ObjectiveTo observe the effect of exosomes secreted by retinal pigment epithelial (RPE) cells which damaged by blue light to Nod-like receptor protein (NLRP3).MethodsCultured ARPE-19 cells were divided into 2 groups; one group of RPE cells were exposed to blue light irradiation for 6 hours, the other group was cultured in routine environment. Total exosomes were extracted from the two groups by differential ultracentrifugation in low-temperature, and examined by transmission electron microscope to identify their forms. The exosomes were then incubated with normal ARPE-19 cells. The expression level of CD63, interleukin (IL)-1β, IL-18 and caspase-1 on the exosome surface were measured by Western blotting. The expressions of NLRP3 mRNA in RPE cells were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction (RT-PCR).ResultsBlue light damaged the cellular morphology. Transmission electron microscopy showed that the exosomes were 50-200nm in diameter and like double-concave disks. Blue light damaged cell-derived exosomes had significantly higher expression of IL-1β (t=18.04), IL-18 (t=12.55) and caspase-1 (t=14.70) than the control group (P＜0.001). ARPE-19 cells cultured with blue light damaged cell-derived exosomes also had significantly higher expression of IL-1β (t=18.59), IL-18 (t=23.95) and caspase-1 (t=35.27) than control exosomes (P＜0.001). RT-PCR showed that the relative expression of NLRP3 mRNA of PRE cells in experimental group and control group were 1.000±0.069 and 0.2±0.01, respectively, the difference was significant (t=12.20, P＜0.001).ConclusionThe expression IL-1β, IL-18 and caspase-1 and NLRP3 mRNA were upregulated by exosomes secreted by blue light damaged-RPE cells.
Objective To observe the effect of metformin (Met) on inflammatory bodies and focal death in human retinal microvascular endothelial cells (hRMEC) in diabetes mellitus (DM) microenvironment. MethodsExperimental research was divided into in vivo animal experiment and in vitro cell experiment. In vivo animal experiments: 9 healthy C57BL/6J male mice were randomly divided into DM group, normal control group, and DM+Met group, with 3 mice in each group. DM group and DM+Met group mice were induced by streptozotocin to establish DM model, and DM+Met group was given Met 400 mg/ (kg · d) intervention. Eight weeks after modeling, the expression of NLRP3, cleaved-membrane perforating protein D (GSDMD) and cleaved-Caspase-1 in the retina of mice in the normal control group, DM group and DM+Met group were observed by immunohistochemical staining. In vitro cell experiments: hRMEC was divided into conventional culture cell group (N group), advanced glycation end products (AGE) group, and AGE+Met group. Joining the AGE, AGE+Met groups cells were induced by 150 μg/ml of glycation end products, and 2.0 mmol/L Met was added to the AGE+Met group. Pyroptosis was detected by flow cytometry; 2',7'-dichlorofluorescein diacetate (DCFH-DA) fluorescent probe was used to detect the expression of reactive oxygen species (ROS) in cells of each group. Real-time fluorescence quantitative polymerase chain reaction and Western blot were used to detect the relative mRNA and protein expression levels of NLRP3, cleaved-GSDMD, cleaved-Caspase-1 in each group of cells. Single factor analysis of variance was used for comparison among the three groups. ResultsIn vivo animal experiments: compared with the DM group, the expression of NLRP3, cleaved-GSDMD, and cleaved-Caspase-1 in the retina of normal control group and DM+Met group mice was significantly reduced, with significant difference among the 3 groups (F=43.478, 36.643, 24.464; P＜0.01). In vitro cell experiment and flow cytometry showed that the pyroptosis rate of AGE group was significantly higher than that of N group and AGE+Met group (F=32.598, P＜0.01). The DCFH-DA detection results showed that the intracellular ROS levels in the N group and AGE+Met group were significantly lower than those in the AGE group, with the significant difference (F=47.267, P＜0.01). The mRNA (F=51.563, 32.192, 44.473; P＜0.01) and protein levels (F=63.372, 54.463, 48.412; P＜0.01) of NLRP3, cleaved-GSDMD, and cleaved-Caspase-1 in hRMEC of the AGE+Met group were significantly reduced compared to the N group. ConclusionMet can down regulate the expression of NLRP3 inflammatory body related factors in hRMEC and inhibit pyroptosis.