Effect of valsartan on the expression of angiotensin II receptors in the lung of chronic antigen exposure rats

Background Many studies have suggested that angiotensin Ⅱ （Ang Ⅱ） and its receptors may be involved in the development of asthma. However, the expression of angiotensin Ⅱ receptors （AGTR） is not clear in the lung tissue of chronic asthmatics. This study was designed to determine the relationship between airway remodeling, dysfunction and the expression of AGTRs in a rat model of asthma. Methods Rats were sensitized with ovalbumin （OVA） for 2 weeks. Sixty minutes before an inhalation challenge, the rats were pretreated either with valsartan （15, 30, 50 mg.kg-1.d-1） or saline intragastrically. Then the rats received an OVA challenge for 30 alternative days. Acetylcholine （Ach）-induced bronchoconstriction was measured after the final antigen challenge. White cell counts in bronchoalveolar lavage fluid （BALF） and morphological changes in the airways were then assessed. The levels of transforming growth factor-beta 1 （TGF-β1） and platelet-derived growth factor （PDGF） in BALF were detected by ELISA. The levels of AGTR1 and AGTR2 mRNA and protein in lung tissues were measured by RT-PCR and Western blotting. Results AGTR1 mRNA and protein levels in repeatedly OVA-challenged rats were significantly increased as compared with negative controls. The AGTR1 mRNA expression versus white cell counts of BALF and airway wall thickness （mainly in small airways） in lungs of chronic antigen-exposed rats were positively correlated. Valsartan decreased the level of AGTR1 in repeatedly OVA-challenged rats. However, AGTR2 mRNA and protein levels in the OVA-challenged rats and high-dose valsartan-treated rats （50 mg.kg-1.d-1） were also increased. Valsartan significantly decreased inflammatory cell accumulation and attenuated Ach-evoked bronchoconstriction in repeatedly antigen-challenged rats. Valsartan also decreased allergen-induced structural changes in rat airway （including total airway wall thickness and smooth muscle area） and the levels of TGF-β1 and PDGF in BALE Conclusions AGTR1 expression is potentially associated with airway remodeling and dysfunction in asthma. Ang Ⅱ and AGTR1 may participate in airway inflammation and airway remodeling of chronic antigen-exposed rats. Valsartan, a AGTR1 antagonist, could inhibit AGTR1 expression and partially inhibits structural airway changes as well as airway inflammation in chronic OVA-exposed rats.

Clinical evaluation of valsartan and metoprolol tartrate in treatment of diabetic nephropathy with positive β1-adrenergic and anti-angiotensin Ⅱ type 1 receptor antibody

Background Studies have confirmed that angiotensin II receptor blocker （ARB） and angiotensin converting enzyme inhibitors （ACEI） in the treatment of diabetic nephropathy （DN） has special advantages. We observed the effects of valsartan and metoprolol tartrate hydrchloride in treatment of DN patients with positive β1-adrenergic and anti-angiotensin II type 1 （AT1） receptor antibody. Methods The epitopes of the second extracellular loop of β1 receptor （197-222） and AT1 receptor （165-191）, were synthesized and used respectively to screen serum autoantibodies from patients with DN （n=371, group A）, diabetes mellitus （DM） without renal failure （n=107, group B） and healthy blood donors （n=47, control, group C） by enzyme-linked immunosorbent assay （ELISA）. Metoprolol tartrate 25-50 mg, three times per day, valsartan 160 mg, once a day, aspirin 100 rag, once a day, and nitrendipine 10-20 mg, three times per day, were given to DN patients with positive or negative autoantibodies. The cystatin C level and 24-hour urinary protein were measured before and after treatment. Results In DN patients, the positive rate of the autoantibodies against β1 receptors and AT1 receptor was 47.7% and 51.5%, respectively, which were significantly higher than those in DM patients and healthy controls （all P 〈0.01）. Patients with anormalous cystatin C had higher positive rates of the autoantibodies than patients with normal cystatin C. Valsartan and metoprolol tartrate reduced proteinuria significantly （P 〈0.01） in DN patients with positive autoantibodies. Conclusions The findings suggest that these autoantibodies against β1 and ATl-receptor may play important roles in the pathogenesis of DN. Valsartan and metoDrolol tartrate are effective and safe in the treatment of DN.

肾素-血管紧张素系统阻断剂与代谢综合征患者脂联素水平的关系

目的探讨肾素-血管紧张素系统(RAS)阻断剂与代谢综合征(Mets)患者血浆脂联素水平的关系。方法53例Mets患者随机分为3组,ACEI组15例予贝那普利(5 mg/d),ARB组15例予坎地沙坦(4 mg/d),对照组23例避免应用影响RAS的相关药物,服药期为4周,检测并比较治疗前后血浆脂联素(APN)、空腹血糖(FBG)、空腹胰岛素(FINS)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、肌酐(CR)、丙氨酸转氨酶(ALT)、胆红素(BIL)和胰岛素抵抗指数(HOMA-IR)的水平。结果ACEI组的FBG和LDL-C、ARB组的CR治疗后低于治疗前(P<0.05);ACEI组和ARB组APN水平治疗后高于治疗前(P<0.01),而3组中FINS、HOMA-IR、TC、ALT和BIL在治疗前后变化差异无统计学意义(P>0.05)。治疗前CR、TC、ALT和BIL是APN水平的影响因素;治疗后FBG和TC是APN水平的影响因素。结论APN可能是ACEI和ARB治疗Mets及其并发症的潜在靶点。

氯沙坦通过下调单核细胞趋化蛋白1受体表达抑制单核细胞活化

目的探讨血管紧张素Ⅱ对单核细胞趋化蛋白1受体CCR2表达的影响及氯沙坦的干预作用。方法人单核细胞株与血管紧张素Ⅱ(10-7mol/L)孵育,加或不加氯沙坦(10-7、10-6和10-5mol/L),检测上清液中单核细胞趋化蛋白1水平、单核和内皮细胞粘附情况以及CCR2mRNA的表达。结果与对照组比较,血管紧张素Ⅱ明显增加单核细胞培养上清液中单核细胞趋化蛋白1水平(26.46±3.58ng/L比10.56±2.34ng/L,P<0.01),增加单核内皮细胞间粘附(596±27比268±16,P<0.01)。血管紧张素Ⅱ刺激细胞后明显上调CCR2mRNA表达,氯沙坦能显著抑制血管紧张素Ⅱ的作用,降低单核细胞趋化蛋白1的水平,减少单核内皮细胞间粘附,下调CCR2 mRNA表达。结论氯沙坦通过下调单核细胞趋化蛋白1受体CCR2基因表达抑制单核细胞活化。

ACEI、ARB及醛固酮受体拮抗剂在心力衰竭患者中的应用

采用血管紧张素转换酶抑制剂(ACEI)、血管紧张素受体拮抗剂(ARB)或醛固酮受体拮抗剂,阻断或削弱肾素-血管紧张素-醛固酮系统的活性,是治疗慢性心力衰竭的主要策略之一。经过10多年的临床试验和实践,这3类药物的适应证和应用要点都已基本明确。ACEI是治疗慢性收缩性心力衰竭的基石和首选药物,ARB主要适用于不能耐受ACEI的患者。醛固酮受体拮抗剂的适应证为严重心力衰竭患者和心肌梗死后心力衰竭,使用时必须密切监测血钾和肌酐水平。

血管紧张素Ⅱ受体阻滞剂治疗肥厚型心肌病的Meta分析

目的 使用Meta分析的方法评价血管紧张素Ⅱ受体拮抗剂（ARBs）类药物对肥厚型心肌病（HCM）的疗效.方法 检索Web of Science、PubMed、EMBASE、Cochrane Central Register of Controlled Trials、中国知网（CNKI）、中国生物医学文献光盘数据库（CBMdisk）的文献,纳入与安慰剂或常规治疗相比较的临床随机对照试验,分析ARB类药物治疗HCM的效果.结果 包括228例患者的6个随机对照试验纳入Meta分析.研究显示,ARB类药物对左室射血分数、二尖瓣舒张早期最大血流速度（E）和舒张晚期最大血流速度（A）及左室质量的影响未见统计学差异.结论 ARB类药物对于HCM患者的心脏功能可能没有影响.

Different effects of telmisartan and valsartan on human aortic vascular smooth muscle cell proliferation

Background Vascular smooth muscle cell proliferation is an important process in the development of atherosclerosis and is associated with other cellular processes in atherogenesis. Telmisartan is reported to have partial peroxisome proliferator-activated receptor （PPAR）-γ activating properties and has been referred to as selective PPAR modulators, but valsartan just blocks angiotensin II （Angll） type 1 （AT1） receptors. This study aimed to compare the different effects of telmisartan and valsartan on human aortic smooth muscle cells （HASMCs） proliferation. Methods Ability of telmisartan and valsartan to inhibit proliferation of HASMCs was evaluated by the Cell Counting Kit-8 （CCK-8） in continuous cell culture. Whether the antiproliferative effects of telmisartan and valsartan depend on their effects on Angll receptors or activating the peroxisome PPAR-y was also investigated in this study. Results Telmisartan inhibited proliferation of HASMCs by 52.4% （P 〈0.01） at the concentration of 25 μmol/L and the effect depended on the dose of telmisartan, but valsartan had little effect on HASMCs proliferation （P 〉0.05） and no dose response. When tested in cells stimulated with Angll, telmisartan had the same inhibition of HASMCs by 59.2% （P 〈0.05） and valsartan also inhibited it by 41.6% （P 〈0.05）. Telmisartan and valsartan had the same effect on down-regulating AT1 receptor expression and telmisartan was superior to valsartan up-regulating Angll type 2 （AT2） receptor expression. Antiproliferative effects of telmisartan were observed when HASMCs were treated with the PPAR-y antagonist GW9662 but antiproliferative effects of the PPAR-y activator pioglitazone were not observed. Conclusions Telmisartan, but not valsartan, inhibits HASMCs proliferation and has dose-dependent response without stimulation of Angll. AT2 receptor up-regulation of telmisartan contributes to its greater antiproliferative effects than valsartan. Its PPAR-y activation does not play a critical role in inhibiting HASMCs proliferation.

Angiogenesis related gene expression profiles of EA.hy926 cells induced by irbesartan： a possible novel therapeutic approach

Background Angiogenesis occurs commonly in various physiological and pathological processes. Improving blood supply through promoting angiogenesis is a novel approach for treating ischemic diseases. Angiotensin II type 1 receptor blockers （ARBs） dominate the management of hypertension, but evidence of their role in angiogenesis is contradictory. Here we explored the angiogenic effects of ARBs through characterizing gene expression of the human umbilical vein endothelial cell line EA.hy926 exposed to irbesartan. Methods The human umbilical vein endothelial cell line EA.hy926 was grown for 72 hours after treatment with different concentrations of irbesartan. The cell proliferative capacity was assessed by CCK8 assay at 24, 48 and 72 hours. Gene expression levels in EA.hy926 cells responding to irbesartan were measured under optimal proliferation conditions by microarray analysis using Affymetrix U133 plus 2.0. The differential expression of genes involved in angiogenesis was identified through cluster analysis of the resulting microarray data. Quantitative RT-PCR and Western blotting analyses were used to validate differential gene expression related to the angiogenesis process. Results In the 104, 105, 106 mol/L treatment groups, cell proliferation studies revealed significantly increased proliferation in EA.hy926 cells after 24 hours of irbesartan treatment. However, after 48 and 72 hours of treatment with different concentrations of irbesartan, there was no significant difference in cell proliferation observed in any treatment group. We selected the group stimulated with irbersartan at a concentration of 10.6 mol/L for microarray experiments. Statistical analysis of the microarray data resulted in the identification of 56 gene transcripts whose expression patterns were significantly correlated, negatively or positively, with irbesartan treatment. Cluster analysis showed that these genes were involved in angiogenesis, extracellular stimulus, binding reactions and skeletal system morphogenesis. Of these 56 genes we identified seven genes （VEGF, KDR, PTGS2, PLXND1, ROB04, LM02, and COL5A1） involved in the angiogenesis process, qRT-PCR analysis of these genes confirmed the microarray results. Protein expression of three VEGF pathway genes （VEGF, KDR, and PTGS2） was further confirmed by Western blotting. Conclusions Our study showed that irbesartan may induce angiogenic effects in vascular endothelial cells. It suggested that the mechanism of angiogenic effects of ARBs might be attributed to the signaling cascade from angiotensin receptors in the VEGF pathway. It also provided evidence indicating that ARBs could be used as a novel therapeutic approach to treat chronic ischemic heart disease as well as anti-hypertensive agents.

肾素-血管紧张素系统对胰岛β细胞功能的影响及AT1R在其中的作用机制

目的研究血管紧张素Ⅱ对胰岛β细胞的分泌、增殖、凋亡、氧化应激和纤维化的作用。方法应用βTC3细胞株、Western印迹检测、实时定量PCR检测、共聚焦显微镜监测Furo3标记的细胞内游离钙离子荧光强度的变化和流式细胞仪检测细胞凋亡及活性氧簇（ROS）产生等方法，研究血管紧张素Ⅱ对β细胞功能的影响，并进一步通过RNA干扰技术减少β细胞中AT1R的表达，研究AT1R在其中的作用机制。结果βTC3细胞在高浓度葡萄糖刺激下胰岛素分泌增加4倍。高糖作用可引起细胞内Ca^2＋荧光强度急剧增加。血管紧张素Ⅱ急性刺激并不直接引起胰岛素分泌的改变，其对β细胞促分泌作用可能与其促增殖功能相关。血管紧张素Ⅱ部分是通过AT1R和蛋白激酶C介导的NAD（P）H途径在β细胞中引起氧化应激。RNAi减少AT1R的表达可以改善血管紧张素Ⅱ引起的细胞凋亡和纤维化。结论血管紧张素Ⅱ通过其1型受体在β细胞的激素分泌、增殖、氧化应激、凋亡和纤维化等过程中发挥着重要作用。