Urinary Isoprostane Excretion Research Articles

Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis.

We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound‐detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross‐sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, −0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40‐ligand (P = 0.0238), soluble Nox2‐derived peptide (sNox2‐dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD40L (Spearman’s rank correlation coefficient [rs], −0.33; P < 0.001), sNox2‐dp (rs, −0.57; P < 0.0001), and urinary excretion of isoprostanes (rs, −0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2‐dp, and urinary 8‐iso prostaglandin F2α‐III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2‐dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation.

Effects of the Prdx2 depletion on blood pressure and life span in spontaneously hypertensive rats.

Oxidative stress is involved in the pathogenesis of hypertension and hypertensive organ damage. Our previous study suggested that stroke-prone spontaneously hypertensive rats (SHRSP) exhibited greater oxidative stress than SHR and that the stroke incidence was significantly greater in SHRSP than SHR. Therefore, we hypothesized that oxidative stress was responsible for the stroke susceptibility in SHRSP. The present study constructed Prdx2 (a gene coding an antioxidative enzyme)-knockout (KO) SHR to examine whether Prdx2 knockout would make SHR more vulnerable to hypertensive organ damage, including stroke. Prdx2-KO SHR were created using CRISPR/CAS9 for genome editing. Eight-week-old male SHR and Prdx2-KO SHR were fed 1% NaCl for 2 months to induce blood pressure (BP) changes and stroke occurrence. The baseline BP was significantly greater in KO SHR, and this difference disappeared after salt loading. The life span of KO SHR was significantly reduced compared to that of SHR despite no differences in BP under salt-loading. However, no stroke was observed in KO SHR. The severity of hypertensive renal and cardiac injuries did not differ significantly between the two strains, but oxidative stress, evaluated using urinary isoprostane excretion and DHE staining, was greater in KO SHR. These results indicated that the Prdx2-depletion caused a shorter life span and modest BP increase in SHR via increased oxidative stress. The pathophysiological roles of oxidative stress in this model should be clarified in future studies.

Abstract 360: Rivaroxaban Enhances the Antiplatelet Activity of Aspirin via Inhibition of Nox2-mediated Thromboxane A 2 and Isoprostane Biosynthesis

Background: A recent study demonstrated that a combination of rivaroxaban, an inhibitor of factor Xa, plus aspirin (100mg/day) reduces cardiovascular events in patients with stable vascular disease, compared to aspirin alone but the underlying mechanism is still unknown. Methods: In vitro study was performed consisting in measuring agonist-induced platelet aggregation, thromboxane (Tx)B 2 and isoprostane biosynthesis, soluble Nox 2 -dp, a marker of Nox2 activation, and PLA 2 activation in platelets from healthy subjects (n=5) added with or without scalar doses of aspirin (25-100 uM) and/or rivaroxaban (15-120 ng/ml). Furthermore, we measured urinary excretion of isoprostanes, and soluble Nox2 before and after 3 months of 20 mg rivaroxaban (n=25) or warfarin (n=25) treatment in atrial fibrillation(AF) patients. Results: In vitro study showed that rivaroxaban significantly reduced platelet aggregation, TxB 2 and isoprostane biosynthesis and Nox2 and PLA 2 activation in a dose-dependent fashion. Also, rivaroxaban dose-dependently inhibited aggregation of platelets treated with low-(25uM) as well as high-(100uM) aspirin doses. In low-dose aspirin-treated samples an incremental inhibition of platelet TxB 2 biosynthesis was achieved; conversely, in platelets treated with high doses of aspirin a significant inhibition of isoprostanes and Nox2 was observed. Inhibition of platelet aggregation by rivaroxaban was detected also in platelets stimulated with convulxin suggesting that its antiplatelet effect was GPVI-dependent. In addition, convulxin elicited PLA 2 activation, that was inhibited by rivaroxaban as well as by a Nox2 inhibitor. Finally, in AF patients treated with rivaroxaban a significant reduction of urinary isoprostanes and soluble Nox2 and GPVI as compared to warfarin-treated ones was detected. Conclusion: Here we show that rivaroxaban inhibits platelet aggregation via GPVI interaction and eventually Nox2-mediated thromboxane and isoprostane biosynthesis in aspirin-treated platelets so providing a novel mechanistic insight into the beneficial effects of combining rivaroxaban with aspirin.

Oxidative stress in patients affected by primary aldosteronism.

Primary aldosteronism, an important form of secondary hypertension, is associated with significant increase of cardiovascular risk (ischaemic heart, cerebrovascular events, arrhythmias) (relative risk 4.6). The specific treatment of primary aldosteronism significantly reduces cardiovascular risk. In addition to high blood pressure values and direct action of aldosterone, new mechanisms such as increased oxidative stress are involved in the development of organ damage, metabolic, endothelial and coagulation complications. The aim of the study was to evaluate parameters of oxidative stress in 38 patients (21 men, 17 women, mean age 53.3 ± 4.7 years) with primary aldosteronism [11 aldosterone-producing adenoma (APA) (4 men, 7 women, mean age 50.2 ± 4.5 years) and 27 idiopathic adrenal hyperplasia (IHA) (17 men, 10 women, mean age 54.5 ± 5.3 years)] at diagnosis and after specific treatment (surgical or pharmacological), with respect to 50 patients with essential hypertension (26 men, 24 women, mean age 49 ± 7.4 years) and 50 healthy individuals (28 men, 22 women, mean age 48.7 ± 4.4 years). Patients with primary aldosteronism showed significant increase of NADPH oxidase (Nox2-dp) plasma levels and urinary isoprostanes (34.9 ± 4.3 μg/dl and 216.3 ± 15.7 ng/mg, respectively; P < 0.05) than essential hypertensive patients (27.1 ± 3.7 μg/dl and 144.8 ± 9.4 ng/mg, respectively; P < 0.05). In APA patients undergoing adrenalectomy, we observed significant reduction of both circulating levels of Nox2-dp (29 ± 2.1  vs. 22,4 ± 1.7 μg/dl; P < 0.05) and urinary levels of isoprostanes (221.1 ± 10.5 vs. 132.6 ± 8.7 ng/mg; P < 0.05). This is the first study showing an increased oxidative stress in primary aldosteronism, characterized by increased serum levels of Nox2-dp and urinary excretion of isoprostanes. After APA removal with laparoscopic adrenalectomy, we found reduction of serum Nox2-dp and urinary isoprostanes.

Abstract 559: Augmented Urinary Angiotensinogen in Young Type-1 Diabetic Subjects Correlates with Hemoglobin A1c and Urinary 8-Isoprostane

Previous studies indicate that the intrarenal renin-angiotensin system (RAS) is activated in type-1 diabetes mellitus (T1DM) experimental animal models and human subjects, and is reflected by augmentation of urinary angiotensinogen (uAGT) excretion rate. Studies were performed to evaluate uAGT in young patients with short duration diabetes mellitus (DM) and its relationships with HbA1c and urinary 8-isoprostane excretion rate. Blood and urine samples were collected from 77 young (15±1 years) patients (44 male, 33 female) with short duration T1DM treated only with insulin and 36 (17 male, 19 female) control subjects. Serum glucose levels were 85±4 mg/dl in control subjects and 192±11 mg/dl in DM patients. Urinary Alb/Cr and uPro/Cr ratios were not significantly different in DM patients compared to control (8.6±.9 vs 9.7±.6 and 51±8 vs 62±14 mg/g). However, the uAGT/Cr ratios were significantly elevated in the DM patients (6.8±.8 vs 16.5±1.5 ug/g). Correlation analysis demonstrated highly significant relationships (P&lt;.0001) between uAGT/Cr and HbA1c (R=.44) and urinary 8-isoprostane excretion rate (R=.52) in the DM patients. These results indicate that, even in young non-albuminuric patients with relatively short duration of DM, uAGT excretion rates are increased, suggesting early activation of the intrarenal RAS, and are correlated with HbA1c and urinary 8-isoprostane levels indicative of increased reactive oxygen species. Accordingly, uAGT levels may serve as an early marker of an activated intrarenal RAS and provide a specific index of renal RAS status potentially useful in monitoring clinical response to therapy.

Dipeptidyl peptidase IV inhibitor protects against renal interstitial fibrosis in a mouse model of ureteral obstruction

Dipeptidyl peptidase IV (DPPIV) is an exopeptidase that modulates the function of several substrates, among which insulin-releasing incretin hormones are the most well known. DPPIV also modulate substrates involved in inflammation, cell migration, and cell differentiation. Although DPPIV is highly expressed in proximal renal tubular cells, the role of DPPIV inhibition in renal disease is not fully understood. For this reason, we investigated the effects of LC15-0444, a DPPIV inhibitor, on renal function in a mouse model of renal fibrosis. Eight-week-old C57/BL6 mice were subjected to unilateral ureteral obstruction (UUO) and were treated with LC15-0444 (a DPPIV inhibitor) at a dose of 150 mg/kg per day in food or vehicle for 14 days. DPPIV activity was significantly increased in obstructed kidneys, and reduced after treatment with LC15-0444. Administration of LC15-0444 resulted in a significant decrease in albuminuria, urinary excretion of 8-isoprostane, and renal fibrosis. DPPIV inhibition also substantially decreased the synthesis of several proinflammatory and profibrotic molecules, as well as the infiltration of macrophages. UUO significantly increased, and LC15-0444 markedly suppressed, levels of phosphorylated Smad2/3, TGFβ1, toll-like receptor 4, high-mobility group box-1, NADPH oxidase 4, and NF-κB. These results suggest that activation of DPPIV in the kidney has a role in the progression of renal disease and that targeted therapy inhibiting DPPIV may prove to be a useful new approach in the management of progressive renal disease, independent of mechanisms mediated by glucagon-like peptide-1.

Combined acute hyperglycemic and hyperinsulinemic clamp induced profibrotic and proinflammatory responses in the kidney

Increase in matrix protein content in the kidney is a cardinal feature of diabetic kidney disease. While renal matrix protein content is increased by chronic hyperglycemia, whether it is regulated by acute elevation of glucose and insulin has not been addressed. In this study, we aimed to evaluate whether short duration of combined hyperglycemia and hyperinsulinemia, mimicking the metabolic environment of prediabetes and early type 2 diabetes, induces kidney injury. Normal rats were subjected to either saline infusion (control, n = 4) or 7 h of combined hyperglycemic-hyperinsulinemic clamp (HG+HI clamp; n = 6). During the clamp, plasma glucose and plasma insulin were maintained at about 350 mg/dl and 16 ng/ml, respectively. HG+HI clamp increased the expression of renal cortical transforming growth factor-β (TGF-β) and renal matrix proteins, laminin and fibronectin. This was associated with the activation of SMAD3, Akt, mammalian target of rapamycin (mTOR) complexes, and ERK signaling pathways and their downstream target events in the initiation and elongation phases of mRNA translation, an important step in protein synthesis. Additionally, HG+HI clamp provoked renal inflammation as shown by the activation of Toll-like receptor 4 (TLR4) and infiltration of CD68-positive monocytes. Urinary F2t isoprostane excretion, an index of renal oxidant stress, was increased in the HG+HI clamp rats. We conclude that even a short duration of hyperglycemia and hyperinsulinemia contributes to activation of pathways that regulate matrix protein synthesis, inflammation, and oxidative stress in the kidney. This finding could have implications for the control of short-term rises in blood glucose in diabetic individuals at risk of developing kidney disease.

Green tea with high-density catechins improves liver function and fat infiltration in non-alcoholic fatty liver disease (NAFLD) patients: A double-blind placebo-controlled study

Catechins, a major component of green tea extract, have anti-hyperlipidemic effects. The present study investigated the effects of consumption of green tea with high-density catechins in non-alcoholic fatty liver disease (NAFLD) patients. Seventeen patients with NAFLD consumed green tea with high-density catechins, low-density catechins or a placebo for 12 weeks in a randomized double-blind study. Ultrasonography and computed tomography (CT) were performed at baseline and after 12 weeks. Serum alanine aminotransferase (ALT) levels and urine 8-isoprostane were monitored and compared to baseline at 4, 8 and 12 weeks. Body fat was significantly decreased in the high-density catechin group compared with the placebo and low-density catechin groups after 12 weeks of consumption. All the patients in the high-density catechin group showed a significantly improved liver-to-spleen CT attenuation ratio compared with the placebo and low-density catechin groups after 12 weeks of consumption. The high-density catechin group significantly decreased serum ALT levels and reduced urinary 8-isoprostane excretion compared with the placebo and low-density catechin group after 12 weeks of consumption. Based on a reduced proportion of body fat as estimated by bioimpedance measurement, increased liver-to-spleen CT attenuation ratio, decreased serum ALT levels and reduced urinary 8-isoprostane excretion, we concluded that 12 weeks of 700 ml per day of green tea containing >1 g catechin improved liver fat content and inflammation by reducing oxidative stress in patients with NAFLD.

Impaired renal function and increased urinary isoprostane excretion in Ghanaian women with pre-eclampsia.

The cause of pre-eclampsia remains largely unknown, but oxidative stress (an imbalance favoring oxidant over antioxidant forces) has been implicated in contributing to the clinical symptoms of hypertension and proteinuria. Assessment of oxidative stress in pre-eclampsia using urinary isoprostane has produced conflicting results, and it is likely that renal function may affect isoprostane excretion. The aim of this study was to determine the role of oxidative stress in the pathophysiology of pre-eclampsia and to assess the effect of renal function on isoprostane excretion in pre-eclampsia in the Ghanaian population. This was a case-controlled study, comprising 103 pre-eclamptic women and 107 normal pregnant controls and conducted at the Korle-Bu Teaching Hospital between December 2006 and May 2007. The study participants were enrolled in the study after meeting the inclusion criteria and signing their written informed consent. Oxidative stress was determined by measuring urinary excretion of isoprostane and total antioxidant capacity using an enzyme-linked immunosorbent assay technique. Renal function was assessed by calculating the estimated glomerular filtration rate using the Modification of Diet in Renal Disease formula. The pre-eclampsia group had significantly (P = 0.0006) higher urinary isoprostane excretion (2.81 ± 0.14 ng/mg creatinine) than the control group (2.01 ± 0.18 ng/mg creatinine) and a significantly (P = 0.0008) lower total antioxidant power (1.68 ± 0.05 mM) than the control group (1.89 ± 0.04 mM). Urinary isoprostane excretion showed a positive correlation with both mean arterial pressure (r = 0.261) and microalbuminuria (r = 0.510) in the pre-eclampsia cases. The pre-eclampsia group had a significantly lower estimated glomerular filtration rate than the control group (P < 0.001), indicating more renal impairment. The increased urinary excretion of isoprostanes and decreased total antioxidant power in the in pre-eclampsia group suggest increased production of oxidants and depletion and/or reduction of maternal antioxidants. Increased oxidative stress may be important in the pathophysiology of pre-eclampsia by contributing to endothelial dysfunction, proteinuria, and hypertension.

Gastric cancer in Zambian adults: a prospective case-control study that assessed dietary intake and antioxidant status by using urinary isoprostane excretion

Gastric cancer is increasingly recognized in Zambia. Although nutritional factors contribute to gastric cancer risk, their effect in Zambia is unknown. The objective was to investigate the association between intake of dietary antioxidants, urinary 8-iso prostaglandin F2α (8-iso PGF2α) as a marker of oxidative stress, and gastric cancer. This was a case-control study at the University Teaching Hospital in Zambia. Gastric cancer cases were compared with age- and sex-matched controls. Urine 8-iso PGF2α was measured primarily by ELISA, and by gas chromatography-mass spectrometry in a subset, expressed as a ratio to creatinine. Blood was collected for Helicobacter pylori, HIV serology, gastrin-17, and pepsinogen 1 and 2 concentrations. Clinical and dietary data were collected by using questionnaires. Food items were broadly classified into 7 major categories (fruit, vegetables, fish, meat, insects, cereals, and starches). Fifty cases with gastric cancer (mean age: 61 y; n = 31 males) and 90 controls (mean age: 54 y; n = 41 males) were enrolled. Median urinary 8-iso PGF2α excretion was higher in cases (0.014; IQR: 0.008-0.021) than in controls (0.011; IQR: 0.006-0.018; P = 0.039). On univariate analysis, habitual fruit intake was lower in cases than in controls during the dry season (P = 0.02). On multivariate analysis, smoking (OR: 7.22; IQR: 1.38-37.9) and gastric atrophy (OR: 2.43; IQR: 1.12-5.13) were independently associated with cancer, and higher fruit intake was protective (OR: 0.44; IQR: 0.20-0.95). Isoprostane excretion was inversely correlated with total fruit intake (ρ = -0.23; n = 140; P = 0.006). Urinary 8-iso PGF2α excretion was associated with the risk of gastric cancer, as were smoking and gastric atrophy, but increased fruit intake conferred protection. This trial was registered at www.pactr.org as ISRCTN52971746.

High blood pressure but normal oxidative stress in D3 dopamine receptor deficient mice

To determine if renal oxidative stress is involved in the regulation of blood pressure (BP) upon disruption of D3R, we measured the BP (telemetry) and indices of oxidative stress in D3R−/−, D3+/− and their wild type (D3+/+) mice on normal (0.8% NaCl) or high (4% NaCl) salt diet for one week. Systolic BP (SBP) was higher in D3‐/‐ and D3+/− relative to D3+/+ mice on normal salt diet. NOX1 (101±10 % of D3+/+ mice), NOX2 (101±8) and NOX4 (120±16) was similar in D3−/− and D3+/+ mice. CuZnSOD expression was increased (135±9, P&lt;0.05, n=5), while the EcSOD and MnSOD were unchanged in D3−/− relative to D3+/+ mice. Nitrotyrosine (NT) was not altered in D3−/− (107±30). Urinary isoprostane excretion tended to be lower in D3−/− (445±106 pg/mg of creatinine) than D3+/+ (852±213), but the difference did not reach statistical significance. In D3+/− mice, NOX1 and NOX4 were unchanged but NOX2 (70±8, n=6) was slightly decreased. NT was similar in D3+/− and D3 +/+ mice. On high salt diet, SBP was increased more than 10% over baseline in D3−/− mice but not in D3+/+ mice. NOX1, NOX2, and NOX4 were not altered while NT was decreased (49±8, P&lt;0.05, n=4) and EcSOD was increased (145±1) in D3−/− relative to D3+/+ mice. Thus, the hypertension and salt sensitivity observed in D3−/− and D3+/− mice are not associated with increased renal oxidative stress and compensatory mechanisms may be involved in maintaining normal production of ROS.

Renal protective effects of α-calcitonin gene-related peptide in deoxycorticosterone-salt hypertension

Deoxycorticosterone salt (DOC-salt) hypertension-induced renal damage is enhanced in α-calcitonin gene-related peptide (α-CGRP) knockout (KO) compared with wild-type (WT) mice. However, since the α-CGRP KO mice have a 15-20 mmHg higher baseline mean arterial pressure (MAP) than WT mice, they also have a higher MAP than WT mice throughout the course of DOC-salt hypertension. To determine the mechanism by which the absence of α-CGRP enhances hypertension-induced renal damage, DOC-salt hypertension was induced in telemetry probe implanted α-CGRP KO and WT mice. To equalize the blood pressure (BP) to that of DOC-salt WT mice, an additional group of DOC-salt α-CGRP KO mice was given 0.025% hydralazine to drink. The DOC-salt protocol increased the final MAP in α-CGRP KO mice to 155 ± 6 mmHg and in WT mice to 140 ± 5 mmHg. The MAP of the hydralazine-treated DOC-salt α-CGRP KO mice was 139 ± 6 mmHg. Urinary excretion of microalbumin and isoprostane, a marker for oxidative stress, was increased, and creatinine clearance was decreased in DOC-salt α-CGRP KO compared with DOC-salt WT mice. Equalization of the MAP in DOC-salt α-CGRP KO to that of DOC-salt WT mice did not significantly improve these parameters. Renal macrophage infiltration; desmin, a marker of podocyte damage; and the inflammatory cytokines TNF-α and IFN-γ and the chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α) were increased in DOC-salt α-CGRP KO mice and were not reduced by hydralazine treatment. However, BP equalization did improve the renal histopathological damage, as determined by light microscopy. Therefore, in DOC-salt hypertension in mice, the mechanism(s) of the renal protective effects of α-CGRP are both BP independent and BP dependent.

Effects of high-amount–high-intensity exercise on in vivo platelet activation: Modulation by lipid peroxidation and AGE/RAGE axis

Physical activity is associated with cardiovascular risk reduction, but the effects of exercise on platelet activation remain controversial. We investigated the effects of regular high-amount, high intensity aerobic exercise on in vivo thromboxane (TX)-dependent platelet activation and plasma levels of platelet-derived proteins, CD40L and P-selectin, and whether platelet variables changes may be related to changes in high-density lipoprotein (HDL) and in the extent of oxidative stress and oxidative stress-related inflammation, as reflected by urinary isoprostane excretion and endogenous soluble receptor for advanced glycation end-products (esRAGE), respectively. Urinary excretion of 11-dehydro-TXB₂ and 8-iso-prostaglandin (PG)F(2α) and plasma levels of P-selectin, CD40L and esRAGE were measured before and after a eight-week standardised aerobic high-amount-high-intensity training program in 22 sedentary subjects with low-to-intermediate risk. Exercise training had a clear beneficial effect on HDL cholesterol (+10%, p=0.027) and triglyceride (-27%, p=0.008) concentration. In addition, a significant (p<0.0001) decrease in urinary 11-dehydro-TXB₂ (26%), 8-iso-PGF(2α) (21%), plasma P-selectin (27%), CD40L (35%) and a 61% increase in esRAGE were observed. Multiple regression analysis revealed that urinary 8-iso-PGF(2α) [beta=0.33, SEM=0.116, p=0.027] and esRAGE (beta=-0.30, SEM=31.3, p=0.046) were the only significant predictors of urinary 11-dehydro-TXB₂ excretion rate over the training period. In conclusion, regular high-amount-high-intensity exercise training has broad beneficial effects on platelet activation markers, paralleled and possibly associated with changes in the lipoprotein profile and in markers of lipid peroxidation and AGE/RAGE axis. Our findings may help explaining why a similar amount of exercise exerts significant benefits in preventing cardiovascular events.

Gastric Cancer in Zambian Adults: A Prospective Case-Control Study Assessing Dietary Intake and Oxidative Stress Using Urinary Isoprostane Excretion

Gastric Cancer in Zambian Adults: A Prospective Case-Control Study Assessing Dietary Intake and Oxidative Stress Using Urinary Isoprostane Excretion

Abstract 370: Upregulation of Renal D5 Dopamine Receptor Ameliorates Hypertension in D3 Deficient Mice

D 3 dopamine receptor (D 3 R) deficient mice have renin-dependent hypertension but the hypertension is mild and is not associated with oxidative stress. In order to determine if any compensatory mechanism in the kidney is involved in the regulation of blood pressure with disruption of D 3 R, we measured the renal protein expression of dopamine receptors in D 3 R homozygous (D 3 -/-) and heterozygous (D 3 +/-) knockout mice and their wild type (D 3 +/+) littermates. D 5 dopamine receptor (D 5 R) (169±23%, reported as % of D 3 +/+, n=5/group) expression was increased but D 4 dopamine receptors protein expression (59±8%) was decreased, while no significant changes were found with D 1 and D 2 dopamine receptors. Immunocytochemistry showed a stronger renal staining of D 5 R but without a change in renal tubule cell distribution in D 3 -/- relative to D 3 +/+ mice. D 5 R abundance was also increased in D 3 +/- (205±30%, n=5/group) relative to D 3 +/+ mice, while D 1 R abundance was similar between D 3 +/- and D 3 +/+ mice. The increase in D 5 R expression was abolished while blood pressure was increased further in D 3 -/- mice fed a high salt diet. Treatment of the D 1 -like (including D 1 and D 5 receptors) antagonist, SCH23390 , increased the blood pressure to a greater extent in anesthetized D 3 -/- mice than in D 3 +/+ mice (n=4/group), suggesting that the upregulation of D 5 R may modulate the hypertension in mice caused by the disruption of D 3 R. Since dopamine inhibits the NADPH oxidase-induced production of reactive oxygen species (ROS) via the D 5 R, we also measured the protein expression of NOXs in the kidney and isoprostane in the urine. No NADPH oxidase subunit was increased in D 3 -/- and D 3 +/- mice relative to D 3 +/+ mice fed a normal or salt high salt diet, and urinary isoprostane excretion was also similar in D 3 -/- and D 3 +/+ mice. Our findings suggest that the upregulation of D 5 R may minimize the hypertension and prevent oxidative stress in D 3 -/- mice.

Obesity and Hypercholesterolemia are Associated with NOX2 Generated Oxidative Stress and Arterial Dysfunction

To analyze the interplay among oxidative stress, NOX2, the catalytic core of nicotinamide-adenine dinucleotide phosphate oxidase, and endothelial dysfunction in children with obesity and/or hypercholesterolemia. We performed a cross-sectional study comparing flow-mediated arterial dilation (FMD), oxidized low-density lipoprotein, and urinary excretion of isoprostanes (8-iso-PGF2α), as markers of oxidative stress, and NOX2 activity, as assessed by blood levels of soluble NOX2-dp (sNOX2-dp), in a population of 100 children, matched for age and sex, including 40 healthy subjects (HS), 20 children with hypercholesterolemia (HC), 20 obese children (OC), and 20 children with coexistence of hypercholesterolemia and obesity (HOC). HOC had higher sNOX2-dp and oxidized low-density lipoprotein levels compared with HS, HC, and OC. HC, OC, and HOC had lower FMD values compared with HS. Urinary 8-iso-PGF2α excretion was higher in HOC compared with HS. FMD was inversely correlated with sNOX2-dp levels (r = -0.483; P < .001) and with the number of cardiovascular risk factors (r = -0.617; P < .001). Multiple linear regression analysis showed that the number of cardiovascular risk factors was the only independent predictive variable associated with FMD (β: -0.585; P < .001; R(2) = 35%) and sNOX2-dp (β: 0.587; P < .001; R(2) = 34%). The study suggests that NOX2-generating oxidative stress may have a pathogenic role in the functional changes of the arterial wall occurring in HOC.

Different behaviour of NOX2 activation in patients with paroxysmal/persistent or permanent atrial fibrillation

BackgroundNOX2, the catalytic subunit of NADPH oxidase, is suggested to play a role in favouring the occurrence of atrial fibrillation (AF) after cardiac surgery via formation of reactive oxidant species....

Osteopontin Plays a Critical Role in Interstitial Fibrosis but Not Glomerular Sclerosis in Diabetic Nephropathy

Background/Aims: Osteopontin (OPN) has been implicated in the pathology of several renal conditions. The aim of this study was to clarify the roles of OPN in diabetic nephropathy. Methods: Diabetes mellitus (DM) was induced in wild-type (WT) and OPN knockout (KO) mice by injecting streptozotocin. The mice were killed 20 weeks after induction of DM and their kidneys removed. Results: Renal mRNA expression of OPN was increased in WT-DM mice compared to WT-sham mice. Immunohistochemistry showed high levels of OPN expression in the proximal tubules of WT-DM mice. Kidney weight and urinary albumin excretion increased to similar levels in the WT-DM and KO-DM mice. Interstitial fibrosis was increased in WT-DM mice compared to KO-DM mice. However, there were no differences in the degree of mesangial expansion or glomerular hypertrophy between the two groups. F4/80-positive cells (macrophages) and FSP-1-positive cells (fibroblasts) showed significantly higher infiltration in WT-DM mice than in KO-DM mice. Renal mRNA expression of NADPH oxidase subunits and urinary 8-isoprostane excretion were also increased in WT-DM mice. Conclusions: These results indicated that OPN is a key molecule that induces interstitial fibrosis in the diabetic kidney, but does not induce glomerular sclerosis.

Prediabetic Nephropathy as an Early Consequence of the High-Calorie/High-Fat Diet: Relation to Oxidative Stress

This study evaluated early renal functional, structural, and biochemical changes in high-calorie/high-fat diet fed mice, a model of prediabetes and alimentary obesity. Male C57BL6/J mice were fed normal (11 kcal% fat) or high-fat (58 kcal% fat) diets for 16 wk. Renal changes were evaluated by histochemistry and immunohistochemistry, Western blot analysis, ELISA, enzymatic assays, and chemiluminometry. High-fat diet consumption led to increased body and kidney weights, impaired glucose tolerance, hyperinsulinemia, polyuria, a 2.7-fold increase in 24-h urinary albumin excretion, 20% increase in renal glomerular volume, 18% increase in renal collagen deposition, and 8% drop of glomerular podocytes. It also resulted in a 5.3-fold increase in urinary 8-isoprostane excretion and a 38% increase in renal cortex 4-hydroxynonenal adduct accumulation. 4-hydroxynonenal adduct level and immunoreactivity or Sirtuin 1 expression in renal medulla were not affected. Studies of potential mechanisms of the high-fat diet induced renal cortex oxidative injury revealed that whereas nicotinamide adenine dinucleotide phosphate reduced form oxidase activity only tended to increase, 12/15-lipoxygenase was significantly up-regulated, with approximately 12% increase in the enzyme protein expression and approximately 2-fold accumulation of 12(S)-hydroxyeicosatetraenoic acid, a marker of 12/15-lipoxygenase activity. Accumulation of periodic acid-Schiff -positive material, concentrations of TGF-β, sorbitol pathway intermediates, and expression of nephrin, CAAT/enhancer-binding protein homologous protein, phosphoeukaryotic initiation factor-α, and total eukaryotic initiation factor-α in the renal cortex were indistinguishable between experimental groups. Vascular endothelial growth factor concentrations were reduced in high-fat diet fed mice. In conclusion, systemic and renal cortex oxidative stress associated with 12/15-lipoxygenase overexpression and activation is an early phenomenon caused by high-calorie/high-fat diet consumption and a likely contributor to kidney disease associated with prediabetes and alimentary obesity.

Estrogen Receptor GPR30 Reduces Oxidative Stress and Proteinuria in the Salt-Sensitive Female mRen2.Lewis Rat

The current study assessed whether activation of the novel estrogen receptor GPR30 ameliorates salt-dependent renal damage in intact mRen2.Lewis (mRen2) females. Hemizygous mRen2 rats were maintained on either a normal salt (0.5% Na) or high-salt (HS; 4.0% Na) diet for 10 weeks (5 to 15 weeks of age), and HS animals were treated with the GPR30 agonist G-1 or vehicle for 2 weeks. Systolic blood pressure markedly increased with HS diet (149±3 to 219±5 mm Hg; P<0.01), but G-1 did not influence pressure (P=0.42). G-1 and estradiol induced relaxation of preconstricted mesenteric vessels from normal salt mRen2 rats, but both responses were attenuated in the HS group. Despite the lack of an effect on blood pressure, G-1 decreased renal hypertrophy, proteinuria, urinary 8-isoprostane excretion, and tubular 4-hydroxynonenal staining. HS diet significantly increased GPR30 mRNA (1.01±0.04 versus 1.59±0.13; P<0.01) and protein (0.60±0.31 versus 3.99±0.75; P<0.01) in the renal cortex. GPR30 was highly expressed in the brush border of proximal tubules and colocalized with megalin. Finally, megalin expression was reduced by HS diet and restored with G-1. We conclude that GPR30-mediated beneficial effects in salt-sensitive mRen2 females occurred independent of changes in systolic blood pressure. The failure of G-1 to influence pressure may reflect a salt-induced impairment in GPR30-mediated vasorelaxation. The renoprotective actions of GPR30 may involve attenuation of tubular oxidative stress and activation of megalin-mediated protein reabsorption.