title: Bcl-2 overexpression in type II epithelial cells does not prevent hyperoxia-induced acute lung injury in mice.
abstract: Bcl-2 is an anti-apoptotic molecule preventing oxidative stress damage and cell death. We have previously shown that Bcl-2 is able to prevent hyperoxia-induced cell death when overexpressed in a murine fibrosarcoma cell line L929. We hypothesized that its specific overexpression in pulmonary epithelial type II cells could prevent hyperoxia-induced lung injury by protecting the epithelial side of the alveolo-capillary barrier. In the present work, we first showed that in vitro Bcl-2 can rescue murine pulmonary epithelial cells (MLE12) from oxygen-induced cell apoptosis, as shown by analysis of LDH release, annexin V/propidium staining, and caspase-3 activity. We then generated transgenic mice overexpressing specifically Bcl-2 in lung epithelial type II cells under surfactant protein C (SP-C) promoter (Tg-Bcl-2) and exposed them to hyperoxia. Bcl-2 did not hinder hyperoxia-induced mitochondria and DNA oxidative damage of type II cell in vivo. Accordingly, lung damage was identical in both Tg-Bcl-2 and littermate mice strains, as measured by lung weight, bronchoalveolar lavage, and protein content. Nevertheless, we observed a significant lower number of TUNEL-positive cells in type II cells isolated from Tg-Bcl-2 mice exposed to hyperoxia compared with cells isolated from littermate mice. In summary, these results show that although Bcl-2 overexpression is able to prevent hyperoxia-induced cell death at single cell level in vitro and ex vivo, it is not sufficient to prevent cell death of parenchymal cells and to protect the lung from acute damage in mice.
authors.affiliation: Department of Pediatrics, Medical School, University of Geneva, Switzerland.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Métrailler-Ruchonnet
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pagano
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Carnesecchi
authors.forename: Karim
authors.initials: K
authors.lastname: Khatib
authors.forename: Pedro
authors.initials: P
authors.lastname: Herrera
authors.forename: Yves
authors.initials: Y
authors.lastname: Donati
authors.forename: Camille
authors.initials: C
authors.lastname: Bron
authors.forename: Constance
authors.initials: C
authors.lastname: Barazzone
mesh_terms: D055371:Acute Lung Injury / Q000209:etiology / Q000517:prevention & control*; D000818:Animals; D017209:Apoptosis; D016923:Cell Death; D002478:Cells, Cultured; D004249:DNA Damage; D004847:Epithelial Cells / Q000145:classification / Q000378:metabolism*; D018496:Hyperoxia / Q000150:complications* / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008168:Lung / Q000378:metabolism* / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008928:Mitochondria / Q000473:pathology; D018384:Oxidative Stress; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2