Kerkhof, Engelien et al. (2015) International Worm Meeting "C. elegans as robust, high throughput in vivo system for hazard assessment."

Pieters, Raymond, Wildwater, Marjolein, Kerkhof, Engelien, Lokman, Christien

[International Worm Meeting, 2015]

Innovative toxicity test systems that enable identification of adverse outcome pathways (AOP) relevant for humans, are highly interesting to allow improved hazard identification and characterization. The nematode Caenorhabditis elegans (C. elegans) has been thoroughly established as a developmental biological test system and shows a high level of conserved molecular pathways and cellular mechanisms compared to man. The behavior of the 959 somatic cells of which the hermaphrodite nematode exists have been mapped in detail. The nematode transparency, short turnover time, small size, conserved organs, high throughput screening ability and the available technological resources allow rapid, reproducible testing of compounds and easy identification of AOPs and molecular initiating events (MIE). Furthermore, in the view of developmental and reproductive toxicology (DART) which is amongst the most difficult toxicological outcomes to assess, and which requires the highest numbers of vertebrates for testing, C. elegans can be a suitable alternative test system as it has a full life cycle. We have tested 22 well documented and well characterized DART compounds from the ECHA, Staatscourant and EPA list and show that the C. elegans test model has a predictive value of ~80% for DART related compounds, indicating the suitability of the C. elegans test system for DART assessment. To understand AOPs underlying DART toxicity in C. elegans, a RNA-sequencing approach was followed. RNA sequencing showed alterations in gene expression profiles of genes orthologous to humans. Data analysis consisted of community based profiling and a posttranscriptional gene silencing approach (RNAi). Two individual genome wide RNAi libraries are available in C. elegans that allow down regulation of gene expression of most genes in the C. elegans genome. If particular up regulated genes (identified by RNA-sequencing) are critically responsible for DART effects, posttranscriptional gene silencing by RNAi should reduce the DART effects, thus enabling the identification of critical AOP genes. Alternatively, community based alignment of DART responses enables the identification of global gene expression patterns responsive to DART effects.