Phosphate Oxidase Activity Research Articles

Oxidative stress, point-of-care test, and metabolic syndrome

Oxidative stress, point-of-care test, and metabolic syndrome

Abstract 9630: HMG-CoA Reductase Inhibitor Pitavastatin Enhances Renoprotective Effects of Angiotensin Receptor1 Blocker Olmesartan In Salt-Sensitive Hypertensive Rats

Objective: The present studies was undertaken to investigate the potential effect of a statin to enhance the inhibitory effect of an ARB on renal injury and the cellular mechanism of theeffect of ARB on renal remodeling and proteinuria. Methods and Results: Dahl salt-sensitive (DS) rats on a high-salt diet were randomly assigned to four groups ( n = 10 for each group) that were treated with either vehicle (0.5% carboxymethyl cellulose), a low or high dosage of olmesartan (1 or 3 mg/kg/d), or pitavastatin (1 mg/kg/d) plus olmesartan (1 mg/kg/d) from 12 to 19 weeks of age. Rats fed a low-salt diet served as age-matched controls. Rats on the high-salt diet developed massive proteinuria and glomerulosclerosis, and these changes were attenuated by olmesartan in a dose-dependent manner. The amounts of mRNAs for AT1R, mineralocorticoid receptor (MR), osteopontin, monocyte chemoattractant protein-1 and collagen type I, and the activities for matrix metalloproteinase-9 and cathepsin S were significantly higher in the failing kidneys of vehicle-treated rats than in the age-matched control rats; olmesartan significantly attenuated these changes. Olmesartan attenuated both the decrease in the ratio of reduced glutathione to oxidized glutathione and the increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity apparent in the kidney cortex of vehicle-treated rats. Furthermore, olmesartan inhibited kidney cortex vascular inflammation and renal fibrosis. The addition of pitavastatin significantly enhanced these beneficial effects by AT1R antagonism via anti-inflammation and anti-proteolysis. Conclusions: The beneficial renal effects of AT1R antagonism are likely attributable, at least in part, to the attenuation of renal oxidative stress and renal vascular inflammation induced by the AT1R-MR signaling interaction. The combination of statin with angiotensin receptor blocker (ARB) may be a potential therapeutic strategy for renal injury with proteinuria.

Rac-Null Leukocytes Are Associated with Increased Inflammation-Mediated Alveolar Bone Loss

Periodontitis is characterized by altered host-biofilm interactions that result in irreversible inflammation-mediated alveolar bone loss. Genetic and epigenetic factors that predispose to ineffective control of biofilm composition and maintenance of tissue homeostasis are not fully understood. We elucidated how leukocytes affect the course of periodontitis in Rac-null mice. Mouse models of acute gingivitis and periodontitis were used to assess the early inflammatory response and patterns of chronicity leading to loss of alveolar bone due to inflammation in Rac-null mice. Leukocyte margination was differentially impaired in these mice during attachment in conditional Rac1-null (granulocyte/monocyte lineage) mice and during rolling and attachment in Rac2-null (all blood cells) mice. Inflammatory responses to subgingival ligatures, assessed by changes in peripheral blood differential leukocyte numbers, were altered in Rac-null compared with wild-type mice. In response to persistent subgingival ligature-mediated challenge, Rac-null mice had increased loss of alveolar bone with patterns of resorption characteristic of aggressive forms of periodontitis. These findings were partially explained by higher osteoclastic coverage of the bone-periodontal ligament interface in Rac-null compared with wild-type mice. In conclusion, this study demonstrates that leukocyte defects, such asdecreased endothelial margination and tissue recruitment, are rate-limiting steps in the periodontal inflammatory process that lead to more aggressive forms of periodontitis.

HOE-140, an antagonist of B2 receptor, protects against memory deficits and brain damage induced by moderate lateral fluid percussion injury in mice

There are evidences indicating the role of kinins in pathophysiology of traumatic brain injury, but little is known about their action on memory deficits. Our aim was to establish the role of bradykinin receptors B₁ (B₁R) and B₂ (B₂R) on the behavioral, biochemical, and histologic features elicited by moderate lateral fluid percussion injury (mLFPI) in mice. The role of kinin B₁ and B₂ receptors in brain damage, neuromotor, and cognitive deficits induced by mLFPI, was evaluated by means of subcutaneous injection of B₂R antagonist (HOE-140; 1 or 10 nmol/kg) or B₁R antagonist (des-Arg9-[Leu8]-bradykinin (DAL-Bk; 1 or 10 nmol/kg) 30 min and 24 h after brain injury. Brain damage was evaluated in the cortex, being considered as lesion volume, inflammatory, and oxidative damage. The open field and elevated plus maze tests were performed to exclude the nonspecific effects on object recognition memory test. Our data revealed that HOE-140 (10 nmol/kg) protected against memory impairment. This treatment attenuated the brain edema, interleukin-1β, tumor necrosis factor-α, and nitric oxide metabolites content elicited by mLFPI. Accordingly, HOE-140 administration protected against the increase of nicotinamide adenine dinucleotide phosphate oxidase activity, thiobarbituric-acid-reactive species, protein carbonylation generation, and Na⁺ K⁺ ATPase inhibition induced by trauma. Histologic analysis showed that HOE-140 reduced lesion volume when analyzed 7 days after brain injury. This study suggests the involvement of the B₂ receptor in memory deficits and brain damage caused by mLFPI in mice.

Histone Deacetylase 4 Controls Neointimal Hyperplasia via Stimulating Proliferation and Migration of Vascular Smooth Muscle Cells

Histone deacetylases (HDACs) are transcriptional coregulators. Recently, we demonstrated that HDAC4, one of class IIa family members, promotes reactive oxygen species-dependent vascular smooth muscle inflammation and mediates development of hypertension in spontaneously hypertensive rats. Pathogenesis of hypertension is, in part, modulated by vascular structural remodeling via proliferation and migration of vascular smooth muscle cells (SMCs). Thus, we examined whether HDAC4 controls SMC proliferation and migration. In rat mesenteric arterial SMCs, small interfering RNA against HDAC4 inhibited platelet-derived growth factor (PDGF)-BB-induced SMC proliferation as determined by a cell counting and bromodeoxyuridine incorporation assay as well as migration as determined by Boyden chamber assay. Expression and activity of HDAC4 were increased by PDGF-BB. HDAC4 small interfering RNA inhibited phosphorylation of p38 mitogen-activated protein kinase and heat shock protein 27 and expression of cyclin D1 as measured by Western blotting. HDAC4 small interfering RNA also inhibited PDGF-BB-induced reactive oxygen species production as measured fluorometrically using 2', 7'-dichlorofluorescein diacetate and nicotinamide adenine dinucleotide phosphate oxidase activity as measured by lucigenin assay. A Ca(2+)/calmodulin-dependent protein kinase II inhibitor, KN93, inhibited PDGF-BB-induced SMC proliferation and migration as well as phosphorylation of HDAC4. In vivo, a class IIa HDACs inhibitor, MC1568 prevented neointimal hyperplasia in mice carotid ligation model. MC1568 also prevented increased activation of HDAC4 in the neointimal lesions. The present results for the first time demonstrate that HDAC4 controls PDGF-BB-induced SMC proliferation and migration through activation of p38 mitogen-activated protein kinase/heat shock protein 27 signals via reactive oxygen species generation in a Ca(2+)/calmodulin-dependent protein kinase-dependent manner, which may lead to the neointimal hyperplasia in vivo.

Chronic Escitalopram Treatment Induces Erectile Dysfunction by Decreasing Nitric Oxide Bioavailability Mediated by Increased Nicotinamide Adenine Dinucleotide Phosphate Oxidase Activity and Reactive Oxygen Species Production

To investigate the effects of escitalopram, a selective serotonin reuptake inhibitor, on erectile and penile vascular function in the rat. The effect of chronic treatment with escitalopram (0.286 mg/kg/day) on change in intracavernosal pressure, maximum intracavernosal pressure/mean arterial pressure, and area under the intracavernosal pressure curve in response to cavernosal nerve stimulation was measured. The effect of chronic escitalopram treatment on endothelial-dependent relaxant responses was investigated in isolated mesenteric and internal pudendal resistance arteries. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and nitric oxide synthase levels were determined with enzymatic assay and Western blot, respectively. Chronic treatment with escitalopram resulted in a significant reduction in the erectile response to cavernosal nerve stimulation without an effect on the response to intracavernosal injection of the nitric oxide donor sodium nitroprusside. The decrease in erectile function was associated with marked increases in NADPH oxidase activity in the corpora cavernosa. Treatment with escitalopram also caused a significant reduction in the relaxant response to acetylcholine in isolated internal pudendal and mesenteric resistance arteries without altering the response to sodium nitroprusside. The decreased response to acetylcholine in the isolated vascular segments was associated with a marked increase in NADPH oxidase activity that was corrected by treatment with the NAPDH oxidase inhibitor apocynin. The inhibitory effects of escitalopram on erectile and vascular function were not accompanied by a change in endothelial nitric oxide synthase, neuronal nitric oxide synthase, inducible nitric oxide synthase expression, or endothelial nitric oxide synthase activity, suggesting that the inhibitory effect is caused by a decrease in nitric oxide bioavailability mediated by increased NADPH oxidase and reactive oxygen species production.

Bradykinin Inhibits Oxidative Stress-Induced Cardiomyocytes Senescence via Regulating Redox State

BackgroundCell senescence is central to a large body of age related pathology, and accordingly, cardiomyocytes senescence is involved in many age related cardiovascular diseases. In consideration of that, delaying cardiomyocytes senescence is of great importance to control clinical cardiovascular diseases. Previous study indicated that bradykinin (BK) protected endothelial cells from senescence induced by oxidative stress. However, the effects of bradykinin on cardiomyocytes senescence remain to be elucidated. In this study, we investigated the effect of bradykinin on H2O2-induced H9C2 cells senescence.Methods and ResultsBradykinin pretreatment decreased the senescence induced by H2O2 in cultured H9C2 cells in a dose dependent manner. Interestingly, 1 nmol/L of BK almost completely inhibited the increase in senescent cell number and p21 expression induced by H2O2. Since H2O2 induces senescence through superoxide-induced DNA damage, we also observed the DNA damage by comet assay, and BK markedly reduced DNA damage induced by H2O2, and moreover, BK treatment significantly prevented reactive oxygen species (ROS) production in H9C2 cells treated with H2O2. Importantly, when co-incubated with bradykinin B2 receptor antagonist HOE-140 or eNOS inhibitor N-methyl-L-arginine acetate salt (L-NAME), the protective effects of bradykinin on H9C2 senescence were totally blocked. Furthermore, BK administration significantly prevented the increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity characterized by increased ROS generation and gp91 expression and increased translocation of p47 and p67 to the membrane and the decrease in superoxide dismutase (SOD) activity and expression induced by H2O2 in H9C2 cells, which was dependent on BK B2 receptor mediated nitric oxide (NO) release.ConclusionsBradykinin, acting through BK B2 receptor induced NO release, upregulated antioxidant Cu/Zn-SOD and Mn-SOD activity and expression while downregulating NADPH oxidase activity and subsequently inhibited ROS production, and finally protected against cardiomyocytes senescence induced by oxidative stress.

Ligation of Signal Inhibitory Receptor on Leukocytes-1 Suppresses the Release of Neutrophil Extracellular Traps in Systemic Lupus Erythematosus

Neutrophil extracellular traps (NETs) have been implicated in the pathogenesis of systemic Lupus erythematosus (SLE), since netting neutrophils release potentially immunogenic autoantigens including histones, LL37, human neutrophil peptide (HNP), and self-DNA. In turn, these NETs activate plasmacytoid dendritic cells resulting in aggravation of inflammation and disease. How suppression of NET formation can be targeted for treatment has not been reported yet. Signal Inhibitory Receptor on Leukocytes-1 (SIRL-1) is a surface molecule exclusively expressed on phagocytes. We recently identified SIRL-1 as a negative regulator of human neutrophil function. Here, we determine whether ligation of SIRL-1 prevents the pathogenic release of NETs in SLE. Peripheral blood neutrophils from SLE patients with mild to moderate disease activity and healthy donors were freshly isolated. NET release was assessed spontaneously or after exposure to anti-neutrophil antibodies or plasma obtained from SLE patients. The formation of NETs was determined by microscopic evaluation using DNA dyes and immunostaining of NET components, as well as by live cell imaging. We show that SLE neutrophils spontaneously release NETs. NET formation is enhanced by stimulation with antibodies against LL37. Inhibition of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and MEK-ERK signaling prevents NET release in response to these antibodies. Signaling via the inhibitory receptor SIRL-1 was induced by ligation with anti-SIRL-1 specific antibodies. Both spontaneous and anti-neutrophil antibody-induced NET formation is suppressed by engagement of SIRL-1. Furthermore, NET release by healthy neutrophils exposed to SLE plasma is inhibited by SIRL-1 ligation. Thus, SIRL-1 engagement can dampen spontaneous and anti-neutrophil antibody-induced NET formation in SLE, likely by suppressing NAPDH oxidase and MEK-ERK activity. Together, these findings reveal a regulatory role for SIRL-1 in NET formation, potentially providing a novel therapeutic target to break the pathogenic loop in SLE.

Palmitate induces reactive oxygen species production and β-cell dysfunction by activating nicotinamide adenine dinucleotide phosphate oxidase through Src signaling.

Chronic hyperlipidemia impairs pancreatic β-cell function, referred to as lipotoxicity. We have reported an important role of endogenous reactive oxygen species (ROS) overproduction by activation of Src, a non-receptor tyrosine kinase, in impaired glucose-induced insulin secretion (GIIS) from diabetic rat islets. In the present study, we investigated the role of ROS production by Src signaling in palmitate-induced dysfunction of β-cells. After rat insulinoma INS-1D cells were exposed to 0.6mmol/L palmitate for 24h (palmitate exposure); GIIS, ROS production and nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity were examined with or without exposure to10μmol/L 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2), a Src inhibitior, for 30 or 60min. Exposure to PP2 recovered impaired GIIS and decreased ROS overproduction as a result of palmitate exposure. Palmitate exposure increased activity of NOX and protein levels of NOX2, a pathological ROS source in β-cells. Palmitate exposure increased the protein level of p47 (phox) , a regulatory protein of NOX2, in membrane fraction compared with control, which was reduced by PP2. Transfection of small interfering ribonucleic acid of p47 (phox) suppressed the augmented p47 (phox) protein level in membrane fraction, decreased augmented ROS production and increased impaired GΙIS by palmitate exposure. In addition, exposure to PP2 ameliorated impaired GIIS and decreased ROS production in isolated islets of KK-A(y) mice, an obese diabetic model with hyperlipidemia. Activation of NOX through Src signaling plays an important role in ROS overproduction and impaired GΙIS caused by chronic exposure to palmitate, suggesting a lipotoxic mechanism of β-cell dysfunction of obese mice.

Abstract 22: Histone Deacetylase (HDAC) 4 Controls Neointimal Hyperplasia via Stimulating Proliferation and Migration of Vascular Smooth Muscle Cells

Histone deacetylases (HDACs) are transcriptional co-regulators. We have recently demonstrated that a class IIa HDAC, HDAC4 promotes reactive oxygen species (ROS)-dependent vascular smooth muscle inflammation and mediates the development of hypertension in spontaneously hypertensive rats. Pathogenesis of hypertension is in part modulated by vascular structural remodeling via proliferation and migration of vascular smooth muscle cells (SMCs). We thus examined whether HDAC4 controls SMCs proliferation and migration. In rat mesenteric arterial SMCs, small interfering RNA (siRNA) against HDAC4 inhibited platelet-derived growth factor (PDGF)-BB-induced SMCs proliferation as determined by a cell counting (51% inhibition, n=7) or bromodeoxyuridine incorporation assay (95% inhibition, n=6) and migration as determined by Boyden chamber assay (71% inhibition, n=3). Expression and activity of HDAC4 were increased by PDGF-BB (30% increase, n=5 and 170% increase, n=4, respectively). HDAC4 siRNA inhibited phosphorylation of p38 (69% inhibition, n=5) and heat shock protein (HSP) 27 (91% inhibition, n=5) and expression of cyclin D1 (58% inhibition, n=5) as measured by Western blotting. HDAC4 siRNA also inhibited PDGF-BB-induce ROS production as measured fluorometrically using 2’ 7’-dichlorofluorescein diacetate (77% inhibition, n=4) and nicotinamide adenine dinucleotide phosphate oxidase activity as measured by lucigenin assay (61% inhibition, n=4). A Ca 2+ /calmodulin (CaM)-dependent protein kinase (CaMK) II inhibitor, KN93 inhibited PDGF-BB-induced SMCs proliferation (58% inhibition, n=4) and migration (75% inhibition, n=3) as well as phosphorylation of HDAC4 (84% inhibition, n=4). In vivo, a class IIa HDACs inhibitor, MC1568 prevented neointimal hyperplasia in mice carotid ligation model (54% inhibition, n=6). MC1568 also inhibited increased activity of HDAC4 in the neointimal lesions. The present results for the first time demonstrate that HDAC4 controls PDGF-BB-induced SMCs proliferation and migration through activation of p38/HSP27 signals via ROS generation in a CaMKII-dependent manner, which may lead to the neointima hyperplasia in vivo.

Inhibition of Src tyrosine kinase activity by squamosamide derivative FLZ attenuates neuroinflammation in both in vivo and in vitro Parkinson's disease models

The participation of neuroinflammation in the pathogenesis of Parkinson's disease (PD) has long been validated. Excessive activated microglia release a large number of pro-inflammatory factors, damage surrounding neurons and eventually induce neurodegeneration. Inhibition of microglial over-activation might be a promising strategy for PD treatment. FLZ (formulated as: N-(2-(4-hydroxy-phenyl)-ethyl)-2-(2, 5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide, the code name: FLZ), a natural squamosamide derivative from a Chinese herb, has been shown to inhibit over-activated microglia and protect dopaminergic neurons in previous studies, but the mechanism remains unclear. In the present study, we further investigated the mechanism in lipopolysaccharide (LPS)-induced in vivo and in vitro PD models. FLZ treatment significantly improved the motor dysfunction of PD model rats induced by intra-nigral injection of LPS and this beneficial effect of FLZ attributed to the inhibition of microglial over-activation and the protection on dopaminergic neurons in the substantia nigra (SN). In vitro mechanistic study revealed that the inhibitive effect of FLZ on microglia was mediated by suppressing Src kinase related inflammatory signaling pathway activation and subsequent NF-κBp65 nuclear translocation, inhibiting nitric oxide (NO) and reactive oxygen species (ROS) production, decreasing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. In conclusion, the present study supports that FLZ exerts neuroprotection against LPS-induced dopaminergic neurodegeneration through its anti-inflammatory effect, which is mediated by suppressing Src tyrosine kinase and the downstream inflammatory signaling pathway. Furthermore, this study defines a critical role of Src tyrosine kinase in neuroinflammation, and suggests that particular tyrosine kinase inhibition may be a potential anti-inflammatory approach for PD treatment.

Salinity-Induced Calcium Signaling and Root Adaptation in Arabidopsis Require the Calcium Regulatory Protein Annexin1

Salinity (NaCl) stress impairs plant growth and inflicts severe crop losses. In roots, increasing extracellular NaCl causes Ca²⁺ influx to elevate cytosolic free Ca²⁺ ([Ca²⁺](cyt)) as a second messenger for adaptive signaling. Amplification of the signal involves plasma membrane reduced nicotinamide adenine dinucleotide phosphate oxidase activation, with the resultant reactive oxygen species triggering Ca²⁺ influx. The genetic identities of the Ca²⁺-permeable channels involved in generating the [Ca²⁺](cyt) signal are unknown. Potential candidates in the model plant Arabidopsis (Arabidopsis thaliana) include annexin1 (AtANN1). Here, luminescent detection of [Ca²⁺](cyt) showed that AtANN1 responds to high extracellular NaCl by mediating reactive oxygen species-activated Ca²⁺ influx across the plasma membrane of root epidermal protoplasts. Electrophysiological analysis revealed that root epidermal plasma membrane Ca²⁺ influx currents activated by NaCl are absent from the Atann1 loss-of-function mutant. Both adaptive signaling and salt-responsive production of secondary roots are impaired in the loss-of-function mutant, thus identifying AtANN1 as a key component of root cell adaptation to salinity.

Defects in neutrophil granule mobilization and bactericidal activity in familial hemophagocytic lymphohistiocytosis type 5 (FHL-5) syndrome caused by STXBP2/Munc18-2 mutations

AbstractFamilial hemophagocytic lymphohistiocytosis (FHL) is caused by genetic defects in cytotoxic granule components or their fusion machinery, leading to impaired natural killer cell and/or T lymphocyte degranulation and/or cytotoxicity. This may accumulate into a life-threatening condition known as macrophage activation syndrome. STXBP2, also known as MUNC18-2, has recently been identified as the disease-causing gene in FHL type 5 (FHL-5). A role for STXBP2 in neutrophils, and for neutrophils in FHL in general, has not been documented thus far. Here, we report that FHL-5 neutrophils have a profound defect in granule mobilization, resulting in inadequate bacterial killing, in particular, of gram-negative Escherichia coli, but not of Staphylococcus aureus, which rather depends on intact reduced NAD phosphate oxidase activity. This impairment of bacterial killing may contribute to the apparent susceptibility to gastrointestinal tract inflammation in patients with FHL-5.

Loss of p47 phox Subunit Enhances Susceptibility to Biomechanical Stress and Heart Failure Because of Dysregulation of Cortactin and Actin Filaments

Rationale: The classic phagocyte nicotinamide adenine dinucleotide phosphate oxidase (gp91 phox or Nox2) is expressed in the heart. Nox2 activation requires membrane translocation of the p47 phox subunit and is linked to heart failure. We hypothesized that loss of p47 phox subunit will result in decreased reactive oxygen species production and resistance to heart failure. Objective: To define the role of p47 phox in pressure overload–induced biomechanical stress. Methods and Results: Eight-week-old male p47 phox null (p47 phox knockout [KO]), Nox2 null (Nox2KO), and wild-type mice were subjected to transverse aortic constriction–induced pressure overload. Contrary to our hypothesis, p47 phox KO mice showed markedly worsened systolic dysfunction in response to pressure overload at 5 and 9 weeks after transverse aortic constriction compared with wild-type–transverse aortic constriction mice. We found that biomechanical stress upregulated N-cadherin and β-catenin in p47 phox KO hearts but disrupted the actin filament cytoskeleton and reduced phosphorylation of focal adhesion kinase. p47 phox interacts with cytosolic cortactin by coimmunoprecipitation and double immunofluorescence staining in murine and human hearts and translocated to the membrane on biomechanical stress where cortactin interacted with N-cadherin, resulting in adaptive cytoskeletal remodeling. However, p47 phox KO hearts showed impaired interaction of cortactin with N-cadherin, resulting in loss of biomechanical stress–induced actin polymerization and cytoskeletal remodeling. In contrast, Nox2 does not interact with cortactin, and Nox2-deficient hearts were protected from pressure overload–induced adverse myocardial and intracellular cytoskeletal remodeling. Conclusions: We showed a novel role of p47 phox subunit beyond and independent of nicotinamide adenine dinucleotide phosphate oxidase activity as a regulator of cortactin and adaptive cytoskeletal remodeling, leading to a paradoxically enhanced susceptibility to biomechanical stress and heart failure.

Oxidative Stress–Mediated Thrombospondin-2 Upregulation Impairs Bone Marrow–Derived Angiogenic Cell Function in Diabetes Mellitus

Circulating angiogenic cells play an essential role in angiogenesis but are dysfunctional in diabetes mellitus characterized by excessive oxidative stress. We hypothesize that oxidative stress-mediated upregulation of thrombospondin-2 (TSP-2), a potent antiangiogenic protein, contributes to diabetic bone marrow-derived angiogenic cell (BMAC) dysfunction. BMACs were isolated from adult male type 2 diabetic db/db mice and control db/+ (C57BLKS/J) mice. In Matrigel tube formation assay, angiogenic function was impaired in diabetic BMACs, accompanied by increased oxidative stress and nicotinamide adenine dinucleotide phosphate oxidase activity. BMAC angiogenic function was restored by overexpression of dominant negative Rac1 or by overexpression of manganese superoxide dismutase. TSP-2 mRNA and protein were both significantly upregulated in diabetic BMACs, mediated by increased oxidative stress as shown by a decrease in TSP-2 level after overexpression of dominant negative Rac1 or manganese superoxide dismutase. Silencing TSP-2 by its small interfering RNA in diabetic BMACs improved BMAC function in tube formation, adhesion, and migration assays. Notably, the upregulation of TSP-2 was also found in BMACs from streptozotocin-induced type 1 diabetic mice, and normal BMACs with high glucose treatment. let-7f, a microRNA which has been related to endothelial angiogenic function, is found to play key role in TSP-2 increase, but let-7f did not directly interact with TSP-2 mRNA. The upregulation of TSP-2 mediated by increased oxidative stress contributes to angiogenesis dysfunction in diabetic BMACs.

Heme Oxygenase Inhibition Increases Blood Pressure in Pregnant Rats

During normal gestation, the placenta is a relatively hypoxic organ and, as such, is subject to significant oxidative stress. In the preeclamptic patient, inadequate remodeling of the maternal vasculature severely exacerbates placental oxidative stress, which has been shown to be an important component of maternal hypertension. There is emerging evidence that Heme Oxygenase-1 (HO-1) acts as an important regulator of placental and cardiovascular function during normal pregnancy. Here, we have examined the effect of Heme Oxygenase (HO) inhibition in late gestation on maternal blood pressure, angiogenic balance, and placental oxidative stress in pregnant rats. HO activity was inhibited with tin mesoporphyrin (SnMP), which was administered on gestational day 14, and blood pressure was measured on gestational day 19. Placental angiogenic balance and plasma Vascular Endothelial Growth Factor (VEGF) were determined by sandwich enzyme-linked immunosorbent assay. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was measured by lucigenin chemilluminescence. In response to SnMP treatment, maternal mean arterial pressure (MAP) was significantly increased (99±1 vs. 113±2mm Hg; P < 0.05; n = 15 per group). Placental soluble fms-like tyrosine kinase-1 (sFlt-1) (631±47 vs. 648±26 pg/mg; P = 0.76) levels in the placenta were not affected by HO inhibition. Additionally, there was no significant difference in free VEGF in the maternal circulation (287±22 vs. 329±14 pg/ml; P = 0.11). There was, however, a significant decrease in placental VEGF (23±2 vs. 16±1 pg/mg; P < 0.05) and a significant increase in placental NADPH oxidase activity in SnMP-treated rats (2021±238 vs. 3005±301 RLU/min/mg; P < 0.05). Our results demonstrate that HO is an important regulator of blood pressure and an important antioxidant in the developing placenta.

Role of T Regulatory Lymphocytes in the Pathogenesis of High-Fructose Diet–Induced Metabolic Syndrome

We recently showed that T regulatory lymphocytes (Treg), which are immune suppressors of inflammatory responses, play a role blunting the development of hypertension-induced injury. Treg are unchanged or decreased in children with metabolic syndrome, and therefore, their role in metabolic syndrome remains unclear. We hypothesized that Treg number or function would be depressed in a high-fructose diet-induced metabolic syndrome-like model in rats. Sprague-Dawley rats were fed normal chow or a high-fructose diet for 5 weeks. The high-fructose diet-induced a 3.8-fold increase in plasma triglycerides and a 14% reduction in high-density lipoprotein cholesterol (P<0.001). The high-fructose diet increased reactive oxygen species in aorta and periaortic adipose tissue 2.8-fold (P<0.05), and reduced nicotinamide adenine dinucleotide phosphate oxidase activity 1.9-fold in aorta, and 2.5-fold in the heart (P<0.05). It also increased plasma nitric oxide metabolite levels 6.4-fold (P<0.001). Western blots showed that the high-fructose diet increased ≥2.3-fold vascular and in platelet endothelial cell adhesion molecule 1 in aorta (P<0.01). It did not affect monocyte/macrophage aortic infiltration but caused a 2.4-fold increase in collagen deposition in the aortic media (P<0.01). No change in plasma interleukin-10 was detected. The percentage of spleen CD4+ CD25- and Treg (CD4+ CD25(high)) cells was unaltered by the high-fructose diet. However, cultured Treg from high-fructose diet-fed rats secreted 62% less interleukin-10 than control cells (P<0.05), suggesting a decreased Treg function, which could play a role in the development of cardiovascular complications of the metabolic syndrome.

Synergetic Neuroprotection of Normobaric Oxygenation and Ethanol in Ischemic Stroke Through Improved Oxidative Mechanism

Normobaric oxygenation (NBO) and ethanol both provide neuroprotection in stroke. We evaluated the enhanced neuroprotective effect of combining these 2 treatments in a rat stroke model. Sprague-Dawley rats were subjected to middle cerebral artery occlusion for 2 hours. Reperfusion was then established and followed by treatment with either (1) an intraperitoneal injection of ethanol (1.0 g/kg), (2) NBO treatment (2-hour duration), or (3) NBO plus ethanol. The extent of brain injury was determined by infarct volume and motor performance. Oxidative metabolism was determined by ADP/ATP ratios, reactive oxygen species levels, nicotinamide adenine dinucleotide phosphate oxidase activity, and pyruvate dehydrogenase activity. Protein expression of major nicotinamide adenine dinucleotide phosphate oxidase subunits (p47(phox), gp91(phox), and p67(phox)) and the enzyme pyruvate dehydrogenase was evaluated through Western immunoblotting. NBO and ethanol monotherapies each demonstrated reductions as compared to stroke without treatment in infarct volume (36.7% and 37.9% vs 48.4%) and neurological deficits (score of 6.4 and 6.5 vs 8.4); however, the greatest neuroprotection (18.8% of infarct volume and 4.4 neurological deficit) was found in animals treated with combination therapy. This neuroprotection was associated with the largest reductions in ADP/ATP ratios, reactive oxygen species levels, and nicotinamide adenine dinucleotide phosphate oxidase activity, and the largest increase in pyruvate dehydrogenase activity. Combination therapy with NBO and ethanol enhances the neuroprotective effect produced by each therapy alone. The mechanism behind this synergistic action is related to changes in cellular metabolism after ischemia reperfusion. NBO plus ethanol is attractive for clinical study because of its ease of use, tolerability, and tremendous neuroprotective potential in stroke.

Neuroprotection conferred by post‐ischemia ethanol therapy in experimental stroke: an inhibitory effect on hyperglycolysis and NADPH oxidase activation

Ethanol provides neuroprotection following ischemia/reperfusion. This study assessed ethanol's effect on hyperglycolysis and NADPH oxidase (NOX) activation. Adult, male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h. Three sets of experiments were conducted to determine ethanol's effect on (i) conferring neuroprotection by measuring infarct volume and neurological deficits 24 h post reperfusion; (ii) cerebral glucose metabolism and lactic acidosis by measuring brain and blood glucose concentrations and protein expression of glucose transporter 1 and 3 (GLUT1, GLUT3), phosphofructokinase (PFK), as well as lactic acidosis by measuring lactate dehydrogenase (LDH), and lactate; and (iii) nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activation by detecting enzymatic activity and subunit expression at 3 h after reperfusion. When administered upon reperfusion, ethanol (1.5 g/kg) reduced infarct volume by 40% (p < 0.01) and neurological deficits by 48% at 24 h post reperfusion while reducing (p < 0.01) elevations in glycolytic protein expression and lactate levels during early reperfusion (3 h). Ethanol increased the reductions in cerebral glucose concentration at 3 h post reperfusion by 64% (p < 0.01) while enhancing (p < 0.01) post stroke blood glucose concentration, suggesting a reduced cellular glucose uptake and utilization. Ethanol decreased (p < 0.01) stroke-induced NOX activation by reducing enzymatic activity and gp91(phox) expression by 45% and 38%, respectively. Post-ischemia ethanol treatment exerts neuroprotection through attenuation of hyperglycolysis and associated NOX activation. Because of the lack of associated hypoglycemia and selectivity toward decreasing cerebral metabolism, further investigation of ethanol's use as a post-stroke therapy, especially in the context of hyperglycemia, seems warranted.

Magnolol Protects Against Oxidative Stress-Mediated Neural Cell Damage by Modulating Mitochondrial Dysfunction and PI3K/Akt Signaling

Magnolol, an orally available compound from Magnolia officinalis used widely in traditional herbal medicine against a variety of neuronal diseases, possesses potent antioxidant properties and protects the brain against oxidative damage. The aim of the work is to examine the protective mechanisms of magnolol on human neuroblastoma SH-SY5Y cells against apoptosis induced by the neurotoxin acrolein, which can cause neurodegenerative disorders by inducing oxidative stress. By investigating the effect of magnolol on neural cell damage induced by the neurotoxin acrolein, we found that magnolol pretreatment significantly attenuated acrolein-induced oxidative stress through inhibiting reactive oxygen species accumulation caused by intracellular glutathione depletion and nicotinamide adenine dinucleotide phosphate oxidase activation. We next examined the signaling cascade(s) involved in magnolol-mediated antiapoptotic effects. The results showed that acrolein induced SH-SY5Y cell apoptosis by activating mitochondria/caspase and MEK/ERK signaling pathways. Our findings provide the first evidence that magnolol protects SH-SY5Y cells against acrolein-induced oxidative stress and prolongs SH-SY5Y cell survival through regulating JNK/mitochondria/caspase, PI3K/MEK/ERK, and PI3K/Akt/FoxO1 signaling pathways.