benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Lung-Diseases

LPS (lipopolysaccharide) is one of the major factors that induce acute lung injury. Recently, it was reported that LPS induced disseminated endothelial apoptosis, preceding nonendothelial tissue damage. Caspases play important roles in apoptosis, including tumor necrosis factor-alpha-induced apoptosis, in several systems. We therefore investigated whether the injection of a caspase inhibitor prevents LPS-induced apoptosis and acute lung injury in mice. LPS (30 mg/kg) was administered intravenously to Institute for Cancer Research mice. Electron microscopic findings demonstrated characteristic features of apoptosis in endothelial cells and alveolar epithelial cells. The caspase-3 activity and the number of terminal dUTP nick-end labeling-positive cells in lung tissues were significantly increased after LPS administration. Benzyloxycarbonil-Val-Ala-Asp fluoromethylketone (Z-VAD.fmk), which is a broad-spectrum caspase inhibitor, was injected before and after the administration of LPS. The injection of Z-VAD.fmk suppressed the caspase-3 activity in lung tissues, and significantly decreased the number of terminal dUTP nick-end labeling-positive cells. Furthermore, the survival rate of mice was prolonged significantly by the injection of Z-VAD.fmk. These results indicate that apoptosis may play an important role in acute lung injury, and thus that inhibition of caspase activity may constitute a new therapeutic approach for treatment of this disease.

Topics: Acute Disease; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Caspase 1; Caspase 3; Caspase Inhibitors; Caspases; Cysteine Proteinase Inhibitors; Interleukin-1; Lipopolysaccharides; Lung; Lung Diseases; Mice; Mice, Inbred ICR; Survival Analysis

Mice exposed to 100% O2 die after 3 or 4 d with diffuse alveolar damage and alveolar edema. Extensive cell death is evident by electron microscopy in the alveolar septa, affecting both endothelial and epithelial cells. The damaged cells show features of both apoptosis (condensation and margination of chromatin) and necrosis (disruption of the plasma membrane). The electrophoretic pattern of lung DNA indicates both internucleosomal fragmentation, characteristic of apoptosis, and overall degradation, characteristic of necrosis. Hyperoxia induces a marked increase in RNA or protein levels of p53, bax, bcl-x, and Fas, which are known to be expressed in certain types of apoptosis. However, we did not detect an increased activity of proteases belonging to the apoptosis "executioner" machinery, such as CPP32 (caspase 3), ICE (caspase 1), or cathepsin D. Furthermore, administration of an ICE-like protease inhibitor did not significantly enhance the resistance to oxygen. Additionally, neither p53-deficient mice nor lpr mice (Fas null) manifested an increased resistance to hyperoxia-induced lung damage. These results show that both necrosis and apoptosis contribute to cell death during hyperoxia. Multiple apoptotic pathways seem to be involved in this, and an antiapoptotic strategy does not attenuate alveolar damage.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; bcl-2-Associated X Protein; bcl-X Protein; Blotting, Western; Caspase 1; Caspase 3; Caspase Inhibitors; Caspases; Cathepsin D; Cysteine Proteinase Inhibitors; Fas Ligand Protein; fas Receptor; Gene Expression; Hyperoxia; In Situ Nick-End Labeling; Lung Diseases; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Necrosis; Oxygen; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pulmonary Alveoli; RNA, Messenger; Tumor Suppressor Protein p53