ABSTRACT
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.Methods:Experimental 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.Results:In 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. Conclusion:Met can down regulate the expression of NLRP3 inflammatory body related factors in hRMEC and inhibit pyroptosis.
ABSTRACT
Objective:To observe the effects of p21 activated kinase 4 (PAK4) on the mitochondrial function and biological behavior in retinal vascular endothelial cells.Methods:The 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. Results:In 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). Conclusion:Over-expression of PAK4 impairs mitochondrial function and significantly promotes leukocyte adhesion and migration in retinal vascular endothelial cells.