Georgia university. US: Promoting healthy gut microbiota, the bacteria that live in the
intestine, can help treat or prevent metabolic syndrome, a combination
of risk factors that increases the risk of heart disease, diabetes and
stroke, according to researchers at Georgia State University and Cornell
University. Their findings are published in the journal Gastroenterology.
The study, a follow-up to the research team’s previous paper in
Science, uses an improved technical approach, making the results more
significant.
The research team includes Dr. Andrew Gewirtz, a professor in the Institute for Biomedical Sciences at Georgia State;
Dr. Benoit Chassaing, a post-doctoral student at Georgia State; and Dr.
Ruth Ley of the departments of Microbiology and Molecular Biology at
Cornell.
“These results suggest that developing a means to promote a more healthy
microbiota can treat or prevent metabolic disease,” Gewirtz said. “They
confirm the concept that altered microbiota can promote low-grade
inflammation and metabolic syndrome and advance the underlying
mechanism. We showed that the altered bacterial population is more
aggressive in infiltrating the host and producing substances, namely
flagellin and lipopolysaccharide, that further promote inflammation.”
Metabolic syndrome is a serious health condition that affects 34
percent of American adults, according to the American Heart Association.
A person is diagnosed with metabolic syndrome when he or she has three
of these risk factors: a large waistline, high triglyceride (type of fat
found in the blood) level, low HDL cholesterol level, high blood
pressure and high fasting blood sugar. A person with metabolic syndrome
is twice as likely to develop heart disease and five times as likely to
develop diabetes, according to the National Institutes of Health.
Because metabolic syndrome is becoming more common, scientists are exploring possible causes. In their previous study in Science, Gewirtz, Ley and other researchers showed altered gut microbiota play a role in promoting metabolic syndrome.
Gut microbiota perform key functions in health and when it becomes
deregulated it can promote chronic inflammatory diseases such as Crohn’s
disease and ulcerative colitis. In addition, altered gut microbiota
promote inflammation that leads to metabolic syndrome.
“We’ve filled in a lot of the details about how it works,” Gewirtz
said. “It’s the loss of TLR5 on the epithelium, the cells that line the
surface of the intestine and their ability to quickly respond to
bacteria. That ability goes away and results in a more aggressive
bacterial population that gets closer in and produces substances that
drive inflammation.”
Normally, the bacteria are in the mucous layer at a certain distance
away from epithelial cells. The researchers showed altered gut
microbiota is more aggressive in infiltrating the host and gets very
close to the epithelium. This altered population produces flagellin and lipopolysaccharide, which further promote inflammation.
The research team improved the study by comparing mice that were
siblings and littermates, making all conditions in the study the same.
The mice only differed by whether they were missing a specific gene,
TLR5. Previously, the researchers studied mice that were from two
different strains and lived in separate environments. In this study,
they found the absence of TLR5 on the intestinal surface leads to
alterations in bacteria that drive inflammation, leading to metabolic
syndrome.
This study was funded by the National Institutes of Health and the Crohn’s and Colitis Foundation of America.