• Microbiota alterations
• Metabolic changes
What is already known on this topic
Parkinson’s disease — a neurodegenerative disorder that affects movement — usually starts with gastrointestinal problems that precede motor symptoms. Although studies have found alterations of the gut microbiota in people with Parkinson’s disease, little is known about the role that gut bacteria play in the symptoms associated with the disease.What this research adds
By analyzing the gut microbiota of more than 30 people with Parkinson’s disease, researchers found that a few key microbial species are associated with disease severity and gastrointestinal problems, among other things. Further analyses revealed that microbes in the gut of individuals with Parkinson’s disease are better able at degrading mucin and host glycans than gut bacteria from control individuals. What’s more, gut microbes appear to contribute to the deficiency of one type of vitamin B called folate as well as to the increased blood levels of the amino acid cysteine observed in people with Parkinson’s disease.Conclusion
The findings could help to uncover the contributions of gut microbes and their metabolites to the disordered processes associated with Parkinson’s disease.
Parkinson’s disease — a neurodegenerative disorder that affects movement — usually starts with gastrointestinal problems that precede motor symptoms. Now, researchers have found that microbial metabolites could play a role in the gastrointestinal complications associated with the disorder.
The findings, published inCell Reports, could help to uncover the contributions of gut microbes and their metabolites to the disordered processes associated with the disease, the researchers say.
Several studies have found alterations of the gut microbiota in individuals with Parkinson’s disease, but little is known about whether gut bacteria could influence the development or the course of gastrointestinal symptoms.
To find out, researchers led by Adil Mardinoglu and Saeed Shoaie at King’s College London and the Science for Life Laboratory analyzed the gut microbiota of 31 people with Parkinson’s disease and 28 healthy individuals.
Microbiota alterations
Compared to controls, the gut microbiota of individuals with Parkinson’s disease showed greater abundances of bacteria includingAkkermansia muciniphila, Alistipes shahii, Alistipes obesi, Alistipes ihumii,andCandidatus gastranaerophilales. Other bacteria, includingPrevotella, Lactobacillus, andStreptococcus species as well asClostridium saccharolyticum, Desulfibrio piger, Roseburia intestinalis, andFaecalibacterium prausnitzii were decreased compared to controls.R. intestinalis andF. prausnitzii are known to produce butyrate, a molecule that has been associated with positive health outcomes.
The changes in gut microbiota composition observed in people with Parkinson’s disease were associated with disease severity, gastrointestinal problems, and age of diseased individuals. For example, the abundance ofEscherichia coli increased with people’s age, and it was associated with disease severity and gastrointestinal dysfunction;ErysipelatoclostridiumandVictivallis vadensiscorrelated with disease severity and age of individuals with Parkinson’s disease.
Metabolic changes
Further analyses revealed that microbes in the gut of individuals with Parkinson’s disease are better able at degrading mucin and host glycans than gut bacteria from control individuals. For instance, the abundance ofA. muciniphila, which is known to degrade glycans and mucins, was substantially increased in individuals with Parkinson’s disease.
The researchers also found that gut microbes appear to contribute to the deficiency of one type of vitamin B called folate as well as to the increased blood levels of the amino acid cysteine observed in people with Parkinson’s disease. Compared to controls, diseased individuals had higher levels ofParaprevotella clara, Prevotellaspecies, andR. intestinalis, which are known to produce folate.A. muciniphila,Subdoligranulum, andEubacterium species as well asClostridiales bacteria were the main producers of homocysteine and increased in people with Parkinson’s disease. “We have found that metabolite levels significantly correlated with abundances of relevant bacteria,” the researchers say.
The alterations in gut microbial composition hinted at a shift toward an inflammatory state associated with reduced anti-inflammatory activity, the researchers say. Such changes could contribute to the gastrointestinal symptoms of Parkinson’s disease, and they have also been suggested as triggers of the abnormal clumping and accumulation of a protein called alpha synuclein in the brain of people with the disease.
