Effects of angiotensin Ⅱ receptor antagonist on expression of collagen Ⅲ, collagen Ⅴ, and transforming growth factor β1 in the airway walls of sensitized rats

Background Repeated attacks of bronchial asthma lead to different degrees of airway remodeling, the mechanism of which is not yet clear. Some evidences indicate that it is related to the excessive expression of some growth promotion factors. Angiotensin Ⅱ is a polypeptide that may be involved in airway remodeling. To evaluate its role in airway remodeling in asthma, we observed the effects of an angiotensin Ⅱ type 1 receptor antagonist (valsartan) on the expression of collagen Ⅲ, collagen Ⅴ, and transforming growth factor β1 (TGF-β1) mRNA and protein in the airway walls of sensitized rats.Methods Forty Wistar rats were randomly divided into 5 groups: control group, sensitized group, and valsartan groups 1, 2, and 3. The rats in the sensitized group and in valsartan groups 1, 2, and 3 were sensitized and challenged with ovalbumin. Rats in control group were sensitized and challenged with 0.9% NaCl. Rats from valsartan groups 1, 2, and 3 were drenched with valsartan (10 μg, 20 μg, or 30 μg, respectively) at the time of the ovalbumin challenges. The expression of collagen Ⅲ, collagen Ⅴ, and TGF-β1 protein were detected using immunohistochemical method in combination with image analysis methods. The expression of TGF-β1 mRNA was detected by in situ hybridization. Results The expression in the airways of collagen Ⅲ and collagen Ⅴ was significantly higher in rats from the sensitized group (7.73±0.81, 1.34±0.28) and from valsartan groups 1, 2, and 3 (5.73±0.64, 1.13±0.15; 4.96±0.51, 0.98±0.08; 4.43±0.35, 0.93±0.06, respectively) than those in the control group (2.65±0.38, 0.67±0.08, P<0.05). In addition, collagen levels were significantly lower in valsartan groups 1, 2, and 3 than those from the sensitized group (P<0.05). The expression of TGF-β1 mRNA and protein in the airways was significantly higher in rats from the sensitized group (20.49%±3.46%, 29.73%±3.25%) and from valsartan groups 1, 2, and 3 (16.47%±1.94%, 19.41%±1.87%; 14.38%±1.58%, 18.29%±1.43%; 12.96%±1.73%, 18.63%±1.11%, respectively) than that from the control group (7.84%±1.61%, 5.63%±1.07%, P<0.05). TGF-β1 mRNA and protein levels were significantly lower in valsartan groups 1, 2, and 3 than that in the sensitized group (P<0.05). Conclusions Angiotensin Ⅱ receptor antagonist valsartan can suppress synthesis of collagen Ⅲ and collagen Ⅴ by downregulating TGF-β1 mRNA and protein expression. Valsartan can decrease airway remodeling and could play a role in asthma therapy.     

Effect of valsartan-eluting stents on the expression of angiotensin Ⅱ type 2 receptor

Percutaneous coronary intervention （PCI） with drug-eluting stent implantation has been provedefficient to reduce complications and restenosis in type B2/C lesions compared with bare stent, since the major drawback of the latter technique is intimal hyperplasia from the vessel media, which significantly cause in-stent restonosis. Despite the beneficial effects on the renin-angiotensin-aldosterone （RAAS） system, the role of angiotensin-converting enzyme （ACE） inhibitors after PCI is still unclear. However, first results of angiotensin receptor antagonist （valsartan） after stent implantation in the VaI-PREST1 and VALVACE2 trials have indicated the systemic pharmacological effect in the prevention of in-stent-restenosis. Up to our knowledge, whether local treatment of valsartan by implanting drug-eluting stent can generally prevent restenosis by inhibiting intimal hyperplasia has not been explored.     

Effect of irbesartan on angiotensin Ⅱ-induced hypertrophy of human proximal tubular cells

Background Intrarenal activation of the renin angiotensin system (RAS) plays an important role in mediating renal fibrosis. Both angiotensin converting enzyme inhibitors (ACEIs) and angiotensin Ⅱ (AngⅡ) receptor antagonists have been shown to exert a protective role against diabetic and non-diabetic nephropathy. However, the exact mechanism of how blocking local RAS prevents renal fibrosis is unclear. The present study was to investigate the influence of a new AngⅡ receptor antagonist, irbesartan (Irb), on AngⅡ-induced hypertrophy in human proximal tubular cell line (HK-2). Methods The cell line, HK-2, was grown in Dulbeccos’s Modified Eagle’s Medium containing 10% heat-inactivated fetal calf serum. After rested in serum-free medium for 24 hours, the effects of Irb on AngⅡ (10(-7) mol/L)-induced ［3H］-leucine incorporation, total protein content (measured by the Coomassie brilliant blue G250 method), and change in cell size (determined by scanning electron microscopy) were observed. The influence of Irb on the cell cycle was analyzed by fluorescence activated cell sorter (FACS) flow cytometry. Results AngⅡ induced cell hypertrophy in a time and dose dependent manner. Stimulation of cells with AngⅡ for 48 hours resulted in a increase in ［3H］-leucine incorporation ［0 hour: (5584±1016) cpm/10(5)cells vs 48 hours: (10741±802) cpm/10(5)cells, P<0.05］, which was significantly attenuated by treatment with Irb. AngⅡ significantly increased the total protein content in HK-2 cells ［control: (0.169±0.011) mg/10(5)cells vs AngⅡ group: (0.202±0.010) mg/10(5) cells, P<0.05］, which was also markedly inhibited by cotreatment with Irb (P<0.01). Scanning electron microscopy showed that AngⅡ induced an increase in average physical cell size, which was significantly inhibited by Irb ［control: (11.92±1.62) μm; AngⅡ group: (20.63±3.83) μm; AngⅡ+Irb group: (13.59±3.15) μm; P<0.01 vs control, respectively］. Furthermore, flow cytometry revealed that AngⅡ arrested cells in the G0-G1 phase, which was significantly reversed by treatment with Irb ［G0-G1 cells in AngⅡ group: (76.09±1.82)%, in AngⅡ+Irb group: (67.00±2.52)%, P<0.05］.Conclusion Irb can inhibit AngⅡ-induced hypertrophy in HK-2 cells.     

Renoprotective effect of combining angiotensin Ⅱ receptor blockers and statins in diabetic rats

Recent studies suggest that treatment with angiotensin Ⅱ type 1 (AT1) receptor blockers and lipid lowering agents, namely the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins may have beneficial effects on renal function independent of lowering actions on blood pressure and cholesterol. However, the renal effects of the combination of AT1 receptor blockers and statins in experimental diabetes are unknown.     

Effect of transfected angiotensin Ⅱreceptor anti—sense nucleotide on the growth of cardiomyocytes in vitro

AsakeymoleculeinRenin-Angiotensin-System(RAS),AngiotensinⅡ(AngⅡ)playsanimportantroleinthepathogenesisofcongestiveheartfailurethroughitseffectoninducingcardiacmyocytehyper-trophyandmatrixfibrosisafteritiscombinedwithitsspecificreceptor(AT1)［1,2］.Regressionofthecardiomy-ocytichypertrophyhasbecomeanimportantproblemtostudy.Inthiswork,weconstructedaplasmidPAT1Acontaininganti-sensenucleotide,andtransfectedcar-diomyocyteswiththeplasmidtoobserveitsinfluenceonthecellgrowthinordertoacquiremorei…     

Effects of vitamin E on the proliferation and collagen synthesis of rat hepatic stellate cells treated with IL-2 or TNF-α

Objective To study the effects of vitamin E on the proliferation and collagen synthesis of rat hepatic stellate cells treated with interleukin-2 (IL-2 ) or tumor necrosis factor-α (TNF-α). Methods Hepatic stellate cells were isolated from male Sprague-Dawley rats by using modified Friedman’s method. Using the isolated cells cultured and treated with IL-2 or TNF-α, we studied the effects of vitamin E on their proliferation and collagen synthesis through an (3)H-thymidine and (3)H-proline incorporation assay, as well as through observation of these cells under a contrary phase microscope. Results Adding IL-2 increased the both proliferation and collagen synthesis of hepatic stellate cells. Their proliferation was also increased by the addition of TNF-α, although it decreased collagen synthesis. Vitamin E had marked inhibitory effects on the ability of cells treated with IL-2 or TNF-α to reproduce or synthesize collagen. Conclusion Vitamin E can inhibit the proliferation and collagen synthesis of hepatic stellate cells. It is possible that vitamin E affects liver fibrosis through these activities.     

Effect of retinoid X receptor alpha (RXRα) transfection on the proliferation and phenotype of rat hepatic stellate cells in vitro

Objective To study the effect of retinoid X receptor alpha (RXRα) transfection plus treatment with the RXRα ligand, 9-cis-RA, on the proliferation and phenotype of platelet-derived growth factor (PDGF)-activated hepatic stellate cells (HSCs). Methods PDGF activated rat hepatic stellate cells were transfected with eukaryotic expression vector pcDNA3.1- human RXRα, and confirmed by Western blot. Proliferation of transfected HSC was assayed by bromodeoxyuridine (BrdU) incorporation as well as MTT, and the phenotype (α-smooth muscle actin, desmin) was observed by immunocytochemistry with image analysis. Results Transfection of the RXRα gene and treatment with ligand 9-cis-RA of PDGF-activated HSCs extended the increased expression of RXRα protein for at least 168 hours. Cell proliferation and expressions of alpha-smooth muscle actin (α-SMA) and desmin were blocked, compared with groups of sham-transfected, PDGF-activated, no transfection, no ligand treatment, and irrelevant ligand treated HSCs. Conclusion Transfection with the RXRα gene followed by 9-cis-RA ligand treatment will inhibit the proliferation and reverse the phenotype of activated HSC.     

血管紧张素Ⅱ对大鼠肝星状细胞收缩及Rho-Rock通路的影响

目的 探讨血管紧张素Ⅱ(AngⅡ)对大鼠肝星状细胞(HSC)ROCk通路的影响机制.方法 采用HSC-T6细胞株,给予AngⅡμmol/L处理,聚硅酮膜法直观检测HSC的收缩性;另予AngⅡ 10 μmol/L处理,免疫印迹法检测肌球蛋白轻链(MLC)磷酸化的表达水平.观察AngⅡ 1型受体(AT-1受体)阻断剂伊贝沙坦和Rho激酶特异性抑制剂Y27632对磷酸化MLC表达水平的影响;逆转录聚合酶链反应检测Rock通路Rock2(Rho kinase 2)mRNA的表达.结果 AngⅡ可诱导磷酸化MLC蛋白水平的变化,并呈时间依赖性,15min达到峰值后逐渐减低.伊贝沙坦和Y27632处理组可抑制AngⅡ诱导的MLC蛋白磷酸化水平.AngⅡ处理组Rock2 mRNA的表达显著增强,伊贝沙坦和Y27632均可抑制Rock2 mRNA的表达.结论 AngⅡ可以通过Rock通路来诱导HSC的收缩.     

血管紧张素II和洛沙坦对肝星状细胞生长、增殖的影响

目的探讨血管紧张素II(AngII)及其1型受体(AT1a)拮抗剂洛沙坦(losartan),对肝星状细胞(HSCs)生长、增殖的影响。方法①分离大鼠HSCs,培养及鉴定;②在不同浓度的AngII或losartan作用下,观察HSCs生长情况分别绘制细胞生长曲线、采用MTT法、3H-胸腺嘧啶核苷掺入释放法检测AngII或losartan对HSCs生长、增殖的影响。结果AngII刺激组在浓度高于10-9 mol/L时,与对照组相比HSCs数量明显增多,DNA含量显著增加(P<0.05 );losartan在浓度高于10-8 mol / L时,HSCs数量明显减少,DNA含量显著降低(P<0.05 );(losartan AngII)组HSCs数量与对照组相比无显著性差异(P>0.05)。结论AngII可以促使HSCs迅速增殖,其拮抗剂losartan明显抑制HSCs的生长、增殖。     

水飞蓟宾对大鼠肝贮脂细胞HSC-T6增殖和胶原合成的影响

目的：观察水飞蓟宾对大鼠肝贮脂细胞ＨＳＣ－Ｔ６增殖和胶原合成的影响,探讨其保护肝脏及抗硬化机制。方法：采用结晶紫染色法测定细胞增殖,＾３Ｈ－脯氨酸掺入法测定胶原合成。结果：水飞蓟宾（６．２５～５０μｇ／ｍｌ）以浓度依赖方式抑制血清、巨噬细胞条件培养液以及血小板源生长因子或转化生长因子β１诱导的细胞增殖和胶原合成。结论：抑制贮脂细胞增殖和胶原合成可能是水飞蓟宾保护肝脏抗硬化机制之一。     

苦参素对肝星状细胞增殖及凋亡的影响

目的探讨苦参素对肝纤维化发生的作用机制。方法培养激活的HSC-T6分为对照组及实验组,实验组以不同浓度的苦参素干预(分别为30、60、120、240、480、960 mg/L),MTT法检测肝星状细胞的增殖,TUNUL法检测凋亡指数。结果药物干预后肝星状细胞的增殖能力降低,凋亡指数升高,均呈剂量依赖性。结论苦参素能通过抑制肝星状细胞的增殖和促进其凋亡来影响肝纤维化的发展。     

大蒜素对大鼠肝星状细胞基质金属蛋白酶抑制剂-1表达的影响

目的 观察大蒜素对大鼠肝星状细胞（HSC-T6）增殖及细胞外基质降解酶-金属蛋白酶抑制剂-1（TIMP-1）的影响,探讨大蒜素抗肝纤维化的作用及其机制.方法 体外培养大鼠肝星状细胞株HSC-T6.MTT法检测大蒜素作用下对大鼠肝星状细胞增殖的影响、Real-time RT-PCR检测肝星状细胞的TIMP-1mRNA水平、Western blot检测肝星状细胞的TIMP-1蛋白的表达水平.结果 HSC-T6大蒜素处理组与空白对照组比较,增殖抑制率明显提高,差异有统计学意义（P ＜0.01）;TIMP-1的mRNA及蛋白表达水平均明显下降,并且大蒜素浓度增高时,TIMP-1的mRNA及蛋白表达水平则逐渐下降,大蒜素高浓度（24μg/mL）组对TIMP-1的抑制作用明显高于空白对照组,差异有统计学意义（P＜0.05）.结论 大蒜素对HSC-T6增殖和TIMP-1的表达均有抑制作用,为临床开发抗肝纤维化的新药物提供了理论基础.     

核心蛋白聚糖对肝细胞和肝星形细胞体外增殖的影响

目的：探讨核心蛋白聚糖（ｄｅｃｏｒｉｎ）在肝纤维化形成机制中的作用。方法：在正常人肝细胞株Ｌ－０２及大鼠肝星形细胞株ＨＳＣ－Ｔ６体外培养体系中,分别加入不同质量浓度（０．０１,５,１０μｇ／ｍｌ）ｄｅｃｏｒｉｎ共培养不同时间后,进行细胞计数以及＾３Ｈ－ＴｄＲ和＾３Ｈ－Ｌｅｕ掺入量测定。结果：实验组经０．０１μｇ／ｍｌ ｄｅｃｏｒｉｎ作用４ｄ或６ｄ后,ＨＳＣ－Ｔ６和Ｌ－０２细胞增殖数量以及＾３Ｈ－Ｔ     

Expression of AT1amRNA in rat hepatic stellate cells and its effects on cell growth collagen production

Activated hepatic stellate cells (HSCs) play important roles in hepatic fibrosis. Studies on HSCs activation in vitro have shown that this process is regulated by a wide variety of growth factors and cytokines。 Recent data indicate that Ang Ⅱ is responsible for the mechanisms of myocardial fibrosis and kidney fibrosis; but there are only few reports on hepatic fibrosis.