Uncovering the evolutionary history of innate immunity: the simple metazoan Hydra uses epithelial cells for host defence.

Authors:
Thomas C G Bosch, René Augustin, Friederike Anton-Erxleben, Sebastian Fraune, Georg Hemmrich, Holger Zill, Philip Rosenstiel, Gunnar Jacobs, Stefan Schreiber, Matthias Leippe, Mareike Stanisak, Joachim Grötzinger, Sascha Jung, Rainer Podschun, Joachim Bartels, Jürgen Harder, Jens-M Schröder
Year of publication:
2009
Volume:
33
Issue:
4
Issn:
0145-305X
Journal title abbreviated:
DEV COMP IMMUNOL
Journal title long:
Developmental and comparative immunology : an international journal on immunological diversification
Impact factor:
3.620
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.