Comparing study of the effect of nanosized silicon dioxide and microsized silicon dioxide on fibrogenesis in rats

Abstract

This study compares the effect of nanosized silicon dioxide (nanosized SiO₂) and microsized silicon dioxide (microsized SiO₂) particles on fibrogenesis in rats. Wistar rats were instilled intratracheally with saline, 20 mg of nanosized SiO₂ or 20 mg of microsized SiO₂, and were sacrificed at 1 and 2 months after instillation. The lungs of rats were analysed for the changes of lung/body coefficient and hydroxyproline content. Changes in pathology and fibrotic grade were observed by use of hematoxylin and eosin and Van Gieson dyeing. The expression of interleukin-4 (IL-4) and transforming growth factor-b1 (TGF-b1) was observed by use of immunohistochemical technique, and protein expression quantitatively analysed by image analysis. The lung/body coefficient and hydroxyproline content of nanosized SiO₂ groups were significantly lower than those of microsized SiO₂ groups at both 1 and 2 months after instillation (PB ^/ 0.05 or PB ^/ 0.01), but without significant differences from those of saline control groups. At 1 month after instillation, there were mainly cellular nodules (Stage I) in nanosized SiO₂ group, while in microsized SiO₂ group Stage II, II of silicotic nodules were observed. At 2 months after instillation, there were still Stage I of silicotic nodules in nanosized SiO₂ group. In microsized SiO₂ group mainly Stage II, III of silicotic nodules were found. Quantity image analysis showed that the expressions of IL-4 and TGF-b1 in nanosized SiO₂ groups were significantly lower than those in microsized SiO₂ groups (PB ^/ 0.01), but without significant difference from those of saline control groups. Our experiment revealed that the effect of fibrogenesis of nanosized SiO₂ might be milder than that of microsized SiO₂ in rats, potentially resulting from nanoparticals tending to be diffused and easily translocated due to their ultrafine particle size compared to microsized particles.

Keywords

lung fibrosis microsized silicon dioxide nanosized silicon dioxide rats

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