Browsing by Author "Mao, Weiming"

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    Age and sex affect TGFβ2-induced ocular hypertension in C57BL/6J mice
    (Elsevier, 2022) Sugali, Chenna Kesavulu; Rayana, Naga Pradeep; Dai, Jiannong; Peng, Michael; Mao, Weiming; Ophthalmology, School of Medicine
    Glaucoma is a leading cause of blindness worldwide. The loss of vision in glaucoma patients is due to optic nerve damage. The most important risk factor of glaucoma is elevated intraocular pressure (IOP) which is due to glaucomatous changes in the trabecular meshwork. Animal models, especially mouse models for ocular hypertension (OHT), are important for studying glaucoma. Published studies showed that 2.5X107 PFU adenoviral vectors expressing the biologically active form of human TGFβ2 elevate IOP in female C57BL/6J mice when they are intravitreally delivered. In this study, we found that 2.5X107 PFU adenoviral TGFβ2 vector did not elevate IOP in 3- or 5-month old male C57BL/6J mice. In contrast, 5X107 PFU of the same viral vectors elevated IOP in both 3- and 5-month old male C57BL/6J mice. Also, 5-month old mice showed earlier OHT and higher IOP compared to 3-month old mice. In summary, our data showed that age and sex play roles in adenoviral vector-mediated TGFβ2-induced OHT in C57BL/6J mice.
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    An ex vivo model of human corneal rim perfusion organ culture
    (Elsevier, 2022) Peng, Michael; Margetts, Tyler J.; Sugali, Chenna Kesavulu; Rayana, Naga Pradeep; Dai, Jiannong; Sharma, Tasneem P.; Raghunathan, Vijay Krishna; Mao, Weiming; Ophthalmology, School of Medicine
    The human anterior segment perfusion culture model is a valuable tool for studying the trabecular meshwork (TM) and aqueous humor outflow in glaucoma. The traditional model relies on whole eye globes resulting in high cost and limited availability. Here, we developed a glue-based method which enabled us to use human corneal rims for perfusion culture experiments. Human corneal rim perfusion culture plates were 3D printed. Human corneal rims containing intact TM were attached and sealed to the plate using low viscosity and high viscosity glues, respectively. The human corneal rims were perfused using the constant flow mode, and the pressure changes were recorded using a computerized system. Outflow facility, TM stiffness, and TM morphology were evaluated. When perfused at rates from 1.2 to 3.6 μl/min, the outflow facility was 0.359 ± 0.216 μl/min/mmHg among 10 human corneal rims. The stiffness of the TM in naïve human corneal rim was similar to that of perfusion cultured human corneal rim. Also, the stiffness of TM of corneal rims perfused with dexamethasone was significantly higher than the control. Human corneal rims with glue contamination in the TM could be differentiated by high baseline intraocular pressure as well as high TM stiffness. Histology studies showed that the TM tissues perfused with plain medium appeared normal. We believed that our glued-based method is a useful tool and low-cost alternative to the traditional anterior segment perfusion culture model.
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    The Canonical Wnt Signaling Pathway Inhibits the Glucocorticoid Receptor Signaling Pathway in the Trabecular Meshwork
    (Elsevier, 2021) Sugali, Chenna Kesavulu; Rayana, Naga Pradeep; Dai, Jiannong; Peng, Michael; Harris, Sherri L.; Webber, Hannah C.; Liu, Shaohui; Dixon, Stephan G.; Parekh, Priyanka H.; Martin, Elizabeth A.; Cantor, Louis B.; Fellman, Ronald L.; Godfrey, David G.; Butler, Michelle R.; Emanuel, Matthew E.; Grover, Davinder S.; Smith, Oluwatosin U.; Clark, Abbot F.; Raghunathan, Vijay Krishna; Mao, Weiming; Ophthalmology, School of Medicine
    Glucocorticoid-induced glaucoma is a secondary open-angle glaucoma. About 40% of the general population may develop elevated intraocular pressure on prolonged glucocorticoid treatment secondary to damages in the trabecular meshwork (TM), a tissue that regulates intraocular pressure. Therefore, identifying the key molecules responsible for glucocorticoid-induced ocular hypertension is crucial. In this study, Dickkopf-related protein 1 (Dkk1), a canonical Wnt signaling inhibitor, was found to be elevated in the aqueous humor and TM of glaucoma patients. At the signaling level, Dkk1 enhanced glucocorticoid receptor (GR) signaling, whereas Dkk1 knockdown or Wnt signaling activators decreased GR signaling in human TM cells as indicated by luciferase assays. Similarly, activation of the GR signaling inhibited Wnt signaling. At the protein level, glucocorticoid-induced extracellular matrix was inhibited by Wnt activation using Wnt activators or Dkk1 knockdown in primary human TM cells. In contrast, inhibition of canonical Wnt signaling by β-catenin knockdown increased glucocorticoid-induced extracellular matrix proteins. At the physiological level, adenovirus-mediated Wnt3a expression decreased glucocorticoid-induced ocular hypertension in mouse eyes. In summary, Wnt and GR signaling inhibit each other in the TM, and canonical Wnt signaling activators may prevent the adverse effect of glucocorticoids in the eye.
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    Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms
    (Association for Research in Vision and Ophthalmology, 2022) McDowell, Colleen M.; Kizhatil, Krishnakumar; Elliott, Michael H.; Overby, Darryl R.; van Batenburg-Sherwood, Joseph; Millar, J. Cameron; Kuehn, Markus H.; Zode, Gulab; Acott, Ted S.; Anderson, Michael G.; Bhattacharya, Sanjoy K.; Bertrand, Jacques A.; Borras, Terete; Bovenkamp, Diane E.; Cheng, Lin; Danias, John; De Ieso, Michael Lucio; Du, Yiqin; Faralli, Jennifer A.; Fuchshofer, Rudolf; Ganapathy, Preethi S.; Gong, Haiyan; Herberg, Samuel; Hernandez, Humberto; Humphries, Peter; John, Simon W.M.; Kaufman, Paul L.; Keller, Kate E.; Kelley, Mary J.; Kelly, Ruth A.; Krizaj, David; Kumar, Ajay; Leonard, Brian C.; Lieberman, Raquel L.; Liton, Paloma; Liu, Yutao; Liu, Katy C.; Lopez, Navita N.; Mao, Weiming; Mavlyutov, Timur; McDonnell, Fiona; McLellan, Gillian J.; Mzyk, Philip; Nartey, Andrews; Pasquale, Louis R.; Patel, Gaurang C.; Pattabiraman, Padmanabhan P.; Peters, Donna M.; Raghunathan, Vijaykrishna; Rao, Ponugoti Vasantha; Rayana, Naga; Raychaudhuri, Urmimala; Reina-Torres, Ester; Ren, Ruiyi; Rhee, Douglas; Chowdhury, Uttio Roy; Samples, John R.; Samples, E. Griffen; Sharif, Najam; Schuman, Joel S.; Sheffield, Val C.; Stevenson, Cooper H.; Soundararajan, Avinash; Subramanian, Preeti; Sugali, Chenna Kesavulu; Sun, Yang; Toris, Carol B.; Torrejon, Karen Y.; Vahabikashi, Amir; Vranka, Janice A.; Wang, Ting; Willoughby, Colin E.; Xin, Chen; Yun, Hongmin; Zhang, Hao F.; Fautsch, Michael P.; Tamm, Ernst R.; Clark, Abbot F.; Ethier, C. Ross; Stamer, W. Daniel; Ophthalmology, School of Medicine
    Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.
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    Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms
    (ARVO, 2022-02) McDowell, Colleen M.; Kizhatil, Krishnakumar; Elliott, Michael H.; Overby, Darryl R.; Van Batenburg-Sherwood, Joseph; Millar, J. Cameron; Kuehn, Markus H.; Zode, Gulab; Acott, Ted S.; Anderson, Michael G.; Bhattacharya, Sanjoy K.; Bertrand, Jacques A.; Borras, Terete; Bovenkamp, Diane E.; Cheng, Lin; Danias, John; De Ieso, Michael Lucio; Du, Yiqin; Faralli, Jennifer A.; Fuchshofer, Rudolf; Ganapathy, Preethi S.; Gong, Haiyan; Herberg, Samuel; Hernandez, Humberto; Humphries, Peter; John, Simon W. M.; Kaufman, Paul L.; Keller, Kate E.; Kelley, Mary J.; Kelly, Ruth A.; Krizaj, David; Kumar, Ajay; Leonard, Brian C.; Lieberman, Raquel L.; Liton, Paloma; Liu, Yutao; Liu, Katy C.; Lopez, Navita N.; Mao, Weiming; Mavlyutov, Timur; McDonnell, Fiona; McLellan, Gillian J.; Mzyk, Philip; Nartey, Andrews; Pasquale, Louis R.; Patel, Gaurang C.; Pattabiraman, Padmanabhan P.; Peters, Donna M.; Raghunathan, Vijaykrishna; Rao, Ponugoti Vasantha; Rayana, Naga; Raychaudhuri, Urmimala; Reina-Torres, Ester; Ren, Ruiyi; Rhee, Douglas; Chowdhury, Uttio Roy; Samples, John R.; Samples, E. Griffen; Sharif, Najam; Schuman, Joel S.; Sheffield, Val C.; Stevenson, Cooper H.; Soundararajan, Avinash; Subramanian, Preeti; Sugali, Chenna Kesavulu; Sun, Yang; Toris, Carol B.; Torrejon, Karen Y.; Vahabikashi, Amir; Vranka, Janice A.; Wang, Ting; Willoughby, Colin E.; Xin, Chen; Yun, Hongmin; Zhang, Hao F.; Fautsch, Michael P.; Tamm, Ernst R.; Clark, Abbot F.; Ethier, C. Ross; Stamer, W. Daniel; Ophthalmology, School of Medicine
    Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.
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    Consensus Recommendations for Studies of Outflow Facility and Intraocular Pressure Regulation Using Ex Vivo Perfusion Approaches
    (Association for Research in Vision and Ophthalmology, 2024) Acott, Ted S.; Fautsch, Michael P.; Mao, Weiming; Ethier, C. Ross; Huang, Alex S.; Kelley, Mary J.; Aga, Mini; Bhattacharya, Sanjoy K.; Borras, Terete; Bovenkamp, Diane; Chowdhury, Uttio Roy; Clark, Abbot F.; Dibas, Mohammed I.; Du, Yiqin; Elliott, Michael H.; Faralli, Jennifer A.; Gong, Haiyan; Herberg, Samuel; Johnstone, Murray A.; Kaufman, Paul L.; Keller, Kate E.; Kelly, Ruth A.; Krizaj, David; Kuehn, Markus H.; Li, Hoi Lam; Lieberman, Raquel; Lin, Shan C.; Liu, Yutao; McDonnell, Fiona S.; McDowell, Colleen M.; McLellan, Gillian J.; Mzyk, Philip; Nair, Kayarat Saidas; Overby, Darryl R.; Peters, Donna M.; Raghunathan, VijayKrishna; Rao, Ponugoti Vasantha; Roddy, Gavin W.; Sharif, Najam A.; Shim, Myoung Sup; Sun, Yang; Thomson, Benjamin R.; Toris, Carol B.; Willoughby, Colin E.; Zhang, Hao F.; Freddo, Thomas F.; Fuchshofer, Rudolf; Hill, Kamisha R.; Karimi, Alireza; Kizhatil, Krishnakumar; Kopcyznski, Casey C.; Liton, Paloma; Patel, Gaurang; Peng, Michael; Pattabiraman, Padmanabhan P.; Prasanna, Ganesh; Reina-Torres, Ester; Samples, E. Griffen; Samples, John R.; Steel, Cynthia L.; Strohmaier, Clemens A.; Subramanian, Preeti; Sugali, Chenna Kesavulu; van Batenburg-Sherwood, Joseph; Wong, Cydney; Youngblood, Hannah; Zode, Gulab S.; White, Elizabeth; Stamer, W. Daniel; Ophthalmology, School of Medicine
    Intraocular pressure (IOP) elevation is the primary risk factor and currently the main treatable factor for progression of glaucomatous optic neuropathy. In addition to direct clinical and living animal in vivo studies, ex vivo perfusion of anterior segments and whole eyes is a key technique for studying conventional outflow function as it is responsible for IOP regulation. We present well-tested experimental details, protocols, considerations, advantages, and limitations of several ex vivo model systems for studying IOP regulation. These include: (1) perfused whole globes, (2) stationary anterior segment organ culture, (3) perfused human anterior segment organ culture, (4) perfused animal anterior segment organ culture, (5) perfused human corneal rims, and (6) perfused human anterior segment wedges. These methods, with due consideration paid to their strengths and limitations, comprise a set of very strong tools for extending our understanding of IOP regulation.
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    Cross-linked actin networks (CLANs) affect stiffness and/or actin dynamics in transgenic transformed and primary human trabecular meshwork cells
    (Elsevier, 2022) Peng, Michael; Rayana, Naga Pradeep; Dai, Jiannong; Sugali, Chenna Kesavulu; Baidouri, Hasna; Suresh, Ayush; Raghunathan, Vijay Krishna; Mao, Weiming; Ophthalmology, School of Medicine
    Cross-linked actin networks (CLANs) in trabecular meshwork (TM) cells may contribute to increased IOP by altering TM cell function and stiffness. However, there is a lack of direct evidence. Here, we developed transformed TM cells that form spontaneous fluorescently labeled CLANs. The stable cells were constructed by transducing transformed glaucomatous TM (GTM3) cells with the pLenti-LifeAct-EGFP-BlastR lentiviral vector and selection with blastcidin. The stiffness of the GTM3-LifeAct-GFP cells were studied using atomic force microscopy. Elastic moduli of CLANs in primary human TM cells treated with/without dexamethasone/TGFβ2 were also measured to validate findings in GTM3-LifeAct-GFP cells. Live-cell imaging was performed on GTM3-LifeAct-GFP cells treated with 1μM latrunculin B or pHrodo bioparticles to determine actin stability and phagocytosis, respectively. The GTM3-LifeAct-GFP cells formed spontaneous CLANs without the induction of TGFβ2 or dexamethasone. The CLAN containing cells showed elevated cell stiffness, resistance to latrunculin B-induced actin depolymerization, as well as compromised phagocytosis, compared to the cells without CLANs. Primary human TM cells with dexamethasone or TGFβ2-induced CLANs were also stiffer and less phagocytic. The GTM3-LifeAct-GFP cells are a novel tool for studying the mechanobiology and pathology of CLANs in the TM. Initial characterization of these cells showed that CLANs contribute to at least some glaucomatous phenotypes of TM cells.
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    Effects of Hydrocephalus on Rodent Optic Nerve and Optic Disc
    (2021-08) McCue, Rachel A.; Belecky-Adams, Teri; Blazer-Yost, Bonnie; Mao, Weiming; Baucum, A.J.; Berbari, Nick
    Hydrocephalus affects 1 in 1,000 newborns and nearly 1,000,000 Americans, leading to an increase in intercranial pressure due to the build-up of cerebrospinal fluid. There are numerous complications that arise as a result of hydrocephalus, but this study focuses on optic disc edema. The subarachnoid space surrounding the optic nerve contains cerebrospinal fluid. The cerebrospinal fluid increases in hydrocephalus, putting pressure on the optic nerve. The additional intracranial pressure has been proposed to cause axoplasmic stasis within the retinal ganglion cell axons, leading to axonal damage and retinal ischemia. The purpose of this study was to determine the effects of hydrocephalus on the optic disc and retina in several animal models of hydrocephalus. This study uses two genetic and two injury-induced models of hydrocephalus in addition to immunohistochemistry and histological stains to examine the optic disc, thickness of retinal layers, and numbers of retinal cells. This study serves as preliminary work to help build the case that hydrocephalus causes cell loss in the retina, as well as swelling of the retinal ganglion cell axons, leading to axoplasmic stasis and cell death.
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    Evidence that cannabinoid CB1 receptors regulate intraocular pressure via two opposing mechanisms
    (Elsevier, 2020) Miller, Sally; Daily, Laura; Ploss, Maya; Greig, Iain; Ross, Ruth; Rayana, Naga Pradeep; Dai, Jiannong; Sugali, Chenna Kesavulu; Mao, Weiming; Straiker, Alex; Ophthalmology, School of Medicine
    The cannabinoid signaling system regulates intraocular pressure (IOP) in the mouse via a complex system that includes three receptors: CB1, GPR18 and GPR119. In each case, activating the receptor lowers IOP, but CB1 receptors are found both at sites of aqueous humor inflow and outflow. As such, knockout mice for any of these receptors would be expected to have higher-than average, or at least unchanged, intraocular pressure. The current study investigates the unexpected observation that CB1 knockout mice have lower pressure than wild type counterparts by testing various regulators of cannabinoid signaling in murine models of IOP. We now report that a CB1 antagonist has differential effects on IOP: SR141716 raises IOP in standard light cycle (SLC) but lowers IOP in reverse light cycle (RLC). This is mimicked by ABD1085, a negative allosteric modulator of CB1. CB1 inhibitors lower IOP in both normotensive and hypertensive mouse eyes. The pressure-lowering effect is absent in CB1 knockout mice. IOP rebounds after the end of treatment but shows no sign of desensitization with daily treatment for a week. Unlike the positive cannabinoid effect, antagonist effects are not sex-dependent. We propose that there are two mechanisms of action for CB1, one that lowers IOP upon activation and a second with inverse sign that lowers IOP when CB1 is antagonized. The relatively lower pressure in CB1 knockout mouse eyes suggests that this second negative regulation of IOP is dominant.
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    Glucocorticoid-Induced Ocular Hypertension and Glaucoma
    (Dove Press, 2024-02-16) Harvey, Devon Hori; Sugali, Chenna Kesavulu; Mao, Weiming; Ophthalmology, School of Medicine
    Glucocorticoid (GC) therapy is indicated in many diseases, including ocular diseases. An important side-effect of GC therapy is GC-induced ocular hypertension (GIOHT), which may cause irreversible blindness known as GC-induced glaucoma (GIG). Here, we reviewed the pathological changes that contribute to GIOHT including in the trabecular meshwork and Schlemm’s canal at cellular and molecular levels. We also discussed the clinical aspects of GIOHT/GIG including disease prevalence, risk factors, the type of GCs, the route of GC administration, and management strategies.