ObjectiveTo investigate the effects of interferon gene stimulating protein (STING) inhibitor (C176) on human retinal microvascular endothelial cells (hRMEC) under oxidative stress. MethodsAn animal experimental study. In vivo experiment: 48 healthy male C57BL/6J mice were randomly divided into wild type mice group (WT group) and diabetes (DM) group, with 24 mice in each group. DM mice were induced by streptozotocin to establish DM model. After successful modeling, DM group was divided into DM+dimethyl sulfoxide (DMSO) group and DM+C176 group, with 12 mice in each group. The mice in the DM+DMSO group were intraperitoneally injected with DMSO at the dose of 50 mg/kg. Mice in DM+C176 group were intraperitoneally injected with STING inhibitor C176 750 nmol at the dose of 50 mg/kg. Four weeks after modeling, immunohistochemical staining, Western blot and real-time fluorescence quantitative polymerase chain reaction were used to detect the expression of STING in the retina of WT and DM mice. The leukocyte adhesion test was used to detect the number of leukocytes adhering to hRMEC in mice with WT, DM+DMSO and DM+C176 groups. In vitro experiment: hRMEC was randomly divided into conventional culture cell group (N group), dimethyl sulfoxide (DMSO) group (with DMSO intervention) and C176 group (with C176 intervention). The cells were induced by 150 μg/ml glycation end products for each group. In vitro leukocyte adhesion test combined with 4', 6-diamino-2-phenylindole staining was used to detect the number of leukocytes adhering to hRMEC. The adherent leukocytes were quantitatively analyzed by flow cytometry; H2DCFDA/reactive oxygen species (ROS) fluorescence probe was used to detect ROS expression in cells; Seahorse XFe96 cell energy metabolism analyzer was used to measure the level of intracellular glycolysis. t-test was used to compare the two groups; single factor analysis of variance was used to compare the three groups. ResultsIn vivo experiment: compared with WT group, the expression level of STING (t=73.248) and the relative expression amount of mRNA (t=67.385) in the retina of DM group mice increased significantly (P＜0.05). Compared with WT group, the number of leukocytes adhering to the retinal vessels of mice in DM+DMSO group was significantly increased, while that in DM+C176 group was significantly decreased (F=84.352, P＜0.01). In vitro: compared with N group and DMSO group, the number of leukocyte adhesion on hRMEC in C176 group decreased significantly (F=35.251, P＜0.01). Compared with N group, the number of leukocytes adhering to hRMEC in DMSO group and C176 group decreased significantly (F=26.374, P＜0.01). The ROS level in hRMEC in C176 group was significantly lower than that in N group and C176 group (F=41.362, P＜0.01). Compared with N group and DMSO group, the glycolysis level of hRMEC in C176 group was significantly reduced, with a statistically significant difference (F=68.741, P＜0.01). ConclusionInhibiting the expression of STING in retinal vascular endothelial cells can improve the progress of DM by inhibiting leukocyte adhesion, ROS production and glycolysis level.
ObjectiveTo observe the effects of p21 activated kinase 4 (PAK4) on the mitochondrial function and biological behavior in retinal vascular endothelial cells. MethodsThe experimental study was divided into two parts: in vivo animal experiment and in vitro cell experiment. In vivo animal experiments: 12 healthy C57BL/6J male mice were randomly divided into normal control group and diabetes group, with 6 mice in each group. Diabetes mice were induced by streptozotocin to establish diabetes model. Eight weeks after modeling, quantitative real-time polymerase chain reaction and Western blots were performed to detect the expression of PAK4 in diabetic retinas. In vitro cell experiments: the human retinal microvascular endothelial cells (hRMEC) were divided into three groups: conventional cultured cells group (N group), empty vector transfected (Vector group); pcDNA-PAK4 eukaryotic expression plasmid transfected group (PAK4 group). WB and qPCR were used to detect transfection efficiency, while scratching assay, cell scratch test was used to detect cell migration in hRMEC of each group. In vitro white blood cell adhesion experiment combined with 4 ', 6-diamino-2-phenylindole staining was used to detect the number of white blood cells adhering to hRMEC in each group. The Seahorse XFe96 cell energy metabolism analyzer measures intracellular mitochondrial basal respiration, adenosine triphosphate (ATP) production, maximum respiration, and reserve respiration capacity. The t-test was used for comparison between the two groups. Single factor analysis of variance was used for comparison among the three groups. ResultsIn vivo animal experiments: compared with normal control group, the relative expression levels of PAK4 mRNA and protein in retina of diabetic mice were significantly increased, with statistical significance (t=25.372, 22.419, 25.372; P＜0.05). In vitro cell experiment: compared with the N group and Vector group, the PAK4 protein, mRNA relative expression and cell mobility in the hRMEC of PAK4 group were significantly increased, with statistical significance (F=36.821, 38.692, 29.421; P＜0.05). Flow cytometry showed that the adhesion number of leukocytes on hRMEC in PAK4 group was significantly increased, and the difference was statistically significant (F=39.649, P＜0.01). Mitochondrial pressure measurement results showed that the capacity of mitochondrial basic respiration, ATP production, maximum respiration and reserve respiration in hRMEC in PAK4 group was significantly decreased, with statistical significance (F=27.472, 22.315, 31.147, 27.472; P＜0.05). ConclusionOver-expression of PAK4 impairs mitochondrial function and significantly promotes leukocyte adhesion and migration in retinal vascular endothelial cells.