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Nano- and micro-particulates firmly attach with the surface of various biological systems. In some chronic pulmonary
disease such as asbestosis and silicosis, causative particulates will induce chronic inflammatory disorder, followed by
poor prognosis diseases. However, nano- and micro-scale specific toxicity of silica particulates is not well examined
enough to recognize the risk of nano- and micro-particulates from the clinical aspect.
To clarify the effect of the size and structure of silica particulates on the cellular damage and the biological response,
we assessed the cytotoxicity of the various kinds of silica particles including amorphous and crystalline silica, in mouse
alveolar macrophage culture, focusing on the fibrotic and inflammatory response.
Our study showed that the cytotoxicity, which depends on the particle size and surface area, is correlated with their
inflammatory response. By contrast, production of TGF-β, which is one of the fibrotic agents in lung, by addition of
crystal silica was much higher than that of amorphous silica.
We conclude that fibrosis and inflammation are induced at different phases and that the size- and structure-differences
of silica particulates affect the both biological responses, caused by surface activity, radical species, and so on.
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