Orally ingested nanosilica causes liver-specific accumulation and induces liver senescence and fibrosis via the microbiota-gut-liver axis

BACKGROUND: The increased use of nanosilica (SiO₂ NPs) poses a safety risk to public health. Current research on the tissue distribution and microbiota-gut-liver crosstalk toxicity of orally ingested SiO₂ NPs remains poorly understood. In this study, we examined the distribution of SiO₂ NPs by gavage in major organs as well as liver senescence and fibrotic injury induced by microbiota-gut-liver crosstalk following the sub-chronic oral ingestion thereof. In addition, probiotics were administered to investigate their protective potential against SiO₂ NPs-induced hepatotoxicity. RESULTS: Our results showed that C57BL/6J mice that received orally administered SiO₂ NPs for 12 w exhibited gut dysbiosis, imbalance of metabolites (short-chain fatty acids and lactate), intestinal barrier damage, and disruption of gut homeostasis. Furthermore, ICP-OES revealed the silicon accumulation in the Liver, with 165% increase compared to the control, higher than that in other tissue. Liver exhibited functional abnormalities and underwent Lipid deposition, autophagy, senescence and fibrosis. 16S rRNA sequencing analysis demonstrated that SiO₂ NPs reduced the abundance of probiotic Muribaculum and Ligilactobacillus, while increasing that of pathogenic Helicobacter. Notably, supplementation with probiotics remodelled the gut microbiome, particularly corrected the microbial communities disrupted by SiO₂ NPs, increased the proliferation of other probiotics, and reduced harmful bacteria. Moreover, the results of Masson staining, Nile red staining, and immunofluorescence showed that probiotic supplementation ameliorated liver lipid deposition, senescence, and fibrosis induced by the oral ingestion of SiO₂ NPs. Mechanistically, the TLR4/NF-κB and caspase-3-cytochrome C pathways may be involved in SiO₂ NPs-induced hepatotoxicity and probiotic regulation. CONCLUSIONS: Continuous oral ingestion of SiO₂ NPs induced liver-specific accumulation, and caused abnormal deposition of liver lipids, senescence and fibrosis via microbiota-gut-liver crosstalk. Microbial therapy involving probiotic supplementation mitigated SiO₂ NPs-induced hepatotoxicity and exerted protective effects. This study provides a scientific reference for the rational application, risk management, and prevention of the harmful effects caused by SiO₂ NPs.