Polystyrene (PS) is one of the most widely used microplastics (MPs) globally. However, the neurotoxicity mechanisms triggered by polystyrene microplastics (PS-MPs) have yet to be elucidated. This study explored the damage induced by PS-MPs to the intestinal and central nervous system (CNS) and the potential mechanism. The results showed that PS-MPs exhibited size-dependent bioaccumulation with enhanced barrier penetration at submicron scales (500 nm > 1 μm ≫ 5 μm). Paradoxically, 1 μm PS-MPs demonstrated maximum neuroinflammation despite inferior biodistribution to 500 nm particles. Mechanistically, both sizes induce gut dysbiosis-mediated barrier disruption, elevating circulatory LPS that translocates across compromised BBB. This triggers excessive activation of the TLR4/MyD88/NF-κB pathway, subsequently inducing a surge in pro-inflammatory cytokines, ultimately leading to synaptic lesions in the hippocampal region. Our findings established smaller PS-MPs (≤1 μm) as latent neurodegeneration risk factors, demanding urgent assessment of chronic exposure consequences.
Yuan et al. (Wed,) studied this question.