Unravelling the mechanisms of PFOS toxicity by combining morphological and transcriptomic analyses in zebrafish embryos

Exposure to PFOS (perfluorooctanesulfonate) has been related to toxic effects on lipid metabolism, immunological response, and different endocrine systems. We present here a transcriptomic analysis of zebrafish embryos exposed to different concentrations of PFOS (0.03–1.0 mg/L) from 48 to 120 hpf. No major survival or morphological alterations (swimming bladder inflation, kyphosis, eye separation and size…) were observed below the 1.0 mg/L mark. Conversely, we observed significant increase in transcripts related to lipid transport and metabolism even at the lowest used concentration. In addition, we observed a general decrease on transcripts related to natural immunity and defense again infections, which adds to the recent concerns about PFOS as immunotoxicant, particularly in humans. Derived PoD (Point of Departure) values for transcriptional changes (0.011 mg/L) were about 200-fold lower than the corresponding PoD values for morphometric effects (2.53 mg/L), and close to levels observed in human blood serum or bird eggs. Our data suggest that currently applicable tolerable levels of PFOS in commercial goods should be re-evaluated, taking into account its potential effects on lipid metabolism and the immune system.This work was supported by European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement n. 320737, and by the Spanish Ministry of Economy and Competitiveness (CTM2014-51985-R). AEC acknowledges the funding from ISCIII (Spanish Ministry of Economy and Competitiveness, grant number PT17/0009/0019), co-financed by the European Fund for Regional Development (FEDER). LNM was supported by a Beatriu de Pinos Postdoctoral Fellowship (2013BP-B-00088) funded by the Secretary for Universities and Research of the Department of Economy and Knowledge of the Government of Catalonia and the Cofund programme of the Marie Curie Actions of the 7th R&D Framework Programme of the European Union. RML was supported by an FPU Fellowship (FPU15/03332) from the Spanish Ministry of Education, Culture and Sport.Peer reviewe