NAD(P)H oxidase-derived hydrogen peroxide mediates endothelial nitric oxide production in response to angiotensin II

Recently, it has been shown that the exogenous addition of hydrogen peroxide (H(2)O(2)) increases endothelial nitric oxide (NO(.)) production. The current study is designed to determine whether endogenous levels of H(2)O(2) are ever sufficient to stimulate NO(.) production in intact endothelial cells. NO(.) production was detected by a NO(.)-specific microelectrode or by an electron spin resonance spectroscopy using Fe(2+)-(DETC)(2) as a NO(.)-specific spin trap. The addition of H(2)O(2) to bovine aortic endothelial cells caused a potent and dose-dependent increase in NO(.) release. Incubation with angiotensin II (10(-7) mol) elevated intracellular H(2)O(2) levels, which were attenuated with PEG-catalase. Angiotensin II increased NO(.) production by 2-fold, and this was prevented by Losartan and by PEG-catalase, suggesting a critical role of AT1 receptor and H(2)O(2) in this response(.) In contrast, NO(.) production evoked by either bradykinin or calcium ionophore was unaffected by PEG-catalase. As in bovine aortic endothelial cells, angiotensin II doubled NO(.) production in aortic endothelial cells from C57BL/6 mice but had no effect on NO(.) production in endothelial cells from p47(phox-/-) mice. In contrast, stimulated NO(.) production to a similar extent in endothelial cells from wild-type and p47(phox-/-) mice. In summary, the present study provides direct evidence that endogenous H(2)O(2), derived from the NAD(P)H oxidase, mediates endothelial NO(.) production in response to angiotensin II. Under disease conditions associated with elevated levels of angiotensin II, this response may represent a compensatory mechanism. Because angiotensin II also stimulates O(2)() production from the NAD(P)H oxidase, the H(2)O(2) stimulation of NO(.) may facilitate peroxynitrite formation in response to this octapeptide.     

Abrogation of bleomycin-induced lung fibrosis by nitric oxide synthase inhibitor, aminoguanidine in mice.

The effects of aminoguanidine (AG), a specific inhibitor of inducible nitric oxide synthase, on the bleomycin (BL)-induced lung fibrosis was evaluated in mice. The animals were placed into five groups: saline (SA)-instilled drinking water (SA+H(2)O), saline-instilled drinking water containing 0.5%AG (SA+0.5%AG), BL-instilled drinking water (BL+H(2)O), BL-instilled drinking water containing 0.2%AG (BL+0.2%AG), and BL-instilled drinking water containing 0.5%AG (BL+0.5%AG). The mice had free access to H(2)O or H(2)O containing AG and lab chow ad lib 2 days prior to intratracheal (IT) instillation of BL (0.07U/mouse/100 microL) or an equivalent volume of sterile isotonic saline. The mice in the SA+0.5%AG group consumed the greatest amount of AG without any ill effects than the mice in any other group. There were no differences in any of the measured biochemical determinants between the SA+H(2)O and SA+0.5%AG control groups. The IT instillation of BL in the BL+H(2)O group caused significant increases in the lipid peroxidation, hydroxyproline content, and prolyl hydroxylase activity of lungs and influx of inflammatory cells in the broncheoalveolar lavage fluid (BALF) as compared to both control groups. The intake of aminoguanidine by mice in the BL+0.5%AG group caused significant reductions in the BL-induced increases in all measured biochemical indices of lung fibrosis without any effects on the influx of inflammatory cells in the BALF. In fact, AG in both BL-treated groups additionally increased the total cell counts in the BALF from mice in the BL+0.2%AG and BL+0.5%AG groups as compared to the BL+H(2)O group. Histopathological evaluation of the lungs revealed that the mice in the BL+0.5%AG group had markedly fewer fibrotic lesions than mice in the BL+H(2)O group. These results demonstrate that aminoguanidine minimizes the BL-induced lung fibrosis at both the biochemical and the morphological level and support our earlier hypothesis that the production of nitric oxide plays a significant role in the pathogenesis lung fibrosis caused by BL.     

High frequency of immature dendritic cells and altered in situ production of interleukin-4 and tumor necrosis factor-α in lung cancer

INTRODUCTION: Antigen-presenting cells, like dendritic cells (DCs) and macrophages, play a significant role in the induction of an immune response and an imbalance in the proportion of macrophages, immature and mature DCs within the tumor could affect significantly the immune response to cancer. DCs and macrophages can differentiate from monocytes, depending on the milieu, where cytokines, like interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF) induce DC differentiation and tumor necrosis factor (TNF)-alpha induce DC maturation. Thus, the aim of this work was to analyze by immunohistochemistry the presence of DCs (S100+ or CD1a+), macrophages (CD68+), IL-4 and TNF-alpha within the microenvironment of primary lung carcinomas. RESULTS: Higher frequencies of both immature DCs and macrophages were detected in the tumor-affected lung, when compared to the non-affected lung. Also, TNF-alpha-positive cells were more frequent, while IL-4-positive cells were less frequent in neoplastic tissues. This decreased frequency of mature DCs within the tumor was further confirmed by the lower frequency of CD14-CD80+ cells in cell suspensions obtained from the same lung tissues analyzed by flow cytometry. CONCLUSION: These data are discussed and interpreted as the result of an environment that does not oppose monocyte differentiation into DCs, but that could impair DC maturation, thus affecting the induction of effective immune responses against the tumor.     

Effects of neutrophil elastase inhibitor (ONO-5046) on lung injury after intestinal ischemia-reperfusion.

The underlying mechanisms of lung endothelial injury after intestinal ischemia-reperfusion (I/R) injury are not fully known. Here we investigated the effects of posttreatment with a neutrophil elastase inhibitor (NEI; ONO-5046) on lung injury after intestinal I/R injury in a rat model. Intestinal I/R was produced by 90 min of ischemia followed by either 60 or 240 min of reperfusion. For all experimental groups, the endothelial permeability index increased, neutrophil H(2)O(2) production increased in the pulmonary vasculature blood, neutrophil counts increased in bronchoalveolar lavage fluid (BALF), and the cytokine-induced neutrophil chemoattractant (CINC)-1 and CINC-3 levels were increased in BALF after 240 min (P < 0.01). In rats treated with NEI from 60 min after reperfusion, the lung endothelial permeability index was significantly reduced (P < 0.05), whereas neutrophil H(2)O(2) production in pulmonary vasculature blood and neutrophil count in BALF were significantly suppressed by NEI (P < 0.05 and P < 0.01, respectively). In addition, NEI significantly suppressed the increase of CINC-1 and CINC-3 levels in BALF (P < 0.05). Our study clearly indicates that posttreatment with NEI reduces neutrophil activation in the pulmonary vessels and neutrophil accumulation in the lungs and suggests that ONO-5046, even when administered after the primary intestinal insult, can prevent the progression of lung injury associated with intestinal I/R.     

Suppression of bleomycin-induced nitric oxide production in mice by taurine and niacin.

The effects of taurine (T) and niacin (N) on the influx of inflammatory cells and nitric oxide (NO) levels in bronchoalveolar lavage fluid (BALF) and expression of inducible NO synthase (iNOS) mRNA and iNOS protein in lungs were evaluated in the bleomycin (BL)-mouse model of lung fibrosis. Mice were placed into four groups: saline-instilled (SA) with a control diet (CD) (SA + CD); saline-instilled with TN (1% taurine in water + 2.5% (w/w) niacin in diet) (SA + TN); BL-instilled with CD (BL + CD); and BL-instilled with TN treatment (BL + TN). There was no difference in differential cell counts in BALF between the SA + CD and SA + TN control groups. Intratracheal instillation (IT) of BL (0.1 U/mouse) in mice stimulated an early influx of neutrophils followed by an increase in lymphocytes and macrophages in the BL + CD group. Taurine and niacin treatment significantly reduced the numbers of neutrophils, lymphocytes, and macrophages in the BL + TN group and caused significant reductions in BL-induced increases in the lung hydroxyproline content at 14 and 21 days in the BL + TN group. The mice in the SA + CD and SA + TN control groups had low levels of NO in BALF, whereas mice in the BL + CD group as compared to the SA + CD control group had elevated levels of NO from day 3 through day 21. Taurine and niacin treatment caused significant reductions in BL-induced increases in NO levels in BALF from mice in the BL + TN group at 7, 14, and 21 days as compared to the corresponding BL + CD group. The increases in NO levels in BALF from the BL + CD group were associated with elevated levels of iNOS gene expression and protein in the lungs. RT-PCR analysis of total RNA isolated from the lungs indicated that taurine and niacin treatment suppressed the BL-induced increases in iNOS message and iNOS protein. The ability of taurine and niacin to suppress the BL-induced increased production of NO secondary to decreases in iNOS mRNA and protein appears to be one of the mechanisms for their anti-inflammatory and antifibrotic effects.     

Inhibition of Nox2 oxidase activity ameliorates influenza A virus-induced lung inflammation

Influenza A virus pandemics and emerging anti-viral resistance highlight the urgent need for novel generic pharmacological strategies that reduce both viral replication and lung inflammation. We investigated whether the primary enzymatic source of inflammatory cell ROS (reactive oxygen species), Nox2-containing NADPH oxidase, is a novel pharmacological target against the lung inflammation caused by influenza A viruses. Male WT (C57BL/6) and Nox2(-/y) mice were infected intranasally with low pathogenicity (X-31, H3N2) or higher pathogenicity (PR8, H1N1) influenza A virus. Viral titer, airways inflammation, superoxide and peroxynitrite production, lung histopathology, pro-inflammatory (MCP-1) and antiviral (IL-1β) cytokines/chemokines, CD8(+) T cell effector function and alveolar epithelial cell apoptosis were assessed. Infection of Nox2(-/y) mice with X-31 virus resulted in a significant reduction in viral titers, BALF macrophages, peri-bronchial inflammation, BALF inflammatory cell superoxide and lung tissue peroxynitrite production, MCP-1 levels and alveolar epithelial cell apoptosis when compared to WT control mice. Lung levels of IL-1β were ～3-fold higher in Nox2(-/y) mice. The numbers of influenza-specific CD8+D(b)NP(366)+ and D(b)PA(224)+ T cells in the BALF and spleen were comparable in WT and Nox2(-/y) mice. In vivo administration of the Nox2 inhibitor apocynin significantly suppressed viral titer, airways inflammation and inflammatory cell superoxide production following infection with X-31 or PR8. In conclusion, these findings indicate that Nox2 inhibitors have therapeutic potential for control of lung inflammation and damage in an influenza strain-independent manner.     

Hydrogen peroxide induces a rapid production of nitric oxide in mung bean (Phaseolus aureus).

Nitric oxide (NO) has recently been identified as an important signaling molecule in plant immune response. The present study aims to investigate the signaling pathway that leads to NO production. Using the NO specific fluorescent dye DAF-2DA, we observed rapid production of NO in mung bean leaves after the addition of 10 mM hydrogen peroxide (H(2)O(2)). NO was probably produced by a NOS-like enzyme in plants, as the NO production was inhibited by l-NAME, a NOS inhibitor. The NOS-like activity in the total leaf protein preparation of mung bean (Phaseolus aureus) was elevated 8.3-fold after 10 mM H(2)O(2) treatment, as demonstrated using the chemiluminescence NOS assay. The NOS-like activity was BH(4) dependent: omitting BH(4) in the reaction mixture of NOS assay reduced the NOS activity by 76%. We also found that the H(2)O(2) induced NO production was mediated via calcium ion flux, as it was blocked in the presence of a calcium ion channel blocker, verapamil. Results from the present study identified H(2)O(2) as an upstream signal that leads to NO production in plants. H(2)O(2) and NO, besides acting as two independent signaling molecules in plant immune response, may interrelate to form an oxidative cell death (OCD) cycle.     

Signal interaction between nitric oxide and hydrogen peroxide in heat shock-induced hypericin production of Hypericum perforatum suspension cells

Heat shock(HS, 40℃, 10 min) induces hypericin production, nitric oxide(NO) generation, and hydrogen peroxide(H2O2) accumulation of Hypericum perforatum suspension cells.Catalase(CAT) and NO spe-cific scavenger 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide(cPTIO) suppress not only the HS-induced H2O2 generation and NO burst, but also the HS-triggered hypericin produc-tion.Hypericin contents of the cells treated with both NO and H2O2 are significantly higher than those of the cells treated with NO alone, although H2O2 per se has no effects on hypericin production of the cells, which suggests the synergistic action between H2O2 and NO on hypericin production.NO treatment enhances H2O2 levels of H.perforatum cells, while external application of H2O2 induces NO generation of cells.Thus, the results reveal a mutually amplifying action between H2O2 and NO in H.perforatum cells.CAT treatment inhibits both HS-induced H2O2 accumulation and NO generation, while cPTIO can also suppress H2O2 levels of the heat shocked cells.The results imply that H2O2 and NO may enhance each other's levels by their mutually amplifying action in the heat shocked cells.Membrane NAD(P)H oxidase inhibitor diphenylene iodonium(DPI) and nitric oxide synthase(NOS) inhibitor S,S′-1,3-phenylene-bis(1,2-ethanediyl)-bis-isothiourea(PBITU) not only inhibit the mutually amplifying action between H2O2 and NO but also abolish the synergistic effects of H2O2 and NO on hypericin production, showing that the synergism of H2O2 and NO on secondary metabolite biosynthesis might be dependent on their mutual amplification.Taken together, data of the present work demonstrate that both H2O2 and NO are essential for HS-induced hypericin production of H.perforatum suspension cells.Furthermore, the results reveal a special interaction between the two signal molecules in mediating HS-triggered secondary metabolite biosynthesis of the cells.     

Absence of host tumor necrosis factor receptor 1 attenuates manifestations of idiopathic pneumonia syndrome

The interaction of TNF-alpha with TNF receptor 1 (TNFR1) activates several signal transduction pathways that lead to apoptosis or NF-kappa B-dependent inflammation and immunity. We hypothesized that host TNFR1 expression contributes to noninfectious lung injury and inflammation commonly observed after bone marrow transplantation (BMT), termed idiopathic pneumonia syndrome (IPS). C57BL/6 TNFR1-sufficient (TNFR1(+/+)) and -deficient (TNFR1(-/-)) mice were total body irradiated with or without cyclophosphamide conditioning and were given bone marrow plus IPS-inducing donor spleen T cells from B10.BR wild-type mice. TNFR1(-/-) recipient mice exhibited improved early post-BMT survival associated with decreased permeability edema. In addition, the low lung compliance measured in anesthetized, ventilated TNFR1(+/+) mice on day 7 after BMT was restored to baseline during TNFR1 deficiency. Importantly, bronchoalveolar lavage fluid (BALF) inflammatory cells from TNFR1(-/-) vs. TNFR1(+/+) mice generated less nitric oxide (.NO) and nitrating species and exhibited suppressed programmed cell death as assessed using flow cytometry. However, cellular infiltration and levels of proinflammatory cytokines and chemokines were generally higher in BALF collected on day 7 after BMT from TNFR1(-/-) compared with TNFR1(+/+) recipient mice. Our results support a major role of host TNFR1 in regulation of .NO production and lung dysfunction after allogeneic BMT.     

ABA-induced NO generation and stomatal closure in Arabidopsis are dependent on H2O2 synthesis

Nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) are key signalling molecules produced in response to various stimuli and involved in a diverse range of plant signal transduction processes. Nitric oxide and H(2)O(2) have been identified as essential components of the complex signalling network inducing stomatal closure in response to the phytohormone abscisic acid (ABA). A close inter-relationship exists between ABA and the spatial and temporal production and action of both NO and H(2)O(2) in guard cells. This study shows that, in Arabidopsis thaliana guard cells, ABA-mediated NO generation is in fact dependent on ABA-induced H(2)O(2) production. Stomatal closure induced by H(2)O(2) is inhibited by the removal of NO with NO scavenger, and both ABA and H(2)O(2) stimulate guard cell NO synthesis. Conversely, NO-induced stomatal closure does not require H(2)O(2) synthesis nor does NO treatment induce H(2)O(2) production in guard cells. Tungstate inhibition of the NO-generating enzyme nitrate reductase (NR) attenuates NO production in response to nitrite in vitro and in response to H(2)O(2) and ABA in vivo. Genetic data demonstrate that NR is the major source of NO in guard cells in response to ABA-mediated H(2)O(2) synthesis. In the NR double mutant nia1, nia2 both ABA and H(2)O(2) fail to induce NO production or stomatal closure, but in the nitric oxide synthase deficient Atnos1 mutant, responses to H(2)O(2) are not impaired. Importantly, we show that in the NADPH oxidase deficient double mutant atrbohD/F, NO synthesis and stomatal closure to ABA are severely reduced, indicating that endogenous H(2)O(2) production induced by ABA is required for NO synthesis. In summary, our physiological and genetic data demonstrate a strong inter-relationship between ABA, endogenous H(2)O(2) and NO-induced stomatal closure.     

Ionizing radiation potentiates the induction of nitric oxide synthase by interferon-gamma (Ifn-gamma) or Ifn-gamma and lipopolysaccharide in bnl cl.2 murine embryonic liver cells: role of hydrogen peroxide

The effects of ionizing irradiation on the nitric oxide (NO) production in murine embryonic liver cell line, BNL CL.2 cells, were investigated. Various doses (5-40 Gy) of radiation made BNL CL.2 cells responsive to interferon-gamma alone for the production of NO in a dose-dependent manner. Small amounts of lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) synergized with IFN-gamma in the production of NO from irradiated BNL CL.2 cells, even though LPS or TNF-alpha alone did not induce NO production from the same cells. Immunoblots showed parallel induction of inducible nitric oxide synthase (iNOS). NO production in irradiated BNL CL.2 cells by IFN-gamma or IFN-gamma plus LPS was decreased by the addition of catalase, suggesting that H(2)O(2) produced by ionizing irradiation primed the cells to trigger NO production in response to IFN-gamma or IFN-gamma plus LPS. Furthermore, the treatment of nongamma-irradiated BNL CL.2 cells with H(2)O(2) made the cells responsive to IFN-gamma or IFN-gamma plus LPS for the production of NO. This study shows that ionizing irradiation has the ability to induce iNOS gene expression in responsive to IFN-gamma via the formation of H(2)O(2) in BNL CL.2 murine embryonic liver cells.     

Farnesol ameliorates massive inflammation, oxidative stress and lung injury induced by intratracheal instillation of cigarette smoke extract in rats: an initial step in lung chemoprevention

Cigarette smoke toxicants are well known for their debilitating effects on lungs. Cigarette smoke toxicities cause various respiratory disorders including pulmonary emphysema, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis and cancer. Farnesol, an isoprenoid, is known to possess anti-inflammatory and chemopreventive properties. In this study we report the protective efficacy of farnesol against massive lung inflammation, oxidative stress and consequent injuries caused by cigarette smoke toxicants. Farnesol was administered by gavage (50 and 100 mg/kg b.wt. in corn oil) one time daily for 7 days. On day 7 lung injuries were induced by intratracheal instillation of aqueous cigarette smoke extract (CSE). LDH, total cell count, total protein, phospholipid content and MDA formation were measured in bronchoalveolar lavage fluid (BALF). In lung tissue H2O2 content, reduced glutathione (GSH), glutathione reductase (GR), glutathione peroxidase (GPx) and catalase activities were evaluated. Prophylactic treatment with farnesol significantly shows lung protection by lowering the levels of LDH, total cell count, total protein and MDA in BALF. Farnesol maintained the phospholipid content of BALF in a positive manner. In lung tissue it positively modulated the CSE altered activities of GR, GPx and catalase. There was a marked increase in GSH content and decrease in H2O2 content of lung tissue by farnesol administration. Histopathological findings correlate with cellular and biochemical parameters of the lungs and potentiate the protective role of farnesol against CSE induced lung inflammation and injuries. These results suggest a potent role of farnesol in protection of lung against cigarette smoke toxicants induced lung injuries.     

Involvement of nitric oxide synthase in sucrose-enhanced hydrogen peroxide tolerance of Rhodococcus sp. strain APG1, a plant-colonizing bacterium.

Hydrogen peroxide (H2O2) tolerance of Rhodococcus sp. strain APG1, previously isolated from the aquatic fern Azolla pinnata, was examined in relation to nitric oxide (NO) production by cells cultured on a variety of C sources. Cells inoculated onto A. pinnata fronds established a surface-sterilant resistant density of 2-4x10(7) cells g(-1) without causing disease. Compared to cultures containing glucose, fructose, mannitol, or glycerol, those provided only with sucrose displayed, on a per C basis, substantially lower (<10%) growth yields and higher resistance to H2O2. NO, a positive regulator of catalase synthesis in bacteria, was produced in larger amounts in sucrose-grown cells as evidence by eightfold greater per cell accumulations in the medium of nitrite (NO2-), a stable oxidation product of NO. Addition to cells of L-arginine, the substrate for nitric oxide synthase (NOS), stimulated production of NO, detected both by fluorometric reaction with diaminofluorescein-FM diacetate (DAF-FM DA) and by increased levels of NO2- in the culture medium. These results suggest that sucrose may enhance H2O2 tolerance of Rhodococcus APG1 by increasing cellular NO producing capacity. We propose a regulatory role for NOS in promoting tolerance of Rhodococcus APG1 to oxidative stress in the phyllosphere.     

Apical,but not basolateral,endotoxin preincubation protects alveolar epithelial cells against hydrogen peroxide-induced loss of barrier function: the role of nitric oxide synthesis

The influence of LPS preincubation on hydrogen peroxide (H(2)O(2))-induced loss of epithelial barrier function was investigated in rat alveolar epithelial type II cells (ATII). Both apical and basolateral H(2)O(2) administration caused a manyfold increase in transepithelial [(3)H]mannitol passage. Apical but not basolateral preincubation of ATII with LPS did not influence control barrier properties but fully abrogated the H(2)O(2)-induced leakage response. The effect of apical LPS was CD14 dependent and was accompanied by a strong up-regulation of NO synthase II mRNA and protein and NO release. Inhibition of NO by N(G)-monomethyl-L-arginine suppressed the LPS effect, whereas it was reproduced by exogenous application of gaseous NO or NO donor agents. Manipulation of the glutathione homeostasis (buthionine-(S,R)-sulfoximine) and the cGMP pathway (1H-(1,2,4)oxadiazolo[4,3-alpha]quinoxaline-1-one; zaprinast) did not interfere with the protective effect of LPS. Superoxide (O*(-)(2)) generation by ATII cells was reduced by exogenous NO and LPS preincubation. O*(-)(2) scavenging with exogenous superoxide dismutase, the intracellular superoxide dismutase analog Mn(III)tetrakis(4-benzoic acid) porphyrin, and the superoxide scavenger nitroblue tetrazolium and, in particular, hydroxyl radical scavenging with hydroxyl radical scavenger 1,3-dimethyl-thiourea inhibited the H(2)O(2)-induced epithelial leakage response. In conclusion, apical but not basolateral LPS preincubation of ATII cells provides strong protection against H(2)O(2)-induced transepithelial leakage, attributable to an up-regulation of epithelial NO synthesis. It is suggested that the LPS-induced NO formation is effective via interaction with reactive oxygen species, including superoxide and hydroxyl radicals. The polarized epithelial response to LPS may be part of the lung innate immune system, activated by inhaled endotoxin or under conditions of pneumonia.     

NO可能作为H2O2的下游信号介导ABA诱导的蚕豆气孔关闭

ABA、H2O2和硝普钠(SNP)均能诱导蚕豆气孔关闭.NO的清除剂c-PTIO可以减轻由ABA或H2O2所诱导的蚕豆气孔关闭的程度,而过氧化氢酶(CAT)则不能减轻NO诱导的气孔关闭程度.激光共聚焦显微检测结果显示,10μmo1/L的ABA处理后,胞内H2O2的产生速率明显高于NO的产生速率;CAT几乎可完全抑制ABA所诱导的DAF的荧光增加;外源H2O2能显著诱导胞内DAF的荧光增加;c-PTIO对ABA诱导的DCF荧光略有促进作用,但外源SNP不能诱导胞内DCF荧光增加.这些结果表明,在ABA诱导气孔关闭过程中,H2O2可能在NO的上游起作用并受NO的负反馈调节.     

Experimental Chemotherapy in Paracoccidioidomycosis Using Ruthenium NO Donor

Paracoccidioidomycosis (PCM) is a granulomatous disease caused by a dimorphic fungus, Paracoccidioides brasiliensis (Pb). To determine the influence of nitric oxide (NO) on this disease, we tested cis-[Ru(bpy)2(NO)SO3](PF6), ruthenium nitrosyl, which releases NO when activated by biological reducing agents, in BALB/c mice infected intravenously with Pb 18 isolate. In a previous study by our group, the fungicidal activity of ruthenium nitrosyl was evaluated in a mouse model of acute PCM, by measuring the immune cellular response (DTH), histopathological characteristics of the granulomatous lesions (and numbers), cytokines, and NO production. We found that cis-[Ru(bpy)2(NO)SO3](PF6)-treated mice were more resistant to infection, since they exhibited higher survival when compared with the control group. Furthermore, we observed a decreased influx of inflammatory cells in the lung and liver tissue of treated mice, possibly because of a minor reduction in fungal cell numbers. Moreover, an increased production of IL-10 and a decrease in TNF-α levels were detected in lung tissues of infected mice treated with cis-[Ru(bpy)2(NO)SO3](PF6). Immunohistochemistry showed that there was no difference in the number of VEGF- expressing cells. The animals treated with cis-[Ru(bpy)2(NO)SO3](PF6) showed high NO levels at 40 days after infection. These results show that NO is effectively involved in the mechanism that regulates the immune response in lung of Pb-infected mice. These data suggest that NO is a resistance factor during paracoccidioidomycosis by controlling fungal proliferation, influencing cytokine production, and consequently moderating the development of a strong inflammatory response.     

Ventilator-induced lung injury is reduced in transgenic mice that overexpress endothelial nitric oxide synthase

Although mechanical ventilation (MV) is an important supportive strategy for patients with acute respiratory distress syndrome, MV itself can cause a type of acute lung damage termed ventilator-induced lung injury (VILI). Because nitric oxide (NO) has been reported to play roles in the pathogenesis of acute lung injury, the present study explores the effects on VILI of NO derived from chronically overexpressed endothelial nitric oxide synthase (eNOS). Anesthetized eNOS-transgenic (Tg) and wild-type (WT) C57BL/6 mice were ventilated at high or low tidal volume (Vt; 20 or 7 ml/kg, respectively) for 4 h. After MV, lung damage, including neutrophil infiltration, water leakage, and cytokine concentration in bronchoalveolar lavage fluid (BALF) and plasma, was evaluated. Some mice were given N(omega)-nitro-L-arginine methyl ester (L-NAME), a potent NOS inhibitor, via drinking water (1 mg/ml) for 1 wk before MV. Histological analysis revealed that high Vt ventilation caused severe VILI, whereas low Vt ventilation caused minimal VILI. Under high Vt conditions, neutrophil infiltration and lung water content were significantly attenuated in eNOS-Tg mice compared with WT animals. The concentrations of macrophage inflammatory protein-2 in BALF and plasma, as well as plasma tumor necrosis factor-alpha and monocyte chemoattractant protein-1, also were decreased in eNOS-Tg mice. L-NAME abrogated the beneficial effect of eNOS overexpression. In conclusion, chronic eNOS overexpression may protect the lung from VILI by inhibiting the production of inflammatory chemokines and cytokines that are associated with neutrophil infiltration into the air space.     

Involvement of nitric oxide in oxidative burst, phenylalanine ammonia-lyase activation and Taxol production induced by low-energy ultrasound in Taxus yunnanensis cell suspension cultures

This work was to characterize the generation of nitric oxide (NO) in Taxus yunnanensis cells exposed to low-energy ultrasound (US) and the signal role of NO in elicitation of plant defense responses and secondary metabolite accumulation. The US sonication (3.5-55.6 mW/cm(3) at 40 kHz fixed frequency) for 2 min induced a rapid and dose-dependent NO production in the Taxus cell culture, which exhibited a biphasic time course, reaching the first plateau within 1.5 h and the second within 7 h after US sonication. The NO donor sodium nitroprusside (SNP) potentiated US-induced H(2)O(2) production and cell death. Inhibition of nitric oxide synthase (NOS) activity by N(omega)-nitro-L-arginine (L-NNA) or scavenging NO by 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxyde (PTIO) partially blocked the US-induced H(2)O(2) production and cell death. Moreover, the NO inhibitors suppressed US-induced activation of phenylalanine ammonium-lyase (PAL) and accumulation of diterpenoid taxanes (Taxol and baccatin III). These results suggest that NO plays a signal role in the US-induced responses and secondary metabolism activities in the Taxus cells.     

Natural killer cells are involved in acute lung immune injury caused by respiratory syncytial virus infection

It is known that respiratory syncytial virus (RSV) is the main cause of bronchiolitis and pneumonia in young children. RSV infection often leads to severe acute lung immunopathology, but the underlying immune mechanisms are not yet fully elucidated. Here, we found that RSV infection induced severe acute lung immune injury and promoted the accumulation and activation of lung natural killer (NK) cells at the early stage of infection in BALB/c mice. Activated lung NK cells highly expressed activating receptors NKG2D and CD27 and became functional NK cells by producing a large amount of gamma interferon (IFN-γ), which was responsible for acute lung immune injury. NK cell depletion significantly attenuated lung immune injury and reduced infiltration of total inflammatory cells and production of IFN-γ in bronchoalveolar lavage fluid (BALF). These data show that NK cells are involved in exacerbating the lung immune injury at the early stage of RSV infection via IFN-γ secretion.     

Regulation of hepatocyte growth factor secretion by fibroblasts in patients with acute lung injury

The mechanisms of pulmonary repair in acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are poorly known. Hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF) are key factors involved in alveolar epithelial repair, present in the bronchoalveolar lavage fluid (BALF) from patients with ALI/ARDS. The role of BALF mediators in their production remains to be determined. We evaluated the overall effect of BALF from 52 patients (27 ventilated patients with ALI/ARDS, 10 ventilated patients without ALI, and 15 nonventilated control patients) on HGF and KGF synthesis by lung fibroblasts. Fibroblasts were cultured in the presence of BALF. HGF and KGF protein secretion was measured using ELISA, and mRNA expression was evaluated using quantitative real-time RT-PCR. Only BALF from ALI/ARDS patients upregulated both HGF and KGF mRNA expression and protein synthesis (+271 and +146% for HGF and KGF, respectively). BALF-induced HGF synthesis from ALI/ARDS patients was higher than that from ventilated patients without ALI (P < 0.05). HGF secretion was correlated with BALF IL-1beta levels (rho = 0.62, P < 0.001) and BALF IL-1beta/IL-1 receptor antagonist ratio (rho = 0.54, P < 0.007) in the ALI/ARDS group. An anti-IL-1beta antibody partially (>50%) inhibited the BALF-induced HGF and PGE(2) secretion, whereas NS-398, a specific cyclooxygenase-2 (COX-2) inhibitor, completely inhibited it. Anti-IL-1beta antibodies as well as NS-398 reversed the COX-2 upregulation induced by BALF. Therefore, IL-1beta is a main BALF mediator involved in HGF secretion, which is mediated through a PGE(2)/COX-2-dependent mechanism. BALF mediators may participate in vivo in the production of HGF and KGF by lung fibroblasts during ALI/ARDS.