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Journal of Neuroinflammation Jun 2024Radiation retinopathy (RR) is a major side effect of ocular tumor treatment by plaque brachytherapy or proton beam therapy. RR manifests as delayed and progressive...
Radiation retinopathy (RR) is a major side effect of ocular tumor treatment by plaque brachytherapy or proton beam therapy. RR manifests as delayed and progressive microvasculopathy, ischemia and macular edema, ultimately leading to vision loss, neovascular glaucoma, and, in extreme cases, secondary enucleation. Intravitreal anti-VEGF agents, steroids and laser photocoagulation have limited effects on RR. The role of retinal inflammation and its contribution to the microvascular damage occurring in RR remain incompletely understood. To explore cellular and vascular events after irradiation, we analyzed their time course at 1 week, 1 month and 6 months after rat eyes received 45 Gy X-beam photons. Müller glial cells, astrocytes and microglia were rapidly activated, and these markers of retinal inflammation persisted for 6 months after irradiation. This was accompanied by early cell death in the outer retina, which persisted at later time points, leading to retinal thinning. A delayed loss of small retinal capillaries and retinal hypoxia were observed after 6 months, indicating inner blood‒retinal barrier (BRB) alteration but without cell death in the inner retina. Moreover, activated microglial cells invaded the entire retina and surrounded retinal vessels, suggesting the role of inflammation in vascular alteration and in retinal cell death. Radiation also triggered early and persistent invasion of the retinal pigment epithelium by microglia and macrophages, contributing to outer BRB disruption. This study highlights the role of progressive and long-lasting inflammatory mechanisms in RR development and demonstrates the relevance of this rat model to investigate human pathology.
Topics: Animals; Rats; Retina; Disease Models, Animal; Retinal Diseases; Inflammation; Radiation Injuries, Experimental; Radiation Injuries; Male; Microglia
PubMed: 38915029
DOI: 10.1186/s12974-024-03151-2 -
Scientific Reports Jun 2024To improve the understanding of potential pathological mechanisms of macular edema (ME), we try to discover biomarker candidates related to ME caused by diabetic...
To improve the understanding of potential pathological mechanisms of macular edema (ME), we try to discover biomarker candidates related to ME caused by diabetic retinopathy (DR) and retinal vein occlusion (RVO) in spectral-domain optical coherence tomography images by means of deep learning (DL). 32 eyes of 26 subjects with non-proliferative DR (NPDR), 77 eyes of 61 subjects with proliferative DR (PDR), 120 eyes of 116 subjects with branch RVO (BRVO), and 17 eyes of 15 subjects with central RVO (CRVO) were collected. A DL model was implemented to guide biomarker candidate discovery. The disorganization of the retinal outer layers (DROL), i.e., the gray value of the retinal tissues between the external limiting membrane (ELM) and retinal pigment epithelium (RPE), the disrupted and obscured rate of the ELM, ellipsoid zone (EZ), and RPE, was measured. In addition, the occurrence, number, volume, and projected area of hyperreflective foci (HRF) were recorded. ELM, EZ, and RPE are more likely to be obscured in RVO group and HRFs are observed more frequently in DR group (all P ≤ 0.001). In conclusion, the features of DROL and HRF can be possible biomarkers related to ME caused by DR and RVO in OCT modality.
Topics: Humans; Macular Edema; Tomography, Optical Coherence; Retinal Vein Occlusion; Diabetic Retinopathy; Female; Male; Biomarkers; Middle Aged; Aged; Retinal Pigment Epithelium; Deep Learning
PubMed: 38906954
DOI: 10.1038/s41598-024-63144-2 -
Scientific Reports Jun 2024Diabetic retinopathy (DR) is a multifactorial disease displaying vascular-associated pathologies, including vascular leakage and neovascularization, ultimately leading...
Diabetic retinopathy (DR) is a multifactorial disease displaying vascular-associated pathologies, including vascular leakage and neovascularization, ultimately leading to visual impairment. However, animal models accurately reflecting these pathologies are lacking. Vascular endothelial growth factor A (VEGF-A) is an important factor in the development of micro- and macro-vascular pathology in DR. In this study, we evaluated the feasibility of using a cumate-inducible lentivirus (LV) mediated expression of vegf-a to understand DR pathology in vitro and in vivo. Retinal pigment epithelial cells (ARPE-19) were transduced with cumate-inducible LV expressing vegf-a, with subsequent analysis of vegf-a expression and its impact on cell proliferation, viability, motility, and permeability. Cumate tolerability in adult Wistar rat eyes was assessed as an initial step towards a potential DR animal model development, by administering cumate via intravitreal injections (IVT) and evaluating consequent effects by spectral domain optical coherence tomography (SD-OCT), flash electroretinography (fERG), ophthalmic examination (OE), and immunohistochemistry. Transduction of ARPE-19 cells with cumate-inducible LV resulted in ~ 2.5-fold increase in vegf-a mRNA and ~ threefold increase in VEGF-A protein secretion. Transduced cells displayed enhanced cell proliferation, viability, permeability, and migration in tube-like structures. However, IVT cumate injections led to apparent retinal toxicity, manifesting as retinal layer abnormalities, haemorrhage, vitreous opacities, and significant reductions in a- and b-wave amplitudes, along with increased microglial activation and reactive gliosis. In summary, while cumate-inducible LV-mediated vegf-a expression is valuable for in vitro mechanistic studies in cellular drug discovery, its use is not a feasible approach to model DR in in vivo studies due to cumate-induced retinal toxicity.
Topics: Animals; Vascular Endothelial Growth Factor A; Diabetic Retinopathy; Lentivirus; Rats; Retinal Pigment Epithelium; Humans; Rats, Wistar; Cell Proliferation; Disease Models, Animal; Cell Line; Intravitreal Injections; Male; Cell Movement; Cell Survival; Tomography, Optical Coherence; Genetic Vectors
PubMed: 38906906
DOI: 10.1038/s41598-024-63590-y -
Investigative Ophthalmology & Visual... Jun 2024Recent studies have shown that the retinal pigment epithelium (RPE) relies on fatty acid oxidation (FAO) for energy, however, its role in overall retinal health is...
PURPOSE
Recent studies have shown that the retinal pigment epithelium (RPE) relies on fatty acid oxidation (FAO) for energy, however, its role in overall retinal health is unknown. The only FAO disorder that presents with chorioretinopathy is long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD). Studying the molecular mechanisms can lead to new treatments for patients and elucidate the role of FAO in the RPE. This paper characterizes the chorioretinopathy progression in a recently reported LCHADD mouse model.
METHODS
Visual assessments, such as optokinetic tracking and fundus imaging, were performed in wildtype (WT) and LCHADD mice at 3, 6, 10, and 12 months of age. Retinal morphology was analyzed in 12-month retinal cross-sections using hematoxylin and eosin (H&E), RPE65, CD68, and TUNEL staining, whereas RPE structure was assessed using transmission electron microscopy (TEM). Acylcarnitine profiles were measured in isolated RPE/sclera samples to determine if FAO was blocked. Bulk RNA-sequencing of 12 month old male WT mice and LCHADD RPE/sclera samples assessed gene expression changes.
RESULTS
LCHADD RPE/sclera samples had a 5- to 7-fold increase in long-chain hydroxyacylcarnitines compared to WT, suggesting an impaired LCHAD step in long-chain FAO. LCHADD mice have progressively decreased visual performance and increased RPE degeneration starting at 6 months. LCHADD RPE have an altered structure and a two-fold increase in macrophages in the subretinal space. Finally, LCHADD RPE/sclera have differentially expressed genes compared to WT, including downregulation of genes important for RPE function and angiogenesis.
CONCLUSIONS
Overall, this LCHADD mouse model recapitulates early-stage chorioretinopathy seen in patients with LCHADD and is a useful model for studying LCHADD chorioretinopathy.
Topics: Animals; Disease Models, Animal; Mice; Retinal Pigment Epithelium; Mice, Inbred C57BL; Long-Chain-3-Hydroxyacyl-CoA Dehydrogenase; Choroid Diseases; Male; Retinal Diseases; Microscopy, Electron, Transmission
PubMed: 38904639
DOI: 10.1167/iovs.65.6.33 -
Bioscience Reports Jun 2024
Expression of Concern: Madecassoside protects retinal pigment epithelial cells against hydrogen peroxide induced oxidative stress and apoptosis through the activation of Nrf2/HO-1 pathway.
Topics: NF-E2-Related Factor 2; Oxidative Stress; Hydrogen Peroxide; Apoptosis; Humans; Heme Oxygenase-1; Retinal Pigment Epithelium; Signal Transduction; Triterpenes; Epithelial Cells; Cell Line; Membrane Proteins; Animals
PubMed: 38904175
DOI: 10.1042/BSR-2019-4347_EOC -
Cureus May 2024Congenital simple hamartoma of the retinal pigment epithelium (CSHRPE) is a rare benign tumor often detected incidentally during routine eye exams. We present a case of...
Congenital simple hamartoma of the retinal pigment epithelium (CSHRPE) is a rare benign tumor often detected incidentally during routine eye exams. We present a case of multifocal CSHRPE in a 32-year-old Hispanic woman, emphasizing the diagnostic challenges posed by its presentation and the pivotal role of multimodal imaging in accurate diagnosis. Despite initial difficulties due to a history of trauma and pigmented fundus, advanced imaging techniques, including optical coherence tomography (OCT), OCT angiography (OCTA), fluorescein angiography (FA), and indocyanine green angiography (ICGA), facilitated a precise diagnosis. Notably, OCTA revealed high signal intensity and flow at the largest nodule site while FA and ICGA exhibited characteristic blockage patterns. Moreover, smaller nodules exhibited OCT findings supporting the theory of islands of retinal pigment epithelium (RPE) cells proliferating ectopically within the retina. Our case underscores the importance of comprehensive imaging assessment in distinguishing CSHRPE from other lesions, contributing to a deeper understanding of this rare ocular condition.
PubMed: 38903341
DOI: 10.7759/cureus.60755 -
Canadian Journal of Ophthalmology.... Jun 2024To compare the visibility and accessibility of the outer retina in neovascular age-related macular degeneration (nAMD) between 2 OCT devices.
OBJECTIVE
To compare the visibility and accessibility of the outer retina in neovascular age-related macular degeneration (nAMD) between 2 OCT devices.
METHODS
In this prospective, cross-sectional exploratory study, differences in thickness and loss of individual outer retinal layers in eyes with nAMD and in age-matched healthy eyes between a next-level High-Res OCT device and the conventional SPECTRALIS OCT (both Heidelberg Engineering GmbH, Heidelberg, Germany) were analyzed. Eyes with nAMD and at least 250 nL of retinal fluid, quantified by an approved deep-learning algorithm (Fluid Monitor, RetInSight, Vienna, Austria), fulfilled the inclusion criteria. The outer retinal layers were segmented using automated layer segmentation and were corrected manually. Layer loss and thickness were compared between both devices using a linear mixed-effects model and a paired t test.
RESULTS
Nineteen eyes of 17 patients with active nAMD and 17 healthy eyes were included. For nAMD eyes, the thickness of the retinal pigment epithelium (RPE) differed significantly between the devices (25.42 μm [95% CI, 14.24-36.61] and 27.31 μm [95% CI, 16.12-38.50] for high-resolution OCT and conventional OCT, respectively; p = 0.033). Furthermore, a significant difference was found in the mean relative external limiting membrane loss (p = 0.021). However, the thickness of photoreceptors, RPE integrity loss, and photoreceptor integrity loss did not differ significantly between devices in the central 3 mm. In healthy eyes, a significant difference in both RPE and photoreceptor thickness between devices was shown (p < 0.001).
CONCLUSION
Central RPE thickness was significantly thinner on high-resolution OCT compared with conventional OCT images explained by superior optical separation of the RPE and Bruch's membrane.
PubMed: 38901467
DOI: 10.1016/j.jcjo.2024.05.014 -
Nature Communications Jun 2024Phototransduction involves changes in concentration of ions and other solutes within photoreceptors and in subretinal space, which affect osmotic pressure and the...
Phototransduction involves changes in concentration of ions and other solutes within photoreceptors and in subretinal space, which affect osmotic pressure and the associated water flow. Corresponding expansion and contraction of cellular layers can be imaged using optoretinography (ORG), based on phase-resolved optical coherence tomography (OCT). Until now, ORG could reliably detect only photoisomerization and phototransduction in photoreceptors, primarily in cones under bright stimuli. Here, by employing a phase-restoring subpixel motion correction algorithm, which enables imaging of the nanometer-scale tissue dynamics during minute-long recordings, and unsupervised learning of spatiotemporal patterns, we discover optical signatures of the other retinal structures' response to visual stimuli. These include inner and outer segments of rod photoreceptors, retinal pigment epithelium, and subretinal space in general. The high sensitivity of our technique enables detection of the retinal responses to dim stimuli: down to 0.01% bleach level, corresponding to natural levels of scotopic illumination. We also demonstrate that with a single flash, the optoretinogram can map retinal responses across a 12° field of view, potentially replacing multifocal electroretinography. This technique expands the diagnostic capabilities and practical applicability of optoretinography, providing an alternative to electroretinography, while combining structural and functional retinal imaging in the same OCT machine.
Topics: Tomography, Optical Coherence; Animals; Retinal Pigment Epithelium; Retinal Rod Photoreceptor Cells; Retina; Light; Photic Stimulation; Algorithms; Male
PubMed: 38898002
DOI: 10.1038/s41467-024-49014-5 -
International Journal of Ophthalmology 2024To evaluate the effect of auraptene (AUR) treatment in forms of free and encapsulated in niosome nanoparticles by investigating the mRNA expression level of vascular...
AIM
To evaluate the effect of auraptene (AUR) treatment in forms of free and encapsulated in niosome nanoparticles by investigating the mRNA expression level of vascular endothelium growth factor (VEGF)-A and platelet-derived growth factors (PDGFs) in human retinal pigment epithelium (RPE) cell line.
METHODS
Niosome nanocarriers were produced using two surfactants Span 60 and Tween 80. RPE cell line was treated with both free AUR and niosome-encapsulated. Optimum dosage of treatments was calculated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Expression of and , , , genes was measured after total RNA extraction and cDNA synthesis, using real-time polymerase chain reaction (RT-PCR).
RESULTS
The highest entrapment efficiency (EE) was achieved by Span 60:cholesterol (1:1) with 64.3%. The half maximal inhibitory concentration (IC) of free and niosome-encapsulated AUR were 38.5 and 27.78 µg/mL, respectively. Release study revealed that niosomal AUR had more gradual delivery to the cells. RT-PCR results showed reduced expression levels of , , , , and after treatment with both free and niosomal AUR.
CONCLUSION
Niosomal formulation of Span 60: cholesterol (1:1) is an effective drug delivery approach to transfer AUR to RPE cells. VEGF-A, PDGF-A, PDGF-B, PDGF-C, and PDGF-D are four angiogenic factors, inhibiting which by niosomal AUR may be effective in age-related macular degeneration.
PubMed: 38895680
DOI: 10.18240/ijo.2024.06.06 -
International Journal of Ophthalmology 2024To explore the effect of epidermal growth factor receptor (EGFR) inhibition by erlotinib and EGFR siRNA on epidermal growth factor (EGF)-induced activation of retinal...
AIM
To explore the effect of epidermal growth factor receptor (EGFR) inhibition by erlotinib and EGFR siRNA on epidermal growth factor (EGF)-induced activation of retinal pigment epithelium (RPE) cells.
METHODS
Human RPE cell line (ARPE-19 cells) was activated by 100 ng/mL EGF. Erlotinib and EGFR siRNA were used to intervene EGF treatment. Cellular viability, proliferation, and migration were detected by methyl thiazolyl tetrazolium (MTT) assay, bromodeoxyuridine (BrdU) staining assay and wound healing assay, respectively. EGFR/protein kinase B (AKT) pathway proteins and N-cadherin, α-smooth muscle actin (α-SMA), and vimentin were tested by Western blot assay. EGFR was also determined by immunofluorescence staining.
RESULTS
EGF treatment for 24h induced a significant increase of ARPE-19 cells' viability, proliferation and migration, phosphorylation of EGFR/AKT proteins, and decreased total EGFR expression. Erlotinib suppressed ARPE-19 cells' viability, proliferation and migration through down regulating total EGFR and AKT protein expressions. Erlotinib also inhibited EGF-induced an increase of proliferative and migrative ability in ARPE-19 cells and clearly suppressed EGF-induced EGFR/AKT proteins phosphorylation and decreased expression of N-cadherin, α-SMA, and vimentin proteins. Similarly, EGFR inhibition by EGFR siRNA significantly affected EGF-induced an increase of cell proliferation, viability, and migration, phosphorylation of EGFR/AKT proteins, and up-regulation of N-cadherin, α-SMA, and vimentin proteins.
CONCLUSION
Erlotinib and EGFR-knockdown suppress EGF-induced cell viability, proliferation, and migration EGFR/AKT pathway in RPE cells. EGFR inhibition may be a possible therapeutic approach for proliferative vitreoretinopathy (PVR).
PubMed: 38895677
DOI: 10.18240/ijo.2024.06.05