scholarly journals Cell Stiffening Contributes to Complement-mediated Injury of Choroidal Endothelial Cells in Early AMD

2021 ◽  
Author(s):  
Andrea P Cabrera ◽  
Jonathan Stoddard ◽  
Irene Santiago Tierno ◽  
Nikolaos Matisioudis ◽  
Mahesh Agarwal ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Membrane Attack Complex ◽  
Small Gtpases ◽  
Age Related Macular Degeneration ◽  
Cell Stiffness ◽  
Age Related ◽  
Dry Amd ◽  
Choroidal Vessels

Age-related macular degeneration (AMD) is the leading cause of blindness in the aging population. Yet, no therapies exist for ~85% of all AMD patients who have the dry form that is marked by degeneration of the retinal pigment epithelium (RPE) and underlying choroidal vasculature. As the choroidal vessels are crucial for RPE development and maintenance, understanding how they degenerate may lead to effective therapies for dry AMD. One likely causative factor for choroidal vascular loss is the cytolytic membrane attack complex (MAC) of the complement pathway that is abundant on choroidal vessels of humans with early dry AMD. To examine this possibility, we studied the effect of complement activation on choroidal endothelial cells (ECs) isolated from a rhesus monkey model of early AMD that, we report, exhibits MAC deposition and choriocapillaris endothelial loss similar to that seen in human early AMD. Treatment of choroidal ECs from AMD eyes with complement-competent normal human serum caused extensive actin cytoskeletal injury that was significantly less pronounced in choroidal ECs from young normal monkey eyes. We further show that ECs from AMD eyes are significantly stiffer than their younger counterparts and exhibit peripheral actin organization that is distinct from the longitudinal stress fibers in young ECs. Finally, these differences in complement susceptibility and mechanostructural properties were found to be regulated by the differential activity of small GTPases Rac and Rho because Rac inhibition in AMD cells led to simultaneous reduction in stiffness and complement susceptibility while Rho inhibition in young cells exacerbated complement injury. Thus, by identifying cell stiffness and cytoskeletal regulators Rac and Rho as important determinants of complement susceptibility, the current findings offer a new mechanistic insight into choroidal vascular loss in early AMD that warrants further investigation for assessment of translational potential.

scholarly journals Single-cell transcriptomics of the human retinal pigment epithelium and choroid in health and macular degeneration

2019 ◽  
Vol 116 (48) ◽  
pp. 24100-24107 ◽  
Author(s):  
Andrew P. Voigt ◽  
Kelly Mulfaul ◽  
Nathaniel K. Mullin ◽  
Miles J. Flamme-Wiese ◽  
Joseph C. Giacalone ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Retinal Pigment Epithelium ◽  
Macular Degeneration ◽  
Single Cell ◽  
Rna Sequencing ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Single Cell Rna Sequencing

The human retinal pigment epithelium (RPE) and choroid are complex tissues that provide crucial support to the retina. Disease affecting either of these supportive tissues can lead to irreversible blindness in the setting of age-related macular degeneration. In this study, single-cell RNA sequencing was performed on macular and peripheral regions of RPE-choroid from 7 human donor eyes in 2 independent experiments. In the first experiment, total RPE/choroid preparations were evaluated and expression profiles specific to RPE and major choroidal cell populations were identified. As choroidal endothelial cells represent a minority of the total RPE/choroidal cell population but are strongly implicated in age-related macular degeneration (AMD) pathogenesis, a second single-cell RNA-sequencing experiment was performed using endothelial cells enriched by magnetic separation. In this second study, we identified gene expression signatures along the choroidal vascular tree, classifying the transcriptome of human choriocapillaris, arterial, and venous endothelial cells. We found that the choriocapillaris highly and specifically expresses the regulator of cell cycle gene (RGCC), a gene that responds to complement activation and induces apoptosis in endothelial cells. In addition, RGCC was the most up-regulated choriocapillaris gene in a donor diagnosed with AMD. These results provide a characterization of the human RPE and choriocapillaris transcriptome, offering potential insight into the mechanisms of choriocapillaris response to complement injury and choroidal vascular disease in age-related macular degeneration.

Hypocrellin B Encapsulated in Triphenyl Phosphonium-Modified Cationic Liposomes for Photodynamic Treatment of Exudative Age-Related Macular Degeneration

2019 ◽  
Vol 15 (12) ◽  
pp. 2305-2320
Author(s):  
Hongxia Chen ◽  
Hong Deng ◽  
Xianbiao Zou ◽  
Jingquan Zhao
Keyword(s):  
Endothelial Cells ◽  
Macular Degeneration ◽  
Vascular Endothelial Cells ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Vascular Endothelial ◽  
Age Related ◽  
Triphenyl Phosphonium ◽  
Hypocrellin B

Verteporfin photodynamic therapy (PDT) has been approved for the treatment of exudative age-related macular degeneration (AMD) for over a decade. However, its extensive application has been impeded by inevitably collateral tissue damage and immediate induction of angiogenesis, in addition to the need of multiple treatments. In order to develop prospective photosensitizers for clinical use, a triphenyl phosphonium-modified cationic liposomal hypocrellin B (TPP cationic LHB) for angiogenic targeting and endothelial internalization was constructed. With optimal PDT parameters, TPP cationic LHB can lead to death of choroid-retinal vascular endothelial cells while cause negligible damage to collateral retinal pigment epithelium cells. This is likely due to the mitochondria targeting and effective intracellular singlet oxygen generation of TPP cationic LHB in vascular endothelial cells. Additionally, in vivo chick chorioallantoic membrane assay indicated the elevated neovessel-targeting ability and photo-induced anti-angiogenic activity of TPP cationic LHB. Furthermore, TPP cationic LHB PDT is able to maintain neovessel occlusion for an extended period of time compared with verteporfin PDT, without inducing significant increased expression of some angiogenic factors, such as vascular endothelial growth factor and integrin αvβ3. This study describes a facile strategy that may be useful for developing new-generation photosensitizers to circumvent the limitations of PDT treatment of exudative AMD.

scholarly journals CIB2 regulates autophagy via Rheb-mTORC1 signaling axis

2020 ◽  
Author(s):  
Saumil Sethna ◽  
Steven L. Bernstein ◽  
Xiaoying Jian ◽  
Sheikh Riazuddin ◽  
Paul A. Randazzo ◽  
...  
Keyword(s):  
Vision Loss ◽  
Neurodegenerative Disorder ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Negative Regulator ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Mtorc1 Signaling ◽  
Signaling Axis ◽  
Dry Amd

SUMMARYAge-related macular degeneration (AMD), a multifactorial neurodegenerative disorder, is the most common cause of vision loss in the elderly. Deficits in autophagy have been associated with age-related retinal pigment epithelium (RPE) pathology in mice, and dry-AMD in humans. In this study, we establish that the calcium and integrin binding protein 2 (CIB2) regulates autophagy in the RPE via Rheb-mTORC1 signaling axis. Cib2 mutant mice have reduced autophagic clearance in RPE and increased mTORC1 signaling – a negative regulator of autophagy. Concordant molecular deficits were also observed in RPE/choroid tissues from humans affected with dry AMD. Mechanistically, CIB2 negatively regulates mTORC1 by preferentially binding to ‘nucleotide empty’ or inactive GDP-loaded Rheb. Upregulated mTORC1 signaling has been implicated in aging, Tuberous sclerosis complex (TSC), and lymphangioleiomyomatosis (LAM) cancer. Over-expressing CIB2 in LAM patient-derived fibroblasts and Tsc2 null cell line down-regulates hyperactive mTORC1 signaling. Thus, our findings have significant ramifications for the etiology of AMD and mTORC1 hyperactivity disorders and treatments.

scholarly journals In vitro evaluation of simulated stereotactic radiotherapy for wet age-related macular degeneration on three different cell lines

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Efstathios Vounotrypidis ◽  
Anna Hillenmayer ◽  
Christian M. Wertheimer ◽  
Alexis Athanasiou ◽  
Jakob Siedlecki ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Death ◽  
Stereotactic Radiotherapy ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Low Energy ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Brdu Assay

AbstractLow energy stereotactic radiotherapy has been proposed for the treatment of neovascular age related macular degeneration. We investigated the in vitro effect of the radiotherapy on pericytes, retinal pigment epithelium and endothelial cells. Primary human retinal pigment epithelium cells, human umbilical vein endothelial cells and human pericytes from Placenta were cultivated. In a pairwise protocol, one plate was irradiated at a dose of 16 Gy, while the second plate served as a non-irradiated control. Thereafter, cells were cultivated either in serum-free (non-permissive) or serum-stimulated (permissive) conditions. A life/dead assay, an XTT and a BrdU assay were performed up to 7 days after irradiation. No cell death occurred at any timepoint in any cell line after treatment nor in the control. Compared to the unirradiated controls, cell viability and metabolic activity were significantly reduced in irradiated cells in the XTT assay, except for non-permissive RPE cells. In the BrdU assay, proliferation was inhibited. While no cell death was detected in vitro, viability and proliferative capacity of all cell lines were significantly reduced. Therefore, it seems that low energy stereotactic radiotherapy inhibits angiogenesis without a direct induction of apoptosis but influencing microvascular function and stability.

scholarly journals Saponin-Mediated Rejuvenation of Bruch’s Membrane: A New Strategy for Intervention in Dry Age-Related Macular Degeneration (AMD)

2021 ◽  
Author(s):  
Yunhee Lee ◽  
Eun Jung Ahn ◽  
Ali Hussain
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Bruch's Membrane ◽  
Bruch’S Membrane ◽  
Age Related ◽  
New Strategy ◽  
The Matrix ◽  
Dry Amd ◽  
Underlying Mechanisms

At present, there is no treatment modality for the vast majority of patients with dry AMD. The pathophysiology of AMD is complex but current evidence suggests that abnormal ageing of Bruch’s membrane imparts a metabolic insult to the retinal pigment epithelium (RPE) and photoreceptor cells that leads eventually to the inflammatory-mediated death of these cells. Underlying mechanisms contributing to the pathology of Bruch’s membrane include the accumulation of ‘debris’ and malfunction of the matrix metalloproteinase (MMP) system resulting in diminished metabolic support of the retina and inefficient removal of toxic pro-inflammatory mediators. Saponins are amphipathic molecules that have a hydrophobic tri-terpenoid lipid region and hydrophilic glycosidic chains that allow for the dispersion of these deposits in Bruch’s and re-activation of the MMP system leading to a 2-fold improvement in the transport properties of the membrane. Such an intervention is expected to improve the bi-directional exchange of nutrients and waste products, thereby slowing the progression of dry AMD. This will be the first drug-based interventionist possibility to address dry AMD.

scholarly journals Systems Biology Profiling of AMD on the Basis of Gene Expression

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Mones S. Abu-Asab ◽  
Jose Salazar ◽  
Jingsheng Tuo ◽  
Chi-Chao Chan
Keyword(s):  
Gene Expression ◽  
Systems Biology ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Geographic Atrophy ◽  
Age Related Macular Degeneration ◽  
Disease Spectrum ◽  
Age Related ◽  
Dry Amd ◽  
Pathway Networks

Genetic pathways underlying the initiation and progression of age-related macular degeneration (AMD) have not been yet sufficiently revealed, and the correlations of AMD’s genotypes, phenotypes, and disease spectrum are still awaiting resolution. We are tackling both problems with systems biology phylogenetic parsimony analysis. Gene expression data (GSE29801: NCBI, Geo) of macular and extramacular specimens of the retinas and retinal pigment epithelium (RPE) choroid complexes representing dry AMD without geographic atrophy (GA), choroidal neovascularization (CNV), GA, as well as pre-AMD and subclinical pre-AMD were polarized against their respective normal specimens and then processed through the parsimony program MIX to produce phylogenetic cladograms. Gene lists from cladograms’ nodes were processed in Genomatix GePS to reveal the affected signaling pathway networks. Cladograms exposed a highly heterogeneous transcriptomic profiles within all the conventional phenotypes. Moreover, clades and nodal synapomorphies did not support the classical AMD phenotypes as valid transcriptomal genotypes. Gene lists defined by cladogram nodes showed that the AMD-related deregulations occurring in the neural retina were different from those in RPE-choroidal tissue. Our analysis suggests a more complex transcriptional profile of the phenotypes than expected. Evaluation of the disease in much earlier stages is needed to elucidate the initial events of AMD.

scholarly journals Dry Age-Related Macular Degeneration – A New Approach In Optical Coherence Tomography Monitoring And Quantitative Assessment

2014 ◽  
Vol 7 (2) ◽  
pp. 148-154
Author(s):  
Elitsa G. Hristova ◽  
Zornitsa I. Zlatarova
Keyword(s):  
Macular Degeneration ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Three Dimensional ◽  
Software Tool ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Dry Amd ◽  
Area And Volume

Summary The purpose of the study was to present the ability of Drusen analysis software tool to measure drusen area and volume in patients with dry age-related macular degeneration (AMD). Eleven patients with confirmed dry AMD aged 59-74 years were scanned with 3D OCT-2000 Topcon 3D Macula scanning protocol by a single operator. All subjects underwent a complete ophthalmologic examination including best corrected visual acuity, indirect biomicroscopy, tonometry, fluorescein angiography and OCT. Drusen analysis was performed on the macula with 6.0 × 6.0 mm volume cube scans and 512×128 pixels scan resolution. The results were presented along with calculated values in two clearly arranged reports. Mean follow-up period was 19 months (6-40). Count, area occupation, volume of the drusen and 3D retinal pigment epithelium (RPE) elevation map were presented in a Macula drusen analysis report. Drusen count and volume in 6 patients were increased at the end of follow-up period. There were 5 patients with regression in drusen count and area and volume of the drusen in 3 of them were higher than on previous examination. Another 2 were with regression not only in drusen count but also in their area and volume. With this software tool the status of RPE can be objectively and automatically examined in detail and can be followed up over time. OCT allows for precise quantitative evaluation and study of microstructural changes in patients with dry AMD and provides three-dimensional information of macular pathology in situ and in real time. This could be useful for determining stages and monitoring the progression of AMD.

scholarly journals Bioprinted 3D Outer Retina Barrier Uncovers RPE-dependent Choroidal Phenotype in Advanced Macular Degeneration

2021 ◽  
Author(s):  
Kapil Bharti ◽  
Min Jae Song ◽  
Russell Quinn ◽  
Eric Nguyen ◽  
Tea Soon Park ◽  
...  
Keyword(s):  
Macular Degeneration ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Specific Gene ◽  
Tissue Integration ◽  
Age Related ◽  
Dry Amd ◽  
Barrier Resistance ◽  
Wet Amd

Abstract Age-related macular degeneration (AMD), a leading cause of blindness, initiates in the outer-blood-retina-barrier (oBRB) formed by Retinal pigment epithelium (RPE), Bruch’s membrane, and choriocapillaris. The mechanism of AMD initiation and progression remain poorly understood due to the lack of physiologically relevant oBRB models. We engineered a native-like 3D-oBRB tissue by bioprinting endothelial cells, pericytes, and fibroblasts on the basal side of a biodegradable scaffold and establishing an RPE monolayer on top. In this 3D-oBRB, a fully-polarized RPE monolayer with apical processes and basal infoldings provides barrier resistance, induces fenestration and choroid-specific gene expression in the choriocapillaris, and supports the formation of a Bruch’s-like membrane that allows tissue integration in rat eyes. Complement activation in the 3D-oBRB triggers dry-AMD phenotypes (including subRPE drusen and choriocapillaris degeneration), and hypoxia activated HIF-α induces wet-AMD phenotypes (choriocapillaris neovascularization). Anti-VEGF drug treatment suppresses neovascularization - validating this model for clinical translation and drug discovery.

Age-related macular degeneration treatment: current view (literature review)

2014 ◽  
Vol 21 (1) ◽  
pp. 43-50
Author(s):  
Monika Kalesinskaitė ◽  
Diana Uljanionok ◽  
Rasa Liutkevičienė
Keyword(s):  
Macular Degeneration ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Treatment Options ◽  
Geographic Atrophy ◽  
Age Related Macular Degeneration ◽  
Current View ◽  
Neovascular Amd ◽  
Age Related ◽  
Dry Amd

Age-related macular degeneration (AMD) – is a damage of the macula, accompanied by a significant and irreversible loss of central vision. It is a major cause of blindness and visual impairment in older adults (>60 years). Damage of the retina always includes both eyes, though the intensity can vary. Early AMD is defined as the presence of drusen and retinal pigmentary abnormalities (RPE); late AMD includes dry AMD (geographic atrophy of the RPE in the absence of neovascular AMD) or neovascular AMD  (detachment of the retinal pigment epithelium, hemorrhages, and/or scars). Unfortunately, the etiology and pathogenesis of AMD aren’t fully understood up to now, so treatment options are limited and not always effective. This article briefly reviews the options of initial and late forms of AMD treatment

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