Replacement Flame-Retardant 2-Ethylhexyldiphenyl Phosphate (EHDPP) Disrupts Hepatic Lipidome: Evidence from Human 3D Hepatospheroid Cell Culture

Abstract

The present study aims to evaluate the effects of repeated exposure to 2-ethylhexyldiphenyl phosphate (EHDPP) on human liver cells. In vitro three-dimensional (3D) hepatospheroid cell culture was utilized to explore the potential mechanisms of EHDPP-mediated metabolic disruption through morphological, transcriptional, and biochemical assays. Lipidomics analysis was performed on the individual hepatospheroids to investigate the effects on intracellular lipid profiles, followed by hepatospheroid morphology, growth, functional parameters, and cytotoxicity evaluation. The possible mechanisms were delineated using the gene-level analysis by assessing the expression of key genes encoding for hepatic lipid metabolism. We revealed that exposure to EHDPP at 1 and 10 μM for 7 days alters the lipid profile of human 3D hepatospheroids. Dysregulation in several lipid classes, including sterol lipids (cholesterol esters), sphingolipids (dihydroceramide, hexosylceramide, ceramide, sphingomyelin), glycerolipids (triglycerides), glycerophospholipids, and fatty acyls, was noted along with alteration in genes including ACAT1, ACAT2, CYP27A1, ABCA1, GPAT2, PNPLA2, PGC1α, and Nrf2. Our study brings a novel insight into the metabolic disrupting effects of EHDPP and demonstrates the utility of hepatospheroids as an in vitro cell culture model complemented with omics technology (e.g., lipidomics) for mechanistic toxicity studies.

Effects of Indoor Dust Exposure on Lung Cells: Association of Chemical Composition with Phenotypic and Lipid Changes in a 3D Lung Cancer Cell Model

“…Specifically, the study identified disruptions in lipid metabolism induced by TPhP, characterized by an increase in triglycerides (TGs) and a decrease in Cer and SM species, among other alterations. In another study, similar lipid disruption profiles were found for EHDPP in HepG2, confirming the adipogenic behavior induced by the OPE family . Concerning cell death induction, a work by Yu et al explored the toxicity of OPEs on A549 cells and reported that TPhP is one of the most cytotoxic OPE compounds .…”

“…In another study, similar lipid disruption profiles were found for EHDPP in HepG2, confirming the adipogenic behavior induced by the OPE family. 51 Concerning cell death induction, a work by Yu et al explored the toxicity of OPEs on A549 cells and reported that TPhP is one of the most cytotoxic OPE compounds. 52 Also, preliminary results of another study in our laboratory show that the exposure of A549 cells to TPhP causes a higher level of cell death than other OPEs at the same concentration (data not published).…”

Lipid Metabolic Disorders Induced by Organophosphate Esters in Silver Carp from the Middle Reaches of the Yangtze River

“…The alterations in lipid homeostasis induced by the OPEs were also observed in several previous studies. For instance, treatment with 10 μM EHDPP led to a significant increase in the concentrations of glycerophospholipids such as PE and PI and decreased the total concentrations of Cer and SM in human liver cells . Exposure to TPHP for 48 h increased TG, PA, and Cer levels but decreased SM and PE levels in JEG-3 cells .…”

“…For instance, treatment with 10 μM EHDPP led to a significant increase in the concentrations of glycerophospholipids such as PE and PI and decreased the total concentrations of Cer and SM in human liver cells. 16 Exposure to TPHP for 48 h increased TG, PA, and Cer levels but decreased SM and PE levels in JEG-3 cells. 44 Moreover, a recent epidemiological study reported that serum levels of tripropyl phosphate (TPrP) and tri-n-butyl phosphate (TnBP) presented negative correlations with PG (18:0) and positive correlations with PI (18:1/22:2), 45 which further supports our findings of lipid metabolism dysfunction induced by OPEs in silver carp.…”

“…These results suggest that OPEs may have potential toxicities for exposed wild fish. Laboratory research has demonstrated that OPEs induce a variety of adverse effects in fish, such as growth inhibition, hepatotoxicity, neurotoxicity, metabolic disruption toxicity, and endocrine disrupting effects. − However, the ecotoxicological effects of OPEs on wild fish remain largely unknown. Limited studies have reported that some OPEs cause mass mortality of crucian carp embryos in Taihu Lake and growth inhibition of silver carp in the Yangtze River, suggesting that the contamination of OPEs in natural aquatic ecosystems might cause fish population/biomass decline. , …”