Parkinson’s & Metagenomics

Results of a large-scale metagenomic analysis of the intestinal microbiome among people with Parkinson’s disease (PD) were recently published in Nature Communications. Deep shotgun metagenomic sequencing was conducted on samples from 234 neurologically healthy controls and 490 persons with PD. It’s worth noting that this study was initiated in response to a growing evidence base supporting a gut origin for some cases of PD; specifically, enteric nerves are suspected to be the initial site of PD pathology, which later spreads to the brain. This has been supported by animal evidence, and may be reflected by the early onset of symptoms such as constipation and postprandial fullness which precede motor symptoms by decades.

This recent study, the largest dataset to be published to date, suggests widespread dysbiosis in the PD microbiome, with over 30% of species, genes and pathways tested varying from the microbiome among healthy controls. Some of the highlights include the enrichment of the phylum Firmicutes and depletion of the genus Prevotella, though alterations in the abundance of 84 different bacterial species were found. This included elevations in Bifidobacterium dentium by 7-fold, Actinomyces oris by 6.5-fold, and Streptococcus mutans by 6-fold among PD participants, and reductions of Roseburia intestinalis by 7.5-fold and Blautia wexlerae by 5-fold. Reductions were also observed for short-chain fatty acid-producing bacteria, including Faecalibacterium prausnitzii. Additionally, hundreds of metabolic pathways were analyzed, with between 1/3 to 2/3 found to be dysregulated among those with PD. This study is an important stepping stone to potentially manipulating the microbiome, perhaps allowing for early prevention of this progressive disease.