Protein disulfide isomerase-mediated transcriptional upregulation of Nox1 contributes to vascular dysfunction in hypertension

Nox1 signaling is a causal key element in arterial hypertension. Recently, we identified protein disulfide isomerase A1 (PDI) as a novel regulatory protein that regulates Nox1 signaling in VSMCs. Spontaneously hypertensive rats (SHR) have increased levels of PDI in mesenteric resistance arteries compared with Wistar controls; however, its consequences remain unclear. Herein, we investigated the role of PDI in mediating Nox1 transcriptional upregulation and its effects on vascular dysfunction in hypertension. We demonstrate that PDI contributes to the development of hypertension via enhanced transcriptional upregulation of Nox1 in vascular smooth muscle cells (VSMCs). We show for the first time that PDI sulfenylation by hydrogen peroxide contributes to EGFR activation in hypertension via increased shedding of epidermal growth factor-like ligands. PDI also increases intracellular calcium levels, and contractile responses induced by ANG II. PDI silencing or pharmacological inhibition in VSMCs significantly decreases EGFR activation and Nox1 transcription. Overexpression of PDI in VSMCs enhances ANG II-induced EGFR activation and ATF1 translocation to the nucleus. Mechanistically, PDI increases ATF1-induced Nox1 transcription and enhances the contractile responses to ANG II. Herein we show that ATF1 binding to Nox1 transcription putative regulatory regions is augmented by PDI. Altogether, we provide evidence that HB-EGF in SHR resistance vessels promotes the nuclear translocation of ATF1, under the control of PDI, and thereby induces Nox1 gene expression and increases vascular reactivity. Thus, PDI acts as a thiol redox-dependent enhancer of vascular dysfunction in hypertension and could represent a novel therapeutic target for the treatment of this disease.

DNAJB12 and DNJB14 are non-redundant Hsp40 redox chaperones involved in endoplasmic reticulum protein reflux

BACKGROUND

The endoplasmic reticulum (ER) transmembrane chaperones DNAJB12(B12) and DNAJB14(B14) are cofactors that cooperate with cytosolic Heat Shock-70 protein (HSC70) facilitating folding/degradation of nascent membrane proteins and supporting the ER-membrane penetration of viral particles. Here, we assessed structural/functional features of B12/B14 with respect to their regulation by ER stress and their involvement in ER stress-mediated protein reflux.

METHODS

We investigated the effect of Unfolded Protein Response(UPR)-eliciting drugs on the expression/regulation of B12-B14 and their roles in ER-to-cytosol translocation of Protein Disulfide Isomerase-A1(PDI).

RESULTS

We show that B12 and B14 are similar but do not seem redundant. They share predicted structural features and show high homology of their cytosolic J-domains, while their ER-lumen DUF1977 domains are quite dissimilar. Interactome analysis suggested that B12/B14 associate with different biological processes. UPR activation did not significantly impact on B12 gene expression, while B14 transcripts were up-regulated. Meanwhile, B12 and B14 (33.4 kDa isoform) protein levels were degraded by the proteasome upon acute reductive challenge. Also, B12 degradation was impaired upon sulfenic-acid trapping by dimedone. We originally report that knockdown of B12/B14 and their cytosolic partner SGTA in ER-stressed cells significantly impaired the amount of the ER redox-chaperone PDI in a cytosolic-enriched fraction. Additionally, B12 but not B14 overexpression increased PDI relocalization in non-stressed cells.

CONCLUSIONS AND GENERAL SIGNIFICANCE

Our findings reveal that B12/B14 regulation involves thiol redox processes that may impact on their stability and possibly on physiological effects. Furthermore, we provide novel evidence that these proteins are involved in UPR-induced ER protein reflux.

Evidence for a protective role of Protein Disulfide Isomerase-A1 against aortic dissection

BACKGROUND AND AIMS

Redox signaling is involved in the pathophysiology of aortic aneurysm/dissection. Protein Disulfide Isomerases and its prototype PDIA1 are thiol redox chaperones mainly from endoplasmic reticulum (ER), while PDIA1 cell surface pool redox-regulates thrombosis, cytoskeleton remodeling and integrin activation, which are mechanisms involved in aortic disease. Here we investigate the roles of PDIA1 in aortic dissection.

METHODS

Initially, we assessed the outcome of aortic aneurysm/dissection in transgenic PDIA1-overexpressing FVB mice using a model of 28-day exposure to lysyl oxidase inhibitor BAPN plus angiotensin-II infusion. In a second protocol, we assessed the effects of PDIA1 inhibitor isoquercetin (IQ) against aortic dissection in C57BL/6 mice exposed to BAPN for 28 days.

RESULTS

Transgenic PDIA1 overexpression associated with ca. 50% (p = 0.022) decrease (vs.wild-type) in mortality due to abdominal aortic rupture and protected against elastic fiber breaks in thoracic aorta. Conversely, exposure of mice to IQ increased thoracic aorta dissection-related mortality rates, from ca. 18%-50% within 28-days (p = 0.019); elastic fiber disruption and collagen deposition were also enhanced. The structurally-related compound diosmetin, which does not inhibit PDI, had negligible effects. In parallel, stretch-tension curves indicated that IQ amplified a ductile-type of biomechanical failure vs. control or BAPN-exposed mice aortas. IQ-induced effects seemed unassociated with nonspecific antioxidant effects or ER stress. In both models, echocardiographic analysis of surviving mice suggested that aortic rupture was dissociated from progressive dilatation.

CONCLUSIONS

Our data indicate a protective role of PDIA1 against aortic dissection/rupture and potentially uncovers a novel integrative mechanism coupling redox and biomechanical homeostasis in vascular remodeling.

Hippocampal Endoplasmic Reticulum Stress Hastens Motor and Cognitive Decline in Adult Male Rats Sustainedly Exposed to High-Sucrose Diet

Metabolic dysfunctions, such as hyperglycemia and insulin resistance, have been associated to cognitive impairment and dementia regardless of advanced age, although the underlying mechanisms are still elusive. Thus, this study investigates the deleterious effects of metabolic syndrome (MetS) induced by long-term exposure to a high-sucrose diet on motor and cognitive functions of male adult rats and its relationship with hippocampal endoplasmic reticulum (ER) stress. Weaned Wistar male rats were fed a high-sucrose diet until adulthood (HSD; 6 months old) and compared to both age-matched (CTR; 6 months old) and middle-aged chow-fed rats (OLD; 20 months old). MetS development, serum redox profile, behavioral, motor, and cognitive functions, and hippocampal gene/protein expressions for ER stress pro-adaptive and pro-apoptotic pathways, as well as senescence markers were assessed. Prolonged exposure to HSD induced MetS hallmarked by body weight gain associated to central obesity, hypertriglyceridemia, insulin resistance, and oxidative stress. Furthermore, HSD rats showed motor and cognitive decline similar to that in OLD animals. Noteworthy, HSD rats presented marked hippocampal ER stress characterized by failure of pro-adaptive signaling and increased expression of Chop, p21, and Parp-1 cleavage, markers of cell death and aging. This panorama resembles that found in OLD rats. In toto, our data showed that early and sustained exposure to a high-sucrose diet induced MetS, which subsequently led to hippocampus homeostasis disruption and premature impairment of motor and cognitive functions in adult rats.

Analysing the impact of modifiable risk factors on cardiovascular disease mortality in Brazil

Objectives

We have examined the impact of changes in modifiable risk factors on CVD mortality in 26 Brazilian states from 2005 to 2017.

Methods

Data were acquired from the Global Burden of Diseases study (GBD) and official sources of the Brazilian government, totalling 312 state-year observations. Population attributable fractions (PAFs) were calculated to determine the number of deaths attributed to changes in each risk factor. Fixed-effects multivariable linear regression models were performed, adjusting for income, income inequality, poverty and access to healthcare.

Results

Between 2005 and 2017, CVD deaths reduced by 21.42%, accompanied by a decrease in smoking (-33%) and increases in hyperglycaemia (+9.5%), obesity (+31%) and dyslipidaemia (+5.2%). Reduction in smoking prevented or postponed almost 20,000 CVD deaths in this period, while increased hyperglycaemia exposure resulted in more than 6,000 CVD deaths. The association between hyperglycaemia and CVD mortality was 5 to 10 times higher than those found for other risk factors, especially in women (11; 95%CI 7 to 14, deaths per 1-point increase in hyperglycaemia exposure). Importantly, the association between hyperglycaemia and CVD mortality was independent of socioeconomic status and access to healthcare, while associations for other risk factors after the same adjustments.

Conclusion

Reduction in smoking was the risk factor that led to the highest number of CVD deaths prevented or postponed, while hyperglycaemia showed the most deleterious association with CVD mortality. Health policies should aim to directly reduce the prevalence of hyperglycaemia to mitigate the population burden of CVD in Brazil in the future.

Treatment With Methotrexate Associated With Lipid Core Nanoparticles Prevents Aortic Dilation in a Murine Model of Marfan Syndrome

In Marfan syndrome (MFS), dilation, dissection, and rupture of the aorta occur. Inflammation can be involved in the pathogenicity of aortic defects and can thus be a therapeutic target for MFS. Previously, we showed that the formulation of methotrexate (MTX) associated with lipid nanoparticles (LDE) has potent anti-inflammatory effects without toxicity. To investigate whether LDEMTX treatment can prevent the development of aortic lesions in the MFS murine model. MgΔloxPneo MFS (n = 40) and wild-type (WT, n = 60) mice were allocated to 6 groups weekly injected with IP solutions of: (1) only LDE; (2) commercial MTX; (3) LDEMTX (dose = 1mg/kg) between 3rd and 6th months of life. After 12 weeks of treatments, animals were examined by echocardiography and euthanatized for morphometric and molecular studies. MFS mice treated with LDEMTX showed narrower lumens in the aortic arch, as well as in the ascending and descending aorta. LDEMTX reduced fibrosis and the number of dissections in MFS but not the number of elastic fiber disruptions. In MFS mice, LDEMTX treatment lowered protein expression of pro-inflammatory factors macrophages (CD68), T-lymphocytes (CD3), tumor necrosis factor-α (TNF-α), apoptotic factor cleaved-caspase 3, and type 1 collagen and lowered the protein expression of the transforming growth factor-β (TGF-β), extracellular signal-regulated kinases ½ (ERK1/2), and SMAD3. Protein expression of CD68 and CD3 had a positive correlation with an area of aortic lumen (r² = 0.36; p < 0.001), suggesting the importance of inflammation in the causative mechanisms of aortic dilation. Enhanced adenosine availability by LDEMTX was suggested by higher aortic expression of an anti-adenosine A2a receptor (A2a) and lower adenosine deaminase expression. Commercial MTX had negligible effects. LDEMTX prevented the development of MFS-associated aortic defects and can thus be a candidate for testing in clinical studies.

Co-Exposure of Cardiomyocytes to IFN-γ and TNF-α Induces Mitochondrial Dysfunction and Nitro-Oxidative Stress: Implications for the Pathogenesis of Chronic Chagas Disease Cardiomyopathy

Infection by the protozoan Trypanosoma cruzi causes Chagas disease cardiomyopathy (CCC) and can lead to arrhythmia, heart failure and death. Chagas disease affects 8 million people worldwide, and chronic production of the cytokines IFN-γ and TNF-α by T cells together with mitochondrial dysfunction are important players for the poor prognosis of the disease. Mitochondria occupy 40% of the cardiomyocytes volume and produce 95% of cellular ATP that sustain the life-long cycles of heart contraction. As IFN-γ and TNF-α have been described to affect mitochondrial function, we hypothesized that IFN-γ and TNF-α are involved in the myocardial mitochondrial dysfunction observed in CCC patients. In this study, we quantified markers of mitochondrial dysfunction and nitro-oxidative stress in CCC heart tissue and in IFN-γ/TNF-α-stimulated AC-16 human cardiomyocytes. We found that CCC myocardium displayed increased levels of nitro-oxidative stress and reduced mitochondrial DNA as compared with myocardial tissue from patients with dilated cardiomyopathy (DCM). IFN-γ/TNF-α treatment of AC-16 cardiomyocytes induced increased nitro-oxidative stress and decreased the mitochondrial membrane potential (ΔΨm). We found that the STAT1/NF-κB/NOS2 axis is involved in the IFN-γ/TNF-α-induced decrease of ΔΨm in AC-16 cardiomyocytes. Furthermore, treatment with mitochondria-sparing agonists of AMPK, NRF2 and SIRT1 rescues ΔΨm in IFN-γ/TNF-α-stimulated cells. Proteomic and gene expression analyses revealed that IFN-γ/TNF-α-treated cells corroborate mitochondrial dysfunction, transmembrane potential of mitochondria, altered fatty acid metabolism and cardiac necrosis/cell death. Functional assays conducted on Seahorse respirometer showed that cytokine-stimulated cells display decreased glycolytic and mitochondrial ATP production, dependency of fatty acid oxidation as well as increased proton leak and non-mitochondrial oxygen consumption. Together, our results suggest that IFN-γ and TNF-α cause direct damage to cardiomyocytes’ mitochondria by promoting oxidative and nitrosative stress and impairing energy production pathways. We hypothesize that treatment with agonists of AMPK, NRF2 and SIRT1 might be an approach to ameliorate the progression of Chagas disease cardiomyopathy.

Endothelial Nox2 Limits Systemic Inflammation and Hypotension in Endotoxemia by Controlling Expression of Toll-Like Receptor 4

ABSTRACT

Leukocyte Nox2 is recognized to have a fundamental microbicidal function in sepsis but the specific role of Nox2 in endothelial cells (EC) remains poorly elucidated. Here, we tested the hypothesis that endothelial Nox2 participates in the pathogenesis of systemic inflammation and hypotension induced by LPS. LPS was injected intravenously in mice with Tie2-targeted deficiency or transgenic overexpression of Nox2. Mice with Tie2-targeted Nox2 deficiency had increased circulating levels of TNF-α, enhanced numbers of neutrophils trapped in lungs, and aggravated hypotension after LPS injection, as compared to control LPS-injected animals. In contrast, Tie2-driven Nox2 overexpression attenuated inflammation and prevented the hypotension induced by LPS. Because Tie2-Cre targets both EC and myeloid cells we generated bone marrow chimeric mice with Nox2 deletion restricted to leukocytes or ECs. Mice deficient in Nox2 either in leukocytes or ECs had reduced LPS-induced neutrophil trapping in the lungs and lower plasma TNF-α levels as compared to control LPS-injected mice. However, the pronounced hypotensive response to LPS was present only in mice with EC-specific Nox2 deletion. Experiments in vitro with human vein or aortic endothelial cells (HUVEC and HAEC, respectively) treated with LPS revealed that EC Nox2 controls NF-κB activation and the transcription of toll-like receptor 4 (TLR4), which is the recognition receptor for LPS. In conclusion, these results suggest that endothelial Nox2 limits NF-κB activation and TLR4 expression, which in turn attenuates the severity of hypotension and systemic inflammation induced by LPS.

Impaired vascular smooth muscle cell force-generating capacity and phenotypic deregulation in Marfan Syndrome mice

Mechanisms whereby fibrillin-1 mutations determine thoracic aorta aneurysms/dissections (TAAD) in Marfan Syndrome (MFS) are unclear. Most aortic aneurysms evolve from mechanosignaling deregulation, converging to impaired vascular smooth muscle cell (VSMC) force-generating capacity accompanied by synthetic phenotype switch. However, little is known on VSMC mechanoresponses in MFS pathophysiology. Here, we investigated traction force-generating capacity in aortic VSMC cultured from 3-month old mg∆^lpn MFS mice, together with morpho-functional and proteomic data. Cultured MFS-VSMC depicted marked phenotype changes vs. wild-type (WT) VSMC, with overexpressed cell proliferation markers but either lower (calponin-1) or higher (SM alpha-actin and SM22) differentiation marker expression. In parallel, the increased cell area and its complex non-fusiform shape suggested possible transition towards a mesenchymal-like phenotype, confirmed through several markers (e.g. N-cadherin, Slug). MFS-VSMC proteomic profile diverged from that of WT-VSMC particularly regarding lower expression of actin cytoskeleton-regulatory proteins. Accordingly, MFS-VSMC displayed lower traction force-generating capacity and impaired contractile moment at physiological substrate stiffness, and markedly attenuated traction force responses to enhanced substrate rigidity. Such impaired mechanoresponses correlated with decreased number, altered morphology and delocalization of focal adhesions, as well as disorganized actin stress fiber network vs. WT-VSMC. In VSMC cultured from 6-month-old mice, phenotype changes were attenuated and both WT-VSMC and MFS-VSMC generated less traction force, presumably involving VSMC aging, but without evident senescence. In summary, MFS-VSMC display impaired force-generating capacity accompanying a mesenchymal-like phenotype switch connected to impaired cytoskeleton/focal adhesion organization. Thus, MFS-associated TAAD involves mechanoresponse impairment common to other TAAD types, but through distinct mechanisms.

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

Chemotherapy acutely impairs neurovascular and hemodynamic responses in women with breast cancer

The purpose of the present study was to test the hypothesis that doxorubicin (DX) and cyclophosphamide (CY) adjuvant chemotherapy (CHT) acutely impairs neurovascular and hemodynamic responses in women with breast cancer. Sixteen women (age: 47.0 ± 2.0 yr; body mass index: 24.2 ± 1.5 kg/m) with stage II-III breast cancer and indication for adjuvant CHT underwent two experimental sessions, saline (SL) and CHT. In the CHT session, DX (60 mg/m2) and CY (600 mg/m2) were administered over 45 min. In the SL session, a matching SL volume was infused in 45 min. Muscle sympathetic nerve activity (MSNA) from peroneal nerve (microneurography), calf blood flow (CBF; plethysmography) and calf vascular conductance (CVC), heart rate (HR; electrocardiography), and beat-to-beat blood pressure (BP; finger plethysmography) were measured at rest before, during, and after each session. Venous blood samples (5 ml) were collected before and after both sessions for assessment of circulating endothelial microparticles (EMPs; flow cytometry), a surrogate marker for endothelial damage. MSNA and BP responses were increased ( P < 0.001), whereas CBF and CVC responses were decreased ( P < 0.001), during and after CHT session when compared with SL session. Interestingly, the vascular alterations were also observed at the molecular level through an increased EMP response to CHT ( P = 0.03, CHT vs. SL session). No difference in HR response was observed ( P > 0.05). Adjuvant CHT with DX and CY in patients treated for breast cancer increases sympathetic nerve activity and circulating EMP levels and, in addition, reduces muscle vascular conductance and elevates systemic BP. These responses may be early signs of CHT-induced cardiovascular alterations and may represent potential targets for preventive interventions.

NEW & NOTEWORTHY It is known that chemotherapy regimens increase the risk of cardiovascular events in patients treated for cancer. Here, we identified that a single cycle of adjuvant chemotherapy with doxorubicin and cyclophosphamide in women treated for breast cancer dramatically increases sympathetic nerve activity and circulating endothelial microparticle levels, reduces the muscle vascular conductance, and elevates systemic blood pressure.

Protein disulfide isomerase plasma levels in healthy humans reveal proteomic signatures involved in contrasting endothelial phenotypes

Redox-related plasma proteins are candidate reporters of protein signatures associated with endothelial structure/function. Thiol-proteins from protein disulfide isomerase (PDI) family are unexplored in this context. Here, we investigate the occurrence and physiological significance of a circulating pool of PDI in healthy humans. We validated an assay for detecting PDI in plasma of healthy individuals. Our results indicate high inter-individual (median = 330 pg/mL) but low intra-individual variability over time and repeated measurements. Remarkably, plasma PDI levels could discriminate between distinct plasma proteome signatures, with PDI-rich (>median) plasma differentially expressing proteins related to cell differentiation, protein processing, housekeeping functions and others, while PDI-poor plasma differentially displayed proteins associated with coagulation, inflammatory responses and immunoactivation. Platelet function was similar among individuals with PDI-rich vs. PDI-poor plasma. Remarkably, such protein signatures closely correlated with endothelial function and phenotype, since cultured endothelial cells incubated with PDI-poor or PDI-rich plasma recapitulated gene expression and secretome patterns in line with their corresponding plasma signatures. Furthermore, such signatures translated into functional responses, with PDI-poor plasma promoting impairment of endothelial adhesion to fibronectin and a disturbed pattern of wound-associated migration and recovery area. Patients with cardiovascular events had lower PDI levels vs. healthy individuals. This is the first study describing PDI levels as reporters of specific plasma proteome signatures directly promoting contrasting endothelial phenotypes and functional responses.

Long-term exposure to high-sucrose diet down-regulates hepatic endoplasmic reticulum-stress adaptive pathways and potentiates de novo lipogenesis in weaned male mice

Childhood consumption of added sugars, such as sucrose, has been associated to increased risk of metabolic syndrome (MetS) and nonalcoholic fatty liver disease (NAFLD). Although the mechanisms underlying NAFLD onset are incompletely defined, recent evidence has proposed a role for the endoplasmic reticulum (ER) stress. Thus, the present study sought to investigate the metabolic outcomes of high-sucrose intake on weaned Swiss mice fed a 25% sucrose diet for 30, 60 and 90 days in comparison to regular chow-fed controls. High-sucrose feeding promoted progressive metabolic and oxidative disturbances, starting from fasting and fed hyperglycemia, hyperinsulinemia, glucose intolerance and increased adiposity at 30-days; passing by insulin resistance, hypertriglyceridemia and NAFLD onset at 60 days; until late hepatic oxidative damage at 90 days. In parallel, assessment of transcriptional and/or translational levels of de novo lipogenesis (DNL) and ER stress markers showed up-regulation of both fatty acid synthesis (ChREBP and SCD1) and oxidation (PPARα and CPT-1α), as well as overexpression of unfolded protein response sensors (IRE1α, PERK and ATF6), chaperones (GRP78 and PDIA1) and antioxidant defense (NRF2) genes at 30 days. At 60 days, fatty acid oxidation genes were down-regulated, and ER stress switched over toward a proapoptotic pattern via up-regulation of BAK protein and CHOP gene levels. Finally, down-regulation of both NRF2 and CPT-1α protein levels led to late up-regulation of SREBP-1c and exponential raise of fatty acids synthesis. In conclusion, our study originally demonstrates a temporal relationship between DNL and ER stress pathways toward MetS and NAFLD development on weaned rats fed a high-sucrose diet.

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.

Protein disulfide isomerases: Redox connections in and out of the endoplasmic reticulum

Protein disulfide isomerases are thiol oxidoreductase chaperones from thioredoxin superfamily. As redox folding catalysts from the endoplasmic reticulum (ER), their roles in ER-related redox homeostasis and signaling are well-studied. PDIA1 exerts thiol oxidation/reduction and isomerization, plus chaperone effects. Also, substantial evidence indicates that PDIs regulate thiol-disulfide switches in other cell locations such as cell surface and possibly cytosol. Subcellular PDI translocation routes remain unclear and seem Golgi-independent. The list of signaling and structural proteins reportedly regulated by PDIs keeps growing, via thiol switches involving oxidation, reduction and isomerization, S-(de)nytrosylation, (de)glutathyonylation and protein oligomerization. PDIA1 is required for agonist-triggered Nox NADPH oxidase activation and cell migration in vascular cells and macrophages, while PDIA1-dependent cytoskeletal regulation appears a converging pathway. Extracellularly, PDIs crucially regulate thiol redox signaling of thrombosis/platelet activation, e.g., integrins, and PDIA1 supports expansive caliber remodeling during injury repair via matrix/cytoskeletal organization. Some proteins display regulatory PDI-like motifs. PDI effects are orchestrated by expression levels or post-translational modifications. PDI is redox-sensitive, although probably not a mass-effect redox sensor due to kinetic constraints. Rather, the "all-in-one" organization of its peculiar redox/chaperone properties likely provide PDIs with precision and versatility in redox signaling, making them promising therapeutic targets.

Early and sustained exposure to high-sucrose diet triggers hippocampal ER stress in young rats

Early-life environmental insults have been shown to promote long-term development of chronic non-communicable diseases, including metabolic disturbances and mental illnesses. As such, premature consumption of high-sugar foods has been associated to early onset of detrimental outcomes, whereas underlying mechanisms are still poorly understood. In the present study, we sought to investigate whether early and sustained exposure to high-sucrose diet promotes metabolic disturbances that ultimately might anticipate neurological injuries. At postnatal day 21, weaned male rats started to be fed a standard chow (10 % sucrose, CTR) or a high-sucrose diet (25 % sucrose, HSD) for 9 weeks prior to euthanasia at postnatal day 90. HSD did not alter weight gain and feed efficiency between groups, but increased visceral, non-visceral and brown adipose tissue accumulation. HSD rats demonstrated elevated blood glucose levels in both fasting and fed states, which were associated to impaired glucose tolerance. Peripheral insulin sensitivity did not change, whereas hepatic insulin resistance was supported by increased serum triglyceride levels, as well as higher TyG index values. Assessment of hippocampal gene expression showed endoplasmic reticulum (ER) stress pathways were activated in HSD rats, as compared to CTR. HSD rats had overexpression of unfolded protein response sensors, PERK and ATF6; ER chaperone, PDIA2 and apoptosis-related genes, CHOP and Caspase 3; but decreased expression of chaperone GRP78. Finally, HSD rats demonstrated impaired neuromuscular function and anxious behavior, but preserved cognitive parameters. In conclusion, our data indicate that early exposure to HSD promote metabolic disturbances, which disrupt hippocampus homeostasis and might precociously affect its neurobehavioral functions.

Preclinical study of a biodegradable polymer-based stent with abluminal sirolimus release

Background

Bioabsorbable polymer stents with drug elution only on the abluminal surface may be safer than durable polymer drug-eluting stents.

Objective

To report the experimental findings with the Inspiron^TM stent - a bioabsorbable polymer-coated stent with sirolimus release from the abluminal surface only, recently approved for clinical use.

Methods

45 stents were implanted in the coronary arteries of 15 pigs. On day 28 after implantation, angiographic, intracoronary ultrasonographic and histomorphological data were collected. Five groups were analyzed: Group I (nine bare-metal stents); Group II (nine coated with bioabsorbable polymer on the luminal and abluminal surfaces); Group III (eight stents coated with bioabsorbable polymer on the abluminal surface); Group IV (nine stents with bioabsorbable polymer and sirolimus on the luminal and abluminal surfaces); and Group V (ten stents with bioabsorbable polymer and sirolimus only on the abluminal surface).

Results

The following results were observed for Groups I, II, III, IV and V, respectively: percentage stenosis of 29 ± 20; 36 ± 14; 33 ± 19; 22 ± 13 and 26 ± 15 (p = 0.443); late lumen loss (in mm) of 1.02 ± 0.60; 1.24 ± 0.48; 1.11 ± 0.54; 0.72 ± 0.44 and 0.78 ± 0.39 (p = 0.253); neointimal area (in mm²) of 2.60 ± 1.99; 2.74 ± 1.51; 2.74 ± 1.30; 1.30 ± 1.14 and 0.97 ± 0.84 (p = 0.001; Groups IV and V versus Groups I, II and III); and percentage neointimal area of 35 ± 25; 38 ± 18; 39 ± 19; 19 ± 18 and 15 ± 12 (p = 0.001; Groups IV and V versus Groups I, II and III). Injury and inflammation scores were low and with no differences between the groups.

Conclusion

The Inspiron^TM stent proved to be safe and was able to significantly inhibit the neointimal hyperplasia observed on day 28 after implantation in porcine coronary arteries.

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.

Mechanisms underlying hypertriglyceridemia in rats with monosodium L-glutamate-induced obesity: evidence of XBP-1/PDI/MTP axis activation

Non-alcoholic fatty liver disease (NAFLD) is intimately associated with insulin resistance and hypertriglyceridemia, whereas many of the mechanisms underlying this association are still poorly understood. In the present study, we investigated the relationship between microsomal triglyceride transfer protein (MTP) and markers of endoplasmic reticulum (ER) stress in the liver of rats subjected to neonatal monosodium L-glutamate (MSG)-induced obesity. At age 120 days old, the MSG-obese animals exhibited hyperglycemia, hypertriglyceridemia, insulin resistance, and liver steatosis, while the control (CTR) group did not. Analysis using fast protein liquid chromatography of the serum lipoproteins revealed that the triacylglycerol content of the very low-density lipoprotein (VLDL) particles was twice as high in the MSG animals compared with the CTR animals. The expression of ER stress markers, GRP76 and GRP94, was increased in the MSG rats, promoting a higher expression of X-box binding protein 1 (XBP-1), protein disulfide isomerase (PDI), and MTP. As the XBP-1/PDI/MTP axis has been suggested to represent a significant lipogenic mechanism in the liver response to ER stress, our data indicate that hypertriglyceridemia and liver steatosis occurring in the MSG rats are associated with increased MTP expression.

Assessment of stent strut endothelialization in iliac arteries of rabbits

BACKGROUND

Fast post-implantation stent endothelialization is desirable for theoretically reducing the possibility of stent thrombosis.

OBJECTIVE

To evaluate the extent of sirolimus-eluting stent strut endothelialization (delivered from the luminal and abluminal aspects or abluminal aspect only) in the iliac arteries of rabbits.

METHODS

The iliac arteries of 10 rabbits were implanted with four sirolimus-eluting stents in the luminal and abluminal aspects, three sirolimus-eluting stents in the abluminal aspect, six polymer-coated stents, and four uncoated stents. After four weeks, the rabbits were euthanized and scanning electron microscopy was performed to quantify the area of exposed stent strut as well as the percentage of endothelialization.

RESULTS

The area (mean ± SD) (mm(2)) of exposed uncoated stent struts, polymer-coated stents, sirulimus-eluting stent in the abluminal and luminal aspects and sirolimus-eluting stent in the abluminal aspect was 0.12 ± 0.08, 0.09 ± 0.12, 0.60 ± 0.67 and 0.05 ± 0.04, respectively (p = 0.120). The percentage of endothelialization (mean ± SD) (%) of uncoated stents, polymer-coated stents, sirolimus-eluting stents in the luminal and abluminal aspects and sirolimus-eluting stents in the abluminal aspect was 99 ± 01, 99 ± 0. 97 ± 03 and 99 ± 0, respectively (p = 0.133).

CONCLUSION

After four weeks of implantation in the iliac arteries of rabbits, both the sirolimus-eluting stents in the luminal plus abluminal aspects and those in the abluminal aspect only showed stent strut endothelialization rates similar to those of the other types of non-drug eluting stents.

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.

Platelet-derived exosomes from septic shock patients induce myocardial dysfunction

Introduction

Mechanisms underlying inotropic failure in septic shock are incompletely understood. We previously identified the presence of exosomes in the plasma of septic shock patients. These exosomes are released mainly by platelets, produce superoxide, and induce apoptosis in vascular cells by a redox-dependent pathway. We hypothesized that circulating platelet-derived exosomes could contribute to inotropic dysfunction of sepsis.

Methods

We collected blood samples from 55 patients with septic shock and 12 healthy volunteers for exosome separation. Exosomes from septic patients and healthy individuals were investigated concerning their myocardial depressant effect in isolated heart and papillary muscle preparations.

Results

Exosomes from the plasma of septic patients significantly decreased positive and negative derivatives of left ventricular pressure in isolated rabbit hearts or developed tension and its first positive derivative in papillary muscles. Exosomes from healthy individuals decreased these variables non-significantly. In hearts from rabbits previously exposed to endotoxin, septic exosomes decreased positive and negative derivatives of ventricular pressure. This negative inotropic effect was fully reversible upon withdrawal of exosomes. Nitric oxide (NO) production from exosomes derived from septic shock patients was demonstrated by fluorescence. Also, there was an increase in myocardial nitrate content after exposure to septic exosomes.

Conclusion

Circulating platelet-derived exosomes from septic patients induced myocardial dysfunction in isolated heart and papillary muscle preparations, a phenomenon enhanced by previous in vivo exposure to lipopolysaccharide. The generation of NO by septic exosomes and the increased myocardial nitrate content after incubation with exosomes from septic patients suggest an NO-dependent mechanism that may contribute to myocardial dysfunction of sepsis.

Isoflavone and the heme oxygenase system in ischemic acute kidney injury in rats

Ischemic acute kidney injury (AKI) is mediated by reactive oxygen species and inflammatory infiltration, among others. The present study was performed to evaluate the interference of isoflavone in ischemic AKI in rats and to determine whether it was mediated by the heme oxygenase (HO) system. The treatment with dry extract of isoflavone, 8 mg/kg/day, resulted in improved renal function reducing oxidative damage. The use of HO inhibitor zinc protoporphyrin (ZnPP), 50 micromol/kg, exacerbated the rates of oxidative damage, urinary peroxides, malondialdehyde (MDA), thiols and catalyse activity, whereas an HO inducer, Hemin, 1 mg/100 g body weight, demonstrated a protective effect on renal function, with a reduction in the rates of oxidative damage. Isoflavone showed a promising role in the protection against oxidative renal dysfunction and its role is probably mediated by heme-oxygenase.

Hepatic gene expression profile associated with non-alcoholic steatohepatitis protection by S-nitroso-N-acetylcysteine in ob/ob mice

BACKGROUND/AIMS

To understand the molecular mechanisms underlying non-alcoholic steatohepatitis (NASH) prevention by S-nitroso-N-acetylcysteine (SNAC), an NO donor that inhibits lipid peroxidation, we examined hepatic differentially expressed genes between ob/ob mice receiving or not SNAC treatment concomitantly with a methionine-choline deficient (MCD) diet.

METHODS

Ob/ob mice were assigned to receive oral SNAC fed solution (MCD+SNAC group) or vehicle (MCD group) by gavage. After four weeks, histopathological analysis and microarray hybridizations were conducted in liver tissues from groups. GeneSifter system was used to identify differentially expressed genes and pathways according to Gene Ontology.

RESULTS

NASH was absent in the MCD+SNAC group and no significant changes in food intake or body weight were observed in comparison to MCD group. After SNAC treatment, several genes belonging to oxidative phosphorylation, fatty acid biosynthesis, fatty acid metabolism and glutathione metabolism pathways were down-regulated in comparison to the MCD group.

CONCLUSIONS

SNAC treatment promotes down regulation of several genes from fatty acid (FA) metabolism related pathways, possibly through abrogation of the cytotoxic effects of reactive oxygen species and lipid peroxides with consequent prevention of mitochondrial overload. Further studies are required to investigate the clinical implications of these findings, in attempt to develop novel therapeutic strategies for NAFLD treatment.

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.

L-Arginine effects on blood pressure and renal function of intrauterine restricted rats

We have previously demonstrated that 3-month-old rats submitted to 50% intrauterine food restriction showed a decreased number of nephrons with increased glomerular diameter, a fact that suggests compensatory hypertrophy. In the present study, we extended the investigation and performed serial blood pressure measurements and renal function evaluation in 8- and 12-week-old rats submitted to 50% intrauterine food restriction (groups R8 and R12) and in age-matched control rats (groups C8 and C12). After weaning, six to eight animals from each group received oral supplements of 2% L-arginine ( L-arg) solution for 4 or 8 weeks (groups CA8, CA12, RA8, RA12). Our findings showed that mean blood pressure (MBP), which was significantly increased from 8 weeks on in R rats, markedly decreased after L-arg supplementation. In control animals, no alterations in MBP were observed with L-arg. Proteinuria was within normal limits in all groups studied but L-arg caused a significant decrease in this parameter in both the RA8 and RA12 groups. Glomerular filtration rate (GFR, ml/min per kg) was significantly decreased in the C8 control group (3.75+/-0.12) and in both restricted groups R8 and R12, (2.47+/-0.13 and 3.76+/-0.16, respectively) compared with the C12 group (6.09+/-0.31; P<0.05 for all comparisons). L-Arg caused an increase in GFR only in the younger groups, C8 and R8. In a separate set of experiments, acetylcholine (ACh)-induced relaxation was examined in mesenteric arteries. The R12 group showed a significant impairment of the response to ACh, which returned to normal values after L-arg supplementation. Urinary excretion of NO(x) (NO3- + NO2-) was significantly decreased in 8- and 12-week-old food-restricted rats relative to control rats. Our data indicate that, besides the known decrease in absolute nephron number, disturbances in the production/sensitivity to the L-arg-nitric oxide system may contribute to the early appearance of hypertension in the offspring of mothers submitted to significant food restriction.

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.