The effects of house dust-derived mixtures of organophosphate esters on Leydig cell phenotype, function, and lipidome†

Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, are frequently detected in indoor environments and human tissues, raising concerns about their potential endocrine-disrupting effects. In this study, we examined the effects of a household dust-based mixture of OPEs, along with two structural distinct sub-mixtures, on the phenotype, function, and lipidome on MA10 Leydig cells. Using high-content imaging, we identified increase in oxidative stress levels and accumulation of lipid droplets as common phenotypic effects across mixtures. Notably, the triaryl OPE sub-mixture exhibited greater potency, suggesting that specific structural features contribute to the toxicity of OPEs. While the OPE mixture did not impair basal steroid hormone production in MA-10 cells, changes were observed in stimulated progesterone levels and transcriptional regulation of key steroidogenic transcripts. When comparing lipidomic profiles across three steroidogenic cell lines (MA-10, H295R, and KGN), we found that glycerolipids, particularly triglycerides and diglycerides, consistently appeared to be the most affected lipid species, highlighting a common disruption in the composition of lipid droplet. However, cell line specific effects were also observed, especially in the regulation of cholesterol esters, likely reflecting differences in cholesterol sourcing and steroidogenic pathways. These findings emphasize the importance of evaluating environmentally relevant chemical mixtures and demonstrate that OPEs can disrupt steroidogenic function and lipid metabolism.