1
|
Benagiano V, Rizzi A, Sannace C, Alessio G, Ribatti D, Dammacco R. Aqueous humor as eye lymph: A crossroad between venous and lymphatic system. Exp Eye Res 2024; 243:109904. [PMID: 38642600 DOI: 10.1016/j.exer.2024.109904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/18/2024] [Accepted: 04/17/2024] [Indexed: 04/22/2024]
Abstract
Aqueous humor (AQH) is a transparent fluid with characteristics similar to those of the interstitial fluid, which fills the eyeball posterior and anterior chambers and circulates in them from the sites of production to those of drainage. The AQH volume and pressure homeostasis is essential for the trophism of the ocular avascular tissues and their normal structure and function. Different AQH outflow pathways exist, including a main pathway, quite well defined anatomically and referred to as the conventional pathway, and some accessory pathways, more recently described and still not fully morphofunctionally understood, generically referred to as unconventional pathways. The conventional pathway is based on the existence of a series of conduits starting with the trabecular meshwork and Schlemm's Canal and continuing with a system of intrascleral and episcleral venules, which are tributaries to veins of the anterior segment of the eyeball. The unconventional pathways are mainly represented by the uveoscleral pathway, in which AQH flows through clefts, interstitial conduits located in the ciliary body and sclera, and then merges into the aforementioned intrascleral and episcleral venules. A further unconventional pathway, the lymphatic pathway, has been supported by the demonstration of lymphatic microvessels in the limbal sclera and, possibly, in the uvea (ciliary body, choroid) as well as by the ocular glymphatic channels, present in the neural retina and optic nerve. It follows that AQH may be drained from the eyeball through blood vessels (TM-SC pathway, US pathway) or lymphatic vessels (lymphatic pathway), and the different pathways may integrate or compensate for each other, optimizing the AQH drainage. The present review aims to define the state-of-the-art concerning the structural organization and the functional anatomy of all the AQH outflow pathways. Particular attention is paid to examining the regulatory mechanisms active in each of them. The new data on the anatomy and physiology of AQH outflow pathways is the key to understanding the pathophysiology of AQH outflow disorders and could open the way for novel approaches to their treatment.
Collapse
Affiliation(s)
- Vincenzo Benagiano
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy.
| | - Anna Rizzi
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
| | - Carmela Sannace
- Azienda Sanitaria Locale Bari, Ophthalmology Day Service Triggiano-Gioia del Colle, Bari, Italy
| | - Giovanni Alessio
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
| | - Domenico Ribatti
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
| | - Rosanna Dammacco
- Department of Translational Biomedicine and Neuroscience, University of Bari 'Aldo Moro', Bari, Italy
| |
Collapse
|
2
|
Gu X, Chen X, Zhang X, Liu K, Li JJ, Lv W, Zeng L, Wu M, Zhou W, Wang W, Shi S, Deng Y, Li Y, Gao X, Ju R, Dubrac A, Liu X, Zhang F. Macrophage-induced integrin signaling promotes Schlemm's canal formation to prevent intraocular hypertension and glaucomatous optic neuropathy. Cell Rep 2024; 43:113799. [PMID: 38367239 DOI: 10.1016/j.celrep.2024.113799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 12/13/2023] [Accepted: 01/31/2024] [Indexed: 02/19/2024] Open
Abstract
Schlemm's canal (SC) functions to maintain proper intraocular pressure (IOP) by draining aqueous humor and has emerged as a promising therapeutic target for glaucoma, the second-leading cause of irreversible blindness worldwide. However, our current understanding of the mechanisms governing SC development and functionality remains limited. Here, we show that vitronectin (VTN) produced by limbal macrophages promotes SC formation and prevents intraocular hypertension by activating integrin αvβ3 signaling. Genetic inactivation of this signaling system inhibited the phosphorylation of AKT and FOXO1 and reduced β-catenin activity and FOXC2 expression, thereby causing impaired Prox1 expression and deteriorated SC morphogenesis. This ultimately led to increased IOP and glaucomatous optic neuropathy. Intriguingly, we found that aged SC displayed downregulated integrin β3 in association with dampened Prox1 expression. Conversely, FOXO1 inhibition rejuvenated the aged SC by inducing Prox1 expression and SC regrowth, highlighting a possible strategy by targeting VTN/integrin αvβ3 signaling to improve SC functionality.
Collapse
Affiliation(s)
- Xinyu Gu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Xun Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Xuan Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Keli Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Jing-Jing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Wenyu Lv
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510060, China
| | - Lei Zeng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Mingjuan Wu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Weibin Zhou
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510060, China
| | - Weifa Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Shunhua Shi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Yicheng Deng
- School of Medicine, Sun Yat-sen University, Guangzhou 510060, China
| | - Yunhua Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Xinbo Gao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Rong Ju
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Alexandre Dubrac
- Centre de Recherche, CHU St. Justine, Montréal, QC, Canada; Département de Pathologie et Biologie Cellulaire, Université de Montréal, Montréal, QC, Canada
| | - Xialin Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China
| | - Feng Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou 510060, China.
| |
Collapse
|
3
|
Youngblood H, Schoenlein PV, Pasquale LR, Stamer WD, Liu Y. Estrogen dysregulation, intraocular pressure, and glaucoma risk. Exp Eye Res 2023; 237:109725. [PMID: 37956940 PMCID: PMC10842791 DOI: 10.1016/j.exer.2023.109725] [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: 09/01/2023] [Revised: 10/20/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
Characterized by optic nerve atrophy due to retinal ganglion cell (RGC) death, glaucoma is the leading cause of irreversible blindness worldwide. Of the major risk factors for glaucoma (age, ocular hypertension, and genetics), only elevated intraocular pressure (IOP) is modifiable, which is largely regulated by aqueous humor outflow through the trabecular meshwork. Glucocorticoids such as dexamethasone have long been known to elevate IOP and lead to glaucoma. However, several recent studies have reported that steroid hormone estrogen levels inversely correlate with glaucoma risk, and that variants in estrogen signaling genes have been associated with glaucoma. As a result, estrogen dysregulation may contribute to glaucoma pathogenesis, and estrogen signaling may protect against glaucoma. The mechanism for estrogen-related protection against glaucoma is not completely understood but likely involves both regulation of IOP homeostasis and neuroprotection of RGCs. Based upon its known activities, estrogen signaling may promote IOP homeostasis by affecting extracellular matrix turnover, focal adhesion assembly, actin stress fiber formation, mechanosensation, and nitric oxide production. In addition, estrogen receptors in the RGCs may mediate neuroprotective functions. As a result, the estrogen signaling pathway may offer a therapeutic target for both IOP control and neuroprotection. This review examines the evidence for a relationship between estrogen and IOP and explores the possible mechanisms by which estrogen maintains IOP homeostasis.
Collapse
Affiliation(s)
- Hannah Youngblood
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Patricia V Schoenlein
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA; Department of Radiology and Georgia Cancer Center, Augusta University, Augusta, GA, USA; Department of Surgery, Augusta University, Augusta, GA, USA
| | - Louis R Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - W Daniel Stamer
- Department of Ophthalmology and Biomedical Engineering, Duke University, Durham, NC, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA; James and Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, USA; Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA, USA.
| |
Collapse
|
4
|
Kizhatil K, Clark G, Sunderland D, Bhandari A, Horbal L, Balasubramanian R, John S. FYN regulates aqueous humor outflow and IOP through the phosphorylation of VE-cadherin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.04.556253. [PMID: 37886565 PMCID: PMC10602025 DOI: 10.1101/2023.09.04.556253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
The exact sites and molecules that determine resistance to aqueous humor drainage and control intraocular pressure (IOP) need further elaboration. Proposed sites include the inner wall of Schlemms's canal and the juxtacanalicular trabecular meshwork ocular drainage tissues. The adherens junctions (AJs) of Schlemm's canal endothelial cells (SECs) must both preserve the blood-aqueous humor (AQH) barrier and be conducive to AQH drainage. How homeostatic control of AJ permeability in SC occurs and how such control impacts IOP is unclear. We hypothesized that mechano-responsive phosphorylation of the junctional molecule VE-CADHERIN (VEC) by SRC family kinases (SFKs) regulates the permeability of SEC AJs. We tested this by clamping IOP at either 16 mmHg, 25 mmHg, or 45 mmHg in mice and then measuring AJ permeability and VEC phosphorylation. We found that with increasing IOP: 1) SEC AJ permeability increased, 2) VEC phosphorylation was increased at tyrosine-658, and 3) SFKs were activated at the AJ. Among the two SFKs known to phosphorylate VEC, FYN, but not SRC, localizes to the SC. Furthermore, FYN mutant mice had decreased phosphorylation of VEC at SEC AJs, dysregulated IOP, and reduced AQH outflow. Together, our data demonstrate that increased IOP activates FYN in the inner wall of SC, leading to increased phosphorylation of AJ VEC and, thus, decreased resistance to AQH outflow. These findings support a crucial role of mechanotransduction signaling in IOP homeostasis within SC in response to IOP. These data strongly suggest that the inner wall of SC partially contributes to outflow resistance.
Collapse
|
5
|
González-Hernández S, Mukouyama YS. Lymphatic vasculature in the central nervous system. Front Cell Dev Biol 2023; 11:1150775. [PMID: 37091974 PMCID: PMC10119411 DOI: 10.3389/fcell.2023.1150775] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 03/28/2023] [Indexed: 04/25/2023] Open
Abstract
The central nervous system (CNS) is considered as an immune privilege organ, based on experiments in the mid 20th century showing that the brain fails to mount an efficient immune response against an allogeneic graft. This suggests that in addition to the presence of the blood-brain barrier (BBB), the apparent absence of classical lymphatic vasculature in the CNS parenchyma limits the capacity for an immune response. Although this view is partially overturned by the recent discovery of the lymphatic-like hybrid vessels in the Schlemm's canal in the eye and the lymphatic vasculature in the outmost layer of the meninges, the existence of lymphatic vessels in the CNS parenchyma has not been reported. Two potential mechanisms by which lymphatic vasculature may arise in the organs are: 1) sprouting and invasion of lymphatic vessels from the surrounding tissues into the parenchyma and 2) differentiation of blood endothelial cells into lymphatic endothelial cells in the parenchyma. Considering these mechanisms, we here discuss what causes the dearth of lymphatic vessels specifically in the CNS parenchyma.
Collapse
|
6
|
Qiao Y, Sun Z, Tan C, Lai J, Sun X, Chen J. Intracameral Injection of AAV-DJ.COMP-ANG1 Reduces the IOP of Mice by Reshaping the Trabecular Outflow Pathway. Invest Ophthalmol Vis Sci 2022; 63:15. [PMID: 36520455 PMCID: PMC9769031 DOI: 10.1167/iovs.63.13.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Purpose The angiopoietin-1 (ANG1)-TIE signaling pathway orchestrates the development and maintenance of the Schlemm's canal (SC). In this study, we investigated the impact of adeno-associated virus (AAV)-mediated gene therapy with cartilage oligomeric matrix protein-ANG1 (COMP-ANG1) on trabecular outflow pathway. Methods Different serotypes of AAVs were compared for transduction specificity and efficiency in the anterior segment. The selected AAVs encoding COMP-ANG1 or ZsGreen1 (control) were delivered into the anterior chambers of wild-type C57BL/6J mice. The IOP and ocular surface were monitored regularly. Ocular perfusion was performed to measure the outflow facility and label flow patterns of the trabecular drainage pathway. Structural features of SC as well as limbal, retinal, and skin vessels were visualized by immunostaining. Ultrastructural changes in the SC and trabecular meshwork were observed under transmission electron microscopy. Results AAV-DJ could effectively infect the anterior segment. Intracameral injection of AAV-DJ.COMP-ANG1 lowered IOP in wild-type C57BL/6J mice. No signs of inflammation or angiogenesis were noticed. Four weeks after AAV injection, the conventional outflow facility and effective filtration area were increased significantly (P = 0.005 and P = 0.04, respectively). Consistently, the area of the SC was enlarged (P < 0.001) with increased density of giant vacuoles in the inner wall (P = 0.006). In addition, the SC endothelia lay on a more discontinuous basement membrane (P = 0.046) and a more porous juxtacanalicular tissue (P = 0.005) in the COMP-ANG1 group. Conclusions Intracamerally injected AAV-DJ.COMP-ANG1 offers a significant IOP-lowering effect by remodeling the trabecular outflow pathway of mouse eyes.
Collapse
Affiliation(s)
- Yunsheng Qiao
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Zhongmou Sun
- University of Rochester, School of Medicine and Dentistry, Rochester, New York, New York, United States
| | - Chen Tan
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Junyi Lai
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China,NHC Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Junyi Chen
- Department of Ophthalmology & Visual Science, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China,NHC Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| |
Collapse
|
7
|
Shaimova VA, Trubilin VN, Dmukh TS, Shaimov TB, Shaimov RB, Kravchenko TG, Maltsev DS, Kulikov AN, Galin AY, Kuchkildina SK, Shaimova TA, Islamova GR, Davletbaeva DR, Fomin AV. [OCT visualization of hyporeflective lacuna in the retrolental space]. Vestn Oftalmol 2021; 137:45-52. [PMID: 34965067 DOI: 10.17116/oftalma202113706145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To investigate the vitreo-lenticular interface and anterior vitreous using high-resolution optical coherence tomography (OCT). MATERIAL AND METHODS This prospective single-center pilot study included 34 patients (68 eyes) - 6 males and 28 females with a mean age of 58.4±12.0 years (age range 24-81 years). OCT scanning was performed on the spectral domain optical coherence tomography (SD-OCT) device SOLIX (OPTOVUE, USA) in the Full Range AC mode with the following scan parameters: from 14 to 18 mm in horizontal length and 6.25 mm in the axial dimension. To improve the signal-to-noise ratio and increase image clarity of the final scan, averaging of eight simultaneous scans was performed. RESULTS In all healthy volunteers, hyporeflective retrolental cavities-lacunae were observed in both eyes during visualization of the retrolental space in the horizontal and vertical planes. The median distance from the posterior pole of the lens to the lacuna was 697 µm. The median width of the lacuna was 157 µm. CONCLUSION To the best of our knowledge, we consider this to be one of the first in vivo visualizations of a previously undescribed structure - hyporeflective retrolental lacuna - using SOLIX high-resolution OCT device. The retrolental lacuna may play the role of a buffer system, or belong to the lymphatic system of the vitreous body and the eye.
Collapse
Affiliation(s)
- V A Shaimova
- Academy of postgraduate education of the Federal Research and Clinical Center of Specialized Medical Care and Medical Technologies, Moscow, Russia.,LLP «Center vision», Chelyabinsk, Russia.,Multidisciplinary center of laser medicine, Chelyabinsk, Russia
| | - V N Trubilin
- Academy of postgraduate education of the Federal Research and Clinical Center of Specialized Medical Care and Medical Technologies, Moscow, Russia.,A.I. Burnasyan Federal Medical Biophysical Center of the Federal Medical Biological Agency, Moscow, Russia
| | - T S Dmukh
- LLP «Center of vision correction «Oculus», Yekaterinburg, Russia
| | | | | | - T G Kravchenko
- Multidisciplinary center of laser medicine, Chelyabinsk, Russia
| | - D S Maltsev
- S.M. Kirov Military Medical Academy, St. Petersburg, Russia
| | - A N Kulikov
- S.M. Kirov Military Medical Academy, St. Petersburg, Russia
| | - A Yu Galin
- LLP «Center vision», Chelyabinsk, Russia
| | | | | | | | - D R Davletbaeva
- LLP «Center of vision correction «Doctor Lens», Yekaterinburg, Russia
| | | |
Collapse
|
8
|
Qiao Y, Chen Y, Tan C, Sun X, Chen X, Chen J. Screening and Functional Analysis of TEK Mutations in Chinese Children With Primary Congenital Glaucoma. Front Genet 2021; 12:764509. [PMID: 34956319 PMCID: PMC8703195 DOI: 10.3389/fgene.2021.764509] [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: 08/25/2021] [Accepted: 10/29/2021] [Indexed: 11/17/2022] Open
Abstract
Purposes: Recent studies have suggested that loss-of-function mutations of the tunica intima endothelial receptor tyrosine kinase (TEK) are responsible for approximately 5% of primary congenital glaucoma (PCG) cases in diverse populations. However, the causative role of TEK mutations has not been studied in Chinese PCG patients. Here, we report the mutation spectrum of TEK after screening a large cohort of PCG patients of Chinese Han origin and analyze the identified variants in functional assays. Methods: TEK-targeted next-generation sequencing (NGS) was performed in 200 PCG patients. Candidate variants were prioritized by mutation type and allele frequency in public datasets. Plasmids containing wild type and identified variants of TEK were constructed and used to assess protein expression, solubility, receptor auto-phosphorylation, and response to ligand stimulation in cell-based assays. Results: Ten missense and one nonsense heterozygous variants were detected by NGS in 11 families. The clinical features of TEK variants carriers were comparable to that of TEK-mutated patients identified in other populations and CYP1B1-mutated individuals from in-house database. Functional analysis confirmed four variants involving evolutionarily conserved residues to be loss-of-function, while one variant (p.R1003H) located in tyrosine kinase domain seemed to be an activating mutation. However, our results did not support the pathogenicity of the other five variants (p.H52R, p.M131I, p.M228V, p.H494Y, and p.L888P). Conclusion: We provide evidence for TEK variants to be causative in Chinese PCG patients for the first time. Attention needs to be paid to TEK mutations in future genetic testing.
Collapse
Affiliation(s)
- Yunsheng Qiao
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yuhong Chen
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Chen Tan
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Xueli Chen
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Junyi Chen
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China.,State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| |
Collapse
|
9
|
Zhao Y, Li Y, Hong J, Le Q, Xu J. Fourier-Domain Optical Coherence Tomographic Assessment of Changes in the Schlemm's Canal of Nonglaucomatous Subjects After Keratoplasty. Front Physiol 2021; 12:716117. [PMID: 34925051 PMCID: PMC8675085 DOI: 10.3389/fphys.2021.716117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 10/28/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: This study aimed to evaluate the impact of keratoplasty on the in vivo anatomical structures in the Schlemm's canal (SC) of nonglaucomatous subjects using Fourier-domain optical coherence tomography (FD-OCT). Methods: Sixty-six nonglaucomatous eyes that underwent penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), or triple surgery were enrolled in this prospective, comparative, observational study. The SC imaging was performed using FD-OCT before and after surgery in both the nasal and temporal quadrants. Patient demographics, SC parameters [e.g., cross-sectional area (CSA), meridional diameter of SC (MSC), sagittal diameter of SC (SSC), and circumference (CCF)], and the correlations between the variation of SC parameters and intraocular pressure (IOP) were analyzed. Results: The mean age of all subjects was 40.27 ± 18.97 years. Among all cases, the nasal, temporal, and mean MSC significantly decreased on the first day after surgery and then increased at 1 week (p = 0.04, 0.017, and 0.01, respectively). Temporal CSA (tCSA), temporal MSC (tMSC), and temporal circumference (tCCF) after PK (p = 0.017, 0.020, and 0.018, respectively) and nasal MSC (nMSC) after DALK (p = 0.025) decreased significantly on the first day after surgery. The shift in mean IOP was significantly correlated with the changes in tMSC (r = 0.341, p = 0.003) and CCF (r = 0.207, p = 0.048). Conclusion: SC had significant in vivo morphological changes in the early period after keratoplasty in nonglaucomatous eyes, accompanied with elevation of IOP. Early intervention might be necessary to prevent secondary glaucoma early after keratoplasty.
Collapse
Affiliation(s)
- Yujin Zhao
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Yue Li
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Jiaxu Hong
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China.,Key Laboratory of Myopia, National Health and Family Planning Commission, Shanghai, China
| | - Qihua Le
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Jianjiang Xu
- Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia (Fudan University), Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| |
Collapse
|
10
|
Aqueous outflow channels and its lymphatic association: A review. Surv Ophthalmol 2021; 67:659-674. [PMID: 34656556 PMCID: PMC9008077 DOI: 10.1016/j.survophthal.2021.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 10/07/2021] [Accepted: 10/11/2021] [Indexed: 11/24/2022]
Abstract
The human eye has a unique immune architecture and behavior. While the conjunctiva is known to have a well-defined lymphatic drainage system, the cornea, sclera, and uveal tissues were historically considered "alymphatic" and thought to be immune privileged. The very fact that the aqueous outflow channels carry a clear fluid (aqueous humor) along the outflow pathway makes it hard to ignore its lymphatic-like characteristics. The development of novel lymphatic lineage markers and expression of these markers in aqueous outflow channels and improved imaging capabilities has sparked a renewed interest in the study of ocular lymphatics. Ophthalmic lymphatic research has had a directional shift over the last decade, offering an exciting new physiological platform that needs further in-depth understanding. The evidence of a presence of distinct lymphatic channels in the human ciliary body is gaining significant traction. The uveolymphatic pathway is an alternative new route for aqueous outflow and adds a new dimension to pathophysiology and management of glaucoma. Developing novel animal models, markers, and non-invasive imaging tools to delineate the core anatomical structure and physiological functions may help pave some crucial pathways to understand disease pathophysiology and help develop novel targeted therapeutic approaches for glaucoma.
Collapse
|
11
|
Identification of Estrogen Signaling in a Prioritization Study of Intraocular Pressure-Associated Genes. Int J Mol Sci 2021; 22:ijms221910288. [PMID: 34638643 PMCID: PMC8508848 DOI: 10.3390/ijms221910288] [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: 09/09/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 12/12/2022] Open
Abstract
Elevated intraocular pressure (IOP) is the only modifiable risk factor for primary open-angle glaucoma (POAG). Herein we sought to prioritize a set of previously identified IOP-associated genes using novel and previously published datasets. We identified several genes for future study, including several involved in cytoskeletal/extracellular matrix reorganization, cell adhesion, angiogenesis, and TGF-β signaling. Our differential correlation analysis of IOP-associated genes identified 295 pairs of 201 genes with differential correlation. Pathway analysis identified β-estradiol as the top upstream regulator of these genes with ESR1 mediating 25 interactions. Several genes (i.e., EFEMP1, FOXC1, and SPTBN1) regulated by β-estradiol/ESR1 were highly expressed in non-glaucomatous human trabecular meshwork (TM) or Schlemm’s canal (SC) cells and specifically expressed in TM/SC cell clusters defined by single-cell RNA-sequencing. We confirmed ESR1 gene and protein expression in human TM cells and TM/SC tissue with quantitative real-time PCR and immunofluorescence, respectively. 17β-estradiol was identified in bovine, porcine, and human aqueous humor (AH) using ELISA. In conclusion, we have identified estrogen receptor signaling as a key modulator of several IOP-associated genes. The expression of ESR1 and these IOP-associated genes in TM/SC tissue and the presence of 17β-estradiol in AH supports a role for estrogen signaling in IOP regulation.
Collapse
|
12
|
Sgambellone S, Lucarini L, Lanzi C, Masini E. Novel Insight of Histamine and Its Receptor Ligands in Glaucoma and Retina Neuroprotection. Biomolecules 2021; 11:1186. [PMID: 34439851 PMCID: PMC8392511 DOI: 10.3390/biom11081186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/06/2021] [Accepted: 08/09/2021] [Indexed: 01/01/2023] Open
Abstract
Glaucoma is a multifactorial neuropathy characterized by increased intraocular pressure (IOP), and it is the second leading cause of blindness worldwide after cataracts. Glaucoma combines a group of optic neuropathies characterized by the progressive degeneration of retinal ganglionic cells (RGCs). Increased IOP and short-term IOP fluctuation are two of the most critical risk factors in glaucoma progression. Histamine is a well-characterized neuromodulator that follows a circadian rhythm, regulates IOP and modulates retinal circuits and vision. This review summarizes findings from animal models on the role of histamine and its receptors in the eye, focusing on the effects of histamine H3 receptor antagonists for the future treatment of glaucomatous patients.
Collapse
Affiliation(s)
- Silvia Sgambellone
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Pharmacology and Toxicology Section, University of Florence, 50139 Florence, Italy; (S.S.); (E.M.)
| | - Laura Lucarini
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Pharmacology and Toxicology Section, University of Florence, 50139 Florence, Italy; (S.S.); (E.M.)
| | - Cecilia Lanzi
- Toxicology Unit, Emergency Department, Careggi University Hospital, 50139 Florence, Italy;
| | - Emanuela Masini
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Pharmacology and Toxicology Section, University of Florence, 50139 Florence, Italy; (S.S.); (E.M.)
| |
Collapse
|
13
|
Madekurozwa M, Stamer WD, Reina-Torres E, Sherwood JM, Overby DR. The ocular pulse decreases aqueous humor outflow resistance by stimulating nitric oxide production. Am J Physiol Cell Physiol 2021; 320:C652-C665. [PMID: 33439773 PMCID: PMC8260357 DOI: 10.1152/ajpcell.00473.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/21/2020] [Accepted: 01/12/2021] [Indexed: 11/22/2022]
Abstract
Intraocular pressure (IOP) is not static, but rather oscillates by 2-3 mmHg because of cardiac pulsations in ocular blood volume known as the ocular pulse. The ocular pulse induces pulsatile shear stress in Schlemm's canal (SC). We hypothesize that the ocular pulse modulates outflow facility by stimulating shear-induced nitric oxide (NO) production by SC cells. We confirmed that living mice exhibit an ocular pulse with a peak-to-peak (pk-pk) amplitude of 0.5 mmHg under anesthesia. Using iPerfusion, we measured outflow facility (flow/pressure) during alternating periods of steady or pulsatile IOP in both eyes of 16 cadaveric C57BL/6J mice (13-14 weeks). Eyes were retained in situ, with an applied mean pressure of 8 mmHg and 1.0 mmHg pk-pk pressure amplitude at 10 Hz to mimic the murine heart rate. One eye of each cadaver was perfused with 100 µM L-NAME to inhibit NO synthase, whereas the contralateral eye was perfused with vehicle. During the pulsatile period in the vehicle-treated eye, outflow facility increased by 16 [12, 20] % (P < 0.001) relative to the facility measured during the preceding and subsequent steady periods. This effect was partly inhibited by L-NAME, where pressure pulsations increased outflow facility by 8% [4, 12] (P < 0.001). Thus, the ocular pulse causes an immediate increase in outflow facility in mice, with roughly one-half of the facility increase attributable to NO production. These studies reveal a dynamic component to outflow function that responds instantly to the ocular pulse and may be important for outflow regulation and IOP homeostasis.
Collapse
Affiliation(s)
- Michael Madekurozwa
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina
| | - Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
| |
Collapse
|
14
|
Oliver G, Kipnis J, Randolph GJ, Harvey NL. The Lymphatic Vasculature in the 21 st Century: Novel Functional Roles in Homeostasis and Disease. Cell 2020; 182:270-296. [PMID: 32707093 PMCID: PMC7392116 DOI: 10.1016/j.cell.2020.06.039] [Citation(s) in RCA: 353] [Impact Index Per Article: 88.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/17/2020] [Accepted: 06/25/2020] [Indexed: 12/19/2022]
Abstract
Mammals have two specialized vascular circulatory systems: the blood vasculature and the lymphatic vasculature. The lymphatic vasculature is a unidirectional conduit that returns filtered interstitial arterial fluid and tissue metabolites to the blood circulation. It also plays major roles in immune cell trafficking and lipid absorption. As we discuss in this review, the molecular characterization of lymphatic vascular development and our understanding of this vasculature's role in pathophysiological conditions has greatly improved in recent years, changing conventional views about the roles of the lymphatic vasculature in health and disease. Morphological or functional defects in the lymphatic vasculature have now been uncovered in several pathological conditions. We propose that subtle asymptomatic alterations in lymphatic vascular function could underlie the variability seen in the body's response to a wide range of human diseases.
Collapse
Affiliation(s)
- Guillermo Oliver
- Center for Vascular and Developmental Biology, Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
| | - Jonathan Kipnis
- Center for Brain Immunology and Glia (BIG), University of Virginia, Charlottesville, VA 22908, USA; Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA
| | - Gwendalyn J Randolph
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Natasha L Harvey
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, SA, Australia
| |
Collapse
|
15
|
Wu Y, Seong YJ, Li K, Choi D, Park E, Daghlian GH, Jung E, Bui K, Zhao L, Madhavan S, Daghlian S, Daghlian P, Chin D, Cho IT, Wong AK, Heur M, Zhang-Nunes S, Tan JC, Ema M, Wong TT, Huang AS, Hong YK. Organogenesis and distribution of the ocular lymphatic vessels in the anterior eye. JCI Insight 2020; 5:135121. [PMID: 32641580 DOI: 10.1172/jci.insight.135121] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 05/27/2020] [Indexed: 12/16/2022] Open
Abstract
Glaucoma surgeries, such as trabeculectomy, are performed to lower intraocular pressure to reduce risk of vision loss. These surgeries create a new passage in the eye that reroutes the aqueous humor outflow to the subconjunctival space, where the fluid is presumably absorbed by the conjunctival lymphatics. Here, we characterized the development and function of the ocular lymphatics using transgenic lymphatic reporter mice and rats. We found that the limbal and conjunctival lymphatic networks are progressively formed from a primary lymphatic vessel that grows from the nasal-side medial canthus region at birth. This primary lymphatic vessel immediately branches out, invades the limbus and conjunctiva, and bidirectionally encircles the cornea. As a result, the distribution of the ocular lymphatics is significantly polarized toward the nasal side, and the limbal lymphatics are directly connected to the conjunctival lymphatics. New lymphatic sprouts are produced mainly from the nasal-side limbal lymphatics, posing the nasal side of the eye as more responsive to fluid drainage and inflammatory stimuli. Consistent with this polarized distribution of the ocular lymphatics, a higher drainage efficiency was observed in the nasal side than the temporal side of the eye when injected with a fluorescent tracer. In contrast, blood vessels are evenly distributed at the anterior surface of the eyes. Also, we found that these distinct vascular distribution patterns were conserved in human eyes. Together, our study demonstrated that the ocular surface lymphatics are more densely present in the nasal side and uncovered the potential clinical benefits in selecting the nasal side as a glaucoma surgery site to improve fluid drainage.
Collapse
Affiliation(s)
- Yifan Wu
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Young Jin Seong
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Kin Li
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA.,College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA
| | - Dongwon Choi
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Eunkyung Park
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - George H Daghlian
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Eunson Jung
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Khoa Bui
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Luping Zhao
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Shrimika Madhavan
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Saren Daghlian
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Patill Daghlian
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Desmond Chin
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Il-Taeg Cho
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | | | - Martin Heur
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - Sandy Zhang-Nunes
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| | - James C Tan
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, UCLA, Los Angeles, California, USA
| | - Masatsugu Ema
- Department of Stem Cells and Human Disease Models Research Center for Animal Life, Science Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, Japan
| | - Tina T Wong
- Singapore Eye Research Institute, Duke NUS Graduate Medical School, Singapore
| | - Alex S Huang
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, UCLA, Los Angeles, California, USA
| | - Young-Kwon Hong
- Department of Surgery and.,Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine of USC, USC, Los Angeles, California, USA
| |
Collapse
|
16
|
Cai J, Perkumas K, Stamer WD, Liu Y. An In Vitro Bovine Cellular Model for Human Schlemm's Canal Endothelial Cells and Their Response to TGFβ Treatment. Transl Vis Sci Technol 2020; 9:32. [PMID: 32832237 PMCID: PMC7414733 DOI: 10.1167/tvst.9.7.32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/17/2020] [Indexed: 12/12/2022] Open
Abstract
Purpose Due to the limited availability of primary human Schlemm's canal (SC) endothelial cells, we aimed to develop an in vitro cellular model using the angular aqueous plexus (AAP) cells from bovine eyes. Methods We harvested a mixture of cells from the trabecular meshwork region including AAP loops from multiple donors, followed by puromycin treatment and immunostaining of Von Willebrand factor and vascular endothelial (VE)-cadherin to confirm identity. Previously identified differentially expressed genes in glaucomatous SC cells were examined in non-glaucomatous SC cells (n = 3) under 0% or 15% equibiaxial strain for 24 hours using droplet digital polymerase chain reaction (ddPCR) and analyzed using the Ingenuity Pathway Analysis (IPA) software application to identify upstream regulators. To compare the cellular responses to candidate regulators of these mechanoresponsive genes, AAP and human SC cells (n = 3) were treated with 5 or 10 ng/mL transforming growth factor beta-2 (TGFβ2) for 24 or 48 hours, followed with expression profiling using real-time PCR or ddPCR. Results We found that the isolated AAP cells displayed uniform cobblestone-like morphology and positive expression of two endothelial markers. In stretched SC cells, nine glaucoma-related genes were upregulated, and IPA implicated TGFβ as a potential upstream regulator. The effects of TGFβ2 treatment were similar for both AAP and SC cells in a dose- and time-dependent manner, activating TGFBR1 and SMAD2, inhibiting BMP4, and altering expression of three glaucoma-related genes (DCN,EZR, and CYP1B1). Conclusions Bovine AAP cells may serve as an alternative cellular model of human SC cells. Translational Relevance These AAP cells may be used to study the functional pathways related to the outflow facility.
Collapse
Affiliation(s)
- Jingwen Cai
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | | | - W. Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
- James & Jean Culver Vision Discovery Institute, Augusta University, Augusta, GA, USA
- Center for Biotechnology and Genomic Medicine, Augusta University, Augusta, GA, USA
| |
Collapse
|
17
|
Wang LY, Su GY, Wei ZY, Zhang ZJ, Liang QF. Progress in the basic and clinical research on the Schlemm's canal. Int J Ophthalmol 2020; 13:816-821. [PMID: 32420231 DOI: 10.18240/ijo.2020.05.18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 01/07/2020] [Indexed: 11/23/2022] Open
Abstract
Glaucoma is a leading cause of irreversible blindness in the world. Intraocular pressure (IOP) plays a key role in glaucoma development and progression. Schlemm's canal (SC), an important structure of the anterior chamber angle, regulates the flow of aqueous humor and maintains IOP. Because of its special function of aqueous outflow, the SC has been intensive investigated recently. Several characteristics of SC in anatomy, physiology and pathophysiology have been revealed. Compare to normal, glaucomatous SC cells are more sensitive to substrate stiffness, have higher stiffness and and lower porosity leading to higher outflow resistance. And SC collapse caused by acute IOP increase is partially or totally reversal. With advanced inspection techniques, high-quality images of the SC can be obtained in vivo, which facilitates SC quantitative measurements clinically and allows us to investigate a new therapy paradigm for glaucoma. In this review, we summarize the basic and clinical research that focused on mechanisms of aqueous outflow resistance and SC changes in physiological, pathological, and post-treatment states.
Collapse
Affiliation(s)
- Le-Ying Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China
| | - Guan-Yu Su
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China
| | - Zhen-Yu Wei
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China
| | - Zi-Jun Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China
| | - Qing-Feng Liang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China
| |
Collapse
|
18
|
Tian YI, Zhang X, Torrejon K, Danias J, Gindina S, Nayyar A, Du Y, Xie Y. A bioengineering approach to Schlemm's canal-like stem cell differentiation for in vitro glaucoma drug screening. Acta Biomater 2020; 105:203-213. [PMID: 31982588 DOI: 10.1016/j.actbio.2020.01.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 12/30/2022]
Abstract
Human Schlemm's canal (HSC) cells are critical for understanding outflow physiology and glaucoma etiology. However, primary donor cells frequently used in research are difficult to isolate. HSC cells exhibit both vascular and lymphatic markers. Human adipose-derived stem cells (ADSCs) represent a potential source of HSC due to their capacity to differentiate into both vascular and lymphatic endothelial cells, via VEGF-A and VEGF-C. Shear stress plays a critical role in maintaining HSC integrity, function, and PROX1 expression. Additionally, the human trabecular meshwork (HTM) microenvironment could provide cues for HSC-like differentiation. We hypothesize that subjecting ADSCs to VEGF-A or VEGF-C, shear stress, and co-culture with HTM cells could provide biological, mechanical, and cellular cues necessary for HSC-like differentiation. To test this hypothesis, effects of VEGF-A, VEGF-C, and shear stress on ADSC differentiation were examined and compared to primary HSC cells in terms of cell morphology, and HSC marker expression using qPCR, immunoblotting, and immunocytochemistry analysis. Furthermore, the effect of co-culture with HTM cells on porous scaffolds on ADSC differentiation was studied. Treatment with VEGF-C under shear stress is effective in differentiating ADSCs into PROX1-expressing HSC-like cells. Co-culture with HTM cells on porous scaffolds leads to HTM/ADSC-derived HSC-like constructs that regulate through-flow and respond as expected to dexamethasone. STATEMENT OF SIGNIFICANCE: We successfully generated human Schlemm's canal (HSC) like cells from adipocyte-derived stem cells induced by biochemical and biomechanical cues as well as bioengineered human trabecular meshwork (HTM) on micropatterned, porous SU8 scaffolds. These stem cell-derived HSC-like cells co-cultured with HTM cells on SU8 scaffolds can regulate through-flow, and in particular, are responsive to steroid treatment as expected. These findings show that ADSC-derived HSC-like cells have the potential to recreate the ocular outflow pathway for in vitro glaucoma drug screening. To the best of our knowledge, it is the very first time to demonstrate derivation of Schlemm's canal-like cells from stem cells. It provides an important alternative source to primary Schlemm's canal cells that are very difficult to be isolated and cultured from human donors.
Collapse
Affiliation(s)
- Yangzi Isabel Tian
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Xulang Zhang
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA
| | - Karen Torrejon
- Glauconix Biosciences, Inc., 251 Fuller Road, Albany, NY 12203, USA
| | - John Danias
- SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | - Sofya Gindina
- SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | - Ashima Nayyar
- SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | - Yiqin Du
- University of Pittsburg School of Medicine, 203 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Yubing Xie
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203, USA.
| |
Collapse
|
19
|
Pawlak JB, Caron KM. Lymphatic Programing and Specialization in Hybrid Vessels. Front Physiol 2020; 11:114. [PMID: 32153423 PMCID: PMC7044189 DOI: 10.3389/fphys.2020.00114] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 01/31/2020] [Indexed: 12/14/2022] Open
Abstract
Building on a large body of existing blood vascular research, advances in lymphatic research have helped kindle broader investigations into vascular diversity and endothelial plasticity. While the endothelium of blood and lymphatic vessels can be distinguished by a variety of molecular markers, the endothelia of uniquely diverse vascular beds can possess distinctly heterogeneous or hybrid expression patterns. These expression patterns can then provide further insight on the development of these vessels and how they perform their specialized function. In this review we examine five highly specialized hybrid vessel beds that adopt partial lymphatic programing for their specialized vascular functions: the high endothelial venules of secondary lymphoid organs, the liver sinusoid, the Schlemm’s canal of the eye, the renal ascending vasa recta, and the remodeled placental spiral artery. We summarize the morphology and endothelial expression pattern of these vessels, compare them to each other, and interrogate their specialized functions within the broader blood and lymphatic vascular systems.
Collapse
Affiliation(s)
- John B Pawlak
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Kathleen M Caron
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| |
Collapse
|
20
|
Alderfer L, Wei A, Hanjaya-Putra D. Lymphatic Tissue Engineering and Regeneration. J Biol Eng 2018; 12:32. [PMID: 30564284 PMCID: PMC6296077 DOI: 10.1186/s13036-018-0122-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 11/19/2018] [Indexed: 12/22/2022] Open
Abstract
The lymphatic system is a major circulatory system within the body, responsible for the transport of interstitial fluid, waste products, immune cells, and proteins. Compared to other physiological systems, the molecular mechanisms and underlying disease pathology largely remain to be understood which has hindered advancements in therapeutic options for lymphatic disorders. Dysfunction of the lymphatic system is associated with a wide range of disease phenotypes and has also been speculated as a route to rescue healthy phenotypes in areas including cardiovascular disease, metabolic syndrome, and neurological conditions. This review will discuss lymphatic system functions and structure, cell sources for regenerating lymphatic vessels, current approaches for engineering lymphatic vessels, and specific therapeutic areas that would benefit from advances in lymphatic tissue engineering and regeneration.
Collapse
Affiliation(s)
- Laura Alderfer
- Department of Aerospace and Mechanical Engineering, Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Alicia Wei
- Department of Aerospace and Mechanical Engineering, Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Donny Hanjaya-Putra
- Department of Aerospace and Mechanical Engineering, Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN 46556 USA
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46656 USA
- Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556 USA
- Center for Stem Cells and Regenerative Medicine, University of Notre Dame, Notre Dame, IN 46556 USA
- Advanced Diagnostics and Therapeutics, University of Notre Dame, Notre Dame, IN 46556 USA
- Center for Nanoscience and Technology (NDnano), University of Notre Dame, Notre Dame, IN 46556 USA
| |
Collapse
|
21
|
Wong BW, Zecchin A, García-Caballero M, Carmeliet P. Emerging Concepts in Organ-Specific Lymphatic Vessels and Metabolic Regulation of Lymphatic Development. Dev Cell 2018; 45:289-301. [PMID: 29738709 DOI: 10.1016/j.devcel.2018.03.021] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 12/12/2017] [Accepted: 03/26/2018] [Indexed: 02/08/2023]
Abstract
The lymphatic system has been less well characterized than the blood vascular system; however, work in recent years has uncovered novel regulators and non-venous lineages that contribute to lymphatic formation in various organs. Further, the identification of organ-specific lymphatic beds underscores their potential interaction with organ development and function, and highlights the possibility of targeting these organ-specific lymphatics beds in disease. This review focuses on newly described metabolic and epigenetic regulators of lymphangiogenesis and the interplay between lymphatic development and function in a number of major organ systems.
Collapse
Affiliation(s)
- Brian W Wong
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute, KU Leuven, Herestraat 49 - B912, Leuven 3000, Belgium; Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, VIB, Leuven 3000, Belgium
| | - Annalisa Zecchin
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute, KU Leuven, Herestraat 49 - B912, Leuven 3000, Belgium; Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, VIB, Leuven 3000, Belgium
| | - Melissa García-Caballero
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute, KU Leuven, Herestraat 49 - B912, Leuven 3000, Belgium; Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, VIB, Leuven 3000, Belgium
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, Leuven Cancer Institute, KU Leuven, Herestraat 49 - B912, Leuven 3000, Belgium; Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, VIB, Leuven 3000, Belgium.
| |
Collapse
|
22
|
Borodin YI, Bgatova NP, Nogovitsina SR, Trunov AN, Konenkov VI, Chernykh VV. [Lymphatic system of the eye]. Vestn Oftalmol 2018; 134:86-91. [PMID: 29771890 DOI: 10.17116/oftalma2018134286-90] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Existence of lymphatic outflow of intraocular fluid is still an open question. Identification of the lymphatic capillaries and vessels in various human organs in normal and pathological conditions became possible with discovery of endotheliocyte markers for lymphatic vessels. However, the available information on the presence of lymphatic structures in the human eye is inconsistent and uncertain. The data on lymphatic drainage of the eye is of interest, particularly because it may help understand glaucoma pathogenesis, mechanisms of development of eye inflammatory diseases, and develop pathogenetic therapies. The article reviews literature and presents the authors' own views on lymphatic drainage of the human eye.
Collapse
Affiliation(s)
- Yu I Borodin
- Research Institute of Clinical and Experimental Lymphology, 2 Timakova St., Novosibirsk, Russian Federation, 630060
| | - N P Bgatova
- Research Institute of Clinical and Experimental Lymphology, 2 Timakova St., Novosibirsk, Russian Federation, 630060
| | - S R Nogovitsina
- Research Institute of Clinical and Experimental Lymphology, 2 Timakova St., Novosibirsk, Russian Federation, 630060
| | - A N Trunov
- Novosibirsk Branch of S. Fyodorov Eye Microsurgery Federal State Institution, 10 Kolkhidskaya St., Novosibirsk, Russian Federation, 630096
| | - V I Konenkov
- Research Institute of Clinical and Experimental Lymphology, 2 Timakova St., Novosibirsk, Russian Federation, 630060
| | - V V Chernykh
- Novosibirsk Branch of S. Fyodorov Eye Microsurgery Federal State Institution, 10 Kolkhidskaya St., Novosibirsk, Russian Federation, 630096
| |
Collapse
|
23
|
Aliancy J, Stamer WD, Wirostko B. A Review of Nitric Oxide for the Treatment of Glaucomatous Disease. Ophthalmol Ther 2017; 6:221-232. [PMID: 28584936 PMCID: PMC5693832 DOI: 10.1007/s40123-017-0094-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Indexed: 12/21/2022] Open
Abstract
Glaucoma is the leading cause of irreversible blindness worldwide, affecting 64.3 million people. An estimated 60.5 million people are affected by primary open angle glaucoma globally, and this will increase to 111.8 million by 2040. The definition of glaucoma has evolved greatly over time. Although multiple risk factors such as ischemia, inflammation, myopia, race, age and low ocular perfusion pressure may play a role, intraocular pressure (IOP) is still the main risk factor we can easily identify and modify. Currently, both medical and surgical interventions aim to reduce IOP. Effective IOP reduction controls and prevents the progression in many cases of glaucoma. Although this multifactorial disease's true pathophysiology is difficult to elucidate, physiologic mediators including nitric oxide (NO) are being evaluated as novel ways to impact progression by both lowering IOP and improving optic nerve head perfusion. Latanoprostene bunod 0.024% is an emerging therapeutic agent that has shown promise in clinical trials. As a nitric oxide-donating prostaglandin F2-alpha receptor agonist, it has proven to effectively, and with good tolerability, reduce IOP in glaucoma and ocular hypertensive patients. Latanoprostene bunod capitalizes on NO's ability to modulate the conventional aqueous humor outflow system, directly improving outflow through the trabecular meshwork, Schlemm's canal and distal scleral vessels. Importantly, targeting the conventional outflow tissues with NO-donating drugs represents an opportunity to restore outflow function, which will most likely have a beneficial consequence of additional IOP-lowering effects with dampening of diurnal and other IOP fluctuations, the benefit of a healthy trabecular meshwork.
Collapse
Affiliation(s)
- Joah Aliancy
- Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | | |
Collapse
|
24
|
Thomson BR, Souma T, Tompson SW, Onay T, Kizhatil K, Siggs OM, Feng L, Whisenhunt KN, Yanovitch TL, Kalaydjieva L, Azmanov DN, Finzi S, Tanna CE, Hewitt AW, Mackey DA, Bradfield YS, Souzeau E, Javadiyan S, Wiggs JL, Pasutto F, Liu X, John SW, Craig JE, Jin J, Young TL, Quaggin SE. Angiopoietin-1 is required for Schlemm's canal development in mice and humans. J Clin Invest 2017; 127:4421-4436. [PMID: 29106382 DOI: 10.1172/jci95545] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/26/2017] [Indexed: 02/06/2023] Open
Abstract
Primary congenital glaucoma (PCG) is a leading cause of blindness in children worldwide and is caused by developmental defects in 2 aqueous humor outflow structures, Schlemm's canal (SC) and the trabecular meshwork. We previously identified loss-of-function mutations in the angiopoietin (ANGPT) receptor TEK in families with PCG and showed that ANGPT/TEK signaling is essential for SC development. Here, we describe roles for the major ANGPT ligands in the development of the aqueous outflow pathway. We determined that ANGPT1 is essential for SC development, and that Angpt1-knockout mice form a severely hypomorphic canal with elevated intraocular pressure. By contrast, ANGPT2 was dispensable, although mice deficient in both Angpt1 and Angpt2 completely lacked SC, indicating that ANGPT2 compensates for the loss of ANGPT1. In addition, we identified 3 human subjects with rare ANGPT1 variants within an international cohort of 284 PCG patients. Loss of function in 2 of the 3 patient alleles was observed by functional analysis of ANGPT1 variants in a combined in silico, in vitro, and in vivo approach, supporting a causative role for ANGPT1 in disease. By linking ANGPT1 with PCG, these results highlight the importance of ANGPT/TEK signaling in glaucoma pathogenesis and identify a candidate target for therapeutic development.
Collapse
Affiliation(s)
- Benjamin R Thomson
- Feinberg Cardiovascular Research Institute and.,Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Tomokazu Souma
- Feinberg Cardiovascular Research Institute and.,Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Stuart W Tompson
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Tuncer Onay
- Feinberg Cardiovascular Research Institute and.,Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | | | - Owen M Siggs
- Department of Ophthalmology, Flinders University, Adelaide, South Australia, Australia
| | - Liang Feng
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Kristina N Whisenhunt
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Tammy L Yanovitch
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma, Oklahoma City, Oklahoma, USA
| | - Luba Kalaydjieva
- Harry Perkins Institute of Medical Research and Centre for Medical Research, University of Western Australia, Perth, Western Australia, Australia
| | - Dimitar N Azmanov
- Harry Perkins Institute of Medical Research and Centre for Medical Research, University of Western Australia, Perth, Western Australia, Australia.,Department of Diagnostic Genomics, PathWest, QEII Medical Centre, Perth, Western Australia, Australia
| | - Simone Finzi
- Department of Ophthalmology, Hospital das Clínicas of University of São Paulo, São Paulo, Brazil
| | - Christine E Tanna
- Feinberg Cardiovascular Research Institute and.,Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Alex W Hewitt
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia.,Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
| | - David A Mackey
- Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia, Australia.,Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
| | - Yasmin S Bradfield
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Emmanuelle Souzeau
- Department of Ophthalmology, Flinders University, Adelaide, South Australia, Australia
| | - Shari Javadiyan
- Department of Ophthalmology, Flinders University, Adelaide, South Australia, Australia
| | - Janey L Wiggs
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA
| | - Francesca Pasutto
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Xiaorong Liu
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Simon Wm John
- Howard Hughes Medical Institute and The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Adelaide, South Australia, Australia
| | - Jing Jin
- Feinberg Cardiovascular Research Institute and.,Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Terri L Young
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Susan E Quaggin
- Feinberg Cardiovascular Research Institute and.,Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| |
Collapse
|
25
|
Kim J, Park DY, Bae H, Park DY, Kim D, Lee CK, Song S, Chung TY, Lim DH, Kubota Y, Hong YK, He Y, Augustin HG, Oliver G, Koh GY. Impaired angiopoietin/Tie2 signaling compromises Schlemm's canal integrity and induces glaucoma. J Clin Invest 2017; 127:3877-3896. [PMID: 28920924 PMCID: PMC5617682 DOI: 10.1172/jci94668] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/18/2017] [Indexed: 12/14/2022] Open
Abstract
Primary open-angle glaucoma (POAG) is often caused by elevated intraocular pressure (IOP), which arises due to increased resistance to aqueous humor outflow (AHO). Aqueous humor flows through Schlemm's canal (SC), a lymphatic-like vessel encircling the cornea, and via intercellular spaces of ciliary muscle cells. However, the mechanisms underlying increased AHO resistance are poorly understood. Here, we demonstrate that signaling between angiopoietin (Angpt) and the Angpt receptor Tie2, which is critical for SC formation, is also indispensable for maintaining SC integrity during adulthood. Deletion of Angpt1/Angpt2 or Tie2 in adult mice severely impaired SC integrity and transcytosis, leading to elevated IOP, retinal neuron damage, and impairment of retinal ganglion cell function, all hallmarks of POAG in humans. We found that SC integrity is maintained by interconnected and coordinated functions of Angpt-Tie2 signaling, AHO, and Prox1 activity. These functions diminish in the SC during aging, leading to impaired integrity and transcytosis. Intriguingly, Tie2 reactivation using a Tie2 agonistic antibody rescued the POAG phenotype in Angpt1/Angpt2-deficient mice and rejuvenated the SC in aged mice. These results indicate that the Angpt-Tie2 system is essential for SC integrity. The impairment of this system underlies POAG-associated pathogenesis, supporting the possibility that Tie2 agonists could be a therapeutic option for glaucoma.
Collapse
Affiliation(s)
- Jaeryung Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Dae-Young Park
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Hosung Bae
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Do Young Park
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Dongkyu Kim
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
| | - Choong-kun Lee
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Sukhyun Song
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
| | - Tae-Young Chung
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Dong Hui Lim
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
- Department of Preventive Medicine, Catholic University School of Medicine, Seoul, Republic of Korea
| | - Yoshiaki Kubota
- The Laboratory of Vascular Biology, School of Medicine, Keio University, Tokyo, Japan
| | - Young-Kwon Hong
- Department of Surgery, Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Yulong He
- Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, Soochow University, Suzhou, China
| | - Hellmut G. Augustin
- Division of Vascular Oncology and Metastasis, German Cancer Research Center Heidelberg (DKFZ-ZMBH Alliance), Heidelberg, Germany
| | - Guillermo Oliver
- Center for Vascular and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Gou Young Koh
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Vascular Research, Institute for Basic Science, Daejeon, Republic of Korea
| |
Collapse
|
26
|
Bernier-Latmani J, Petrova TV. All TIEd up: mechanisms of Schlemm's canal maintenance. J Clin Invest 2017; 127:3594-3597. [PMID: 28920923 DOI: 10.1172/jci96840] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Glaucoma is a leading cause of blindness, with an estimated world-wide prevalence of 3.5% in members of the population older than 40 years of age. Elevated intraocular pressure as the result of abnormal resistance to aqueous humor drainage is a major contributing, and the only preventable, factor in glaucoma development. Schlemm's canal (SC), a lymphatic-like vessel encircling the anterior portion of the eye, plays a key role in promoting aqueous humor outflow and maintenance of normal intraocular pressure. The risk of developing glaucoma increases with age; therefore, understanding mechanisms of SC maintenance and how aging affects SC function are of special importance, both for prevention and novel treatment approaches to glaucoma. Using a compelling array of genetic models, Kim et al. report in this issue of the JCI that continuous angiopoietin/TIE2 signaling is required for maintaining SC identity and integrity during adulthood and show that its age-related changes can be rescued by a TIE2 agonistic antibody.
Collapse
Affiliation(s)
- Jeremiah Bernier-Latmani
- Department of Fundamental Oncology, Ludwig Cancer Research, Lausanne Branch, and Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Epalinges, Switzerland
| | - Tatiana V Petrova
- Department of Fundamental Oncology, Ludwig Cancer Research, Lausanne Branch, and Institute of Pathology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Epalinges, Switzerland.,Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| |
Collapse
|
27
|
Reina-Torres E, Wen JC, Liu KC, Li G, Sherwood JM, Chang JYH, Challa P, Flügel-Koch CM, Stamer WD, Allingham RR, Overby DR. VEGF as a Paracrine Regulator of Conventional Outflow Facility. Invest Ophthalmol Vis Sci 2017; 58:1899-1908. [PMID: 28358962 PMCID: PMC5374885 DOI: 10.1167/iovs.16-20779] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Purpose Vascular endothelial growth factor (VEGF) regulates microvascular endothelial permeability, and the permeability of Schlemm's canal (SC) endothelium influences conventional aqueous humor outflow. We hypothesize that VEGF signaling regulates outflow facility. Methods We measured outflow facility (C) in enucleated mouse eyes perfused with VEGF-A164a, VEGF-A165b, VEGF-D, or inhibitors to VEGF receptor 2 (VEGFR-2). We monitored VEGF-A secretion from human trabecular meshwork (TM) cells by ELISA after 24 hours of static culture or cyclic stretch. We used immunofluorescence microscopy to localize VEGF-A protein within the TM of mice. Results VEGF-A164a increased C in enucleated mouse eyes. Cyclic stretch increased VEGF-A secretion by human TM cells, which corresponded to VEGF-A localization in the TM of mice. Blockade of VEGFR-2 decreased C, using either of the inhibitors SU5416 or Ki8751 or the inactive splice variant VEGF-A165b. VEGF-D increased C, which could be blocked by Ki8751. Conclusions VEGF is a paracrine regulator of conventional outflow facility that is secreted by TM cells in response to mechanical stress. VEGF affects facility via VEGFR-2 likely at the level of SC endothelium. Disruption of VEGF signaling in the TM may explain why anti-VEGF therapy is associated with decreased outflow facility and sustained ocular hypertension.
Collapse
Affiliation(s)
- Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Joanne C Wen
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Katy C Liu
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Guorong Li
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Jason Y H Chang
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Pratap Challa
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Cassandra M Flügel-Koch
- Department of Anatomy II, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - R Rand Allingham
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom
| |
Collapse
|
28
|
van Lessen M, Shibata-Germanos S, van Impel A, Hawkins TA, Rihel J, Schulte-Merker S. Intracellular uptake of macromolecules by brain lymphatic endothelial cells during zebrafish embryonic development. eLife 2017; 6. [PMID: 28498105 PMCID: PMC5457137 DOI: 10.7554/elife.25932] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/11/2017] [Indexed: 01/01/2023] Open
Abstract
The lymphatic system controls fluid homeostasis and the clearance of macromolecules from interstitial compartments. In mammals brain lymphatics were only recently discovered, with significant implications for physiology and disease. We examined zebrafish for the presence of brain lymphatics and found loosely connected endothelial cells with lymphatic molecular signature covering parts of the brain without forming endothelial tubular structures. These brain lymphatic endothelial cells (BLECs) derive from venous endothelium, are distinct from macrophages, and are sensitive to loss of Vegfc. BLECs endocytose macromolecules in a selective manner, which can be blocked by injection of mannose receptor ligands. This first report on brain lymphatic endothelial cells in a vertebrate embryo identifies cells with unique features, including the uptake of macromolecules at a single cell level. Future studies will address whether this represents an uptake mechanism that is conserved in mammals and how these cells affect functions of the embryonic and adult brain. DOI:http://dx.doi.org/10.7554/eLife.25932.001
Collapse
Affiliation(s)
- Max van Lessen
- Institute of Cardiovascular Organogenesis and Regeneration, WWU Münster, Münster, Germany.,Faculty of Medicine, WWU Münster, Münster, Germany.,Cells-in-Motion Cluster of Excellence, WWU Münster, Münster, Germany
| | | | - Andreas van Impel
- Institute of Cardiovascular Organogenesis and Regeneration, WWU Münster, Münster, Germany.,Faculty of Medicine, WWU Münster, Münster, Germany.,Cells-in-Motion Cluster of Excellence, WWU Münster, Münster, Germany
| | - Thomas A Hawkins
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Jason Rihel
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Stefan Schulte-Merker
- Institute of Cardiovascular Organogenesis and Regeneration, WWU Münster, Münster, Germany.,Faculty of Medicine, WWU Münster, Münster, Germany.,Cells-in-Motion Cluster of Excellence, WWU Münster, Münster, Germany
| |
Collapse
|
29
|
Carreon TA, Edwards G, Wang H, Bhattacharya SK. Segmental outflow of aqueous humor in mouse and human. Exp Eye Res 2017; 158:59-66. [PMID: 27498226 PMCID: PMC5290258 DOI: 10.1016/j.exer.2016.08.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 07/08/2016] [Accepted: 08/01/2016] [Indexed: 12/28/2022]
Abstract
The main and only modifiable risk factor in glaucoma, the group of usually late onset progressive and irreversible blinding optic neuropathies, is elevated intraocular pressure (IOP). The increase in IOP is due to impeded aqueous humor (AH) outflow through the conventional pathway. The aberrant increased resistance at the trabecular meshwork (TM), the filter-like region in the anterior eye chamber is the major contributory factor in causing the impeded outflow. In normal as well as in glaucoma eyes the regions of the TM are divided into areas of high and low flow. The collector channels and distal outflow regions are now increasingly being recognized as potential players in contributing to impede AH outflow. Structural and molecular make-up contributing to the segmental blockage to outflow is likely to provide greater insight. Establishing segmental blockage to outflow in model systems of glaucoma such as the mouse in parallel to human eyes will expand our repertoire of tools for investigation. Further study into this area of interest has the potential to ultimately lead to the development of new therapeutics focused on lowering IOP by targeting the various components of segmental blockage of outflow in the TM and in the distal outflow region.
Collapse
Affiliation(s)
- Teresia A Carreon
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, 33136, USA; Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, 33136, USA
| | - Genea Edwards
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, 33136, USA; Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, 33136, USA
| | - Haiyan Wang
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, 33136, USA; Shanghai First People's Hospital Affiliated to Jiaotong University, Shanghai, 200080, China
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, 33136, USA; Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, 33136, USA.
| |
Collapse
|
30
|
Lohrberg M, Wilting J. The lymphatic vascular system of the mouse head. Cell Tissue Res 2016; 366:667-677. [PMID: 27599481 PMCID: PMC5121175 DOI: 10.1007/s00441-016-2493-8] [Citation(s) in RCA: 40] [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: 04/21/2016] [Accepted: 08/15/2016] [Indexed: 12/25/2022]
Abstract
Histological studies of the lymphatic vascular system in adult mice are hampered because bones cannot be sectioned properly. Here, we decalcified the heads of 14-day-old mice, embedded them in paraffin and stained resultant serial sections with the lymphendothelial-specific antibodies Lyve-1 and Podoplanin. We show that the tissues with the highest lymphatic vascular density are the dermis and the oral mucous membranes. In contrast, the nasal mucous membrane is devoid of lymphatics, except for its most basal parts below the vomeronasal organ. The inferior nasal turbinate contains numerous lymphatics and is connected to the nasolacrimal duct (NLD), which is ensheathed by a dense network of lymphatics. The lymphatics of the eye lids and conjunctiva are connected to those of the inferior nasal turbinate. We suggest that cerebro-spinal fluid (CSF) can drain via the optic nerve and NLD lymphatics, whereas CSF drained via the Fila olfactoria into the nasal mucous membrane is used for moisturization of the respiratory air. Tongue, palatine and buccal mucous membranes possess numerous lymphatics, whereas the dental pulp has none. Lymphatics are present in the maxillary gland and close to the temporomandibular joint, suggesting the augmentation of lymph flow by chewing and yawning. Lymphatics can also be found in the dura mater and in the dural septae entering into deeper parts of the brain. Our findings are discussed with regard to CSF drainage and potential routes for ocular tumor dissemination.
Collapse
Affiliation(s)
- Melanie Lohrberg
- Department of Anatomy and Cell Biology, University Medical School Göttingen, Göttingen, Germany.
| | - Jörg Wilting
- Department of Anatomy and Cell Biology, University Medical School Göttingen, Göttingen, Germany
| |
Collapse
|
31
|
Prasanna G, Li B, Mogi M, Rice DS. Pharmacology of novel intraocular pressure-lowering targets that enhance conventional outflow facility: Pitfalls, promises and what lies ahead? Eur J Pharmacol 2016; 787:47-56. [DOI: 10.1016/j.ejphar.2016.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 02/15/2016] [Accepted: 03/01/2016] [Indexed: 12/18/2022]
|
32
|
Bentley MD, Hann CR, Fautsch MP. Anatomical Variation of Human Collector Channel Orifices. Invest Ophthalmol Vis Sci 2016; 57:1153-9. [PMID: 26975026 PMCID: PMC4794087 DOI: 10.1167/iovs.15-17753] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose To examine the anatomical variation of normal human collector channel orifices and their relationship with Schlemm's canal. Methods Ten human anterior segments fixed by immersion or perfusion were dissected radially and further divided by fine dissection into corresponding inner and outer wall segments. The tissues were dehydrated, critical-point dried, sputter coated, and examined by scanning electron microscopy. Images were obtained at magnifications from ×200 to ×10,000. Selected radial collector channel regions were processed for plastic embedding. Results Two classes of collector channel orifices were identified. Simple oval orifices (54.7 ± 4.6–μm diameter) were lined with endothelial cells and most often occurred on a planar region of Schlemm's canal outer wall. Complex orifices (62.7 ± 3.4–μm diameter) were often found associated with septal columns and bridges, and typically covered with flap-like structures (10–40 μm) that extended between the inner and outer wall and over the collector channel orifices. Both simple and complex orifices had complete or partial lip-like rims. In orifices with partial rims, a trough-like groove was often visible on the outer wall surface opposite the lip. Transected septa and inner and outer wall adhesion sites were often found in association with complex collector channel orifices. Conclusions Collector channel orifice structure varied from simple ovals to complex tethered flaps and bridges. Collector channel orifices with complex flaps connect the inner and outer walls of Schlemm's canal, and may serve to enhance and regulate aqueous outflow in these regions.
Collapse
Affiliation(s)
- Michael D Bentley
- Department of Biological Sciences Minnesota State University, Mankato, Minnesota, United States
| | - Cheryl R Hann
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| |
Collapse
|
33
|
Giblin JP, Comes N, Strauss O, Gasull X. Ion Channels in the Eye: Involvement in Ocular Pathologies. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:157-231. [PMID: 27038375 DOI: 10.1016/bs.apcsb.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.
Collapse
Affiliation(s)
- Jonathan P Giblin
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Comes
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Xavier Gasull
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
| |
Collapse
|
34
|
Roy Chowdhury U, Hann CR, Stamer WD, Fautsch MP. Aqueous humor outflow: dynamics and disease. Invest Ophthalmol Vis Sci 2015; 56:2993-3003. [PMID: 26024085 DOI: 10.1167/iovs.15-16744] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Affiliation(s)
- Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Cheryl R Hann
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| |
Collapse
|
35
|
Dautriche CN, Tian Y, Xie Y, Sharfstein ST. A Closer Look at Schlemm's Canal Cell Physiology: Implications for Biomimetics. J Funct Biomater 2015; 6:963-85. [PMID: 26402712 PMCID: PMC4598687 DOI: 10.3390/jfb6030963] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/10/2015] [Accepted: 09/06/2015] [Indexed: 12/13/2022] Open
Abstract
Among ocular pathologies, glaucoma is the second leading cause of progressive vision loss, expected to affect 80 million people worldwide by 2020. A primary cause of glaucoma appears to be damage to the conventional outflow tract. Conventional outflow tissues, a composite of the trabecular meshwork and the Schlemm's canal, regulate and maintain homeostatic responses to intraocular pressure. In glaucoma, filtration of aqueous humor into the Schlemm's canal is hindered, leading to an increase in intraocular pressure and subsequent damage to the optic nerve, with progressive vision loss. The Schlemm's canal encompasses a unique endothelium. Recent advances in culturing and manipulating Schlemm's canal cells have elucidated several aspects of their physiology, including ultrastructure, cell-specific marker expression, and biomechanical properties. This review highlights these advances and discusses implications for engineering a 3D, biomimetic, in vitro model of the Schlemm's canal endothelium to further advance glaucoma research, including drug testing and gene therapy screening.
Collapse
Affiliation(s)
- Cula N Dautriche
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
| | - Yangzi Tian
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
| | - Yubing Xie
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
| | - Susan T Sharfstein
- State University of New York (SUNY) Polytechnic Institute, Colleges of Nanoscale Science and Engineering, 257 Fuller Road, Albany, NY 12203, USA.
| |
Collapse
|
36
|
Chang JYH, Stamer WD, Bertrand J, Read AT, Marando CM, Ethier CR, Overby DR. Role of nitric oxide in murine conventional outflow physiology. Am J Physiol Cell Physiol 2015; 309:C205-14. [PMID: 26040898 DOI: 10.1152/ajpcell.00347.2014] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 05/30/2015] [Indexed: 11/22/2022]
Abstract
Elevated intraocular pressure (IOP) is the main risk factor for glaucoma. Exogenous nitric oxide (NO) decreases IOP by increasing outflow facility, but whether endogenous NO production contributes to the physiological regulation of outflow facility is unclear. Outflow facility was measured by pressure-controlled perfusion in ex vivo eyes from C57BL/6 wild-type (WT) or transgenic mice expressing human endothelial NO synthase (eNOS) fused to green fluorescent protein (GFP) superimposed on the endogenously expressed murine eNOS (eNOS-GFPtg). In WT mice, exogenous NO delivered by 100 μM S-nitroso-N-acetylpenicillamine (SNAP) increased outflow facility by 62 ± 28% (SD) relative to control eyes perfused with the inactive SNAP analog N-acetyl-d-penicillamine (NAP; n = 5, P = 0.016). In contrast, in eyes from eNOS-GFPtg mice, SNAP had no effect on outflow facility relative to NAP (-9 ± 4%, P = 0.40). In WT mice, the nonselective NOS inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME, 10 μM) decreased outflow facility by 36 ± 13% (n = 5 each, P = 0.012), but 100 μM l-NAME had no detectable effect on outflow facility (-16 ± 5%, P = 0.22). An eNOS-selective inhibitor (cavtratin, 50 μM) decreased outflow facility by 19 ± 12% in WT (P = 0.011) and 39 ± 25% in eNOS-GFPtg (P = 0.014) mice. In the conventional outflow pathway of eNOS-GFPtg mice, eNOS-GFP expression was localized to endothelial cells lining Schlemm's canal and the downstream vessels, with no apparent expression in the trabecular meshwork. These results suggest that endogenous NO production by eNOS within endothelial cells of Schlemm's canal or downstream vessels contributes to the physiological regulation of aqueous humor outflow facility in mice, representing a viable strategy to more successfully lower IOP in glaucoma.
Collapse
Affiliation(s)
- Jason Y H Chang
- Department of Bioengineering, Imperial College London, London, United Kingdom; Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina
| | - Jacques Bertrand
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - A Thomas Read
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada; and
| | - Catherine M Marando
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - C Ross Ethier
- Department of Bioengineering, Imperial College London, London, United Kingdom; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom;
| |
Collapse
|
37
|
Hann CR, Fautsch MP. Recent Developments in Understanding the Role of Aqueous Humor Outflow in Normal and Primary Open Angle Glaucoma. CURRENT OPHTHALMOLOGY REPORTS 2015; 3:67-73. [PMID: 26236568 DOI: 10.1007/s40135-015-0072-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Primary open angle glaucoma (POAG) is the second leading cause of blindness in the world's rapidly aging population. POAG is characterized by progressive degeneration of neural structures in the posterior segment, often associated with a concomitant elevation of intraocular pressure. Changes in IOP are believed to be caused by a disruption in the normal outflow of aqueous humor. This article reviews recent research associated with normal and POAG aqueous humor outflow. Novel findings elucidating biochemical and pathological changes in the ocular tissues affected in POAG are presented. Stem cell research, identification of lymphatic markers, and increased use of mouse models give researchers exciting new tools to understand aqueous humor outflow, changes associated with POAG and identify underlying causes of the disease.
Collapse
Affiliation(s)
- Cheryl R Hann
- Department of Ophthalmology Mayo Clinic 200 First Street SW Rochester, MN 55905 USA
| | - Michael P Fautsch
- Department of Ophthalmology Mayo Clinic 200 First Street SW Rochester, MN 55905 USA
| |
Collapse
|
38
|
Schmidl D, Schmetterer L, Garhöfer G, Popa-Cherecheanu A. Pharmacotherapy of glaucoma. J Ocul Pharmacol Ther 2015; 31:63-77. [PMID: 25587905 PMCID: PMC4346603 DOI: 10.1089/jop.2014.0067] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 10/31/2014] [Indexed: 12/25/2022] Open
Abstract
Glaucoma is a group of diseases involving the optic nerve and associated structures, which is characterized by progressive visual field loss and typical changes of the optic nerve head (ONH). The only known treatment of the disease is reduction of intraocular pressure (IOP), which has been shown to reduce glaucoma progression in a variety of large-scale clinical trials. Nowadays, a relatively wide array of topical antiglaucoma drugs is available, including prostaglandin analogues, carbonic anhydrase inhibitors, beta-receptor antagonists, adrenergic agonists, and parasympathomimetics. In clinical routine, this allows for individualized treatment taking risk factors, efficacy, and safety into account. A major challenge is related to adherence to therapy. Sustained release devices may help minimize this problem but are not yet available for clinical routine use. Another hope arises from non-IOP-related treatment concepts. In recent years, much knowledge has been gained regarding the molecular mechanisms that underlie the disease process in glaucoma. This also strengthens the hope that glaucoma therapy beyond IOP lowering will become available. Implementing this concept with clinical trials remains, however, a challenge.
Collapse
Affiliation(s)
- Doreen Schmidl
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Leopold Schmetterer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | | |
Collapse
|
39
|
Stamer WD, Braakman ST, Zhou EH, Ethier CR, Fredberg JJ, Overby DR, Johnson M. Biomechanics of Schlemm's canal endothelium and intraocular pressure reduction. Prog Retin Eye Res 2015; 44:86-98. [PMID: 25223880 PMCID: PMC4268318 DOI: 10.1016/j.preteyeres.2014.08.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 12/29/2022]
Abstract
Ocular hypertension in glaucoma develops due to age-related cellular dysfunction in the conventional outflow tract, resulting in increased resistance to aqueous humor outflow. Two cell types, trabecular meshwork (TM) and Schlemm's canal (SC) endothelia, interact in the juxtacanalicular tissue (JCT) region of the conventional outflow tract to regulate outflow resistance. Unlike endothelial cells lining the systemic vasculature, endothelial cells lining the inner wall of SC support a transcellular pressure gradient in the basal to apical direction, thus acting to push the cells off their basal lamina. The resulting biomechanical strain in SC cells is quite large and is likely to be an important determinant of endothelial barrier function, outflow resistance and intraocular pressure. This review summarizes recent work demonstrating how biomechanical properties of SC cells impact glaucoma. SC cells are highly contractile, and such contraction greatly increases cell stiffness. Elevated cell stiffness in glaucoma may reduce the strain experienced by SC cells, decrease the propensity of SC cells to form pores, and thus impair the egress of aqueous humor from the eye. Furthermore, SC cells are sensitive to the stiffness of their local mechanical microenvironment, altering their own cell stiffness and modulating gene expression in response. Significantly, glaucomatous SC cells appear to be hyper-responsive to substrate stiffness. Thus, evidence suggests that targeting the material properties of SC cells will have therapeutic benefits for lowering intraocular pressure in glaucoma.
Collapse
Affiliation(s)
- W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA; Department of Biomedical Engineering, Duke University, Durham, NC, 27710, USA.
| | - Sietse T Braakman
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - Enhua H Zhou
- Department of Ophthalmology, Novartis Institutes of BioMedical Research, Cambridge, MA 02139, USA
| | - C Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA; Department of Ophthalmology, Emory University, Atlanta, GA 30322, USA
| | - Jeffrey J Fredberg
- Program in Molecular and Integrative Physiological Sciences, Harvard School of Public Health, Boston, MA 02115, USA; Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - Mark Johnson
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, US; Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA; Department of Ophthalmology Engineering, Northwestern University, Chicago, IL, USA
| |
Collapse
|
40
|
Aspelund A, Tammela T, Antila S, Nurmi H, Leppänen VM, Zarkada G, Stanczuk L, Francois M, Mäkinen T, Saharinen P, Immonen I, Alitalo K. The Schlemm's canal is a VEGF-C/VEGFR-3-responsive lymphatic-like vessel. J Clin Invest 2014; 124:3975-86. [PMID: 25061878 PMCID: PMC4153703 DOI: 10.1172/jci75395] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/30/2014] [Indexed: 12/21/2022] Open
Abstract
In glaucoma, aqueous outflow into the Schlemm's canal (SC) is obstructed. Despite striking structural and functional similarities with the lymphatic vascular system, it is unknown whether the SC is a blood or lymphatic vessel. Here, we demonstrated the expression of lymphatic endothelial cell markers by the SC in murine and zebrafish models as well as in human eye tissue. The initial stages of SC development involved induction of the transcription factor PROX1 and the lymphangiogenic receptor tyrosine kinase VEGFR-3 in venous endothelial cells in postnatal mice. Using gene deletion and function-blocking antibodies in mice, we determined that the lymphangiogenic growth factor VEGF-C and its receptor, VEGFR-3, are essential for SC development. Delivery of VEGF-C into the adult eye resulted in sprouting, proliferation, and growth of SC endothelial cells, whereas VEGF-A obliterated the aqueous outflow system. Furthermore, a single injection of recombinant VEGF-C induced SC growth and was associated with trend toward a sustained decrease in intraocular pressure in adult mice. These results reveal the evolutionary conservation of the lymphatic-like phenotype of the SC, implicate VEGF-C and VEGFR-3 as critical regulators of SC lymphangiogenesis, and provide a basis for further studies on therapeutic manipulation of the SC with VEGF-C in glaucoma treatment.
Collapse
|
41
|
Karpinich NO, Caron KM. Schlemm's canal: more than meets the eye, lymphatics in disguise. J Clin Invest 2014; 124:3701-3. [PMID: 25061871 PMCID: PMC4151199 DOI: 10.1172/jci77507] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Schlemm's canal (SC) is a unique vascular structure that functions to maintain fluid homeostasis by draining aqueous humor from the eye into the systemic circulation. The endothelium lining the inner wall of SC has both blood and lymphatic vascular characteristics, thus prompting exploration of the development and regulation of this unique channel. In this issue of the JCI, back-to-back papers by Aspelund et al. and Park et al. detail the mechanisms of SC development, which includes a lymphatic reprogramming that is necessary to maintain proper function. Furthermore, both groups exploit the lymph-like qualities of this canal: they identify VEGF-C as a potential therapeutic for glaucoma and suggest that expression of PROX1, a marker of lymphatic fate, could also serve as a biosensor for monitoring SC integrity. These studies provide substantial insight into the molecular and cellular pathways that govern SC development and reveal that ocular pathology is associated with deregulation of the lymph-like characteristics of SC.
Collapse
Affiliation(s)
- Natalie O. Karpinich
- Department of Cell Biology and Physiology and Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Kathleen M. Caron
- Department of Cell Biology and Physiology and Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| |
Collapse
|
42
|
Park DY, Lee J, Park I, Choi D, Lee S, Song S, Hwang Y, Hong KY, Nakaoka Y, Makinen T, Kim P, Alitalo K, Hong YK, Koh GY. Lymphatic regulator PROX1 determines Schlemm's canal integrity and identity. J Clin Invest 2014; 124:3960-74. [PMID: 25061877 DOI: 10.1172/jci75392] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/30/2014] [Indexed: 12/30/2022] Open
Abstract
Schlemm's canal (SC) is a specialized vascular structure in the eye that functions to drain aqueous humor from the intraocular chamber into systemic circulation. Dysfunction of SC has been proposed to underlie increased aqueous humor outflow (AHO) resistance, which leads to elevated ocular pressure, a factor for glaucoma development in humans. Here, using lymphatic and blood vasculature reporter mice, we determined that SC, which originates from blood vessels during the postnatal period, acquires lymphatic identity through upregulation of prospero homeobox protein 1 (PROX1), the master regulator of lymphatic development. SC expressed lymphatic valve markers FOXC2 and integrin α9 and exhibited continuous vascular endothelial-cadherin (VE-cadherin) junctions and basement membrane, similar to collecting lymphatics. SC notably lacked luminal valves and expression of the lymphatic endothelial cell markers podoplanin and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1). Using an ocular puncture model, we determined that reduced AHO altered the fate of SC both during development and under pathologic conditions; however, alteration of VEGF-C/VEGFR3 signaling did not modulate SC integrity and identity. Intriguingly, PROX1 expression levels linearly correlated with SC functionality. For example, PROX1 expression was reduced or undetectable under pathogenic conditions and in deteriorated SCs. Collectively, our data indicate that PROX1 is an accurate and reliable biosensor of SC integrity and identity.
Collapse
|
43
|
Kizhatil K, Ryan M, Marchant JK, Henrich S, John SWM. Schlemm's canal is a unique vessel with a combination of blood vascular and lymphatic phenotypes that forms by a novel developmental process. PLoS Biol 2014; 12:e1001912. [PMID: 25051267 PMCID: PMC4106723 DOI: 10.1371/journal.pbio.1001912] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 06/12/2014] [Indexed: 01/04/2023] Open
Abstract
A draining vessel in the eye arises via a novel hybrid process of vascular development and is important for understanding ocular fluid homeostasis and glaucoma. Schlemm's canal (SC) plays central roles in ocular physiology. These roles depend on the molecular phenotypes of SC endothelial cells (SECs). Both the specific phenotype of SECs and development of SC remain poorly defined. To allow a modern and extensive analysis of SC and its origins, we developed a new whole-mount procedure to visualize its development in the context of surrounding tissues. We then applied genetic lineage tracing, specific-fluorescent reporter genes, immunofluorescence, high-resolution confocal microscopy, and three-dimensional (3D) rendering to study SC. Using these techniques, we show that SECs have a unique phenotype that is a blend of both blood and lymphatic endothelial cell phenotypes. By analyzing whole mounts of postnatal mouse eyes progressively to adulthood, we show that SC develops from blood vessels through a newly discovered process that we name “canalogenesis.” Functional inhibition of KDR (VEGFR2), a critical receptor in initiating angiogenesis, shows that this receptor is required during canalogenesis. Unlike angiogenesis and similar to stages of vasculogenesis, during canalogenesis tip cells divide and form branched chains prior to vessel formation. Differing from both angiogenesis and vasculogenesis, during canalogenesis SECs express Prox1, a master regulator of lymphangiogenesis and lymphatic phenotypes. Thus, SC development resembles a blend of vascular developmental programs. These advances define SC as a unique vessel with a combination of blood vascular and lymphatic phenotypes. They are important for dissecting its functions that are essential for ocular health and normal vision. Schlemm's canal serves as a drainage tube for fluid from the anterior chamber of the eye and is directly relevant to glaucoma, a disease that causes vision loss in over 70 million people. Aqueous humor enters the canal and then drains into connected veins. Molecular understanding of the development of Schlemm's canal and its drainage functions has remained limited. We provide a detailed characterization of Schlemm's canal development, and in so doing discover a novel process of vascular development that we name “canalogenesis.” We show that although the process requires a functional KDR receptor, which is also critical in blood vessel development, the endothelial cells of Schlemm's canal have a unique hybrid molecular phenotype, expressing proteins that are characteristic of both blood and lymphatic vessels. Of note, the expression of Prox1, a master regulator of lymphatic fate, and other lymphatic proteins are largely restricted to specialized cells of the inner wall of Schlemm's canal through which the aqueous humor passes as it exits the eye. Thus, Prox1 and other lymphatic proteins may be critical for the functional specialization of these cells for aqueous humor drainage. Schlemm's canal is thus a unique vessel with a combination of blood vascular and lymphatic characteristics.
Collapse
Affiliation(s)
- Krishnakumar Kizhatil
- The Howard Hughes Medical Institute, and The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Margaret Ryan
- The Howard Hughes Medical Institute, and The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Jeffrey K. Marchant
- Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Stephen Henrich
- The Howard Hughes Medical Institute, and The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Simon W. M. John
- The Howard Hughes Medical Institute, and The Jackson Laboratory, Bar Harbor, Maine, United States of America
- Department of Ophthalmology and Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
44
|
van der Merwe EL, Kidson SH. The three-dimensional organisation of the post-trabecular aqueous outflow pathway and limbal vasculature in the mouse. Exp Eye Res 2014; 125:226-35. [PMID: 24979218 DOI: 10.1016/j.exer.2014.06.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 05/29/2014] [Accepted: 06/13/2014] [Indexed: 11/17/2022]
Abstract
The mouse eye has been used as a model for studies on the microanatomy of the outflow pathways but most of what is known comes from histological sections. These studies have focused mainly on the morphological features of the trabecular meshwork, Schlemm's canal and aqueous channels that link to the superficial episcleral vasculature. However, the anatomical architecture of the aqueous outflow vessels and their relationship to each other and to the general vascular circulation is not well understood. The aim of this study was to provide a detailed description of the microarchitecture of the aqueous outflow vessels and their relationship to the superficial limbal/episcleral vasculature throughout the entire limbus. The aqueous outflow vessels and blood and lymphatic vessels were imaged in PECAM-1 and LYVE-1 immunostained whole anterior segments of adult mice and three-dimensional (3-D) reconstructions of the optical sections were generated to reveal the aqueous, blood and lymphatic architecture. The arterial supply, venous drainage, organisation of perilimbal vasculature, collector channels/aqueous veins and the morphology of Schlemm's canal were revealed in their entirety and the relationships between these structures is described. Schlemm's canal was PECAM-1 positive but there was no affinity for the lymphatic marker LYVE-1. We show that Schlemm's canal is a continuous circular structure and more often seen as a single, broad, varicose vessel with short regions appearing as a plexus. Aqueous veins link Schlemm's canal to the superficial vasculature and there were no direct links seen between the canal and the lymphatic vessels.
Collapse
Affiliation(s)
- Elizabeth L van der Merwe
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925 Cape Town, South Africa.
| | - Susan H Kidson
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925 Cape Town, South Africa; Institute of Infectious Diseases and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory 7925 Cape Town, South Africa
| |
Collapse
|
45
|
Rokicki W, Żaba M, Mrukwa-Kominek E, Wyględowska-Promieńska D, Brzozowa M, Reichman-Warmusz E, Wojnicz R. von Willebrand factor in iris vasculature of glaucoma patients. Med Sci Monit 2014; 20:1051-5. [PMID: 24954072 PMCID: PMC4072563 DOI: 10.12659/msm.890176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Background Previous reports have indicated the role of endothelium disturbances, as expressed by von Willebrand factor (vWF) release, in pathophysiology of glaucoma. The objective of this study was to investigate the vWF expression in iris vasculature of patients with primary open-angle glaucoma (POAG). Material/Methods Immunohistochemistry of vWF expression was performed on cryostat sections of samples collected at the time of peripheral iridectomy and controls collected from dead donors. Results Twenty-seven Caucasians age 66.6±3.7 with 5.8±3.7-year history of treated PAOG and 10 controls age 62.2±1.92 with no history of glaucoma. The percentage of patients who presented normal and up-regulation of vWF phenotype expression differed statistically between examined and control groups: 48% versus 100% (p=0.035, chi-square test with Yates’ correction). Sex, age, glaucoma duration, and visual field quantitative indices had no impact on vWF expression. A significant correlation between mean pre-surgery intraocular pressure and vWF expression was found (Spearman r=0.42, p=0.03). Conclusions Considering the results, it may be suggested that vWF is actively involved in the pathophysiology of glaucoma.
Collapse
Affiliation(s)
- Wojciech Rokicki
- Department and Clinic of Ophthalmology, Medical University of Silesia, Katowice, Poland
| | - Małgorzata Żaba
- Department of Histology and Embryology, Medical University of Silesia, Zabrze, Poland
| | - Ewa Mrukwa-Kominek
- Department and Clinic of Ophthalmology, Medical University of Silesia, Katowice, Poland
| | | | - Marlena Brzozowa
- Department of Histology and Embryology, Medical University of Silesia, Zabrze, Poland
| | | | - Romuald Wojnicz
- Department of Histology and Embryology, Medical University of Silesia, Zabrze, Poland
| |
Collapse
|
46
|
Truong TN, Li H, Hong YK, Chen L. Novel characterization and live imaging of Schlemm's canal expressing Prox-1. PLoS One 2014; 9:e98245. [PMID: 24827370 PMCID: PMC4020937 DOI: 10.1371/journal.pone.0098245] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 04/29/2014] [Indexed: 11/18/2022] Open
Abstract
Schlemm's canal is an important structure of the conventional aqueous humor outflow pathway and is critically involved in regulating the intraocular pressure. In this study, we report a novel finding that prospero homeobox protein 1 (Prox-1), the master control gene for lymphatic development, is expressed in Schlemm's canal. Moreover, we provide a novel in vivo method of visualizing Schlemm's canal using a transgenic mouse model of Prox-1-green fluorescent protein (GFP). The anatomical location of Prox-1+ Schlemm's canal was further confirmed by in vivo gonioscopic examination and ex vivo immunohistochemical analysis. Additionally, we show that the Schlemm's canal is distinguishable from typical lymphatic vessels by lack of lymphatic vessel endothelial hyaluronan receptor (LYVE-1) expression and absence of apparent sprouting reaction when inflammatory lymphangiogenesis occurred in the cornea. Taken together, our findings offer new insights into Schlemm's canal and provide a new experimental model for live imaging of this critical structure to help further our understanding of the aqueous humor outflow. This may lead to new avenues toward the development of novel therapeutic intervention for relevant diseases, most notably glaucoma.
Collapse
Affiliation(s)
- Tan N. Truong
- Graduate Group in Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
| | - Hannah Li
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
| | - Young-Kwon Hong
- Department of Surgery and Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Lu Chen
- Graduate Group in Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
- The Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, United States of America
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: .
| |
Collapse
|
47
|
Stamer WD, Lei Y, Boussommier-Calleja A, Overby DR, Ethier CR. eNOS, a pressure-dependent regulator of intraocular pressure. Invest Ophthalmol Vis Sci 2011; 52:9438-44. [PMID: 22039240 DOI: 10.1167/iovs.11-7839] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Pathology in the primary drainage pathway for aqueous humor in the eye is responsible for ocular hypertension, the only treatable risk factor in patients with glaucoma. Unfortunately, the mechanisms that regulate pressure-dependent drainage of aqueous humor and thus intraocular pressure (IOP) are unknown. To better understand one possible underlying molecular factor that regulates IOP, nitric oxide (NO), pressure-dependent drainage in transgenic mice overexpressing endothelial NO synthase (eNOS) was studied. METHODS IOP was measured by rebound tonometry in mice, and pressure versus flow data were measured by ex vivo perfusion at multiple pressures between 8 and 45 mm Hg, using mock AH ±100 μM L-NAME. A subset of eyes was examined histologically using standard techniques or was assayed for fusion protein expression by Western blot analysis. RESULTS IOP was lower (9.6 ± 2.7 vs. 11.4 ± 2.5 mm Hg; mean ± SD; P = 0.04) and pressure-dependent drainage was higher (0.0154 ± 0.006 vs. 0.0066 ± 0.0009 μL/min/mm Hg; P = 0.002) in the transgenic mice than in the wild-type animals; however, pressure-independent drainage was unaffected. The NOS inhibitor L-NAME normalized pressure-dependent drainage in transgenic animals. For IOP >35 mm Hg, the slope of the pressure-flow curve in wild-type mice increased to match that seen in transgenic mice. Shear stress in the pressure-dependent pathway at elevated pressures was calculated to be in a range known to affect eNOS expression and activity in vascular endothelia. CONCLUSIONS Endothelial NOS overexpression lowers IOP by increasing pressure-dependent drainage in the mouse eye. Data are consistent with NO's having a mechanoregulatory role in aqueous humor dynamics, with eNOS induction at elevated IOPs leading to increased pressure-dependent outflow.
Collapse
Affiliation(s)
- W Daniel Stamer
- Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona, USA.
| | | | | | | | | |
Collapse
|
48
|
Sumida GM, Stamer WD. S1P₂ receptor regulation of sphingosine-1-phosphate effects on conventional outflow physiology. Am J Physiol Cell Physiol 2011; 300:C1164-71. [PMID: 21289286 DOI: 10.1152/ajpcell.00437.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Elevated intraocular pressure is the main risk factor in primary open-angle glaucoma, involving an increased resistance to aqueous humor outflow in the juxtacanalicular region of the conventional outflow pathway which includes the trabecular meshwork (TM) and the inner wall of Schlemm's canal (SC). Previously, sphingosine-1-phosphate (S1P) was shown to decrease outflow facility in porcine and human eyes, thus increasing outflow resistance and intraocular pressure. Owing to S1P's known effect of increasing barrier function in endothelial cells and the robust expression of the S1P₁ receptor on the inner wall of SC, we hypothesized that S1P₁ receptor activation promotes junction formation and decreases outflow facility. The effects of subtype-specific S1P receptor compounds were tested in human and porcine whole-eye perfusions and human primary cultures of SC and TM cells to determine the receptor responsible for S1P effects on outflow resistance. The S1P₁-specific agonist SEW2871 failed to both mimic S1P effects in paired human eye perfusions, as well as increase myosin light chain (MLC) phosphorylation in cell culture, a prominent outcome in S1P-treated SC and TM cells. In contrast, the S1P₂ antagonist JTE-013, but not the S1P₁ or S1P₁,₃ antagonists, blocked the S1P-promoted increase in MLC phosphorylation. Moreover, JTE-013 prevented S1P-induced decrease in outflow facility in perfused human eyes (P < 0.05, n = 6 pairs). Similarly, porcine eyes perfused with JTE-013 + S1P did not differ from eyes with JTE-013 alone (P = 0.53, n = 3). These results demonstrate that S1P₂ , and not S1P₁ or S1P₃, receptor activation increases conventional outflow resistance and is a potential target to regulate intraocular pressure.
Collapse
Affiliation(s)
- Grant M Sumida
- Dept. of Ophthalmology and Vision Science, University of Arizona, 655 North Alvernon Way, Tucson, AZ 85711, USA
| | | |
Collapse
|
49
|
Lei Y, Overby DR, Read AT, Stamer WD, Ethier CR. A new method for selection of angular aqueous plexus cells from porcine eyes: a model for Schlemm's canal endothelium. Invest Ophthalmol Vis Sci 2010; 51:5744-50. [PMID: 20554623 DOI: 10.1167/iovs.10-5703] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The authors sought to develop a technique for isolating and culturing angular aqueous plexus (AAP) cells from more plentiful porcine eyes. AAP is an analogue of Schlemm's canal. METHODS Cells were differentially selected with puromycin, a toxin often used to select brain microvascular endothelial cells based on the expression of P-glycoprotein (P-gp), a multidrug resistance efflux pump. Trabecular meshwork containing AAP was dissected and pooled from fresh porcine eyes, digested in collagenase I, washed, filtered, and cultured for 8 days in a gelatin-coated plastic flask. Cells were then selected by exposure to 4 μg/mL puromycin for 2 days in the culture medium. Cells were fixed and immunostained for P-gp, ICAM II, von Willebrand factor (vWF), VE-cadherin, and α-smooth muscle actin (α-SMA). RESULTS Histology of the limbus showed that the dissection was limited to the trabecular meshwork region, including the AAP. Before puromycin treatment, cells appeared heterogeneous and polygonal, suggestive of a mixed population. More than 90% of the cells were removed by puromycin, leaving a population that appeared uniformly cobblestone-like when grown to confluence and that was contact inhibited. Puromycin-selected cells stained positively for the endothelial markers ICAM II, vWF, and VE-cadherin but negatively for α-SMA, consistent with staining patterns in whole tissue. CONCLUSIONS Based on marker expression, morphology, and behavior in culture, puromycin-selected cells from porcine outflow tissues are AAP endothelial cells. Thus, porcine eyes can provide a plentiful alternative cell source for studying Schlemm's canal biology related to ocular hypertension.
Collapse
Affiliation(s)
- Yuan Lei
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | | | | | | | | |
Collapse
|
50
|
van der Merwe EL, Kidson SH. Advances in imaging the blood and aqueous vessels of the ocular limbus. Exp Eye Res 2010; 91:118-26. [PMID: 20447395 DOI: 10.1016/j.exer.2010.04.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 04/16/2010] [Accepted: 04/26/2010] [Indexed: 10/19/2022]
Abstract
The vessels of the limbus play a pivotal role in the drainage of the major portion of aqueous humour from the anterior chamber. Aberrations in the limbal architecture can lead to raised intraocular pressure, which in turn can lead to blinding conditions such as glaucoma. Imaging these vessels in the normal eye, in development, and in conditions where there is anterior segment dysgenesis remains a challenge. Here we review the progress in limbal vessel imaging in the past 50 years and provide key information on their strengths and limitations. Included is an analysis of serial histological sectioning, ultrathin sections, microvascular perfusion with plastics and corrosion casting, X-ray microcomputed tomography, in vivo imaging including analysis of transgenic mice expressing GFP-vascular endothelium fusion proteins, in vivo microscopy imaging using fluorescent-labelled antibodies, slit-lamp microscopy and gonioscopy, fluorescein angiography, optical coherence tomography, and various labelling procedures for the vascular endothelium and the various forms of microscopy used to view these.
Collapse
Affiliation(s)
- E L van der Merwe
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, 7925 Cape Town, South Africa.
| | | |
Collapse
|