How exactly do the countless microbes that call our bodies "home" help us to maintain healthy immune systems?
A new study with mice, published last week in Science, has shown that specific bacteria of the genus Clostridium promote the generation of regulatory T cells, or Treg cells, in the mouse colon -- a discovery that suggests new therapeutic approaches to allergies and autoimmunity.
Koji Atarashi and colleagues first eliminated all the bacteria from the colons of mice and found that populations of colonic Treg cells plummeted.
By dosing those bacteria-free mice with a certain mix of Clostridium strains, the researchers observed a return of those Treg cells to the colon.
The researchers also found that feeding wild-type mice (with all their commensal bacteria intact) the Clostridium bacteria produced elevated levels of Treg cells in the mice and helped the rodents to ward off autoimmune colitis and other allergies.
These data highlight how these particular Clostridium bacteria help to regulate specific immune cell populations, and in the future the findings might even be used to improve treatment for certain autoimmune diseases.
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"Induction of colonic regulatory T cells by indigenous Clostridium species," by K. Atarashi et al., Science, January 2010.