Germs: The Answer to Inflammatory Skin Diseases?

Ever since the nineteenth century, when microbes were identified as the source of infectious diseases, efforts to stamp out germs have been intensifying. One manifestation of our war against the microbial world is the constant onslaught of anti-germ products, everything from hand soaps and gels to disinfecting wipes, household cleansers and carpet shampoos. Certainly people living in the developed world today are cleaner than at any other time in the history of our species. But in the quest to sanitize our surroundings, are we threatening the very alliances on which our survival depends? Is there such a thing as being too clean?

From shortly after birth to death, we are covered from head to toe with germs—the product of thousands of years of co-evolution. As adults, each of us carry about a quarter of a pound. They reside in dense multi-species communities in a variety of niches, from the moist recesses of the tongue to the nutritious large intestines. These native germs are thought to work on our behalf, giving us needed vitamins and protecting us from more harmful microbes. Even more importantly, however, is the growing body of evidence suggesting that indigenous bacteria play an active role as the body’s first line of defense, a theory further supported by a recent study at the University of California, San Diego (UCSD) School of Medicine.

By performing experiments in mice and human cell cultures, the research team discovered that common bacteria present on the skin’s surface can prevent excessive inflammation after injury. The effect occurs because of a chemical produced by the bacteria called staphylococcal lipoteichoic acid, which prevents the interaction between the skin cells and their special receptors that is required to generate an inflammatory response. “These germs are actually good for us,” said Richard L. Gallo, professor of medicine and pediatrics, chief of UCSD’s Division of Dermatology and the Dermatology section of the Veterans Affairs San Diego Healthcare System. “This may help us devise new therapeutic approaches for inflammatory skin diseases.”