Adolescent exposure to polystyrene nanoplastics induces male reproductive damage via the microbiome-gut-testis axis.

Polystyrene nanoplastics (PS-NPs), are increasingly associated with reduced male fertility, yet the underlying mechanisms remain poorly defined. Here, we systematically unraveled a novel microbiome-gut-testis axis mediating PS-NPs-induced reproductive toxicity. Adolescent rats exposed to PS-NPs for 5 weeks induced dose-dependent testicular injury, characterized by disrupted spermatogenesis, and compromised blood-testis barrier. Single-cell atlases revealed spermatogenic arrest, abnormal immune microenvironment, and perturbed testicular cell communication upon exposure to PS-NPs. Furthermore, multi-omics analysis highlighted the activation of NF-κB/IL-17/HIF-1 and inhibition of PPAR-γ signaling, contributing to increased DNA damage and apoptosis, suppressed autophagy, and dysregulated energy-lipid metabolism. Additionally, PS-NPs exposure initiated gut microbial dysbiosis, significantly increasing pro-inflammatory bacteria, while reducing beneficial commensals. This microbial disruption compromised intestinal barrier integrity, leading to elevated circulating LPS levels. Subsequent activation of the TLR4/MyD88/NF-κB signaling pathway propagated inflammatory responses to testes. Crucially, FMT from PS-NPs-exposed donors reproduced the damage in healthy recipients, thus suggesting gut microbiota as a causal mediator. Therapeutically, DI intervention effectively mitigated the reproductive toxicity by restoring gut barrier integrity, rebalancing microbial communities, and suppressing inflammation. Our findings unveil a gut microbiome-centric mechanism for nanoplastic-induced male reproductive toxicity, and identify DI as a promising therapeutic candidate, accordingly providing critical insights for environmental risk assessment.