PPARγ mediated lysosomal membrane permeabilization and lipophagy blockage were involved in microplastics and di (2-ethylhexyl) phthalate co-exposure induced immature testis injury

Polystyrene microplastics (PS-MPs) and di (2-ethylhexyl) phthalate (DEHP), two main composites of plastic products, are always exposed to human at the same time. However, most existing research has focused on single exposure, which is not consistent with the actual exposure circumstance. In this study, single and co-exposure animal model were established. C57/BL6J mice were exposed to corn oil, 20 mg/kg PS-MPs, 200 mg/kg DEHP and PS-MPs + DEHP for 28 days. The HE staining showed more serious seminiferous epithelium disorganization in co-exposed mice, indicating that PS-MPs and DEHP co-exposure could aggravate testicular injury. Compared with control group, integrative analysis of transcriptomics and proteomics revealed that PPARγ pathway played a crucial role in PS-MPs and DEHP co-exposure induced testis injury. In vitro, spermatocytes (GC-2) and leydig cells (TM3) were exposed to 50 μM MEHP, 10 mg/L PS-MPs and PS-MPs + MEHP for 48 h. Though PS-MPs and MEHP single exposure also triggered oxidative stress and PPAR pathway, the protein levels showed more remarkable difference in co-exposure group. Furthermore, co-exposure to PS-MPs and MEHP induced lysosomal membrane permeabilization (LMP), which significantly impaired lysosomal-mediated lipid degradation, thereby exacerbating lipid metabolism dysfunction in testicular cells. Treatment with N-Acetylcysteine (NAC) and knockdown of fatty acid-binding protein (FABP4) restored lipophagy flux and reduced lipid droplets deposition. Overall, co-exposure of PS-MPs and DEHP has synergistic toxic effect, inducing oxidative stress, PPARγ activation and lipophagy blockage, finally resulting in unbalanced lipid metabolism and testicular damage.