Uncovering the evolutionary history of innate immunity: the simple metazoan Hydra uses epithelial cells for host defence.
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.
Bosch
Thomas C G
TC
Zoological Institute, Christian-Albrechts-University Kiel, Germany. tbosch@zoologie.uni-kiel.de
Augustin
René
R
Anton-Erxleben
Friederike
F
Fraune
Sebastian
S
Hemmrich
Georg
G
Zill
Holger
H
Rosenstiel
Philip
P
Jacobs
Gunnar
G
Schreiber
Stefan
S
Leippe
Matthias
M
Stanisak
Mareike
M
Grötzinger
Joachim
J
Jung
Sascha
S
Podschun
Rainer
R
Bartels
Joachim
J
Harder
Jürgen
J
Schröder
Jens-M
JM
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
D023181:Antimicrobial Cationic Peptides; D000975:Antioxidants; D011956:Receptors, Cell Surface; D005408:Flagellin; D014527:Uric Acid