Background
The gut microbiome and its metabolites can impact brain health and are altered in Parkinson's disease (PD) patients. It has been recently demonstrated that PD patients have reduced fecal levels of the potent epigenetic modulator butyrate and its bacterial producers. Here, we investigate whether the changes in the gut microbiome and associated metabolites are linked to PD symptoms and epigenetic markers in leucocytes and neurons.
Methods
Stool, whole blood samples, and clinical data were collected from 55 PD patients and 55 controls. We performed DNA methylation analysis on whole blood samples and analyzed the results in relation to fecal short-chain fatty acid concentrations and microbiota composition. In another cohort, prefrontal cortex neurons were isolated from control and PD brains. We identified the genome-wide DNA methylation by targeted bisulfite sequencing.
Results
We show that lower fecal butyrate and reduced Roseburia, Romboutsia, and Prevotella counts are linked to depressive symptoms in PD patients. Genes containing butyrate-associated methylation sites include PD risk genes and significantly overlap with sites epigenetically altered in PD blood leucocytes, predominantly neutrophils, and in brain neurons, relative to controls. Moreover, butyrate-associated methylated-DNA (mDNA) regions in PD overlap with those altered in gastrointestinal, autoimmune, and psychiatric diseases.
Exploratory analysis of age and sex dependent DNA methylation patterns on the X-chromosome in whole blood samples
