Histone deacetylase 9 promotes endothelial-mesenchymal transition and an unfavorable atherosclerotic plaque phenotype

Endothelial-mesenchymal transition (EndMT) is associated with various cardiovascular diseases and in particular with atherosclerosis and plaque instability. However, the molecular pathways that govern EndMT are poorly defined. Specifically, the role of epigenetic factors and histone deacetylases (HDACs) in controlling EndMT and the atherosclerotic plaque phenotype remains unclear. Here, we identified histone deacetylation, specifically that mediated by HDAC9 (a class IIa HDAC), as playing an important role in both EndMT and atherosclerosis. Using in vitro models, we found class IIa HDAC inhibition sustained the expression of endothelial proteins and mitigated the increase in mesenchymal proteins, effectively blocking EndMT. Similarly, ex vivo genetic knockout of Hdac9 in endothelial cells prevented EndMT and preserved a more endothelial-like phenotype. In vivo, atherosclerosis-prone mice with endothelial-specific Hdac9 knockout showed reduced EndMT and significantly reduced plaque area. Furthermore, these mice displayed a more favorable plaque phenotype, with reduced plaque lipid content and increased fibrous cap thickness. Together, these findings indicate that HDAC9 contributes to vascular pathology by promoting EndMT. Our study provides evidence for a pathological link among EndMT, HDAC9, and atherosclerosis and suggests that targeting of HDAC9 may be beneficial for plaque stabilization or slowing the progression of atherosclerotic disease.

Endothelial Lipase Modulates Paraoxonase 1 Content and Arylesterase Activity of HDL

Endothelial lipase (EL) is a strong modulator of the high-density lipoprotein (HDL) structure, composition, and function. Here, we examined the impact of EL on HDL paraoxonase 1 (PON1) content and arylesterase (AE) activity in vitro and in vivo. The incubation of HDL with EL-overexpressing HepG2 cells decreased HDL size, PON1 content, and AE activity. The EL modification of HDL did not diminish the capacity of HDL to associate with PON1 when EL-modified HDL was incubated with PON1-overexpressing cells. The overexpression of EL in mice significantly decreased HDL serum levels but unexpectedly increased HDL PON1 content and HDL AE activity. Enzymatically inactive EL had no effect on the PON1 content of HDL in mice. In healthy subjects, EL serum levels were not significantly correlated with HDL levels. However, HDL PON1 content was positively associated with EL serum levels. The EL-induced changes in the HDL-lipid composition were not linked to the HDL PON1 content. We conclude that primarily, the interaction of enzymatically active EL with HDL, rather than EL-induced alterations in HDL size and composition, causes PON1 displacement from HDL in vitro. In vivo, the EL-mediated reduction of HDL serum levels and the consequently increased PON1-to-HDL ratio in serum increase HDL PON1 content and AE activity in mice. In humans, additional mechanisms appear to underlie the association of EL serum levels and HDL PON1 content.

Developmental differences in focal adhesion kinase expression modulate pulmonary endothelial barrier function in response to inflammation

Compromised pulmonary endothelial cell (PEC) barrier function characterizes acute respiratory distress syndrome (ARDS), a cause of substantial morbidity and mortality. Survival from ARDS is greater in children compared with adults. Whether developmental differences intrinsic to PEC barrier function contribute to this survival advantage remains unknown. To test the hypothesis that PEC barrier function is more well-preserved in neonatal lungs compared with adult lungs in response to inflammation, we induced lung injury in neonatal and adult mice with systemic lipopolysaccharide (LPS). We assessed PEC barrier function in vivo and in vitro, evaluated changes in the expression of focal adhesion kinase 1 (FAK1) and phosphorylation in response to LPS, and determined the effect of FAK silencing and overexpression on PEC barrier function. We found that LPS induced a greater increase in lung permeability and PEC barrier disruption in the adult mice, despite similar degrees of inflammation and apoptosis. Although baseline expression was similar, LPS increased FAK1 expression in neonatal PEC but increased FAK1 phosphorylation and decreased FAK1 expression in adult PEC. Pharmacologic inhibition of FAK1 accentuated LPS-induced barrier disruption most in adult PEC. Finally, in response to LPS, FAK silencing markedly impaired neonatal PEC barrier function, whereas FAK overexpression preserved adult PEC barrier function. Thus, developmental differences in FAK expression during inflammatory injury serve to preserve neonatal pulmonary endothelial barrier function compared with that of adults and suggest that intrinsic differences in the immature versus pulmonary endothelium, especially relative to FAK1 phosphorylation, may contribute to the improved outcomes of children with ARDS.

Chronic Cigarette Smoking Impairs Erectile Function through Increased Oxidative Stress and Apoptosis, Decreased nNOS, Endothelial and Smooth Muscle Contents in a Rat Model

Cigarette use is an independent risk factor for the development of erectile dysfunction (ED). While the association between chronic smoking and ED is well established, the fundamental mechanism(s) of cigarette-related ED are incompletely understood, partly due to no reliable animal model of smoking-induced ED. The present study was designed to validate an in vivo rat model of chronic cigarette-induced ED. Forty 12-week old male Sprague-Dawley rats were divided into 4 groups. Ten rats served as control group and were exposed only to room air. The remaining 30 rats were passively exposed to cigarette smoke (CS) for 4 weeks (n = 10), 12 weeks (n = 10), and 24 weeks (n = 10). At the 24-week time point all rats were assessed with intracavernous pressure (ICP) during cavernous nerve electrostimulation. Blood and urine were collected to measure serum testosterone and oxidative stress, respectively. Corporal tissue was assessed by Western blot for neuronal nitric oxide synthase (nNOS). Penile tissues were subjected to immunohistochemistry for endothelial, smooth muscle, and apoptotic content. Mean arterial pressure (MAP) was significantly higher in 24-week cigarette exposed animals compared to the control animals. Mean ICP/MAP ratio and cavernosal smooth muscle/endothelial contents were significantly lower in the 12- and 24-week rats compared to control animals. Oxidative stress was significantly higher in the 24-week cigarette exposed group compared to control animals. Mean nNOS expression was significantly lower, and apoptotic index significantly higher, in CS-exposed animals compared to control animals. These findings indicate that the rat model exposure to CS increases apoptosis and oxidative stress and decreases nNOS, endothelial and smooth muscle contents, and ICP in a dose dependent fashion. The rat model is a useful tool for further study of the molecular and cellular mechanisms of CS-related ED.

Serum gamma - glutamyltransferase is associated with albuminuria: a population-based study

Background

Serum γ - glutamyltransferase (GGT) is implicated in the pathogenesis of endothelial dysfunction and atherosclerosis. Albuminuria is a marker of endothelial damage and correlated with structural and functional integrity of the vasculature. Our objective was to evaluate the association between serum GGT level and prevalence of albuminuria in a Chinese population.

Materials and Methods

We conducted a population-based cross-sectional study in 9,702 subjects aged 40 years or older. Increased urinary albumin excretion was defined according to the urinary albumin-to-creatinine ratio (ACR) ranges greater or equal than 30 mg/g. Low-grade albuminuria was defined according to the highest quartile of ACR in participants without increased urinary albumin excretion.

Results

The prevalence of low-grade albuminuria and increased urinary albumin excretion were respectively 23.4% and 6.6% in this population and gradually increased across the sex-specific serum GGT quartiles (all P for trend <0.05). In logistic regression analysis, compared with subjects in the lowest quartile of serum GGT level, the adjusted odds ratios (ORs) in the highest quartile was 1.22 [95% confidence interval (CI), 1.04–1.43] for low-grade albuminuria and 1.55 (95% CI, 1.18–2.04) for increased urinary albumin excretion. In subgroup analysis, significant relationship of serum GGT level with both low-grade albuminuria and increased urinary albumin excretion were detected in women, younger subjects, overweight subjects and in those with hypertension or glomerular filtration rate greater than 90 (all P <0.05).

Conclusion

Serum GGT level is associated with urinary albumin excretion in middle-aged and elderly Chinese.

Bicarbonate disruption of the pulmonary endothelial barrier via activation of endogenous soluble adenylyl cyclase, isoform 10

It is becoming increasingly apparent that cAMP signals within the pulmonary endothelium are highly compartmentalized, and this compartmentalization is critical to maintaining endothelial barrier integrity. Studies demonstrate that the exogenous soluble bacterial toxin, ExoY, and heterologous expression of the forskolin-stimulated soluble mammalian adenylyl cyclase (AC) chimera, sACI/II, elevate cytosolic cAMP and disrupt the pulmonary microvascular endothelial barrier. The barrier-disruptive effects of cytosolic cAMP generated by exogenous soluble ACs are in contrast to the barrier-protective effects of subplasma membrane cAMP generated by transmembrane AC, which strengthens endothelial barrier integrity. Endogenous soluble AC isoform 10 (AC10 or commonly known as sAC) lacks transmembrane domains and localizes within the cytosolic compartment. AC10 is uniquely activated by bicarbonate to generate cytosolic cAMP, yet its role in regulation of endothelial barrier integrity has not been addressed. Here we demonstrate that, within the pulmonary circulation, AC10 is expressed in pulmonary microvascular endothelial cells (PMVECs) and pulmonary artery endothelial cells (PAECs), yet expression in PAECs is lower. Furthermore, pulmonary endothelial cells selectively express bicarbonate cotransporters. While extracellular bicarbonate generates a phosphodiesterase 4-sensitive cAMP pool in PMVECs, no such cAMP response is detected in PAECs. Finally, addition of extracellular bicarbonate decreases resistance across the PMVEC monolayer and increases the filtration coefficient in the isolated perfused lung above osmolality controls. Collectively, these findings suggest that PMVECs have a bicarbonate-sensitive cytosolic cAMP pool that disrupts endothelial barrier integrity. These studies could provide an alternative mechanism for the controversial effects of bicarbonate correction of acidosis of acute respiratory distress syndrome patients.

Protective effects of GLP-1 on glomerular endothelium and its inhibition by PKCβ activation in diabetes

To characterize glucagon-like peptide (GLP)-1 signaling and its effect on renal endothelial dysfunction and glomerulopathy. We studied the expression and signaling of GLP-1 receptor (GLP-1R) on glomerular endothelial cells and the novel finding of protein kinase A-dependent phosphorylation of c-Raf at Ser259 and its inhibition of angiotensin II (Ang II) phospho-c-Raf(Ser338) and Erk1/2 phosphorylation. Mice overexpressing protein kinase C (PKC)β2 in endothelial cells (EC-PKCβ2Tg) were established. Ang II and GLP-1 actions in glomerular endothelial cells were analyzed with small interfering RNA of GLP-1R. PKCβ isoform activation induced by diabetes decreased GLP-1R expression and protective action on the renal endothelium by increasing its degradation via ubiquitination and enhancing phospho-c-Raf(Ser338) and Ang II activation of phospho-Erk1/2. EC-PKCβ2Tg mice exhibited decreased GLP-1R expression and increased phospho-c-Raf(Ser338), leading to enhanced effects of Ang II. Diabetic EC-PKCβ2Tg mice exhibited greater loss of endothelial GLP-1R expression and exendin-4-protective actions and exhibited more albuminuria and mesangial expansion than diabetic controls. These results showed that the renal protective effects of GLP-1 were mediated via the inhibition of Ang II actions on cRaf(Ser259) and diminished by diabetes because of PKCβ activation and the increased degradation of GLP-1R in the glomerular endothelial cells.

[Expression of matrix metalloproteinase-2 and tissue inhibitor type 2 in the lung in relation to the stage of experimental respiratory distress syndrome]

Acute respiratory distress syndrome (ARDS) was reproduced in rats by endotracheal administration of 45-55 thousand lysed rat neutrophils (RF patent). In each stage of the syndrome, immunohistochemistry was used to determine the expression of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor type 2 (MIMP-2) by lung cells. It was found that there was a substantial increment of MMP-2 expression in the fibroblasts, macrophages, endothelium, and fibroblasts in the exudative stage of ARDS. In its proliferative stage, the expression of MMP-2 remained high in the neutrophils and type II alveolocytes, by reducing in the macrophages, endothelium, and fibroblasts. In the fibrotic stage, it returned to the level of the control group only in the macrophages and type II alveolocytes, by remaining high in the other cells, as before. In progressive ARDS, the expression of TIMP-2 increased only in the neutrophils, endotheliocytes, and fibroblasts, remaining to be equal over all stages.

Stereological analysis of neuron, glial and endothelial cell numbers in the human amygdaloid complex

Cell number alterations in the amygdaloid complex (AC) might coincide with neurological and psychiatric pathologies with anxiety imbalances as well as with changes in brain functionality during aging. This stereological study focused on estimating, in samples from 7 control individuals aged 20 to 75 years old, the number and density of neurons, glia and endothelial cells in the entire AC and in its 5 nuclear groups (including the basolateral (BL), corticomedial and central groups), 5 nuclei and 13 nuclear subdivisions. The volume and total cell number in these territories were determined on Nissl-stained sections with the Cavalieri principle and the optical fractionator. The AC mean volume was 956 mm³ and mean cell numbers (x10⁶) were: 15.3 neurons, 60 glial cells and 16.8 endothelial cells. The numbers of endothelial cells and neurons were similar in each AC region and were one fourth the number of glial cells. Analysis of the influence of the individuals’ age at death on volume, cell number and density in each of these 24 AC regions suggested that aging does not affect regional size or the amount of glial cells, but that neuron and endothelial cell numbers respectively tended to decrease and increase in territories such as AC or BL. These accurate stereological measures of volume and total cell numbers and densities in the AC of control individuals could serve as appropriate reference values to evaluate subtle alterations in this structure in pathological conditions.

Peroxiredoxin 6 phosphorylation and subsequent phospholipase A2 activity are required for agonist-mediated activation of NADPH oxidase in mouse pulmonary microvascular endothelium and alveolar macrophages

Peroxiredoxin 6 (Prdx6), a bifunctional enzyme with glutathione peroxidase and phospholipase A2 (PLA(2)) activities, participates in the activation of NADPH oxidase 2 (NOX2) in neutrophils, but the mechanism for this effect is not known. We now demonstrate that Prdx6 is required for agonist-induced NOX2 activation in pulmonary microvascular endothelial cells (PMVEC) and that the effect requires the PLA(2) activity of Prdx6. Generation of reactive oxygen species (ROS) in response to angiotensin II (Ang II) or phorbol 12-myristate 13-acetate was markedly reduced in perfused lungs and isolated PMVEC from Prdx6 null mice. Rac1 and p47(phox), cytosolic components of NOX2, translocated to the endothelial cell membrane after Ang II treatment in wild-type but not Prdx6 null PMVEC. MJ33, an inhibitor of Prdx6 PLA(2) activity, blocked agonist-induced PLA(2) activity and ROS generation in PMVEC by >80%, whereas inhibitors of other PLA(2)s were ineffective. Transfection of Prx6 null cells with wild-type and C47S mutant Prdx6, but not with mutants of the PLA(2) active site (S32A, H26A, and D140A), "rescued" Ang II-induced PLA(2) activity and ROS generation. Ang II treatment of wild-type cells resulted in phosphorylation of Prdx6 and its subsequent translocation from the cytosol to the cell membrane. Phosphorylation as well as PLA(2) activity and ROS generation were markedly reduced by the MAPK inhibitor, U0126. Thus, agonist-induced MAPK activation leads to Prdx6 phosphorylation and translocation to the cell membrane, where its PLA(2) activity facilitates assembly of the NOX2 complex and activation of the oxidase.

Regulation of lymphocytes by nitric oxide

Shortly after the identification of nitric oxide (NO) as a product of macrophages, it was discovered that NO generated by inducible NO synthase (iNOS) inhibits the proliferation of T lymphocytes. Since then, it has become clear that iNOS activity also regulates the development, differentiation, and/or function of various types of T cells and B cells and also affects NK cells. The three key mechanisms underlying the iNOS-dependent immunoregulation are (a) the modulation of signaling processes by NO, (b) the depletion of arginine, and (c) the alteration of accessory cell functions. This chapter highlights important principles of iNOS-dependent immunoregulation of lymphocytes and also reviews more recent evidence for an effect of endothelial or neuronal NO synthase in lymphocytes.

FOXO3a governs early and late apoptotic endothelial programs during elevated glucose through mitochondrial and caspase signaling

Mechanisms that preserve endothelial cell (EC) integrity remain elusive, but are critical for new strategies directed against endocrine disorders such as diabetes mellitus (DM). Here we demonstrate in primary cerebral ECs with a clinically relevant model of elevated d-glucose that Akt1 and the post-translational modification and subcellular trafficking of the forkhead transcription factor FoxO3a are critical for early apoptotic membrane signaling and subsequent degradation of nuclear DNA. FoxO3a also directly governs apoptotic mitochondrial signal transduction pathways, since gene knockdown of FoxO3a prevents mitochondrial membrane depolarization as well as the release of cytochrome c. Control of this apoptotic cascade extends to the rapid and progressive activation of caspases. The presence of FoxO3a is necessary for cleaved (active) caspase 1 and 3 expression, since loss of FoxO3a abrogates the induction of caspase activity. Our work identifies Akt1, FoxO3a and closely aligned pathways as key therapeutic targets during impaired glucose tolerance and DM.

Endothelium-specific GTP cyclohydrolase I overexpression accelerates refractory wound healing by suppressing oxidative stress in diabetes

Refractory wound is a severe complication that leads to limb amputation in diabetes. Endothelial nitric oxide synthase (eNOS) plays a key role in normal wound repair but is uncoupled in streptozotocin (STZ)-induced type 1 diabetes because of reduced cofactor tetrahydrobiopterin (BH(4)). We tested the hypothesis that overexpression of GTP cyclohydrolase I (GTPCH I), the rate-limiting enzyme for de novo BH(4) synthesis, retards NOS uncoupling and accelerates wound healing in STZ mice. Blood glucose levels were significantly increased in both male endothelium-specific GTPCH I transgenic mice (Tg-GCH; via a tie-2 promoter) and wild-type (WT) littermates 5 days after STZ regimen. A full-thickness excisional wound was created on mouse dorsal skin by a 4-mm punch biopsy. Wound closure was delayed in STZ mice, which was rescued in STZ Tg-GCH mice. Cutaneous BH(4) level was significantly reduced in STZ mice vs. WT mice, which was maintained in STZ Tg-GCH mice. In STZ mice, constitutive NOS (cNOS) activity and nitrite levels were decreased compared with WT mice, paralleled by increased superoxide anion (O(2)(-)) level and inducible NOS (iNOS) activity. In STZ Tg-GCH mice, nitrite level and cNOS activity were potentiated and O(2)(-) level and iNOS activity were suppressed compared with STZ mice. Thus endothelium-specific BH(4) overexpression accelerates wound healing in type 1 diabetic mice by enhancing cNOS activity and suppressing oxidative stress.

Aberrant pre-receptor regulation of estrogen and progesterone action in endometrial cancer

Endometrial cancer is related to estrogen stimulation not opposed by progesterone. We have examined expression of the pre-receptor regulatory enzymes aromatase, 17beta-hydroxysteroid dehydrogenases (17beta-HSDs), 20alpha-hydroxysteroid dehydrogenases (20alpha-HSDs), sulfatase and sulfotransferase, and estrogen (ERs) and progesterone (PRs) receptors in samples of endometrial cancer and adjacent normal endometrium. No significant gene up-regulation was seen, although aromatase, AKR1C3, a 17beta-HSD and 20alpha-HSD, and AKR1C1, the major 20alpha-HSD, were up-regulated in 50% of samples. Significant down-regulation was seen for 17beta-HSD types 1 and 7, sulfotransferase, ERalpha, ERbeta, PR-AB. Western blotting revealed higher levels of AKR1C3 and PR-B and lower levels of ERalpha in cancerous endometrium, and immunohistochemistry confirmed expression of AKR1C3, PR-B and ERalpha at the cellular level. Up-regulation of aromatase in concert with AKR1C3 can lead to increased levels of estradiol, which acts via ERalpha. Up-regulation of AKR1C1 and AKR1C3 can result in lower levels of the protective progesterone, which acts mainly via PR-B.

Early iNOS impairment and late eNOS enhancement during reperfusion following 2.49 MHz continuous ultrasound exposure after ischemia

OBJECTIVE

Ischemia reperfusion (IR) injury, occurring during heart attacks, hemorrhagic shock, and bypass and transplant surgeries, impairs microcirculatory function and nitric oxide (NO) synthesis. We report the regulation of endothelial and inducible NO synthase (eNOS and iNOS) proteins as a consequence of the application of continuous mode diagnostic frequency ultrasound application following IR injury.

METHODS

Animals were assigned to one of five groups for microcirculatory assessment or Western blot analysis (WB) as follows: (1) IR+iNOS inhibition (1400W); and (2) IR+1400W+ultrasound for microcirculatory assessment, (3) Control; (4) IR; and (5) IR+ultrasound for WB. Functional capillary density and microvascular diameter, flow velocity, and flow were monitored for microcirculatory assessment. Skin tissue samples were harvested for WB. 2.49MHz continuous ultrasound was used for application.

RESULTS

Both the inhibition of iNOS alone and iNOS inhibition with ultrasound irradiation positively influenced the microcirculation of observed animals relative to baseline values. Ultrasound exposure resulted in a significant production of eNOS protein in skin tissue harvested 24h into reperfusion (p<0.01). iNOS levels from the same tissue of ultrasound exposed animals were found to be significantly decreased 0.5h into reperfusion (p<0.05).

CONCLUSION

Protection from lasting IR injury effects in the microcirculation, with continuous mode diagnostic frequency ultrasound, results from augmented eNOS protein levels during late reperfusion. Ultrasound inhibited iNOS protein production during early reperfusion may also confer protection from IR injury.

Asymmetric dimethylarginine (ADMA) and other endogenous nitric oxide synthase (NOS) inhibitors as an important cause of vascular insulin resistance

Asymmetric dimethylarginine (ADMA) and NG-monomethyl- L-arginine ( L-NMMA) are important endogenous endothelial nitric oxide synthase (eNOS) inhibitors. Studies have shown that patients with insulin resistance have elevated plasma levels of ADMA. Moreover, ADMA levels have a prognostic value on long-term outcome of patients with coronary artery disease. Insulin resistance, a disorder associated to inadequate biological responsiveness to the actions of exogenous or endogenous insulin, is a metabolic condition, which exists in patients with cardiovascular diseases. This disorder affects the functional balance of vascular endothelium via changes of nitric oxide (NO) metabolism. Nitric oxide is produced in endothelial cells from the substrate L-arginine via eNOS. Elevated ADMA levels cause eNOS uncoupling, a mechanism which leads to decreased NO bioavailability and increased production of hydrogen peroxide. According to clinical studies, the administration of L-arginine to patients with high ADMA levels improves NO synthesis by antagonizing the deleterious effect of ADMA on eNOS function, although in specific populations such as diabetes mellitus, this might even been harmful. More studies are required in order to certify the role of NOS inhibitors in insulin resistance and endothelial dysfunction. It is still difficult to say whether increased ADMA levels in certain populations is only a reason or the result of the molecular alterations, which take place in vascular disease states.

Pulmonary angiotensin-converting enzyme and its inhibition: a historical survey

Angiotensin-converting enzyme, the peptidase hydrolysing angiotensin I to angiotensin II and first discovered in plasma, has been demonstrated in lung tissue on the luminal surface of endothelial cells lining pulmonary blood vessels. Because converting enzyme is the final activating step in the renin-angiotensin system its inhibition prevents the pressor and other effects of increased renin secretion. Lung converting enzyme activity is inhibited specifically by a nonapeptide (BPP9a:SQ 20 881) contained in Bothrops jararaca venom. This peptide inhibits the pressor effects of injected angiotensin I in humans and lowers blood pressure in patients with high-renin hypertension. Recently a synthetic inhibitor, captopril, was devised which is effective, given orally, in reducing the blood pressure of high-renin hypertensives and of a proportion of hypertensives with normal renin levels. The latter finding suggests that blood pressure may be maintained by renin-dependent mechanisms without increased renin secretion.

Review article: steroid hormones and uterine vascular adaptation to pregnancy

Pregnancy is a physiological state that involves a significant decrease in uterine vascular tone and an increase in uterine blood flow, which is mediated in part by steroid hormones, including estrogen, progesterone, and cortisol. Previous studies have demonstrated the involvement of these hormones in the regulation of uterine artery contractility through signaling pathways specific to the endothelium and the vascular smooth muscle. Alterations in endothelial nitric oxide synthase expression and activity, nitric oxide production, and expression of enzymes involved in PGI(2) production contribute to the uterine artery endothelium-specific responses. Steroid hormones also have an effect on calcium-activated potassium channel activity, PKC signaling pathway and myogenic tone, and alterations in pharmacomechanical coupling in the uterine artery smooth muscle. This review addresses current understanding of the molecular mechanisms by which steroid hormones including estrogen, progesterone, and cortisol modulate uterine artery contractility to alter uterine blood flow during pregnancy with an emphasis on the pregnant ewe model.

Effects of selective cyclooxygenase isoform inhibition on systemic prostacyclin synthesis and on platelet function at rest and after exercise in healthy volunteers

To test the hypothesis that selective inhibition of cyclooxygenase (COX)-2 would result in exercise-induced platelet activation by causing a shift in the endogenous thromboxane (TX)/prostacyclin balance, a double blind, randomized study comparing aspirin (300 mg/d) with rofecoxib (25 mg/d) (cross-over design, 14 days washout between treatments) in n = 10 trained healthy volunteers was carried out. Physical exercise resulted only in a minor platelet activation, as reflected by the expression of basal or ADP-stimulated platelet activation markers or basal plasma concentrations of TXB(2). Aspirin significantly reduced TXB(2) in plasma while rofecoxib significantly increased TXB(2) in urine. Although no increase in systemic prostacyclin concentration was observed, there was a significant exercise-related increase in both platelet cAMP and cGMP without any drug-related effects. It is concluded that, in trained healthy volunteers, selective inhibition of COX-1 (aspirin) or COX-2 (rofecoxib) does not affect systemic prostacyclin synthesis after physical exercise. However, our data do not exclude the possibility that in subjects at risk for atherothrombotic complications (e.g. patients with advanced atherosclerotic disease) COX-2 inhibitors may result in platelet activation by inhibiting endothelial prostacyclin formation.

Reductase domain of Drosophila melanogaster nitric-oxide synthase: redox transformations, regulation, and similarity to mammalian homologues

The nitric oxide synthase of Drosophila melanogaster (dNOS) participates in essential developmental and behavioral aspects of the fruit fly, but little is known about dNOS catalysis and regulation. To address this, we expressed a construct comprising the dNOS reductase domain and its adjacent calmodulin (CaM) binding site (dNOSr) and characterized the protein regarding its catalytic, kinetic, and regulatory properties. The Ca2+ concentration required for CaM binding to dNOSr was between that of the mammalian endothelial and neuronal NOS enzymes. CaM binding caused the cytochrome c reductase activity of dNOSr to increase 4 times and achieve an activity comparable to that of mammalian neuronal NOS. This change was associated with decreased shielding of the FMN cofactor from solvent and an increase in the rate of NADPH-dependent flavin reduction. Flavin reduction in dNOSr was relatively slow following the initial 2-electron reduction, suggesting a slow inter-flavin electron transfer, and no charge-transfer complex was observed between bound NADP+ and reduced FAD during the process. We conclude that dNOSr catalysis and regulation is most similar to the mammalian neuronal NOS reductase domain, although differences exist in their flavin reduction behaviors. The apparent conservation between the fruit fly and mammalian enzymes is consistent with dNOS operating in various signal cascades that involve NO.

Angiotensin-converting enzyme (ACE) inhibitors have different selectivity for bradykinin binding sites of human somatic ACE

The angiotensin-converting enzyme (ACE) has two natural substrates and two catalytic domains: one cleaving angiotensin I and one inactivating bradykinin. The aim of this study was to investigate the comparative binding affinity of ACE inhibitors for the two binding sites of human endothelial ACE. In vitro binding assays were performed to test the ability of bradykinin, angiotensin I, or various ACE inhibitors (enalaprilat, perindoprilat, quinaprilat, ramiprilat, and trandolaprilat) to displace a saturating concentration of [(125)I]351A, a radiolabeled lisinopril analogue, from ACE binding sites. The calculated IC(50) values for the ACE inhibitors were in the nanomolar range, while those for the natural substrates were in the micromolar range. The bradykinin/angiotensin I selectivity ratios calculated from double displacement experiments were: perindoprilat, 1.44; ramiprilat, 1.16; quinaprilat, 1.09; trandolaprilat, 1.08; enalaprilat, 1.00. The ACE inhibitors generally had higher affinity for the bradykinin than the angiotensin I binding sites, supporting the idea that these agents are primarily inhibitors of bradykinin degradation, and secondarily inhibitors of angiotensin II production. Perindoprilat had the highest selectivity for bradykinin versus angiotensin I binding sites, and enalaprilat has the lowest. These results indicate that there are differences in the affinity of ACE inhibitors toward sites for bradykinin degradation, which could lead to differences in efficacy in cardiovascular disease.

Endothelial iNOS versus platelet iNOS: Responsibility for the platelet/leukocyte endothelial cell interaction in murine antigen induced arthritis in vivo

OBJECTIVE

Since an increase of platelet-endothelial cell interactions has been observed in mice with Antigen- induced-Arthritis (AiA) as well as an increase of NO expression, the aim of our study was to investigate in vivo the influence of NO, especially the platelet and endothelial inducible NO Synthase, on the platelet- and leukocyte endothelial cell interaction.

MATERIAL AND METHODS

C57/Bl6 mice and iNOS deficient mice were disposed in 6 groups (each=7). After induction of AiA, rolling and adherent fluorescence labelled platelets and leukocytes were investigated by intravital microscopy (IVM) on day 8 after AiA. Rank SUM Test and ANOVA on ranks have been performed regarding the data.

RESULTS

All arthritic mice presented an increase in platelet and leukocyte interaction with the endothelium compared to control groups. The arthritic iNOS deficient mice showed a more intense interaction of platelets and leukocytes with the endothelium in comparison with the wild-type arthritic mice. The group using arthritic wild-type recipient and iNOS deficient donor mice showed an increase in cell-interactions, leading to an endothelial effect, compared to the group using iNOS deficient arthritic recipient and wild-type donor mice.

CONCLUSION

The IVM data lead to an anti-inflammatory effect of NO, since NO followed an increase in platelet- and leukocyte- endothelial cell interaction in iNOS deficient mice with AiA. In addition, we have shown for the first time in vivo that platelet NO produced by iNOS seems to have a minor influence on the leukocyte induced tissue damage in contrast to endothelial iNOS. Therefore, selective platelet inhibition would not interfere with the protective effect of NO.

Angiotensin II up-regulates soluble epoxide hydrolase in vascular endothelium in vitro and in vivo

Epoxyeicosatrienoic acids (EETs), as metabolites of arachidonic acid, may function as antihypertensive and antiatherosclerotic mediators for vasculature. EETs are degraded by soluble epoxide hydrolase (sEH). Pharmacological inhibition and genetic ablation of sEH have been shown to increase the level of EETs, and treating angiotensin II (Ang II)-infused hypertension rats with sEH-selective inhibitors increased the levels of EETs, with attendant decrease in systolic blood pressure. To elucidate the mechanisms by which Ang II regulates sEH expression, we treated human umbilical vein endothelial cells (ECs) and bovine aortic ECs with Ang II and found increased sEH expression at both the mRNA and protein levels. Transient transfection assays showed that the activity of the human sEH promoter was increased in ECs in response to Ang II. Further analysis of the promoter region of the sEH gene demonstrated that treatment with Ang II, like overexpression of c-Jun/c-Fos, activates the sEH promoter through an AP-1-binding motif. The binding of c-Jun to the AP-1 site of the sEH promoter was confirmed by chromatin immunoprecipitation assays. In contrast, adenovirus overexpression of the dominant-negative mutant of c-Jun significantly attenuated the effects of Ang II on sEH induction. An elevated level of sEH was found in the aortic intima of both spontaneously hypertensive rats and Ang II-infused Wistar rats. Blocking Ang II binding to Ang II receptor 1 by losartan abolished the sEH induction. Thus, AP-1 activation is involved in the transcriptional up-regulation of sEH by Ang II in ECs, which may contribute to Ang II-induced hypertension.

Immunotargeting of catalase to lung endothelium via anti-angiotensin-converting enzyme antibodies attenuates ischemia-reperfusion injury of the lung in vivo

Limitation of reactive oxygen species-mediated ischemia-reperfusion (I/R) injury of the lung by vascular immunotargeting of antioxidative enzymes has the potential to become a promising modality for extension of the viability of banked transplantation tissue. The preferential expression of angiotensin-converting enzyme (ACE) in pulmonary capillaries makes it an ideal target for therapy directed toward the pulmonary endothelium. Conjugates of ACE monoclonal antibody (MAb) 9B9 with catalase (9B9-CAT) have been evaluated in vivo for limitation of lung I/R injury in rats. Ischemia of the right lung was induced for 60 min followed by 120 min of reperfusion. Sham-operated animals (sham, n = 6) were compared with ischemia-reperfused untreated animals (I/R, n = 6), I/R animals treated with biotinylated catalase (CAT, n = 6), and I/R rats treated with the conjugates (9B9-CAT, n = 6). The 9B9-CAT accumulation in the pulmonary endothelium of injured lungs was elucidated immunohistochemically. Arterial oxygenation during reperfusion was significantly higher in 9B9-CAT (221 +/- 36 mmHg) and sham (215 +/- 16 mmHg; P < 0.001 for both) compared with I/R (110 +/- 10 mmHg) and CAT (114 +/- 30 mmHg). Wet-dry weight ratio of I/R (6.78 +/- 0.94%) and CAT (6.54 +/- 0.87%) was significantly higher than of sham (4.85 +/- 0.29%; P < 0.05), which did not differ from 9B9-CAT (5.58 +/- 0.80%). The significantly lower degree of lung injury in 9B9-CAT-treated animals compared with I/R rats was also shown by decreased serum levels of endothelin-1 (sham, 18 +/- 9 fmol/mg; I/R, 42 +/- 12 fmol/mg; CAT, 36 +/- 11 fmol/mg; 9B9-CAT, 26 +/- 9 fmol/mg; P < 0.01) and mRNA for inducible nitric oxide synthase (iNOS) [iNOS-GAPDH ratio: sham, 0.15 +/- 0.06 arbitrary units (a.u.); I/R, 0.33 +/- 0.08 a.u.; CAT, 0.26 +/- 0.05 a.u.; 9B9-CAT, 0.14 +/- 0.04 a.u.; P < 0.001]. These results validate immunotargeting by anti-ACE conjugates as a prospective and specific strategy to augment antioxidative defenses of the pulmonary endothelium in vivo.

Transforming growth factor-beta, estrogen, and progesterone converge on the regulation of p27Kip1 in the normal and malignant endometrium

Hormones and growth factors regulate endometrial cell growth. Disrupted transforming growth factor-beta (TGF-beta) signaling in primary endometrial carcinoma (ECA) cells leads to loss of TGF-beta-mediated growth inhibition, which we show herein results in lack of up-regulation of the cyclin-dependent kinase inhibitor p27(Kip1) (p27) to arrest cells in G(1) phase of the cell cycle. Conversely, in normal primary endometrial epithelial cells (EECs), TGF-beta induces a dose-dependent increase in p27 protein, with a total 3.6-fold maximal increase at 100 pmol/L TGF-beta, which was 2-fold higher in the nuclear fraction; mRNA levels were unaffected. In addition, ECA tissue lysates show a high rate of ubiquitin-mediated degradation of p27 compared with normal secretory-phase endometrial tissue (SE) such that 4% and 89% of recombinant p27 added to the lysates remains after 3 and 20 h, respectively. These results are reflected in vivo as ECA tissue lacks p27 compared with high expression of p27 in SE (P < or = 0.001). Furthermore, we show that estrogen treatment of EECs causes mitogen-activated protein kinase-driven proteasomal degradation of p27 whereas progesterone induces a marked increase in p27 in both normal EECs and ECA cells. Therefore, these data suggest that TGF-beta induces accumulation of p27 for normal growth regulation of EECs. However, in ECA, in addition to enhanced proteasomal degradation of p27, TGF-beta cannot induce p27 levels due to dysregulated TGF-beta signaling, thereby causing 17beta-estradiol-driven p27 degradation to proceed unchecked for cell cycle progression. Thus, p27 may be a central target for growth regulation of normal endometrium and in the pathogenesis of ECA.

Promoter polymorphism (-786t>C) in the endothelial nitric oxide synthase gene is associated with risk of sporadic breast cancer in non-Hispanic white women age younger than 55 years

BACKGROUND

Nitric oxide (NO) is constitutively synthesized in the endothelium by endothelial nitric oxide synthase (eNOS) and acts as a pleiotropic regulator involved in carcinogenesis. Most breast cancers develop from mammary epithelial cells; therefore, NO may play a role in their development. It was hypothesized that eNOS polymorphisms are associated with risk of breast cancer.

METHODS

In the current hospital-based case-control study of 421 non-Hispanic white women with sporadic breast cancer and 423 frequency-matched control subjects, we genotyped 3 polymorphisms of eNOS (i.e., -786T>C, the 27-base pair [bp] variable number of tandem repeats [VNTR] in intron 4, and 894G>T [Glu298Asp]) and assessed their associations with risk of breast cancer.

RESULTS

It was found that, compared with -786TT, the -786C variant genotypes were associated with a significantly increased risk of breast cancer in an allele dose-dependent manner (adjusted odds ratio [OR], 1.33 [95% confidence interval (95% CI)], 0.99-1.77 for -786TC; and OR, 1.79 [95% CI, 1.11-2.87] for -786CC; P(trend) = .007), but 27-bp VNTR and 894G>T genotypes were not. Stratification analysis demonstrated that the risk associated with -786C variant genotypes (-786TC/CC) was more pronounced in smokers and in those 50 years or older (OR, 1.82 [95% CI, 1.19-2.80] and OR, 2.08 [95% CI, 1.25-3.45], respectively), and in the estrogen and progesterone receptor-negative cases (OR, 1.70 [95% CI, 1.10-2.62] and OR, 1.57 [95% CI, 1.07-2.32], respectively). Furthermore, the C4G haplotype derived from the observed genotypes was also associated with a significantly increased risk of breast cancer (OR, 2.16; 95% CI, 1.07-4.36).

CONCLUSIONS

The results suggest that eNOS polymorphisms (especially -786T>C) may play a role in the development of sporadic breast cancer.

Arginine uptake is attenuated, through post-translational regulation of cationic amino acid transporter-1, in hyperlipidemic rats

Endothelial cell dysfunction (ECD) is a common feature of hypercholesterolemia. Defective nitric oxide (NO) generation due to decreased endothelial nitric oxide synthase (eNOS) activity is a crucial parameter characterizing ECD. L-arginine is the sole precursor for NO biosynthesis. Among several transporters that mediate L-arginine uptake, cationic amino acid transporter-1 (CAT-1) acts as a specific arginine transporter for eNOS. Our hypothesis implies that CAT-1 is a major determinant of eNOS activity in hypercholesterolemia. We studied aortic arginine uptake, CAT-1 and CAT-2 mRNA expression, and CAT-1, and PKC alpha protein in: (a) control, untreated animals (CTL), (b) rats fed with 4% cholesterol+1% cholate and 2% corn oil for 6 weeks (CHOL) and (c) rats with hypercholesterolemia treated orally with either atorvastatin (CHOL+ATORVA, 20mg/kg BW/day) or arginine 1% (CHOL+ARG) in the drinking water (modalities which have been shown to enhance CAT-1 activity and improve endothelial function). Serum cholesterol levels significantly increased in cholesterol fed animals, an increase which was blocked by atorvastatin (CTL: 66.8+/-15, CHOL: 133.9+/-22, CHOL+ARG: 128.2+/-20, CHOL+ATORVA: 77+/-15 mg/dl). Arginine transport was significantly decreased in CHOL. Treatment with neither arginine nor atorvastatin had an effect. Using RT-PCR, we found no change in aortic CAT-1 and CAT-2 mRNA expression in CHOL as well as following arginine or atorvastatin administration. The abundance of CAT-1 protein was significantly augmented in cholesterol fed rats and was not affected by arginine or atorvastatin. PKC alpha protein content, which was previously shown to regulate CAT-1 activity, increased significantly in CHOL and was neither affected by atorvastatin nor arginine. In conclusion, aortic arginine uptake is attenuated in hypercholesterolemia, through post-translational modulation of CAT-1 protein, possibly via upregulation of PKC alpha.

Insertion/deletion polymorphism on ACE gene is associated with endothelial dysfunction in young patients with hypertension

Endothelial dysfunction, insulin resistance (IR) and genetic predispositions are important risk factors of hypertension. Aim of our study was to test the hypothesis, whether insertion/deletion (I/D) polymorphism on the angiotensin converting enzyme (ACE) gene and M235T polymorphism on angiotesinogen gene (AGT) correlates with parameters of insulin sensitivity and plasminogen activator inhibitor (PAI-1) levels in newly diagnosed hypertensive patients as compared with normotensive controls. Blood pressure (BP), fasting plasma glucose, insulin, epinephrine, norepinephrine and PAI-1 concentrations were determined in 30 male patients with hypertension grade 1 (HT) and in 31 matched healthy subjects (NT). Insulin resistance was estimated using IR HOMA formula. Patients with HT had increased levels of PAI-1, norepinephrine, fasting plasma insulin levels, IR HOMA (p<0.001) compared to controls. Subjects (HT and NT) with DD and ID genotype had a significantly higher systolic BP (p<0.05) and PAI-1 compared to those with II genotype. Homozygous subjects 235T had a higher systolic BP and higher levels of epinephrine and norepinephrine than heterozygous or homozygous M235 (p<0.05). In conclusion, no association was found between M235T polymorphism and insulin resistance or PAI-1 levels, but results indicate relationship between I/D polymorphism of the ACE gene and plasma PAI-1 levels in the early stage of hypertension.

Cyclooxygenase 2 expression in vessels and nerves in reversal reaction leprosy

Tissue expression of cyclooxygenase (COX)2, an inducible enzyme synthesizing eicosanoids in inflammation, was studied in reversal reaction (RR) leprosy in comparison with nonreactionary leprosy. COX2 was consistently expressed in cells of the mononuclear-macrophage lineage across the leprosy spectrum. Only in RR, the following two additional sites showed COX2 expression in the dermis and subcutis: 1) microvessels and 2) nerve bundles and isolated nerve fibers. The same sites also express vascular endothelial growth factor (VEGF). This is in keeping with experimental models relating VEGF to COX2 expression, with VEGF enhancing prostaglandin production through COX2 stimulation and prostaglandin synthase expression. We postulate that selective COX2 inhibitors, which are currently used in several inflammatory conditions, could be considered for RR treatment to reduce acute symptoms caused by tissue edema and possibly prevent long-term nerve damage, the main complication of RR.

Role of apoptosis in the pathogenesis of COPD and pulmonary emphysema

Chronic obstructive pulmonary disease (COPD) is characterised by chronic inflammation of the airways and progressive destruction of lung parenchyma, a process that in most cases is initiated by cigarette smoking. Several mechanisms are involved in the development of the disease: influx of inflammatory cells into the lung (leading to chronic inflammation of the airways), imbalance between proteolytic and anti-proteolytic activity (resulting in the destruction of healthy lung tissue) and oxidative stress. Recently, an increasing number of data suggest a fourth important mechanism involved in the development of COPD: apoptosis of structural cells in the lung might possibly be an important upstream event in the pathogenesis of COPD. There is an increase in apoptotic alveolar epithelial and endothelial cells in the lungs of COPD patients. Since this is not counterbalanced by an increase in proliferation of these structural cells, the net result is destruction of lung tissue and the development of emphysema. Data from animal models suggest a role for Vascular Endothelial Growth Factor (VEGF) in the induction of apoptosis of structural cells in the lung. Other mediators of apoptosis, such as caspase-3 and ceramide, could be interesting targets to prevent apoptosis and the development of emphysema. In this review, recent data on the role of apoptosis in COPD from both animal models as well as from studies on human subjects will be discussed. The aim is to provide an up to date summary on the increasing knowledge on the role of apoptosis in COPD and pulmonary emphysema.

Gene transfer to trabecular meshwork endothelium via direct injection into the Schlemm canal and in vivo toxicity study

PURPOSE

Our aim was to investigate the efficiency of adenoviral gene transfer via direct injection into the Schlemm canal ex vivo in human donor eyes and to examine the effect of human MMP-3 transgene expression in a rat model in vivo.

METHODS

A viscocanalostomy-like operation was performed and adenoviral vector encoding for MMP-3 and green fluorescent protein was injected into human Schlemm canal or rat anterior chamber.

RESULTS

Transgene expression was high in trabecular meshwork endothelium in human donor eyes. In vivo, adenovirus caused dose-dependent inflammation.

CONCLUSIONS

Direct injection of adenoviral vectors into the Schlemm canal has potential in glaucoma treatment.

Association analysis of genes in the renin-angiotensin system with subclinical cardiovascular disease in families with Type 2 diabetes mellitus: the Diabetes Heart Study

AIMS

Cardiovascular disease (CVD) is a major complication of Type 2 diabetes mellitus. The renin-angiotensin system (RAS) and nitric oxide production are both important regulators of vascular function and blood pressure. Genes encoding proteins involved in these pathways are candidates for a contribution to CVD in diabetic patients. We have investigated variants of the angiotensinogen (AGT), angiotensin converting enzyme (ACE), angiotensin type 1 receptor (AT1R) and endothelial nitric oxide synthase (NOS3) genes for association with subclinical measures of CVD in families with Type 2 diabetes mellitus (T2DM).

METHODS

Atherosclerosis was measured by carotid intima-media thickness and calcification of the carotid and coronary arteries in 620 European Americans and 117 African Americans in the Diabetes Heart Study. Because of the role of these systems in blood pressure regulation, blood pressure was also investigated.

RESULTS

Compelling evidence of association was not detected with any of the SNPs with any outcome measures after adjustments for covariates despite sufficient power to detect relatively small differences in traits for specific genotype combinations.

CONCLUSIONS

Genetic variation of the RAS and NOS3 genes do not appear to strongly influence subclinical cardiovascular disease or blood pressure in this diabetic population.

Cyclooxygenases Regulation by Estradiol on Endothelium

Estrogen and hormone replacement therapies are being tested to prevent the incidence of cardiovascular disease in postmenopausal women. In spite of the evidence from several epidemiological studies suggesting that estrogens protect against atherosclerosis and associated diseases, controversy exists. Moreover, it is important to develop synthetic compounds that achieve the beneficial effects of estrogens on the cardiovascular system while minimizing such undesirable effects on other tissues as the increased risk of endometrial and breast cancer. Some drugs that modulate estrogen function in a tissue-specific manner (Selective Estrogen Receptor Modulators; SERMs) have been discovered and are currently being used in clinical practice. An example of these is raloxifene. Clinical and experimental data support the consideration of endothelium as a target for estradiol and other sexual hormones. Among other actions, estradiol has been implicated in the control of prostacyclin production through cyclooxygenases (COX) regulation in endothelial cells. Prostacyclins are powerful vasodilators and potent inhibitors of platelet aggregation which are produced from free arachidonic acid through the catalytic activity of two COX: COX-1 and COX-2. Together, these COX represent the main control mechanism for prostacyclin production. Although several non-specific COX inhibitors have been available for decades (aspirin, indomethacin, ibuprofen), COX-2 selective inhibitors have been commercialized only within the last few years, thus making it possible to increase the study and treatment of different disorders. This review will discuss clinical and experimental data that document the endothelial effects of estradiol and SERMs on prostacyclin production and COX regulation, their vascular consequences, and their possible interactions with COX inhibitors.

Penile erection requires association of soluble guanylyl cyclase with endothelial caveolin-1 in rat corpus cavernosum

Erectile dysfunction is caused by a variety of pathogenic factors, particularly impaired formation and action of nitric oxide (NO). NO released from nerve endings and corpus cavernosum endothelial cells plays a crucial role in initiating and maintaining increased intracavernous pressure, penile vasodilatation, and penile erection. Classically, these effects are dependent on cGMP synthesized during activation of soluble guanylyl cyclase (sGC) by NO in smooth muscle cells. The enzyme NO synthase in endothelial cells has been localized to caveolae, small invaginations of the plasma membrane rich in cholesterol. Membrane cholesterol depletion impairs acetylcholine-induced relaxation in arteries attributed to an alteration in caveolar structure. It has been shown that sGC may be activated in endothelial caveolae contributing to vasodilation. We hypothesized that caveolae are the platform for sGC/cGMP signaling in cavernosum smooth muscle eliciting erection. Methyl-beta-cyclodextrin, a pharmacological tool to deplete membrane cholesterol and disassemble caveolae, impaired rat erectile responses in vivo and cavernosum smooth muscle relaxation induced by the NO donor sodium nitroprusside and the sGC activator 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole in vitro. Methyl-beta-cyclodextrin had no effect on cavernosum smooth muscle relaxation induced by NO released upon nerve stimulation or by exogenous cGMP. Furthermore, sGC and caveolin-1, the major coat protein of caveolae, were colocalized in rat corpus cavernosum sinusoidal endothelium. Electron microscopy indicated caveolae disruption in corpus cavernosum treated with methyl-beta-cyclodextrin. In summary, our results provide evidence of compartmentalization of sGC in the caveolae of cavernosal endothelial cells contributing to NO signaling mediating smooth muscle relaxation and erection.

Genetics of progressive renal failure in diabetic kidney disease

Diabetic kidney disease is a microvascular complication that is observed in a minority of patients with long-standing hyperglycemia. Diabetic nephropathy (DN) is associated with shortened patient survival, severe morbidity, and increased health care costs. Unfortunately, the incidence rates of DN continue to increase in Western societies, and DN is now the most common reported cause of end-stage renal disease in developed nations. DN results from a complex interplay between inherited and environmental factors. This article reviews the data that support an inherited basis for susceptibility to DN by summarizing familial aggregation studies, genome-wide linkage, and population-based association analyses in diabetic and nondiabetic kidney disease. Recent evidence linking genes involved in the regulation of endothelial function with genetic predisposition to albuminuria is presented. The integration of carefully designed genetic linkage and association studies with gene expression experiments in human and animal models of diabetic kidney disease appear to offer great promise for detecting the molecular mechanisms underlying susceptibility to DN.

Endothelial and lipoprotein lipases in human and mouse placenta

Placenta expresses various lipase activities. However, a detailed characterization of the involved genes and proteins is lacking. In this study, we compared the expression of endothelial lipase (EL) and LPL in human term placenta. When placental protein extracts were separated by heparin-Sepharose affinity chromatography, the EL protein eluted as a single peak without detectable phospholipid or triglyceride (TG) lipase activity. The major portion of LPL protein eluted slightly after EL. This peak also had no lipase activity and most likely contained monomeric LPL. Fractions eluting at a higher NaCl concentration contained small amounts of LPL protein (most likely dimeric LPL) and had substantial TG lipase activity. In situ hybridization studies showed EL mRNA expression in syncytiotrophoblasts and endothelial cells and LPL mRNA in syncytiotrophoblasts. In contrast, immunohistochemistry showed EL and LPL protein associated with both cell types. In mouse placentas, lack of LPL expression resulted in increased EL mRNA expression. These results suggest that the cellular expression of EL and LPL in human placenta is different. Nevertheless, the two lipases might have overlapping functions in the mouse placenta. Our data also suggest that the major portions of both proteins are stored in an inactive form in human term placenta.

Cyclophilin A may contribute to the inflammatory processes in rheumatoid arthritis through induction of matrix degrading enzymes and inflammatory cytokines from macrophages

Cyclophilin A (CypA) levels increase in the sera and synovial fluids of rheumatoid arthritis (RA) patients, but the cell types expressing CypA and the function of CypA in the pathogenesis of RA are not known yet. Immunohistochemistry analyses revealed high level CypA staining in the macrophages in the lining layers of human RA and osteoarthritis synovium. Low level CypA staining was also detected in endothelial cells, lymphocytes, and smooth muscle cells in RA synovium. Further investigation of the CypA function using monocyte/macrophage cell lines revealed that CypA induced expression of cytokine/chemokines such as TNF-alpha, IL-8, MCP-1, and IL-1beta and matrix metalloproteinase (MMP)-9 through a pathway that is dependent on NFkappaB activation. Furthermore, MMP-9 staining pattern overlapped with that of CypA in both RA and OA synovium. Our data suggest that CypA may stimulate macrophages to degrade joint cartilage via MMP-9 expression and promote inflammation via pro-inflammatory cytokine secretion.

Involvement of calpain-calpastatin in cigarette smoke-induced inhibition of lung endothelial nitric oxide synthase

We reported that cigarette smoke extract (CSE) causes decreases in the activity and expression of endothelial nitric oxide synthase (eNOS) and calpain activity in pulmonary artery endothelial cells (PAECs). Calpains are a family of calcium-dependent endopeptidases, and their specific endogenous inhibitor is calpastatin. In this study, we evaluated the role of calpain-calpastatin in CSE-induced decrease in eNOS gene expression. PAEC were incubated with 5-10% CSE for 2-24 h. eNOS gene transcription rate, eNOS messenger ribonucleic acid (mRNA) half-life, and the activity and protein contents of calpain and calpastatin were measured. Incubation of PAEC with CSE caused significant decreases in eNOS gene transcription and calpain activity and an increase in calpastatin protein content. eNOS mRNA half-life was not significantly altered by CSE. To investigate whether CSE-induced inhibition of eNOS gene expression is caused by decreased calpain activity due to an increase in calpastatin protein content, we cloned calpastatin gene from PAEC and constructed adenovirus vectors containing calpastatin. Overexpression of calpastatin mimics the inhibitory effects of CSE on calpain activity and on the activity, protein, and mRNA of eNOS. The cell-permeable calpain inhibitor, calpastatin peptide, inhibits acetylcholine-induced endothelium-dependent relaxation of the pulmonary artery. Incubation of PAEC with an antisense oligodeoxyribonucleotide of calpastatin prevented CSE-induced increases in calpastatin protein and CSE-induced decreases in calpain activity, eNOS gene transcription, activity and protein content of eNOS, and NO release. These results indicate that CSE-induced inhibition of eNOS expression in PAEC is caused by calpain inhibition due to an increase in calpastatin protein content.

Rho GTPases and leucocyte-induced endothelial remodelling

Leucocytes in the bloodstream respond rapidly to inflammatory signals by crossing the blood vessel wall and entering the tissues. This process involves adhesion to, and subsequent transmigration across, the endothelium, mediated by a cascade of interactions between adhesion molecules and stimulation of intracellular signalling pathways in both leucocytes and endothelial cells. This leads to changes in endothelial cell morphology that assist leucocyte extravasation, including endothelial cell contraction, intercellular junction disruption, increased permeability, remodelling of the endothelial apical surface and alterations in vesicle trafficking. Rho GTPases play a central role in many of the endothelial responses to leucocyte interaction. In this review, we discuss recent findings on leucocyte-induced alterations to endothelial cells, and the roles of Rho GTPases in these responses.

The inositol trisphosphate pathway mediates platelet-activating-factor-induced pulmonary oedema

Platelet-activating factor (PAF) is a pro-inflammatory lipid mediator that increases vascular permeability by simultaneous activation of two pathways, one dependent on the cyclooxygenase metabolite prostaglandin E2 and the other on the sphingomyelinase metabolite ceramide. The hypothesis that part of the PAF-induced oedema is mediated via the inositol 1,4,5-trisphosphate (IP3) pathway or Rho kinase pathway was investigated. Oedema formation was induced in isolated perfused rat lungs by injection of 5 nmol PAF into the pulmonary artery. Lungs were pre-treated with specific inhibitors: edelfosine (L108) to block phosphatidyl-inositol-specific phospholipase C, xestospongin to block the IP3 receptor, 5-iodonaphthalene-1-sulphonyl-homopiperazine (ML-7) to block myosin light chain kinase, and (+)-R-trans-4-(aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide (Y27632) to block Rho-associated protein kinase. Pre-treatment with L108 or xestospongin reduced PAF-induced oedema formation by 58 and 56%, respectively. The effect of L108 was additive to that of the cyclooxygenase inhibitor acetyl salicylic acid (88% oedema reduction). PAF-induced oedema formation was also reduced if extracellular calcium concentrations were lowered. Furthermore, treatment with ML-7 reduced oedema formation by 54%, whereas Y27632 was without effect. It is concluded that platelet-activating-factor-triggered oedema is mediated by activation of the inositol 1,4,5-trisphosphate pathway, influx of extracellular calcium and subsequent activation of a myosin light chain kinase-dependent and Rho-associated-protein-kinase-independent mechanism.

Sinusoidal endothelial COX-1-derived prostanoids modulate the hepatic vascular tone of cirrhotic rat livers

CCl(4) cirrhotic rat liver exhibits a hyperresponse to the alpha(1)-adrenergic agonist methoxamine (Mtx) that is associated with enhanced thromboxane A(2) (TXA(2)) production and is abrogated by indomethacin. To further elucidate the molecular mechanisms involved in the hyperresponse to vasoconstrictors, portal perfusion pressure dose-response curves to Mtx were performed in CCl(4) cirrhotic rats livers after preincubation with vehicle, the cyclooxygenase (COX)-1 selective inhibitor SC-560, and the COX-2 selective inhibitor SC-236. TXA(2) production was determined in samples of the perfusate. COX-1 expression was analyzed and quantified in hepatocytes, Kupffer cells, sinusoidal endothelial cells (SEC), and hepatic stellate cells (HSC) isolated from control and cirrhotic rat livers by double-immunofluorescence staining, with specific markers for each population using flow cytometry or Western blot analysis. COX-1 protein levels were not significantly increased in cirrhotic livers, but COX-2 protein expression was increased. COX-1 inhibition, but not COX-2, significantly attenuated the response to Mtx and prevented the increased production of TXA(2). Cirrhotic livers showed an increased expression of COX-1 in SEC and reduced expression in HSC compared with control livers, whereas COX-1 was similarly distributed in Kupffer cells. Despite abundant hepatic COX-2 expression, the increased response to Mtx of cirrhotic livers is mainly dependent of COX-1. Upregulation of COX-1 in cirrhotic SEC may be responsible for the hyperesponse to Mtx.

The relaxant effect of urocortin in rat pulmonary arteries

Urocortin is a potent vasodilator, which plays physiological or pathophysiological roles in systemic circulation. However, little is known about its action on pulmonary circulation. The present study was aimed to characterize some cellular mechanisms underlying the relaxant effect of urocortin in isolated rat pulmonary arteries. Changes in isometric tension were measured on small vessel myographs. Urocortin inhibited U46619-induced contraction with reduction of the maximal response. Urocortin-induced relaxation was independent of the presence of endothelium. Inhibitors of nitric oxide (NO)-dependent dilator, NG-nitro-L-arginine methyl ester or 1H-[1,2,4]oxadizolo[4,3-a]quinoxalin-1-one, did not affect the relaxation. Astressin (100-500 nM), a corticotropin-releasing factor (CRF) receptor antagonist and KT5720, a protein kinase A (PKA) inhibitor reduced urocortin-induced relaxation. Urocortin produced less relaxant effect in 30 mM K+- than U46619-contracted arterial rings. Urocortin did not reduce CaCl2-induced contraction in 60 mM K+-containing solution. Ba2+ (100-500 microM) but not other K+ channel blockers reduced the relaxant responses to urocortin. Urocortin also relaxed the rings preconstricted by phorbol 12,13-diacetae in normal Krebs solution while this relaxation was less in a Ca2+-free solution. Our results show that urocortin relaxed rat pulmonary arteries via CRF receptor-mediated and PKA-dependent but endothelium/NO or voltage-gated Ca2+ channel-independent mechanisms. Stimulation of Ba2+-sensitive K+ channel may contribute to urocortin-induced relaxation. Finally, urocortin relaxed pulmonary arteries partly via inhibition of a PKC-dependent contractile mechanism.

The anticoagulant protein C pathway

The anticoagulant protein C system regulates the activity of coagulation factors VIIIa and Va, cofactors in the activation of factor X and prothrombin, respectively. Protein C is activated on endothelium by the thrombin-thrombomodulin-EPCR (endothelial protein C receptor) complex. Activated protein C (APC)-mediated cleavages of factors VIIIa and Va occur on negatively charged phospholipid membranes and involve protein cofactors, protein S and factor V. APC also has anti-inflammatory and anti-apoptotic activities that involve binding of APC to EPCR and cleavage of PAR-1 (protease-activated receptor-1). Genetic defects affecting the protein C system are the most common risk factors of venous thrombosis. The protein C system contains multi-domain proteins, the molecular recognition of which will be reviewed.

Production of NA by endothelial NO-synthase: An in vitro versus in vivo study

Endothelial-derived relaxing factor (EDRF) is secreted by different endothelia in vivo. It is synthesised by endothelial NO-synthase (eNOS). Despite numerous works, its identity is not fully understood. Here the production of NA, a nitroso-arginine, which was shown to be synthesised by brain NO-synthase (bNOS), was studied in eNOS preparations. NA was quantified by reductive differential pulse voltammetry (RDPV) during its irreversible electrochemical transformation to N-hydroxy-arginine (NHA). Using microelectrodes, NA and nitrite were simultaneously measured in pure recombinant eNOS giving similar enzyme activity. NA was detected at the surface of human endothelial cells (HUVEC) and disappeared when D-arginine was introduced in the culture medium. NA production by endothelium tissue was studied in rat corpus cavernosum using voltammetric microelectrodes. NA concentration at the endothelium surface was linked to vasodilatation measured by laser Doppler induced by acetylcholine injection. LNMA ic injection induced NA disappearance. These preliminary new experiments suggested that NA could be the endogenous nitroso-compound presented early as EDRF.

[Vascular damage in chronic renal failure. The increase of vascular nitrotyrosine and cytochines accumulation is accompanied by an increase of endothelial nitric oxide synthase (eNOS) expression]

Patients with chronic renal failure (CRF) are at a greatly increased risk of cardiovascular mortality. This fact could be due to the presence of conventional risk factor and specific uremic as increase of oxidative stress, hyperhomocystaenemia, deranged calcium-phosphate metabolism and chronic inflammatory state. In order to analyze the vascular effects of CRF, we studied the histomorphometric characteristics (intima-media thickness and monocyte chemoattractant protein (MCP-1) accumulation (inmunohistochemical) on radial artery from 13 patients with CRF. We determined by Western blot analysis, the vascular nitrotyrosin abundance (footprint of nitric oxide (NO) inactivation by reactive oxygen species (ROS), and the endothelial nitric oxide synthase (eNOS) expression. The NOS activity was, also, determined. The results were compared with those obtained in pudenda artery from a healthy control group (n: 16). The CRF group showed a significant increase in intima and media thickness 108 +/- 16 vs 14 +/- 2.5 microm, p < 0.001 and 291 +/- 19 vs 153 +/- 15 microm, p < 0.001, respectively). The CRF group exhibited a marked elevation of MCP-1 vascular expression (2 +/- 0.15 vs 0.6 +/- 0.12 u, p < 0.001). A significant positive correlation was found between MCP-1 vascular expression and its inmunohistochemical deposits (r: 0.98, p < 0.0001). Nitrotyrosin abundance (western blot) was significantly increased in artery of CRF patients (2.1 +/- 0.1 vs 0.42 +/- 0.1 u, p < 0.0001). No significant differences was found in NOS activity between CRF and control groups. However, eNOS expression was greatly increased in the CRF patients (1.73 +/- 0.1 vs 0.67 +/- 0.1 u, p < 0.001). A significant positive correlation was found between nitrotyrosin and eNOS expression and systolic arterial pressure. However, the differences between CRF and control groups persisted after statistically fitting to arterial pressure. The present study demonstrate that in CRF there are arterial preatherosclerotic changes and an increase of vascular nitrotyrosin accumulation, which is the footprint of NO inactivation by ROS. The secondary NO inactivation can, in turn, contribute to eNOS vascular upregulation.

Ceramide-Induced Impairment of Endothelial Function Is Prevented by CuZn Superoxide Dismutase Overexpression

Objective— Ceramide is an important intracellular second messenger that may also increase superoxide. The goal of this study was to determine whether overexpression of CuZn superoxide dismutase (SOD) protects against ceramide-induced increases in vascular superoxide and endothelial dysfunction.

Methods and Results— Carotid arteries from CuZnSOD-transgenic (CuZnSOD-Tg) and nontransgenic littermates were examined in vitro. Immunohistochemistry confirmed that CuZnSOD protein was greater in carotid artery from CuZnSOD-Tg compared with nontransgenic mice. Ceramide ( N -acetyl- d -sphingosine; 1 and 10 μmol/L) produced concentration-dependent impairment ( P <0.05) of vasorelaxation in response to the endothelium-dependent agonist acetylcholine (ACh) in nontransgenic mice. For example, 100 μmol/L ACh relaxed arteries from nontransgenic mice by 96±4% and 52±5% in the presence of vehicle and 10 μmol/L ceramide, respectively. In contrast, ceramide (1 or 10 μmol/L) had no effect ( P >0.05) on responses of carotid artery to ACh in CuZnSOD-Tg mice. Ceramide had no effect on nitroprusside- or papaverine-induced relaxation in CuZnSOD-Tg or nontransgenic mice. Ceramide increased superoxide in arteries from nontransgenic vessels, and this effect was prevented by polyethyleneglycol-SOD (50 U/mL) or overexpression of CuZnSOD.

Conclusions— These results suggest that ceramide-induced increases in superoxide impair endothelium-dependent relaxation, and that select overexpression of the CuZn isoform of SOD prevents ceramide-induced oxidative stress in vessels.