metallothionein and Lung-Diseases

Superoxide formation in pulmonary tissue is modulated by cytokines, PO2, shear force, and disease states, and can be stimulated by drugs. Superoxide has diverse actions on pulmonary cells, including smooth muscle contraction, interaction with redox enzymes, cell proliferation, and gene transcription. In the lungs, there is an impressive array of specific defence mechanisms that destroy superoxide, especially superoxide dismutase (SOD) and metallothionein. Superoxide formation is increased in hyperoxia (e.g., oxygen therapy); however, superoxide-forming enzymes also can be up-regulated in hypoxia. Superoxide has been implicated in acute respiratory distress syndrome, lung ischaemia-reperfusion injury, and lung transplantation. Novel approaches to therapy have been explored, including SOD gene therapy and SOD targeting to the lung. In the future, new drugs interacting with superoxide may provide significant advances in the treatment of lung diseases.

Topics: Animals; Cell Division; Cell Membrane Permeability; Genetic Therapy; Humans; Hyperoxia; Hypoxia; Lung Diseases; Metallothionein; Pulmonary Artery; Reperfusion Injury; Superoxide Dismutase; Superoxides; Transcription, Genetic

To study the acute and subacute pulmonary toxicity of colloidal silver nanoparticles (Ag-NPs), 0 or 100 ppm of Ag-NPs were instilled intratracheally in mice. Cellular and biochemical parameters in bronchoalveolar lavage fluid (BALF) and histological alterations were determined 1, 3, 7, 15, and 30 days after instillation. Ag-NPs induced moderate pulmonary inflammation and injury on BALF indices during the acute period; however, these changes gradually regressed in a time-dependent manner. Concomitant histopathological and laminin immunohistochemical findings generally correlated to BALF data. Superoxide dismutase and metallothionein expression occurred in particle-laden macrophages and alveolar epithelial cells, which correlated to lung lesions in mice treated with Ag-NPs. These findings suggest that instillation of Ag-NPs causes transient moderate acute lung inflammation and tissue damage. Oxidative stress may underlie the induction of injury to lung tissue. Moreover, the expression of metallothionein in tissues indicated the protective response to exposure to Ag-NPs.

Topics: Acute Disease; Administration, Inhalation; Animals; Colloids; Disease Models, Animal; Epithelial Cells; Lung; Lung Diseases; Macrophages; Male; Metal Nanoparticles; Metallothionein; Mice; Mice, Inbred ICR; Silver; Time Factors

Epidemiological studies associate environmental cadmium (Cd) exposure with the risk of lung diseases. Although mechanisms are not fully elucidated, several studies demonstrate Cd effects on actin and actin-associated proteins. In a recent study of Cd at concentrations similar to environmental exposures, we found that redox-dependent inflammatory signaling by NF-κB was sensitive to the actin-disrupting agent, cytochalasin D. The goal of the present study was to use mass spectrometry-based redox proteomics to investigate Cd effects on the actin cytoskeleton proteome and related functional pathways in lung cells at low environmental concentrations. The results showed that Cd under conditions that did not alter total protein thiols or glutathione redox state caused significant oxidation of peptidyl Cys of proteins regulating actin cytoskeleton. Immunofluorescence microscopy of lung fibroblasts and pulmonary artery endothelial cells showed that low-dose Cd exposure stimulated filamentous actin formation and nuclear localization of destrin, an actin-depolymerizing factor. Taken together, the results show that redox states of peptidyl Cys in proteins associated with actin cytoskeleton pathways are selectively oxidized in lung by Cd at levels thought to occur from environmental exposure.

Topics: Actin Cytoskeleton; Animals; Cadmium; Cells, Cultured; Cysteine; Destrin; Environmental Pollutants; Fibroblasts; Gene Expression; Glutathione; Lung Diseases; Metabolic Networks and Pathways; Metallothionein; Mice; Mice, Inbred C57BL; Oxidation-Reduction; Oxidative Stress; Protein Transport; Proteome

As a result of repeated exposures to inhaled toxicants such as zinc oxide (ZnO), numerous individuals acquire tolerance to the exposures and display reduced symptoms. To ascertain whether tolerance is developed in an animal model, NIH-Swiss mice were exposed to 1.0 mg/m(3) ZnO for 1, 3, or 5 days (1X, 3X, or 5X), and polymorphonuclear leukocyte (PMN) and protein levels in bronchoalveolar lavage (BAL) were measured. Mice acquired tolerance to neutrophil infiltration into the lungs, as total PMNs returned near baseline in 5X-exposed animals as compared to that of the 1X exposure group (1X = 2.7 +/- 0.4 x 10(4), 5X = 0.2 +/- 0.1 x 10(4), mean +/- SE, p < 0.05). Development of tolerance to changes in lavageable protein, however, was not observed (1X = 313 +/- 29 microg/ml, 5X = 684 +/- 71 microg/ml, p < 0.05). Tolerance to PMN influx did not persist following re-exposure to ZnO after 5 days of rest. In contrast to ZnO exposure, following single and repeated exposure to aerosolized endotoxin there was development of tolerance to protein in BAL (1X = 174 +/- 71 microg/ml, 5X = 166 +/- 14 microg/ml, p > 0.05), but not to PMN influx (1X = 5.5 +/- 1.7 x 10(4), 13.9 +/- 1.7 x 10(4), p < 0.05). Induction of lung metallothionein (MT) was also observed in mice exposed once or repeatedly exposed to ZnO, suggesting that MT may play a role in its molecular mechanism.

Topics: Adaptation, Physiological; Administration, Inhalation; Animals; Bronchoalveolar Lavage Fluid; Cell Count; Drug Tolerance; Escherichia coli; Lipopolysaccharides; Lung; Lung Diseases; Male; Metallothionein; Mice; Neutrophils; RNA, Messenger; Volatilization; Zinc Oxide

Oxidant-induced lung injury is believed to be mediated by reactive oxygen species. Recovery from oxidant exposure has been associated with pulmonary inflammation. Inflammatory cell accumulation involves the synthesis of chemokines, including neutrophil chemoattractants such as macrophage inflammatory protein-2 (MIP-2) and monocyte chemoattractants such as monocyte chemoattractant protein-1 (MCP-1). Antioxidants are the first line of defense of lung cells against inhaled oxidants. Metallothionein (MT) can act as an antioxidant and free-radical scavenger. To better understand the pulmonary response associated with recovery from oxidant-mediated injury, we exposed mice to either 15 ppm nitrogen dioxide for 24 h, >99% oxygen for 72 h, or 1 ppm ozone for 24 h. Mice were examined at the end of exposure or after recovering in room air for 4 or 24 h. Neutrophils were elevated at the end of exposure and remained elevated through the postexposure period, whereas macrophage numbers were decreased at the end of exposure and remained below control levels at 4 and 24 h postexposure. MT, MIP-2, and MCP-1 mRNA levels were elevated at 4 h postexposure; however, after 24 h of recovery only MCP-1 remained elevated. These results indicate that MT, MIP-2, and MCP-1 mRNA levels responded similarly to recovery from nitrogen dioxide, oxygen, and ozone exposure. Monocyte accumulation was delayed as compared to neutrophils and was consistent with the timing of MIP-2 and MCP-1 expression. Peak expression of MT and MIP-2 preceded peak neutrophil accumulation. Consequently, the timing of MT, MIP-2, and MCP-1 expression may be important biological markers in assessing the state of injury and recovery associated with oxidant-mediated injury.

Topics: Administration, Inhalation; Animals; Bronchoalveolar Lavage; Bronchoalveolar Lavage Fluid; Chemokine CCL2; Chemokine CXCL2; Chemotactic Factors; In Situ Hybridization; Lung Diseases; Male; Metallothionein; Mice; Mice, Inbred C57BL; Monokines; Nitrogen Dioxide; Nuclease Protection Assays; Oxidants, Photochemical; Oxygen; Ozone; RNA, Messenger

This study examined the protective role of metallothionein (MT) against pulmonary damage caused by acute exposure to metallic mercury (Hg0) vapor using MT-null and wild-type mice. Both strains of mice were exposed to Hg0 at 6.6 to 7.5 mg/m3 for 4 hr each day for 3 consecutive days. This dosing protocol was lethal to over 60% of MT-null mice but did not kill any wild-type mice. More severe pulmonary damage was found by histopathological observation in MT-null mice than in wild-type mice. MT levels in the lung were elevated in wild-type mice after Hg0 vapor exposure, and gel filtration of the lung cytosol revealed that most of the mercury was associated with MT. In MT-null mice, MT levels were below the limit of detection (0.2 microg/g tissue) for the MT assay even after exposure. After exposure to Hg0 vapor for 3 consecutive days, the pulmonary mercury levels in wild-type mice were significantly higher than in MT-null mice. These findings suggest that MT plays a protective role against the acute pulmonary toxicity of Hg0 vapor.

Topics: Administration, Inhalation; Alanine Transaminase; Animals; Aspartate Aminotransferases; Blood Urea Nitrogen; Chromatography, Gel; Creatinine; Lung; Lung Diseases; Mercury; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Radioimmunoassay; Survival Rate; Volatilization

3-Methylindole (3MI) selectively causes damage to pulmonary tissues; the species-selective order is goats, rats, and rabbits, with rabbits sustaining the least damage. 3MI is bioactivated to toxic intermediates by cytochrome P450 enzymes. Covalent binding of the electrophilic 3-methyleneindolenine intermediate to proteins is a likely mechanism of 3MI-mediated lung damage. Polyclonal antibodies were developed to thioether adducts of 3-methyleneindolenine and were shown by competitive enzyme-linked immunosorbent assay (ELISA) to be highly selective for the detection of 3MI adducts. Rabbits, rats, and goats were treated with 350, 400, and 15 mg/kg 3MI, respectively. The lungs, liver, and kidneys of each animal were collected 24 hr later and tissue fractions were analyzed by ELISA. Lung tissue fractions from goat (pellet, cytosol, and microsomes) had greater immunoreactivity than those from rat. Immunoreactivity in rat tissues was greater than that in rabbit tissues. In all of the animals, lung had greater immunoreactivity than kidney, and kidney had greater reactivity than liver. These studies demonstrate that thioether adducts of 3MI with proteins can be detected specifically by these antisera, and the adducts are precisely correlated to species and tissue susceptibility of 3MI. In addition, human lung and liver samples were moderately immunoreactive. Therefore, humans form adducts of 3MI in these tissues and are predicted to be susceptible to 3MI-mediated toxicity.

Topics: Animals; Antibody Formation; Antibody Specificity; Cross Reactions; Enzyme-Linked Immunosorbent Assay; Goats; Humans; Immunoglobulin G; Indoles; Kidney; Liver; Lung; Lung Diseases; Male; Metallothionein; Organ Specificity; Rabbits; Rats; Rats, Sprague-Dawley; Skatole; Species Specificity

There is sufficient evidence for pulmonary carcinogenicity of inhaled Cd compounds in rats whereas no such evidence was found in mice and hamsters; the evidence in humans has been termed limited, indicating significant species differences in pulmonary response to inhaled Cd. We hypothesized that expression of metallothionein (MT) protein in the lung after inhalation of Cd differs between species thereby providing different degrees of sequestration of Cd and protection from its effects. Rats and mice were exposed to 100 micrograms CdCl2 aerosols/m3 for 4 weeks, and the presence of MT was determined in lung and free lung cell homogenates as well as by immunocytochemistry in lung sections up to 28 days postexposure. In addition, pulmonary inflammatory, and cell proliferative responses were determined. Cd exposure significantly increased MT in homogenates of total lung in both species; however, no significant increase of MT in rat lung tissue after removal of free lung cells by lavage was found whereas MT was still significantly increased in lavaged mouse lung tissue throughout the postexposure time. In contrast, exposed rats showed significant increases in MT in the lavageable lung cells and mice did not. Histochemical analysis of lung sections revealed that mainly the epithelial cells of the bronchi, bronchioli, and alveoli of Cd-exposed mice expressed MT. Mice also exhibited a marked and sustained pulmonary inflammatory and cell proliferative response upon CdCl2 exposure which was not observed in rats. The retained Cd dose per gram lung was about 2-fold greater in mice, which is consistent with a greater deposition efficiency of inhaled Cd-aerosols in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Administration, Inhalation; Animals; Cadmium; Carcinogens; Humans; Lung Diseases; Male; Metallothionein; Mice; Pneumonia; Rats; Rats, Inbred F344; Species Specificity

Low molecular weight cadmium-binding proteins were studed in lung tissue from rabbits exposed to aerosols of CdCl2. Lungs obtained from animals exposed by inhalation to aerosols of 800 or 1600 micrograms/m3 CdCl2 for 2-hr periods/day, every other day for a 5-day period, were found to contain at least three low molecular weight cadmium-binding proteins, two of which were similar electrophoretically and spectrally to rabbit liver metallothionein. The third protein(s), which accounted for the majority of the cadmium in the soluble fraction of the tissue, did not bind to an anionic exchange gel and did not appear to be a polymerized form of metallothionein. Translocation studies of lung cadmium suggest a long half-life for cadmium in lung tissue following inhalation exposure, due perhaps to the high affinity of cadmium for specific lung cadmium-binding proteins. A small but significant redistribution of lung cadmium did occur to both kidney and liver tissue with time.

Topics: Aerosols; Animals; Cadmium; Cadmium Chloride; Injections, Spinal; Kidney; Liver; Lung; Lung Diseases; Male; Metalloproteins; Metallothionein; Molecular Weight; Rabbits