Mechanism Analysis of a Novel Angiotensin-I-Converting Enzyme Inhibitory Peptide from Isochrysis zhanjiangensis Microalgae for Suppressing Vascular Injury in Human Umbilical Vein Endothelial Cells.

Microalgae are primary producers with multiple nutrients in aquatic environments and mostly have applications in biological feed and fuel industry. There are few studies assessing the angiotensin-I-converting enzyme (ACE) inhibition potential of Isochrysis zhanjiangensis, other than its antioxidant potential. In this study, we evaluated a peptide from I. zhanjiangensis (PIZ, FEIHCC) and its vascular endothelial factors and mechanism in human umbilical vein endothelial cells (HUVEC). The results reveal that PIZ (IC50 = 61.38 µM) acts against ACE in a non-competitive binding mode. In addition, PIZ inhibits angiotensin II (Ang II)-induced vascular factor secretion and expression by blocking inflammation and apoptosis through nuclear factor κB (NF-κB), nuclear erythroid 2-related factor 2 (Nrf2), mitogen-activated protein kinases (MAPKs), and the serine/threonine kinase (Akt) signal pathways. This study reveals that PIZ has potential to be developed as a therapeutic agent for hypertension and provides a new method of high-value utilization of I. zhanjiangensis.

Antihypertensive and renal protective effect of Shunaoxin pill combined with captopril on spontaneous hypertension rats.

INTRODUCTION: According to previous reports, hypertension has become the most common chronic disease in the world. Captopril, an angiotensin-converting enzyme inhibitor, has been widely used for the therapy of arterial hypertension and cardiovascular diseases therapy. Besides, Shunaoxin pill (SNX) as a traditional Chinese prescription showed antihypertensive effect in our previous research. OBJECTIVE: This study means to investigate whether SNX combining with captopril could show antihypertensive and renal protective effects on spontaneous hypertension rats (SHRs). METHODS: SHRs were randomly assigned to four treatment groups, including non-treated group, captopril, SNX, and captopril + SNX-treated groups. Their body weight and systolic blood pressure (SBP) were measured weekly. Histopathological examination was analyzed through Masson staining and hematoxylin and eosin staining. Biochemical analyses, ELISA, and western blot were used to analyze their combining mechanism. RESULTS: In this experiment, this combinatorial therapy significantly reduced aortic wall thickness, increased the content of NO, NOS and eNOS, decreased the content of bradykinin and endothelin 1(ET-1), and regulated the levels of TG, TC and HDLC back to normal, which suggested they could induce vasodilation and lower blood pressure. Meanwhile, histological examination alleviated that captopril + SNX remarkably inhibited renal injury, including tubular disorder, inflammatory cell infiltration and fibrosis. They down-regulated the serum levels of BUN and Cr, protein expression of IL-1ß, NF-κB, Bax, Cyt c, caspase 3, 8 and 9 in kidney tissues and significantly increased the levels of Bcl-2 in kidney tissues compared with monotherapy group. CONCLUSION: The combinatorial treatment of SNX and captopril lowered blood pressure through adjusting NO/NOS, ET-1 and dyslipidemia profile. Furthermore, this treatment alleviated the kidney damage via reducing the release of inflammatory factors and the expression of apoptotic markers. Therefore, these results provided a rationale for future clinical use of SNX combined with captopril in antihypertensive and protecting renal functions in hypertension.

A high-fat diet rich in corn oil induces cardiac fibrosis in rats by activating JAK2/STAT3 and subsequent activation of ANG II/TGF-1ß/Smad3 pathway: The role of ROS and IL-6 trans-signaling.

This study compared the effect of low-fat diet (LFD) and high-fat diet rich in corn oil (HFD-CO) on left ventricular (LV) fibrosis in rats and examined their effect of angiotensin II (ANG II), JAK/STAT, and TGF-1ß/smad3 pathways. As compared to LFD which didn't affect any of the measured parameters, HFD-CO-induced type 2 diabetes phenotype and increased LV collagen synthesis. Mechanistically, it increased LV levels of ROS, ANG II, ACE, IL-6, s-IL-6Rα, TGF-ß1, Smad-3, and activities of JAK1/2 and STAT1/3. AG490, a JAK2 inhibitor, partially ameliorated these effect while Losartan, an AT1 inhibitor completely abolished collagen synthesis. However, with both treatments, levels of ANG II, IL-6, and s-IL-6Rα, and activity of JAK1/STAT3 remained high, all of which were normalized by co-administration of NAC or IL-6 neutralizing antibody. In conclusion: HFD-CO enhances LV collage synthesis by activation of JAK1/STAT3/ANG II/TGF-1ß/smad3 pathway. PRACTICAL APPLICATIONS: We report that chronic consumption of a high-fat diet rich in corn oil (HFD-CO) induces diabetes mellitus phenotype 2 associated with left ventricular (LV) cardiac fibrosis in rats. The findings of this study show that HFD-CO, and through the increasing generation of ROS and IL-6 levels and shedding, could activate LV JAK1/2-STAT1/3  and  renin-angiotensin system (RAS) signaling pathways, thus creating a positive feedback between the two which ultimately leads to activation of TGF-1ß/Smad3 fibrotic pathway. Herein, we also report a beneficial effect of the antioxidant, NAC, or IL-6 neutralizing antibody in preventing such adverse effects of such HFD-CO. However, this presents a warning message to the current sudden increase in idiopathic cardiac disorders, especially with the big shift in our diets toward n-6 PUFA.

Preparation and antagonistic effect of ACE inhibitory peptide from cashew.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitory peptides were found to alleviate acute hepatitis significantly. In this study, we purified and identified ACE inhibitory peptide from cashew to evaluate its protective role on alcohol-induced acute hepatitis in mice. RESULTS: The ACE inhibitory peptides were purified by using consecutive chromatographic techniques. One of these peptides (FETISFK) exhibited the highest ACE inhibition rate (91.04 ± 0.31%). In vivo, the results showed that ACE inhibitory peptide decreased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) caused by alcohol exposure. Moreover, it could increase the activities of superoxide dismutase (SOD) and glutathione (GSH), and decrease the level of malondialdehyde (MDA). It was also found to down-regulate markedly the expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). It could also decrease the expression of ACE, angiotensin II (AngII) and angiotensin II type 1 receptor (AT1 R). CONCLUSION: These findings support the view that the ACE inhibitory peptide alleviated acute hepatitis by down-regulating the ACE-AngII-AT1 R axis, broadening the research approach to prevent acute hepatitis, and providing experimental data for the development and utilization of cashews. © 2019 Society of Chemical Industry.

Sini decoction alleviates E. coli induced acute lung injury in mice via equilibrating ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis.

AIMS: Acute respiratory distress syndrome (ARDS), one of the serious form of acute lung injury (ALI), is the primary cause of death in patients with ALI. Sini decoction (SND) is a widely used Traditional Chinese Medicine (TCM). However, the application of SND in ALI is rarely reported. Previous studies have found that renin-angiotensin-aldosterone system (RAAS) played vital and bidirectional roles in ALI. Therefore, the aim of the present study was to investigate protective effect of SND on ALI model induced by E. coli, as well as to further explore relations between RAAS and SND. MATERIALS AND METHODS: The ALI model was evaluated by morphological observations and biochemical assays. The expression levels of angiotensin converting enzyme (ACE), Angiotensin II type 1 receptor (AT1R) and angiotensin converting enzyme 2 (ACE2) were examined by Western blotting. The expression levels of angiotensinII (AngII) and angiotensin-(1-7) (Ang-(1-7)) were measured through ELISA. MasR, IL-6, IL-1ß and TNFα were all measured using qRT-PCR. KEY FINDINGS: SND significantly ameliorated E. coli-induced ALI, including reducing inflammatory factors in lung tissue and the activity of MPO in serum. Furthermore, SND could obviously decrease the expression of ACE, AngII and AT1R, which were induced by E. coli. On the other hand, SND could markedly activate ACE2-Ang-(1-7)-Mas pathway. SIGNIFICANCE: In this paper, we demonstrated that SND alleviates E. coli induced acute lung injury in mice via equilibrating ACE-AngII-AT1R and ACE2-Ang-(1-7)-Mas axis.

NAFLD and Atherosclerosis Are Prevented by a Natural Dietary Supplement Containing Curcumin, Silymarin, Guggul, Chlorogenic Acid and Inulin in Mice Fed a High-Fat Diet.

Non-alcoholic fatty liver disease (NAFLD) confers an increased risk of cardiovascular diseases. NAFDL is associated with atherogenic dyslipidemia, inflammation and renin-angiotensin system (RAS) imbalance, which in turn lead to atherosclerotic lesions. In the present study, the impact of a natural dietary supplement (NDS) containing Curcuma longa, silymarin, guggul, chlorogenic acid and inulin on NAFLD and atherosclerosis was evaluated, and the mechanism of action was examined. C57BL/6 mice were fed an HFD for 16 weeks; half of the mice were simultaneously treated with a daily oral administration (os) of the NDS. NAFLD and atherogenic lesions in aorta and carotid artery (histological analysis), hepatic expression of genes involved in the NAFLD (PCR array), hepatic angiotensinogen (AGT) and AT1R mRNA expression (real-time PCR) and plasma angiotensin (ANG)-II levels (ELISA) were evaluated. In the NDS group, steatosis, aortic lesions or carotid artery thickening was not observed. PCR array showed upregulation of some genes involved in lipid metabolism and anti-inflammatory activity (Cpt2, Ifng) and downregulation of some genes involved in pro-inflammatory response and in free fatty acid up-take (Fabp5, Socs3). Hepatic AGT, AT1R mRNA and ANG II plasma levels were significantly lower with respect to the untreated-group. Furthermore, NDS inhibited the dyslipidemia observed in the untreated animals. Altogether, these results suggest that NDS prevents NAFLD and atherogenesis by modulating the expression of different genes involved in NAFLD and avoiding RAS imbalance.

Increased mitochondrial superoxide in the brain, but not periphery, sensitizes mice to angiotensin II-mediated hypertension.

Angiotensin II (AngII) elicits the production of superoxide (O2•-) from mitochondria in numerous cell types within peripheral organs and in the brain suggesting a role for mitochondrial-produced O2•- in the pathogenesis of hypertension. However, it remains unclear if mitochondrial O2•- is causal in the development of AngII-induced hypertension, or if mitochondrial O2•- in the absence of elevated AngII is sufficient to increase blood pressure. Further, the tissue specific (i.e. central versus peripheral) redox regulation of AngII hypertension remains elusive. Herein, we hypothesized that increased mitochondrial O2•- in the absence of pro-hypertensive stimuli, such as AngII, elevates baseline systemic mean arterial pressure (MAP), and that AngII-mediated hypertension is exacerbated in animals with increased mitochondrial O2•- levels. To address this hypothesis, we generated novel inducible knock-down mouse models of manganese superoxide dismutase (MnSOD), the O2•- scavenging antioxidant enzyme specifically localized to mitochondria, targeted to either the brain subfornical organ (SFO) or peripheral tissues. Contrary to our hypothesis, knock-down of MnSOD either in the SFO or in peripheral tissues was not sufficient to alter baseline systemic MAP. Interestingly, when mice were challenged with chronic, peripheral infusion of AngII, only the MnSOD knock-down confined to the SFO, and not the periphery, demonstrated an increased sensitization and potentiated hypertension. In complementary experiments, over-expressing MnSOD in the SFO significantly decreased blood pressure in response to chronic AngII. Overall, these studies indicate that mitochondrial O2•- in the brain SFO works in concert with other AngII-dependent factors to drive an increase in MAP, as elevated mitochondrial O2•- alone, either in the SFO or peripheral tissues, failed to raise baseline blood pressure.

Low-protein diet supplemented with ketoacids ameliorates proteinuria in 3/4 nephrectomised rats by directly inhibiting the intrarenal renin-angiotensin system.

Low-protein diet plus ketoacids (LPD+KA) has been reported to decrease proteinuria in patients with chronic kidney diseases (CKD). However, the mechanisms have not been clarified. As over-activation of intrarenal renin-angiotensin system (RAS) has been shown to play a key role in the progression of CKD, the current study was performed to investigate the direct effects of LPD+KA on intrarenal RAS, independently of renal haemodynamics. In this study, 3/4 subtotal renal ablated rats were fed 18 % normal-protein diet (Nx-NPD), 6 % low-protein diet (Nx-LPD) or 5 % low-protein diet plus 1 % ketoacids (Nx-LPD+KA) for 12 weeks. Sham-operated rats fed NPD served as controls. The level of proteinuria and expression of renin, angiotensin II (AngII) and its type 1 receptors (AT1R) in the renal cortex were markedly higher in Nx-NPD group than in the sham group. LPD+KA significantly decreased the proteinuria and inhibited intrarenal RAS activation. To exclude renal haemodynamic impact on intrarenal RAS, the serum samples derived from the different groups were added to the culture medium of mesangial cells. It showed that the serum from Nx-NPD directly induced higher expression of AngII, AT1R, fibronectin and transforming growth factor-ß1 in the mesangial cells than in the control group. Nx-LPD+KA serum significantly inhibited these abnormalities. Then, proteomics and biochemical detection suggested that the mechanisms underlying these beneficial effects of LPD+KA might be amelioration of the nutritional metabolic disorders and oxidative stress. In conclusion, LPD+KA could directly inhibit the intrarenal RAS activation, independently of renal haemodynamics, thus attenuating the proteinuria in CKD rats.

Dietary nitrate improves age-related hypertension and metabolic abnormalities in rats via modulation of angiotensin II receptor signaling and inhibition of superoxide generation.

Advanced age is associated with increased risk for cardiovascular disease and type 2 diabetes. A proposed central event is diminished amounts of nitric oxide (NO) due to reduced generation by endothelial NO synthase (eNOS) and increased oxidative stress. In addition, it is widely accepted that increased angiotensin II (ANG II) signaling is also implicated in the pathogenesis of endothelial dysfunction and hypertension by accelerating formation of reactive oxygen species. This study was designed to test the hypothesis that dietary nitrate supplementation could reduce blood pressure and improve glucose tolerance in aged rats, via attenuation of NADPH oxidase activity and ANG II receptor signaling. Dietary nitrate supplementation for two weeks reduced blood pressure (10-15mmHg) and improved glucose clearance in old, but not in young rats. These favorable effects were associated with increased insulin responses, reduced plasma creatinine as well as improved endothelial relaxation to acetylcholine and attenuated contractility to ANG II in resistance arteries. Mechanistically, nitrate reduced NADPH oxidase-mediated oxidative stress in the cardiovascular system and increased cGMP signaling. Finally, nitrate treatment in aged rats normalized the gene expression profile of ANG II receptors (AT1A, AT2, AT1A/AT2 ratio) in the renal and cardiovascular systems without altering plasma levels of renin or ANG II. Our results show that boosting the nitrate-nitrite-NO pathway can partly compensate for age-related disturbances in endogenous NO generation via inhibition of NADPH oxidase and modulation of ANG II receptor expression. These novel findings may have implications for nutrition-based preventive and therapeutic strategies against cardiovascular and metabolic diseases.

Influence of Sanao Tang on urine volume and expression of aquaporin 2 in rats with respiratory function impairment induced by passive smoking and lipopolysaccharide.

OBJECTIVE: To investigate the effect of Sanao Tang (SAT) on urine volume and the expression of aquaporin- 2 (AQP2) in rats with lung dysfunction induced by passive smoking and lipopolysaccharide. METHODS: Totally 45 healthy Specific pathogen Free Wistar Rats were randomized into 3 groups: normal control group, model group and SAT group. A rat model of respiratory dysfunction induced by exposure to cigarette smoking and lipopolysaccharide (LPS). Lavage of decoction of the Chinese medicine was performed for rats in the SAT group. Anires 2005 System was used to analyze the pulmonary function. Urine of rats was collected through metabolism cage method. Enzyme-linked immunosorbent assay (ELISA) was used to determine content of antidiuretic hormone (ADH), angiotensin Ⅱ (AngⅡ), atrial natriuretic factor (ANP), endothelin 1 (ET-1), nitric oxide (NO) and prostaglandin E2 (PGE2) in serum, lung and kidney. The expression of AQP2 in rat renal tissue was determined with real-time fluorescence quantitative PCR (RT-PCR). RESULTS: (a) In comparison with the normal control, It was found that enforced vital capacity (FVC), 1-second forced expiratory volume/forced vital capacity% (FEV(1)/FVC%), 24 h urine volume content of NO and PGE2 were decreased, while AQP2mRNA level and content of ADH, Agn Ⅱ, ANP and ET-1 were increased in the model group with statistical significance (P < 0.05). (b) In comparison with the model group, It was found that FVC, FEV(1), FEV(1)/FVC%, 24 h urine volume, content of PGE2 and NO decreased, while AQP2mRNA level, content of ANP, ADH and Ang Ⅱ decreased in the SAT group with statistical significance (P < 0.05). CONCLUSION: SAT might effectively regulate the urine volume in the modeled rats; ADH, Ang Ⅱ, ANP, ET-1, NO and PGE2 might play an important role in the regulation on urine volume by lungs. This might be the mechanisms underpinning the function of lung governing water passage in terms of the theory of Traditional Chinese Medicine.

Nifedipine attenuation of abdominal aortic aneurysm in hypertensive and non-hypertensive mice: Mechanisms and implications.

Rupture of abdominal aortic aneurysm (AAA) is a lethal event. No oral medicine has been available to prevent or treat AAA. We have recently identified a novel mechanism of eNOS uncoupling by which AAA develops, in angiotensin II (Ang II) infused hyperphenylalaninemia 1 (hph-1) mice. Using this unique model we investigated effects on AAA formation of the L-type calcium channel blocker nifedipine, in view of the unclear relationship between hypertension and AAA, and unclear mechanisms of aneurysm protective effects of some blood pressure lowering drugs. Six-month old hph-1 mice were infused with Ang II (0.7 mg/kg/day) for 2 weeks, and fed nifedipine chow at two different doses (5 and 20 mg/kg/day). While the high dose of nifedipine reduced blood pressure, the lower dose had no effect. Interestingly, the incidence rate of AAA dropped from 71% to 7 and 12.5% for low and high dose nifedipine, respectively. Expansion of abdominal aorta, determined by ultrasound imaging, was abolished by both doses of nifedipine, which recoupled eNOS completely to improve NO bioavailability. Both also abrogated aortic superoxide production. Of note, Ang II activation of NADPH oxidase in vascular smooth muscle cells and endothelial cells, known to uncouple eNOS, was also attenuated by nifedipine. Although low dose was a sub-pressor while the high dose reduced blood pressure via inhibition of calcium channels, both doses were highly effective in preventing AAA by preserving eNOS coupling activity to eliminate sustained oxidative stress from uncoupled eNOS. These data demonstrate that oral treatment of nifedipine is highly effective in preserving eNOS function to attenuate AAA formation. Nifedipine may be used for AAA prevention either at low dose in AAA risk group, or at high dose in patients with co-existing hypertension.

Yiqi Huaju formula, a Chinese herbal medicine, reduces arterial pressure in salt­sensitive hypertension by inhibiting renin­angiotensin system activation.

Hypertension is a chronic disease with a high prevalence, and is associated with a high risk of vascular disease and premature death. Traditional Chinese medicine has been administered to treat hypertension for many years. In the present study, the effects of Yiqi Huaju formula (YQ; a compound used in traditional Chinese herbal medicine) were observed in salt­sensitive hypertension, which was induced by a high­salt and high­fat (HSF) diet and the potential mechanism was investigated. YQ was prepared from five plant extracts and was dissolved in normal sodium chloride prior to use. Male Sprague­Dawley rats were randomly divided into three groups, and fed either a normal diet (control), an HSF diet or an HSF diet with YQ. At week eight, blood pressure was measured and 24­h urine samples were collected from all of the rats. The rats were subsequently sacrificed, and their blood was collected for biochemical analyses and kidney tissue samples were dissected for the immunohistochemical assay. YQ was observed to decrease the high arterial pressure and serum total cholesterol level, which had been induced by the HSF diet. It also enhanced the excretion of urinary angiotensinogen, Na+, and decreased the loss of urinary aldosterone, K+ and microalbuminuria. In addition, YQ inhibited the high mRNA expression level of renal renin, angiotensin II (Ang II), and Ang II receptor, type 1 (AT1R), and inhibited the protein expression of renal AT1R and Ang II receptor type 2, which had been induced by the HSF diet. These results indicate that YQ may reduce the arterial pressure in salt­sensitive hypertension via the inhibition of renin­angiotensin system activation.

Long-Term Reduction of High Blood Pressure by Angiotensin II DNA Vaccine in Spontaneously Hypertensive Rats.

Recent research on vaccination has extended its scope from infectious diseases to chronic diseases, including Alzheimer disease, dyslipidemia, and hypertension. The aim of this study was to design DNA vaccines for high blood pressure and eventually develop human vaccine therapy to treat hypertension. Plasmid vector encoding hepatitis B core-angiotensin II (Ang II) fusion protein was injected into spontaneously hypertensive rats using needleless injection system. Anti-Ang II antibody was successfully produced in hepatitis B core-Ang II group, and antibody response against Ang II was sustained for at least 6 months. Systolic blood pressure was consistently lower in hepatitis B core-Ang II group after immunization, whereas blood pressure reduction was continued for at least 6 months. Perivascular fibrosis in heart tissue was also significantly decreased in hepatitis B core-Ang II group. Survival rate was significantly improved in hepatitis B core-Ang II group. This study demonstrated that Ang II DNA vaccine to spontaneously hypertensive rats significantly lowered high blood pressure for at least 6 months. In addition, Ang II DNA vaccines induced an adequate humoral immune response while avoiding the activation of self-reactive T cells, assessed by ELISPOT assay. Future development of DNA vaccine to treat hypertension may provide a new therapeutic option to treat hypertension.

[Effect of tanshinone II(A) on expression of different components in renin-angiotensin system of left ventricles of hypertensive rats].

OBJECTIVE: To investigate the effect of tanshinone II(A) on the expression of different components in the renin-angiotensin system of left ventricles of renal hypertensive rats. METHOD: The renal hypertension model was established in rats by the two-kidney-one-clip (2K1C) method. In the experiment, all of the rats were randomly divided into four groups (n = 15 per group) before the operation: the sham-operated (Sham) group, the hypertensive model (Model) group, the low-dose tanshinone II(A) group and the high-dose tanshinone II(A) group. At 5 week after the renal artery narrowing, the third and fourth groups were administered with 35 mg kg(-1) x d(-1) and 70 mg x kg(-1) x d(-1) of tanshinone II(A), respectively. The blood pressure in rats was determined by the standard tail-cuff method in each week after the operation. After the drug treatment for 8 weeks, all the rats were put to death, and their left ventricles were separated to determine the ratio of left ventricle weight to body weight (LVW/BW), the myocardial collagen content, and the expressions of different components in myocardial RAS, including angiotensin converting enzyme (ACE), angiotensin converting enzyme 2 (ACE2), angiotensin 1-type receptor (AT1R), Mas receptor mRNA expression and angiotensin II (Ang II) and angiotensin (1-7) [Ang (1-7)] content. RESULT: Compared with the sham group, the hypertensive model group exhibited a markable increase in the content of Ang II and Ang (1-7) and the mRNA expressions of ACE, ACE2, AT1R and Mas (P < 0.01). However, the treatment with tanshinone II(A) showed the does dependence, inhibited left ventricle hypertrophy, decreased myocardial Ang II content and the mRNA expression of ACE and AT, R in renal hypertensive rats (P < 0. 01) , further increased the myocardial Ang (1-7) content and the mRNA expression of ACE2 and Mas (P < 0.01) , but without any change in the blood pressure of hypertensive rats. CONCLUSION: The treatment with tanshinone II(A) could inhibit left ventricle hypertrophy of renal hypertensive rats. Its mechanism may be partially related to the expression of different components in the renin-angiotensin system for regulating myocardial tissues.

Serine carboxypeptidase SCPEP1 and Cathepsin A play complementary roles in regulation of vasoconstriction via inactivation of endothelin-1.

The potent vasoconstrictor peptides, endothelin 1 (ET-1) and angiotensin II control adaptation of blood vessels to fluctuations of blood pressure. Previously we have shown that the circulating level of ET-1 is regulated through its proteolytic cleavage by secreted serine carboxypeptidase, cathepsin A (CathA). However, genetically-modified mouse expressing catalytically inactive CathA S190A mutant retained about 10-15% of the carboxypeptidase activity against ET-1 in its tissues suggesting a presence of parallel/redundant catabolic pathway(s). In the current work we provide direct evidence that the enzyme, which complements CathA action towards ET-1 is a retinoid-inducible lysosomal serine carboxypeptidase 1 (Scpep1), a CathA homolog with previously unknown biological function. We generated a mouse strain devoid of both CathA and Scpep1 activities (DD mice) and found that in response to high-salt diet and systemic injections of ET-1 these animals showed significantly increased blood pressure as compared to wild type mice or those with single deficiencies of CathA or Scpep1. We also found that the reactivity of mesenteric arteries from DD mice towards ET-1 was significantly higher than that for all other groups of mice. The DD mice had a reduced degradation rate of ET-1 in the blood whereas their cultured arterial vascular smooth muscle cells showed increased ET-1-dependent phosphorylation of myosin light chain 2. Together, our results define the biological role of mammalian serine carboxypeptidase Scpep1 and suggest that Scpep1 and CathA together participate in the control of ET-1 regulation of vascular tone and hemodynamics.

An ethanolic extract of Lindera obtusiloba stems, YJP-14, improves endothelial dysfunction, metabolic parameters and physical performance in diabetic db/db mice.

Lindera obtusiloba is a medicinal herb traditionally used in Asia for improvement of blood circulation, treatment of inflammation, and prevention of liver damage. A previous study has shown that an ethanolic extract of Lindera obtusiloba stems (LOE) has vasoprotective and antihypertensive effects. The possibility that Lindera obtusiloba improves endothelial function and metabolic parameters in type 2 diabetes mellitus (T2DM) remains to be examined. Therefore, the aim of the present study was to determine the potential of LOE to prevent the development of an endothelial dysfunction, and improve metabolic parameters including hyperglycemia, albuminuria and physical exercise capacity in db/db mice, an experimental model of T2DM. The effect of LOE (100 mg/kg/day by gavage for 8 weeks) on these parameters was compared to that of an oral antidiabetic drug, pioglitazone (30 mg/kg/day by gavage). Reduced blood glucose level, body weight and albumin-creatinine ratio were observed in the group receiving LOE compared to the control db/db group. The LOE treatment improved endothelium-dependent relaxations, abolished endothelium-dependent contractions to acetylcholine in the aorta, and normalized the increased vascular oxidative stress and expression of NADPH oxidase, cyclooxygenases, angiotensin II, angiotensin type 1 receptors and peroxynitrite and the decreased expression of endothelial NO synthase in db/db mice. The angiotensin-converting enzyme (ACE) activity was reduced in the LOE group compared to that in the control db/db group. LOE also inhibited the activity of purified ACE, COX-1 and COX-2 in a dose-dependent manner. In addition, LOE improved physical exercise capacity. Thus, the present findings indicate that LOE has a beneficial effect on the vascular system in db/db mice by improving endothelium-dependent relaxations and vascular oxidative stress most likely by normalizing the angiotensin system, and also on metabolic parameters, and these effects are associated with an enhanced physical exercise capacity.

Epigallocatechin-3-gallate inhibits angiotensin II and interleukin-6-induced C-reactive protein production in macrophages.

BACKGROUND: Consumption of green tea has been associated with health benefits against multiple diseases including cardiovascular diseases. However, the action mechanisms of green tea and its major ingredient epigallocatechin-3-gallate (EGCG) against cardiovascular diseases are still unclear. Emerging evidence has suggested a common role for C-reactive protein (CRP) in the pathogenesis of inflammation and atherosclerosis. Therefore, the effect of EGCG on angiotensin II (Ang II)- and interleukin-6 (IL-6)-induced CRP production in U937 macrophages and the possible mechanisms were observed. METHODS: U937 macrophages were cultured, and Ang II and IL-6 were used as stimulants for generation of CRP. U937 macrophages were preincubated with EGCG at 1, 3, 10 µM for 1 h prior to the stimulation. mRNA expression and protein level were determined by RT-PCR and ELISA, respectively. ROS production was observed by a fluorescence microscope. RESULTS: Pretreatment of macrophages with EGCG prior to the stimulation concentration-dependently inhibited Ang II- and IL-6-induced expression of CRP both in protein and mRNA levels. Meanwhile, EGCG reduced Ang II- and IL-6-stimulated generation of ROS in macrophages. CONCLUSION: EGCG is able to inhibit Ang II- and IL-6-stimulated CRP expression in macrophages to produce an anti-inflammation by interfering with ROS generation. The finding is helpful to update understanding of anti-atherosclerotic effects of EGCG.

Influence of angiotensin-converting enzyme insertion/deletion polymorphism on nitric oxide production in hypertensives and hypercholesterolaemics.

UNLABELLED: WHAT IS NEW AND OBJECTIVE: Some evidence suggests that angiotensin-converting enzyme insertion/deletion (I/D) polymorphism may play a role in endothelium-dependent vasodilatation. However, the impact of I/D polymorphism on endogenous nitric oxide production, which may be of great therapeutic significance, has scarcely been studied. This study aimed to investigate this in hypertensives and hypercholesterolaemics. METHODS: Adult Han subjects were recruited by cluster sampling from two communities in Shunde, Guangdong province, China. Plasma nitrite and nitrate (NO(x)) levels were determined by colorimetry assay and angiotensin II and 6-keto-prostaglandin F1-alpha by radioimmunoassay. Angiotensin-converting enzyme gene I/D polymorphism were genotyped by polymer chain reaction-amplified fragment length polymorphism. RESULTS AND DISCUSSION: Of the 779 subjects who met our inclusion criteria, 502 were with normotensive and normocholesterolaemic, 76 had hypertension only, 146 hypercholesterolaemia only, and 55 had both hypertension and hypercholesterolaemia. Among subjects with hypertension only, the plasma levels of NO(x) for genotype DD were significantly lower than those for genotype II (P = 0·034). And the plasma levels of NO(x) for genotype DD was significantly higher than those for genotype II (P = 0·040) in subjects with hypercholesterolaemia only. WHAT IS NEW AND CONCLUSION: Our results suggest that I/D polymorphism has an impact on in vivo NO production in hypertensives and hypercholesterolaemics at the population level. Hypertensives with allele D may be benefit from L-arginine supplementation and hypercholesterolaemics with allele D may respond better to statins or antioxidants.

[Effects of Shenkangwan on renal expressions of angiotensin II and its type I receptor in rats with early diabetic nephropathy].

OBJECTIVE: To investigate the effects of Shenkangwan on the expressions of angiotensin II (AngII) and its type I receptor (AT(1)R) and the renalprotection mechanism of Shenkangwan in rats with early diabetic nephropathy (DN). METHODS: The rat models of DN established by a single injection of streptozotocin were randomly divided into 4 groups, namely the model group, Shenkangwan treatment group, irbesartan treatment group, and Shenkangwan and irbesartan treatment group, with normal rats as the control. All the rats received daily gavage for 8 weeks. The urinary protein quality in 24 h and plasma and renal contents of AngII were measured. The expressions of AT1R at the protein and mRNA levels in the kidney tissues were measured by immunohistochemistry and reverse transcription-polymerase chain reaction, respectively. The pathological changes of the kidney were observed microscopically. RESULTS: In DN rats, Shenkangwan reduced the urinary protein quantity in 24 h and the contents of AngII in the plasma and kidney tissues, decreased the renal expressions of AT(1)R protein and mRNA, and alleviated the morphological damage of the kidney. CONCLUSIONS: Shenkangwan offers renalprotection against DN probably by reducing the contents of AngII in the plasma and kidney tissues and inhibiting renal AT(1)R expressions.

Salvia miltiorrhiza depresses plasminogen activator inhibitor-1 production through inhibition of angiotensin II.

The purpose of this study was to investigate the effect of Salvia miltiorrhiza on the production of plasminogen activator inhibitor-1(PAI-1) induced by angiotensin II (Ang II) in renal mesangial cells. Rat mesangial cells were exposed to 100 nM Ang II. Meanwhile, different concentrations of Salvia miltiorrhiza injection were added to Mesangial Cells. PAI-1 mRNA was measured by semi-quantification reverse transcriptase polymerase chain reaction (RT-PCR) and PAI-1 protein by Western blotting. ELISA was used to detect the expression of transforming growth factor beta(1) (TGF-beta(1)) in serum free MEM medium. The level of cellular reactive oxygen species (ROS) was measured by confocal laser scanning microscopy. Salvia miltiorrhiza notably attenuated expression of PAI-1 induced by Ang II in a concentration-dependent manner. Meanwhile, it suppressed the production of TGF-beta(1) and cellular ROS in mesangial cells. These effects were due to Salvia miltiorrhiza's ability of inhibiting the activities of angiotensin II. Therefore, Salvia miltiorrhiza can be used to retard progression of glomerular sclerosis.