Skin bacteria may help protect the body

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BETHESDA, Md., July 31 (UPI) -- Bacteria that normally live on the skin may help protect the body from infection, U.S. researchers found.

Researchers at the laboratories of Yasmine Belkaid at the National Institute of Allergy and Infectious Diseases -- in collaboration with Julie Segre at the National Human Genome Research Institute and Dr. Giorgio Trinchieri and Dr. Heidi Kong at the National Cancer Institute -- said millions of naturally occurring commensal bacteria in the skin have a beneficial role.

Commensal organisms can benefit from each other without affecting each other.

Using mouse models, the research team observed that commensals contribute to protective immunity by interacting with the immune cells in the skin.

The investigators colonized germ-free mice -- mice bred with no naturally occurring microbes in the gut or skin -- with the human skin with commensalStaphylococcus epidermidis. The team observed that colonizing the mice with this species of good bacteria enabled an immune cell in the mouse skin to produce a cell-signaling molecule needed to protect against harmful microbes, the study said.

The researchers subsequently infected both colonized and non-colonized germ-free mice with a parasite. Mice that were not colonized with the bacteria did not mount an effective immune response to the parasite; mice that were colonized did.

The findings were published in the journal Science.