title: Invertebrate extracellular phagocyte traps show that chromatin is an ancient defence weapon.
abstract: Controlled release of chromatin from the nuclei of inflammatory cells is a process that entraps and kills microorganisms in the extracellular environment. Now termed ETosis, it is important for innate immunity in vertebrates. Paradoxically, however, in mammals, it can also contribute to certain pathologies. Here we show that ETosis occurs in several invertebrate species, including, remarkably, an acoelomate. Our findings reveal that the phenomenon is primordial and predates the evolution of the coelom. In invertebrates, the released chromatin participates in defence not only by ensnaring microorganisms and externalizing antibacterial histones together with other haemocyte-derived defence factors, but crucially, also provides the scaffold on which intact haemocytes assemble during encapsulation; a response that sequesters and kills potential pathogens infecting the body cavity. This insight into the early origin of ETosis identifies it as a very ancient process that helps explain some of its detrimental effects in mammals.
authors.affiliation: 1] Centre for Marine Biodiversity and Biotechnology, School of Life Sciences, Heriot Watt University, Edinburgh, Scotland EH14 4AS, UK [2] Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, Scotland EH16 4TJ, UK.
authors.forename: Calum T
authors.initials: CT
authors.lastname: Robb
authors.affiliation: Centre for Marine Biodiversity and Biotechnology, School of Life Sciences, Heriot Watt University, Edinburgh, Scotland EH14 4AS, UK.
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Dyrynda
authors.affiliation: Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, Scotland EH16 4TJ, UK.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Gray
authors.affiliation: Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, Scotland EH16 4TJ, UK.
authors.forename: Adriano G
authors.initials: AG
authors.lastname: Rossi
authors.affiliation: Scottish Oceans Institute, School of Biology, University of St Andrews, St Andrews, Scotland KY16 8LB, UK.
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Smith
mesh_terms: D000818:Animals; D003386:Brachyura / Q000166:cytology / Q000276:immunology*; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D002843:Chromatin / Q000502:physiology*; D019610:Cytoprotection / Q000276:immunology; D065206:Extracellular Traps / Q000276:immunology*; D006434:Hemocytes / Q000166:cytology / Q000276:immunology*; D007113:Immunity, Innate / Q000502:physiology*; D066298:In Vitro Techniques; D010586:Phagocytes / Q000166:cytology / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology*; D010802:Phylogeny
chemical_list: D002843:Chromatin