The Effects of Probiotic Supplementation on Gene Expression Related to Inflammation, Insulin and Lipid in Patients with Parkinson’s Disease: A Randomized, Double-blind, Placebo-Controlled Trial

Background: This study was conducted to evaluate the effects of probiotic supplementation on gene expression related to inflammation, insulin and lipid in patients with Parkinson’s disease (PD). Methods: This randomized, double-blind, placebo-controlled clinical trial was conducted in 50 patients with PD as a pilot study. Participants were randomly allocated into two groups to take either 8×109 CFU/day probiotic supplements or placebo (n = 25 each group, one capsule daily) for 12 weeks. Gene expression related to inflammation, insulin, and lipid was quantified in peripheral blood mononuclear cells (PBMC) of PD patients, with RT-PCR method. Results: After the 12-week intervention, compared with the placebo, probiotic intake downregulated gene expression of interleukin-1 (IL-1) (P = 0.03), IL-8 (P < 0.001) and tumor necrosis factor alpha (TNF-α) (P=0.04) in PBMC of subjects with PD. In addition, probiotic supplementation upregulated transforming growth factor beta (TGF-β) (P = 0.02) and peroxisome proliferator-activated receptor gamma (PPAR-γ) (P = 0.03) in PBMC of subjects with PD compared with the placebo. We did not observe any significant effect of probiotic intake on gene expression of low-density lipoprotein receptor (LDLR) and vascular endothelial growth factor (VEGF) in PBMC of patients with PD. Conclusion: Overall, probiotics supplementation for 12 weeks in PD patients significantly improved gene expression of IL-1, IL-8, TNF-α, TGF-β and PPAR-γ, but did not affect gene expression of VEGF and LDLR, and biomarkers of inflammation and oxidative stress.