Endocrine Abstracts

The pathophysiology of human neurodevelopment entails complex interactions between individual genetic backgrounds and environmental exposures. Endocrine Disruptive Chemicals (EDCs), a heterogeneous class of compounds widely present in our environment, can interfere with human endocrine system and the effects of this exposure on the developing brain can cause adverse neurodevelopmental effects. As opposed to previous works focusing on single compounds, we studied an EDC mixture associated to language delay in a longitudinal pregnancy cohort study. We integrated the epidemiological results with in vitro molecular testing on human fetal neural progenitors, and cortical brain organoids (CBO). Transcriptomic analysis revealed that chronic exposure to the mixture altered genes related to epigenetic regulation, cell proliferation, and neuronal maturation. Moreover it down-regulated bona fide ASD-causing genes (annotated with the highest scores in the Simons Foundation Autism Research Initiative (SFARI) gene database), thus indicating that EDC exposure interferes with the same molecular targets implicated in the pathogenesis of ASD cases caused by genetic mutations. Experimental results were then used to determine that up to 54% of the investigated women exceeded exposure levels of concern, emphasizing the need to take mixtures into account for chemical testing, and providing an integrative framework to guide risk assessment (1). Building on that, we are deepening our investigation of causal links between endocrine pathways alteration and developmental neurotoxicity in the ENDpoiNTs project (https://endpoints.eu/), where we systematically exposed CBO to single compounds and mixtures of several hormones and EDCs, thus establishing a molecular and cellular atlas of endocrine impact on the developing human brain cortex. We also established a novel experimental platform to carry out high throughput developmental disease modelling and EDC exposure on CBO. We implemented and benchmarked a new strategy to multiplex CBO from multiple induced pluripotent stem cell lines (generating mosaic CBO), and leveraged single cell transcriptomics to deconvolve individual cell identity-using variant calling. We thus integrated our longitudinal (up to day 300 CBO) single cell datasets, where all the relevant clusters of neurodevelopmental cell populations were annotated and analysed, and we deeply characterised specific neuronal (excitatory and inhibitory lineages) and glial developmental trajectories. This work represents a unique resource for using brain organoids to perform disease modelling at scale, towards an in vitro epidemiology paradigm, for neurotoxicological studies on multiple genetic backgrounds.