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Baumann JM, Yarishkin O, Lakk M, De Ieso ML, Rudzitis CN, Kuhn M, Tseng YT, Stamer WD, Križaj D. TRPV4 and chloride channels mediate volume sensing in trabecular meshwork cells. Am J Physiol Cell Physiol 2024; 327:C403-C414. [PMID: 38881423 DOI: 10.1152/ajpcell.00295.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Revised: 06/06/2024] [Accepted: 06/10/2024] [Indexed: 06/18/2024]
Abstract
Aqueous humor drainage from the anterior eye determines intraocular pressure (IOP) under homeostatic and pathological conditions. Swelling of the trabecular meshwork (TM) alters its flow resistance but the mechanisms that sense and transduce osmotic gradients remain poorly understood. We investigated TM osmotransduction and its role in calcium and chloride homeostasis using molecular analyses, optical imaging, and electrophysiology. Anisosmotic conditions elicited proportional changes in TM cell volume, with swelling, but not shrinking, evoking elevations in intracellular calcium concentration [Ca2+]TM. Hypotonicity-evoked calcium signals were sensitive to HC067047, a selective blocker of TRPV4 channels, whereas the agonist GSK1016790A promoted swelling under isotonic conditions. TRPV4 inhibition partially suppressed hypotonicity-induced volume increases and reduced the magnitude of the swelling-induced membrane current, with a substantial fraction of the swelling-evoked current abrogated by Cl- channel antagonists 4,4'-diisothiocyanato-2,2'-stilbenedisulfonic acid (DIDS) and niflumic acid. The transcriptome of volume-sensing chloride channel candidates in primary human was dominated by ANO6 transcripts, with moderate expression of ANO3, ANO7, and ANO10 transcripts and low expression of LTTRC genes that encode constituents of the volume-activated anion channel. Imposition of 190 mosM but not 285 mosM hypotonic gradients increased conventional outflow in mouse eyes. TRPV4-mediated cation influx thus works with Cl- efflux to sense and respond to osmotic stress, potentially contributing to pathological swelling, calcium overload, and intracellular signaling that could exacerbate functional disturbances in inflammatory disease and glaucoma.NEW & NOTEWORTHY Intraocular pressure is dynamically regulated by the flow of aqueous humor through paracellular passages within the trabecular meshwork (TM). This study shows hypotonic gradients that expand the TM cell volume and reduce the outflow facility in mouse eyes. The swelling-induced current consists of TRPV4 and chloride components, with TRPV4 as a driver of swelling-induced calcium signaling. TRPV4 inhibition reduced swelling, suggesting a novel treatment for trabeculitis and glaucoma.
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Affiliation(s)
- Jackson M Baumann
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Oleg Yarishkin
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Michael L De Ieso
- Duke Eye Center, Duke University, Durham, North Carolina, United States
| | | | - Megan Kuhn
- Duke Eye Center, Duke University, Durham, North Carolina, United States
| | - Yun Ting Tseng
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - W Daniel Stamer
- Duke Eye Center, Duke University, Durham, North Carolina, United States
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, Utah, United States
- Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, Utah, United States
- Department of Neurobiology, University of Utah, Salt Lake City, Utah, United States
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Li G, van Batenburg‐Sherwood J, Safa BN, Fraticelli Guzmán NS, Wilson A, Bahrani Fard MR, Choy K, de Ieso ML, Cui JS, Feola AJ, Weisz T, Kuhn M, Bowes Rickman C, Farsiu S, Ethier CR, Stamer WD. Aging and intraocular pressure homeostasis in mice. Aging Cell 2024; 23:e14160. [PMID: 38566432 PMCID: PMC11258442 DOI: 10.1111/acel.14160] [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: 12/07/2023] [Revised: 03/09/2024] [Accepted: 03/14/2024] [Indexed: 04/04/2024] Open
Abstract
Age and elevated intraocular pressure (IOP) are the two primary risk factors for glaucoma, an optic neuropathy that is the leading cause of irreversible blindness. In most people, IOP is tightly regulated over a lifetime by the conventional outflow tissues. However, the mechanistic contributions of age to conventional outflow dysregulation, elevated IOP and glaucoma are unknown. To address this gap in knowledge, we studied how age affects the morphology, biomechanical properties and function of conventional outflow tissues in C57BL/6 mice, which have an outflow system similar to humans. As reported in humans, we observed that IOP in mice was maintained within a tight range over their lifespan. Remarkably, despite a constellation of age-related changes to the conventional outflow tissues that would be expected to hinder aqueous drainage and impair homeostatic function (decreased cellularity, increased pigment accumulation, increased cellular senescence and increased stiffness), outflow facility, a measure of conventional outflow tissue fluid conductivity, was stable with age. We conclude that the murine conventional outflow system has significant functional reserve in healthy eyes. However, these age-related changes, when combined with other underlying factors, such as genetic susceptibility, are expected to increase risk for ocular hypertension and glaucoma.
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Affiliation(s)
- Guorong Li
- Department of OphthalmologyDuke UniversityDurhamNorth CarolinaUSA
| | | | - Babak N. Safa
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGeorgiaUSA
| | - Nina Sara Fraticelli Guzmán
- Department of OphthalmologyEmory UniversityAtlantaGeorgiaUSA
- George W. Woodruff School of Mechanical EngineeringGeorgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Andrea Wilson
- Department of OphthalmologyDuke UniversityDurhamNorth CarolinaUSA
| | - Mohammad Reza Bahrani Fard
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGeorgiaUSA
| | - Kevin Choy
- Department of Biomedical EngineeringDuke UniversityDurhamNorth CarolinaUSA
| | | | - J. Serena Cui
- Department of OphthalmologyDuke UniversityDurhamNorth CarolinaUSA
| | - Andrew J. Feola
- Department of OphthalmologyEmory UniversityAtlantaGeorgiaUSA
- Department of Biomedical EngineeringDuke UniversityDurhamNorth CarolinaUSA
- Center for Visual and Neurocognitive RehabilitationAtlanta Virginia Medical CenterDecaturGeorgiaUSA
| | - Tara Weisz
- Department of OphthalmologyDuke UniversityDurhamNorth CarolinaUSA
| | - Megan Kuhn
- Department of OphthalmologyDuke UniversityDurhamNorth CarolinaUSA
| | | | - Sina Farsiu
- Department of OphthalmologyDuke UniversityDurhamNorth CarolinaUSA
- Department of Biomedical EngineeringDuke UniversityDurhamNorth CarolinaUSA
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGeorgiaUSA
- Department of OphthalmologyEmory UniversityAtlantaGeorgiaUSA
| | - W. Daniel Stamer
- Department of OphthalmologyDuke UniversityDurhamNorth CarolinaUSA
- Department of Biomedical EngineeringDuke UniversityDurhamNorth CarolinaUSA
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Becker S, L'Ecuyer Z, Jones BW, Zouache MA, McDonnell FS, Vinberg F. Modeling complex age-related eye disease. Prog Retin Eye Res 2024; 100:101247. [PMID: 38365085 PMCID: PMC11268458 DOI: 10.1016/j.preteyeres.2024.101247] [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: 08/15/2023] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 02/18/2024]
Abstract
Modeling complex eye diseases like age-related macular degeneration (AMD) and glaucoma poses significant challenges, since these conditions depend highly on age-related changes that occur over several decades, with many contributing factors remaining unknown. Although both diseases exhibit a relatively high heritability of >50%, a large proportion of individuals carrying AMD- or glaucoma-associated genetic risk variants will never develop these diseases. Furthermore, several environmental and lifestyle factors contribute to and modulate the pathogenesis and progression of AMD and glaucoma. Several strategies replicate the impact of genetic risk variants, pathobiological pathways and environmental and lifestyle factors in AMD and glaucoma in mice and other species. In this review we will primarily discuss the most commonly available mouse models, which have and will likely continue to improve our understanding of the pathobiology of age-related eye diseases. Uncertainties persist whether small animal models can truly recapitulate disease progression and vision loss in patients, raising doubts regarding their usefulness when testing novel gene or drug therapies. We will elaborate on concerns that relate to shorter lifespan, body size and allometries, lack of macula and a true lamina cribrosa, as well as absence and sequence disparities of certain genes and differences in their chromosomal location in mice. Since biological, rather than chronological, age likely predisposes an organism for both glaucoma and AMD, more rapidly aging organisms like small rodents may open up possibilities that will make research of these diseases more timely and financially feasible. On the other hand, due to the above-mentioned anatomical and physiological features, as well as pharmacokinetic and -dynamic differences small animal models are not ideal to study the natural progression of vision loss or the efficacy and safety of novel therapies. In this context, we will also discuss the advantages and pitfalls of alternative models that include larger species, such as non-human primates and rabbits, patient-derived retinal organoids, and human organ donor eyes.
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Affiliation(s)
- Silke Becker
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Zia L'Ecuyer
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Bryan W Jones
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Moussa A Zouache
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Fiona S McDonnell
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA; Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Frans Vinberg
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA; Biomedical Engineering, University of Utah, Salt Lake City, UT, USA.
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Strohmaier CA, Wanderer D, Zhang X, Zhang HF, Strohmaier S, Weinreb RN, Huang AS. Lack of Correlation Between Segmental Trabecular Meshwork Pigmentation and Angiographically Determined Outflow in Ex Vivo Human Eyes. J Glaucoma 2024; 33:355-360. [PMID: 37851964 PMCID: PMC10995104 DOI: 10.1097/ijg.0000000000002318] [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: 08/07/2023] [Accepted: 09/18/2023] [Indexed: 10/20/2023]
Abstract
PRCIS Trabecular meshwork (TM) pigmentation is not correlated with angiographically determined aqueous humor outflow (AHO) in an ex vivo perfusion model using human eyes. PURPOSE To evaluate whether segmental TM pigmentation is correlated to segmental AHO in human eyes. METHODS Postmortem human eyes were acquired, and anterior segments were dissected. TM pigmentation was photographed 360-degrees around the eye. The anterior segments were then mounted onto a perfusion apparatus and perfused with Dulbecco's phosphate buffered saline (DPBS) until a stabile baseline outflow facility was achieved. Aqueous angiography (AHO angiography) was performed using fluorescein (2%), and segmental AHO was documented around the limbus using an angiographic camera (Spectralis HRA+OCT). Circumferential and nasal TM pigmentation were compared with respective angiographic outflow imaging using a Pearson correlation analysis. RESULTS Segmental TM pigment distribution and segmental AHO were seen. TM pigment was statistically greatest in the inferior quadrant. AHO angiographic outflow was numerically greatest in the nasal quadrant, but this was not statistically significant. No statistically significant correlation was observed (r=-0.083, P =0.06) between segmental TM pigmentation and segmental AHO angiographic signal. Analyzing just the nasal quadrant, a significant weak negative correlation was found (r=-0.296, P =0.001). DISCUSSION Segmental TM pigmentation circumferentially around the eye is not a good proxy for segmental AHO circumferentially around the eye and should not be used to guide trabecular minimally invasive glaucoma surgeries.
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Affiliation(s)
- Clemens A. Strohmaier
- Hamilton Glaucoma Center, The Viterbi Family Department of Ophthalmology, Shiley Eye Institute, University of California, San Diego, CA, USA
- Department of Ophthalmology and Optometry, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Daniel Wanderer
- Hamilton Glaucoma Center, The Viterbi Family Department of Ophthalmology, Shiley Eye Institute, University of California, San Diego, CA, USA
| | - Xiaowei Zhang
- Hamilton Glaucoma Center, The Viterbi Family Department of Ophthalmology, Shiley Eye Institute, University of California, San Diego, CA, USA
| | - Hao F. Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Susanne Strohmaier
- Department of Epidemiology, Center for Public Health, Medical University of Vienna, Vienna, Austria
| | - Robert N. Weinreb
- Hamilton Glaucoma Center, The Viterbi Family Department of Ophthalmology, Shiley Eye Institute, University of California, San Diego, CA, USA
| | - Alex S. Huang
- Hamilton Glaucoma Center, The Viterbi Family Department of Ophthalmology, Shiley Eye Institute, University of California, San Diego, CA, USA
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Zhang X, Xi G, Feng P, Li C, Kuehn MH, Zhu W. Intraocular pressure across the lifespan of Tg-MYOC Y437H mice. Exp Eye Res 2024; 241:109855. [PMID: 38453040 DOI: 10.1016/j.exer.2024.109855] [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: 01/01/2024] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 03/09/2024]
Abstract
Transgenic C57BL/6 mice expressing human myocilinY437 (Tg-MYOCY437H) are a well-established model for primary open-angle glaucoma (POAG). While the reduced trabecular meshwork (TM) cellularity due to severe endoplasmic reticulum (ER) stress has been characterized as the etiology of this model, there is a limited understanding of how glaucomatous phenotypes evolve over the lifespan of Tg-MyocY437H mice. In this study, we compiled the model's intraocular pressure (IOP) data recorded in our laboratory from 2017 to 2023 and selected representative eyes to measure the outflow facility (Cr), a critical parameter indicating the condition of the conventional TM pathway. We found that Tg-MYOCY437H mice aged 4-12 months exhibited significantly higher IOPs than age-matched C57BL/6 mice. Notably, a decline in IOP was observed in Tg-MYOCY437H mice at 17-24 months of age, a phenomenon not attributable to the gene dosage of mutant myocilin. Measurements of the Cr of Tg-MYOCY437H mice indicated that the age-related IOP reduction was not a result of ongoing TM damage. Instead, Hematoxylin and Eosin staining, immunohistochemistry analysis, and transmission electron microscopic examination revealed that this reduction might be induced by degenerations of the non-pigmented epithelium in the ciliary body of aged Tg-MYOCY437H mice. Overall, our findings provide a comprehensive profile of mutant myocilin-induced ocular changes over the Tg-MYOCY437H mouse lifespan and suggest a specific temporal window of elevated IOP that may be ideal for experimental purposes.
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Affiliation(s)
- Xiaoyan Zhang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, 266021, China
| | - Gaiping Xi
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, 266021, China
| | - Pengchao Feng
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, 266021, China
| | - Cong Li
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, 266021, China
| | - Markus H Kuehn
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, 52242, USA; Center for the Prevention and Treatment of Visual Loss, Iowa City Veterans Affairs Medical Center, Iowa City, IA, 52246, USA
| | - Wei Zhu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, 266021, China; Advanced Innovation Center for Big Data-Based Precision Medicine, Beijing University of Aeronautics and Astronautics, Capital Medical University, Beijing, 100083, China.
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Li G, van Batenburg-Sherwood J, Safa BN, Fraticelli Guzmán NS, Wilson A, Bahrani Fard MR, Choy K, De Ieso ML, Cui JS, Feola AJ, Weisz T, Kuhn M, Rickman CB, Farsiu S, Ethier CR, Stamer WD. Aging and intraocular pressure homeostasis in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.17.562768. [PMID: 38106150 PMCID: PMC10723259 DOI: 10.1101/2023.10.17.562768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Age and elevated intraocular pressure (IOP) are the two primary risk factors for glaucoma, an optic neuropathy that is the leading cause of irreversible blindness. In most people, IOP is tightly regulated over a lifetime by the conventional outflow tissues. However, the mechanistic contributions of age to conventional outflow dysregulation, elevated IOP and glaucoma are unknown. To address this gap in knowledge, we studied how age affects the morphology, biomechanical properties and function of conventional outflow tissues in C57BL/6 mice, which have an outflow system similar to humans. As reported in humans, we observed that IOP in mice was maintained within a tight range over their lifespan. Remarkably, despite a constellation of age-related changes to the conventional outflow tissues that would be expected to hinder aqueous drainage and impair homeostatic function (decreased cellularity, increased pigment accumulation, increased cellular senescence and increased stiffness), outflow facility, a measure of conventional outflow tissue fluid conductivity, was stable with age. We conclude that the murine conventional outflow system has significant functional reserve in healthy eyes. However, these age-related changes, when combined with other underlying factors, such as genetic susceptibility, are expected to increase risk for ocular hypertension and glaucoma.
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