Targeted RNA-seq (TempO-Seq) of temporal concentration responses to cosmetic ingredients exposures in PHH and HepaRG cells
For the purpose of mechanism-based risk assessment, we investigated temporal concentration-dependent responses in cultures of PHH and HepaRG cells exposed to three cosmetics ingredients, 2,7-naphthalenediol (NPT), triclosan (TCS) and butylated hydroxytoluene (BHT), that are suspected to have liver injury liability. To facilitate the identification of early KEs and visualisation of their development over time, samples were collected at 4 time points, namely 8 and 24 hours (single exposure), 48 and 72 hours (daily repeated exposure), after exposure to a broad concentration range. Concentrations were selected based on the estimated Cmax of the cosmetic ingredients. The selected maximum concentration was set at approximately 100x Cmax, whilst the minimum tested concentration was approximately 0.2x Cmax. The large concentration range allowed to apply benchmark concentration (BMC) modelling on individual genes as well as gene co-expression networks to derive in vitro transcriptomics benchmark concentrations (BMCs) and assess their suitability to be used as PoD in chemical risk assessment.