Polystyrene microplastics are associated with oral microbiome and gingival metabolic perturbations in mice: an exploratory multi-omics study

Background and Objective Microplastics are widespread environmental contaminants that can enter the body through ingestion. This exploratory study aimed to evaluate whether repeated exposure to polystyrene microplastics (PS-MPs) is associated with alterations in the oral microbial community and gingival metabolome in mice.Design C57BL/6 mice were randomly assigned to receive PS-MPs by daily gavage at 0, 5, 10, or 20 mg/kg body weight for 30 days. Oral microbial communities were characterized by 16S rRNA gene sequencing, and gingival metabolic features were profiled using untargeted liquid chromatography-mass spectrometry. Microbiome and metabolomics data were integrated using correlation-based network analysis.Results PS-MPs exposure, particularly at 10 and 20 mg/kg, was associated with reduced observed oral microbial richness and differences in microbial community composition relative to the control group. Beneficial commensal genera such as Gemella and Lactobacillus were depleted, while opportunistic pathogens including Streptococcus and Rodentibacter were relatively enriched. Metabolomic profiling revealed 206 and 270 differential metabolites in the medium- and high-dose groups versus controls, respectively. KEGG pathway enrichment identified nucleotide metabolism, unsaturated fatty acid biosynthesis, and pantothenate/CoA biosynthesis as candidate pathways. In an exploratory integrated network analysis, the microbial dysbiosis index was highest in the high-dose group, and Gemella and catechin-centred metabolite were among the most connected nodes.Conclusions These findings provide exploratory multi-omics evidence that repeated PS-MPs exposure is associated with changes in oral microbial ecology and gingival metabolic profiles in mice. Larger studies integrating direct periodontal outcomes and mechanistic validation are warranted.