Naoki Hagimoto

Protection from lethal apoptosis in lipopolysaccharide-induced acute lung injury in mice by a caspase inhibitor

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.

Expression of apoptosis-regulatory genes in epithelial cells in pulmonary fibrosis in mice.

Up‐regulation of Fas and Fas ligand and excessive apoptosis of bronchiolar and alveolar epithelial cells were identified in bleomycin‐induced pulmonary fibrosis in mice. This study hypothesized that apoptosis‐regulatory genes other than Fas–Fas ligand, such as p53, p21 (Waf1/Cip1), bcl‐2, bcl‐x, and bax, may also participate in epithelial cell apoptosis in this model. The expression of these genes was assessed by reverse transcription polymerase chain reaction (RT‐PCR), RT in situ PCR, or immunohistochemistry. The expression of p53 and p21 mRNA was concurrently up‐regulated in the alveolar epithelial cells at 1 h to 7 days after intratracheal instillation of bleomycin. The expression of bcl‐2 mRNA was weakly up‐regulated at 1 h to 14 days, while the expression level of bcl‐2 protein was not changed. The expression of bcl‐x(L) and bax mRNA was strongly up‐regulated at 1 h to 7 days. The expression of bcl‐x protein was up‐regulated in lymphocytes and macrophages, whereas bax protein was up‐regulated in both epithelial and inflammatory cells. It is concluded that epithelial cell apoptosis in this model may also be induced by the up‐regulation of p53 and bax and by the imbalance between apoptosis‐inducible and ‐inhibitory genes, in addition to the up‐regulation of the Fas–Fas ligand pathway. Copyright

Upregulation of Fas-signalling molecules in lung epithelial cells from patients with idiopathic pulmonary fibrosis

The caspase cascade is an executioner of apoptosis, mediated by Fas. Fas-associating protein with death domain (FADD) interacts with Fas and initiates apoptosis through activating caspase-8. It has previously been demonstrated that the Fas-Fas ligand pathway may be involved in the pathophysiology of idiopathic pulmonary fibrosis (IPF). The aim of this study was to investigate Fas-signalling molecules in epithelial cells in IPF. The immunohistochemistry for FADD and caspase-1 and -3 and terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick endlabelling (TUNEL) methods were performed in lung tissues from 10 patients with IPF obtained by thoracoscopic biopsy and in seven normal lung parenchyma specimens. The induction of caspases expression and activation by Fas-ligation on lung epithelial cell line A549 was also investigated. The immunoreactivity grade for FADD and caspase-1 and -3, and positive signals for TUNEL were significantly increased in epithelial cells of IPF compared with controls. Fas-ligation induced upregulation of caspase-1 and -3 expression in the nucleus and cytoplasm in A549 cells. Procaspase-1, -3, and -8 were activated in apoptotic cells, but not in viable cells. Although direct measurement of the caspase activity in lung epithelial cells of idiopathic pulmonary fibrosis could not be made, these results suggest that the Fas-signalling pathway is upregulated in lung epithelial cells of idiopathic pulmonary fibrosis.

Expression of FasL and Fas Protein and Their Soluble Form in Patients with Hypersensitivity Pneumonitis

Background: Hypersensitivity pneumonitis (HP) is characterized by a lymphocytic alveolitis and loosely formed granulomas in lung biopsy specimens. HP improves or disappears altogether after cessation of antigen exposure. The Fas-Fas ligand (FasL) system is one of the representative systems of apoptosis-signaling receptor molecules, and is involved in various inflammatory diseases. We hypothesized that the Fas-FasL system may be associated with this disorder. Methods: We examined the expression of FasL and Fas proteins in lung tissues from patients with HP using immunohistochemistry. We also measured the soluble form of FasL (sFasL) and sFas levels in serum and bronchoalveolar lavage fluid (BALF) from patients with HP using enzyme-linked immunosorbent assay (ELISA). Furthermore, we also measured the cytotoxic activity of BALF sFasL in vitro. Results: FasL was detected in infiltrating mononuclear cells, and Fas was detected in infiltrating mononuclear cells, alveolar macrophages, and epithelioid cells in HP, whereas FasL was not detected and Fas was detected in few alveolar macrophages in controls. The levels of sFasL and sFas in BALF, but not in serum, were significantly increased in HP compared with controls. BALF of HP that included high levels of sFasL had no cytotoxic activity for bronchiolar epithelial cells in vitro. Conclusions: In HP, there is an upregulation of FasL and Fas in lung tissues. Since there is no incidence of apoptosis and no cytotoxic activity for lung epithelial cells in BALF from patients with HP, the increased levels of BALF sFasL and sFas may reflect the activation and sequestration of inflammatory cells rather than apoptosis.

Expression of p53, p21 (Waf1/Cip1/Sdi1) and Fas antigen in collagen vascular and granulomatous lung diseases

Fas is expressed in various cells and transduces the cell death signal. p21 is a mediator of p53-dependent G1 arrest associated with deoxyribonucleic acid (DNA) damage. The upregulation of p53 and p21 associated with DNA damage in idiopathic pulmonary fibrosis has been described previously. In this study, p53, p21, and Fas expression and DNA damage were examined in interstitial pneumonia associated with collagen vascular diseases (CVD-IP). DNA damage was assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end-labelling (TUNEL) and p53, p21 and Fas proteins were detected by immunohistochemistry in 13 cases of CVD-IP, 13 of sarcoidosis, seven of hypersensitivity pneumonitis (HP) and eight control patients with normal lung parenchyma. TUNEL-positive signals were found in bronchiolar or alveolar epithelial cells in 11 of 13 (85%) specimens of CVD-IP, but not in sarcoidosis, HP or controls, except for a case of chronic HP with pulmonary fibrosis. p53, p21 and Fas were detected in bronchiolar or alveolar epithelial cells in nine (69%), 10 (77%) and 12 (92%) of 13 specimens of CVD-IP, respectively, but not in sarcoidosis, HP or controls, except for a case of chronic HP. These results suggest that the upregulation of p53, p21 and Fas in bronchiolar and alveolar epithelial cells associated with deoxyribonucleic acid damage may participate in the process of pulmonary fibrosis in interstitial pneumonia associated with collagen vascular diseases and chronic hypersensitivity pneumonitis.

Expression of B7–1, B7–2, and Interleukin–12 in Anti–Fas Antibody–Induced Pulmonary Fibrosis in Mice

Background: We have previously reported that the inhalation of anti–Fas antibody induced pulmonary fibrosis in mice. To induce an effective immune response, antigen–presenting cells have to not only present antigenic peptide with MHC molecules to T lymphocytes, but also express B7 costimulating molecules. The purpose of this study is to investigate whether B7 family costimulating molecules and interleukin–12 (IL–12), which primarily promote cellular immunity, are associated with anti–Fas antibody–induced pulmonary fibrosis. Methods: We examined the expression of B7–1, B7–2, and IL–12 using the revese transcription–polymerase chain reaction (RT–PCR), RT–in situ PCR, and immunohistochemistry. Results: We observed the upregulation of B7–1, B7–2, and IL–12 p40 mRNA after anti–Fas antibody inhalation. B7–2 and IL–12 p40 mRNA appeared to be expressed in mononuclear cells, while B7–1 mRNA and protein were expressed in bronchiolar epithelial cells as well as macrophages. Conclusion: These findings indicate that the T–cell–mediated immune response in this model involved the upregulation of B7–1, B7–2, and IL–12, and that the aberrant expression of B7–1 in bronchiolar epithelial cells may induce autoreactive T cell proliferation against themselves.