微塑料已成为严重的环境污染物，并因此对人类健康产生了有害影响。因此，需要探讨微塑料对人类细胞的影响。本研究探讨了聚苯乙烯纳米塑料（PS-NPs，直径为21.5±2.7 nm）对人类肝细胞癌（HepG2）细胞系亚细胞器水平的细胞毒性影响。在6.25、12.5、25和50 μg/mL的浓度下暴露24小时后，PS-NPs处理显著浓度依赖性地降低了细胞存活率。PS-NPs处理导致线粒体损伤，包括形态学改变、腺苷酸三磷酸（ATP）产生减少和线粒体膜电位（MMP）丢失。PS-NPs处理通过上调HepG2细胞中的caspase 3、caspase 9、细胞色素c和Bcl-2相关X蛋白（Bax）/B细胞淋巴瘤-2（Bcl-2）等蛋白质，引发了细胞凋亡，这种凋亡与线粒体功能障碍有关。PS-NPs暴露能够刺激细胞内过量的活性氧自由基（ROS）产生，并通过上调有丝分裂动力蛋白相关蛋白1（DRP1）和磷酸化DRP1，降低视神经萎缩蛋白1（OPA1）和过氧化物酶体增殖物激活受体-gamma共激活因子1alpha（PGC-1α）的表达水平，导致线粒体分裂。通过N-乙酰半胱氨酸（NAC）、线粒体分裂抑制剂1（Mdivi-1）和DRP1 siRNA的预处理可以逆转由PS-NPs诱导的线粒体损伤。结果表明ROS和DRP1依赖的线粒体分裂之间的相互作用促进了由PS-NPs引起的线粒体损伤和线粒体相关的凋亡。这些分子机制上的发现为预防微塑料对人类健康产生的危害提供了理论依据。© 2023年版权所有。Elsevier B.V.出版。

Microplastics have become a serious environmental pollutant and subsequently have harmful effects on human health. Thus, the impacts of microplastics on human cells need to be explored. In the present study, the cytotoxic effects at the subcellular-organelle levels to polystyrene nanoplastics (PS-NPs, diameter 21.5 ± 2.7 nm) were investigated in the human hepatocellular carcinoma (HepG2) cell line. The cell viability exposed to PS-NPs at the concentrations of 6.25, 12.5, 25 and 50 μg/mL for 24 h diminished in a concentration-dependent manner. The PS-NPs treatment induced mitochondrial injuries, including morphological changes, decreased adenosine triphosphate (ATP) production and the loss of mitochondrial membrane potentials (MMP). The PS-NPs treatment could further spark cell apoptosis by upregulating caspase 3, caspase 9, cytochrome c, and Bcl-2 associated X protein (Bax)/B-cell lymphoma-2 (Bcl-2) in HepG2 cells, which is related to the mitochondrial dysfunction. PS-NPs exposure stimulated the excessive cellular reactive oxygen species (ROS) production and also induced mitochondrial fission by upregulating dynamin-related protein 1 (DRP1) and P-DRP1, but downregulating optic atrophy protein 1 (OPA1) and peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1α) expression levels. The above effects on mitochondria damage induced by PS-NPs were reversed by the pretreatment of N-acetylcysteine (NAC), mitochondrial division inhibitor 1 (Mdivi-1) and DRP1 siRNA. The results suggested that the interaction between ROS and DRP1-dependent mitochondrial division could promote mitochondrial lesions and mitochondria-related apoptosis caused by PS-NPs. These findings on molecular mechanisms provide a theoretical basis for preventing the hazards caused by microplastics to human health.Copyright © 2023. Published by Elsevier B.V.