Polystyrene Nanoplastics and Cadmium Co-Exposure Accelerates Mitochondrial Autophagy Mediated by HSP60–SIRT3–SOD ₂ Signaling Pathway in Primary Duck Embryo Hepatocytes

Microplastics (MPs) in the environment frequently act as a medium to adsorb heavy metals and antibiotics. This combined exposure often has a greater effect on animal toxicity than exposure alone. However, there is a paucity of research focusing on the combined toxicity of nanoplastics (NPs) and heavy metals when coexposed to hepatocytes in poultry. In this study, the effects of PS-NPs (0.08 μm, 10 μg/mL) and cadmium chloride (CdCl₂) (4 μg/mL) on duck hepatocytes and their mechanisms were observed using primary duck embryo hepatocytes (PDEH) cells as an in vitro model. The results demonstrated that Cd exposure exacerbated the accumulation of PS-NPs in PDEH cells, likely due to the formation of pores on the cell membrane surface. The addition of the antioxidant <i>N</i>-Acetyl-l-cysteine (NAC) significantly reduced the uptake of PS-NPs by PDEH cells. PDEH cells in the coexposed group exhibited significantly abnormal morphology and diminished cell number and survival rate. Furthermore, exposure to PS-NPs exacerbated Cd-mediated oxidative stress and mitochondrial autophagy damage in duck hepatocytes. The restoration of these injuries was observed in response to intervention with the SIRT3 activator (NRCL, 2 ng/mL). Immunoprecipitation experiments demonstrated that the SIRT3 protein interacted with the SOD₂ protein. The present study found that co-exposure of PS-NPs+Cd induced mitochondrial autophagy in PDEH cells, which may be mediated by the HSP60/SIRT3/SOD₂ signaling axis. It is hoped that these findings will provide new ideas for combating the mechanism of microplastics and Cd-induced hepatotoxicity in poultry.