Dexamethasone inhibits the Nox-dependent ROS production via suppression of MKP-1-dependent MAPK pathways in activated microglia

<p>Abstract</p> <p>Background</p> <p>Nox-2 (also known as gp91<it>phox</it>), a subunit component of NADPH oxidases, generates reactive oxygen species (ROS). Nox-dependent ROS generation and nitric oxide (NO) release by microglia have been implicated in a variety of diseases in the central nervous system. Dexamethasone (Dex) has been shown to suppress the ROS production, NO release and inflammatory reaction of activated microglial cells. However, the underlying mechanisms remain unclear.</p> <p>Results</p> <p>The present study showed that the increased ROS production and NO release in activated BV-2 microglial cells by LPS were associated with increased expression of Nox-2 and iNOS. Dex suppressed the upregulation of Nox-2 and iNOS, as well as the subsequent ROS production and NO synthesis in activated BV-2 cells. This inhibition caused by Dex appeared to be mediated by upregulation of MAPK phosphatase-1 (MKP-1), which antagonizes the activity of mitogen-activated protein kinases (MAPKs). Dex induced-suppression of Nox-2 and -upregulation of MKP-1 was also evident in the activated microglia from corpus callosum of postnatal rat brains. The overexpression of MKP-1 or inhibition of MAPKs (by specific inhibitors of JNK and p38 MAPKs), were found to downregulate the expression of Nox-2 and iNOS and thereby inhibit the synthesis of ROS and NO in activated BV-2 cells. Moreover, Dex was unable to suppress the LPS-induced synthesis of ROS and NO in BV-2 cells transfected with MKP-1 siRNA. On the other hand, knockdown of Nox-2 in BV-2 cells suppressed the LPS-induced ROS production and NO release.</p> <p>Conclusion</p> <p>In conclusion, it is suggested that downregulation of Nox-2 and overexpression of MKP-1 that regulate ROS and NO may form the potential therapeutic strategy for the treatment of neuroinflammation in neurodegenerative diseases.</p

Determinación de NOX-2 y NOX-4 en miocardio de ratas, analizando su relación con la cardiopatía diabética

69 p.La diabetes corresponde a una patología altamente prevalente tanto a nivel nacional como internacional. Dentro de sus complicaciones encontramos la cardiopatía diabética, siendo una de las mayores causas de mortalidad de la enfermedad. Esta complicación se relaciona con la mayor producción de especies reactivas del oxígeno (ROS), lo cual se encuentra modulado por el complejo NAPDH oxidasa, por la respiración mitocondrial y por la Angiotensina II. Estos modulares provocan una regulación positiva de las ROS. La familia de las NAPDH oxidasas, ahora denominadas NOXs comprenden variadas isoformas, donde podemos destacar NOX-2 y NOX-4, a nivel cardiaco.En este estudio se llevó a cabo la pesquisa de NOX-2 y NOX-4 determinando su expresión génica a través del ARNm, estudiado en un modelo de diabetes; ratas control (C), ratas diabéticas (inducido por aloxano) sin ejercicio físico (S) y ratas diabéticas (inducido por aloxano) sometidas a ejercicio físico (E). El ARNm fue extraído del tejido cardiaco con el método del TRIZOL. Luego de ello se realizó la transcripción del ARNm a ADNc, para finalmente continuar con la cuantificación del transcrito por medio de la PCR-real time. Finalmente, los resultados obtenidos (CTs) nos permitieron analizar los datos comparando la producción de ARNm entre los distintos grupos estudiados,pudiendo concluirse, que el ejercicio físico no disminuía la producción de ARNm para NOX hallándose aumentada tanto NOX-2 como NOX-4, en comparación a las ratas diabéticas sedentarias y las ratas control. Palabras claves: NOX-2,NOX-4 , NAPDH, PCR-real time, Cardiopatía Diabética, / ABSTRACT: Diabetes corresponds to a highly prevalent pathology both nationally and internationally. Among its complications diabetic cardiomyopathy is one of the main causes of mortality of the disease. This complication is associated with increased production of reactive oxygen species (ROS), which is modulated by the NADPH oxidase complex, mitochondrial respiration and Angiotensin II. These cause upregulation of ROS. The family of NADPH oxidases, now called NOXs, comprises various isoforms, where NOX-2 and NOX-4 are the most important in the heart. In this study we conducted the investigation of NOX-2 and NOX-4 determining gene expression through mRNA, studied in a model of diabetes; control rats (C),diabetic rats (induced by alloxan) without exercise (S) and diabetic rats (induced by alloxan) subjected to physical exercise (E). mRNA was extracted from the cardiac tissue with the Trizol method. After the mRNA isolation, the transcription to cDNA was performed. Finally the amount of NOXs transcript was quantified by real-time PCR.The results obtained (CTs) allowed us to analyze the data comparing mRNA production between the different groups studied. It can be concluded that exercise did not decrease the production of mRNA for NOX. On the contrary, it is associated with an increase in both NOX-2 and NOX-4 mRNA in exercised rats compared to sedentary diabetic rats and control rats. Keywords: NOX-2, NOX-4, NAPDH, PCR-real time, Diabetic cardiopathy, Diabetes

Gas-turbine critical research and advanced technology support project

The technical progress made during the first 15 months of a planned 40-month project to provide a critical-technology data base for utility gas-turbine systems capable of burning coal-derived fuels is summarized. Tasks were included in the following areas: (1) combustion, to study the combustion of coal-derived fuels and conversion of fuel-bound nitrogen to NOx; (2) materials, to understand and prevent hot corrosion; and (3) system studies, to integrate and guide the other technologies. Significant progress was made

Low grade endotoxemia and oxidative stress in offspring of patients with early myocardial infarction

Background and aims: Offspring of patients with early myocardial infarction are at higher cardiovascular risk, but the underlying physio-pathological mechanism is unclear. NADPH oxidase-type 2 (NOX-2) plays a pivotal role as mediator of oxidative stress and could be involved in activating platelets in these patients. Furthermore, altered intestinal permeability and serum lipopolysaccharide (LPS) could be a trigger to promote NOX-2 activation and platelet aggregation. This study aims to evaluate the behavior of low grade endotoxemia, oxidative stress and platelet activation in offspring of patients with early myocardial infarction. Methods: We enrolled, in a cross-sectional study, 46 offspring of patients with early myocardial infarction and 86 healthy subjects (HS). LPS levels and gut permeability (assessed by zonulin), oxidative stress (assessed by serum NOX-2-derived peptide (sNOX2-dp) release, hydrogen peroxide (H2O2) production and isoprostanes), serum nitric oxide (NO) bioavailability and platelet activation (by serum thromboxane B2 (TXB2) and soluble P-Selectin (sP-Selectin)) were analyzed. Results: Compared to HS, offspring of patients with early myocardial infarction had higher values of LPS, zonulin, serum isoprostanes, sNOX2-dp H2O2, TXB2, p-selectin and lower NO bioavailability. Logistic regression analysis showed that the variables associated with offspring of patients with early myocardial infarction were LPS, TXB2 and isoprostanes. The multiple linear regression analysis confirmed that serum NOX-2, isoprostanes, p-selectin and H2O2 levels were significantly associated to LPS. Furthermore, serum LPS, isoprostanes and TXB2 levels were significantly associated with sNOX-2-dp. Conclusions: Offspring of patients with early myocardial infarction have a low grade endotoxemia that could generate oxidative stress and platelet activation increasing their cardiovascular risk. Future studies are needed to understand the role of dysbiosis in this population

Effective algebraic degeneracy

We prove that any nonconstant entire holomorphic curve from the complex line C into a projective algebraic hypersurface X = X^n in P^{n+1}(C) of arbitrary dimension n (at least 2) must be algebraically degenerate provided X is generic if its degree d = deg(X) satisfies the effective lower bound: d larger than or equal to n^{{(n+1)}^{n+5}}

Red wine polyphenols prevent metabolic and cardiovascular alterations associated with obesity in Zucker fatty rats (Fa/Fa)

Peer reviewedPublisher PD

Experimental rat models of chronic allograft nephropathy: a review

Chronic allograft nephropathy (CAN) is the leading cause of late allograft loss after renal transplantation (RT), which continues to remain an unresolved problem. A rat model of CAN was first described in 1969 by White et al. Although the rat model of RT can be technically challenging, it is attractive because the pathogenesis of CAN is similar to that following human RT and the pathological features of CAN develop within months as compared with years in human RT. The rat model of RT is considered as a useful investigational tool in the field of experimental transplantation research. We have reviewed the literature on studies of rat RT reporting the donor and recipient strain combinations that have investigated resultant survival and histological outcomes. Several different combinations of inbred and outbred rat combinations have been reported to investigate the multiple aspects of transplantation, including acute rejection, cellular and humoral rejection mechanisms and their treatments, CAN, and potential targets for its prevention

Short-term e-cigarette vapour exposure causes vascular oxidative stress and dysfunction: evidence for a close connection to brain damage and a key role of the phagocytic NADPH oxidase (NOX-2)

AIMS: Electronic (e)-cigarettes have been marketed as a \u27healthy\u27 alternative to traditional combustible cigarettes and as an effective method of smoking cessation. There are, however, a paucity of data to support these claims. In fact, e-cigarettes are implicated in endothelial dysfunction and oxidative stress in the vasculature and the lungs. The mechanisms underlying these side effects remain unclear. Here, we investigated the effects of e-cigarette vapour on vascular function in smokers and experimental animals to determine the underlying mechanisms. METHODS AND RESULTS: Acute e-cigarette smoking produced a marked impairment of endothelial function in chronic smokers determined by flow-mediated dilation. In mice, e-cigarette vapour without nicotine had more detrimental effects on endothelial function, markers of oxidative stress, inflammation, and lipid peroxidation than vapour containing nicotine. These effects of e-cigarette vapour were largely absent in mice lacking phagocytic NADPH oxidase (NOX-2) or upon treatment with the endothelin receptor blocker macitentan or the FOXO3 activator bepridil. We also established that the e-cigarette product acrolein, a reactive aldehyde, recapitulated many of the NOX-2-dependent effects of e-cigarette vapour using in vitro blood vessel incubation. CONCLUSIONS: E-cigarette vapour exposure increases vascular, cerebral, and pulmonary oxidative stress via a NOX-2-dependent mechanism. Our study identifies the toxic aldehyde acrolein as a key mediator of the observed adverse vascular consequences. Thus, e-cigarettes have the potential to induce marked adverse cardiovascular, pulmonary, and cerebrovascular consequences. Since e-cigarette use is increasing, particularly amongst youth, our data suggest that aggressive steps are warranted to limit their health risks

Spatial Weighting Matrix Selection in Spatial Lag Econometric Model

This paper investigates the choice of spatial weighting matrix in a spatial lag model framework. In the empirical literature the choice of spatial weighting matrix has been characterized by a great deal of arbitrariness. The number of possible spatial weighting matrices is large, which until recently was considered to prevent investigation into the appropriateness of the empirical choices. Recently Kostov (2010) proposed a new approach that transforms the problem into an equivalent variable selection problem. This article expands the latter transformation approach into a two-step selection procedure. The proposed approach aims at reducing the arbitrariness in the selection of spatial weighting matrix in spatial econometrics. This allows for a wide range of variable selection methods to be applied to the high dimensional problem of selection of spatial weighting matrix. The suggested approach consists of a screening step that reduces the number of candidate spatial weighting matrices followed by an estimation step selecting the final model. An empirical application of the proposed methodology is presented. In the latter a range of different combinations of screening and estimation methods are employed and found to produce similar results. The proposed methodology is shown to be able to approximate and provide indications to what the ‘true’ spatial weighting matrix could be even when it is not amongst the considered alternatives. The similarity in results obtained using different methods suggests that their relative computational costs could be primary reasons for their choice. Some further extensions and applications are also discussed

New potential biomarkers for early chronic kidney disease diagnosis in patients with different glucose tolerance status

Background: The purpose of the present study was to investigate the role of oxidative stress, platelet activation, and endocan levels in renal dysfunction in normal glucose tolerance (NGT) patients with 1-h plasma glucose values ≥155 mg/dl (NGT ≥ 155), compared to NGT &lt; 155, impaired glucose tolerance (IGT), and type 2 diabetes mellitus (T2DM) newly diagnosed subjects. We enlisted 233 patients subjected to an oral glucose tolerance test (OGTT). Materials and methods: The serum levels of platelet activation (glycoprotein VI and sP-selectin), oxidative stress biomarkers (8-isoprostane and Nox-2), and endocan were evaluated using an ELISA test. Results: Among NGT &lt; 155 patients and the T2DM group, there was a statistically significant increase in 8-isoprostane (p &lt; 0.0001), Nox-2 (p &lt; 0.0001), glycoprotein VI (p &lt; 0.0001), and sP-selectin (p &lt; 0.0001) serum levels. Higher serum endocan levels were found with the worsening of metabolic profile (p &lt; 0.0001); specifically, NGT ≥ 155 patients presented higher serum endocan values when compared to NGT &lt; 155 patients (p &lt; 0.0001). From the multivariate linear regression analysis, 1-h glucose resulted in the major predictor of estimated glomerular filtration rate (e-GFR) justifying 23.6% of its variation (p &lt; 0.0001); 8-isoprostane and Nox-2 added respectively another 6.0% (p &lt; 0.0001) and 3.2% (p = 0.001). Conclusion: Our study confirmed the link between 1-h post-load glucose ≥155 mg/dl during OGTT and the possible increased risk for chronic kidney disease (CKD) in newly diagnosed patients. The novelty is that we demonstrated a progressive increase in oxidative stress, platelet activation, and serum endocan levels with the worsening of metabolic profile, which becomes evident early during the progression of CKD