Polystyrene microplastics induce apoptosis and necroptosis in swine testis cells via <scp>ROS</scp>/<scp>MAPK</scp>/<scp>HIF1α</scp> pathway

Microplastics (MPs) generally refer to the plastic fragments or particles smaller than 5 mm in diameter, which are closely concerned due to their widespread presence in the environment. Recent studies have shown that MPs have a serious threat on the reproductive health of organisms. Pigs are often selected as the model animals because of their high similarity to human tissues and organs. However, there are no reports on the effects and mechanisms of MPs exposure on swine germ cells. In the present study, we established swine testis (ST) cell models exposed to 250, 500, and 1000 μg/ml polystyrene microplastics (PS-MPs, 1-10 μm), respectively. The findings revealed that PS-MPs reduced cell viability dose-dependently. Acridine orange/ethidium bromide staining and flow cytometry results indicated the occurrence of apoptosis and necrosis in ST cells under PS-MPs exposure, and the expression changes of relevant marker genes (B-cell lymphoma-2, Bcl-2 Associated X, Caspase-3, Caspase-9, Receptor-interacting protein kinase 1, Receptor-interacting protein kinase 3, Mixed lineage kinase domain-like, and Caspase-8) were clarified via quantitative real-time PCR and western blot. Further mechanistic studies found that PS-MPs treatment induced excessive intracellular reactive oxygen species (ROS) production, which promoted the phosphorylation of mitogen-activated protein kinase (MAPK) pathway-related genes (P38, c-Jun N-terminal kinase, extracellular regulated protein kinases) and activated the downstream gene hypoxia-inducible factor (HIF1α). In conclusion, our study suggests that PS-MPs treatment causes apoptosis and necroptosis in ST cells via ROS/MAPK/HIF1α signaling pathway.