Browsing by Subject "Intraocular Pressure / physiology"
Now showing 1 - 6 of 6
- Results Per Page
- Sort Options
Item BMP and Activin Membrane Bound Inhibitor Regulates the Extracellular Matrix in the Trabecular Meshwork(ARVO Journals, 2018-04) Hernandez, Humberto; Millar, J. Cameron; Curry, Stacy M.; Clark, Abbot F.; McDowell, Colleen M.Purpose: The trabecular meshwork (TM) has an important role in the regulation of aqueous humor outflow and IOP. Regulation of the extracellular matrix (ECM) by TGFbeta2 has been studied extensively. Bone morphogenetic protein (BMP) and activin membrane-bound inhibitor (BAMBI) has been shown to inhibit or modulate TGFbeta2 signaling. We investigate the role of TGFbeta2 and BAMBI in the regulation of TM ECM and ocular hypertension. Methods: Mouse TM (MTM) cells were isolated from B6;129S1-Bambitm1Jian/J flox mice, characterized for TGFbeta2 and dexamethasone (DEX)-induced expression of fibronectin, collagen-1, collagen-4, laminin, alpha-smooth muscle actin, cross-linked actin networks (CLANs) formation, and DEX-induced myocilin (MYOC) expression. MTM cells were transduced with Ad5.GFP to identify transduction efficiency. MTM cells and mouse eyes were transduced with Ad5.Null, Ad5.Cre, Ad5.TGFbeta2, or Ad5.TGFbeta2 + Ad5.Cre to evaluate the effect on ECM production, IOP, and outflow facility. Results: MTM cells express TM markers and respond to DEX and TGFbeta2. Ad5.GFP at 100 MOI had the highest transduction efficiency. Bambi knockdown by Ad5.Cre and Ad5.TGFbeta2 increased fibronectin, collagen-1, and collagen-4 in TM cells in culture and tissue. Ad5.Cre, Ad5.TGFbeta2, and Ad5.TGFbeta2 + Ad5.Cre each significantly induced ocular hypertension and lowered aqueous humor outflow facility in transduced eyes. Conclusions: We show for the first time to our knowledge that knockdown of Bambi alters ECM expression in cultured cells and mouse TM, reduces outflow facility, and causes ocular hypertension. These data provide a novel insight into the development of glaucomatous TM damage and identify BAMBI as an important regulator of TM ECM and ocular hypertension.Item C1q propagates microglial activation and neurodegeneration in the visual axis following retinal ischemia/reperfusion injury(BioMed Central Ltd., 2016-03-24) Silverman, Sean M.; Kim, Byung-Jin; Howell, Garreth R.; Miller, Joselyn; John, Simon W. M.; Wordinger, Robert J.; Clark, Abbot F.BACKGROUND: C1q represents the initiating protein of the classical complement cascade, however recent findings indicate pathway independent roles such as developmental pruning of retinal ganglion cell (RGC) axons. Furthermore, chronic neuroinflammation, including increased expression of C1q and activation of microglia and astrocytes, appears to be a common finding among many neurodegenerative disease models. Here we compare the effects of a retinal ischemia/reperfusion (I/R) injury on glial activation and neurodegeneration in wild type (WT) and C1qa-deficient mice in the retina and superior colliculus (SC). Retinal I/R was induced in mice through elevation of intraocular pressure to 120 mmHg for 60 min followed by reperfusion. Glial cell activation and population changes were assessed using immunofluorescence. Neuroprotection was determined using histological measurements of retinal layer thickness, RGC counts, and visual function by flash electroretinography (ERG). RESULTS: Retinal I/R injury significantly upregulated C1q expression in the retina as early as 72 h and within 7 days in the superficial SC, and was sustained as long as 28 days. Accompanying increased C1q expression was activation of microglia and astrocytes as well as a significantly increased glial population density observed in the retina and SC. Microglial activation and changes in density were completely ablated in C1qa-deficient mice, interestingly however there was no effect on astrocytes. Furthermore, loss of C1qa significantly rescued I/R-induced loss of RGCs and protected against retinal layer thinning in comparison to WT mice. ERG assessment revealed early preservation of b-wave amplitude deficits from retinal I/R injury due to C1qa-deficiency that was lost by day 28. CONCLUSIONS: Our results for the first time demonstrate the spatiotemporal changes in the neuroinflammatory response following retinal I/R injury at both local and distal sites of injury. In addition, we have shown a role for C1q as a primary mediator of microglial activation and pathological damage. This suggests developmental mechanisms of C1q may be re-engaged during injury response, modulation of which may be beneficial for neuroprotection.Item Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms(ARVO Journals, 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 S.; 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, Rudolph; 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 A.; 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. DanielDue 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.Item In vitro and in vivo neuroprotective effects of cJun N-terminal kinase inhibitors on retinal ganglion cells(BioMed Central Ltd., 2016-04-21) Kim, Byung-Jin; Silverman, Sean M.; Liu, Yang; Wordinger, Robert J.; Pang, Iok-Hou; Clark, Abbot F.BACKGROUND: The c-Jun N-terminal kinase (JNK) signaling pathway plays an important role in neuronal pathophysiology. Using JNK inhibitors, we examined involvement of the JNK pathway in cultured rat retinal ganglion cell (RGC) death and in mouse retinal ischemia/reperfusion (I/R) injury of the visual axis. The in vitro effects of JNK inhibitors were evaluated in cultured adult rat retinal cells enriched in RGCs. Retinal I/R was induced in C57BL/6J mice through elevation of intraocular pressure to 120 mmHg for 60 min followed by reperfusion. SP600125 was administered intraperitoneally once daily for 28 days. Phosphorylation of JNK and c-Jun in the retina was examined by immunoblotting and immunohistochemistry. The thickness of retinal layers and cell numbers in the ganglion cell layer (GCL) were examined using H&E stained retinal cross sections and spectral domain optical coherence tomography (SD-OCT). Retinal function was measured by scotopic flash electroretinography (ERG). Volumetric measurement of the superior colliculus (SC) as well as VGLUT2 and PSD95 expression were studied. RESULTS: JNK inhibitors SP600125 and TAT-JNK-III, dose-dependently and significantly (p < 0.05) protected against glutamate excitotoxicity and trophic factor withdrawal induced RGC death in culture. In the I/R model, phosphorylation of JNK (pJNK) in the retina was significantly (p < 0.05) increased after injury. I/R injury significantly (p < 0.05) decreased the thickness of retinal layers, including the whole retina, inner plexiform layer, and inner nuclear layer and cell numbers in the GCL. Administration of SP600125 for 28 days protected against all these degenerative morphological changes (p < 0.05). In addition, SP600125 significantly (p < 0.05) protected against I/R-induced reduction in scotopic ERG b-wave amplitude at 3, 7, 14, 21 and 28 days after injury. SP600125 also protected against the I/R-induced losses in volume and levels of synaptic markers in the SC. Moreover, the protective effects of SP600125 in the retina and SC were also detected even with only 7 days (Days 1-7 after I/R) of SP600125 treatment. CONCLUSIONS: Our results demonstrate the important role the JNK pathway plays in retinal degeneration in both in vitro and in vivo models and suggest that JNK inhibitors may be a useful therapeutic strategy for neuroprotection of RGCs in the retina.Item The Role of Wnt/beta-Catenin Signaling and K-Cadherin in the Regulation of Intraocular Pressure(ARVO Journals, 2018-03) Webber, Hannah C.; Bermudez, Jaclyn Y.; Millar, J. Cameron; Mao, Weiming; Clark, Abbot F.Purpose: Wnt/beta-catenin signaling in the trabecular meshwork (TM) is required for maintaining normal intraocular pressure (IOP), although the mechanism(s) behind this are unknown. We hypothesize that Wnt/beta-catenin signaling regulates IOP via beta-catenin's effects on cadherin junctions. Methods: Nonglaucomatous primary human TM (NTM) cells were treated with or without 100 ng/ml Wnt3a, 1 mug/ml sFRP1, or both for 4 to 48 hours. Cells were immunostained for beta-catenin, total cadherins, or cadherin isoforms. Membrane proteins or whole-cell lysates were isolated for Western immunoblotting and probed for cadherin isoforms. RNA was extracted for cDNA synthesis and qPCR analysis of cadherin expression. Some NTM cells were cultured on electric plates for cell impedance assays. Ad5.CMV recombinant adenoviruses encoding K-cadherin, and/or sFRP1 were injected into eyes of 4- to 6-month-old female BALB/cJ mice (n = 8-10). Conscious IOPs were assessed for 35 days. Results: Upon Wnt3a treatment, total cadherin expression increased and beta-catenin accumulated at the TM cell membrane and on processes formed between TM cells. qPCR showed that Wnt3a significantly increased K-cadherin expression in NTM cells (P < 0.01, n = 3), and Western immunoblotting showed that Wnt3a increased K-cadherin in NTM cells, which was inhibited by the addition of sFRP1. Cell impedance assays showed that Wnt3a treatment increased transcellular resistance and anti-K-cadherin siRNA decreased transcellular resistance (P < 0.001, n = 4-6). Our in vivo study showed that K-cadherin significantly decreased sFRP1-induced ocular hypertension (P < 0.05, n = 6). Western immunoblotting also showed that K-cadherin alleviated sFRP1-induced beta-catenin decrease in mouse anterior segments. Conclusions: Our results suggest that cadherins play important roles in the regulation of TM homeostasis and IOP via the Wnt/beta-catenin pathway.Item Upregulation of the endothelin A (ETA) receptor and its association with neurodegeneration in a rodent model of glaucoma(BioMed Central Ltd., 2017-03-01) McGrady, Nolan R.; Minton, Alena Z.; Stankowska, Dorota L.; He, Shaoqing; Jefferies, Hayden B.; Krishnamoorthy, Raghu R.BACKGROUND: Primary open angle glaucoma is a heterogeneous group of optic neuropathies that results in optic nerve degeneration and a loss of retinal ganglion cells (RGCs) ultimately causing blindness if allowed to progress. Elevation of intraocular pressure (IOP) is the most attributable risk factor for developing glaucoma and lowering of IOP is currently the only available therapy. However, despite lowering IOP, neurodegenerative effects persist in some patients. Hence, it would be beneficial to develop approaches to promote neuroprotection of RGCs in addition to IOP lowering therapies. The endothelin system is a key target for intervention against glaucomatous neurodegeneration. The endothelin family of peptides and receptors, particularly endothelin-1 (ET-1) and endothelin B (ETB) receptor, has been shown to have neurodegenerative roles in glaucoma. The purpose of this study was to examine changes in endothelin A (ETA) receptor protein expression in the retinas of adult male Brown Norway rats following IOP elevation by the Morrison's model of ocular hypertension and the impact of ETA receptor overexpression on RGC viability in vitro. RESULTS: IOP elevation was carried out in one eye of Brown Norway rats by injection of hypertonic saline through episcleral veins. After 2 weeks of IOP elevation, immunohistochemical analysis of retinal sections from rat eyes showed an increasing trend in immunostaining for ETA receptors in multiple retinal layers including the inner plexiform layer, ganglion cell layer and outer plexiform layer. Following 4 weeks of IOP elevation, a significant increase in immunostaining for ETA receptor expression was found in the retina, primarily in the inner plexiform layer and ganglion cells. A modest increase in staining for ETA receptors was also found in the outer plexiform layer in the retina of rats with IOP elevation. Cell culture studies showed that overexpression of ETA receptors in 661W cells as well as primary RGCs decreases cell viability, compared to empty vector transfected cells. Adeno-associated virus mediated overexpression of the ETA receptor produced an increase in the ETB receptor in primary RGCs. CONCLUSIONS: Elevated IOP results in an appreciable change in ETA receptor expression in the retina. Overexpression of the ETA receptor results in an overall decrease in cell viability, accompanied by an increase in ETB receptor levels, suggesting the involvement of both ETA and ETB receptors in mediating cell death. These findings raise possibilities for the development of ETA/ETB dual receptor antagonists as neuroprotective treatments for glaucomatous neuropathy.