肾素抑制剂研究新进展

近年来大量研究证实,抑制肾素血管紧张素系统(renin angiotensin system, RAS)对治疗心血管疾病、肾脏疾病及糖尿病并发症等具有良好的效果.众所周知,经典的RAS通过以下途径激活:血管紧张素原在肾素作用下生成无活性的十肽:血管紧张素Ⅰ,后者经血管紧张素转换酶(ACE)催化形成具有活性的八肽:血管紧张素Ⅱ,过度激活RAS产生的血管紧张素Ⅱ将主要通过血管紧张素Ⅱ受体1型(AT1R)产生高血压及靶器官损害.     

内皮素1、血管紧张素Ⅱ1型受体和血管紧张素Ⅱ2型受体在大鼠气道重塑过程中的表达研究

目的 探讨血管紧张素Ⅱ1型受体(aongiotensinⅡtype 1 receptor,AT1R)、AT2R和内素素1(endothelin-1,ET-1)在SD大鼠气道重塑模型中的表达,及糖皮质激素对其表达的影响.方法 清洁级SD大鼠,按照随机数字将其分为3组:支气管哮喘(简称哮喘)组、对照组和地塞米松干预组.建立大鼠哮喘模型,采用免疫组织化学技术结合计算机病理图像分析系统,测定大鼠气道支气管壁的ET-1、AT1R和AT2R染色的IOD值.测定完整的支气管横断面的基底膜周经和管壁面积,计算气道壁厚度.结果 哮喘组大鼠支气管壁的AT1R和ET-1表达明显高于对照组(P<0.01),地塞米松干预组大鼠的表达明显低于哮喘组(P<0.01),哮喘组、对照组和地塞米松干预组的AT2R表达有差别,但差异无统计学意义;哮喘组大鼠支气管壁ET-1和AT1R的表达均与气道壁厚度呈正相关(P<0.01),AT2R的表达与气道壁厚度无相关性;哮喘组大鼠支气管壁ET-1和AT1R的表达呈正相关(P<0.01).结论 血管紧张素Ⅱ主要通过AT1R参与了SD大鼠哮喘气道重塑过程;ET-1参与了SD大鼠哮喘气道重塑过程;糖皮质激素可通过抑制AT1R和ET-1的表达,干预气道重塑的形成;在SD大鼠哮喘气道重塑过程中ET-1和血管紧张素Ⅱ可能存在协同作用.     

血管紧张素转移酶2-血管紧张素(1-7)-Mas轴在肾脏疾病发病机制中的作用

肾素-血管紧张素系统(RAS)过度兴奋,尤其是肾脏局部RAS高表达对肾脏疾病发生发展起重要作用.随着对RAS深入研究发现,除经典的RAS途径外,还有一条新的RAS途径:血管紧张素转移酶2-血管紧张素(1-7)-Mas轴[ACE2-Ang(1-7)-Mas轴],它和经典RAS相互作用,共同调节机体内环境稳定、维持肾脏功能正常.本文就ACE2-Ang(1-7)-Mas轴在肾脏生理及疾病中的作用及其机制做一简述.     

肾素-血管紧张素系统与炎症性肠病关系的研究进展

炎症性肠病(IBD)是一组以肠道慢性非特异性炎性反应为表现的疾病,其发病机制尚不完全清楚。越来越多的研究表明,肾素-血管紧张素系统(RAS)成分在IBD患者血清或肠道黏膜中的表达发生改变,动物实验也证实血管紧张素转化酶抑制剂(ACEI)或血管紧张素受体拮抗剂(ARB)能减轻肠炎症状。因此,深入揭示RAS与IBD的关系,可能为探索IBD的发病机制以及治疗提供新的方向。     

血管紧张素转换酶-2在肺部疾病中的研究进展

肾素-血管紧张素系统( renin-angiotensin system,RAS)在维持血压和体内水盐平衡方面起重要作用.目前的研究提示RAS与肺纤维化、肺动脉高压等多种呼吸系统疾病的发病机制相关,而血管紧张素转换酶-2(angiot ensin-conver ting enzyme-2,ACE2)是ACE同工酶,起负向调节RAS活性的作用,对急性呼吸窘迫综合征等肺部疾病起保护作用,有望成为呼吸系统疾病治疗的新靶点.     

血管紧张素转化酶抑制剂和血管紧张素受体拮抗剂与肾保护作用

目前认为肾素血管紧张素系统（RAS）参与了慢性肾脏疾病的进展,阻断RAS能延缓肾脏疾病进展。血管紧张素转化酶抑制剂（ACEI）及血管紧张素ⅡAT1受体拮抗剂（AT1RA）是阻断RAS的主要药物。本文就此两类药物的肾保护作用进行综述,以供临床用药参考。     

ACE2--RAS代谢新通路在心血管活动调节中的作用

肾素-血管紧张素系统(RAS)在哺乳动物心血管活动调节中发挥着关键的作用。对RAS系统中血管紧张素转化酶(ACE)及血管紧张素Ⅱ(AngⅡ)的研究和认识已为临床治疗高血压、心力衰竭等心血管疾病提供了相当有效的帮助。近来,一种新的血管紧张素转化酶2(ACE2)被发现,ACE2的新的代谢通路对RAS系统传统代谢通路可能有着负性调节作用,ACE2代谢通路的发现为RAS系统的研究、认识心血管疾病发病机制和新药开发等开辟了全新的领域。     

RAS抑制剂预防心房颤动研究进展

大量研究证实肾素-血管紧张素-醛固酮系统(RAS)的激活在心房颤动(房颤)的发生、发展中起重要作用。RAS抑制剂包括血管紧张素转化酶抑制剂(ACEI)和血管紧张素Ⅱ受体拮抗剂(ARB),通过阻断RAS激活,尤其是阻断血管紧张素Ⅱ     

ACE2-Ang-（1—7）-Mas轴：心血管疾病治疗的新靶点

肾素一血管紧张素系统(RAS)在哺乳动物心血管活动的调节中发挥了重要的作用.随着血管紧张素转化酶(ACE)2和血管紧张素1-7[Ang-(1-7)]特异性受体Mas的发现,形成了RAS中一个对心血管有益的新分支:ACE2-Ang-(1-7)-Mas轴.其中ACE2可以水解血管紧张素Ⅰ(Ang Ⅰ)、血管紧张素Ⅱ(AngⅡ)生成Ang-(1-7).Ang-(1-7)则通过Mas受体拮抗AngⅡ的作用,引起血管舒张、抑制细胞增殖.这一新分支的发现为心血管疾病的治疗提供了新靶点.     

血管紧张素转换酶2研究新进展

血管紧张素转换酶(ACE)是一种锌指金属蛋白酶,对肾素-血管紧张素系统(RAS)有关键调控作用.ACE 2主要分布在心脏、肾脏和睾丸,能水解血管紧张素(Ang)Ⅰ,产生Ang 1-9,还能水解RAS中的主要物质AngⅡ,产生具有血管扩张作用的Ang 1-7.研究表明ACE 2可能在RAS中扮演与ACE相反的角色,达到血管收缩和舒张之间的平衡,与高血压、心力衰竭及糖尿病肾病等关系密切.     

Renin-Angiotensin System Component Gene Polymorphism in Japanese Bronchial Asthma Patients

The influence of renin-angiotensin system (RAS) component gene polymorphism in the pathogenesis of bronchial asthma was investigated in an association study involving 119 bronchial asthma patients and 208 control subjects. The selected RAS polymorphisms were angiotensinogen (Agt) T235/M235 and angiotensin l-converting enzyme (ACE) insertion/deletion (l/D). The control allelic frequencies of the Agt T235/M235 (0.84/0.16) and ACE l/D (0.63/0.37) in this study were similar to the previous reports in Japanese normal population. The allelic frequencies of the Agt T235/M235 (0.84/0.16) and ACE l/D (0.65/ 0.35) among the asthma patients were not significantly different from those among the control subjects. There was no association between severity of bronchial asthma and the selected RAS component gene polymorphism. From these data, we conclude that in the Japanese population, the RAS component gene polymorphism is not associated with increased risk for bronchial asthma.     

Local renin-angiotensin system in the pancreas: the significance of changes by chronic hypoxia and acute pancreatitis

The circulating renin-angiotensin system (RAS) plays an important role in the maintenance of blood pressure and fluid homeostasis. Recently, there has been a shift of emphasis from the circulating RAS to the local RAS in the regulation of individual tissue functions via a paracrine and/or autocrine mechanism. In fact, a local RAS has been proposed to be present in an array of tissues including the brain, heart, kidney and gonads. Our previous studies have provided solid evidence that several key elements of the RAS, notably angiotensinogen and renin, are present in the rat pancreas. The data support the existence of an intrinsic RAS in the pancreas and this local RAS may be important for the exocrine/endocrine functions of the pancreas. Interestingly, such a pancreatic RAS has been demonstrated to be markedly activated by experimental rat models of chronic hypoxia and acute pancreatitis. The activation of the pancreatic RAS by chronic hypoxia and experimental pancreatitis could play a role in the physiology and pathophysiology of the pancreas. The significant changes of pancreatic RAS may have clinical relevance to acute pancreatitis and hypoxia-induced injury in the pancreas.     

Medikament?se oder instrumentelle Therapie der Nierenarterienstenose?

Arteriosclerotic renal artery stenosis (RAS) has an increased incidence in patients with cardiovascular risk factors. Clinically RAS presents in some patients as secondary, sometimes resistant arterial hypertension and in others as chronic renal insufficiency, sometimes with acute renal failure and in a third group both symptoms are observed. Doppler ultrasound plays a central role in the diagnosis of RAS. Therapeutically, it is important to identify hemodynamically relevant RAS before interventional therapy is initiated. The therapy of RAS has been under intensive debate since the publication of randomized controlled trials (RCT) which showed that only a subset of RAS can be successfully treated by interventional therapy. Since then the medicinal therapy of RAS has gained more and more impact. The following questions are raised: which forms of RAS can be treated by which therapy? What is the best medicinal therapy to treat RAS? What substances are recommended?     

Transforming genes in chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is a hematopoietic malignancy characterized by an indolent chronic phase that invariably leads to a "blast crisis" indistinguishable from acute leukemia. Using a sensitive assay based on gene transfer and tumorigenesis, we sought evidence that damage to protooncogenes might figure in the progression from the chronic to the blast phase of CML. Seven of the 12 patients with CML examined in this manner harbored transforming genes. Mutations in RAS protooncogenes were detected in the leukemic cells from 1 of 6 chronic-phase patients, and 3 of 6 blast-crisis patients. In addition, a presently unidentified transforming gene (neither RAS nor RAF) was detected in 1 patient with chronic phase and 1 with blast crisis. Our data indicate that mutations in RAS genes may play diverse roles in the pathogenesis of CML.     

Molecular Mechanisms Involved in Intrarenal Renin-Angiotensin and Alternative Pathways in Diabetic Nephropathy - A Review

Uncontrolled or chronic hyperglycemia causes kidney failure induced by the dysfunction of biomolecules and upregulation of inflammatory cytokines and growth factors. The reninangiotensin system (RAS) is incorporated in the regulation of renal hemodynamics. In a healthy state, local RAS is independent of systemic RAS. However, in pathological conditions such as chronic hyperglycemia, angiotensin II (Ang II) increases locally and causes tissue damage, mainly through the induction of oxidative stress, inflammation, and upregulation of some growth factors and their receptors. Such tissue events may cause disruption of the glomerular filtration barrier, thickening and hypertrophy of the glomerular basement membrane, microvascular hyperpermeability, proteinuria, and finally decrease in the glomerular filtration rate (GFR). Reduced GFR causes the kidney to sense falsely a low blood pressure condition and respond to it by stimulating systemic and local RAS. Therefore, patients with diabetic nephropathy (DN) suffer from chronic hypertension. In contrast to local RAS, there are alternative pathways in the kidney that act protectively by reducing tissue Ang II. Such autoregulatory and protective mechanisms are weakened in chronic kidney disease. Previously, it was presumed that systemic RAS inhibitors such as ACE inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) could prevent renal damage by controlling blood pressure and proteinuria. However, the progression of renal failure to end-stage renal disease (ESRD), despite such treatments, indicates the presence of factors other than Ang II. This review highlights the molecular mechanism in renal disease and discusses pharmaceutical and therapeutic approaches.     

RAS mutations are rare events in Philadelphia chromosome-negative/bcr gene rearrangement-negative chronic myelogenous leukemia, but are prevalent in chronic myelomonocytic leukemia

Previous reports have indicated that mutations of the RAS oncogenes are not associated with the chronic phase of Philadelphia chromosome-positive chronic myelogenous leukemia (Ph1+ CML). However, further studies were needed to determine their association with Ph1- CML and chronic myelomonocytic leukemia (CMML). Therefore, 6 patients with Ph1- CML who were also negative for BCR rearrangements (Ph1-/BCR- CML) and 30 patients with CMML were analyzed for the presence of RAS oncogene point mutations to determine the similarities of these diseases at the molecular level. The assay used the polymerase chain reaction for amplification of the target RAS sequences and panels of specific synthetic oligonucleotide probes for hybridization to wild type and/or mutated sequences. None of the six Ph1-/BCR- CML patients had mutations in the RAS oncogenes, while 17 of 30 (57%) of the CMML patients had RAS oncogene mutations. Eighty percent of the mutations involved substitution of aspartic acid for glycine (G----A) in the 12th or 13th codons of N-ras or K-ras. Furthermore, although not statistically significant, survival studies raise the possibility of shortened survival in patients with RAS oncogene point mutations, with the average survival being 33 months for Ph1-/BCR- CML, 35 months for CMML without point mutations, and 11 months for CMML with RAS mutations. Thus, RAS mutations appear to be associated with CMML and not Ph1-/BCR- chronic phase CML, there is a high propensity for the K-ras or N-ras mutations to involve an G----A substitution in the 12th or 13th codons, and RAS mutations in CMML may relate to prognosis and require further studies.     

Potential role of the tissue renin-angiotensin system in the pathophysiology of congestive heart failure

The circulating renin-angiotensin system (RAS) plays an important role in the maintenance of cardiovascular homeostasis. It has recently been demonstrated that endogenous RAS exist in target tissues that are important in cardiovascular regulation. This article reviews the multiple effects of angiotensin II in target tissues, the evidence for the presence of functional tissue RAS and the data that suggest a role for these tissue RAS in the pathophysiology of heart failure. Activation of circulating neurohormones is predictive of worsened survival in heart failure; however, cardiac and renal tissue RAS activities are also increased in the compensated stage of heart failure, when plasma renin-angiotensin activity is normal. It is hypothesized that the plasma RAS maintains circulatory homeostasis during acute cardiac decompensation, while changes in tissue RAS contribute to homeostatic responses during chronic sustained cardiac impairment. This concept of different functions of circulating and tissue RAS in the pathophysiology of heart failure may have important pharmacologic implications.     

Treating patients for cardiovascular protection: combination therapy to achieve complete renin-angiotensin system blockade

Inhibition of the renin-angiotensin system (RAS) with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) is a proven antihypertensive strategy. Understanding of the pathophysiologic effects of chronic RAS activation and clinical data indicate that RAS inhibition may exert beneficial effects in addition to blood pressure reduction. Studies indicate that monotherapy with ACE inhibitors and ARBs slows progression of diabetic and non-diabetic renal disease. Vascular protective effects of RAS inhibition have also been demonstrated in patients at high risk for cardiovascular events in the absence of significant blood pressure elevation or left ventricular dysfunction. Combining the complementary effects of ACE inhibitors and ARBs to achieve more complete RAS blockade is a promising approach to further reducing cardiovascular risk. This review will present the rationale for dual RAS inhibition, clinical data relating to its efficacy, and ongoing studies designed to evaluate its utility in patients at high risk for cardiovascular events.     

Beneficial effects of antioxidant vitamins on the stenotic kidney

Renal artery stenosis (RAS) may lead to renal injury, partly mediated through increased oxidative stress. However, the potential effects of chronic oral antioxidant intervention on the stenotic kidney remain unknown. This study was designed to test the hypothesis that chronic antioxidant vitamin supplementation in RAS would preserve renal function and structure. Single-kidney hemodynamics and function were quantified in vivo in pigs using electron-beam CT after 12 weeks of unilateral RAS (n=7), a similar degree of RAS orally supplemented with vitamins C (1 g) and E (100 IU/kg) (RAS+Vitamins, n=7), or controls (normal, n=7). Renal tissue was studied ex vivo using Western blotting and immunohistochemistry. Mean arterial pressure was similarly elevated in both RAS groups, while ischemic renal volume and glomerular filtration rate were similarly reduced. Renal blood flow was decreased in RAS compared with normal (326.5+/-99.9 versus 553.4+/-48.7 mL/min, respectively, P=0.01), but preserved in RAS+Vitamins (485.2+/-104.1 mL/min, P=0.3 versus normal). The marked increase in the expression of the NADPH-oxidase subunits p47phox and p67phox, nitrotyrosine, endothelial and inducible nitric oxide synthase, and nuclear factor-kappaB observed in RAS (P<0.05 versus normal) was normalized in RAS+Vitamins (P>0.1). Furthermore, trichrome staining and the expression of transforming growth factor-beta and tissue inhibitor of matrix-metalloproteinase-1 were also decreased in RAS+Vitamins. In conclusion, chronic blockade of the oxidative stress pathway in RAS using antioxidant vitamins improved renal hemodynamics and decreased oxidative stress, inflammation, and fibrosis in the ischemic kidney. These observations underscore the involvement of oxidative stress in renal injury in RAS and support a role for antioxidant vitamins in preserving the ischemic kidney.