Contribution of Immune Responses to the Cardiotoxicity and Hepatotoxicity of Deltamethrin in Early Life Stage Zebrafish (Danio rerio)

Deltamethrin (DM) is a widely used insecticide that has demonstrated developmental toxicity in the early life stages of fish. To better characterize the underlying mechanisms, embryos from Tg(cmlc2:RFP), Tg(apo14:GFP), and Tg(mpx:GFP) transgenic strains of zebrafish were exposed to nominal DM concentrations of 0.1, 1, 10, 25, and 50 μg/L until 120 h post-fertilization (hpf). Heart size increased 56.7%, and liver size was reduced by 17.1% in zebrafish exposed to 22.7 and 24.2 μg/L DM, respectively. RNA sequencing and bioinformatic analyses predicted that key biological processes affected by DM exposure were related to inflammatory responses. Expression of IL-1 protein was increased by 69.0% in the 24.4 μg/L DM treatment, and aggregation of neutrophils in cardiac and hepatic histologic sections was also observed. Coexposure to resatorvid, an anti-inflammatory agent, mitigated inflammatory responses and cardiac toxicity induced by DM and also restored liver biomass. Our data indicated a complex proinflammatory mechanism underlying DM-induced cardiotoxicity and hepatotoxicity which may be important for key events of adverse outcomes and associated risks of DM to early life stages of fish.