A new study published in Nature has shown that a gut infection can lead to symptoms resembling Parkinson's in mice, suggesting that the immune system may play a more central role in the condition than previously thought.
In mice lacking a protein linked to Parkinson’s called PINK1, a bacterial infection in the gut triggered later problems with movement and reduced the amount of dopamine released in the brain.
Implicating the immune system
Mutations in genes such as PINK1 and Parkin are associated with rare inherited forms of Parkinson's. The proteins encoded in these genes play a role in the recycling of old mitochondria in the cell.
But recent evidence suggests that these proteins may also play a role in the immune cell response. Researchers discovered that changes in PINK1 and Parkin triggered an auto-immune response, where the immune system mistakenly attacks healthy cells.
Studies in mice
Looking in mice lacking the PINK1 gene, researchers at the University of Montreal found that a gut infection was enough to trigger Parkinson’s-like symptoms as the mice got older.
Following infection, and in the absence of PINK1, proteins from faulty mitochondria appeared on the cell surface and triggered an autoimmune response. The overactive immune cells were shown to reduce the amount of dopamine released in the brain and resulted in problems with mobility. These symptoms were temporarily reversed by treatment with the Parkinson’s drug, L-Dopa.
A new area of research
The groundbreaking findings suggest that some forms of Parkinson’s could be classified as an auto-immune condition, likely starting in the gut.
Dr Beckie Port, Research Communications Manager at Parkinson’s UK said:
"Currently we don't fully understand the causes of Parkinson's, but this study in mice helps us to better understand how genetics and the environment combine in Parkinson's risk. Further to this, these results add to growing evidence of the importance of gut health in the condition.
"Further research is needed to understand the implications of these results for people with Parkinson's. However, this promising new research could help pave the way for better treatments to slow, or even stop Parkinson's for good.”