Objective: Our goal was to evaluate, whether gut microbiota are altered in a Southern German PD cohort. In addition, we assessed changes in the microbiome in different disease stages and hypothesized that the microbiome of PD patients is altered already at an early disease stage. Furthermore, we tested whether initial changes persist at intermediate and late disease stages.

Background: Accumulating evidence suggests that alpha-synucleinopathy within the enteric nervous system (ENS) may be one of the initial sites for the premotor onset of Parkinson’s disease (PD). Altered gut microbiota may contribute to, or trigger the process of alpha-synuclein aggregation in the ENS. Changes in the gut microbiome have previously been observed in different North European study populations.

Method: Between November 2016 and June 2018, 176 subjects were screened, and 102 (71 patients, 31 controls) were subsequently enrolled. Motor symptoms were measured using part III of the Unified Parkinson’s Disease Rating Scale (UPDRS III) and disease staging followed the Hoehn & Yahr scale (H&Y). Severity of non-motor symptoms was assessed using the Non-Motor Symptoms Scale (NMS). The degree of constipation was assessed using the Wexner score. Participants collected fecal samples in a DNA stabilizing solution (Stool Collection Tubes with Stool DNA Stabilizer; Stratec ®, Stratec Molecular, Berlin, Germany). Total DNA was extracted from the samples. Polymerase chain reaction amplification and pyrosequencing of the V3 and V4 regions of the bacterial 16S ribosomal RNA gene was performed and used for taxonomic assignment.

Results: We analyzed the microbiome of 71 PD patients (mean age: 65.2±10.2; 45.1% females) and 31 controls (mean age: 64.3±8.9; 45.2% females). Our results indicate, that there is no change in alpha- or beta-diversity in the gut microbiome between groups. However, abundances of individual bacterial families, such as Lactobacillaceae, Sutterellaceae, and Enterobactericeace differ between disease stages and controls. On the genus level, abundances of Citrobacter and Lactobacillus were significantly altered, particularly at H&Y IV.

Conclusion: Distinct bacterial families may be altered at early PD stages. Thus, specific bacterial families may contribute to an altered micromilieu, favoring alpha-synuclein aggregation early in the course of PD. At later stages, alterations in other bacterial families may rather be related to non-motor symptoms like constipation.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gastrointestinal-microbiome-in-parkinsons-disease-in-a-bavarian-cohort/