Journal of Biological Chemistry
Volume 289, Issue 36, 5 September 2014, Pages 24821-24831
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Immunology
Antimicrobial Histones and DNA Traps in Invertebrate Immunity: Evidences in Crassostrea Gigas*

https://doi.org/10.1074/jbc.M114.576546Get rights and content
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Although antimicrobial histones have been isolated from multiple metazoan species, their role in host defense has long remained unanswered. We found here that the hemocytes of the oyster Crassostrea gigas release antimicrobial H1-like and H5-like histones in response to tissue damage and infection. These antimicrobial histones were shown to be associated with extracellular DNA networks released by hemocytes, the circulating immune cells of invertebrates, in response to immune challenge. The hemocyte-released DNA was found to surround and entangle vibrios. This defense mechanism is reminiscent of the neutrophil extracellular traps (ETs) recently described in vertebrates. Importantly, oyster ETs were evidenced in vivo in hemocyte-infiltrated interstitial tissues surrounding wounds, whereas they were absent from tissues of unchallenged oysters. Consistently, antimicrobial histones were found to accumulate in oyster tissues following injury or infection with vibrios. Finally, oyster ET formation was highly dependent on the production of reactive oxygen species by hemocytes. This shows that ET formation relies on common cellular and molecular mechanisms from vertebrates to invertebrates. Altogether, our data reveal that ET formation is a defense mechanism triggered by infection and tissue damage, which is shared by relatively distant species suggesting either evolutionary conservation or convergent evolution within Bilateria.

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*

This work was supported by grants from the Agence Nationale de la Recherche (ANR) (Vibriogen project, Blanc SVSE7 2011) and the Languedoc-Roussillon region (REVARESP project, Chercheur(se) d'avenir 2009).

This article contains Online supplement 1.

1

Supported by a fellowship from the Ministry of Higher Education and Research.

2

Present address: Laboratory of Immunology Applied to Aquaculture, Dept. of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, 88040-900 Florianópolis, SC, Brazil.

3

Supported by a fellowship from Ifremer.

5

The abbreviations used are:

    ET

    extracellular trap

    ROS

    reactive oxygen species

    PMA

    phorbol myristate acetate

    MIC

    minimum inhibitory concentration

    DPI

    diphenylene iodonium chloride

    WGA

    wheat germ agglutinin

    TRITC

    tetramethylrhodamine isothiocyanate

    SSW

    sterile seawater

    DAMP

    damage-associated molecular pattern

    HMG

    high mobility group

    CIP

    Collection de l'institut Pasteur.