How leaky is the gut in Parkinson's disease?

The intestinal epithelial barrier (IEB) plays a critical role in health and disease by regulating the absorption of nutrients, electrolytes and water while preventing gut translocation of pathogens. A compromised intestinal barrier has been reported in Parkinson's disease (PD) further reinforcing the assumption that PD is a gut-brain axis disorder and suggesting that gut-derived factors may participate in disease development and/or progression. However, the diversity of methodology between existing studies on gut permeability in PD, especially regarding the methods used for the evaluation of the IEB, has led to diverging results and it is definitely too early to draw any definite conclusions. We envision novel approaches, such as intestinal organoids and confocal laser endomicroscopy that could be used to study more precisely the IEB in PD.