| Background: Endothelial injury and dysfunction play an important role in atherosclerosis.The renin angiotensin system (RAS) plays a major role in the pathogenesis of cardiovascular diseases . Emerging evidence suggests that angiotensin (AngⅡ)is not the only active peptide of the RAS.Other members of the system; AngⅢ[Ang-(2-8)], AngⅣ[Ang-(3-8)], and Ang-(1-7) may also mediate the actions of the RAS . Studies using the selective Ang-(1-7) antagonist A-779 provide evidence for an Ang-(1-7) receptor distinct from the classical AngⅡreceptors AT1 and AT2. New findings reveal depressor, vasodilator, and antihypertensive actions that may be more apparent in hypertensive animals or humans. Thus, the accumulating evidence suggests that Ang-(1-7) may oppose the actions of AngⅡeither directly or by stimulation of prostaglandins and nitric oxide. A number of studies have proved that oxidatively modified low-density lipoprotein (ox-LDL) is involved in endothelial dysfunction via a lectin-like receptor for ox-LDL (LOX-1) . whether Ang-(1-7) can modulate endothelial LOX-1 expression and endothelial cells apoptosis induced by AngⅡremains to be analyzed.Aim: In this study, we stimulated human umbilical vein endothelial cells (HUVECs) with AngⅡin vitro, to observe the regulation of NF-κB signal activation on LOX-1 expression and endothelial cells apoptosis, to investigate the role of NF-κB signal activation in atherosclerosis, and to clarify the intervention of Ang-(1-7) on HUVFCs, and to determine whether the effect of Ang -(1-7) might be its specific receptor mediated .Method:1. HUVEC were isolated from freshly obtained human umbilical cords by collagenase typeⅡtreatment. The cells were cultured in M1640 supplemented with 10% bovine colf serum and passages 2 to 3 were used in this study.2. HUVECs were incubated by AngⅡ(10-9～10-6mol/L) for 24 hours. LOX-1mRNA expression were measured by RT-PCR. The expression percentage of LOX-1 positive cells and endothelial cells apoptosis were detected by flow cytometry.3. HUVECs were pretreated by NF-κB inhibitor PDTC (1mmol/L)for 30 min, then was incubated with AngⅡ. The effects of PDTC on LOX-1mRNA expression and cells apoptosis were investigated by the same methods above.4. HUVECs were pretreated by Ang-(1-7) (10-9-10-6mol/L) and A-779 for 30 min, then was incubated with AngⅡfor 24h. The effects of Ang-(1-7) on LOX-1mRNA expression and cells apoptosis were investigated by the same methods above. Results:1. AngⅡ(10-9～10-6mol/L) upregulated LOX-1 mRNA (0.758±0.018,0.881±0.015,0.987±0.019,1.090±0.023,vs control 0.387±0.02,P <0.05) and percentage of LOX-1 positive cells expression(17.8%±3.1% vs 22.3%±2.5%,33.2%±3.2%,48.5%±2.75%,62.6%±4.8%,P<0.01),and increased cells apoptosis (5.02±1.01,10.13±2.21,25.60±3.17,19.46±3.09,vs control 2.12±0.24 ,P<0.05),in a dose-dependent manner.2. NF-κB inhibitor PDTC (lmmol/L) attenuated LOX-1 mRNA expression (1.090±0.023 vs AngⅡgroup0.543±0.027, P<0.05)and percentage of LOX-1 positive cells (62.6%±4.8% vs 22.6%±2.3%,P<0.05), and attenuated cells apoptosis(9.32±2.08 vs AngⅡgroup 25.60±3.17, P<0.05).3. Ang-(1-7) (10-9～10-6mol/L) suppressed AngⅡ-induced LOX-1 mRNA expression(1.017±0.01,0.798±0.023,0.619±0.018,0.533±0.011 vs AngⅡgroup1.089±0.012 P<0.05) and percentage of LOX-1 positive cells (56.9%±2.1%,48.9%±1.3%,37.7%±2.5%,22.8%±2.4% vs 62.2%±2.5% P<0.05),and suppressed cells apoptosis (20.04%±2.21%,16.04%±1.32 %,10.04%±2.05,7.79%±1.50% vs AngⅡgroup 25.60%±3.17% ,P<0.05 ), in a dose-dependent manner.4. The effects of Ang-(1-7) could be blocked by A-779( P<0.05).Conclusion:1. AngⅡupregulated LOX-1 expression and increased cells apoptosis which involved in endothelial dysfunction.2. NF-κB plays a critical role in the AngⅡ-induced effects above, the intervention on NF-κB signal may be a target in the prevention and treatment of atherosclerosis.3. And(1-7) has a protective effect on HUVFCs via inhibition of AngⅡinduced LOX-1 expression and apoptosis, suggesting that Ang-(1-7) may play an important role in prevention and treatment of vascular diseases.4. The effect of Ang-(1-7) might be its specific receptor mediated .
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