scholarly journals Glycine-Conjugated Bile Acids Protect RPE Tight Junctions against Oxidative Stress and Inhibit Choroidal Endothelial Cell Angiogenesis In Vitro

Biomolecules ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 626
Author(s):  
Cassandra Warden ◽  
Milam A. Brantley
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Bile Acids ◽  
Tight Junctions ◽  
Retinal Pigment ◽  
Tube Formation ◽  
Age Related Macular Degeneration ◽  
Rpe Cells ◽  
Conjugated Bile Acids

We previously demonstrated that the bile acid taurocholic acid (TCA) inhibits features of age-related macular degeneration (AMD) in vitro. The purpose of this study was to determine if the glycine-conjugated bile acids glycocholic acid (GCA), glycodeoxycholic acid (GDCA), and glycoursodeoxycholic acid (GUDCA) can protect retinal pigment epithelial (RPE) cells against oxidative damage and inhibit vascular endothelial growth factor (VEGF)-induced angiogenesis in choroidal endothelial cells (CECs). Paraquat was used to induce oxidative stress and disrupt tight junctions in HRPEpiC primary human RPE cells. Tight junctions were assessed via transepithelial electrical resistance and ZO-1 immunofluorescence. GCA and GUDCA protected RPE tight junctions against oxidative damage at concentrations of 100–500 µM, and GDCA protected tight junctions at 10–500 µM. Angiogenesis was induced with VEGF in RF/6A macaque CECs and evaluated with cell proliferation, cell migration, and tube formation assays. GCA inhibited VEGF-induced CEC migration at 50–500 µM and tube formation at 10–500 µM. GUDCA inhibited VEGF-induced CEC migration at 100–500 µM and tube formation at 50–500 µM. GDCA had no effect on VEGF-induced angiogenesis. None of the three bile acids significantly inhibited VEGF-induced CEC proliferation. These results suggest glycine-conjugated bile acids may be protective against both atrophic and neovascular AMD.

scholarly journals Autophagy Upregulation by the TFEB Inducer Trehalose Protects against Oxidative Damage and Cell Death Associated with NRF2 Inhibition in Human RPE Cells

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Samuel Abokyi ◽  
Sze wan Shan ◽  
Chi-ho To ◽  
Henry Ho-lung Chan ◽  
Dennis Yan-yin Tse
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Mrna Levels ◽  
Neuroprotective Effects ◽  
Rpe Cells ◽  
Age Related ◽  
Protein Expressions

Trehalose is a natural dietary molecule that has shown antiaging and neuroprotective effects in several animal models of neurodegenerative diseases. The role of trehalose in the management of age-related macular degeneration (AMD) is yet to be investigated and whether trehalose could be a remedy for the treatment of diseases linked to oxidative stress and NRF2 dysregulation. Here, we showed that incubation of human retinal pigment epithelial (RPE) cells with trehalose enhanced the mRNA and protein expressions of TFEB, autophagy genes ATG5 and ATG7, as well as protein expressions of macroautophagy markers, LC3B and p62/SQTM1, and the chaperone-mediated autophagy (CMA) receptor LAMP2. Cathepsin D, a hydrolytic lysosomal enzyme, was also increased by trehalose, indicating higher proteolytic activity. Moreover, trehalose upregulated autophagy flux evident by an increase in the endogenous LC3B level, and accumulation of GFP-LC3B puncta and free GFP fragments in GFP-LC3 ̶ expressing cells in the presence of chloroquine. In addition, the mRNA levels of key molecular targets implicated in RPE damage and AMD, such as vascular endothelial growth factor- (VEGF-) A and heat shock protein 27 (HSP27), were downregulated, whereas NRF2 was upregulated by trehalose. Subsequently, we mimicked in vitro AMD conditions using hydroquinone (HQ) as the oxidative insult on RPE cells and evaluated the cytoprotective effect of trehalose compared to vehicle treatment. HQ depleted NRF2, increased oxidative stress, and reduced the viability of cells, while trehalose pretreatment protected against HQ-induced toxicity. The cytoprotection by trehalose was dependent on autophagy but not NRF2 activation, since autophagy inhibition by shRNA knockdown of ATG5 led to a loss of the protective effect. The results support the transcriptional upregulation of TFEB and autophagy by trehalose and its protection against HQ-induced oxidative damage in RPE cells. Further investigation is, therefore, warranted into the therapeutic value of trehalose in alleviating AMD and retinal diseases associated with impaired NRF2 antioxidant defense.

scholarly journals Autophagy in Age-Related Macular Degeneration: A Regulatory Mechanism of Oxidative Stress

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zi-Yuan Zhang ◽  
Xiao-Li Bao ◽  
Yun-Yi Cong ◽  
Bin Fan ◽  
Guang-Yu Li
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Macular Degeneration ◽  
Retinal Pigment ◽  
The Elderly ◽  
Age Related Macular Degeneration ◽  
Therapeutic Interventions ◽  
Cell Degeneration ◽  
Rpe Cells ◽  
Age Related

Age-related macular degeneration (AMD) is a leading cause of severe visual loss and irreversible blindness in the elderly population worldwide. Retinal pigment epithelial (RPE) cells are the major site of pathological alterations in AMD. They are responsible for the phagocytosis of shed photoreceptor outer segments (POSs) and clearance of cellular waste under physiological conditions. Age-related, cumulative oxidative stimuli contribute to the pathogenesis of AMD. Excessive oxidative stress induces RPE cell degeneration and incomplete digestion of POSs, leading to the continuous accumulation of cellular waste (such as lipofuscin). Autophagy is a major system of degradation of damaged or unnecessary proteins. However, degenerative RPE cells in AMD patients cannot perform autophagy sufficiently to resist oxidative damage. Increasing evidence supports the idea that enhancing the autophagic process can properly alleviate oxidative injury in AMD and protect RPE and photoreceptor cells from degeneration and death, although overactivated autophagy may lead to cell death at early stages of retinal degenerative diseases. The crosstalk among the NFE2L2, PGC-1, p62, AMPK, and PI3K/Akt/mTOR pathways may play a crucial role in improving disturbed autophagy and mitigating the progression of AMD. In this review, we discuss how autophagy prevents oxidative damage in AMD, summarize potential neuroprotective strategies for therapeutic interventions, and provide an overview of these neuroprotective mechanisms.

scholarly journals Protective Effect of Melatonin against Oxidative Stress-Induced Apoptosis and Enhanced Autophagy in Human Retinal Pigment Epithelium Cells

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Chih-Chao Chang ◽  
Tien-Yi Huang ◽  
Hsin-Yuan Chen ◽  
Tsui-Chin Huang ◽  
Li-Chun Lin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Critical Role ◽  
Age Related Macular Degeneration ◽  
Cell Degeneration ◽  
Rpe Cells ◽  
Age Related ◽  
Human Rpe Cells

Age-related macular degeneration (AMD) affects the retinal macula and results in loss of vision, and AMD is the primary cause of blindness and severe visual impairment among elderly people worldwide. AMD is characterized by the accumulation of drusen in the Bruch’s membrane and dysfunction of retinal pigment epithelial (RPE) cells and photoreceptors. The pathogenesis of AMD remains unclear, and no effective treatment exists. Accumulating evidence indicates that oxidative stress plays a critical role in RPE cell degeneration and AMD. Melatonin is an antioxidant that scavenges free radicals, and it has anti-inflammatory, antitumor, and antiangiogenic effects. This study investigated the antioxidative, antiapoptotic, and autophagic effects of melatonin on oxidative damage to RPE cells. We used hydrogen peroxide (H2O2) to stimulate reactive oxygen species production to cause cell apoptosis in ARPE-19 cell lines. Our findings revealed that treatment with melatonin significantly inhibited H2O2-induced RPE cell damage, decreased the apoptotic rate, increased the mitochondrial membrane potential, and increased the autophagy effect. Furthermore, melatonin reduced the Bax/Bcl-2 ratio and the expression levels of the apoptosis-associated proteins cytochrome c and caspase 7. Additionally, melatonin upregulated the expression of the autophagy-related proteins LC3-II and Beclin-1 and downregulated the expression of p62. Thus, melatonin’s effects on autophagy and apoptosis can protect against H2O2-induced oxidative damage in human RPE cells. Melatonin may have multiple protective effects on human RPE cells against H2O2-induced oxidative damage.

scholarly journals Superior Properties of N-Acetylcysteine Ethyl Ester over N-Acetyl Cysteine to Prevent Retinal Pigment Epithelial Cells Oxidative Damage

2021 ◽  
Vol 22 (2) ◽  
pp. 600
Author(s):  
Gian Marco Tosi ◽  
Daniela Giustarini ◽  
Lorenzo Franci ◽  
Alberto Minetti ◽  
Francesco Imperatore ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
Ethyl Ester ◽  
Retinal Pigment ◽  
Developed Countries ◽  
Retinal Pigment Epithelial Cells ◽  
Age Related Macular Degeneration ◽  
Retinal Diseases ◽  
Rpe Cells ◽  
Age Related

Oxidative stress plays a key role in the pathophysiology of retinal diseases, including age-related macular degeneration (AMD) and diabetic retinopathy, which are the major causes of irreversible blindness in developed countries. An excess of reactive oxygen species (ROS) can directly cause functional and morphological impairments in retinal pigment epithelium (RPE), endothelial cells, and retinal ganglion cells. Antioxidants may represent a preventive/therapeutic strategy and reduce the risk of progression of AMD. Among antioxidants, N-acetyl-L-cysteine (NAC) is widely studied and has been proposed to have therapeutic benefit in treating AMD by mitigating oxidative damage in RPE. Here, we demonstrate that N-acetyl-L-cysteine ethyl ester (NACET), a lipophilic cell-permeable cysteine derivative, increases the viability in oxidative stressed RPE cells more efficiently than NAC by reacting directly and more rapidly with oxidizing agents, and that NACET, but not NAC, pretreatment predisposes RPE cells to oxidative stress resistance and increases the intracellular reduced glutathione (GSH) pool available to act as natural antioxidant defense. Moreover, we demonstrate the ability of NACET to increase GSH levels in rats’ eyes after oral administration. In conclusion, even if experiments in AMD animal models are still needed, our data suggest that NACET may play an important role in preventing and treating retinal diseases associated with oxidative stress, and may represent a valid and more efficient alternative to NAC in therapeutic protocols in which NAC has already shown promising results.

scholarly journals FHL-1 interacts with human RPE cells through the α5β1 integrin and confers protection against oxidative stress

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rawshan Choudhury ◽  
Nadhim Bayatti ◽  
Richard Scharff ◽  
Ewa Szula ◽  
Viranga Tilakaratna ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Fate ◽  
Retinal Pigment ◽  
Factor H ◽  
Age Related Macular Degeneration ◽  
Bruch's Membrane ◽  
Bruch’S Membrane ◽  
Rpe Cells ◽  
Age Related

AbstractRetinal pigment epithelial (RPE) cells that underlie the neurosensory retina are essential for the maintenance of photoreceptor cells and hence vision. Interactions between the RPE and their basement membrane, i.e. the inner layer of Bruch’s membrane, are essential for RPE cell health and function, but the signals induced by Bruch’s membrane engagement, and their contributions to RPE cell fate determination remain poorly defined. Here, we studied the functional role of the soluble complement regulator and component of Bruch’s membrane, Factor H-like protein 1 (FHL-1). Human primary RPE cells adhered to FHL-1 in a manner that was eliminated by either mutagenesis of the integrin-binding RGD motif in FHL-1 or by using competing antibodies directed against the α5 and β1 integrin subunits. These short-term experiments reveal an immediate protein-integrin interaction that were obtained from primary RPE cells and replicated using the hTERT-RPE1 cell line. Separate, longer term experiments utilising RNAseq analysis of hTERT-RPE1 cells bound to FHL-1, showed an increased expression of the heat-shock protein genes HSPA6, CRYAB, HSPA1A and HSPA1B when compared to cells bound to fibronectin (FN) or laminin (LA). Pathway analysis implicated changes in EIF2 signalling, the unfolded protein response, and mineralocorticoid receptor signalling as putative pathways. Subsequent cell survival assays using H2O2 to induce oxidative stress-induced cell death suggest hTERT-RPE1 cells had significantly greater protection when bound to FHL-1 or LA compared to plastic or FN. These data show a non-canonical role of FHL-1 in protecting RPE cells against oxidative stress and identifies a novel interaction that has implications for ocular diseases such as age-related macular degeneration.

scholarly journals Sulforaphane Enhances the Ability of Human Retinal Pigment Epithelial Cell against Oxidative Stress, and Its Effect on Gene Expression Profile Evaluated by Microarray Analysis

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Liang Ye ◽  
Ting Yu ◽  
Yanqun Li ◽  
Bingni Chen ◽  
Jinshun Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Microarray Analysis ◽  
Retinal Pigment Epithelial ◽  
Nuclear Translocation ◽  
Retinal Pigment ◽  
Regulation Of Gene Expression ◽  
Age Related Macular Degeneration ◽  
Rpe Cells ◽  
Pigment Epithelial

To gain further insights into the molecular basis of Sulforaphane (SF) mediated retinal pigment epithelial (RPE) 19 cell against oxidative stress, we investigated the effects of SF on the regulation of gene expression on a global scale and tested whether SF can endow RPE cells with the ability to resist apoptosis. The data revealed that after exposure to H2O2, RPE 19 cell viability was increased in the cells pretreated with SF compared to the cell not treated with SF. Microarray analysis revealed significant changes in the expression of 69 genes in RPE 19 cells after 6 hours of SF treatment. Based on the functional relevance, eight of the SF-responsive genes, that belong to antioxidant redox system, and inflammatory responsive factors were validated. The up-regulating translation of thioredoxin-1 (Trx1) and the nuclear translocation of Nuclear factor-like2 (Nrf2) were demonstrated by immunoblot analysis in SF treated RPE cells. Our data indicate that SF increases the ability of RPE 19 cell against oxidative stress through up-regulating antioxidative enzymes and down-regulating inflammatory mediators and chemokines. The results suggest that the antioxidant, SF, may be a valuable supplement for preventing and retarding the development of Age Related Macular Degeneration.

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 PGC-1α Protects RPE Cells of the Aging Retina against Oxidative Stress-Induced Degeneration through the Regulation of Senescence and Mitochondrial Quality Control. The Significance for AMD Pathogenesis

2018 ◽  
Vol 19 (8) ◽  
pp. 2317 ◽  
Author(s):  
Kai Kaarniranta ◽  
Jakub Kajdanek ◽  
Jan Morawiec ◽  
Elzbieta Pawlowska ◽  
Janusz Blasiak
Keyword(s):  
Oxidative Stress ◽  
Cellular Senescence ◽  
Mitochondrial Biogenesis ◽  
Vision Loss ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Sirtuin 1 ◽  
Age Related Macular Degeneration ◽  
Rpe Cells ◽  
Age Related

PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) is a transcriptional coactivator of many genes involved in energy management and mitochondrial biogenesis. PGC-1α expression is associated with cellular senescence, organismal aging, and many age-related diseases, including AMD (age-related macular degeneration), an important global issue concerning vision loss. We and others have developed a model of AMD pathogenesis, in which stress-induced senescence of retinal pigment epithelium (RPE) cells leads to AMD-related pathological changes. PGC-1α can decrease oxidative stress, a key factor of AMD pathogenesis related to senescence, through upregulation of antioxidant enzymes and DNA damage response. PGC-1α is an important regulator of VEGF (vascular endothelial growth factor), which is targeted in the therapy of wet AMD, the most devastating form of AMD. Dysfunction of mitochondria induces cellular senescence associated with AMD pathogenesis. PGC-1α can improve mitochondrial biogenesis and negatively regulate senescence, although this function of PGC-1α in AMD needs further studies. Post-translational modifications of PGC-1α by AMPK (AMP kinase) and SIRT1 (sirtuin 1) are crucial for its activation and important in AMD pathogenesis.

scholarly journals Oxidative stress-mediated TXNIP loss causes RPE dysfunction

2019 ◽  
Vol 51 (10) ◽  
pp. 1-13 ◽  
Author(s):  
Min Ji Cho ◽  
Sung-Jin Yoon ◽  
Wooil Kim ◽  
Jongjin Park ◽  
Jangwook Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Function ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Common Factor ◽  
Age Related Macular Degeneration ◽  
Autophagic Flux ◽  
Blood Retinal Barrier ◽  
Rpe Cells ◽  
Age Related

Abstract The disruption of the retinal pigment epithelium (RPE), for example, through oxidative damage, is a common factor underlying age-related macular degeneration (AMD). Aberrant autophagy also contributes to AMD pathology, as autophagy maintains RPE homeostasis to ensure blood–retinal barrier (BRB) integrity and protect photoreceptors. Thioredoxin-interacting protein (TXNIP) promotes cellular oxidative stress by inhibiting thioredoxin reducing capacity and is in turn inversely regulated by reactive oxygen species levels; however, its role in oxidative stress-induced RPE cell dysfunction and the mechanistic link between TXNIP and autophagy are largely unknown. Here, we observed that TXNIP expression was rapidly downregulated in RPE cells under oxidative stress and that RPE cell proliferation was decreased. TXNIP knockdown demonstrated that the suppression of proliferation resulted from TXNIP depletion-induced autophagic flux, causing increased p53 activation via nuclear localization, which in turn enhanced AMPK phosphorylation and activation. Moreover, TXNIP downregulation further negatively impacted BRB integrity by disrupting RPE cell tight junctions and enhancing cell motility by phosphorylating, and thereby activating, Src kinase. Finally, we also revealed that TXNIP knockdown upregulated HIF-1α, leading to the enhanced secretion of VEGF from RPE cells and the stimulation of angiogenesis in cocultured human retinal microvascular endothelial cells. This suggests that the exposure of RPE cells to sustained oxidative stress may promote choroidal neovascularization, another AMD pathology. Together, these findings reveal three distinct mechanisms by which TXNIP downregulation disrupts RPE cell function and thereby exacerbates AMD pathogenesis. Accordingly, reinforcing or restoring BRB integrity by targeting TXNIP may serve as an effective therapeutic strategy for preventing or attenuating photoreceptor damage in AMD.

scholarly journals Protective Effect of Metformin against Hydrogen Peroxide-Induced Oxidative Damage in Human Retinal Pigment Epithelial (RPE) Cells by Enhancing Autophagy through Activation of AMPK Pathway

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xia Zhao ◽  
Linlin Liu ◽  
Yizhou Jiang ◽  
Marta Silva ◽  
Xuechu Zhen ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Age Related Macular Degeneration ◽  
Protective Effects ◽  
Rpe Cells ◽  
Mitochondria Membrane Potential ◽  
Ampk Pathway ◽  
Age Related ◽  
Diabetes Drug

Age-related macular degeneration (AMD) is a leading cause of blindness with limited effective treatment. Although the pathogenesis of this disease is complex and not fully understood, the oxidative damage caused by excessive reactive oxygen species (ROS) in retinal pigment epithelium (RPE) has been considered as a major cause. Autophagy is essential for the degradation of cellular components damaged by ROS, and its dysregulation has been implicated in AMD pathogenesis. Therefore, strategies aiming to boost autophagy could be effective in protecting RPE cells from oxidative damage. Metformin is the first-line anti-type 2 diabetes drug and has been reported to stimulate autophagy in many tissues. We therefore hypothesized that metformin may be able to protect RPE cells against H2O2-induced oxidative damage by autophagy activation. In the present study, we found that metformin attenuated H2O2-induced cell viability loss, apoptosis, elevated ROS levels, and the collapse of the mitochondria membrane potential in D407 cells. Autophagy was stimulated by metformin, and inhibition of autophagy by 3-methyladenine (3-MA) and chloroquine (CQ) or knockdown of Beclin1 and LC3B blocked the protective effects of metformin. In addition, we showed that metformin could activate the AMPK pathway, whereas both pharmacological and genetic inhibitions of AMPK blocked the autophagy-stimulating and protective effects of metformin. Metformin conferred a similar protection against H2O2-induced oxidative damage in primary cultured human RPE cells. Taken together, these results demonstrate that metformin could protect RPE cells from H2O2-induced oxidative damage by stimulating autophagy via the activation of the AMPK pathway, supporting its potential use in the prevention and treatment of AMD.

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