Advances in thyroid hormone system disruption testing - In vitro method for monitoring disrupted thyrotropin...

In recent years, increasing attention has been directed toward development of in vitro methods to assess thyroid hormone system disrupting chemicals suitable for regulatory applications. As a part of this effort, the EU Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM) coordinated an international validation project through the European Union Network of Laboratories for the Validation of Alternative Methods (EU-NETVAL). This initiative involved the validation of 18 test methods, all aimed at contributing to a comprehensive testing battery for thyroid disruption. This work presents our contribution to the project, specifically focusing on the further development of a method designed to screen for disruption of the human thyrotropin receptor (hTSHR). Our objective is to provide an update on recent advancements in creating a reliable in vitro assay for toxicological assessment of chemicals that mimic or inhibit thyroid-stimulating hormone (TSH) function. We present and discuss pilot data generated using the developed standard operating procedure, including results from the initial testing of coded chemicals. The work highlights key challenges encountered during the method development and offers recommendations for future research and improvement. Our aim is to encourage more research teams to build upon this foundation, contributing to the refinement of a robust and reliable method. Ultimately, this approach could support the development of a comprehensive test battery for detecting disruptions in thyroid hormone signaling.