ABSTRACT
The study investigates the mechanism by which Peganum harmala L. (Luotuopeng, LTP) inhibits tube formation in retinal vascular endothelial cells. Tube formation was induced by treatment of retinal vascular endothelial cells with glucose. The cells were divided into a normal group, model group, and an LTP group. The total length of tube formation was measured. The active components, targets, and pathway by which LTP acts in the treatment of diabetic retinopathy was explored by network pharmacology. The mRNA expression levels of targets [extracellular signal-regulated kinase 2 (ERK2), phosphoinositide 3 kinase catalytic alpha polypeptide (PIK3CA), serine/threonine-protein kinase 1 (AKT1)] related to the mitogen-activated protein kinase (MAPK) signaling pathway and vascular endothelial growth factor (VEGF) signaling pathway was measured by real-time PCR. The results of tube formation indicated that compared with the normal group, the total tube length increased in the model group (P < 0.01); after the treatment with LTP, the total tube length decreased compared with the model group (P < 0.01). Network pharmacology revealed that the targets of LTP included PIK3CA, AKT1, and ERK2, and the pathways involved the MAPK signaling pathway and the VEGF signaling pathway. Real-time PCR indicated that compared with the normal group, the mRNA expression levels of ERK2, PIK3CA and AKT1 were elevated in the model group (P < 0.05); after treatment with LTP, the mRNA expression levels of ERK2, PIK3CA and AKT1 decreased compared with the model group (P < 0.05). LTP may inhibit retinal vascular endothelial cell tube formation by regulating the MAPK signaling pathway and the VEGF signaling pathway. This study confirms the multi-targets and multi-pathways of LTP and provides a basis for its use in the treatment of diabetic retinopathy．
ABSTRACT
Background Studies showed that inflammatory process participates in the pathogenesis anddevelopment of diabetic retinopathy targeting retinal vascular endothelial cells (RVECs).A growing body of evidence revealed that metformin reduces the risk of micro-and macro-vascular complications by protecting blood-brain barrier,however,whether it plays a protective effect on human retinal vascular by similar mechanism is still unelucidated.Objective This study was to investigate the effects of metformin on the proliferation,migration and secreting monocyte chemotactic protein-1 (MCP-1) and interleukin-8 (IL-8) of human retinal vascular endothelial cells (RVECs) under the stimulation of tumor necrosis factor-alpha (TNF-α).Methods RVECs were cultured and divided into normal control group,metformin (5 mmol/L) group,TNF-α 2.5 ng/ml group,and TNF-α+metformin (5,10,20 and 40 mmol/L,respectively) groups.Corresponding drugs were added into medium according to grouping for 24 hours.Cell numbers were calculated before and after treatment.The metabolic activity (absorbancy) of RVECs was measured with MTS assay.Cell migration of RVECs was assessed with transwell migration assay.The MCP-1 and IL-8 concentrations in the cell supernatant were detected by ELISA assay.Results The number of the cells was significantly different among the normal control group,metformin group,TNF-α group,and TNF-α+metformin (5,10,20 and 40 mmol/L,respectively) groups (F =189.31,P ＜ 0.01).The metabolic activities of RVECs were 0.32 + 0.02,0.32±0.03,0.97 ± 0.02,0.90 ± 0.05,0.76 ± 0.15,0.74 ± 0.05 and 0.41 ± 0.03;migrated cell numbers were (1 214±49),(1 200±45),(1 648±43),(1 309±48),(1 279±73),(961±60) and (942±106)/field;the concentrations of MCP-1 were (0.385 ±0.050),(0.362±0.060),(2.285 ±0.200),(1.131 ±0.180),(0.622 ± 0.120),(0.537±0.090) and (0.492±0.130) μg/ml,and those of IL-8 were (0.385±0.080),(0.390±0.120),(1.123±0.130),(0.899±0.180),(0.680±0.060),(0.417±0.090) and (0.335±0.100) μg/ml in the normal control group,metformin group,TNF-α group,and TNF-α + metformin (5,10,20 and 40 mmol/L,respectively) groups,showing significant differences among the groups (F =73.31,103.89,150.92,268.32,all at P＜ 0.01).The cell number,cell metabolic activity,migrated cell number,and MCP-1 and IL-8 levels in the cell supernatant were evidently increased in the TNF-α group compared with the normal control group,and those in the TNF-α+10 mmol/L metformin group,TNF-e +20 mmol/L metformin group and TNF-α+40 mmol/L metformin group were significantly decreased in comparison with the TNF-α group (all at P＜0.05).Conclusions Metformin can inhibit TNF-α-induced proliferation,migration and MCP-1 and IL-8 secretion of the cells,and therefore plays a protective role on RVECs in the inflammatory environment.
ABSTRACT
Rhesus retinal vascular endothelial cell line RF/6A cells were treated with human insulin. Cell proliferation, migration, and lumen formation, as well as the expressions of vascular endothelial growth factor-A ( VEGF-A ), VEGF-A receptors, and phosphorylated receptors were measured. Insulin promoted RF/6A cell proliferation, migration, and lumen formation ( all P＜0. 01 ). Insulin increased the expression of VEGF-A mRNA and improved its protein activity ( all P＜0. 05 ), and promoted the expression of VEGFR2 mRNA and its phosphorylation ( both P＜0. 01 ). There was no significant difference in the expression of VEGFR1 mRNA among the groups ( P＞0. 05 ).