The role of angiotensin II in regulating vascular structural and functional changes in hypertension

SARS-CoV-2 pathogenesis in an angiotensin II-induced heart-on-a-chip disease model and extracellular vesicle screening

Adverse cardiac outcomes in COVID-19 patients, particularly those with preexisting cardiac disease, motivate the development of human cell-based organ-on-a-chip models to recapitulate cardiac injury and dysfunction and for screening of cardioprotective therapeutics. Here, we developed a heart-on-a-chip model to study the pathogenesis of SARS-CoV-2 in healthy myocardium established from human induced pluripotent stem cell (iPSC)-derived cardiomyocytes and a cardiac dysfunction model, mimicking aspects of preexisting hypertensive disease induced by angiotensin II (Ang II). We recapitulated cytopathic features of SARS-CoV-2-induced cardiac damage, including progressively impaired contractile function and calcium handling, apoptosis, and sarcomere disarray. SARS-CoV-2 presence in Ang II-treated hearts-on-a-chip decreased contractile force with earlier onset of contractile dysfunction and profoundly enhanced inflammatory cytokines compared to SARS-CoV-2 alone. Toward the development of potential therapeutics, we evaluated the cardioprotective effects of extracellular vesicles (EVs) from human iPSC which alleviated the impairment of contractile force, decreased apoptosis, reduced the disruption of sarcomeric proteins, and enhanced beta-oxidation gene expression. Viral load was not affected by either Ang II or EV treatment. We identified MicroRNAs miR-20a-5p and miR-19a-3p as potential mediators of cardioprotective effects of these EVs.

Chemokine Fractalkine and Non-Obstructive Coronary Artery Disease-Is There a Link?

Non-obstructive coronary artery disease (NO-CAD) constitutes a heterogeneous group of conditions collectively characterized by less than 50% narrowing in at least one major coronary artery with a fractional flow reserve (FFR) of ≤0.80 observed in coronary angiography. The pathogenesis and progression of NO-CAD are still not fully understood, however, inflammatory processes, particularly atherosclerosis and microvascular dysfunction are known to play a major role in it. Chemokine fractalkine (FKN/CX3CL1) is inherently linked to these processes. FKN/CX3CL1 functions predominantly as a chemoattractant for immune cells, facilitating their transmigration through the vessel wall and inhibiting their apoptosis. Its concentrations correlate positively with major cardiovascular risk factors. Moreover, promising preliminary results have shown that FKN/CX3CL1 receptor inhibitor (KAND567) administered in the population of patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI), inhibits the adverse reaction of the immune system that causes hyperinflammation. Whereas the link between FKN/CX3CL1 and NO-CAD appears evident, further studies are necessary to unveil this complex relationship. In this review, we critically overview the current data on FKN/CX3CL1 in the context of NO-CAD and present the novel clinical implications of the unique structure and function of FKN/CX3CL1 as a compound which distinctively contributes to the pathomechanism of this condition.

Blood-Pressure-Lowering and Endothelium-Dependent Vasorelaxant Effects of Nutgall Tree in Rats

Hypertension is the crucial modifiable risk factor for cardiovascular diseases, and efforts to identify functional foods that are effective for hypertension control are increasing. The nutgall tree (NT, Rhus chinensis Mill.) is used in traditional medicine and food because of its medicinal value. However, the role of NT in hypertension has not been investigated. Therefore, the hypotensive effect of NT leaf ethanol extract (NTE) was investigated in spontaneously hypertensive rats (SHRs). SHRs were allocated to three groups (control, 300, or 1000 mg/kg NTE), and blood pressure was measured before and after oral administration. Systolic and diastolic blood pressure significantly decreased in the NTE 1000 mg/kg group and was the lowest at 2 h after administration (-26.4 ± 10.3, -33.5 ± 9.8%, respectively). Daily NTE administration for five days also resulted in a similar effect. Further, the vasorelaxant effects and related mechanisms were investigated in the aortas of Sprague Dawley rats. NTE showed the dose-dependent blood-vessel-relaxing effect, and its mechanism involves the NO-sGC-cGMP pathway, activation of K+ channels, and reduction in the vasoconstrictive action of angiotensin II. Therefore, our study provides basic data indicating the potential use of NTE as a functional food for high blood pressure.

Regulation of vascular angiotensin II type 1 and type 2 receptor and angiotensin-(1-7)/MasR signaling in normal and hypertensive pregnancy

Normal pregnancy (Norm-Preg) is associated with a slight reduction in blood pressure (BP) and decreased BP response to vasoconstrictor stimuli such as angiotensin II (Ang II), although the renin-angiotensin-aldosterone system (RAAS) is upregulated. Preeclampsia (PE) is a complication of pregnancy manifested as hypertension-in-pregnancy (HTN-Preg), and dysregulation of angiotensin biosynthesis and signaling have been implicated. Ang II activates vascular Ang II type-1 receptor (AT1R) and Ang II type-2 receptor (AT2R), while angiotensin-(1-7) promotes Ang-(1-7)/MasR signaling. The role of AT1R in vasoconstriction and the activated cellular mechanisms are well-characterized. The sensitivity of vascular AT1R to Ang II and consequent activation of vasoconstrictor mechanisms decrease during Norm-Preg, but dramatically increase in HTN-Preg. Placental ischemia in late pregnancy could also initiate the release of AT1R agonistic autoantibodies (AT1AA) with significant impact on endothelial dysfunction and activation of contraction pathways in vascular smooth muscle including [Ca2+]c and protein kinase C. On the other hand, the role of AT2R and Ang-(1-7)/MasR in vascular relaxation, particularly during Norm-Preg and PE, is less clear. During Norm-Preg, increases in the expression/activity of vascular AT2R and Ang-(1-7)/MasR promote the production of endothelium-derived relaxing factors such as nitric oxide (NO), prostacyclin and endothelium-derived hyperpolarizing factor leading to generalized vasodilation. Aortic segments of Preg rats show prominent endothelial AT2R staining and increased relaxation and NO production in response to AT2R agonist CGP42112A, and treatment with AT2R antagonist PD123319 enhances phenylephrine-induced contraction. Decreased vascular AT2R and Ang-(1-7)/MasR expression and receptor-mediated mechanisms of vascular relaxation have been suggested in HTN-Preg animal models, but their role in human PE needs further testing. Changes in angiotensin-converting enzyme-2 (ACE2) have been observed in COVID-19 patients, and whether ACE2 influences the course of COVID-19 viral infection/immunity in Norm-Preg and PE is an intriguing area for research.

Hexahydrocurcumin mitigates angiotensin II-induced proliferation, migration, and inflammation in vascular smooth muscle cells

The proliferation and migration of vascular smooth muscle cells (VSMCs) play vital roles in the pathogenesis of atherosclerosis and hypertension. It has been proposed and verified that hexahydrocurcumin (HHC), a metabolite form of curcumin, has cardiovascular protective effects. This study examined the effect of HHC on angiotensin II (Ang II)-induced proliferation, migration, and inflammation in rat aortic VSMCs and explored the molecular mechanisms related to the processes. The results showed that HHC significantly suppressed Ang II-induced proliferation, migration, and inflammation in VSMCs. HHC inhibited Ang II-induction of the increase in cyclin D1 and decrease in p21 expression in VSMCs. Moreover, HHC attenuated the generation of reactive oxygen species (ROS), and the expression of nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and matrix metalloproteinases-9 (MMP9) in Ang II-induced VSMCs. The proliferation, migration, inflammation, and ROS production were also inhibited by GKT137831 (NADPH oxidase, NOX1/4 inhibitor) and the combination of HHC and GKT137831. In addition, HHC restored the Ang-II inhibited expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) and peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). These findings indicate that HHC may play a protective role in Ang II-promoted proliferation, migration, and inflammation by suppressing NADPH oxidase mediated ROS generation and elevating PPAR-γ and PGC-1α expression. See also Figure 1(Fig. 1).

Role of G-protein coupled receptors in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of death globally, with CVDs accounting for nearly 30% of deaths worldwide each year. G-protein-coupled receptors (GPCRs) are the most prominent family of receptors on the cell surface, and play an essential regulating cellular physiology and pathology. Some GPCR antagonists, such as β-blockers, are standard therapy for the treatment of CVDs. In addition, nearly one-third of the drugs used to treat CVDs target GPCRs. All the evidence demonstrates the crucial role of GPCRs in CVDs. Over the past decades, studies on the structure and function of GPCRs have identified many targets for the treatment of CVDs. In this review, we summarize and discuss the role of GPCRs in the function of the cardiovascular system from both vascular and heart perspectives, then analyze the complex ways in which multiple GPCRs exert regulatory functions in vascular and heart diseases. We hope to provide new ideas for the treatment of CVDs and the development of novel drugs.

Is the anti-aging effect of ACE2 due to its role in the renin-angiotensin system?-Findings from a comparison of the aging phenotypes of ACE2-deficient, Tsukuba hypertensive, and Mas-deficient mice

Angiotensin converting enzyme 2 (ACE2) functions as an enzyme that produces angiotensin 1-7 (A1-7) from angiotensin II (AII) in the renin-angiotensin system (RAS). We evaluated aging phenotypes, especially skeletal muscle aging, in ACE2 systemically deficient (ACE2 KO) mice and found that ACE2 has an antiaging function. The characteristic aging phenotype observed in ACE2 KO mice was not reproduced in mice deficient in the A1-7 receptor Mas or in Tsukuba hypertensive mice, a model of chronic AII overproduction, suggesting that ACE2 has a RAS-independent antiaging function. In this review, the results we have obtained and related studies on the aging regulatory mechanism mediated by RAS components will be presented and summarized. We evaluated the aging phenotype of ACE2 systemically deficient (ACE2 KO) mice, particularly skeletal muscle aging, and found that ACE2 has an antiaging function. The characteristic aging phenotype observed in ACE2 KO mice was not reproduced in Mas KO mice, angiotensin 1-7 receptor-deficient mice or in Tsukuba hypertensive mice, a model of chronic angiotensin II overproduction, suggesting that the antiaging functions of ACE2 are independent of the renin-angiotensin system (RAS).

Epigenetic Mechanisms Involved in Inflammaging-Associated Hypertension

PURPOSE OF REVIEW

This review summarizes the involvement of inflammaging in vascular damage with focus on the epigenetic mechanisms by which inflammaging-induced hypertension is triggered.

RECENT FINDINGS

Inflammaging in hypertension is a complex condition associated with the production of inflammatory mediators by the immune cells, enhancement of oxidative stress, and tissue remodeling in vascular smooth muscle cells and endothelial cells. Cellular processes are numerous, including inflammasome assembly and cell senescence which may involve mitochondrial dysfunction, autophagy, DNA damage response, dysbiosis, and many others. More recently, a series of noncoding RNAs, mainly microRNAs, have been described as possessing epigenetic actions on the regulation of inflammasome-related hypertension, emerging as a promising therapeutic strategy. Although there are a variety of pharmacological agents that effectively regulate inflammaging-related hypertension, a deeper understanding of the epigenetic events behind the control of vessel deterioration is needed for the treatment or even to prevent the disease onset.

Regulation of total LC3 levels by angiotensin II in vascular smooth muscle cells

Hypertension is associated with high circulating angiotensin II (Ang II). We have reported that autophagy regulates Ang II‐induced vascular smooth muscle cell (VSMC) hypertrophy, but the mechanism mediating this effect is still unknown. Therefore, we studied how Ang II regulates LC3 levels in VSMCs and whether Bag3, a co‐chaperone known to regulate LC3 total levels, may be involved in the effects elicited by Ang II. A7r5 cell line or rat aortic smooth muscle cell (RASMC) primary culture were stimulated with Ang II 100 nM for 24 h and LC3 I, LC3 II and Bag3 protein levels were determined by Western blot. MAP1LC3B mRNA levels were assessed by RT‐qPCR. Ang II increased MAP1LC3B mRNA levels and protein levels of LC3 I, LC3 II and total LC3 (LC3 I + LC3 II). Cycloheximide, but not actinomycin D, abolished LC3 II and total LC3 increase elicited by Ang II in RASMCs. In A7r5 cells, cycloheximide prevented the Ang II‐mediated increase of LC3 I and total LC3, but not LC3 II. Moreover, Ang II increased Bag3 levels, but this increase was not observed upon co‐administration with either losartan 1 μM (AT1R antagonist) or Y‐27632 10 μM (ROCK inhibitor). These results suggest that Ang II may regulate total LC3 content through transcriptional and translational mechanisms. Moreover, Bag3 is increased in response to Ang II by a AT1R/ROCK signalling pathway. These data provide preliminary evidence suggesting that Ang II may stimulate autophagy in VSMCs by increasing total LC3 content and LC3 processing.

Angiotensin II-induced histone deacetylase 5 phosphorylation, nuclear export, and Egr-1 expression are mediated by Akt pathway in A10 vascular smooth muscle cells

Angiotensin II (ANG II) regulates an array of physiological and pathological responses in vascular smooth muscle cells (VSMCs) by activating ERK1/2 and phosphoinositide 3-kinase (PI3K)/Akt signaling pathways. We have demonstrated that ANG II and insulin-like growth factor-1 (IGF-1) induce the expression of early growth response protein-1 (Egr-1), a zinc finger transcription factor, which regulates the transcription of cell cycle regulatory genes network in VSMCs. We have reported that IGF-1 induces the phosphorylation of histone deacetylase 5 (HDAC5), which has been implicated in the expression of genes linked to VSMC growth and hypertrophy, via a PI3K/Akt-dependent pathway in VSMCs. However, the involvement of PI3K/Akt pathways in ANG II-induced HDAC5 phosphorylation and the contribution of HDAC5 in Egr-1 expression and hypertrophy in VSMCs remain unexplored. Here, we show that pharmacological blockade of the PI3K/Akt pathway either by wortmannin/SC66 or siRNA-induced silencing of Akt attenuated ANG II-induced HDAC5 phosphorylation and its nuclear export. Moreover, SC66 or Akt knockdown also suppressed ANG II-induced Egr-1 expression. Furthermore, pharmacological inhibition of HDAC5 by MC1568 or TMP-195 or knockdown of HDAC5 and the blockade of the nuclear export of HDAC5 by leptomycin B or KPT-330 significantly reduced ANG II-induced Egr-1 expression. In addition, depletion of either HDAC5 or Egr-1 by siRNA attenuated VSMC hypertrophy in response to ANG II. In summary, our results demonstrate that ANG II-induced HDAC5 phosphorylation and its nuclear exclusion are mediated by PI3K/Akt pathway and HDAC5 is an upstream regulator of Egr-1 expression and hypertrophy in VSMCs.NEW & NOTEWORTHY ANG II-induced histone deacetylase 5 (HDAC5) phosphorylation and nuclear export occurs via the phosphoinositide 3-kinase/Akt pathway. Akt, through HDAC5, regulates ANG II-induced expression of early growth response protein-1 (Egr-1), which is a transcription factor linked with vascular dysfunction. Inhibition of HDAC5 exclusion by nuclear export inhibitors suppresses ANG II-induced Egr-1 expression. HDAC5 is an upstream mediator of Egr-1 expression and cell hypertrophy in response to ANG II in vascular smooth muscle cells.

New insights into RhoA/Rho-kinase signaling: a key regulator of vascular contraction

While Rho-signalling controlling vascular contraction is a canonical mechanism, with the modern approaches used in research, we are advancing our understanding and details into this pathway are often uncovered. RhoA-mediated Rho-kinase is the major regulator of vascular smooth muscle cells and a key player manoeuvring other functions in these cells. The discovery of new interactions, such as oxidative stress and hydrogen sulphide with Rho signalling are emerging addition not only in the physiology of the smooth muscle, but especially in the pathophysiology of vascular diseases. Likewise, the interplay between ageing and Rho-kinase in the vasculature has been recently considered. Importantly, in smooth muscle contraction, this pathway may also be affected by sex hormones, and consequently, sex-differences. This review provides an overview of Rho signalling mediating vascular contraction and focuses on recent topics discussed in the literature affecting this pathway such as ageing, sex differences and oxidative stress.

Juglone as antihypertensive agent acts through multiple vascular mechanisms

Background: Juglone, a natural phenolic compound obtained from the walnut tree, is known for its wide range of biological activities. However, it has yet to be tested for its effects on hypertension and vascular tone. This investigation was aimed to explore the antihypertensive effect and the nature of vascular reactivity of juglone in rat models.Methods: Juglone was tested in in vivo and in vitro experiments in rats. The responses were analyzed and recorded through a PowerLab data acquisition system.Results: Intravenous injection of juglone significantly decreased the mean arterial blood pressure (MAP) in normotensive and hypertensive rats (Max. fall, 43.50 ± 2.96 vs 49.66 ± 3.28 mmHg). In rats pretreated with Nω-Nitro l-arginine methyl ester (_L-NAME), the effect of juglone on MAP was reduced as compared to the control. However, in rats pretreated with atropine the fall in MAP by juglone was not altered. Juglone induced relaxation in the phenylephrine, K⁺ (80 mM), and angiotensin II pretreated isolated rat aortic rings. This vasorelaxant effect was reduced with _L-NAME pretreatment. Atropine pretreatment did not modify the vasorelaxant effect of juglone. Pre-incubation with juglone attenuated the intracellular Ca²⁺ release by suppressing phenylephrine peak formation and also shifted CaCl₂ concentration-response curves (CRCs) to the right. Of note, combined treatment with 4-aminopyridine and barium chloride also reduced juglone-mediated vasorelaxation suggesting a role of K⁺-channels as well.Conclusion: In conclusion, juglone exerts its antihypertensive effect through vasorelaxation, which is mediated by nitric oxide, inhibition of intracellular calcium release and opening of K⁺-channels.

Calcilytic NPS2143 promotes proliferation and inhibits apoptosis of spontaneously hypertensive rat vascular smooth muscle cells via activation of the renin-angiotensin system

Vascular smooth muscle cell (VSMC) proliferation and apoptosis and the renin-angiotensin system (RAS) play critical roles in the development of essential hypertension. The activation of calcium-sensing receptor (CaSR), functionally expressed in VSMCs, inhibits cyclic adenosine monophosphate (cAMP) formation by elevating intracellular calcium ([Ca²⁺]_i) and then suppressing renin release. The present study aimed to investigate the effects of NPS2143-mediated inhibition of CaSR on VSMC proliferation and apoptosis in spontaneously hypertensive rat (SHR) VSMCs and to assess whether these effects were mediated by alterations to RAS signaling. Primary VSMCs were isolated from the aortas of SHRs and Wistar-Kyoto rats. SHR VSMCs were treated with CaSR antagonist NPS2143 and cell proliferation and CaSR and RAS-related protein expression levels were measured to assess the effect. The results indicated that NPS2143 treatment promoted SHR VSMC proliferation, lower CaSR expression levels and higher RAS-related proteins levels when compared with control treatment. Additional measurement of the expression levels of proteins related to proliferation, remodeling, apoptosis and RAS related proteins, as well as cell viability, cell cycle, cell apoptosis ratio, [Ca²⁺]_i, and the concentration of cAMP was performed after treatment with NPS2143, PLC inhibitor U73122, IP3 receptor antagonist 2-aminoethoxydiphenylborane (APB), adenylyl cyclase-V inhibitor MDL12330A, angiotensin converting enzyme inhibitor captopril, angiotensin I receptor (AT1R) inhibitor losartan, NPS2143 + U73122, NPS2143 + 2-APB, NPS2143 + MDL12330A, NPS2143 + captopril and NPS2143 + losartan. The results suggested that NPS2143 promoted cell proliferation, inhibited cell apoptosis, decreased [Ca²⁺]_i and increased the expression of RAS compared with control treatments. NPS2143 + U73122 and NPS2143 + 2-APB enhanced the effects of NPS2143, while NPS2143 + MDL12330A, NPS2143 + captopril, NPS2143 + losartan attenuated the effected of NPS2143 in SHR VSMCs. Furthermore, the knockdown of AT1R by AT1R-short hairpin RNA also attenuated the effects of NPS2143 compared with NPS2143 alone. Collectively, these data indicated that NPS2143 promoted proliferation and inhibited apoptosis of VSMCs in SHRs, the effect of which was achieved by activation of RAS signaling.

Development of a novel nanoflow liquid chromatography-parallel reaction monitoring mass spectrometry-based method for quantification of angiotensin peptides in HUVEC cultures

BACKGROUND

This study aimed to develop an analytical method using liquid chromatography tandem mass spectrometry (LC-MS/MS) for the determination of angiotensin (Ang) I, Ang (1-9), Ang II, Ang (1-7), Ang (1-5), Ang III, Ang IV in human umbilical vein endothelial cell (HUVEC) culture supernatant.

METHODS

HUVEC culture supernatant was added with gradient concentrations (0.05-1,000 ng/ml) of standard solutions of the Ang peptides. These samples underwent C18 solid-phase extraction and separation using a preconcentration nano-liquid chromatography mass spectrometry system. The target peptides were detected by a Q Exactive quadrupole orbitrap high-resolution mass spectrometer in the parallel reaction monitoring mode. Ang converting enzyme (ACE) in HUVECs was silenced to examine Ang I metabolism.

RESULTS

The limit of detection was 0.1 pg for Ang II and Ang III, and 0.5 pg for Ang (1-9), Ang (1-7), and Ang (1-5). The linear detection range was 0.1-2,000 pg (0.05-1,000 ng/ml) for Ang II and Ang III, and 0.5-2,000 pg (0.25-1,000 ng/ml) for Ang (1-9) and Ang (1-5). Intra-day and inter-day precisions (relative standard deviation) were <10%. Ang II, Ang III, Ang IV, and Ang (1-5) were positively correlated with ACE expression by HUVECs, while Ang I, Ang (1-7), and Ang (1-9) were negatively correlated.

CONCLUSION

The nanoflow liquid chromatography-parallel reaction monitoring mass spectrometry-based methodology established in this study can evaluate the Ang peptides simultaneously in HUVEC culture supernatant.

Antihypertensive and Vasodilatory Effects of Qingda Granules by Suppression of Calcium Influx and the AKT Pathway

The Qingda granule (QDG) formulation was simplified from the Qingxuan Jiangya Decoction, which has been used in China to treat hypertension for decades. However, the molecular mechanisms of QDG in antihypertension remain largely unknown. Therefore, we evaluated the therapeutic efficacy of QDG against elevated blood pressure and explored its underlying mechanism. QDG treatment decreased elevated blood pressure and increased the vascular elasticity of thoracic aortic rings to KCl stimulation in spontaneously hypertensive rats. QDG treatment increased the relaxation of isolated thoracic aortic rings precontracted with norepinephrine (NE) or KCl in an endothelium-independent manner, which was attenuated by treatment with verapamil, but not by treatment with TEA, 4-AP, Gli, or BaCl2. Moreover, QDG pretreatment attenuated the CaCl2-induced constriction of isolated thoracic aortic rings in K- or NE-containing Ca-free solutions. In addition, QDG pretreatment significantly inhibited the influx of Ca in A7r5 cells induced by a K- or NE-containing Ca solution and decreased the levels of p-AKT but had no effect on levels of total AKT protein in isolated thoracic aortic rings. Considering these results, QDG treatment attenuated elevated blood pressure and promoted the vasorelaxation of thoracic aortic rings by inhibiting the influx of Ca and activating the AKT pathway.

Sauchinone inhibits angiotensin II-induced proliferation and migration of vascular smooth muscle cells

Hypertension is a common type of cardiovascular disease that remains a major cause of death in the world. Vascular remodelling is an important complication of hypertension, and vascular smooth muscle cells (VSMCs) play a major role in vascular remodelling. Sauchinone is one of the active lignins which has been found to possess vascular protective effects. However, the functional role of sauchinone in hypertension has not been investigated. The aim of this study was to evaluate the role of sauchinone in the angiotensin II (Ang II)-induced vascular remodelling model in VSMCs. The results showed that treatment of sauchinone inhibited Ang II-induced VSMCs proliferation and migration in VSMCs. Sauchinone treatment suppressed the reactive oxygen species (ROS) production and NADPH oxidase (NOX) activity in Ang II-induced VSMCs. The inhibitory effects of Ang II on expressions of VSMCs phenotype markers including α-smooth muscle actin (α-SMA), calponin, osteopontin were mitigated by sauchinone treatment. Furthermore, sauchinone inhibited Ang II-induced over-activation of TGF-β1/Smad3 signalling pathway in VSMCs. Taken together, this study identified sauchinone as a potential agent for preventing vascular remodelling in hypertension.

Atorvastatin reverses the dysfunction of human umbilical vein endothelial cells induced by angiotensin II

Statins exert pleiotropic effects on endothelial cells, in addition to lowering cholesterol. This study evaluated angiotensin II (Ang II)-induced dysfunction in human umbilical vein endothelial cells (HUVECs), and the effects of atorvastatin (Ator) on induced HUVECs in vitro. The cytotoxicity of Ang II and Ator was determined by the MTT assay. A series of cellular responses were screened, including oxidative stress, cellular apoptosis, inflammatory response, autophagy, expression of endothelial nitric oxide synthase and the angiogenic function of HUVECs. Ator returned these cellular responses to a normal level. The present study also examined cellular organelle dysfunction. In HUVECs, Ang II triggered mitochondrial damage, as demonstrated by a decreased mitochondrial membrane potential, while Ator attenuated this Ang II-induced damage. The observed cellular dysfunction may cause endothelial senescence due to excessive cell injury. The current study examined several aging markers, which revealed that these disorders of cellular functions triggered endothelial senescence, which was delayed by Ator. Ator also suppressed Ang II-induced angiogenesis damage. The data presented in this study strongly suggested that Ang II induced a series of processes that lead to cellular dysfunction in HUVECs, including oxidative stress, inflammation, and mitochondrial damage, leading to apoptosis and endothelial senescence. However, Ator significantly reversed these effects and modulated intracellular stability. The present study indicated that Ator serves an antagonistic role against HUVEC dysfunction and may potentially prevent several diseases, including coronary disease and atherosclerosis, by maintaining cellular homeostasis.

The probable roles of valsartan in alleviating chronic obstructive pulmonary disease following co-exposure to cold stress and fine particulate matter

Angiotensin II (ANG II) might play an important role in the co-effects of cold stress and fine particulate matter (PM_2.5) on chronic obstructive pulmonary disease (COPD). The purpose of this study is to evaluate the roles of valsartan in alleviating COPD following co-exposure to cold stress and PM_2.5. Both the two intervention factors are carried out upon COPD rats with the intervention of valsartan. Blockade of angiotensin receptor by valsartan decreases the levels of malondialdehyde in the normal temperature and tumor necrosis factor-α under cold stress significantly. When treated with valsartan and PM_2.5 simultaneously, the expression of 8-hydroxy-2-deoxyguanosine, nuclear factor kappa B and heme oxygenase-1 decrease significantly in the group of cold stress. In conclusion, these results indicate that valsartan might relieve the co-effects of cold stress and PM_2.5 on COPD rat lung to some degree.

Dysregulation of the Renin-Angiotensin System and the Vasopressinergic System Interactions in Cardiovascular Disorders

Purpose of Review

In many instances, the renin-angiotensin system (RAS) and the vasopressinergic system (VPS) are jointly activated by the same stimuli and engaged in the regulation of the same processes.

Recent Findings

Angiotensin II (Ang II) and arginine vasopressin (AVP), which are the main active compounds of the RAS and the VPS, interact at several levels. Firstly, Ang II, acting on AT1 receptors (AT1R), plays a significant role in the release of AVP from vasopressinergic neurons and AVP, stimulating V1a receptors (V1aR), regulates the release of renin in the kidney. Secondly, Ang II and AVP, acting on AT1R and V1aR, respectively, exert vasoconstriction, increase cardiac contractility, stimulate the sympathoadrenal system, and elevate blood pressure. At the same time, they act antagonistically in the regulation of blood pressure by baroreflex. Thirdly, the cooperative action of Ang II acting on AT1R and AVP stimulating both V1aR and V2 receptors in the kidney is necessary for the appropriate regulation of renal blood flow and the efficient resorption of sodium and water. Furthermore, both peptides enhance the release of aldosterone and potentiate its action in the renal tubules.

Summary

In this review, we (1) point attention to the role of the cooperative action of Ang II and AVP for the regulation of blood pressure and the water-electrolyte balance under physiological conditions, (2) present the subcellular mechanisms underlying interactions of these two peptides, and (3) provide evidence that dysregulation of the cooperative action of Ang II and AVP significantly contributes to the development of disturbances in the regulation of blood pressure and the water-electrolyte balance in cardiovascular diseases.

Atorvastatin inhibits the apoptosis of human umbilical vein endothelial cells induced by angiotensin II via the lysosomal-mitochondrial axis

This study was aimed to evaluate lysosomes-mitochondria cross-signaling in angiotensin II (Ang II)-induced apoptosis of human umbilical vein endothelial cells (HUVECs) and whether atorvastatin played a protective role via lysosomal-mitochondrial axis. Apoptosis was detected by flow cytometry, Hoechst 33342 and AO/EB assay. The temporal relationship of lysosomal and mitochondrial permeabilization was established. Activity of Cathepsin D (CTSD) was suppressed by pharmacological and genetic approaches. Proteins production were measured by western blotting. Our study showed that Ang II could induce the apoptosis of HUVECs in a dose-depended and time-depended manner. Exposure to 1 μM Ang II for 24 h resulted in mitochondrial depolarization, cytochrome c release, and increased ROS production. Lysosomal permeabilization and CTSD redistribution into the cytoplasm occurred several hours prior to mitochondrial dysfunction. These effects were all suppressed by atorvastatin. Either pharmacological or genetic inhibition of CTSD preserved mitochondrial function and decreased apoptosis in HUVECs. Most importantly, we found that the protective effect of atorvastatin was significantly greater than pharmacological or genetic inhibition of CTSD. Finally, overexpression of CTSD without exposure to Ang II had no effect on mitochondrial function and apoptosis. Our data strongly suggested that Ang II induced apoptosis through the lysosomal-mitochondrial axis in HUVECs. Furthermore, atorvastatin played an important role in the regulation of lysosomes and mitochondria stability, resulting in an antagonistic role against Ang II on HUVECs.

Atorvastatin protects the proliferative ability of human umbilical vein endothelial cells inhibited by angiotensin II by changing mitochondrial energy metabolism

This study aimed to explore whether angiotensin II (Ang II) inhibits the proliferation of human umbilical vein endothelial cells (HUVECs) by changing mitochondrial energy metabolism, and whether atorvastatin has a protective role via restoration of endothelial function. HUVECs were treated with 1 µM Ang II alone or with 10 µM atorvastatin for 24 h. Proliferation was detected by MTT assay, cell counting, 5-ethynyl-2′-deoxyuridine assay and real-time cell analyzer. Mitochondrial energy metabolism including oxygen consumption rate and extracellular acidification rate were measured using a Seahorse metabolic flux analyzer. Mitochondrial membrane potential was detected under fluorescence microscope following staining with tetramethylrhodamine. Respiratory chain complexes I–V were detected using western blotting. The current study showed that Ang II inhibits the proliferation of HUVECs. Results from the Seahorse metabolic flux analyzer indicated that Ang II decreased basal oxygen consumption, maximal respiration capacity, spare respiration capacity, adenosine triphosphate-linked respiration and non-mitochondrial respiration. By contrast, Ang II increased the proton leak. Additionally, Ang II increased glycolysis, glycolytic capacity and non-glycolytic acidification. Furthermore, these effects were all suppressed by atorvastatin. The results indicated that atorvastatin prevents cellular energy metabolism switching from oxidative phosphorylation to glycolysis induced by Ang II and protected the proliferative ability of HUVECs.

Silencing salusin-β attenuates cardiovascular remodeling and hypertension in spontaneously hypertensive rats

Salusin-β is a bioactive peptide involved in vascular smooth muscle cell proliferation, vascular fibrosis and hypertension. The present study was designed to determine the effects of silencing salusin-β on hypertension and cardiovascular remodeling in spontaneously hypertensive rats (SHR). Thirteen-week-old male SHR and normotensive Wistar-Kyoto rats (WKY) were subjected to intravenous injection of PBS, adenoviral vectors encoding salusin-β shRNA (Ad-Sal-shRNA) or a scramble shRNA. Salusin-β levels in plasma, myocardium and mesenteric artery were increased in SHR. Silencing salusin-β had no significant effect on blood pressure in WKY, but reduced blood pressure in SHR. It reduced the ratio of left ventricle weight to body weight, cross-sectional areas of cardiocytes and perivascular fibrosis, and decreased the media thickness and the media/lumen ratio of arteries in SHR. Silencing salusin-β almost normalized plasma norepinephrine and angiotensin II levels in SHR. It prevented the upregulation of angiotensin II and AT₁ receptors, and reduced the NAD(P)H oxidase activity and superoxide anion levels in myocardium and mesenteric artery of SHR. Knockdown of salusin-β attenuated cell proliferation and fibrosis in vascular smooth muscle cells from SHR. These results indicate that silencing salusin-β attenuates hypertension and cardiovascular remodeling in SHR.

DL0805-2, a novel indazole derivative, relaxes angiotensin II-induced contractions of rat aortic rings by inhibiting Rho kinase and calcium fluxes

AIM

DL0805-2 [N-(1H-indazol-5-yl)-1-(4-methylbenzyl) pyrrolidine-3-carboxamide] is a DL0805 derivative with more potent vasorelaxant activity and lower toxicity. This study was conducted to investigate the vasorelaxant mechanisms of DL0805-2 on angiotensin II (Ang II)-induced contractions of rat thoracic aortic rings in vitro.

METHODS

Rat thoracic aortic rings and rat aortic vascular smooth muscle cells (VSMCs) were pretreated with DL0805-2, and then stimulated with Ang II. The tension of the aortic rings was measured through an isometric force transducer. Ang II-induced protein phosphorylation, ROS production and F-actin formation were assessed with Western blotting and immunofluorescence assays. Intracellular free Ca(2+) concentrations were detected with Fluo-3 AM.

RESULTS

Pretreatment with DL0805-2 (1-100 μmol/L) dose-dependently inhibited the constrictions of the aortic rings induced by a single dose of Ang II (10(-7) mol/L) or accumulative addition of Ang II (10(-10)-10(-7) mol/L). The vasodilatory effect of DL0805-2 was independent of endothelium. In the aortic rings, pretreatment with DL0805-2 (1, 3, and 10 μmol/L) suppressed Ang II-induced Ca(2+) influx and intracellular Ca(2+) mobilization, and Ang II-induced phosphorylation of two substrates of Rho kinase (MLC and MYPT1). In VSMCs, pretreatment with DL0805-2 (1, 3, and 10 μmol/L) also suppressed Ang II-induced Ca(2+) fluxes and phosphorylation of MLC and MYPT1. In addition, pretreatment with DL0805-2 attenuated ROS production and F-actin formation in the cells.

CONCLUSION

DL0805-2 exerts a vasodilatory action in rat aortic rings through inhibiting the Rho/ROCK pathway and calcium fluxes.

Adiponectin Attenuates Angiotensin II-Induced Vascular Smooth Muscle Cell Remodeling through Nitric Oxide and the RhoA/ROCK Pathway

INTRODUCTION

Adiponectin (APN), an adipocytokine, exerts protective effects on cardiac remodeling, while angiotensin II (Ang II) induces hypertension and vascular remodeling. The potential protective role of APN on the vasculature during hypertension has not been fully elucidated yet. Here, we evaluate the molecular mechanisms of the protective role of APN in the physiological response of the vascular wall to Ang II.

METHODS AND RESULTS

Rat aortic tissues were used to investigate the effect of APN on Ang II-induced vascular remodeling and hypertrophy. We investigated whether nitric oxide (NO), the RhoA/ROCK pathway, actin cytoskeleton remodeling, and reactive oxygen species (ROS) mediate the anti-hypertrophic effect of APN. Ang II-induced protein synthesis was attenuated by pre-treatment with APN, NO donor S-nitroso-N-acetylpenicillamine (SNAP), or cGMP. The hypertrophic response to Ang II was associated with a significant increase in RhoA activation and vascular force production, which were prevented by APN and SNAP. NO was also associated with inhibition of Ang II-induced phosphorylation of cofilin. In addition, immunohistochemistry revealed that 24 h Ang II treatment increased the F- to G-actin ratio, an effect that was inhibited by SNAP. Ang II-induced ROS formation and upregulation of p22(phox) mRNA expression were inhibited by APN and NO. Both compounds failed to inhibit Nox1 and p47(phox) expression.

CONCLUSION

Our results suggest that the anti-hypertrophic effects of APN are due, in part, to NO-dependent inhibition of the RhoA/ROCK pathway and ROS formation.

Understanding the mechanisms of angiotensin II signaling involved in hypertension and its long-term sequelae: insights from Bartter's and Gitelman's syndromes, human models of endogenous angiotensin II signaling antagonism

Angiotensin II (Ang II) plays a key role in hypertension, renal and cardiovascular pathophysiology via intracellular pathways that involve the activation of a multiplicity of signaling mechanisms. Although experimental and genetic animal models have been developed and used to explore Ang II signaling's role in hypertension, a complete understanding of the processes mediating Ang II signaling in hypertension in humans remains elusive. One impediment is that these animal models do not exhibit all the traits of human hypertension, making it impossible to extrapolate from them to humans. To overcome this issue, we have used patients with Bartter's and Gitelman's syndromes, a human model of endogenously blunted and blocked Ang II signaling that presents a constellation of clinical findings which manifest themselves as the opposite of hypertension. This article reviews the aspects of the pathophysiology of human hypertension and its short and long term sequelae, and uses the results of our studies in Bartter's and Gitelman's syndromes along with those of others to gain better insight and understanding of the role of Ang II signaling in these processes.

Roles of Caveolin-1 in Angiotensin II-Induced Hypertrophy and Inward Remodeling of Cerebral Pial Arterioles

Angiotensin II (Ang II) is a major determinant of inward remodeling and hypertrophy in pial arterioles that may have an important role in stroke during chronic hypertension. Previously, we found that epidermal growth factor receptor is critical in Ang II-mediated hypertrophy that may involve caveolin-1 (Cav-1). In this study, we examined the effects of Cav-1 and matrix metalloproteinase-9 (MMP9) on Ang II-mediated structural changes in pial arterioles. Cav-1-deficient (Cav-1(-/-)), MMP9-deficient (MMP9(-/-)), and wild-type mice were infused with either Ang II (1000 ng/kg per minute) or saline via osmotic minipumps for 28 days (n=6-8 per group). Systolic arterial pressure was measured by a tail-cuff method. Pressure and diameter of pial arterioles were measured through an open cranial window in anesthetized mice. Cross-sectional area of the wall was determined histologically in pressurized fixed pial arterioles. Expression of Cav-1, MMP9, phosphorylated epidermal growth factor receptor, and Akt was determined by Western blotting and immunohistochemistry. Deficiency of Cav-1 or MMP9 did not affect Ang II-induced hypertension. Ang II increased the expression of Cav-1, phosphorylated epidermal growth factor receptor, and Akt in wild-type mice, which was attenuated in Cav-1(-/-) mice. Ang II-induced hypertrophy, inward remodeling, and increased MMP9 expression in pial arterioles were prevented in Cav-1(-/-) mice. Ang II-mediated increases in MMP9 expression and inward remodeling, but not hypertrophy, were prevented in MMP9(-/-) mice. In conclusion, Cav-1 is essential in Ang II-mediated inward remodeling and hypertrophy in pial arterioles. Cav-1-induced MMP9 is exclusively involved in inward remodeling, not hypertrophy. Further studies are needed to determine the role of Akt in Ang II-mediated hypertrophy.

ACE2 and vasoactive peptides: novel players in cardiovascular/renal remodeling and hypertension

The renin-angiotensin system (RAS) is a key component of cardiovascular physiology and homeostasis due to its influence on the regulation of electrolyte balance, blood pressure, vascular tone and cardiovascular remodeling. Deregulation of this system contributes significantly to the pathophysiology of cardiovascular and renal diseases. Numerous studies have generated new perspectives about a noncanonical and protective RAS pathway that counteracts the proliferative and hypertensive effects of the classical angiotensin-converting enzyme (ACE)/angiotensin (Ang) II/angiotensin type 1 receptor (AT1R) axis. The key components of this pathway are ACE2 and its products, Ang-(1-7) and Ang-(1-9). These two vasoactive peptides act through the Mas receptor (MasR) and AT2R, respectively. The ACE2/Ang-(1-7)/MasR and ACE2/Ang-(1-9)/AT2R axes have opposite effects to those of the ACE/Ang II/AT1R axis, such as decreased proliferation and cardiovascular remodeling, increased production of nitric oxide and vasodilation. A novel peptide from the noncanonical pathway, alamandine, was recently identified in rats, mice and humans. This heptapeptide is generated by catalytic action of ACE2 on Ang A or through a decarboxylation reaction on Ang-(1-7). Alamandine produces the same effects as Ang-(1-7), such as vasodilation and prevention of fibrosis, by interacting with Mas-related GPCR, member D (MrgD). In this article, we review the key roles of ACE2 and the vasoactive peptides Ang-(1-7), Ang-(1-9) and alamandine as counter-regulators of the ACE-Ang II axis as well as the biological properties that allow them to regulate blood pressure and cardiovascular and renal remodeling.

Angiotensin II and Cardiovascular-Renal Remodelling in Hypertension: Insights from a Human Model Opposite to Hypertension

Insights into the Angiotensin II (Ang II) signalling pathways have been provided by extensive studies using Bartter's/Gitelman's syndromes patients. These syndromes are characterized by activation of the renin-angiotensin-aldosterone system but do not develop hypertension and cardiovascular remodelling, therefore represent a mirror image of hypertension and clinically manifest themselves as the opposite of hypertension. The short and the long-term signalling of Ang II remain an important matter of investigation to shed light on mechanisms responsible for the pathophysiology of hypertension and its long-term complications, such as cardiovascular remodelling and atherogenesis. In particular the long-term signalling of Ang II is involved in the pathophysiology of cardiovascular-renal remodelling, inflammatory and hypertrophic responses in which the relationship between RhoA/Rho kinase pathway and NO system plays a crucial role. This review reports the results of our studies in Bartter's and Gitelman's syndromes to get better insight these processes and the role of Ang II signaling. The information obtained from the studies in Bartter's/Gitelman's patients can, in fact, clarify, confirm or be used to gather more general data on the biochemical mechanisms responsible for the pathophysiology of hypertension and its long-term complications and could contribute to identify additional potential significant targets of therapy.

Angiotensin II and vascular injury

Vascular injury, characterized by endothelial dysfunction, structural remodelling, inflammation and fibrosis, plays an important role in cardiovascular diseases. Cellular processes underlying this include altered vascular smooth muscle cell (VSMC) growth/apoptosis, fibrosis, increased contractility and vascular calcification. Associated with these events is VSMC differentiation and phenotypic switching from a contractile to a proliferative/secretory phenotype. Inflammation, associated with macrophage infiltration and increased expression of redox-sensitive pro-inflammatory genes, also contributes to vascular remodelling. Among the many factors involved in vascular injury is Ang II. Ang II, previously thought to be the sole biologically active downstream peptide of the renin-angiotensin system (RAS), is converted to smaller peptides, [Ang III, Ang IV, Ang-(1-7)], that are functional and that modulate vascular tone and structure. The actions of Ang II are mediated via signalling pathways activated upon binding to AT1R and AT2R. AT1R activation induces effects through PLC-IP3-DAG, MAP kinases, tyrosine kinases, tyrosine phosphatases and RhoA/Rho kinase. Ang II elicits many of its (patho)physiological actions by stimulating reactive oxygen species (ROS) generation through activation of vascular NAD(P)H oxidase (Nox). ROS in turn influence redox-sensitive signalling molecules. Here we discuss the role of Ang II in vascular injury, focusing on molecular mechanisms and cellular processes. Implications in vascular remodelling, inflammation, calcification and atherosclerosis are highlighted.

Expression of classical components of the renin-angiotensin system in the human eye

PURPOSE

The purpose of this study was to determine the relative expression of clinically-relevant components of the renin-angiotensin system (RAS) in the adult human eye.

METHODS

We obtained 14 post-mortem enucleated human eyes from patients whom had no history of inflammatory ocular disease nor pre-mortem ocular infection. We determined the gene expression for prorenin, renin, prorenin receptor, angiotensin-converting enzyme, angiotensinogen and angiotensin II Type 1 receptor, on tissue sections and in cultured human primary retinal pigment epithelial and iris pigment epithelial (RPE/IPE) cell lines, using both qualitative and quantitative reverse transcription polymerase chain reaction (RT-PCR). Protein expression was studied using indirect immunofluorescence (IF).

RESULTS

Almost all components of the classical RAS were found at high levels, at both the transcript and protein level, in the eyes' uvea and retina; and at lower levels in the cornea, conjunctiva and sclera. There was a much lower level of expression in the reference cultured RPE/IPE cells lines.

CONCLUSION

This study describes the distribution of RAS in the normal adult human eye and demonstrates the existence of an independent ocular RAS, with uveal and retinal tissues showing the highest expression of RAS components. These preliminary findings provide scope for examination of additional components of this system in the human eye, as well as possible differential expression under pathological conditions.

Vasotrophic regulation of age-dependent hypoxic cerebrovascular remodeling

Hypoxia can induce functional and structural vascular remodeling by changing the expression of trophic factors to promote homeostasis. While most experimental approaches have been focused on functional remodeling, structural remodeling can reflect changes in the abundance and organization of vascular proteins that determine functional remodeling. Better understanding of age-dependent hypoxic macrovascular remodeling processes of the cerebral vasculature and its clinical implications require knowledge of the vasotrophic factors that influence arterial structure and function. Hypoxia can affect the expression of transcription factors, classical receptor tyrosine kinase factors, non-classical G-protein coupled factors, catecholamines, and purines. Hypoxia's remodeling effects can be mediated by Hypoxia Inducible Factor (HIF) upregulation in most vascular beds, but alterations in the expression of growth factors can also be independent of HIF. PPARγ is another transcription factor involved in hypoxic remodeling. Expression of classical receptor tyrosine kinase ligands, including vascular endothelial growth factor, platelet derived growth factor, fibroblast growth factor and angiopoietins, can be altered by hypoxia which can act simultaneously to affect remodeling. Tyrosine kinase-independent factors, such as transforming growth factor, nitric oxide, endothelin, angiotensin II, catecholamines, and purines also participate in the remodeling process. This adaptation to hypoxic stress can fundamentally change with age, resulting in different responses between fetuses and adults. Overall, these mechanisms integrate to assure that blood flow and metabolic demand are closely matched in all vascular beds and emphasize the view that the vascular wall is a highly dynamic and heterogeneous tissue with multiple cell types undergoing regular phenotypic transformation.

Mechanisms underlying the antihypertensive effects of garlic bioactives

Cardiovascular disease remains the leading cause of death worldwide with hypertension being a major contributing factor to cardiovascular disease-associated mortality. On a population level, non-pharmacological approaches, such as alternative/complementary medicine, including phytochemicals, have the potential to ameliorate cardiovascular risk factors, including high blood pressure. Several epidemiological studies suggest an antihypertensive effect of garlic (Allium sativum) and of many its bioactive components. The aim of this review is to present an in-depth discussion regarding the molecular, biochemical and cellular rationale underlying the antihypertensive properties of garlic and its bioactive constituents with a primary focus on S-allyl cysteine and allicin. Key studies, largely from PubMed, were selected and screened to develop a comprehensive understanding of the specific role of garlic and its bioactive constituents in the management of hypertension. We also reviewed recent advances focusing on the role of garlic bioactives, S-allyl cysteine and allicin, in modulating various parameters implicated in the pathogenesis of hypertension. These parameters include oxidative stress, nitric oxide bioavailability, hydrogen sulfide production, angiotensin converting enzyme activity, expression of nuclear factor-κB and the proliferation of vascular smooth muscle cells. This review suggests that garlic and garlic derived bioactives have significant medicinal properties with the potential for ameliorating hypertension and associated morbidity; however, further clinical and epidemiological studies are required to determine completely the specific physiological and biochemical mechanisms involved in disease prevention and management.

Rho kinase inhibition activity of pinocembrin in rat aortic rings contracted by angiotensin II

AIM

To investigate the effects of pinocembrin on angiotensin II (Ang II)-induced vascular contraction, and to explore its molecular mechanism of actions.

METHODS

The isometric vascular tone was measured in rat thoracic aortic rings with denuded endothelium. Phosphorylation level of myosin phosphatase target unit 1 (MYPT1), and protein levels of Rho kinase 1 (ROCK1, ROKβ or p160ROCK) and angiotensin II type-1 receptor (AT1R) were determined by Western blot analysis.

RESULTS

Pinocembrin produced a relaxant effect on endothelium-denuded aortic rings contracted by Ang II (100 nmol·L(-1)) in a dose-dependent manner. In endothelium-denuded aortic rings stimulated by Ang II, pretreatment with pinocembrin (25 and 100 μmol·L(-1)) for 20 min significantly attenuated MYPT1 phosphorylation and ROCK1 protein levels. Meanwhile, the protein level of AT1R in response to Ang II was not affected by pinocembrin in rat aortic rings.

CONCLUSION

These findings indicate that pinocembrin inhibits vasoconstriction induced by Ang II in rat endothelium-denuded aortic rings, and the mechanism at least in part, is due to the blockade of the RhoA/ROCK pathway.

Overexpression of SIRT1 in vascular smooth muscle cells attenuates angiotensin II-induced vascular remodeling and hypertension in mice

Angiotensin II (AngII) induces the development of vascular hypertrophy and hypertension. We have shown previously that overexpression of class III deacetylase SIRT1 inhibits AngII-induced hypertrophy in vascular smooth muscle cells (VSMCs). However, the direct role of SIRT1 in VSMCs in response to AngII infusion in vivo remains unclear. Here, we found that the expression and activity of SIRT1 in mouse aortas was decreased significantly by AngII infusion. VSMC-specific SIRT1 transgene (SV-Tg) prevented the increase in systolic blood pressure (SBP) caused by AngII infusion without affecting heart function in mice. SIRT1 overexpression alleviated vascular remodeling in mouse thoracic and renal aortas induced by AngII infusion, and significantly inhibited reactive oxygen species (ROS) generation, vascular inflammation, and collagen synthesis in arterial walls. Reduced expression of transforming growth factor-β 1 (TGF-β1) was also observed in the aortas of AngII-infused SV-Tg mice. Moreover, SIRT1 overexpression decreased AngII-increased binding of nuclear factor-κB on its specific binding sites on TGF-β1 promoter. Taken together, these data demonstrate that SIRT1 overexpression in VSMCs reduces SBP and inhibits AngII-induced vascular remodeling in mice. The inhibition of vascular remodeling contributes, at least in part, to the antihypertensive effect of SIRT1.

KEY MESSAGE

SIRT1 is reduced in aortas of AngII-infused hypertensive mice. SIRT1 VSMC transgene alleviates AngII-increased systolic blood pressure. SIRT1 VSMC transgene attenuates AngII-induced vascular remodeling. VSMC SIRT1 overexpression inhibits remodeling-related pathological changes. VSMC SIRT1 overexpression reduces AngII-induced TGF-β1 expression.

Rutaecarpine inhibits angiotensin II-induced proliferation in rat vascular smooth muscle cells

OBJECTIVE

To evaluate the effects and possible mechanisms of rutaecarpine on angiotensin II (Ang II)-induced proliferation in cultured rat vascular smooth muscle cells (VSMCs).

METHODS

VSMCs were isolated from Male Sprague-Dawley rat aorta, and cultured by enzymic dispersion method. Experiments were performed with cells from passages 3-8. The cultured VSMCs were randomly divided into control, model (Ang II 0.1 μmol/L), and rutaecarpine (0.3-3.0 μmol/L) groups. VMSC proliferation was induced by Ang II, and was evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and cell counting. To examine the mechanisms involved in anti-proliferative effects of rutaecarpine, nitric oxide (NO) levels and NO synthetase (NOS) activity were determined. Expressions of VSMC proliferation-related genes including endothelial nitric oxide synthase (eNOS), and c-myc hypertension related gene-1 (HRG-1) were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Rutaecarpine (0.3-3.0 μmol/L) inhibited Ang II-induced VSMC proliferation and the best effects were achieved at 3.0 μmol/L. The Ang II-induced decreases in cellular NO contents and NOS activities were antagonized by rutaecarpine (P <0.05). Ang II administration suppressed the expressions of eNOS and HRG-1, while increased c-myc expression (P <0.05). All these effects were attenuated by 3.0 μmol/L rutaecarpine (P <0.05).

CONCLUSION

Rutaecarpine is effective against Ang II-induced rat VSMC proliferation, and this effect is due, at least in part, to NO production and the modulation of VMSC proliferation-related gene expressions.

Pinocembrin inhibits angiotensin II-induced vasoconstriction via suppression of the increase of [Ca2+]i and ERK1/2 activation through blocking AT(1)R in the rat aorta

Pinocembrin (5,7-dihydroxyflavanone) is one of the primary flavonoids in propolis. Angiotensin II (AngII) is a biologically active peptide that induces vasoconstriction via the activation of the angiotensin type 1 receptor (AT1R). In the present study, we investigated the vasorelaxant effect of pinocembrin on AngII-induced vasoconstriction and the molecular mechanism of action. Pinocembrin was observed to inhibit AngII-induced vasoconstriction in rat aortic rings with either intact or denuded endothelium. In endothelium-denuded tissues, pinocembrin (pD́'2pD2(') 4.28±0.15) counteracted the contractions evoked by cumulative concentrations of AngII. In a docking model, pinocembrin showed effective binding at the active site of AT1R. Pinocembrin was shown to inhibit both AngII-induced Ca(2+) release from internal stores and Ca(2+) influx. Moreover, the increase in the phosphorylation of extracellular signal-regulated kinase (ERK1/2) and myosin light chain 2 (MLC2) induced by AngII was blocked by pinocembrin. These results demonstrate that pinocembrin inhibits AngII-induced rat aortic ring contraction, and these inhibitory effects may be related to the reduction of the AngII-induced increase in [Ca(2+)]i and ERK1/2 activation via blocking AT1R.

Angiotensin II regulates the LARG/RhoA/MYPT1 axis in rat vascular smooth muscle in vitro

AIM

To identify a key protein that binds monomeric G protein RhoA and activates the RhoA/Rho kinase/MYPT1 axis in vascular smooth muscle cells (VSMCs) upon angiotensin II (Ang II) stimulation.

METHODS

Primary cultured VSMCs from Sprague-Dawley rats were transfected with siRNAs against leukemia-associated RhoGEF (LARG), and then treated with Ang II, losartan, PD123319, or Val(5)-Ang II. The target mRNA and protein levels were determined using qPCR and Western blot analysis, respectively. Rat aortic rings were isolated, and the isometric contraction was measured with a force transducer and recorder.

RESULTS

Stimulation with Ang II (0.1 μmol/L) for 0.5 h significantly increased the level of LARG mRNA in VSMCs. At 3, 6, and 9 h after the treatment with Ang II (0.1 μmol/L) plus AT(2) antagonist PD123319 (1 μmol/L) or with AT(1) agonist Val(5)-Ang II (1 μmol/L), the LARG protein, RhoA activity, and phosphorylation level of myosin phosphatase target subunit 1 (MYPT1) in VSMCs were significantly increased. Knockdown of LARG with siRNA reduced these effects caused by AT(1) receptor activation. In rat aortic rings pretreated with LARG siRNA, Ang II-induced contraction was diminished.

CONCLUSION

Ang II upregulates LARG gene expression and activates the LARG/RhoA/MYPT1 axis via AT(1), thereby maintaining vascular tone.

The roles of integrins in mediating the effects of mechanical force and growth factors on blood vessels in hypertension

Hypertension is characterized by a sustained increase in vasoconstriction and attenuated vasodilation in the face of elevated mechanical stress in the blood vessel wall. To adapt to the increased stress, the vascular smooth muscle cell and its surrounding environment undergo structural and functional changes known as vascular remodeling. Multiple mechanisms underlie the remodeling process, including increased expression of humoral factors and their receptors as well as adhesion molecules and their receptors, all of which appear to collaborate and interact in the response to pressure elevation. In this review, we focus on the interactions between integrin signaling pathways and the activation of growth factor receptors in the response to the increased mechanical stress experienced by blood vessels in hypertension.

Angiotensin II modifies the expression of α(1)-adrenoceptors in aorta smooth muscle cells of α(1D)-adrenoceptor knockout mice

1 The effect of angiotensin II (Ang II) on α(1A)-, α(1B)-, and a(1D)-adrenoceptors (α(1)-AR) expression was analyzed in aorta smooth muscle cells obtained from wild-type (WT) and knock out of α(1D)-AR (α(1D)-AR KO) mice. 2 The relative abundance of mRNA for the three α(1)-ARs was determined in WT and α(1D)-AR KO aortic smooth muscle cells. There were no significant differences between WT and α(1D)-AR KO cells. 3 As early as 1 h Ang II increased α(1B)-AR mRNA in WT cells ≈ 2 fold compared with control; in contrast, in α(1D)-AR KO cells the α(1B)-AR transcript was ≈ 50% of control. 4 Western blot assays showed that Ang II incremented protein content for α(1A)-AR, 86% and 107% in WT and α(1D)-AR KO cells, respectively. 5 Protein for α(1B)- and α(1D)-ARs did not change significantly with Ang II in both WT and a(1D)-AR KO cells. 6 The effect of Ang II on α(1B)-AR mRNA seems to be influenced by the absence of α(1D)-AR in aortic smooth muscle cells, which might be important to understand the interactions among α(1)-ARs.

Angiotensin II type 1 receptor, but no type 2 receptor, interferes with the insulin-induced nitric oxide production in HUVECs

OBJECTIVE

Two subtypes of angiotensin II (ATII) receptor have been defined on the basis of their differential pharmacological and biochemical properties: ATII-type1 receptors (AT(1)-R) and ATII-type2 receptors (AT(2)-R). It has been hypothesized that part of the protective effects on the cardiovascular system of AT(1)-R blockers is mediated by an ATII-mediated overstimulation of AT(2)-R. We hypothesized that the inhibition of AT(1)-R has a stronger impact on insulin-induced nitric oxide (NO) production than ATII-mediated overstimulation of AT(2)-R. Therefore we studied the effect of the inhibition of AT(1)-R and AT(2)-R on ATII-mediated actions in Human Umbilical Vein Endothelial Cells (HUVECs).

METHODS

We analyzed the phosphorylation state of IRS1 at Ser(616) and Ser(312) and on tyrosines after preincubation with PD123319, an inhibitor of AT(2)-R, alone and in combination with losartan, an inhibitor of AT(1)-R. In addition we measured eNOS and Akt activation through the evaluation of their phosphorylation at Ser(1177) and Ser(473) sites respectively.

RESULTS

ATII induces IRS-1 phosphorylation at Ser(312) and Ser(616) through the activation of JNK and ERK 1/2, resulting in the inhibition of the insulin-induced phosphorylation of IRS1 tyrosines, Akt and eNOS. Treatment of HUVECs with AT(1)-R inhibitor restored the insulin signaling leading to NO production, whereas AT(2)-R inhibitor did not have effects on NO production in presence of ATII.

CONCLUSION

Our results demonstrate that in presence of AT(1)-R antagonist, the AT(2)-R blockage does not modify the effect obtained with the AT(1)-R inhibition alone. Therefore, a possible positive role of an AT(2)-R overstimulation in condition of AT(1)-R antagonism seems to be irrelevant.

Nitroalkylation--a redox sensitive signaling pathway

Redox-sensitive posttranslational modification emerged as important signaling mechanisms. Besides other posttranslational modifications nitroalkylation by nitrated fatty acids mediate favorable anti-inflammatory effects. This review gives an overview of the generation and the reactivity of nitrated fatty acids. Additionally, it provides insights into the so far described pathways regulated by nitrated fatty acids. This article is part of a Special Issue entitled Regulation of Cellular Processes by S-nitrosylation.