Chemical Exposures and Epidermal Growth Factor-mediated Placental Cell Dysfunction

Placental development is essential for fetal growth, with the epidermal growth factor receptor (EGFR) playing a critical role in trophoblast cell functions such as proliferation, fusion, and invasion. Dysfunction in EGFR signaling has been linked to pregnancy complications like preeclampsia and intrauterine growth restriction. Environmental chemical, including polychlorinated biphenyls (PCBs), bisphenols, and pesticides, are known to interfere with EGFR activation, potentially affecting placental function. This study explores the effects of a mixture of EGFR-disrupting chemicals (Chem-Mix), including PCB-126, PCB-153, atrazine, bisphenol S, trans-nonachlor, and niclosamide, on placental trophoblast cells. The impact of Chem-Mix on EGFR activation, trophoblast cell functions (proliferation, invasion, and differentiation), and placental bioenergetics was evaluated using HTR-8/SVneo cells and third-trimester human primary cytotrophoblasts. Methods included EGFR binding assays, RNA sequencing, mitochondrial and glycolytic stress tests, ATP production, glucose consumption, and super-resolution imaging. Additionally, first-trimester placental villus explants exposed to Chem-Mix were analyzed for cytokine, human chorionic gonadotropin (hCG), and soluble fms-like tyrosine kinase-1 (sFlt-1) secretion. Chem-Mix competed with EGF for EGFR binding and reduced EGFR phosphorylation in a dose-dependent manner, impairing trophoblast cell invasion independent of EGF. The mixture altered mitochondrial function by diminishing the maximum respiratory capacity and ATP production in a dose-dependent manner. While EGF increased oxygen consumption and glycolytic acidification, Chem-Mix reduced both EGF-mediated and basal bioenergetic functions. Super-resolution imaging revealed a disruption in mitochondrial network architecture, supported by a decrease in the mitochondrial fusion protein OPA1. RNA sequencing further showed changes in the transcriptional profile of genes involved in cellular energetics. Cytokine analysis of placental villus explants showed altered secretion of IL-1RA, IL-27, EGF, and Fractalkine by the Chem-Mix in an EGF-dependent manner. Concentrations of hCG and sFlt-1 decreased with gestational age, with reduced concentrations by Chem-Mix plus EGF and these effects were sex specific. Exposure to a mixture of EGFR-disrupting chemicals alters placental function, bioenergetics, and secretory profiles during early pregnancy, potentially contributing to adverse pregnancy outcomes. These findings underscore the need for further research into the mechanisms of chemical-induced disruptions in placental development and the implications for pregnancy health.