Free radical biology & medicine
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Free Radic. Biol. Med. · Dec 2014
Enhanced hydrogen peroxide generation accompanies the beneficial bioenergetic effects of methylene blue in isolated brain mitochondria.
The redox dye methylene blue (MB) is proven to have beneficial effects in various models of neurodegenerative diseases. Here we investigated the effects of MB (100 nM, 300 nM, and 1 μM) on key bioenergetic parameters and on H2O2 production/elimination in isolated guinea pig brain mitochondria under normal as well as respiration-impaired conditions. As measured by high-resolution Oxygraph the rate of resting oxygen consumption was increased, but the ADP-stimulated respiration was unaffected by MB with any of the substrates (glutamate malate, succinate, or α-glycerophosphate) used for supporting mitochondrial respiration. ⋯ Furthermore, it also decreased the elimination of H2O2. Generation of H2O2 without superoxide formation, observed in the presence of MB, is interpreted as a result of reduction of molecular oxygen to H2O2 by the reduced MB. The elevated generation and impaired elimination of H2O2 should be considered for the overall oxidative state of mitochondria treated with MB.
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Free Radic. Biol. Med. · Dec 2014
Cardiac mitochondrial biogenesis in endotoxemia is not accompanied by mitochondrial function recovery.
Mitochondrial biogenesis emerges as a compensatory mechanism involved in the recovery process in endotoxemia and sepsis. The aim of this work was to analyze the time course of the cardiac mitochondrial biogenesis process occurring during endotoxemia, with emphasis on the quantitative analysis of mitochondrial function. Female Sprague-Dawley rats (45 days old) were ip injected with LPS (10 mg/kg). ⋯ Complex II and complex IV showed decreased activity only at 24 h. The present results show that partial restoration of cardiac mitochondrial architecture is not accompanied by improvement of mitochondrial function in acute endotoxemia. The key implication of our study is that cardiac failure due to bioenergetic dysfunction will be overcome by therapeutic interventions aimed to restore cardiac mitochondrial function.
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Free Radic. Biol. Med. · Aug 2014
Inducible nitric oxide synthase is key to peroxynitrite-mediated, LPS-induced protein radical formation in murine microglial BV2 cells.
Microglia are the resident immune cells in the brain. Microglial activation is characteristic of several inflammatory and neurodegenerative diseases including Alzheimer's disease, multiple sclerosis, and Parkinson's disease. Though lipopolysaccharide (LPS)-induced microglial activation in models of Parkinson's disease is well documented, the free radical-mediated protein radical formation and its underlying mechanism during LPS-induced microglial activation are not known. ⋯ Inhibition of iNOS precisely correlated with decreased protein radical formation in LPS-treated BV2 cells. The time course of protein radical formation also matched the time course of iNOS expression. Taken together, these results prove the role of iNOS in peroxynitrite-mediated protein radical formation in LPS-treated microglial BV2 cells.
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Free Radic. Biol. Med. · Aug 2014
The glutaredoxin/S-glutathionylation axis regulates interleukin-17A-induced proinflammatory responses in lung epithelial cells in association with S-glutathionylation of nuclear factor κB family proteins.
Interleukin-17A (IL-17A) is a newly emerging player in the pathogenesis of chronic lung diseases that amplifies inflammatory responses and promotes tissue remodeling. Stimulation of lung epithelial cells with IL-17A leads to activation of the transcription factor nuclear factor κB (NF-κB), a key player in the orchestration of lung inflammation. We have previously demonstrated the importance of the redox-dependent posttranslational modification S-glutathionylation in limiting activation of NF-κB and downstream gene induction. ⋯ SiRNA-mediated ablation or genetic ablation of Glrx1 decreased the expression of the NF-κB-regulated genes KC and CCL20 in response to IL-17A, but conversely increased the expression of IL-6. Last, siRNA-mediated ablation of IKKα attenuated nuclear RelA and RelB content and decreased expression of KC and CCL20 in response to IL-17A. Together, these data demonstrate a critical role for the S-glutathionylation/Grx1 redox axis in regulating IKKα and RelA S-glutathionylation and the responsiveness of epithelial cells to IL-17A.
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Free Radic. Biol. Med. · Jul 2014
TRPA1 receptor stimulation by hydrogen peroxide is critical to trigger hyperalgesia and inflammation in a model of acute gout.
Acute gout attacks produce severe joint pain and inflammation associated with monosodium urate (MSU) crystals leading to oxidative stress production. The transient potential receptor ankyrin 1 (TRPA1) is expressed by a subpopulation of peptidergic nociceptors and, via its activation by endogenous reactive oxygen species, including hydrogen peroxide (H2O2), contributes to pain and neurogenic inflammation. The aim of this study was to investigate the role of TRPA1 in hyperalgesia and inflammation in a model of acute gout attack in rodents. ⋯ In addition, we showed that MSU evoked generation of H2O2 in synovial tissue, which stimulated TRPA1 producing CGRP release and plasma protein extravasation. The MSU-elicited responses were also reduced by the H2O2-detoxifying enzyme catalase and the reducing agent dithiothreitol. TRPA1 activation by MSU challenge-generated H2O2 mediates the entire inflammatory response in an acute gout attack rodent model, thus strengthening the role of the TRPA1 receptor and H2O2 production as potential targets for treatment of acute gout attacks.