肾上腺髓质素对血管外膜成纤维细胞迁移及胶原生成的影响

目的:探讨肾上腺髓质素(ADM)对血管紧张素Ⅱ(AngⅡ)诱导的血管外膜成纤维细胞(AF)迁移及胶原生成的影响及机制。方法:体外培养大鼠胸主动脉AF,运用Trans well技术测定不同浓度ADM对AF迁移的影响,采用酶联免疫吸附法(ELISA)测定培养上清中Ⅰ、Ⅲ型胶原蛋白含量,用RT-PCR及Western blotting分析AngⅡ(10-6mol/L)及不同浓度ADM干预后大鼠胸主动脉AF内骨桥蛋白(OPN)、转化生长因子β1(TGFβ1)mRNA及蛋白的表达。结果:在AngⅡ(10-6mol/L)趋化作用下,AF迁移数目较对照组显著增多[(30.26±1.08)∶(4.35±1.26),P<0.01]。ADM可抑制AngⅡ刺激的细胞迁移,迁移细胞数目在一定范围内随着ADM浓度增加而减少;AngⅡ(10-6mol/L)诱导OPN呈高表达,ADM可下调这种表达,呈一定剂量依赖性;AngⅡ显著增加培养上清中Ⅰ、Ⅲ型胶原蛋白含量,ADM呈剂量依赖的抑制AngⅡ上述作用,其中10-8mol/LADM组中Ⅰ、Ⅲ型胶原合成分别抑制了30%和31%(P<0.01),10-7mol/LADM组则分别抑制了43%和4...     

肾上腺髓质素对大鼠血管外膜成纤维细胞迁移的影响

目的研究肾上腺髓质素（ADM）对血管紧张素II（Ang II）诱导的大鼠胸主动脉外膜成纤维细胞迁移的影响。方法采用体外培养的大鼠胸主动脉外膜成纤维细胞,运用Transwell技术测定不同浓度ADM对外膜成纤维细胞迁移的影响,用RT-PCR及Western blotting分析Ang II（1×10-6mol/L）及不同浓度ADM干预后大鼠胸主动脉外膜成纤维细胞内骨桥蛋白的表达。结果在Ang II（1×10-6mol/L）趋化作用下,外膜成纤维细胞迁移活性较对照组显著增强,ADM可抑制Ang II刺激的细胞迁移,迁移细胞数目在一定范围内随着ADM浓度增加而减少;Ang II（1×10-6mol/L）诱导骨桥蛋白呈高表达,ADM可下调这种表达,呈一定剂量依赖性。结论ADM明显抑制Ang II刺激的外膜成纤维细胞迁移,并且ADM可以抑制Ang II刺激的骨桥蛋白表达。     

血管紧张素Ⅱ对人肾成纤维细胞的影响

目的：观察血管紧张素Ⅱ（ＡｎｇⅡ）对人肾成纤维细胞（ＫＦＢ）的影响。方法：采用ＥＬＩＳＡ法,四甲基偶氮唑蓝（ＭＴＴ）法、流式细胞仪、免疫组织化学法分别检测ＡｎｇⅡ对ＫＦＢ分泌的胶原酶活性、ＫＦＢ增生、凋亡、Ⅰ型胶原表达的影响。结果;ＡｎｇⅡ能提高ＫＦＢ分泌的总胶原活性、促进味道一、抑制ＫＦＢ凋亡、促进ＫＦＢⅠ型胶原的表达。结论：ＡｎｇⅡ能通过促进ＫＦＢ增生、抑制ＫＦＢ凋亡、促进ＫＦＢⅠ型胶原的表达     

松弛素对血管紧张素Ⅱ诱导的大鼠血管外膜成纤维细胞胶原水平的影响

目的:探讨松弛素(RLX)对血管紧张素(Ang)Ⅱ诱导的大鼠血管外膜成纤维细胞胶原水平的影响及机制。方法:体外培养大鼠主动脉外膜成纤维细胞,随机分为对照组、AngⅡ组(10-6 mmol/L),RLX组(100μg/L)及AngⅡ+RLX组。采用波形蛋白染色法鉴定血管外膜成纤维细胞,用RT-PCR检测Ⅰ、Ⅲ型胶原蛋白mRNA表达,用Western blot印迹法检测基质金属蛋白酶(MMP)-2、MMP-9及转化生长因子(TGF)-β1蛋白的表达。结果:AngⅡ可显著增加培养液上清中Ⅰ、Ⅲ型胶原蛋白含量及TGF-β1蛋白表达,而RLX明显抑制AngⅡ的上述作用;AngⅡ可显著下调细胞内MMP-2和MMP-9的蛋白表达,而RLX明显抑制AngⅡ的上述作用(均P<0.05)。结论:AngⅡ可刺激血管外膜成纤维细胞胶原合成增加,而RLX通过上调MMP-2、MMP-9表达和下调TGF-β1表达,抑制AngⅡ刺激的Ⅰ、Ⅲ型胶原蛋白生成,从而发挥抗血管纤维化作用。     

肾上腺髓质素抑制血管紧张素Ⅱ刺激血管平滑肌细胞增生作用

目的　观察肾上腺髓质素 (adrenomedullinADM)对血管紧张素Ⅱ (AngⅡ )刺激血管平滑肌细胞增生作用的影响。方法　测定ADM、AngⅡ对细胞3H leu掺入及 (MAPK)和 (PKC)活性的作用。结果　AngⅡ促进细胞3H leu掺入及MAPK和PKC活性增加 ;ADM对细胞3H leu掺入及MAPK、PKC活性均无明显影响 ,但呈浓度依赖方式抑制AngⅡ促细胞3H leu掺入及MAPK活性增加。结论　ADM通过抑制AngⅡ对MAPK的激活 ,拮抗其促血管平滑肌细胞增生作用。     

妊娠期高血压疾病患者血浆肾上腺髓质素和血管紧张素Ⅱ的变化

目的 探讨肾上腺髓质素(ADM)及血管紧张素Ⅱ(AngⅡ)在妊娠期高血压疾病患者和正常晚孕期妇女及未妊娠妇女血浆中含量的变化.方法 采用放射免疫法测定妊娠期高血压疾病患者、正常晚孕期妇女及未妊娠妇女血浆中ADM及AngⅡ含量.结果 妊娠期高血压疾病组血浆ADM和AngⅡ的含量明显高于正常妊娠组(P<0.05);妊娠期高血压疾病患者血浆ADM和AngⅡ水平:子痫前期重度>子痫前期轻度>妊娠期高血压,三者间比较,差异有统计学意义(P<0.05).未妊娠组与正常妊娠组血浆ADM与AngⅡ两组比较具有统计学意义(P<0.05).结论 ADM与AngⅡ参与妊娠期高血压疾病的病理生理过程,血浆ADM升高可能与AngⅡ含量升高有关.     

血管紧张素Ⅱ及其受体拮抗剂对血管外膜成纤维细胞亚群增殖和胶原合成的影响

目的探讨血管紧张素Ⅱ(AngⅡ)及其受体拮抗剂氯沙坦(Los)和PD123319对大鼠胸主动脉血管外膜成纤维细胞亚群增殖和胶原生成的影响。方法通过克隆环法获得血管外膜成纤维细胞单克隆,根据细胞表型克隆了两种细胞亚型并分别进行培养,逆转录聚合酶链反应(RT-PCR)和免疫荧光染色方法鉴定细胞的纯度;流式细胞术对两细胞亚群的形状和大小进行比较;四甲基偶氮唑盐(MTT)法和Western印迹法检测AngⅡ及其受体拮抗剂Los、PD123319对细胞亚群的增殖活性和Ⅰ型胶原(CollagenⅠ)合成的影响。结果克隆环法获得血管外膜成纤维细胞两个亚群,经显微镜和流式细胞仪观察根据细胞表型分别命名为:圆形细胞亚群(RC)和纺锤形细胞亚群(SC)。经RT-PCR和免疫荧光染色对第Ⅷ因子(vWF)、CD8、MHC、Desmin进行检测,结果显示无内皮细胞、平滑肌细胞细胞标志物的表达,分别为两种纯系细胞。实验发现AngⅡ对RC亚群的增殖活性及CollagenⅠ的合成能力均有显著影响,既促进RC的增殖又提高Ⅰ型胶原的合成,但经Los预处理后,AngⅡ的促增殖及胶原合成能力被显著性抑制(P<0.05),而SC亚群的增殖活性和胶原合成情况无显著性改变。经PD123319预处理后,对RC亚群和SC亚群增殖和胶原的合成均无明显影响。结论 AngⅡ在促进两细胞亚群的增殖和胶原合成的能力方面有差异,说明血管外膜成纤维细胞两种亚群在表型、功能和作用机制上具有显著性的差异,提示两种细胞亚群在病理生理机制及其血管重构和修复过程中扮演着不同的角色。     

血管紧张素Ⅱ诱导血管外膜成纤维细胞产生结缔组织生长因子

目的 研究血管外膜成纤维细胞(AF)能否产生结缔组织生长因子(CTGF)，以及血管紧张素Ⅱ(AngⅡ)对CTGF的影响。方法 组织贴片法培养WKY大鼠主动脉AF，经AngⅡ(10^-7～10^-9mol／L)处理，应用免疫细胞化学和Western blot的方法，观察CTGF的表达，及AT1受体阻断剂氯沙坦和AT2型受体阻断剂PD123319干预后的CTGF表达。结果 免疫细胞化学显示AF表达CTGF，AngⅡ可以诱导AF以及其上清液中CTGF表达增加。Western blot显示AngⅡ诱导CTGF表达呈剂量和时间依赖性。10^-7mol／L AngⅡ刺激24h诱导AF产生CTGF作用最强。AngⅡ诱导CTGF表达增加作用可以被氯沙坦阻断，而不受PD123319影响。结论 AngⅡ通过AT1受体诱导CTGF合成。     

血管紧张素Ⅱ对肾间质成纤维细胞的作用

目的：探讨血管紧张素Ⅱ（Ａｎｇ Ⅱ）在肾间质纤维化过程中的作用机制。　方法：应用ＭＴＴ 比色法检测Ａｎｇ Ⅱ对成纤维细胞的增生,ＲＴＰＣＲ 检测纤溶酶原激活物抑制物（ＰＡＩ１）ｍＲＮＡ 的表达。　结果：Ａｎｇ Ⅱ可促进肾间质成纤维细胞增生及ＰＡＩ１ ｍＲＮＡ 的表达,且氯沙坦（１０ －４ｇ／Ｌ） 可抑制Ａｎｇ Ⅱ的促增生作用。　结论：Ａｎｇ Ⅱ可能通过直接作用于肾间质成纤维细胞,促进其增生,同时抑制细胞外基质的降解而参与肾间质纤维化的过程,而Ａｎｇ Ⅱ受体拮抗剂拮抗Ａｎｇ Ⅱ促细胞增生作用。     

肾上腺髓质素对血管紧张素Ⅱ诱导的血管平滑肌细胞MCP-1表达的影响

目的观察肾上腺髓质素（ADM）对血管紧张素Ⅱ（AngⅡ）诱导的大鼠主动脉血管平滑肌细胞（VSMCs）单核细胞趋化蛋白-1（MCP-1）表达的影响。方法体外培养大鼠主动脉VSMCs。实验分组：空白对照组（A组）;1×10^-7mol/L ADM组（B组）;1×10^-7mol／LAngⅡ组（C组）;1×10^-8mol／L ADM＋1×10^-7mol／L AngⅡ组（D组）;1×10^-7mol／LADM＋1×10^-7mol／LAng Ⅱ组（E组）。采用逆转录聚合酶链反应技术测定细胞中MCP-1 mRNA的表达量。结果C组MCP-1 mRNA的表达量高于A组（P〈0．05）。D组、E组MCP-1 mRNA的表达量低于C组（P〈0．05）。结论ADM对Ang Ⅱ诱导的大鼠主动脉VSMCs MCP-1的表达起明显的抑制作用,这可能是其发挥抗炎、心血管保护作用机理中的一个重要途径。     

NADPH oxidase mediates angiotensin II-induced endothelin-1 expression in vascular adventitial fibroblasts

OBJECTIVE: We have recently reported that adventitial fibroblasts are able to express endothelin-1 (ET-1) in response to angiotensin II (Ang II) stimulation. However, the mechanism by which this occurs in the adventitia remains unclear. As Ang II has been reported to increase oxidant production by NADPH oxidase, we examined the role of this complex in Ang II stimulated ET-1 expression in vascular adventitial fibroblasts. METHODS AND RESULTS: Adventitial fibroblasts were isolated and cultured from mouse aorta. Cells were treated with Ang II (100 nmol/L) in the presence or absence of NADPH oxidase inhibitors, apocynin (100 micromol/L) and diphenyleneiodonium (10 micromol/L), superoxide scavengers, SOD (350 units/mL), tempol (100 micromol/L), tiron (100 micromol/L), and ET-receptor antagonists (10 microM), BQ123 (for ET(A)-) and BQ788 (for ET(B)-). PreproET-1 mRNA and ET-1 level were determined by relative RT-PCR and ELISA, respectively. Type I procollagen-alpha-I (collagen) level was detected by Western blot. Superoxide anion (superoxide) production was determined by coelenterazine or lucigenin chemiluminescence. Ang II-induced collagen expression was inhibited by BQ123, suggesting that adventitial ET-1 plays a significant role in regulating the extracellular matrix. NADPH oxidase inhibitors and superoxide scavengers significantly decreased Ang II-induced ET-1 mRNA and peptide expression, superoxide production as well as collagen expression. Furthermore, deletion of gp91(phox) (a key subunit of NADPH oxidase) and overexpression of SOD1 attenuated Ang II-induced responses. CONCLUSION: Ang II-evoked expression of ET-1 in adventitial fibroblasts appears to be mediated, at least in part, by NADPH oxidase. Functionally, this mechanism stimulates collagen expression thereby implicating the adventitia as a potential contributor to the vascular pathophysiology associated with oxidative stress and vascular remodeling.     

Antioxidant effect of adrenomedullin on angiotensin II-induced reactive oxygen species generation in vascular smooth muscle cells

Recent adrenomedullin (AM) gene-targeting studies have proposed a novel concept that AM plays a protective role against oxidative stress in vivo. The present study was undertaken to explore the underlying molecular mechanism of the putative antioxidant action of AM against angiotensin II (Ang II)induced reactive oxygen species (ROS) generation in rat vascular smooth muscle cells (VSMCs). Intracellular ROS levels were measured by dichlorofluoroscein fluorescence. Redox-sensitive c-Jun amino-terminal kinase (JNK) and ERK1/2 activation and gene expression induced by Ang II in VSMCs were also studied. AM dose-relatedly (10(-8)-10(-7) m) inhibited intracellular ROS generation stimulated by Ang II (10(-7) m), as mimicked by dibutyl-cAMP, the effect of which was inhibited by the pretreatment with N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinolinesulfonamide hydrochloride, a protein kinase A inhibitor, and calcitonin gene-related peptide(8-37), an AM/calcitonin gene-related peptide receptor antagonist. Ang II induced JNK and ERK1/2 activation via a redox-sensitive manner, whereas AM inhibited JNK, but not ERK1/2, activation by Ang II. Furthermore, AM inhibited Ang II-induced redox-sensitive gene expression (plasminogen activator inhibitor-1 and monocyte chemoattractant protein-1) in the same manner as N-acetyl-l-cysteine, a potent antioxidant. AM also inhibited Ang II-induced up-regulation of Nox1, a critical membrane-bound component of reduced nicotinamide adenine dinucleotide phosphate oxidase in VSMCs, in the same degree as N-acetyl-l-cysteine. Our study demonstrates for the first time that AM directly inhibits intracellular ROS generation via an AM receptor-mediated and c-AMP-protein kinase A-dependent mechanism in VSMCs and that AM with its potent antioxidant action inhibits redox-sensitive JNK activation and gene expression induced by Ang II. These data suggest that AM plays a protective role as an endogenous antioxidant in Ang II-induced vascular injury.     

Antifibrotic effect of adrenomedullin on coronary adventitia in angiotensin II-induced hypertensive rats

OBJECTIVE: The extracellular matrix (ECM) determines the structural integrity of the heart and vasculature, participating in cardiovascular remodeling. We previously reported that adrenomedullin (AM) inhibited cellular proliferation and protein synthesis of cardiac fibroblasts; however, the precise mechanisms of AM actions as an antifibrotic factor remain unknown. The purpose of this study was to examine the biological actions of AM against the profibrotic factor angiotensin II (Ang II) in coronary adventitia. METHODS AND RESULTS: Rats with hypertension induced by Ang II infusion were administered 0.06 mug/kg/min recombinant human AM subcutaneously for 14 days. The AM infusion significantly (p<0.05) reduced the Ang II-induced increase of coronary adventitial fibroblasts expressing Ki-67 and alpha-smooth muscle actin (alpha-SMA) in the left ventricle, by 65%, and 62%, respectively, without affecting systolic blood pressure, left ventricle/body weight, or cross-sectional area of myocardial fibers. Collagen deposition of coronary arteries was reduced by the AM infusion (-24%, p<0.01), and these effects of AM were accompanied by significant reductions in gene expression of type 1 collagen (-49%, p<0.05) and transforming growth factor-beta1 (TGF-beta1) (-55%, p<0.01). In cultured cardiac fibroblasts, 10(-7) mol/L AM exerted an inhibitory effect on TGF-beta1-induced alpha-SMA expression (p<0.01) that was mimicked by 8-bromo-cAMP and attenuated by the protein kinase A inhibitor H-89. CONCLUSION: AM decreased Ang II-induced collagen deposition surrounding the coronary arteries, inhibiting myofibroblast differentiation and expressions of ECM-related genes in rats. The present findings further support the biological action of AM as an antifibrotic factor in vascular remodeling.     

Angiotensin II-stimulated collagen synthesis in aortic adventitial fibroblasts is mediated by connective tissue growth factor

Angiotensin II (Ang II), a potent mediator of vascular remodeling, can stimulate the synthesis of extracellular matrix in vascular cells. Recent studies indicate that connective tissue growth factor (CTGF) is involved in collagen synthesis. There is also increasing evidence that adventitial fibroblasts (AFs) are actively involved in vascular remodeling. However, whether collagen synthesis by AFs is mediated by CTGF, or whether it is relevant to Ang II, has not been studied. The present study was conducted to determine whether CTGF is expressed in AFs, and if so, whether the CTGF produced by AFs participates in collagen synthesis. The AFs were isolated from thoracic aorta of Wistar-Kyoto rats (WKY). The expression of CTGF was measured by Western blot or real-time PCR. Collagen synthesis was assessed by [(3)H]proline incorporation. Our results suggested that CTGF was expressed in AFs and secreted into medium. Ang II increased CTGF mRNA and protein expression in a time- and dose-dependent manner, with the maximal protein increase occurring at 24 h with an Ang II dose of 10(-7) mol/L, and this increase was inhibited by the Ang II receptor type 1 (AT(1)-R) antagonist losartan, but not by the Ang II receptor type 2 (AT(2)-R) antagonist PD123319. Ang II dose-dependently stimulated the incorporation of [(3)H]proline into cultured AFs, and this effect was inhibited by a CTGF antisense oligodeoxynucleotide. Overexpression of CTGF by pcDNA3.1(+)/CTGF increased [(3)H]proline incorporation in cultured AFs. The results demonstrated that, in cultured AFs, Ang II increased CTGF production via AT(1)-R, which could be mediators of collagen synthesis by Ang II. This finding suggests that CTGF might be a novel target for antifibrotic therapy in vascular diseases.     

Mnk1 is required for angiotensin II-induced protein synthesis in vascular smooth muscle cells

Angiotensin II (Ang II) stimulates protein synthesis in vascular smooth muscle cells (VSMCs), possibly secondary to regulatory changes at the initiation of mRNA translation. Mitogen-activated protein (MAP) kinase signal-integrating kinase-1 (Mnk1), a substrate of ERK and p38 MAP kinase, phosphorylates eukaryotic initiation factor 4E (eIF4E), an important factor in translation. The goal of the present study was to investigate the role of Mnk1 in Ang II-induced protein synthesis and to characterize the molecular mechanisms by which Mnk1 and eIF4E is activated in rat VSMCs. Ang II treatment resulted in increased Mnk1 activity and eIF4E phosphorylation. Expression of a dominant-negative Mnk1 mutant abolished Ang II-induced eIF4E phosphorylation. PD98059 or introduction of kinase-inactive MEK1/MKK1, but not SB202190 or kinase-inactive p38 MAP kinase, inhibited Ang II-induced Mnk1 activation and eIF4E phosphorylation, suggesting that ERK, but not p38 MAP kinase, is required for Ang II-induced Mnk1-eIF4E activation. Further, dominant-negative constructs for Ras, but not for Rho, Rac, or Cdc42, abolished Ang II-induced Mnk1 activation. Finally, treatment of VSMCs with CGP57380, a novel specific kinase inhibitor of Mnk1, resulted in dose-dependent decreases in Ang II-stimulated phosphorylation of eIF4E, protein synthesis, and VSMC hypertrophy. In summary, these data demonstrated that (1) Ang II-induced Mnk1 activation is mediated by the Ras-ERK cascade in VSMCs, and (2) Mnk1 is involved in Ang II-mediated protein synthesis and hypertrophy, presumably through the activation of translation-initiation. The Mnk1-eIF4E pathway may provide new insights into molecular mechanisms involved in vascular hypertrophy and other Ang II-mediated pathological states.     

Evidence for renal vascular remodeling in angiotensin II-induced hypertension

OBJECTIVES: To determine whether 'slow pressor' hypertension from systemic angiotensin (Ang II) infusion was associated with renal vascular structural remodeling of the renal resistance vessels and glomerulus. METHODS: Ang II (4.5-10 ng/kg per min) or vehicle was infused for 10 days. Renal resistance vascular lumen changes were assessed at 10 days as changes in renal pressure flow and pressure-glomerular filtration rate (GFR) and pressure-Na+ excretion in maximally dilated, isotonically perfused kidneys. RESULTS: Low-dose, initially subpressor Ang II infusion for 10 days increased conscious arterial pressure by 27 mmHg compared to vehicle-infused rats (140 +/- 7 and 113 +/- 2 mmHg, respectively). There was no change in the pressure-flow relationship but the slope of the pressure-GFR relationship was reduced in the rats treated with Ang II. These changes are consistent with equal and opposite pre-and post-glomerular effects (i.e., increased pre-glomerular vessel resistance and reduced post-glomerular vessel resistance) and reduced glomerular ultrafiltration coefficient. There was also a significant reduction in pressure-dependent Na+ excretion. CONCLUSIONS: Slow pressor Ang II-induced hypertension was associated with apparent pro-hypertensive changes in the kidney involving pre/post-glomerular vessel remodeling as indicated by an apparent reduction in pre-glomerular lumen dimensions, a reduced glomerular filtration capacity and a reduction in the pressure natriuresis relationship.