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Toxicol In Vitro 2024 Mar 01;95:105762. doi: 10.1016/j.tiv.2023.105762.
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In vitro screening of per- and polyfluorinated substances (PFAS) for interference with seven thyroid hormone system targets across nine assays.

Degitz SJ , Olker JH , Denny JS , Degoey PP , Hartig PC , Cardon MC , Eytcheson SA , Haselman JT , Mayasich SA , Hornung MW .

The US Environmental Protection Agency is evaluating the ecological and toxicological effects of per- and polyfluorinated chemicals. A number of perfluorinated chemicals have been shown to impact the thyroid axis in vivo suggesting that the thyroid hormone system is a target of these chemicals. The objective of this study was to evaluate the activity of 136 perfluorinated chemicals at seven key molecular initiating events (MIE) within the thyroid axis using nine in vitro assays. The potential MIE targets investigated are Human Iodothyronine Deiodinase 1 (hDIO1), Human Iodothyronine Deiodinase 2 (hDIO2), Human Iodothyronine Deiodinase 3 (hDIO3), Xenopus Iodothyronine Deiodinase (xDIO3); Human Iodotyrosine Deiodinase (hIYD), Xenopus Iodotyrosine Deiodinase (xIYD), Human Thyroid Peroxidase (hTPO); and the serum binding proteins Human Transthyretin (hTTR) and Human Thyroxine Binding Globulin (hTBG). Of the 136 PFAS chemicals tested, 85 had sufficient activity to produce a half-maximal effect concentration (EC50) in at least one of the nine assays. In general, most of these PFAS chemicals did not have strong potency towards the seven MIEs examined, apart from transthyretin binding, for which several PFAS had potency similar to the respective model inhibitor. These data sets identify potentially active PFAS chemicals to prioritize for further testing in orthogonal in vitro assays and at higher levels of biological organization to evaluate their capacity for altering the thyroid hormone system and causing potential adverse health and ecological effects.

PubMed ID: 38072180
PMC ID: PMC11081714
Article link: Toxicol In Vitro

Species referenced: Xenopus laevis
Genes referenced: dio1 dio2 dio3 iyd tpo
GO keywords: thyroxine 5'-deiodinase activity [+]