Written by Charlotte Harrison, Science Writer.
A study led by researchers from the University of Helsinki indicates that Desulfovibrio bacteria are a likely cause of Parkinson’s disease (PD) in a worm model. The study adds to growing evidence for the role of bacteria in the pathogenesis of PD, and if the findings are mirrored in humans, eliminating the bacteria might one day be used to slow or halt PD.
The authors used a Caenorhabditis elegans model expressing a fluorescent form of human α-synuclein, the neuronal protein that is a pathogenic hallmark of PD. The worms were fed strains of Desulfovibrio bacteria isolated from PD patients and healthy individuals.
Worms were imaged using confocal microscopy to detect α-synuclein aggregation.
The researchers showed that Desulfovibrio bacteria, especially those from PD patients, enhanced the aggregation of α-synuclein. Worms fed Desulfovibrio bacteria from PD patients had more α-synuclein aggregates, and the aggregates were larger than worms fed Desulfovibrio bacteria from healthy individuals or worms fed control E. coli strains.
Additionally, worms fed Desulfovibrio bacteria from PD patients were more likely to die than worms fed control E. coli.
How might Desulfovibrio bacteria contribute to PD pathogenesis? The researchers suggest that the Desulfovibrio bacteria damage the function of the intestinal barrier, allowing interactions between intestine cells and surrounding cells, such as enteroendocrine cells. In this way, α-synuclein pathology could spread from the gut to the brain via the vagus nerve.
The study found that Desulfovibrio bacteria from healthy people also caused α-synuclein aggregation, albeit not as severe as PD-derived bacteria. This finding led the authors to suggest that all Desulfovibrio strains share common features, but those from PD patients have greater virulence. Here the authors note that future comparative genomic studies will shed light on the genetic differences underlying specific Desulfovibrio strains andtraits.
Overall, this study shows that Desulfovibrio bacteria contribute to PD pathogenesis by inducing α-synuclein aggregation, a finding that could have therapeutic implications.
“Our findings make it possible to screen for the carriers of these harmful Desulfovibrio bacteria. Consequently, they can be targeted by measures to remove these strains from the gut, potentially alleviating and slowing the symptoms of patients with Parkinson’s disease,” said author Per Saris in a press release.