scholarly journals Dihydrolipoamide Acyltransferase Is Critical for Mycobacterium tuberculosis Pathogenesis

2006 ◽  
Vol 74 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Shuangping Shi ◽  
Sabine Ehrt
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Sodium Nitrite ◽  
Pyruvate Dehydrogenase ◽  
Nitrosative Stress ◽  
Oxidative And Nitrosative Stress ◽  
Retarded Growth ◽  
Mouse Macrophages

ABSTRACT Mycobacterium tuberculosis has evolved to persist in host macrophages, where it faces a nutrient-poor environment and is exposed to oxidative and nitrosative stress. To defend itself against oxidative/nitrosative stress, M. tuberculosis expresses an NADH-dependent peroxidase and peroxynitrite reductase that is encoded by ahpC, ahpD, lpd, and dlaT. In addition to its central role in the peroxynitrite reductase complex, dlaT (Rv2215) also encodes the E2 component of pyruvate dehydrogenase. Here we demonstrate that inactivation of dlaT in the chromosome of H37Rv resulted in a mutant (H37RvΔdlaT) that displayed phenotypes associated with DlaT's role in metabolism and in defense against nitrosative stress. The H37RvΔdlaT strain showed retarded growth in vitro and was highly susceptible to killing by acidified sodium nitrite. Mouse macrophages readily killed intracellular H37RvΔdlaT organisms, and in mice dlaT was required for full virulence.

scholarly journals Silencing of Oxidative Stress Response in Mycobacterium tuberculosis: Expression Patterns of ahpC in Virulent and Avirulent Strains and Effect ofahpC Inactivation

2001 ◽  
Vol 69 (10) ◽  
pp. 5967-5973 ◽  
Author(s):  
B. Springer ◽  
S. Master ◽  
P. Sander ◽  
T. Zahrt ◽  
M. McFalone ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Nitrosative Stress ◽  
Expression Patterns ◽  
Acute Infection ◽  
Cumene Hydroperoxide ◽  
Green Fluorescence Protein ◽  
Normal Growth ◽  
Oxidative And Nitrosative Stress ◽  
Virulent Strains

ABSTRACT Intracellular pathogens such as Mycobacterium tuberculosis are able to survive in the face of antimicrobial products generated by the host cell in response to infection. The product of the alkyl hydroperoxide reductase gene (ahpC) of M. tuberculosis is thought to be involved in protecting the organism against both oxidative and nitrosative stress encountered within the infected macrophage. Here we report that, contrary to expectations, ahpC expression in virulent strains of M. tuberculosis and Mycobacterium bovis grown in vitro is repressed, often below the level of detection, whereas expression in the avirulent vaccine strainM. bovis BCG is constitutively high. The repression of the ahpC gene of the virulent strains is independent of the naturally occurring lesions of central regulatoroxyR. Using a green fluorescence protein vector (gfp)-ahpC reporter construct we present data showing that repression of ahpC of virulentM. tuberculosis also occurred during growth inside macrophages, whereas derepression in BCG was again seen under identical conditions. Inactivation of ahpC on the chromosome ofM. tuberculosis by homologous recombination had no effect on its growth during acute infection in mice and did not affect in vitro sensitivity to H2O2. However, consistent with AhpC function in detoxifying organic peroxides, sensitivity to cumene hydroperoxide exposure was increased in theahpC::Kmr mutant strain. The preservation of a functional ahpC gene in M. tuberculosis in spite of its repression under normal growth conditions suggests that, while AhpC does not play a significant role in establishing infection, it is likely to be important under certain, as yet undefined conditions. This is supported by the observation that repression of ahpC expression in vitro was lifted under conditions of static growth.

scholarly journals A Possible Novel Anti-Inflammatory Mechanism for the Pharmacological Prolyl Hydroxylase Inhibitor 3,4-Dihydroxybenzoate: Implications for Use as a Therapeutic for Parkinson’s Disease

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Shankar J. Chinta ◽  
Subramanian Rajagopalan ◽  
Abirami Ganesan ◽  
Julie K. Andersen
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Microglial Activation ◽  
Nitrosative Stress ◽  
Neurodegenerative Disorder ◽  
Oxidative And Nitrosative Stress ◽  
Prolyl Hydroxylases ◽  
Age Related

Parkinson’s disease (PD) is an age-related neurodegenerative disorder characterized in part by the preferential loss of nigrostriatal dopaminergic neurons. Although the precise etiology of PD is unknown, accumulating evidence suggests that PD involves microglial activation that exerts neurotoxic effects through production of proinflammatory cytokines and increased oxidative and nitrosative stress. Thus, controlling microglial activation has been suggested as a therapeutic target for combating PD. Previously we demonstrated that pharmacological inhibition of a class of enzymes known as prolyl hydroxylases via 3,4-dihydroxybenzoate administration protected against MPTP-induced neurotoxicity, however the exact mechanisms involved were not elucidated. Here we show that this may be due to DHB’s ability to inhibit microglial activation. DHB significantly attenuated LPS-mediated induction of nitric oxide synthase and pro-inflammatory cytokines in murine BV2 microglial cellsin vitroin conjunction with reduced ROS production and activation of NFκB and MAPK pathways possibly due to up-regulation of HO-1 levels. HO-1 inhibition partially abrogates LPS-mediated NFκB activity and subsequent NO induction.In vivo, DHB pre-treatment suppresses microglial activation elicited by MPTP treatment. Our results suggest that DHB’s neuroprotective properties could be due to its ability to dampen induction of microglial activation via induction of HO-1.

scholarly journals Glutaraldehyde-Polymerized Hemoglobin: In Search of Improved Performance as Oxygen Carrier in Hemorrhage Models

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Anca D. Farcas ◽  
Vlad Al Toma ◽  
Ioana Roman ◽  
Bogdan Sevastre ◽  
Florina Scurtu ◽  
...  
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Nitrosative Stress ◽  
Oxygen Carrier ◽  
Oxygen Carriers ◽  
Oxidative And Nitrosative Stress ◽  
Rat Serum ◽  
Improved Performance

Hemoglobin- (Hb-) based oxygen carriers (HBOC) have for several decades been explored for treatment of hemorrhage. In our previous top-up tests, HBOC with lower in vitro prooxidant reactivity (incorporating a peroxidase or serum albumin to this end) showed a measurable but small improvement of oxidative stress-related parameters. Here, such HBOCs are tested in a hemorrhage set-up; ovine hemoglobin is also tested for the first time in such a setting, based on in vitro data showing its improved performance versus bovine Hb against oxidative and nitrosative stress agents. Indeed, ovine Hb performs better than bovine Hb in terms of survival rates, arterial tension, immunology, and histology. On the other hand, unlike in the top-up models, where the nonheme peroxidase rubrerythrin as well as bovine serum albumin copolymerized with Hb were shown to improve the performance of HBOC, in the present hemorrhage models rubrerythrin fails dramatically as HBOC ingredient (with a distinct immunological reaction), whereas serum albumin appears not feasible if its source is a different species (i.e., bovine serum albumin fares distinctly worse than rat serum albumin, in HBOC transfusions in rats). An effect of the matrix in which the HBOCs are dissolved (PBS versus gelofusine versus plasma) is noted.

scholarly journals DNA Alkylation Damage as a Sensor of Nitrosative Stress in Mycobacterium tuberculosis

2003 ◽  
Vol 71 (2) ◽  
pp. 997-1000 ◽  
Author(s):  
Steven I. Durbach ◽  
Burkhard Springer ◽  
Edith E. Machowski ◽  
Robert J. North ◽  
K. G. Papavinasasundaram ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mycobacterium Tuberculosis ◽  
Nitrosative Stress ◽  
Dna Alkylation ◽  
Genotoxic Effects ◽  
Alkylation Damage ◽  
Damage Repair

ABSTRACT One of the cellular consequences of nitrosative stress is alkylation damage to DNA. To assess whether nitrosative stress is registered on the genome of Mycobacterium tuberculosis, mutants lacking an alkylation damage repair and reversal operon were constructed. Although hypersensitive to the genotoxic effects of N-methyl-N′-nitro-N-nitrosoguanidine in vitro, the mutants displayed no phenotype in vivo, suggesting that permeation of nitrosative stress to the level of cytotoxic DNA damage is restricted.

scholarly journals Type I interferon signaling mediates Mycobacterium tuberculosis–induced macrophage death

2020 ◽  
Vol 218 (2) ◽  
Author(s):  
Li Zhang ◽  
Xiuju Jiang ◽  
Daniel Pfau ◽  
Yan Ling ◽  
Carl F. Nathan
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Critical Role ◽  
Type I ◽  
Type I Ifn ◽  
Paracrine Signaling ◽  
Type I Ifns ◽  
Genome Wide ◽  
Mouse Macrophages ◽  
Definition Of

Macrophages help defend the host against Mycobacterium tuberculosis (Mtb), the major cause of tuberculosis (TB). Once phagocytized, Mtb resists killing by macrophages, replicates inside them, and leads to their death, releasing Mtb that can infect other cells. We found that the death of Mtb-infected mouse macrophages in vitro does not appear to proceed by a currently known pathway. Through genome-wide CRISPR-Cas9 screening, we identified a critical role for autocrine or paracrine signaling by macrophage-derived type I IFNs in the death of Mtb-infected macrophages in vitro, and blockade of type I IFN signaling augmented the effect of rifampin, a first-line TB drug, in Mtb-infected mice. Further definition of the pathway of type I IFN–mediated macrophage death may allow for host-directed therapy of TB that is more selective than systemic blockade of type I IFN signaling.

scholarly journals Melatonin Scavenger Properties against Oxidative and Nitrosative Stress: Impact on In Vitro Embryo Production in Mammals

2017 ◽  
Author(s):  
Pía Loren ◽  
Raúl Sánchez ◽  
María-Elena Arias ◽  
Ricardo Felmer ◽  
Jennie Risopatrón ◽  
...  
Keyword(s):  
Reactive Nitrogen Species ◽  
Culture Medium ◽  
Nitrosative Stress ◽  
Culture Conditions ◽  
Oxidative And Nitrosative Stress ◽  
Positive Effects ◽  
Mammalian Embryos ◽  
Vitro Development ◽  
Hormone System

Oxidative and nitrosative stress are a common problem when manipulating gametes in vitro. In vitro development in mammalian embryos is highly affected by culture conditions, especially by reactive oxygen species (ROS) and reactive nitrogen species (RNS), because its absence or over production causes embryo arrest and changes in gene expression. Melatonin in gamete co-incubation during IVF has deleterious or positive effects depending on the concentration used in culture medium, demonstrating the delicate balance that must exist between antioxidant and pro-oxidant activity. Further research is needed to better understand the possible impact of melatonin on the different IVP steps in domestic animals, especially in seasonal breeds where this neuro-hormone system highly regulates its reproduction physiology.

scholarly journals S-allylmercaptocysteine scavenges hydroxyl radical and singlet oxygen in vitro and attenuates gentamicin-induced oxidative and nitrosative stress and renal damage in vivo

2004 ◽  
Vol 4 (1) ◽  
Author(s):  
José Pedraza-Chaverrí ◽  
Diana Barrera ◽  
Perla D Maldonado ◽  
Yolanda I Chirino ◽  
Norma A Macías-Ruvalcaba ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Singlet Oxygen ◽  
Renal Damage ◽  
Nitrosative Stress ◽  
Oxidative And Nitrosative Stress
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