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Dietary fiber can prevent Alzheimer's disease, major new study finds

[Apr. 12, 2023: Staff Writer, The Brighter Side of News]


Research reports for the first time a pathway that begins in the gut and ends with a potent pro-inflammatory toxin in brain cells contributing to the development of Alzheimer’s disease (AD). (CREDIT: Creative Commons)


LSU Health New Orleans Neuroscience Center has made a groundbreaking discovery on the development of Alzheimer's disease. A study led by Drs. Yuhai Zhao and Walter J Lukiw has identified a pathway that begins in the gut and ends with a potent pro-inflammatory toxin in brain cells that contributes to the development of Alzheimer's disease.


The study has also found a simple way to prevent it. The results of the study were published in Frontiers in Neurology.


 
 

The researchers found evidence that a molecule containing a very potent microbial-generated neurotoxin (lipopolysaccharide or LPS) derived from the Gram-negative bacteria Bacteroides fragilis in the human gastrointestinal (GI) tract generates a neurotoxin known as BF-LPS. This pathway is novel as it begins in the gut and ends with a potent pro-inflammatory toxin in brain cells contributing to the development of Alzheimer’s disease.


“LPSs in general are probably the most potent microbial-derived pro-inflammatory neurotoxic glycolipids known,” says Dr. Lukiw. “Many laboratories, including our own, have detected different forms of LPS within neurons of the Alzheimer’s disease-affected human brain.”


 

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In the study, the researchers detailed the pathway of BF-LPS from the gut to the brain and its mechanisms of action once there. BF-LPS leaks out of the GI tract, crosses the blood-brain barrier via the circulatory system, and accesses brain compartments.


Then it increases inflammation in brain cells and inhibits neuron-specific neurofilament light (NF-L), a protein that supports cell integrity. A deficit of this protein leads to progressive neuronal cell atrophy, and ultimately cell death, as is observed in AD-affected neurons. The researchers also found that adequate intake of dietary fiber can head off the process.


 
 

The AD-stimulating pathway begins inside of us - in our GI-tract microbiome - and is therefore very "locally sourced" and active throughout our lives. The highly potent neurotoxin BF-LPS is a natural by-product of GI-tract-based microbial metabolism. Bacteroides fragilis abundance in the microbiome, which is the source of the neurotoxin BF-LPS, can be regulated by dietary fiber intake.


Analysis of the hsa-miRNA-30b-5p (miRNA-30b) interaction with the Homo sapien NF-L 3'-UTR. (CREDIT: Frontiers in Neurology)


Lukiw explains that dietary-based approaches to balance the microorganisms in the microbiome may be an attractive means to modify the abundance, speciation, and complexity of enterotoxigenic forms of AD-relevant microbes and their potential for the pathological discharge of highly neurotoxic microbial-derived secretions that include BF-LPS and other forms of LPS.


 
 

An improved understanding of the interaction between the GI tract-Central Nervous System axis and the GI-tract microbiome and Alzheimer’s disease has considerable potential to lead to new diagnostic and therapeutic strategies in the clinical management of Alzheimer’s disease and other lethal, progressive, and age-related neurodegenerative disorders.


For each experiment (using different batches of HNG cells) a control luciferase signal was generated that included separate controls with each analysis. (CREDIT: Frontiers in Neurology)


Alzheimer's disease is the most common diagnosis for patients with dementia and the sixth leading cause of death for Americans, according to the National Institutes of Health. Experts estimate that as many as 5.8 million Americans aged 65 and older have Alzheimer's disease, and the prevalence in the United States is projected to increase to 13.8 million by 2050.


 
 

The study has found that the abundance of Bacteroides fragilis in the microbiome, which is the source of the neurotoxin BF-LPS, can be regulated by dietary fiber intake. It has been estimated that Americans eat 10-15 grams of fiber a day on average. The USDA recommends that women up to age 50 consume 25 grams a day and men 38 grams. Over age 50, women and men should consume 21 and 30 grams daily, respectively.


LPS, present in brain cells affected with AD, has an inhibitory effect on NF-L expression. (CREDIT: Frontiers in Neurology)


"The novel features of this newly described pathological pathway are threefold," says Dr. Lukiw. "The AD-stimulating pathway begins inside of us - in our GI-tract microbiome - and therefore is very 'locally sourced' and active throughout our lives. The highly potent neurotoxin BF-LPS is a natural by-product of GI-tract-based microbial metabolism. Bacteroides fragilis abundance in the microbiome, which is the source of the neurotoxin BF-LPS, can be regulated by dietary fiber intake."


 
 

The researchers suggest that dietary-based approaches to balance the microorganisms in the microbiome may be an attractive means to modify the abundance, speciation, and complexity of enterotoxigenic forms of Alzheimer's disease-relevant microbes and their potential for the pathological discharge of highly neurotoxic microbial-derived secretions that include BF-LPS and other forms of LPS.


The study's co-authors included Drs. Vivian Jaber and Nathan Sharfman from the LSU Health New Orleans and Aileen Pogue from Alchem Biotech Research in Toronto, Canada.


The study was supported by funding from LSU Health New Orleans, the Brown Foundation, the Joe and Dorothy Dorsett Innovation in Science Health Aging Award, and the National Institutes on Aging of the National Institutes of Health.






For more science news stories check out our New Discoveries section at The Brighter Side of News.


 

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.


 
 

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