Abstract

Growing evidence demonstrated that bioaccumulation of polystyrene nanoplastics (PS-NPs) in various organisms including human beings caused destructive effects on health. Nanoplastics may adversely affect fetal development potentially since they can pass through the placental barrier. However, very little has been known about the embryonic toxicity of polystyrene nanoplastics, especially in embryonic neurulation, the early developmental stage of the fetus, as well as the corresponding mechanisms. In this study, we first observed that 60- or 900-nm PS-NPs (especially 60-nm PS-NPs) could cross mouse placentas and affect developing mice fetuses. To avoid the indirect adverse effects derived from the restricted placenta, we employed early chick embryos as a developmental model to evaluate direct adverse effects of PS-NPs on embryo/fetal development, revealing suppressive effects on embryo development and an increased frequency of congenital abnormalities (especially in the nervous system), including neural tube defects. Thus, we focused on the potential negative effects of PS-NPs on neurulation, the earliest stage of nervous system development. Using caveolin-1 immunofluorescent staining of SH-SY5Y cells exposed to PS-NPs-GFP, we demonstrated that PS-NPs were internalized by SH-SY5Y cells via caveolae-mediated endocytosis. Transmission electron microscopy; LC3B immunofluorescent staining; and Atg7, Atg5, p62 and LC3B western blot results revealed that autophagy was activated in SH-SY5Y cells exposed to PS-NPs. However, PS-NPs were not degraded by the autophagic-lysosomal system given the lack of LAMP1 changes and minimal PS-NPs-GFP and LAMP1 colocalization. Furthermore, the cytoplasmic accumulation of PS-NPs caused faulty apoptotic cell death in SH-SY5Y cells and the developing neural tube as revealed by c-caspase3 immunofluorescent staining. Thus, defective neural tube morphogenesis, as demonstrated by neural tube defects, occurred during embryogenesis in the context of PS-NP exposure.

摘要

越来越多的证据表明，聚苯乙烯纳米塑料 (PS-NPs) 在包括人类在内的各种生物体中的生物积累会对健康造成破坏性影响。纳米塑料可能会对胎儿发育产生潜在的不利影响，因为它们可以穿过胎盘屏障。然而，人们对聚苯乙烯纳米塑料的胚胎毒性知之甚少，尤其是在胚胎神经形成、胎儿的早期发育阶段，以及相应的机制。在这项研究中，我们首先观察到 60-或 900-nm PS-NPs（尤其是 60-nm PS-NPs）可以穿过小鼠胎盘并影响发育中的小鼠胎儿。为了避免来自受限胎盘的间接不利影响，我们采用早期鸡胚作为发育模型来评估 PS-NPs 对胚胎/胎儿发育的直接不利影响，揭示对胚胎发育的抑制作用和先天性异常（尤其是神经系统）的频率增加，包括神经管缺陷。因此，我们专注于 PS-NPs 对神经发育的潜在负面影响，这是神经系统发育的最早阶段。使用暴露于 PS-NPs-GFP 的 SH-SY5Y 细胞的 caveolin-1 免疫荧光染色，我们证明了 PS-NPs 通过小窝介导的内吞作用被 SH-SY5Y 细胞内化。透射电子显微镜；LC3B免疫荧光染色；Atg7、Atg5、p62 和 LC3B 蛋白质印迹结果显示，在暴露于 PS-NPs 的 SH-SY5Y 细胞中自噬被激活。然而，由于缺乏 LAMP1 变化和最小的 PS-NPs-GFP 和 LAMP1 共定位，PS-NPs 不会被自噬-溶酶体系统降解。此外，如 c-caspase3 免疫荧光染色所揭示的，PS-NPs 的细胞质积累导致 SH-SY5Y 细胞和发育中的神经管中的错误凋亡细胞死亡。因此，如神经管缺陷所证明的那样，在 PS-NP 暴露的情况下，胚胎发生过程中发生了有缺陷的神经管形态发生。