ATLANTA, Georgia - In humans, developing metabolic disease,
particularly type 2 diabetes, is correlated with having bacteria
that penetrate the mucus lining of the colon, according to a study
led by Drs. Benoit Chassaing and Andrew Gewirtz at Georgia State University.
The findings, which provide insight on how people develop
insulin resistance-associated dysglycemia (abnormal blood glucose
levels), are published in the journal
Cellular and Molecular Gastroenterology and
Metabolic syndrome is the term for a group of factors that
raise a person's risk for heart disease and other health problems,
such as diabetes and stroke.
Such risk factors include a large waistline, a high
triglyceride level (type of fat found in the blood), low HDL
cholesterol level, high blood pressure and high fasting blood sugar
Metabolic syndrome, which has become far more common due
to a rise in obesity rates among adults, is a leading risk factor
for many serious, life-threatening diseases, including type 2
diabetes and heart disease, according to the National Institutes of
"Alterations in bacteria have been associated with
metabolic diseases, including obesity and type 2 diabetes, but
mechanisms remain elusive," said Gewirtz, professor in the
Institute for Biomedical Sciences at Georgia State.
Dr Andrew Gerwitz, professor in the
Institute for Biomedical Sciences at Georgia
"Previous studies in mice have indicated that bacteria
that are able to encroach upon the epithelium might be able to
promote inflammation that drives metabolic diseases, and now we've
shown that this is also a feature of metabolic disease in humans,
specifically type 2 diabetics who are exhibiting microbiota
The epithelium is the mucus-lined cellular covering of
internal and external surfaces of the body, including the
Gut microbiota is the collective term for the communities
of microscopic living organisms that inhabit this
Gut microbiota that live in the outer regions of the mucus
and remain a safe distance from epithelial cells provide a benefit
to the host, but Chassaing and Gewirtz hypothesize that microbiota
that encroach upon host cells drive chronic inflammation that
interferes with the normal action of insulin, promoting type 2
In this study, the researchers used samples from human
subjects enrolled at the Veteran's Administration Hospital in
Atlanta. The subjects, at least 21 years old with no major health
problems besides diabetes, were undergoing colonoscopy for colon
The researchers obtained each subject's history of
diabetes and gastrointestinal complaints through interviews and
reviewing medical records. During the colonoscopy procedure, two
mucosal biopsies were taken from the left colon and
The study's results have impressed leading experts in
"The data are impressive and may have opened a new field
of investigation in metabolic function and type 2 diabetes," said
Dr. Samuel Klein, chief of the Division of Geriatrics and
Nutritional Science at the Washington University School of Medicine
Diabetes Research Center.
The researchers are conducting follow-up studies to
determine the identity of the bacteria that are invading the colon
lining and are exploring remedies to prevent such bacteria
Chassaing, assistant professor in the Institute for
Biomedical Sciences and Center for Inflammation, Immunity and
Infection, is lead author of the study.
Co-authors of the paper include Dr. Shreya M. Raja and Dr.
Shanthi Srinivasan of Emory University School of Medicine and Dr.
James D. Lewis of Perelman School of Medicine at University of
The study is funded by the National Institutes of Health
and the Crohn's and Colitis Foundation.
- Georgia State University