Inhibition of EGFR attenuates EGF-induced activation of retinal pigment epithelium cell via EGFR/AKT signaling pathway

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 via EGFR/AKT pathway in RPE cells.EGFR inhibition may be a possible therapeutic approach for proliferative vitreoretinopathy(PVR).

RNA-sequencing expression profile and functional analysis of retinal pigment epithelium in atrophic age-related macular degeneration

The retinal pigment epithelium(RPE)is fundamental to sustaining retinal homeostasis.RPE abnormality leads to visual defects and blindness,including age-related macular degeneration(AMD).Although breakthroughs have been made in the treatment of neovascular AMD,effective intervention for atrophic AMD is largely absent.The adequate knowledge of RPE pathology is hindered by a lack of the patients'RPE datasets,especially at the single-cell resolution.In the current study,we delved into a large-scale single-cell resource of AMD donors,in which RPE cells were occupied in a substantial proportion.Bulk RNA-seq datasets of atrophic AMD were integrated to extract molecular characteristics of RPE in the pathogenesis of atrophic AMD.Both in vivo and in vitro models revealed that carboxypeptidase X,M14 family member 2(CPXM2),was specifically expressed in the RPE cells of atrophic AMD,which might be induced by oxidative stress and involved in the epithelial-mesenchymal transition of RPE cells.Additionally,silencing of CPXM2 inhibited the mesenchymal phenotype of RPE cells in an oxidative stress cell model.Thus,our results demonstrated that CPXM2 played a crucial role in regulating atrophic AMD and might serve as a potential therapeutic target for atrophic AMD.

Effect of acetyl L-carnitine on human retinal pigment epithelium-19 cells in hypoxic conditions

AIM:To investigate the effect of acetyl-L-carnitine(ALCAR)on cell viability,morphological integrity,and vascular endothelial growth factor(VEGF)expression in human retinal pigment epithelium(ARPE-19)cells using a hypoxic model.METHODS:In the first set of experiments,the optimal CoCl_(2) dose was determined by exposing ARPE-19 cell cultures to different concentrations.To evaluate the effect of ALCAR on cell viability,five groups of ARPE-19 cell culture were established that included a control group,a sham group(200μM CoCl_(2)),and groups that received 1,10 and 100 mM doses of ALCAR combined with 200μM CoCl_(2),respectively.The cell viability was measured by MTT assay.The morphological characteristics of cells were observed by an inverted phase contrast microscope.The levels of VEGF and HIF-1α secretion by ARPE-19 cells were detected by enzyme linked immunosorbent assay(ELISA)assay.RESULTS:ARPE-19 cells were exposed to different doses of CoCl_(2) in order to create a hypoxia model.Nevertheless,when exposed to a concentration of 200μM CoCl_(2),a notable decrease in viability to 83% was noted.ALCAR was found to increase the cell viability at 1 mM and 10 mM concentrations,while the highest concentration(100 mM)did not have an added effect.The cell viability was found to be significantly higher in the groups treated with a concentration of 1 mM and 10 mM ALCAR compared to the Sham group(P=0.041,P=0.019,respectively).The cell viability and morphology remained unaffected by the greatest dose of ALCAR(100 mM).The administration of 10 mM ALCAR demonstrated a statistically significant reduction in the levels of VEGF and HIF-1α compared with the Sham group(P=0.013,P=0.033,respectively).CONCLUSION:The findings from the current study indicate that ALCAR could represent a viable therapeutic option with the potential to open up novel treatment pathways for retinal diseases,particular relevance for age-related macular degeneration(AMD).However,to fully elucidate ALCAR’s application potential in retinal diseases,additional investigation is necessary to clearly define the exact mechanisms involved.

Oxidative stress in retinal pigment epithelium degeneration:from pathogenesis to therapeutic targets in dry age-related macular degeneration

Age-related macular degeneration is a primary cause of blindness in the older adult population. Past decades of research in the pathophysiology of the disease have resulted in breakthroughs in the form of anti-vascular endothelial growth factor therapies against neovascular age-related macular degeneration;however, effective treatment is not yet available for geographical atrophy in dry agerelated macular degeneration or for preventing the progression from early or mid to the late stage of age-related macular degeneration. Both clinical and experimental investigations involving human agerelated macular degeneration retinas and animal models point towards the atrophic alterations in retinal pigment epithelium as a key feature in age-related macular degeneration progression. Retinal pigment epithelium cells are primarily responsible for cellular-structural maintenance and nutrition supply to keep photoreceptors healthy and functional. The retinal pigment epithelium constantly endures a highly oxidative environment that is balanced with a cascade of antioxidant enzyme systems regulated by nuclear factor erythroid-2-related factor 2 as a main redox sensing transcription factor. Aging and accumulated oxidative stress triggers retinal pigment epithelium dysfunction and eventually death. Exposure to both environmental and genetic factors aggravates oxidative stress damage in aging retinal pigment epithelium and accelerates retinal pigment epithelium degeneration in age-related macular degeneration pathophysiology. The present review summarizes the role of oxidative stress in retinal pigment epithelium degeneration, with potential impacts from both genetic and environmental factors in age-related macular degeneration development and progression. Potential strategies to counter retinal pigment epithelium damage and protect the retinal pigment epithelium through enhancing its antioxidant capacity are also discussed, focusing on existing antioxidant nutritional supplementation, and exploring nuclear factor erythroid-2-related factor 2 and its regulators including REV-ERBα as therapeutic targets to protect against age-related macular degeneration development and progression.

Gene Therapy Activates Retinal Pigment Epithelium Cell Proliferation for Age-related Macular Degeneration in a Mouse Model

Objective Age-related macular degeneration(AMD)is a degenerative retinal disease.The degeneration or death of retinal pigment epithelium(RPE)cells is implicated in the pathogenesis of AMD.This study aimed to activate the proliferation of RPE cells in vivo by using an adeno-associated virus(AAV)vector encodingβ-catenin to treat AMD in a mouse model.Methods Mice were intravitreally injected with AAV2/8-Y733F-VMD2-β-catenin for 2 or 4 weeks,andβ-catenin expression was measured using immunofluorescence staining,real-time quantitative reverse transcription polymerase chain reaction(PCR),and Western blotting.The function ofβ-catenin was determined using retinal flat mounts and laser-induced damage models.Finally,the safety of AAV2/8-Y733F-VMD2-β-catenin was evaluated by multiple intravitreal injections.Results AAV2/8-Y733F-VMD2-β-catenin induced the expression ofβ-catenin in RPE cells.It activated the proliferation of RPE cells and increased cyclin D1 expression.It was beneficial to the recovery of laser-induced damage by activating the proliferation of RPE cells.Furthermore,it could induce apoptosis of RPE cells by increasing the expression of Trp53,Bax and caspase3 while decreasing the expression of Bcl-2.Conclusion AAV2/8-Y733F-VMD2-β-catenin increasedβ-catenin expression in RPE cells,activated RPE cell proliferation,and helped mice heal from laser-induced eye injury.Furthermore,it could induce the apoptosis of RPE cells.Therefore,it may be a safe approach for AMD treatment.

Combined hamartoma of the retina and retinal pigment epithelium:A case report

BACKGROUND Combined hamartoma of the retina and retinal pigment epithelium(CHRRPE)is a rare congenital benign tumor which is commonly monocular.Typical CHRRPE comprises slightly raised lesions at the posterior pole,with proliferation membrane often leading to vascular distortion.In severe cases,macular edema,macular hole,retinal detachment or vitreous hemorrhage may occur.Patients with atypical clinical manifestations are prone to misdiagnosis by inexperienced ophthalmologists.CASE SUMMARY A 33-year-old man reported onset of right eye blurred vision for one week prior.Anterior segment and intraocular pressure were normal in both eyes.Left eye fundus photography was normal.Right eye ophthalmoscopy showed vitreous hemorrhage and off-white raised retinal lesions below the optic disc.Proliferative membranes on the lesion surfaces resulted in superficial retinal detachment and tortuosity and occlusion of peripheral blood vessels.A horseshoe-like tear in the temporal periphery was surrounded by retinal detachment.Optical coherence tomography revealed retinal thickening at the focal site with structural disturbance indicated by high reflectance.Right eye ultrasound showed retinal thickening at the lesion,stretching and uplifting of the proliferative membrane,with moderately patchy echo at the optic disc edge.Cytokines and antibodies were detected in vitreous fluids during the operation to rule out other diseases.Fundus fluorescein angiography(FFA)at postoperative follow-up led to final diagnosis of CHRRPE.CONCLUSION FFA is helpful in diagnosing retinal and retinal pigment epithelial combined hamartoma.In addition,other cytokine and etiological tests facilitate further differential diagnosis to rule out other suspected diseases.

Autophagy: a new mechanism for regulating VEGF and PEDF expression in retinal pigment epithelium cells

AIM: To investigate the regulation of vascular endothelial growth factors(VEGF) and pigment epithelium-derived factor(PEDF) expression by autophagy in retinal pigment epithelium(RPE) cells on exposure to hypoxia. METHODS: ARPE-19, an RPE cell line, was treated as following: the control group was kept in a normoxic incubator; the hypoxia group was incubated in a hypoxic incubator with 1% O_2/5% CO_2/94% N_2 for 24 h; the hypoxia + 3-methyladenine(3-MA) group was pretreated with 10 mmol/L 3-MA for 1 h and then in the hypoxic incubator for 24 h; and the hypoxia + chloroquine(CQ) group was pretreated with 50 μmol/L CQ for 1 h and then in the hypoxic incubator for 24 h. The morphology and ultrastructure of the cells was observed by an inverted microscope or a transmission electronic microscope(TEM). Western blot was performed to assay the expression of autophagy-associated markers, including microtubule associated protein 1 light chain 3 B(LC3 B), Beclin-1, Atg5 and p62. The concentration of VEGF and PEDF in the culture supernatant was determined by ELISA, and the ratio of VEGF/PEDF was calculated. RESULTS: There were no obvious differences in cell morphology among different groups and autolysosomes could be observed in the cytoplasm in all groups. Compared to the control cells, the LC3 B-II/I ratio and levels of Beclin-1 and Atg5 were significantly increased and p62 level was significantly decreased in the hypoxia group. With the increase of VEGF and decrease of PEDF concentration, the VEGF/PEDF ratio was significantly increased in the hypoxia group compared to the control cells. The LC3 B-II/I ratio was significantly reduced by 3-MA treatment and increased by CQ treatment. The expressions of Beclin-1 and Atg5 were significantly reduced by 3-MA or CQ treatment, while expression of p62 was increased in the 3-MA or CQ treated cells. The concentration of VEGF was significantly decreased and PEDF increased, thereby the VEGF/PEDF ratio was decreased in the hypoxia + 3-MA group and hypoxia + CQ group compared with that in the hypoxia group. CONCLUSION: Hypoxia leads to elevated autophagy in RPE cells, and expression of VEGF and PEDF might be regulated by autophagy on exposure to hypoxia to further participate in regulating the formation of retinal neovascularization.

Protective effects of lipoic acid-niacin dimers against blue light-induced oxidative damage to retinal pigment epithelium cells

AIM: To evaluate the protective effects of lipoic acid-niacin(N2 L) dimers against blue light(BL)-induced oxidative damage to human retinal pigment epithelium(hRPE) cells in vitro.METHODS: h RPE cells were divided into a control group(CG), a BL group, an N2 L plus BL irradiation group, an α-lipoic acid(ALA) plus BL group, an ALA-only group, and an N2 L-only group. hRPE cellular viability was detected by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium(MTT) bromide assays, and apoptosis was evaluated by annexin-V-PE/7-AAD staining followed by flow cytometry. Ultrastructural changes in subcellular organelles were observed by transmission electron microscopy. Reactive oxygen species formation was assayed by flow cytometry. The expression levels of the apoptosis-related proteins BCL-2 associated X protein(BAX), B-cell leukmia/lymphoma 2(BCL-2), and caspase-3 were quantified by Western blot analysis.RESULTS: BL exposure with a light density of 4±0.5 mW/cm2 exceeding 6 h caused hRPE toxicity, whereas treatment with a high dose of N2 L(100 mol/L) or ALA(150 mol/L) maintained cell viability at control levels. BL exposure caused vacuole-like degeneration, mitochondrial swelling, and reduced microvillus formation;however, a high dose of N2 L or ALA maintained the ultrastructure of hRPE cells and their organelles. High doses of N2 L and ALA also protected hRPE cells from BL-induced apoptosis, which was confirmed by Western blot analysis: BCL-2 expression significantly increased, while BAX and caspase-3 expression slightly decreased compared to the CG.CONCLUSION: High-dose N2 L treatment(>100 mol/L) can reduce oxidative damage in degenerating hRPE cells exposed to BL with an efficacy similar to ALA.

A novel xeno-free culture system for human retinal pigment epithelium cells

AIM: To find out an animal-free, xeno-free culture method for human fetal retinal pigment epithelium(fRPE) cells aiming for cell-replacement therapy. METHODS: Human AB serum, knock-out serum replacement(KSR) and B27 were supplemented as a substitute of fetal bovine serum(FBS) in culture medium of human fRPE cells. Cell morphology was examined by light microscope and transmission electron microscope. Proliferation ability was detected by cell cycle analysis and examination of KI67 expression. Apoptosis was analyzed using FACS. The expression ofRPE-specific markers was demonstrated by quantitative real-time polymerase chain reaction(qPCR), Western blot(WB) and immunocytochemistry. Paracrine function was determined using enzyme-linked immunosorbent assay method.RESULTS: Our results indicated that the optimum concentration of KSR was 15%, the optimum concentration of B27 was 2%, and the optimum concentration of human AB serum was 10%. fRPE cells cultured in 15% KSR and 2% B27 media showed repressed propagation and differentiation ability, and gradually lost epithelial morphology and RPE function. While fRPE cells cultured in 10% human AB serum media showed a typical cobblestone morphology with pigmentation, elevated proliferation ability, satisfying paracrine function and expressed RPE-specific markers. CONCLUSION: Our study indicates that culturing fRPE cells in 10% human AB serum-supplemented medium is more favorable compared with KSR, B27 and traditional FBS-supplemented mediums when fRPE cells are to be applied in cell-based therapy.

The thickness and volume of the choroid,outer retinal layers and retinal pigment epithelium layer changes in patients with diabetic retinopathy

AIM: To evaluate the thickness and volume changes of the choroidal, outer retinal layers(ORL) and retinal pigment epithelium(RPE) in patients with diabetic retinopathy(DR) using optical coherence tomography(OCT) and correlate them with visual acuity.METHODS: We carried out a retrospective observational case series. Consecutive DR patients were recruited for color fundus photography and OCT assessment. The RPE, ORL and choroidal thickness were measured. The correlation with the best-corrected visual acuity(BCVA) was also investigated.RESULTS: The study included 128 eyes, comprising 45 eyes of 25 diabetic macular edema(DME) patients, 34 eyes of 20 DR without DME(non-DME) patients, and 49 eyes of 25 age-matched normal individuals. The choroidal thickness in DR patients were decreased statistically significantly compared with the control group(P<0.05). The mean macular ORL thickness in DME(73.02±15.34 μm) and non-DME groups(76.35±7.32 μm) were decreased statistically significantly compared with the control group(80.20±5.85 μm; P=0.006, P=0.013, respectively). In both the non-DME and DME groups, the RPE thickness were decreased compared with the control group(P<0.05), except in the macular and central ring. The BCVA were significant interactions with the total inner retinal volume and macular RPE thickness in the DME group(r=0.115, P<0.001, r=-0.013, P=0.017, respectively).CONCLUSION: The choroid, ORL and RPE thickness are significantly decreased in DR patients compared with controls in different segments.

Age-related maculopathy susceptibility 2 participates in the phagocytosis functions of the retinal pigment epithelium

AIM: Age-related macular degeneration (AMD) is a multifactorial disease and a prevalent cause of visual impairment in developed countries. Many studies suggest that age-related maculopathy susceptibility 2 (ARMS2) is a second major susceptibility gene for AMD. At present, there is no functional information on this gene. Therefore, the purpose of the present study was to detect the expression of ARMS2 in retinal pigment epithelium (RPE) cells and to investigate the effect of ARMS2 on the phagocytosis function of RPE cells. METHODS: Immunofluorescence and reverse transcriptase PCR were used to demonstrate the presence and location of ARMS2 in ARPE-19 (human retinal pigment epithelial cell line, ATCC, catalog No.CRL-2302) cells. siRNA was used to knock down ARMS2 mRNA, and the effects of the knockdown on the phagocytosis function of the ARPE-19 cells were evaluated via Fluorescence Activated Cell Sorting (FACS). RESULTS: ARMS2 was present in ARPE-19 cells, localized in the cytosol of the perinuclear region. The expression of ARMS2 mRNA (messenger RNA) in ARPE-19 cells transfected with ARMS2-siRNA (small interfering RNA, 0.73+/- 0.08) was decreased compared with normal cells (1.00+/- 0.00) or with cells transfected with scrambled siRNA (0.95+/- 0.13) (P<0.05). After incubation of RPE cells with a latex beads medium for 12, 18, or 24 hours, the fluorescence intensities were 38.04 +/- 1.02, 68.92 +/- 0.92, and 78.00 +/- 0.12 in the ARMS2-siRNA-transfected groups, respectively, and 77.98 +/- 5.43, 94.87 +/- 0.60, and 98.30 +/- 0.11 in the scrambled siRNA-transfected groups, respectively. The fluorescent intensities of the same time points in the two groups were compared using Student's t-test, and the p values were all less than 0.001 at the three different time points. CONCLUSION: There is endogenous expression of ARMS2 in ARPE-19 cells. ARMS2 plays a role in the phagocytosis function of RPE cells, and this role may be one of the mechanisms that participates in the development of AMD.

Amyloid beta deposition related retinal pigment epithelium cell impairment and subretinal microglia activation in aged APPswePS1 transgenic mice

AIM：To identify the pathological role of amyloid beta（Aβ） deposition in retinal degeneration,and explore Aβ deposition on the retinal pigment epithelium cells（RPE） layer and the associated structural and functional changes in Alzheimer＇s disease transgenic mice.METHODS：RPE changes in the eyes of APPswe/PS1 transgenic and none transgenic（NTG） mice over 20 months old were examined.Histological changes were investigated via hematoxylin and eosin（H＆E） staining and transmission electron microscopy（TEM） examination,whereas the expression of amyloid precursor protein（APP）,Aβ,Zonula occludens-1（ZO-1） and Ionized calcium binding adaptor molecule-1（IBA-1） were investigated using immunohistochemistry and immunofluorescence techniques.All of the obtained results were quantitatively and statistically analyzed.RESULTS：In aged transgenic mice,an APP-positive immunoreaction and Aβ deposition were detected on the RPE layer but were undetectable in NTG mice.The RPE demonstrated some vacuole changes,shortened basal infoldings and basal deposition in histopathological examination and TEM tests,wherein irregular shapes were indicated by ZO-1 disorganization through fluorescence.Furthermore,IBA-1 positive cells were observed to have accumulated and infiltrated into the RPE layer and localized beneath the RPE/Bruch＇s membrane（Br M） complex,which was accompanied by an increase in BrM thickness in aged transgenic mice in comparison to NTG mice.The IBA-1 positive cells were found to be co-stained with Aβ deposition on the RPE flat mounts.CONCLUSION：The observed Aβ deposition in the RPE layer may cause RPE dysfunction,which is associated with microglia cells infiltration into the retina of aged transgenic mice,suggesting that Aβ deposition probably plays a significant role in RPE-related degenerative disease.

Inhibition of cell proliferation,migration and apoptosis in blue-light illuminated human retinal pigment epithelium cells by down-regulation of HtrA1

AIM：To investigate the effect of Htr A1 on the proliferation,migration and apoptosis of human retinal pigment epithelium（RPE） cells in the light injured model,as well as the expression of the apoptosis related molecules.METHODS：The human RPE cell line ARPE-19 was exposed to blue light to establish the light injured model.The cells were transfected with Htr A1 si RNA to knockdown Htr A1 expression.Subsequent expression of Htr A1 was determined by real-time polymerase chain reaction（RTPCR） and Western blot,respectively.Changes in cell proliferation,migration and apoptosis were assessed by cell counting kit-8（CCK-8）,Transwell assay and flow cytometry respectively,as well as changes in the m RNA and protein levels of Bax,Caspase-3 and Bcl-2 expression.RESULTS：Htr A1 was highly expressed in ARPE-19 cells after blue light irradiation.Knockdown of Htr A1 expression inhibited the proliferation,migration and apoptosis of the blue-light-irradiated ARPE-19 cells（P〈0.05）.Bax and Caspase-3 expression were significantly reduced both at m RNA and protein levels（P〈0.05） after si RNA treatment.Bcl-2 expression significantly increased in blue-lightirradiated ARPE-19 cells after si RNA interference（P〈0.05）.CONCLUSION：Silence of Htr A1 may inhibit the proliferation,migration and apoptosis of ARPE-19 cells in light injured model.Moreover,Htr A1 suppression in blue-lightirradiated ARPE-19 cells may ameliorate cell apoptosis through down-regulation of Bax and Caspase-3,and upregulation of Bcl-2 expression.

Melanin change of retinal pigment epithelium and choroid in the convalescent stage of Vogt-Koyanagi-Harada disease

AIM:To observe the melanin change of the retinal pigment epithelium(RPE)and choroid in the convalescent stage of Vogt-Koyanagi-Harada(VKH).METHODS:A retrospective study was performed on 40 eyes of 20 patients in the convalescent stage of VKH.Fundus photography(FP),multi-spectral imaging(MSI),and optical coherence tomography(OCT)were performed.RESULTS:In the VKH convalescent stage,focal RPE melanin accumulation(FRMA)was detected in 34 eyes(85%)on MSI and in 7 eyes(17.5%)on FP.FRMA was limited to the previous retinal detachment area in all 28 eyes(FRMA was detected in 34 eyes on MSI,which were enrolled,and 6 eyes lacked data in the acute stage).Sunset-glow fundus was detected in 20 eyes(50%)on FP.The mean density of FRMA in a 1-mm-diameter circular area of the fovea was 0.04±0.07 on MSI,which was significantly correlated with sunset-glow fundus(ρ=0.467,P=0.02).CONCLUSION:In the VKH convalescent stage,FRMA is derived from the RPE melanin change,and sunset-glow fundus is derived from the choroid melanin change.A higher density of FRMA in the fovea and sunset-glow fundus represents more serious depigmentation of melanin.

Role of glycolysis in retinal vascular endothelium, glia, pigment epithelium, and photoreceptor cells and as therapeutic targets for related retinal diseases

Glycolysis produces large amounts of adenosine triphosphate(ATP)in a short time.The retinal vascular endothelium feeds itself primarily through aerobic glycolysis with less ATP.But when it generates new vessels,aerobic glycolysis provides rapid and abundant ATP support for angiogenesis,and thus inhibition of glycolysis in endothelial cells can be a target for the treatment of neovascularization.Aerobic glycolysis has a protective effect on Müller cells,and it can provide with a target for visual protection and maintenance of the blood-retinal barrier.Under physiological conditions,the mitochondria of RPE can use lactic acid produced by photoreceptor cells as an energy source to provide ATP for survival.In pathological conditions,because RPE cells avoid their oxidative damage by increasing glycolysis,a large number of glycolysis products accumulate,which in turn has a toxic effect on photoreceptor cells.This shows that stabilizing the function of RPE mitochondria may become a target for the treatment of diseases such as retinal degeneration.The decrease of aerobic glycolysis leads to the decline of photoreceptor cell function and impaired vision;therefore,aerobic glycolysis of stable photoreceptor cells provides a reliable target for delaying vision loss.It is of great significance to study the role of glycolysis in various retinal cells for the targeted treatment of ocular fundus diseases.

Chordin-like 2 influences the differentiation fate of retinal pigment epithelium cells by dynamically regulating BMP pathway

AIM:To explore the functions of Chordin-like 2,which is encoded by CHRDL2,in the process of retinal pigmented epithelium(RPE)differentiation and damage repair.METHODS:The fetal RPE cells(f RPE)was obtained from aborted fetus which obeyed medical ethics.Real-time quantitative polymerase chain reaction was used to measure expression quantity of CHRDL2 and other functional genes expression.Knocking down and overexpression was used to analyze the functions about Chordin-like 2.Enzyme-linked immunosorbent assay(ELISA)was used to detect the secretion of bone morphogenetic proteins 4(BMP4).Flow cytometry was used to analyze cell cycle.Cell morphology was observed by phase contrast microscope(PCM).RESULTS:In normal RPE cells,CHRDL2 was firstly upregulated and followed a downregulation but eventually,it was expressed higher than the cells which undergone epithelial-mesenchymal transition(EMT).After knocking down CHRDL2,the secretion of BMP4 was decreased,RPErelated genes(OTX2,MITF,RPE65)were downregulated while EMT-related genes(SNAI1,VIM)were upregulated.However,the expression of these related genes after overexpression of CHRDL2 had contrary results.Chordin-like 2 also regulated the cell cycle by regulating BMP pathway.When CHRDL2 was knocked down,more f RPE cells stayed in S phase of cell cycle,while adding BMP4 reduced the proportion of the cells in S phase.However,overexpression of CHRDL2 increased more BMP4 secretion,this effect decreased the number of cells in S phase,but exogenous BMP inhibitor also could change this effect.At last,in the process of RPE cells differentiation,adding BMP4 at early stage could intervene normal RPE differentiation.Compared with BMP4,inhibiting BMP pathway had no significant negative effect at early stage,but suppressed differentiation at late stage.CONCLUSION:BMP pathway can be activated in a correct temporal order,otherwise,the cells have incorrect differentiation orientation.And Chordin-like 2 plays a role in dynamic regulation of BMP pathway and it also regulates the differentiation of RPE cells.Therefore,this research enlightens a new direction to inhibit EMT and promote cell redifferentiation after injury.

New antioxidant SkQ1 is an effective protector of rat eye retinal pigment epithelium and choroid under conditions of long-term organotypic cultivation

Cells have intrinsic mechanisms for cleaning harmful oxidants represented mainly by reactive oxygen species (ROS). Despite the antioxidant defense, ROS can cause serious damage to the retina that with age leads to various eye diseases and even blindness. Among numerous cell sites of ROS generation, mitochondrial electron transport is of crucial importance. Recently, for the purpose of cleaning ROS in the mitochondrial matrix, powerful mitochondria- targeted antioxidant “SkQ1” has been invented. We studied SkQ1 effects upon tissues of rat posterior eye cup that consisted: retinal pigment epithelium (RPE) ? choroidal coat ? scleral coat. The eye cups were isolated from the eyes of adult albino rats and cultivated in rotary tissue culture system in the presence of 20 nM SkQ1 or without this compound. After 7 days - 1 month in vitro eye cup samples were studied by immunohistochemistry, routine histology, morphometry, and digital image analysis. We have found that under chosen, “in vitro like in vivo” conditions 20 nM SkQ1 effectively reduced cell death in RPE and choroid, protected RPE from disintegration caused by cell phenotypic transformation and withdrawal from the layer, suppressed transmigration of choroidal coat cells. In the ex vivo model we used degenerative processes were more pronounced in the eye cup center where SkQ1 effect was most vivid. All this give us hopes for effectiveness of SkQ1 treatment of retinal central part that is very susceptible to light-induced over-oxidation injury and mostly suffering in many age-related diseases, AMD, in particular.

Application of stem cell-derived retinal pigmented epithelium in retinal degenerative diseases： present and future

As a constituent of blood-retinal barrier and retinal outer segment（ROS） scavenger, retinal pigmented epithelium（RPE） is fundamental to normal function of retina. Malfunctioning of RPE contributes to the onset and advance of retinal degenerative diseases. Up to date, RPE replacement therapy is the only possible method to completely reverse retinal degeneration. Transplantation of human RPE stem cell-derived RPE（h RPESC-RPE） has shown some good results in animal models. With promising results in terms of safety and visual improvement, human embryonic stem cell-derived RPE（h ESC-RPE） can be expected in clinical settings in the near future. Despite twists and turns, induced pluripotent stem cell-derived RPE（i PSC-RPE） is now being intensely investigated to overcome genetic and epigenetic instability. By far, only one patient has received i PSCRPE transplant, which is a hallmark of i PSC technology development. During follow-up, no major complications such as immunogenicity or tumorigenesis have been observed. Future trials should keep focusing on the safety of stem cell-derived RPE（SC-RPE） especially in long period, and better understanding of the nature of stem cell and the molecular events in the process to generate SC-RPE is necessary to the prosperity of SC-RPE clinical application.

Characteristics of normal human retinal pigment epithelium cells with extremes of autofluorescence or intracellular granule count

Background:Cells of the retinal pigment epithelium(RPE)accumulate different kinds of granules(lipofuscin,melanolipofuscin,melanosomes)within their cell bodies,with lipofuscin and melanolipofuscin being autofluorescent after blue light excitation.High amounts of lipofuscin granules within the RPE have been associated with the development of RPE cell death and age-related macular degeneration(AMD);however,this has not been confirmed in histology so far.Here,based on our previous dataset of RPE granule characteristics,we report the characteristics of RPE cells from human donor eyes that show either high or low numbers of intracellular granules or high or low autofluorescence(AF)intensities.Methods:RPE flatmounts of fifteen human donors were examined using high-resolution structured illumination microscopy(HR-SIM)and laser scanning microscopy(LSM).Autofluorescent granules were analyzed regarding AF phenotype and absolute number of granules.In addition,total AF intensity per cell and granule density(number of granules per cell area)were determined.For the final analysis,RPE cells with total granule number below 5th or above the 95th percentile,or a total AF intensity±1.5 standard deviations above or below the mean were included,and compared to the average RPE cell at the same location.Data are presented as mean±standard deviation.Results:Within 420 RPE cells examined,42 cells were further analyzed due to extremes regarding total granule numbers.In addition,20 RPE cells had AF 1.5 standard deviations below,28 RPE cells above the mean local AF intensity.Melanolipofuscin granules predominate in RPE cells with low granule content and low AF intensity.RPE cells with high granule content have nearly twice(1.8 times)as many granules as an average RPE cell.Conclusions:In normal eyes,outliers regarding autofluorescent granule load and AF intensity signals are rare among RPE cells,suggesting that granule deposition and subsequent AF follows intrinsic control mechanisms at a cellular level.The AF of a cell is related to the composition of intracellular granule types.Ongoing studies using AMD donor eyes will examine possible disease related changes in granule distribution and further put lipofuscin´s role in aging and AMD further into perspective.

Pathological,Ultrastructural and Immunohistochemical Observations of Adenoma of Retinal Pigment Epithelium

Purpose: To Study the clinical, pathological, ultrastructural and immunohistchemicalcharacters of adenoma of the retinal pigment epithelium in order to offer evidence todiagnose this tumor.Methods: Routine paraffin slices HE stain, histochemistry PAS and VG stain,transmission electron microscopy, and immunohistochemistry for S-100 and vimentinwith LSAB method were used.Results: The tumor cells were oval and cuboidal in shape. Part of the tumor had atubular arrangement. Around the sheets of tumors cells there was a large amount ofuniform red stick-like substances. The above matter represented positive in PAS stain.Most of the above matter was yellow, while less of the matter showed red in VG stain.Transmission electron microscopy showed that there were tight junctions between tumorcells. Immunohistochemistry showed positive for S-100, negative for vimentin.Conclusions: The ultrastructural and immunohistochemical characters of the adenoma ofretinal pigment epithelium are consistent with the retinal pigment epithelium.