An Autopsy Case of COVID-19 with New Diffuse Pulmonary Ossification.

We present the case of a 61-year-old man who developed coronavirus disease 2019 (COVID-19) and died during treatment for relapsing polychondritis. The patient was intubated and treated with steroid pulse therapy, remdecivir, antibacterial agents, baricitinib, and tocilizumab. However, his respiratory condition worsened, and he died 108 days after disease onset. An autopsy revealed diffuse alveolar damage in the fibrotic phase in all lung lobes, diffuse pulmonary ossification, and cytomegalovirus-infected cells in the middle lobe of the right lung. We herein discuss the clinical features and pathological findings of COVID-19 in immunosuppressed patients.

Correlation of 4-meter gait speed with clinical indicators of chronic obstructive pulmonary disease.

BACKGROUND: Measuring daily physical activity and exercise capacity is recommended in the routine care of patients with chronic obstructive pulmonary disease (COPD). The 4-m gait speed (4mGS) is simple and effective in stratifying patients according to exercise performance, dyspnea, health status, and prognosis. We assessed the reliability of the 4mGS as a clinical marker by examining its association with established clinical indicators among hospitalized patients with COPD. METHODS: This retrospective study included 78 patients hospitalized with COPD (mean age: 76.3 ± 0.9 years; males, n = 69) between January 2016 and June 2018 who were assessed using the 4mGS and divided into slow (<0.8 m/s) and normal (≥0.8 m/s) 4mGS groups. Clinical characteristics were compared, including death during the observation period, time to first exacerbation, and long-term oxygen therapy requirement. RESULTS: There were strong relationships between 4mGS performance, the 6-min walk test (R = 0.70; p < 0.0001), and the modified Medical Research Council dyspnea scale (R = 0.68; p < 0.0001) among the 78 patients. The slow 4mGS group had a higher frequency of death during the observation period (p = 0.0095) and a greater requirement for long-term oxygen therapy (p = 0.0063). The 4mGS correlated with inspiratory capacity (IC) and IC/total lung capacity ratios, which are respiratory failure indicators. CONCLUSIONS: The 4mGS is a simple and easy method of assessing the physical condition as well as estimating the prognosis of patients with COPD, and may serve as a useful marker in home medical treatment or clinical settings.

The Evaluation of the Sputum Antigen Kit in the Diagnosis of Pneumococcal Pneumonia.

Objective A previously developed sputum antigen detection kit for Streptococcus pneumoniae enabled the early diagnosis of pneumococcal pneumonia using sputum samples. We conducted a prospective study to compare the sensitivity of the sputum and urinary antigen kits. Methods Pneumonia patients who were treated from April 2014 to September 2015 were recruited for the present study. Patients with pneumococcal pneumonia who could not participate in the prospective arm of the study were analyzed in the retrospective arm. Results Nine of the 69 participants in the prospective study had pneumococcal pneumonia. The sputum antigen kit results correlated well with the sputum culture results. The sensitivity of the sputum antigen kit was 88.9% (8/9), which was higher than that of the urinary antigen kit (5/9; 55.6%). When patients from the retrospective arm of the study were included, the sensitivity of the sputum culture was 93.5% (29/31), which was significantly higher than that of the urinary antigen kit (19/31; 60.6%). False positives were obtained using the sputum antigen kit in four cases. Three of the four false positives were suspected to have resulted from the administration of antibiotics prior to the use of the kit; the remaining case likely occurred due to a false reaction to S. milleri-induced pyothorax. Conclusion Collectively, our findings suggest that the sputum antigen kit has a higher sensitivity for detecting S. pneumoniae than the urinary antigen kit. However, the prior administration of antibiotics can render the sputum culture results negative or lead to a false-positive result.

Prognostic value of serial serum KL-6 measurements in patients with idiopathic pulmonary fibrosis.

BACKGROUND: The prognostic significance of serial measurements of serum KL-6 levels in patients with idiopathic pulmonary fibrosis (IPF) is unclear; hence, it was assessed in this study. METHODS: Medical records of 66 patients with IPF, who were not treated with pirfenidone prior to enrollment, were retrospectively reviewed for information on clinical progress, forced vital capacity (FVC), survival, and serum KL-6 levels. We assessed initial serum levels of KL-6, serial changes in serum KL-6 levels, yearly decline in FVC (ΔFVC), and the rate of decline (%ΔFVC). RESULTS: Patients with increased serum KL-6 levels during follow-up had a significantly steeper decline in ΔFVC than those with no KL-6 increase (-201 vs. -50.7ml/year; p=0.0001). Patients with both initial serum KL-6 ≥1000U/ml and serial increases in serum KL-6 had the steepest decline, while those with both initial serum KL-6 <1000ml and no serial increases in KL-6 had the least decline in ΔFVC and %ΔFVC. Relative to the non-increased KL-6 group, survival in the increased KL-6 group tended to be poorer (p=0.0530). Patients with both initial serum KL-6 values <1000U/ml and no serial increase in KL-6 had more favorable prognoses than those with serial increases in KL-6 or initial serum KL-6 values ≥1000U/ml (p<0.0044). Prognosis was significantly poorer in patients with serial KL-6 changes >51.8U/ml/year than in those with serial KL-6 changes <51.8U/ml/year (p=0.0009). CONCLUSION: Thus, serial serum KL-6 measurements can be useful for assessing prognosis in patients with IPF.

Heterogeneous clinical features in patients with pulmonary fibrosis showing histology of pleuroparenchymal fibroelastosis.

BACKGROUND: The histological pattern of pleuroparenchymal fibroelastosis (PPFE) is well defined, but its clinical features remain unclear. METHODS: We retrospectively examined the predominantly involved lung-fields (based on abnormal opacities on computed tomography [CT] images), and the initial value and annual decline of respiratory function in patients with pulmonary fibrosis presenting with histologically confirmed PPFE. RESULTS: Thirteen female and nine male subjects were included. Eleven interpreters independently analyzed 231 CT image series. One-third of the CT series (78/231) was interpreted as demonstrating equal involvement of the upper and lower lung fields, i.e., six out of 21 patients had equal involvement of the upper and lower lung fields, based on a majority decision of the interpreters. The residual volume/total lung capacity (RV/TLC) was increased and correlated inversely with forced vital capacity (FVC) at the initial measurement. FVC followed two patterns of decline over time: a gradual decline over a follow-up period of more than 6 years (-55mL/year, R(2)=0.799), and a relatively rapid decline over a shorter period (-364mL/year, R(2)=0.855) as determined by mixed-effect linear regression. CONCLUSIONS: The predominantly involved sites seen on CT images of PPFE were not limited to the upper lobes. In some cases, upper lung fields were predominantly involved, but in other cases, both upper and lower lung fields were equally involved. Two patterns of FVC decline exists: a rapid decline over a short period and a slow decline over a longer period, suggesting that the disease follows a heterogeneous clinical course.

Histological evolution of pleuroparenchymal fibroelastosis.

AIMS: To investigate the histological evolution in the development of pleuroparenchymal fibroelastosis (PPFE). METHODS AND RESULTS: We examined four patients who had undergone surgical lung biopsy twice, or who had undergone surgical lung biopsy and had been autopsied, and in whom the histological diagnosis of the first biopsy was not PPFE, but the diagnosis of the second biopsy or of the autopsy was PPFE. The histological patterns of the first biopsy were cellular and fibrotic interstitial pneumonia, cellular interstitial pneumonia (CIP) with organizing pneumonia, CIP with granulomas and acute lung injury in cases 1, 2, 3, and 4, respectively. Septal elastosis was already present in the non-specific interstitial pneumonia-like histology of case 1, but a few additional years were necessary to reach consolidated subpleural fibroelastosis. In case 3, subpleural fibroelastosis was already present in the first biopsy, but only to a small extent. Twelve years later, it was replaced by a long band of fibroelastosis. The septal inflammation and fibrosis and airspace organization observed in the first biopsies were replaced by less cellular subpleural fibroelastosis within 3-12 years. CONCLUSIONS: Interstitial inflammation or acute lung injury may be an initial step in the development of PPFE.

Randomized phase III trial of erlotinib versus docetaxel as second- or third-line therapy in patients with advanced non-small-cell lung cancer: Docetaxel and Erlotinib Lung Cancer Trial (DELTA).

PURPOSE: To investigate the efficacy of erlotinib versus docetaxel in previously treated patients with advanced non-small-cell lung cancer (NSCLC) in an epidermal growth factor receptor (EGFR) -unselected patient population. PATIENTS AND METHODS: The primary end point was progression-free survival (PFS). Secondary end points included overall survival (OS), response rate, safety, and analyses on EGFR wild-type tumors. Patients with stage IIIB or IV NSCLC, previous treatment with one or two chemotherapy regimens, evaluable or measurable disease, and performance status of 0 to 2 were eligible. RESULTS: From August 2009 to July 2012, 150 and 151 patients were randomly assigned to erlotinib (150 mg daily) and docetaxel (60 mg/m(2) every 3 weeks), respectively. EGFR wild-type NSCLC was present in 109 and 90 patients in the erlotinib and docetaxel groups, respectively. Median PFS for erlotinib versus docetaxel was 2.0 v 3.2 months (hazard ratio [HR], 1.22; 95% CI, 0.97 to 1.55; P = .09), and median OS was 14.8 v 12.2 months (HR, 0.91; 95% CI, 0.68 to 1.22; P = .53), respectively. In a subset analysis of EGFR wild-type tumors, PFS for erlotinib versus docetaxel was 1.3 v 2.9 months (HR, 1.45; 95% CI, 1.09 to 1.94; P = .01), and OS was 9.0 v 10.1 months (HR, 0.98; 95% CI, 0.69 to 1.39; P = .91), respectively. CONCLUSION: Erlotinib failed to show an improvement in PFS or OS compared with docetaxel in an EGFR-unselected patient population.

Combined unclassifiable interstitial pneumonia and emphysema: a report of two cases.

We herein report two cases of combined pulmonary fibrosis and emphysema (CPFE), whose histological patterns of lung pathology could not be categorized into any subset of idiopathic interstitial pneumonias(IIPs). Case 1 was a 62-year-old man, who presented with dyspnea on exertion and cough. Case 2 was a 51-year-old man with a dry cough. The CT findings of both cases fit the definition of CPFE. Surgical lung biopsies of both patients revealed alveolar septal widening due to collagen deposition, with emphysema and respiratory bronchiolitis mainly in the subpleural parenchyma. These cases suggest that the fibrosis of CPFE includes smoking-related interstitial fibrosis other than the known histological patterns of IIPs.

Recombinant human erythropoietin reduces epithelial cell apoptosis and attenuates bleomycin-induced pneumonitis in mice.

BACKGROUND AND OBJECTIVE: Erythropoietin (EPO) has recently been demonstrated to have a tissue protective role by acting as an anti-apoptotic agent in various tissues, such as brain, spinal cord, heart and kidney. The purpose of this study was to determine whether human recombinant EPO reduces epithelial cell apoptosis and attenuates bleomycin-induced pneumonitis in mice. METHODS: Bleomycin was instilled intratracheally into C57BL/6 mice. Recombinant human EPO or saline was injected intraperitoneally, daily from day 5 to day 13 after bleomycin instillation. RESULTS: EPO receptor was expressed in bronchiolar and alveolar type II cells. At 14 days after instillation, the number of terminal uridine deoxynucleotidyl transferase nick end-labelled positive cells in the lung was decreased, and the histological degree of inflammation and fibrosis was attenuated in mice injected with EPO compared with controls. Expression of phosphorylated Akt and Erk, which are thought to mediate the survival signalling pathway induced by EPO, tended to be increased in lung tissues from mice treated with EPO compared with those from mice treated with saline after bleomycin instillation. CONCLUSIONS: As it is likely that EPO protects epithelial cells from injury and apoptosis, EPO administration could be a potential therapeutic strategy for the prevention of lung injury.

Biphasic effects of free radical scavengers against bleomycin-induced pulmonary fibrosis.

Oxidative stress plays a critical role in the development of pulmonary fibrosis. However, the effects of treatment with anti-oxidant agents against pulmonary fibrosis have not yet been thoroughly investigated. In this study, the effect of MCI-186, a novel free radical scavenger, on bleomycin-induced pulmonary fibrosis was investigated. Bleomycin (0.05units/mouse) was administered intratracheally into C57Bl/6 mice. MCI-186 was given to bleomycin-treated mice intraperitoneally from (i) day -3 to day 7, or from (ii) day 10 to day 28 after bleomycin administration in successive days. At 28 days after bleomycin administration, pulmonary fibrosis was then assessed by lung histology and hydroxyproline. MCI-186 inhibited H(2)O(2)-induced DNA damage in bronchial epithelium in vitro. MCI-186 decreased the lipid peroxide content, a marker for DNA damage, in the lung and reduced 8-OHdG positive cells in the lung in vivo. During the early period (day -3 to day 7) administration, MCI-186 partially attenuated bleomycin-induced pulmonary fibrosis. However, during the late period (day 10 to day 28) MCI-186 exacerbated pulmonary fibrosis, based on the histology and hydroxyproline content. In this condition, MCI-186 in the late period decreased the number of apoptosis cells induced by bleomycin, and therefore it might contribute to the deterioration of pulmonary fibrosis. These data indicate that MCI-186, radical scavenger, has a biphasic effect on bleomycin-induced pulmonary fibrosis in mice. Careful attention should be paid before clinical application of new remedies for pulmonary fibrosis.

The role of high mobility group box1 in pulmonary fibrosis.

High mobility group box1 protein (HMGB1) was originally discovered as a nuclear binding protein, and is known to play an important role in acute lung injury. However, the role of HMGB1 in pulmonary fibrosis has not been addressed. Therefore, we measured the HMGB1 levels in serum and bronchoalveolar lavage fluids (BALF) from patients with idiopathic pulmonary fibrosis (IPF), nonspecific interstitial pneumonia, interstitial pneumonia associated with collagen vascular diseases, and hypersensitivity pneumonitis (HP) by enzyme-linked immunosorbent assay. We also assessed the HMGB1 expression in bleomycin-induced pulmonary fibrosis in mice, and examined the effect of anti-HMGB1 antibody and ethyl pyluvate, which inhibits the HMGB1 secretion from alveolar macrophages. In addition, we examined the effect of HMGB1 on fibroblast proliferation, apoptosis, and collagen synthesis in vitro. Serum HMGB1 levels were not significantly increased in interstitial lung diseases compared with control subjects. BALF HMGB1 levels were significantly increased in IPF and HP compared with control subjects. HMGB1 protein was predominantly detected in inflammatory cells and hyperplasic epithelial cells in IPF. In bleomycin-induced pulmonary fibrosis in mice, HMGB1 protein was predominantly up-regulated in bronchiolar epithelial cells at early phase and in alveolar epithelial and inflammatory cells in fibrotic lesions at later phase. Intraperitoneal injection of anti-HMGB1 antibody or ethyl pyluvate significantly attenuated lung inflammation and fibrosis in this model. HMGB1 significantly induced proliferation, but not apoptosis or collagen synthesis on cultured fibroblasts. HMGB1 may be a promising target against pulmonary fibrosis as well as acute lung injury.

Dual-immunohistochemistry provides little evidence for epithelial-mesenchymal transition in pulmonary fibrosis.

Epithelial-mesenchymal transition (EMT) has been considered to be involved in organ fibrogenesis. However, there is few direct evidence of this process in the pathophysiology of pulmonary fibrosis in vivo. Therefore, we tried to verify the involvement of this process in the development of pulmonary fibrosis. Since the co-expressions of epithelial and mesenchymal markers are thought to be a marker of EMT, we performed dual-immuunohistochemistry to assess the co-expressions of these proteins in lung tissues from bleomycin-induced pulmonary fibrosis in mice, and from patients with idiopathic pulmonary fibrosis, and nonspecific interstitial pneumonia. Double positive cells for epithelial markers including E-cadherin, T1alpha, or aquaporin 5, and a mesenchymal markers alpha-smooth muscle actin or vimentin were not found in bleomycin-induced pulmonary fibrosis in mice. Double positive cells for E-cadherin, ICAM-1, LEA, CD44v9, or SP-A and alpha-smooth muscle actin or vimentin were not found in lung tissues from normal lung parenchyma, idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia. These results offer at least two possibilities. One is that EMT does not occur in IPF or bleomycin-induced pulmonary fibrosis in mice. Another is that EMT may occur in pulmonary fibrosis but the time during this transition in which cells express detectable levels of epithelial and mesenchymal markers is too small to be detected by double immunohistochemistry.

Gene transfer of soluble transforming growth factor type II receptor by in vivo electroporation attenuates lung injury and fibrosis.

BACKGROUND: Transforming growth factor-beta1 (TGF-beta1) has the potential to induce acute inflammation and apoptosis in lung epithelial cells and plays a central role in subsequent fibrosis. AIMS: To examine a new anti-TGF-beta1 therapy against lung injury and fibrosis, which comprises the transfection of soluble TGF type II receptor (sTGFRII) gene into skeletal muscles by in vivo electroporation. METHODS: Soluble TGFRII was detectable between 1 and 14 days in the serum and significantly increased between 3 and 10 days after gene transfer into muscles. Based on these findings, the sTGFRII gene was injected at 3 days before or 4 days after the bleomycin instillation in order to examine the significance of TGF-beta1 on the early inflammatory phase (day 0 to day 7) or the fibrotic phase (day 7 to day 14) in this model. RESULTS: Transfection of sTGFRII gene at 3 days before or 4 days after bleomycin instillation significantly attenuated apoptosis, injury, and fibrosis at 7 or 14 days, respectively. This method does not require the use of viral vector or neutralising antibody, and it is therefore possible to avoid problems regarding the pathogenicity of the viral vector or immunocomplex. CONCLUSIONS: This novel anti-TGF-beta1 strategy may have clinical application in the treatment of lung injury and fibrosis.

Anti-vascular endothelial growth factor gene therapy attenuates lung injury and fibrosis in mice.

Vascular endothelial growth factor (VEGF) is an angiogenesis factor with proinflammatory roles. Flt-1 is one of the specific receptors for VEGF, and soluble flt-1 (sflt-1) binds to VEGF and competitively inhibits it from binding to the receptors. We examined the role of VEGF in the pathophysiology of bleomycin-induced pneumopathy in mice, using a new therapeutic strategy that comprises transfection of the sflt-1 gene into skeletal muscles as a biofactory for anti-VEGF therapy. The serum levels of sflt-1 were significantly increased at 3-14 days after the gene transfer. Transfection of the sflt-1 gene at 3 days before or 7 days after the intratracheal instillation of bleomycin decreased the number of inflammatory cells, the protein concentration in the bronchoalveolar lavage fluid and with von Willebrand factor expression at 14 days. Transfection of the sflt-1 gene also attenuated pulmonary fibrosis and apoptosis at 14 days. Since the inflammatory cell infiltration begins at 3 days and is followed by interstitial fibrosis, it is likely that VEGF has important roles as a proinflammatory, a permeability-inducing, and an angiogenesis factor not only in the early inflammatory phase but also in the late fibrotic phase. Furthermore, this method may be beneficial for treating lung injury and fibrosis from the viewpoint of clinical application, since it does not require the use of a viral vector or neutralizing Ab.

[A case of rapidly deteriorated pulmonary aspergillosis with various clinical manifestations].

A 62-year-old man with chronic hepatitis was admitted to the hospital because of severe asthma, fever, and a chest radiograph abnormality. He had previously been treated unsuccessfully with several antibiotics in another hospital. The chest radiographs and CT films showed multiple infiltrations along the bronchi and in the peripheral regions of both lungs. Aspergillus fumigatus was detected in a sputum culture and the non-specific serum IgE was elevated. Allergic broncho-pulmonary aspergillosis (ABPA) was suspected and then steroids were administered. Although the asthma symptoms improved after the steroid therapy, lung infiltration deteriorated rapidly, affecting both lungs, and cavitations appeared. We concluded that invasive aspergillosis had developed from ABPA. Itraconazole and amphotericin B were administered, resulting in gradual improvements in the bilateral infiltration seen in the chest radiographs. The patient underwent open lung biopsy to rule out systemic vasculitis. The histological diagnosis was organizing pneumonia without vasculitis and without aspergillus or other organisms. The pathological findings resulted from the intensive anti-fungal therapy. There is a possibility that the temporal steroid therapy may have affected the conversion of ABPA to invasive aspergillosis.

Anti-monocyte chemoattractant protein-1 gene therapy attenuates pulmonary fibrosis in mice.

Monocyte chemoattractant protein-1 (MCP-1) is a proinflammatory chemokine and may play an important role in the development of pulmonary fibrosis. We examined a new therapeutic strategy that comprises the transfection of the mutant MCP-1 gene into skeletal muscles as a biofactory for anti-MCP-1 therapy against bleomycin-induced pulmonary fibrosis in mice. Overexpression of the mutant MCP-1 gene at 10-14 days after intratracheal instillation of bleomycin resulted in decreased DNA damage, apoptosis, and pulmonary fibrosis at 14 days. However, overexpression of the mutant MCP-1 at 0-4 days after bleomycin instillation did not result in decreased pathological grade, DNA damage, or apoptosis at 7 and 14 days. Because, in this model, inflammatory cell infiltration begins at 3 days and is followed by interstitial fibrosis, it is likely that MCP-1 has an important role to play in the development of fibrogenesis but not in the development of early lung inflammation. This method does not require the use of viral vector or neutralizing antibody, and, as such, it is possible to avoid problems regarding the pathogenicity of the viral vector or immunocomplex. This new strategy may be a beneficial method of treating pulmonary fibrosis from the viewpoint of clinical application.

Induction of CDK inhibitor p21 gene as a new therapeutic strategy against pulmonary fibrosis.

Alveolar epithelial cells are known to be present at the primary site of lung damage in pulmonary fibrosis. Apoptosis has been implicated as being involved in epithelial cell damage and pulmonary fibrosis. Because the cyclin-dependent kinase inhibitor p21 induces G1 arrest and DNA repair and because it also prevents apoptosis in some cells, we hypothesized that p21 gene transfer may attenuate bleomycin-induced pulmonary fibrosis in mice, the pathogenesis of which likely involves epithelial cell apoptosis. Human p21 protein was expressed in mouse alveolar epithelial cells at 1-7 days in vitro and was detected predominantly in lung epithelial cells at 1-7 days in vivo after adenoviral transfer of the human p21 gene. Inflammatory cell infiltration and fibrosis had already begun at 7 days in this model. Adenoviral transfer of the human p21 gene at 7 days after intratracheal instillation of bleomycin led to a decrease in the number of apoptotic cells, lung inflammation, and fibrosis at 14 days. Therefore, the forced expression of p21 exerted both anti-apoptotic and anti-fibrotic effects, which would facilitate the ultimate goal of treatment for pulmonary fibrosis.

Mitochondria-mediated apoptosis of lung epithelial cells in idiopathic interstitial pneumonias.

We previously demonstrated that the up-regulation of p53, Fas, and DNA damage are present in lung epithelial cells from patients with idiopathic interstitial pneumonias (IIP). Fas ligation induces apoptosis of lung epithelial cells predominantly through the direct activation of the caspase cascade via caspase-8 activation, whereas the up-regulation of p53 and other cellular stresses can induce mitochondria-mediated apoptosis. In this study, we investigated the incidence of mitochondria-mediated apoptosis of epithelial cells in IIP. We performed TUNEL staining to detect apoptotic cells and western blot analysis and immunohistochemistry to assess the expression and activation of caspases and the cytochrome c release from mitochondria in lung tissues from eight patients with usual interstitial pneumonia, five patients with nonspecific interstitial pneumonia, and eight patients with normal lung parenchyma. The expressions of pro- and cleaved caspase-8, 9, 3, and cytochrome c release from the mitochondria were all significantly increased in the lung tissues of IIP compared with normal lung parenchyma. The positive signals for caspases in epithelial cells were increased in IIP compared with normal lung parenchyma by immunohistochemistry. The results of TUNEL and electron microscopy suggested that apoptotic cells were predominantly epithelial cells. TUNEL-positive cells in % of epithelial cells were significantly increased in IIP compared with normal lung parenchyma, and significantly correlated with cytochrome c release from the mitochondria and with the expression of cleaved caspase-3 in epithelial cells. We conclude that mitochondria-mediated apoptosis may be involved in the pathophysiology of IIP.

TGF-beta 1 as an enhancer of Fas-mediated apoptosis of lung epithelial cells.

Transforming growth factor-beta 1 (TGF-beta 1) has important roles in lung fibrosis and the potential to induce apoptosis in several types of cells. We previously demonstrated that apoptosis of lung epithelial cells induced by Fas ligation may be involved in the development of pulmonary fibrosis. In this study, we show that TGF-beta1 induces apoptosis of primary cultured bronchiolar epithelial cells via caspase-3 activation and down-regulation of cyclin-dependent kinase inhibitor p21. Concentrations of TGF-beta 1 that were not sufficient to induce apoptosis alone could enhance agonistic anti-Fas Ab or rFas ligand-mediated apoptosis of cultured bronchiolar epithelial cells. Soluble Fas ligand in the bronchoalveolar lavage fluid (BALF) from patients with idiopathic pulmonary fibrosis (IPF) also induced apoptosis of cultured bronchiolar epithelial cells that was significantly attenuated by anti-TGF-beta Ab. Otherwise, BALF from patients with hypersensitivity pneumonitis (HP) could not induce apoptosis on bronchiolar epithelial cells, despite its comparable amounts of soluble Fas ligand. The concentrations of TGF-beta 1 in BALF from patients with IPF were significantly higher compared with those in BALF from patients with HP or controls. Furthermore, coincubation with the low concentration of TGF-beta 1 and HP BALF created proapoptotic effects comparable with the IPF BALF. In vivo, the administration of TGF-beta 1 could enhance Fas-mediated epithelial cell apoptosis and lung injury via caspase-3 activation in mice. Our results demonstrate a novel role of TGF-beta 1 in the pathophysiology of pulmonary fibrosis as an enhancer of Fas-mediated apoptosis of lung epithelial cells.