A bacterium normally present in the skin can control cutaneous inflammation, a study in this week's Nature Medicine reports.
The normal bacterial flora of the skin includes staphylococcal species which are certain bacteria that induce inflammation when present below one of the layers of skin but are harmless on the surface layer. Richard Gallo and his coworkers found a mechanism by which staphylococci bacteria inhibit skin inflammation. This inhibition depends on the amount of LTA, a molecule produced by the staphylococci that acts on skin cells.
The authors discovered that skin cells require activation of a pathogen-sensing receptor called TLR3 to release proinflammatory molecules. Staphylococcal LTA inhibits this release acting through a second pathogen-sensing receptor: TLR2. This work is the first time that the skin flora is documented to regulate specific inflammatory responses in the skin.