"Future studies should study the effects of long-term supplementation of promising nutrients, such as butyrate and niacin, on their abilities to halt or reverse disease progression in PD. "
Niacin and Butyrate: Nutraceuticals Targeting Dysbiosis and Intestinal Permeability in Parkinson’s Disease 2020 mdpi.com/2072-6643/13/1/28/htm
10. Conclusions
Microbiome studies in Parkinson’s disease, like other conditions, suffer from methodological variation and confounding factors and, therefore, specific bacteria involved in the pathogenesis of PD are difficult to characterize. However, an overall pattern corresponding to decreases in SCFA-producing bacteria and increases in endotoxin-producing bacteria have been observed in PD subjects. Fecal microbiome transplantation (FMT) and pre- and probiotics offer potential options for restoring the microbiome to PD patients. There are no robust data to adequately support FMT efficacy on motor and/or non-motor symptoms improvement or slowing the progression of PD or which route of administration and what content/volume of FMT is optimal. Therefore, we need more rigorous and well designed clinical trials to support FMT or the use of pro- and prebiotics in selected subgroups of PD patients in the future. GPR109A, a G-protein coupled receptor found on the surface of intestinal epithelium and macrophages, closely interacts with the microbiome to permit immune tolerance or trigger an inflammatory cascade. Loss of GPR109A is associated with decreased concentration of tight junction proteins and increased intestinal permeability. In inflammatory states, butyrate acts via GPR109A to increase concentrations of tight junction proteins and improve intestinal permeability. Niacin deficiency is exacerbated in PD by dopaminergic medications. Furthermore, niacin shifts macrophage polarization from pro-inflammatory to an anti-inflammatory profile. Future studies should study the effects of long-term supplementation of promising nutrients, such as butyrate and niacin, on their abilities to halt or reverse disease progression in PD. A deeper understanding of the GPR109A pathway in modulating intestinal permeability and its interplay in the microbiome–gut–brain axis may provide therapeutic options for multiple inflammatory and other neurodegenerative conditions.
