Browsing by Subject "ocular hypertension"
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Item Clinical Internship with the Clinical Glaucoma/Viability Group at Alcon Research, Ltd.: The Use of Prostaglandin Analogues in the Treatment of Patients with Open-Angle Glaucoma (OAG) or Ocular Hypertension (OHT)(2003-12-01) Hall, Magali G.; Robert Wordinger; Richard Easom; Victoria RudickHall, Magali. Master of Science, Biomedical Sciences, December 2003. The use of Prostaglandin Analogues (PGAs) in the Treatment of Patients with Open-Angle Glaucoma (OAG) or Ocular Hypertension (OHT). Summary: Glaucoma is an ocular condition that causes damage to the optic nerve leading to a loss of visual function, and permanent blindness if left untreated. It is the leading cause of preventable blindness in the U.S. The main risk factor for glaucomatous optic neuropathy is elevated intraocular pressure (IOP), which can be controlled by pharmaceutical therapy, surgical therapy or both. Topical medication is usually recommended prior to surgical intervention. Objectives: This study had two main objectives. First, to determine the IOP lower safety and efficacy of three concentrations of a new prostaglandin analogues (PGA), and secondly to determine the incidence of ocular hyperemia with once-daily dosing of study medication compared to it’s vehicle and to latanoprost, a marketed PGA. Study Design: This was a Phase II, double-masked, dose-response study with five treatment arms (the three different concentrations of study drug), vehicle, and latanoprost. Study was conducted in fourteen days, with five study visits as follows: Screening and eligibility visit followed by three on-therapy visits scheduled on Day 1, Day 7, and Day 14. The primary efficacy variable was IOP measurements taken at four different time points on study visits. Results: Final data will not available in time to include in this paper.Item CNS axonal degeneration and transport deficits at the optic nerve head precede structural and functional loss of retinal ganglion cells in a mouse model of glaucoma(BioMed Central Ltd., 2020-08-27) Maddineni, Prabhavathi; Kasetti, Ramesh B.; Patel, Pinkal D.; Millar, J. Cameron; Kiehlbauch, Charles; Clark, Abbot F.; Zode, Gulab S.BACKGROUND: Glaucoma is a leading neurodegenerative disease affecting over 70 million individuals worldwide. Early pathological events of axonal degeneration and retinopathy in response to elevated intraocular pressure (IOP) are limited and not well-defined due to the lack of appropriate animal models that faithfully replicate all the phenotypes of primary open angle glaucoma (POAG), the most common form of glaucoma. Glucocorticoid (GC)-induced ocular hypertension (OHT) and its associated iatrogenic open-angle glaucoma share many features with POAG. Here, we characterized a novel mouse model of GC-induced OHT for glaucomatous neurodegeneration and further explored early pathological events of axonal degeneration in response to elevated IOP. METHODS: C57BL/6 J mice were periocularly injected with either vehicle or the potent GC, dexamethasone 21-acetate (Dex) once a week for 10 weeks. Glaucoma phenotypes including IOP, outflow facility, structural and functional loss of retinal ganglion cells (RGCs), optic nerve (ON) degeneration, gliosis, and anterograde axonal transport deficits were examined at various stages of OHT. RESULTS: Prolonged treatment with Dex leads to glaucoma in mice similar to POAG patients including IOP elevation due to reduced outflow facility and dysfunction of trabecular meshwork, progressive ON degeneration and structural and functional loss of RGCs. Lowering of IOP rescued Dex-induced ON degeneration and RGC loss, suggesting that glaucomatous neurodegeneration is IOP dependent. Also, Dex-induced neurodegeneration was associated with activation of astrocytes, axonal transport deficits, ON demyelination, mitochondrial accumulation and immune cell infiltration in the optic nerve head (ONH) region. Our studies further show that ON degeneration precedes structural and functional loss of RGCs in Dex-treated mice. Axonal damage and transport deficits initiate at the ONH and progress toward the distal end of ON and target regions in the brain (i.e. superior colliculus). Most of anterograde transport was preserved during initial stages of axonal degeneration (30% loss) and complete transport deficits were only observed at the ONH during later stages of severe axonal degeneration (50% loss). CONCLUSIONS: These findings indicate that ON degeneration and transport deficits at the ONH precede RGC structural and functional loss and provide a new potential therapeutic window for rescuing neuronal loss and restoring health of damaged axons in glaucoma.Item Crosstalk Between Transforming Growth Factor Beta-2 and Toll-Like Receptor 4 in the Trabecular Meshwork(2017-12-01) Hernandez, Humberto; McDowell, Colleen; Clark, Abbot F.; Pang, Iok-HouThe trabecular meshwork (TM) is the main site of outflow resistance in primary-open angle glaucoma (POAG) patients. In these patients, aqueous humor outflow resistance increases, subsequently leading to a rise in intraocular pressure (IOP). The rise in IOP ultimately damages the optic nerve and leads to blindness. Accumulation of extracellular matrix (ECM) at the TM has been shown by our laboratory and many others to be responsible for the increase in outflow resistance. The molecular mechanisms underlying the pathology are beginning to be elucidated. The pro-fibrotic cytokine, transforming growth factor beta-2 (TGFβ2), has been shown to be elevated in the aqueous humor of POAG patients. Mice injected with adenovirus encoding active TGFβ2 develop ocular hypertension and ECM deposition at the TM. Recently, toll-like receptor 4 (TLR4) signaling has been linked to the development of fibrosis. In our studies, we evaluated the crosstalk between TGFβ2 and TLR4 in the TM. We utilized in vitro and in vivo models to evaluate the role of TLR4 on the production of ECM and development of ocular hypertension. We also utilized a conditional knockout in vitro and in vivo adenovirus delivery system to study BMP and Activin Membrane Bound Inhibitor (BAMBI), a critical molecule in the crosstalk between TGFβ2 and TLR4. Our studies reveal a novel pathway involved in the development of TM damage and potential targets to lower IOP.Item Identification of Actin Binding Proteins Associated with Cross-Linked Actin Networks(2006-12-01) Mills, Christy E.; Clark, Abbot F.; Yorio, Thomas; Wordinger, Robert J.Mills, Christy E., Identification of Actin Binding Proteins Associated with Cross-Lined Actin Networks. Master of Science (Pharmacology and Neuroscience), December 2006, 95 pp., 9 tables, 16 figures, references, 122 titles. Glucocorticoid therapy can leady to ocular hypertension and glaucoma. The purpose of this study is to examine mechanisms contributing to increased intraocular pressure using tissue culture models of steroid-induced ocular hypertension through identification of specific actin-binding proteins associated with cross-linked actin network (CLANs). Human trabecular meshwork ™ cells were cultured to confluence and treated with dexamethasone or vehicle for 14 days. Total RNA was extracted for gene expression analysis to confirm steroid-induced expression of actin binding proteins in human TM cells. Western blots confirmed expression of actin binding proteins and demonstrated the specificity of selected antibodies. Fluorescence microscopy of treated TM cells showed cytoskeleton rearrangements from linear actin stress fibers to cross-linked actin networks and the position of candidate proteins in relation to CLANs. Dexamethasone treatment of TM cells altered the expression of actin-associated proteins that may be important in the formation of CLANs and increased outflow resistance.Item Mechanisms of Glucocorticoid-induced ocular hypertension(2003-08-01) Zhang, Xinyu; Thomas YorioZhang, Xinyu, Mechanisms of glucocorticoid-induced ocular hypertension. Doctor of Philosophy (Pharmacology & Neuroscience). August 2003; 163p; 4 tables; 24 figures; 102 titles. Glucocorticoids, frequently used anti-inflammatory and immunosuppressive agents, are associated with ocular hypertension and glaucoma. Endothelin-1 (ET-1) is also implicated in glaucoma pathology and optic neuropathy as its concentration is elevated in glaucoma patients and in animal models of glaucoma and chronic administration of ET-1 produces damage to the optic nerve head in rats. Glucocorticoids have been reported to regulate the expression of ET-1 gene and ET receptors in the cardiovascular system. However in the eye, the interactions between glucocorticoids and ET-1 have been implicated in the regulation of intraocular pressure and contribute to glaucoma pathology. Therefore, the purpose of the investigations described herein was to determine the novel mechanisms that may be involved in the regulation of intraocular pressure by glucocorticoids with interactions with ET-1 and ET receptors in NPE cells, a source of ET-1, and in TM cells where both glucocorticoids and ET-1 effect aqueous humor outflow. The hypothesis was that ET-1 exacerbates the actions of glucocorticoids on TM cells and contributes to increased outflow resistance. Furthermore, individual sensitivities to glucocorticoids differ considerably. About one in every three people in the general population is considered potential steroid responders while almost all primary open angle glaucoma (POAG) patients are steroid responders and develop ocular hypertension after ocular administration of glucocorticoids. The molecular mechanisms underlying the higher glucocorticoid responsiveness among POAG patients remain unknown. The glucocorticoid receptor beta isoform (hGRβ) has become a candidate for glucocorticoid resistance in some diseases, especially in asthma, based on the reports of its negative activity. The purpose of this segment of the investigations was to test the hypothesis that glucocorticoid responsiveness was regulated by the expression of hGRβ in TM cells. We demonstrated that dexamethaosone (Dex), a synthetic glucocorticoid, increased ET-1 synthesis and release from human non-pigmented ciliary epithelial (HNPE) cells. Dex also suppressed ETB receptor protein expression and attenuated ET-1 mediated increase in nitric oxide (NO) while Dex had no effect on ETA receptor expression and ETA receptor mediated intracellular Ca2+ mobilization in TM cells. The increase in the release of ET-1 from HNPE cells with a concomitant decrease of ETB receptor protein expression and ETB receptor mediated NO release by Dex in TM could result in an increase in the contraction and decrease in relaxation of trabecular meshwork thus reducing the intratrabecular space. Such actions by ET-1 may exacerbate Dex effects on the outflow pathway leading to increased outflow resistance and consequently elevated intraocular pressure that typically is associated with glucocorticoids. We have also found a significant difference in hGRβ levels among normal versus glaucomatous TM cell lines, with the POAG TM cell lines having lower hGRβ receptor expression. This is coincidence with the fact that in the normal population, there is a low rate of glucocorticoid responders as compared to almost all POAG patients considered as glucocorticoid responders. Overexpression of hGRβ in TM cells, produced by transfecting a hGRβ expression construct, inhibited Dex-induced expression of myocilin, a glaucomatous gene, supporting the contention that hGRβ acts as a negative regulator of glucocorticoid activity. In addition, we studied the machinery of cytoplasm to nuclear transport of hGRβ. We identified that a chaperon protein, hsp90, is a requirement for the nuclear translocation of hGRβ. In conclusion, we have described a novel-signaling pathway for glucocorticoids through the regulation of ET-1 and ET receptors in the anterior segment which have consequences on aqueous humor outflow. We have also demonstrated a possible molecular mechanism by which glucocorticoid responsiveness in POAG patients is achieved as a result of the low level of nuclear hGRβ receptor isoform expression. Furthermore, we have, for the first time, identified hap90 as a chaperon protein for the translocation of hGRβ from the cytoplasm to the nucleus.Item Proteomics-Based Identification of Retinal Protein Networks Impacted by Elevated Intraocular Pressure in the Hypertonic Saline Injection Model of Experimental Glaucoma(MDPI, 2023-08-26) Zaman, Khadiza; Nguyen, Vien; Prokai-Tatrai, Katalin; Prokai, LaszloElevated intraocular pressure is considered a major cause of glaucomatous retinal neurodegeneration. To facilitate a better understanding of the underlying molecular processes and mechanisms, we report a study focusing on alterations of the retina proteome by induced ocular hypertension in a rat model of the disease. Glaucomatous processes were modeled through sclerosing the aqueous outflow routes of the eyes by hypertonic saline injections into an episcleral vein. Mass spectrometry-based quantitative retina proteomics using a label-free shotgun methodology identified over 200 proteins significantly affected by ocular hypertension. Various facets of glaucomatous pathophysiology were revealed through the organization of the findings into protein interaction networks and by pathway analyses. Concentrating on retinal neurodegeneration as a characteristic process of the disease, elevated intraocular pressure-induced alterations in the expression of selected proteins were verified by targeted proteomics based on nanoflow liquid chromatography coupled with nano-electrospray ionization tandem mass spectrometry using the parallel reaction monitoring method of data acquisition. Acquired raw data are shared through deposition to the ProteomeXchange Consortium (PXD042729), making a retina proteomics dataset on the selected animal model of glaucoma available for the first time.Item Role of Glucocorticoids and Glucocorticoid Receptors in Glaucoma Pathogenesis(MDPI, 2023-10-27) Patel, Pinkal D.; Kodati, Bindu; Clark, Abbot F.The glucocorticoid receptor (GR), including both alternative spliced isoforms (GRalpha and GRbeta), has been implicated in the development of primary open-angle glaucoma (POAG) and iatrogenic glucocorticoid-induced glaucoma (GIG). POAG is the most common form of glaucoma, which is the leading cause of irreversible vision loss and blindness in the world. Glucocorticoids (GCs) are commonly used therapeutically for ocular and numerous other diseases/conditions. One serious side effect of prolonged GC therapy is the development of iatrogenic secondary ocular hypertension (OHT) and OAG (i.e., GC-induced glaucoma (GIG)) that clinically and pathologically mimics POAG. GC-induced OHT is caused by pathogenic damage to the trabecular meshwork (TM), a tissue involved in regulating aqueous humor outflow and intraocular pressure. TM cells derived from POAG eyes (GTM cells) have a lower expression of GRbeta, a dominant negative regulator of GC activity, compared to TM cells from age-matched control eyes. Therefore, GTM cells have a greater pathogenic response to GCs. Almost all POAG patients develop GC-OHT when treated with GCs, in contrast to a GC responder rate of 40% in the normal population. An increased expression of GRbeta can block GC-induced pathogenic changes in TM cells and reverse GC-OHT in mice. The endogenous expression of GRbeta in the TM may relate to differences in the development of GC-OHT in the normal population. A number of studies have suggested increased levels of endogenous cortisol in POAG patients as well as differences in cortisol metabolism, suggesting that GCs may be involved in the development of POAG. Additional studies are warranted to better understand the molecular mechanisms involved in POAG and GIG in order to develop new disease-modifying therapies to better treat these two sight threatening forms of glaucoma. The purpose of this timely review is to highlight the pathological and clinical features of GC-OHT and GIG, mechanisms responsible for GC responsiveness, potential therapeutic options, as well as to compare the similar features of GIG with POAG.Item Steroid-Induced Ocular Hypertension in Mice Is Differentially Reduced by Selective EP2, EP3, EP4, and IP Prostanoid Receptor Agonists(MDPI, 2024-03-28) Sharif, Najam A.; Millar, J. Cameron; Zode, Gulab S.; Ota, TakashiWe tested five chemically and metabolically stable prostaglandin (PG) receptor agonists in a mouse model of dexamethasone-induced ocular hypertension (OHT). Whilst all compounds significantly (p < 0.05, ANOVA) lowered intraocular pressure (IOP) after twice-daily bilateral topical ocular dosing (5 microg/dose) over three weeks, the time course and magnitude of the responses varied. The onset of action of NS-304 (IP-PG receptor agonist) and rivenprost (EP4-PG receptor agonist) was slower than that of misoprostol (mixed EP2/EP3/EP4-PG receptor agonist), PF-04217329 (EP2-PG receptor agonist), and butaprost (EP2-PG receptor agonist). The rank order of IOP-lowering efficacies aligned with the onset of actions of these compounds. Peak IOP reductions relative to vehicle controls were as follows: misoprostol (74.52%) = PF-04217329 (74.32%) > butaprost (65.2%) > rivenprost (58.4%) > NS-304 (55.3%). A literature survey indicated that few previously evaluated compounds (e.g., latanoprost, timolol, pilocarpine, brimonidine, dorzolamide, cromakalim analog (CKLP1), losartan, tissue plasminogen activator, trans-resveratrol, sodium 4-phenyl acetic acid, etc.) in various animal models of steroid-induced OHT were able to match the effectiveness of misoprostol, PF-04217329 or butaprost. Since a common feature of the latter compounds is their relatively high affinity and potency at the EP2-PG receptor sub-type, which activates the production of intracellular cAMP in target cells, our studies suggest that drugs selective for the EP2-PG receptor may be suited to treat corticosteroid-induced OHT.Item The regulation of transforming growth factor beta-2-induced ocular hypertension and glaucomatous environment in the trabecular meshwork(2020-12) Roberts, Amanda L.; Clark, Abbot F.; Krishnamoorthy, Raghu R.; Pang, Iok-Hou; Tovar-Vidales, Tara; Gatch, Michael B.Glaucoma is a heterogeneous group of optic neuropathies that damage the optic nerve that leads to progressive visual loss and irreversible blindness in over 80 million people worldwide. Primary open angle glaucoma (POAG) is the most common form of glaucoma, and elevated intraocular pressure (IOP) is the major risk factor for the development and progression of this ocular disease. One of the potential mechanisms responsible for elevated IOP in POAG patients is the excessive accumulation of extracellular matrix (ECM) proteins within the trabecular meshwork (TM). Damage to the TM impairs the aqueous humor outflow and increases aqueous humor outflow resistance, and elevates IOP. Discovering potential new disease modifying targets to lower IOP is necessary to develop effective therapies to inhibit the progression of glaucoma. Here, we explored a novel molecular mechanism involved in the development of glaucomatous TM ECM damage. The effects of transforming growth factor beta 2 (TGF[beta]2) signaling pathways in the TM ECM have been extensively studied. TGF[beta]2 is a profibrotic signaling component in ocular hypertension development that increases ECM deposition in the TM. As a member of the toll-like receptor family, toll-like receptor 4 (TLR4) was originally identified as the receptor for lipopolysaccharide (LPS). TLR4 can also be activated by endogenous ligands known as damaged associated molecular patterns (DAMPS), which are generated as a result of injury, cell damage, and ECM remodeling. DAMP-induced TLR4 activation has been linked to fibrosis, ECM protein deposition, and augmented TGF[beta]2 signaling and downstream fibrotic responses. Recently, we identified TGF[beta]2-TLR4 signaling crosstalk that regulates the TM ECM, and mutation in TLR4 rescues TGF[beta]2-induced ocular hypertension in mice. The goal of this work was to investigate the role of the endogenous TLR4 ligand fibronectin containing extra domain A isoform (FN-EDA), and the TLR4 downstream signaling molecule NF[kappa]B in TGF[beta]2-induced ocular hypertension in mice. Overall, we discovered that TLR4, FNEDA and NF[kappa]B are necessary for TGF[beta]2-induced ocular hypertension and ECM deposition in mice. In addition, constitutively active EDA mice spontaneously develop ocular hypertension. These data provide new targets to lower IOP and inhibit glaucoma disease progression.Item The Role of Wnt/β-catenin Signaling in the Trabecular Meshwork Relating to Ocular Hypertensive Primary Open Angle Glaucoma(2017-05-01) Webber, Hannah C.; Mao, Weiming; Clark, Abbot F.; Pang, Iok-HouOcular hypertension is the greatest causative risk factor of primary open angle glaucoma (POAG), the most prevalent subset of age-related glaucoma. Wnt signaling antagonist sFRP1 is increased in the trabecular meshwork (TM) of patients with POAG and induces ocular hypertension in human ex vivo eyes and in mice, which is resolved upon downstream Wnt/β-catenin signaling activation. The molecular mechanisms behind this remain unknown. β-catenin plays a role as an accessory protein to classical cadherin cytosolic domains, connecting these cell-cell adhesion proteins to the actin cytoskeleton. In other cell types, Wnt/β-catenin signaling crosstalks with the TGFβ/SMAD pathway, which is overactive in the POAG TM and is implicated in ocular hypertension. Our hypothesis is that the Wnt/β-catenin signaling pathway maintains TM cell adhesion and intraocular pressure by stabilizing cadherins junctions on the TM cell membrane and by inhibiting the POAG-related TGFβ/SMAD pathway. We used primary or transformed human non-glaucomatous TM (NTM) cells for all molecular and cell-based studies. NTM cells were treated with reporter viruses to study DNA binding element activity, recombinant protein to modulate Wnt/β-catenin or TGFβ/SMAD pathways, or siRNA to knockdown pathway mediators or cadherins. After treatment, NTM nucleic acid or protein was isolated or probed for Wnt/β-catenin or TGFβ signaling markers or cadherins. Some NTM cells were also plated for Real Time Cell Analysis (RTCA) cell impedance assays. Ad5.CMV recombinant adenoviruses encoding K-cadherin and/or sFRP1 were injected into BALB/cJ mouse eyes. Conscious IOP was assessed for up to 35 days. We found that Wnt/β-catenin signaling cross-inhibits TGFβ signaling in a β-catenin and Smad4-dependent manner. This cross-inhibition resulted in a decreased K-cadherin and fibronectin expression. Wnt/β-catenin signaling also enhanced mRNA, protein, and membrane-bound levels of K-cadherin, the most highly expressed cadherin isoform in the TM. In vivo, K-cadherin reduced the ocular hypertensive effects of sFRP1. RTCA assays showed that Wnt/β-catenin signaling and K-cadherin are responsible for maintenance of TM cell adhesion. Wnt/β-catenin signaling is responsible for intraocular pressure maintenance through increased expression of K-cadherin-mediated TM cell adhesion and through inhibition of TGFβ/SMAD signaling.