Pneumologie 2014; 68 - A18
DOI: 10.1055/s-0033-1363111

Regulation of macroautophagy in amiodarone induced pulmonary fibrosis

P Mahavadi 1, I Henneke 1, L Knudsen 2, 3, C Ruppert 1, S Venkatesan 1, G Liebisch 4, RC Chambers 5, K Piskulak 1, M Ochs 2, 3, G Schmitz 4, C Vancheri 6, W Seeger 1, 3, M Korfei 1, A Guenther 1, 3, 7
  • 1University of Gießen Lung Center, Biomedizinisches Forschungszentrum Seltersberg, Gießen
  • 2Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover
  • 3Member of the German Center for Lung Research
  • 4Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Regensburg
  • 5Centre for Inflammation and Tissue Repair, UCL Respiratory, University College London, London, UK
  • 6Department of Clinical and Molecular Biomedicine, University of Catania, Catania, Italy
  • 7Lung Clinic Waldhof-Elgershausen, Greifenstein

Rationale: Amiodarone (AD) is a well known anti arrhythmic drug, limited by its potential side effects. Severe pulmonary toxicity is reported in patients receiving amiodarone even at low doses, most common histological finding being chronic interstitial pneumonia. Amiodarone is known to induce autophagy in some cell types. A potential role for autophagy in the development of lung fibrosis has not been elucidated so far.

Aims: We aimed to establish a murine model of amiodarone induced pulmonary fibrosis and assess the role of autophagy.

Methods: AD or vehicle was instilled intra tracheally into C57BL/6 mice, and sacrificed on days 7, 14, 21 & 28. Lungs were either snap frozen or fixed in formalin. Fibrosis development was shown by hydroxyproline measurement. (MLE)-12 cells and AECII were treated with AD/vehicle and harvested after 8, 16 & 24 hours. Surfactant proteins and markers for autophagy, apoptosis and lysosomal stress were studied by western blotting, immunofluorescence and immunohistochemistry.

Results: Lung fibrosis was observed in AD treated mice from day7. Accumulation of surfactant proteins was observed paralleled by an induction of autophagy (LC3B-II) lysosomal stress (Cathepsin D) and apoptosis (cleaved caspase 3) in AECII. MLE12 and AECII treated with AD showed the presence of LC3 positive vacuolar structures as after AD treatment. AD treated cells showed increase in the apoptotic marker cleaved caspase-3. Conclusion: We conclude that the autophagy pathway might be involved in the development of amiodarone inuced pulmonary fibrosis, but its interplay with apoptosis and lysosomal stress has yet to be clearly studied in this disease.