Related Experiment Videos
Role of reactive oxygen metabolites in crocidolite asbestos toxicity to mouse macrophages
Abstract:
Crocidolite asbestos is toxic to macrophages in vitro. We hypothesize that this toxicity is mediated by the generation of reactive oxygen metabolites. Elicited mouse peritoneal macrophages were found to release reactive oxygen metabolites upon incubation with crocidolite asbestos in vitro. Crocidolite toxicity to both primary cultures of mouse peritoneal macrophages and P388D1 cells, a mouse macrophage-like cell line, could be prevented by a hypoxic environment or by addition of the reactive oxygen metabolite scavengers, superoxide dismutase and catalase. In addition, if crocidolite fibers were presoaked with the iron chelator deferoxamine, no macrophage death occurred. In an attempt to mimic crocidolite-induced cytotoxicity, P388D1 cells or primary elicited macrophages were exposed to the nontoxic mineral particle titanium dioxide in the presence and absence of ferric chloride. Titanium dioxide was only lethal when ferric chloride was added. This toxicity was prevented by superoxide dismutase, catalase, or deferoxamine. These results suggest that crocidolite-induced injury to macrophages depends on the formation of reactive oxygen metabolites. Iron present in crocidolite fibers may catalyze the production of hydroxyl radical from superoxide anion and hydrogen peroxide generated during phagocytosis. These highly reactive hydroxyl radicals are postulated to mediate lethal cell injury.
Insights
Crocidolite asbestos causes macrophage toxicity through reactive oxygen metabolites. Preventing these metabolites, like superoxide dismutase and catalase, or removing iron protects macrophages from asbestos injury.
Area of Science:
- Toxicology
- Cell Biology
- Environmental Health
Background:
- Crocidolite asbestos is known to be toxic to macrophages in vitro.
- The mechanism of asbestos-induced macrophage toxicity is not fully understood.
- Reactive oxygen metabolites (ROMs) are implicated in cellular damage.
Purpose of the Study:
- To investigate the role of reactive oxygen metabolites in crocidolite asbestos-induced macrophage toxicity.
- To determine if iron catalyzes the production of ROMs leading to cell injury.
Main Methods:
- Incubation of elicited mouse peritoneal macrophages and P388D1 cells with crocidolite asbestos in vitro.
- Assessment of ROM production using assays.
- Evaluation of protective effects of hypoxic environment, ROM scavengers (superoxide dismutase, catalase), and iron chelator (deferoxamine).
- Experiment using titanium dioxide and ferric chloride to mimic asbestos toxicity.
Main Results:
- Macrophages released ROMs upon incubation with crocidolite asbestos.
- Crocidolite toxicity was prevented by hypoxia, superoxide dismutase, catalase, and deferoxamine.
- Titanium dioxide induced cell death only when combined with ferric chloride, and this toxicity was also prevented by ROM scavengers and deferoxamine.
Conclusions:
- Crocidolite-induced macrophage injury is mediated by the formation of reactive oxygen metabolites.
- Iron in crocidolite fibers likely catalyzes the production of hydroxyl radicals, which cause lethal cell injury.