Proliferative vitreoretinopathy and its relationship with inflammatory serum biomarkers

AIM:To analyze if a relationship between levels ofinflammatory serum biomarkers and severity of primaryproliferative vitreoretinopathy(PVR)exists.METHODS:A retrospective case-control study.Thehealthy adult patients with rhegmatogenous retinaldetachment and primary PVR were included in the PVRgroup.For the control group,healthy adults who underwentcataract surgery were included.The grade of PVR wasclassified according to the Retinal Society TerminologyCommittee.Blood samples were obtained before surgery,and processed in MYTHIC 18.Measures of interest wereneutrophil-to-lymphocyte ratio(NLR),platelet-to-lymphocyteratio(PLR),and lymphocyte-to-monocyte ratio(LMR),thetime between the decrease in visual acuity and surgery,PVRgrade,type of surgery,final best corrected visual acuity,andrate of re-detachment.RESULTS:Totally 240 patients were included,120 ineach group,79(65.8%)and 56(46.7%)were male in thePVR and control group,respectively.PVR A had greaterlevels of monocytes(0.28±0.18 vs 0.12±0.32,P=0.002),neutrophils(4.59±1.51 vs 3.92±1.27,P=0.006),and LMR(9.32±4.42 vs 7.43±3.90,P=0.01).PVR B had a greatermonocyte count(0.30±0.13 vs 0.12±0.32,P=0.001),andPVR C demonstrated higher levels in monocytes(0.27±0.12vs 0.12±0.32,P=0.004),neutrophils(4.39±1.13 vs3.92±1.27,P=0.004),and LMR(9.63±3.24 vs 7.43±3.90,P=0.002)compared to control,respectively.An LMR cut-offvalue of 9.38 predicted PVR with a sensibility of 54.2%andspecificity of 77.5%and NLR cut-off of 1.70 predicted PVRwith a sensibility of 62%and specificity of 54.2%.CONCLUSION:Patients with primary PVR demonstrategreater neutrophil,monocyte,and LMR levels than thecontrol group.Cut-off values obtained from ratios could beuseful in a clinical setting when no posterior view of thefundus is possible due to media opacity.

Effect of etanercept on post-traumatic proliferative vitreoretinopathy

AIM: To evaluate the safety and efficacy of intravitreal etanercept in the inhibiting of proliferative vitreoretinopathy(PVR) in a model of penetrating ocular injury. METHODS: Penetrating ocular injury on the retina of rabbit was induced, which was subsequently treated using 0.1 mL of sterile water or 0.1 m L of 12.5 mg/mL etanercept. The development of PVR was evaluated by fundus images, the B-scan, and the histopathology. The mRNA and protein expressions of tumor necrosis factor-α(TNF-α), transforming growth factor β(TGF-β) as well as connective tissue growth factor(CTGF) were examined at various time points after the etanercept injection with the reverse transcriptase-polymerase chain reaction(RT-PCR) and Western blotting, respectively. The safety of etanercept was evaluated by injection of 12.5 mg/mL etanercept into a normal rabbit eye without penetrating trauma. RESULTS: Clinical assessment and grading clearly demonstrated that the PVR formation was prevented in etanercept-treated animals, which was confirmed via fundus images, B-scan and histopathology. The RT-PCR and Western blotting showed increased mRNA and protein expression of TNF-α, TGF-β as well as CTGF in the retina of rabbits following penetrating ocular injury, and these factors were dramatically mitigated by ocular etanercept treatment. In addition, there was no adverse effect of etanercept intravitreal injection in normal eyes without penetrating trauma, it showed normal structure and histology. CONCLUSION: The etanercept is a potential therapy for inhibiting PVR development. To assess the clinic application of the etanercept in preventing PVR, further clinical studies are required.

The role of intravitreal ranubizumab in the treatment of familial exudative vitreoretinopathy of stage 2 or greater

AIM： To evaluate the role of intravitreal ranubizumab （IVR） in the treatment of familial exudative vitreoretinopathy （FEVR） of stage 2 or greater either as primary or an ajunct to conventional treatments. METHODS： Retrospective, non-controlled clinical study. Thirty patients （37 eyes） diagnosed with FEVR were enrolled. Twenty patients （66.67%） were male and 10 patients （33.33%） were female. Age ranged from 0.4 to 35 years old （median 3y）. IVR was used either as primary or as a combined therapy according to the retinal neovasuclar activities. The follow up ranged from 1 to 57mo with mean 16.73±15.73 （median 11）mo. The treatment effect of retinal neovasuclar activites were recorded as well as the ocular and systemic side effects. RESULTS： Among 30 patients （37 eyes）, 10 eyes received single IVR, 1 eye received 2 injections. Three eyes were treated with IVR and simutanous laser photocoagulation. Laser indirect ophthalmoscopy （LIO） was applied in 5 eyes 1mo after the primary IVR. Seven eyes were treated surgically following the primary IVR due to persistent retinal neovasuclar activities and retinal traction. IVR was used as combined treatment with vitrectomy in 11 eyes. Retinal neovascular regression was notified 1mo following the primary IVR in all eyes. Neither systemic nor ocular complications were recorded. CONCLUSION： IVR may be an effective modality in the treatment of FEVR either as primary or as an ajunct to the conventional therapies. The long term effect and safty of IVR still need further research.

Outcomes and predictors of vitrectomy and silicone oil tamponade in retinal detachments complicated by proliferative vitreoretinopathy

AIM:To evaluate outcomes and determine factors influencing the outcomes of vitrectomy with silicone oil(SO)endotamponade for the management of rhegmatogenous retinal detachment(RRD)complicated by advanced proliferative vitreoretinopathy(PVR).METHODS:This is a retrospective,interventional case series of eyes with PVR grade C associated RRD with or without prior surgery that underwent vitreoretinal surgery and SO tamponade.Eyes with a minimum follow-up of 6mo after SO extraction were included.Eyes were classified into three PVR subgroups according to severity and extension of proliferation.The influence of several preoperative,intraoperative and postoperative factors upon the functional and anatomical outcomes was assessed using multivariate logistic regression analysis.RESULTS:A hundred and one eyes of 101 patients that met the inclusion criteria were studied.Seventy-five of 101 eyes(74.3%)had successful retinal reattachment after one operation.Increased aqueous cell and flare at the first week exam had a statistically significant association with redetachment,recurrent membrane proliferation and keratopathy.Visual acuity improvement was significantly associated with faint postoperative aqueous inflammation values,primary vitrectomy and PVR outside of the posterior pole.CONCLUSION:Although encouraging anatomical and functional outcomes are achieved after vitrectomy and SO tamponade in eyes with RRD complicated by PVR,an increase in aqueous flare or cells at the first week follow-up is most likely to result in postoperative late complications.Primary vitrectomy,PVR associated with minimal posterior pole extension and absent to mild postoperative aqueous inflammation are associated with improved post-operative final visual acuity.

Nomogram for predicting non-proliferative vitreoretinopathy probability after vitrectomy in eyes with rhegmatogenous retinal detachment

AIM:To identify the risk factors for postoperative proliferative vitreoretinopathy(PVR)in patients with primary rhegmatogenous retinal detachment(RRD)and develop a nomogram for predicting postoperative PVR-free probability.METHODS:A total of 741 patients(741 eyes)diagnosed with primary RRD who underwent first surgery in the same hospital were retrospectively reviewed and randomly assigned with 521 to the training set and 220 to the validation set.Univariate and multivariate logistic regression analyses were performed in the training cohort to determine risk factors to construct a nomogram for predicting the 3-,4-,5-,and 6-month postoperative PVR-free probabilities.Nomogram performance was estimated by the concordance index(C-index),calibration plot,and the area receiver operating characteristic(ROC)curve.RESULTS:A nomogram was constructed based on the preoperative PVR,silicone oil tamponade time(SOTT),photocoagulation energy(PE),retinal tear size(RTS),and hypertension.In the training set,the C-index of the nomogram was 0.896,0.936,0.961,and 0.972 at 3,4,5,and 6mo,respectively.The C-index values in the validation set were 0.860,0.936,0.951,and 0.965 at 3,4,5,and 6mo,respectively.Decision-curve analysis indicated that only the 4-,5-,and 6-month nomograms had significant net benefits over a large threshold probabilities interval.CONCLUSION:Preoperative PVR,SOTT,PE,RTS,and hypertension are significant risk factors for postoperative PVR formation in patients with primary RRD.The proposed nomogram can effectively predict the 4-,5-,and 6-month PVR-free probabilities after surgery and assist in making clinical decisions during follow-up.

Expression of IGFBP-6 in a proliferative vitreoretinopathy rat model and its effects on retinal pigment epithelial cell proliferation and migration

AIM: To investigate the expression of insulin-like growth factor binding protein-6(IGFBP-6) in a proliferative vitreoretinopathy(PVR) model and its effects on proliferation and migration in retinal pigment epithelial(RPE) cells. ·METHODS: A PVR Wistar rat model was established by the intravitreal injection of RPE-J cells combined with platelet-rich plasma(PRP). The expression levels of IGFBP-6 were tested by ELISA. ARPE-19 cell proliferation was evaluated by the MTS method,and cell migration was evaluated by wound healing assays. ·RESULTS: The success rate of the PVR model was 89.3%(25/28). IGFBP-6 was expressed at higher levels in the vitreous,serum and retina of rats experiencing advanced PVR(grade 3) than in the control group(vitreous: 152.80 ±15.08ng/mL vs 105.44 ±24.81ng/mL,P 】 0.05; serum: 93.48 ±9.27ng/mL vs 80.59 ±5.20ng/mL,P 【 0.05; retina: 3.02±0.38ng/mg vs 2.05±0.53ng/mg,P 【0.05). In vitro,IGFBP-6(500ng/mL) inhibited the IGF-II(50ng/mL) induced ARPE-19 cell proliferation(OD value at 24h: from 1.38±0.05 to 1.30±0.02; 48h: from 1.44±0.06 to 1.35± 0.05). However,it did not affect basal or VEGF-,TGF-β-and PDGF-induced cell proliferation. IGFBP-6(500ng/ml) reduced the IGF-II(50ng/mL)-induced would healing rate [24h: from(43.91 ±3.85)% to(29.76 ±2.49)%; 48h: from(66.09±1.67)% to(59.88±3.43)%]. ·CONCLUSION: Concentrations of IGFBP-6 increased in the vitreous,serum,and retinas only in advanced PVR in vivo. IGFBP-6 also inhibited IGF-II-induced cell proliferation in a not dose or time dependent manner and migration. IGFBP-6 participates in the development of PVR and might play a protective role in PVR.

Intravitreal slow-release dexamethasone alleviates traumatic proliferative vitreoretinopathy by inhibiting persistent inflammation and Müller cell gliosis in rabbits

AIM:To evaluate the effects of intravitreal slow-release dexamethasone on traumatic proliferative vitreoretinopathy(PVR)and Müller cell gliosis and preliminarily explored the possible inflammatory mechanism in a rabbit model induced by penetrating ocular trauma.METHODS:Traumatic PVR was induced in the right eyes of pigmented rabbits by performing an 8-mm circumferential scleral incision placed 2.5 mm behind the limbus,followed by treatment with a slow-release dexamethasone implant(Ozurdex)or sham injection.Left eyes were used as normal controls.The intraocular pressure(IOP)was monitored using an iCare tonometer.PVR severity was evaluated via anatomical and histopathological examinations every week for 6wk;specific inflammatory cytokine and proliferative marker levels were measured by quantitative real-time polymerase chain reaction,Western blot,protein chip analysis,or immunofluorescence staining.RESULTS:During the observation period,PVR severity gradually increased.Intense Müller cell gliosis was observed in the peripheral retina near the wound and in the whole retina of PVR group.Ozurdex significantly alleviated PVR development and Müller cell gliosis.Post-traumatic inflammation fluctuated and was persistent.The interleukin-1β(IL-1β)mRNA level was significantly upregulated,peaking on day 3 and increasing again on day 21 after injury.The expression of nod-like receptor family pyrin domain containing 3(NLRP3)showed a similar trend that began earlier than that of IL-1βexpression.Ozurdex suppressed the expression of IL-1β,NLRP3,and phosphorylated nuclear factor-kappa B(NF-κB).The average IOP after treatment was within normal limits.CONCLUSION:The present study demonstrates chronic and fluctuating inflammation in a traumatic PVR rabbit model over 6wk.Ozurdex treatment significantly inhibites inflammatory cytokines expression and Müller cell gliosis,and thus alleviates PVR severity.This study highlights the important role of IL-1β,and Ozurdex inhibites inflammation presumably via the NF-κB/NLRP3/IL-1βinflammatory axis.In summary,Ozurdex provides a potential therapeutic option for traumatic PVR.

Atypical Adams-Oliver syndrome with typical ocular signs of familial exudative vitreoretinopathy

AIM:To report an atypical Adams-Oliver syndrome(AOS)family with typical ocular signs of familial exudative vitreoretinopathy(FEVR).METHODS:A patient with visible avascular area and obvious non-perfusion zone in the peripheral retina with systemic signs of AOS was reported.Familial and personal characteristics were collected for the patient and his sister.Gene sequencing and ophthalmic examinations including fluorescein angiography were all performed for the whole family.RESULTS:Two novel mutations of DOCK6(c.1396C>T and c.4796G>A)were identified in the proband and his family,and two compound heterozygous mutations were revealed in the proband and his sister.The patient and his sister showed physical deformities and mental abnormalities while FEVR mimicking retinal disorder can also be defined.No remarkable ocular or systemic abnormality can be observed for their parents.Peripheral retinal non-perfusion area,obvious abnormal vascularization or even retinal fold were observed in the proband and his sister,while only small avascular zone was identified for their parents.CONCLUSION:This is the first genetic authenticated AOS case mimicked as FEVR with genetic sequencing of a family.For the patients with ocular phenotype of FEVR,further examination should be performed if the systemic or mental abnormalities exist.

Evaluating for Vitreous Surgery Used in Proliferative Vitreoretinopathy Grede D_3

Proliferative vitreoretinopathy (PVR) is one of the main failure causes of retinal detachment repair. In this paper, 25 cases of vitreous surgery used in the PVR D3 are analyzed. The diagnosis of PVR depended on the classification of the America Retina Society Terminology Committee. Vitrectomy and peeling were carried out in all of the patients. Intraocular tamponade included silicone oil and gas tamponade. Follow-up is more than 3 months. The anatomic successful rate was 68% and 11 cases arrived 20/400...

Anterior proliferative vitreoretinopathy in a patient with Coats disease

Dear Editor,I am Satoru Kase,from the Department of Ophthalmology,Faculty of Medicine and Graduate School of Medicine,Hokkaido University,Sapporo,Japan.I write to present a case of Coats disease showing anterior proliferative vitreoretinopathy（PVR）and neovascular glaucoma.

De novel heterozygous copy number deletion on 7q31.31-7q31.32 involving TSPAN12 gene with familial exudative vitreoretinopathy in a Chinese family

AIM:To investigate the genetic and clinical characteristics of patients with a large heterozygous copy number deletion on 7q31.31-7q31.32.METHODS:A family with familial exudative vitreoretinopathy(FEVR)phenotype was included in the study.Whole-exome sequencing(WES)was initially used to locate copy number variations(CNVs)on 7q31.31-31.32,but failed to detect the precise breakpoint.The long-read sequencing,Oxford Nanopore sequencing Technology(ONT)was used to get the accurate breakpoint which is verified by quantitative real-time polymerase chain reaction(QPCR)and Sanger Sequencing.RESULTS:The proband,along with her father and younger brother,were found to have a heterozygous 4.5 Mb CNV deletion located on 7q31.31-31.32,which included the FEVRrelated gene TSPAN12.The specific deletion was confirmed as del(7)(q31.31q31.32)chr7:g.119451239_123956818del.The proband exhibited a phase 2A FEVR phenotype,characterized by a falciform retinal fold,macular dragging,and peripheral neovascularization with leaking of fluorescence.These symptoms led to a significant decrease in visual acuity in both eyes.On the other hand,the affected father and younger brother showed a milder phenotype.CONCLUSION:The heterozygous CNV deletion located on 7q31.31-7q31.32 is associated with the FEVR phenotype.The use of long-read sequencing techniques is essential for accurate molecular diagnosis of genetic disorders.

Upregulation of ASPP2 expression alleviates the development of proliferative vitreoretinopathy in a rat model

AIM:To investigate whether upregulation of apoptosisstimulating p53 protein 2(ASPP2)expression could alleviate the development of proliferative vitreoretinopathy(PVR)in a rat model.METHODS:ASPP2-lentivirus or scrambled-lentivirus were transfected into ARPE-19 cells,followed with measurements of cell cytotoxicity by cell counting kit-8 assay.ASPP2 upregulation was confirmed by Western blotting and immunocytochemistry.Then ARPE-19 cells pretreated with ASPP2-lentivirus were intravitreally injected to Brown Norway rats to induce PVR models.PVR development and retinal function were evaluated by retinal photography and electroretinography,respectively.Finally,epithelial-mesenchymal transition as well as autophagy were investigated in rats’retinas via Western blotting.RESULTS:Protein expression of ASPP2 was significantly upregulated by ASPP2-lentivirus transfection in ARPE-19 cells.The development and progression of PVR were impeded significantly in rats with intravitreal injection of ARPE-19 cells pretreated with ASPP2-lentivirus.Accordingly,retinal functions were less affected and PVR grades were much lower in rats with ASPP2-lentivirus compared to scrambledlentivirus treatment.Moreover,epithelial-mesenchymal transition and autophagy markers were decreased in the retinas of rats treated with ASPP2-lentivirus.CONCLUSION:ASPP2-lentivirus transfected to ARPE-19 cells mitigates the progression of PVR in rat models,which might be partly through reduced autophagy and attenuated epithelial-mesenchymal transition.ASPP2 might stand as a new approach for PVR treatment in the future.

Defective EMC1 drives abnormal retinal angiogenesis via Wnt/β-catenin signaling and may be associated with the pathogenesis of familial exudative vitreoretinopathy

Endoplasmic reticulum(ER)membrane protein complex(EMC)is required for the co-translational insertion of newly synthesized multi-transmembrane proteins.Compromised EMC function in different cell types has been implicated in multiple diseases.Using inducible genetic mouse models,we revealed defects in retinal vascularization upon endothelial cell(EC)specific deletion of Emc1,the largest subunit of EMC.Loss of Emc1 in ECs led to reduced vascular progression and vascular density,diminished tip cell sprouts,and vascular leakage.We then performed an unbiased transcriptomic analysis on human retinal microvascular endothelial cells(HRECs)and revealed a pivotal role of EMC1 in theβ-catenin signaling pathway.Further in-vitro and in-vivo experiments proved that loss of EMC1 led to compromisedβ-catenin signaling activity through reduced expression of Wnt receptor FZD4,which could be restored by lithium chloride(LiCl)treatment.Driven by these findings,we screened genomic DNA samples from familial exudative vitreoretinopathy(FEVR)patients and identified one heterozygous variant in EMC1 that co-segregated with FEVR phenotype in the family.In-vitro expression experiments revealed that this variant allele failed to facilitate the expression of FZD4 on the plasma membrane and activate theβ-catenin signaling pathway,which might be a main cause of FEVR.In conclusion,our findings reveal that variants in EMC1 gene cause compromisedβ-catenin signaling activity,which may be associated with the pathogenesis of FEVR.

Variants in the Wnt co-receptor LRP6 are associated with familial exudative vitreoretinopathy

Familial exudative vitreoretinopathy(FEVR),an inherited eye disease,is characterized by abnormal retinal vascular development,such as neovascularization,vitreous hemorrhage,exudation,and retinal detachment(Criswick and Schepens,1969;Robitaille et al.,2002).FEVR is inherited as autosomal dominant,autosomal recessive,and X-linked patterns(de Crecchio et al.,1998).

Inhibition of RhoA/Rho-kinase pathway suppresses the expression of extracellular matrix induced by CTGF or TGF-β in ARPE-19

AIM:To investigate the role of Rho-associated protein kinase (ROCK) inhibitor, Y27632, in mediating the production of extracellular matrix (ECM) components including fibronectin, matrix metallo-proteinase-2 (MMP-2) and type I collagen as induced by connective tissue growth factor(CTGF) or transforming growth factor-β (TGF-β) in a human retinal pigment epithelial cell line, ARPE-19. METHODS:The effect of Y27632 on the CTGF or TGF-β induced phenotype in ARPE-19 cells was measured with immunocytochemistry as the change in F-actin. ARPE-19 cells were treated with CTGF (1, 10, 100ng/mL)and TGF-β (10ng/mL) in serum free media, and analyzed for fibronectin, laminin, and MMP-2 and type I collagen by RT-qPCR and immunocytochemistry. Cells were also pretreated with an ROCK inhibitor, Y27632, to analyze the signaling contributing to ECM production. ·RESULTS:Treatment of ARPE-19 cells in culture with TGF-β or CTGF induced an ECM change from a cobblestone morphology to a more elongated swirl pattern indicating a mesenchymal phenotype. RT-qPCR analysis and different gene expression analysis demonstrated an upregulation in expression of genes associated with cytoskeletal structure and motility. CTGFor TGF-β significantly increased expression of fibronectin mRNA (P =0.006, P =0.003 respectively), laminin mRNA (P =0.006, P =0.005), MMP-2 mRNA (P =0.006, P =0.001), COL1A1 mRNA (P =0.001, P =0.001), COL1A2 mRNA (P = 0.001, P =0.001). Preincubation of ARPE-19 with Y27632 (10mmol/L) significantly prevented CTGF or TGF-β induced fibronectin (P=0.005, P=0.003 respectively), MMP-2 (P = 0.003, P =0.002), COL1A1 (P =0.006, P =0.003), and COL1A2 (P =0.006, P =0.004) gene expression, but not laminin (P =0.375, P =0.516). CONCLUSION:Our study demonstrated that both TGF-β and CTGF upregulate the expression of ECM components including fibronectin, laminin, MMP-2 and type I collagen by activating the RhoA/ROCK signaling pathway. During this process, ARPE-19 cells were shown to change from an epithelial to a mesenchymal phenotype in vitro. Y27632, a ROCK inhibitor, inhibited the transcription of fibronectin, MMP-2 and type I collagen, but not laminin. The data from our work suggest a role for CTGF as a profibrotic mediator. Inhibiting the RhoA/ROCK pathway represents a potential target to prevent the fibrosis of retinal pigment epithelial (RPE) cells. This might lead to a novel therapeutic approach to preventing the onset of early proliferative vitreoretinopathy(PVR).

GSK3β inhibits epithelial-mesenchymal transition via the Wnt/β-catenin and PI3K/Akt pathways

AIM： To investigate the regulatory mechanism of glycogen synthase kinase 3β（GSK3β） in epithelialmesenchymal transition（EMT） process after proliferative vitreoretinopathy（PVR） induction. METHODS： Experimental PVR was induced by intravitreal injection of retinal pigment epithelium（RPE） cells in the eyes of rabbits. A PI3 K/Akt inhibitor（wortmannin） and a GSK3β inhibitor（Li Cl） were also injected at different time during PVR progress. Electroretinogram（ERG）, ocular fundus photographs, and B-scan ultrasonography were used to observe the PVR progress. Western blot test on the extracted retina were performed at 1, 2, 4 wk. The expression of the mesenchymal marker vimentin was determined by immunohistochemistry. Toxicity of wortmannin and Li Cl were evaluated by ERG and Td Tmediated d UTP nick-end labeling（TUNEL） assay. The vitreous was also collected for metabolomic analysis. RESULTS： Experimental PVR could significantly lead to EMT, along with the suppressed expression of GSK3β and the activation of Wnt/β-catenin and PI3 K/Akt pathways. It was verified that upregulating the expression of GSK3β could effectively inhibit EMT process by suppressing Wnt/β-catenin and PI3 K/Akt pathways. CONCLUSION： GSK3β effectively inhibits EMT via the Wnt/β-catenin and PI3 K/Akt pathways. GSK3β may be regarded as a promising target of experimental PVR inhibition.

PI3K/AKT/mTOR signaling pathway inhibitors in proliferation of retinal pigment epithelial cells

AIM: To determine whether the PI3K/AKT/mTOR pathway is activated in proliferative vitreoretinopathy (PVR) in homo-sapiens. METHODS: The retina of controls and patients with PVR were collected and their levels of PI3K, phospho-AKT, phospho-mTOR, phospho-p70S6k and phospho-4EBP-1 were determined by Western blot. The cultured human retinal pigment epithelial cell line D407 was treated with a specific mTOR inhibitor, rapamycin (RAPA) or a PI3K inhibitor, LY294002, of various concentrations and durations. Cell morphology was observed by phase contrast microscopy and the proliferation and apoptosis of treated cells were determined by MTT assay and flow cytometry. RESULTS: Levels of PI3K, phospho-AKT, phospho-mTOR, phospho-P70S6K and phospho-4EBP1 was increased in the retina in PVR (P <0.05). In D407 cells, both RAPA and LY294002 significantly inhibited cell proliferation and cell cycle progression, and promoted apoptosis (P <0.05); morphologically, the cells became smaller. Both RAPA and LY294002 reduced levels of phospho-AKT, phospho-mTOR, phospho-p70S6k and phospho-4EBP1 expression (P <0.05). RAPA, but not LY294002, had no significant effect on PI3K expression. CONCLUSION: PI3K/AKT/mTOR signaling pathway is highly activated in the retinal pigment epithelial cells of PVR. The inhibitors of PI3K/AKT/mTOR signaling pathway, RAPA and LY294002, could inhibited the PI3K/AKT/mTOR signaling pathway by reducing the levels of phosphorylation of mTOR pathway components.

The role of mechanical stretch and TGF-β2 in epithelial-mesenchymal transition of retinal pigment epithelial cells

AIM: To explore the effects and mechanisms of mechanical stress and transforming growth factor-beta2(TGF-β2) on epithelial-mesenchymal transition(EMT) in cultured human retinal pigment epithelial(RPE) cells. METHODS: Human RPE cells were inoculated on BioF ex 6-well plates and RPE cells received 0, 1, 2, 3, or 4 mild stretch injuries delivered 3h apart after 24h of culture. The device of mechanical stress parameters were set to sine wave, frequency 1 Hz, stretch strength 20%. For treatment with TGF-β2, when the inoculated RPE cells in 6-well plates were around 60% confluent, serum was reduced to 0 for 12h and recombinant human TGF-β2(0, 1, 5, 10 ng/mL)was added for 48h. α-SMA, Vimentin and N-Cadherin, fibronectin proteins expressions were detected by Western blotting, confocal cell immunofluorescence and quantitative real-time polymerase chain reaction(q RT-PCR). Then we detected the change of mi RNA-29b and ascertained the changes of phosphatidylinositol 3-kinase-serine threonine protein kinase(PI3K/Akt) pathway after RPE cells were stretched by the device of mechanical stress and induced by TGF-β2 by Western blotting, confocal cell immunofluorescence and qR T-PCR. RESULTS: Mechanical stress induce EMT and activate the PI3K/Akt pathway in ways that lead to the EMT process. TGF-β2 induce RPE cells EMT and in a certain range and TGF-β2 decrease the miR NA-29b expression in RPE cells, and the inhibitory effect is more obvious with the increase of TGF-β2 concentration. CONCLUSION: Our findings are crucial steps in determining the critical roles of the PI3K/Akt signaling pathway and mi RNA-29b in pathogenesis of proliferative vitreoretinopathy(PVR) which may be a potential target for preventing or treating PVR.

Artesunate inhibits proliferation and migration of RPE cells and TGF-β2 mediated epithelial mesenchymal transition by suppressing PI3K/AKT pathway

AIM:To study the braking effectiveness of artesunate on transforming growth factor(TGF)-β2 mediated epithelial-mesenchymal transition(EMT)in retinal pigment epithelium(RPE)in vitro.METHODS:The fostered ARPE-19 cells were processed with artesunate alone or combined with the TGF-β2.The CCK-8 examination was utilized to test the cell propagation.Cell migration was detected by scratch as well as the Transwell examination.The EMT characters and activation of PI3K/Akt signal channel were estimated by Western blotting and immunofluorescence.The Western blotting was utilized in order to confirm the vitreous of controls as well as patients with proliferative vitreoretinopathy(PVR)were collected and the levels of PI3K,phospho-PI3K,Akt.RESULTS:Disposal of ARPE-19 cells with artesunate(50-150μmol/L)obviously suppressed their propagation and immigration,which dependent on the concentration and time.Artesunate suppressed the EMT which was induced by TGF-β2 in ARPE-19 cells through sustaining the expression of vimentin andα-SMA through the suppression of PI3K,phospho-PI3K,phospho-Akt and Akt.Levels of PI3K,phospho-PI3K,AKT and phospho-Akt was increased in the vitreous in PVR(P<0.05).CONCLUSION:Such findings indicate that PI3K/Akt signal channel is highly activated in vitreous of PVR.Artesuante is an operative depressor of the propagation,immigration and TGF-β2-mediated EMT of ARPE-19 cells by reduced the expression of PI3K/Akt channel.

Pirfenidone suppresses the abnormal activation of human Müller cells after platelet-derived growth factor-BB stimulation

AIM: To determine the effect of pirfenidone on the activated human Müller cells by platelet-derived growth factor-BB(PDGF-BB). METHODS: The primary human Müller cells were separated from retinal tissues and established the pathogenic model by stimulated with PDGF-BB. The Müller cells behaviour of normal group and the model group was measured by MTT assay, Trypan blue assay, cell migration assay, and collagen contraction assay. The expression of transforming growth factor(TGF)-β1,-β2, and pigment epithelium-derived factor(PEDF) was estimated with realtime polymerase chain reaction(PCR), Western blot and immunofluorescence analyses. RESULTS: A pathogenic/proliferative model of Müller cells was established by stimulating normal cultured Müller cells with 10 ng/mL PDGF-BB for 48 h. After treated with 0.2 and 0.3 mg/mL pirfenidone, the proliferation, migration and collagen contraction was statistically significantly depressed in the model group compared with the normal groups. The expression levels of TGF-β1 and TGF-β2 were significantly down-regulated, while the PEDF expression was significantly up-regulated after treated with 0.2 and 0.3 mg/mL pirfenidone in the model group. CONCLUSION: Pirfenidone effectively suppress the proliferation, migration and collagen contraction of the human Müller cells stimulated with PDGF-BB through down-regulation of TGF-β1/TGF-β2 and up-regulation of PEDF.