johnt said:
"A paper [1] by Sampson et al, which is behind a paywall, has some interesting findings.
...
[1] Gut Microbiota Regulate Motor Deficits and Neuroinflammation in a Model of Parkinson’s Disease, Timothy R. Sampson et al. Cell, Dec 2016."

This may turn out to be a significant paper. It was published late last year, but already has more than 30 citations. Two of these (so far) have caught my attention.

The first one is a brief article giving an overview of the paper. The following sentence stood out: "The authors think that molecules made by gut microbes could activate certain immune cells and boost inflammation in general, which then enhances the clumping of α-synuclein in the brain."

Microbiology: Gut bacteria linked to Parkinson'''s : Nature : Nature Research

The second one is actually a couple of comments on a website called PubPeer. The comments (from users "Unregistered Submission" and "Peer 2") are particularly critical of the quality of the statistical analysis that has been done. They sound to me like they know what they are talking about, but for some reason they have chosen to remain anonymous, and have chosen the PubPeer website rather than PubMed Commons.

PubPeer - Gut Microbiota Regulate Motor Deficits and Neuroinflammation in a Model of Parkinson?s Disease