Abstract

Rodent studies on the effects of engineered nanomaterials (ENM) on the gut microbiome have revealed contradictory results. Our aim was to assess the effects of four well-investigated model ENM using a realistic exposure scenario. Two independent ad libitum feeding studies were performed. In study 1, female mice from the local breeding facility received feed pellets containing 1% CeO₂ or 1% SiO₂ for three weeks. In study 2, both female and male mice were purchased and exposed to 0.2% Ag-PVP or 1% TiO₂ for four weeks. A next generation 16S rDNA sequencing-based approach was applied to assess impacts on the gut microbiome. None of the ENM had an effect on the α- or β-diversity. A decreased relative abundance of the phylum Actinobacteria was observed in SiO₂ exposed mice. In female mice, the relative abundance of the genus Roseburia was increased with Ag exposure. Furthermore, in study 2, a sex-related difference in the β-diversity was observed. A difference in the β-diversity was also shown between the female control mice of the two studies. We did not find major effects on the gut microbiome. This contrast to other studies may be due to variations in the study design. Our investigation underlined the important role of the sex of test animals and their microbiome composition prior to ENM exposure initiation. Hence, standardization of microbiome studies is strongly required to increase comparability. The ENM-specific effects on Actinobacteria and Roseburia, two taxa pivotal for the human gut homeostasis, warrant further research on their relevance for health.

摘要

关于工程纳米材料 (ENM) 对肠道微生物组影响的啮齿动物研究揭示了相互矛盾的结果。我们的目标是使用真实的暴露场景评估四个经过充分研究的模型 ENM 的影响。进行了两项独立的随意喂养研究。在研究 1 中，来自当地饲养设施的雌性小鼠连续三周接受含有 1% CeO ₂或 1% SiO _{2 的}饲料颗粒。在研究 2 中，购买雌性和雄性小鼠并接触 0.2% Ag-PVP 或 1% TiO ₂四个星期。应用基于下一代 16S rDNA 测序的方法来评估对肠道微生物群的影响。ENM 对α-或β-多样性没有影响。在暴露于 SiO _{2 的}小鼠中观察到放线菌门的相对丰度降低。在雌性小鼠中，Roseburia属的相对丰度银暴露增加。此外，在研究 2 中，观察到 β 多样性的性别相关差异。两项研究的雌性对照小鼠之间也显示了 β 多样性的差异。我们没有发现对肠道微生物组的重大影响。与其他研究的这种对比可能是由于研究设计的变化。我们的调查强调了在 ENM 暴露开始之前测试动物的性别及其微生物组组成的重要作用。因此，强烈需要微生物组研究的标准化以增加可比性。ENM 对放线菌和 Roseburia 的特异性影响，这两种对人类肠道稳态至关重要的分类群，需要进一步研究它们与健康的相关性。