Toxic mechanisms of PET microplastics in recurrent pregnancy loss: integrating network toxicology with experimental validation

Abstract Objective Polyethylene terephthalate microplastics (PET-MPs) are widespread emerging environmental pollutants, yet their pathogenic role in recurrent pregnancy loss (RPL) has not been clarified. This study intended to uncover key molecular targets and mechanisms mediating the connection between PET-MP exposure and RPL. Methods We collected PET-related targets and RPL differentially expressed genes from dataset GSE165004, then performed enrichment and protein-protein interaction analyses on overlapping genes. Machine learning selected hub genes, followed by immune infiltration assessment and molecular docking verification. Decidual single-cell RNA sequencing, YWHAZ virtual knockout, and in vitro PET-MP treatment of trophoblast and endometrial stromal cells were implemented. Results Thirty-five intersecting genes were screened. Four hub genes (YWHAZ, SRC, CYP1A2, PAK2) had promising diagnostic capacity and correlated with immune cell infiltration. Molecular docking revealed stable binding of PET to all four hub proteins. YWHAZ was downregulated in multiple decidual cell subsets of RPL patients, and its knockout disturbed immune pathways. In vitro, PET-MPs suppressed cell viability and YWHAZ protein expression in trophoblast and endometrial stromal cells. Conclusion This exploratory integrated study suggests that PET-MP exposure may contribute to RPL through immune and signaling dysfunction. YWHAZ is identified as a candidate PET-responsive mediator and a potential diagnostic biomarker for RPL. This study provides exploratory mechanistic insights and candidate biomarkers for microplastic‑associated reproductive toxicity.