Dot/Icm-Dependent Restriction of Legionella pneumophila within Neutrophils

ABSTRACT The Dot/Icm type IV secretion system (T4SS) of Legionella pneumophila is essential for lysosomal evasion and permissiveness of macrophages for intracellular proliferation of the pathogen. In contrast, we show that polymorphonuclear cells (PMNs) respond to a functional Dot/Icm system through rapid restriction of L. pneumophila. Specifically, we show that the L. pneumophila T4SS-injected amylase (LamA) effector catalyzes rapid glycogen degradation in the PMNs cytosol, leading to cytosolic hyperglucose. Neutrophils respond through immunometabolic reprogramming that includes upregulated aerobic glycolysis. The PMNs become activated with spatial generation of intracellular reactive oxygen species within the Legionella-containing phagosome (LCP) and fusion of specific and azurophilic granules to the LCP, leading to rapid restriction of L. pneumophila. We conclude that in contrast to macrophages, PMNs respond to a functional Dot/Icm system, and specifically to the effect of the injected amylase effector, through rapid engagement of major microbicidal processes and rapid restriction of the pathogen. IMPORTANCE Legionella pneumophila is commonly found in aquatic environments and resides within a wide variety of amoebal hosts. Upon aerosol transmission to humans, L. pneumophila invades and replicates with alveolar macrophages, causing pneumonia designated Legionnaires’ disease. In addition to alveolar macrophages, neutrophils infiltrate into the lungs of infected patients. Unlike alveolar macrophages, neutrophils restrict and kill L. pneumophila, but the mechanisms were previously unclear. Here, we show that the pathogen secretes an amylase (LamA) enzyme that rapidly breakdowns glycogen stores within neutrophils, and this triggers increased glycolysis. Subsequently, the two major killing mechanisms of neutrophils, granule fusion and production of reactive oxygen species, are activated, resulting in rapid killing of L. pneumophila.

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Reactive oxygen species and caspase activation mediate silica-induced apoptosis in alveolar macrophages

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.2001.280.1.l10 ◽

2001 ◽

Vol 280 (1) ◽

pp. L10-L17 ◽

Cited By ~ 32

Author(s):

Han-Ming Shen ◽

Zhuo Zhang ◽

Qi-Feng Zhang ◽

Choon-Nam Ong

Keyword(s):

Reactive Oxygen Species ◽

Cell Death ◽

Alveolar Macrophages ◽

Caspase 3 ◽

Reactive Oxygen ◽

Parp Cleavage ◽

Oxygen Species ◽

Caspase Activation ◽

Caspase 9 ◽

Induced Apoptosis

Alveolar macrophages (AMs) are the principal target cells of silica and occupy a key position in the pathogenesis of silica-related diseases. Silica has been found to induce apoptosis in AMs, whereas its underlying mechanisms involving the initiation and execution of apoptosis are largely unknown. The main objective of the present study was to examine the form of cell death caused by silica and the mechanisms involved. Silica-induced apoptosis in AMs was evaluated by terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling assay and cell cycle/DNA content analysis. The elevated level of reactive oxygen species (ROS), caspase-9 and caspase-3 activation, and poly(ADP-ribose) polymerase (PARP) cleavage in silica-treated AMs were also determined. The results showed that there was a temporal pattern of apoptotic events in silica-treated AMs, starting with ROS formation and followed by caspase-9 and caspase-3 activation, PARP cleavage, and DNA fragmentation. Silica-induced apoptosis was significantly attenuated by a caspase-3 inhibitor, N-acetyl-Asp-Glu-Val-Asp aldehyde, and ebselen, a potent antioxidant. These findings suggest that apoptosis is an important form of cell death caused by silica exposure in which the elevated ROS level that results from silica exposure may act as an initiator, leading to caspase activation and PARP cleavage to execute the apoptotic process.

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Oxidative Stressors Modify the Response of Streptococcus mutans to Its Competence Signal Peptides

Applied and Environmental Microbiology ◽

10.1128/aem.01345-17 ◽

2017 ◽

Vol 83 (22) ◽

Cited By ~ 9

Author(s):

Matthew De Furio ◽

Sang Joon Ahn ◽

Robert A. Burne ◽

Stephen J. Hagen

Keyword(s):

Oxidative Stress ◽

Reactive Oxygen Species ◽

Dental Caries ◽

Signaling Pathway ◽

Streptococcus Mutans ◽

Reactive Oxygen ◽

Oxygen Species ◽

Oral Biofilm ◽

Genetic Competence ◽

Content Type

ABSTRACTThe dental caries pathogenStreptococcus mutansis continually exposed to several types of stress in the oral biofilm environment. Oxidative stress generated by reactive oxygen species has a major impact on the establishment, persistence, and virulence ofS. mutans. Here, we combined fluorescent reporter-promoter fusions with single-cell imaging to study the effects of reactive oxygen species on activation of genetic competence inS. mutans. Exposure to paraquat, which generates superoxide anion, produced a qualitatively different effect on activation of expression of the gene for the master competence regulator, ComX, than did treatment with hydrogen peroxide (H2O2), which can yield hydroxyl radical. Paraquat suppressed peptide-mediated induction ofcomXin a progressive and cumulative fashion, whereas the response to H2O2displayed a strong threshold behavior. Low concentrations of H2O2had little effect on induction ofcomXor the bacteriocin genecipB, but expression of these genes declined sharply if extracellular H2O2exceeded a threshold concentration. These effects were not due to decreased reporter gene fluorescence. Two different threshold concentrations were observed in the response to H2O2, depending on the gene promoter that was analyzed and the pathway by which the competence regulon was stimulated. The results show that paraquat and H2O2affect theS. mutanscompetence signaling pathway differently, and that some portions of the competence signaling pathway are more sensitive to oxidative stress than others.IMPORTANCEStreptococcus mutansinhabits the oral biofilm, where it plays an important role in the development of dental caries. Environmental stresses such as oxidative stress influence the growth ofS. mutansand its important virulence-associated behaviors, such as genetic competence.S. mutanscompetence development is a complex behavior that involves two different signaling peptides and can exhibit cell-to-cell heterogeneity. Although oxidative stress is known to influenceS. mutanscompetence, it is not understood how oxidative stress interacts with the peptide signaling or affects heterogeneity. In this study, we used fluorescent reporters to probe the effect of reactive oxygen species on competence signaling at the single-cell level. Our data show that different reactive oxygen species have different effects onS. mutanscompetence, and that some portions of the signaling pathway are more acutely sensitive to oxidative stress than others.

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Polymorphonuclear cells and reactive oxygen species in contagious bovine pleuropneumonia: New insight from in vitro investigations

Veterinary Immunology and Immunopathology ◽

10.1016/j.vetimm.2018.04.011 ◽

2018 ◽

Vol 201 ◽

pp. 16-19 ◽

Cited By ~ 2

Author(s):

Giovanni Di Teodoro ◽

Giuseppe Marruchella ◽

Francesco Mosca ◽

Andrea Di Provvido ◽

Flavio Sacchini ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Reactive Oxygen ◽

Polymorphonuclear Cells ◽

Oxygen Species ◽

Contagious Bovine Pleuropneumonia

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The Dynll1-Cox4i1 Complex Regulates Intracellular Pathogen Clearance via Release of Mitochondrial Reactive Oxygen Species

Infection and Immunity ◽

10.1128/iai.00738-19 ◽

2020 ◽

Vol 88 (4) ◽

Cited By ~ 2

Author(s):

Jiangbei Yuan ◽

Zihan Zheng ◽

Liting Wang ◽

Haiying Ran ◽

Xiangyu Tang ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Listeria Monocytogenes ◽

Membrane Proteins ◽

Defense Mechanisms ◽

Reactive Oxygen ◽

Cellular Membrane ◽

Oxygen Species ◽

Dynein Light Chain ◽

Mitochondrial Reactive Oxygen Species ◽

Content Type

ABSTRACT Cellular membrane proteins are a critical part of the host defense mechanisms against infection and intracellular survival of Listeria monocytogenes. The complex spatiotemporal regulation of bacterial infection by various membrane proteins has been challenging to study. Here, using mass spectrometry analyses, we depicted the dynamic expression landscape of membrane proteins upon L. monocytogenes infection in dendritic cells. We showed that Dynein light chain 1 (Dynll1) formed a persistent complex with the mitochondrial cytochrome oxidase Cox4i1, which is disturbed by pathogen insult. We discovered that the dissociation of the Dynll1-Cox4i1 complex is required for the release of mitochondrial reactive oxygen species and serves as a regulator of intracellular proliferation of Listeria monocytogenes. Our study shows that Dynll1 is an inhibitor of mitochondrial reactive oxygen species and can serve as a potential molecular drug target for antibacterial treatment.

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Ascorbate-Dependent Peroxidase (APX) from Leishmania amazonensis Is a Reactive Oxygen Species-Induced Essential Enzyme That Regulates Virulence

Infection and Immunity ◽

10.1128/iai.00193-19 ◽

2019 ◽

Vol 87 (12) ◽

Cited By ~ 1

Author(s):

Lucia Xiang ◽

Maria Fernanda Laranjeira-Silva ◽

Fernando Y. Maeda ◽

Jason Hauzel ◽

Norma W. Andrews ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Molecular Mechanisms ◽

Reactive Oxygen ◽

Oxygen Species ◽

Macrophage Infection ◽

Cutaneous Lesions ◽

Signaling Mechanism ◽

Content Type ◽

Temporal Regulation ◽

Metacyclic Promastigotes

ABSTRACT The molecular mechanisms underlying biological differences between two Leishmania species that cause cutaneous disease, L. major and L. amazonensis, are poorly understood. In L. amazonensis, reactive oxygen species (ROS) signaling drives differentiation of nonvirulent promastigotes into forms capable of infecting host macrophages. Tight spatial and temporal regulation of H2O2 is key to this signaling mechanism, suggesting a role for ascorbate-dependent peroxidase (APX), which degrades mitochondrial H2O2. Earlier studies showed that APX-null L. major parasites are viable, accumulate higher levels of H2O2, generate a greater yield of infective metacyclic promastigotes, and have increased virulence. In contrast, we found that in L. amazonensis, the ROS-inducible APX is essential for survival of all life cycle stages. APX-null promastigotes could not be generated, and parasites carrying a single APX allele were impaired in their ability to infect macrophages and induce cutaneous lesions in mice. Similar to what was reported for L. major, APX depletion in L. amazonensis enhanced differentiation of metacyclic promastigotes and amastigotes, but the parasites failed to replicate after infecting macrophages. APX expression restored APX single-knockout infectivity, while expression of catalytically inactive APX drastically reduced virulence. APX overexpression in wild-type promastigotes reduced metacyclogenesis, but enhanced intracellular survival following macrophage infection or inoculation into mice. Collectively, our data support a role for APX-regulated mitochondrial H2O2 in promoting differentiation of virulent forms in both L. major and L. amazonensis. Our results also uncover a unique requirement for APX-mediated control of ROS levels for survival and successful intracellular replication of L. amazonensis.

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Reactive oxygen species are required for driving efficient and sustained aerobic glycolysis during CD4+ T cell activation

PLoS ONE ◽

10.1371/journal.pone.0175549 ◽

2017 ◽

Vol 12 (4) ◽

pp. e0175549 ◽

Cited By ~ 29

Author(s):

Dana M. Previte ◽

Erin C. O’Connor ◽

Elizabeth A. Novak ◽

Christina P. Martins ◽

Kevin P. Mollen ◽

...

Keyword(s):

Reactive Oxygen Species ◽

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Aerobic Glycolysis ◽

Reactive Oxygen ◽

Cd4 T Cell ◽

Oxygen Species

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Arginine Biosynthesis Modulates Pyoverdine Production and Release in Pseudomonas putida as Part of the Mechanism of Adaptation to Oxidative Stress

Journal of Bacteriology ◽

10.1128/jb.00454-19 ◽

2019 ◽

Vol 201 (22) ◽

Cited By ~ 3

Author(s):

Laura Barrientos-Moreno ◽

María Antonia Molina-Henares ◽

Marta Pastor-García ◽

María Isabel Ramos-González ◽

Manuel Espinosa-Urgel

Keyword(s):

Oxidative Stress ◽

Reactive Oxygen Species ◽

Amino Acid ◽

Pseudomonas Putida ◽

Reactive Oxygen ◽

Full Detail ◽

Oxygen Species ◽

Arginine Biosynthesis ◽

Content Type ◽

And Oxidative Stress

ABSTRACT Iron is essential for most life forms. Under iron-limiting conditions, many bacteria produce and release siderophores—molecules with high affinity for iron—which are then transported into the cell in their iron-bound form, allowing incorporation of the metal into a wide range of cellular processes. However, free iron can also be a source of reactive oxygen species that cause DNA, protein, and lipid damage. Not surprisingly, iron capture is finely regulated and linked to oxidative-stress responses. Here, we provide evidence indicating that in the plant-beneficial bacterium Pseudomonas putida KT2440, the amino acid l-arginine is a metabolic connector between iron capture and oxidative stress. Mutants defective in arginine biosynthesis show reduced production and release of the siderophore pyoverdine and altered expression of certain pyoverdine-related genes, resulting in higher sensitivity to iron limitation. Although the amino acid is not part of the siderophore side chain, addition of exogenous l-arginine restores pyoverdine release in the mutants, and increased pyoverdine production is observed in the presence of polyamines (agmatine and spermidine), of which arginine is a precursor. Spermidine also has a protective role against hydrogen peroxide in P. putida, whereas defects in arginine and pyoverdine synthesis result in increased production of reactive oxygen species. IMPORTANCE The results of this study show a previously unidentified connection between arginine metabolism, siderophore turnover, and oxidative stress in Pseudomonas putida. Although the precise molecular mechanisms involved have yet to be characterized in full detail, our data are consistent with a model in which arginine biosynthesis and the derived pathway leading to polyamine production function as a homeostasis mechanism that helps maintain the balance between iron uptake and oxidative-stress response systems.

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The Helicobacter pylori CZB Cytoplasmic Chemoreceptor TlpD Forms an Autonomous Polar Chemotaxis Signaling Complex That Mediates a Tactic Response to Oxidative Stress

Journal of Bacteriology ◽

10.1128/jb.00071-16 ◽

2016 ◽

Vol 198 (11) ◽

pp. 1563-1575 ◽

Cited By ~ 23

Author(s):

Kieran D. Collins ◽

Tessa M. Andermann ◽

Jenny Draper ◽

Lisa Sanders ◽

Susan M. Williams ◽

...

Keyword(s):

Oxidative Stress ◽

Reactive Oxygen Species ◽

Helicobacter Pylori ◽

Molecular Mechanisms ◽

Reactive Oxygen ◽

Host Cells ◽

Oxygen Species ◽

Content Type ◽

Signaling Complex ◽

H Pylori

ABSTRACTCytoplasmic chemoreceptors are widespread among prokaryotes but are far less understood than transmembrane chemoreceptors, despite being implicated in many processes. One such cytoplasmic chemoreceptor isHelicobacter pyloriTlpD, which is required for stomach colonization and drives a chemotaxis response to cellular energy levels. Neither the signals sensed by TlpD nor its molecular mechanisms of action are known. We report here that TlpD functions independently of the other chemoreceptors. When TlpD is the sole chemoreceptor, it is able to localize to the pole and recruits CheW, CheA, and at least two CheV proteins to this location. It loses the normal membrane association that appears to be driven by interactions with other chemoreceptors and with CheW, CheV1, and CheA. These results suggest that TlpD can form an autonomous signaling unit. We further determined that TlpD mediates a repellent chemotaxis response to conditions that promote oxidative stress, including being in the presence of iron, hydrogen peroxide, paraquat, and metronidazole. Last, we found that all testedH. pyloristrains express TlpD, whereas other chemoreceptors were present to various degrees. Our data suggest a model in which TlpD coordinates a signaling complex that responds to oxidative stress and may allowH. pylorito avoid areas of the stomach with high concentrations of reactive oxygen species.IMPORTANCEHelicobacter pylorisenses its environment with proteins called chemoreceptors. Chemoreceptors integrate this sensory information to affect flagellum-based motility in a process called chemotaxis. Chemotaxis is employed during infection and presumably aidsH. pyloriin encountering and colonizing preferred niches. A cytoplasmic chemoreceptor named TlpD is particularly important in this process, and we report here that this chemoreceptor is able to operate independently of other chemoreceptors to organize a chemotaxis signaling complex and mediate a repellent response to oxidative stress conditions.H. pyloriencounters and must cope with oxidative stress during infection due to oxygen and reactive oxygen species produced by host cells. TlpD's repellent response may allow the bacteria to escape niches experiencing inflammation and elevated reactive oxygen species (ROS) production.

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Leptospira interrogans Catalase Is Required for Resistance to H2O2and for Virulence

Infection and Immunity ◽

10.1128/iai.00466-12 ◽

2012 ◽

Vol 80 (11) ◽

pp. 3892-3899 ◽

Cited By ~ 64

Author(s):

Azad Eshghi ◽

Kristel Lourdault ◽

Gerald L. Murray ◽

Thanatchaporn Bartpho ◽

Rasana W. Sermswan ◽

...

Keyword(s):

Oxidative Stress ◽

Reactive Oxygen Species ◽

Immune Response ◽

Innate Immune Response ◽

Reactive Oxygen ◽

Innate Immune ◽

Leptospira Interrogans ◽

Oxygen Species ◽

Content Type ◽

Host Innate Immune Response

ABSTRACTPathogenicLeptospiraspp. are likely to encounter higher concentrations of reactive oxygen species induced by the host innate immune response. In this study, we characterizedLeptospira interroganscatalase (KatE), the only annotated catalase found within pathogenicLeptospiraspecies, by assessing its role in resistance to H2O2-induced oxidative stress and during infection in hamsters. PathogenicL. interrogansbacteria had a 50-fold-higher survival rate under H2O2-induced oxidative stress than did saprophyticL. biflexabacteria, and this was predominantly catalase dependent. We also characterized KatE, the only annotated catalase found within pathogenicLeptospiraspecies. Catalase assays performed with recombinant KatE confirmed specific catalase activity, while protein fractionation experiments localized KatE to the bacterial periplasmic space. The insertional inactivation ofkatEin pathogenicLeptospirabacteria drastically diminished leptospiral viability in the presence of extracellular H2O2and reduced virulence in an acute-infection model. Combined, these results suggest thatL. interrogansKatE confersin vivoresistance to reactive oxygen species induced by the host innate immune response.

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Porphyromonas gingivalis-Induced Reactive Oxygen Species Activate JAK2 and Regulate Production of Inflammatory Cytokines through c-Jun

Infection and Immunity ◽

10.1128/iai.02000-14 ◽

2014 ◽

Vol 82 (10) ◽

pp. 4118-4126 ◽

Cited By ~ 18

Author(s):

Huizhi Wang ◽

Huaxin Zhou ◽

Xiaoxian Duan ◽

Ravi Jotwani ◽

Himabindu Vuddaraju ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Porphyromonas Gingivalis ◽

Proinflammatory Cytokines ◽

Molecular Mechanisms ◽

Reactive Oxygen ◽

Oxygen Species ◽

Content Type ◽

Amino Terminal ◽

Signaling Axis ◽

Interfering Rna

ABSTRACTPathogen-induced reactive oxygen species (ROS) play a crucial role in host innate immune responses through regulating the quality and quantity of inflammatory mediators. However, the underlying molecular mechanisms of this effect have yet to be clarified. In this study, we examined the mechanism of action of ROS stimulated byPorphyromonas gingivalisin gingival epithelial cells.P. gingivalisinduced the rapid production of ROS, which lead to the phosphorylation of JAK2 and increased levels of secreted proinflammatory cytokines interleukin-6 (IL-6) and IL-1β. Neutralization of ROS byN-acetyl-l-cysteine (NAC) abrogated the phosphorylation of JAK2 and suppressed the production of IL-6 and IL-1β. ROS-mediated phosphorylation of JAK2 induced the phosphoactivation of c-Jun amino-terminal protein kinase (JNK) and the downstream transcriptional regulator c-Jun. Inhibition of JAK2, either pharmacologically or by small interfering RNA (siRNA), reduced both the phosphorylation of these molecules and the production of proinflammatory cytokines in response toP. gingivalis. Furthermore, pharmacological inhibition or siRNA-mediated gene silencing of JNK or c-Jun mimicked the effect of JAK2 inhibition to suppressP. gingivalis-induced IL-6 and IL-1β levels. The results show that ROS-mediated activation of JAK2 is required forP. gingivalis-induced inflammatory cytokine production and that the JNK/c-Jun signaling axis is involved in the ROS-dependent regulation of IL-1β and IL-6 production.

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