title: Systems Analysis of the Dynamic Inflammatory Response to Tissue Damage Reveals Spatiotemporal Properties of the Wound Attractant Gradient.
abstract: In the acute inflammatory phase following tissue damage, cells of the innate immune system are rapidly recruited to sites of injury by pro-inflammatory mediators released at the wound site. Although advances in live imaging allow us to directly visualize this process in vivo, the precise identity and properties of the primary immune damage attractants remain unclear, as it is currently impossible to directly observe and accurately measure these signals in tissues. Here, we demonstrate that detailed information about the attractant signals can be extracted directly from the in vivo behavior of the responding immune cells. By applying inference-based computational approaches to analyze the in vivo dynamics of the Drosophila inflammatory response, we gain new detailed insight into the spatiotemporal properties of the attractant gradient. In particular, we show that the wound attractant is released by wound margin cells, rather than by the wounded tissue per se, and that it diffuses away from this source at rates far slower than those of previously implicated signals such as H2O2 and ATP, ruling out these fast mediators as the primary chemoattractant. We then predict, and experimentally test, how competing attractant signals might interact in space and time to regulate multi-step cell navigation in the complex environment of a healing wound, revealing a period of receptor desensitization after initial exposure to the damage attractant. Extending our analysis to model much larger wounds, we uncover a dynamic behavioral change in the responding immune cells in vivo that is prognostic of whether a wound will subsequently heal or not. VIDEO ABSTRACT.
authors.affiliation: Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK; School of Cellular and Molecular Medicine, Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Weavers
authors.affiliation: Theoretical Systems Biology, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK.
authors.forename: Juliane
authors.initials: J
authors.lastname: Liepe
authors.affiliation: Theoretical Systems Biology, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK.
authors.forename: Aaron
authors.initials: A
authors.lastname: Sim
authors.affiliation: School of Cellular and Molecular Medicine, Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Will
authors.initials: W
authors.lastname: Wood
authors.affiliation: Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK; Department of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, Bristol BS8 1TD, UK; School of Medicine, Cardiff University, Cardiff CF14 4XN, UK; Lee Kong Chian School of Medicine, Nanyang Technologicial University, Singapore 636921, Singapore. Electronic address: paul.martin@bristol.ac.uk.
authors.forename: Paul
authors.initials: P
authors.lastname: Martin
authors.affiliation: Theoretical Systems Biology, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK. Electronic address: m.stumpf@imperial.ac.uk.
authors.forename: Michael P H
authors.initials: MPH
authors.lastname: Stumpf
mesh_terms: D000818:Animals; D002630:Chemotactic Factors / Q000378:metabolism*; D004330:Drosophila / Q000502:physiology*; D007113:Immunity, Innate; D013597:Systems Analysis
chemical_list: D002630:Chemotactic Factors