The impact of endocrine-disrupting chemicals on oxidative stress and innate immune response in zebrafish embryos

Bisphenol A (BPA) and nonylphenol (NP) are well known endocrine-disrupting chemicals (EDCs) ubiquitous in the aquatic environment and are an ecotoxicological risk for the health of aquatic organisms. Limited attention has been given to the immunotoxicity of these chemicals. The present study revealed a concentration-dependent increase of reactive oxygen species content and an induced expression of redox-sensitive transcription factors in zebrafish embryos after exposure to various concentrations of BPA, NP, and BPA/NP mixture for 4 h to 168 h postfertilization. Transcription of genes related to the immune response, including IFNγ, IL1β, IL10, Mx, TNFα, CC-chemokine, and CXCL-clc, were significantly up-regulated on exposure to EDCs. A significant induction of concentrations of proinflammatory mediator, nitric oxide, accompanied by an increase in the activity of nitric oxide synthase (NOS) and an upregulation of inducible NOS gene expression, was detected in zebrafish embryos on exposures to EDCs. To elucidate the potential mechanisms by which BPA and NP activate the innate immune response, expression profiles of genes related to the Toll-like receptors (TLRs) signaling pathway were examined. Expressions of TLR3, TRIF, MyD88, SARM, IRAK4, and TRAF6 were altered on exposure to EDCs. The authors' results demonstrate that exposure to BPA and NP significantly affects the expression of genes related to immune response in zebrafish embryos following oxidative stress.