Extracellular superoxide dismutase has a highly specific localization in idiopathic pulmonary fibrosis/usual interstitial pneumonia.

AIMS: Recent studies suggest the importance of oxidant stress in the progression of pulmonary fibrosis. The aim of this study was to investigate extracellular superoxide dismutase (ECSOD), the major antioxidant enzyme of the extracellular matrix of human lung, in biopsy-proven idiopathic pulmonary fibrosis (IPF) related to usual interstitial pneumonia (UIP). METHODS AND RESULTS: Fibrotic areas and fibroblastic foci in UIP lungs were notable for absence of ECSOD by immunohistochemistry. Western blotting showed significantly lowered immunoreactivity of ECSOD in fibrotic compared with non-fibrotic areas of the diseased lung. The only cell type that showed intense ECSOD positivity in UIP was the interstitial mast cell. In order to investigate the mechanism for ECSOD depletion in fibrotic areas, alveolar epithelial cells were exposed to tumour necrosis factor-alpha and transforming growth factor (TGF)-beta1; TGF-beta suggested a trend towards decreased synthesis. Patients with UIP were also assessed to determine whether this disease is associated with a naturally occurring mutation in ECSOD (Arg213Gly) which leads to a loss of tissue binding of ECSOD. No significant differences could be found in the allele or genotype frequencies of this polymorphism between 63 UIP patients and 61 control subjects. CONCLUSION: Overall, consistent with several other antioxidant enzymes, ECSOD is very low in fibrotic areas of UIP, which may further increase the oxidant burden in this disease.

Cell specific expression of peroxiredoxins in human lung and pulmonary sarcoidosis.

BACKGROUND: Six proteins of the peroxiredoxin (Prx) family have recently been characterised which have the capacity to decompose hydrogen peroxide in vivo and in vitro. These proteins may have an important role in the protection of human lung against endogenous and exogenous oxidant stress. However, the expression and distribution of these proteins in healthy human lung and diseased lung tissue is unknown. METHODS: The cell specific expression of Prxs in healthy lung tissue from four non-smokers and in parenchymal tissue from 10 subjects with pulmonary sarcoidosis was investigated by immunohistochemistry, and expression of these proteins in various cultured lung cells and cells of bronchoalveolar lavage (BAL) fluid of controls and patients with sarcoidosis was assessed by Western blot analysis. RESULTS: All six Prxs could be synthesised in cultured human lung cells. The bronchial epithelium showed moderate to high expression of Prxs I, III, V and VI, the alveolar epithelium expressed mainly Prxs V and VI, and alveolar macrophages expressed mainly Prxs I and III. Granulomas of subjects with sarcoidosis expressed mainly Prxs I and III. Samples of BAL fluid from controls and from subjects with sarcoidosis had very similar findings, except that Prxs II and III had a tendency for increased immunoreactivity in sarcoidosis tissue. CONCLUSIONS: Prxs I, III, V, and VI, in particular, have prominent and cell specific expression in human lung tissue. High expression of Prxs I and III in granulomas and alveolar macrophages of sarcoidosis parenchyma may have a significant effect on the oxidant burden and the progression of lung injury in this disease.

Expression and regulation of hemeoxygenase 1 in healthy human lung and interstitial lung disorders.

Hemeoxygenase 1 (HO-1) has been implicated in the protection of lung tissue against exogenous oxidant exposure. However, the expression and cellular distribution of HO-1 in human lung continue to be poorly characterized. The localization of HO-1 was studied in histopathologically healthy lung from nonsmoking patients with a carcinoid or other lung tumor (5 cases), pulmonary sarcoidosis (13 cases), and chronic interstitial pneumonias (9 cases, usual interstitial pneumonia; 10 cases, desquamative interstitial pneumonia). Immunostaining was graded from 0 (no immunoreactivity) to +++ (intense immunoreactivity). In healthy lung, HO-1 was localized to alveolar macrophages with reactivity varying from moderate to intense, and in bronchial epithelium, alveolar epithelium, endothelium, and interstitium, the immunoreactivity was not detectable or was very low. Sarcoidosis and interstitial pneumonias showed intense HO-1 immunoreactivity in alveolar macrophages in most of the cases and weak to intense immunoreactivity in the granulomas of sarcoidosis. The immunoreactivity of interstitium was negative or weak in the fibrotic areas of the lung and also in the samples of bronchoalveolar lavage fluid obtained from the patients with UIP. Western blotting indicated that HO-1 is up-regulated by exposure of monocytes to formylated peptide, fMLP, which causes respiratory burst in the cells, and that inhibition of HO-1 by tin protoporphyrin potentiates the injury of fMLP-exposed cells. In conclusion, these data show differential distribution of HO-1 in human lung cells and strongly suggest the importance of HO-1, especially in the defense of alveolar macrophages in normal human lung and in the inflammatory, but not in the fibrotic, stage of interstitial lung disorders.

Expression of inducible nitric oxide synthase in healthy pleura and in malignant mesothelioma.

In this study we investigated the immunohistochemical expression of inducible nitric oxide synthase (iNOS) in a set of normal pleural mesothelial tissues, malignant mesotheliomas, mesothelioma cell lines and metastatic pleural adenocarcinomas. Furthermore, the expression of mRNA was assessed in four malignant mesothelioma cell lines in culture. Apoptosis and vascular density in malignant mesotheliomas was assessed by the TUNEL method and by immunohistochemistry with an antibody against FVIII-related antigen. Immunohistochemically mesothelial cells in non-neoplastic healthy pleural tissues were mostly negative for iNOS. Positivity for iNOS was observed in 28/38 (74%) and 24/25 (96%) of malignant mesotheliomas and metastatic pleural adenocarcinomas, respectively. Epithelial and mixed mesotheliomas expressed more often strong iNOS immunoreactivity compared to the sarcomatoid subtype (P = 0.023). Moreover, metastatic adenocarcinomas expressed more often iNOS positivity than mesotheliomas (P = 0.021). Experiments with the cell lines confirmed that malignant mesothelioma cells are capable of synthesizing iNOS. No significant association was found between iNOS expression and apoptosis or vascular density in malignant mesotheliomas. The higher expression of iNOS in the epithelial subtype of mesothelioma and pleural metastatic adenocarcinoma might be due to an increased sensitivity of these cell types to cytokine-mediated iNOS upregulation. The strong expression of iNOS suggests a putative role for NO in the growth and progression of these tumours.

Inducible nitric oxide synthase expression, apoptosis, and angiogenesis in in situ and invasive breast carcinomas.

In this investigation, we studied the expression of inducible nitric oxide synthase (iNOS) and its association to apoptosis and angiogenesis in 43 in situ and 68 invasive breast carcinomas. Its expression was studied immunohistochemically using a polyclonal iNOS antibody, and the staining was evaluated both in tumor and stromal cells. Apoptosis was detected by 3' end labeling of fragmented DNA (terminal deoxynucleotidyl transferase-mediated nick end labeling method). Vascularization was detected immunohistochemically using an antibody to the FVIII-related antigen, and calculated microvessel densities were determined. In addition to strong iNOS expression in stromal cells, iNOS positivity was observed in tumor cells in 46.5% of in situ and 58.8% of invasive carcinomas. In invasive carcinomas, there were more cases with iNOS positivity both in tumor and stromal cells compared to in situ carcinomas (0.007). The proportion of cases with iNOS-positive tumor cells increased in in situ carcinomas from grade I to III (20.0%, 46.2%, and 73.3%). In invasive ductal carcinomas, there were more cases with iNOS-positive tumor cells than with in situ carcinomas (P = 0.04). Carcinomas with both iNOS-positive tumor and stromal cells had a higher apoptotic index (P = 0.02) and a higher calculated microvessel densities index (P = 0.02). A high number of iNOS-positive stromal cells associated with metastatic disease (P = 0.05). The results show that breast carcinoma cells, in addition to stromal cells, express iNOS and are capable of producing NO. Carcinomas with iNOS-positive tumor and stromal cells have a higher apoptotic indices and increased vascularization, suggesting that iNOS contributes to promotion of apoptosis and angiogenesis in breast carcinoma. The association of the number of iNOS-positive stromal cells with metastatic disease might be attributable to stimulation of angiogenesis, resulting in a higher vascular density and consequently a higher probability for tumor cells to invade.

Manganese superoxide dismutase and catalase are coordinately expressed in the alveolar region in chronic interstitial pneumonias and granulomatous diseases of the lung.

Free radicals have been suggested to play an important role in the pathogenesis of interstitial lung diseases, the most important of which are chronic interstitial pneumonias such as usual interstitial pneumonia (UIP) and desquamative interstitial pneumonia (DIP) and granulomatous lung diseases such as sarcoidosis. Because manganese superoxide dismutase (MnSOD) and catalase are two important intracellular antioxidant enzymes that probably play a central role in lung defense, the localization and intensity of these two enzymes were assessed by immunohistochemistry in biopsies of UIP (n = 9), DIP (n = 11), pulmonary sarcoidosis (n = 14), and extrinsic allergic alveolitis (n = 6). The mRNA of these enzymes in selected samples of bronchoalveolar lavage was assessed by Northern blotting. Catalase, but not MnSOD, was constitutively expressed, especially in type II pneumocytes of the healthy lung of nonsmoking individuals. In contrast, manganese SOD immunoreactivity was markedly upregulated in all of the interstitial lung diseases investigated, whereas no increased expression of catalase could be detected in any case. Both enzymes were expressed, especially in type II pneumocytes and alveolar macrophages of DIP and UIP, in the well-preserved areas of the lung, in the acute fibromyxoid lesions of UIP, and in the granulomas of sarcoidosis and extrinsic allergic alveolitis. The simultaneous expression of MnSOD and catalase in the alveolar region suggests their protective role against the progression of lung disease.

Expression of antioxidant enzymes in human inflammatory cells.

Because antioxidant enzymes may have an important role in the oxidant resistance of inflammatory cells, we investigated the mRNA levels and specific activities of manganese and copper-zinc superoxide dismutases (Mn SOD and Cu,Zn SOD), catalase (Cat), and glutathione peroxidase, as well as the concentrations of glutathione (GSH) in human neutrophils, monocytes, monocyte-derived macrophages, and alveolar macrophages. Levels of GSH and glutathione peroxidase activity in monocytes were three times higher than in neutrophils, whereas the mRNA of Cat was 50-fold and its specific activity 4-fold higher in neutrophils. Although Mn SOD mRNA levels were higher in neutrophils, enzyme activities, as well as those of Cu,Zn SOD, were similar in all phagocytic cells. Neutrophils lost their viability, assessed by adenine nucleotide depletion, within 24 h ex vivo and more rapidly if GSH was depleted. However, neutrophils were the most resistant cell type to exogenous H(2)O(2). In conclusion, high Cat activity of neutrophils appears to explain their high resistance against exogenous H(2)O(2), whereas low GSH content and GSH-related enzymes seem to account for the poor survival of human neutrophils.

Carboxyterminal propeptide of type I procollagen in ELF: elevation in asbestosis, but not in pleural plaque disease.

Markers of collagen metabolism may possibly be used in the assessment of pulmonary involvement in asbestosis-related pulmonary diseases. In this study the levels of the carboxyterminal propeptide of type I procollagen (PICP) and the aminoterminal propeptide of type III procollagen (PIIINP) were evaluated in bronchoalveolar lavage fluid (BALF), epithelial lining fluid (ELF) and serum from patients with asbestos related pulmonary and pleural involvement. Forty-two consecutive patients with occupational exposure to asbestos fibres, who underwent bronchoscopy and bronchoalveolar lavage (BAL) at the time of the diagnosis were investigated. Five patients were diagnosed as having asbestosis, while 37 showed no parenchymal involvement. Of the latter group, 25 had pleural plaques, while 12 had no detectable changes in chest radiographs. The patients were followed-up for an average of 7 yrs. The PICP in BALF and ELF was detectable in all patients with asbestosis and in 8/37 subjects without parenchymal involvement. The levels of PICP in BALF and ELF were significantly higher in the asbestosis group compared to the patients without asbestosis (9.8+/-1.8 microg x L(-1) versus 0.6+/-1.3 microg x L(-1), p<0.001 and 488.9+/-208.8 microg x L(-1) versus 22.6+/-50.6 microg x L(-1), p<0.001, respectively). Only 1 patient with asbestosis and 3 patients without parenchymal involvement had detectable levels of PIIINP in BALF. The serum levels of PICP and PIIINP did not differ between the patients with asbestosis and those with exposure to asbestos fibres without asbestosis and were within the normal range. None of the 37 patients exposed to asbestos fibres without parenchymal involvement at the baseline developed asbestosis during the follow-up period of 7 yrs. In conclusion, the data show that the carboxyterminal propeptide of procollagen type I, but not the aminoterminal propeptide of type III procollagen is highly elevated in bronchoalveolar lavage fluid and epithelial lining fluid in patients with asbestosis, but not in those without parenchymal involvement. This suggests that the determination of carboxyterminal propeptide of procollagen type I in bronchoalveolar lavage fluid could be used as a marker of parenchymal involvement in patients exposed to asbestos fibres.

Type III and type I procollagen markers in fibrosing alveolitis.

Deposition of types I and III collagen is a typical feature in the development of pulmonary fibrosis. We assessed the propeptides of these procollagens as prognostic markers in 18 patients with fibrosing alveolitis. We analyzed the amino-terminal propeptide of type III procollagen (PIIINP) and the carboxy-terminal propeptide of type I procollagen (PICP) from samples of bronchoalveolar lavage fluid (BALF) and serum, and also estimated their concentrations in epithelial lining fluid (ELF) by the urea method. The level of PIIINP in serum (p < 0.05), BALF (p < 0.05), and ELF (p < 0.05), and the levels of PICP in BALF (p < 0.001) and ELF (p < 0.001) but not in serum, were significantly increased in the patients with fibrosing alveolitis as compared with 17 controls who had been investigated for minor respiratory symptoms. In the BALF and ELF of patients with fibrosing alveolitis, PICP but not PIIINP had significant negative correlations with the specific diffusion coefficient for carbon monoxide (DLCO/ VA). The amino-terminal propeptide of type III procollagen and the carboxy-terminal propeptide of type I procollagen in BALF correlated significantly with one another. During the follow-up period of 6 yr, seven of the 18 patients with fibrosing alveolitis died of the disease, 3 others died of malignancy, and one patient died from an unknown cause. DLCO (p < 0.05) differed significantly between the surviving patients and those who died of fibrosing alveolitis, and detectable PIIINP in BALF predicted death from fibrosing alveolitis (p = 0.05). In conclusion, these results show that PIIINP in BALF, ELF, and serum, and PICP in BALF and ELF, are increased in patients with fibrosing alveolitis. A high level of PICP in BALF, and especially in ELF, suggests a chronic process and increased synthesis of type I collagen in the lungs, whereas PIIINP in BALF and ELF suggests active disease and a poor prognosis.

Manganese superoxide dismutase, but not CuZn superoxide dismutase, is highly expressed in the granulomas of pulmonary sarcoidosis and extrinsic allergic alveolitis.

The role of antioxidant defense mechanisms in the pathogenesis of granulomatous human lung diseases remains open to investigation. In this study we investigated the immunoreactivity of two important superoxide radical scavenging intracellular antioxidant enzymes, manganese superoxide dismutase (MnSOD) and copperzinc superoxide dismutase (CuZnSOD), in pulmonary sarcoidosis and extrinsic allergic alveolitis. In histologically normal lung MnSOD was variable but mostly positive in the cells of bronchial epithelium, alveolar epithelium especially in type II pneumocytes, and alveolar macrophages. Copperzinc SOD showed positive immunoreactivity most markedly in the bronchial epithelium. The biopsies of 22 patients with pulmonary sarcoidosis and 10 with extrinsic allergic alveolitis indicated that MnSOD was highly stained in the granulomas of both diseases, with 60 to 100% of the granulomas showing intensive immunoreactivity. Western blots conducted on the cell samples of bronchoalveolar lavage (BAL) fluid revealed significantly higher amounts of MnSOD in sarcoidosis and extrinsic allergic alveolitis than in the controls. Immunohistochemistry on the cells obtained from BAL fluid showed positive immunoreactivity of MnSOD in the macrophages but not in the lymphocytes. In contrast, copperzinc SOD was not induced in either of these diseases. We conclude that MnSOD is highly expressed in the granulomas of pulmonary sarcoidosis and extrinsic allergic alveolitis, and variable but mostly positive in alveolar macrophages, possibly owing to cytokine mediated induction during the granuloma formation.