Iatrogenic Laryngotracheal Stenosis and Type II Diabetes Mellitus

Characterization of Fibroblasts in Latrogenic 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, 2020