How Gut Bacteria Train Our Immune Syestem

[Rosie]

The most recent issue of "Nature" has an important finding related to the mechanism of tolerance to gut bacteria. The news article provides a very nice overview of how tolerance occurs, and is fairly easy to follow.

http://www.nature.com/news/2011/110921/ ... 1.550.html
Microbes living in the colons of mice coax immune cells in their host to embrace them rather than spark an immune response, according to a study published today in Nature1. That process happens not in a specialized organ called the thymus, where such immune cells are normally trained, but right in the microbes' front yard: the gut.

"The idea here is that the commensal bacteria for some reason preferentially induce regulatory T cells, which then induce tolerance to these bacteria."
How exactly that happens is still unknown, but Hsieh says his lab is working on that question. The findings so far suggest that there may be a mechanism that distinguishes between two different types of foreign bacteria — harmful versus friendly.

Identifying that mechanism may open up new possibilities for treating colitis, Hsieh notes. Previously, researchers had no idea which antigens in the colon were being recognized to trigger the inflammation, but it may now be possible to figure that out.

Rosie

[tex]

Finally, the researchers noticed that in mice with colitis, receptors normally present on regulatory T cells in the colon were instead present on effector T cells. "So if you don't develop a regulatory T-cell response, you could actually induce an inflammatory response to these bacteria," Hsieh says.

Some of us have long suspected that this may be the cause of inflammation with IBDs, (or at least one of the causes) - either missing, insufficient, or corrupt regulatory T-cells. The discovery quoted above certainly appears to validate that theory. I'm kind of surprised that no one ever noticed that previously.

Thanks for the information.

Tex