Brain Disorders Get A Gut Check

Certain gut bacteria promote degeneration of neurons causing medical conditions such as Parkinson’s disease, researchers from Hong Kong have found.

AsianScientist (Jan. 11, 2022) – Growing scientific evidence shows that the brain and the gut talk to each other and influence each other—sometimes negatively. Proteins secreted by certain gut bacteria could even accelerate the progression of neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease, discovered a new study published in the Proceedings of the National Academy of Sciences of the United States of America.

Neurodegenerative diseases are caused by the accumulation of proteins in brain cells or neurons. Bacteria living in the gut—collectively called the gut microbiome—may have a role to play in that, previous scientific evidence has suggested. But so far, little is known about the molecular mechanisms underlying the interactions between the gut microbiome and the neurons.

To get around that problem, a team led by Dr. Zheng Chaogu from the School of Biological Sciences at the University of Hong Kong identified 38 bacterial genes that can promote neurodegeneration in an animal host. Two of these genes code for proteins that form curli, one type of bacterial amyloid fibers.

The bacterial curli enters the neurons and promotes the accumulation of a protein called human amyloid α-synuclein, eventually causing death of the neurons. When the researchers deleted the curli genes or inhibited the production of the curli using drugs, the symptoms of Parkinson’s disease were suppressed and the functioning of neurons improved in the animal host.

The researchers also found that the curli promoted neurodegeneration in animal models of Alzheimer’s disease, amyotrophic lateral sclerosis and Huntington’s disease, suggesting that the bacteria-secreted curli may have detrimental effects in a range of nervous system disorders.

Therefore, targeting production of bacterial curli in the gut could lead to the development of therapeutic approaches to prevent or slow down the progression of some neurodegenerative diseases. Green tea, for example, has a compound called EGCG which can completely inhibit curli secretion in bacteria, the authors noted.

“This study established a new paradigm for understanding how bacterial components from the gut microbiome can influence neuronal health in animals,” said Zheng.

The article can be found at: Wang et al. (2021) Genome-wide screen identifies curli amyloid fibril as a bacterial component promoting host neurodegeneration.


Source: University of Hong Kong; Photo: Shutterstock.
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