Citation:

Tal, T. AND N. Kleinstreuer. Adverse Outcome Pathways for Embryonic Vascular Disruption and Alternative Methods to Identify Chemical Vascular Disruptor. Presented at Cardiovascular Risk Workshop, RTP, NC, October 10 - 11, 2013.

Impact/Purpose:

Chemically induced vascular toxicity during embryonic development can result in a wide range of adverse prenatal outcomes. We used information from genetic mouse models linked to phenotypic outcomes and a vascular toxicity knowledge base to construct an embryonic vascular disruption adverse outcome pathway (AOP).

Description:

Chemically induced vascular toxicity during embryonic development can result in a wide range of adverse prenatal outcomes. We used information from genetic mouse models linked to phenotypic outcomes and a vascular toxicity knowledge base to construct an embryonic vascular disruption adverse outcome pathway (AOP). The AOP was built based on molecular initiating events (MIEs) corresponding to genes from critical pathways (hypoxia/growth factor signaling, chemokine networks, extracellular matrix interactions and vessel remodeling/stabilization) with evidence of abnormal embryonic vascular development in the mammalian phenotype browsers of the Mouse Genome Informatics database (http://www.informatics.jax.org/). ToxCast high throughput screening (HTS) data for 25 assays mapping to targets in the AOP were used to prioritize >1000 chemicals for their potential to disrupt vascular development. A subset of 38 predicted vascular disrupting chemicals (pVDCs) or non-pVDCs were selected for targeted testing in zebrafish (D. rerio). To test computational predictions empirically, TG(flk1:GFP) zebrafish embryos were used to visualize and quantify blood vessel formation during development. Manual and automated methods of vessel quantification were developed, and the assay was evaluated with anti-angiogenic reference compounds PTK787 and AG1478, small molecule inhibitors of VEGFR2 and EGFR, respectively. The functional consequence of developmental vascular toxicity was assessed in larval and juvenile zebrafish. The assay was used to test the effects of 38 pVDCs and non-pVDCs including pesticides, flame retardants, and endocrine active compounds. The test chemicals were also evaluated in a functional angiogenesis assay comprised of a human endothelial cell and fibroblast co-culture system. Chemical rankings were well correlated among the predictive signature and zebrafish and in vitro tubulogenesis assays. Taken together, the zebrafish assay meets a critical need for an in vivo platform that can assess predictions generated by computational models of developmental vascular toxicity. This abstract does not necessarily reflect EPA policy. Keywords: Zebrafish, Vascular Toxicity, Developmental Toxicity, Adverse Outcome Pathway, Molecular Initiating Event

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