Objective: To investigate gut microbiota alterations in Parkinson’s disease (PD) along disease progression.

Background: Gut microbiota dysbiosis is considered a hallmark in PD¹. However, it is still unclear whether microbiota alterations represent a pathogenetic starting point or also a consequence of disease²

Method:

A first research line, using a transactional approach, compared faecal samples collected from 3 groups: PD patients at diagnosis “de-novo” PD(dnPD); advanced PD(advPD), defined by H&Y stage≥3 and/or LEED>850mg, and healthy controls (HC, cohabitants). The second research line followed longitudinally a cohort of dnPD for 2 years, divided into 2 groups: the “eubiotics” group and the “dysbiotics” one. 

Microbiota compositions was studied through 16rRNA amplicon sequencing and classified to taxonomic rank through bioinformatic analysis.

Results: In the transactional study, we compared samples from 30 dnPD, 38 advPD and 79 HC. The three groups differed both in alfa- and in beta-diversity comparisons. We observed a progressive reduction both in alfa and beta diversity moving from HC to dnPD to advPD. A progressive reduction in Bacteroidaceae, Lacnospiraceae, Family XIII, Prevotellaceae, Ruminococcaceae, Rikenellaceae families (from HC to dnPD and to advanced PD) was observed; whilst a reverse trend occurred for Enterobacteriaceae and Lactobacillaceae families. Likewise with genera, we found a progressive reduction in Roseburia, Lacnospira, Butyricicoccus, Faecalibacterium genus moving from HC to dnPD and to advPD and a reverse trend in Lactobacillus genus. In the longitudinal study, patients belonging to the “dysbiotic” group (n13) showed a faster and more severe disease progression.

Conclusion: Our study, asides from the presence of gut microbiota alterations in earliest PD stages, shows a more severe alteration as featuring PD advanced stages. According to our results, the progression of the PD seems to correlate, regarding gut microbiota with: progressive impoverishment of biodiversity, loss of homeostatic taxa and prevalence of pro-inflammatory Families.  Moreover, the presence of dysbiosis at the diagnosis correlates with a more rapid disease spectrum, including cognitive disorders over time. These findings candidate the dysbiosis of gut microbiota in PD, not only as biomarker of prodromal/early-stage, but also as a biomarker of disease progression and a negative prognostic factor.

References: [1] J.M. Boertien, P.A.B. Pereira, V.T.E. Aho, F. Scheperjans. Increasing Comparability and Utility of Gut Microbiome Studies in Parkinson’s Disease: A Systematic Review. Journal of Parkinson’s Disease 9 (2019) S297-S312. doi: 10.3233/JPD-191711.
[2] A. Keshavarzian, P Engen, S Bonvegna, R Cilia. The gut microbiome in Parkinson’s disease: A culprit or a bystander? Prog Brain Res. 252 (2020) 357-450. doi: 10.1016/bs.pbr.2020.01.004

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gut-microbiota-dysbiosis-in-parkinsons-disease-patients-a-potential-biomarker-of-disease-severity-and-progression/