title: Dysregulated Macrophages Are Present in Bleomycin-Induced Murine Laryngotracheal Stenosis.
abstract: OBJECTIVE
  To define the inflammatory cell infiltrate preceding fibrosis in a laryngotracheal stenosis (LTS) murine model.
  
  
  METHODS
  Prospective controlled murine study.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Chemomechanical injury mice (n = 44) sustained bleomycin-coated wire-brush injury to the laryngotracheal complex while mechanical injury controls (n = 42) underwent phosphate-buffered saline (PBS)-coated wire-brush injury. Mock surgery controls (n = 34) underwent anterior transcervical tracheal exposure only. Inflammatory and fibrosis protein and gene expression were assessed in each condition. Immunohistochemistry served as a secondary outcome.
  
  
  RESULTS
  In chemomechanical injury mice, there was an upregulation of collagen I (P < .0001, P < .0001), Tgf-β (P = .0023, P = .0008), and elastin (P < .0001, P < .0001) on day 7; acute inflammatory gene Il1β (P = .0027, P = .0008) on day 1; and macrophage gene CD11b (P = .0026, P = .0033) on day 1 vs mechanical and mock controls, respectively. M1 marker inducible nitric oxide synthase (iNOS) expression decreased (P = .0014) while M2 marker Arg1 (P = .0002) increased on day 7 compared with mechanical controls. Flow cytometry demonstrated increased macrophages (P = .0058, day 4) and M1 macrophages (P = .0148, day 4; P = .0343, day 7; P = .0229, day 10) compared to mock controls. There were similarities between chemomechanical and mechanical injury mice with an increase in M2 macrophages at day 10 (P = .0196).
  
  
  CONCLUSIONS
  The bleomycin-induced LTS mouse model demonstrated increased macrophages involved with the development of fibrosis. Macrophage immunophenotype suggested that dysregulated M2 macrophages have a role in abnormal laryngotracheal wound healing. These data delineate inflammatory cells and signaling pathways in LTS that may potentially be modulated to lessen fibroblast proliferation and collagen deposition.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA ahillel@jhmi.edu.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Hillel
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Idris
authors.initials: I
authors.lastname: Samad
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Garret
authors.initials: G
authors.lastname: Ma
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Dacheng
authors.initials: D
authors.lastname: Ding
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Kaitlyn
authors.initials: K
authors.lastname: Sadtler
authors.affiliation: Department of Oncology, John Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Powell
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Lane
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Maureen R
authors.initials: MR
authors.lastname: Horton
mesh_terms: D000818:Animals; D001761:Bleomycin; D003094:Collagen / Q000032:analysis; D004195:Disease Models, Animal; D004549:Elastin / Q000032:analysis; D005434:Flow Cytometry; D015870:Gene Expression; D007150:Immunohistochemistry; D007829:Laryngostenosis / Q000139:chemically induced / Q000473:pathology*; D007830:Larynx / Q000293:injuries; D008264:Macrophages / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011446:Prospective Studies; D014132:Trachea / Q000293:injuries; D014135:Tracheal Stenosis / Q000139:chemically induced / Q000473:pathology*; D016212:Transforming Growth Factor beta / Q000032:analysis
chemical_list: D016212:Transforming Growth Factor beta; D001761:Bleomycin; D003094:Collagen; D004549:Elastin
keywords: airway epithelial injury; laryngotracheal stenosis; mouse model; subglottic stenosis; trachea