Characterization of Fibroblasts in Iatrogenic Laryngotracheal Stenosis and Type II Diabetes Mellitus.

Objectives: Iatrogenic laryngotracheal stenosis (iLTS) is the pathological narrowing of the glottis, subglottis, and/or trachea due to scar tissue. Patients with type 2 diabetes mellitus (T2DM) are over 8 times more likely to develop iLTS and represent 26% to 53% of all iLTS patients. In this investigation, we compared iLTS scar‐derived fibroblasts in patients with and without T2DM. Study Design: Controlled ex vivo study. Methods: iLTS scar fibroblasts were isolated and cultured from subglottic scar biopsies in iLTS patients diagnosed with or without type 2 diabetes (non‐T2DM). Fibroblast proliferation, fibrosis‐related gene expression, and metabolic utilization of oxidative phosphorylation (OXPHOS) and glycolysis were assessed. Contractility was measured using a collagen‐based assay. Metabolically targeted drugs (metformin, phenformin, amobarbital) were tested, and changes in fibrosis‐related gene expression, collagen protein, and contractility were evaluated. Results: Compared to non‐T2DM, T2DM iLTS scar fibroblasts had increased α‐smooth muscle actin (αSMA) expression (8.2× increased, P =.020), increased contractility (mean 71.4 ± 4.3% vs. 51.7 ± 16% Δ area × 90 minute−1, P =.016), and reduced proliferation (1.9× reduction at 5 days, P <.01). Collagen 1 (COL1) protein was significantly higher in the T2DM group (mean 2.06 ± 0.19 vs. 0.74 ±.44 COL1/total protein [pg/μg], P =.036). T2DM iLTS scar fibroblasts had increased measures of OXPHOS, including basal respiration (mean 86.7 vs. 31.5 pmol/minute/10 μg protein, P =.016) and adenosine triphosphate (ATP) generation (mean 97.5 vs. 25.7 pmol/minute/10 μg protein, P =.047) compared to non‐T2DM fibroblasts. Amobarbital reduced cellular contractility; decreased collagen protein; and decreased expression of αSMA, COL1, and fibronectin. Metformin and phenformin did not significantly affect fibrosis‐related gene expression. Conclusion: T2DM iLTS scar fibroblasts demonstrate a myofibroblast phenotype and greater contractility compared to non‐T2DM. Their bioenergetic preference for OXPHOS drives their increased contractility, which is selectively targeted by amobarbital. Level of Evidence: NA Laryngoscope, 131:1570–1577, 2021 [ABSTRACT FROM AUTHOR]