Role and Mechanism of Gut Microbiota in Human Disease 2021

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Full article: frontiersin.org/articles/10...

Despite the findings of an increased Bifidobacterium in PD, a study showed that a decrease in Bifidobacterium later in disease may be able to predict whether PD stage is going to deteriorate or not. This implicates that the increase in Bifidobacterium in PD may represent a mechanism of beneficial effect against neurodegenerative aggravation. Thus, it can be inferred that a probiotic intervention with Bifidobacterium could prevent the progression of PD to severer stages (Gerhardt and Mohajeri, 2018).

Lots of studies showed that the abundance of Bifidobacterium, Pasteurella, and Enterococcus in intestinal microorganisms of PD patients increased significantly (Hill-Burns et al., 2017; Hopfner et al., 2017; Peng et al., 2018), while the abundance of Brautella, Prevotella, and Faecococcus decreased (Scheperjans et al., 2015; Bedarf et al., 2017; Heintz-Buschart et al., 2018).

Many experimental studies have confirmed gut-brain axis in PD. Alterations in GM in PD patients can lead to the accumulation of α-synuclein and excessive activation of microglia in brain neurons (Sampson et al., 2016). In an experiment that used mice overexpressing α-synuclein, it was shown that more α-synuclein aggregations were present in the brains of mice with non-eradicated microbial as compared to germ-free mice that had no gut bacteria. In the same study, transplantation of the fecal microbiota from PD patients to germ-free mice aggravated α-synuclein-induced motor symptoms to a greater degree than a fecal transplant from healthy people (Sampson et al., 2016). Recent studies show that the decline in short-chain fatty acids and ghrelin mediated by GM alteration in PD patients might be a critical factor in the pathophysiology of PD (Elfil et al., 2020).

A number of studies indicate a significant difference in GM composition between PD and healthy groups, albeit with an incongruent picture across different studies. Bacteria can affect the nervous system in PD directly or indirectly through chemical signals, neural pathways or the immune system. Therefore, these previous studies suggest that GM may play an important role in the intestinal lesions in the pathogenesis of PD.

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"Thus, it can be inferred that a probiotic intervention with Bifidobacterium could prevent the progression of PD to severer stages (Gerhardt and Mohajeri, 2018)"

Mannitol is a polyol. ncbi.nlm.nih.gov/pmc/articl...

"moderate doses of polyols increase the number of bifidobacteria in the microbiomes of healthy individuals and may therefore be beneficial as a prebiotic, but the data are limited to patients with a number of intestinal diseases, including IBS"