouse model with elastic fiber defects caused by lack of lysyl oxidase like 1 (LOXL1 encoded by Loxl1), combined with microfibril deficiency due to Fbn1 mutation (encoding fibrillin-1, Fbn1C1041G/+) will display ocular and systemic phenotypes of XFS. METHODS Loxl1-/- was crossed with Fbn1C1041G/+ to create double mutant (dbm) mice. Intraocular pressure (IOP), visual acuity (VA), electroretinogram (ERG), and biometry were characterized in 4 genotypes (wt, Fbn1C1041G/+, Loxl1-/-, dbm) at 16 weeks of age. Optic nerve (ON) area was measured by ImageJ, and axon counting was achieved by AxonJ. Deep whole-body phenotyping was performed in wt and dbm mice. Two-tailed Student t test was used for statistical analysis. RESULTS There was no difference in IOP between the 4 genotypes. VA was significantly reduced only in dbm mice. The majority of biometric parameters showed significant differences in all 3 mutant genotypes compared with wt, and dbm had exacerbated anomalies compared with single mutants. Dbm mice showed reduced retinal function and significantly enlarged ON area compared with wt. Dbm mice exhibited severe systemic phenotypes related to abnormal elastic fibers, such as pelvic organ prolapse and cardiovascular and pulmonary abnormalities. CONCLUSIONS Ocular and systemic findings in dbm mice support functional overlap between fibrillin-1 and LOXL1, 2 prominent components of exfoliation material. Although no elevated IOP or reduction of axon numbers was detected in dbm mice at 16 weeks of age, their reduced retinal function and enlarged ON area indicate early retinal ganglion cell dysfunction. Dbm mice also provide insight on the link between XFS and systemic diseases in humans. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
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Affiliation(s)
- Rachel W Kuchtey
- From the Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center (R.W.K., S.I., J.K.), Nashville, Tennessee; Department of Molecular Physiology and Biophysics, Vanderbilt University (R.W.K.), Nashville, Tennessee.
| | - Samuel Insignares
- From the Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center (R.W.K., S.I., J.K.), Nashville, Tennessee
| | - Tzushan S Yang
- Division of Comparative Medicine, Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center (T.S.Y.), Nashville, Tennessee, USA
| | - John Kuchtey
- From the Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center (R.W.K., S.I., J.K.), Nashville, Tennessee
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Wu HJ, Krystofiak E, Kuchtey J, Kuchtey RW. Enhanced Optic Nerve Expansion and Altered Ultrastructure of Elastic Fibers Induced by Lysyl Oxidase Inhibition in a Mouse Model of Marfan Syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2024; 194:1317-1328. [PMID: 38548269 PMCID: PMC11317902 DOI: 10.1016/j.ajpath.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 02/27/2024] [Accepted: 03/11/2024] [Indexed: 04/09/2024]
Abstract
Two major constituents of exfoliation material, fibrillin-1 and lysyl oxidase-like 1 (encoded by FBN1 and LOXL1), are implicated in exfoliation glaucoma, yet their individual contributions to ocular phenotype are minor. To test the hypothesis that a combination of FBN1 mutation and LOXL1 deficiency exacerbates ocular phenotypes, the pan-lysyl oxidase inhibitor β-aminopropionitrile (BAPN) was used to treat adult wild-type (WT) mice and mice heterozygous for a missense mutation in Fbn1 (Fbn1C1041G/+) for 8 weeks and their eyes were examined. Although intraocular pressure did not change and exfoliation material was not detected in the eyes, BAPN treatment worsened optic nerve and axon expansion in Fbn1C1041G/+ mice, an early sign of axonal damage in rodent models of glaucoma. Disruption of elastic fibers was detected only in Fbn1C1041G/+ mice, which increased with BAPN treatment, as shown by histologic and immunohistochemical staining of the optic nerve pia mater. Transmission electron microscopy showed that Fbn1C1041G/+ mice had fewer microfibrils, smaller elastin cores, and a lower density of elastic fibers compared with WT mice in control groups. BAPN treatment led to elastin core expansion in both WT and Fbn1C1041G/+ mice, but an increase in the density of elastic fiber was confined to Fbn1C1041G/+ mice. LOX inhibition had a stronger effect on optic nerve and elastic fiber parameters in the context of Fbn1 mutation, indicating the Marfan mouse model with LOX inhibition warrants further investigation for exfoliation glaucoma pathogenesis.
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Affiliation(s)
- Hang-Jing Wu
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Evan Krystofiak
- Cell Imaging Shared Resource, Vanderbilt University, Nashville, Tennessee
| | - John Kuchtey
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Rachel W Kuchtey
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.
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Meyer KJ, Fingert JH, Anderson MG. Lack of evidence for GWAS signals of exfoliation glaucoma working via monogenic loss-of-function mutation in the nearest gene. Hum Mol Genet 2024:ddae088. [PMID: 38770563 DOI: 10.1093/hmg/ddae088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/29/2024] [Accepted: 05/14/2024] [Indexed: 05/22/2024] Open
Abstract
PURPOSE Exfoliation syndrome (XFS) is a systemic disease of elastin-rich tissues involving a deposition of fibrillar exfoliative material (XFM) in the anterior chamber of the eye, which can promote glaucoma. The purpose of this study was to create mice with CRISPR/Cas9-induced variations in candidate genes identified from human genome-wide association studies (GWAS) and screen them for indices of XFS. METHODS Variants predicted to be deleterious were sought in the Agpat1, Cacna1a, Loxl1, Pomp, Rbms3, Sema6a, and Tlcd5 genes of C57BL/6J mice using CRISPR/Cas9-based gene editing. Strains were phenotyped by slit-lamp, SD-OCT imaging, and fundus exams at 1-5 mos of age. Smaller cohorts of 12-mos-old mice were also studied. RESULTS Deleterious variants were identified in six targets; Pomp was recalcitrant to targeting. Multiple alleles of some targets were isolated, yielding 12 strains. Across all genotypes and ages, 277 mice were assessed by 902 slit-lamp exams, 928 SD-OCT exams, and 358 fundus exams. Homozygosity for Agpat1 or Cacna1a mutations led to early lethality; homozygosity for Loxl1 mutations led to pelvic organ prolapse, preventing aging. Loxl1 homozygotes exhibited a conjunctival phenotype of potential relevance to XFS. Multiple other genotype-specific phenotypes were variously identified. XFM was not observed in any mice. CONCLUSIONS This study did not detect XFM in any of the strains. This may have been due to species-specific differences, background dependence, or insufficient aging. Alternatively, it is possible that the current candidates, selected based on proximity to GWAS signals, are not effectors acting via monogenic loss-of-function mechanisms.
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Affiliation(s)
- Kacie J Meyer
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd, Iowa City, IA 52242, United States
- Institute for Vision Research, University of Iowa, 375 Newton Rd, Iowa City, IA 52242, United States
| | - John H Fingert
- Institute for Vision Research, University of Iowa, 375 Newton Rd, Iowa City, IA 52242, United States
- Department of Ophthalmology and Visual Sciences, University of Iowa, 200 Hawkins Dr, Iowa City, IA 52242, United States
| | - Michael G Anderson
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd, Iowa City, IA 52242, United States
- Institute for Vision Research, University of Iowa, 375 Newton Rd, Iowa City, IA 52242, United States
- Department of Ophthalmology and Visual Sciences, University of Iowa, 200 Hawkins Dr, Iowa City, IA 52242, United States
- Center for the Prevention and Treatment of Visual Loss, Iowa City VA Health Care System, 601 Hwy 6 W, Iowa City, IA 52246, United States
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Loo Y, Chan ASY, Khor CC, Aung T, Wang Z. Rodent genetically modified models of glaucoma. Mol Aspects Med 2024; 95:101229. [PMID: 38039744 DOI: 10.1016/j.mam.2023.101229] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 11/11/2023] [Accepted: 11/15/2023] [Indexed: 12/03/2023]
Abstract
Glaucoma, one of the leading causes of irreversible blindness worldwide, is a complex and heterogenous disease. While environmental factors are important, it is well-recognized that the disease has a strong heritable component. With the advent of large-cohort genome wide association studies, a myriad of genetic risk loci has been linked to different forms of glaucoma. Animal models have been an indispensable tool in characterizing these loci, especially if they lie within coding regions in the genome. Not only do these models connect genotype to phenotype, advancing our understanding of glaucoma pathogenesis in the process, they also have valuable utility as a platform for the pre-clinical testing of potential therapies. In this review, we will outline genetic models used for studying the major forms of glaucoma, including primary open angle glaucoma, normal tension glaucoma, primary angle closure glaucoma, pigmentary glaucoma, pseudoexfoliation glaucoma, and early onset glaucoma, including congenital and developmental glaucoma, and how studying these models have helped shed light on human glaucoma.
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Affiliation(s)
- Yunhua Loo
- Duke-NUS Medical School, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Anita Sook Yee Chan
- Duke-NUS Medical School, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Chiea Chuen Khor
- Duke-NUS Medical School, Singapore; Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Tin Aung
- Duke-NUS Medical School, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Zhenxun Wang
- Duke-NUS Medical School, Singapore; Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
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Mueller A, Lam I, Kishor K, Lee RK, Bhattacharya S. Secondary glaucoma: Toward interventions based on molecular underpinnings. WIREs Mech Dis 2024; 16:e1628. [PMID: 37669762 DOI: 10.1002/wsbm.1628] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 08/08/2023] [Accepted: 08/10/2023] [Indexed: 09/07/2023]
Abstract
Glaucoma is a heterogeneous group of progressive diseases that leads to irreversible blindness. Secondary glaucoma refers to glaucoma caused by a known underlying condition. Pseudoexfoliation and pigment dispersion syndromes are common causes of secondary glaucoma. Their respective deposits may obstruct the trabecular meshwork, leading to aqueous humor outflow resistance, ocular hypertension, and optic neuropathy. There are no disease-specific interventions available for either. Pseudoexfoliation syndrome is characterized by fibrillar deposits (pseudoexfoliative material) on anterior segment structures. Over a decade of multiomics analyses taken together with the current knowledge on pseudoexfoliative glaucoma warrant a re-think of mechanistic possibilities. We propose that the presence of nucleation centers (e.g., vitamin D binding protein), crosslinking enzymes (e.g., transglutaminase 2), aberrant extracellular matrix, flawed endocytosis, and abnormal aqueous-blood barrier contribute to the formation of proteolytically resistant pseudoexfoliative material. Pigment dispersion syndrome is characterized by abnormal iridolenticular contact that disrupts iris pigment epithelium and liberates melanin granules. Iris melanogenesis is aberrant in this condition. Cytotoxic melanogenesis intermediates leak out of melanosomes and cause iris melanocyte and pigment epithelium cell death. Targeting melanogenesis can likely decrease the risk of pigmentary glaucoma. Skin and melanoma research provides insights into potential therapeutics. We propose that specific prostanoid agonists and fenofibrates may reduce melanogenesis by inhibiting cholesterol internalization and de novo synthesis. Additionally, melatonin is a potent melanogenesis suppressor, antioxidant, and hypotensive agent, rendering it a valuable agent for pigmentary glaucoma. In pseudoexfoliative glaucoma, where environmental insults drive pseudoexfoliative material formation, melatonin's antioxidant and hypotensive properties may offer adjunct therapeutic benefits. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Anna Mueller
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, USA
| | - Isabel Lam
- Idaho College of Osteopathic Medicine, Meridian, Idaho, USA
| | - Krishna Kishor
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Miami Integrative Metabolomics Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Richard K Lee
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Miami Integrative Metabolomics Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Sanjoy Bhattacharya
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
- Miami Integrative Metabolomics Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
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Suarez MF, Schmitt HM, Kuhn MS, Watkins T, Hake KM, Weisz T, Flynn EJ, Elliott MH, Hauser MA, Stamer WD. Genetic background determines severity of Loxl1-mediated systemic and ocular elastosis in mice. Dis Model Mech 2023; 16:dmm050392. [PMID: 37905384 PMCID: PMC10668029 DOI: 10.1242/dmm.050392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/20/2023] [Indexed: 11/02/2023] Open
Abstract
Pseudoexfoliation syndrome (PEX) is a systemic, age-related disorder characterized by elastosis and extracellular matrix deposits. Its most significant ocular manifestation is an aggressive form of glaucoma associated with variants in the gene encoding lysyl oxidase-like 1 (LOXL1). Depending upon the population, variants in LOXL1 can impart risk or protection for PEX, suggesting the importance of genetic context. As LOXL1 protein levels are lower and the degree of elastosis is higher in people with PEX, we studied Loxl1-deficient mice on three different genetic backgrounds: C57BL/6 (BL/6), 129S×C57BL/6 (50/50) and 129S. Early onset and high prevalence of spontaneous pelvic organ prolapse in BL/6 Loxl1-/- mice necessitated the study of mice that were <2 months old. Similar to pelvic organ prolapse, most elastosis endpoints were the most severe in BL/6 Loxl1-/- mice, including skin laxity, pulmonary tropoelastin accumulation, expansion of Schlemm's canal and dilation of intrascleral veins. Interestingly, intraocular pressure was elevated in 50/50 Loxl1-/- mice, depressed in BL/6 Loxl1-/- mice and unchanged in 129S Loxl1-/- mice compared to that of control littermates. Overall, the 129S background was protective against most elastosis phenotypes studied. Thus, repair of elastin-containing tissues is impacted by the abundance of LOXL1 and genetic context in young animals.
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Affiliation(s)
- Maria F. Suarez
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
| | - Heather M. Schmitt
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Megan S. Kuhn
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
| | - TeddiJo Watkins
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
| | - Kristyn M. Hake
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
| | - Tara Weisz
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
| | - Edward J. Flynn
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
| | - Michael H. Elliott
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Michael A. Hauser
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27701, USA
- Department of Medicine, Duke University, Durham, NC 27710, USA
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC 27705, USA
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Braunger BM, Gießl A, Schlötzer-Schrehardt U. The Blood-ocular Barriers and their Dysfunction: Anatomy, Physiology, Pathology. Klin Monbl Augenheilkd 2023; 240:650-661. [PMID: 37207638 DOI: 10.1055/a-2063-8957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Complex barriers comprise the blood-aqueous (BAB) and the blood-retinal barrier (BRB), and separate anterior and posterior eye chambers, vitreous body, and sensory retina from the circulation. They prevent pathogens and toxins from entering the eye, control movement of fluid, proteins, and metabolites, and contribute to the maintenance of the ocular immune status. Morphological correlates of blood-ocular barriers are tight junctions between neighboring endothelial and epithelial cells, which function as gatekeepers of the paracellular transport of molecules, thereby limiting their uncontrolled access to ocular chambers and tissues. The BAB is composed of tight junctions between endothelial cells of the iris vasculature, endothelial cells of Schlemm's canal inner wall, and cells of the nonpigmented ciliary epithelium. The BRB consists of tight junctions between endothelial cells of the retinal vessels (inner BRB) and epithelial cells of the retinal pigment epithelium (outer BRB). These junctional complexes respond rapidly to pathophysiological changes, thus enabling vascular leakage of blood-derived molecules and inflammatory cells into ocular tissues and chambers. Blood-ocular barrier function, which can be clinically measured by laser flare photometry or fluorophotometry, is compromised in traumatic, inflammatory, or infectious processes, but also frequently contributes to the pathophysiology of chronic diseases of the anterior eye segment and the retina, as exemplified by diabetic retinopathy and age-related macular degeneration.
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Affiliation(s)
- Barbara M Braunger
- Institut für Anatomie und Zellbiologie, Julius-Maximilians-Universität Würzburg, Medizinische Fakultät, Deutschland
| | - Andreas Gießl
- Augenklinik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Medizinische Fakultät, Erlangen, Deutschland
| | - Ursula Schlötzer-Schrehardt
- Augenklinik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Medizinische Fakultät, Erlangen, Deutschland
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Lysyl oxidase-like 1 deficiency alters ultrastructural and biomechanical properties of the peripapillary sclera in mice. Matrix Biol Plus 2022; 16:100120. [PMID: 36060791 PMCID: PMC9436796 DOI: 10.1016/j.mbplus.2022.100120] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 08/17/2022] [Indexed: 11/30/2022] Open
Abstract
Lysyl oxidate-like 1 knockout (Loxl1-/-) mice have decreased vision without elevated intraocular pressure. Loxl1-/- mice exhibit biometric changes of the anterior segment of the eye. Loxl1-/- mice have altered elastin and collagen structure in peripapillary sclera. Structural alternations of peripapillary sclera correlate with its increased stiffness in Loxl1-/- mice.
Lysyl oxidase-like 1 encoded by the LOXL1 gene is a member of the lysyl oxidase family of enzymes that are important in the maintenance of extracellular matrix (ECM)-rich tissue. LOXL1 is important for proper elastic fiber formation and mice lacking LOXL1 (Loxl1−/−) exhibit systemic elastic fiber disorders, such as pelvic organ prolapse, a phenotype associated with exfoliation syndrome (XFS) in humans. Patients with XFS have a significant risk of developing exfoliation glaucoma (XFG), a severe form of glaucoma, which is a neurodegenerative condition leading to irreversible blindness if not detected and treated in a timely fashion. Although Loxl1−/− mice have been used extensively to investigate mechanisms of pelvic organ prolapse, studies of eyes in those mice are limited and some showed inconsistent ocular phenotypes. In this study we demonstrate that Loxl1−/− mice have significant anterior segment biometric abnormalities which recapitulate some human XFS features. We then focused on the peripapillary sclera (PPS), a critical structure for maintaining optic nerve health. We discovered quantitative and qualitive changes in ultrastructure of PPS, such as reduced elastic fibers, enlarged collagen fibrils, and transformed collagen lamella organization detected by transmission electron microscopy (TEM). Importantly, these changes corelate with altered tissue biomechanics detected by Atomic Force Microscopy (AFM) of PPS in mice. Together, our results support a crucial role for LOXL1 in ocular tissue structure and biomechanics, and Loxl1−/− mice could be a valuable resource for understanding the role of scleral tissue biomechanics in ocular disease.
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11
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Wang Z, Wiggs JL, Aung T, Khawaja AP, Khor CC. The genetic basis for adult onset glaucoma: Recent advances and future directions. Prog Retin Eye Res 2022; 90:101066. [PMID: 35589495 DOI: 10.1016/j.preteyeres.2022.101066] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/19/2022] [Accepted: 04/23/2022] [Indexed: 11/26/2022]
Abstract
Glaucoma, a diverse group of eye disorders that results in the degeneration of retinal ganglion cells, is the world's leading cause of irreversible blindness. Apart from age and ancestry, the major risk factor for glaucoma is increased intraocular pressure (IOP). In primary open-angle glaucoma (POAG), the anterior chamber angle is open but there is resistance to aqueous outflow. In primary angle-closure glaucoma (PACG), crowding of the anterior chamber angle due to anatomical alterations impede aqueous drainage through the angle. In exfoliation syndrome and exfoliation glaucoma, deposition of white flaky material throughout the anterior chamber directly interfere with aqueous outflow. Observational studies have established that there is a strong hereditable component for glaucoma onset and progression. Indeed, a succession of genome wide association studies (GWAS) that were centered upon single nucleotide polymorphisms (SNP) have yielded more than a hundred genetic markers associated with glaucoma risk. However, a shortcoming of GWAS studies is the difficulty in identifying the actual effector genes responsible for disease pathogenesis. Building on the foundation laid by GWAS studies, research groups have recently begun to perform whole exome-sequencing to evaluate the contribution of protein-changing, coding sequence genetic variants to glaucoma risk. The adoption of this technology in both large population-based studies as well as family studies are revealing the presence of novel, protein-changing genetic variants that could enrich our understanding of the pathogenesis of glaucoma. This review will cover recent advances in the genetics of primary open-angle glaucoma, primary angle-closure glaucoma and exfoliation glaucoma, which collectively make up the vast majority of all glaucoma cases in the world today. We will discuss how recent advances in research methodology have uncovered new risk genes, and how follow up biological investigations could be undertaken in order to define how the risk encoded by a genetic sequence variant comes into play in patients. We will also hypothesise how data arising from characterising these genetic variants could be utilized to predict glaucoma risk and the manner in which new therapeutic strategies might be informed.
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Affiliation(s)
- Zhenxun Wang
- Duke-NUS Medical School, Singapore; Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
| | - Janey L Wiggs
- Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Tin Aung
- Duke-NUS Medical School, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Anthony P Khawaja
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
| | - Chiea Chuen Khor
- Duke-NUS Medical School, Singapore; Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
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Disatham J, Brennan L, Jiao X, Ma Z, Hejtmancik JF, Kantorow M. Changes in DNA methylation hallmark alterations in chromatin accessibility and gene expression for eye lens differentiation. Epigenetics Chromatin 2022; 15:8. [PMID: 35246225 PMCID: PMC8897925 DOI: 10.1186/s13072-022-00440-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 02/16/2022] [Indexed: 12/13/2022] Open
Abstract
Background Methylation at cytosines (mCG) is a well-known regulator of gene expression, but its requirements for cellular differentiation have yet to be fully elucidated. A well-studied cellular differentiation model system is the eye lens, consisting of a single anterior layer of epithelial cells that migrate laterally and differentiate into a core of fiber cells. Here, we explore the genome-wide relationships between mCG methylation, chromatin accessibility and gene expression during differentiation of eye lens epithelial cells into fiber cells. Results Whole genome bisulfite sequencing identified 7621 genomic loci exhibiting significant differences in mCG levels between lens epithelial and fiber cells. Changes in mCG levels were inversely correlated with the differentiation state-specific expression of 1285 genes preferentially expressed in either lens fiber or lens epithelial cells (Pearson correlation r = − 0.37, p < 1 × 10–42). mCG levels were inversely correlated with chromatin accessibility determined by assay for transposase-accessible sequencing (ATAC-seq) (Pearson correlation r = − 0.86, p < 1 × 10–300). Many of the genes exhibiting altered regions of DNA methylation, chromatin accessibility and gene expression levels in fiber cells relative to epithelial cells are associated with lens fiber cell structure, homeostasis and transparency. These include lens crystallins (CRYBA4, CRYBB1, CRYGN, CRYBB2), lens beaded filament proteins (BFSP1, BFSP2), transcription factors (HSF4, SOX2, HIF1A), and Notch signaling pathway members (NOTCH1, NOTCH2, HEY1, HES5). Analysis of regions exhibiting cell-type specific alterations in DNA methylation revealed an overrepresentation of consensus sequences of multiple transcription factors known to play key roles in lens cell differentiation including HIF1A, SOX2, and the MAF family of transcription factors. Conclusions Collectively, these results link DNA methylation with control of chromatin accessibility and gene expression changes required for eye lens differentiation. The results also point to a role for DNA methylation in the regulation of transcription factors previously identified to be important for lens cell differentiation. Supplementary Information The online version contains supplementary material available at 10.1186/s13072-022-00440-z.
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Affiliation(s)
- Joshua Disatham
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Lisa Brennan
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Xiaodong Jiao
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Zhiwei Ma
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - J Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Marc Kantorow
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA.
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13
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Chakraborty M, Rao A. Alternate Causes for Pathogenesis of Exfoliation Glaucoma, a Multifactorial Elastotic Disorder: A Literature Review. Curr Issues Mol Biol 2022; 44:1191-1202. [PMID: 35723301 PMCID: PMC8946964 DOI: 10.3390/cimb44030078] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 02/17/2022] [Accepted: 02/19/2022] [Indexed: 12/27/2022] Open
Abstract
Exfoliation glaucoma (XFG) is the most recognizable form of secondary open-angle glaucoma associated with a high risk of blindness. This disease is characterized by white flaky granular deposits in the anterior chamber that leads to the elevation of intraocular pressure (IOP) and subsequent glaucomatous optic nerve damage. Conventionally, XFG is known to respond poorly to medical therapy, and surgical intervention is the only management option in most cases. Various genetic and nongenetic factors are known to be linked to the development of XFG. Despite decades of research on the genetic factors in exfoliation syndrome (XFS) by study groups and global consortia involving different ethnic populations, the pathogenesis of XFS and the mechanism of onset of glaucoma still remains an unsolved mystery. The key lies in understanding how the function of a gene (or set of genes) is altered by environmental triggers, along with other molecular events that underlie the key disease attributes, namely, oxidative stress and the disruption of the blood–aqueous barrier (BAB). It remains a challenge to evolve a theory encompassing all factions of molecular events occurring independently or parallelly that determine the disease manifestation (phenotype) or the stage of the disease in the eye (or in any tissue) in exfoliation. Our enhanced understanding of the underlying molecular pathophysiology of XFG, beyond the known genes or polymorphisms involved in the disease, will lead to improved diagnosis and management and the ability to recognize how the environment influences these key events that lead to the disease phenotype or disease progression. This review summarizes the recent observations and discoveries of four key factors that may hold the answers to the non-lysyl oxidase-like 1 (LOXL1) mechanisms behind XFG pathogenesis, namely, the epigenetic factor miRNA, disordered autophagy along with the potential involvement of mitochondrial mutations, and a compromised aqueous–blood barrier.
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Affiliation(s)
- Munmun Chakraborty
- Hyderabad Eye Research Foundation (HERF), L.V. Prasad Eye Institute, Bhubaneswar 751024, Odisha, India;
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India
| | - Aparna Rao
- Hyderabad Eye Research Foundation (HERF), L.V. Prasad Eye Institute, Bhubaneswar 751024, Odisha, India;
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India
- Correspondence:
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14
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Aboobakar IF, Wiggs JL. The genetics of glaucoma: Disease associations, personalised risk assessment and therapeutic opportunities-A review. Clin Exp Ophthalmol 2022; 50:143-162. [PMID: 35037362 DOI: 10.1111/ceo.14035] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 12/23/2022]
Abstract
Glaucoma refers to a heterogenous group of disorders characterised by progressive loss of retinal ganglion cells and associated visual field loss. Both early-onset and adult-onset forms of the disease have a strong genetic component. Here, we summarise the known genetic associations for various forms of glaucoma and the possible functional roles for these genes in disease pathogenesis. We also discuss efforts to translate genetic knowledge into clinical practice, including gene-based tests for disease diagnosis and risk-stratification as well as gene-based therapies.
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Affiliation(s)
- Inas F Aboobakar
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, USA
| | - Janey L Wiggs
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, USA
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15
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Zhang M, Sun S, Wang L, Wang X, Chen T, Chen Z, Jiang Y. Zonular defects in loxl1-deficient zebrafish. Clin Exp Ophthalmol 2021; 50:62-73. [PMID: 34585825 DOI: 10.1111/ceo.14017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/17/2021] [Accepted: 09/25/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND To investigate the roles of the lysyl oxidase-like 1 (loxl1) gene in zebrafish eye development and the potency of loxl1 deficiency in mimicking the ocular manifestations of exfoliation syndrome (XFS). METHODS CRISPR/Cas9 technology was used to generate a frameshift coding deletion in zebrafish loxl1. Expression profiles and ocular manifestations of the wildtype, heterozygous mutant (loxl1+/- ) and homozygous mutant (loxl1-/- ) zebrafish were analysed in a range of developmental stages from zebrafish larvae to dissected adult zebrafish eyes. RESULTS The loxl1 deficiency caused zonular bundling disorders in juvenile zebrafish and accumulation of pearl-like particles adhering to the adult zebrafish zonule. The bundles appeared to lack form and were thinner in both loxl1+/- and loxl1-/- zebrafish compared with the wildtype (p < 0.01 for all Bonferroni post-hoc analyses). The zonule of loxl1-/- zebrafish appeared stretched, ragged and torn, with isolated fibres also detected. The particles in loxl1-/- zebrafish were more numerous (counts: 92.33 ± 10.02/100 μm2 vs. 58.33 ± 5.03/100 μm2 , p = 0.006), but smaller in size (diameter: 0.21 ± 0.03 μm vs. 0.43 ± 0.04 μm, p = 0.002) compared with those in loxl1+/- . Transmission electron microscopy revealed thinning or even loss of elastic lamina in loxl1+/- Bruch's membrane (BM) (thickness of elastic lamina: 92.94 ± 18.19 nm in the wildtype vs 35.65 ± 14.76 nm in loxl1+/- , p = 0.003). The breakage of BM was observed in loxl1-/- . CONCLUSIONS The loxl1-/- zebrafish is a promising animal model of XFS zonular pathology.
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Affiliation(s)
- Min Zhang
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.,Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shaoyang Sun
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Lei Wang
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xu Wang
- Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Tianhui Chen
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Zexu Chen
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Yongxiang Jiang
- Department of Ophthalmology and Vision Science, Eye & ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
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16
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Seese SE, Deml B, Muheisen S, Sorokina E, Semina EV. Genetic disruption of zebrafish mab21l1 reveals a conserved role in eye development and affected pathways. Dev Dyn 2021; 250:1056-1073. [PMID: 33570754 PMCID: PMC8349561 DOI: 10.1002/dvdy.312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The male-abnormal 21 like (MAB21L) genes are important in human ocular development. Homozygous loss of MAB21L1 leads to corneal dystrophy in all affected individuals along with cataracts and buphthalmos in some. The molecular function and downstream pathways of MAB21L factors are largely undefined. RESULTS We generated the first mab21l1 zebrafish mutant carrying a putative loss-of-function allele, c.107delA p.(Lys36Argfs*7). At the final stages of embryonic development, homozygous mab21l1c.107delA fish displayed enlarged anterior chambers and corneal thinning which progressed with age. Additional studies revealed increased cell death in the mutant corneas, transformation of the cornea into a skin-like epithelium, and progressive lens degeneration with development of fibrous masses in the anterior chamber. RNA-seq of wild-type and mutant ocular transcriptomes revealed significant changes in expression of several genes, including irf1a and b, stat1, elf3, krt17, tlr9, and loxa associated with immunity and/or corneal function. Abnormal expression of lysyl oxidases have been previously linked with corneal thinning, fibrosis, and lens defects in mammals, suggesting a role for loxa misexpression in the progressive mab21l1c.107delA eye phenotype. CONCLUSIONS Zebrafish mab21l1 is essential for normal corneal development, similar to human MAB21L1. The identified molecular changes in mab21l1c.107delA mutants provide the first clues about possible affected pathways.
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Affiliation(s)
- Sarah E. Seese
- Department of Pediatrics, The Medical College of Wisconsin, Milwaukee, Wisconsin
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Brett Deml
- Department of Pediatrics, The Medical College of Wisconsin, Milwaukee, Wisconsin
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin
- PreventionGenetics, Marshfield, Wisconsin
| | - Sanaa Muheisen
- Department of Pediatrics, The Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Elena Sorokina
- Department of Pediatrics, The Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Elena V. Semina
- Department of Pediatrics, The Medical College of Wisconsin, Milwaukee, Wisconsin
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Children's of Wisconsin, Milwaukee, Wisconsin
- Children's Research Institute, Medical College of Wisconsin, Children's of Wisconsin, Milwaukee, Wisconsin
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17
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A Comparison of Genomic Advances in Exfoliation Syndrome and Primary Open-Angle Glaucoma. CURRENT OPHTHALMOLOGY REPORTS 2021. [DOI: 10.1007/s40135-021-00270-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Abstract
PURPOSE OF REVIEW The genetic basis of pseudoexfoliation (PEX) syndrome, the most common identifiable cause of open-angle glaucoma, is steadily being elucidated. This review summarizes the recent advances on genetic risk factors for PEX syndrome/glaucoma and their potential functional implications in PEX pathophysiology. RECENT FINDINGS As of today, seven loci associated with the risk of PEX surpassing genome-wide significance have been identified by well-powered genome-wide association studies and sequencing efforts. LOXL1 (lysyl oxidase-like 1) represents the major genetic effect locus, although the biological role of common risk variants and their reversed effect in different ethnicities remain an unresolved problem. Rare protein-coding variants at LOXL1 and a single noncoding variant downstream of LOXL1 showed no allele effect reversal and suggested potential roles for elastin homeostasis and vitamin A metabolism in PEX pathogenesis. Other PEX-associated genetic variants provided biological insights into additional disease processes and pathways, including ubiquitin-proteasome function, calcium signaling, and lipid biosynthesis. Gene-environment interactions, epigenetic alterations, and integration of multiomics data have further contributed to our knowledge of the complex etiology underlying PEX syndrome and glaucoma. SUMMARY PEX-associated genes are beginning to reveal relevant biological pathways and processes involved in disease development. To understand the functional consequences and molecular mechanisms of these loci and to translate them into novel therapeutic approaches are the major challenges for the future.
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19
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Li G, Schmitt H, Johnson WM, Lee C, Navarro I, Cui J, Fleming T, Gomez-Caraballo M, Elliott MH, Sherwood JM, Hauser MA, Farsiu S, Ethier CR, Stamer WD. Integral role for lysyl oxidase-like-1 in conventional outflow tissue function and behavior. FASEB J 2020; 34:10762-10777. [PMID: 32623782 DOI: 10.1096/fj.202000702rr] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 12/15/2022]
Abstract
Lysyl oxidase-like-1 (LOXL1), a vital crosslinking enzyme in elastin fiber maintenance, is essential for the stability and strength of elastic vessels and tissues. Variants in the LOXL1 locus associate with a dramatic increase in risk of exfoliation syndrome (XFS), a systemic fibrillopathy, which often presents with ocular hypertension and exfoliation glaucoma (XFG). We examined the role of LOXL1 in conventional outflow function, the prime regulator of intraocular pressure (IOP). Using Loxl1-/- , Loxl1+/- , and Loxl1+/+ mice, we observed an inverse relationship between LOXL1 expression and IOP, which worsened with age. Elevated IOP in Loxl1-/- mice was associated with a larger globe, decreased ocular compliance, increased outflow facility, extracellular matrix (ECM) abnormalities, and dilated intrascleral veins, yet, no dilation of arteries or capillaries. Interestingly, in living Loxl1-/- mouse eyes, Schlemm's canal (SC) was less susceptible to collapse when challenged with acute elevations in IOP, suggesting elevated episcleral venous pressure (EVP). Thus, LOXL1 expression is required for normal IOP control, while ablation results in altered ECM repair/homeostasis and conventional outflow physiology. Dilation of SC and distal veins, but not arteries, is consistent with key structural and functional roles for elastin in low-pressure vessels subjected to cyclical mechanical stress.
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Affiliation(s)
- Guorong Li
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | - Heather Schmitt
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | | | - Chanyoung Lee
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA, USA
| | - Iris Navarro
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | - Jenny Cui
- East Chapel Hill School, Chapel Hill, NC, USA
| | - Todd Fleming
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | | | - Michael H Elliott
- Department of Ophthalmology and Physiology, University of Oklahoma Health, Oklahoma City, OK, USA
| | | | - Michael A Hauser
- Department of Ophthalmology, Duke University, Durham, NC, USA.,Molecular Physiology Institute, Duke University, Durham, NC, USA
| | - Sina Farsiu
- Department of Ophthalmology, Duke University, Durham, NC, USA.,Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - C Ross Ethier
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, GA, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA.,Department of Biomedical Engineering, Duke University, Durham, NC, USA
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20
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Associations of polymorphisms in LOXL1 and copper chaperone genes with pseudoexfoliation-syndrome-related cataract in a Chinese Uygur population. Int Ophthalmol 2020; 40:1841-1848. [DOI: 10.1007/s10792-020-01354-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/24/2020] [Indexed: 10/24/2022]
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21
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Abstract
Animal models are powerful tools for studying diseases that affect the eye, such as exfoliation syndrome (XFS). Two types of animal models have been used to investigate the pathophysiology of XFS and glaucoma. One class of models is engineered to have key features of a disease by alteration of their genome (genotype-driven animal models). LOXL1 is the first gene known to increase the risk for developing XFS in humans. Two transgenic mouse models with altered Loxl1 genes have been generated to study XFS. One strain of mice, Loxl1 deficient mice, also known as Loxl1 knockout mice, have had the Loxl1 gene removed from their genomes. Another strain has been engineered to produce excess amounts of the protein produced by the Loxl1 gene, or Loxl1 overexpression. A second class of animal models includes naturally occurring strains of mice that exhibit key clinical features of a disease. Studies of these phenotype-driven animal models may identify genes that cause disease and may also provide a valuable resource for investigating pathogenesis. One strain of mice, B6-Lyst, has several key features of human XFS, including ocular production of exfoliation-like material, and stereotypical iris abnormalities. Studies of this range of mice and other public mouse genetic resources have provided some important insights into the biology of XFS and may be useful for future studies to test the efficacy of drug therapies.
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22
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Schlötzer-Schrehardt U, Zenkel M. The role of lysyl oxidase-like 1 (LOXL1) in exfoliation syndrome and glaucoma. Exp Eye Res 2019; 189:107818. [PMID: 31563608 DOI: 10.1016/j.exer.2019.107818] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 12/27/2022]
Abstract
Exfoliation syndrome (XFS) is an age-related systemic disease that affects the extracellular matrix. It increases the risk of glaucoma (exfoliation glaucoma, XFG) and susceptibility to diseases of elastin-rich connective tissues. LOXL1 (lysyl oxidase-like 1) is still recognized as the major genetic effect locus in XFS and XFG in all populations worldwide, although its genetic architecture is incompletely understood. LOXL1 is a key cross-linking enzyme in elastic fiber formation and remodeling, which is compatible with the pathogenetic concept of XFS as a specific type of elastosis. This review provides an overview on the current knowledge about the role of LOXL1 in the etiology and pathophysiology of XFS and XFG. It covers the known genetic associations at the LOXL1 locus, potential mechanisms of gene regulation, implications of LOXL1 in XFS-associated fibrosis and connective tissue homeostasis, its role in the development of glaucoma and associated systemic diseases, and the currently available LOXL1-based in vivo and in vitro models. Finally, it also identifies gaps in knowledge and suggests potential areas for future research.
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Affiliation(s)
| | - Matthias Zenkel
- Department of Ophthalmology, University of Erlangen-Nürnberg, Schwabachanlage 6, 91054, Erlangen, Germany
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23
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Zadravec P, Braunger BM, Melzer B, Kroeber M, Bösl MR, Jägle H, Schlötzer-Schrehardt U, Tamm ER. Transgenic lysyl oxidase homolog 1 overexpression in the mouse eye results in the formation and release of protein aggregates. Exp Eye Res 2019; 179:115-124. [DOI: 10.1016/j.exer.2018.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/31/2018] [Accepted: 11/01/2018] [Indexed: 01/08/2023]
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24
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Yelenskiy A, Ko MK, Chu ER, Gonzalez JM, Siegmund K, Tan JC. Total Outflow Facility in Live C57BL/6 Mice of Different Age. Biomed Hub 2017; 2:1-10. [PMID: 31988919 PMCID: PMC6945946 DOI: 10.1159/000484126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/08/2017] [Indexed: 01/12/2023] Open
Abstract
Purpose To characterize total outflow facility across the live adult mouse lifespan as a reference for mouse glaucoma studies and the common C57BL/6 background strain. Methods Microperfusion was performed by single-needle cannulation and feedback-controlled coupling of pressure and flow to maintain a constant pressure in the anterior chambers of live C57BL/6NCrl mice aged 3-4 months (n = 17), 6-9 months (n = 10), and 23-27 months (n = 12). This mouse age range represented an equivalent human age range of young adult to elderly. We characterized the following across age groups in vivo: (1) outflow facility based on constant pressure perfusion in a pressure range of 15-35 mm Hg, (2) perfusion flow rates, and (3) anterior segment tissue histology after perfusion. Thirty-nine live mice underwent perfusion. Results Pressure-flow rate functions were consistently linear for all age groups (all R 2 > 0.96). Total outflow facility in mice aged 3-4, 6-9, and 23-27 months was 0.0066, 0.0064, and 0.0077 μL/min/mm Hg, respectively. Facility was not significantly different between age groups (all p > 0.4). The groups had closely overlapping frequency distribution profiles with right-sided tails. Post hoc estimates indicated that group facility differences of at least 50% would have been detectable, with this limit set mainly by inherent variability in the strain. A trend toward higher perfusion flow rates was seen in older mice aged 23-27 months, but this was not significantly different from that of mice aged 3-4 months or 6-9 months (p > 0.2). No histological disruption or difference in iridocorneal angle or drainage tissue structure was seen following perfusion in the different age groups. Conclusion We did not find a significant difference in total outflow facility between different age groups across the live C57BL/6 mouse adult lifespan, agreeing with some human studies. The possibility that more subtle differences might exist ought to be judged with respect to the heterogeneity in facility at different ages. Our findings provide reference data for live perfusion studies pertaining to glaucoma involving the C57BL/6 strain.
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Affiliation(s)
- Aleksandr Yelenskiy
- Doheny Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA.,Tulane University Department of Ophthalmology, Tulane University School of Medicine, Tulane University, New Orleans, LA, USA
| | - MinHee K Ko
- Doheny Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Edward R Chu
- Doheny Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jose M Gonzalez
- Doheny Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kimberly Siegmund
- Department of Preventive Medicine, University of Southern California, Los Angeles, CA, USA
| | - James C Tan
- Doheny Eye Institute and Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA
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25
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Nailfold capillary morphology in exfoliation syndrome. Eye (Lond) 2017; 31:698-707. [PMID: 28085140 DOI: 10.1038/eye.2016.312] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/26/2016] [Indexed: 02/08/2023] Open
Abstract
PurposeThe purpose of the study was to investigate nailfold microvascular morphology in exfoliation syndrome with or without glaucoma (XFS/XFG) compared with primary open-angle glaucoma (POAG) and control subjects using nailfold capillary videomicroscopy.Patients and methodsWe used a JH-1004 capillaroscope to perform nailfold capillary videomicroscopy on the fourth and fifth digit of the non-dominant hand. We enrolled 56 XFS/XFG patients, 87 POAG patients, and 75 control subjects. Masked observers graded the videos for hemorrhages, avascular zones ≥200 microns (μm), and degree of microvascular tortuosity on a four-point subjective scale. Multivariable odds ratios, 95% confidence intervals and P-for trends for assessing the relation between morphological changes and POAG or XFS/XFG were obtained from logistic regression analyses. We also assessed this relation with XFS/XFG compared with POAG in multivariable models.ResultsAfter adjusting for multiple covariates, nailfold hemorrhages, avascular zones ≥200 μm, and higher degree of vascular tortuosity were more common in XFS/XFG vs controls (P-for trend ≤0.0001) and in POAG vs controls (P-for trend ≤0.01). For each 100 capillaries, the number of hemorrhages was similar (P-for trend=0.91) between XFS/XFG and POAG patients; however, there were more avascular zones per 100 capillaries with borderline significance (P-for trend=0.04) in the XFS/XFG group. XFS/XFG patients had more tortuosity than POAG patients; specifically, having a tortuosity score ≥1.5 was associated with a 4.4-fold increased odds of XFS/XFG (95% confidence interval: 1.5-13.3) relative to a tortuosity score <1.0 (P-for trend=0.005).ConclusionA high degree of nailfold capillary tortuosity is a distinct non-ocular feature associated with XFS/XFG compared with either POAG or controls.
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26
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Aboobakar IF, Johnson WM, Stamer WD, Hauser MA, Allingham RR. Major review: Exfoliation syndrome; advances in disease genetics, molecular biology, and epidemiology. Exp Eye Res 2016; 154:88-103. [PMID: 27845061 DOI: 10.1016/j.exer.2016.11.011] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/06/2016] [Accepted: 11/10/2016] [Indexed: 12/20/2022]
Abstract
Exfoliation syndrome (XFS) is a common age-related disorder that leads to deposition of extracellular fibrillar material throughout the body. The most recognized disease manifestation is exfoliation glaucoma (XFG), which is a common cause of blindness worldwide. Recent developments in XFS genetics, cell biology and epidemiology have greatly improved our understanding of the etiology of this complex inherited disease. This review summarizes current knowledge of XFS pathogenesis, identifies gaps in knowledge, and discusses areas for future research.
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Affiliation(s)
- Inas F Aboobakar
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
| | - William M Johnson
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
| | - Michael A Hauser
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
| | - R Rand Allingham
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA.
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Pasquale LR, Borrás T, Fingert JH, Wiggs JL, Ritch R. Exfoliation syndrome: assembling the puzzle pieces. Acta Ophthalmol 2016; 94:e505-12. [PMID: 26648185 DOI: 10.1111/aos.12918] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 09/25/2015] [Indexed: 12/15/2022]
Abstract
PURPOSE To summarize various topics and the cutting edge approaches to refine XFS pathogenesis that were discussed at the 21st annual Glaucoma Foundation Think Tank meeting in New York City, Sept. 19-20, 2014. METHODS The highlights of three categories of talks on cutting edge research in the field were summarized. RESULTS Exfoliation syndrome (XFS) is a systemic disorder with a substantial ocular burden, including high rates of cataract, cataract surgery complications, glaucoma and retinal vein occlusion. New information about XFS is akin to puzzle pieces that do not quite join together to reveal a clear picture regarding how exfoliation material (XFM) forms. CONCLUSION Meeting participants concluded that it is unclear how the mild homocysteinemia seen in XFS might contribute to the disarrayed extracellular aggregates characteristic of this syndrome. Lysyl oxidase-like 1 (LOXL1) variants are unequivocally genetic risk factors for XFS but exactly how these variants contribute to the assembly of exfoliation material (XFM) remains unclear. Variants in a new genomic region, CACNA1A associated with XFS, may alter calcium concentrations at the cell surface and facilitate XFM formation but much more work is needed before we can place this new finding in proper context. It is hoped that various animal model and ex vivo systems will emerge that will allow for proper assembly of the puzzle pieces into a coherent picture of XFS pathogenesis. A clear understanding of XFS pathogenesis may lead to 'upstream solutions' to reduce the ocular morbidity produced by XFS.
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Affiliation(s)
- Louis R. Pasquale
- Department of Ophthalmology; Mass Eye & Ear Infirmary; Harvard Medical School; Boston Massachusetts USA
- Department of Medicine; Harvard Medical School; Brigham and Women's Hospital; Boston Massachusetts USA
| | - Terete Borrás
- Department of Ophthalmology; University of North Carolina; Chapel Hill North Carolina USA
| | - John H. Fingert
- Department of Ophthalmology and Visual Sciences; University of Iowa; Iowa City Iowa USA
| | - Janey L. Wiggs
- Department of Ophthalmology; Mass Eye & Ear Infirmary; Harvard Medical School; Boston Massachusetts USA
| | - Robert Ritch
- Einhorn Clinical Research Center; New York Eye and Ear Infirmary of Mount Sinai; New York City New York USA
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Trackman PC. Lysyl Oxidase Isoforms and Potential Therapeutic Opportunities for Fibrosis and Cancer. Expert Opin Ther Targets 2016; 20:935-45. [PMID: 26848785 DOI: 10.1517/14728222.2016.1151003] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The lysyl oxidase family of enzymes is classically known as being required for connective tissue maturation by oxidizing lysine residues in elastin and lysine and hydroxylysine residues in collagen precursors. The resulting aldehydes then participate in cross-link formation, which is required for normal connective tissue integrity. These enzymes have biological functions that extend beyond this fundamental biosynthetic role, with contributions to angiogenesis, cell proliferation, and cell differentiation. Dysregulation of lysyl oxidases occurs in multiple pathologies including fibrosis, primary and metastatic cancers, and complications of diabetes in a variety of tissues. AREAS COVERED This review summarizes the major findings of novel roles for lysyl oxidases in pathologies, and highlights some of the potential therapeutic approaches that are in development and which stem from these new findings. EXPERT OPINION Fundamental questions remain regarding the mechanisms of novel biological functions of this family of proteins, and regarding functions that are independent of their catalytic enzyme activity. However, progress is underway in the development of isoform-specific pharmacologic inhibitors, potential therapeutic antibodies and gaining an increased understanding of both tumor suppressor and metastasis promotion activities. Ultimately, this is likely to lead to novel therapeutic agents.
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Affiliation(s)
- Philip C Trackman
- a Department of Molecular and Cell Biology , Boston University, Henry M. Goldman School of Dental Medicine , Boston , MA , USA
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Álvarez L, García M, González-Iglesias H, Escribano J, Rodríguez-Calvo PP, Fernández-Vega L, Coca-Prados M. LOXL1 gene variants and their association with pseudoexfoliation glaucoma (XFG) in Spanish patients. BMC MEDICAL GENETICS 2015; 16:72. [PMID: 26319397 PMCID: PMC4593192 DOI: 10.1186/s12881-015-0221-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 08/20/2015] [Indexed: 12/04/2022]
Abstract
Background LOXL1 gene is the most important genetic risk factor known so far for pseudoexfoliation glaucoma (XFG). Our purpose was to evaluate the potential association of individual genetic variants of the lysyl oxidase-like 1 (LOXL1) gene and haplotypes with XFG in Spanish patients. Methods Blood samples were collected from a total of 105 Spanish patients with XFG and 200 healthy controls. The entire LOXL1 gene along with the promoter, coding and non-coding regions including the 5´- and 3´-untranslated regions, were sequenced using next-generation sequencing in 99 XFG patients. SNPs rs16958477 (promoter), rs1048661 (exon 1), rs3825942 (exon 1), rs2165241 (intron 1) and rs3522 (exon 7) in LOXL1 were genotyped by restriction fragment-length polymorphism (RFLP) in all Spanish control participants and in six additional XFG patients, and a case–control association study was performed. Comparisons of the allelic and genotypic frequencies were performed using standard χ2 test with Bonferroni and Pearson corrections. Logistic regression analyses were permormed using Sigmaplot v11. Haplotypes frequencies were performed using HaploView 4.0. Results Sequencing of the LOXL1 gene in XFG participants identified a total of 212 SNPs, of which 49 exhibited allelic frequencies with significant differences between cases and controls, and 66 were not previously described. The allele frequencies of SNPs rs16958477, rs1048661, rs3825942, rs2165241, were significantly associated with an increased risk for XFG, however the SNP rs3522 was not. The haplotype frequencies of SNPs rs16958477, rs1048661, rs3825942 and rs2165241 and their association with XFG indicated that the CGGT haplotype, containing all four risk alleles, and the AGGT haplotype, which carries the protective allele of rs16958477 and three risk alleles of the other three SNPs, were significantly associated with XFG (p = 4.5×10−6, and p = 8.8×10−6), conferring more than 2-fold increased disease susceptibility. Conclusions SNPs of the LOXL1 gene are associated with XFG in the Spanish population. This information adds new support to the distinct risk association frequencies of LOXL1 alleles with XFG in Western European and Asian populations. Identification and validation of additional SNPs along the entire LOXL1 gene of XFG cases may provide insightful information on their potential role in the pathogenesis of this disease. Electronic supplementary material The online version of this article (doi:10.1186/s12881-015-0221-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lydia Álvarez
- Fundación de Investigación Oftalmológica, Instituto Oftalmológico Fernández-Vega, Avenida Doctores Fernández-Vega, 34, Oviedo, 33012, Spain.
| | - Montserrat García
- Fundación de Investigación Oftalmológica, Instituto Oftalmológico Fernández-Vega, Avenida Doctores Fernández-Vega, 34, Oviedo, 33012, Spain.
| | - Héctor González-Iglesias
- Fundación de Investigación Oftalmológica, Instituto Oftalmológico Fernández-Vega, Avenida Doctores Fernández-Vega, 34, Oviedo, 33012, Spain.
| | - Julio Escribano
- Laboratorio de Genética Molecular Humana, Facultad de Medicina/Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, Albacete, 02006, Spain.
| | - Pedro P Rodríguez-Calvo
- Fundación de Investigación Oftalmológica, Instituto Oftalmológico Fernández-Vega, Avenida Doctores Fernández-Vega, 34, Oviedo, 33012, Spain.
| | - Luis Fernández-Vega
- Fundación de Investigación Oftalmológica, Instituto Oftalmológico Fernández-Vega, Avenida Doctores Fernández-Vega, 34, Oviedo, 33012, Spain.
| | - Miguel Coca-Prados
- Fundación de Investigación Oftalmológica, Instituto Oftalmológico Fernández-Vega, Avenida Doctores Fernández-Vega, 34, Oviedo, 33012, Spain. .,Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT, 06510, USA.
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Wiggs JL. Glaucoma Genes and Mechanisms. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 134:315-42. [PMID: 26310163 DOI: 10.1016/bs.pmbts.2015.04.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genetic studies have yielded important genes contributing to both early-onset and adult-onset forms of glaucoma. The proteins encoded by the current collection of glaucoma genes participate in a broad range of cellular processes and biological systems. Approximately half the glaucoma-related genes function in the extracellular matrix, however proteins involved in cytokine signaling, lipid metabolism, membrane biology, regulation of cell division, autophagy, and ocular development also contribute to the disease pathogenesis. While the function of these proteins in health and disease are not completely understood, recent studies are providing insight into underlying disease mechanisms, a critical step toward the development of gene-based therapies. In this review, genes known to cause early-onset glaucoma or contribute to adult-onset glaucoma are organized according to the cell processes or biological systems that are impacted by the function of the disease-related protein product.
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Affiliation(s)
- Janey L Wiggs
- Harvard Medical School, and Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA.
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Vranka JA, Kelley MJ, Acott TS, Keller KE. Extracellular matrix in the trabecular meshwork: intraocular pressure regulation and dysregulation in glaucoma. Exp Eye Res 2015; 133:112-25. [PMID: 25819459 DOI: 10.1016/j.exer.2014.07.014] [Citation(s) in RCA: 266] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/14/2014] [Accepted: 07/16/2014] [Indexed: 12/30/2022]
Abstract
The trabecular meshwork (TM) is located in the anterior segment of the eye and is responsible for regulating the outflow of aqueous humor. Increased resistance to aqueous outflow causes intraocular pressure to increase, which is the primary risk factor for glaucoma. TM cells reside on a series of fenestrated beams and sheets through which the aqueous humor flows to exit the anterior chamber via Schlemm's canal. The outer trabecular cells are phagocytic and are thought to function as a pre-filter. However, most of the outflow resistance is thought to be from the extracellular matrix (ECM) of the juxtacanalicular region, the deepest portion of the TM, and from the inner wall basement membrane of Schlemm's canal. It is becoming increasingly evident that the extracellular milieu is important in maintaining the integrity of the TM. In glaucoma, not only have ultrastructural changes been observed in the ECM of the TM, and a significant number of mutations in ECM genes been noted, but the stiffness of glaucomatous TM appears to be greater than that of normal tissue. Additionally, TGFβ2 has been found to be elevated in the aqueous humor of glaucoma patients and is assumed to be involved in ECM changes deep with the juxtacanalicular region of the TM. This review summarizes the current literature on trabecular ECM as well as the development and function of the TM. Animal models and organ culture models targeting specific ECM molecules to investigate the mechanisms of glaucoma are described. Finally, the growing number of mutations that have been identified in ECM genes and genes that modulate ECM in humans with glaucoma are documented.
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Affiliation(s)
- Janice A Vranka
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Mary J Kelley
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ted S Acott
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Kate E Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, OR 97239, USA.
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Expression and regulation of LOXL1 and elastin-related genes in eyes with exfoliation syndrome. J Glaucoma 2015; 23:S62-3. [PMID: 25275910 DOI: 10.1097/ijg.0000000000000124] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Variants in LOXL1 are significantly associated with exfoliation syndrome (XFS), however the impact of the associated variants on disease development is not yet understood. Initially the associated missense changes, R141L and G153D, were considered to be pathogenic alleles. Flipping of the risk allele in certain populations for both missense variants provided strong evidence that these missense changes are not biologically significant and suggest that other LOXL1 variant(s), in linkage disequilibrium with these missense variants, predispose to exfoliation syndrome by affecting gene expression or protein function. Several lines of evidence support dysregulation of LOXL1 gene expression as a contributing factor to disease development. First, in the German population the R141L (rs1048661) risk allele reduced LOXL1 expression by 20%. Second, haplotype analysis identified a risk haplotype that includes including R141L, G153D, as well as a LOXL1 promoter region variant previously shown to reduce gene expression (rs16958477). Third, the LOXL1 risk haplotype influences gene expression induced by disease-associated factors TGF-B1, oxidative stress, UV light and hypoxia. Finally, a LOXL1 null mouse has some features of XFS suggesting that decreased enzyme activity contributes to predisposition to the disease. Collectively, these results suggest that dysregulation of LOXL1 expression is a contributing factor to exfoliation disease development.
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Abstract
The blood-aqueous barrier of the eye is composed by tight junctions in the ciliary process nonpigmented epithelium, the endothelial cells in the iris vasculature, and the inner wall endothelium of Schlemm's canal. Tight junctions are gatekeepers of the paracellular transport limiting the selective diffusion of ions and small solutes through the space between neighboring cells. Tight junctions (ie, junctional adhesion molecules, claudins, occludins, zonula occludens, cingulin) are part of the apical junctional complex that also includes the adherens junctions (ie, cadherin-catenin and nectin-afadin complexes) and the gap junctions (ie, connexins). These junctional complexes respond rapidly to pharmacologic agents and physiological changes. Barrier dysfunction can contribute to the pathophysiology of inflammatory ocular diseases in a passive way by the vascular leakage of blood-borne molecules and inflammatory cells into the anterior segment of the eye.
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Abstract
At present, no animal models fully embody exfoliation syndrome or exfoliation glaucoma. Both genetic and environmental factors appear critical for disease manifestation, and both must be considered when generating animal models. Because mice provide a powerful mammalian platform for modeling complex disease, this paper focuses on mouse models of exfoliation syndrome and exfoliation glaucoma.
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Manthey AL, Terrell AM, Lachke SA, Polson SW, Duncan MK. Development of novel filtering criteria to analyze RNA-sequencing data obtained from the murine ocular lens during embryogenesis. GENOMICS DATA 2014; 2:369-374. [PMID: 25478318 PMCID: PMC4248573 DOI: 10.1016/j.gdata.2014.10.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Next-generation sequencing of the transcriptome (RNA-Seq) is a powerful method that allows for the quantitative determination of absolute gene expression, and can be used to investigate how these levels change in response to an experimental manipulation or disease condition. The sensitivity of this method allows one to analyze transcript levels of all expressed genes, including low abundance transcripts that encode important regulatory molecules, providing valuable insights into the global effects of experimental manipulations. However, this increased sensitivity can also make it challenging to ascertain which expression changes are biologically significant. Here, we describe a novel set of filtering criteria - based on biological insights and computational approaches - that were applied to prioritize genes for further study from an extensive number of differentially expressed transcripts in lenses lacking Smad interacting protein 1 (Sip1) obtained via RNA-Seq by Manthey and colleagues in Mechanisms of Development (Manthey et al., 2014). Notably, this workflow allowed an original list of over 7,100 statistically significant differentially expressed genes (DEGs) to be winnowed down to 190 DEGs that likely play a biologically significant role in Sip1 function during lens development. Focusing on genes whose expression was upregulated or downregulated in a manner opposite to what normally occurs during lens development, we identified 78 genes that appear to be strongly dependent on Sip1 function. From these data (GEO accession number GSE49949), it appears that Sip1 regulates multiple genes in the lens that are generally distinct from those regulated by Sip1 in other cellular contexts, including genes whose expression is prominent in the early head ectoderm, from which the lens differentiates. Further, the analysis criteria outlined here represent a filtering scheme that can be used to prioritize genes in future RNA-Seq investigations performed at this stage of ocular lens development.
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Affiliation(s)
- Abby L. Manthey
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - Anne M. Terrell
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - Salil A. Lachke
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - Shawn W. Polson
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, USA
| | - Melinda K. Duncan
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
- Corresponding author at: Melinda K. Duncan, Professor, Department of Biological Sciences, University of Delaware, Newark DE 19716.
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Sun W, Sheng Y, Weng Y, Xu CX, Williams SEI, Liu YT, Hauser MA, Allingham RR, Jin MJ, Chen GD. Lack of association between lysyl oxidase-like 1 polymorphisms and primary open angle glaucoma: a meta-analysis. Int J Ophthalmol 2014; 7:550-6. [PMID: 24967207 DOI: 10.3980/j.issn.2222-3959.2014.03.29] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/20/2014] [Indexed: 02/03/2023] Open
Abstract
AIM To study the associations between lysyl oxidase-like 1 (LOXL1) polymorphisms and primary open angle glaucoma (POAG) remain inconsistent. In this study, we have performed a meta-analysis to investigate the association of LOXL1 polymorphisms with POAG risk. METHODS Published literature from PubMed and other databases were retrieved. All studies evaluating the association between LOXL1 polymorphisms (rs2165241, rs1048661, rs3825942) and POAG risk were included. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using random- or fixed-effects model. RESULTS Twelve studies were identified as eligible articles, with thirteen (2098 cases and 16 473 controls), thirteen (1795 cases and 2916 controls) and sixteen population cohorts (2456 cases and 2846 controls) for the association of rs2165241, rs1048661 and rs3825942 with POAG risk respectively. Overall analyses showed no association between each LOXL1 polymorphism and POAG risk, and the negative associations were remained when the subjects were stratified as Caucasian and Asian. The heterozygote of rs2165241 was associated with reduced POAG risk in hospital-based populations (TC vs CC: OR, 0.79, 95%CI: 0.63-0.99), and rs1048661 was associated with increased POAG risk in hospital-based populations in a dominant model (TT vs CC+CT: OR, 1.23, 95%CI: 1.01-1.50); however, these associations were not found in population-based subjects. CONCLUSION This meta-analysis suggests that LOXL1 polymorphisms are not associated with POAG risk. Given the limited sample size, the associations of LOXL1 polymorphisms with POAG risk in hospital-based populations await further investigation.
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Affiliation(s)
- Wen Sun
- Department of Ophthalmology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, Zhejiang Province, China
| | - Yan Sheng
- Department of Ophthalmology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, Zhejiang Province, China
| | - Yu Weng
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, Zhejiang Province, China
| | - Chun-Xiao Xu
- Department of Public Health, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang Province, China
| | - Susan E I Williams
- Division of Ophthalmology, Department of Neurosciences, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Yu-Tao Liu
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Michael A Hauser
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA ; Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina 27710, USA
| | - R Rand Allingham
- Center for Human Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA ; Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina 27710, USA
| | - Ming-Juan Jin
- Department of Public Health, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang Province, China
| | - Guang-Di Chen
- Department of Public Health, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang Province, China
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