Gut Bacterial Community Helps Prevent Diabetes

A new study reveals that hosts with robust commensal bacteria living in their intestines produce biochemicals and hormones that could stop diabetes from developing.

Researchers at the University of Bern (Switzerland) and the University of Toronto (Canada) demonstrated, in a mouse model, a direct interaction between sex hormones and early life microbial exposures on the control of autoimmunity in the non-obese diabetic (NOD) mouse model of type 1 diabetes (T1D). The researchers showed that intestinal colonization by commensal microbes elevated serum testosterone levels and protected the NOD male mice from T1D.


In addition, the transfer of gut bacteria from adult males to immature females altered their microbiota, causing elevated testosterone levels and various metabolomic changes that reduced islet inflammation and autoantibody production, providing the females with acquired robust T1D protection. The researchers also found that these effects were dependent on androgen receptor activity, and concluded that commensal microbial community could help alter sex hormone levels and regulate or alter autoimmune disease fate in individuals with high genetic risk. The study was published on January 17, 2013, in Science.

“We hope that our new understanding of how intestinal bacteria may protect susceptible children from developing diabetes will allow us to start to develop new treatments to stop children getting the disease,” said study coauthor Prof. Andrew Macpherson, MD, PhD, of the Clinic for Visceral Surgery and Medicine at the University of Bern.

The average human body, consisting of about ten trillion cells, has about ten times that number of microorganisms in the gut. The metabolic activity performed by these bacteria is equal to that of a virtual organ, leading to gut bacteria being termed a "forgotten" organ. The relationship between gut flora and humans is not merely commensal, but rather is a mutually symbiotic relationship; the microorganisms perform a host of useful functions, such as fermenting unused energy substrates, training the immune system, preventing growth of harmful species, regulating the development of the gut, producing vitamins for the host (such as biotin and vitamin K), and producing hormones to direct the host to store fats.

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University of Bern
University of Toronto