FLICKR, PETER ALFRED HESSThe microbial communities that inhabit the skin, perhaps the most diverse of the human body, are suspected to be key players in host defense. New evidence suggests that commensal skin bacteria both directly protect humans from pathogenic invaders and help the immune system maintain that delicate balance between effective protection and damaging inflammation. While causal links between the skin’s commensal microbes and health or disease remain to be demonstrated, the clues that have accumulated in the last few years paint a suggestive picture.
“None of us in the field—and this is true for the gut, this is true for the skin—none of us can actually tell how our experimental observations really relate to human disease, but we’re getting, all of us, closer to mechanistic insights,” said immunologist Yasmine Belkaid, chief of mucosal immunology at the National Institute of Allergy and Infectious Disease (NIAID).
Recent research has begun to document how skin commensals interact with one another, with pathogenic microbes, and with human cells. Staphylococcus epidermidis secrete antimicrobial substances that help fight pathogenic invaders and Propionibacterium acnes use the skin’s lipids to generate short-chain fatty acids that can similarly ward off microbial threats. Meanwhile, these and other skin microbes may be able to alter the behavior human immune cells, ...
