Progress on the function and mechanism of pigment epithelium derived factor receptors in the occurrence and development of diabetic retinopathy / 中华眼底病杂志

Endogenous pigment epithelium derived factor (PEDF) shows great potential as a drug target for the treatment of diabetes retinopathy (DR) due to its anti-angiogenesis, anti-inflammatory, neuroprotective and neurotrophic effects. PEDF plays a biological role by combining with receptor proteins on cell membrane surface and regulating a variety of signaling pathways. Low density lipoprotein receptor related protein 6 plays a role in inhibiting oxidative stress reaction, inflammatory reaction, and neovascularization of DR. Adipose triglyceride lipase, laminin receptor, plexin domain containing 1 (PLXDC) 1, PLXDC2 and F 1-adenosine triphosphate synthase have the effect of promoting endothelial cell apoptosis, among which PLXDC1 also has neuroprotective effect. By clarifying the receptor that PEDF acts on, exploring the affinity between the receptor and PEDF, the difference in the expression level of each receptor in the process of disease, and the specific function that PEDF plays after binding with specific receptors, we can develop fusion protein drugs for the active domain of high affinity of receptors, have a clearer understanding of the pathogenesis of DR, and take PEDF or PEDF receptor as the target to consolidate the theoretical basis for the development of new therapeutic drugs and strategies for DR.

miR-191 inhibits retinal vascular endothelial cell proliferation and angiogenesis / 中华眼底病杂志

Objective:To observe the inhibitory effect of lentivirus (LV)-mediated miR-191 on the proliferation and angiogenesis of human retinal vascular endothelial cells (hREC) cultured in vitro.Methods:The hREC cell lines were cultured in vitro and divided into control group, hypoxia group, LV-empty vector (LV-vector) group, and LV-miR-191 (LV-191) group. The LV-vector group and LV-191 group were transferred to the corresponding lentiviral vector respectively. Flow cytometry was used to detect cell transfection efficiency. Cell Counting Kit-8 (CCK-8) test was used to detect cell proliferation ability. Scarification test and invasion chamber (Transwell) test were used to detect cell migration ability. Matrigel test was used to detect cell lumen formation ability. Real-time quantitative polymerase chain reaction (qPCR) was used to detect the relative expression of miR-191 and relative mRNA expression of its downstream target genes p21, vascular endothelial growth factor (VEGF), cell division protein kinase (CDK) 6, cyclin-D1 (Cyclin D1). Independent sample t test was used for pairwise comparison. Results:The results of flow cytometry showed that the transfection efficiency of cells in the control group and the LV-191 group were 0.615% and 99.400%, respectively. The results of CCK-8, scarification, Transwell and Matrigel test showed that, compared with the control group, the number of cell proliferation ( t=6.130, 4.606), the cell mobility ( t=4.910, 6.702), the number of stained cells on the microporous membrane ( t=7.244, 6.724) and the lumen formation ability cells ( t=8.345, 9.859) were significantly increased in the hypoxia group and the LV-vector group ( P<0.01), while the LV-191 group showed completely opposite performance ( t=14.710, 6.245, 5.333, 5.892; P≤0.01). The qPCR test results showed that, compared with the control group and the LV-vector group, the relative expression of miR-191 mRNA in the cells of the LV-191 group was significantly up-regulated ( t=44.110, 42.680), the relative expression of Cyclin D1 mRNA ( t=29.940, 14.010) and CDK6 mRNA ( t=15.200, 7.645) decreased significantly, and the difference were statistically significant ( P<0.01); the relative expression of p21 mRNA increased, however, the difference was not statistically significant ( t=2.013, 2.755; P>0.05). There was no significant difference in the relative expression of VEGF mRNA in the 4 groups of cells ( F=0.966, P>0.05). Conclusions:LV-191 can inhibit the proliferation, migration and tubing of hREC by up-regulating p21 and down-regulating CDK6 and Cyclin D1.

Application of proteomics in exploring the inflammatory biomarkers of diabetic retinopathy / 中华实验眼科杂志

Diabetic retinopathy (DR) is a common neurovascular complication of diabetes patients, which seriously threatens the vision health of working-age people and brings a heavy social and economic burden to our society.Most patients with DR have progressed to the stage of proliferative diabetic retinopathy and need to receive intravitreal injection of drugs or surgery but resulting in poor recovery of vision.Therefore, exploring new biomarkers is of great significance for the diagnosis and treatment of early DR.High-throughput proteomics research can examine smaller volumes of biological fluid specimen such as aqueous humor, vitreous humor, tears, and serum, finding differential proteins involved in inflammatory processes in the retina, providing references for the early diagnosis and treatment of DR.Proteomics techniques used for the screening and identification of inflammatory biomarkers in DR in recent years and existing problems were reviewed in this article.

Research of selection and application of diabetic retinopathy animal model / 中华眼底病杂志

According to different experimental methods of induced diabetic retinopathy (DR) and different characteristics of the observed retinopathy, DR animal models can be divided into drug or dietary-induced models, oxygen-induced retinopathy (OIR) models, spontaneous inheritance models, and transgenic models. At present, induced model is one of the most commonly used animal model for DR study, which has the advantages of short modeling cycle, low cost, simple experimental operation and good repeatability. However, the drugs have certain side effects on various organs of animals and the risk of animal death is higher. OIR model has good repeatability, good stability and relatively low cost. However, due to the lack of metabolic changes of hyperglycemia in OIR mice, this model cannot accurately reflect the effects of metabolism on retina under hyperglycemia. The pathological changes of the spontaneous model are relatively stable, however, the application of this model is limited because the genetic homogeneity of diabetes differs from that of human and the cost is high. Transgenic model has definite etiology, however, its application is limited owing to the high cost and the high requirements of technology, operation and equipment. Therefore, researchers should comprehensively consider characteristics and limitations of different models while choosing suitable DR model based on research objectives, observation indicators, experimental conditions, and funds. In addition, animal models that can more accurately simulate DR need to be developed to provide more effective tools for studying the mechanism of DR and developing feasible prevention and treatment approaches.

MiSeq analysis of gene expression profiles in human retinal capillary endothelial cells induced by fulvic acid / 中华眼底病杂志

Objective:To observe the MiSeq sequencing analysis results of fulvic acid (FA) intervention in hypoxia-induced human retinal microvascular endothelial cell (hRMEC) gene expression profile.Methods:hRMEC were cultured in vitro and divided into the hypoxia group (hypoxia treatment) and the FA intervention group (FA intervention after hypoxia). The MTT colorimetric method was used to detect the influence of different concentrations and different modes of FA on hRMEC activity. The optimal concentration of FA was chosen. RT-PCR was used to investigated the effect of FA on hypoxia-induced intercellular adhesion molecule-1 (ICAM-1), IL-1β, IL-4, IL-6, IL-6, IL-8, IL-10, MMP-2, TNF-α, TNF-β, other inflammatory factors in hRMEC, and inflammation-related factors mRNA expression. Cells in the hypoxia group and FA intervention group in the logarithmic growth phase were collected. MiSeq sequencing technology was applyed to complete the whole transcriptome sequencing of the two groups of cells, biological data were obtained, and the differentially expressed miRNA were analyzed on this basis. Gene annotation (GO) functionally significant enrichment analysis and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway significant enrichment analysis were used to analyze the functions and signal pathways of differential miRNAs. The expression of inflammatory factors and inflammation-related factors were compared between groups. The expression level of the corresponding miRNA in the cell was regulated by miRNA mimic, and its effect on cell function was observed, so as to judge the effect of the miRNA.Results:Different concentrations and different modes of action of FA had no effect on the cell viability of hRMEC. The mRNA expression of ICAM-1, IL-1β, IL-6 and TNF-β in the hypoxia group hRMEC were significantly up-regulated compared with the normal group, and the difference was statistically significant ( t=3.426, 6.011, 5.282, 6.500; P=0.027, 0.004, 0.006, 0.003); the mRNA expression of ICAM-1, IL-6, TNF-α and TNF-β in the FA intervention group hRMEC was significantly lower than that of the hypoxia group, and the difference was statistically significant ( t=9.961, 3.676, 3.613, 3.387; P=0.001, 0.021, 0.023, 0.028). There were 14 differentially expressed miRNAs between the hypoxia group and the FA intervention group, of which 9 were up-regulated genes and 5 were down-regulated genes. The predicted target genes of 4 differential miRNAs (hsa-miR-1 285-3p, hsa-miR-30d-3p, hsa-miR-3 170, hsa-miR-7 976) were all ICAM-1. The results of significant enrichment analysis of GO function showed that the functions of differential genes were mainly enriched in the process of cell development, cell differentiation and single organism development. Significant enrichment analysis of the KEGG pathway showed that the differential miRNA expression was highly enriched in the proteoglycan pathway and the cytokine-cytokine receptor interaction pathway in cancer, and the arachidonic acid metabolism pathway and the amphetamine pathway were the more obvious differential expressions. Conclusion:FA may affect the expression level of downstream ICAM-1 mRNA by regulating the expression of multiple miRNAs, thereby affecting the inflammatory state of cells after hypoxia-stimulated hRMEC.

The effects of highly expression of polypyramidine tract binding protein-associated splicing factor on advanced glycation end-products-induced human retinal microvascular endothelial cells / 中华眼底病杂志

Objective:To investigate the protection and the corresponding molecular mechanisms of polypyramidine tract binding protein-associated splicing factor (PSF) overexpression on human retinal microvascular endothelial cells (hRMECs) induced by advanced glycation end-products (AGEs).Methods:The hRMECs were divided into the normal group, the vector group, PSF group, zinc protoporphyrin (ZnPP) group and PSF+ZnPP group for experiment. Cells in the normal group were cultured in a DMEM medium containing 10% fetal calf serum, penicillin/streptomycin, and placed in a closed constant temperature incubator at 37 °C, 95% air, and 5% CO 2. Cells in the vector group were infected with empty lentivirus. The cells in the PSF group were infected with overexpressing PSF lentivirus. Cells in the ZnPP group were treated with ZnPP (10 mol/L) for 2 h. The PSF+ZnPP group cells were infected with overexpressing PSF lentivirus, and then pretreated with ZnPP (10 mol/L) for 2 h. With the last four groups of cells stimulated with AGEs, HE, Hoechst33258 staining and flow cytometry were used to observe the protective effect of high expression of PSF on cell damage and the antagonistic effect of ZnPP on PSF. Western blot was used to detect the protein expression of heme oxygenase-1 (HO-1), phosphorylated (p) extracellular regulatory protein kinase (ERK), and Nrf2 in the cells. U0126, a specific antagonist of ERK pathway, was introduced, and Western blot verified the reversal effect of U0126 on the expression of HO-1 induced by PSF protein. Results:HE staining and Hoechst33258 staining showed that the number of nuclei of damaged cells of PSF group were significantly increased compared with control group, while decreased compared with PSF+ZnPP group ( F=27.5, 38.7; P<0.05). The results of flow cytometry showed that the ROS produced by cells in the PSF group was significantly increased compared to the normal group, and significantly decreased compared to the PSF+ZnPP group, the difference was statistically significant ( F=126.4, P<0.05). Western blot results showed that HO-1 expression of PSF group was significantly increased compared with control and the vector group ( F=70.1, P<0.05). AGEs inducement of 30, 60, 120 and 240 min could significantly improve pERK expression compared with 15 min ( F=474.0, P<0.05). The expression of HO-1 and Nrf2 proteins in the PSF+/U0126- group was significantly more than those in the PSF-/U0126-group, the expression of HO-1 and Nrf2 proteins in the PSF+/U0126+ group was significantly lower than that in the PSF+/U0126- group, and the differences were statistically significant ( F=30.2, 489.4; P<0.05). Conclusion:Over expression of PSF can promote the HO-1 expression by activating ERK pathway and promoting the Nrf2 to the nucleus, thus protect hRMECs against AGEs-induced oxidative damage.

Effects of pyrimidine bundle-binding protein-associated splicing factors on the function of hypoxia-induced human retinal microvascular endothelial cells / 中华眼底病杂志

Objective:To observe the effect of pyrimidine bundle-binding protein-associated splicing factors (PSF) on the function of hypoxia-induced human retinal microvascular endothelial cells (hRMECs).Methods:A three-plasmid system was used to construct lentivirus (LV)-PSF. After LV-PSF infected hRMECs in vitro, the infection efficiency was measured by flow cytometry. Real-time quantitative PCR (RT-PCR) was used to detect the expression of PSF mRNA in hRMECs infected with LV-PSF. The experiment was divided into two parts, in vivo and in vitro. In vivo experiments: 20 healthy C57B/L6 mice at the age of postnatal 7 were randomly divided into normal group, oxygen-induced retinopathy (OIR) group, OIR+LV-Vec group, and OIR+LV-PSF group, each group has five mice. Mice in 3 groups were constructed with OIR models except the normal group and the mice in OIR group were not treated. The mice in the OIR + LV-Vec group and the OIR+LV-PSF group were injected with an empty vector (LV-Vec) or LV-PSF in the vitreous cavity, respectively. The effect of LV-PSF on the formation of retinal neovascularization (RNV) was observed then. In vitro experiments: hRMECs were divided into normal group, hypoxia group, vector group, and PSF high expression group. HRMECs in the normal group were cultured in vitro; hRMECs in the hypoxic group were restored to normal culture conditions for 3 h after 3 h of hypoxia stimulation; hRMECs in the vector group and PSF high expression group were infected with LV-Vec and LV-PSF for 48 h, and hRMECs were returned to normal culture conditions for 24 h with hypoxia stimulation for 3 h. The effect of PSF on cell proliferation was observed by MTT colorimetry. Cell scratch test and Transwell migration experiment were used to observe the effect of PSF on cell migration ability under hypoxia stimulation. RT-PCR was used to observe the mRNA expression of HIF-1α, VEGF and PSF in each group of cells.Results:The LV-PSF of stably expressing PSF was successfully constructed. The infection efficiency was 97% determined by flow cytometry. The level of PSF mRNA in hRMECs infected with LV-PSF was significantly increased and detected by RT-PCR. In vivo experiments: The RNV area of the mice in the OIR group and the OIR + LV-Vec group was significantly increased compared to the normal group ( t=18.31, 43.71), and the RNV area of the mice in the OIR + LV-PSF group was smaller than that in the OIR group ( t=11.30) and OIR + The LV-Vec group ( t=15.47), and the differences were statistically significant ( P<0.05). In vitro experiments: MTT colorimetry results showed that the proliferative capacity of hRMECs in the hypoxic group was significantly enhanced compared with the normal group ( t=2.57), and the proliferative capacity of hRMECs in the PSF high expression group was significantly lower than that of the normal, hypoxic, and vector groups ( t=5.26, 5.46, 3.73), the differences were statistically significant ( P<0.05). The results of cell scratch test showed that the hRMECs could be stimulated by the hypoxia stimulation for 3 hours to restore the normal condition for 24 hours or 48 hours ( t=8.35, 13.84; P<0.05). Compared with the vector group, cell migration rate in the PSF-high expression group was not significant ( t=10.99, 18.27, 9.75, 8.93, 26.94, 7.01; P<0.05). Transwell experiments showed that the number of cells stained on the microporous membrane was higher in the normal group and the vector groups, while the number of cells stained in the PSF high expression group was significantly reduced ( t=9.33, 6.15; P<0.05). The results of RT-PCR showed that the mRNA expression of HIF-1α and VEGF in hRMECs in the hypoxic and vector groups increased significantly compared with the normal group ( t=15.23, 21.09; P<0.05), but no change in the mRNA expression of PSF ( t=0.12, 2.15; P>0.05); compared with the hypoxia group and the vector group, the HIF-1α and VEGF mRNA expression in hRMECs in the PSF high expression group were significantly decreased ( t=10.18, 13.10; P<0.05), but the PSF mRNA expression increased ( t=65.00, 85.79; P<0.05). Conclusion:PSF can reduce the RNV area in OIR model mice. PSF may inhibit hypoxia-induced proliferation and migration of hRMECs through the HIF-1α/VEGF signaling pathway.

Effects of Krüppel-like factor 6 overexpression towards apoptosis of human lens epithelial cells with ultra violetradiation B treatment / 中华实验眼科杂志

Objective To investigate the effect of the overexpression of Krüppel-like factor 6 (KLF6)towards the apoptosis of human lens epithelial cells (HLECs) induced by ultraviolet B (UVB) radiation.Methods The eukaryotic expression plasmid pEGFP-C2-KLF6 which was successfully constructed were transfected into HLECs,followed by the detection of KLF6 level by using Western blot,and then companied by UVB stimulation.Cell viability was measured by methyl thiazolyl tetrazolium (MTT) assay.The morphology of the cells was observed by using hematoxylin-eosin staining method.The cell damage was examined by Live/Dead staining.The apoptotic markers bax and bcl-2 were detected by Western blot.Quantitative apoptotic levels were measured with the apoptosis detection kit;the expression level of reactive oxygen species (ROS) was analyzed by DCFH-DA probe.Results The cell viability of the 0.5 μg transfection group and the 1.0 μg transfection group was significantly lower than that of the blank vector control group (both at P＜0.05).In high KLF6 expression group,the cells were sparse,long and narrow in size and shape,and the cytoplasm was concentrated.The cells in the normal control group were green living cells with stable morphology and even quantity.The number of red dead cells was increased significantly in the KLF6 highexpression group.After UVB irradiation,the apoptosis value,relative bax expression,bax/bcl-2 ratio and ROS expression of HLECs cells in the KLF6 high-expression group were all higher than those in the blank vector control group,with statistically significant differences between them (all at P＜0.05).Conclusions Overexpression of KLF6 can exacerbate apoptosis of HLECs caused by UVB,by regulating the expression of apoptosis-related proteins and promoting the accumulation of ROS in the endoplasmic reticulum.Down-regulation of KLF6 expression by biological tools may play a protective role on LECs to a certain extent.

miR-191 inhibits oxygen-induced retinal neovascularization in mice / 中华眼底病杂志

Objective To observe the inhibitory effect of lentiviral vector miR-191 (LV-191) on retinal neovascularization (RNV) in mice model of oxygen-induced retinopathy (OIR).Methods Eighty healthy 7-day-old C57BL/6J mice were randomly divided into 5 groups including normal group, non-intervention group, normal saline (NS) group, LV-191 group and LV-green fluorescent protein (GFP) group, 16 mice in each group. The OIR model was established in the non-intervention group, NS group, LV-191 group and LV-GFP group. NS group, LV-191 group and LV-GFP group were given an intravitreal injection of 1 μl of NS, LV-191 and LV-GFP at the age of 12 days. No injection was performed in the non-intervention group. In normal group,newborn mouse were maintained in room air form P0 to P17, and no treatment was performed. Mice in all five groups were euthanized at P17. Retinal neovasculation (RNV) was evaluated by counting the number of pre-retinal neovascular cells and analysis of non-perfusion area area by immunofluorescent staining of the mouse retina. Real-time quantitative PCR (RT-PCR) to detect miR -191 and P21 expression of retinal tissue.Results In the LV-191 group, the non-perfusion area were both significantly smaller than those in non-intervention group, NS group and LV-GFP group (F=127.20,P<0.001). The number of pre-retinal neovascular cell nuclei in retinas from LV-191 group were obviously lower than those in the retinas from non-intervention group, NS group and LV-GFP group (F=31.71,P<0.05). RT-PCR showed that the LV-191 and P21 level of LV-191 group increased significantly than other groups (F=10.95, 15.60;P<0.05).Conclusion Intravitreal injection of LV-191 inhibits RNV in mice model of OIR possibly through up-regulating p21.