Fibroblasts in Hypoxic Conditions Mimic Laryngotracheal Stenosis

Linda X. Yin, Kevin M. Motz, Idris Samad, Madhavi Duvvuri, Michael Murphy, Dacheng Ding, Alexander T. Hillel

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: To elucidate the role of hypoxia and inflammatory pathways in the pathogenesis of iatrogenic laryngotracheal stenosis (iLTS). Study Design: (1) Examination of mucosal surface gene expression in human iLTS. (2) In vitro comparison of normal and scar laryngotracheal fibroblasts under normoxic and hypoxic conditions. Setting: Tertiary care hospital in a research university (2012-2016). Subjects and Methods: Brush biopsies were obtained from normal laryngotracheal tissue and scar in iLTS patients; gene expression was compared. Fibroblasts were isolated from normal and scarred trachea and grown in vitro in either a 1% O2 or normoxic environment. Cell growth and gene and protein expression were compared. Statistical analysis utilized a multilevel mixed effects model. Results: Expression of IL-6 (fold change = 2.8, P <.01), myofibroblast marker αSMA (fold change = 3.0, P =.01), and MMP13 (fold change = 5.4, P =.02) was significantly increased in scar biopsy samples as compared to normal. Under hypoxic conditions in vitro, normal laryngotracheal fibroblasts proliferated significantly faster (n = 8, P <.01 each day). Expression of IL-6 (n = 8, fold change = 2.6, P <.01) increased significantly after 12 hours under hypoxia. Expression of αSMA (n = 8, fold change= 2.0, P =.03), COL1 (n = 8, fold change = 1.1, P =.03), and MMP13 (n = 8, fold change = 1.6, P =.01) increased significantly after 48 hours under hypoxia. Scar fibroblasts also proliferated significantly faster under hypoxic conditions but did not display the same expression profile. Conclusion: Human iLTS scar has a myofibroblast phenotype. Under hypoxic conditions in vitro, normal laryngotracheal fibroblasts can transdifferentiate into a similar phenotype. These changes may be mediated by IL-6, a fibrosis-related cytokine.

Original languageEnglish (US)
Pages (from-to)886-892
Number of pages7
JournalOtolaryngology - Head and Neck Surgery (United States)
Volume156
Issue number5
DOIs
StatePublished - May 1 2017

Keywords

  • fibrosis
  • hypoxia
  • iatrogenic
  • laryngotracheal stenosis
  • scar
  • subglottic stenosis

ASJC Scopus subject areas

  • Surgery
  • Otorhinolaryngology

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