Unveiling the molecular toxicity of plasticizers derived from microplastics (DMP and DEP) in diabetic kidney disease: integrative insights from network toxicology and multi-omics analysis

Abstract

Diabetic kidney disease (DKD) is a prevalent microvascular complication with limited therapeutic options. This study aimed to identify biomarkers associated with microplastic-associated plasticizers in DKD and to explore their potential molecular mechanisms. Publicly available datasets were integrated for biomarker discovery, followed by experimental validation in human proximal tubular epithelial cells (HK-2). Pathway enrichment and immune infiltration analyses were performed to characterize the biological relevance of the identified biomarkers. Molecular docking and molecular dynamics simulations were used to evaluate the predicted interactions between the biomarkers and the plasticizers dimethyl phthalate (DMP) and diethyl phthalate (DEP). Single-cell transcriptomic analysis was further conducted to characterize the cell-type-specific expression of the identified biomarkers. CASP3, PTGES, and SLC6A2 were identified as candidate biomarkers. Pathway analysis revealed that these genes were notably enriched in oxidative phosphorylation, while immune infiltration analysis indicated a strong correlation between PTGES and memory B cells. Molecular docking and molecular dynamics simulations predicted stable interactions between the biomarkers and DMP and DEP. In vitro experiments further showed that DMP and DEP exposure reduced HK-2 cell viability, promoted apoptosis, and dysregulated the expression of CASP3, PTGES, and SLC6A2. Notably, these toxic effects were exacerbated under high-glucose conditions, suggesting an enhanced combined effect between the diabetic milieu and plasticizer-induced stress. Single-cell transcriptomic analysis further indicated predominant CASP3 expression in proximal convoluted tubule (PCT) cells. This study provides a hypothesis-generating framework by identifying CASP3, PTGES, and SLC6A2 as potential DKD biomarkers that are computationally predicted and experimentally shown to be regulated by microplastic-associated plasticizers. These findings suggest potential molecular links between plasticizer exposure and DKD-related cellular injury; however, their exposure-dependent relevance and mechanistic roles in human DKD require further validation.