Good Gut Bugs

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Science  03 Jan 2014:
Vol. 343, Issue 6166, pp. 7
DOI: 10.1126/science.343.6166.7-d

The trillions of bacteria in the human gut are important for normal digestion and can contribute to disease when their beneficial actions are lost. They also communicate with and modulate the behavior of the intestinal cells that they contact. Jones et al. examined the signaling mechanisms by which Lactobacilli, bacteria that we consume in cheese and yogurt, stimulate normal proliferation of intestinal cells in fruit flies and mice. These beneficial bacteria caused activation of NADPH oxidase, an enzyme that produces reactive oxygen species (ROS). Oddly enough, production of large amounts of ROS by phagocytes or in the intestine is a defense mechanism for killing bacteria. The smaller amounts produced in response to the Lactobacilli, however, had the beneficial effect of promoting cell proliferation needed for a healthy intestine in the flies and mice tested. Patel et al. point out in a commentary that the difference between the reaction to pathogenic and friendly bacteria may thus be primarily in the amount, rather than the type, of signal produced.

EMBO J. 32 10.1038/emboj.2013.224; 10.1038/emboj.2013.244 (2013).

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