The effects of intravitreally injected bevacizumab on the retina and retina pigment epithelium: experimental in-vivo electron microscopic study in intact versus vitrectomized eyes

Open Medicine ◽  
2010 ◽  
Vol 5 (6) ◽  
pp. 745-751 ◽  
Author(s):  
Nilufer Kocak ◽  
Candan Ozogul ◽  
Suleyman Kaynak ◽  
Ulker Sonmez ◽  
Mehmet Zengin ◽  
...  
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Intravitreal Bevacizumab ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Control Group ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Electron Microscopes

AbstractTo analyze the retinal toxicity of bevacizumab at various doses both in vitrectomized and non-vitrectomized rabbit models. Twenty- eight rabbits were included in the study. Twenty- four rabbits were assigned to six groups, with 4 of the rabbits in the control group. The animals in Groups 1, 2 and 3 received bevacizumab at a dose of 0.3 mg, 0.5 mg and 1.5 mg /eye, respectively. The rabbits in Groups 4, 5 and 6 received intravitreal bevacizumab of 0.3 mg, 0.5 mg and 1.5mg/eye, respectively, after gas compression vitrectomy. Two weeks after the procedure, the rabbits were euthanized. Retina tissue samples were then obtained and examined with both light and electron microscopes. In Groups 1, 2 and 3 after bevacizumab injection, toxic degeneration in the photoreceptor and retinal pigment epithelium cells was observed via electron microscopic examination. The findings in Groups 4 and 5 were normal as compared to the control group. In Group 6, toxicity in the bipolar neurons and photoreceptor cells was noticed. Increased toxicity and retinal penetration were noticed in all administered doses of bevacizumab in the presence of vitreous. In addition, ocular toxicity occurred through the injection of the highest dose of bevacizumab after vitrectomy. It is possible that the bevacizumab dose and the, vitreous are as important as the drug half-life in the vitreous.

scholarly journals UNC569-induced Morphological Changes in Pigment Epithelia and Photoreceptor Cells in the Retina through MerTK Inhibition in Mice

2018 ◽  
Vol 46 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Ayako Sayama ◽  
Keiko Okado ◽  
Koichi Nakamura ◽  
Tatsuya Kawaguchi ◽  
Takuma Iguchi ◽  
...  
Keyword(s):  
Tissue Sample ◽  
Morphological Changes ◽  
Pigment Epithelium ◽  
Outer Nuclear Layer ◽  
Retinal Pigment ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Electron Microscopic ◽  
Drug Induced ◽  
Photoreceptor Outer Segments

Mer proto-oncogene tyrosine kinase (MerTK), which is expressed in the retinal pigment epithelium (RPE), regulates phagocytosis of shed photoreceptor outer segments (POS). To investigate the effects of drug-induced MerTK inhibition on the retina, UNC569, a specific MerTK inhibitor, was orally administered to male mice at a concentration of 60, 100, or 150 mg/kg for up to 14 days. Furthermore, MerTK inhibition in the retinal tissue sample was examined using a phosphorylation assay following a single dose of UNC569 at 100 mg/kg. In electron microscopic examination, UNC569 at 100 mg/kg or more increased phagosomes and phagolysosomes in the RPE. In addition, UNC569 at 150 mg/kg increased chromatin-condensed nuclei in the outer nuclear layer, indicating the early phase of apoptosis of photoreceptor cells. MiR-183, miR-96, and miR-124, which are enriched in photoreceptor cells, were elevated in the plasma of mice following treatment of 150-mg/kg UNC569, in conjunction with the photoreceptor lesion. Additionally, 100-mg/kg UNC569 inhibited MerTK phosphorylation in the retina. These results suggest that MerTK inhibition impaired phagocytic function of the retina, leading to accumulation of shed POS within the POS layer and increasing phagosomes and phagolysosomes in the RPE to delay POS renewal, resulting in apoptosis of photoreceptor cells.

scholarly journals The Impact of the Timing of Dosing on the Severity of UNC569-Induced Ultrastructural Changes in the Mouse Retina

2020 ◽  
Vol 48 (5) ◽  
pp. 669-676
Author(s):  
Ayako Sayama ◽  
Keiko Okado ◽  
Mayu Yamaguchi ◽  
Naozumi Samata ◽  
Masako Imaoka ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Ultrastructural Changes ◽  
Mouse Retina ◽  
Visual Cycle ◽  
Electron Microscopic ◽  
The Impact

Mer proto-oncogene tyrosine kinase (MerTK), expressed in the retinal pigment epithelium (RPE), regulates the phagocytosis of shed photoreceptor outer segments. To investigate the influence of dosing time on MerTK inhibitor UNC569-induced retinal toxicity, UNC569 at 100 mg/kg was orally administered to male mice at 2 different Zeitgeber times (ZT5.5 or ZT22) for 28 days. Electron microscopy was conducted at ZT2 after the final dosing. Additionally, the visual cycle components (11-cis-retinal, all-trans-retinal, all-trans-retinol, and 11-cis-retinol), which play an important role in maintaining retinal homeostasis, were quantified by liquid chromatography/mass spectrometry/mass spectrometry. Under electron microscopic examination, the number of phagosomes and phagolysosomes in the RPE increased in both the ZT5.5 and ZT22 administered groups, while endoplasmic reticulum dilatation in the RPE and chromatin aggregation of photoreceptor nuclei were observed only in the ZT22 administered group. No change was observed in any of the visual cycle components. These results suggest that the timing of the dosing in relation to the physiological MerTK phosphorylation affected the severity of changes in the RPE, leading to the apoptosis of the photoreceptor cells.

JAM-C maintains VEGR2 expression to promote retinal pigment epithelium cell survival under oxidative stress

2017 ◽  
Vol 117 (04) ◽  
pp. 750-757
Author(s):  
Xin Jia ◽  
Chen Zhao ◽  
Qishan Chen ◽  
Yuxiang Du ◽  
Lijuan Huang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment Epithelium ◽  
Cell Survival ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelium Cell ◽  
Photoreceptor Cells ◽  
Rpe Cells

SummaryJunctional adhesion molecule-C (JAM-C) has been shown to play critical roles during development and in immune responses. However, its role in adult eyes under oxidative stress remains poorly understood. Here, we report that JAM-C is abundantly expressed in adult mouse retinae and choroids in vivo and in cultured retinal pigment epithelium (RPE) and photoreceptor cells in vitro. Importantly, both JAM-C expression and its membrane localisation are downregulated by H2O2-induced oxidative stress. Under H2O2-induced oxidative stress, JAM-C is critically required for the survival of human RPE cells. Indeed, loss of JAM-C by siRNA knockdown decreased RPE cell survival. Mechanistically, we show that JAM-C is required to maintain VEGFR2 expression in RPE cells, and VEGFR2 plays an important role in keeping the RPE cells viable since overexpression of VEGFR2 partially restored impaired RPE survival caused by JAM-C knockdown and increased RPE survival. We further show that JAM-C regulates VEGFR2 expression and, in turn, modulates p38 phosphorylation. Together, our data demonstrate that JAM-C plays an important role in maintaining VEGR2 expression to promote RPE cell survival under oxidative stress. Given the vital importance of RPE in the eye, approaches that can modulate JAM-C expression may have therapeutic values in treating diseases with impaired RPE survival.

scholarly journals Noninvasive two-photon imaging reveals retinyl ester storage structures in the eye

2004 ◽  
Vol 164 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Yoshikazu Imanishi ◽  
Matthew L. Batten ◽  
David W. Piston ◽  
Wolfgang Baehr ◽  
Krzysztof Palczewski
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Retinyl Ester ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
In Vivo Experiments ◽  
Essential Components ◽  
Intracellular Compartments

Visual sensation in vertebrates is triggered when light strikes retinal photoreceptor cells causing photoisomerization of the rhodopsin chromophore 11-cis-retinal to all-trans-retinal. The regeneration of preillumination conditions of the photoreceptor cells requires formation of 11-cis-retinal in the adjacent retinal pigment epithelium (RPE). Using the intrinsic fluorescence of all-trans-retinyl esters, noninvasive two-photon microscopy revealed previously uncharacterized structures (6.9 ± 1.1 μm in length and 0.8 ± 0.2 μm in diameter) distinct from other cellular organelles, termed the retinyl ester storage particles (RESTs), or retinosomes. These structures form autonomous all-trans-retinyl ester-rich intracellular compartments distinct from other organelles and colocalize with adipose differentiation-related protein. As demonstrated by in vivo experiments using wild-type mice, the RESTs participate in 11-cis-retinal formation. RESTs accumulate in Rpe65−/− mice incapable of carrying out the enzymatic isomerization, and correspondingly, are absent in the eyes of Lrat−/− mice deficient in retinyl ester synthesis. These results indicate that RESTs located close to the RPE plasma membrane are essential components in 11-cis-retinal production.

scholarly journals CRISPR-engineered mosaicism rapidly reveals that loss of Kcnj13 function in mice mimics human disease phenotypes

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Hua Zhong ◽  
Yiyun Chen ◽  
Yumei Li ◽  
Rui Chen ◽  
Graeme Mardon
Keyword(s):  
Gene Function ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Mutant Mice ◽  
Wild Type ◽  
Cell Degeneration ◽  
Rpe Cells ◽  
Mosaic Expression

Abstract The era of genomics has demanded the development of more efficient and timesaving approaches to validate gene function in disease. Here, we utilized the CRISPR-Cas9 system to generate Kcnj13 mutant mice by zygote injection to verify the pathogenic role of human KCNJ13, mutations of which are thought to cause Leber congenital amaurosis (LCA), an early-onset form of blindness. We found that complete loss of Kcnj13 is likely postnatal lethal. Among surviving F0-generation mice examined, 80% show mosaic KCNJ13 expression in the retinal pigment epithelium (RPE). Mosaic expression correlates with decreased response to light and photoreceptor degeneration, indicating that Kcnj13 mutant mice mimic human KCNJ13-related LCA disease. Importantly, mosaic animals enable us to directly compare Kcnj13 mutant and wild-type RPE cells in the same eye. We found that RPE cells lacking KCNJ13 protein still survive but overlying photoreceptors exhibit cell degeneration. At the same time, wild-type RPE cells can rescue neighboring photoreceptor cells that overlie mutant RPE cells. These results suggest that KCNJ13 expression is required for RPE cells to maintain photoreceptor survival. Moreover, we show that CRISPR-Cas9 engineered mosaicism can be used to rapidly test candidate gene function in vivo.

scholarly journals Effect of methanol on the ultrastructure of chorioretinal complex of rats’ eyes in the early stages of the experiment

2014 ◽  
Vol 18 (1 (69)) ◽  
Author(s):  
N. І. Molchanyuk
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Electron Microscopic ◽  
White Rats ◽  
Intraperitoneal Dose ◽  
A Cell ◽  
Number Of Cells ◽  
Observation Period

Electron-microscopic structure of the chorioretinal complex were investigated (СRC), [choriocapillaries (HC) – retinal pigment epithelium (RPE) – photoreceptor cells (FC)], of white rats in a period of 40 min. to 3 days after a single intraperitoneal dose of methanol 0.75 g/kg body weight. It has been established that RPE cells are the most responsiveto the dose of the methanol used. In the dynamics (from 40 min. up to 3 days), they grew destructive changes of mitochondria and elements of smooth endoplasmic reticulum, the smoothness of the basal folds and patchy destruction of the apical microvilli. The changes in CC and FC were similar. By the end of the observation period, these phenomena in the CRC structure spread to a larger number of cells. At the same time, during the whole period of the study, and, in particular, after a day, some signs of recovery of compensatory nature were obvious. Attention is drawn to pronounced reaction of mitochondria, which are energy forming structures of a cell.

scholarly journals Ocular Toxoplasmosis: Mechanisms of Retinal Infection and Experimental Models

Parasitologia ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 50-60
Author(s):  
Veronica Rodriguez Fernandez ◽  
Giovanni Casini ◽  
Fabrizio Bruschi
Keyword(s):  
Ex Vivo ◽  
Cell Damage ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Treatment Strategies ◽  
Experimental Models ◽  
Ocular Toxoplasmosis ◽  
Cell Infection

Ocular toxoplasmosis (OT) is caused by the parasite Toxoplasma gondii and affects many individuals throughout the world. Infection may occur through congenital or acquired routes. The parasites enter the blood circulation and reach both the retina and the retinal pigment epithelium, where they may cause cell damage and cell death. Different routes of access are used by T. gondii to reach the retina through the retinal endothelium: by transmission inside leukocytes, as free parasites through a paracellular route, or after endothelial cell infection. A main feature of OT is the induction of an important inflammatory state, and the course of infection has been shown to be influenced by the host immunogenetics. On the other hand, there is evidence that the T. gondii phenotype also has an impact on the distribution of the pathology in different areas. Although considerable knowledge has been acquired on OT, a deeper knowledge of its mechanisms is necessary to provide new, more targeted treatment strategies. In particular, in addition to in vitro and in vivo experimental models, organotypic, ex vivo retinal explants may be useful in this direction.

A Bibliometric Analysis of the Top 100 Cited Papers in Retinal Detachment

2021 ◽  
pp. 247412642110073
Author(s):  
Masumi George Asahi ◽  
Haig Pakhchanian ◽  
Christine Doepker ◽  
Rahul Raiker ◽  
Ron P. Gallemore
Keyword(s):  
Retinal Detachment ◽  
Bibliometric Analysis ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Microscopic Analysis ◽  
The United States ◽  
Electron Microscopic ◽  
Research Areas ◽  
Science Index ◽  
Funding Agencies

Purpose: This work aimed to identify and analyze the most frequently cited articles in retinal detachment (RD). Methods: Institute for Scientific Information’s Web of Science index (Thomas Scientific) was used to identify the top 100 most cited articles on RD between 1900 and 2019. Data from the top 100 most cited articles that met inclusion criteria were analyzed based on title, citation frequency, authorship, institution, journal, year of publication, and country of origin. Results: The top 100 articles in RD were cited 88 to 480 times. Steven K. Fisher was the most cited individual, with the University of California system being the most cited organization. Sixty-four percent of the top 100 articles originated from the United States and were published in the American Journal of Ophthalmology, Ophthalmology, and Archives of Ophthalmology at frequencies of 36%, 24%, and 11%, respectively. The top funding agencies included the US Department of Health and Human Services, the National Institutes of Health, and the National Eye Institute at 29%, 28%, and 27%, respectively. The top-cited article, which assessed the role of the retinal pigment epithelium by histologic and electron microscopic analysis of RDs in eyes of owl monkeys, was by Machemer and Laqua in the American Journal of Ophthalmology. Conclusions: This bibliometric analysis provides researchers and clinicians with a detailed overview of the most cited manuscripts in RD. Such analyses may guide researchers and funding agencies on important research areas in the field.

scholarly journals OCT imaging of rod mitochondrial respiration in vivo

2021 ◽  
pp. 153537022110137
Author(s):  
Bruce A Berkowitz ◽  
Haohua Qian
Keyword(s):  
Signaling Pathway ◽  
Mitochondrial Respiration ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
The Body ◽  
Subretinal Space ◽  
Outer Retina ◽  
Water Efflux ◽  
Resolution Imaging

There remains a need for high spatial resolution imaging indices of mitochondrial respiration in the outer retina that probe normal physiology and measure pathogenic and reversible conditions underlying loss of vision. Mitochondria are involved in a critical, but somewhat underappreciated, support system that maintains the health of the outer retina involving stimulus-evoked changes in subretinal space hydration. The subretinal space hydration light–dark response is important because it controls the distribution of vision-critical interphotoreceptor matrix components, including anti-oxidants, pro-survival factors, ions, and metabolites. The underlying signaling pathway controlling subretinal space water management has been worked out over the past 30 years and involves cGMP/mitochondria respiration/pH/RPE water efflux. This signaling pathway has also been shown to be modified by disease-generating conditions, such as hypoxia or oxidative stress. Here, we review recent advances in MRI and commercially available OCT technologies that can measure stimulus-evoked changes in subretinal space water content based on changes in the external limiting membrane-retinal pigment epithelium region. Each step within the above signaling pathway can also be interrogated with FDA-approved pharmaceuticals. A highlight of these studies is the demonstration of first-in-kind in vivo imaging of mitochondria respiration of any cell in the body. Future examinations of subretinal space hydration are expected to be useful for diagnosing threats to sight in aging and disease, and improving the success rate when translating treatments from bench-to-bedside.

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