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Updated: Dec 30, 2025
Refined Murine Model of Idiopathic Pulmonary Fibrosis
Published on: June 17, 2025
Azithromycin has enhanced effects on lung fibroblasts from idiopathic pulmonary fibrosis (IPF) patients compared to
Kristina Krempaska1,2,3, Sandra Barnowski1,2, Jacopo Gavini4
1Department of Pulmonary Medicine, Inselspital, Bern University Hospital, University of Bern, CH-3010, Bern, Switzerland.
Background:
Idiopathic pulmonary fibrosis (IPF) is a chronic fatal lung disease without a cure and new drug strategies are urgently needed. Differences in behavior between diseased and healthy cells are well known and drug response can be different between cells isolated from IPF patients and controls. The macrolide Azithromycin (AZT) has anti-inflammatory and immunomodulatory properties. Recently anti-fibrotic effects have been described. However, the anti-fibrotic effects on primary IPF-fibroblasts (FB) directly compared to control-FB are unknown. We hypothesized that IPF-FB react differently to AZT in terms of anti-fibrotic effects.
Methods:
Primary normal human lung and IPF-FB were exposed to TGF-β (5 ng/ml), Azithromycin (50 μM) alone or in combination prior to gene expression analysis. Pro-collagen Iα1 secretion was assessed by ELISA and protein expression by western blot (αSMA, Fibronectin, ATP6V1B2, LC3 AB (II/I), p62, Bcl-xL). Microarray analysis was performed to screen involved genes and pathways after Azithromycin treatment in control-FB. Apoptosis and intraluminal lysosomal pH were analyzed by flow cytometry.
Results:
AZT significantly reduced collagen secretion in TGF-β treated IPF-FB compared to TGF-β treatment alone, but not in control-FB. Pro-fibrotic gene expression was similarly reduced after AZT treatment in IPF and control-FB. P62 and LC3II/I western blot revealed impaired autophagic flux after AZT in both control and IPF-FB with significant increase of LC3II/I after AZT in control and IPF-FB, indicating enhanced autophagy inhibition. Early apoptosis was significantly higher in TGF-β treated IPF-FB compared to controls after AZT. Microarray analysis of control-FB treated with AZT revealed impaired lysosomal pathways. The ATPase and lysosomal pH regulator ATP6V0D2 was significantly less increased after additional AZT in IPF-FB compared to controls. Lysosomal function was impaired in both IPF and control FB, but pH was significantly more increased in TGF-β treated IPF-FB.
Conclusion:
We report different treatment responses after AZT with enhanced anti-fibrotic and pro-apoptotic effects in IPF compared to control-FB. Possibly impaired lysosomal function contributes towards these effects. In summary, different baseline cell phenotype and behavior of IPF and control cells contribute to enhanced anti-fibrotic and pro-apoptotic effects in IPF-FB after AZT treatment and strengthen its role as a new potential anti-fibrotic compound, that should further be evaluated in clinical studies.
Insights
Azithromycin (AZT) shows enhanced anti-fibrotic and pro-apoptotic effects in Idiopathic Pulmonary Fibrosis (IPF) fibroblasts compared to controls. This suggests AZT
Area of Science:
- Pulmonary Medicine
- Cell Biology
- Pharmacology
Background:
- Idiopathic Pulmonary Fibrosis (IPF) is a fatal lung disease lacking effective treatments.
- Fibroblast behavior differs between IPF patients and healthy individuals, impacting drug responses.
- Azithromycin (AZT), a macrolide, possesses anti-inflammatory, immunomodulatory, and potential anti-fibrotic properties.
Purpose of the Study:
- To investigate the anti-fibrotic effects of Azithromycin (AZT) on primary IPF fibroblasts compared to control fibroblasts.
- To determine if IPF fibroblasts exhibit differential responses to AZT treatment.
- To explore the underlying mechanisms, including effects on apoptosis and lysosomal function.
Main Methods:
- Primary human lung fibroblasts (control and IPF) were treated with TGF-β and Azithromycin (AZT).
- Assays included ELISA for pro-collagen Iα1, Western blot for fibrotic markers and autophagy proteins, and microarray analysis.
- Apoptosis and lysosomal pH were analyzed via flow cytometry.
Main Results:
- AZT significantly reduced collagen secretion in TGF-β treated IPF fibroblasts, but not in controls.
- Pro-fibrotic gene expression decreased similarly in both IPF and control fibroblasts after AZT treatment.
- AZT treatment led to increased apoptosis in IPF fibroblasts and impaired lysosomal function in both cell types, more pronounced in IPF cells.
Conclusions:
- IPF fibroblasts demonstrate enhanced anti-fibrotic and pro-apoptotic responses to AZT compared to control fibroblasts.
- Impaired lysosomal function in IPF cells may contribute to these differential effects.
- AZT shows potential as a novel anti-fibrotic compound for IPF, warranting further clinical investigation.
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