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Published on: January 21, 2020
Azithromycin Prevents Subglottic Stenosis in Mice
Daniel D Ghaderi1, Matthew R Aronson1,2, Amrita Mehta1
1Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Insights
Azithromycin demonstrates potential in treating pediatric subglottic stenosis (SGS) by reducing airway fibrosis and inflammation. This study shows azithromycin prevents pro-fibrotic gene expression and protects mice from developing SGS.
Area of Science:
- Otolaryngology
- Pulmonology
- Pharmacology
Background:
- Pediatric subglottic stenosis (SGS) involves airway narrowing due to pathological fibroblast activity and extracellular matrix deposition.
- Recent observations suggest azithromycin may reduce SGS, potentially by impacting airway infections and the microbiome.
- This study investigates azithromycin's therapeutic effects against SGS.
Purpose of the Study:
- To characterize the immunomodulatory and antibacterial protective effects of azithromycin against subglottic stenosis.
- To assess azithromycin's impact on fibroblast-mediated extracellular matrix production and myofibroblast differentiation.
- To evaluate azithromycin's efficacy in a murine model of SGS.
Main Methods:
- In vitro: Azithromycin's effects on TGF-β1-stimulated fibroblasts were assessed for gene expression (RT-qPCR) and myofibroblast differentiation (α-SMA immunostaining).
- In vivo: Mice were pretreated with intranasal azithromycin before SGS induction via wire brush injury.
- Disease severity and immune cell infiltration were analyzed using histology and immunostaining.
Main Results:
- Azithromycin significantly reduced extracellular matrix and myofibroblast gene expression (COL1A1, LOX, ACTA2) in vitro.
- α-SMA immunostaining showed decreased myofibroblast differentiation in azithromycin-treated fibroblasts.
- In vivo, azithromycin treatment led to reduced lamina propria thickness and altered T-cell infiltration, indicating decreased stenosis.
Conclusions:
- Azithromycin effectively prevents pro-fibrotic gene expression and myofibroblast differentiation.
- The study demonstrates azithromycin's protective effect against the development of subglottic stenosis in a murine model.
- Azithromycin is proposed as a potential therapeutic agent for treating pediatric subglottic stenosis.
Objective:
Pediatric subglottic stenosis (SGS) is characterized by subglottic narrowing which occurs when pathological fibroblasts deposit extracellular matrix that reduces airway patency. Recent clinical observations have suggested that azithromycin may have favorable impacts on SGS reduction while treating airway infections; furthermore, our recent work in mice demonstrated that the airway microbiome influences SGS. In this work, we characterize the protective effect of azithromycin as an immunomodulatory and antibacterial therapeutic against subglottic stenosis.
Methods:
Immunomodulatory and antifibrotic effects of azithromycin were assessed on TGF-β1-stimulated airway fibroblasts at 10 μg/mL for 5 days. Changes in gene expression were quantified by RT-qPCR and myofibroblast differentiation by α-SMA immunostaining. Murine airways were pretreated (2-weeks) with intranasal azithromycin before SGS injury by a twisted wire brush. Disease severity and immune response were characterized by histology and immunostaining for immune cells.
Results:
In vitro, azithromycin treatment of TGF-β1-stimulated fibroblasts exhibited strong reductions in extracellular matrix (COL1A1, LOX) and myofibroblast-related gene expression (ACTA2). Notably, there was a significant reduction in pro-fibrotic expression, which was observed with 10 μg/mL azithromycin. Immunostaining of fibroblasts for α-SMA revealed strong reductions in the number of positive-staining cells and the intensity of each positive cell. In vivo, azithromycin exhibited a significant decrease in lamina propria thickness indicative of reduced stenosis with associated changes in T-cell infiltration.
Conclusions:
Overall, we show azithromycin prevents pro-fibrotic gene expression and myofibroblast differentiation and can help protect mice from developing SGS. This introduces azithromycin as a potential treatment for SGS.
Level Of Evidence:
NA Laryngoscope, 135:409-415, 2025.
