Persistent effects of di-n-butyl phthalate on liver transcriptome: impaired energy and lipid metabolic pathways.

Abstract

The environmental contaminant dibutyl phthalate (DBP) is reported to be hepatotoxic, but the underlying molecular pathways and pathological processes remain unclear. Here we used RNA-sequencing to characterize persistent hepatic transcriptional effects one week after the conclusion of five weeks oral exposure to 10 mg/kg/day or 100 mg/kg/day DBP in male mice. The exploratory transcriptome analysis demonstrated five differentially expressed genes (DEGs) in the 10 mg/kg/day group and thirteen in the 100 mg/kg/day group. Gene Set Enrichment Analysis (GSEA), which identifies affected biological pathways rather than focusing solely on individual genes, revealed nine significantly enriched Reactome pathways shared by both DBP treatment groups. Additionally, we found 54 upregulated and one downregulated Reactome pathways in the 10 mg/kg/day DBP group, and 29 upregulated and 13 downregulated pathways in the 100 mg/kg/day DBP group. According to the DEGs and the GSEA findings DBP exposure disrupts several key biological processes, including protein translation, protein folding, apoptosis, hedgehog signaling, degradation of extracellular matrix and alterations in the energy/lipid metabolism. Subsequent liver tissue analysis corroborated these findings, showing that DBP exposure induced tissue disorganization, oxidative stress, lipid accumulation, increased TNF-α, ATP and glucokinase levels. In addition, several proteins central for the metabolic system were affected, mostly in a dose-response pattern. Taken together the results show that DBP can cause hepatic stress and damage and suggest a potential role for DBP in the development of non-alcoholic fat liver disease, the most prevalent liver disease worldwide.