Oxidative Stress of Asbestos or its Substitute to the Lung

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1. Alveolar macrophages of rats, RAW264.7 or J774 cells which is macrophage cell line established from mouse, induced nitric oxide(NO) Synthase(NOS), and increased the prduction of NO in the culture with asbestos or man-made mineral fiber(MMMF), such as glass fiber, ceramic fiber, rock wool or slug wool by way of substitute for asbestos.2. Increase in NO Synthesis was confirmed in the culture of AM from rats instilled asbestos into trachea.3. Generation of superoxide anion, O_2^- as well as NO was significantly enhanced in the culture of AM, RAW264.7 or J774 with asbestos or MMMF.4. When cultured with asbestos or MMMF, RAW264.7, AM or J774 decreased significantly intracellular glutathione levels in both reduced-and ozxdized-form.5. Taken altogether, these findings imply that oxidative stress in AM, RAW264.7 or J774 was strongly euhanced on exposure to asbestos or MMMF.6. It is well known that NO or peroxynitrite ONOO which is product of NO and O_2^- causes a nitration reaction with free thiol group in protein or wih reduced-form glutathione(GSH). These reaction products are RS-NO or GS-NO. We succeeded in developing a simple and new method for measuremert of RS-NO or GS-NO by using fluorescent dye. Using this method, we found an increased amount of GS-NO or RS-NO in conditioned media of AM, RAW264.7 or J774 cells cultured with asbestos or MMMF. This increase reflects at least in part a decrease in glutathione level in the cultured cells, suggesting the enhancement of oxidative stress or change of protein functions.7. Moreover, when cultured with asbestos or MMMF, AM, RAW264.7 or J774 responded to increase the production of proin- flammatory cytokines such as TNF-α, IL-1β, IL-6. The increases were found in BALF (Bronchoalveolar lavage fluid) from rats inntilled asbestos into trachea. These findings suggeet that collagen synthesis increases and will progress to the development of pneumoconiosis, that is, lung fibrosis soon or later.