The universal presence of micro-nanoplastics (MNPLs) and its relative unknown effects on human health is a concern demanding reliable data to evaluate their safety. As ingestion is one of the main exposure routes for humans, we have assessed their hazard using two in vitro models that simulate the human intestinal barrier and its associated lymphoid system. Two different coculture models (differentiated Caco-2/HT29 intestinal cells and Caco-2/HT29 + Raji-B cells) were exposed to polystyrene nanoparticles (PSNPs) for 24 h. Endpoints such as viability, membrane integrity, NPS localization and translocation, ROS induction, and genotoxic damage were evaluated to have a comprehensive view of their potentially harmful effects. No significant cytotoxic effects were observed in any of the analyzed systems. In addition, no adverse effects were detected in the integrity or in the permeability of the barrier model. Nevertheless, confocal microscopy analysis showed that MNPLs were highly uptaken by both of the barrier model systems, and that translocation across the membrane occurred. Thus, MNPLs were detected into Raji-B cells, placed in the basolateral compartment of the insert. The internalization followed a dose-dependent pattern, as assessed by flow cytometry. Nonetheless, no genotoxic or oxidative DNA damage induction was detected in either case. Finally, no variations in the transcription of oxidative and stress genes could be detected in any of the in vitro barrier models. Our results show that MNPLs can enter and cross the epithelial barrier of the digestive system, as demonstrated when Raji-B cells were included in the model, but without exerting apparent hazardous effects.

微纳米塑料（MNPL）的普遍存在及其对人类健康的相对未知的影响是一个令人担忧的问题，需要可靠的数据来评估其安全性。由于摄入是人类的主要暴露途径之一，因此我们使用两种体外模型来评估其危害，这些模型模拟了人类肠道屏障及其相关的淋巴系统。将两种不同的共培养模型（分化的Caco-2 / HT29肠道细胞和Caco-2 / HT29 + Raji-B细胞）暴露于聚苯乙烯纳米颗粒（PSNP）24小时。评估了诸如生存力，膜完整性，NPS定位和易位，ROS诱导和遗传毒性损害等端点，以全面了解其潜在危害。在任何分析系统中均未观察到明显的细胞毒性作用。此外，在屏障模型的完整性或渗透性中未检测到不利影响。然而，共聚焦显微镜分析表明，两种屏障模型系统都高度摄取MNPL，并且发生了跨膜易位。因此，将MNPLs检测到置于插入物基底外侧区室的Raji-B细胞中。通过流式细胞术评估，内在化遵循剂量依赖性模式。但是，在两种情况下均未检测到遗传毒性或氧化性DNA损伤诱导。最后，在任何体外屏障模型中均未检测到氧化和应激基因转录的变化。我们的结果表明，MNPL可以进入并穿过消化系统的上皮屏障，如模型中包含Raji-B细胞所示，