The respiratory burst oxidase

Raman Spectroscopy and Imaging Studies of Human Digestive Tract Cells and Tissues-Impact of Vitamin C and E Supplementation

Cancers of digestive tract such as colorectal cancer (CRC) and gastric cancer (GC) are the most commonly detected types of cancer worldwide and their origin can be associated with oxidative stress conditions. Commonly known and followed antioxidants, such as vitamin C and E, are widely considered as potential anti-cancer agents. Raman spectra have great potential in the biochemical characterization of matter based on the fact that each molecule has its own unique vibrational properties. Raman spectroscopy allows to precisely characterize components (proteins, lipids, nucleic acids). The paper presents the application of the Raman spectroscopy technique for the analysis of tissue samples and cells of the human colon and stomach. The main goal of this study is to show the differences between healthy and cancerous tissues from the human digestive tract and human normal and cancer colon and gastric cell lines. The paper presents the spectroscopic characterization of normal colon cells, CCD-18 Co, in physiological and oxidative conditions and effect of oxidative injury of normal colon cells upon supplementation with vitamin C at various concentrations based on Raman spectra. The obtained results were related to the Raman spectra recorded for human colon cancer cells-CaCo-2. In addition, the effect of the antioxidant in the form of vitamin E on gastric cancer cells, HTB-135, is presented and compared with normal gastric cells-CRL-7869. All measured gastric samples were biochemically and structurally characterized by means of Raman spectroscopy and imaging. Statistically assisted analysis has shown that normal, ROS injured and cancerous human gastrointestinal cells can be distinguished based on their unique vibrational properties. ANOVA tests, PCA (Principal Component Analysis) and PLSDA (Partial Least Squares Discriminant Analysis) have confirmed the main role of nucleic acids, proteins and lipids in differentiation of human colon and stomach normal and cancer tissues and cells. The conducted research based on Raman spectra proved that antioxidants in the form of vitamin C and E exhibit anti-cancer properties. In consequence, conducted studies proved that label-free Raman spectroscopy may play an important role in clinical diagnostic differentiation of human normal and cancerous gastrointestinal tissues and may be a source of intraoperative information supporting histopathological analysis.

Neurospora crassa NADPH Oxidase NOX-1 Is Localized in the Vacuolar System and the Plasma Membrane

The NADPH oxidases (NOX) catalyze the production of superoxide by transferring electrons from NADPH to O₂, in a regulated manner. In Neurospora crassa NOX-1 is required for normal growth of hyphae, development of aerial mycelium and asexual spores, and it is essential for sexual differentiation and cell-cell fusion. Determining the subcellular localization of NOX-1 is a critical step in understanding the mechanisms by which this enzyme can regulate all these different processes. Using fully functional versions of NOX-1 tagged with mCherry, we show that in growing hyphae NOX-1 shows only a minor association with the endoplasmic reticulum (ER) markers Ca²⁺-ATPase NCA-1 and an ER lumen-targeted GFP. Likewise, NOX-1 shows minor co-localization with early endosomes labeled with YPT-52, a GTPase of the Rab5 family. In contrast, NOX-1 shows extensive co-localization with two independent markers of the entire vacuolar system; the vacuolar ATPase subunit VMA-1 and the fluorescent molecule carboxy-DFFDA. In addition, part of NOX-1 was detected at the plasma membrane. The NOX-1 regulatory subunit NOR-1 displays a very different pattern of localization, showing a fine granular distribution along the entire hypha and some accumulation at the hyphal tip. In older hyphal regions, germinating conidia, and conidiophores it forms larger and discrete puncta some of which appear localized at the plasma membrane and septa. Notably, co-localization of NOX-1 and NOR-1 was mainly observed under conidial cell-cell fusion conditions in discrete vesicular structures. NOX functions in fungi have been evaluated mainly in mutants that completely lacked this protein, also eliminating interactions between hyphal growth regulatory proteins NOR-1, the GTPase RAC-1 and the scaffold protein BEM-1. To dissect NOX-1 roles as scaffold and as ROS-producing enzyme, we analyzed the function of NOX-1::mCherry proteins carrying proline 382 by histidine (P382H) or cysteine 524 by arginine (C524R) substitutions, predicted to only affect NADPH-binding. Without notably affecting NOX-1 localization or protein levels, each of these substitutions resulted in lack of function phenotypes, indicating that NOX-1 multiple functions are all dependent on its oxidase activity. Our results open new interpretations to possible NOX functions, as components of the fungal vacuolar system and the plasma membrane, as well as to new vacuolar functions.

Analysis of protein chlorination by mass spectrometry

Chlorination of tyrosine is a commonly known effect/consequence of myeloperoxidase activity at sites of inflammation, and detection of 3-chlorotyrosine has been used as biomarker for inflammatory diseases. However, few studies have addressed site specific chlorination in proteins, and no methods for large scale chloroproteomics studies have yet been published.

In this study, we present an optimized mass spectrometry based protocol to identify and quantify chlorinated peptides from single proteins modified by HOCl (100 and 500 μM, within estimated pathophysiological levels), at a high level of sensitivity and accuracy. Particular emphasis was placed on 1) sensitive and precise detection of modification sites, 2) the avoidance of loss or artefactual creation of modifications, 3) accurate quantification of peptide abundance and reduction of missing values problem, 4) monitoring the dynamics of modification in samples exposed to different oxidant concentrations and 5) development of guidelines for verification of chlorination sites assignment.

A combination of an optimised sample preparation protocol, and improved data analysis approaches have allowed identification of 33 and 15 chlorination sites in laminin and fibronectin, respectively, reported in previous manuscripts [1,2]. The method was subsequently tested on murine basement membrane extract, which contains high levels of laminin in a complex mixture. Here, 10 of the major chlorination sites in laminin were recapitulated, highlighting the utility of the method in detecting damage in complex samples.

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An optimized mass spectrometry method is presented to detect protein chlorination.

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Reduction and alkylation leads to loss of chlorinated residues.

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Identification of modification sites in fibronectin and laminin induced by HOCl.

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Quantification of relative site occupancy (RSO) of chlorinated residues.

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Largest chloroproteomics dataset to date.

STIM-Orai Channels and Reactive Oxygen Species in the Tumor Microenvironment

The tumor microenvironment (TME) is shaped by cancer and noncancerous cells, the extracellular matrix, soluble factors, and blood vessels. Interactions between the cells, matrix, soluble factors, and blood vessels generate this complex heterogeneous microenvironment. The TME may be metabolically beneficial or unbeneficial for tumor growth, it may favor or not favor a productive immune response against tumor cells, or it may even favor conditions suited to hijacking the immune system for benefitting tumor growth. Soluble factors relevant for TME include oxygen, reactive oxygen species (ROS), ATP, Ca2+, H⁺, growth factors, or cytokines. Ca2+ plays a prominent role in the TME because its concentration is directly linked to cancer cell proliferation, apoptosis, or migration but also to immune cell function. Stromal-interaction molecules (STIM)-activated Orai channels are major Ca2+ entry channels in cancer cells and immune cells, they are upregulated in many tumors, and they are strongly regulated by ROS. Thus, STIM and Orai are interesting candidates to regulate cancer cell fate in the TME. In this review, we summarize the current knowledge about the function of ROS and STIM/Orai in cancer cells; discuss their interdependencies; and propose new hypotheses how TME, ROS, and Orai channels influence each other.

A Vacuolar Membrane Ferric-Chelate Reductase, OsFRO1, Alleviates Fe Toxicity in Rice (Oryza sativa L.)

Ferric reductase oxidase (FRO), the enzyme that reduced ferric iron [Fe (III)] into ferrous iron [Fe (II)], is known to play important roles in Fe absorption and homeostasis in plants that utilize a strategy I mechanism to obtain iron. Rice can use both strategies I and II for Fe uptake depending on the growth conditions. FRO is encoded by two genes in rice genome. Amino acid sequence alignment shows that OsFRO1 contains all necessary predicted motifs for a functional FRO enzyme, whereas OsFRO2 lacks a complete transmembrane domain at the N-terminal. Transient expression of OsFRO1: GFP protein fusion revealed that OsFRO1 is localized to the vacuolar membrane in rice protoplast. OsFRO1 is primarily expressed in leaves and transcript abundance was decreased under excess Fe conditions. Transgenic plants overexpressing OsFRO1 were more sensitive to Fe toxicity, in contrast RNA interference lines showed more tolerance to Fe excess stress. Furthermore, RNAi lines showed decreased Fe concentrations compared to wild type plants under Fe excess condition. Together these data show that OsFRO1 is involved in reducing ferric Fe into ferrous Fe in the vacuole, and makes the vacuolar stored Fe available to the cytoplasm through Fe (II) or chelated Fe (II) transporters. Under Fe excess condition, the downregulation of OsFRO1 in the RNAi plants reduced the amount of Fe (II) available for cytoplasm, to alleviate Fe excess toxicity. This indicates that OsFRO1 plays an important role to maintain Fe homeostasis between the cytoplasm and vacuole in rice.

Magnetic Fields and Reactive Oxygen Species

Reactive oxygen species (ROS) ubiquitously exist in mammalian cells to participate in various cellular signaling pathways. The intracellular ROS levels are dependent on the dynamic balance between ROS generation and elimination. In this review, we summarize reported studies about the influences of magnetic fields (MFs) on ROS levels. Although in most cases, MFs increased ROS levels in human, mouse, rat cells, and tissues, there are also studies showing that ROS levels were decreased or not affected by MFs. Multiple factors could cause these discrepancies, including but not limited to MF type/intensity/frequency, exposure time and assay time-point, as well as different biological samples examined. It will be necessary to investigate the influences of different MFs on ROS in various biological samples systematically and mechanistically, which will be helpful for people to get a more complete understanding about MF-induced biological effects. In addition, reviewing the roles of MFs in ROS modulation may open up new scenarios of MF application, which could be further and more widely adopted into clinical applications, particularly in diseases that ROS have documented pathophysiological roles.

Molecular mechanisms regulating secretory organelles and endosomes in neutrophils and their implications for inflammation

Neutrophils constitute the first line of cellular defense against invading microorganisms and modulate the subsequent innate and adaptive immune responses. In order to execute a rapid and precise response to infections, neutrophils rely on preformed effector molecules stored in a variety of intracellular granules. Neutrophil granules contain microbicidal factors, the membrane-bound components of the respiratory burst oxidase, membrane-bound adhesion molecules, and receptors that facilitate the execution of all neutrophil functions including adhesion, transmigration, phagocytosis, degranulation, and neutrophil extracellular trap formation. The rapid mobilization of intracellular organelles is regulated by vesicular trafficking mechanisms controlled by effector molecules that include small GTPases and their interacting proteins. In this review, we focus on recent discoveries of mechanistic processes that are at center stage of the regulation of neutrophil function, highlighting the discrete and selective pathways controlled by trafficking modulators. In particular, we describe novel pathways controlled by the Rab27a effectors JFC1 and Munc13-4 in the regulation of degranulation, reactive oxygen species and neutrophil extracellular trap production, and endolysosomal signaling. Finally, we discuss the importance of understanding these molecular mechanisms in order to design novel approaches to modulate neutrophil-mediated inflammatory processes in a targeted fashion.

Protective Effect of N-Acetyl-Cysteine (NAC) in Lipopolysaccharide (LPS)-Associated Inflammatory Response in Rat Neonates

OBJECTIVE

Increased inflammatory response may be associated with adverse clinical outcomes, especially in the neonatal period. The aims of this study were to determine whether N-acetyl-cysteine (NAC), an anti-inflammatory agent, attenuates the inflammatory response in young rats and to determine the most effective route of administration.

METHODS

Four groups of Sprague-Dawley rats (in each group four rats) were studied at 30 days of age. One hour following intraperitoneal (IP) injection of lipopolysaccharide 50 μg/kg, the rats were randomized to subcutaneous (SC), per os (PO), or intraperitoneal (IP) injection of NAC 300 mg/kg, or saline. The control group received saline injection (IP). Three hours following the N-acetyl-cysteine injection the rats were sacrificed, then serum tumor necrosis factor-α (TNF-α) and IL-6 levels were determined by ELISA.

RESULTS

Lipopolysaccharide significantly increased the neonatal serum IL-6 and TNF-α (2051.0±349 and 147.0±25.8 pg/mL, respectively; P<0.01) levels compared to 10 pg/mL in the controls. N-acetyl-cysteine administered one hour following lipopolysaccharide injection significantly attenuated the inflammatory response. Intraperitoneal administration of NAC decreased IL-6 and TNF-α concentration to 294.6 and 17.1 pg/mL, respectively, and was more effective than SC or PO administration.

CONCLUSIONS

N-acetyl-cysteine attenuated the inflammatory response in the neonatal rats, and IP was the most effective administration route.

The Tumorigenic Roles of the Cellular REDOX Regulatory Systems

The cellular REDOX regulatory systems play a central role in maintaining REDOX homeostasis that is crucial for cell integrity, survival, and proliferation. To date, a substantial amount of data has demonstrated that cancer cells typically undergo increasing oxidative stress as the tumor develops, upregulating these important antioxidant systems in order to survive, proliferate, and metastasize under these extreme oxidative stress conditions. Since a large number of chemotherapeutic agents currently used in the clinic rely on the induction of ROS overload or change of ROS quality to kill the tumor, the cancer cell REDOX adaptation represents a significant obstacle to conventional chemotherapy. In this review we will first examine the different factors that contribute to the enhanced oxidative stress generally observed within the tumor microenvironment. We will then make a comprehensive assessment of the current literature regarding the main antioxidant proteins and systems that have been shown to be positively associated with tumor progression and chemoresistance. Finally we will make an analysis of commonly used chemotherapeutic drugs that induce ROS. The current knowledge of cancer cell REDOX adaptation raises the issue of developing novel and more effective therapies for these tumors that are usually resistant to conventional ROS inducing chemotherapy.

The gut microbiota engages different signaling pathways to induce Duox2 expression in the ileum and colon epithelium

The epithelium is a first line of defense against microorganisms in the gut. Reactive oxygen species (ROS) have an important role in controlling the normal gut microbiota and pathogenic bacteria. Dual oxidase 2 (DUOX2) is an important source of hydrogen peroxide in the small and large intestine, and the gut microbiota induces Duox2 expression. Here, we investigated the microbial regulation of Duox2 expression. We found that Duox2 was expressed by intestinal epithelial cells mainly in the tip of the epithelium. Duox2 expression was strongly induced by the presence of a normal microbiota in mice, but not when germ-free mice were colonized with various commensal bacteria. Duox2 expression was more rapidly induced by the gut microbiota in the colon than in the ileum. Furthermore, we showed that regulation of Duox2 expression in the ileum involved TIR-domain-containing adaptor protein including interferon-β (TRIF) and canonical nuclear factor-κB p50/p65 signaling, whereas regulation of Duox2 expression in the colon involved MyD88 and the p38 pathway. Collectively, these data indicate that the gut microbiota uses two distinct signaling pathways to induce Duox2 expression in the ileum and colon epithelium.

Potential role of NADPH oxidase in pathogenesis of pancreatitis

Studies have demonstrated that reactive oxygen species (ROS) are closely related to inflammatory disorders. Nicotinamide adenine dinucleotide phosphate oxidase (NOX), originally found in phagocytes, is the main source of ROS in nonphagocytic cells. Besides directly producing the detrimental highly reactive ROS to act on biomolecules (lipids, proteins, and nucleic acids), NOX can also activate multiple signal transduction pathways, which regulate cell growth, proliferation, differentiation and apoptosis by producing ROS. Recently, research on pancreatic NOX is no longer limited to inflammatory cells, but extends to the aspect of pancreatic acinar cells and pancreatic stellate cells, which are considered to be potentially associated with pancreatitis. In this review, we summarize the literature on NOX protein structure, activation, function and its role in the pathogenesis of pancreatitis.

The role of Rab27a in the regulation of neutrophil function

Neutrophils are central regulators of the innate immune response and help shape the adaptive immune response. Malfunction and unregulated neutrophil activation leads to disease and inflammation. During the host response to infection, neutrophils display several mechanisms of defense mediated by their arsenal of granular proteins. Regulation of granular trafficking, docking and fusion is at the core of the neutrophil defense response to pathogens. The small GTPase Rab27a has emerged as a central regulator of the neutrophil response through its tight control of vesicular trafficking and degranulation. This review focuses on the latest research that has led to the characterization of Rab27a as an essential regulator of neutrophil function.

Peroxynitrite, a potent macrophage-derived oxidizing cytotoxin to combat invading pathogens

Macrophages are among the first cellular actors facing the invasion of microorganisms. These cells are able to internalize pathogens and destroy them by means of toxic mediators, many of which are produced enzymatically and have strong oxidizing capacity. Indeed, macrophages count on the NADPH oxidase complex activity, which is triggered during pathogen invasion and leads to the production of superoxide radical inside the phagosome. At the same time, the induction of nitric oxide synthase results in the production of nitric oxide in the cytosol which is able to readily diffuse to the phagocytic vacuole. Superoxide radical and nitric oxide react at diffusion controlled rates with each other inside the phagosome to yield peroxynitrite, a powerful oxidant capable to kill micro-organisms. Peroxynitrite toxicity resides on oxidations and nitrations of biomolecules in the target cell. The central role of peroxynitrite as a key effector molecule in the control of infections has been proven in a wide number of models. However, some microorganisms and virulent strains adapt to survive inside the potentially hostile oxidizing microenvironment of the phagosome by either impeding peroxynitrite formation or rapidly detoxifying it once formed. In this context, the outcome of the infection process is a result of the interplay between the macrophage-derived oxidizing cytotoxins such as peroxynitrite and the antioxidant defense machinery of the invading pathogens.

Redefining the major contributors to superoxide production in contracting skeletal muscle. The role of NAD(P)H oxidases

The production of reactive oxygen and nitrogen species (RONS) by skeletal muscle is important as it (i) underlies oxidative damage in many degenerative muscle pathologies and (ii) plays multiple regulatory roles by fulfilling important cellular functions. Superoxide and nitric oxide (NO) are the primary radical species produced by skeletal muscle and studies in the early 1980s demonstrated that their generation is augmented during contractile activity. Over the past 30 years considerable research has been undertaken to identify the major sites that contribute to the increased rate of RONS generation in response to contractions. It is widely accepted that NO is regulated by the nitric oxide synthases, however the sites that modulate changes in superoxide during exercise remain unclear. Despite the initial indications that the mitochondrial electron transport chain was the predominant source of superoxide during activity, with the development of analytical methods a number of alternative potential sites have been identified including the NAD(P)H oxidases, xanthine oxidase, cyclooxygenases, and lipoxygenases linked to the activity of the phospholipase A2 enzymes. In the present review we outline the subcellular sites that modulate intracellular changes in superoxide in skeletal muscle and based on the available experimental evidence in the literature we conclude that the NAD(P)H oxidases are likely to be the major superoxide generating sources in contracting skeletal muscle.

Nox enzymes and new thinking on reactive oxygen: a double-edged sword revisited

Reactive oxygen species (ROS) are a chemical class of molecules that have generally been conceptualized as deleterious entities, albeit ones whose destructive properties could be harnessed as antimicrobial effector functions to benefit the whole organism. This appealingly simplistic notion has been turned on its head in recent years with the discovery of the NADPH oxidases, or Noxes, a family of enzymes dedicated to the production of ROS in a variety of cells and tissues. The Nox-dependent, physiological generation of ROS is highly conserved across virtually all multicellular life, often as a generalized response to microbes and/or other exogenous stressors. This review discusses the current knowledge of the role of physiologically generated ROS and the enzymes that form them in both normal biology and disease.

Basic principles and emerging concepts in the redox control of transcription factors

Convincing concepts of redox control of gene transcription have been worked out for prokaryotes and lower eukaryotes, whereas the knowledge on complex mammalian systems still resembles a patchwork of poorly connected findings. The article, therefore, reviews principles of redox regulation with special emphasis on chemical feasibility, kinetic requirements, specificity, and physiological context, taking well investigated mammalian transcription factor systems, nuclear transcription factor of bone marrow-derived lymphocytes (NF-κB), and kelch-like ECH-associated protein-1 (Keap1)/Nrf2, as paradigms. Major conclusions are that (i) direct signaling by free radicals is restricted to O(2)•- and •NO and can be excluded for fast reacting radicals such as •OH, •OR, or Cl•; (ii) oxidant signals are H(2)O(2), enzymatically generated lipid hydroperoxides, and peroxynitrite; (iii) free radical damage is sensed via generation of Michael acceptors; (iv) protein thiol oxidation/alkylation is the prominent mechanism to modulate function; (v) redox sensors must be thiol peroxidases by themselves or proteins with similarly reactive cysteine or selenocysteine (Sec) residues to kinetically compete with glutathione peroxidase (GPx)- and peroxiredoxin (Prx)-type peroxidases or glutathione-S-transferases, respectively, a postulate that still has to be verified for putative mammalian sensors. S-transferases and Prxs are considered for system complementation. The impact of NF-κB and Nrf2 on hormesis, management of inflammatory diseases, and cancer prevention is critically discussed.

Hydrogen peroxide: a Jekyll and Hyde signalling molecule

Reactive oxygen species (ROS) are a group of molecules produced in the cell through metabolism of oxygen. Endogenous ROS such as hydrogen peroxide (H₂O₂) have long been recognised as destructive molecules. The well-established roles they have in the phagosome and genomic instability has led to the characterisation of these molecules as non-specific agents of destruction. Interestingly, there is a growing body of literature suggesting a less sinister role for this Jekyll and Hyde molecule. It is now evident that at lower physiological levels, H₂O₂ can act as a classical intracellular signalling molecule regulating kinase-driven pathways. The newly discovered biological functions attributed to ROS include proliferation, migration, anoikis, survival and autophagy. Furthermore, recent advances in detection and quantification of ROS-family members have revealed that the diverse functions of ROS can be determined by the subcellular source, location and duration of these molecules within the cell. In light of this confounding paradox, we will examine the factors and circumstances that determine whether H₂O₂ acts in a pro-survival or deleterious manner.

Microarray expression profiling of Spodoptera litura in response to oxidative stress

To examine the expression profile of oxidative stress responsive genes in Spodoptera litura, we constructed a cDNA library from S. litura injected with hydrogen peroxide (H(2)O(2)). Using a microarray chip composed of 2,964 cDNAs, we screened gene expression at 1, 3, 5, 7, and 9 h post H(2)O(2) injection. Data were clustered into 15 groups of genes that behave similarly across each time course. Seventy-three genes were identified as being at least twofold up- or downregulated after treatment with H(2)O(2) in S. litura. We constructed expressed sequence tags (ESTs) for genes that changed at least twofold after treatment with H(2)O(2) . The functional classification of these ESTs based on Gene Ontology showed that the ESTs are rich in genes involved in oxidoreductase activity (5.7%), defense (14.3%), cellular process (22.9%), and development (17.1%).

NOX2, p22phox and p47phox are targeted to the nuclear pore complex in ischemic cardiomyocytes colocalizing with local reactive oxygen species

BACKGROUND

NADPH oxidases play an essential role in reactive oxygen species (ROS)-based signaling in the heart. Previously, we have demonstrated that (peri)nuclear expression of the catalytic NADPH oxidase subunit NOX2 in stressed cardiomyocytes, e.g. under ischemia or high concentrations of homocysteine, is an important step in the induction of apoptosis in these cells. Here this ischemia-induced nuclear targeting and activation of NOX2 was specified in cardiomyocytes.

METHODS

The effect of ischemia, mimicked by metabolic inhibition, on nuclear localization of NOX2 and the NADPH oxidase subunits p22(phox) and p47(phox), was analyzed in rat neonatal cardiomyoblasts (H9c2 cells) using Western blot, immuno-electron microscopy and digital-imaging microscopy.

RESULTS

NOX2 expression significantly increased in nuclear fractions of ischemic H9c2 cells. In addition, in these cells NOX2 was found to colocalize in the nuclear envelope with nuclear pore complexes, p22(phox), p47(phox) and nitrotyrosine residues, a marker for the generation of ROS. Inhibition of NADPH oxidase activity, with apocynin and DPI, significantly reduced (peri)nuclear expression of nitrotyrosine.

CONCLUSION

We for the first time show that NOX2, p22(phox) and p47(phox) are targeted to and produce ROS at the nuclear pore complex in ischemic cardiomyocytes.

Effect of NADPH-oxidase inhibitors in the experimental model of zymosan-induced shock in mice

The aim of this study was to investigate the effects of NADPH-oxidase inhibitors, in a mouse model of zymosan. Zymosan-induced shock was induced in mice by administration of zymosan (500 mg/kg, i.p.). The pharmacological treatment was the administration of apocynin (5 mg/kg 10% DMSO i.p.) and diphenylene iodonium chloride (DPI) (1 mg/kg i.v.) 1 h and 6 h after zymosan administration. MOF and systemic inflammation in mice was assessed 18 h after administration of zymosan. NADPH-oxidase inhibitors caused a significant reduction of the (1) peritoneal exudate formation, (2) neutrophil infiltration, (3) multiple organ dysfunction syndrome, (4) nitrotyrosine, (5) poly (ADP-ribose) (PAR), (6) cytokine formation, (7) adhesion molecule expression, (8) nuclear factor (NF-κB) expression and (9) apoptosis induced by zymosan. Moreover, NADPH-oxidase inhibitors treatment significantly reduced the systemic toxicity, the loss in body weight and the mortality caused by zymosan. This study has shown that NADPH-oxidase inhibitors attenuate the degree of zymosan-induced non-septic shock in mice.

Naringenin attenuates mucous hypersecretion by modulating reactive oxygen species production and inhibiting NF-κB activity via EGFR-PI3K-Akt/ERK MAPKinase signaling in human airway epithelial cells

Naringenin (Nar) is a flavonoid derived from plant foods. It has been shown to have anti-inflammatory properties. Many studies have shown that overexpression of reactive oxygen species (ROS) and nuclear factor-κB (NF-κB) leads to increased mucin (MUC) 5AC expression in chronic inflammation of the airway. In addition, some studies have reported that naringenin inhibits NF-κB activity in a murine model of asthma. We speculated that naringenin might be associated with mucous hypersecretion, but the molecular mechanisms remain to be defined. Our study has also investigated whether naringenin could inhibit production of ROS and the activity of NF-κB on the inflammatory pulmonary diseases induced by human neutrophil elastase (HNE) and reduce the mRNA and protein levels of MUC5AC as shown by reverse transcriptase-polymerase chain reaction and real-time PCR (RT-PCR). Serum total MUC5AC protein was detected by enzyme-linked immunosorbent assay (ELISA), the protein morphological changes of MUC5AC were also observed by immunofluorescence and confocal laser technology. Hyperactivation of epidermal growth factor receptor (EGFR) signaling is commonly involved in the mucous hypersecretion process and initiates both the activation of extracellular signal-related kinases 1/2 (ERK1/2) and of phosphatidylinositol 3-kinase (PI3K) and Akt kinase. NF-κB is a key factor downstream of PI3K/Akt signaling, which induces overexpression of the MUC5AC gene. Our data revealed that naringenin inhibited the activation of EGFR resulting in the downregulation of the enzyme activities. Naringenin also reduced the protein expressions of p-EGFR, PI3K, p-Akt, p-ERK1/2, and NF-κB as shown by western blotting. Furthermore, naringenin significantly inhibited PI3K/Akt and ERK MAPKinase signaling with a concurrent reduction in production of ROS and NF-κB activities. These results suggest that naringenin may play a protective role by minimizing mucous production during airway inflammation by down-regulating ROS production and inhibiting the NF-κB activity via EGFR-PI3K-Akt/ERK MAPKinase signaling pathway.

Metal sensing in Salmonella: implications for pathogenesis

Both the essentiality and toxicity of transition metals are exploited as part of mammalian immune defenses against bacterial infection. Salmonella serovars continue to cause serious medical and veterinary problems worldwide and detecting deficiency and excess of different metal ions (such as copper, iron, zinc, manganese, nickel, and cobalt) is fundamental to their virulence. This involves multiple DNA-binding metal-responsive transcription factors that discriminate between elements and trigger expression of genes that mediate appropriate responses to metal fluxes. This review focuses on the metal stresses encountered by Salmonella during infection and the roles of the different metal-sensing regulatory proteins and their target genes in adapting to these changing metal levels. Current knowledge regarding the mechanisms of metal-regulated gene expression and the structural features of sensory metal binding sites are described. In addition, the principles governing the ability of the different sensors to detect specific metals within a cell to control cytosolic metal levels are also discussed. These proteins represent potential targets for the development of new therapeutic approaches.

Rac1-dependent intracellular superoxide formation mediates vascular endothelial growth factor-induced placental angiogenesis in vitro

Vascular endothelial growth factor (VEGF) is one of the best characterized angiogenic factors controlling placental angiogenesis; however, how VEGF regulates placental angiogenesis has not yet completely understood. In this study, we found that all the components of assembling a functional NADPH oxidase (NOX2, p22(phox), p47(phox), p67(phox), and Rac1) are expressed in ovine fetoplacental artery endothelial cells (oFPAECs) in vitro and ex vivo. Treatment with VEGF (10 ng/ml) rapidly and transiently activated Rac1 in oFPAECs in vitro and increased Rac1 association with p67(phox) in 5 min. Intracellular superoxide formation began to significantly increase after 25-30 min of VEGF stimulation, which was mediated by both VEGFR1 and VEGFR2. VEGF also stimulated oFPAE cell proliferation and migration and enhanced the formation of tube-like structures on Matrigel matrix. In oFAPEC transfected with specific Rac1 small interfering RNA (siRNA, 40 nm), VEGF-induced intracellular superoxide formation was completely abrogated in association with a 78% reduction of endogenous Rac1. In oFPAE cells transfected with the specific Rac1 siRNA, but not with transfection reagent alone or scrambled control siRNA, VEGF-induced cell proliferation, migration, and tube-like structure formation were dramatically inhibited. Pretreatment of an NADPH oxidase inhibitor apocynin also abrogates the VEGF-stimulated intracellular superoxide production and DNA synthesis in oFPAECs. Taken together, our results demonstrated that a Rac1/Nox2-based NADPH oxidase system is present in placental endothelial cells. This NADPH oxidase system appears to generate the second messenger superoxide that plays a critical role in the signaling control of the VEGF-induced placental angiogenesis.

Oxidative and nitrosative responses of the chicken macrophage cell line MQ-NCSU to experimentalSalmonellainfection

Phagocytes limit replication or kill ingested organisms by producing toxic reactive oxygen and nitrogen species via NADPH oxidase and inducible nitric oxide synthase (iNOS). The present experiments were to investigate the production and the possible roles of superoxide, hydrogen peroxide (H2O2) and nitric oxide (NO) in the MQ-NCSU chicken macrophage cell line infected with Salmonella in vitro. After infection, intracellular Salmonella viable counts remained constant until 24 h post infection (PI) and started to decline from 48 h PI. Infection of cells with S. Typhimurium, S. Enteritidis and S. Gallinarum, as well as exposure to S. Enteritidis LPS induced low, but significant concentrations of superoxide 1 to 2 h PI, as determined by reduction of ferricytochrome c. There was no difference in superoxide production in infected cells and control cells after 4 h. Increased H2O2 was observed from cells infected with all the different Salmonella species between 2 and 3 h of infection. Nitrite was always greater in infected cells compared to uninfected cells at all times. However, Salmonella was not completely eliminated from the cells though these cells are capable of eliciting a noticeable oxidative burst response and great nitrosative responses, indicating that a strong oxidative burst (and other mechanism/s) is essential for the elimination of intracellular Salmonella.

TLR2 enhances NADPH oxidase activity and killing of Staphylococcus aureus by PMN

Toll-like receptors play an essential role in the detection of invading pathogens. TLR2 is expressed in high concentrations on neutrophils and has been implicated as a critical mediator inducing host antimicrobial defenses against Gram-positive bacteria. Neutrophil responses induced via TLR2 are likely to have important clinical consequences, since Gram-positive organisms, such as Staphylococcus aureus, are an increasingly important source of severe infections. In the present study, we report that TLR2 has a central role in killing of S. aureus by murine PMN via enhancement of NADPH oxidase activity. PMN from TLR2-deficient mice showed a similar inability to kill S. aureus in vitro and under in vivo-like conditions as PMN with a non-functional NADPH oxidase. This defect in killing by TLR2-deficient PMN was not related to phagocytosis but caused by delayed and reduced NADPH oxidase-mediated production of superoxide anion in response to S. aureus and other Gram-positive bacteria. The cause of this was independent of PI3K- and p38 signaling. The TLR2-enhanced induction of superoxide was a defect in proper NADPH oxidase assembly. We hypothesize that early activation of TLR2-signaling may enhance p47(phox) phosphorylation subsequent to phagocytosis-mediated phosphorylation. Summarized, these data demonstrate a novel role of TLR2 in the killing of S. aureus by ensuring a rapid activation of the NADPH oxidase complex.

Reactive oxygen species in cancer

Elevated rates of reactive oxygen species (ROS) have been detected in almost all cancers, where they promote many aspects of tumour development and progression. However, tumour cells also express increased levels of antioxidant proteins to detoxify from ROS, suggesting that a delicate balance of intracellular ROS levels is required for cancer cell function. Further, the radical generated, the location of its generation, as well as the local concentration is important for the cellular functions of ROS in cancer. A challenge for novel therapeutic strategies will be the fine tuning of intracellular ROS signalling to effectively deprive cells from ROS-induced tumour promoting events, towards tipping the balance to ROS-induced apoptotic signalling. Alternatively, therapeutic antioxidants may prevent early events in tumour development, where ROS are important. However, to effectively target cancer cells specific ROS-sensing signalling pathways that mediate the diverse stress-regulated cellular functions need to be identified. This review discusses the generation of ROS within tumour cells, their detoxification, their cellular effects, as well as the major signalling cascades they utilize, but also provides an outlook on their modulation in therapeutics.

Microarray analysis of response of Salmonella during infection of HLA-B27- transfected human macrophage-like U937 cells

BACKGROUND

Human leukocyte antigen (HLA)-B27 is strongly associated with the development of reactive arthritis (ReA) in humans after salmonellosis. Human monocytic U937 cells transfected with HLA-B27 are less able to eliminate intracellular Salmonella enterica serovar Enteritidis than those transfected with control HLA antigens (e.g. HLA-A2). To investigate further the mechanisms by which HLA-B27-transfected cells allow increased replication of these bacteria, a DNA-based microarray was used for comparative genomic analysis of S. Enteritidis grown in HLA-B27- or HLA-A2-transfected cells. The microarray consisted of 5080 oligonucleotides from different serovars of Salmonella including S. Enteritidis PT4-specific genes. Bacterial RNA was isolated from the infected HLA-B27- or HLA-A2-transfected cells, reverse-transcribed to cDNA, and hybridized with the oligonucleotides on the microarrays. Some microarray results were confirmed by RT-PCR.

RESULTS

When gene expression was compared between Salmonella grown in HLA-B27 cells and in HLA-A2 cells, 118 of the 4610 S. Enteritidis-related genes differed in expression at 8 h after infection, but no significant difference was detectable at 2 h after infection. These differentially expressed genes are mainly involved in Salmonella virulence, DNA replication, energy conversion and metabolism, and uptake and metabolism of nutrient substances, etc. The difference suggests HLA-B27-dependent modulation of Salmonella gene expression, resulting in increased Salmonella replication in HLA-B27-positive cells. Among the up-regulated genes were those located in Salmonella pathogenicity island (SPI)-2, which play a central role in intracellular survival and replication of Salmonella.

CONCLUSIONS

This is the first report to show the regulation of Salmonella gene expression by HLA-B27 during infection of host cells. This regulation probably leads to increased Salmonella survival and replication in HLA-B27-positive cells. SPI-2 genes seem to contribute significantly to the increased replication.

Redox control of vascular smooth muscle migration

Vascular smooth muscle cell migration is important during vascular development and contributes to lesion formation in the adult vasculature. The mechanisms regulating migration of this cell type are therefore of great interest. Recent work has shown that reactive oxygen species (ROS) derived from NADPH oxidases are important mediators of promigratory signaling pathways. ROS regulate the intracellular signals responsible for lamellipodia formation, actin cytoskeleton remodeling, focal adhesion turnover, and contraction of the cell body. In addition, they contribute to matrix remodeling, a critical step to initiate and support vascular smooth muscle cell motility. Despite these recent advances in our understanding of the redox mechanisms that contribute to migration, additional work is needed to evaluate fully the potential of ROS-sensitive molecular signals as therapeutic targets to prevent inappropriate smooth muscle cell migration.

Impaired macrophage function following bacterial stimulation in chronic granulomatous disease

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is critical for phagocyte anti-microbial activity and plays a major role in innate immunity. Defects in genes coding for components of the NADPH oxidase enzyme system are responsible for chronic granulomatous disease (CGD), a rare primary neutrophil immunodeficiency associated with recurrent, life-threatening bacterial and fungal infections. Microbial killing and digestion within the neutrophil phagosomal compartment are defective in these patients. NADPH oxidase activity is also crucial for optimal macrophage and dendritic cell function and has recently been implicated in both cross-presentation and T-cell priming. We present evidence of impaired macrophage function in CGD, with attenuated pro-inflammatory cytokine and increased interleukin-10 secretion following bacterial stimulation. These results highlight additional abnormalities in macrophage function associated with CGD and the importance of NADPH oxidase activity in immunity.

Neutrophil antimicrobial defense against Staphylococcus aureus is mediated by phagolysosomal but not extracellular trap-associated cathelicidin

Neutrophils kill invading pathogens by AMPs, including cathelicidins, ROS, and NETs. The human pathogen Staphylococcus aureus exhibits enhanced resistance to neutrophil AMPs, including the murine cathelicidin CRAMP, in part, as a result of alanylation of teichoic acids by the dlt operon. In this study, we took advantage of the hypersusceptible phenotype of S. aureus DeltadltA against cationic AMPs to study the impact of the murine cathelicidin CRAMP on staphylococcal killing and to identify its key site of action in murine neutrophils. We demonstrate that CRAMP remained intracellular during PMN exudation from blood and was secreted upon PMA stimulation. We show first evidence that CRAMP was recruited to phagolysosomes in infected neutrophils and exhibited intracellular activity against S. aureus. Later in infection, neutrophils produced NETs, and immunofluorescence revealed association of CRAMP with S. aureus in NETs, which similarly killed S. aureus wt and DeltadltA, indicating that CRAMP activity was reduced when associated with NETs. Indeed, the presence of DNA reduced the antimicrobial activity of CRAMP, and CRAMP localization in response to S. aureus was independent of the NADPH oxidase, whereas killing was partially dependent on a functional NADPH oxidase. Our study indicates that neutrophils use CRAMP in a timed and locally coordinated manner in defense against S. aureus.

Syndecan-1, a new target molecule involved in progression of androgen-independent prostate cancer

Heparan sulfate proteoglycan syndecan-1 (CD138) is well known to be associated with cell proliferation, adhesion and migration in various types of malignancies. In the present study, we focused on the role of syndecan-1 in human prostate cancer. Immunohistochemical analysis revealed either no or rare expression of syndecan-1 in normal secretory glands and prostate cancer cells at hormone naïve status, whereas the expression was significantly increased in viable cancer cells following neo-adjuvant hormonal therapy. Syndecan-1 expression was much higher in the androgen independent prostate cancer cell lines DU145 and PC3, rather than the androgen-dependent LNCaP, but the level in LNCaP was up-regulated in response to long-term culture under androgen deprivation. Silencing of syndecan-1 by siRNA transfection reduced endogenous production of reactive oxygen species through down-regulating NADPH oxidase 2 and induced apoptosis in DU145 and PC3 cells. Consistently, NADPH oxidase 2 knockdown induced apoptosis to a similar extent. Subcutaneous inoculation of PC3 cells in nude mice demonstrated the reduction of tumor size by localized injection of syndecan-1 siRNA in the presence of atelocollagen. Moreover, the mouse model and chorioallantoic membrane assay demonstrated significant inhibition of vascular endothelial growth factor and tumor angiogenesis by silencing of syndecan-1. In conclusion, syndecan-1 might participate in the process of androgen-dependent to -independent conversion, and be a new target molecule for hormone resistant prostate cancer therapy.

Caenorhabditis elegans and human dual oxidase 1 (DUOX1) "peroxidase" domains: insights into heme binding and catalytic activity

The seven members of the NOX/DUOX family are responsible for generation of the superoxide and H(2)O(2) required for a variety of host defense and cell signaling functions in nonphagocytic cells. Two members, the dual oxidase isozymes DUOX1 and DUOX2, share a structurally unique feature: an N-terminal peroxidase-like domain. Despite sequence similarity to the mammalian peroxidases, the absence of key active site residues makes their binding of heme and their catalytic function uncertain. To explore this domain we have expressed in a baculovirus system and purified the Caenorhabditis elegans (CeDUOX1(1-589)) and human (hDUOX1(1-593)) DUOX1 "peroxidase" domains. Evaluation of these proteins demonstrated that the isolated hDUOX1(1-593) does not bind heme and has no intrinsic peroxidase activity. In contrast, CeDUOX1(1-589) binds heme covalently, exhibits a modest peroxidase activity, but does not oxidize bromide ion. Surprisingly, the heme appears to have two covalent links to the protein despite the absence of a second conserved carboxyl group in the active site. Although the N-terminal dual oxidase motif has been proposed to directly convert superoxide to H(2)O(2), neither DUOX1 domain demonstrated significant superoxide dismutase activity. These results strengthen the in vivo conclusion that the CeDUOX1 protein supports controlled peroxidative polymerization of tyrosine residues and indicate that the hDUOX1 protein either has a unique function or must interact with other protein factors to express its catalytic activity.

Differential expression from two iron-responsive promoters in Salmonella enterica serovar Typhimurium reveals the presence of iron in macrophage-phagosomes

The metal status of macrophage-phagosomes during Salmonella infection is largely unknown. In this study, we have precisely calibrated the metal-specificities of two metal-responsive promoters, P(iroBCDE) and P(sodB), from Salmonella enterica serovar Typhimurium and used these to directly monitor iron-levels in Salmonella-containing macrophage-phagosomes. Expression from the P(iroBCDE) promoter is highly elevated in metal-depleted media but low in media supplemented with iron or cobalt, and to a lesser extent manganese. In contrast, P(sodB) shows low levels of expression in metal-depleted media but is induced in media supplemented with iron but no other metals at maximum permissive concentrations. In both cases, iron-responsive expression corresponds to changes in the number of iron atoms per bacterial cell and is unaffected by pH or the presence of reactive oxygen species (hydrogen peroxide and superoxide). Importantly, expression from P(iroBCDE) remained low while expression from P(sodB) was elevated during infection of both Nramp1(+/+) and Nramp1(-/-) macrophages. Expression from a control promoter, P(polA), unaffected by metal ions, remained unchanged. These findings are therefore consistent with the presence of iron within Salmonella-containing macrophage-phagosomes and support a model in which the toxic potential of iron may be exploited as a component of the respiratory burst killing mechanism.

Inhibitory action of NoxA1 on dual oxidase activity in airway cells

Imbalance between pro- and antioxidant mechanisms in the lungs can compromise pulmonary functions, including blood oxygenation, host defense, and maintenance of an anti-inflammatory environment. Thus, tight regulatory control of reactive oxygen species is critical for proper lung function. Increasing evidence supports a role for the NADPH oxidase dual oxidase (Duox) as an important source for regulated H2O2 production in the respiratory tract epithelium. In this study Duox expression, function, and regulation were investigated in a fully differentiated, mucociliary airway epithelium model. Duox-mediated H2O2 generation was dependent on calcium flux, which was required for dissociation of the NADPH oxidase regulatory protein Noxa1 from plasma membrane-bound Duox. A functional Duox1-based oxidase was reconstituted in model cell lines to permit mutational analysis of Noxa1 and Duox1. Although the activation domain of Noxa1 was not required for Duox function, mutation of a proline-rich domain in the Duox C terminus, a potential interaction motif for the Noxa1 Src homology domain 3, caused up-regulation of basal and stimulated H2O2 production. Similarly, knockdown of Noxa1 in airway cells increased basal H2O2 generation. Our data indicate a novel, inhibitory function for Noxa1 in Duox regulation. This represents a new paradigm for control of NADPH oxidase activity, where second messenger-promoted conformational change of the Nox structure promotes oxidase activation by relieving constraint induced by regulatory components.

Reactive oxygen species and angiogenesis: NADPH oxidase as target for cancer therapy

Angiogenesis is essential for tumor growth, metastasis, arteriosclerosis as well as embryonic development and wound healing. Its process is dependent on cell proliferation, migration and capillary tube formation in endothelia cells (ECs). High levels of reactive oxygen species (ROS) such as superoxide and H2O2 are observed in various cancer cells. Accumulating evidence suggests that ROS function as signaling molecules to mediate various growth-related responses including angiogenesis. ROS-dependent angiogenesis can be regulated by endogenous antioxidant enzymes such as SOD and thioredoxin. Vascular endothelial growth factor (VEGF), one of the major angiogenesis factor, is induced in growing tumors and stimulates EC proliferation and migration primarily through the VEGF receptor type2 (VEGFR2, Flk1/KDR). Major source of ROS in ECs is a NADPH oxidase which consists of Nox1, Nox2, Nox4, Nox5, p22phox, p47phox and the small G-protein Rac1. NADPH oxidase is activated by various growth factors including VEGF and angiopoietin-1 as well as hypoxia and ischemia, and ROS derived from this oxidase are involved in VEGFR2 autophosphorylation, and diverse redox signaling pathways leading to induction of transcription factors and genes involved in angiogenesis. Dietary antioxidants appear to be effective for treatment of tumor angiogenesis. The aim of this review is to provide an overview of the recent progress on role of ROS derived from NADPH oxidase and redox signaling events involved in angiogenesis. Understanding these mechanisms may provide insight into the NADPH oxidase and redox signaling components as potential therapeutic targets for tumor angiogenesis.

Mechanism of apoptosis induced by apigenin in HepG2 human hepatoma cells: involvement of reactive oxygen species generated by NADPH oxidase

Although plant-derived flavonoids have been reported to have anti-cancer activities, the exact mechanism of these actions is not completely understood. In this study we investigated the role for reactive oxygen species (ROS) as a mediator of the apoptosis induced by apigenin, a widespread flavonoid in plant, in HepG2 human hepatoma cells. Apigenin reduced cell viability, and induced apoptotic cell death in a dose-dependent manner. In addition, it evoked a dose-related elevation of intracellular ROS level. Treatment with various inhibitors of the NADPH oxidase (diphenylene iodonium, apocynin, neopterine) significantly blunted both the generation of ROS and induction of apoptosis induced by apigenin. These results suggest that ROS generated through the activation of the NADPH oxidase may play an essential role in the apoptosis induced by apigenin in HepG2 cells. These results further suggest that apigenin may be valuable for the therapeutic management of human hepatomas.

Myeloperoxidase and chlorinated peptides in osteoarthritis: potential biomarkers of the disease

Osteoarthritis (OA) is a disabling condition in which multiple initiating events or conditions (heritable and nonheritable) result in eventual loss of articular cartilage. However, the etiology of OA remains poorly understood, and diagnosis of early disease is difficult due to the lack of specific identifiers. Recent literature suggests that a series of inflammatory processes may be involved in initiating and propagating OA. We hypothesized that products of neutrophils and macrophages, namely myeloperoxidase (MPO), a specific enzyme responsible for the production of both highly reactive hypochlorous acid (HOCl) and chlorine gas (Cl(2)) and chlorinated peptides, may be present in the synovial fluid of patients with OA. We examined the synovial fluid from 30 patients to identify and profile the presence of MPO. We divided the samples into three groups using radiographic and clinical assessment: (1) control, patients with acute knee injury with no history of OA and no radiographic evidence of OA; (2) early OA, patients with a mild OA based on radiographs; and (3) late OA, patients with a longstanding history of OA and with radiographic evidence of complete joint loss. Patients with early OA demonstrated significantly elevated levels of MPO. We also demonstrated the presence of HOCl and Cl(2) modified proteins (Cl-peptides) in early OA synovial fluid samples by liquid chromatography and mass spectrometry. Patients in the control and advanced OA groups demonstrated little elevation in MPO levels and Cl-peptides were undetectable. These results indicate that MPO and Cl-peptides may serve as diagnostic markers for the detection of early OA.

Lipoamide dehydrogenase mediates retention of coronin-1 on BCG vacuoles, leading to arrest in phagosome maturation

Mycobacterium tuberculosis evades the innate antimicrobial defenses of macrophages by inhibiting the maturation of its phagosome to a bactericidal phagolysosome. Despite intense studies of the mycobacterial phagosome, the mechanism of mycobacterial persistence dependent on prolonged phagosomal retention of the coat protein coronin-1 is still unclear. The present study demonstrated that several mycobacterial proteins traffic intracellularly in M. bovis BCG-infected cells and that one of them, with an apparent subunit size of M(r) 50,000, actively retains coronin-1 on the phagosomal membrane. This protein was initially termed coronin-interacting protein (CIP)50 and was shown to be also expressed by M. tuberculosis but not by the non-pathogenic species M. smegmatis. Cell-free system experiments using a GST-coronin-1 construct showed that binding of CIP50 to coronin-1 required cholesterol. Thereafter, mass spectrometry sequencing identified mycobacterial lipoamide dehydrogenase C (LpdC) as a coronin-1 binding protein. M. smegmatis over-expressing Mtb LpdC protein acquired the capacity to maintain coronin-1 on the phagosomal membrane and this prolonged its survival within the macrophage. Importantly, IFNgamma-induced phagolysosome fusion in cells infected with BCG resulted in the dissociation of the LpdC-coronin-1 complex by a mechanism dependent, at least in part, on IFNgamma-induced LRG-47 expression. These findings provide further support for the relevance of the LpdC-coronin-1 interaction in phagosome maturation arrest.

Effect of quercitrin gallate on zymosan A-lnduced peroxynitrite production in macrophages

We previously isolated quercetin 3-O-beta-(2"-galloyl)-rhamnopyranoside (QGR), a quercitrin gallate, from aerial parts of Persicaria lapathifolia (Polygonaceae) to prevent superoxide produc tion in monocytes from venous blood of healthy human donors. In this study, effects of QGR and its building moieties (quercitrin, quercetin and gallic acid) on the production of peroxyni trite, a coupling oxidant between superoxide and nitric oxide (NO) radicals, were investigated in zymosan A-stimulated macrophages RAW 264.7. The QGR, quercitrin and quercetin inhib ited peroxynitrite production in dose-dependent manners with IC50 values of 2.1 microM, 24.5 microM and 5.1 microM, respectively, but gallic acid even at 100 microM was inactive. QGR also inhibited both zymosan A- and phorbol 12-myristate 13-acetate-induced superoxide productions with IC50 values of 3.2 microM and 4.7 microM, respectively. However, QGR affected neither zymosan A-induced NO production nor inducible NO synthase synthesis. Taken together, QGR could inhibit peroxynitrite production by blocking superoxide production without affecting NO production. Finally, this study could provide a pharmacological potential of QGR in the oxidative stress-implicated disorders.

Mucin overproduction in chronic inflammatory lung disease

Mucus overproduction and hypersecretion are commonly observed in chronic inflammatory lung disease. Mucins are gel-forming glycoproteins that can be stimulated by a variety of mediators. The present review addresses the mechanisms involved in the upregulation of secreted mucins. Mucin induction by neutrophil elastase, bacteria, cytokines, growth factors, smoke and cystic fibrosis transmembrane conductance regulator malfunction are also discussed.