Co-exposure of cadmium and polystyrene nanoplastics: Induction pyroptosis and autophagy in mice testis

PURPOSE: Cadmium (Cd) and polystyrene nanoplastics (PSNPs) are prevalent common environmental contaminants hat can accumulate in animal and human tissues through the food chain. This study aimed to investigate the toxic effects of Cd and/or PSNPs on mouse testicular tissue and to focus on the interplay between pyroptosis and autophagy in mediating this toxicity. METHODS: In a long-term toxicological study, male C57BL/6 mice was exposed to 1.5 mg/kg Cd, 1 mg/kg PSNPs (the environmentally relevant dose), or a combination of both for thirty-five days. After exposure, testicular tissues were analyzed for damage, as well as alterations in pyroptosis- and autophagy-related gene and protein expressions. To further examine the direct interplay between pyroptosis and autophagy, TM4 cells were treated for 24 h with 60 μg/mL PSNPs, 3 μM Cd, 60 μM ac-YVAD-CMK (YVAD; a pyroptosis inhibitor), and 2.5 μM 3-methyladenine (3-MA; an autophagy inhibitor), either alone or in combination. RESULTS: The results indicated substantial testicular injury in mice exposed to Cd and/or PSNPs, with co-exposure producing more pronounced toxicity than single-agent treatment. Both Cd and PSNPs altered the expression of genes and proteins implicated in pyroptosis and autophagy. In TM4 cells, pyroptosis and autophagy induced by Cd and PSNPs were closely interconnected. Specifically, inhibition of autophagy by 3-MA exacerbated pyroptosis, while inhibition of pyroptosis by YVAD attenuated the autophagic response to Cd and PSNPs exposure. In conclusion, co-exposure to Cd and PSNPs exacerbates testicular damage in mice compared to single exposures, a process regulated by the intricate cross-talk between pyroptosis and autophagy.