State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China; Department of Environmental Science, School of Engineering, China Pharmaceutical University, Nanjing, 211198, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China.
Chemosphere. 2020 Oct;256:127204. doi: 10.1016/j.chemosphere.2020.127204. Epub 2020 May 24.
The digestive tract is an important target organ for microplastics (MPs). However, little is known about the effects of digestive treatment on the intestinal toxicity of MPs. In this study, an in vitro digestive process was applied to transform 100 nm and 5 μm polystyrene microplastics (PS-MPs). Intestinal toxicities of original PS-MPs and transformed PS-MPs (t-PS-MPs) were determined using an in vitro Caco-2 monolayer model. Results showed that the digestive process did not alter the chemical constitution of PS-MPs, but formed a corona on the surface of PS-MPs. The 100 nm PS-MPs showed higher intestinal toxicity than 5 μm PS-MPs. Digestive treatment relieved cytotoxicity and transport function disorder of the Caco-2 monolayer induced by the original PS-MPs. Moreover, the combined toxicities of PS-MPs and arsenic were also decreased by digestive treatment. However, the in vitro digestive process increased the proinflammatory effects of PS-MPs. The formation of a corona on the PS-MP surface, which lead to a change in size, Zeta potential, and adsorbed compounds, might induce the above influence of digestive treatment. Our study suggests that direct cytotoxicity assays of PS-MPs might misestimate their intestinal effects, which provide new lights to the toxicity evaluation of PS-MPs by oral exposure.
消化道是微塑料（MPs）的重要靶器官。然而，对于消化处理对 MPs 肠道毒性的影响知之甚少。在本研究中，采用体外消化过程来转化 100nm 和 5μm 聚苯乙烯微塑料（PS-MPs）。使用体外 Caco-2 单层模型测定原始 PS-MPs 和转化 PS-MPs（t-PS-MPs）的肠道毒性。结果表明，消化过程并未改变 PS-MPs 的化学组成，但在 PS-MPs 表面形成了一个冠。100nm PS-MPs 比 5μm PS-MPs 表现出更高的肠道毒性。消化处理减轻了原始 PS-MPs 诱导的 Caco-2 单层细胞毒性和转运功能障碍。此外，消化处理还降低了 PS-MPs 和砷的联合毒性。然而，体外消化过程增加了 PS-MPs 的促炎作用。PS-MP 表面形成的冠导致尺寸、Zeta 电位和吸附化合物的变化，可能会引起上述消化处理的影响。我们的研究表明，PS-MPs 的直接细胞毒性测定可能会错误估计其肠道效应，这为口服暴露时 PS-MPs 的毒性评估提供了新的思路。
