Respiratory Burst Of Phagocytic Cells Research Articles

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.3

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.3

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.2

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.2

The methylglyoxal pathway is a sink for glutathione in Salmonella experiencing oxidative stress.

Salmonella suffer the cytotoxicity of reactive oxygen species generated by the phagocyte NADPH oxidase in the innate host response. Periplasmic superoxide dismutases, catalases and hydroperoxidases detoxify superoxide and hydrogen peroxide (H2O2) synthesized in the respiratory burst of phagocytic cells. Glutathione also helps Salmonella combat the phagocyte NADPH oxidase; however, the molecular mechanisms by which this low-molecular-weight thiol promotes resistance of Salmonella to oxidative stress are currently unknown. We report herein that Salmonella undergoing oxidative stress transcriptionally and functionally activate the methylglyoxal pathway that branches off from glycolysis. Activation of the methylglyoxal pathway consumes a substantial proportion of the glutathione reducing power in Salmonella following exposure to H2O2. The methylglyoxal pathway enables Salmonella to balance glucose utilization with aerobic respiratory outputs. Salmonella take advantage of the metabolic flexibility associated with the glutathione-consuming methylglyoxal pathway to resist reactive oxygen species generated by the enzymatic activity of the phagocyte NADPH oxidase in macrophages and mice. Taken together, glutathione fosters oxidative stress resistance in Salmonella against the antimicrobial actions of the phagocyte NADPH oxidase by promoting the methylglyoxal pathway, an offshoot metabolic adaptation of glycolysis.

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.1

Transient Receptor Potential channels (TRP) in GtoPdb v.2023.1

Transient Receptor Potential channels (TRP) in GtoPdb v.2022.1

Transient Receptor Potential channels (TRP) in GtoPdb v.2022.1

Transient Receptor Potential channels (TRP) in GtoPdb v.2021.3

Transient Receptor Potential channels (TRP) in GtoPdb v.2021.3

Transient Receptor Potential channels (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

Transient Receptor Potential channels (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

METHODS OF ESTIMATION AND THE ROLE OF RESPIRATORY BURST IN THE PATHOGENESIS OF INFECTIOUS AND INFLAMMATORY DISEASES

According to the modern concepts the respiratory burst directly related to the processes of phagocytosis characterizes the functional activity of phagocytic cells. This review presents modern methods for assessing the respiratory burst state of phagocytes based on cytofluorometric and chemiluminescent analysis. The sequence and mechanisms of the reactions of reactive oxygen species (ROS) synthesis in the process of respiratory cell burst are presented in detail. The sequence of synthesis from ROS with low bactericidal activity to ROS with high bactericidal activity is characterized. The review describes in detail the most popular dyes for cytofluorometric analysis to assess the levels of ROS synthesis. Characteristics and examples of the use of such dyes as dihydroethidine, dichlorodihydrofluorescein and dihydrorhodamine 123 are given. The main stages and mechanisms of the chemiluminescence reaction are presented. The features of the use of the main indicators (luminol and lucigenin) of the chemiluminescence reaction are described. A mechanism for estimating the parameters of the chemiluminescence reaction characterizing the features of the state and kinetics of the respiratory burst of phagocytic cells is given. The separate section of the review is devoted to the role of a respiratory burst in phagocytic cells in various immunopathological states. Data on the pathogenetic significance of changes in the intensity and kinetics of respiratory burst of phagocytes in infectious, inflammatory and oncological diseases were presented. Examples of new methods for diagnosing and predicting the course of the immunopathological states characters are presented on the basis of an assessment of the respiratory burst of phagocytic cells. The literature data show that at present, in the diagnosis and evaluation of the nature of the diseases characters the state of a respiratory burst is evaluated in various types of cells of innate immunity: neutrophils, monocytes, etc. It is concluded that the evaluation of the respiratory burst of phagocytic cells can be characterized as the fundamental mechanisms of reacting cells of innate immunity to pathogenic and regulatory effects, so to develop new highly sensitive methods for diagnosing and predicting the development and outcome of various immunopathological conditions. The presented methods of flow cytometry and chemiluminescence analysis make it possible to determine both the integral state of the respiratory explosion, and the levels and kinetic parameters of the synthesis of individual ROS.

The effect of core and lanthanide ion dopants in sodium fluoride-based nanocrystals on phagocytic activity of human blood leukocytes

Sodium fluoride-based β-NaLnF4 nanoparticles (NPs) doped with lanthanide ions are promising materials for application as luminescent markers in bio-imaging. In this work, the effect of NPs doped with yttrium (Y), gadolinium (Gd), europium (Eu), thulium (Tm), ytterbium (Yb) and terbium (Tb) ions on phagocytic activity of monocytes and granulocytes and the respiratory burst was examined. The surface functionalization of <10-nm NPs was performed according to our variation of patent pending ligand exchange method that resulted in meso-2,3-dimercaptosuccinic acid (DMSA) molecules on their surface. Y-core-based NCs were doped with Eu ions, which enabled them to be excited with UV light wavelengths. Cultures of human peripheral blood (n = 8) were in vitro treated with five different concentrations of eight NPs for 24 h. In summary, neither type of nanoparticles is found toxic with respect to conducted test; however, some cause toxic effects (they have statistically significant deviations compared to reference) in some selected doses tested. Both core types of NPs (Y-core and Gd-core) impaired the phagocytic activity of monocytes the strongest, having minimal or none whatsoever influence on granulocytes and respiratory burst of phagocytic cells. The lowest toxicity was observed in Gd-core, Yb, Tm dopants and near-infrared nanoparticles. Clear dose-dependent effect of NPs on phagocytic activity of leukocytes and respiratory burst of cells was observed for limited number of samples.

Superoxide dismutase of Streptococcus suis serotype 2 plays a role in anti-autophagic response by scavenging reactive oxygen species in infected macrophages

Streptococcus suis serotype 2 (SS2) causes septic shock and meningitis. However, its pathogenesis is still not well-understood. We have recently shown that superoxide dismutase sodA of SS2 is a virulence factor probably by increasing resistance to oxidative stresses. Reactive oxygen species (ROS) are products of the respiratory burst of phagocytic cells and have been shown to activate autophagy. We wanted to know if and how SS2 explores its sodA to interfere with cell autophagic responses. A sodA deletion mutant (Δsod) was compared with its parent and complemented strain in autophagic response in the murine macrophage cell line RAW264.7. We found that the Δsod mutant induced significant autophagic responses in infected cells, shown as increased LC3 lipidation (LC3-II) and EGFP-LC3 punctae, than those infected by its parent or complemented strain at 1 or 2h post-infection. Co-localization of the autophagosomal EGFP-LC3 vesicles with lysosomes was seen in cells infected with Δsod mutant and its parent strain, indicating that SS2 infection induced complete autophagic responses. Reduced autophagic responses of cells infected with the wild-type strain might be related to decreased ROS by the scavenging effect of its sodA, as shown by increased superoxide anion or ROS level in cells infected with the Δsod mutant and in the cell free xanthine oxidase–hypoxanthine ROS-generating system, as compared with its parent or complemented strain. Taken together, SS2 makes use of its sodA for survival not only by scavenging ROS but also by alleviating the host autophagic responses due to ROS stimulation.

Immunomudulatory effects of hydroalcoholic extract of Hypericum perforatum.

Hypericum perforatum (St. John's Wort) has long been used in traditional medicine to treat a variety of internal and external ailments. The present study was done to evaluate the immumodulatory potentials of the hydroalcoholic extract of H. perforatum. Twenty male BALB/c-mice were randomly allocated in two equal groups and immunized with sheep red blood cells (SRBCs) and complete Freund's adjuvant. Mice in the treatment group orally received hydroalcoholic extract of H. perforatum (110 mg/Kg daily) from the beginning of the study which continued for 2 weeks. The data indicated a significant increase in the level of anti-SRBC antibody and simultaneously a significant decrease in the level of cellular immunity, an enhancement in foot pad thickness, in treatment group compared to control group. The level of the respiratory burst in phagocytic cells and the level of lymphocyte proliferation in splenocytes were significantly decreased in the treatment group compared to control group. Moreover, extract caused a significant reduction in the production of pro-inflammatory IL-17 as well as IFN-γ, parallel to increasing the level of IL-6. The hydroalcoholic extract of H. perforatum may be used as a natural source for treatment of immunopathologic conditions.

Risk Factors for high serum SeM titers after natural outbreaks of Streptococcus equi equi in horses

Rhodococcosis classically caused severe lung affections as suppurative bronchopneumonia and sometimes unusual forms as digestive or bone forms. R. equi is able to survive and multiply in macrophages despite unsuitable conditions, caused notably by reactive oxygen metabolites such as hydrogen peroxide (H2O2) generated during the respiratory burst of phagocytic cells. It was known that R. equi presents a great capacity of resistance to H2O2 exposition independently to the presence of the virulence plasmid. Recently, the analysis of R. equi 103 genome revealed the presence of four potential catalase genes named katA to katD. The aim of this study was to determine the implication of each catalase in R. equi oxidative stress resistance. For that, we used the R. equi 103 plasmid-less strain to construct four catalase deficient mutants, each lacking one catalase gene to obtain DkatA, DkatB, DkatC and DkatD. Survivals of those mutants were analyzed in vitro after exposition to oxidative stress by H2O2 treatment and in vivo by survival assay in mouse peritoneal macrophages. A quantitative RT-PCR analysis of catalase genes expression levels, in R. equi 103 plasmid-less WT, after exposition to H2O2, was also performed. We observed that, after exposition to H2O2 in stationary or exponential phase, survival of DkatA was respectively completely abolished or decreased by two orders of magnitude, compared to the parental strain. Results showed also decrease by three orders of magnitude in DkatC survival after treatment in exponential phase. In vivo experiments in mice macrophages showed that DkatA was the most susceptible mutant and was completely eliminated from macrophages 72h post infection (Figure 1). The others mutants were more susceptible to elimination by macrophages than R. equi 103 WT, but were not completely eliminated 48h and 72h post infection (Figure 1). Quantitative RT-PCR results showed that external H2O2 exposition only increased katA gene expression. After treatment in stationary or exponential phase, katA was respectively overexpressed 367.9 ( 122.6) times and 3.11 ( 0.59) times, compared to untreated conditions. Taken together, our results revealed the main implication of KatA and in a less manner, KatC, in resistance to external H2O2 exposition. The role of the others catalases of R. equi 103 in oxidative stress resistance is not clearly demonstrated in our experimental conditions. In conclusion, this study highlights the main role of katA in response and resistance to external oxidative stress in R. equi 103 plasmid-less starin.

Rhodococcus equi’s Extreme Resistance to Hydrogen Peroxide Is Mainly Conferred by One of Its Four Catalase Genes

Rhodococcus equi is one of the most widespread causes of disease in foals aged from 1 to 6 months. R. equi possesses antioxidant defense mechanisms to protect it from reactive oxygen metabolites such as hydrogen peroxide (H2O2) generated during the respiratory burst of phagocytic cells. These defense mechanisms include enzymes such as catalase, which detoxify hydrogen peroxide. Recently, an analysis of the R. equi 103 genome sequence revealed the presence of four potential catalase genes. We first constructed ΔkatA-, ΔkatB-, ΔkatC-and ΔkatD -deficient mutants to study the ability of R. equi to survive exposure to H2O2 in vitro and within mouse peritoneal macrophages. Results showed that ΔkatA and, to a lesser extent ΔkatC, were affected by 80 mM H2O2. Moreover, katA deletion seems to significantly affect the ability of R. equi to survive within murine macrophages. We finally investigated the expression of the four catalases in response to H2O2 assays with a real time PCR technique. Results showed that katA is overexpressed 367.9 times (±122.6) in response to exposure to 50 mM of H2O2 added in the stationary phase, and 3.11 times (±0.59) when treatment was administered in the exponential phase. In untreated bacteria, katB, katC and katD were overexpressed from 4.3 to 17.5 times in the stationary compared to the exponential phase. Taken together, our results show that KatA is the major catalase involved in the extreme H2O2 resistance capability of R. equi.

Receptor Activation of NADPH Oxidases

Reactive oxygen species (ROS) have been implicated in many intra- and intercellular processes. High levels of ROS are generated as part of the innate immunity in the respiratory burst of phagocytic cells. Low levels of ROS, however, are generated in a highly controlled manner by various cell types to act as second messengers in redox-sensitive pathways. A NADPH oxidase has been initially described as the respiratory burst enzyme in neutrophils. Stimulation of this complex enzyme system requires specific signaling cascades linking it to membrane-receptor activation. Subsequently, a family of NADPH oxidases has been identified in various nonphagocytic cells. They mainly differ in containing one out of seven homologous catalytic core proteins termed NOX1 to NOX5 and DUOX1 or 2. NADPH oxidase activity is controlled by regulatory subunits, including the NOX regulators p47phox and p67phox, their homologs NOXO1 and NOXA1, or the DUOX1 or 2 regulators DUOXA1 and 2. In addition, the GTPase Rac modulates activity of several of these enzymes. Recently, additional proteins have been identified that seem to have a regulatory function on NADPH oxidase activity under certain conditions. We will thus summarize molecular pathways linking activation of different membrane-bound receptors with increased ROS production of NADPH oxidases.

Novel sources of reactive oxygen species in the human body

There are several sources of reactive oxygen in the human body. Production of superoxide in mitochondria is a by-product of the function of the respiratory chain [1]. The first known example of regulated generation of reactive oxygen species (ROS) in mammalian cells was through the respiratory burst of phagocytic cells by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. This enzyme complex uses electrons derived from intracellular NADPH to generate superoxide anion, which is further processed to form hydrogen peroxide and other ROS-providing host defense against bacterial and fungal pathogens [2]. The essential role of the phagocytic oxidase in host defense is well illustrated by the serious phenotype of chronic granulomatous disease (CGD), in which susceptibility to infections develops in the absence of a functional phagocytic oxidase [3]. Non-mitochondrial production of ROS was detected in various cell types, showing that intentional generation of ROS is a general feature of many tissues, rather than a unique function of phagocytes. Homology searches in human genome databases resulted in the discovery of six novel NADPH oxidase enzymes: Nox1, Nox3, Nox4, Nox5, Duox1 and Duox2 [4–6]. They all have at least partially similar structure and generate ROS in response to various stimuli. The physiological function of these proteins and their potential role in the pathogenesis of human diseases is currently under intensive investigation. Structural aspects

The oxidative hypothesis of senescence

The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g, those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc). This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal beta -oxidation and respiratory burst of phagocytic cells), antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol), alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

Down-regulation of Rac Activity during β2 Integrin-mediated Adhesion of Human Neutrophils

In human neutrophils, beta2 integrin engagement mediated a decrease in GTP-bound Rac1 and Rac2. Pretreatment of neutrophils with LY294002 or PP1 (inhibiting phosphatidylinositol 3-kinase (PI 3-kinase) and Src kinases, respectively) partly reversed the beta2 integrin-induced down-regulation of Rac activities. In contrast, beta2 integrins induced stimulation of Cdc42 that was independent of Src family members. The PI 3-kinase dependence of the beta2 integrin-mediated decrease in GTP-bound Rac could be explained by an enhanced Rac-GAP activity, since this activity was blocked by LY204002, whereas PP1 only had a minor effect. The fact that only Rac1 but not Rac2 (the dominating Rac) redistributed to the detergent-insoluble fraction and that it was independent of GTP loading excludes the possibility that down-regulation of Rac activities was due to depletion of GTP-bound Rac from the detergent-soluble fraction. The beta2 integrin-triggered relocalization of Rac1 to the cytoskeleton was enabled by a PI 3-kinase-induced dissociation of Rac1 from LyGDI. The dissociations of Rac1 and Rac2 from LyGDI also explained the PI 3-kinase-dependent translocations of Rac GTPases to the plasma membrane. However, these accumulations of Rac in the membrane, as well as that of p47phox and p67phox, were also regulated by Src tyrosine kinases. Inasmuch as Rac GTPases are part of the NADPH oxidase and the respiratory burst is elicited in neutrophils adherent by beta2 integrins, our results indicate that activation of the NADPH oxidase does not depend on the levels of Rac-GTP but instead requires a beta2 integrin-induced targeting of the Rac GTPases as well as p47phox and p67phox to the plasma membrane.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation by silica in inflammation and fibrosis.

Exposure to particulate silica (most crystalline polymorphs) causes a persistent inflammation sustained by the release of oxidants in the alveolar space. Reactive oxygen species (ROS), which include hydroxyl radical, superoxide anion, hydrogen peroxide, and singlet oxygen, are generated not only at the particle surface, but also by phagocytic cells attempting to digest the silica particle. Two distinct kinds of surface centers-silica-based surface radicals and poorly coordinated iron ions-generate O(2)(*)(-) and HO(*) in aqueous solution via different mechanisms. Crystalline silica is also a potent stimulant of the respiratory burst in phagocytic cells with increased oxygen consumption and production of O(*)(-), H(2)O(2), and NO leading to acute inflammation and HO(*) generation in the lung. Oxidative stress elicited by crystalline silica is also evidenced by increased expression of antioxidant enzymes such as manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase, and the enzyme inducible nitric oxide synthase (iNOS). Generation of oxidants by crystalline silica particles and by silica-activated cells results in cell and lung injury, activation of cell signaling pathways to include MAPK/ERK kinase (MEK), and extracellular signal-regulated kinase (ERK) phosphorylation, increased expression of inflammatory cytokines (e.g., tumor necrosis factoralpha [TNFalpha], interleukin-1 [IL-1]), and activation of specific transcription factors (e.g., NFkappaB, AP-1). Silica can also initiate apoptosis in response to oxygen- and nitrogen-based free radicals, leading to mitochondrial dysfunction, increased gene expression of death receptors, and/or their ligands (TNFalpha, Fas ligand [FasL]).

Ambroxol inhibits peroxynitrite-induced damage of alpha1-antiproteinase and free radical production in activated phagocytic cells.

The present study examined the effect of ambroxol on toxic action of peroxynitrite and the respiratory burst in activated phagocytic cells. Ambroxol decreased the inactivation or destruction of alpha1-antiproteinase induced by peroxynitrite (ONOO-) or hypochlorous acid (HOCl), which was similar to penicillamine and glutathione and was greater than diclofenac sodium and naproxen sodium. Ambroxol significantly decreased ONOO--mediated tyrosine nitration and iron plus EDTA-mediated degradation of 2-deoxy-D-ribose. Ambroxol significantly attenuated the production of superoxide, hydrogen peroxide, HOCl, and nitric oxide in fMLP- or IL-1-activated phagocytic cells, while the inhibitory effects of antiinflammatory and thiol compounds were only observed in HOCl production. Ambroxol and antiinflammatory drugs did not show a cytotoxic effect on macrophages. The results suggest that ambroxol protects tissue components against oxidative damage by an action different from antiinflammatory drugs. Ambroxol may interfere with oxidative damage of alpha1-antiproteinase through a scavenging action on ONOO- and HOCl and inhibition of the respiratory burst of phagocytic cells.

Development of Functional Models for a SOD

Superoxide dismutase (SOD) is the scavenger of superoxide anion (O2−) and functions as a protector of living bodies. Study of a model compound of SOD is important when searching for the relationship between functions and structures of enzymes. Furthermore, SOD model compounds have potential for therapeutic usefulness. Although many SOD: model compounds have been reported, their structures are quite different from those of the native enzyme. Cu,Zn-SOD has been proposed for clinical uses. Unfortunately, many problems such as half-lifetime and antigenicity have not been overcome even though several copper(II) complexes are known to show SOD activity. Active oxygen species such as superoxide (O2−) from various components of the cellular electron transport chains, and provided during the respiratory burst of phagocytic cells, have been implicated both in the aging process and in degenerative diseases, including arthritis and cancer. Therefore, the biological system posseses the protective mechanisms against active species.