Bacterial DNA has been found in the blood, liver and fat of people who are obese, showing that either fragments of bacteria or entire live bacteria are leaking into their bodies from their guts, which shouldn鈥檛 be happening.
鈥淓ven fragments of bacteria can trigger an immune response,鈥� says Andr茅 Marette at the Qu茅bec Heart and Lung Research Institute in Canada.
In people who are obese the intestinal barrier is more fragile, Marette says, allowing bacterial fragments or live bacteria to get inside their body. This could contribute to the development of diabetes by causing inflammation in organs such as the liver. We know that obesity increases the risk of type 2 diabetes.
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To investigate, Marette and his colleagues analysed samples of blood, liver and fat tissue taken from people having surgery for weight loss. The team took many precautions to rule out bacterial contamination, which would have compromised the results.
The researchers were surprised to find bacterial DNA in all three types of sample. 鈥淚 never thought they could actually reach organs,鈥� Marette says.
They also found a wide range of bacterial DNA, including some from bacteria known to cause disease, some thought to be beneficial 鈥� at least in the gut 鈥� and some that live in soil or water rather than in our bodies. 鈥淭hat came as a big surprise to us,鈥� Marette says.
The study also found the type of bacteria varied from tissue to tissue and depending on whether people had type 2 diabetes or not.
Because the researchers looked only for the presence of bacterial DNA, they can鈥檛 say whether the DNA came from living bacteria or from fragments of dead bacteria. Living bacteria can cause potentially fatal infections when they get inside the body, but none of the people tested showed signs of this. Marette plans to try to grow bacteria from such tissue samples in future studies, to see whether they are alive or not.
If the leaking of bacteria into the body really does play a part in the development of diabetes, it might be possible to develop new treatments, Marette says. For instance, there might be ways to make the gut less leaky or to kill off the bacteria that cause the problem.
Nature Metabolism
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