title: Flagellin delivery by Pseudomonas aeruginosa rhamnolipids induces the antimicrobial protein psoriasin in human skin.
abstract: The opportunistic pathogen Pseudomonas aeruginosa can cause severe infections in patients suffering from disruption or disorder of the skin barrier as in burns, chronic wounds, and after surgery. On healthy skin P. aeruginosa causes rarely infections. To gain insight into the interaction of the ubiquitous bacterium P. aeruginosa and healthy human skin, the induction of the antimicrobial protein psoriasin by P. aeruginosa grown on an ex vivo skin model was analyzed. We show that presence of the P. aeruginosa derived biosurfactant rhamnolipid was indispensable for flagellin-induced psoriasin expression in human skin, contrary to in vitro conditions. The importance of the bacterial virulence factor flagellin as the major inducing factor of psoriasin expression in skin was demonstrated by use of a flagellin-deficient mutant. Rhamnolipid mediated shuttle across the outer skin barrier was not restricted to flagellin since rhamnolipids enable psoriasin expression by the cytokines IL-17 and IL-22 after topical application on human skin. Rhamnolipid production was detected for several clinical strains and the formation of vesicles was observed under skin physiological conditions. In conclusion we demonstrate herein that rhamnolipids enable the induction of the antimicrobial protein psoriasin by flagellin in human skin without direct contact of bacteria and responding cells. Hereby, human skin might control the microflora to prevent colonization of unwanted microbes in the earliest steps before potential pathogens can develop strategies to subvert the immune response.
authors.affiliation: Department of Dermatology, University Hospital Schleswig-Holstein, Kiel, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Meyer-Hoffert
authors.forename: Alexandra
authors.initials: A
authors.lastname: Zimmermann
authors.forename: Manfred
authors.initials: M
authors.lastname: Czapp
authors.forename: Joachim
authors.initials: J
authors.lastname: Bartels
authors.forename: Yulia
authors.initials: Y
authors.lastname: Koblyakova
authors.forename: Regine
authors.initials: R
authors.lastname: Gläser
authors.forename: Jens-Michael
authors.initials: JM
authors.lastname: Schröder
authors.forename: Ulrich
authors.initials: U
authors.lastname: Gerstel
mesh_terms: D000890:Anti-Infective Agents; D001424:Bacterial Infections / Q000276:immunology / Q000517:prevention & control; D005408:Flagellin / Q000276:immunology*; D006017:Glycolipids / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000276:immunology; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins / Q000235:genetics*; D012867:Skin / Q000382:microbiology*; D015533:Transcriptional Activation
chemical_list: D000890:Anti-Infective Agents; D006017:Glycolipids; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; C089242:S100A7 protein, human; C418382:rhamnolipid; D005408:Flagellin