Inhibition of viability of human retinal microvascular endothelial cells by vialinin A under high glucose condition

AIM:To investigate the effects of vialinin A on viability of human retinal endothelial cells(HRECs)under high glucose condition and its potential mechanism.METHODS:The HRECs were divided into four groups:normal glucose control group(NG,5 mmol/L D-glucose),high glucose group(HG,30 mmol/L D-glucose),HG+1μmol/L vialinin A group,and HG+5μmol/L vialinin A group.The cell viabilities were measured with cell counting kit-8(CCK-8)assay for proliferation,with scratch assay for migration,and tube formation,for evaluation of the impact of vialinin A on cellular behaviour.Real-time PCR and Western blotting were used to determine the expression level of vascular endothelial growth factor(VEGF).RESULTS:The proliferative capacity and migration of HRECs was reduced by 5μmol/L vialinin A in high glucose environment(both P<0.05).Vialinin A also inhibited highglucose-induced tube formation of HRECs.The expression level of VEGF and PI3K in HRECs was also significantly decreased by vialinin A(P<0.05).CONCLUSION:Vialinin A inhibits the cell viability of HRECs.It may serve as a potential target for anti-angiogenic therapy.

Anti-vascular endothelial growth factor drugs combined with laser photocoagulation maintain retinal ganglion cell integrity in patients with diabetic macular edema: study protocol for a prospective, non-randomized, controlled clinical trial

The integrity of retinal ganglion cells is tightly associated with diabetic macular degeneration that leads to damage and death of retinal ganglion cells,affecting vision.The major clinical treatments for diabetic macular edema are anti-vascular endothelial growth factor drugs and laser photocoagulation.However,although the macular thickness can be normalized with each of these two therapies used alone,the vision does not improve in many patients.This might result from the incomplete recovery of retinal ganglion cell injury.Therefore,a prospective,non-randomized,controlled clinical trial was designed to investigate the effect of anti-vascular endothelial growth factor drugs combined with laser photocoagulation on the integrity of retinal ganglion cells in patients with diabetic macular edema and its relationship with vision recovery.In this trial,150 patients with diabetic macular edema will be equally divided into three groups according to therapeutic methods,followed by treatment with anti-vascular endothelial growth factor drugs,laser photocoagulation therapy,and their combination.All patients will be followed up for 12 months.The primary outcome measure is retinal ganglion cell-inner plexiform layer thickness at 12 months after treatment.The secondary outcome measures include retinal ganglion cell-inner plexiform layer thickness before and 1,3,6,and 9 months after treatment,retinal nerve fiber layer thickness,best-corrected visual acuity,macular area thickness,and choroidal thickness before and 1,3,6,9,and 12 months after treatment.Safety measure is the incidence of adverse events at 1,3,6,9,and 12 months after treatment.The study protocol hopes to validate the better efficacy and safety of the combined treatment in patients with diabetic macula compared with the other two monotherapies alone during the 12-month follow-up period.The trial is designed to focus on clarifying the time-effect relationship between imaging measures related to the integrity of retinal ganglion cells and best-corrected visual acuity.The trial protocol was approved by the Medical Ethics Committee of the Affiliated Hospital of Beihua University with approval No.(2023)(26)on April 25,2023,and was registered with the Chinese Clinical Trial Registry(registration number:ChiCTR2300072478,June 14,2023,protocol version:2.0).

5-aza-2'-deoxycytidine in the regulation of antioxidant enzymes in retinal endothelial cells and rat diabetic retina

AIM: To investigate the roles of a DNA methyltransferase(DNMT) inhibitor 5-aza-2'-deoxycytidine(5-aza-dC) in the regulation of antioxidant enzymes in diabetic retinopathy(DR) models. METHODS: DNMTs expressions and activity, and changes of two key antioxidant enzymes in DR, MnSOD(encoded by SOD2 gene) and glutathione S-transferase theta 1(GSTT1), were quantified in the isolated human retinal endothelial cells(HRECs) exposed to high glucose(HG) with or without 5-aza-dC treatment. The downstream exacerbating factors including vascular endothelial growth factor(VEGF), intercellular adhesion molecule 1(ICAM-1) and matrix metalloproteinase 2(MMP2), which are implicated in the pathogenesis of DR and closely related to oxidative stress were also analyzed. The key parameters were confirmed in the retina from streptozotocin(STZ) diabetic rats. RESULTS: DNMTs expression and DNMT activity was induced in HRECs exposed to HG. Hyperglycemia decreased MnSOD and GSTT1 expression. 5-aza-dC administration effectively suppressed DNMTs expression and activity and reversed the MnSOD and GSTT1 expression under HG condition. VEGF, ICAM-1 and MMP2 induced by HG were also suppressed by 5-aza-dC treatment. Similar results were observed in the retina from STZ diabetic rats. CONCLUSION: Our findings suggest that DNA methylation may serves as one of the mechanisms of antioxidant defense system disruption in DR progression. Modulation of DNA methylation using pharmaceutic means such as DNMT inhibitors could help maintain redox homeostasis and prevent further progression of DR.

Small interfering RNA targeting PGC-1α inhibits VEGF expression and tube formation in human retinal vascular endothelial cells

AIMTo determine whether small interfering RNA (siRNA) of PGC-1α could inhibit vascular endothelial growth factor (VEGF) expression and tube formation in human retinal vascular endothelial cells (hRVECs).METHODShRVECs transfected with peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) siRNA were incubated for 24h and then placed into a normoxic (20%, O2) or hypoxic (1%, O2) environment for another 16h. PGC-1α mRNA and protein levels were detected by real-time PCR and Western blot. VEGF mRNA and protein levels were detected by real-time PCR and ELISA. Cell proliferation was evaluated by BrdU incorporation assay. Forty-eight hours after siRNA transfection, hRVECs were planted into Matrigel-coated plates and cultured under normoxic (20%, O2) or hypoxic (1%, O2) conditions for another 48h. The tube formation of hRVECs was observed under an optical microscope and quantified by counting the number of branch points and calculating the total tube length.RESULTSPGC-1α mRNA and protein levels were significantly reduced by PGC-1α siRNA, and VEGF mRNA and protein levels also decreased significantly. The percentage of BrdU-labeled cells in siPGC-1α groups were significantly decreased compared with control siRNA groups under normoxia and hypoxia in cell proliferation assay. In the tube formation assay, PGC-1α siRNA treated cells formed significantly fewer tubes.CONCLUSIONBlocking PGC-1α expression can inhibit VEGF expression in hRVECs and inhibit their ability to form tubes under both normoxic and hypoxic conditions.

Repression of retinal microvascular endothelial cells by transthyretin under simulated diabetic retinopathy conditions

AIM： To investigate biological effects of transthyretin （TTR） on the development of neovascularization under simulated diabetic retinopathy （DR） condition associated with high glucose and hypoxia. METHODS： Human retinal microvascular endothelial cells （hRECs） were cultured in normal and simulated DR environments with high glucose and hypoxia. The normal serum glucose concentration is approximately 5.5 mmol/L; thus, hyperglycemia was simulated with 25 mmol/L glucose, while hypoxia was induced using 200 μmol/L CoCI. The influence of TTR on hRECs and human retinal pigment epithelial cells （hRPECs） was determined by incubating the cells with 4μmol/L TTR in normal and abnormal media. A co -culture system was then employed to evaluate the effects of hRPECs on hRECs. RESULTS： Decreased hRECs and hRPECs were observed under abnormal conditions, including high- glucose and hypoxic media. In addition, hRECs were significantly inhibited by 4 pmol/L exogenous TTR during hyperglycemic culture. During co-culture, hRPECs inhibited hRECs in both the normal and abnormal environments. CONCLUSION： hREC growth is inhibited by exogenous TTR under simulated DR environments with highglucose and hypoxic, particularly in the medium containing 25 mmol/L glucose, hRPECs, which manufacture TTR in the eye, also represses hRECs in the same environment. TTR is predicted to inhibit the proliferation of hRECs and neovascularization.

Inhibition of proliferation of retinal vascular endothelial cells more effectively than choroidal vascular endothelial cell proliferation by bevacizumab

AIM： To evaluate the differential inhibitory effects of bevacizumab on cell proliferation of vascular endothelial growth factor （VEGF）-stimulated choroidal vascular endothelial cells （CVECs） and retinal vascular endothelial cells （RVECs） in vitro.METHODS： VEGF （400 ng/mL） enriched CVECs and RVECs were treated with escalating doses of bevacizumab （0.1, 0.5, 1, 1.5 and 2 mg/mL）. Cell proliferation changes were analyzed with WST-1 assay and trypan blue exclusion assay at 48, 72h and 1wk. Morphological changes were recorded with bright field microscopy.RESULTS： VEGF enriched RVECs showed significantly more decline of cell viability than CVECs after bevacizumab treatment. One week after treatment, RVEC cell proliferation decreased by 29.7%, 37.5%, 52.8%, 35.9% and 45.6% at 0.1, 0.5, 1.0, 1.5 and 2 mg/mL bevacizumab respectively compared to CVEC proliferation decrease of 4.1%, 7.7%, 2.4%, 4.1% and 17.7% （P〈0.05） by WST-1 assay. Trypan blue exclusion assay also revealed similar decrease in RVEC proliferation of 20%, 60%, 73.3%, 80% and 93.3% compared to CVEC proliferation decrease of 4%, 12%, 22.9%, 16.7% and 22.2% respectively （P〈0.05）. The maximum differential effect between the two cell types was observed at bevacizumab doses of 1.0 and 1.5 mg/mL at all time points. RVECs were 22 fold more sensitive （P〈0.01） compared to CVECs （52.8% vs 2.4%） at concentration of 1.0 mg/mL, and 8.7 fold more at 1.5 mg/mL （35.9% vs 4.1%） 1wk after treatment （P〈0.05 respectively）.CONCLUSION： VEGF-enriched RVECs are more susceptible to bevacizumab inhibition than CVECs at clinically used dosage of 1.25 mg and this differential sensitivity between two cell types should be taken into consideration in dosage selection.

Adenoviral 15-lipoxygenase-1 gene transfer inhibits hypoxia-induced proliferation of retinal microvascular endothelial cells in vitro

AIM: To investigate whether 15-Lipoxygenase-1 (15-LOX-1) plays an important role in the regulation of angiogenesis, inhibiting hypoxia-induced proliferation of retinal microvascular endothelial cells (RMVECs) and the underlying mechanism. METHODS: Primary RMVECs were isolated from the retinas of C57/BL63 mice and identified by an evaluation for FITC-marked CD31. The hypoxia models were established with the Bio-bag and evaluated with a blood-gas analyzer. Experiments were performed using RMVECs treated with and without transfer. Ad-15-LOX-1 or Ad-vector both under hypoxia and normoxia condition at 12, 24, 48, 72 hours. The efficacy of the gene transfer was assessed by immunofluorescence staining. Cells proliferation was evaluated by the CCK-8 method. RNA and protein expressions of 15-LOX-1, VEGF-A, VEGFR-2, eNOs and PPAR-r were analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blot. RESULTS: Routine evaluation for FITC-marked CD31 showed that cells were pure. The results of blood-gas analysis showed that when the cultures were exposed to hypoxia for more than 2 hours, the Po2 was 4.5 to 5.4 Kpa. We verified RMVECs could be infected with Ad-LS-LOX-for Ad-vectorvia Fluorescence microscopy. CCK-8 analysis revealed that the proliferative capacities of RMVECs in hypoxic group were significantly higher at each time point than they were in normoxic group (P <0.05). In a hypoxic condition, the proliferative capacities of RMVECs in 15-LOX-1 group were significantly inhibited (P<0.05). Real-time RT-PCR analysis revealed that the expressions of VEGF-A, VEGF-R2 and eNOs mRNA increased in hypoxia group compared with normoxia group (P<0.01). However, the expressions of 15-LOX-1, PPAR-r mRNA decreased in hypoxia group compared with normoxia group (P<0.01). It also showed that in a hypoxic condition, the expressions of VEGF-A, VEGF-R2 and eNOs mRNA decreased significantly in 15-LOX-1 group compared with hypoxia group (P<0.01). However, 15-LOX-1 and PPAR-r mRNA increased significantly in 15-LOX-1 group compared with hypoxia group (P<0.01). There was no significant difference of the mRNA expressions between vector group and hypoxia group (P>0.05). Western blot analysis revealed that the expressions of relative proteins were also ranked in that order. CONCLUSION: Our results suggested that 15-LOX-1 and PPAR-r might act as a negative regulator of retinal angiogenesis. And the effect of 15-LOX-1 overexpression is an anti-angiogenic factor in hypoxia-induced retinal neovascularization (RNV). Overexpression 15-LOX-1 on RMVECs of hypoxia-induced RNV blocked signaling cascades by inhibiting hypoxia-induced increases in VEGF family. PPAR-r effect on VEGFR(2) could be an additional mechanism whereby 15-LOX-1 inhibited the hypoxia-induced RNV.

Autophagy activation and the mechanism of retinal microvascular endothelial cells in hypoxia

AIM： To explore the state of autophagy and related mechanisms in the murine retinal microvascular endothelial cells（RMECs） under hypoxia stimulation.METHODS： The murine RMECs were primarily cultured and randomly divided into three groups： hypoxia group（cultured in 1% O_2 environment）, hypoxia＋autophagy inhibition group [pretreated with 5 mmol/L 3-methyladenine（3-MA） for 4 h followed by incubation in 1% O_2] and control group（cultured under normoxic condition）. The state of autophagy in RMECs was examined by assaying the turnover of light chain 3 B（LC3BB） and expression of Beclin-1, Atg3 and Atg5 proteins with Western blotting, by detecting formation of autophagosomes with transmission electron microscopy（TEM） and by counting the number of GFP＋ puncta in RMECs. The protein levels of AMPK, P-AMPK, Akt, P-Akt, m-TOR and P-m TOR were also assayed by Western blotting.RESULTS： Primary murine RMECs were successfully cultured. Under hypoxic conditions, the ratio of LC3BB-Ⅱ/Ⅰ and the expression of Beclin-1, Atg3 and Atg5 proteins were increased when compared with the control group. In addition, the numbers of autophagosome and the GFP＋ puncta were also increased under hypoxia. However, pretreatment with 3-MA obviously attenuated these changes in autophagy in RMECs under hypoxia. Protein expression of P-Akt and P-AMPK was increased but P-m TOR level was decreased in cells exposed to hypoxia. CONCLUSION： In murine RMECs autophagy is activated under hypoxia possibly through activation of the AMPK/mTOR signaling pathway.

Epigallocatechin-3-gallate attenuates lipopolysaccharideinduced inflammation in human retinal endothelial cells

AIM:To investigate the mechanism underlying the anti-inflammatory effects of epigallocatechin-3-gallate(EGCG)in lipopolysaccharide(LPS)-stimulated human retinal endothelial cells(HRECs).METHODS:HRECspre-treatedwithEGCG(0-100μmol/L)were stimulated with LPS(250 ng/mL).Levels of tumor necrosis factor alpha(TNF-α),vascular endothelial growth factor(VEGF),monocyte chemotactic protein-1(MCP-1)and nitric oxide(NO)in the supernatants were determined by enzyme-linked immunosorbent assay(ELISA)and Griess assay.The protein expression of phosphorylated extracellular signal-regulated kinase(ERK)1/2 and p38 mitogen-activated protein kinases(p38)were determined by Western blot analysis.RESULTS:EGCG pre-treatment significantly inhibited the secretion of TNF-α,VEGF,MCP-1 and NO in LPSstimulated HRECs.Moreover,EGCG effectively attenuated LPS-induced activation and phosphorylation of ERK1/2 and p38 in HRECs in a dose-dependent manner.CONCLUSION:EGCG exhibited inhibitory effects on LPS-induced pro-inflammatory cytokines production by modulating ERK1/2 and p38 pathways in HRECs,suggesting EGCG as a potential candidate for antiinflammatory intervention.

Mesenchymal stem cell-derived exosomes inhibit the VEGF-A expression in human retinal vascular endothelial cells induced by high glucose

AIM:To determine the effect of exosomes derived from human umbilical cord blood mesenchymal stem cells(hUCMSCs)on the expression of vascular endothelial growth factor A(VEGF-A)in human retinal vascular endothelial cells(HRECs).METHODS:Exosomes were isolated from hUCMSCs using cryogenic ultracentrifugation and characterized by transmission electron microscopy,Western blotting and nanoparticle tracking analysis.HRECs were randomly divided into a normal control group(group A),a high glucose model group(group B),a high glucose group with 25μg/mL(group C),50μg/mL(group D),and 100μg/mL exosomes(group E).Twenty-four hours after coculture,the cell proliferation rate was detected using flow cytometry,and the VEGF-A level was detected using immunofluorescence.After coculture 8,16,and 24h,the expression levels of VEGF-A in each group were detected using PCR and Western blots.RESULTS:The characteristic morphology(membrane structured vesicles)and size(diameter between 50 and 200 nm)were observed under transmission electron microscopy.The average diameter of 122.7 nm was discovered by nanoparticle tracking analysis(NTA).The exosomal markers CD9,CD63,and HSP70 were strongly detected.The proliferation rate of the cells in group B increased after 24h of coculture.Immunofluorescence analyses revealed that the upregulation of VEGF-A expression in HRECs stimulated by high glucose could be downregulated by cocultured hUCMSC-derived exosomes(F=39.03,P<0.01).The upregulation of VEGF-A protein(group C:F=7.96;group D:F=17.29;group E:F=11.89;8h:F=9.45;16h:F=12.86;24h:F=42.28,P<0.05)and mRNA(group C:F=4.137;group D:F=13.64;group E:F=22.19;8h:F=7.253;16h:F=16.98;24h:F=22.62,P<0.05)in HRECs stimulated by high glucose was downregulated by cocultured hUCMSC-derived exosomes(P<0.05).CONCLUSION:hUCMSC-derived exosomes downregulate VEGF-A expression in HRECs stimulated by high glucose in time and concentration dependent manner.

Role of apigenin in high glucose-induced retinal microvascular endothelial cell dysfunction via regulating NOX4/p38 MAPK pathway in vitro

AIM:To investigate the retinoprotective role of Apigenin(Api)against high glucose(HG)-induced human retinal microvascular endothelial cells(HRMECs),and to explore its regulatory mechanism.METHODS:HRMECs were stimulated by HG for 48h to establish the in vitro cell model.Different concentrations of Api(2.5,5,and 10μmol/L)were applied for treatment.Cell counting kit-8(CCK-8),Transwell,and tube formation assays were performed to examine the effects of Api on the viability,migration,and angiogenesis in HG-induced HRMECs.Vascular permeability was evaluated by Evans blue dye.The inflammatory cytokines and oxidative stress-related factors were measured using their commercial kits.Protein expression of nicotinamide adenine dinucleotide phosphate(NADPH)oxidase 4(NOX4)and p38 mitogen-activated protein kinase(MAPK)was measured by Western blot.RESULTS:Api prevented HG-induced HRMECs viability,migration,angiogenesis,and vascular permeability in a concentration-dependent manner.Meanwhile,Api also concentration-dependently inhibited inflammation and oxidative stress in HRMECs exposed to HG.In addition,HG caused an elevated expression of NOX4,which was retarded by Api treatment.HG stimulation facilitated the activation of p38 MAPK signaling in HRMECs,and Api could weaken this activation partly via downregulating NOX4 expression.Furthermore,overexpression of NOX4 or activation of p38 MAPK signaling greatly weakened the protective role of Api against HG-stimulated HRMECs.CONCLUSION:Api might exert a beneficial role in HGstimulated HRMECs through regulating NOX4/p38 MAPK pathway.

Effects of LY294002 on the function of retinal endothelial cell in vitro

AIM： To study the effects of LY294002 [phosphatidylinositol 3-kinase（PI3K） inhibitor] on the function and mechanisms of retinal endothelial cells（RECs） in vitro.METHODS： RECs were randomly divided into control group and LY294002 treatment group. RECs in the control group were placed the incubator for hypoxic exposure in vitro. RECs in the LY294002 treatment group were pretreated with LY294002（40 μmol/L） under hypoxic condition. The expression of matrix metalloproteinase（MMP）-2, MMP-9, vascular endothelial growth factor（VEGF）, and apoptosis and proliferation of RECs were evaluated with Western blot, real-time reverse transcription-polymerase chain reaction（RT-PCR）, and flow cytometric analysis, correspondently.RESULTS： Compared with the control group, treating the RECs with LY294002 was able to remarkably inhibit cell proliferation rates（t_（1d）=2.13, t_（2d）=2.65, t_（3d）=2.36, t_（4d）=2.06, all P〈0.05）. Flow cytometric analysis indicated that a moderate increase in apoptosis in the LY294002 treatment group compared to the control group（t=2.51, P〈0.05）. The expression of MMP-2, MMP-9 and VEGF were downregulated in the LY294002 treatment group by Western blot and real-time RT-PCR（all P〈0.05）.CONCLUSION： LY294002 regulates the function of RECs by reducing the expression of MMP-2, MMP-9, and VEGF in vitro. LY294002 may provide an effective method for preventing pathological angiogenesis.

Inhibition of VEGF-A expression in hypoxia-exposed fetal retinal microvascular endothelial cells by exosomes derived from human umbilical cord mesenchymal stem cells

Objective:This study aimed to investigate the potential of human umbilical cord mesenchymal stem cell(hucMSC)-derived exosomes(hucMSC-Exos)in inhibiting hypoxia-induced cell hyper proliferation and overexpression of vascular endothelial growth factor A(VEGF-A)in immature human fetal retinal microvascular endothelial cells(hfRMECs).Methods:Exosomes were isolated from hucMSCs using cryogenic ultracentrifugation and characterized through various techniques,including transmission electron microscopy,nanoparticle tracking analysis,bicinchoninic acid assays,and western blotting.The hfRMECs were identified using von Willebrand factor(vWF)co-staining and divided into four groups:a control group cultured under normoxic condition,a hypoxic model group,a hypoxic group treated with low-concentration hucMSC-Exos(75μg/mL)and a hypoxic group treated with high-concentration hucMSC-Exos(100μg/mL).Cell viability and proliferation were assessed using Cell Counting Kit-8(CCK-8)assay and EdU(5-ethynyl-2′-deoxyuridine)assay respectively.Expression levels of VEGF-A were evaluated using RT-PCR,western blotting and immunofluorescence.Results:Hypoxia significantly increased hfRMECs’viability and proliferation by upregulating VEGF-A levels.The administration of hucMSC-Exos effectively reversed this response,with the high-concentration group exhibiting greater efficacy compared to the lowconcentration group.Conclusion:In conclusion,hucMSC-Exos can dose-dependently inhibit hypoxia-induced hyperproliferation and VEGF-A overexpression in immature fetal retinal microvascular endothelial cells.

Regulation of opticin on bioactivity of retinal vascular endothelial cells cultured in collagen

AIM:To investigate the effects of collagen and opticin on the bioactivity of human retinal vascular endothelial cells(hR VECs),and explore its regulations by integrins and RhoA/ROCK1 signal pathway.METHODS:h RVECs were cultured in collagen and treated by opticin,and cell-based bioactivity assays of cell proliferation,migration,and adhesion were performed.The expression of integrinα2,integrinβ1,Rho A and ROCK1 were examined with real-time PCR and Western blotting.RESULTS:Collagen could promote cell viability of proliferation and migration(all P<0.05),and enhance the m RNA expression of integrinα2,integrinβ1,Rho A and ROCK1(all P<0.05).Opticin could inhibit proliferation and migration ability of hR VECs cultured in collagen,and reduce the mR NA expression of integrinα2,integrinβ1,RhoA and ROCK1(all P<0.05).CONCLUSION:Collagen and opticin can affect bioactivity of hR VECs,which may be regulated byα2-,β1-integrins and RhoA/ROCK1 signal pathway.

Down-regulation of histone deacetylase 7 reduces biological activities of retinal microvascular endothelial cells under high glucose condition and related mechanism

AIM:To investigate the expression and effect of histone deacetylase 7(HDAC7)in human retinal microvascular endothelial cells(HRMECs)under high glucose condition and related mechanism,and the expression of HDAC7 in the retinal tissue in diabetic rats.METHODS:The expression of HDAC7 in HRMECs under high glucose and the retinal tissue from normal or diabetic rats were detected with immunohistochemistry and Western blot.LV-shHDAC7 HRMECs were used to study the effect of HDAC7 on cell activities.Cell count kit-8(CCK-8),5-ethynyl2’-deoxyuridine(EdU),flow cytometry,scratch test,Transwell test and tube formation assay were used to examine the ability of cell proliferation,migration,and angiogenesis.Finally,a preliminary exploration of its mechanism was performed by Western blot.RESULTS:The expression of HDAC7 was both upregulated in retinal tissues of diabetic rats and high glucosetreated HRMECs.Down-regulation of HDAC7 expression significantly reduced the ability of proliferation,migration,and tube formation,and reversed the high glucose-induced high expression of CDK1/Cyclin B1 and vascular endothelial growth factor in high glucose-treated HRMECs.CONCLUSION:High glucose can up-regulate the expression of HDAC7 in HRMECs.Down-regulation of HDAC7 can inhibit HRMECs activities.HDAC7 is proposed to be involved in pathogenesis of diabetic retinopathy and a therapeutic target.

miRNA-451 regulates rhesus choroid-retinal endothelial cell function and proteome profile

AIM:To evaluate the effect of miRNA-451 on rhesus macaque choroid-retinal endothelial(RF/6A)cell function and proteome profile.METHODS:The RF/6A cells were transfected with miRNA-451 mimic and inhibitor.The role of miRNA-451 on proliferation ability was evaluated by CCK-8 assay.Furthermore,iTRAQ quantitative proteomic analysis was applied to comprehensively illuminate the change of cellular proteins and biological function between different groups.RESULTS:In miRNA-451 overexpression group,cell proliferation of RF/6A decreased both at 24 h and 48 h;while in miRNA-451 inhibition group,on the contrary,RF/6A cell proliferation was increased at 48 h.Based on iTRAQ quantitative proteomic analysis,23 differentially expressed proteins(DEPs)were detected in the comparison of miRNA-451 mimic and mimic control-transfected RF/6A cells,and 30 DEPs were identified in the comparison of RF/6A cells transfected with miRNA-451 inhibitor and inhibitor control.DEPs such as GORASP2,KRT1,SLC7 A2,RIC8 A,DDX42,CAP1,PCBP2 might be closely related to the inhibitory effect of miRNA-451 on RF/6A cell proliferation,while PCYT1 A,MGAT1,TUBB,MCU,SIL1,BID,MSH6 might account for the positive effect of miRNA-451 inhibitor on RF/6A cell growth.PTPN1,as the only protein exhibiting an opposite trend between miRNA-451 mimic and inhibitortransfected cells,was most likely accountable for the inhibition of miRNA-451 mimic on RF/6A cell growth,and the promotion of miRNA-451 inhibitor on RF/6A cell proliferation.CONCLUSION:miRNA-451 overexpression can suppress the growth of RF/6A cells while knockdown of miRNA-451 can promote RF/6A cell viability.Among all DEPs,increased PTPN1 is most likely to account for the negative regulation of miRNA-451 on RF/6A proliferation.miRNA-451 can be a protective factor for neovascular disease of fundus via regulating choroid retinal endothelial cell function.

Trimethylamine N-oxide aggravates vascular permeability and endothelial cell dysfunction under diabetic condition:in vitro and in vivo study

AIM:To provide the direct evidence for the crucial role of trimethylamine N-oxide(TMAO)in vascular permeability and endothelial cell dysfunction under diabetic condition.METHODS:The role of TMAO on the in vitro biological effect of human retinal microvascular endothelial cells(HRMEC)under high glucose conditions was tested by a cell counting kit,wound healing,a transwell and a tube formation assay.The inflammation-related gene expression affected by TMAO was tested by real-time polymerase chain reaction(RT-PCR).The expression of the cell junction was measured by Western blotting(WB)and immunofluorescence staining.In addition,two groups of rat models,diabetic and non-diabetic,were fed with normal or 0.1%TMAO for 16wk,and their plasma levels of TMAO,vascular endothelial growth factor(VEGF),interleukin(IL)-6 and tumor necrosis factor(TNF)-αwere tested.The vascular permeability of rat retinas was measured using FITC-Dextran,and the expression of zonula occludens(ZO)-1 and claudin-5 in rat retinas was detected by WB or immunofluorescence staining.RESULTS:TMAO administration significantly increased the cell proliferation,migration,and tube formation of primary HRMEC either in normal or high-glucose conditions.RT-PCR showed elevated inflammation-related gene expression of HRMEC under TMAO stimulation,while WB or immunofluorescence staining indicated decreased cell junction ZO-1 and occludin expression after high-glucose and TMAO treatment.Diabetic rats showed higher plasma levels of TMAO as well as retinal vascular leakage,which were even higher in TMAO-feeding diabetic rats.Furthermore,TMAO administration increased the rat plasma levels of VEGF,IL-6 and TNF-αwhile decreasing the retinal expression levels of ZO-1 and claudin-5.CONCLUSION:TMAO enhances the proliferation,migration,and tube formation of HRMEC,as well as destroys their vascular integrity and tight connection.It also regulates the expression of VEGF,IL-6,and TNF-α.

Knockdown of fibrillin-1 suppresses retina-blood barrier dysfunction by inhibiting vascular endothelial apoptosis under diabetic conditions

AIM:To investigate the effects of fibrillin-1(FBN1)deletion on the integrity of retina-blood barrier function and the apoptosis of vascular endothelial cells under diabetic conditions.METHODS:Streptozotocin(STZ)-induced diabetic mice were used to simulate the diabetic conditions of diabetic retinopathy(DR)patients,and FBN1 expression was detected in retinas from STZ-diabetic mice and controls.In the Gene Expression Omnibus(GEO)database,the GSE60436 dataset was selected to analyze FBN1 expressions in fibrovascular membranes from DR patients.Using lentivirus to knock down FBN1 levels,vascular leakage and endothelial barrier integrity were detected by Evans blue vascular permeability assay,fluorescein fundus angiography(FFA)and immunofluorescence labeled with tight junction marker in vivo.High glucose-induced monkey retinal vascular endothelial cells(RF/6A)were used to investigate effects of FBN1 on the cells in vitro.The vascular endothelial barrier integrity and apoptosis were detected by trans-endothelial electrical resistance(TEER)assay and flow cytometry,respectively.RESULTS:FBN1 mRNA expression was increased in retinas of STZ-induced diabetic mice and fibrovascular membranes of DR patients(GSE60436 datasets)using RNA-seq approach.Besides,knocking down of FBN1 by lentivirus intravitreal injection significantly inhibited the vascular leakage compared to STZ-DR group by Evans blue vascular permeability assay and FFA detection.Expressions of tight junction markers in STZ-DR mouse retinas were lower than those in the control group,and knocking down of FBN1 increased the tight junction levels.In vitro,30 mmol/L glucose could significantly inhibit viability of RF/6A cells,and FBN1 mRNA expression was increased under 30 mmol/L glucose stimulation.Down-regulation of FBN1 reduced high glucose(HG)-stimulated retinal microvascular endothelial cell permeability,increased TEER,and inhibited RF/6A cell apoptosis in vitro.CONCLUSION:The expression level of FBN1 increases in retinas and vascular endothelial cells under diabetic conditions.Down-regulation of FBN1 protects the retina of early diabetic rats from retina-blood barrier damage,reduce vascular leakage,cell apoptosis,and maintain vascular endothelial cell barrier function.

Human umbilical cord mesenchymal stem cells derivedexosomes on VEGF-A in hypoxic-induced mice retinal astrocytes and mice model of retinopathy of prematurity

AIM:To observe the effect of human umbilical cord mesenchymal stem cells(hUCMSCs)secretions on the relevant factors in mouse retinal astrocytes,and to investigate the effect of hUCMSCs on the expression of vascular endothelial growth factor-A(VEGF-A)and to observe the therapeutic effect on the mouse model of retinopathy of prematurity(ROP).METHODS:Cultured hUCMSCs and extracted exosomes from them and then retinal astrocytes were divided into control group and hypoxia group.MTT assay,flow cytometry,reverse transcription-polymerase chain reaction(RT-PCR)and Western blot were used to detect related indicators.Possible mechanisms by which hUCMSCs exosomes affect VEGF-A expression in hypoxia-induced mouse retinal astrocytes were explored.At last,the efficacy of exosomes of UCMSCs in a mouse ROP model was explored.Graphpad6 was used to comprehensively process data information.RESULTS:The secretion was successfully extracted from the culture supernatant of hUCMSCs by gradient ultracentrifugation.Reactive oxygen species(ROS)and hypoxia inducible factor-1α(HIF-1α)of mice retinal astrocytes under different hypoxia time and the expression level of VEGF-A protein and VEGF-A mRNA increased,and the ROP cell model was established after 6h of hypoxia.The secretions of medium and high concentrations of hUCMSCs can reduce ROS and HIF-1α,the expression levels of VEGF-A protein and VEGF-A mRNA are statistically significant and concentration dependent.Compared with the ROP cell model group,the expression of phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/mammalian target of rapamycin(mTOR)signal pathway related factors in the hUCMSCs exocrine group is significantly decreased.The intravitreal injection of the secretions of medium and high concentrations of hUCMSCs can reduce VEGF-A and HIF-1αin ROP model tissues.HE staining shows that the number of retinal neovascularization in ROP mice decreases with the increase of the dose of hUCMSCs secretion.CONCLUSION:In a hypoxia induced mouse retinal astrocyte model,hUCMSCs exosomes are found to effectively reduce the expression of HIF-1αand VEGF-A,which are positively correlated with the concentration of hUCMSCs exosomes.HUCMSCs exosomes can effectively reduce the number of retinal neovascularization and the expression of HIF-1αand VEGF-A proteins in ROP mice,and are positively correlated with drug dosage.Besides,they can reduce the related factors on the PI3K/AKT/mTOR signaling pathway.

Mechanism of piR-1245/PIWI-like protein-2 regulating Janus kinase-2/signal transducer and activator of transcription-3/vascular endothelial growth factor signaling pathway in retinal neovascularization

Inhibiting retinal neovascularization is the optimal strategy for the treatment of retina-related diseases, but there is currently no effective treatment for retinal neovascularization. P-element-induced wimpy testis(PIWI)-interacting RNA(piRNA) is a type of small non-coding RNA implicated in a variety of diseases. In this study, we found that the expression of piR-1245 and the interacting protein PIWIL2 were remarkably increased in human retinal endothelial cells cultured in a hypoxic environment, and cell apoptosis, migration, tube formation and proliferation were remarkably enhanced in these cells. Knocking down piR-1245 inhibited the above phenomena. After intervention by a p-JAK2 activator, piR-1245 decreased the expression of hypoxia inducible factor-1α and vascular endothelial growth factor through the JAK2/STAT3 pathway. For in vivo analysis, 7-day-old newborn mice were raised in 75 ± 2% hyperoxia for 5 days and then piR-1245 in the retina was knocked down. In these mice, the number of newly formed vessels in the retina was decreased, the expressions of inflammationrelated proteins were reduced, the number of apoptotic cells in the retina was decreased, the JAK2/STAT3 pathway was inhibited, and the expressions of hypoxia inducible factor-1α and vascular endothelial growth factor were decreased. Injection of the JAK2 inhibitor JAK2/TYK2-IN-1 into the vitreous cavity inhibited retinal neovascularization in mice and reduced expression of hypoxia inducible factor-1α and vascular endothelial growth factor. These findings suggest that piR-1245 activates the JAK2/STAT3 pathway, regulates the expression of hypoxia inducible factor-1α and vascular endothelial growth factor, and promotes retinal neovascularization. Therefore, piR-1245 may be a new therapeutic target for retinal neovascularization.