‘Sweet tooth’ in the gut plays a key role in fighting infections, study finds

Too much sugar can cause all sorts of problems when it comes to gut health, but one study shows that glucose also plays a key role in our immune system’s ability to fight infection. Scientists say that a specific group of immune cells residing in the intestines uses glucose as an energy source and has a faster metabolism than lymphocytes that circulate in blood. The study finds that, during infections, the local availability of glucose in the gut may have an impact on the speed of resolution of an infection. 

Most lymphocytes circulate through the body in blood, acting as a surveillance system, but there is a specialized group of lymphocytes that reside permanently in tissues. This study, led by Marc Veldhoen at the Institute of Molecular Medicine (iMM) in Portugal, focuses on a specific group of lymphocytes that reside in the intestinal wall, called tissue resident lymphocytes.

“Circulating lymphocytes spend most of their lifetime in the lymph nodes, where there is high availability of energy,” explains Veldhoen in a statement. The lymphocytes that reside in the tissues, however, do not have the same amount of energy available.

“These cells are constantly in a state of semi-activation, ready to respond to challenges, such as infections. We found that these resident lymphocytes are able to adapt to their environment in the gut, and regulate their activity depending on the availability of glucose,” he explains. 

Glucose is rapidly taken up by these cells to generate lactate or pyruvate, molecules that are used to produce energy,” adds Vanessa Morais, another group leader at iMM and collaborator in the study. In the gut, the resident lymphocytes produce energy faster than circulating lymphocytes.

To test if glucose plays a role in the immune response to infection, researchers used a model of gut infection in mice.

“We found that in mice infected with an intestinal pathogen, the local availability of glucose can determine the activation of the resident lymphocytes and [lead] to a faster clearance of infection,” explains Špela Konjar, first author of the study.

These results show that resident lymphocytes are adapted to their environment. Researchers say the findings show how a balanced diet is essential for gut function and immune response.

The findings are published in Proceedings of the National Academy of Sciences.

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