Substantiate a read-across hypothesis by using transcriptome data—A case study on volatile diketones

Frontiers in Toxicology, vol. 5, pp. 1155645

Abstract

This case study explores the applicability of transcriptome data to characterize a common mechanism of action within groups of short-chain aliphatic α-, β-, and γ-diketones. Human reference in vivo data indicate that the α-diketone diacetyl induces bronchiolitis obliterans in workers involved in the preparation of microwave popcorn. The other three α-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®. 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 α- and β-diketones are more active compared to γ-diketones. α-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 α-diketones showed very similar results with regard to the number of activated and shared pathways. Overall, the number of signaling pathways decreased from α-to β-to γ-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.

Authors 11

1. Matthias M. Wehr

   Fraunhofer Institute for Toxicology and Experimental Medicine

   Affiliation as printed

   Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany

2. Walter Zobl

   Fraunhofer Institute for Toxicology and Experimental Medicine

   Affiliation as printed

   Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany

3. Jeannette Koschmann

   GeneXplain (Germany)

   Affiliation as printed

   GeneXplain GmbH, Wolfenbüttel, Germany

4. Britta Anna Kühne

   Fraunhofer Institute for Toxicology and Experimental Medicine

   Affiliation as printed

   Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany

5. Tanja Hansen

   Fraunhofer Institute for Toxicology and Experimental Medicine

   Affiliation as printed

   Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany

6. Jan Knebel

   Fraunhofer Institute for Toxicology and Experimental Medicine

   Affiliation as printed

   Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany

7. Detlef G. Ritter

   Fraunhofer Institute for Toxicology and Experimental Medicine

   Affiliation as printed

   Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany

8. Jan Boei Aachen

   Leiden University Medical Center

   Affiliation as printed

   Leiden University Medical Center, Leiden, Netherlands

9. Harry Vrieling Aachen

   Leiden University Medical Center

   Affiliation as printed

   Leiden University Medical Center, Leiden, Netherlands

10. Annette Bitsch

    Fraunhofer Institute for Toxicology and Experimental Medicine

    Affiliation as printed

    Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany

11. Sylvia E. Escher

    Fraunhofer Institute for Toxicology and Experimental Medicine

    Affiliation as printed

    Fraunhofer Institute for Toxicology and Experimental Medicine, Chemical Safety and Toxicology, Hannover, Germany