Bacterial molecules may prevent inflammatory bowel disease
Common compounds produced by gut microbes quench colitis in mice
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Web edition: July 9, 2013
Common molecules made by bacteria in the gut may act as chill pills for the immune system. Molecules secreted by intestinal bacteria work to prevent misplaced immune attacks in inflammatory bowel diseases like colitis, a new study finds.
“It is a huge advance,” says Sarkis Mazmanian of Caltech. “This opens up the notion that a very easy and potentially very safe therapy for inflammatory bowel disease could exist.”
Decades of research have hinted that microbes play a role in immune-related diseases such as obesity, allergy, inflammatory bowel disease and colon cancer. But scientists have had difficulty pinpointing direct links between the bacteria in the gut and the army of immune cells that live there.
Some researchers have focused on individual microbial species among the gut’s teeming hordes to see how they affect the immune system. But Wendy Garrett’s team at Harvard University decided to look instead for possible immune tamers among the various molecules that many different bacteria make. The team chose to investigate short-chain fatty acids because bacterial species that make large amounts are in short supply in some people with inflammatory bowel disease.
To see whether the microbial molecules play a role in quieting the immune system, the researchers added them to mice’s drinking water. The animals developed elevated levels of inflammation-dousing regulatory T cells in their colons, the team reports July 4 in Science. The cells work like wet blankets, dampening autoimmune flare-ups before they burn out of control.