title: Uncovering the evolutionary history of innate immunity: the simple metazoan Hydra uses epithelial cells for host defence.
abstract: Although many properties of the innate immune system are shared among multicellular animals, the evolutionary origin remains poorly understood. Here we characterize the innate immune system in Hydra, one of the simplest multicellular animals known. In the complete absence of both protective mechanical barriers and mobile phagocytes, Hydra's epithelium is remarkably well equipped with potent antimicrobial peptides to prevent pathogen infection. Induction of antimicrobial peptide production is mediated by the interaction of a leucine-rich repeats (LRRs) domain containing protein with a TIR-domain containing protein lacking LRRs. Conventional Toll-like receptors (TLRs) are absent in the Hydra genome. Our findings support the hypothesis that the epithelium represents the ancient system of host defence.
authors.affiliation: Zoological Institute, Christian-Albrechts-University Kiel, Germany. tbosch@zoologie.uni-kiel.de
authors.forename: Thomas C G
authors.initials: TC
authors.lastname: Bosch
authors.forename: René
authors.initials: R
authors.lastname: Augustin
authors.forename: Friederike
authors.initials: F
authors.lastname: Anton-Erxleben
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fraune
authors.forename: Georg
authors.initials: G
authors.lastname: Hemmrich
authors.forename: Holger
authors.initials: H
authors.lastname: Zill
authors.forename: Philip
authors.initials: P
authors.lastname: Rosenstiel
authors.forename: Gunnar
authors.initials: G
authors.lastname: Jacobs
authors.forename: Stefan
authors.initials: S
authors.lastname: Schreiber
authors.forename: Matthias
authors.initials: M
authors.lastname: Leippe
authors.forename: Mareike
authors.initials: M
authors.lastname: Stanisak
authors.forename: Joachim
authors.initials: J
authors.lastname: Grötzinger
authors.forename: Sascha
authors.initials: S
authors.lastname: Jung
authors.forename: Rainer
authors.initials: R
authors.lastname: Podschun
authors.forename: Joachim
authors.initials: J
authors.lastname: Bartels
authors.forename: Jürgen
authors.initials: J
authors.lastname: Harder
authors.forename: Jens-M
authors.initials: JM
authors.lastname: Schröder
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000235:genetics* / Q000276:immunology; D000975:Antioxidants / Q000494:pharmacology; D001483:Base Sequence; D004847:Epithelial Cells / Q000276:immunology* / Q000382:microbiology / Q000648:ultrastructure; D019143:Evolution, Molecular; D005408:Flagellin / Q000276:immunology; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D006829:Hydra / Q000276:immunology* / Q000382:microbiology / Q000648:ultrastructure; D007113:Immunity, Innate; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D011550:Pseudomonas aeruginosa; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D016415:Sequence Alignment; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology; D014527:Uric Acid / Q000494:pharmacology
chemical_list: D023181:Antimicrobial Cationic Peptides; D000975:Antioxidants; D011956:Receptors, Cell Surface; D005408:Flagellin; D014527:Uric Acid