Dietary fibre and bacterial curli in mouse PD model. Dietary fibre deprivation and bacterial curli exposure shift gut microbiome and exacerbate Parkinson’s disease-like pathologies in an alpha-synuclein-overexpressing mouse

The microbiome-gut-brain axis has been proposed as a pathogenic path in Parkinson’s disease (PD). Dietary driven dysbiosis and reduced gut barrier function could facilitate the interaction of toxic external or internal factors with the enteric nervous system, where PD could start. Amyloid bacterial protein such as curli can act as seed to corrupt enteric α-synuclein and lead to its aggregation. Misfolded α-synuclein can propagate to and throughout the brain. Here, we aimed at understanding if fibre deprivation and amyloidogenic protein curli could, individually or together, exacerbate the phenotype in both enteric and central nervous systems of a transgenic mouse overexpressing wild-type human α-synuclein. We analysed the gut microbiome, motor behaviour, gastrointestinal and brain pathologies in these mice. Our findings show that external interventions, akin to unhealthy life habits in humans, can exacerbate PD-like pathologies in mice. We believe that our results shed light on how lifestyle affects PD progression.