How bacteria in your colon can influence your immune system

Companion papers were published in Science magazine this week that show the bacteria in the gut can influence the development of allergic responses.

These papers are fascinating. Done in germ-free mice, these studies show that the microbiota that reside in your colon can influence the type of immune cells (specifically increasing the T regulatory cells and decreasing T helper 17 cells) that also live in that area. So, why does this matter? Changing the types of T cells that are in the colon can influence why type of immune response you will have – whether it is a cytotoxic response or an allergic response. If you have more T regulatory (Tregs) an allergic response will be generated. In fact, these studies both show that antibiotics given early in the lives of these mice can dramatically alter the makeup of the microbiota in the colon and drive it towards being more of the allergic phenotype. So, by killing off some of the beneficial bacteria, you may be influencing your immune system and producing more allergic responses.

It is critical to keep in mind that these are studies done in mice. It remains to be seen if these same findings will be upheld in humans.

To read more, check out these papers – Ohnmacht and colleagues and Sefik and colleagues and a commentary by Hegazy and Powrie .

photo by AJC

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