Overseas research has revealed that intestinal microorganisms (microbiome) can also affect diseases occurring in the brain such as Alzheimer's. Microbiome is a term for microbial fungi that live in the intestines.
Until now, studies have shown that microbiome provides a wide range of benefits to our body, such as helping vitamin production, digesting food, and preventing excessive growth of harmful bacteria. However, the study also confirmed that microbiome can damage brain tissue and affect immune cell behavior.
However, the research team expected that the results of this study could affect the intestinal microbial community through antibiotics, probiotics, and diet in the future, leading to a new way to prevent and treat neurodegenerative diseases.
On the 16th, a research team at the University of Washington Medical School in the U.S. said, "We found that microbiome clusters play an important role in brain health in animal testing." Compounds created by intestinal bacteria can damage brain tissue and affect immune cell behavior in a state similar to Alzheimer's.
The research team conducted animal experiments on mice that can cause brain damage and cognitive impairment similar to Alzheimer's by expressing a mutation in human tau protein. Tau protein mutation is known to cause Alzheimer's along with amyloid beta (A)) when excessive accumulation in the brain.
The research team allowed mice to accumulate in neurons, where tau protein is a nerve cell, by 9 months of age, causing damage and causing brain contraction. In addition, genes modified by human aporipoprotein (APOE), an Alzheimer's risk factor, were expressed.
There was a difference in the formation of intestinal microbial groups by dividing them into aseptic environment and a normal environment, respectively. As a result, no intestinal microbial community was found in mice raised in a sterile environment at 40 weeks, and brain damage was much less than that of mice raised in a normal environment.
In addition, when antibiotics were administered to mice grown in normal environments for two weeks, the intestinal microbial group decreased, and brain damage also decreased in male mice. However, the administration of antibiotics did not have a significant impact on female mice.
The research team also examined the effects of three types of specific short-chain fatty acids on neurodegeneration. Short-chain fatty acids are substances made by microorganisms in the intestine breaking down dietary fibers or sugars.
Short-chain fatty acids activate immune cells in the blood, causing neurodegeneration. In particular, activation of immune cells in the brain led to brain tissue damage.
Short-chain fatty acids were not detected in mice without intestinal microbial groups, and when fed, immune cells in the brain were more active and more damage related to tau protein was observed. Fewer three short-chain fatty acids were detected in mice administered with antibiotics.
The research team evaluated the results of this study as meaning that a treatment that changes intestinal microorganisms could affect the development or progression of neurodegenerative disorders.
The research team said, "It is evidence that the intestinal microbial community of Alzheimer's patients and the intestinal microbial community of healthy people may be different," but added, "It is not clear how this difference can affect the disease if it changes the microbial community."
In the future, we plan to study whether mice with genetically neurodegenerative diseases can be manipulated to slow or prevent neurodegeneration before signs of nerve damage appear, he said. "It is the same effect as treating people who are still normal after middle age but have no disability."
Writer: Yeyoung Jeon
(Picture from Unsplash)
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