The Role of Peroxisome Proliferator­Activated Receptor Gamma (PPARγ) in Mono(2-ethylhexyl) Phthalate (MEHP)-Mediated Cytotrophoblast Differentiation.

BACKGROUND: Phthalates are environmental contaminants commonly used as plasticizers in polyvinyl chloride (PVC) products. Recently, exposure to phthalates has been associated with preterm birth, low birth weight, and pregnancy loss. There is limited information about the possible mechanisms linking maternal phthalate exposure and placental development, but one such mechanism may be mediated by peroxisome proliferator­activated receptor γ (PPARγ). PPARγ belongs to the nuclear receptor superfamily that regulates, in a ligand-dependent manner, the transcription of target genes. Studies of PPARγ-deficient mice have demonstrated its essential role in lipid metabolism and placental development. In the human placenta, PPARγ is expressed in the villous cytotrophoblast (VCT) and is activated during its differentiation into syncytiotrophoblast. OBJECTIVES: The goal of this study was to investigate the action of mono(2-ethylhexyl) phthalate (MEHP) on PPARγ activity during in vitro differentiation of VCTs. METHODS: We combined immunofluorescence, PPARγ activity/hCG assays, western blotting, and lipidomics analyses to characterize the impacts of physiologically relevant concentrations of MEHP (0.1, 1, and 10 µM) on cultured VCTs isolated from human term placentas. RESULTS: Doses of 0.1 and 1 µM MEHP showed significantly lower PPARγ activity and less VCT differentiation in comparison with controls, whereas, surprisingly, a 10 µM dose had the opposite effect. MEHP exposure inhibited hCG production and significantly altered lipid composition. In addition, MEHP had significant effects on the mitogen-activated protein kinase (MAPK) pathway. CONCLUSIONS: This study suggests that MEHP has a U-shaped dose­response effect on trophoblast differentiation that is mediated by the PPARγ pathway and acts as an endocrine disruptor in the human placenta. https://doi.org/10.1289/EHP3730.

Lipidome-wide disturbances of human placental JEG-3 cells by the presence of MEHP.

During pregnancy, exposure to environmental contaminants can lead to adverse effects on fetal growth and development, especially by targeting the placenta. Di(2-ethylhexyl)phthalate (DEHP), the most abundant chemical used in plastic materials, is known to induce toxicity on animals reproductive system and is suspected to give rise to similar effect in humans. Toxicity of DEHP is due to its main metabolite, MEHP, which is also known to disturb lipid synthesis in several organs. Moreover, mono-(2-ethylhexyl)phtalate (MEHP) is a high affinity ligand of the peroxisome proliferator-activated receptor PPARγ which is essential for placental development and lipid metabolism. In order to investigate possible lipid disruptions induced by MEHP, in the JEG-3 human trophoblast cell line, a differential lipidomic analysis was carried out by UPLC-MS on both exposed and control cells. Our results showed that MEHP induced an important change of JEG-3 cells lipidome, especially in glycerolipids and glycerophospholipids, with a marked accumulation of triacylglycerols. For the first time, our results highlighted adverse effects of MEHP on human placental cells lipidome and thus, its potential effect on placental physiology.

Synthesis of a molecularly imprinted sorbent for selective solid-phase extraction of ß-N-methylamino-L-alanine.

The aim of the work was to synthesize a molecularly imprinted material for the selective solid-phase extraction (SPE) of ß-N-methylamino-L-alanine (L-2-amino-3-methylpropionic acid; BMAA) from cyanobacterial extracts. BMAA and its structural analogs that can be used as template are small, polar and hydrophilic molecules. These molecules are poorly soluble in organic solvents that are commonly used for the synthesis of acrylic-based polymers. Therefore, a sol gel approach was chosen to carry out the synthesis and the resulting sorbents were evaluated with different extraction procedures in order to determine their ability to selectively retain BMAA. The presence of imprinted cavities in the sorbent was demonstrated by comparing elution profiles obtained by using molecularly imprinted silica (MIS) and non-imprinted silica (NIS) as a control. The molecularly imprinted solid-phase extraction (MISPE) procedure was first developed in a pure medium (acetonitrile) and further optimized for the treatment of cyanobacterial samples. It was characterized by high elution recoveries (89% and 77% respectively in pure and in real media).The repeatability of the extraction procedure in pure medium, in real medium and the reproducibility of MIS synthesis all expressed as RSD values of extraction recovery of BMAA were equal to 3%, 12% and 5%, respectively. A MIS capacity of 0.34 µmol/g was measured. The matrix effects, which affected the quantification of BMAA when employing a mixed mode sorbent, were completely removed by adding a clean-up step of the mixed-mode sorbent extract on the MIS.