Crosstalk between histological alterations, oxidative stress and immune aberrations of the emerging PFOS alternative OBS in developing zebrafish

Abstract

Sodium p-perfluorous nonenoxybenzene sulfonate (OBS) has been widely applied as a novel PFOS alternative in many industrial fields. However, our knowledge about its toxic effects is limited. In this study, the toxicities of PFOS and OBS in zebrafish larvae were compared by examining their effects on histology, oxidative stress and immune responses. Mortality and malformations caused by OBS were lower than those caused by PFOS under the same exposure concentrations. However, both PFOS and OBS caused histological alterations, manifesting in somatic striated muscle cell necrosis and a reduction in intestinal fold height, respectively. Significant increases in MDA and ROS content were observed in the PFOS and OBS treatment groups, respectively, suggesting the occurrence of oxidative stress in the zebrafish larvae. Furthermore, the transcriptomic and qRT-PCR results showed that the expression of most immune-related genes was upregulated in both PFOS and OBS treatment groups, but the latter was to a lesser extent. Consistent with their mRNA expression, the expression of the IL-1β, CXCL8, MMP9 and Casp8 proteins was significantly elevated following OBS exposure. However, the expression of these proteins was not affected by PFOS, possibly because the translation process was severely disrupted. Collectively, both OBS and PFOS could induce oxidative stress and inflammatory responses in zebrafish larvae. Our findings highlight that the health risks of OBS as a substitute for PFOS should not be ignored.