This case study explores the applicability of transcriptome data to characterize a common mechanism of action within groups of short-chain aliphatic alpha-, beta-, and gamma-diketones. Human... Show moreThis case study explores the applicability of transcriptome data to characterize a common mechanism of action within groups of short-chain aliphatic alpha-, beta-, and gamma-diketones. Human reference in vivo data indicate that the alpha-diketone diacetyl induces bronchiolitis obliterans in workers involved in the preparation of microwave popcorn. The other three alpha-diketones induced inflammatory responses in preclinical in vivo animal studies, whereas beta and gamma diketones in addition caused neuronal effects. We investigated early transcriptional responses in primary human bronchiolar (PBEC) cell cultures after 24 h and 72 h of air-liquid exposure. Differentially expressed genes (DEGs) were assessed based on transcriptome data generated with the EUToxRisk gene panel of Temp-O-Seq (R). For each individual substance, genes were identified displaying a consistent differential expression across dose and exposure duration. The log fold change values of the DEG profiles indicate that alpha- and beta-diketones are more active compared to gamma-diketones. alpha-diketones in particular showed a highly concordant expression pattern, which may serve as a first indication of the shared mode of action. In order to gain a better mechanistic understanding, the resultant DEGs were submitted to a pathway analysis using ConsensusPathDB. The four alpha-diketones showed very similar results with regard to the number of activated and shared pathways. Overall, the number of signaling pathways decreased from alpha-to beta-to gamma-diketones. Additionally, we reconstructed networks of genes that interact with one another and are associated with different adverse outcomes such as fibrosis, inflammation or apoptosis using the TRANSPATH-database. Transcription factor enrichment and upstream analyses with the geneXplain platform revealed highly interacting gene products (called master regulators, MRs) per case study compound. The mapping of the resultant MRs on the reconstructed networks, visualized similar gene regulation with regard to fibrosis, inflammation and apoptosis. This analysis showed that transcriptome data can strengthen the similarity assessment of compounds, which is of particular importance, e.g., in read-across approaches. It is one important step towards grouping of compounds based on biological profiles. Show less
Chemical-induced organ toxicity is a major concern in the development and use of chemicals, including drugs, pesticides, industrial chemicals and cosmetics. In the last decades, the onset and... Show moreChemical-induced organ toxicity is a major concern in the development and use of chemicals, including drugs, pesticides, industrial chemicals and cosmetics. In the last decades, the onset and progression of chemical-induced organ toxicity has been linked amongst others to perturbation of mitochondria.In this work, we set out to further unravel the mechanisms behind mitochondrial toxicity initiated by a chemical insult. More in-depth and biology driven assessment of the onset and progression of mitochondrial perturbation supports the development of relevant prediction tools. We aimed to stimulate the integration of these in vitro and in silico prediction tools in the safety assessment of existing and new chemicals, to allow detailed assessment of mitochondrial fitness upon chemical exposure. Show less
