"The impact of the gut microbiome is being increasingly appreciated in health and in various chronic diseases, among them neurodegenerative disorders such as Parkinson’s disease (PD). … In addition to increased local inflammatory activity in the intestine, there is also evidence of increased systemic inflammatory activity in Parkinson’s disease. Thus, the working group around Williams-Grey and Bordacki detected increased levels of proinflammatory cytokines such as TNF-α, INF-gamma, IL1-β, IL-2, IL-4, IL-6 and IL-10 within the blood of PD patients … In this context, it has already been suspected that proinflammatory cytokines lead to a disruption of the blood-brain barrier and consequently are indirectly involved in the activation of glial cells … in a mouse model of PD transplantation of the microbiome of patients with PD into receptive mice led to motor symptoms as opposed to the transplant sample of healthy individuals … Furthermore, recently it has also been shown that gut-associated bacteria differ in their ability to decarboxylate levodopa to dopamine via tyrosine decarboxylases in the proximal small intestine and thereby influence the levodopa dosages needed for symptom control … In this regard, a conserved tyrosine decarboxylase (TyrDC) has been detected within Enterococcus faecalis … In addition, a negative correlation between the frequency of Firmicutes and the use of entacapone has been reported … These data suggest that in future the microbiome might be a crucial component in the management of side effects as well as in the therapy of PD."