title: A transgenic mouse model of inducible macrophage depletion: effects of diphtheria toxin-driven lysozyme M-specific cell lineage ablation on wound inflammatory, angiogenic, and contractive processes.
abstract: Whether the wound macrophage is a key regulatory inflammatory cell type in skin repair has been a matter of debate. A transgenic mouse model mediating inducible macrophage depletion during skin repair has not been used to date to address this question. Here, we specifically rendered the monocyte/macrophage leukocyte lineage sensitive to diphtheria toxin by expressing the lysozyme M promoter-driven, Cre-mediated excision of a transcriptional STOP cassette from the simian DT receptor gene in mice (lysM-Cre/DTR). Application of diphtheria toxin to lysM-Cre/DTR mice led to a rapid reduction in both skin tissue and wound macrophage numbers at sites of injury. Macrophage-depleted mice revealed a severely impaired wound morphology and delayed healing. In the absence of macrophages, wounds were re-populated by large numbers of neutrophils. Accordingly, macrophage-reduced wound tissues exhibited the increased and prolonged persistence of macrophage inflammatory protein-2, macrophage chemoattractant protein-1, interleukin-1beta, and cyclooxygenase-2, paralleled by unaltered levels of bioactive transforming growth factor-beta1. Altered expression patterns of vascular endothelial growth factor on macrophage reduction were associated with a disturbed neo-vascularization at the wound site. Impaired wounds revealed a loss of myofibroblast differentiation and wound contraction. Our data in the use of lysM-Cre/DTR mice emphasize the pivotal function of wound macrophages in the integration of inflammation and cellular movements at the wound site to enable efficient skin repair.
authors.affiliation: Pharmazentrum Frankfurt/ZAFES, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Itamar
authors.initials: I
authors.lastname: Goren
authors.forename: Nadine
authors.initials: N
authors.lastname: Allmann
authors.forename: Nir
authors.initials: N
authors.lastname: Yogev
authors.forename: Christoph
authors.initials: C
authors.lastname: Schürmann
authors.forename: Andreas
authors.initials: A
authors.lastname: Linke
authors.forename: Martin
authors.initials: M
authors.lastname: Holdener
authors.forename: Ari
authors.initials: A
authors.lastname: Waisman
authors.forename: Josef
authors.initials: J
authors.lastname: Pfeilschifter
authors.forename: Stefan
authors.initials: S
authors.lastname: Frank
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D019070:Cell Lineage / Q000276:immunology*; D004167:Diphtheria Toxin / Q000633:toxicity; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000276:immunology*; D015603:Keratinocytes / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009113:Muramidase / Q000276:immunology / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000276:immunology*; D011042:Poisons / Q000633:toxicity; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014945:Wound Healing / Q000276:immunology*
chemical_list: D004167:Diphtheria Toxin; D011042:Poisons; D016212:Transforming Growth Factor beta; D009113:Muramidase; C472450:lysozyme M, mouse