Dysregulated Macrophages Are Present in Bleomycin-Induced Murine Laryngotracheal Stenosis. (August 2015)

• Record Type: Journal Article
• Authors: Hillel, Alexander T.; Samad, Idris; Ma, Garret; Ding, Dacheng; Sadtler, Kaitlyn; Powell, Jonathan D.; Lane, Andrew P.; Horton, Maureen R.
• Is Part Of: Otolaryngology--head and neck surgery. Volume 153:Number 2(2015:Aug.)
• Page Start: 244
• Page End: 250
• Publication Date: 2015-08
• Subjects: trachea -- laryngotracheal stenosis -- subglottic stenosis -- mouse model -- airway epithelial injury; Head -- Surgery -- Periodicals; Neck -- Surgery -- Periodicals; Otolaryngology -- Periodicals; 617.51
• DOI: 10.1177/0194599815589106
• Languages: English
• ISSNs: 0194-5998

Abstract

Objective: To define the inflammatory cell infiltrate preceding fibrosis in a laryngotracheal stenosis (LTS) murine model. Study Design: Prospective controlled murine study. Setting: Laboratory. Subjects and 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.