3-nitrotyrosine and Asbestosis

Asbestos induces generation of reactive oxygen and nitrogen species in laboratory studies. Several such species can be measured non-invasively in humans in exhaled breath condensate (EBC) but few have been evaluated. This study aimed to assess oxidative stress and lung inflammation in vivo.. Eighty six men were studied: sixty subjects with asbestos-related disorders (asbestosis: 18, diffuse pleural thickening (DPT): 16, pleural plaques (PPs): 26) and twenty six age- and gender-matched normal individuals.. Subjects with asbestosis had raised EBC markers of oxidative stress compared with normal controls [8-isoprostane (geometric mean (95% CI) 0.51 (0.17-1.51) vs 0.07 (0.04-0.13) ng/ml, p<0.01); hydrogen peroxide (13.68 (8.63-21.68) vs 5.89 (3.99-8.69) microM, p<0.05), as well as increased EBC total protein (17.27 (10.57-28.23) vs 7.62 (5.13-11.34) microg/ml, p<0.05), and fractional exhaled nitric oxide (mean+/-SD) (9.67+/-3.26 vs 7.57+/-1.89ppb; p<0.05). EBC pH was lower in subjects with asbestosis compared with subjects with DPT (7.26+/-0.31 vs 7.53+/-0.24; p<0.05). There were no significant differences in exhaled carbon monoxide, EBC total nitrogen oxides and 3-nitrotyrosine between any of the asbestos-related disorders, or between these and controls.. In asbestos-related disorders, markers of inflammation and oxidative stress are significantly elevated in subjects with asbestosis compared with healthy individuals but not in pleural diseases.

Topics: Aged; Asbestos; Asbestosis; Biomarkers; Dinoprost; Forced Expiratory Volume; Humans; Lung Diseases; Male; Nitric Oxide; Oxidative Stress; Prognosis; Tyrosine

Reactive oxygen and nitrogen species have been implicated in the pathogenesis of asbestos fibers-associated pulmonary diseases. By comparing the responses of inducible nitric oxide synthase (iNOS) knockout and wild-type mice we investigated the consequences of iNOS expression for the development of the inflammatory response and tissue injury upon intratracheal instillation of asbestos fibers. Exposure to asbestos fibers resulted in an increased iNOS mRNA and protein expression in the lungs from wild-type mice. Moreover, iNOS knockout mice exhibited an exceeded pulmonary expression and production of TNF-alpha as well as a higher influx of neutrophils into the alveolar space than wild-type mice. In contrast, iNOS knockout animals displayed an attenuated oxidant-related tissue injury reflected in a decrease in protein leakage and LDH release into the alveolar space as well as weaker nitrotyrosine staining of lung tissue compared to wild-type mice. Data presented here indicate that iNOS-derived NO exerts a dichotomous role in acute asbestos-induced lung injury in that iNOS deficiency resulted in an exacerbated inflammatory response but improved oxidant-promoted lung tissue damage.

Topics: Acute Disease; Animals; Asbestos; Asbestosis; Bronchoalveolar Lavage Fluid; Chemotaxis; Enzyme Induction; Gene Expression Regulation; Inflammation; L-Lactate Dehydrogenase; Lung; Mice; Mice, Inbred C57BL; Mice, Knockout; Neutrophils; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxidation-Reduction; Peroxidase; RNA, Messenger; Tumor Necrosis Factor-alpha; Tyrosine

Recent studies have suggested that inducible nitric oxide synthase (iNOS) plays a role in the development of asbestos-related pulmonary disorders. The pulmonary reactions of rats and hamsters upon exposure to asbestos fibers are well known to be disparate. In addition, in vitro experiments have indicated that mononuclear phagocytes from hamsters, in contrast to those from rats, lack the iNOS pathway. Therefore, the purpose of this study was to investigate whether rats and hamsters differ in lung iNOS expression in vivo upon exposure to asbestos fibers and whether differences in iNOS induction are associated with differences in the acute pulmonary inflammatory reaction. Body weight, alveolar-arterial oxygen difference, differential cell count in bronchoalveolar lavage fluid, total protein leakage, lung myeloperoxidase activity and lipidperoxidation, wet/dry ratio, iNOS mRNA and protein expression, and nitrotyrosine staining of lung tissue were determined 1 and 7 days after intratracheal instillation of asbestos fibers in CD rats and Syrian golden hamsters. Exposure of rats to asbestos fibers resulted in enhanced pulmonary iNOS expression and nitrotyrosine staining together with an acute inflammation that was characterized by an influx of neutrophils, enhanced myeloperoxidase activity and lipid peroxidation, damage of the alveolar-capillary membrane, edema formation, and impairment of gas exchange. In comparison, instillation of asbestos fibers in hamsters resulted in a significantly milder inflammatory reaction of the lung with no induction of iNOS in pulmonary cells. The data obtained provide important information to understand the underlying mechanisms of species differences in the pulmonary response upon exposure to asbestos fibers.

Topics: Animals; Asbestos, Crocidolite; Asbestosis; Body Weight; Bronchoalveolar Lavage Fluid; Cell Count; Cricetinae; Disease Models, Animal; Inhalation Exposure; Intubation, Intratracheal; Lung; Mesocricetus; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxygen; Peroxidase; Rats; RNA, Messenger; Species Specificity; Thiobarbituric Acid Reactive Substances; Tyrosine