Research

Marked alveolar apoptosis/proliferation imbalance in end-stage emphysema

Fiorella Calabrese¹ , Cinzia Giacometti^1* , Bianca Beghe^2* , Federico Rea^3* , Monica Loy^3* , Renzo Zuin^2* , Giuseppe Marulli^3* , Simonetta Baraldo^2* , Marina Saetta^2* and Marialuisa Valente^1*

¹  Institute of Pathology, University of Padua, Italy

²  Department of Clinical and Experimental Medicine, Section of Respiratory Diseases, University of Padua, Italy

³  Department of Gastroenterological Sciences, Section of Thoracic Surgery, University of Padua, Italy

author email corresponding author email* Contributed equally

Respiratory Research 2005, 6:14doi:10.1186/1465-9921-6-14

Published:	10 February 2005

Abstract

Background

Apoptosis has recently been proposed to contribute to the pathogenesis of emphysema.

Methods

In order to establish if cell fate plays a role even in end-stage disease we studied 16 lungs (9 smoking-associated and 7 α1antitrypsin (AAT)-deficiency emphysema) from patients who had undergone lung transplantations. Six unused donor lungs served as controls. Apoptosis was evaluated by TUNEL analysis, single-stranded DNA laddering, electron microscopy and cell proliferation by an immunohistochemical method (MIB1). The role of the transforming growth factor (TGF)-β1 pathway was also investigated and correlated with epithelial cell turnover and with the severity of inflammatory cell infiltrate.

Results

The apoptotic index (AI) was significantly higher in emphysematous lungs compared to the control group (p ≤ 0.01), particularly if only lungs with AAT-deficiency emphysema were considered (p ≤ 0.01 vs p = 0.09). The proliferation index was similar in patients and controls (1.9 ± 2.2 vs 1.7 ± 1.1). An increased number of T lymphocytes was observed in AAT-deficiency lungs than smoking-related cases (p ≤ 0.05). TGF-β1 expression in the alveolar wall was higher in patients with smoking-associated emphysema than in cases with AAT-deficiency emphysema (p ≤ 0.05). A positive correlation between TGF-βRII and AI was observed only in the control group (p ≤ 0.005, r² = 0.8). A negative correlation was found between the TGF-β pathway (particularly TGF-βRII) and T lymphocytes infiltrate in smoking-related cases (p ≤ 0.05, r² = 0.99)

Conclusion

Our findings suggest that apoptosis of alveolar epithelial cells plays an important role even in end-stage emphysema particularly in AAT-deficiency disease. The TGFβ-1 pathway does not seem to directly influence epithelial turnover in end-stage disease. Inflammatory cytokine different from TGF-β1 may differently orchestrate cell fate in AAT and smoking-related emphysema types.