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Bacteria that invade colon lining linked to metabolic syndrome, diabetes
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Microbiota that invade the normally sterile inner colonic mucus layer correlate with the development of metabolic disease in humans, especially type 2 diabetes, according to new research.
Experts said these “impressive” findings provide new insight on how insulin resistance-associated dysglycemia develops in humans.
“Alterations in bacteria have been associated with metabolic diseases, including obesity and type 2 diabetes, but mechanisms remain elusive,” Andrew T. Gewirtz, PhD, a professor in the Institute for Biomedical Sciences at Georgia State University, said in a press release. “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 encroachment.”
Andrew T. Gewirtz
To investigate whether encroachment of colonic microbiota upon host epithelial cells may correlate with features of metabolic syndrome, Gewirtz and colleagues used confocal microscopy to measure the distance of the closest bacteria to the epithelium in left-colon biopsies taken from 42 participants who underwent routine cancer screening colonoscopy at the Atlanta VA Hospital (mean age, 58.1 years). Overall, 86% of participants were overweight, 45% were obese and a third had diabetes.
After standard bowel cleansing, the investigators found that remaining bacteria were “almost exclusively observed in outer regions of the mucus layer” in healthy participants without obesity or diabetes, “whereas in obese persons with diabetes, bacteria could be found in the dense inner mucus and in close proximity to the epithelium.”
The investigators found an inverse correlation between bacterial-epithelial distance and markers of metabolic syndrome in all patients, including BMI, fasting blood glucose levels, and hemoglobin A1c.
After stratifying participants with and without diabetes, they found that bacterial-epithelial distance was nearly three times lower in patients with type 2 diabetes, even after excluding participants with obesity.
Further, they found that bacterial-epithelial distance was comparable between patients with and without obesity after excluding those with diabetes.
The researchers concluded that “microbiota encroachment is a feature of insulin resistance-associated dysglycemia in humans,” and wrote that their findings could eventually contribute to novel treatment and prevention strategies for metabolic syndrome.
“The data are impressive and may have opened a new field of investigation in metabolic function and type 2 diabetes,” Samuel Klein, MD, chief of the division of geriatrics and nutritional science at the Washington University School of Medicine Diabetes Research Center, said in the press release.
Follow-up studies to identify the encroaching bacteria and explore prevention strategies are ongoing, according to the press release. – by Adam Leitenberger
Disclosures: The researchers report no relevant financial disclosures.
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