Lactiplantibacillus plantarum F57 mitigates waterborne polypropylene microplastic-induced liver injury via gut microbiota modulation in zebrafish.

Polypropylene microplastics (PP-MPs) are pervasive aquatic pollutants, but the hepatotoxicity of waterborne large-sized PP-MPs and potential probiotic interventions remain poorly understood. Here, we evaluated the protective effects of Lactiplantibacillus plantarum (L. plantarum) strains against liver injury induced by 50-μm PP-MPs in zebrafish. PP-MPs exposure was associated with liver damage, including inflammatory activation, histopathological lesions, elevated plasma ALT and ALP, and oxidative stress. Among the tested strains, L. plantarum F57 showed the most pronounced protective association, accompanied by substantial alleviation of inflammatory liver pathology and partial normalization of hepatic biochemical parameters. Spearman correlation analysis indicated that in vitro antioxidant capacity was more closely associated with attenuation of liver injury than the capacity for PP-MPs adsorption. 16S rRNA sequencing showed that F57 supplementation was associated with an alleviation of PP-MPs-induced gut microbiota dysbiosis, reflected by increased alpha diversity, enrichment of potentially beneficial taxa, and a reduction in Aeromonas. Hepatic transcriptomic analysis further revealed that PP-MPs were associated with extracellular matrix-related disruption, whereas F57 supplementation was accompanied by transcriptomic changes involving innate immune-related pathways, including NIK/NF-κB, Toll-like receptor, and NOD-like receptor signaling. Overall, these findings support a protective role of L. plantarum F57 against PP-MPs-associated hepatotoxicity in zebrafish and suggest that this effect is accompanied by changes in oxidative status, gut microbiota composition, and hepatic immune-related transcriptional responses.