Microbes Tickling Your Tummy: the Importance of the Gut-Brain Axis in Parkinson’s Disease

Paula Perez-Pardo, Mitch Hartog, Johan Garssen, Aletta D. Kraneveld

Patients suffering from Parkinson's disease (PD) are known to experience gastrointestinal dysfunction that might precede the onset of motor symptoms by several years. Evidence suggests an important role of the gut-brain axis in PD pathogenesis. These interactions might be essentially influenced by the gut microbiota. Here, we review recent findings supporting that changes in the gut microbiota composition might be a trigger for inflammation contributing to neurodegeneration in PD. Recent research revealed that PD patients exhibit a pro-inflammatory microbiota profile in their intestinal tract that might increase gut permeability, allowing leakage of bacterial products and inflammatory mediators from the intestines. Evidence in literature indicates that alpha-synuclein deposition might start in the enteric nervous system by pro-inflammatory immune activity and then propagates to the CNS. Alternatively, the peripheral inflammatory response could impact the brain through systemic mechanisms. A better understanding of the gut-brain interactions and the role of the intestinal microbiota in the regulation of immune responses might bring new insights in PD pathological progression and might lead to novel diagnostics and therapeutic approaches.