Major Source Of Oxidative Stress Research Articles

NADPH oxidase 4 (Nox4) is a major source of oxidative stress in the failing heart

NAD(P)H oxidases (Noxs) produce O(2)(-) and play an important role in cardiovascular pathophysiology. The Nox4 isoform is expressed primarily in the mitochondria in cardiac myocytes. To elucidate the function of endogenous Nox4 in the heart, we generated cardiac-specific Nox4(-/-) (c-Nox4(-/-)) mice. Nox4 expression was inhibited in c-Nox4(-/-) mice in a heart-specific manner, and there was no compensatory up-regulation in other Nox enzymes. These mice exhibited reduced levels of O(2)(-) in the heart, indicating that Nox4 is a significant source of O(2)(-) in cardiac myocytes. The baseline cardiac phenotype was normal in young c-Nox4(-/-) mice. In response to pressure overload (PO), however, increases in Nox4 expression and O(2)(-) production in mitochondria were abolished in c-Nox4(-/-) mice, and c-Nox4(-/-) mice exhibited significantly attenuated cardiac hypertrophy, interstitial fibrosis and apoptosis, and better cardiac function compared with WT mice. Mitochondrial swelling, cytochrome c release, and decreases in both mitochondrial DNA and aconitase activity in response to PO were attenuated in c-Nox4(-/-) mice. On the other hand, overexpression of Nox4 in mouse hearts exacerbated cardiac dysfunction, fibrosis, and apoptosis in response to PO. These results suggest that Nox4 in cardiac myocytes is a major source of mitochondrial oxidative stress, thereby mediating mitochondrial and cardiac dysfunction during PO.

Involvement of NADPH oxidase in age-associated cardiac remodeling

Increased activation of the renin–angiotensin–aldosterone system (RAAS) and an increase in oxidative stress are both implicated in age-related cardiac remodeling but their precise interrelationship and linkage to underlying molecular and cellular abnormalities remain to be defined. Recent studies indicate that NADPH oxidases are major sources of oxidative stress and are activated by the RAAS. This study investigated the relationship between the NADPH oxidase system, age-related cardiac remodeling and its underlying mechanisms. We studied male Fisher 344 cross Brown Norway rats aged 2 months (young rats), 8 months (young adult rats) or 30 months (old rats). Aging-dependent increases in blood pressure, cardiomyocyte area, coronary artery remodeling and cardiac fibrosis were associated with increased myocardial NADPH oxidase activity attributable to the Nox2 isoform. These changes were accompanied by evidence of local RAAS activation, increased expression of connective tissue growth factor (CTGF) and TGF-β1, and a significant activation of MMP-2 and MT1-MMP. The changes in old rats were replicated in 8 month old rats that were chronically treated with angiotensin II for 28 days. Increased RAAS activation may drive age-related cardiac remodeling through the activation of Nox2 NADPH oxidase and subsequent increases in MMP activation, fibrosis and cardiomyocyte hypertrophy.

Antioxidant Defense to Hemolysis Is Organ-Specific and Reflects a Heterogeneity in Vascular Permeability in Sickle Cell Disease.

Abstract 1537Poster Board I-560Sickle cell disease (SCD) is characterized by intravascular hemolysis generating cell-free hemoglobin at concentrations that exceed the scavenging capabilities of heme-binding plasma proteins. Heme is a major source of oxidative stress, which is widely known to increase vascular permeability and cause tissue edema. Barrier disruptive effects of oxidative stress can however be counterbalanced by adaptive antioxidant defenses. Hitherto, the identity of specific antioxidant enzymes and cognate mechanisms protecting individual organs from oxidative stress in SCD remains poorly defined. In this study, microarray analysis was performed using non-toxic concentrations of hemin to analyze mechanisms of antioxidant defense by the endothelium. Multiple candidate antioxidant enzymes were identified each differentially elevated in several major organs in anemic SCD mice compared to non-anemic heterozygote and hemizygote littermates. Remarkably, none of the antioxidants was elevated in the brain of sickle mice. Moreover, the antioxidant phenotype in the kidney, spleen and liver of sickle mice were predominantly acute while the sickle lung was characterized by a predominantly chronic antioxidant phenotype. This latter finding was confirmed in SCD patients with chronic lung disease. Antioxidant enzyme activity was significantly higher in the lungs of adult sickle mice aged 3-6 months than in younger mice aged 4-6 weeks (p=0.004). However, this enhanced antioxidant activity declined significantly in middle-age mice 11-13 months old (p=0.005). Vascular permeability assessed by extravsasation of Evans blue dye was normal in the brain of sickle mice of all ages in agreement with our data indicating absence of oxidative stress in this organ. On the contrary, vascular permeability in the lung, kidney and heart of adult sickle mice was abnormally high. This abnormality deteriorated significantly exclusively in the lung (p= 0.04) but not in the heart or kidney in middle-age mice. Increased lung permeability in middle-age sickle mice was confirmed by overt tissue edema determined by lung wet/dry weight ratios. Our study has shown for the first time that the antioxidant response to the systemic chronic hemolysis of SCD is organ-specific. Furthermore, we have identified decline of antioxidant reserve concomitant with tissue edema as potential age-dependant risk factors for fatal lung complications in SCD. Finally, our data provide a framework to develop targeted antioxidant therapies to preserve organ function in SCD. DisclosuresNo relevant conflicts of interest to declare.

Proteomics analysis of protein expression and specific protein oxidation in human papillomavirus transformed keratinocytes upon UVB irradiation

Increasing evidence supports the role of oxidative stress in cancer development. Ultraviolet (UV) irradiation is one of the major sources of oxidative stress through the generation of reactive oxygen species (ROS). Besides the physiological function of ROS in cellular homeostasis, accumulating reports suggest that ROS are involved in all stages of multistep cancer development. In order to investigate the involvement of oxidative damage into the mechanisms of tumour progression, we used a parallel proteomic approach to analyse the protein expression profile and to identify oxidatively modified proteins in human papillomavirus (HPV)-transformed keratinocytes (HK-168 cells) upon ultraviolet B (UVB) exposure. The HK-168 cells were obtained from normal human epidermal keratinocytes transfected with the whole genome of the high-risk HPV type 16, unanimously recognized as an etiological agent of cervical carcinoma. Because of its year-long latency, this tumour offers a convenient model to study the role of environmental concurring agents in the multistep malignant progression. By the protein expression profile, we identified 21 proteins that showed different expression levels in HK-168 cells treated with UVB in comparison with untreated cells. Focusing on the oxidative modifications occurring at the protein level, we identified five proteins that showed elevated protein carbonyls levels: alpha-enolase, heat shock protein 75, annexin 2, elongation factor Tu and elongation factor gamma. Our results indicate that UVB-induced oxidative stress perturbs the normal redox balance and shifts HPV-transformed keratinocytes into a state in which the carbonylation of specific proteins is systematically induced. We suggest that UVB-induced modulation of protein expression combined with oxidative modification lead to protein dysfunction that might contribute to the malignant progression of transformed cells.

Silymarin, a Flavonoid from Milk Thistle (Silybum marianum L.), Inhibits UV‐induced Oxidative Stress Through Targeting Infiltrating CD11b+ Cells in Mouse Skin†

Phytochemicals have shown promise in inhibiting UV-induced oxidative stress, and therefore are considered as potent inhibitors of UV-induced oxidative stress-mediated skin diseases. We have shown previously that topical treatment of silymarin, a flavonoid from milk thistle (Silybum marianum), inhibits UV-induced oxidative stress in mouse skin. However, the cellular targets responsible for the inhibition of UV-induced oxidative stress by silymarin are not clearly defined. To address this issue, C3H/HeN mice were UV irradiated (90 mJ cm(-2)) with or without topical treatment with silymarin (1 mg cm(-2) skin area). Mice were killed 48 h later and skin samples collected. Flow cytometric analysis of viable dermal cells revealed that the number of infiltrating CD11b+ cells were the major source of oxidative stress (31.8%) in UV-irradiated skin compared with non-UV-exposed skin (0.4%). Treatment of silymarin inhibited UV-induced oxidative stress through inhibition of infiltrating CD11b+ cells. The analysis of myeloperoxidase also indicated that silymarin significantly (P < 0.001) decreased UV-induced infiltration of leukocytes, and this effect of silymarin was similar to that of intraperitoneal treatment of mice with monoclonal antibodies to CD11b. The inhibitory effect of silymarin, regardless of whether it is topically treated before or after UV irradiation, was of similar magnitude. Intraperitoneal administration of monoclonal antibodies to CD11b (rat IgG2b) to C3H/HeN mice inhibited UVB-induced oxidative stress generated by both epidermal and dermal cells as is evident by relative fluorescence intensity of oxidized rhodamine. Similar to the effect of anti-CD11b, silymarin also inhibited UV-induced oxidative stress in both epidermal and dermal cells. Further, CD11b+ and CD11b- cell subsets from UV-treated or silymarin+UV-treated mice were separated by immunomagnetic cell isolation technique from total epidermal and dermal single cell suspensions and analyzed for reactive oxygen species (ROS)/H2O2 production. Analytic data revealed that CD11b+ cell population from UV-irradiated skin resulted in significantly higher production of ROS in both epidermis and dermis than CD11b- cell population, and that silymarin inhibited UV-induced oxidative stress through targeting infiltrating the CD11b+ cell type in the skin.

No effect of cigarette smoking dose on oxidized plasma proteins

Cigarette smoking is a major source of oxidative stress. Protein carbonyls have been used as a biomarker of oxidative stress because of the relative stability of carbonylated proteins and the high protein concentration in blood. Increased levels of carbonyl groups have been found in serum proteins of smokers compared to nonsmokers. However, neither the dose effect of current cigarette smoke nor other predictors of oxidative stress have been studied. Hence, we used an Enzyme-Linked Immunosorbent Assay (ELISA) to evaluate plasma protein carbonyls in smokers recruited in the Early Lung Cancer Action Project (ELCAP) program. The lung cancer screening program enrolled current and former smokers age 60 years and over without a prior cancer diagnosis. A total of 542 participants (282 men and 260 women) completed a baseline questionnaire and provided blood samples for the biomarker study. Protein oxidation was measured by derivatization of the carbonyl groups with 2,4-dinitrophenylhydrazine (DNPH) and ELISA quantitation of the DNPH group. Current smoking status was confirmed with urinary cotinine. The mean (±S.D.) protein carbonyl level was 17.9±2.9 nmol carbonyl/ml plasma. Protein carbonyls did not differ significantly by gender. Carbonyl levels were higher among current than former smokers, but these differences did not attain statistical significance, nor did differences by urine cotinine levels, pack-years, pack/day among current smokers, and smoking duration. In a multiple regression analysis, higher protein carbonyl levels were independently associated with increasing age (0.59 nmol/ml increase per 10 years, 95% CI 0.14, 1.05, p=0.01), African-American vs. white race/ethnicity, (1.30 nmol/ml, 95% CI 0.4, 2.19, p=0.008), and lower educational attainment (0.75 nmol/ml, 95% CI 0.12, 1.38, p=0.02). Although we found no significant difference between current vs. past cigarette smoking and protein carbonyls in this older group of smokers, associations were found for age, ethnicity, and educational attainment. Our results indicate that the measurement of plasma carbonyls by this ELISA technique is still an easy and suitable method for studies of diseases related to oxidative stress.

Oxidative Stress Modulates Complement Factor H Expression in Retinal Pigmented Epithelial Cells by Acetylation of FOXO3

Age-related macular degeneration (AMD), the leading cause of severe vision loss in the elderly, is a complex disease that results from genetic modifications that increase susceptibility to environmental exposures. Smoking, a major source of oxidative stress, increases the incidence and severity of AMD, and antioxidants slow progression, suggesting that oxidative stress plays a major role. Polymorphisms in the complement factor H (CFH) gene that reduce activity of CFH increase the risk of AMD. In this study we demonstrate an interaction between these two risk factors, because oxidative stress reduces the ability of an inflammatory cytokine, interferon-gamma, to increase CFH expression in retinal pigmented epithelial cells. The interferon-gamma-induced increase in CFH is mediated by transcriptional activation by STAT1, and its suppression by oxidative stress is mediated by acetylation of FOXO3, which enhances FOXO3 binding to the CFH promoter, reduces its binding to STAT1, inhibits STAT1 interaction with the CFH promoter, and reduces expression of CFH. Expression of SIRT1, a mammalian homolog of NAD-dependent protein deacetylase sir2, attenuated FOXO3 recruitment to the CFH regulatory region and reversed the H(2)O(2)-induced repression of CFH gene expression. These data suggest an important interaction between environmental exposure and genetic susceptibility in the pathogenesis of AMD and, by elucidating molecular signaling involved in the interaction, provide potential targets for therapeutic intervention.

Pitavastatin ameliorates albuminuria and renal mesangial expansion by downregulating NOX4 in db/db mice

Recent studies have uncovered various pleiotrophic effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase-inhibiting drugs (statins). Several studies have identified a beneficial effect of statins on diabetic nephropathy; however, the molecular mechanisms are unclear. In this study, we show that statin ameliorates nephropathy in db/db mice, a rodent model of type 2 diabetes, via downregulation of NAD(P)H oxidase NOX4, which is a major source of oxidative stress in the kidney. Pitavastatin treatment for 2 weeks starting at 12 weeks of age significantly reduced albuminuria in the db/db mice concomitant with a reduction of urinary 8-hydroxy-2'-deoxyguanosine and 8-epi-prostaglandin F(2alpha). Immunohistochemical analysis found increased amounts of 8-hydroxy-2'-deoxyguanosine and NOX4 protein in the kidney of db/db mice. Quantitative reverse transcription-polymerase chain reaction also showed increased levels of NOX4 mRNA. Pitavastatin normalized all of these changes in the kidneys of diabetic animals. Additionally, 12-week treatment with the statin completely normalized the levels of transforming growth factor-beta1 and fibronectin mRNA as well as the mesangial expansion characteristic of diabetic nephropathy. Our study demonstrates that pitavastatin ameliorates diabetic nephropathy in db/db mice by minimizing oxidative stress by downregulating NOX4 expression. These findings may provide insight into the mechanisms of statin therapy in early stages of diabetic nephropathy.

The effect of adrenomedullin on rats exposed to lead

Adrenomedullin (AdM) was originally discovered as a vasorelaxant peptide. The antioxidative properties of AdM have been reported recently. Through its antioxidative effect, adrenomedullin can protect organs from damage induced by stressors. Lead, commonly detected in air, soil, water and food, is a major source of oxidative stress. The effect of AdM in the liver of rats exposed to lead was investigated. Twenty-four female Wistar rats were divided into four groups: a control group (C), adrenomedullin group (AdM), lead (Pb) group and lead + adrenomedullin (Pb + AdM) group. In the Pb-treated groups, the animals were exposed to lead in drinking water containing 250 ppm PbCl2 for 4 weeks. In the AdM-treated group, the animals received an i.p. injection of AdM (3000 ng kg(-1) body weight) in the third week of lead treatment for 1 week. The activities of catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) and the level of malondialdehyde (MDA) were determined in the liver of rats. Histological changes in the liver were examined by light and electron microscopy as well. The MDA levels were increased significantly in the Pb-treated groups, but in the Pb + AdM group the MDA levels were decreased significantly when compared with the Pb group. AdM reduced hepatic damage in the Pb + AdM group, but the difference in the total histopathological scores between the Pb and Pb + AdM groups was not significant. When the results are taken together, it can be concluded that AdM may have protective or compensating effects in lead toxicity.

CD11b+ Cells are the Major Source of Oxidative Stress in UV Radiation-irradiated Skin: Possible Role in Photoaging and Photocarcinogenesis¶

Exposure of skin to solar UV radiation induces oxidative stress and suppression of cell-mediated immune responses. These effects are associated with the greater risk of several skin disorders including photoaging and photocarcinogenesis. We have shown that UV-induced infiltrating leukocytes contribute in developing oxidative stress in UV-irradiated skin. The peak period of UV-induced infiltrating leukocytes lies between 48 and 72 h after UV exposure of the skin. In this study we demonstrated that UV (90 mJ/cm2)-induced infiltrating CD11b+ cells in C3H/HeN mice skin were the major source of oxidative stress. Hydrogen peroxide (H2O2) was determined as a marker of oxidative stress. Flow cytometric analysis of viable cells revealed that the number of CD11b+H2O2+ cells were significantly higher (31.8%, P < 0.001) in UV-irradiated skin in comparison with non–UV-exposed skin (0.4%). Intraperitoneal administration of monoclonal antibodies to CD11b (rat IgG2b) to C3H/HeN mice inhibited UVB-induced infiltration of leukocytes, as evidenced by reduction in myeloperoxidase activity (64–80%, P < 0.0005), concomitant with significant reduction in H2O2 production both in epidermis and dermis (66–83%, P < 0.001–0.0005) when compared with the administration of rat IgG2b isotype of anti-CD11b. Furthermore, CD11b+ and CD11b− cell subsets were separated by immunomagnetic cell isolation technique from total epidermal and dermal single cell suspensions obtained 48 h after UV irradiation of the skin and analyzed for H2O2 production. Analytical data revealed that CD11b+ cell population from UV-irradiated skin resulted in significantly higher production of total H2O2 in both epidermis and dermis (87–89%, P < 0.0001) in comparison with CD11b− cell population (11–13% of total H2O2). These data revealed that infiltrating CD11b+ cells were the major source of oxidative stress in UV-irradiated skin and thus may contribute to photoaging and promotion of skin tumor growth within the UV-irradiated skin. Together, these data suggest that reduction in UV-induced skin infiltration of CD11b+ cells may be an alternative and effective strategy to reduce solar UV light–induced oxidative stress–mediated skin disorders including photoaging and photocarcinogenesis.

Association Between Cigarette Smoking and Oxidized Proteins

P-159 Introduction: Cigarette smoking is a major source of oxidative stress. Protein carbonyls have been used as a biomarker of oxidative stress because of the relative stability of carbonylated proteins and the high protein concentration in blood. Increased levels of carbonyl groups have been found in serum proteins of smokers compared to nonsmokers. However, the dose effect of cigarette smoke on oxidative stress has not been studied. Hence, we used an ELISA (Enzyme-Linked Immunosorbent Assay) to evaluate plasma protein carbonyls as a parameter of oxidative stress in subjects who were enrolled in the EMphysema and Lung Cancer Action Project (EMCAP). Methods: The EMCAP lung cancer screening program enrolled current and former smokers age 60 years and over without a prior cancer diagnosis. A total of 542 participants (282 males and 260 females) completed a baseline questionnaire and provided blood samples for the biomarker study. The protein oxidation was measured by derivatization of the carbonyl groups with 2,4-dinitrophenylhydrazine (DNPH) and ELISA quantitation of the DNPH group. Results: The mean (± SD) protein carbonyl level was 17.9 ± 2.9 nmol carbonyls/ml plasma. Protein carbonyls did not differ significantly by gender. Carbonyl levels were higher among current than former smokers, but these differences did not attain statistical significance, nor did differences by pack-years, pack/day among current smokers, and smoking duration. In a multiple regression analysis, higher protein carbonyl levels were independently associated with increasing age (5.6 nmol/ml increase per 10 years, 95% CI 1.1, 10.1, p = 0.01), African-American vs. white race/ethnicity, (1.2 nmol/ml, 95% CI 0.2, 2.2, p = 0.01), lower educational attainment (0.7 nmol/ml, 95% CI 0.4, 1.3, p = 0.043) and higher body mass index (0.7 nmol/ml, 95% CI 0.01, 1.4, p = 0.04). Conclusions: Although we found no association between cigarette smoking and protein carbonyls in this older group of long term smokers and exsmokers, associations were found for age, ethnicity, educational attainment and obesity. The measurement of plasma carbonyls by this ELISA technique is relatively easy and suitable for studies on the oxidative stress-related disease. Funding: NIH: HL075476 and ES09089.

Redox Regulation of Growth and Death in Cardiac Myocytes

Antioxidants & Redox SignalingVol. 8, No. 9-10 Forum Editorial Cardiac Myocytes Part IRedox Regulation of Growth and Death in Cardiac MyocytesJunichi SadoshimaJunichi SadoshimaSearch for more papers by this authorPublished Online:20 Sep 2006https://doi.org/10.1089/ars.2006.8.1621AboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited byMaresin 1 Attenuates Lipopolysaccharide-Induced Acute Kidney Injury via Inhibiting NOX4/ROS/NF-κB Pathway10 December 2021 | Frontiers in Pharmacology, Vol. 12αB-crystallin response to a pro-oxidant non-cytotoxic environment in murine cardiac cells: An “in vitro” and “in vivo” studyFree Radical Biology and Medicine, Vol. 152Can Hypoxic Conditioning Improve Bone Metabolism? A Systematic Review21 May 2019 | International Journal of Environmental Research and Public Health, Vol. 16, No. 10Understanding Key Mechanisms of Exercise-Induced Cardiac Protection to Mitigate Disease: Current Knowledge and Emerging ConceptsPhysiological Reviews, Vol. 98, No. 1Cardioprotective effects of fucoidan against hypoxia-induced apoptosis in H9c2 cardiomyoblast cells15 April 2015 | Pharmaceutical Biology, Vol. 53, No. 9Humans In Hypoxia: A Conspiracy Of Maladaptation?!Physiology, Vol. 30, No. 4Why Does Exercise "Trigger" Adaptive Protective Responses in the Heart?19 November 2014 | Dose-Response, Vol. 1, No. -1The “Goldilocks Zone†from a redox perspective—Adaptive vs. deleterious responses to oxidative stress in striated muscle18 September 2014 | Frontiers in Physiology, Vol. 5The polymorphic and contradictory aspects of intermittent hypoxiaAmerican Journal of Physiology-Lung Cellular and Molecular Physiology, Vol. 307, No. 2Concentration-dependent wrestling between detrimental and protective effects of H2O2 during myocardial ischemia/reperfusion19 June 2014 | Cell Death & Disease, Vol. 5, No. 6Histone deacetylase signaling in cardioprotection6 December 2013 | Cellular and Molecular Life Sciences, Vol. 71, No. 9The Complex Regulation of Tanshinone IIA in Rats with Hypertension-Induced Left Ventricular Hypertrophy19 March 2014 | PLoS ONE, Vol. 9, No. 3Pharmacological approaches to the treatment of oxidative stress-induced cardiovascular dysfunctionsFuture Medicinal Chemistry, Vol. 5, No. 4Thymosin Beta 4 Prevents Oxidative Stress by Targeting Antioxidant and Anti-Apoptotic Genes in Cardiac Fibroblasts25 October 2011 | PLoS ONE, Vol. 6, No. 10Intermittent hypobaric hypoxia improves postischemic recovery of myocardial contractile function via redox signaling during early reperfusionAmerican Journal of Physiology-Heart and Circulatory Physiology, Vol. 301, No. 4Synergistic genotoxic effect between gene and environmental pollutant: Oxidative DNA damage induced by thioredoxin reductase 1 silencing under nickel treatment5 October 2011 | Molecular & Cellular Toxicology, Vol. 7, No. 3NADPH oxidase 4 (Nox4) is a major source of oxidative stress in the failing heart16 August 2010 | Proceedings of the National Academy of Sciences, Vol. 107, No. 35The role of redox modulation of class II histone deacetylases in mediating pathological cardiac hypertrophy8 May 2009 | Journal of Molecular Medicine, Vol. 87, No. 8Thiol-based mechanisms of the thioredoxin and glutaredoxin systems: implications for diseases in the cardiovascular systemAmerican Journal of Physiology-Heart and Circulatory Physiology, Vol. 292, No. 3 Volume 8Issue 9-10Sep 2006 InformationCopyright 2006, Mary Ann Liebert, Inc.To cite this article:Junichi Sadoshima.Redox Regulation of Growth and Death in Cardiac Myocytes.Antioxidants & Redox Signaling.Sep 2006.1621-1624.http://doi.org/10.1089/ars.2006.8.1621Published in Volume: 8 Issue 9-10: September 20, 2006PDF download

Endothelin-1-induced oxidative stress in DOCA-salt hypertension involves NADPH-oxidase-independent mechanisms

We have demonstrated recently [Callera, Touyz, Teixeira, Muscara, Carvalho, Fortes, Schiffrin and Tostes (2003) Hypertension 42, 811-817] that increased vascular oxidative stress in DOCA (deoxycorticosterone acetate)-salt rats is associated with activation of the ET (endothelin) system via ETA receptors. The exact source of ET-1-mediated oxidative stress remains unclear. The aim of the present study was to investigate whether ET-1 increases generation of ROS (reactive oxygen species) in DOCA-salt hypertension through NADPH-oxidase-dependent mechanisms. Xanthine oxidase, eNOS (endothelial nitric oxide synthase) and COX-2 (cyclo-oxygenase-2) were also examined as potential ET-1 sources of ROS as well as mitochondrial respiration. DOCA-salt and control UniNX (uninephrectomized) rats were treated with the ETA antagonist BMS182874 (40 mg.day(-1).kg(-1) of body weight) or vehicle. Plasma TBARS (thiobarbituric acid-reacting substances) were increased in DOCA-salt compared with UniNX rats. Activity of NADPH and xanthine oxidases in aorta, mesenteric arteries and heart was increased in DOCA-salt rats. BMS182874 decreased plasma TBARS levels without influencing NADPH and xanthine oxidase activities in DOCA-salt rats. Increased p22(phox) protein expression and increased p47(phox) membrane translocation in arteries from DOCA-salt by rats were not affected by BMS182874 treatment. Increased eNOS and COX-2 expression, also observed in aortas from DOCA-salt rats, was unaltered by BMS182874. Increased mitochondrial generation of ROS in DOCA-salt rats was normalized by BMS182874. ETA antagonism also increased the expression of mitochondrial MnSOD (manganese superoxide dismutase) in DOCA-salt rats. In conclusion, activation of NADPH oxidase does not seem to be the major source of oxidative stress induced by ET-1/ETA in DOCA-salt hypertension, which also appears to be independent of increased activation of xanthine oxidase or eNOS/COX-2 overexpression. Mitochondria may play a role in ET-1-driven oxidative stress, as evidenced by increased mitochondrial-derived ROS in this model of hypertension.

Liver Failure and Liver Disease

Liver Failure and Liver Disease

The Nrf2-ARE Signalling Pathway: Promising Drug Target to Combat Oxidative Stress in Neurodegenerative Disorders

A large body of evidence indicates that oxidative stress is a salient pathological feature in many neurodegenerative diseases, including Amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. In addition to signs of systemic oxidative stress, at the biochemical and neuropathological level, neuronal degeneration in these disorders has been shown to coincide with several markers of oxidative damage to lipids, nucleic acids, and proteins in affected brain regions. Neuroinflammatory processes, often associated with the induction of free radical generating enzymes and the accumulation of reactive astrocytes and microglial cells, are considered as a major source of oxidative stress. Given the pathogenic impact of oxidative stress and neuroinflammation, therapeutic strategies aimed to blunt these processes are considered an effective way to confer neuroprotection. Recently, the nuclear transcription factor Nrf2, that binds to the antioxidant response element (ARE) in gene promoters, has been reported to constitute a key regulatory factor in the co-ordinate induction of a battery of endogenous cytoprotective genes, including those encoding for both antioxidant- and anti-inflammatory proteins. In the present review, besides discussing recent evidence underscoring the thesis that the Nrf2-ARE signalling pathway is an attractive therapeutic target for neurodegenerative diseases, we advocate the view that chemopreventive agents might be suitable candidates to serve as lead compounds for the development of a new class of neuroprotective drugs.

Mechanisms for suppressing NADPH oxidase in the vascular wall

Oxidative stress underlies many forms of vascular disease as well as tissue injury following ischemia and reperfusion. The major source of oxidative stress in the artery wall is an NADPH oxidase. This enzyme complex as expressed in vascular cells differs from that in phagocytic leucocytes both in biochemical structure and functions. The crucial flavin-containing catalytic subunits, Nox1 and Nox4, are not found in leucocytes, but are highly expressed in vascular cells and upregulated with vascular remodeling, such as that found in hypertension and atherosclerosis. The difference in catalytic subunits offers the opportunity to develop "vascular specific" NADPH oxidase inhibitors that do not compromise the essential physiological signaling and phagocytic functions carried out by reactive oxygen and nitrogen species. Nitric oxide and targeted inhibitors of NADPH oxidase that block the source of oxidative stress in the vasculature are more likely to prevent the deterioration of vascular function that leads to stroke and heart attack, than are conventional antioxidants. The roles of Nox isoforms in other inflammatory conditions are yet to be explored.

Role of NADPH Oxidase in Hypertension and Diabetic Nephropathy

Oxidative stress plays an important role in the development of renal damage in diabetes and hypertension. The major source of oxidative stress is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived superoxide anion (O2.-) that directly damage cell and also activate signaling of cell proliferation, adhesion molecules, and fibrosis. O2.- also inactivates endothelium derived nitric oxide and cause endothelial nitric oxide synthase uncoupling. In the spontaneously hypertensive rat and Dahl salt-sensitive hypertensive rat with heart failure and in the streptozotocininduced diabetic rats NADPH oxidase is increased via increased renal angiotensin II (AngII), and angiotensin converting enzyme inhibitor (ACEI) or AngII AT1 receptor blocker (ARB) confer renal protection by decrease in NADPH oxidase expression. Hypercholesterolemia additively increases NADPH oxidase in diabetes, as well as increases the adhesion molecule ICAM-1 and glomerular macrophage infiltration. Antioxidant drugs including apocynin, an inhibitor of the translocation of cytosolic components of NADPH oxidase, p38 MAPK inhibitor, or tempol, a superoxide dismutase mimetic, also show renoprotective effect in diabetes or in hypertension. In summary, stimulation of NADPH oxidase by renal AngII has a common pathogenic role in the development of renal damage in hypertension and diabetes and suppression of renal NADPH oxidase is a promising strategy against renal damage.

The osmolyte strategy of normal human keratinocytes in maintaining cell homeostasis.

Compatible organic osmolytes, such as betaine, myoinositol, and taurine, are involved in cell volume homeostasis as well as in cell protection, for example, against oxidative stress. This so-called osmolyte strategy requires the expression of specific osmolyte transporting systems such as the betaine/gamma-amino-n-butyric acid (GABA) transporter, the sodium-dependent myoinositol transporter and the taurine transporter (TAUT). In contrast to liver, kidney, and neural cells, nothing is known about osmolytes in the skin. Here we report that primary normal human keratinocytes (NHK) express mRNA specific for the betaine/GABA transporter, for the sodium-dependent myoinositol transporter and for the TAUT. In comparison to normoosmotic (305 mosmol per L) controls, a 3-5-fold induction of mRNA expression for the betaine/GABA-, the sodium-dependent myoinositol- and the TAUT was observed within 6-24 h after hyperosmotic exposure (405 mosmol per L). Expression of osmolyte transporters was associated with an increased uptake of radiolabeled osmolytes. Conversely, hypoosmotic (205 mosmol per L) stimulation induced significant efflux of these osmolytes. Exposure to ultraviolet B (290-315 nm) or ultraviolet A (340-400 nm) radiation, which are major sources of oxidative stress in skin, significantly stimulated osmolyte uptake. Increased osmolyte uptake was associated with upregulation of mRNA steady-state levels for osmolyte transporters in irradiated cells. These studies demonstrate that NHK possess an osmolyte strategy, which is important for their capacity to maintain cell volume homeostasis and seems to be part of their response to UV radiation.

Applied and ecological aspects of oxidative-stress damage to bacterial spores and to oral microbes.

Bacterial cells have adapted in a variety of ways to resist oxidative stresses and damage in their everyday lives in a predominantly aerobic world. The nearly universal occurrence of resistance mechanisms against oxidative stresses, particularly those due to reactive oxygen species (ROS), suggests that most, if not all, bacteria have to deal with oxidative assaults. A primary source of oxidative stress is aerobic metabolism, which leads to production of ROS such as hydrogen peroxide, superoxide radical, perhydroxyl radical, hydroxyl radical and a variety of other toxic metabolites, including organic peroxides and other organics or inorganics able to transfer electrons to sites of oxidative damage. Anaerobes as well as aerobic and facultative organisms are subject to oxidative stresses, often as a result of their own metabolism of O2 or that of associated facultative organisms. If anaerobes would just ignore oxygen instead of metabolizing it, they would not have to deal with toxic metabolites of their own making. Another major source of oxidative stress comes from the use of oxidative agents in the disinfection-sterilization industry. Notable examples are hypochlorite for water purification and hydrogen peroxide used for industrial sterilization. Antimicrobials such as isoniazide and mitomycin C also act oxidatively to cause damage. In this article, aseptic packaging and processing involving use of hydrogen peroxide for sterilization of packaging materials is reviewed as an example of oxidative stress imposed on bacterial spores and vegetative cells from outside the organisms or the microbial community. The other example considered is related to oral microbiology and infectious disease in which oxidative stress may arise from the metabolism of the oral microbiota or may come from outside through use of oral care products.

Evidence for contribution of vascular NAD(P)H oxidase to increased oxidative stress in animal models of diabetes and obesity

It is well established that oxidative stress is enhanced in diabetes. However, the major in vivo source of oxidative stress is not clear. Here we show that vascular NAD(P)H oxidase may be a major source of oxidative stress in diabetic and obese models. In vivo electron spin resonance (ESR)/spin probe was used to evaluate systemic oxidative stress in vivo. The signal decay rate of the spin probe (spin clearance rate; SpCR) significantly increased in streptozotocin-induced diabetic rats 2 weeks after the onset of diabetes. This increase was completely normalized by treatment with the antioxidants α-tocopherol (40 mg/kg) and superoxide dismutase (5000 units/kg), and was significantly inhibited by treatment with a PKC-specific inhibitor, CGP41251 (50 mg/kg), and a NAD(P)H oxidase inhibitor, apocynin (5 mg/kg). Both obese ob/ob mice (10 weeks old) with mild hyperglycemia and Zucker fatty rats (11 weeks old) with normoglycemia exhibited significantly increased SpCR as compared with controls. Again, this increase was inhibited by treatment with both CGP41251 and apocynin. Oral administration of insulin sensitizer, pioglitazone (10 mg/kg), for 7 days also completely normalized SpCR values. These results suggest that vascular NAD(P)H oxidase may be a major source of increased oxidative stress in diabetes and obesity.