scholarly journals Evaluation of the Effectiveness of a Chronic Ocular Hypertension Mouse Model Induced by Intracameral Injection of Cross-Linking Hydrogel

2021 ◽  
Vol 8 ◽  
Author(s):  
Junjue Chen ◽  
Jun Sun ◽  
Huan Yu ◽  
Ping Huang ◽  
Yisheng Zhong
Keyword(s):  
Intraocular Pressure ◽  
Optic Nerve ◽  
Ocular Hypertension ◽  
Retinal Ganglion Cells ◽  
Cell Activation ◽  
Ganglion Cells ◽  
Cross Linking ◽  
Control Group ◽  
Retinal Ganglion ◽  
Intracameral Injection

Background: Glaucoma is an irreversible and blinding neurodegenerative disease that is characterized by progressive loss of retinal ganglion cells. The current animal models of glaucoma fail to provide a chronic elevated intraocular pressure and cannot maintain the optical media clarity for a long time, which brings some difficulties to the study of glaucoma. Here, we developed a new chronic ocular hypertension model of mice induced by cross-linking hydrogel intracameral injection.Methods: C57BL/6J mice aged 6–8 weeks were randomly divided into the control group and the operation group. The mice of the operation group were injected with cross-linking hydrogel to induce ocular hypertension. Intraocular pressure was measured preoperatively, 3 days after surgery, and weekly until the end of the study. Flash visual evoked potential (F-VEP) was used to observe optic nerve function at different times (preoperatively and 2, 4, and 6 weeks) after chronic ocular hypertension (COH). Retinal TNF-α, IL-1β, and IL-17A protein expression were measured by western blotting in the control group and in mice at 2, 4, and 6 weeks after COH. Microglial cell activation was evaluated by immunofluorescence staining and western blotting. Apoptosis and loss of retinal ganglion cells after 2, 4, and 6 weeks of intracameral injection of cross-linking hydrogel were observed by the TUNEL assay and Brn3a protein labeling. The loss of optic nerve axons in COH mice was evaluated by neurofilament heavy polypeptide protein labeling.Results: Intracameral injection of the cross-linking hydrogel induces increased intraocular pressure (IOP) to a mean value of 19.3 ± 4.1 mmHg, which was sustained for at least 8 weeks. A significant difference in IOP was noted between COH mice and sham-operation mice (p < 0.0001). The success rate was 75%. The average amplitude of F-VEP in mice with COH was reduced (p = 0.0149, 0.0012, and 0.0009 at 2, 4, and 6 weeks after COH vs. the control group, respectively), and the average latent period in mice with COH was longer (p = 0.0290, <0.0001, and <0.0001 at 2, 4, and 6 weeks after COH vs. the control group, respectively) compared with that in the control group. TNF-α, IL-1β, IL-17A, Iba-1, and CD68 protein expression increased in COH mice. During the processing of COH, the number of microglial cells increased along with cellular morphological changes of rounder bodies and thicker processes compared with the control group. Apoptosis of retinal ganglion cells (RGCs) was clearly observed in mice at 2, 4, and 6 weeks after COH (p = 0.0061, 0.0012, <0.0001, and 0.0371 at 2, 4, and 6 weeks after COH vs. the control group, respectively). The RGC density decreased significantly in the COH mice compared with the control group (p = 0.0042, 0.0036, and <0.0001 at 2, 4, and 6 weeks after COH vs. the control group, respectively). There was a significant loss of optic nerve axons in mice after intracameral injection of cross-linking hydrogel (p = 0.0095, 0.0002, and <0.0001 at 2, 4, and 6 weeks after COH vs. the control group, respectively).Conclusions: A single intracameral injection of cross-linking hydrogel can effectively induce chronic ocular hypertension in mice, which causes progressive loss of retinal ganglion cells, increased expression levels of inflammatory cytokines and microglial cell activation, and deterioration of optic nerve function.

scholarly journals An Overview of Glaucoma: Bidirectional Translation between Humans and Pre-Clinical Animal Models

2021 ◽  
Author(s):  
Sophie Pilkinton ◽  
T.J. Hollingsworth ◽  
Brian Jerkins ◽  
Monica M. Jablonski
Keyword(s):  
Risk Factor ◽  
Intraocular Pressure ◽  
Optic Nerve ◽  
Animal Models ◽  
Retinal Ganglion Cells ◽  
Optic Nerve Head ◽  
Ganglion Cells ◽  
Treatment Modalities ◽  
Retinal Ganglion ◽  
Glaucomatous Damage

Glaucoma is a multifactorial, polygenetic disease with a shared outcome of loss of retinal ganglion cells and their axons, which ultimately results in blindness. The most common risk factor of this disease is elevated intraocular pressure (IOP), although many glaucoma patients have IOPs within the normal physiological range. Throughout disease progression, glial cells in the optic nerve head respond to glaucomatous changes, resulting in glial scar formation as a reaction to injury. This chapter overviews glaucoma as it affects humans and the quest to generate animal models of glaucoma so that we can better understand the pathophysiology of this disease and develop targeted therapies to slow or reverse glaucomatous damage. This chapter then reviews treatment modalities of glaucoma. Revealed herein is the lack of non-IOP-related modalities in the treatment of glaucoma. This finding supports the use of animal models in understanding the development of glaucoma pathophysiology and treatments.

scholarly journals Therapeutic Drugs and Devices for Tackling Ocular Hypertension and Glaucoma, and Need for Neuroprotection and Cytoprotective Therapies

2021 ◽  
Vol 12 ◽  
Author(s):  
Najam A. Sharif
Keyword(s):  
Optic Nerve ◽  
Anterior Chamber ◽  
Ocular Hypertension ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Surgical Techniques ◽  
Nitric Oxide Donor ◽  
Glaucomatous Optic Neuropathy ◽  
Retinal Ganglion ◽  
Outflow Pathway

Damage to the optic nerve and the death of associated retinal ganglion cells (RGCs) by elevated intraocular pressure (IOP), also known as glaucoma, is responsible for visual impairment and blindness in millions of people worldwide. The ocular hypertension (OHT) and the deleterious mechanical forces it exerts at the back of the eye, at the level of the optic nerve head/optic disc and lamina cribosa, is the only modifiable risk factor associated with glaucoma that can be treated. The elevated IOP occurs due to the inability of accumulated aqueous humor (AQH) to egress from the anterior chamber of the eye due to occlusion of the major outflow pathway, the trabecular meshwork (TM) and Schlemm’s canal (SC). Several different classes of pharmaceutical agents, surgical techniques and implantable devices have been developed to lower and control IOP. First-line drugs to promote AQH outflow via the uveoscleral outflow pathway include FP-receptor prostaglandin (PG) agonists (e.g., latanoprost, travoprost and tafluprost) and a novel non-PG EP2-receptor agonist (omidenepag isopropyl, Eybelis®). TM/SC outflow enhancing drugs are also effective ocular hypotensive agents (e.g., rho kinase inhibitors like ripasudil and netarsudil; and latanoprostene bunod, a conjugate of a nitric oxide donor and latanoprost). One of the most effective anterior chamber AQH microshunt devices is the Preserflo® microshunt which can lower IOP down to 10–13 mmHg. Other IOP-lowering drugs and devices on the horizon will be also discussed. Additionally, since elevated IOP is only one of many risk factors for development of glaucomatous optic neuropathy, a treatise of the role of inflammatory neurodegeneration of the optic nerve and retinal ganglion cells and appropriate neuroprotective strategies to mitigate this disease will also be reviewed and discussed.

scholarly journals miRNA Changes in Retinal Ganglion Cells after Optic Nerve Crush and Glaucomatous Damage

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1564
Author(s):  
Ben Mead ◽  
Alicia Kerr ◽  
Naoki Nakaya ◽  
Stanislav I. Tomarev
Keyword(s):  
Optic Nerve ◽  
Ocular Hypertension ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Optic Nerve Crush ◽  
Retinal Ganglion ◽  
Nerve Crush ◽  
Rat Retina ◽  
Retinal Injury ◽  
Generation Sequencing

The purpose of this study was to characterize the miRNA profile of purified retinal ganglion cells (RGC) from healthy and diseased rat retina. Diseased retina includes those after a traumatic optic nerve crush (ONC), and after ocular hypertension/glaucoma. Rats were separated into four groups: healthy/intact, 7 days after laser-induced ocular hypertension, 2 days after traumatic ONC, and 7 days after ONC. RGC were purified from rat retina using microbeads conjugated to CD90.1/Thy1. RNA were sequenced using Next Generation Sequencing. Over 100 miRNA were identified that were significantly different in diseased retina compared to healthy retina. Considerable differences were seen in the miRNA expression of RGC 7 days after ONC, whereas after 2 days, few changes were seen. The miRNA profiles of RGC 7 days after ONC and 7 days after ocular hypertension were similar, but discrete miRNA differences were still seen. Candidate mRNA showing different levels of expression after retinal injury were manipulated in RGC cultures using mimics/AntagomiRs. Of the five candidate miRNA identified and subsequently tested for therapeutic efficacy, miR-194 inhibitor and miR-664-2 inhibitor elicited significant RGC neuroprotection, whereas miR-181a mimic and miR-181d-5p mimic elicited significant RGC neuritogenesis.

scholarly journals Neuroprotective effect of Erigeron Breviscapus (vant) Hand-mazz extract on retinal ganglion cells in rabbits with chronic elevated intraocular pressure

2011 ◽  
Vol 5 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Yi-sheng Zhong ◽  
Min-hong Xiang ◽  
Wen Ye ◽  
Ping Huang ◽  
Yu Cheng ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Optic Nerve ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Neuroprotective Effect ◽  
Treated Group ◽  
Ultrastructural Changes ◽  
Retinal Ganglion ◽  
Elevated Intraocular Pressure ◽  
Erigeron Breviscapus

Abstract Background: Retinal ganglion cells (RGCs) are protected in rats with acute elevated intraocular pressure (IOP) by Erigeron breviscapus (vant.) hand-mazz (EBHM). However, it is unclear whether EBHM has neuroprotective effect on RGCs in animal with chronic elevated IOP. Objective: Investigate the protective effect of EBHM extract on RGCs in rabbits with chronic elevated IOP. Methods: Unilateral chronic elevated IOP was produced in rabbits by repeated injection of 2% methylcellulose into the anterior chamber. Secondary degeneration was measured with and without EBHM extract treatment for 60 days. At 60 days, the cells density of the RGCs layer, the thickness of retinal nerve fiber layer (RNFL), and the optic nerve axons were observed and analyzed using an image analysis system. The ultrastructural changes of RGCs and optic nerve axons were observed using transmission electron microscopy. Results: Compared with their contralateral control eyes with normal IOP, in the retinas of 3-4 mm from the optic disc, the cells density of the RGCs layer in the eyes with chronic elevated IOP was 23.2±6.5 cells (n = 6) and 36.0±8.9 cells (n = 10) per three 400x fields at 60 days in untreated and EBHM-treated group, respectively. The RNFL thickness in eyes with chronic elevated IOP was 3.4±0.4 μm (n = 6) and 5.0±1.0 μm (n = 10) at 60 days in untreated and EBHM-treated group, respectively. The axons number per 15057.8 μm2 in eyes with chronic elevated IOP was 370.4±41.0 (n = 6) and 439.0±50.8 (n = 10) at 60 days in untreated and EBHM-treated group, respectively. The number of the organelles in RGCs plasm appeared decreased and mitochondrion vacuolated in the elevated IOP eyes of EBHM-treated group, while some dispersive mitochondrion and rough surfaced endoplasmic reticulum and ribosome still existed in the RGCs plasm. The myelin sheath plates condensed and degenerated, and the microfilaments and microtubules decreased or disappeared in the elevated IOP eyes, but the axons degeneration in the chronic elevated IOP with EBHM treatment was less than that in the chronic elevated IOP without treatment. Conclusion: EBHM extract provided a neuroprotective effect on retinal ganglion cells in rabbits with chronic elevated IOP.

scholarly journals Oral administration of a dual ETA/ETB receptor antagonist promotes neuroprotection in a rodent model of glaucoma

2020 ◽  
Author(s):  
Nolan R. McGrady ◽  
Dorota L. Stankowska ◽  
Hayden B. Jefferies ◽  
Raghu R. Krishnamoorthy
Keyword(s):  
Intraocular Pressure ◽  
Oral Administration ◽  
Receptor Antagonist ◽  
Ocular Hypertension ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Brown Norway ◽  
Retinal Ganglion ◽  
Elevated Intraocular Pressure ◽  
Iop Elevation

AbstractPurposeGlaucoma is a neurodegenerative disease associated with elevated intraocular pressure and characterized by optic nerve axonal degeneration, cupping of the optic disc and loss of retinal ganglion cells (RGCs). The endothelin (ET) system of vasoactive peptides (ET-1, ET-2, ET-3) and their G-protein coupled receptors (ETA and ETB receptors) have been shown to be contributors to the pathophysiology of glaucoma. The purpose of this study was to determine if administration of the endothelin receptor antagonist, macitentan, after the onset of IOP elevation, was neuroprotective to retinal ganglion cells in ocular hypertensive rats.MethodsBrown Norway rats were subjected to the Morrison model of ocular hypertension by injection of hypertonic saline through episcleral veins. Macitentan (5 and 10 mg/kg body wt/day) was administered orally following the elevation of IOP and rats with IOP elevation were maintained for 4 weeks. RGC function was determined by pattern electroretinography at 2 and 4 weeks post IOP elevation. Rats were euthanized by approved humane methods and retinal flat-mounts generated were immunostained with RGC-selective markers RBPMS and Brn3a. RGC counts were conducted in a masked manner.ResultsA significant protection of retinal ganglion cells against cell loss was found following oral administration of macitentan (5 and 10 mg/kg body wt/day) in rats with elevated intraocular pressure. In addition, treatment with macitentan was able to preserve RGC function as measured by pattern ERG analysis.ConclusionsMacitentan was able to promote neuroprotection independent of IOP-lowering suggesting that this could complement existing treatments to prevent neurodegeneration during ocular hypertension. The findings presented have implications for the use of macitentan as an oral formulation to promote neuroprotection in glaucoma patients.

Involvement of Upregulated P53-Induced Death Domain Protein in Retinal Ganglion Cells Apoptosis After Optic Nerve Crush

2019 ◽  
Vol 20 (1) ◽  
pp. 51-59
Author(s):  
Mingyuan Zhang ◽  
Lifei Chen ◽  
Fan Xu ◽  
Li Jiang ◽  
Wenya Yan ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Control Group ◽  
Optic Nerve Crush ◽  
Retinal Ganglion ◽  
Death Domain ◽  
Nerve Crush ◽  
Caspase 2 ◽  
Sirna Group

Purpose: Retinal ganglion cells (RGCs) apoptosis is a common characteristic of optic neuropathies. p53-induced protein with a death domain (PIDD) is a well-known regulator of genotoxic stress-induced apoptosis, which is constitutively cleaved into three main fragments: PIDD-N, PIDD-C and PIDD-CC. Thus, we aim to determine the physiological relevance of PIDD in RGCs apoptosis in an optic nerve crush (ONC) model. Methods: All animals were evenly randomized into four groups: sham-control group, con-siRNA group, ONC group, and PIDD-siRNA group (ONC +PIDD-siRNA). Expressions of PIDD, caspase-2, Brn3a and tBid in ONC model were analyzed by Western blot and immunofluorescence. Mean densities of RGCs/mm2 were calculated with Fluoro-Gold (FG). Moreover, we tested the effect of PIDD-siRNA on ONC-induced RGCs apoptosis using TUNEL staining. Results: The level of full-length PIDD was weakly present and showed no significant differences at any time points. PIDD-CC and PIDD-C were significantly up-regulated in the retina at 3 days after ONC. Meanwhile, the expression of PIDD was significantly increased in Brn3a (a marker of RGCs) positive cells, indicating that the localization of PIDD appeared to be confined to RGCs. Furthermore, inhibition of PIDD prevented RGCs apoptosis by inhibiting caspase-2 and tBid activation. Conclusions: Taken together, PIDD may play a crucial role in RGCs apoptosis after ONC, and this process may be relevant to caspase-2 and tBid.

Melatonin As a Modulator of Degenerative and Regenerative Signaling Pathways in Injured Retinal Ganglion Cells

2019 ◽  
Vol 25 (28) ◽  
pp. 3057-3073 ◽  
Author(s):  
Kobra B. Juybari ◽  
Azam Hosseinzadeh ◽  
Habib Ghaznavi ◽  
Mahboobeh Kamali ◽  
Ahad Sedaghat ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Mitochondrial Dysfunction ◽  
Signaling Pathways ◽  
Retinal Ganglion Cells ◽  
Molecular Mechanisms ◽  
Nitrosative Stress ◽  
Ganglion Cells ◽  
Axon Growth ◽  
Nerve Fibers ◽  
Retinal Ganglion

Optic neuropathies refer to the dysfunction or degeneration of optic nerve fibers caused by any reasons including ischemia, inflammation, trauma, tumor, mitochondrial dysfunction, toxins, nutritional deficiency, inheritance, etc. Post-mitotic CNS neurons, including retinal ganglion cells (RGCs) intrinsically have a limited capacity for axon growth after either trauma or disease, leading to irreversible vision loss. In recent years, an increasing number of laboratory evidence has evaluated optic nerve injuries, focusing on molecular signaling pathways involved in RGC death. Trophic factor deprivation (TFD), inflammation, oxidative stress, mitochondrial dysfunction, glutamate-induced excitotoxicity, ischemia, hypoxia, etc. have been recognized as important molecular mechanisms leading to RGC apoptosis. Understanding these obstacles provides a better view to find out new strategies against retinal cell damage. Melatonin, as a wide-spectrum antioxidant and powerful freeradical scavenger, has the ability to protect RGCs or other cells against a variety of deleterious conditions such as oxidative/nitrosative stress, hypoxia/ischemia, inflammatory processes, and apoptosis. In this review, we primarily highlight the molecular regenerative and degenerative mechanisms involved in RGC survival/death and then summarize the possible protective effects of melatonin in the process of RGC death in some ocular diseases including optic neuropathies. Based on the information provided in this review, melatonin may act as a promising agent to reduce RGC death in various retinal pathologic conditions.

scholarly journals Dynamic Expression of HDAC3 in db/db Mouse RGCs and Its Relationship with Apoptosis and Autophagy

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yuhong Fu ◽  
Ying Wang ◽  
Xinyuan Gao ◽  
Huiyao Li ◽  
Yue Yuan
Keyword(s):  
Diabetic Retinopathy ◽  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Retinal Ganglion Cell ◽  
Ganglion Cells ◽  
Control Group ◽  
Diabetic Patients ◽  
Retinal Ganglion ◽  
Glucose Levels ◽  
Dynamic Expression

Background. Diabetic retinopathy (DR) is a severe complication of diabetes mellitus. DR is considered as a neurovascular disease. Retinal ganglion cell (RGC) loss plays an important role in the vision function disorder of diabetic patients. Histone deacetylase3 (HDAC3) is closely related to injury repair and nerve regeneration. The correlation between HDAC3 and retinal ganglion cells in diabetic retinopathy is still unclear yet. Methods. To investigate the chronological sequence of the abnormalities of retinal ganglion cells in diabetic retinopathy, we choose 15 male db/db mice (aged 8 weeks, 12 weeks, 16 weeks, 18 weeks, and 25 weeks; each group had 3 mice) as diabetic groups and 3 male db/m mice (aged 8 weeks) as the control group. In this study, we examined the morphological and immunohistochemical changes of HDAC3, Caspase3, and LC3B in a sequential manner by characterizing the process of retinal ganglion cell variation. Results. Blood glucose levels and body weights of db/db mice were significantly higher than that of the control group, P<0.01. Compared with the control group, the number of retinal ganglion cells decreased with the duration of disease increasing. HDAC3 expression gradually increased in RGCs of db/db mice. Caspase3 expression gradually accelerated in RGCs of db/db mice. LC3B expression dynamically changed in RGCs of db/db mice. HDAC3 was positively correlated with Caspase3 expression (r=0.7424), P<0.01. HDAC3 was positively correlated with LC3B expression (r=0.7336), P<0.01. Discussion. We clarified the dynamic expression changes of HDAC3, Caspase3, and LC3B in retinal ganglion cells of db/db mice. Our results suggest the HDAC3 expression has a positive correlation with apoptosis and autophagy.

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