A Mixture Reflecting Polybrominated Diphenyl Ether (PBDE) Profiles Detected in Human Follicular Fluid Significantly Affects Steroidogenesis and Induces Oxidative Stress in a Human Granulosa Cell Line

Brominated flame retardants (BFRs) are incorporated into consumer products to prevent flame propagation. These compounds leach into the domestic environment, resulting in chronic exposure and contamination. Pregnancy failure is associated with high levels of BFRs in human follicular fluid, raising serious questions regarding their impact on female fertility. Our goal was to elucidate effects of a mixture reflecting human follicular fluid levels of polybrominated flame retardants (PBDEs), the major class of BFRs, on an immortalized human granulosa cell line, the KGN cell line. We showed that cell viability was altered and oxidative stress was induced, as reflected by increased reactive oxygen species formation, at 20 µM of the PBDE mixture. Transcriptomic analysis revealed that several genes showing an altered expression after the PBDE treatment were involved in oxidative stress signaling pathways. Significant dose-dependent reduction of progesterone and estradiol levels was measured after PBDE treatment; expression of genes involved in steroid hormone metabolism, namely CYP1A1, was significantly affected by PBDEs. Treatment with the PBDE mixture also modified genes encoding for members of the transforming growth factor β superfamily like inhibins and cytokines, including the pro-inflammatory factor, interleukin-6 (IL6). Concentration of IL-6 in KGN cell culture media was consistently increased after treatment with the PBDE mixture. Our results clearly demonstrate that the PBDEs detected in human follicular fluid alter human granulosa cell functions by inducing oxidative stress, disrupting steroidogenesis and triggering an inflammatory response. This strengthens the fact that PBDEs are detrimental to ovarian functions and thus, to women’s reproductive health. KGN cells were exposed to 0, 1, 5 and 20 µM of a PBDE mixture for 48h; n=6 in triplicates for each experiments except for samples at 5 µM of a PBDE, for which there are 5 replicates.