Zhiming Yang

Angiotensin-(1-7) Attenuates Angiotensin II-Induced ICAM-1, VCAM-1, and MCP-1 Expression via the MAS Receptor Through Suppression of P38 and NF-κB Pathways in HUVECs.

Background/Aims: Atherosclerosis is a chronic inflammatory disease. Intracellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1), and monocyte chemoattractant protein-1 (MCP-1) play important roles in inflammatory processes. P38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB signaling regulate ICAM-1, VCAM-1, and MCP-1 expression. Angiotensin (Ang) II upregulates ICAM-1, VCAM-1, and MCP-1 expression through the P38 MAPK and NF-κB pathways. Ang-(1-7) may oppose the actions of Ang II. We investigated whether Ang-(1-7) prevents Ang II-induced ICAM-1, VCAM-1, and MCP-1 expression in human umbilical vein endothelial cells (HUVECs). Methods: ICAM-1, VCAM-1, and MCP-1 expression was estimated by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA); P38, NF-κB, and p-IκB-a expression was estimated by western blotting. Results: Ang-(1-7) inhibited Ang II-induced ICAM-1, VCAM-1, and MCP-1 expression and secretion in HUVECs. Ang II sharply increased P38 MAPK phosphorylation, which was inhibited by pretreatment with Ang-(1-7). Moreover, Ang-(1-7) significantly inhibited Ang II-induced IκB-a phosphorylation and NF-κB P65 nuclear translocation. The MAS receptor antagonist A-779 abolished the suppressive effects of Ang-(1-7). Conclusion: Ang-(1-7) attenuates Ang II-induced ICAM-1, VCAM-1, and MCP-1 expression via the MAs receptor by suppressing the P38 and NF-κB pathways in HUVECs. Ang-(1-7) might delay the progression of inflammatory diseases, including atherosclerosis.

Angiotensin-(1-7) treatment ameliorates angiotensin II-induced apoptosis of human umbilical vein endothelial cells.

Angiotensin (Ang)‐(1–7), a metabolite of AngI and AngII, is a counter‐regulatory mediator of AngII. In the present study, we investigated the effects of Ang‐(1–7) on AngII‐induced apoptosis in human umbilical vein endothelial cells (HUVEC). To this end, HUVEC were pretreated with 10−9, 10−8, 10−7 or 10−6 mol/L Ang‐(1–7) at for 30 min before being stimulated with 10−6 mol/L Ang‐II for another 24 h. Acridine orange/ethidium bromide and propidium iodide staining were used to analyse the effects of Ang‐(1–7) on AngII‐induced apoptosis. Alone, 10−6 mol/L Ang‐(1–7) had no effect on the apoptosis of HUVEC following exposure of cells for 30 min, whereas AngII (10−6 mol/L, 24 h) significantly enhanced the number of apoptotic cells (P < 0.01). The AngII‐induced apoptosis of HUVEC was suppressed by 10−9–10−6 mol/L Ang‐(1–7). The anti‐apoptotic effects of Ang‐(1–7) were almost completely abolished by A‐779 (10−6 mol/L, 30 min), a specific Mas receptor antagonist. In addition, Ang‐(1–7) inhibited AngII‐induced accumulation of cleaved caspase 3 and enhanced the expression of the anti‐apoptotic factor Bcl‐2 at both the mRNA and protein levels. Angiotensin II upregulated the expression of lectin‐like oxidized low‐density lipoprotein receptor‐1 (LOX‐1), which is involved in endothelial apoptosis, at both the mRNA and protein levels. This effect was blocked by Ang‐(1–7) in a concentration‐dependent manner, although A‐779 almost completely reversed Ang‐(1–7)‐mediated inhibition of AngII‐induced upregulation of LOX‐1. Silencing of LOX‐1 using short interference RNA enhanced the protective effects of Ang‐(1–7) against AngII‐induced apoptosis in HUVEC. Together, the results suggest that Ang‐(1–7) ameliorates AngII‐induced apoptosis of HUVEC at least in part by suppressing LOX‐1 expression.

Amlodipine Treatment Prevents Angiotensin II-induced Human Umbilical Vein Endothelial Cell Apoptosis

BACKGROUND AND AIMS Amlodipine, a long-acting dihydropyridine calcium channel blocker, is able to improve angiotensin II-mediated vascular endothelial dysfunction. However, the underlying mechanism remains not fully understood. In the present study we attempted to determine whether the protective effect of amlodipine against Ang II-induced endothelial impairment was mediated through blockage of endothelial cell apoptosis. METHODS We pretreated human umbilical venous endothelial cells with increasing doses of amlodipine (10(-8)-10(-6) M) followed by the addition of Ang II. Cell apoptosis was assessed by acridine orange/ethidium bromide staining and by annexin-V/propidium iodide double-labeled cytometry. The involvement of the apoptosis regulators, Bcl-2, Bax, and lectin-like oxidized low-density lipoprotein receptor-1, was determined. RESULTS Pretreatment with amlodipine resulted in a dose-dependent suppression of Ang II-induced HUVEC apoptosis. Moreover, the Bcl-2/Bax ratio was found to be increased in cells pretreated with amlodipine, indicating an enhanced anti-apoptosis potential. Additionally, the induction of LOX-1 by Ang II was remarkably counteracted by the pre-exposure to amlodipine. CONCLUSIONS Our data demonstrate that amlodipine ameliorates Ang II-induced endothelial apoptosis, which is likely associated with the elevation of Bcl-2/Bax ratio and reduction of the LOX-1 expression.

Angiotensin-(1–7) upregulates expression of adenosine triphosphate-binding cassette transporter A1 and adenosine triphosphate-binding cassette transporter G1 through the Mas receptor through the liver X receptor alpha signalling pathway in THP-1 macrophages treated with angiotensin-II

Adenosine triphosphate‐binding cassette transporter A1 (ABCA1) and ABCG1 play crucial roles in reverse cholesterol transport, and have anti‐atherosclerosis effects, and liver X receptor alpha (LXRα) can stimulate cholesterol efflux through these transporters. Angiotensin (Ang)‐(1–7) can protect endothelial cells, inhibit smooth muscle cell growth, ameliorate inflammation and exert anti‐atherosclerotic effects. In the present study, we attempted to clarify the effect of Ang‐(1–7) on expression of ABCA1 and ABCG1, and explored the role of LXRα in the regulation of ABCA1 and ABCG1 in THP‐1 macrophages that had been incubated with angiotensin‐II (AngII). Ang‐(1–7) increased ABCA1 and ABCG1 expression in a concentration‐dependent manner at both the mRNA and protein levels, promoted cholesterol efflux, and decreased cholesterol content in THP‐1 macrophages treated with AngII. Furthermore, Ang‐(1–7) upregulated the expression of LXRα in a concentration‐dependent manner in these cells. LXRα small interfering RNA, as well as the Mas receptor antagonist A‐779, completely abolished these effects of Ang‐(1–7). In summary, Ang‐(1–7) upregulates ABCA1 and ABCG1 expression in THP‐1 macrophages treated with AngII through the Mas receptor, via the LXRα pathway. This novel insight into the molecular mechanism underlying Ang‐(1–7) and AngII interaction could prove useful for developing new strategies for treatment of cardiovascular diseases.