Endothelial Nitric Oxide Availability Research Articles

Physiological Correlates of Hypnotizability: Hypnotic Behaviour and Prognostic Role in Medicine.

Studies in the field of experimental hypnosis highlighted the role of hypnotizability in the physiological variability of the general population. It is associated, in fact, with a few differences which are observable in the ordinary state of consciousness and in the absence of suggestions. The aim of the present scoping review is summarizing them and indicate their relevance to the neural mechanisms of hypnosis and to the prognosis and treatment of a few medical conditions. Individuals with high, medium and low hypnotizability scores display different cerebral functional differences-i.e., functional equivalence between imagery and perception/action, excitability of the motor cortex, interoceptive accuracy-possibly related to brain structural and functional characteristics, and different control of blood supply at peripheral and cerebral level, likely due to different availability of endothelial nitric oxide. These differences are reviewed to support the idea of their participation in hypnotic behaviour and to indicate their prognostic and therapeutic usefulness in a few medical conditions.

COMPOUND 21 IMPROVES VASCULAR FUNTION IN THE THORACIC AORTA FROM OBESE MICE: IMPLICATION OF AT2, MAS AND B2 RECEPTORS

Objective: The angiotensin AT2 Receptor (AT2R) is known to form heterodimers with either the Mas (MasR) or the bradykinin B2 receptor (B2R). Compound 21 (C21), a highly selective AT2R agonist, induces vascular relaxation through stimulation of nitric oxide (NO). Since AT2R is overexpressed in obese models, we hypothesize that C21 might prevent the development of vascular alterations associated with obesity. The aim of this study was to assess the effect of C21 on endothelial function in a model of diet-induced obesity and the potential crosstalk between AT2R, MasR and/or B2R in this response. Design and method: Eleven-week-old male C57BL6J mice (n = 20/group) were fed a standard (Chow) or a very high-fat diet (HF) for 6 weeks. Half of mice per group were simultaneously treated with C21 (1 mg/kg/day in drinking water, Chow-C21, HF-C21). Vascular reactivity experiments were performed in rings from thoracic aorta. NO production was determined in human endothelial cells (EA.hy926) using DAF-2DA (10-5 M). Results: Thoracic aortas from HF mice exhibited impaired relaxations to acetylcholine (Ach) compared to the Chow group. This alteration was prevented by treatment with C21 [Ach, ChowEmax = 85,6 ± 1,7%; HFEmax = 63,8 ± 3,0% vs HF-C21Emax = 86,0 ± 1,8%, P < 0.001]. In addition, NO availability calculated from the area under the Ach curve in presence and absence of L-NAME (NO synthase inhibitor) was significantly lower in HF mice and increased by C21 treatment [Chow = 237 arbitrary units (AU), HF = 168 AU vs HF-C21 = 239 AU; P < 0.001]. Aortic rings from HF mice exhibited stronger contractions to angiotensin II (Ang II, 10-9-10-6 M). PD123177 (AT2R antagonist, 10-7 M), A779 (MasR antagonist, 10-6 M) or HOE-140 (B2R antagonist, 10-7 M) significantly enhanced Ang II-induced contractions in Chow- but not in HF-rings. HF-C21 aortas exhibited similar responses to Chow rings. In EA.hy926 cells, C21 (10-6 M) significantly increased levels of phosphorylated eNOS and NO production. Both effects were abolished by PD123177, A779 or HOE-140, respectively. Conclusions: In conclusion, our data suggest that C21 improves endothelial dysfunction induced by HF-feeding due to an increase in endothelial NO availability via AT2R activation. In addition, both MasR and B2R are implicated in this response and seem necessary for mediating C21 effects.

Partial loss of endothelial nitric oxide leads to increased cerebrovascular beta amyloid

Cerebral amyloid angiopathy (CAA) is present in over half of the elderly population and in 80–90% of Alzheimer’s disease (AD) patients. CAA is defined by the deposition of beta amyloid (Aβ) in small cerebral arteries and capillaries. Cardiovascular risk factors are associated with an increased incidence of CAA. We utilized 18-month-old endothelial nitric oxide synthase (eNOS) heterozygous knockout (+/−) mice, a clinically relevant model of endothelial dysfunction, to examine the role of endothelial nitric oxide (NO) in vascular Aβ accumulation. eNOS+/− mice had significantly higher vascular levels of Aβ40 (P < 0.05). Aβ42 was not detected. There was no difference in Aβ in brain tissue. Amyloid precursor protein and β-site APP cleavage enzyme 1 protein levels were unaltered, while levels of the α-secretase enzyme, a disintegrin and metalloproteinase 10, were significantly lower in eNOS + /− microvascular tissue (P < 0.05). Insulin degrading enzyme and low-density lipoprotein receptor-related protein 1 were significantly increased in eNOS+/− microvascular tissue, most likely an adaptive response to locally higher Aβ concentrations. Lastly, catalase and CuZn superoxide dismutase were significantly elevated in eNOS+/− microvascular tissue (P < 0.05). These data demonstrate decreased availability of endothelial NO leads to increased cerebrovascular concentration of Aβ along with compensatory mechanisms to protect the vasculature.

Luteolin Prevents Cardiometabolic Alterations and Vascular Dysfunction in Mice With HFD-Induced Obesity.

Purpose: Luteolin exerts beneficial effects against obesity-associated comorbidities, although its influence on vascular dysfunction remains undetermined. We examined the effects of luteolin on endothelial dysfunction in a mouse model of diet-induced obesity.Methods: Standard diet (SD) or high-fat diet (HFD)-fed mice were treated daily with luteolin intragastrically. After 8 weeks, body and epididymal fat weight, as well as blood cholesterol, glucose, and triglycerides were evaluated. Endothelium-dependent relaxations of resistance mesenteric vessels was assessed by a concentration-response curve to acetylcholine, repeated upon Nw-nitro-L-arginine methylester (L-NAME) or ascorbic acid infusion to investigate the influence of nitric oxide (NO) availability and reactive oxygen species (ROS) on endothelial function, respectively. Intravascular ROS production and TNF levels were measured by dihydroethidium dye and ELISA, respectively. Endothelial NO synthase (eNOS) and superoxide dismutase 1 (SOD1), as well as microRNA-214-3p expression were examined by Western blot and RT-PCR assays, respectively.Results: HFD animals displayed elevated body weight, epididymal fat weight and metabolic indexes. Endothelium-dependent relaxation was resistant to L-NAME and enhanced by ascorbic acid, which restored also the inhibitory effect of L-NAME, suggesting a ROS-dependent reduction of NO availability in HFD vessels. Moreover, media-lumen ratio, intravascular superoxide anion and TNF levels were increased, while vascular eNOS, SOD1, and microRNA-214-3p expression were decreased. In HFD mice, luteolin counteracted the increase in body and epididymal fat weight, and metabolic alterations. Luteolin restored vascular endothelial NO availability, normalized the media-lumen ratio, decreased ROS and TNF levels, and normalized eNOS, SOD1 and microRNA-214-3p expression.Conclusion: Luteolin prevents systemic metabolic alterations and vascular dysfunction associated with obesity, likely through antioxidant and anti-inflammatory mechanisms.

Role of flavonoids and nitrates in cardiovascular health.

CVD remain the leading cause of death globally. Effective dietary strategies for their reduction are of high priority. Increasing evidence suggests that phytochemicals, particularly dietary flavonoids and nitrates, are key modulators of CVD risk reduction through impact on multiple risk factors. The aim of this review is to explore the evidence for the impact of flavonoid- and nitrate-rich foods and supplements on CVD risk, with specific reference to their importance as mediators of vascular health and platelet function. There is accumulating evidence to support benefits of dietary flavonoids on cardiovascular health. Dose-dependent recovery of endothelial function and lowering of blood pressure have been reported for the flavanol (-)-epicatechin, found in cocoa, apples and tea, through production and availability of endothelial nitric oxide (NO). Furthermore, flavonoids, including quercetin and its metabolites, reduce in vitro and ex vivo platelet function via inhibition of phosphorylation-dependent cellular signalling pathways, although further in vivo studies are required to substantiate these mechanistic effects. Hypotensive effects of dietary nitrates have been consistently reported in healthy subjects in acute and chronic settings, although there is less evidence for these effects in patient groups. Proposed mechanisms of actions include endothelial-independent NO availability, which is dependent on the entro-salivary circulation and microbial conversion of dietary nitrate to nitrite in the mouth. In conclusion, flavonoid- and nitrate-rich foods show promising effects on vascular function, yet further randomly controlled studies are required to confirm these findings and to determine effective doses.

The Interactions Between Kynurenine, Folate, Methionine and Pteridine Pathways in Obesity.

Obesity activates both innate and adaptive immune responses in adipose tissue. Elevated levels of eosinophils with depression of monocyte and neutrophil indicate the deficiencies in the immune system of morbidly obese individuals. Actually, adipose tissue macrophages are functional antigen-presenting cells that promote the proliferation of interferon-gamma (IFN-gamma)-producing CD4+ T cells in adipose tissue of obese subjects. Eventually, diet-induced obesity is associated with the loss of tissue homeostasis and development of type 1 inflammatory responses in visceral adipose tissue. Activity of inducible indoleamine 2,3-dioxygenase-1 (IDO-1) plays a major role under pro-inflammatory, IFN-gamma dominated settings. One of the two rate-limiting enzymes which can metabolize tryptophan to kynurenine is IDO-1. Tumor necrosis factor-alpha (TNF-alpha) correlates with IDO-1 in adipose compartments. Actually, IDO-1-mediated tryptophan catabolism due to chronic immune activation is the cause of reduced tryptophan plasma levels and be considered as the driving force for food intake in morbidly obese patients. Thus, decrease in plasma tryptophan levels and subsequent reduction in serotonin (5-HT) production provokes satiety dysregulation that leads to increased caloric uptake and obesity. However, after bariatric surgery, weight reduction does not lead to normalization of IDO-1 activity. Furthermore, there is a connection between arginine and tryptophan metabolic pathways in the generation of reactive nitrogen intermediates. Hence, abdominal obesity is associated with vascular endothelial dysfunction and reduced nitric oxide (NO) availability. IFN-gamma-induced activation of the inducible nitric oxide synthase (iNOS) and dissociation of endothelial adenosine monophosphate activated protein kinase (AMPK)- phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt)- endothelial NO synthase (eNOS) pathway enhances oxidative stress production secondary to high-fat diet. Thus, reduced endothelial NO availability correlates with the increase in plasma non-esterified fatty acids and triglycerides levels. Additionally, in obese patients, folate-deficiency leads to hyperhomocysteinemia. Folic acid confers protection against hyperhomocysteinemia-induced oxidative stress.

Moderate hypothermia attenuates α1-adrenoceptor-mediated contraction in human varicose spermatic vein: The role of nitric oxide(Short communication).

The effects of moderate hypothermia (28°C) on the response of human varicose spermatic vein to α1-adrenoceptor agonist phenylephrine and the role of endothelial nitric oxide (NO) in these effects were studied. Concentration-response curves for phenylephrine (10-9 to 3 × 10-4 M) were recorded in rings with and without endothelium at 37 and 28°C. To further analyze the role of NO, in the response to phenylephrine during hypothermia, the effects of this agonist in the presence of NG-nitro-L-arginine methyl ester (10-4 M) were also determined. Under every condition tested, phenylephrine produced a marked, concentration-dependent contraction. Sensitivity of intact veins to the agonist was consistently lower at 28°C than at 37°C. There was no significant difference in phenylephrine response at 28 and 37°C in vessels without endothelium but at 28°C veins without endothelium showed a higher sensitivity than intact veins to phenylephrine. The sensitivity of veins with and without endothelium to nitroprusside (10-9 to 3 × 10-3 M) was significantly decreased during hypothermia, and endothelium removal did not affect the relaxation to this nitrovasodilator. These results suggest that moderate hypothermia decreases the sensitivity of human varicose spermatic vein to phenylephrine probably by increasing the availability of endothelial NO.

Endothelial Dysfunction in Resistance Arteries of Hypertensive Humans: Old and New Conspirators.

A large body of homogeneous reports documented that endothelial dysfunction, which characterizes human essential hypertension is largely dependent on an impaired endothelial nitric oxide availability and an increased production of endothelium-derived contracting factors. These factors include endothelin, prostanoids, and reactive oxygen species (ROS). In particular, it was evidenced that acute intraarterial administration of indomethacin, a nonselective cyclooxygenase (COX)-inhibitor, and ascorbic acid, an antioxidant, normalized the blunted endothelial dysfunction by restoring nitric oxide availability at the level of peripheral microcirculation, thus demonstrating that COX-derived endothelium-derived contracting factors are one of the major sources of ROS. Recent studies put in evidence new lights on the mechanisms involved in endothelial dysfunction in human hypertension, identified as "new conspirators." In particular, functional and immunohistochemical experiments with selective COX inhibitors identified the isoform COX-2 as the main source of intravascular ROS generation in isolated small vessels from essential hypertensive patients. In addition, important vascular protective properties by human ghrelin have been demonstrated in human hypertension, in terms that its systemic reduction is involved in the pathophysiology of endothelial dysfunction, while a normalization of its levels may restore vascular homeostasis.

Role of rutin on nitric oxide synthesis in human umbilical vein endothelial cells.

Nitric oxide (NO), produced by endothelial nitric oxide synthase (eNOS), is a major antiatherogenic factor in the blood vessel. Oxidative stress plays an important role in the pathogenesis of various cardiovascular diseases, including atherosclerosis. Decreased availability of endothelial NO promotes the progression of endothelial dysfunction and atherosclerosis. Rutin is a flavonoid with multiple cardiovascular protective effects. This study aimed to investigate the effects of rutin on eNOS and NO production in cultured human umbilical vein endothelial cells (HUVEC). HUVEC were divided into four groups: control; oxidative stress induction with 180 μM H2O2; treatment with 300 μM rutin; and concomitant induction with rutin and H2O2 for 24 hours. HUVEC treated with rutin produced higher amount of NO compared to control (P < 0.01). In the oxidative stress-induced HUVEC, rutin successfully induced cells' NO production (P < 0.01). Rutin promoted NO production in HUVEC by inducing eNOS gene expression (P < 0.05), eNOS protein synthesis (P < 0.01), and eNOS activity (P < 0.05). Treatment with rutin also led to increased gene and protein expression of basic fibroblast growth factor (bFGF) in HUVEC. Therefore, upregulation of eNOS expression by rutin may be mediated by bFGF. The results showed that rutin may improve endothelial function by augmenting NO production in human endothelial cells.

Variant angina associated with myocardial bridging and obstructive sleep apnea syndrome after lumbar spine surgery.

Variant angina associated with myocardial bridging and obstructive sleep apnea syndrome after lumbar spine surgery.

Vascular Dysfunction in a Mouse Model of Rett Syndrome and Effects of Curcumin Treatment

Mutations in the coding sequence of the X-linked gene MeCP2 (Methyl CpG–binding protein) are present in around 80% of patients with Rett Syndrome, a common cause of intellectual disability in female and to date without any effective pharmacological treatment. A relevant, and so far unexplored feature of RTT patients, is a marked reduction in peripheral circulation. To investigate the relationship between loss of MeCP2 and this clinical aspect, we used the MeCP2 null mouse model B6.129SF1-MeCP2tm1Jae for functional and pharmacological studies. Functional experiments were performed on isolated resistance mesenteric vessels, mounted on a pressurized myograph. Vessels from female MeCP2+/− mice show a reduced endothelium-dependent relaxation, due to a reduced Nitric Oxide (NO) availability secondary to an increased Reactive Oxygen Species (ROS) generation. Such functional aspects are associated with an intravascular increase in superoxide anion production, and a decreased vascular eNOS expression. These alterations are reversed by curcumin administration (5% (w/w) dietary curcumin for 21 days), which restores endothelial NO availability, decreases intravascular ROS production and normalizes vascular eNOS gene expression. In conclusion our findings highlight alterations in the vascular/endothelial system in the absence of a correct function of MeCP2, and uncover related cellular/molecular mechanisms that are rescued by an anti-oxidant treatment.

Asymmetric Dimethylarginine: A Possible Link between Vascular Disease and Dementia

There is good epidemiological evidence that vascular disease predisposes to cognitive decline and dementia. The impact of vascular disease on dementia is likely to increase further because of the poor diagnosis and management of vascular risk factors, the increase in life expectancy, and the improved survival following major cardiovascular events, e.g. acute stroke. It is estimated that the adequate management of vascular risk factors, with pharmacological and/or nonpharmacological interventions, might result in a 50% reduction in the forecasted dementia prevalence. The exact mechanisms by which vascular risk factors and vascular disease adversely affect brain function remain unclear, but it is hypothesized that endothelial dysfunction plays an important role. Reduced synthesis and availability of endothelial nitric oxide (NO) may contribute to the development of dementia by at least two mechanisms: (1) favoring the onset and progression of atherosclerosis, vasoconstriction, and impaired cerebral blood flow regulation; and (2) reduced neuroprotection.Several studies have shown that asymmetric dimethylarginine (ADMA), an endogenous methylated form of the amino acid L-arginine, inhibits NO synthesis and favors oxidative stress and vascular damage. Unlike NO, ADMA concentrations are relatively stable and can be accurately measured in plasma. There is good evidence that higher plasma ADMA concentrations favor atherosclerosis and independently predict adverse cardiovascular and cerebrovascular outcomes in several patient groups. ADMA might represent a unifying pathophysiological pathway linking the presence of vascular risk factors with the onset and progression of cognitive decline and dementia. This review discusses the biological role of ADMA, its potential contribution to the onset and progression of dementia through vascular disease and atherosclerosis, the available evidence linking ADMA with cognitive impairment and dementia, and the strategies to characterize the predictive role of ADMA in cognitive impairment in epidemiological studies. Therapeutic implications and suggestions for future research directions are also discussed.

Abnormal High-Density Lipoprotein Induces Endothelial Dysfunction via Activation of Toll-like Receptor-2

Endothelial injury and dysfunction (ED) represent a link between cardiovascular risk factors promoting hypertension and atherosclerosis, the leading cause of death in Western populations. High-density lipoprotein (HDL) is considered antiatherogenic and known to prevent ED. Using HDL from children and adults with chronic kidney dysfunction (HDL(CKD)), a population with high cardiovascular risk, we have demonstrated that HDL(CKD) in contrast to HDL(Healthy) promoted endothelial superoxide production, substantially reduced nitric oxide (NO) bioavailability, and subsequently increased arterial blood pressure (ABP). We have identified symmetric dimethylarginine (SDMA) in HDL(CKD) that causes transformation from physiological HDL into an abnormal lipoprotein inducing ED. Furthermore, we report that HDL(CKD) reduced endothelial NO availability via toll-like receptor-2 (TLR-2), leading to impaired endothelial repair, increased proinflammatory activation, and ABP. These data demonstrate how SDMA can modify the HDL particle to mimic a damage-associated molecular pattern that activates TLR-2 via a TLR-1- or TLR-6-coreceptor-independent pathway, linking abnormal HDL to innate immunity, ED, and hypertension.

Reversible Pulmonary Hypertension Associated With Vitamin C Deficiency

We describe the case of a 40-year-old female patient who developed severe pulmonary hypertension and life-threatening right-sided heart failure in association with dietary scurvy and iron deficiency. Supplementation with oral vitamin C and iron very likely contributed to her complete cure. Scurvy-associated pulmonary arterial hypertension could result from impaired availability of endothelial nitric oxide, but inappropriate activation of the hypoxia-inducible family (HIF) of transcription factors could play an even more important role. HIF coordinates the body's responses to hypoxia, and its activity is regulated by oxygen-dependent prolyl hydroxylases, which need vitamin C and iron as cofactors. Deficiency of these cofactors could lead to uncontrolled HIF activity and pulmonary vasoconstriction responsive to vitamin C and iron administration.

Combined Antihypertensive and Cardioprotective Effects of Nebivolol and Hydrochlorothiazide in Spontaneous Hypertensive Rats

The antihypertensive and cardioprotective effects of the combination of nebivolol (NEB) and hydrochlorothiazide (HCTZ) in spontaneously hypertensive rats (SHR) were investigated. SHR and age-matched Wistar-Kyoto normotensive rats were randomly assigned to one of six groups: SHR treated with NEB (1 mg/kg/day, intragastric); SHR treated with HCTZ (5 mg/kg/day, intragastric); SHR treated with NEB plus HCTZ (1 + 2.5 mg/kg/day); SHR treated with NEB plus HCTZ (1 + 5 mg/kg/day), along with a SHR and a WKY control group. The effects of NEB and HCTZ on clinical chemistry parameters and on cardiac function and structure were evaluated. NEB and HCTZ in combination had synergistic antihypertensive effects and significantly reduced heart rate and blood pressure compared with monotherapy with either agent. These effects were independent of water intake, urine output and electrolyte excretion. NEB plus HCTZ was associated with reduced oxidative stress in terms of glutathione availability, lower angiotensin I levels as index of plasma renin activity and reduced clearance of urinary sodium compared with HCTZ alone. Cardiac morphometric data and antioxidant parameters indicate that NEB may influence cardiac structure by reducing hypertrophy and by enhancing the availability of endothelial nitric oxide - a unique characteristic of NEB. The authors suggest that a combination of NEB and HCTZ for the treatment of hypertension may be useful for the synergistic characteristics of both drugs.

Abstract 5553: S100A1 Modulates Endothelial Nitric Oxide Availability by Co-ordinate Regulation of Nitric Oxide Synthase Phosphorylation and Gene Expression of Related Signaling Molecules

Background: S100A1, a Ca 2+ -sensor protein in endothelial cell, regulates endothelial function. S100A1 knockout mice (KO) are hypertensive with impaired nitric oxide (NO) production and endothelial-dependent vasodilatation. We examine the impact of S100A1 on phosphorylation of Ser 1177 and Thr 495 , positive and negative regulatory residues, respectively, in endothelial nitric oxide synthase (eNOS) and on expression of diverse genes involved in eNOS signaling. Methods and Results: Endothelial cells (EC) were isolated and from pulmonary vasculature of wild-type (WT) and KO mice. WT EC exhibited higher proliferative rates than KO measured by WST-method, and expressed as absorbance/5000 cells/well (0.8923±0.091 vs. 0.268±0.055, p&lt;0.05, n=3) and higher NO production (2214.00±1016.17 vs. 566.75±243.79 nM, p&lt;0.05, n=6). Lower eNOS activity in KO was associated with higher and lower basal phosphorylation at Thr 495 and Ser 1177 , respectively. Bradykinin (100 nM) resulted in rapid (1 minute) 3-fold higher maximal phosphorylation of Ser 1177 in WT vs. KO with equivalent rapid dephosphorylation of Thr 495 in both cell types. By contrast, acetylcholine (10 μ M) at 30 seconds produced more robust dephosphorylation of Thr 495 in WT compared to KO, with comparable effects on Ser 1177 phosphorylation. In KO versus WT EC, PCR microarray analysis demonstrated greater than 2-fold increase in mRNA expression of caveolin-1, NADPH oxidase 1, glutathione peroxidase, and calmodulin-1. KO EC exhibited a 5-fold reduction in eNOS mRNA, confirmed by a reduction in eNOS protein (4.02±0.19 fold, n=3). Conclusion: Absence of S100A1 in endothelial cells results in impaired proliferation, decreased NO availability, and regulation of gene expression that contributes or, alternately, compensates for this phenotype. Lack of S100A1 also impairs co-ordinated eNOS phosphorylation at baseline, and in response to agonists, that augments NO production. Thus, S100A1 plays a multifactorial and novel role in controlling NO synthesis and the endothelial phenotype.

Lipoproteins, Platelets, and Atherothrombosis

Atherosclerosis and thrombosis associated with the rupture of vulnerable plaque are the main causes of cardiovascular events, including acute coronary syndrome. Low-density lipoprotein (LDL) plays a key role in the pathogenesis of atherothrombotic processes. LDLs modify the antithrombotic properties of the vascular endothelium and change vessel contractility by reducing the availability of endothelial nitric oxide and activating proinflammatory signaling pathways. In addition, LDLs also influence the functions and interactions of cells present in atherosclerotic lesions, whether they come from the circulation or are resident in vessel walls. In fact, LDLs entering affected vessels undergo modifications (e.g. oxidation, aggregation and glycosylation) that potentiate their atherogenic properties. Once modified, these intravascular LDLs promote the formation of foam cells derived from smooth muscle cells and macrophages, thereby increasing the vulnerability of atherosclerotic plaque. Moreover, they also increase the thrombogenicity of both plaque and blood, in which circulating tissue factor levels are raised and platelet reactivity is enhanced. This review focuses on the importance of native and modified LDL for the pathogenesis of atherothrombosis. It also discusses current studies on LDL and its effects on the actions of vascular cells and blood cells, particularly platelets, and considers novel potential therapeutic targets.

Do Adenosine Receptors Offer New Therapeutic Options for Diabetic Nephropathy?

Diabetes mellitus is currently considered to be an epidemic disease. Approximately a third of individuals with type 1 and type 2 diabetes develop persistent albuminuria, lose renal function, and are at increased risk of cardiovascular and other microvascular complications. Diabetic nephropathy (DN) is the primary cause of end stage renal disease throughout the world. Microvascular dysfunction in the glomerulus appears as an early pathogenic event in progression of this renal complication. In recent years, studies with animal knockout (KO) models have revealed that uncoupling of the vascular endothelial growth factor/nitric oxide (VEGF/NO) axis leads to the glomerular alterations that characterize diabetic nephropathy. Therefore, new therapeutic alternatives may usefully target VEGF overproduction or endothelial nitric oxide availability. Recent studies also demonstrate a role for adenosine receptors in glomerular physiology and VEGF production that looks promising for therapeutic intervention of the evolution of diabetic nephropathy. However further progress is required in order to understand the dynamics of local adenosine production, in particular the extracellular metabolism of adenine nucleotides by ectoenzymes and the role of nucleoside transporters on external adenosine accumulation in the glomerulus in the pathological state. So far there is no assay that is sufficiently sensitive and accurate for subclinical diagnoses of this renal disease, which is complicated and costly to patients with often devastating effects. Current studies using proteomics offer promising alternatives for the identification of new renal injury markers. It is hoped these will permit evaluation of new therapeutic tools for more opportune intervention of this disease.

Blockade of Nitroxidative Stress by Roasted Licorice Extracts in High Glucose-exposed Endothelial Cells

Diabetes can cause a wide variety of vascular complications and endothelial dysfunction. In this study, human vascular endothelial cells were exposed to 5.5 mM and 33 mM glucose for 5 d in the absence and presence of 1 to 20 mug/mL roasted licorice (Glycyrrhiza inflata Bat.) ethanol extracts (rLE). Caspase-3 activation and Annexin V staining revealed that high glucose induced endothelial apoptotic toxicity with a generation of reactive oxygen species (ROS) and these effects were reversed by rLE at >/=1 mug/mL in a dose-dependent manner. Cytoprotective rLE substantially reduced high glucose-induced expression of endothelial nitric oxide synthase (eNOS), and hence attenuated the formation of peroxynitrite radicals derived from NO. In addition, rLE suppressed expression of PKCbeta2 and activation of NADPH oxidase subunit of p22phox promoted by high glucose. However, rLE </=1 mug/mL did not modulate the high glucose-triggered activation of ASK-JNK signaling pathway. Our results suggest that PKCbeta2 expression and NADPH oxidase-dependent superoxide production and eNOS-mediated peroxynitrite generation may be essential mechanisms responsible for increased oxidative stress and endothelial apoptosis in chronic hyperglycemic conditions. Thus, rLE may be a beneficial agent most likely contributing to prevention of vascular NADPH oxidase induction and preservation of endothelial nitric oxide availability, resulting in blunting diabetes-associated endothelial dysfunction and vascular complications.

A Major Haplotype Block at the Rho-Associated Kinase 2 Locus Is Associated with a Lower Risk of Hypertension in a Recessive Manner: The HYPGENE Study

The goals of our study were to evaluate the haplotype pattern at the Rho-associated kinase 2 (ROCK2) locus and prospectively test the association between the ROCK2 haplotype-tagging single-nucleotide polymorphisms (tagSNPs) with hypertension for verified incident hypertensive patients (n=607) and healthy, normotensive controls (n=586) in a HYPGENE study. Rho-associated kinases (ROCKs) play a central role in signaling pathways that are involved in vascular smooth muscle contraction and endothelial nitric oxide availability. Using a set of stringent criteria (minor allele frequency>or=0.05, pairwise r2>or=0.95), we identified 18 tagSNPs from the 109 SNPs available in the HapMap Caucasian data set. TagSNPs were genotyped using the Illumina BeadStation platform. The 18 tagSNPs consisted of two linkage disequilibrium (LD) blocks. A haplotype defined by four SNPs (rs965665, rs10178332, rs6755196, rs10929732) in LD block 2 was recessively associated with a lower risk of hypertension (p=0.003). Homozygotes for the minor alleles had an 85% lower risk of hypertension than carriers of the common allele. The associations were independent of baseline age, cardiorespiratory fitness, body mass index, sex, and follow-up time. The LD block 2 spans about 137 kb of genomic DNA at the 5'-end of the ROCK2 locus and covers exons encoding the kinase domain of the protein. Our data strongly suggest that a major haplotype block at the ROCK2 locus is recessively associated with a lower risk of hypertension. Identification of functional mutation(s) could thus help in the development of ROCK2-specific treatments.