The p53-Mdm2 association in epithelial cells in idiopathic pulmonary fibrosis and non-specific interstitial pneumonia.

BACKGROUND: Wild-type p53 is increased during cellular responses to various stresses. Mdm2, which is induced by p53, regulates p53 protein concentrations through the ubiquitin-proteasome pathway. AIM: To investigate whether the Mdm2 mediated ubiquitination of p53 is associated with epithelial cell apoptosis in idiopathic pulmonary fibrosis (IPF). METHODS: Immunohistochemistry and western blot analysis were carried out on lung samples obtained by lung biopsy from patients with IPF and non-specific interstitial pneumonia (NSIP). RESULTS: The expression of p53, phosphorylated p53, Mdm2, p21, and Bax was upregulated in epithelial cells from patients with IPF and NSIP compared with normal lung parenchyma. Except for p21, there was a significant increase in the expression of these factors in IPF compared with NSIP. In addition, the number of apoptotic cells and the number of p53 and Bax positive cells was increased compared with controls. p53 conjugated with Mdm2 was decreased in IPF compared with NSIP and controls. Ubiquitinated p53 was increased in both IPF and NSIP compared with controls. CONCLUSIONS: Signalling molecules associated with p53 mediated apoptosis may participate in epithelial cell apoptosis, and the attenuation of p53-Mdm2 conjugation and of p53 degradation may be involved in the epithelial cell apoptosis seen in IPF. Augmented epithelial apoptosis in IPF may lead to the poor prognosis compared with NSIP.

The perforin mediated apoptotic pathway in lung injury and fibrosis.

AIMS: The perforin mediated pathway is the major pathway of cytotoxicity induced by activated T cells and natural killer cells, and may be involved in the development of pulmonary fibrosis. METHODS: Perforin and granzyme B expression were examined in idiopathic pulmonary fibrosis by means of immunohistochemistry, and perforin knockout mice were used to examine whether or not perforin mediated cytotoxicity participates in the pathophysiology of bleomycin induced pneumopathy. RESULTS: Perforin and granzyme B expression were upregulated in infiltrating lymphocytes in lung tissue from patients with idiopathic pulmonary fibrosis compared with normal lung parenchyma. Perforin and granzyme B expression were upregulated predominantly in infiltrating mononuclear cells after bleomycin instillation in wild-type mice. Although the development of bleomycin induced pneumopathy was not completely prevented, the pathological grade of inflammation and fibrosis, and the number of apoptotic cells in lung tissue, were significantly decreased in perforin knockout mice compared with wild-type mice. CONCLUSIONS: These results suggest that perforin mediated apoptosis may be associated with the pathophysiology of lung injury and fibrosis.

The role of apoptosis in pulmonary fibrosis.

Pulmonary fibrosis is a common response to various injuries to the lung. The resolution of a fibroproliferative response after lung injury is key to survival. Although there are various initiating factors or causes, the terminal stages are characterized by proliferation and progressive accumulation of connective tissue replacing normal functional parenchyma. Conventional therapy consisting of glucocorticoids or immunosuppressive drugs is usually ineffective in preventing progression of fibrosis. Further understanding of the molecular mechanisms of endothelial and epithelial cell injury, inflammatory reaction, fibroblast proliferation, collagen deposition and tissue remodeling, should lead to the development of effective treatments against pulmonary fibrosis. Evidence that apoptosis plays an important role in the pathophysiology of pulmonary fibrosis has been accumulated. We overview the role of apoptosis in each of the pathogenic events which have emerged from animal models and human tissue studies.

Retinoic acid fails to reverse emphysema in adult mouse models.

BACKGROUND: Previous work has shown that all-trans-retinoic acid reverses elastase induced emphysema in rats. Since there is currently no effective treatment for pulmonary emphysema, the effect of retinoic acid should be further investigated in other adult species. A study was undertaken using two murine models of emphysema to evaluate the effect of retinoic acid. METHODS: The models used were an elastase induced emphysema model for acute alveolar destruction and a tumour necrosis factor (TNF)-alpha transgenic mouse which exhibits chronic air space enlargement, loss of elastic recoil, increased lung volume, and pulmonary hypertension comparable to human pulmonary emphysema. All-trans-retinoic acid (2 mg/kg) was injected for 12 successive days after the establishment of emphysema. The effects of treatment were evaluated using physiological and morphometric analyses. RESULTS: In contrast to the rat, administration of all-trans-retinoic acid in these murine models did not improve the emphysema. Moreover, worsening of emphysema was observed in TNF-alpha transgenic mice treated with all-trans-retinoic acid. The level of keratinocyte chemoattractant (KC), a CXC chemokine, in bronchoalveolar lavage fluid was increased in TNF-alpha transgenic mice following retinoic acid treatment. These data raise the possibility that retinoic acid causes deterioration of emphysema by promoting inflammation in this model. CONCLUSIONS: In these models, retinoic acid did not show positive effects on emphysema. The effect of retinoic acid in the treatment of pulmonary emphysema remains controversial, and further studies are required to determine its physiological effects under a variety of experimental conditions.

Oxidative stress in lung epithelial cells from patients with idiopathic interstitial pneumonias.

Lung epithelial cells are a primary target for reactive oxygen species (ROS). ROS can cause oxidative deoxyribonucleic acid modification, such as 8-hydroxy-deoxyguanosine (8-OHdG). A human homologue of the MutT protein (hMTH1) prevents this modification. Mitochondria are the most important cellular source of ROS and may be susceptible to oxidative damage. The purpose of this study is to investigate oxidative stress and mitochondrial damage in lung epithelial cells from idiopathic interstitial pneumonias (IIPs). The authors analysed 8-OHdG, hMTH1, and mitochondrial proteins on lung specimens from 13 patients with IlPs consisted of eight patients with usual interstitial pneumonia and five patients with nonspecific interstitial pneumonia using Western blot analysis and immunohistochemistry. Immunoreactivity for 8-OHdG and hMTH1 was significantly increased in the lung epithelial cells from patients with IIPs compared with controls. The expression of hMTH1 was localised in the nuclear and cytoplasmic, but not the mitochondrial, fraction of lung homogenates. Immunoreactivity for mitochondrial protein and cytochrome c oxidase complex subunit IV was increased in the lung epithelial cells from patients with IIPs compared with controls. The current study concludes that oxidative stress may participate in epithelial cell damage in idiopathic interstitial pneumonia, and that increased mitochondrial mass may associate with increased reactive oxygen species production in idiopathic interstitial pneumonia.

Resistance to Fas-mediated apoptosis in human lung fibroblast.

The current authors have demonstrated previously that epithelial cell apoptosis, induced by the Fas-Fas ligand pathway, might be involved in fibrosing lung diseases. Whereas lung epithelial cells are sensitive to the Fas-mediated apoptosis, lung fibroblasts may be resistant to Fas-mediated apoptosis and replace damaged epithelial cells. The WI-38 lung fibroblast cell line and primary lung fibroblasts were used to examine the resistant to Fas-mediated apoptosis and the association of anti-apoptotic proteins with this resistance. The administration of agonistic anti-Fas antibody (CH-11) or cycloheximide alone did not induce apoptosis, whereas the co-administration of CH-11 with cycloheximide induced apoptosis in WI-38 cells, in which caspase-8 and -3, but not -9, were activated, and X chromosome-linked inhibitor of apoptosis (ILP) and FLICE-like inhibitor protein (FLIP(L)), but not bcl-xL and bcl-2, were remarkably down regulated. Primary lung fibroblasts were also resistant to Fas-mediated apoptosis, and ILP and FLIP appeared to be involved in this resistance. Furthermore, the results of immunohistochemistry demonstrated that fibroblasts expressed ILP and FLIP(L) proteins in lung tissues from patients with idiopathic pulmonary fibrosis. These results suggest that anti-apoptotic proteins such as X chromosome-linked inhibitor of apoptosis and FLICE-like inhibitor protein may play an important role in preventing Fas-mediated apoptosis in lung fibroblasts, and participate in the development of pulmonary fibrosis.

KL-6, surfactant protein A and D in bronchoalveolar lavage fluid from patients with pulmonary sarcoidosis.

BACKGROUND: KL-6, and surfactant protein A (SP-A) and surfactant protein D (SP-D) derived from alveolar type II cells and/or bronchiolar epithelial cells have been reported to be useful markers for interstitial lung diseases. OBJECTIVE: The aim of this study was to measure the levels of these molecules in bronchoalveolar lavage fluid (BALF) from patients with pulmonary sarcoidosis to investigate their relationship with other markers of inflammatory activity. METHODS: We measured KL-6, SP-A and SP-D levels in BALF from patients with pulmonary sarcoidosis using an ELISA. RESULTS: KL-6 and SP-D, but not SP-A levels were significantly increased in pulmonary sarcoidosis compared with controls. KL-6, SP-A and SP-D levels were significantly correlated with each other. KL-6 and SP-D levels were relatively and significantly correlated with the percentage of lymphocytes in BALF. KL-6, SP-D, but not SP-A levels were significantly correlated with the concentration of albumin in BALF. There was no significant correlation between KL-6, SP-A, or SP-D levels and chest X-ray findings, angiotensin-converting enzyme levels, or CD4/CD8 ratio in BALF. CONCLUSIONS: We conclude that KL-6 and SP-D levels in BALF were increased in pulmonary sarcoidosis. Since these markers are specifically derived from epithelial cells, it is considered that KL-6 and SP-D levels are reflecting damage or release of these markers from epithelial cells due to the inflammatory response.

Attenuation of bleomycin-induced pneumopathy in mice by monoclonal antibody to interleukin-12.

We previously demonstrated essential roles of the Fas-Fas ligand (FasL) pathway in bleomycin-induced pneumopathy in mice. T lymphocytes and natural killer cells express FasL on activation and use it as a cytotoxic effector molecule. Because interleukin (IL)-12 is known to play a critical role in cell-mediated immunity, we investigated whether anti-IL-12 antibody treatment suppresses the development of this model. The anti-IL-12 antibody treatment decreased the number of apoptotic cells and the degree of inflammation and fibrosis in lung tissue. The results of RT-PCR showed that IL-12p40, IL-12 receptor (R) beta2, interferon-gamma, tumor necrosis factor-alpha and FasL mRNAs were upregulated after bleomycin instillation. The upregulation of FasL, IL-12Rbeta2, and tumor necrosis factor-alpha mRNA expression in lung tissue was suppressed by anti-IL-12 antibody treatment. The results of enzyme-linked immunosorbent assay showed that the levels of IL-12p40, but not of IL-12p70, were increased in lung tissue after bleomycin instillation. Although the increase in IL-12Rbeta2 mRNA levels suggests that the T helper type 1 cell response may participate in lung injury, the increase in IL-12p40 supports T helper type 2 cell predominance in the fibrotic process of this model. The administration of anti-IL-12 antibody could be a novel therapy against lung injury and pulmonary fibrosis.

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.

Attenuation of bleomycin-induced pneumopathy in mice by a caspase inhibitor.

Caspases have been implicated in the effector process of apoptosis in several systems including the Fas-Fas ligand pathway. We previously demonstrated that excessive apoptosis of lung epithelial cells and the Fas-Fas ligand pathway were essential in the pathogenesis of bleomycin-induced pneumopathy in mice. Therefore, the purpose of this study was to investigate whether a caspase inhibitor could prevent the development of this model. The expression of caspase-1 and caspase-3 was upregulated on lung epithelial cells, alveolar macrophages, and infiltrating inflammatory cells in this model. We demonstrated that a broad-spectrum caspase inhibitor, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone, decreased the caspase-1- and caspase-3-like activity, the number of apoptotic cells, the pathological grade of lung inflammation and fibrosis, and the hydroxyproline content in lung tissues in this model. We conclude that caspase inhibitors could be a new therapeutic approach against lung injury and pulmonary fibrosis.

Molecular mechanisms of pulmonary fibrosis and current treatment.

Pulmonary fibrosis is a common response to various insults or injuries to the lung. Although there are various initiating factors or causes, the terminal stages are characterized by proliferation and progressive accumulation of connective tissue replacing normal functional parenchyma. The pathogenesis of pulmonary fibrosis includes endothelial and epithelial cell injury, production of inflammatory cells and their mediators, and fibroblast activation. Conventional therapy consisting of glucocorticoids or cytotoxic drugs is usually ineffective in preventing progression of the disease. Further understanding of the molecular mechanisms of endothelial and epithelial cell injury, inflammatory reaction, fibroblast proliferation, collagen deposition and lung repair, should lead to the development of effective treatments against pulmonary fibrosis. Accordingly, this review summarizes recent progress made in understanding the molecular mechanisms of pulmonary fibrosis. A detailed discussion is presented regarding each of the potential new therapies which have emerged from the animal models of pulmonary fibrosis and which have been developed through advances in cellular and molecular biology.

[An autopsy case of idiopathic interstitial pneumonia with diffuse alveolar hemorrhage due to acute exacerbation].

There has hitherto been no report describing idiopathic interstitial pneumonia associated with diffuse alveolar hemorrhage, but we herein report one such rare case. A 75-year-old man who had received a diagnosis of idiopathic interstitial pneumonia had been followed in our hospital since 1995, and had been treated with cyclophosphamide since September 1999. He discontinued taking cyclophosphamide without informing us, and two months later he was admitted to our hospital with deterioration of dyspnea on September 13, 2000. Since chest radiography and CT findings demonstrated alveolar infiltrates in the right middle lung field, he was treated with antibiotic agents. Although no deterioration of symptoms occurred, on September 14 he began to suffer rapidly progressive dyspnea accompanied with production of bloody sputum, which eventually developed into full-blown hemoptysis in the evening of September 15. He died of respiratory failure early the next morning. The autopsy findings demonstrated diffuse alveolar hemorrhage, diffuse alveolar damage, interstitial pneumonia, and pulmonary fibrosis.

[A case of sarcoidosis involving multiple organs that showed significant improvement as the serum KL-6 level fell after steroid therapy].

Pulmonary sarcoidosis was diagnosed by transbronchial lung biopsy in a 27-year old man admitted to our hospital in September 1996. In October 1999, bilateral parenchymal findings on chest radiography and the results of pulmonary function tests had significantly deteriorated compared with those of three years before. Since skin, heart, liver, and spleen lesions were also detected, this patient was treated with corticosteroids. The lung parenchymal lesions and the pulmonary function as well as the abnormal findings in other organs showed significantly improvement along with a decrease of the KL-6 level after steroid therapy.

Lack of a relation between serum potassium concentration and exercise hyperpnea in patients with chronic heart disease.

Exertional dyspnea, a major symptom of patients with chronic heart failure, mainly stems from an abnormally high ventilatory response to exercise. However, there has been considerable controversy surrounding the mechanisms of respiratory control during exercise, especially regarding the role of serum potassium. We investigated the relation between serum potassium concentration [K+] and ventilation (VE) during exercise before and after oral supplements of potassium chloride in cardiac patients. Thirteen patients with chronic heart disease performed a 6-min constant-work-rate exercise (65.8+/-11.1 W) with respiratory gas measurements before initiating oral supplements of potassium chloride, 4 weeks after continued supplements, and 4 weeks after discontinuing supplements. Blood was sampled from a forearm vein at rest before exercise and at the end of exercise for measurement of [K+] and blood gases. The [K+] at rest was 3.66+/-0.30 mmol/L before oral supplements of potassium and significantly increased to 4.08+/-0.31 mmol/L (p<0.01) after supplements. In spite of the significant increases in the [K+], resting VE was not changed. While serum [K+] during exercise was significantly higher after potassium supplements than before, exercise VE was not influenced by the changes in [K+] throughout the study period. The findings of the present study strongly suggest that the chronic increase in the serum [K+] has no influence on the resting or exercise VE in patients with heart disease.

Soluble form of fas and fas ligand in BAL fluid from patients with pulmonary fibrosis and bronchiolitis obliterans organizing pneumonia.

STUDY OBJECTIVES: The Fas-Fas ligand (FasL) pathway is a representative system of apoptosis-signaling receptor molecules. We previously described that this pathway may play an important role in the pathogenesis of fibrosing lung diseases. In this study, we hypothesized that soluble form of Fas (sFas) and FasL (sFasL) may also be associated with this disorder. MEASUREMENTS AND RESULTS: We measured sFas and sFasL levels in BAL fluid (BALF) from patients with idiopathic pulmonary fibrosis (IPF), interstitial pneumonia associated with collagen vascular diseases (CVD-IP), and bronchiolitis obliterans organizing pneumonia (BOOP), using enzyme-linked immunosorbent assay. BALF from all patients was obtained before prednisolone therapy. sFasL levels were relatively increased in IPF patients (p = 0.084), and significantly increased in CVD-IP patients (p < 0.05) and BOOP patients (p < 0.05), compared with control subjects. BALF sFasL levels were elevated in the IPF or CVD-IP subgroups with an indication for prednisolone therapy, compared with those without an indication for therapy. The BALF sFasL level in IPF patients was correlated with the number of total cells and lymphocytes. The BALF sFasL level in BOOP patients was relatively or significantly correlated with the number of total cells or lymphocytes, respectively. The BALF sFas level was significantly increased in BOOP patients, but not in IPF or CVD-IP patients. CONCLUSIONS: We conclude that BALF sFasL levels may be associated with the accumulation of inflammatory cells and reflect the degree of lymphocyte alveolitis in IPF. The elevation of sFasL may be associated with the deterioration of IPF and CVD-IP. The elevation of the BALF sFas level may abrogate the cytotoxicity of FasL in BOOP patients, which may be associated with better prognosis of BOOP, compared with IPF or CVD-IP.

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 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.

Analysis of Fas and Fas ligand expression and function in lung cancer cell lines.

The aim of this study was to investigate the expression of Fas and Fas ligand (FasL) and to determine the significance of these molecules in lung cancer cell lines. Immunoblotting, RT-PCR and flow cytometric analyses were carried out to measure the expression of Fas and FasL and to examine their interactions and effects on cell growth and apoptosis. Fas and FasL were co-expressed in most of the cell lines but to varying degrees. Apoptosis induced by the agonistic anti-Fas antibody was significantly correlated with Fas expression (P=0.0075), whereas cisplatin-induced apoptosis was not. Upregulation of Fas and FasL expression by the administration of cisplatin was found in 7 of 11 (64%) and 9 of 11 (82%) cell lines, respectively. However, cisplatin-induced apoptosis was not suppressed by antagonistic anti-FasL antibody. Thus, our data indicated that Fas and FasL were co-expressed in lung cancer cell lines, and that Fas ligation induced by agonistic anti-Fas antibody is functional and induced apoptosis that was dependent on the levels of Fas expression. In contrast, Fas-FasL interactions appeared to be non-functional. Furthermore, our results suggest that cisplatin-induced apoptosis in lung cancer cells was independent of the Fas-FasL interaction.

B7-1, B7-2 and class II MHC molecules in idiopathic pulmonary fibrosis and bronchiolitis obliterans-organizing pneumonia.

Interstitial lung diseases are thought to be associated with the infiltration of activated T-lymphocytes. To induce an effective immune response, antigen-presenting cells have to not only present antigenic peptide with major histocompatibility complex (MHC) molecules to T-lymphocytes but also express B7 molecules. Therefore, the expression of B7-1, B7-2 and class II MHC molecules was investigated in lung tissues from patients with idiopathic pulmonary fibrosis (IPF) and bronchiolitis obliterans-organizing pneumonia (BOOP), and in normal lung parenchyma as a control, using immunohistochemical localization. B7-1 and B7-2 were aberrantly expressed in bronchiolar and alveolar epithelial cells, and class II MHC molecules were also aberrantly expressed in bronchiolar epithelial cells in IPF. B7-1 was aberrantly expressed in bronchiolar epithelial cells in BOOP. There was no significant difference in the expression of these proteins in alveolar macrophages between IPF and control subjects. However, B7-2 and class II MHC molecule expression in alveolar macrophages was decreased in BOOP compared with that in control subjects. Expression of CD28 and CTLA4, receptors for B7 molecules, was detected in infiltrating lymphocytes in lung tissues in IPF and BOOP. It was concluded that bronchiolar and alveolar epithelial cells may actively participate in the pathophysiology of idiopathic pulmonary fibrosis through the aberrant expression of B7 and class II major histocompatibility complex molecules. The dysregulation of these molecules in epithelial cells may lead to the activation of autoreactive T-lymphocytes, which might contribute to the pathogenesis of fibrosing lung diseases.

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.