Effects of orally exposed SiO2 nanoparticles on lipid profiles in gut-liver axis of mice

Recently we proposed the possibility of orally exposed nanoparticles (NPs) to alter metabolite homeostasis by changing metabolism pathways, in addition to intestinal damages, but relatively few studies investigated the changes of metabolite profiles in multi-organs. This study investigated the influences of orally exposed SiO₂ NPs on lipid profiles in gut-liver axis. To this end, we treated mice with 16, 160 or 1600 mg/kg bodyweight SiO₂ NPs via intragastric route. After 5 days exposure (once a day), we observed that SiO₂ NPs induced minimal pathological changes but increased most of the trace elements. Furthermore, lipid staining was gradually decreased in intestines and livers with the increase of NP levels. Consistently, lipidomics results showed that most of the lipid classes in mouse intestines and livers were decreased following SiO₂ NP administration. We further identified the lipid classes significantly decreased in both intestines and livers, such as phosphatidylserine (PS), phosphatidylglycerol (PG), and phosphatidylethanolamine (PE). Only a few lipid classes, such as anandamide, showed opposite trends in these organs. For metabolism pathway, SiO₂ NPs suppressed autophagy, showing as a significant decrease of microtubule-associated protein 1 A/1B light chain 3 (LC3) and adipose triglyceride lipase (Atgl), accompanying with an accumulation of P62, in both intestines and livers. However, lysosomal-associated membrane protein 2 (Lamp2) showed different trend, that it was significantly increased in intestines but decreased in livers. Combined, our results indicated that intragastric administration of SiO₂ NPs altered trace element balance and lipid profiles, accompanying with a change of autophagic lipolysis proteins, in mouse gut-liver axis.