Extrapulmonary distribution, organ effect of nanosilica and micro-silica in C57BL/6J mouse intratracheal instillation model

The emergence of novel industries, such as the semiconductor, has resulted in an increased utilization of silica, which has had a significant impact on public health. Nevertheless, the effect of intratracheal instillation of silica on extrapulmonary distribution and organ effect in C57BL/6J mouse model is not fully understood. In our study, we synthesized fluorescent silica composites and used an inductively coupled plasma-optical emission spectrometer (ICP-OES) for quantitative detection of silica content to detect the extrapulmonary distribution of silica in C57BL/6J mouse. The organ-specific effects of nanosilica and micro-silica were examined through histopathological examination and molecular experiments. Following intratracheal instillation, nanosilica was found to be transferred to organs such as the brain and heart, while micro-silica mainly remained in the lung. Our study demonstrated that, compared to micro-silica, nanosilica induced significantly higher pulmonary inflammatory responses and promoted apoptosis in mouse brain tissue. Additionally, more collagen accumulation and fibrous nodules were detected in the lung tissue of C57BL/6J mouse exposed to micro-silica compared to those exposed to nanosilica. No pathological changes were observed in the mouse heart, liver, or kidney tissues due to nanosilica and micro-silica. Furthermore, the findings of our study revealed no significant differences in the effects of fluorescently labeled and unlabeled silica on C57BL/6J mouse. The findings indicated that nanosilica exhibited a higher extrapulmonary distribution potential in C57BL/6J mice compared with micro-silica. Beyond its stronger ability to induce pulmonary inflammatory responses, nanosilica may also exert deleterious effects on brain tissue. This study presents experimental evidence demonstrating the extrapulmonary distribution and organ effects of nanosilica particles administered via intratracheal instillation into C57BL/6J mice.