House Dust-Derived Mixtures of Organophosphate Esters Alter the Phenotype, Function, Transcriptome, and Lipidome of KGN Human Ovarian Granulosa Cells
Background: Organophosphate esters (OPEs), used as flame retardants and plasticizers, are present ubiquitously in the environment. Previous studies suggested that exposure to OPEs may be detrimental to female fertility in humans. However, no experimental information is available on the effects of OPE mixtures on ovarian granulosa cells, which play essential roles in female reproduction.  Objectives: The goal of this study was to elucidate the effects of OPE mixtures representative of those found in Canadian house dust on ovarian granulosa cells. Methods: We used high-content imaging to investigate the effects an environmentally relevant OPE mixtures on KGN human granulosa cell phenotypes. Perturbation to steroidogenesis was assessed using ELISA and qRT-PCR. A high-throughput transcriptomic approach, TempO-Seq, was used to identify transcriptional changes in a targeted panel of genes. Effects on lipid homeostasis were explored using cholesterol assay and global lipidomic profiling. Results: OPE mixtures with distinct structural characteristics altered multiple phenotypic features of KGN cells with different potencies. The mixtures increased basal production of steroid hormones; this was mediated by significant changes in the expression of critical transcripts involved in steroidogenesis. Further, the total-OPE mixture disrupted cholesterol homeostasis and the composition of intracellular lipid droplets. Discussion: Exposure to house dust-derived mixtures of OPEs may adversely affect female reproductive health by altering a multitude of phenotypic and functional endpoints in granulosa cells. This study provides novel insights into the mechanisms of actions underlying the toxicity induced by OPE mixtures and highlights the need to examine the effects of human relevant chemical mixtures. Overall design: We used a high-throughput transcriptomic approach, TempO-Seq, to examine the expression of 3386 probes covering 2730 genes in the human S1500+ gene set in KGN cells following exposure to a house dust-derived OPE mixture for 48 hrs.