Platelet-endothelial cell adhesion molecule-1 regulates endothelial NO synthase activity and localization through signal transducers and activators of transcription 3-dependent NOSTRIN expression

Endothelial cell dysfunction in cardiac disease: driver or consequence?

The vascular endothelium is a multifunctional cellular system which directly influences blood components and cells within the vessel wall in a given tissue. Importantly, this cellular interface undergoes critical phenotypic changes in response to various biochemical and hemodynamic stimuli, driving several developmental and pathophysiological processes. Multiple studies have indicated a central role of the endothelium in the initiation, progression, and clinical outcomes of cardiac disease. In this review we synthesize the current understanding of endothelial function and dysfunction as mediators of the cardiomyocyte phenotype in the setting of distinct cardiac pathologies; outline existing in vivo and in vitro models where key features of endothelial cell dysfunction can be recapitulated; and discuss future directions for development of endothelium-targeted therapeutics for cardiac diseases with limited existing treatment options.

Improving Diastolic and Microvascular Function in Heart Transplantation with Donation after Circulatory Death

The impact of the machine perfusion of donation after circulatory death (DCD) hearts with the novel Custodiol-N solution on diastolic and coronary microvascular dysfunction is unknown. Porcine DCD-hearts were maintained four hours by perfusion with normothermic blood (DCD-B), hypothermic Custodiol (DCD-C), or Custodiol-N (DCD-CN), followed by one hour of reperfusion with fresh blood, including microvascular and contractile evaluation. In another group (DCD group), one hour of reperfusion, including microvascular and contractile evaluation, was performed without a previous maintenance period (all groups N = 5). We measured diastolic function with a balloon catheter and microvascular perfusion by Laser-Doppler-Technology, resulting in Laser-Doppler-Perfusion (LDP). We performed immunohistochemical staining and gene expression analysis. The developed pressure was improved in DCD-C and DCD-CN. The diastolic pressure decrement (DCD-C: -1093 ± 97 mmHg/s; DCD-CN: -1703 ± 329 mmHg/s; DCD-B: -690 ± 97 mmHg/s; p < 0.05) and relative LDP (DCD-CN: 1.42 ± 0.12; DCD-C: 1.11 ± 0.13; DCD-B: 1.22 ± 0.27) were improved only in DCD-CN. In DCD-CN, the expression of eNOS increased, and ICAM and VCAM decreased. Only in DCD-B compared to DCD, the pathways involved in complement and coagulation cascades, focal adhesion, fluid shear stress, and the IL-6 and IL-17 pathways were upregulated. In conclusion, machine perfusion with Custodiol-N improves diastolic and microvascular function and preserves the microvascular endothelium of porcine DCD-hearts.

The effects of melatonin against atherosclerosis-induced endothelial dysfunction and inflammation in hypercholesterolemic rats

The aim of this study was to investigate the effects of melatonin on the serum asymmetric dimethylarginine (ADMA) levels and the expressions of vaspin, visfatin, dimethylarginine dimethylaminohydrolase (DDAH), and signal transducer and activator of transcription-3 (STAT-3) for evaluation of endothelial function and inflammation in the hypercholesterolemic rats. Rats were divided into 5 groups: (1) control, (2) hypercholesterolaemia, (3) melatonin administrated concurrently with cholesterol diet, (4) melatonin administrated only last 2 weeks and fed with cholesterol diet, (5) atorvastatin administered only last 2 weeks fed with cholesterol diet. Although an increase was observed in the expressions of visfatin and STAT-3 and the serum ADMA levels, the vaspin and DDAH protein expressions were found to decrease with hypercholesterolemic diets. Melatonin was determined to restore all the parameters to the normal levels. In conclusion, melatonin may have protective and therapeutic effects on hypercholesterolaemia by regulating vaspin, STAT-3, DDAH, and ADMA signalling pathways and create similar effects with atorvastatin.

Cytokine Adsorber Use during DCD Heart Perfusion Counteracts Coronary Microvascular Dysfunction

Microvascular dysfunction (MVD) in cardiac allografts is associated with an impaired endothelial function in the coronary microvasculature. Ischemia/reperfusion injury (IRI) deteriorates endothelial function. Hearts donated after circulatory death (DCD) are exposed to warm ischemia before initiating ex vivo blood perfusion (BP). The impact of cytokine adsorption during BP to prevent MVD in DCD hearts is unknown. In a porcine DCD model, we assessed the microvascular function of hearts after BP with (DCD-BPCytoS, n = 5) or without (DCD-BP, n = 5) cytokine adsorption (CytoSorb®). Microvascular autoregulation was assessed by increasing the coronary perfusion pressure, while myocardial microcirculation was measured by Laser-Doppler-Perfusion (LDP). We analyzed the immunoreactivity of arteriolar oxidative stress markers nitrotyrosine and 4-hydroxy-2-nonenal (HNE), endothelial injury indicating cell adhesion molecules CD54, CD106 and CD31, and eNOS. We profiled the concentration of 13 cytokines in the perfusate. The expression of 84 genes was determined and analyzed using machine learning and decision trees. Non-DCD hearts served as a control for the gene expression analysis. Compared to DCD-BP, relative LDP was improved in the DCD-BPCytoS group (1.51 ± 0.17 vs. 1.08 ± 0.17). Several pro- and anti-inflammatory cytokines were reduced in the DCD-BPCytoS group. The expression of eNOS significantly increased, and the expression of nitrotyrosine, HNE, CD54, CD106, and CD31, markers of endothelial injury, majorly decreased in the DCD-BPCytoS group. Three genes allowed exact differentiation between groups; regulation of HIF1A enabled differentiation between perfusion (DCD-BP, DCD-BPCytoS) and non-perfusion groups. CAV1 allowed differentiation between BP and BPCytoS. The use of a cytokine adsorption device during BP counteracts preload-dependent MVD and preserves the microvascular endothelium by preventing oxidative stress and IRI of coronary arterioles of DCD hearts.

Genetic Factors for Coronary Heart Disease and Their Mechanisms: A Meta-Analysis and Comprehensive Review of Common Variants from Genome-Wide Association Studies

Genome-wide association studies (GWAS) have discovered 163 loci related to coronary heart disease (CHD). Most GWAS have emphasized pathways related to single-nucleotide polymorphisms (SNPs) that reached genome-wide significance in their reports, while identification of CHD pathways based on the combination of all published GWAS involving various ethnicities has yet to be performed. We conducted a systematic search for articles with comprehensive GWAS data in the GWAS Catalog and PubMed, followed by a meta-analysis of the top recurring SNPs from ≥2 different articles using random or fixed-effect models according to Cochran Q and I² statistics, and pathway enrichment analysis. Meta-analyses showed significance for 265 of 309 recurring SNPs. Enrichment analysis returned 107 significant pathways, including lipoprotein and lipid metabolisms (rs7412, rs6511720, rs11591147, rs1412444, rs11172113, rs11057830, rs4299376), atherogenesis (rs7500448, rs6504218, rs3918226, rs7623687), shared cardiovascular pathways (rs72689147, rs1800449, rs7568458), diabetes-related pathways (rs200787930, rs12146487, rs6129767), hepatitis C virus infection/hepatocellular carcinoma (rs73045269/rs8108632, rs56062135, rs188378669, rs4845625, rs11838776), and miR-29b-3p pathways (rs116843064, rs11617955, rs146092501, rs11838776, rs73045269/rs8108632). In this meta-analysis, the identification of various genetic factors and their associated pathways associated with CHD denotes the complexity of the disease. This provides an opportunity for the future development of novel CHD genetic risk scores relevant to personalized and precision medicine.

Role of Endothelial STAT3 in Cerebrovascular Function and Protection from Ischemic Brain Injury

STAT3 plays a protective role against ischemic brain injury; however, it is not clear which brain cell type mediates this effect, and by which mechanism. We tested the hypothesis that endothelial STAT3 contributes to protection from cerebral ischemia, by preserving cerebrovascular endothelial function and blood-brain barrier (BBB) integrity. The objective of this study was to determine the role of STAT3 in cerebrovascular endothelial cell (EC) survival and function, and its role in tissue outcome after cerebral ischemia. We found that in primary mouse brain microvascular ECs, STAT3 was constitutively active, and its phosphorylation was reduced by oxygen-glucose deprivation (OGD), recovering after re-oxygenation. STAT3 inhibition, using two mechanistically different pharmacological inhibitors, increased EC injury after OGD. The sub-lethal inhibition of STAT3 caused endothelial dysfunction, demonstrated by reduced nitric oxide release in response to acetylcholine and reduced barrier function of the endothelial monolayer. Finally, mice with reduced endothelial STAT3 (Tie2-Cre; STAT3flox/wt) sustained larger brain infarcts after middle cerebral artery occlusion (MCAO) compared to wild-type (WT) littermates. We conclude that STAT3 is vital to maintaining cerebrovascular integrity, playing a role in EC survival and function, and protection against cerebral ischemia. Endothelial STAT3 may serve as a potential target in preventing endothelial dysfunction after stroke.

Paracrine Shear-Stress-Dependent Signaling from Endothelial Cells Affects Downstream Endothelial Function and Inflammation

Cardiovascular diseases (CVDs), mainly ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and major contributors to disability worldwide. Despite their heterogeneity, almost all CVDs share a common feature: the endothelial dysfunction. This is defined as a loss of functionality in terms of anti-inflammatory, anti-thrombotic and vasodilatory abilities of endothelial cells (ECs). Endothelial function is greatly ensured by the mechanotransduction of shear forces, namely, endothelial wall shear stress (WSS). Low WSS is associated with endothelial dysfunction, representing the primary cause of atherosclerotic plaque formation and an important factor in plaque progression and remodeling. In this work, the role of factors released by ECs subjected to different magnitudes of shear stress driving the functionality of downstream endothelium has been evaluated. By means of a microfluidic system, HUVEC monolayers have been subjected to shear stress and the conditioned media collected to be used for the subsequent static culture. The results demonstrate that conditioned media retrieved from low shear stress experimental conditions (LSS-CM) induce the downregulation of endothelial nitric oxide synthase (eNOS) expression while upregulating peripheral blood mononuclear cell (PBMC) adhesion by means of higher levels of adhesion molecules such as E-selectin and ICAM-1. Moreover, LSS-CM demonstrated a significant angiogenic ability comparable to the inflammatory control media (TNFα-CM); thus, it is likely related to tissue suffering. We can therefore suggest that ECs stimulated at low shear stress (LSS) magnitudes are possibly involved in the paracrine induction of peripheral endothelial dysfunction, opening interesting insights into the pathogenetic mechanisms of coronary microvascular dysfunction.

The vital role for nitric oxide in intraocular pressure homeostasis

Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.

Fluid shear stress sensing in vascular homeostasis and remodeling: Towards the development of innovative pharmacological approaches to treat vascular dysfunction

Blood circulation, facilitating gas exchange and nutrient transportation, is a quintessential feature of life in vertebrates. Any disruption to blood flow, may it be by blockade or traumatic rupture, irrevocably leads to tissue infarction or death. Therefore, it is not surprising that hemostasis and vascular adaptation measures have been evolutionarily selected to mitigate the adverse consequences of altered circulation. Blood vessels can be broadly categorized as arteries, veins, or capillaries, based on their structure, hemodynamics, and gas exchange. However, all of them share one property: they are lined with an epithelial sheet called the endothelium, which typically lies on a basement membrane. This endothelium is the primary interface between the flowing blood and the rest of the body, and it has highly specialized molecular mechanisms to detect and respond to changes in blood perfusion. The purpose of this commentary will be to highlight some of the recent developments in the research on blood flow sensing, vascular remodeling, and homeostasis and to discuss the development of innovative pharmaceutical approaches targeting mechanosensing mechanisms to prolong patient survival and improve quality of life.

Phospholipase D2 loss results in increased blood pressure via inhibition of the endothelial nitric oxide synthase pathway

The Phospholipase D (PLD) superfamily is linked to neurological disease, cancer, and fertility, and a recent report correlated a potential loss-of-function PLD2 polymorphism with hypotension. Surprisingly, PLD2 -/- mice exhibit elevated blood pressure accompanied by associated changes in cardiac performance and molecular markers, but do not have findings consistent with the metabolic syndrome. Instead, expression of endothelial nitric oxide synthase (eNOS), which generates the potent vasodilator nitric oxide (NO), is decreased. An eNOS inhibitor phenocopied PLD2 loss and had no further effect on PLD2 -/- mice, confirming the functional relationship. Using a human endothelial cell line, PLD2 loss of function was shown to lower intracellular free cholesterol, causing upregulation of HMG Co-A reductase, the rate-limiting enzyme in cholesterol synthesis. HMG Co-A reductase negatively regulates eNOS, and the PLD2-deficiency phenotype of decreased eNOS expression and activity could be rescued by cholesterol supplementation and HMG Co-A reductase inhibition. Together, these findings identify a novel pathway through which the lipid signaling enzyme PLD2 regulates blood pressure, creating implications for on-going therapeutic development of PLD small molecule inhibitors. Finally, we show that the human PLD2 polymorphism does not trigger eNOS loss, but rather creates another effect, suggesting altered functioning for the allele.

Nitric-oxide synthase trafficking inducer is a pleiotropic regulator of endothelial cell function and signaling

Endothelial nitric-oxide synthase (eNOS) and its bioactive product, nitric oxide (NO), mediate many endothelial cell functions, including angiogenesis and vascular permeability. For example, vascular endothelial growth factor (VEGF)-mediated angiogenesis is inhibited upon reduction of NO bioactivity both in vitro and in vivo Moreover, genetic disruption or pharmacological inhibition of eNOS attenuates angiogenesis during tissue repair, resulting in delayed wound closure. These observations emphasize that eNOS-derived NO can promote angiogenesis. Intriguingly, eNOS activity is regulated by nitric-oxide synthase trafficking inducer (NOSTRIN), which sequesters eNOS, thereby attenuating NO production. This has prompted significant interest in NOSTRIN's function in endothelial cells. We show here that NOSTRIN affects the functional transcriptome of endothelial cells by down-regulating several genes important for invasion and angiogenesis. Interestingly, the effects of NOSTRIN on endothelial gene expression were independent of eNOS activity. NOSTRIN also affected the expression of secreted cytokines involved in inflammatory responses, and ectopic NOSTRIN overexpression functionally restricted endothelial cell proliferation, invasion, adhesion, and VEGF-induced capillary tube formation. Furthermore, NOSTRIN interacted directly with TNF receptor-associated factor 6 (TRAF6), leading to the suppression of NFκB activity and inhibition of AKT activation via phosphorylation. Interestingly, TNF-α-induced NFκB pathway activation was reversed by NOSTRIN. We found that the SH3 domain of NOSTRIN is involved in the NOSTRIN-TRAF6 interaction and is required for NOSTRIN-induced down-regulation of endothelial cell proteins. These results have broad biological implications, as aberrant NOSTRIN expression leading to deactivation of the NFκB pathway, in turn triggering an anti-angiogenic cascade, might inhibit tumorigenesis and cancer progression.

Endothelial Nitric Oxide Synthase Traffic Inducer (NOSTRIN) is a Negative Regulator of Disease Aggressiveness in Pancreatic Cancer

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is refractory to available treatments. Delineating critical pathways, responsible for disease aggressiveness and therapeutic resistance, may identify effective therapeutic targets. We aimed to identify key pathways contributing to disease aggressiveness by comparing gene expression profiles of tumors from early-stage PDAC cases with extremely poor survival (≤7 months) and those surviving 2 years or more following surgical resection.

EXPERIMENTAL DESIGN

Gene expression profiling was performed in tumors in a test cohort of PDAC (N = 50), which included short (≤7 months, N = 11) and long surviving (≥2 years, N = 14) patients, using affymetrix GeneChip Human 1.0 ST array. Key genes associated with disease aggressiveness were identified, using Cox regression, Kaplan-Meier, and pathway analyses with validations in independent cohorts for mechanistic and functional analyses.

RESULTS

Gene expression profiling identified 1,820 differentially expressed genes between short and long survival groups with inflammatory gene network ranking first. Lower expression of endothelial nitric oxide synthase traffic inducer (NOSTRIN) was associated with worst survival indicating its potential inhibitory role in disease progression. NOSTRIN overexpression suppressed migration and invasion of pancreatic cancer cells and enhanced sensitivity to chemotherapeutic drug gemcitabine. NOSTRIN inhibited production of nitric oxide (NO) by suppressing the activation of endothelial nitric oxide synthase (eNOS). Furthermore, miR-221, bound to the 3'UTR of NOSTRIN and suppressed its expression, and an increased miR-221 expression associated with poor survival in PDAC.

CONCLUSIONS

Our findings showed that NOSTRIN is a potential negative regulator of disease aggressiveness, which may be targeted for designing improved treatment strategy in PDAC. Clin Cancer Res; 22(24); 5992-6001. ©2016 AACR.

Biomechanics of vascular mechanosensation and remodeling

Flowing blood exerts a frictional force, fluid shear stress (FSS), on the endothelial cells that line the blood and lymphatic vessels. The magnitude, pulsatility, and directional characteristics of FSS are constantly sensed by the endothelium. Sustained increases or decreases in FSS induce vessel remodeling to maintain proper perfusion of tissue. In this review, we discuss these mechanisms and their relevance to physiology and disease, and propose a model for how information from different mechanosensors might be integrated to govern remodeling.

Endothelial Mechanosignaling: Does One Sensor Fit All?

SIGNIFICANCE

Forces are important in the cardiovascular system, acting as regulators of vascular physiology and pathology. Residing at the blood vessel interface, cells (endothelial cell, EC) are constantly exposed to vascular forces, including shear stress. Shear stress is the frictional force exerted by blood flow, and its patterns differ based on vessel geometry and type. These patterns range from uniform laminar flow to nonuniform disturbed flow. Although ECs sense and differentially respond to flow patterns unique to their microenvironment, the mechanisms underlying endothelial mechanosensing remain incompletely understood.

RECENT ADVANCES

A large body of work suggests that ECs possess many mechanosensors that decorate their apical, junctional, and basal surfaces. These potential mechanosensors sense blood flow, translating physical force into biochemical signaling events.

CRITICAL ISSUES

Understanding the mechanisms by which proposed mechanosensors sense and respond to shear stress requires an integrative approach. It is also critical to understand the role of these mechanosensors not only during embryonic development but also in the different vascular beds in the adult. Possible cross talk and integration of mechanosensing via the various mechanosensors remain a challenge.

FUTURE DIRECTIONS

Determination of the hierarchy of endothelial mechanosensors is critical for future work, as is determination of the extent to which mechanosensors work together to achieve force-dependent signaling. The role and primary sensors of shear stress during development also remain an open question. Finally, integrative approaches must be used to determine absolute mechanosensory function of potential mechanosensors. Antioxid. Redox Signal. 25, 373-388.

The Cytokinome Profile in Patients with Hepatocellular Carcinoma and Type 2 Diabetes

Understanding the dynamics of the complex interaction network of cytokines, defined as ‘‘cytokinome’’, can be useful to follow progression and evolution of hepatocellular carcinoma (HCC) from its early stages as well as to define therapeutic strategies. Recently we have evaluated the cytokinome profile in patients with type 2 diabetes (T2D) and/or chronic hepatitis C (CHC) infection and/or cirrhosis suggesting specific markers for the different stages of the diseases. Since T2D has been identified as one of the contributory cause of HCC, in this paper we examined the serum levels of cytokines, growth factors, chemokines, as well as of other cancer and diabetes biomarkers in a discovery cohort of patients with T2D, chronic hepatitis C (CHC) and/or CHC-related HCC comparing them with a healthy control group to define a profile of proteins able to characterize these patients, and to recognize the association between diabetes and HCC. The results have evidenced that the serum levels of some proteins are significantly and differently up-regulated in all the patients but they increased still more when HCC develops on the background of T2D. Our results were verified also using a separate validation cohort. Furthermore, significant correlations between clinical and laboratory data characterizing the various stages of this complex disease, have been found. In overall, our results highlighted that a large and simple omics approach, such as that of the cytokinome analysis, supplemented by common biochemical and clinical data, can give a complete picture able to improve the prognosis of the various stages of the disease progression. We have also demonstrated by means of interactomic analysis that our experimental results correlate positively with the general metabolic picture that is emerging in the literature for this complex multifactorial disease.

PECAM-1 isoforms, eNOS and endoglin axis in regulation of angiogenesis

Vascular development and maintenance of proper vascular function through various regulatory mechanisms are critical to our wellbeing. Delineation of the regulatory processes involved in development of the vascular system and its function is one of the most important topics in human physiology and pathophysiology. Platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), a cell adhesion molecule with proangiogenic and proinflammatory activity, has been the subject of numerous studies. In the present review, we look at the important roles that PECAM-1 and its isoforms play during angiogenesis, and its molecular mechanisms of action in the endothelium. In the endothelium, PECAM-1 not only plays a role as an adhesion molecule but also participates in intracellular signalling pathways which have an impact on various cell adhesive mechanisms and endothelial nitric oxide synthase (eNOS) expression and activity. In addition, recent studies from our laboratory have revealed an important relationship between PECAM-1 and endoglin expression. Endoglin is an essential molecule during angiogenesis, vascular development and integrity, and its expression and activity are compromised in the absence of PECAM-1. In the present review we discuss the roles that PECAM-1 isoforms may play in modulation of endothelial cell adhesive mechanisms, eNOS and endoglin expression and activity, and angiogenesis.

Platelet endothelial cell adhesion molecule-1 mediates endothelial-cardiomyocyte communication and regulates cardiac function

Background

Dilated cardiomyopathy is characterized by impaired contractility of cardiomyocytes, ventricular chamber dilatation, and systolic dysfunction. Although mutations in genes expressed in the cardiomyocyte are the best described causes of reduced contractility, the importance of endothelial‐cardiomyocyte communication for proper cardiac function is increasingly appreciated. In the present study, we investigate the role of the endothelial adhesion molecule platelet endothelial cell adhesion molecule (PECAM‐1) in the regulation of cardiac function.

Methods and Results

Using cell culture and animal models, we show that PECAM‐1 expressed in endothelial cells (ECs) regulates cardiomyocyte contractility and cardiac function via the neuregulin‐ErbB signaling pathway. Conscious echocardiography revealed left ventricular (LV) chamber dilation and systolic dysfunction in PECAM‐1^−/− mice in the absence of histological abnormalities or defects in cardiac capillary density. Despite deficits in global cardiac function, cardiomyocytes isolated from PECAM‐1^−/− hearts displayed normal baseline and isoproterenol‐stimulated contractility. Mechanistically, absence of PECAM‐1 resulted in elevated NO/ROS signaling and NRG‐1 release from ECs, which resulted in augmented phosphorylation of its receptor ErbB2. Treatment of cardiomyocytes with conditioned media from PECAM‐1^−/− ECs resulted in enhanced ErbB2 activation, which was normalized by pre‐treatment with an NRG‐1 blocking antibody. To determine whether normalization of increased NRG‐1 levels could correct cardiac function, PECAM‐1^−/− mice were treated with the NRG‐1 blocking antibody. Echocardiography showed that treatment significantly improved cardiac function of PECAM‐1^−/− mice, as revealed by increased ejection fraction and fractional shortening.

Conclusions

We identify a novel role for PECAM‐1 in regulating cardiac function via a paracrine NRG1‐ErbB pathway. These data highlight the importance of tightly regulated cellular communication for proper cardiac function.

Polymers for Cardiovascular Stent Coatings

Polymers have found widespread applications in cardiology, in particular in coronary vascular intervention as stent platforms (scaffolds) and coating matrices for drug-eluting stents. Apart from permanent polymers, current research is focussing on biodegradable polymers. Since they degrade once their function is fulfilled, their use might contribute to the reduction of adverse events like in-stent restenosis, late stent-thrombosis, and hypersensitivity reactions. After reviewing current literature concerning polymers used for cardiovascular applications, this review deals with parameters of tissue and blood cell functions which should be considered to evaluate biocompatibility of stent polymers in order to enhance physiological appropriate properties. The properties of the substrate on which vascular cells are placed can have a large impact on cell morphology, differentiation, motility, and fate. Finally, methods to assess these parameters under physiological conditions will be summarized.

Unraveling the mechanisms of action of lactoferrin-derived antihypertensive peptides: ACE inhibition and beyond

The characterization of lactoferrin-derived antihypertensive peptides shows that they might act on several molecular targets.

Specificity in S-nitrosylation: a short-range mechanism for NO signaling?

SIGNIFICANCE

Nitric oxide (NO) classical and less classical signaling mechanisms (through interaction with soluble guanylate cyclase and cytochrome c oxidase, respectively) operate through direct binding of NO to protein metal centers, and rely on diffusibility of the NO molecule. S-Nitrosylation, a covalent post-translational modification of protein cysteines, has emerged as a paradigm of nonclassical NO signaling.

RECENT ADVANCES

Several nonenzymatic mechanisms for S-nitrosylation formation and destruction have been described. Enzymatic mechanisms for transnitrosylation and denitrosylation have been also studied as regulators of the modification of specific subsets of proteins. The advancement of modification-specific proteomic methodologies has allowed progress in the study of diverse S-nitrosoproteomes, raising clues and questions about the parameters for determining the protein specificity of the modification.

CRITICAL ISSUES

We propose that S-nitrosylation is mainly a short-range mechanism of NO signaling, exerted in a relatively limited range of action around the NO sources, and tightly related to the very controlled regulation of subcellular localization of nitric oxide synthases. We review the nonenzymatic and enzymatic mechanisms that support this concept, as well as physiological examples of mammalian systems that illustrate well the precise compartmentalization of S-nitrosylation.

FUTURE DIRECTIONS

Individual and proteomic studies of protein S-nitrosylation-based signaling should take into account the subcellular localization in order to gain further insight into the functional role of this modification in (patho)physiological settings.

Specificity in S-nitrosylation: a short-range mechanism for NO signaling?

SIGNIFICANCE

Nitric oxide (NO) classical and less classical signaling mechanisms (through interaction with soluble guanylate cyclase and cytochrome c oxidase, respectively) operate through direct binding of NO to protein metal centers, and rely on diffusibility of the NO molecule. S-Nitrosylation, a covalent post-translational modification of protein cysteines, has emerged as a paradigm of nonclassical NO signaling.

RECENT ADVANCES

Several nonenzymatic mechanisms for S-nitrosylation formation and destruction have been described. Enzymatic mechanisms for transnitrosylation and denitrosylation have been also studied as regulators of the modification of specific subsets of proteins. The advancement of modification-specific proteomic methodologies has allowed progress in the study of diverse S-nitrosoproteomes, raising clues and questions about the parameters for determining the protein specificity of the modification.

CRITICAL ISSUES

We propose that S-nitrosylation is mainly a short-range mechanism of NO signaling, exerted in a relatively limited range of action around the NO sources, and tightly related to the very controlled regulation of subcellular localization of nitric oxide synthases. We review the nonenzymatic and enzymatic mechanisms that support this concept, as well as physiological examples of mammalian systems that illustrate well the precise compartmentalization of S-nitrosylation.

FUTURE DIRECTIONS

Individual and proteomic studies of protein S-nitrosylation-based signaling should take into account the subcellular localization in order to gain further insight into the functional role of this modification in (patho)physiological settings.

Modelling the effect of a functional endothelium on the development of in-stent restenosis

Treatment of stenosed coronary arteries by balloon angioplasty and stenting results in arterial injury including severe damage to the endothelium at the site of treatment and initiates a complex cascade of inflammatory processes that may lead to the development of in-stent restenosis (ISR). Many clinical and biological factors involved in the progression of restenotic lesions have been studied in detail over the past few years but the mystery behind the pathophysiological mechanisms of this disease is still unresolved. In the present work, the effects of re-endothelialization and nitric oxide release on neointimal growth are investigated in-silico using a two dimensional multi-scale model of ISR. The effect of stent deployment depths on the development of ISR is studied as a function of time after stenting. Two dimensional domains were prepared by deploying bare metal stent struts at three different deployment depths into the tissue. Shear stress distribution on endothelial cells, obtained by blood flow simulations, was translated into nitric oxide production that keeps the smooth muscle cells in quiescent state. The cellular growth trends were plotted as a function of time and the data indicate a positive correlation between the neointimal growths and strut deployment depths in the presence of a functional endothelium, in qualitative agreement with in-vivo data. Additionally, no ISR is observed if a functional endothelium appears much earlier.

A comparison of maternal serum levels of endothelial nitric oxide synthase, asymmetric dimethylarginine, and homocysteine in normal and preeclamptic pregnancies

Background

The aim of this study was to determine the maternal serum concentrations of eNOS, ADMA, and homocysteine in preeclamptic pregnancies.

Material/Methods

The study was carried out on 62 patients with pregnancy complicated by early onset and 53 patients with late onset preeclampsia. The control group consisted of 65 healthy normotensive pregnant patients. The serum eNOS, ADMA and homocysteine concentrations were determined using ELISA assays.

Results

Our study revealed elevated levels of homocysteine and ADMA in the serum of women with preeclampsia. The highest levels were observed in patients with early onset preeclampsia, but the differences between both groups of preeclamptic patients with early and late onset of preeclampsia were not statistically significant. Both groups of preeclamptic women had slightly lower levels of maternal serum endothelial nitric oxide synthase than in normotensive pregnant women, but these differences were not statistically significant.

Conclusions

The higher levels of homocysteine and ADMA observed in patients with early onset preeclampsia may suggest that higher levels of maternal serum homocysteine and ADMA correlate with the severity, and may determine the earlier clinical onset of the disease. The elevated levels of ADMA and the unchanged levels of eNOS in preeclamptic pregnancies suggest that NO deficiency in this pregnancy disorder results not from a reduced level or activity of eNOS, but from elevated levels of ADMA, an endogenous eNOS inhibitor. The lowering of increased levels of homocysteine and ADMA may be helpful in therapy of vascular disturbances occurring in preeclampsia.

Differences in the association between maternal serum homocysteine and ADMA levels in women with pregnancies complicated by preeclampsia and/or intrauterine growth restriction

OBJECTIVE

The aim of our study was to investigate the association between homocysteine and asymmetric dimethylarginine in preeclamptic women with and without intrauterine growth restriction compared with normal healthy uncomplicated pregnancies and normotensive pregnancies complicated by idiopathic isolated intrauterine fetal growth restriction.

METHODS

The maternal serum homocysteine and asymmetric dimethylarginine concentrations were determined using a sandwich enzyme-linked immunosorbent assays.

RESULTS

A statistically significant positive correlation of maternal serum homocysteine levels with the serum asymmetric dimethylarginine levels was observed in healthy normotensive uncomplicated pregnant women from the control group and in preeclamptic patients with appropriate-for-gestational-age fetuses (R = 0.380079, p-value = 0.002311* and R = 0.455797, p-value = 0.004030* for the control and the P groups, respectively). However, this correlation was not significant in women with pregnancy complicated by intrauterine growth restriction, both isolated and in the course of severe preeclampsia.

CONCLUSION

These findings provide support for the hypothesis that elevated levels of asymmetric dimethylarginine in pregnancy complicated by preeclampsia are associated with elevated homocysteine levels. But our results also demonstrate that in pregnancies complicated by intrauterine growth restriction, this mechanism is important, although not the only one.

Rapamycin protects against myocardial ischemia-reperfusion injury through JAK2-STAT3 signaling pathway

Rapamycin (Sirolimus®) is used to prevent rejection of transplanted organs and coronary restenosis. We reported that rapamycin induced cardioprotection against ischemia-reperfusion (I/R) injury through opening of mitochondrial K(ATP) channels. However, signaling mechanisms in rapamycin-induced cardioprotection are currently unknown. Considering that STAT3 is protective in the heart, we investigated the potential role of this transcription factor in rapamycin-induced protection against (I/R) injury. Adult male ICR mice were treated with rapamycin (0.25mg/kg, i.p.) or vehicle (DMSO) with/without inhibitor of JAK2 (AG-490) or STAT3 (stattic). One hour later, the hearts were subjected to I/R either in Langendorff mode or in situ ligation of left coronary artery. Additionally, primary murine cardiomyocytes were subjected to simulated ischemia-reoxygenation (SI/RO) injury in vitro. For in situ targeted knockdown of STAT3, lentiviral vector containing short hairpin RNA was injected into the left ventricle 3 weeks prior to initiating I/R injury. Infarct size, cardiac function, and cardiomyocyte necrosis and apoptosis were assessed. Rapamycin reduced infarct size, improved cardiac function following I/R, and limited cardiomyocyte necrosis as well as apoptosis following SI/RO which were blocked by AG-490 and stattic. In situ knock-down of STAT3 attenuated rapamycin-induced protection against I/R injury. Rapamycin triggered unique cardioprotective signaling including phosphorylation of ERK, STAT3, eNOS and glycogen synthase kinase-3ß in concert with increased prosurvival Bcl-2 to Bax ratio. Our data suggest that JAK2-STAT3 signaling plays an essential role in rapamycin-induced cardioprotection. We propose that rapamycin is a novel and clinically relevant pharmacological strategy to target STAT3 activation for treatment of myocardial infarction.

The F-BAR protein NOSTRIN participates in FGF signal transduction and vascular development

F-BAR proteins are multivalent adaptors that link plasma membrane and cytoskeleton and coordinate cellular processes such as membrane protrusion and migration. Yet, little is known about the function of F-BAR proteins in vivo. Here we report, that the F-BAR protein NOSTRIN is necessary for proper vascular development in zebrafish and postnatal retinal angiogenesis in mice. The loss of NOSTRIN impacts on the migration of endothelial tip cells and leads to a reduction of tip cell filopodia number and length. NOSTRIN forms a complex with the GTPase Rac1 and its exchange factor Sos1 and overexpression of NOSTRIN in cells induces Rac1 activation. Furthermore, NOSTRIN is required for fibroblast growth factor 2 dependent activation of Rac1 in primary endothelial cells and the angiogenic response to fibroblast growth factor 2 in the in vivo matrigel plug assay. We propose a novel regulatory circuit, in which NOSTRIN assembles a signalling complex containing FGFR1, Rac1 and Sos1 thereby facilitating the activation of Rac1 in endothelial cells during developmental angiogenesis.

Lessons from the endothelial junctional mechanosensory complex

Mechanotransduction plays a key role in both normal physiology and in diseases such as cancer, atherosclerosis and hypertension. Nowhere is this more evident than in the vascular system, where fluid shear stress from blood flow plays a critical role in shaping the blood vessels and in determining their function and dysfunction. Responses to flow are mediated in part by a complex of proteins comprised of PECAM-1, VE-cadherin and VEGFR2 at endothelial cell-cell junctions; all proteins that clearly have other, non-mechanical functions. We review recent progress toward understanding the functions and mechanisms of mechanotransduction by this complex and suggest some principles that may apply more broadly.