Monday, November 5, 2018

The appendix is implicated in Parkinson’s disease

Clumps of alpha-synuclein (red) in the appendix of a healthy individual suggests the possibility
that the gut plays a role in the pathogenesis of Parkinson disease
The appendix may contribute to a person’s chances of developing Parkinson’s disease. An analysis of data from nearly 1.7 million Swedes found that those who’d had their appendix removed had a lower overall risk of Parkinson’s disease. Also, samples of appendix tissue from healthy individuals revealed protein clumps similar to those found in the brains of Parkinson’s patients, researchers report online October 31 in Science Translational Medicine.

Together, the findings suggest that the appendix may play a role in the early events of Parkinson’s disease, Viviane Labrie, a neuroscientist at the Van Andel Research Institute in Grand Rapids, Mich., said at a news conference on October 30.

Symptoms related to Parkinson’s can show up in the gut earlier than they do in the brain. So Labrie and her colleagues turned their attention to the appendix. Often considered a “useless organ,” Labrie said, “the appendix is actually an immune tissue that’s responsible for sampling and monitoring pathogens.”

In the new study, Labrie’s team analyzed health records from a national registry of Swedish people, some of whom were followed for as many as 52 years. That long observation time was key: People have their appendix removed most often in their teens or 20s but, on average, don’t develop Parkinson’s disease until their 60s. More than half a million people in the registry had had an appendectomy, while a total of 2,252 people out of the 1.7 million developed Parkinson’s. Removing the appendix was associated with a 19 percent drop in the risk of developing Parkinson’s disease, the team reports.

Surgical samples from a tissue bank of appendixes from 48 people without Parkinson’s provided another link to the disease. The team discovered alpha-synuclein clumps in 46 of the samples — from both old and young patients — similar to those seen in the brains of Parkinson’s patients.

If the clumped protein in the appendix turns out to jump-start the disease, Labrie said, “preventing excessive alpha-synuclein clump formation in the appendix, and its departure from the gastrointestinal tract, could be a useful new form of therapy.”

Ongoing clinical trials are investigating different strategies to remove alpha-synuclein from the brain. If a new therapy could clear the protein from the brain, says UPenn neuropathologist John Trojanowski, perhaps it would do the same for the appendix.

B. Killinger et alThe vermiform appendix impacts the risk of developing Parkinson’s diseaseScience Translational Medicine. Published online October 31, 2018. doi:10.1126/scitranslmed.aar5280.

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