Polystyrene Nanoplastics Hitch-Hike the Gut–Brain Axis to Exacerbate Parkinson’s Pathology

The neurological implications of micro- and nanoplastic exposure have recently come under scrutiny due to the environmental prevalence of these synthetic materials. Parkinson's disease (PD) is a major neurological disorder clinically characterized by intracellular Lewy-body inclusions and dopaminergic neuronal death. These pathological hallmarks of PD, according to Braak's hypothesis, are mediated by the afferent propagation of α synuclein (αS) via the enteric nervous system, or the so-called gut-brain axis. Here we first examined the effect of enteric exposure to polystyrene nanoplastics on the peripheral and central pathogenesis of A53T, a representative αS mutant. Specifically, the polystyrene nanoplastics accelerated the amyloid aggregation of A53T αS, which subsequently elevated the in vitro production of glial activation biomarkers, cytokines, and reactive oxygen species and compromised mitochondrial and lysosomal membrane integrity, further shifting cellular metabolite profiles in association with PD pathophysiology. In vivo, coadministration of the polystyrene nanoplastics and A53T αS facilitated their synergistic gut-to-brain transmission in mice, leading to progressive impairment of physical and motor skills in resemblance to characteristic PD symptoms. This study provides insights into the response and vulnerability of Parkinson's gut-brain axis to polystyrene nanoplastics.