Vascular Endothelial Growth Factor Nitric Oxide Research Articles

Irisin protects against obesity-related chronic kidney disease by regulating perirenal adipose tissue function in obese mice

BackgroundCompared with typical visceral fat deposits in obesity and metabolic syndrome, perirenal adipose tissue (PRAT) dysfunction is more closely linked to obesity-related chronic kidney disease (OB-CKD). The myokine irisin reportedly promotes positive outcomes in metabolic disease. This study investigated whether irisin could reduce urinary albumin excretion and demonstrate renoprotective effects through the regulation of PRAT function in obese mice.MethodsC57BL/6 J mice received a high-fat diet (HFD) with or without concurrent administration of irisin. Glucose tolerance, plasma levels of free fatty acids, and urinary albumin excretion were assessed, along with renal morphology. The vascular endothelial growth factor and nitric oxide in glomeruli were also analyzed, in addition to PRAT function-associated proteins.ResultsIrisin administration significantly reduced the final body weight, fat mass, and free fatty acids, without reducing PRAT mass, in HFD mice. Furthermore, irisin decreased urinary albumin excretion and attenuated both renal fibrosis and lipid accumulation. Irisin administration led to increases in PRAT function-associated proteins, including sirtuin1, uncoupling protein-1, and heme-oxygenase-1. Ex vivo treatment of PRAT and glomeruli with irisin also restored PRAT function. Finally, irisin treatment restored the vascular endothelial growth factor–nitric oxide axis.ConclusionsIrisin attenuated metabolic disorders and protected against OB-CKD by normalizing the PRAT–kidney axis. These results suggest that agents targeting PRAT activation might be useful for treatment of OB-CKD.

Liraglutide improves obesity-induced renal injury by alleviating uncoupling of the glomerular VEGF-NO axis in obese mice.

Obesity-related kidney disease is associated with generalized endothelial dysfunction. Liraglutide, a glucagon-like peptide-1 agonist, has cardiovascular-renal protective effects in patients with diabetes. In this study, the ability of liraglutide to reduce urinary albumin excretion by alleviating glomerular vascular endothelial growth factor-nitric oxide (VEGF-NO) axis uncoupling was assessed in high fat diet-induced obese mice. C57BL/6J mice were divided into control and obesity groups, treated with or without liraglutide (200μg/kg/day). Blood biochemistry and urinary albumin excretion were measured. Glomerular VEGF and the AMPK-endothelial nitric oxide synthase (eNOS) pathway were assayed by western blotting. Glomerular NO, renal haeme oxygenase-1 activity, and malondialdehyde levels were also measured. Treatment of obese mice with liraglutide led to significant reductions in body weight gain (46±1g vs 55±1g, P<.0001), visceral fat (8.9±0.6g vs 14.5±0.6g, P<.0001), perirenal fat (2.9±0.2g vs 5.4±0.3g, P<.0001), and free fatty acid (1.71±0.12mmol/L vs 1.02±0.08mmol/L, P<.0001). Liraglutide significantly improved glucose homeostasis, which was impaired in obese mice. Liraglutide reduced urinary albumin excretion and glomerular hypertrophy in obese mice. Additionally, liraglutide significantly decreased VEGF and increased glomerular NO production in glomeruli, indicating restoration of the glomerular VEGF-NO axis. Furthermore, liraglutide activated the glomerular AMPK-eNOS pathway in obese mice, upregulated renal haeme oxygenase-1 activity, and reduced the renal malondialdehyde levels in obese mice. In conclusion, liraglutide reduced microalbuminuria and ameliorated renal injury by alleviating the uncoupling of the glomerular VEGF-NO axis.

Snakehead fish extract as an enhancer of vascular endothelial growth factor and nitric oxide levels in cerebral angiogenesis: an insight of stroke therapy.

Aim To assess the effect of snakehead fish extract administration in angiogenesis focusing on the level of vascular endothelial growth factor (VEGF), nitric oxide (NO) and VEGF receptor 2(R2) expression is ischemic stroke models. Methods An experimental study was conducted on 5 groups of ischemic stroke rats models: Group K- without carotid artery ligation, Group K+ with artery ligation, Group P1 with artery ligation and administration of 200 mg/day extract, Group P2 with artery ligation and 400 mg/day extract, and Group P3 with artery ligation and 800 mg/day extract. The VEGF expression and NO levels were assessed on day 3. Results Snakehead fish extract significantly increased VEGF levels along with increasing doses, in which the highest VEGF level was observed in P3 group (361.7±40.2; p<0.001). The NO level also increased along with an increasing dose of snakehead fish extract, in which the highest NO level was found in P3 group(59.43±0.88 μmol/gr; p<0.001). The VEGFR2 expression also increased significantly after snakehead extract administration along with increasing doses (p<0.001) in which administration of 800mg extract yielded the highest VEGFR2 expression compared with lower doses (17.7 vs. 15.6; p<0.001) Conclusion Snakehead fish extract administration increased angiogenesis process marked by an increased level of VEGF, NO and VEGFR2 expression in ischemic stroke rat models.

P6289Neuregulin-1 improves cardiac function through protecting the loss of endothelial barrier in septic rats via RhoA/ROCK pathway

Abstract Background The main path of sepsis-induced cardiomyopathy is the loss of endothelial barrier function. Neuregulin-1 (NRG-1) has beneficial effects on endothelial function. Purpose To investigate the effect of NRG-1 treatment on the protection of cardiac endothelial cells and the changes of RhoA/ROCK signaling in sepsis. Methods Rats were randomly divided into three groups: sham, LPS, and NRG-1. After successful induction of sepsis by lipopolysaccharide (LPS, 10mg/kg), rats were administered either a vehicle or recombinant human neuregulin-1 (rhNRG-1, 10μg/kg/d) for one or two days. We recorded their survival rate at 48h after sepsis. Hemodynamic methods were performed to assess cardiac function. We used immunofluorescence assay to detect von Willebrand Factor (vWF). Intercellular adhesion molecule-1 (ICAM-1) and vascular endothelial growth factor (VEGF)levels in serum were measured by enzyme-linked immunosorbent assay (ELISA), and serum nitric oxide (NO) was detected by reductase method. We used transmission electron microscopy to observe changes in myocardial ultrastructure and western blot to assess expression of RhoA and ROCK1 protein. Results Sepsis impaired endothelial function manifested by increased ICAM-1, NO and VEGF levels in serum, NRG-1 treatment could significantly alleviate these increase (P&lt;0.05). Compared with the vehicle, NRG-1 significantly decreased cardiac vascular permeability through increasing the expression of vWF on endothelial lining (P&lt;0.05). Moreover, NRG-1 alleviated damages of ultrastructure of myocardial cells and suppressed the expression of RhoA and ROCK1 protein (P&lt;0.05). Ultimately, NRG-1 improved the survival,and prevented hemodynamic derangement. Levels of endothelial biomarker in serum ICAM-1 (pg/ml) VEGF (pg/ml) NO (pg/ml) Sham 24h 1564.74±94.41 0.84±0.28 203.27±1.81 Sham 48h 322.92±7.92 1.78±0.61 6.57±0.38 LPS 24h 5139.85±284.15† 3.11±0.04† 679.05±78.59† LPS 48h 950.41±25.23†‡ 4.65±0.30† 180.40±30.08†‡ NRG 24h 2772.18±164.45§ 0.30±0.04§ 355.14±23.41§ NRG 48h 578.57±28.97§‡ 1.02±0.45§ 104.67±2.13§‡ †p&lt;0.05 vs. the sham group, §p&lt;0.05 vs. the LPS group and ‡p&lt;0.05 vs. the 24h group. Effect of NRG-1 on endothelial cells Conclusions NRG-1 could alleviate endothelial injury in sepsis by strengthening the barrier function of vascular, reducing the secretion of endothelial-related biomarkers and inhibiting oxidative stress, thus improving cardiac function and survival rate, these effects may base on RhoA/ROCK signaling pathway. These may contribute to reverse the impaired endothelial cells in sepsis in the future. Acknowledgement/Funding The national natural science foundation of China (81772044)

Effects of bradykinin on the survival of multiterritory perforator flaps in rats

BackgroundBradykinin, a vasoactive peptide, has many biological functions. For example, it accelerates angiogenesis. Thus, we studied the effects of bradykinin on the survival of perforator flaps.MethodsAveragely, 50 male Sprague–Dawley rats were divided into control and bradykinin groups and underwent procedures to the multiterritory perforator flap. Areas of flap survival were tested 7 days later. Flap perfusion was evaluated by laser Doppler imaging. We assessed the extent of autophagy by determining LC3-II/I, Beclin 1, and p62. Flap angiogenesis was assessed by immunohistochemistry and H&E staining. We measured the level of vascular endothelial growth factor (VEGF) protein using western blot. We assessed oxidative stress by measuring the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) levels. The apoptotic index was also evaluated by western blot, and we determined nitric oxide (NO) production using an NO assay kit.ResultsThe bradykinin group exhibited significantly larger areas of flap survival, higher blood supply, and more neovascularization. The bradykinin group also had higher SOD activity, higher VEGF expression and NO content, and reduced MDA compared to the control group. Rats treated with bradykinin also had lower levels of apoptosis and autophagy relative to the control group.ConclusionOur results suggest that bradykinin promotes the survival of multiterritory perforator flaps by increasing angiogenesis, promoting the release of NO, suppressing apoptosis, reducing oxidative stress, and inhibiting autophagy.

Danhong Huayu Koufuye Prevents Diabetic Retinopathy in Streptozotocin-Induced Diabetic Rats via Antioxidation and Anti-Inflammation.

Danhong Huayu Koufuye (DHK), a traditional Chinese prescription, is used to treat central retinal vein occlusion clinically. We previously reported that DHK prevented diabetic retinopathy (DR) in rats. Moreover, we found that it protected endothelial cells from hyperglycemia-induced apoptosis through antioxidation and anti-inflammation. Here, we investigated whether antioxidative and anti-inflammatory activities of DHK contributed to its therapeutic effect on DR in streptozotocin- (STZ-) induced diabetic rats. DHK significantly blocked the breakdown of the blood-retinal barrier (BRB) and increased the thickness of the inner nuclear layer (INL), as well as suppressed the swelling of the ganglion cell layer (GCL) in diabetic retinas. DHK remarkably increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in plasma, and decreased serum level of nitric oxide (NO). Moreover, DHK markedly reduced the serum levels of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1). Furthermore, DHK significantly downregulated protein expressions of VEGF and inducible NO synthase (iNOS) and mRNA expression of ICAM-1 in retinas. These results suggest that the antioxidative and anti-inflammatory activities of DHK may be important mechanisms involved in the protective effect of DHK on DR in STZ-induced diabetic rats.

The Effect of Inducible Nitric Oxide Synthase on Multiterritory Perforator Flap Survival in Rats

Background Inducible nitric oxide synthase (iNOS) plays an important role in vasodilation, angiogenesis, and ischemia-reperfusion injury. We investigated the effects of iNOS on the survival and choke vessels of multiterritory perforator flaps in rats. Methods In this study, 84 rats were divided into two groups of 42 rats each and subjected to multiterritory perforator flap operations. Rats in group A received daily intraperitoneal doses of 100 mg per kg of aminoguanidine (AG) and rats in group B received daily intraperitoneal injections of the same volume of saline solution. On postoperative day 7, the surviving flap area was calculated as a percentage of the total flap dimensions using DP2-BSW software. The diameter and density of microvessels in the second choke zone of the flap were calculated from histology studies. The nitric oxide (NO) content was measured using NO concentration assay kits, and the levels of vascular endothelial growth factor (VEGF) and iNOS were assessed using western blotting. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured using test kits. Laser Doppler imaging was used to evaluate flap perfusion in the second choke zone for 7 days after surgery. Results The flap survival area, diameter and density of microvessels, iNOS and VEGF levels, NO content, blood perfusion, and MDA content were significantly higher in the control group compared with the AG group, whereas SOD activity was significantly lower in the control group. Conclusions iNOS has a beneficial effect on the survival of multiterritory perforator flaps.

Rifaximin, a non-absorbable antibiotic, inhibits the release of pro-angiogenic mediators in colon cancer cells through a pregnane X receptor-dependent pathway.

Activation of intestinal human pregnane X receptor (PXR) has recently been proposed as a promising strategy for the chemoprevention of inflammation-induced colon cancer. The present study was aimed at evaluating the effect of rifaximin, a non-absorbable antibiotic, in inhibiting angiogenesis in a model of human colorectal epithelium and investigating the role of PXR in its mechanism of action. Caco-2 cells were treated with rifaximin (0.1, 1.0 and 10.0µM) in the presence or absence of ketoconazole (10µM) and assessed for cell proliferation, migration and expression of proliferating cell nuclear antigen (PCNA). The release of vascular endothelial growth factor (VEGF) and nitric oxide (NO), expression of Akt, mechanistic target of rapamycin (mTOR), p38 mitogen activated protein kinases (MAPK), nuclear factor κB (NF-κB) and metalloproteinase-2 and -9 (MMP-2 and -9) were also evaluated. Treatment with rifaximin 0.1, 1.0 and 10.0µM caused significant and concentration-dependent reduction of cell proliferation, cell migration and PCNA expression in the Caco-2 cells vs. untreated cells. Treatment downregulated VEGF secretion, NO release, VEGFR-2 expression, MMP-2 and MMP-9 expression vs. untreated cells. Rifaximin treatment also resulted in a concentration-dependent decrease in the phosphorylation of Akt, mTOR, p38MAPK and inhibition of hypoxia-inducible factor 1-α (HIF-1α), p70S6K and NF-κB. Ketoconazole (PXR antagonist) treatment inhibited these effects. These findings demonstrated that rifaximin causes PXR-mediated inhibition of angiogenic factors in Caco-2 cell line and may be a promising anticancer tool.

Renal protective effects of induction of haem oxygenase-1 combined with increased adiponectin on the glomerular vascular endothelial growth factor-nitric oxide axis in obese rats.

What is the central question of this study? This study aimed to investigate whether induction of haem oxygenase-1 (HO-1) can protect the kidneys of obese rats by regulating the glomerular vascular endothelial growth factor-nitric oxide (VEGF-NO) axis by increasing the adiponectin concentrations. What is the main finding and its importance? Induction of HO-1 reduces the degree of microalbuminuria and has renal protective effects by improving endothelial function and regulating the uncoupled glomerular VEGF-NO axis in diet-induced obese rats. The mechanism may be related to increased activation of the HO-1-adiponectin axis. The glomerular vascular endothelial growth factor-nitric oxide (VEGF-NO) axis plays a critical role in maintenance of normal kidney function in obesity. Induction of haem oxygenase-1 (HO-1) may result in a parallel increase in adiponectin secretion. The aim of this study was to investigate whether induction of HO-1 could protect the kidneys of obese rats by regulating the glomerular VEGF-NO axis by increasing adiponectin levels. Rats received high-fat diets and were injected with either cobalt protoporphyrin to induce HO-1 or stannous protoporphyrin to inhibit HO-1. Blood and urine samples were collected. Endothelial function was determined by measuring the endothelium-dependent vasodilatation of the aorta. Renal tissues were collected for CD34 immunohistochemistry. The glomerular VEGF-NO axis and the AMP kinase-phosphoinositide 3-kinase (PI3K)/Akt-endothelial nitric oxide synthase pathway were measured. Induction of HO-1 by cobalt protoporphyrin decreased microalbuminuria, plasma free fatty acids, serum high-sensitivity C-reactive protein and malondialdehyde levels and increased serum adiponectin levels compared with the untreated obese rats. Severe impairment of endothelium-dependent vasodilatation was observed in the obese rats, which was improved to some extent by HO-1 induction. Induction of HO-1 reduced glomerular CD34 expression and production of reactive oxygen species in obese rats. Obese rats showed increased glomerular VEGF expression and reduced NO levels. This uncoupling of the glomerular VEGF-NO axis was improved to some extent by induction of HO-1, with enhancement of p-AMP kinase, p-Akt and phospho-endothelial nitric oxide synthase in obese rats. These results indicate that induction of HO-1 with cobalt protoporphyrin reduces the degree of microalbuminuria and has renal protective effects by improving endothelial dysfunction and regulating the glomerular VEGF-NO axis in diet-induced obese rats by increasing adiponectin levels.

Protective effects of adiponectin on uncoupling of glomerular VEGF-NO axis in early streptozotocin-induced type 2 diabetic rats.

To determine whether adiponectin could reduce microalbuminuria and provide renal protective effects by improving endothelial dysfunction and uncoupling of the glomerular vascular endothelial growth factor (VEGF)-nitric oxide (NO) axis in streptozotocin-induced type 2 diabetic rats. Wistar rats were randomly divided into normal control group, diabetic nephropathy (DN) group induced by high-fat feeding and streptozotocin, diabetic rats injected with adenovirus-expressed adiponectin (AD-AdipoQ), and diabetic rats injected with AD-IRES-EGFP as control. Blood and urine samples were collected. Endothelium-dependent vasodilatation (EDV) of the aorta was measured. Renal tissues were collected for CD34 immunohistochemistry. Glomerular NO and VEGF levels were measured by the Griess reaction and Western blot testing, respectively. Injections of AD-AdipoQ significantly increased serum adiponectin levels and reduced the urinary albumin-to-creatinine ratio in diabetic rats (P < 0.05). The levels of plasma glucose, serum insulin, high-sensitivity C-reactive protein, and malondialdehyde were significantly reduced in diabetic rats after injections of AD-AdipoQ (P < 0.05). Severe EDV impairment was observed in the DN group, which was improved by AD-AdipoQ. CD34 expression in the glomeruli was also higher in diabetic rats, indicating increased proliferation of glomerular endothelial cells. However, AD-AdipoQ improved the increased proliferation of endothelial cells in the glomeruli. Diabetic rats showed increased glomerular VEGF levels and reduced NO levels. This uncoupling of the VEGF-NO axis was partially improved by AD-AdipoQ. Adiponectin reduces the degree of microalbuminuria and has renal protective effects by improving endothelial dysfunction and uncoupling of the glomerular VEGF-NO axis in early diabetic nephropathy.

High FFA levels related to microalbuminuria and uncoupling of VEGF-NO axis in obese rats

The objectives of this study were to test whether elevated free fatty acids (FFA) from visceral fat accumulation is related to increased urinary albumin excretion and whether fenofibrate has renal protective effects by regulating vascular endothelial growth factor-nitric oxide (VEGF-NO) axis in rats with diet-induced obesity. Wistar rats were randomly divided into groups fed a normal diet, a high-fat diet, and a high-fat diet plus fenofibrate. Blood and urine samples were collected. Endothelial function was determined by measuring endothelium-dependent vasodilatation (EDV) of the aorta. Renal tissues were collected for CD31 immunohistochemistry. Glomerular NO and VEGF expression were measured by Griess reaction and Western blot, respectively. At the end of 24 weeks, plasma FFA and triglyceride levels significantly increased in the obese rats. Fenofibrate intervention decreased serum FFA and triglyceride levels by 43.4 and 48 %, respectively, accompanied by a reduced visceral fat index. Urinary albumin/creatinine ratio increased in obese rats, which decreased 62.6 % after fenofibrate intervention. Severe EDV impairment was observed in obese rats; this was partially improved by fenofibrate. CD31 expression in glomeruli increased in obese rats, indicating increased endothelial cell proliferation. Obese rats showed increased glomerular VEGF expression and reduced NO levels. This uncoupling of VEGF-NO axis was partially improved by fenofibrate. Elevated circulating FFA level may cause increased microalbuminuria in obese rats due to impairment of EDV; increased microalbuminuria can be improved by fenofibrate intervention. The mechanism may be related to FFA-induced uncoupling of VEGF-NO axis and endothelial dysfunction.

Exercise training restores the endothelial progenitor cells number and function in hypertension

Aerobic exercise training has been established as an important nonpharmacological treatment for hypertension. We investigated whether the number and function of endothelial progenitor cells (EPCs) are restored after exercise training, potentially contributing to neovascularization in hypertension. Twelve-week-old male spontaneously hypertensive rats (SHRs, n = 14) and Wistar-Kyoto (WKY, n = 14) rats were assigned to four groups: SHR; trained SHR (SHR-T); WKY; and trained WKY. Exercise training consisted of 10 weeks of swimming. EPC number and function, as well as the vascular endothelial growth factor (VEGF), nitrotyrosine and nitrite concentration in peripheral blood were quantified by fluorescence-activated cell sorter analysis (CD34+/Flk1+ cells), colony-forming unit assay, ELISA and nitric oxide (NO) analyzer, respectively. Soleus capillary/fiber ratio and protein expression of VEGF and endothelial NO synthase (eNOS) by western blot were assessed. Exercise training was effective in reducing blood pressure in SHR-T accompanied by resting bradycardia, an increase in exercise tolerance, peak oxygen uptake (VO2) and citrate synthase activity. In response to hypertension, the amount of peripheral blood-EPC and number of colonies were decreased in comparison with control levels. In contrast, exercise training normalized the EPC levels and function in SHR-T accompanied by an increase in VEGF and NO levels. In addition, oxidative stress levels were normalized in SHR-T. Similar results were found in the number and function of bone marrow EPC. Exercise training repaired the peripheral capillary rarefaction in hypertension by a signaling pathway VEGF/eNOS-dependent in SHR-T. Moreover, improvement in EPC was significantly related to angiogenesis. Our data show that exercise training repairs the impairment of EPC in hypertension, which could be associated with peripheral revascularization, suggesting a mechanism for its potential therapeutic application in vascular diseases.

Renoprotective potential of Macrothelypteris torresiana via ameliorating oxidative stress and proinflammatory cytokines

Ethnopharmacological relevanceMacrothelypteris torresiana is traditionally used in Chinese folk medicine for the treatment of edema for patients suffering from kidney/bladder problems due to its satisfactory therapeutic effectiveness. Aim of the studyThe aim of this study was to investigate the renoprotective nature of the total polyphenols fraction from Macrothelypteris torresiana (PMT). Materials and methodsThe biochemical criterions of plasma and kidney tissues were evaluated to study the effects of PMT on puromycin aminonucleoside-induced chronic nephrotic syndrome (NS) in hyperlipidemic mice. ResultsIn this study, the NS and hyperlipidemia were ameliorated after 9 weeks administration of PMT. Besides, PMT was able to modulate the level of renal oxidative stress and vascular endothelial growth factor–nitric oxide (VEGF–NO) pathway. ConclusionsIt represented a potential resource of PMT for the treatment of NS involved in metabolic syndrome.

Imbalance of glomerular VEGF-NO axis in diabetic rats: prevention by chronic therapy with propyl gallate

The uncoupling of the vascular endothelial growth factor-nitric oxide (VEGF-NO) axis may play a vital role in inducing glomerular endothelial dysfunction. We investigate the factors that contribute to the imbalance of the VEGF-NO axis and evaluate the effect of propyl gallate on preventing endothelial dysfunction. Streptozotocin (STZ, 60 mg/kg) was administrated to rats to establish an animal diabetic nephropathy model. The diabetic rats were randomly divided into a diabetic model group and a propyl gallate-treated group. Animals were sacrificed 8 weeks after the model was established. Periodic acid-Schiff staining was conducted to observe pathological changes, and reverse transcriptase polymerase chain reaction and Western blot were employed to analyze endothelial nitric oxide synthase (eNOS) and VEGF expressions. Commercial kits were used to detect glomerular eNOS activity and NO production, as well as oxidative stress. Compared with that in the normal control group, glomerular eNOS activity significantly decreased in diabetic rats, but eNOS expression remained at the same level. The expression of VEGF increased at this stage. Levels of glomerular oxidative stress also increased in diabetic rats and were inversely correlated with eNOS activity. Treatment with propyl gallate restored eNOS activity, ameliorated oxidative stress and improved glomerular pathological changes, but did not alter eNOS and VEGF expressions. The imbalance of the VEGF-NO axis in the glomeruli of diabetic rats may have resulted from eNOS inactivation, but not from the decrement in eNOS expressions at the early stage of rat diabetic nephropathy. Propyl gallate improved glomerular pathological changes in diabetic rats, possibly through oxidative stress reduction and VEGF-NO axis recovery.

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.

Hyperoxia disrupts vascular endothelial growth factor-nitric oxide signaling and decreases growth of endothelial colony-forming cells from preterm infants

Exposure of preterm infants to hyperoxia impairs vascular growth, contributing to the development of bronchopulmonary dysplasia and retinopathy of prematurity. Disruption of vascular endothelial growth factor (VEGF)-nitric oxide (NO) signaling impairs vascular growth. Endothelial progenitor cells (EPCs) may play an important role in vascular growth. Endothelial colony-forming cells (ECFCs), a type of EPC, from human preterm cord blood are more susceptible to hyperoxia-induced growth impairment than term ECFCs. Therefore, we hypothesized that hyperoxia disrupts VEGF-NO signaling and impairs growth in preterm ECFCs and that exogenous VEGF or NO preserves growth in hyperoxia. Growth kinetics of preterm cord blood-derived ECFCs (gestational ages, 27-34 wk) were assessed in room air (RA) and hyperoxia (40-50% oxygen) with or without VEGF, NO, or N(omega)-nitro-l-arginine. VEGF, VEGF receptor-2 (VEGFR-2), and endothelial NO synthase (eNOS) protein expression and NO production were compared. Compared with RA controls, hyperoxia significantly decreased growth, VEGFR-2 and eNOS expression, and NO production. VEGF treatment restored growth in hyperoxia to values measured in RA controls and significantly increased eNOS expression in hyperoxia. NO treatment also increased growth in hyperoxia. N(omega)-nitro-l-arginine treatment inhibited VEGF-augmented growth in RA and hyperoxia. We conclude that hyperoxia decreases growth and disrupts VEGF-NO signaling in human preterm ECFCs. VEGF treatment restores growth in hyperoxia by increasing NO production. NO treatment also increases growth during hyperoxia. Exogenous VEGF or NO may protect preterm ECFCs from the adverse effects of hyperoxia and preservation of ECFC function may improve outcomes of preterm infants.

Effet du NO inhalé sur le poumon et le cerveau en développement

With the advent of prenatal steroids, postnatal exogenous surfactant and less aggressive respiratory support, premature infants can develop chronic lung disease without even acute respiratory distress. This "new bronchopulmonary dysplasia" could be the result of impaired postnatal growth. Several experimental studies have suggested a possible role of the vascular endothelial growth factor/nitric oxide (VEGF/NO) pathway in restoring pulmonary angiogenesis and enhancing distal lung growth. The results of the clinical studies are, however, inconclusive, and it is currently unclear which subsets of premature infants might benefit from inhaled nitric oxide. Besides, severe intracranial haemorrhage and/or cystic periventricular leukomalacia may affect the most immature babies, many of whom are spared from severe initial respiratory disease. Recently, inhaled nitric oxide was shown to significantly decrease the incidence of these neurological events, and to improve the long-term outcome in a few clinical trials. At times neuroprotective, at times neurotoxic, nitric oxide is capable of divergent effects depending upon the extent of cerebral damage, the redox state of the cell, and the experimental model used. Recently, inhaled nitric oxide had recognized to have dramatic remote effects including angiogenesis and maturation on the developing brain in rodent pups. Therefore, the developmental consequences of inhaled NO should be further investigated to ensure its safety on the developing brain and to test its potential neurprotective effect.

Cellular and Vascular Changes in the Retina of Neonatal Rats after an Acute Exposure to Hypoxia

This study was undertaken to examine the effects of an acute hypoxic exposure on the retinal cells and production of vascular factors such as vascular endothelial growth factor (VEGF) and nitric oxide (NO), which may affect vascular permeability in the developing retina. Retinas of 1-day-old rats were examined at 3 hours to 14 days after hypoxic exposure. The mRNA and protein expression of hypoxia-inducible factor-1alpha (HIF-1alpha), VEGF, endothelial nitric oxide synthase (eNOS), neuronal NOS (nNOS), and inducible NOS (iNOS) were determined by real-time RT-PCR, Western blot analysis, and immunohistochemistry. Electron microscopy was used to examine the structural alterations in retinal cells, and rhodamine isothiocyanate (RhIC) or horseradish peroxidase (HRP) was administered intraperitoneally or intravenously to determine vascular permeability. The mRNA and protein expression of HIF-1alpha, VEGF, eNOS, nNOS, and iNOS, along with VEGF concentration and NO production, were increased in response to hypoxia. Swollen Müller cell processes, apoptotic and necrotic cells in the inner nuclear layer, and changes in ganglion cells such as swollen and disrupted mitochondria were observed in hypoxic animals. Increased leakage of RhIC and HRP from retinal and hyaloid vessels was seen after hypoxic exposure. The authors suggest that increased VEGF and NO production in hypoxia resulted in increased vascular permeability, leading to changes in Müller cells and degeneration of neural cells. Melatonin administration reduced VEGF and NO production, diminished leakage of RhIC and HRP, and promoted cell proliferation, suggesting this as a potential therapeutic agent in reducing hypoxia-associated damage in the developing retina.

The Effect of Hypercholesterolemia on Serum Vascular Endothelial Growth Factor and Nitrite Concentrations in Early Stage of Atherosclerosis in Rabbits

Vascular Endothelial Growth Factor (VEGF) and Nitric Oxide (NO) play an important role for maintaining endothelial integrity. The purpose is to investigate the VEGF alteration during early atherosclerosis lesion formation in an animal model of hypercholesterolemia. We also measured nitrite to observe the relationship between VEGF and endothelial NO production. 20 white male rabbits randomly assigned in 2 groups (1% high-cholesterol diet, HC group, n = 14, or standard diet, control, n = 6) for 4 weeks. The serum levels of VEGF and nitrite (NO metabolite) were determined. Fatty streaks were measured in rabbit’s aortas. The results indicated that the serum level of VEGF concentration was significantly higher in hypercholesterolemic rabbits and negatively correlated with fatty streak lesions (r = -0.89, p<0.05). The serum level of nitrite was significantly higher in HC group than the control (p<0.05). There was a significant negative correlation between serum level of nitrite and VEGF (r = -0.55, p<0.05). It is concluded that, the increased VEGF in early atherosclerosis may be regarded as a safeguarding response to endothelial injury, which is responsible for maintaining endothelial integrity.

Inhaled nitric oxide to prevent bronchopulmonary dysplasia in preterm neonates

Bronchopulmonary dysplasia is a chronic lung disease that affects premature infants and contributes to their morbidity and mortality. With the advent of prenatal steroids and postnatal exogenous surfactant and less aggressive respiratory support, premature infants can develop chronic oxygen dependency without even acute respiratory distress. This 'new bronchopulmonary dysplasia' could be the result of impaired postnatal growth. Several experimental studies have suggested a possible role of the vascular endothelial growth factor/nitric oxide (VEGF/NO) pathway in restoring pulmonary angiogenesis and enhancing distal lung growth. The results of the clinical studies are, however, inconclusive, and it is currently unclear which subsets of premature infants might benefit from inhaled nitric oxide. Besides, severe intracranial haemorrhage and/or cystic periventricular leucomalacia may affect the most immature babies, many of whom are spared from severe initial respiratory disease. Recently, inhaled nitric oxide was shown to significantly decrease the incidence of these neurological events, and to improve the long-term outcome in a few clinical trials. At times neuroprotective, at times neurotoxic, nitric oxide is capable of divergent effects depending upon the extent of cerebral damage, the redox state of the cell, and the experimental model used. Recently, our group found that inhaled nitric oxide had remote effects including angiogenesis and maturation on the developing brain in rodent pups. Thus, we await the results of the recently completed randomised clinical trial of inhaled nitric oxide to prevent bronchopulmonary dysplasia (the European Nitric Oxide or 'EUNO' trial) where, besides the primary endpoint of chronic oxygen dependency reduction at 36 weeks' postconceptional age, long-term lung and brain will be followed-up until 7 years of age.