In vivo evidence of free radical generation in the mouse lung after exposure to Pseudomonas aeruginosa bacterium: an ESR spin-trapping investigation.
ABSTRACT In the Pseudomonas aeruginosa-induced rodent pneumonia model, it is thought that free radicals are significantly associated with the disease pathogenesis. However, until now there has been no direct evidence of free radical generation in vivo. Here we used electron spin resonance (ESR) and in vivo spin trapping with α-(4-pyridyl-1-oxide)-N-tert-butylnitrone to investigate free radical production in a murine model. We detected and identified generation of lipid-derived free radicals in vivo (a(N) =14.86 ± 0.03 G and a(H)(β) =2.48 ± 0.09 G). To further investigate the mechanism of lipid radical production, we used modulating agents and knockout mice. We found that with GdCl(3) (phagocytic toxicant), NADPH-oxidase knockout mice (Nox2(-)/(-)), allopurinol (xanthine-oxidase inhibitor) and Desferal (metal chelator), generation of lipid radicals was decreased; histopathological and biological markers of acute lung injury were noticeably improved. Our study demonstrates that lipid-derived free radical formation is mediated by NADPH-oxidase and xanthine-oxidase activation and that metal-catalysed hydroxyl radical-like species play important roles in lung injury caused by Pseudomonas aeruginosa.
SourceAvailable from: Ange Mouithys-Mickalad[Show abstract] [Hide abstract]
ABSTRACT: Nanomaterials are being utilized in an increasing variety of manufactured goods. Because of their unique physico-chemical, electrical, mechanical and thermal properties, single walled carbon nanotubes (SWCNTs) have found numerous applications in the electronics, aerospace, chemical, polymer and pharmaceutical industries. Previously, we have reported that pharyngeal exposure of C57BL/6 mice to SWCNTs caused dose-dependent formation of granulomatous bronchial interstitial pneumonia, fibrosis, oxidative stress, acute inflammatory/cytokine responses and a decrease in pulmonary function. In the current study, we used electron spin resonance (ESR) to directly assess whether exposure to respirable SWCNTs caused formation of free radicals in the lungs and in two distant organs, the heart and liver. Here we report that exposure to partially purified SWCNTs (HiPco, CNI, Inc, TX) resulted in the augmentation of oxidative stress as evidenced by ESR detection of a-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) spin-trapped carbon-centered lipid-derived radicals recorded shortly after the treatment. This was accompanied by a significant depletion of antioxidants and elevated biomarkers of inflammation presented by recruitment of inflammatory cells and an increase in pro-inflammatory cytokines in the lungs, as well as development of multifocal granulomatous pneumonia, interstitial fibrosis and suppressed pulmonary function. Moreover, pulmonary exposure to SWCNTs also caused the formation of carbon-centered lipid-derived radicals in the heart and liver at later time points (day 7 post exposure). Additionally, SWCNTs induced a significant accumulation of oxidatively modified proteins, an increase in lipid peroxidation products, depletion of antioxidants and an inflammatory response in both the heart and the liver. Furthermore, the iron chelator deferoxamine (DFO) noticeably reduced lung inflammation and oxidative stress indicating an important role of metal-catalyzed species in lung injury caused by SWCNTs. Overall, we provided direct evidence that lipid-derived free radicals are a critical contributor to tissue damge induced by SWCNTs not only in the lungs, but in distant organs.Free Radical Biology and Medicine 05/2014; 73. DOI:10.1016/j.freeradbiomed.2014.05.010 · 5.71 Impact Factor
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ABSTRACT: The relationship between hydroxyl radical (·OH) and oxidatively modified macromolecule formations was examined in tissues from young and aged mice. To determine the ·OH generation in tissues in vivo using the hydroxylation trapping reaction of ·OH into salicylic acid (SA), analytical conditions for dihydroxybenzoic acid (DHBA) and SA determination, and optimum dosages of SA for administration and time-points of tissue sampling were determined. 2, 3-DHBA levels in tissues from young mice and age-related changes were determined with the oxidatively modified macromolecules. 2, 3-DHBA, a hydroxylation compound of SA, is considered to be suitable for determination of ·OH levels in tissues. Tissue levels of 2, 3-DHBA expressed as a molar ratio to SA, was comparable among tissues, and was in accordance with 8-oxo-2'-deoxyguanosine (8-oxodG) and carbonylated proteins. In the aging process, 2, 3-DHBA levels in the brain and heart increased in the biphasic pattern in accordance with the 8-oxodG and thiobarbituric acid reactive substances (TBARS) levels, whereas levels of carbonylated proteins were not changed with age. An in vivo method for ·OH measurement using hydroxylation of SA was optimized. However, as a limitation, 2, 3-DHBA, as well as other oxidative stress markers, could be affected by various in vivo factors. The accordance was seen among 2, 3-DHBA, 8-oxodG and carbonylated protein levels in tissues from young mice. The tissue levels of 2, 3-DHBA increased in accordance with the 8-oxodG and TBARS during the aging process. Geriatr Gerontol Int 2013; ●●: ●●-●●.Geriatrics & Gerontology International 07/2013; DOI:10.1111/ggi.12107 · 1.58 Impact Factor