P2577Losartan diminishes the expression of TGF-beta and improves cardiomyopathy in mice with Marfan syndrome

Introduction

Marfan syndrome (MFS) is caused by mutations in the fibrillin-1 gene, leading to abnormal signaling of the transforming growth factor beta (TGF-β). This results in aortic root dilation, dissection and rupture, which are the main causes of morbidity and mortality of MFS patients. Current treatment with losartan, an angiotensin-II receptor-1 blocker, has shown beneficial effect on aortic disease in MFS murine models. However, the mechanisms whereby the treatment with losartan improves cardiac remodeling and function of the left ventricle (LV) in MFS are still unknown.

Purpose

To investigate the effects of losartan on mechanisms of the cardiomyopathy in mice with MFS.

Methods

mgΔloxPneo MFS murine model from C129/sv background was utilized in this study. To evaluate the effect of the treatment with losartan on the LV of MFS and wild-type mice, animals were allocated in 2 groups of treatments: Losartan group: mice were kept with water supplemented with losartan (0.6g/L); Untreated control group: mice were kept with water only. The animals received treatment from 1 month of age until completing 6 months. After five months of treatment, LV echocardiography was performed, and fragments of LV tissue were analyzed by morphometry and protein expression analysis by Western blot.

Results

Losartan MFS mice showed decrease in interventricular septum and posterior wall thickness and LV mass. Furthermore, losartan prevented aortic and mitral regurgitation, arrhythmia, bradycardia, septal hypokinesia and pulmonary hypertension when compared with control MFS mice. Systolic and diastolic LV function were not different between groups. Collagen volume fraction and the disorganization and disruptions of the elastic fibers in coronary arteries were lower in losartan treatment than in controls. The protein expression of pro-apoptotic factors (BAX/Bcl-2 and caspase 3 and 9), proliferating cell nuclear antigen and hypoxia-inducible factor 1 and 2α were lower in losartan treatment, whereas the expression of vascular endothelial growth factor was increased in losartan group when compared with control MFS mice. Moreover, the treatment with losartan strongly reduced the TGF-β, ERK and p38MAPK protein expression compared to controls.

Conclusion

In this murine model of MFS, losartan treatment has the ability to change several pathophysiological mechanisms related with the fibrillin-1 mutation, by decreasing apoptosis, cell proliferation and increasing angiogenesis. Overall, the treatment resulted in improved structural rearrangement and attenuation of the rupture of elastic fibers in the coronary arteries, of the cardiac hypertrophy and myocardial fibrosis. These effects were possibly related with the decreased TGF-β expression by ERK and p38MAPK signaling pathways by losartan. Our findings shed a new light on the mechanisms of action of losartan on MFS cardiomyopathy.

Acknowledgement/Funding

FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo)

4096Additive effects of exercise training upon cognitive function in regular red wine consumers compared to abstainers

Background

Although regular red wine (RW) consumption and physical exercise (PE) exert cardiovascular protection a possible aditive effect of both is unknown, especially regarding cognition.

Purpose

To investigate the effects of supervised PE upon cognitive function in regular RW consumers compared to abstainers (Abs)

Methods

Cognitive function was assessed by functional Cerebral Magnetic Resonance Image (fMRI) through Stroop Color Word test (Stroop) for executive function and 2-back for working memory as well as neuropsychological tests (trails A, B and Stroop1). Seventy three healthy males, aged 59±5.9 (SD) years were divided into 4 groups: 37 Abs (17 with PE, 20 without) and 36 RW drinkers (17 with PE, 19 without) and then were randomized in the pre-PE phase, either to supervised PE for 3 months, 3x week/1h duration or no PE. Cardiopulmonary exercise test (CET) was performed before and after interventions. Plasma lipids and glucose also were measured.

Results

Drinkers ingested 19.8±10.3 (SD) gr of ethanol/day as RW for an average of 26.1±15.7 years and did not change their habits during the study period. In pre-PE phase RW drinkers showed lower execution times than Abs in neurophsychological tests (trails A and B and Stroop1) and higher accuracy in the 2-back test in fMRI (p<0.05 for both). Furthermore, in post intervention phase, RW consumers with PE showed a trend towards improvement in executive function (Stroop: % accuracy 92.5±9.2 vs 95.6±5.0, p=0.05) and reduction in execution time (21.9±6 vs 19±3.4; p=0.049) as well as in neuropsychological Stroop-2 (p<0.05).In parallel there were no changes in activated cerebral áreas in either group after PE. However, there was a negative correlation between peak VO2 and activated brain areas by fMRI (Expert Analysis Tool based on the Generalized Linear Model; p<0.05) in both Abs and drinkers.

In contrast, there were no significant changes in any cognition test among abstainers regardless of PE; also there were no changes in metabolic profile. PE induced significant increments in peak VO2 in all PE groups (p<0.05).

fMRI BOLD sign during 2-back test

Conclusion

Physical exercise induced further improvement in executive function and working memory in long term RW drinkers, while no effects occurred in abstainers. Such effect was correlated with global fitness, as assessed by peak VO2.

Acknowledgement/Funding

Fundação de Amparo à Pesquisa do Estado de São Paulo; Banco Bradesco SA

P2683Beneficial effects of red wine intake upon gut microbiota and parallel effects upon plasma metabolomics

Background

Evidence suggests that red wine (RW) components can influence favorably gut microbiota. However, Interactions of RW, gut microbiota and plasma metabolomics remain unclear.

Purpose

The goal of this study was to assess the effects upon gut microbiota and plasma metabolomic profile of short-term, moderate RW intake in patients (pts) with documented coronary artery disease (CAD)

Methods

Forty-two males aged 60.4±5.4 years (SD) with documented CAD by angiography underwent a randomized, crossover, controlled, interventional trial. They were assigned to either RW treatment or abstinence from any alcoholic beverage, as control. Each treatment was preceded by a 2-week washout period. During the RW intervention, subjects ingested 250 ml of RW per day/ 5 days a week/ 3 weeks. Fasting blood samples and fecal samples were collected 4 times, after washout and at the end of each 3-week intervention. Gut microbiota was analysed by 16 S rRNA gene sequences and plasma metabolomics was performed by Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy. Twenty pts chosen randomly had their global metabolic profiles examined at all visits. Diet was carefully controlled and quantified by a 3 day/week questionnaire at beginning and end of the study. Prebiotics, probiotics were not allowed during the study. Patients in need for antibiotic therapy were not included.

Results

In the RW period compared to abstinence, fecal metagenomic revealed a decrease in abundance of Collinsella, a bacterial genus correlated with atherosclerosis; an increase in Eubacterium, genus related to fiber digestion and bile acid metabolism; and a significant increase in alpha diversity (p<0.05 for all). In plasma, trimethylamine N-oxide (TMAO), fell non-significantly post RW consumption. HDL and resveratrol increased after RW consumption (p<0.05). Plasma metabolomic analysis of 20 pts revealed microbiome related changes associated with RW consumption: decreased levels of phenylalanine, benzoate, tyrosine and tryptophan; lower levels of primary bile acids (BA) cholate, taurocholate, and also secondary BA deoxycholate and lithocholate sulfate. In parallel, RW elevated androgenic steroids and decreased beta oxidation (p<0.05 for all). Simultaneously total energy, proteins, carbohydrates and fat components of the diet did not change significantly.

Conclusions

Moderate RW ingestion augmented microbiota diversity, increased the proportion of putative anti-atherosclerotic bacteria and influenced plasma metabolomics. RW influenced energy metabolism through gut microbiota related plasma changes in amino acids, nucleotide profile, bile acids, androgenic steroids and beta-oxidation. These findings furnish some novel insight into mechanisms whereby RW may mitigate atherosclerosis.

Acknowledgement/Funding

FAPESP (Fundacao de Amparo à Pesquisa do Estado de Sao Paulo), IBRAVIN (Instituto Brasileiro do Vinho), Banco Bradesco SA

Novel antiplatelet role for a protein disulfide isomerase-targeted peptide: evidence of covalent binding to the C-terminal CGHC redox motif

Essentials Inhibitors of protein disulfide isomerase (PDI) have been considered a new antithrombotic class. CxxC is a PDI-targeted peptide that has been previously shown to inhibit its reductase activity. CxxC binds to surface PDI and inhibits ADP- and thrombin-evoked platelet activation and aggregation. CxxC binds to Cys400 on CGHC redox motif of PDI a' domain, a site for PDI prothrombotic activity.

SUMMARY

Background Protein disulfide isomerase (PDI) plays a major role in platelet aggregation, and its inhibitors have emerged as novel antithrombotic drugs. In previous work, we designed a peptide based on a PDI redox motif (CGHC) that inhibited both PDI reductase activity and PDI-modulated superoxide generation by neutrophil Nox2. Thus, we hypothesized that this peptide would also inhibit platelet aggregation by association with surface PDI. Methods Three peptides were used: CxxC, containing the PDI redox motif; Scr, presenting a scrambled sequence of the same residues and AxxA, with cysteines replaced by alanine. These peptides were tested under platelet aggregation and flow cytometry protocols to identify their possible antiplatelet activity. We labeled membrane free thiol and electrospray ionization liquid chromatography tandem mass spectrometry to test for an interaction. Results CxxC decreased platelet aggregation in a dose-dependent manner, being more potent at lower agonist concentrations, whereas neither AxxA nor Scr peptides exerted any effect. CxxC decreased aIIbb3 activation, but had no effect on the other markers. CxxC also decreased cell surface PDI pulldown without interfering with the total thiol protein content. Finally, we detected the addition of one CxxC molecule to reduced PDI through binding to Cys400 through mass spectrometry. Interestingly, CxxC did not react with oxidized PDI. Discussion CxxC has consistently shown its antiplatelet effects, both in PRP and washed platelets, corroborated by decreased aIIbb3 activation. The probable mechanism of action is through a mixed dissulphide bond with Cys400 of PDI, which has been shown to be essential for PDI's actions. Conclusion In summary, our data support antiplatelet activity for CxxC through binding to Cys400 in the PDI a0 domain, which can be further exploited as a model for sitedriven antithrombotic agent development.

Lipoic acid, but not tempol, preserves vascular compliance and decreases medial calcification in a model of elastocalcinosis

Vascular calcification decreases compliance and increases morbidity. Mechanisms of this process are unclear. The role of oxidative stress and effects of antioxidants have been poorly explored. We investigated effects of the antioxidants lipoic acid (LA) and tempol in a model of atherosclerosis associated with elastocalcinosis. Male New Zealand white rabbits (2.5-3.0 kg) were fed regular chow (controls) or a 0.5% cholesterol (chol) diet+10⁴ IU/day vitamin D₂ (vitD) for 12 weeks, and assigned to treatment with water (vehicle, n=20), 0.12 mmol·kg^-1·day^-1 LA (n=11) or 0.1 mmol·kg^-1·day^-1 tempol (n=15). Chol+vitD-fed rabbits developed atherosclerotic plaques associated with expansive remodeling, elastic fiber disruption, medial calcification, and increased aortic stiffness. Histologically, LA prevented medial calcification by ∼60% and aortic stiffening by ∼60%. LA also preserved responsiveness to constrictor agents, while intima-media thickening was increased. In contrast to LA, tempol was associated with increased plaque collagen content, medial calcification and aortic stiffness, and produced differential changes in vasoactive responses in the chol+vitD group. Both LA and tempol prevented superoxide signals with chol+vitD. However, only LA prevented hydrogen peroxide-related signals with chol+vitD, while tempol enhanced them. These data suggest that LA, opposite to tempol, can minimize calcification and compliance loss in elastocalcionosis by inhibition of hydrogen peroxide generation.

Increased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia

BACKGROUND AND PURPOSE

There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries.

EXPERIMENTAL APPROACH

Vascular reactivity to ET-1 and ET(A) and ET(B) receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET(A) and ET(B) receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [(125)I]-ET-1.

KEY RESULTS

HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET(A) or ET(B) receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET(A) but not of ET(B) receptors abolished enhancement in HHcy tissues. ET(A) and ET(B) receptor gene expressions were not up-regulated. ET(A) receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A(2) receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO.

CONCLUSIONS AND IMPLICATIONS

Increased ET(A) receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET(A) receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility.

High levels of active quiescin Q6 sulfhydryl oxidase (QSOX) are selectively present in fetal serum

The participation of thiol-oxidoreductases such as thioredoxin during implantation, embryogenesis and fetal development has been extensively studied. Here, we analyzed the expression of the thioredoxin superfamily enzyme quiescin Q6/sulfhydryl oxidase (QSOX) during development. Results show that QSOX is present in fetal bovine serum (4 months' gestation), but its levels decrease with time after birth (from P1 to P60). We also demonstrate that a sulfhydryl oxidase activity correlates with QSOX expression in such sera, suggesting a putative role in the redox modulation of developmental programs.

Redox Mechanisms of Vascular Cell Dysfunction in Sepsis

Sepsis remains one of the leading causes of death in intensive care units, despite recent acquired knowledge on pathophysiology and treatment. Several mediators of inflammation and cellular damage have been implicated in the complex host-pathogen interaction underlying organ damage and multisystem organ failure , which are hallmarks of sepsis and common causes of death. Among such mediators, reactive oxygen/nitrogen species have been increasingly studied in the context of direct cytotoxicity as well as altered cell signaling. While the generation of reactive oxygen species by inflammatory cells in sepsis is well known, recent studies have shown that vascular cells are able to release reactive oxygen intermediates that may be associated with endothelial dysfunction of sepsis. These compounds can activate transcription factors such as NF-kappaB that sustain inflammatory process or enzymatic systems like poly(ADP-ribose) polymerase-1, which are involved in apoptosis and cytotoxicity of sepsis. Our laboratory recently showed that platelet-derived exosomes from septic patients carry components of a superoxide-producing NADPH oxidase and can, at least in vitro, induce apoptosis of endothelial and vascular smooth muscle cells by a ROS-dependent pathway. Taken together, these data show that reactive oxygen species are involved in cell signaling and organ injury in sepsis. Efforts must be made to identify the precise contribution of these factors in septic process, in order to clarify the mechanisms associated with the disease. This will certainly lead to discovery of therapeutic strategies that can help us to mitigate vascular dysfunction of sepsis.

Antiatherogenic effects of S-nitroso-N-acetylcysteine in hypercholesterolemic LDL receptor knockout mice

BACKGROUND

The pathophysiology of the NO/NO synthase system and dysfunctional changes in the endothelium in the early phases of the atherogenic process are incompletely understood. In this study, we investigated the effects of the nitrosothiol NO donor S-nitroso-N-acetylcysteine (SNAC) in the early prevention of plaque development in the hypercholesterolemic LDLr-/- mice as well as the changes in endothelium-dependent relaxation and NO synthase expression.

METHODS AND RESULTS

LDLr-/- mice were fed a 1.25% cholesterol-enriched diet for 15 days. Plasma cholesterol/triglyceride levels increased and this increase was accompanied by the development of aortic root lesions. Aortic vasorelaxation to acetylcholine was increased, although endothelium-independent relaxation in response to sodium nitroprusside did not change, which suggest stimulated NO release enhanced. This dysfunction was associated with enhanced aortic superoxide production and with increased levels of constitutive NOS isoform expression, particularly neuronal NOS. SNAC (S-nitroso-N-acetylcysteine) administration (0.51 micromol/kg/day i.p. for 15 days) decreased the extent of the plaque by 55% in hypercholesterolemic mice, but had no effects on vasomotor changes. It did, however, lead to a decrease in constitutive NOS expression. The SNAC induced only minor changes in plasma lipid profile.

CONCLUSION

The present study has shown that, in early stages of plaque development in LDLr-/- mice, specific changes in NO/NO synthase system develop, that are characterized by increased endothelium-dependent vasorelaxation and increased constitutive NOS expression. Since the development of plaque and the indicator of endothelial cell dysfunction were prevented by SNAC, such treatment may constitute a novel strategy for the halting of progression of early plaque.

Estrogen enhances vasoconstrictive remodeling after injury in male rabbits

The complete spectrum of estrogen vascular effects remains unclear. In particular, estrogen effects in the vascular response to profound injury in males have not been explored in detail. Therefore, we submitted 44 male New Zealand rabbits weighing 3.4 +/- 0.6 kg to overdistention balloon injury of the right iliac artery. Rabbits were given 17beta-estradiol (5.45 micromol/day, sc) or vehicle for 7 days before and 14 days after injury, when the arteries were examined by post-mortem histomorphometry. Arteriographic caliber was assessed in vivo at baseline and before sacrifice. On day 14 after injury, in vivo arteriographic caliber (baseline = 2.44 +/- 0.43 mm) was decreased by 23.1 +/- 0.1% in controls and by 44.5 +/- 0.1% in estrogen-treated rabbits (P < 0.001). Neither the neointimal area nor the neointima/media area ratio changed after estrogen treatment. Collagen fraction was increased in the media and neointima of estrogen-treated rabbits vs control (1.38 +/- 1.30 vs 0.35 +/- 0.67, respectively, P = 0.01). Taken together, these findings suggest that estrogen increased negative vascular remodeling. Transcription of endothelial and inducible nitric oxide synthases (eNOS and iNOS) was analyzed by RT-PCR. eNOS mRNA expression was marginally increased after estrogen (P = 0.07) and injury. iNOS mRNA was increased 2- to 3-fold on day 14 after injury. With estrogen treatment, iNOS mRNA increased in uninjured arteries and exhibited a further 5.5-fold increase after injury. We concluded that estrogen increased lumen loss after balloon injury in male rabbits, likely by increased negative remodeling, which may be related to increased iNOS transcriptional rates.

The balloon catheter induces an increase in contralateral carotid artery reactivity to angiotensin II and phenylephrine

1. The effects of balloon injury on the reactivity of ipsilateral and contralateral carotid arteries were compared to those observed in arteries from intact animals (control arteries). 2. Carotid arteries were obtained from Wistar rats 2, 4, 7, 15, 30 or 45 days after injury and mounted in an isolated organ bath. Reactivity to angiotensin II (Ang II), phenylephrine (Phe) and bradykinin (BK) was studied. Curves were constructed in the absence or presence of endothelium or after incubation with 10 microm indomethacin, 500 microm valeryl salicylate or 0.1 microm celecoxib. 3. Phe, Ang II and BK maximum effects (Emax) were decreased in ipsilateral arteries when compared to control arteries. No differences were observed among pD2 or Hill coefficient. 4. Emax to Phe (4 and 7 days) and to Ang II (15 and 30 days) increased in the contralateral artery. In addition, Phe or Ang II reactivity was not significantly different in aorta rings from control or carotid-injured animals. 5. The increased responsiveness of contralateral artery was not due to changes in carotid blood flow or resting membrane potential. The endothelium-dependent inhibitory component is not present in the contraction of contralateral arteries and it is not related to superoxide anion production. 6. Indomethacin decreased contralateral artery responsiveness to Phe and Ang II. Valeryl salicylate reduced the Ang II response in contralateral and control arteries. Celecoxib decreased the Phe Emax of contralateral artery. 7. In conclusion, decreased endothelium-derived factors and increased prostanoids appear to be responsible for the increased reactivity of contralateral arteries after injury.

Nitric oxide regulates angiotensin-I converting enzyme under static conditions but not under shear stress

Mechanical forces including pressure and shear stress play an important role in vascular homeostasis via the control of the production and release of a variety of vasoactive factors. An increase in vascular shear stress is accompanied by nitric oxide (NO) release and NO synthase activation. Previously, we have demonstrated that shear stress induces angiotensin-I converting enzyme (ACE) down-regulation in vivo and in vitro. In the present study, we determined whether NO participates in the shear stress-induced ACE suppression response. Rabbit aortic endothelial cells were evaluated using the NO synthase inhibitor L-NAME, and two NO donors, diethylamine NONOate (DEA/NO) and sodium nitroprusside (SNP). Under static conditions, incubation of endothelial cells with 1 mM L-NAME for 18 h increased ACE activity by 27% (from 1.000 +/- 0.090 to 1.272 +/- 0.182) while DEA/NO and SNP (0.1, 0.5 and 1 mM) caused no change in ACE activity. Interestingly, ACE activity was down-regulated similarly in the presence or absence of L-NAME (delta(0 mM) = 0.26 0.055, delta(0.1 mM) = 0.21 +/- 0.22, delta(1 mM) = 0.36 +/- 0.13) upon 18 h shear stress activation (from static to 15 dyn/cm2 ). Taken together, these results indicate that NO can participate in the maintenance of basal ACE levels in the static condition but NO is not associated with the shear stress-induced inactivation of ACE.

Oxidative stress in the pathogenesis of nonalcoholic fatty liver disease, in rats fed with a choline-deficient diet

BACKGROUND/AIM

The pathogenesis of Nonalcoholic Fatty Liver Disease remains largely unknown, but oxidative stress seems to be involved. The aim of this study was to evaluate the role of oxidative stress in experimental hepatic steatosis induced by a choline-deficient diet.

METHODS

Fatty liver disease was induced in Wistar rats by a choline-deficient diet. The animals were randomized into three groups: I (G1) and II (G2), n=6 each--fed with a choline-deficient diet for four and twelve weeks respectively; Group III (control-G3; n=6)--fed with a standard diet for twelve weeks. Samples of plasma and liver were submitted to biochemical, histological and oxidative stress analysis. Variables measured included serum levels of aminotransferases (AST, ALT), cholesterol and triglycerides. Oxidative stress was measured by lucigenin-enhanced luminescence and the concentration of hydroperoxides (CE-OOH-cholesteryl ester) in the liver tissue.

RESULTS

We observed moderate macro- and microvesicular fatty change in periportal zones G1 and G2 as compared to controls (G3). In G2, fatty change was more severe. The inflammatory infiltrate was scanty and no fibrosis was seen in any group. There was a significant increase of AST and triglycerides in G1 and G2 as compared to control group G3. The lucigenin-amplified luminescence (cpm/mg/min x 10(3)) was significantly increased in G1 (1393-/+790) and G2 (7191-/+500) as compared to controls (513-/+170), p<0.05. The concentrations of CE-OOH were higher in G1 (5.7-/+0.9 nmol/mg protein) as compared to control (2.6-/+0.7 nmol/mg protein), p<0.05.

CONCLUSION

1) Oxidative stress was found to be increased in experimental liver steatosis; 2) The production of reactive oxygen species was accentuated when liver steatosis was more severe; 3) The alterations produced by oxidative stress could be an important step in the pathogenesis of nonalcoholic fatty liver disease.