Microbes residing in the hair follicles and over the surface of the skin may contribute to the immune system’s normal ability to function, according to new research published last week in Science (July 26). The finding could help scientists understand skin diseases like psoriasis and improve the design of tissue-specific vaccines, according to the authors.
Commensal microbes living in the GI tract have long been known to help prime the immune system for pathogenic attack. Now, it appears that organisms living on the skin do the same. “No one had any idea of the relative magnitude of the immunological effect in skin, or how similar any mechanisms found outside the gut would be to those occurring inside the gut,” Curtis Huttenhower, a computational biologist at the Harvard School of Public Health in Boston who was not involved in the study, told Nature.
Researchers from the National Institute of Allergy and Infectious Diseases in Bethesda compared mice grown in germ-free conditions to those whose skin had only colonized by certain known bacteria and observed that T cells in the germ-free mice did not produce a cytokine that is crucial in initiating an immune response. These and other experiments demonstrate that commensal bacteria on the skin are required for the skin’s immune cells to produce and respond to this essential cytokine and fight infection.