Eye / Vision

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/29926

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Toll-like Receptor 4, FIbronectin Extra Domain A, and Nuclear Factor kappa B are Necessary for TGFβ2-induced Ocular Hypertension
(2020) McDowell, Colleen; Hernandez, Humberto; Curry, Stacy; Harris, Sherri; Roberts, Amanda
Purpose: Ocular hypertension is the major risk factor for developing primary open-angle glaucoma (POAG). Trabecular meshwork (TM) damage in POAG patients leads to impaired aqueous humor outflow and retinal ganglion cell damage. We explored a novel molecular mechanism involved in glaucomatous TM extracellular matrix (ECM) development through the TGFβ2-TLR4 signaling crosstalk; which regulates TM ECM changes. We discovered that mutations in Tlr4, FN-EDA, and NFkB rescues TGFβ2 -induced ocular hypertension. Methods: B6.FN-EDA+/+, B6.FN-EDA-/-, B6.TLR4-/-, B6.FN-EDA+/+/TLR4-/-, B6.FN-EDA-/-/TLR4-/-, and C57BL/6J mice were intravitreally injected with 2.0µL Ad5.TGFβ2 (2.5x10^7 pfu) in one eye and the contralateral uninjected eye was the control. Likewise, we tested mice lacking the p50 subunit of NFκB (B6.Cg-NFκB1tm1Bal/J) and C57BL/6J mice. IOP was measured weekly using a TonoLab rebound tonometer on isoflurane-anesthetized mice. Significance determined by one-way ANOVA. Eyes were harvested, 4%-paraformaldehyde-fixed, and sectioned for immunohistochemistry to access total fibronectin and FN-EDA isoform expressions. Results: Ad5.TGFβ2 significantly induced ocular hypertension C57BL/6J and B6.EDA+/+ mice. B6.EDA+/+ mice developed spontaneous ocular hypertension. Mutations in Tlr4, FN-EDA, and NFκB blocked Ad5.TGFβ2 -induced ocular hypertension. Total FN and FN-EDA expression increased in uninjected B6.FN-EDA+/+ mice and increased in response to TGFβ2 in wildtype and EDA mice. Conclusions: TLR4, FN-EDA, and NFκB are necessary for TGFβ2 induced ocular hypertension and ECM deposition in mice. These data provide new targets to lower IOP and inhibit glaucoma disease progression.
MCT2 Overexpression Rescues Metabolic Vulnerability and Protects Retinal Ganglion Cells in Two Glaucoma Models
(2020) Inman, Denise; Harun-Or-Rashid, Mohammad; Jassim Jaboori, Assraa; Pappenhagen, Nathaniel
Purpose: The ketogenic diet decreases retinal ganglion cell degeneration in models of glaucoma. Retina and optic nerves from mice on the diet also had elevated expression of monocarboxylate transporter 2 (MCT2), which transports monocarboxylates intracellularly to be used as fuel for mitochondria. We used a viral vector approach to increase expression of MCT2 in retinal ganglion cells (RGCs) to determine if the upregulation of MCT2 without the ketogenic diet could increase RGC survival in glaucoma. Methods: We injected AAV2-CAG2-mSLC16A7-2A-GFP (AAV2:MCT2) intraocularly to infect RGCs and promote MCT2 overexpression in the DBA/2J mouse model of glaucoma and the magnetic microbead induced ocular hypertension (OHT). Retinas and optic nerves were collected; axons were stained with PPD, and RGCs were labeled with RBPMS for counting. Data was compared to DBA/2J-Gpnmb+/+ or sham injected controls. Metabolic proteins of interest were quantified using capillary electrophoresis, and visual function was tested with pattern ERG (PERG). Results: AAV2:MCT2 injection rescued RGCs in both models of glaucoma. Glaucomic mice injected with AAV2:MCT2 had significantly higher axon counts, RGC soma densities, and visual function than glaucomic mice treated with a control virus (AAV2:eGFP). The decreased pAMPK/AMPK ratio indicated that AAV2:MCT2 treated eyes were under less metabolic stress than eyes treated with AAV2:eGFP. PERG traces showed higher P1 amplitude in mice treated with AAV2:MCT2 than in controls, indicating improved visual function in those mice. Conclusions: MCT2 overexpression caused increased RGC survival in two models of glaucoma, suggesting there is a metabolic problem underlying glaucomic degeneration.
A Systemic Pharmacology Analysis of the Age-Related Eye Disease Study 2 (AREDS2) formula and its role in preventing Age-Related Macular Degeneration (AMD)
(2020) Wu, Hongli; Yu, Yu; Lou, Alexander; Garcia, Luis; Tran, Myhoa; Duong, Anh; Wang, Miki; Brown, Erica
Purpose: According to the major clinical trial sponsored by the National Eye Institute (NEI), oral supplementation with the Age-Related Eye Disease Study 2 (AREDS2) formulation (vitamins C and E, zinc, copper, lutein, and zeaxanthin) has been shown to delay the progression of advanced age-related macular degeneration (AMD). However, the detailed pharmacological mechanisms of AREDS2 have not been fully understood at the molecular level, other than its well-known antioxidative effects. In this study, we intend to develop a systemic approach to predict the AREDS2-associated targets and to build the drug-disease-target network. Methods: Genes of interest were identified via the NCBI database for all compounds in the AREDS2 formula. Cytoscape software was used to visually create a network of source and target nodes to analyze similarities between nodes. Cytoscape was again used to identify major pathways the AREDS2 formula targeted. Results: A total of 158 genes were identified to be targets of the AREDS2 formula. 27 out of 158 genes were a result of multiple components of the AREDS2 formula. The main pathways these genes affect were identified and mapped out to include adipogenesis, angiogenesis, apoptosis cascade, DNA damage response, fluid shear stress and atherosclerosis, glutathione metabolism, HIF1 signaling pathway, innate immune pathway, lipoprotein metabolism, Nrf2 pathway and oxidative stress pathway. The top 5 target genes were GSTP1, Nrf2, VEGFA, HIF1A, and CXCL8. Conclusion: The systemic pharmacology-based approach provides beneficial information for elucidating the potential mechanisms of action of the AREDS2 formula in treating AMD.
Functional impairment of TRPV4-eNOS signaling in glaucomatous trabecular meshwork contributes to elevation of intraocular pressure.
(2020) Kasetti, Ramesh; Zode, Gulab S.; Maddineni, Prabhavathi; Sonkusare, Swapnil; Millar, J. Cameron; Chen, Yen-Lin; Patel, Pinkal
Purpose: Nitric oxide (NO) is known to reduce intraocular pressure (IOP) by relaxation of the trabecular meshwork (TM). However, the intrinsic mechanism regulating NO production in the TM is yet to be elucidated. Here, we examined whether transient receptor potential vanilloid 4 (TRPV4) channels regulate IOP via endothelial nitic oxide synthase (eNOS) signaling. We also assess whether TRPV4-eNOS signaling is impaired in glaucoma. Methods: In WT C57BL/6J mice, the effect of the TRPV4 agonist GSK1016790A (GSK101) on IOP and outflow facility was determined using rebound tonometry and constant-flow infusion method, respectively. The effect of GSK101 on eNOS activation and NO production was determined using Western blot and a fluorometric DAF-FM assay in normal and glaucomatous primary human TM cells. We further examined whether TRPV4 channel function is impaired in glaucoma using high-speed Calcium imaging in normal and glaucomatous human primary TM cells. Results: Topical administration of GSK101 (20 µM) significantly improved outflow facility (P=0.05) and reduced IOP (P< 0.0001) in WT mice. GSK101 (20 nM) treatment resulted in increased eNOS phosphorylation in primary human TM cells and donor tissues. GSK101 treatment also resulted in increased DAF-FM fluorescence, which signifies an increase in NO production. Importantly, human glaucomatous primary TM cells exhibited significantly attenuated Calcium influx, eNOS phosphorylation, and NO production in response to GSK101 when compared to normal human primary TM cells. Conclusion: TRPV4 channel activation lowers IOP by regulating NO in the TM. Functional impairment of these channels may contribute to glaucomatous pathophysiology.
Synthesis and in vitro study of dual acting hybrid compound for treating Glaucoma
(2020) Stankowska, Dorota; Acharya, Suchismita; Ellis, Dorette; Weston, Courtney; Li, Linya; Gondi, Sudershan
Purpose: Glaucoma presents with high intraocular pressure (IOP) due to decreased aqueous humor outflow and impaired trabecular meshwork (TM). Increased IOP affects the optic nerve head leading to degeneration of retinal ganglion cells (RGC's). Currently many therapies aim to reduce IOP, however they do not address the damage done to the RGCs. Our goal is to find a multifunctional molecule that can lower IOP while also being neuroprotective. For this project, we planned to synthesize a series of compounds and evaluate their cellular activity in primary human TM cells. Methods: Compounds SA-2, PLGA encapsulated SA-2 nanoparticles (NP) and SA-24 were synthesized. Proton NMR and dynamic light scattering methods were used to determine structure and particle size. Greiss assay was used to assess total nitrite and reactive oxygen species (ROS) scavenging assay was performed following the manufacturer's protocol. Next, primary hTM-80 cells were seeded in 96 well plates to confluency, and exposed to tert-butyl hydrogen peroxide (TBHP, 300uM) for 15 min. followed by treatment with the compounds. The cell proliferation was measured using MTT assays (Promega). The experiments were done in quadruplicates. Results: SA-2, SA-2NP and SA-24 were equally effective in scavenging ROS at 250 µM and SA-2 provided highest amount of NO. Compound SA-2 (200uM) and SA-2NP (1%) significantly protect TBHP induced decreased cell proliferation. Conclusion: Compound SA-2 has both NO releasing and ROS scavenging activity. As expected, SA-2NP has slow release profile and better proliferative activity.
Emerging functional crosstalk between the glutaredoxin system and Nrf2 antioxidant pathway: evidence from ultraviolet radiation-induced cataract formation
(2020) Yu, Yu; Lou, Alexander; Garcia, Luis; Tran, Myhoa; Duong, Anh; Wu, Hongli; Liu, Xiaobin
Purpose: To determine the function of glutaredoxin (Grx) system, both glutaredoxin 1 (Grx1) and glutaredoxin 2 (Grx2), in protecting the lens against ultraviolet (UV)-induced cataract formation by using Grx1/Grx2 double knockout (DKO) mice as a model. Methods: One-month old Grx1/Grx2 DKO and age-matched wild-type (WT) mice were exposed to UV radiation to induce cataracts. Mice were euthanized at 4 days post-exposure. The degree of the cataract and lens morphology were evaluated under a dissecting microscope. Glutathione (GSH), free protein thiol(PSH), and protein glutathionylation (PSSG) levels were measured as general markers of oxidative damage. Nrf2 and its downstream target proteins were examined using Western blot. Results: We found that UV radiation caused more severe anterior subcapsular cataract in Grx1/Grx2 DKO than that of WT mice. The opacity of the lenses in DKO mice appeared to extend deeper into the cortical and even nuclear regions. Lenses of Grx1/Grx2 DKO mice contained significant lower levels of GSH and PSH. On the other hand, the accumulation of PSSG was much higher in Grx1/Grx2 DKO group. Deletion of Grx1 and Grx2 also decreased the expression of antioxidant enzyme transcription factor regulator, Nrf2, and its downstream antioxidant genes, including catalase, superoxide dismutase (SOD), and another redox regulator of thioredoxin (Trx). These changes were especially extensive in the lens after UV exposure. Conclusions: With combined Grx1 and Grx2 deletion, the Nrf2-dependent antioxidant response is severely impaired, causing elevation of oxidative stress that may increase the lens susceptibility to UV-induced damage.
Refractive Error and Amblyogenic Risk Factors in Pre-School Children
(2020) Aryal, Subhash; Galvan, Coulter; Zielke, Cameron; Mozdbar, Sima; Aiken, Julia
Amblyopia is the most common cause of vision loss in children and is defined as reduced visual acuity in the absence of ocular pathology. Early detection and treatment of children identified as having amblyogenic risk factors, including high refractive error, is imperative in reducing long-term visual impairment. This study determines the prevalence of refractive errors and amblyogenic risk factors in children aged 3-5 years and attending Fort Worth, Texas schools. Researchers performed vision screenings in 20 elementary schools. The sample was delimited to children 5 years and younger (N=1,769). Binomial variables indicating refractive errors (hyperopia, myopia, astigmatism and anisometropia) were created to execute frequencies and Chi-Square tests amongst race/ethnicity and gender. Participants were also stratified by presence of any amblyogenic risk factors. Those with at least one refractive error accounted for 32% of the sample. Nearly 1% (n=22) had an amblyogenic risk factor. No significant presence of refractive errors by gender were present, but significance appeared amongst Hispanic (p< .0001), Black (p< .0001), and Asian (p< .0460) children. Hispanic and Black children had 3.445 (95%, CI=2.418-4.909) and 2.912 (95%, CI=1.947-4.357) higher odds, respectively, of having a refractive error than their White counterparts. Significant differences in refractive errors by race and ethnicity align with findings in previous studies. The prevalence of uncorrected refractive errors indicates a potential for learning difficulties and developmental challenges. These findings support the importance of routine vision screening and the need for community-targeted education regarding comprehensive eye examinations.
Topical steroid induced retinopathy
(2020) Chavala, Sai; DeCrescenzo, Andrew; Menter, Alan; Hilton, Taylor
Introduction: Central serous chorioretinopathy (CSCR) is a condition defined by subretinal fluid accumulation in the area of the macula leading to serous detachment, which can lead to irreversible vision loss. Oral administration of corticosteroids has long been known to be a factor contributing to CSCR in patients. Rarely, topical steroids have been reported to elicit this adverse effect. We report a case of a patient with two separate episodes of CSCR induced by the use of topical steroids. Case Report: A 48-year-old male with a history of psoriasis was using intermittent topical clobetasol for a recent flair of his psoriasis. He presented with new-onset blurred vision in the left eye after application of clobetasol to the tip of his nose, eyebrows, and periauricular skin. The patient was evaluated by a retina specialist and was found to have CSCR in the left eye. The patient was advised to discontinue steroid usage at that time. At two months follow up, the subretinal fluid associated with CSCR was completely resolved Six months later, the patient restarted clobetasol and within two weeks presented to the retina specialist and was found to have a relapse in CSCR. The patient once again discontinued topical steroids and the subretinal fluid resolved. Discussion: This case illustrates a rare finding of central serous chorioretinopathy induced by topical steroids twice in the same patient.
Endothelin-1 Mediated Decrease in Mitochondrial Gene Expression and Bioenergetics Contribute to Neurodegeneration of Retinal Ganglion Cells.
(2020) Chaphalkar, Renuka M.
Endothelin-1 (ET-1) is a vasoactive peptide that is elevated in aqueous humor as well as circulation of primary open angle glaucoma (POAG) patients. ET-1 has been shown to promote degeneration of optic nerve axons and apoptosis of retinal ganglion cells (RGCs), however, the precise mechanisms are still largely unknown. In this study, RNA-seq analysis was used to assess changes in ET-1 mediated gene expression in primary RGCs, which revealed that 23 out of 156 differentially expressed genes (DEGs) had known or predicted mitochondrial function, of which oxidative phosphorylation emerged as the top-most enriched pathway. ET-1 treatment significantly decreased protein expression of key mitochondrial genes includ-ing cytochrome C oxidase copper chaperone (COX17) and ATP Synthase, H+ transporting, Mitochondrial Fo Complex (ATP5H) in primary RGCs and in vivo following intravitreal ET-1 injection in rats. A Seahorse ATP rate assay revealed a significant decrease in the rate of mitochondrial ATP production following ET-1 treatment. IOP elevation in Brown Norway rats showed a trend towards decreased expression of ATP5H. Our results demonstrate that ET-1 produced a decrease in expression of vital components of mitochondrial electron transport chain, which compromise bioenergetics and suggest a mechanism by which ET-1 promotes neurodegeneration of RGCs in glaucoma.
PEA-15 Knockdown Decreases Phagocytosis Function in Astrocytes
(2020) Liu, Yang; Pang, Iok-Hou; Bussan, Emily
Purpose: We used a phosphoproteomic approach to assess retinal proteins whose phosphorylation was affected by optic nerve (ON) injury. This study is to localize one of these proteins, Phosphoprotein Enriched in Astrocytes (PEA-15), in the retina and ON, and to test effect of siRNA knockdown PEA-15 on phagocytic function of astrocytes. Methods: Mouse retinal proteins labeled with CyDye-C2 were subjected to 2D-PAGE to determine changes of protein phosphorylation following ON crush. Protein spots with significant changes were selected for protein sequence analysis. Western blot and immunohistochemistry were used to confirm phosphorylation and localize PEA-15 in the retina and ON. Knockdown of PEA-15 protein in cultured mouse ON astrocytes by siRNA was confirmed by western blot. Phagocytic activity was assessed using pHrodo-conjugated synaptosomes. Results: PEA-15 phosphorylation was significantly augmented (ratios ≥ 1.5) in retinas of eyes with ON injury compared to control eyes. Densitometry analysis of western blots confirmed that ON crush significantly increased PEA-15 phosphorylation. PEA-15 was localized by immunohistochemistry in astrocytes in retina and ON. Treatment of cultured mouse astrocytes by PEA-15 targeted siRNA successfully knocked down PEA-15 protein as indicated by western blot. Knockdown of PEA-15 significantly (p< 0.05) suppressed the phagocytic activity of astrocytes compared to control cells containing PEA-15 protein. Conclusion: PEA-15 protein is present in retinal and ON astrocytes. Knockdown of this protein decreased phagocytic activity of these cells, suggesting PEA-15 is involved in the phagocytic function of astrocytes.
Role of TGFβ2 and miRNAs in optic nerve head fibrosis
(2020) Tovar-Vidales, Tara; Clark, Abbot; Lopez, Navita
Purpose: Glaucoma is characterised by degeneration of retinal ganglion cells (RGCs) and loss of visual function. This is associated with extracellular matrix (ECM) remodelling of the optic nerve head (ONH). The ONH provides mechanical and biochemical support to unmyelinated RGC axons as they exit the eye to form the optic nerve; thus, changes in the ONH affect the physiology of axons and may damage the visual circuitry. In glaucoma, mechanosensitive cells in the ONH respond to elevated pressure by secreting growth factors, ECM and inflammatory cytokines that damage RGCs and remodel the ONH. A key upregulated pathway in glaucoma is TGFβ2, which leads to increased expression of profibrotic genes. We hypothesised that impaired regulation of TGFβ2 and miRNAs is involved in glaucomatous remodelling of the ONH ECM. The purpose of this study was to identify cell-specific changes in glaucoma pathophysiology. Method: ONH astrocytes and lamina cribrosa (LC) were treated with TGFβ2 (5ng/ml) or vehicle and analyzed by miRNA qPCR arrays and NGS. Cells were transfected with candidate miRNA mimics, inhibitors, or non-targeting siRNA (10nM) to determine ECM expression. Results: TGFβ2 treatment decreased the expression of multiple antifibrotic miRNAs, which was associated with increased expression of several profibrotic genes including collagen I and IV and fibronectin. Overexpression of antifibrotic miRNAs including miR-29c-3p and miR-200b-3p decreased TGFβ2 induced collagen I and IV and fibronectin expression. Conclusion: TGFβ2 modulated the expression of several miRNAs to stimulate a profibrotic response; this may lead to pathogenic ONH remodelling.
Neuroprotective effects of SB203580 (p38 MAP kinase inhibitor) against Endothelin-1-induced retinal ganglion cell death
(2020) He, Shaoqing; Chaphalkar, Renuka; Kodati, Bindu; Krishnamoorthy, Raghu; Krishnamoorthy, Vignesh
Purpose: Endothelin-1 (ET-1) is a vasoactive peptide contributing to neurodegeneration in glaucoma, however, the underlying mechanisms are not completely understood. The current study tested the involvement of the p38 MAP kinase in ET-1-induced cell death in primary rat retinal ganglion cells (RGCs). Methods: Primary RGCs were treated for 24 hours with 100nM ET-1 either in the presence or absence of the p38 MAP kinase inhibitor SB203580. A Live/Dead assay was used to determine cell viability and the number of surviving and dying/dead cells were quantitated. Results: ET-1 induced RGC death following a 24 hour treatment (as seen by an increase in the dead/live ratio from 0.446 to 0.621), compared to untreated controls. Interestingly, compared to the untreated controls, an appreciable decrease in cell death was found in cells treated with SB203580 alone (a decrease in the dead/live ratio from 0.446 to 0.243). Following treatment with a combination of ET-1 and SB203580, cell counts showed a decrease in cell death when compared with cells treated with ET-1 alone (a change in the dead/live ratio from 0.621 to 0.333). Conclusions: The p38 MAP kinase pathway is known to be involved in signaling mechanisms underlying numerous pathways related to cellular stress. The current study suggests that p38 MAP kinase contributes to ET-1-mediated RGC death. Elucidation of endothelin-mediated signaling pathways will help understand mechanisms by which endothelins promote neurodegeneration in glaucoma.
Inhibition of Chronic Endoplasmic Reticulum Stress Prevents TGFβ2-induced ECM Accumulation in Human Trabecular Meshwork Cells
(2020) Zode, Gulab; Kasetti, Ramesh; Patil, Shruti
Purpose: TGFβ2 is known to be involved in the pathogenesis of primary open angle glaucoma. TGFβ2-induced ECM accumulation is associated with glaucomatous trabecular meshwork (TM) damage and IOP elevation. Previously, we have demonstrated that dexamethasone-induced abnormal ECM accumulation leads to ER stress in TM. Here, we investigated whether TGFβ2 induces ER stress in human TM cells and whether chronic ER stress plays a pathological role in dysfunction of TM cells. Methods: Transformed GTM3 cells or primary human TM cells were treated with vehicle or recombinant TGFβ2 (5ng/mL) to determine its effect on expression of chronic ER stress markers and ECM proteins using Western blot (WB) and immunostaining. Further, chronic ER stress induced ATF4 or CHOP were knock down in these cells using CRISPR/Cas9 technology. The endogenous ATF4 activity was also inhibited by transducing with ad5 ATF4􀀀RK followed by TGFβ2 treatment. Results: WB analysis demonstrated TGFβ2 induced ER stress as evident from increased levels of GRP78, GRP94, ATF4 and CHOP proteins. Immunostaining revealed that TGFβ2 treatment increased fibronectin and collagen IV levels and its colocalization with ER stress markers (KDEL and calreticulin), suggesting TGFβ2-induced ECM proteins are associated with ER stress. Knockdown of key chronic ER stress transcriptional factors, ATF4 or CHOP prevented TGFβ2-induced ECM deposition and also reduced ER stress in TM cells. Treatment of TM cells with small molecule, PBA also inhibited TGFβ2-induced fibronectin deposition. Conclusion: These data indicate that TGFβ2 induces chronic ER stress, which is associated with increased ECM accumulation.
Sodium 4-phenylbyrate rescues glucocorticoid-induced ocular hypertension by reducing abnormal ECM deposition in the TM via activation of MMP9
(2020) Kasetti, Ramesh; Zode, Gulab; Maddineni, Prabhavathi
Purpose: Ocular hypertension (OHT) is a serious side effect of glucocorticoid (GC) therapy and if left undiagnosed, it leads to glaucoma. Previously, we have shown that, sodium-4-phenylbutyrate (PBA) rescues GC-induced OHT. However, the exact mechanism behind PBA mediated reduction of GC-induced OHT is not completely understood. Here, we examined whether PBA rescues GC-induced OHT by reducing abnormal ECM deposition via activating MMP. Methods: GC-induced OHT mice were topically instilled 1% PBA or vehicle twice daily. IOPs and outflow facility were analyzed. Immunostaining, western blot and qPCR were performed to analyze the effect of PBA on GC-induced ECM deposition and ER stress in primary human TM cells, mouse and ex-vivo cultured human TM tissues. Effect of PBA on MMP's activity was analyzed by zymography. Results: Topical PBA eye-drops reduced GC-induced OHT and improved outflow facility significantly. PBA reduced GC-induced intracellular and extracellular ECM accumulation, and prevented induction of ER stress in primary human TM cells, ex-vivo human cultured TM tissues and mouse TM tissues. We observed that PBA can reduce existing ECM deposition when primary TM cells were grown on decellularized GC-treated ECM. Gene expression, western blot and zymography assays revealed that PBA induces increased expression and activity of MMP-9. Inhibition of MMP-9 activity by chemical-inhibitors abrogated PBA's effect on ECM reduction. Conclusions: PBA can be a very attractive treatment for general POAG via targeting abnormal ECM accumulation in the TM.
Endothelin B (ETB) receptor selective agonist endothelin 3 (ET-3) andmediated RGC death and implication for glaucoma.
(2020) Kodati, Bindu; Krishnamoorthy, Raghu; Stankowska, Dorota; Harris, Payton; Wisniewski, Zoe; Krishnamoorthy, Vignesh; Beall, Kallen
Purpose: To determine if dietary administration of the dual ETA/ ETB receptor antagonist, macitentan, could protect retinal ganglion cells (RGCs) from cell death following an intravitreal injection of endothelin-1 (ET-1) and endothelin-3 (ET-3) in Brown Norway rats. Methods: Brown Norway rats (n=3 per group) were either untreated or treated with macitentan (5 mg/kg body weight) once a day for 3 days, followed by intravitreal injection of either 4 µl of 500 µM ET-1, ET-3 (2 nmole/eye) or vehicle in one eye. Following the injections, treatments with either macitentan or control gels without macitentan was continued for 7 days. After the treatments, retinal flat mounts were prepared and surviving RGCs were counted in a masked manner. Results: ET-1 produced 46% increase in RGC loss (p< 0.0001), compared to contralateral control eyes in rats 7 days post intravitreal administration. Macitentan treatment modestly protected from RGC loss following intravitreal ET-1 injection (27% RGC loss). ET-3 administration caused a modest increase (23%) in RGC death in this acute model, however, macitentan did not cause any further improvement in RGC survival (25% RGC loss). Conclusion: Both ET-1 and ET-3 mediate RGC loss following intravitreal administration in rats. Endothelin receptor antagonists have the potential to be developed as neuroprotective agents for the treatment of glaucoma.
Novel Peptain for Neuroprotection in Glaucoma
(2020) Stankowska, Dorota; Krishnamoorthy, Vignesh; Krishnamoorthy, Raghu; Chaphalkar, Renuka; Nagaraj, Ram; Nahomi, Rooban; Nam, Mi-hyun; Beall, Kallen; Brodrick, Ashley; Kodati, Bindu
Purpose: To determine if intravitreal administration of the core peptide of [alpha]-B crystallin, peptain-1 (P1) conjugated to a cell permeable peptide (CPP) (named P1-CPP) could inhibit retinal ganglion cell (RGC) death and functional decline in a rodent model of glaucoma. Methods: Primary RGCs were treated with endothelin-3 (ET-3) in the presence of either P1-CPP (12.5 µg/ml) or vehicle, following which RGC survival was assessed. In a different set of experiments, intraocular pressure (IOP) was elevated in one eye of Brown Norway (BN) rats and intravitreally injected with 2 µl of either P1-CPP or vehicle, once in a week for 6 weeks. RGC function was assessed by the pattern electroretinogram (PERG) amplitude. Retinal flat mounts were imaged and surviving RGCs were counted. Results: ET-3 treatment lead to 24% of RGCs loss compared to vehicle treated cells (p< 0.0001). P1-CPP treatment significantly lowered the ET-3-mediated cell loss (7% cell death, p< 0.001). IOP elevation in vehicle injected animals produced 11% and 27% loss of RGCs, in central and peripheral retina respectively, which was significantly lower in P1-CPP treated rats (7% loss in both eccentricities, **p< 0.01). P1-CPP treatment also promoted axonal protection during IOP elevation. IOP elevation caused 63% decline in the PERG amplitude (*p< 0.03) in comparison with naïve rats, which was sustained by P1-CPP treatment. Conclusion:The intravitreally injected P1-CPP provides cellular as well as functional protection of RGCs, which could facilitate neuroprotection against glaucomatous insults.
Ethmoid Sinusitis as a Possible Differential in Orbital Complications
(2020) Marcincuk, Michelle; Jung, Esther
Background: Reoccurring orbital complications due to sinusitis are rare and are evidenced in limited literature. This case study attempts to provide insight into the broad differential of periorbital swelling through a pediatric patient who presented twice with orbital complications due to ethmoid sinusitis. Case Presentation: An 8-month-old male presented to the emergency department with periorbital cellulitis and evidence of ethmoid sinusitis in the left eye. Following intravenous clindamycin, the patient improved and was discharged. A year and a half later, the patient presented with fever and swelling in the same eye; however, this time he was unresponsive to antibiotics. A computerized tomography (CT) scan identified left postseptal orbital cellulitis with a subperiosteal abscess. After an endoscopic left maxillary antrostomy, total ethmoidectomy, and decompression of the orbital abscess, the patient recovered well with no changes in vision and no reoccurrences of orbital complications to date. Conclusions: Although orbital abscesses due to ethmoid sinusitis are quite rare, it is important to consider ethmoid sinusitis as a primary cause. The treatment options include surgical intervention that must take place rapidly to avoid irreversible consequences. The risk of radiation exposure in this population is further complicated since orbital abscesses due to primary sinusitis can only be definitively diagnosed by CT imaging. It is important for healthcare providers to keep ethmoid sinusitis in mind when considering the differential of periorbital swelling to minimize the risk of permanent complications in their pediatric patients.

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