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Screening for angiogenic inhibitors in zebrafish to evaluate a predictive model for developmental vascular toxicity
Citation:
Tal, T., C. Kilty, A. Smith, C. LaLone, B. Kennedy, A. Tennant, C. McCollum, M. Bondesson, T. Knudsen, S. Padilla, AND N. Kleinstreuer. Screening for angiogenic inhibitors in zebrafish to evaluate a predictive model for developmental vascular toxicity. REPRODUCTIVE TOXICOLOGY. Elsevier Science Ltd, New York, NY, 70:70-81, (2017).
Impact/Purpose:
Development of the cardiovascular system is required for normal development and is susceptible to perturbation by drugs or chemicals. Because we lack vascular-specific toxicity data for most environmental chemicals, the pVDC signature was used to characterize the ToxCast chemical inventory based on a subset of human in vitro HTS assays that measure endpoints relevant to blood vessel development. This HTS approach does not account for in vivo factors like absorption, distribution, metabolism, elimination, and blood flow/shear stress that can influence toxicity. Nor does it include key signaling pathways that control developmental angiogenesis like canonical wnt and BMP signaling, simply because there are no ToxCast assay data available for these pathways. Despite these caveats, the pVDC signature is a crucial tool that enables rank ordering of a diverse chemical space for which no vascular-specific toxicity data exists. This study was performed to evaluate computational toxicology predictions derived from the pVDC signature in an in vivo experimental system and ultimately, to refine a predictive signature of developmental toxicity derived from human HTS in vitro data.The zebrafish model contains regional specification of blood vessel networks that are representative of vascular architecture in higher order vertebrates. This research has filled a critical need for an integrated in vivo platform that can identify HTS assays predictive of vascular toxicity in vivo and thus be used to evaluate a pathway-level model predictive of developmental vascular toxicity. In addition to supporting model validation, zebrafish data can refine the pVDC signature by adding novel HTS assays that are highly correlated with in vivo vascular toxicity.
Description:
Chemically-induced vascular toxicity during embryonic development may cause a wide range of adverse effects. To identify putative vascular disrupting chemicals (pVDCs), a predictive signature was constructed from U.S. EPA ToxCast high-throughput screening (HTS) assays that map to molecular initiating events (MIEs) associated with altered cytokine, extracellular matrix (ECM), angiogenic, and vessel stabilization pathways. Termed the pVDC signature, the predictive tool contains 124 assays used to rank 1060 chemicals for their potential to disrupt vascular development. A subset of 37 pVDCs or non-pVDCs were selected for targeted testing in zebrafish embryos. Transgenic Tg(kdrl:EGFP) and Tg(fli1:EGFP) lines were used to visualize and quantify blood vessel formation during development following chemical exposures. Due to conservation of MIEs when compared to humans, we hypothesized that zebrafish vascular toxicity data would correlate with human cell-based and cell-free in vitro HTS ToxCast data. Univariate statistical associations used to filter HTS data based on correlations with zebrafish vascular toxicity in vivo revealed 132 total significant associations, 33 of which were already captured in the pVDC signature, and 689 non-significant assay associations. Correlated assays were enriched in cytokine and ECM pathways. Signature refinements were proposed including the addition of primary endothelial cell death assays and an X-box binding protein 1 assay that serves as a proxy measurement for flow-mediated vessel patterning. Taken together, the findings indicate the utility of in vivo zebrafish assays to refine a pathway based predictive model of developmental vascular toxicity.
