Combining in vitro assays and mathematical modelling to study developmental neurotoxicity induced by chemical mixtures

• Published in: Reproductive toxicology (Elmsford, N.Y.) Vol. 105; pp. 101 - 119
• Main Authors: Pistollato, Francesca, Carpi, Donatella, Mendoza-de Gyves, Emilio, Paini, Alicia, Bopp, Stephanie K., Worth, Andrew, Bal-Price, Anna
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2021; Pergamon In Cooperation With The Reproductive Toxicology Center
• Subjects: Adverse outcome pathway; Astrocytes - drug effects; Benzhydryl Compounds - toxicity; Biological Assay; Brain-Derived Neurotrophic Factor - metabolism; Cell Differentiation; Cell Survival - drug effects; Cells, Cultured; Children’s health; Chlorpyrifos - toxicity; Combined toxicity; Ethanol - toxicity; Halogenated Diphenyl Ethers - toxicity; Human induced pluripotent stem cells; Humans; Induced Pluripotent Stem Cells - cytology; Lead - toxicity; Mathematical modelling; Methylmercury Compounds - toxicity; Mixture risk assessment; Models, Theoretical; Neural Stem Cells - cytology; Neuronal differentiation; Neurons - drug effects; Neurotoxicity Syndromes; Oxazoles - toxicity; Phenols - toxicity; Polychlorinated Biphenyls - toxicity; Polychlorinated Dibenzodioxins - toxicity; Valproic Acid - toxicity; Mixture risk assessment; Combined toxicity; Human induced pluripotent stem cells; Neuronal differentiation; Mathematical modelling; Adverse outcome pathway; Children’s health
• ISSN: 0890-6238; 1873-1708
• DOI: 10.1016/j.reprotox.2021.08.007

•Mixtures of similar MoA chemicals increased BDNF levels and neurite outgrowth.•Mixtures of similar MoA chemicals decreased synapse formation and electrical activity.•Synergistic effects on synaptogenesis features was predicted by mathematical modelling.•Some of the DNT effects observed in hiPSC-neurons/astrocytes recapitulate ASD features.•In vitro assays combined with mathematical modelling enable DNT testing of chemical mixtures. Prenatal and postnatal co-exposure to multiple chemicals at the same time may have deleterious effects on the developing nervous system. We previously showed that chemicals acting through similar mode of action (MoA) and grouped based on perturbation of brain derived neurotrophic factor (BDNF), induced greater neurotoxic effects on human induced pluripotent stem cell (hiPSC)-derived neurons and astrocytes compared to chemicals with dissimilar MoA. Here we assessed the effects of repeated dose (14 days) treatments with mixtures containing the six chemicals tested in our previous study (Bisphenol A, Chlorpyrifos, Lead(II) chloride, Methylmercury chloride, PCB138 and Valproic acid) along with 2,2′4,4′-tetrabromodiphenyl ether (BDE47), Ethanol, Vinclozolin and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)), on hiPSC-derived neural stem cells undergoing differentiation toward mixed neurons/astrocytes up to 21 days. Similar MoA chemicals in mixtures caused an increase of BDNF levels and neurite outgrowth, and a decrease of synapse formation, which led to inhibition of electrical activity. Perturbations of these endpoints are described as common key events in adverse outcome pathways (AOPs) specific for DNT. When compared with mixtures tested in our previous study, adding similarly acting chemicals (BDE47 and EtOH) to the mixture resulted in a stronger downregulation of synapses. A synergistic effect on some synaptogenesis-related features (PSD95 in particular) was hypothesized upon treatment with tested mixtures, as indicated by mathematical modelling. Our findings confirm that the use of human iPSC-derived mixed neuronal/glial models applied to a battery of in vitro assays anchored to key events in DNT AOP networks, combined with mathematical modelling, is a suitable testing strategy to assess in vitro DNT induced by chemical mixtures.