Oxidative Stress Participates in Age-Related Cataract Formation by Disrupting Connection between Lens Epithelial Cells through c-Src/VEGF Pathway.

PURPOSE: To observe the effects of oxidative stress on vascular endothelial growth factor (VEGF) and connections of lens epithelial cells. METHODS: Human lens epithelium of patients with age-related cataract (ARC), both SRA01/04 cells and whole mice lens stimulated by H2O2 were employed. VEGF in human aqueous humor of ARC-patients and the supernatant of SRA01/04 cells was determined by ELISA. The expressions of VEFG in human lens epithelium were detected by immunofluorescence staining. Multiple linear regression analysis and spearman rank-order correlation were used to determine the associations between VEGF and parameters of ARC individuals. In H2O2-induced SRA01/04 cells, Catalase (CAT), PP1 (inhibitor of c-Src kinase) and Avastin (VEGF antibody) were used to inhibit the effects of H2O2, activation of c-Src kinase and VEGF, which were detected by Western blot. The alterations of ZO-1 and N-cadherin were tested by immunofluorescence staining and Western blot. In H2O2-induced whole lens, the changes of opacification area in different treatment of inhibitors were observed. RESULTS: The secretion of VEGF in aqueous humor and expression of VEGF in the lens epithelium of ARC patients increased significantly with age. In H2O2-induced SRA01/04 cells, the VEGF in the supernatant was increased with the culture duration and the dose of H2O2. The expressions of p-Src418 and VEGF were also up-regulated, whereas the expressions of ZO-1 and N-cadherin were down-regulated. CAT effectively prevented these changes induced by H2O2, while PP1 inhibited not only p-Src418 but also up-regulation of VEGF, Avastin partially inhibited VEGF up-regulation. Both PP1 and Avastin prevented down-regulation of ZO-1 and N-cadherin, respectively, but Avastin combined with PP1 had no significant synergistic effects. In H2O2-induced cataract, CAT prevented development of opacification area effectively, and PP1 and Avastin did partially. CONCLUSIONS: Oxidative stress disrupts connections of lens epithelial cells by activating c-Src/VEGF, inhibiting which may prevent cataract.

Long-term efficacy and safety of YAG laser vitreolysis for vision degrading myodesopsia.

AIM: To assess the long-term efficacy and safety of yttrium-aluminum garnet (YAG) laser vitreolysis for vision degrading myodesopsia (VDM) caused by posterior vitreous detachment (PVD). METHODS: This retrospective study reviewed VDM patients of PVD type undergoing YAG laser vitreolysis. The baseline demographic information, the patterns of floaters, the number of floaters, and the subjective improvement of floater sympotoms (ranging from 0 to 100%) from medical records were collected. Significant improvement was defined as a relief of floater symptoms of ≥50% at the final visit. The long-term efficacy and safety of YAG laser vitreolysis were analyzed. The risk factors linked to significant improvement of floater symptoms were defined using univariate and multivariate logistic regression analyses. RESULTS: The final analysis included 221 patients with VDM. The mean age of patients was 61.08±7.74y, and the mean length of follow-up was 21.38±5.61mo. Totally 57.01% of patients experienced a significant improvement in their floater symptoms after YAG laser therapy, and none of them developed delayed retinal abnormalities such as retinal tears or detachments. Age (OR=1.049, 95%CI=1.007-1.092, P=0.021) was identified as a significant risk factor for significant improvement in VDM. CONCLUSION: YAG laser vitreolysis is an effective and secure treatment for PVD-type VDM, and patients of advanced age are more likely to get favorable outcomes.

Agreement of intraocular pressure measurement with Corvis ST, non-contact tonometer, and Goldmann applanation tonometer in children with ocular hypertension and related factors.

AIM: To access the agreement of intraocular pressure (IOP) values obtained from biomechanically corrected tonometer [Corvis ST (CST)], non-contact tonometer (NCT), and Goldmann applanation tonometer (GAT) in children with NCT measured-IOP (NCT-IOP) values of 22 mm Hg or more, and related factors. METHODS: A total of 51 eyes with NCT-IOP≥22 mm Hg in children aged 7 to 14y were examined and IOP was measured by CST, NCT, and GAT. Based on GAT measured IOP (GAT-IOP), ocular hypertension (OHT) group (≥22 mm Hg, 24 eyes) and the non-OHT group (<22 mm Hg, 27 eyes) were defined. We compared the agreement of the three measurements, i.e., CST measured IOP (CST-IOP), GAT-IOP, and NCT-IOP, and further analyzed the correlation between the differences in tonometry readings, central corneal thickness (CCT), axial length (AL), optic disc rim volume, and age. RESULTS: Compared with the OHT group, thicker CCT, larger rim volume, and higher differences between NCT-IOP and GAT-IOP, were found in the non-OHT group. The differences between CST-IOP and GAT-IOP were lower than the differences between NCT-IOP and GAT-IOP in both groups. The mean differences in CST-IOP and GAT-IOP were 1.26 mm Hg (95% limit of agreement ranged from 0.1 to 2.41 mm Hg, OHT group) and 1.20 mm Hg (95% limit of agreement ranged from -0.5 to 3.00 mm Hg, non-OHT group), and the mean differences in NCT and GAT were 3.90 mm Hg (95% limit of agreement ranged from -0.19 to 9.70 mm Hg, OHT group) and 6.00 mm Hg (95% limit of agreement ranged from 1.50 to 10.50 mm Hg, non-OHT group). The differences between CST-IOP and GAT-IOP were not related to CCT, age, and AL in both groups; while the differences between NCT-IOP and GAT-IOP were related to CCT in the OHT group (r=0.93, P<0.001) and to CCT and AL in the non-OHT group (r=0.66, P<0.001, r=-0.81, P<0.001). CONCLUSION: The accuracy of NCT in the diagnosis of pediatric OHT is low. The agreement of CST-IOP and GAT-IOP was significantly higher in children with and without OHT than in those with NCT-IOP and GAT-IOP. Therefore, CST can be used as a good alternative for IOP measurement in children. The impacts of CCT and AL on NCT measurement need to be fully considered when managing childhood IOP.

Long-term outcomes of anti-VEGF treatment with 5+PRN regimen for macular edema due to central retinal vein occlusion.

AIM: To assess the long-term outcomes of treating macular edema (ME) associated with central retinal vein occlusion (CRVO) with a regimen of "5+pro re nata (PRN)". METHODS: This retrospective study included 27 eyes of 27 patients with ME associated with non-ischemic CRVO (non-iCRVO group, n=15) and ischemic CRVO (iCRVO group, n=12). The eyes were treated with five consecutive intravitreal injections of conbercept or ranibizumab, followed by reinjections as needed or PRN. Retinal laser photocoagulation or intravitreal dexamethasone implants (DEX) were implemented in both groups when necessary. The best-corrected visual acuity (BCVA, logMAR) and central retinal thickness (CRT) were recorded at baseline, at 1, 2, 3, 4, 5, 6, and 12mo, and at the final visit. The efficacy rates of BCVA and CRT before and after treatment were calculated. The number of injections at each visit and the incidence of adverse events were also recorded. RESULTS: The patients, aged 59.4±15.1y, were followed up for 24.7±8.8mo (range: 15-42mo). After treatment, BCVA improved significantly from 1.04±0.56 logMAR at baseline to 0.59±0.36 logMAR (P=0.038) at the final visit in all patients. Both the non-iCRVO and the iCRVO groups achieved improved BCVA compared to the baseline at all visit points, but there was no statistical significance (P=0.197 and 0.33, respectively). The mean CRT was statistically reduced compared to baseline at all visit points in all the eyes and in both groups (all P<0.001). The apparent effective rate was 22.22% for BCVA and 37.04% for CRT after the first injection, 48.15% for BCVA and 62.96% for CRT after 5 consecutive injections, and 74.08% for BCVA and 100% for CRT at the end of follow up. The average number of injections in all patients was 9.0±2.4 at 12mo and 14.9±8.1 finally with no statistical significance between both groups (P>0.05). Laser treatment was applied to all eyes in the iCRVO group, while only 5 patients in the non-iCRVO group. Six patients in the non-iCRVO group and 3 patients in the iCRVO group had a drug switch. DEX was applied to 4 eyes in the non-iCRVO group and 5 eyes in the iCRVO group. CONCLUSION: The 5+PRN anti-vascular endothelial growth factor (VEGF) regimen is found to be safe and effective for both iCRVO and non-iCRVO, especially in the iCRVO group. The best regimen for such patients needs to be further investigated. Adjuvant laser therapy and DEX are necessary in some cases.

Efficacy and safety of atropine at different concentrations in prevention of myopia progression in Asian children: a systematic review and Meta-analysis of randomized clinical trials.

AIM: To assess the efficacy versus the adverse effects of various concentrations of atropine in the prevention of myopia in Asian children. METHODS: Databases (PubMed, EMBASE, the Cochrane Library and Web of science) were comprehensively searched from inception to April 2022. Types of studies included were randomized clinical trials (RCTs). The published languages were limited to English. Two researchers assessed the quality of included studies independently using Cochrane risk of bias tool based on the Cochrane Handbook for Systematic Reviews of Interventions. Funnel plots and Egger's test were used for detection of publication bias. Meta-analyses were conducted using STATA (version 15.0; StataCorp). RESULTS: A total of 15 RCTs involving 2268 patients were included in the study. In the atropine group, spherical equivalent progressed at a significantly lower rate [weighted mean difference (WMD)=0.39, 95% confidence interval (CI): 0.23, 0.54] than in the control group. A WMD of 0.15 mm was associated with less axial elongation (95%CI -0.19, -0.10). Different doses showed statistically significant differences (P<0.05) and an improved effect could result from a higher concentration. Changes in photopic pupil size and mesopic pupil size in atropine group is 0.70 mm (95%CI: 0.33, 1.06) and 0.38 mm (95%CI: 0.22, 0.54) more than the control group. In the present Meta-analysis, no changes in accommodative amplitude (AA) were associated with atropine administration. Atropine administration increased the risk of adverse effects by 1.37 times. CONCLUSION: Concentrations of less than 1% atropine are able to effectively retard diopter and axis growth of myopia in Asian children in a dose-dependent manner. Meanwhile, it caused pupil enlargement, but induced no change in the AA within this range. Further study is required to determine the dosage needed to achieve maximum efficacy and minimal side effects.

Differential analysis of aqueous humor cytokine levels in patients with macular edema secondary to diabetic retinopathy or retinal vein occlusion.

AIM: To evaluate the difference and the correlation between the concentrations of cytokines in the aqueous humor of eyes with macular edema secondary to diabetic retinopathy (DR) or retinal vein occlusion (RVO). METHODS: This is a retrospective case control study. The aqueous humor samples were collected during intravitreal injection of anti-vascular endothelial growth factor (VEGF) for patients diagnosed with macular edema secondary to DR (DME) or RVO (RVO-ME) at Xijing Hospital from August 2021 to July 2022. Meanwhile, aqueous humor samples during vitrectomy from patients with idiopathic macular hole (IMH) were also collected and served as controls. The aqueous humor concentrations of VEGF, platelet-derived factor (PDGF), interleukin (IL)-6, IL-8, IL-18, tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein 1 (MCP-1) were measured with Human Premixed Multi-Analyte Kit (Luminex). The difference of the aqueous cytokines and the correlation between the two diseases were analyzed. RESULTS: A total of 40 eyes of 38 patients were enrolled in the study, including 13 eyes of 11 DME patients (DME group), 16 eyes of 16 RVO-ME patients (RVO-ME group) and 11 eyes of 11 IMH patients (control group). The VEGF, PDGF, IL-6, IL-8, and MCP-1 levels of the aqueous humor were higher in both DME and RVO-ME groups compared with the control group (all P<0.05), the levels of TNF-α was higher in the DME group than in the control group (P<0.05). The VEGF, IL-6, MCP-1, and TNF-α levels in the aqueous humor were significantly higher in the DR group than those in the RVO group (all P<0.05). Correlation analyses revealed that there were complex positive correlations between IL-6, IL-8, IL-18, MCP-1, and TNF-α levels in the aqueous humor of eyes with two diseases. CONCLUSION: Although ischemic and inflammatory factors are similarly involved in the pathogenesis of DME and RVO-ME, the roles of these factors are more significant or more likely to be activated in DR patients, suggesting different treatment strategies should be considered for the two diseases.

Guideline for the treatment of no light perception eyes induced by mechanical ocular trauma.

Severe mechanical ocular trauma with no light perception (NLP) predicts a poor prognosis of visual acuity and enucleation of the eyeball. Since the innovative treatment concept of exploratory vitreoretinal surgery has developed and treatment technology has advanced, the outcomes of severe ocular trauma treatment in NLP patients have greatly improved. However, there remains a lack of unified standards for the determination, surgical indication, and timing of vitrectomy in NLP eye treatment. To address these problems, we aimed to create evidence-based medical guidelines for the diagnosis, treatment, and prognosis of mechanical ocular trauma with NLP. Sixteen relevant recommendations for mechanical ocular trauma with NLP were obtained, and a consensus was reached. Each recommendation was explained in detail to guide the treatment of mechanical ocular trauma associated with NLP.

Vitreous function and intervention of it with vitrectomy and other modalities.

The vitreous body, the largest intraocular component, plays a key role in eye development, refraction, cell barrier function, oxygen metabolism and the pathogenesis of assorted diseases. Age, refraction and systemic diseases can cause vitreous metabolic abnormalities. With the continuous development of vitrectomy techniques and equipment, vitreous injections and vitrectomies have increased over the recent decades. However, the normal oxygen tension gradient in the vitreous helps to protect the lens and anterior chamber angle from oxidative stress damage, whereas the increased vitreous oxygen tension around lens and the trabecular meshwork after vitrectomy. It may lead to postoperative nuclear cataract and increase the risk for glaucoma. As a conventional procedure, scleral buckling holds several advantages over vitrectomy in selected cases. This review raises concerns regarding the function of the vitreous and encourages conducting vitreous interventions prudently if it is possible.

Intraocular lens removal or not during vitrectomy for acute infectious endophthalmitis after cataract surgery.

At present, the incidence of infectious endophthalmitis after cataract surgery has been significantly reduced, but it is still a serious complication. Removal or not of the intraocular lens (IOL) during vitrectomy in cases with a moderate or severe inflammation is controversial. In order to call upon more discussion, we publish the article entitled "Timely vitrectomy without intraocular lens removal for acute endophthalmitis after cataract surgery" written by Guo et al in this issue. With recent advanced vitrectomy techniques, and critical measures for management of risk factors related to occurrence of infection, IOL remaining during timely vitrectomy for acute endophthalmitis can possibly be safe and effective in selected cases.

Comparable postoperative myopic shift in eyes with retinal vascular diseases and vitreomacular interface diseases after phacovitrectomy.

PURPOSE: To compare the predictive refractive error (PRE) of intraocular lens (IOL) power between retinal vascular and vitreomacular interface diseases after phacovitrectomy. METHODS: We retrospectively reviewed patients who underwent phacovitrectomy for various retinal diseases. Patients with retinal vascular diseases and vitreomacular interface diseases were included in group A and group B, respectively. Age- and gender-matched senile cataract patients with phacoemulsification were set as controls. The mean PRE and absolute value of refractive error (ARE) among different groups were compared. The associated risk factors with ARE were also analyzed in the univariate and multivariate analyses. RESULTS: In total, 106 patients (Group A), 108 patients (Group B), and 110 patients as controls were included. The PRE in Group A (- 0.35 ± 0.83D) and Group B (- 0.53 ± 0.74D) were more myopic compared to the control group (- 0.11 ± 0.58D) (p < 0.05). The ARE in Group A (0.70 ± 0.57D) and Group B (0.75 ± 0.51D) were significantly higher compared to the control group (0.47 ± 0.35D) (p < 0.05). There were no significant differences in the PRE and ARE values between the two study groups (p = 0.267 and 0.861, respectively). There were no significant differences of the PRE and ARE in the eyes with silicone oil tamponade (- 0.63 ± 0.75D, 0.81 ± 0.54D) and gas tamponade (- 0.42 ± 0.83D, 0.74 ± 0.56D) (p = 0.693 and 0.988, respectively). In the multivariate model, preoperative LogMAR visual acuity (ß = 0.162, 95%CI = 0.113-0.211, p < 0.001), mean corneal curvature (ß = 0.105, 95% CI = 0.074-0.135, p < 0.001), and age (ß = 0.012, 95% CI = 0.005-0.019, p = 0.001) were all positively correlated with the ARE. CONCLUSIONS: Postoperative myopic shift after phacovitrectomy may be comparable in retinal vascular diseases and vitreomacular interface diseases, no matter the gas or silicone oil tamponade. Older age, steeper corneal curvature, and worse preoperative visual acuity could produce more prediction errors.

Long-term outcomes of drusenoid pigment epithelium detachment in intermediate AMD treated with 577 nm subthreshold micropulse laser: a preliminary clinical study.

AIM: To evaluate the long-term anatomical and visual outcomes of drusenoid pigment epithelial detachment (D-PED) in intermediate age-related macular degeneration (AMD) eyes treated with 577 nm yellow subthreshold micropulse laser (SML). METHODS: In this retrospective study, 21 eyes of 16 patients with D-PED in intermediate AMD were consecutively included and assessed. All the eyes were treated with 577 nm SML in several sessions according to D-PED growth status. The logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) were assessed at the initial visit and after treatment. Spectral-domain optical coherence tomography (SD-OCT) was performed to evaluate the D-PED lifecycle by volumetric calculations. Regression analysis was used to determine the breakpoint, growth, and collapse rate of the D-PED lesions. The progression to advanced AMD was also documented. RESULTS: All the eyes were treated with SML for 2.9±1.0 sessions. The mean follow-up period was 25.3±12.6mo. The BCVA was stable from the baseline to final visit. All the eyes were categorized into two groups according to the anatomical changes of the D-PED lesion: the collapse group (n=6, 28.6%) and non-collapse group (n=15, 71.4%). The change in logMAR BCVA did not differ significantly between the collapse group 0.00 (-0.31, 0.85) and non-collapse group 0.00 (0.00, 0.00; P=1). Regression analysis showed that the growth rate was significantly higher in the collapse group (0.090±0.095 mm3/mo) than in the non-collapse group (0.025±0.035 mm3/mo; P<0.001). One eye (4.8%) developed macular neovascularization at 11mo after SML treatment in the non-collapse group. Three eyes (14.3%) developed geographic atrophy (GA) in the collapse group. CONCLUSION: Compared to the natural course of D-PED reported by previous studies, our results preliminarily show that SML can alleviate visual loss and possibility of progression to advanced AMD in eyes with D-PED in intermediate AMD. A controlled clinical trial needs to further verify the benefit of the intervention.

The Efficacy and Safety of YAG Laser Vitreolysis for Symptomatic Vitreous Floaters of Complete PVD or Non-PVD.

INTRODUCTION: To evaluate and compare the efficacy and safety of YAG laser vitreolysis in treating symptomatic vitreous floaters of complete posterior vitreous detachment (PVD) and non-PVD. METHODS: In this prospective cohort study, 51 eyes with symptomatic floaters were treated with YAG laser vitreolysis. Participants were divided into complete PVD and non-PVD groups. Objective visual quality measures including the Strehl ratio (SR), internal spherical aberration (SA), internal comatic aberration (CA), internal high-order aberration (HOA), area ratio of modulation transfer function (MTFa) and Vitreous Floaters Symptom Questionnaire (VFSQ-13) scores were used to compare the efficacy of YAG laser vitreolysis treatment between two groups. RESULTS: The mean age of all patients was 56.80 ± 10.82 years old. In total, 36 of 51 (70.59%; 95% CI 58.10-83.10) patients reported their symptoms as significant or complete improvement after YAG laser vitreolysis treatment. Post-treatment MTFa, internal SA and internal HOA were significantly better compared to baseline (26.19 ± 14.73 vs. 29.19 ± 17.98, p = 0.013; 0.05 ± 0.05 vs. 0.04 ± 0.04, p = 0.031 and 0.23 ± 0.22 vs. 0.16 ± 0.07, p = 0.044; respectively) in all eyes. Twenty-nine of 51 (56.86%) eyes had floaters of non-PVD type. Significant or complete subjective improvements in the PVD group and non-PVD group were 72.73% and 68.97% (p = 0.344), respectively. CONCLUSIONS: Improved subjective and objective visual quality in participants with symptomatic floaters following YAG laser vitreolysis was found in both groups. The efficacy of YAG laser vitreolysis was comparable in floaters of complete PVD and non-PVD types.

Vitreous function and intervention of it with vitrectomy and other modalities.

The vitreous body, the largest intraocular component, plays a key role in eye development, refraction, cell barrier function, oxygen metabolism and the pathogenesis of assorted diseases. Age, refraction and systemic diseases can cause vitreous metabolic abnormalities. With the continuous development of vitrectomy techniques and equipment, vitreous injections and vitrectomies have increased over the recent decades. However, the normal oxygen tension gradient in the vitreous helps to protect the lens and anterior chamber angle from oxidative stress damage, whereas the increased vitreous oxygen tension around lens and the trabecular meshwork after vitrectomy may lead to postoperative nuclear cataract and a high incidence of open angle glaucoma. As a conventional procedure, scleral buckling holds several advantages over vitrectomy in selected cases. This review raises concerns regarding the function of the vitreous, and encourages conducting vitreous interventions prudently.

Newly-found functions of metformin for the prevention and treatment of age-related macular degeneration.

Metformin (MET), a first-line oral agent used to treat diabetes, exerts its function mainly by activating adenosine monophosphate-activated protein. The accumulation of oxidized phospholipids in the outer layer of the retina plays a key role in retinal pigment epithelium (RPE) cells death and the formation of choroidal neovascularization (CNV), which mean the development of age-related macular degeneration (AMD). Recent studies have shown that MET can regulate lipid metabolism, inhibit inflammation, and prohibit retinal cell death and CNV formation due to various pathological factors. Here, newly discovered functions of MET that may be used for the prevention and treatment of AMD were reviewed.

Commentary review on peripapillary morphological characteristics in high myopia eyes with glaucoma: diagnostic challenges and strategies.

The incidences of open angle glaucoma (OAG) and high myopia are increasing concomitantly. Considering the aging population and concurrent rapid increase in the number of individuals with myopia, the risk of visual defects caused by highly myopic OAG is likely to increase dramatically over the next few decades. However, precise screening and diagnosis of OAG is challenging because of the tilt and rotation of the optic disc, as well as extensive ß-zone parapapillary atrophy in highly myopic eyes. Recent advances in optical coherence tomography (OCT) and OCT angiography (OCTA) technologies imply that both modalities are promising tools for the detection of highly myopic OAG. Notably, the diagnosis of OAG remains to be determined with the longitudinal changes of functional damages (e.g. visual field defect, visual electrophysiological changes). We herein describe some aspects of microvascular and microstructural pathology in patients with highly myopic OAG and proposes a framework for the development of novel diagnostic and therapeutic strategies.

Connective tissue growth factor promotes retinal pigment epithelium mesenchymal transition via the PI3K/AKT signaling pathway.

Proliferative vitreoretinopathy (PVR) is a disease leading to the formation of contractile preretinal membranes (PRMs) and is one of the leading causes of blindness. Connective tissue growth factor (CTGF) has been identified as a possible key determinant of progressive tissue fibrosis and excessive scarring. Therefore, the present study investigated the role and mechanism of action of CTGF in PVR. Immunohistochemical staining was performed to detect the expression of CTGF, fibronectin and collagen type III in PRMs from patients with PVR. The effects and mechanisms of recombinant human CTGF and its upstream regulator, TGF­ß1, on epithelial­mesenchymal transition (EMT) and the synthesis of extracellular matrix (ECM) by retinal pigment epithelium (RPE) cells were investigated using reverse transcription­quantitative PCR, western blotting and a [3H]proline incorporation assay. The data indicated that CTGF, fibronectin and collagen type III were highly expressed in PRMs. In vitro, CTGF significantly decreased the expression of the epithelial markers ZO­1 and E­cadherin and increased that of the mesenchymal markers fibronectin, N­cadherin and α­smooth muscle actin in a concentration­dependent manner. Furthermore, the expression of the ECM protein collagen type III was upregulated by CTGF. However, the trends in expression for the above­mentioned markers were reversed after knocking down CTGF. The incorporation of [3H]proline into RPE cells was also increased by CTGF. In addition, 8­Bromoadenosine cAMP inhibited CTGF­stimulated collagen synthesis and transient transfection of RPE cells with a CTGF antisense oligonucleotide inhibited TGF­ß1­induced collagen synthesis. The phosphorylation of PI3K and AKT in RPE cells was promoted by CTGF and TGF­ß1 and the latter promoted the expression of CTGF. The results of the present study indicated that CTGF may promote EMT and ECM synthesis in PVR via the PI3K/AKT signaling pathway and suggested that targeting CTGF signaling may have a therapeutic or preventative effect on PVR.

A modified laser-induced choroidal neovascularization animal model with intravitreal oxidized low-density lipoprotein.

AIM: To investigate whether intravitreal injection of oxidized low-density lipoprotein (OxLDL) can promote laser-induced choroidal neovascularization (CNV) formation in mice and the mechanism involved, thereby to develop a better animal model. METHODS: C57BL6/J mice were randomized into three groups. Immediately after CNV induction with 532 nm laser photocoagulation, 1.0 µL of OxLDL [100 µg/mL in phosphate-buffered saline (PBS)] was intravitreally injected, whereas PBS and the same volume low-density lipoprotein (LDL; 100 µg/mL in PBS) were injected into the vitreous as controls. Angiogenic and inflammatory cytokines were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB) after 5d, and CNV severity was analyzed by choroid flat mount and immunofluorescence staining after 1wk. In vitro, retinal pigment epithelial (RPE) cell line (ARPE19) were treated with OxLDL (LDL as control) for 8h. Angiogenic and inflammatory cytokine levels were measured. A specific inhibitor of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) was used to evaluate the role of LOX1 in this process. RESULTS: At 7d after intravitreal injection of 1 µL (100 µg/mL) OxLDL, T15-labeled OxLDL was mainly deposited around the CNV area, and the F4/80-labeled macrophages, the CD31-labeled vascular endothelial cells number and CNV area were increased. Meanwhile, WB and qRT-PCR results showed that vascular endothelial growth factor (VEGF), CC chemokine receptor 2 (CCR2), interleukin-6 (IL-6), IL-1ß, and matrix metalloproteinase 9 (MMP9) expressions were increased, which was supported by in vitro experiments in RPE cells. LOX1 inhibitors significantly reduced expressions of inflammatory factors IL-1ß and VEGF. CONCLUSION: A modified laser-induced CNV animal model is established with intravitreal injection of 1 µL (100 µg/mL) of OxLDL at 7d, which at least partially through LOX1. This animal model can be used as a simple model for studying the role of OxLDL in age-related macular degeneration.

OxLDL enhances choroidal neovascularization lesion through inducing vascular endothelium to mesenchymal transition process and angiogenic factor expression.

Oxidized lowdensity lipoprotein (OxLDL) can impact the formation of choroidal neovascularization (CNV) via regulating endothelial cell proliferation and secretion of inflammatory and angiogenic factors, but the specific molecular mechanism is not clear. In this study, we evaluated the role of molecular pathways that affect angiogenesis at different stages. In vivo, we found that intravitreal injection of OxLDL following the laser photocoagulation significantly enhanced the CNV size. In vitro experiment confirmed that OxLDL impacts the formation of CNV via regulating endothelial cell proliferation in Rhesus monkey choroid-retinal vascular endothelial cells (RF/6A) and secretion of inflammatory and angiogenic factors. OxLDL promotes angiogenesis through increasing VEGF and some other pro-angiogenic factors expression. Treatment with LY294002, a specific inhibitor of the PI3K pathway, could abrogate VEGF-increased angiogenesis. OxLDL induced the TGF-ß2/Smad signaling axis to participate in the maintenance of neovascular formation. Treatment with PD98059, a specific inhibitor of the MEK pathway, could abrogate it. We also found that OxLDL increased the level of pro-angiogenic factors and promoted the endothelium-mesenchymal transition (EndMT) process, which is important for early tube formation and late maintaining of angiogenesis respectively. In summary, our results indicate that OxLDL affects CNV formation by increasing VEGF expression in the early stage, with activation of the MEK/ERK pathway. And OxLDL induces the TGF-ß2/Smad signaling axis, which leads to EndMT, to affects the later stage of CNV formation by activating the PI3K/AKT pathway.