Ultrastructural features of lung fibroblast differentiation into myofibroblasts

Fibroblast differentiation into myofibroblast in transforming growth factor-beta1-exposed human lung fibroblasts and the immunolocalizations of alpha-smooth muscle actin, fibronectin, tenascin-C, and osteopontin in exposed cells were studied by conventional transmission electron microscopy and immunoelectron microscopy. Ultrastructural features of myofibroblasts were detected after exposure, e.g., alpha-smooth muscle actin positive bundles in the cytoplasm of cells and extracellular fibronectin-containing structures on the surface of the cell forming fibronexus structure, osteopontin adjacent to rough endoplastic reticulum and extracellular tenascin-C in the vicinity of the cell. The authors concluded that exposure to transforming growth factor-beta1 can differentiate lung fibroblasts into ultrastructurally typical myofibroblasts.

Claudin-1, -2, -3, -4, -5, and -7 in usual interstitial pneumonia and sarcoidosis

The aim of this study was to study the expression of various claudins in sarcoidosis, usual interstitial pneumonia (UIP), and normal human lung. The expression and cell-specific localization of claudin-1, -2, -3, -4, -5, and -7 was analyzed by IHC. Bronchiolar epithelial cells showed mostly strong expression for claudin-1, -2, -3, -4, and -7 and mainly weak expression for claudin-5 in UIP, sarcoidosis, and normal lung. Three claudins, claudin-3, -4, and -7, were expressed in normal alveolar epithelium, mainly in type II pneumocytes. Claudin-5 was expressed strongly in endothelium of normal lung, and its staining was extremely intense in endothelium of UIP. Moderate or strong expression for claudin-1, -2, -3, -4, and -7 was observed in metaplastic alveolar- and bronchiolar-type epithelium in UIP and also in metaplastic alveolar-type epithelium in sarcoidosis. Expression of claudin-5 was mainly weak in metaplastic alveolar- and bronchiolar-type epithelium in UIP. We conclude that claudin-1, -2, -3, -4, -5, and -7 are expressed in UIP and sarcoidosis, and furthermore, the most prominent enhancement of staining is localized in metaplastic alveolar- and bronchiolar-type epithelium in UIP compared with the healthy lung.

Does the oxidative stress in chronic obstructive pulmonary disease cause thioredoxin/peroxiredoxin oxidation?

The thioredoxin/peroxiredoxin system comprises a redox-regulated antioxidant family in human lung; its significance, regulation, or oxidation has not been evaluated in smoking-related lung diseases. Here, we present the expression of the thioredoxin/peroxiredoxin system in lung biopsies from normal lung (n = 14), smokers (n = 21), and patients with chronic obstructive pulmonary disease (COPD, n = 38), and assess the possible inactivation/oxidation of this system by nonreducing Western blotting, two-dimensional gel electrophoresis, and mass spectrometry. Our study shows that the thiol status of the Trx/Prx-system can be modulated in vitro, but it appears to have high resistance against the oxidative stress in COPD.

Extracellular matrix proteins and myofibroblasts in granulomas of sarcoidosis, atypical mycobacteriosis, and tuberculosis of the lung

Sarcoidosis, atypical mycobacteriosis, and tuberculosis are common diseases of human lung with a typical feature of formation of granulomas. The structure of granulomas has not been elucidated completely. We studied the expression of tenascin-C, precursor proteins of collagens I and III, and the presence of myofibroblasts in granulomas of sarcoidosis, atypical mycobacteriosis, and tuberculosis of human lung. Twenty-five histologic samples of lung were analyzed by immunohistochemistry using antibodies to tenascin-C and aminoterminal propeptides of collagens I and III. To identify the myofibroblast-type cells in granulomas, the sections were also stained with antibodies against alpha-smooth muscle actin, vimentin, and desmin. In every case, tenascin-C and precursor proteins of collagens I and III were expressed around granulomas. Precursor protein of collagen I was expressed also within them. In tuberculosis and atypical mycobacteriosis, expression of tenascin-C and precursor protein of collagen I was stronger than in sarcoidosis. The cells demarcating granulomas and, thus, colocalizing with tenascin-C and both collagen precursors were positive for alpha-smooth muscle actin and vimentin, which suggests that these cells are myofibroblasts. They were also more abundantly present in tuberculosis and atypical mycobacteriosis, as suggested by alpha-smooth muscle actin staining. We concluded that tenascin-C and precursor proteins of collagens I and III are expressed around granulomas in sarcoidosis, atypical mycobacteriosis, and tuberculosis of the lung; and furthermore, their expression colocalize with the expression of myofibroblasts. Our results further point to the fact that fibrogenesis and matrix turnover is stronger in tuberculosis and atypical mycobacteriosis than in sarcoidosis.

COX-2 is widely expressed in metaplastic epithelium in pulmonary fibrous disorders

Idiopathic usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF) and asbestosis represent progressive and often fatal pulmonary fibrous disorders, whereas cryptogenic organizing pneumonia (COP), desquamative interstitial pneumonia (DIP), and respiratory bronchiolitis-interstitial lung disease (RB-ILD) usually are reversible or nonprogressive conditions. Prostaglandin E2 (PGE2) inhibits fibroblast proliferation and myofibroblast transition, its production depending on cyclooxygenase-2 (COX-2). In patients with UIP/IPF, levels of PGE2 and COX-2 are reduced in fibroblasts, and levels of PGE2 in bronchioalveolar lavage fluid may be lowered. We analyzed the immunohistochemical expression of COX-2 in UIP/IPF, asbestosis, COP, DIP, and RB-ILD. Our results show that the metaplastic epithelium in UIP/IPF, asbestosis, and COP is widely COX-2+, whereas COX-2 positivity is scant in DIP and RB-ILD. The mesenchymal cells remained negative. Our results suggest that irrespective of the underlying disease, lung injury that causes extensive fibrosis induces wide expression of COX-2 in the regenerating metaplastic epithelium.

Relationship between histopathological features and the course of idiopathic pulmonary fibrosis/usual interstitial pneumonia

BACKGROUND

Fibroblastic focus (FF) is the typical histopathological feature of idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonia (UIP). A study was undertaken to analyse FF at diagnosis, to analyse the histopathological findings at necropsy, and to examine their association with the course of the disease.

METHODS

A retrospective study was made of 76 UIP cases collected over a period of 30 years from one university hospital; 64 had idiopathic IPF. The surface area of one slide of each lung biopsy specimen was defined by image analysis and the total number of FF was quantified. The histological features of necroscopic lung samples were re-analysed in 11 cases. Clinical follow up information was obtained from the registers.

RESULTS

Patients with < or =50 FF/cm(2) (n = 34) in the lung biopsy specimen had a median survival of 89 months (95% CI 38 to 140) compared with 49 months (95% CI 36 to 62) in those with >50 FF/cm(2) (n = 42, p = 0.0358). Diffuse alveolar damage (DAD) was detected in 10 necropsy samples and almost prevented the histopathological confirmation of UIP in six cases. Accumulation of neutrophils occurred in nine cases. There was no association between FF at diagnosis and DAD at necropsy, or between FF and exacerbation of the disease before death.

CONCLUSIONS

The number of FF in lung samples before death is associated with poor survival but not with DAD, which is a common feature in necropsy specimens of patients with UIP. FF cannot predict an acute exacerbation of IPF.

Localization of precursor proteins and mRNA of type I and III collagens in usual interstitial pneumonia and sarcoidosis

The aim of this study was to assess and compare the accumulation and distribution of newly synthesized type I and III collagens in usual interstitial pneumonia (UIP) and pulmonary sarcoidosis. Lung biopsies from 10 patients with UIP and 13 patients with sarcoidosis were investigated by immunohistochemical technique and mRNA in situ hybridization. The antibodies for the aminoterminal propeptide of type I procollagen and the aminoterminal propeptide of type III procollagen (PINP and PIIINP, respectively) were used. When compared to healthy lung, levels of type I pN- and type III pN-collagens were increased in both of these disorders. Type I procollagen was mostly present as intracellular spots in newly formed fibrosis in UIP while type III pN-collagen was expressed extracellularly underneath metaplastic alveolar epithelium. Type I procollagen was present intracellularly within and around the granulomas of sarcoidosis, whereas type III pN-collagen was expressed extracellularly, mainly around the granulomas. mRNAs of both collagens colocalized with the precursor proteins. We conclude that the expression of precursor proteins and mRNA of type I and type III collagens is increased in UIP and sarcoidosis, reflecting mainly active synthesis of these collagens in different areas of the lung.

Lysyl oxidase is essential for normal development and function of the respiratory system and for the integrity of elastic and collagen fibers in various tissues

Lysyl oxidases, a family comprising LOX and four LOX-like enzymes, catalyze crosslinking of elastin and collagens. Mouse Lox was recently shown to be crucial for development of the cardiovascular system because null mice died perinatally of aortic aneurysms and cardiovascular dysfunction. We show here that Lox is also essential for development of the respiratory system and the integrity of elastic and collagen fibers in the lungs and skin. The lungs of E18.5 Lox(-/-) embryos showed impaired development of the distal and proximal airways. Elastic fibers in E18.5 Lox(-/-) lungs were markedly less intensely stained and more disperse than in the wild type, especially in the mesenchyme surrounding the distal airways, bronchioles, bronchi, and trachea, and were fragmented in pulmonary arterial walls. The organization of individual collagen fibers into tight bundles was likewise abnormal. Similar elastic and collagen fiber abnormalities were seen in the skin. Lysyl oxidase activity in cultured Lox(-/-) skin fibroblasts and aortic smooth muscle cells was reduced by approximately 80%, indicating that Lox is the main isoenzyme in these cells. LOX abnormalities may thus be critical for the pathogenesis of several common diseases, including pulmonary, skin, and cardiovascular disorders.

Thoracoscopic Lung Biopsy Is a Safe Procedure in Diagnosing Usual Interstitial Pneumonia

OBJECTIVES

To evaluate the effect of lung biopsy on the survival of patients when histopathologic confirmation of usual interstitial pneumonia (UIP) is needed.

BACKGROUND

Idiopathic pulmonary fibrosis is a distinct clinical entity with histopathologic features of UIP. Surgical biopsy is needed when clinical and radiologic findings are not typical. The safety of lung biopsy is a matter of debate, and the results of short-term mortality (< 30 days) after biopsy are variable.

METHODS

Seventy-six patients with UIP, including 34 patients who underwent video-assisted thoracoscopic surgery (VATS) biopsy and 42 patients who underwent open-lung biopsy, were included in this retrospective study. All biopsies were reevaluated for UIP histopathology. Clinical data such as age at the time of biopsy, type of biopsy, preoperative pulmonary function, major postoperative complications, date and cause of death, and survival time after the biopsy were gathered. Median survival was used to compare the survival between different groups, and cumulative survival was estimated using Kaplan-Meyer method.

RESULTS

Thoracoscopic biopsy was safe for diagnosing UIP, with no short-term mortality. In contrast, open-lung biopsy was followed by four deaths (5.3%) within 1 month after the procedure. All fatal cases were accompanied by a histopathologic pattern of diffuse alveolar damage. Age of the patient at the time of biopsy was a significant predicting factor for survival. Patients < 50 years old lived 181 months (range, 119 to 242 months), and patients > 50 years old lived 75 months (range, 55 to 95 months).

CONCLUSIONS

VATS biopsy is a safe procedure in diagnosing UIP.

Manganese superoxide dismutase is increased in the airways of smokers' lungs

Oxidant stress is a key mechanism for smoking-induced chronic obstructive pulmonary disease (COPD). Smoking has been shown to upregulate several antioxidant enzymes, with potential effects on the prevention of the disease and/or its progression. Superoxide dismutases (SOD)s are the only enzymes capable of consuming superoxide radicals. The purpose of the present study was to investigate SODs in the lungs of nonsmokers, smokers and COPD patients. Manganese superoxide dismutase (MnSOD), copper zinc SOD (CuZnSOD), and extracellular SOD (ECSOD), were investigated by immunohistochemistry in the airways of 13 nonsmokers, 20 smokers and 22 COPD patients with mild-to-moderate disease. Lung tissue homogenates of three nonsmokers and four smokers were used for Western blot and enzyme activity analysis. The expression of MnSOD was higher in the central bronchial epithelium of smokers with COPD and in the alveolar epithelium of smokers without or with COPD than innonsmokers. Lung MnSOD immunoreactivity, evaluated by Western blotting and specific activity, were 33% and 51% higher, respectively, in smokers than in nonsmokers. No major changes could be observed in lung CuZnSOD or ECSOD immunoreactivities. Manganese superoxide dismutase is elevated in the alveolar epithelium of cigarette smokers, probably due to the increased oxidant burden in smokers' lungs.

Distribution of antioxidant enzymes in developing human lung, respiratory distress syndrome, and bronchopulmonary dysplasia

We studied cell-specific protein expression of all the major antioxidant enzymes (AOEs) and related proteins, such as copper-zinc superoxide dismutase (CuZnSOD), manganese SOD (MnSOD), extracellular SOD (ECSOD), catalase, the heavy and light chains of gamma-glutamylcysteine synthetase (gamma-GCS-l and gamma-GCS-h, also called glutamate cysteine ligase), the rate-limiting enzyme in glutathione synthesis, hemeoxygenase-1 (HO-1), and thioredoxin (Trx), in developing human lung, respiratory distress syndrome, and bronchopulmonary dysplasia by immunohistochemistry. Generally, after 17 weeks of gestational age, MnSOD was predominantly expressed in bronchial epithelium, alveolar epithelium, and macrophages, CuZnSOD was expressed in bronchial epithelium, ECSOD was expressed in bronchial epithelium, vascular endothelium, and the extracellular matrix, catalase was expressed in bronchial epithelium and alveolar macrophages, gamma-GCS-h was expressed in bronchial epithelium and endothelium, and gamma-GCS-l was expressed in bronchial epithelium. Trx was restricted to bronchial epithelium and to a lesser extent to alveolar macrophages, and HO-1 found in alveolar macrophages. Basically, the expression of these enzymes was similar in normal and diseased lung. It can be concluded that various AOEs and related proteins differ in their distribution and expression in lung before term, but generally it seems that infants are better adapted to high oxygen tension than might be expected.

Expression of glutaredoxin is highly cell specific in human lung and is decreased by transforming growth factor-β in vitro and in interstitial lung diseases in vivo

Glutaredoxins (Grx) are thiol-disulfide oxidoreductases with antioxidant capacity and catalytic functions closely associated with glutathione, an antioxidant abundantly present in human lung. The present study investigated the expression of both human glutaredoxins in cultured human lung cells and lung homogenates by reverse-transcription polymerase chain reaction and Western blotting. Immunohistochemical studies were conducted with 38 human lung specimens, including healthy lung, parenchymal sarcoidosis, extrinsic allergic alveolitis, and usual interstitial pneumonia (UIP). The ultrastructural localization of Grx1 was assessed by immunoelectron microscopy. In addition, cultured airway epithelial cells were exposed to tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta. Both Grx1 and Grx2 could be detected at the mRNA and protein level in cultured human lung cells, but only Grx1 was prominently expressed in lung homogenates and alveolar macrophages. Immunohistochemically, Grx1 was highly concentrated to alveolar macrophages and weakly positive in the bronchial epithelium. Grx1 was ultrastructurally localized to the plasma membrane, cytoplasmic vacuoles, and nucleus. The expression of Grx1 decreased in alveolar macrophages of sarcoidosis and allergic alveolitis compared with the case for controls (P < 0.001), and bronchial epithelium of these diseases revealed no Grx1 immunoreactivity. Fibroblast foci and other fibrotic areas in UIP were mainly negative. In A549 cells, Grx1 was down-regulated by TGF-beta, whereas TNF-alpha caused no clear effect. Overall, high expression of Grx1 in alveolar macrophages suggests its importance in the primary defense of human lung. Decreased expression of Grx1 further suggests the impairment of this system both in inflammatory and fibrotic lung diseases, consistent with the down-regulation of Grx1 by TGF-beta in vitro.

Type I and III collagen protein precursors and mRNA in the developing human lung

Extracellular matrix proteins have a prominent role in both ontogenesis and fibrogenesis in the human lung. The aim of this study was to analyse the expression of newly formed precursor proteins and mRNA of collagen types I and III in developing human lung tissues from 12 to 40 weeks of gestation, and also in neonatal disorders such as respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD). Lung tissues were obtained at autopsy from 60 non-malformed cases. All tissues were analysed by immunohistochemistry and 24 were also investigated by mRNA in situ hybridization. The precursor proteins and mRNA of both collagens were expressed in abundance in pulmonary arteries and veins during all developmental periods. In RDS and BPD, precursor proteins and mRNAs of both collagen types were increased within alveolar walls. The cells in these locations showed alpha-smooth muscle actin, vimentin, and variable desmin immunoreactivity. Collagen I and III precursor proteins and mRNA were also observed in pleura, bronchi, bronchioles, and around chondrocytes during all developmental periods and in diseased lung. In conclusion, collagens I and III were expressed in a similar way in and around various cell types in the developing lung and their expression was increased within alveolar walls in RDS and BPD. Myofibroblast-type cells appeared to produce mRNA for both types of collagen in alveoli.

Expression of the thioredoxin system in interstitial lung disease

The thioredoxin system containing thioredoxin (Trx) and thioredoxin reductase (TrxR) has profound effects on cell proliferation and protection against exogenous oxidants. The significance of the Trx system in human lung and lung diseases is, however, largely unresolved. Altogether, 66 specimens of human lung were investigated by immunohistochemistry for their expression of Trx and TrxR. The diseases included interstitial pneumonias such as usual interstitial pneumonia (UIP), desquamative interstitial pneumonia (DIP), and UIP associated with collagen vascular diseases (CVD-ILD), and granulomatous diseases such as sarcoidosis and allergic alveolitis. The ultrastructural localization of Trx and TrxR was analysed by immunoelectron microscopy. In healthy lung, Trx and TrxR were expressed in bronchial epithelium and alveolar macrophages. Trx and TrxR were highly concentrated in areas of metaplastic epithelium in UIP and in alveolar macrophages in DIP, though fibrotic areas in UIP were mainly negative. The expression of both enzymes was clearly weaker in CVD-ILD than in UIP. Granulomas of sarcoidosis showed moderate to intense Trx immunoreactivity. Ultrastructurally, Trx and TrxR were expressed diffusely in the cytosolic compartment and plasma membrane of metaplastic type II pneumocytes, macrophages, and bronchial epithelial cells. This study highlights the importance of Trx and TrxR in primary defence in bronchial epithelium, alveolar epithelium, and macrophages in human lung, but also indicates that elevated expression of these proteins may serve as markers of ongoing cell regeneration and inflammation.

Laminin-5 γ2Chain in Cryptogenic Organizing Pneumonia and Idiopathic Pulmonary Fibrosis

Insufficient reepithelialization of injured alveolar walls may be important in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Laminin-5 is expressed in epithelial cells of healing wounds, promoting cell attachment and migration. In this study we have studied the extent of reepithelialization of newly formed intraluminal connective tissue, the immunohistochemical expression and ultrastructural localization of the laminin-5 gamma2 chain protein, and the synthesis of the laminin-5 gamma2 chain mRNA in regenerating epithelial cells in cryptogenic organizing pneumonia (COP) and IPF. The results show that the mean extent of reepithelialization of intraluminal connective tissue lesions was 76% (SD, +/- 27%) in COP, and 54% (SD, +/- 23%) in IPF (p < 0.025). The laminin-5 gamma2 chain was synthesized and widely expressed in regenerating epithelial cells in both diseases. Immunohistochemistry for surfactant-associated protein A suggests a pneumocyte origin for the regenerating epithelial cells in IPF. It is concluded that both in COP and IPF, regenerating epithelial cells are capable of synthesizing the laminin-5 gamma2 chain needed for adhesive connections to the underlying basement membrane. However, in IPF, the reepithelialization seems to be disturbed or delayed.

Over-expression of tenascin-C in malignant pleural mesothelioma

AIMS

Tenascin-C is an extracellular matrix glycoprotein known to have anti-adhesive characteristics and to be expressed in various human malignant neoplasms. We hypothesized that the expression of tenascin-C would be increased in human malignant pleural mesothelioma, and its accumulation associated with the prognosis of the patients with this disease.

METHODS AND RESULTS

Thirty-seven cases of mesothelioma were studied by immunohistochemically using a monoclonal antibody against tenascin-C, and with a semiquantitative scoring system for tenascin-C in different areas of the tumours. In 10 selected cases tenascin-C mRNA in-situ hybridization was also analysed. Since transforming growth factor-beta (TGF-beta) is known to induce both the synthesis of tenascin-C and the growth of mesotheliomas, an immunohistochemical analysis of TGF-beta 1, -beta 2 and -beta 3 was also performed. Normal pleura (n = 7) and metastatic pleural adenocarcinomas (n = 7) were used as controls. Tenascin-C protein was expressed in every histological subtype of malignant mesothelioma, being most prominent in the fibrotic stroma of a tumour, around tumour cells and at the invasive border, whereas tenascin-C mRNA was scarce in tumour cells. The patients with less immunohistochemical expression for tenascin-C tended to live longer (P = 0.028 by Fishers' exact probability test). All mesotheliomas showed positivity for at least one isoform of TGF-beta.

CONCLUSIONS

In conclusion, high expression of tenascin-C protein in malignant pleural mesotheliomas may play a role in its invasive growth, and might serve as a prognostic marker of the disease.

Expression of antioxidant enzymes in bronchial metaplastic and dysplastic epithelium

We investigated immunohistochemical expression of manganese superoxide dismutase (MnSOD) and three hydrogen peroxide (H(2)O(2)) scavenging pathways, i.e. catalase (CAT), gamma-glutamyl cysteine synthetase (gammaGCS) and thioredoxin (Trx) system in normal bronchial epithelium, bronchial metaplasia and dysplasia and correlated their expression with NF-kappaB activation (p50) and proliferation (Ki67). Normal bronchial epithelium was positive for MnSOD, heavy and light subunits of gammaGCS, CAT and Trx and TrxR. Metaplastic epithelium showed strongest expression of gammaGCSh and Trx, whereas dysplastic epithelium expressed most prominently MnSOD and CAT. There was a significant correlation between expression of gammaGCSh and gammaGCSl (P=0.034) and Trx and TrxR (P=0.037). Trx expression also correlated with gammaGCSh (P<0.001) and gammaGCSl (P=0.012) and TrxR with gammaGCSh (P<0.001) but not with gammaGCSl immunoreactivity (P=0.744). Expression of p50 was highest in metaplastic epithelium while Ki67 was highest in dysplastic lesions. Expression of Trx and gammaGCSh correlated inversely with age of the patients (R=-0.6038, P<0.001 for Trx and R=-0.6162, P<0.001 for gammaGCSh). Changes in the expression of these enzymes in bronchial lesions might be due to alterations of antioxidative mechanisms due to irritation via exogenous toxins and activation of reactive oxygen species (ROS) known to be associated with induction of metaplasia and dysplasia in the bronchial tree.

Diminished immunoreactivity of gamma-glutamylcysteine synthetase in the airways of smokers' lung

Glutathione (GSH) plays a major role in protecting the airways against oxidative stress. The rate-limiting enzyme in de novo GSH synthesis is gamma-glutamylcysteine synthetase (gamma-GCS), which is induced by acute exposure to GSH-depleting cytokines and oxidants, but downregulated by transforming growth factor beta and prolonged oxidant exposure, at least in vitro. Cell-specific expression or regulation of gamma-GCS may play an important role both in the defense against oxidants and in the pathogenesis of oxidant-associated airway diseases. In this study, the localizations of gamma-GCS heavy (gamma-GCS-HS) and light (gamma-GCS-LS) subunits were investigated by immunohistochemistry in 22 patients with chronic obstructive pulmonary disease (COPD), 20 smokers without COPD, and 13 lifelong nonsmokers. The ultrastructural distributions of both gamma-GCS subunits were assessed by immuno-electron microscopy. Both subunits were expressed most prominently in the large airways, and their ultrastructural localization was both cytoplasmic and along the plasma membrane. The expression of gamma-GCS-HS was stronger in the central bronchial epithelium than in the peripheral bronchioli (p = 0.020), or in alveolar macrophages (p = 0.008). The expression of gamma-GCS-HS in the central bronchial epithelium showed a tendency to be higher in nonsmokers compared with all smokers (p = 0.052). Alveolar macrophages of nonsmokers had higher levels of gamma-GCS-HS (p = 0.001) and gamma-GCS-LS (p = 0.001) than did smokers. The expression of gamma-GCS-HS in the central bronchial epithelium was more marked in nonsmokers than in patients with COPD (p = 0.015), the difference between smokers and patients with COPD was not significant. In conclusion, the heavy and light subunits of gamma-GCS are mainly expressed in the large airways. Their tendency to decrease in cigarette smokers may further predispose lung cells to ongoing oxidant stress, which contributes to the progression of lung injury.

Tenascin-C is highly expressed in respiratory distress syndrome and bronchopulmonary dysplasia

Tenascin-C is an extracellular matrix (ECM) glycoprotein expressed in human tissues during organogenesis and in fibrotic and neoplastic processes. We hypothesized that its expression would increase in human lung in neonatal disorders such as infant respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD). Tenascin-C expression was studied by immunohistochemistry (IHC) and mRNA in situ hybridization (ISH). The extent of tenascin-C immunoreactivity was scored as absent (0), low (+), moderate (++), strong (+++), or very strong (++++) separately in different types of pulmonary cells in controls (seven cases), RDS (19 cases), and BPD (12 cases). In controls, tenascin-C expression was low (+) underneath alveolar and bronchiolar epithelium, moderate (++) in intima of veins, and strong (+++) around chondrocytes. In RDS, tenascin-C expression was moderate (++) or strong (+++) underneath both bronchiolar and often detached alveolar epithelium underlying hyaline membranes in the walls of dilated alveoli. In particular, the patients with RDS who survived for 1 day or more had strong expression of tenascin-C within alveolar walls. In patients with BPD, tenascin-C was very strongly (++++) expressed in the remodeled fibrotic alveolar walls underneath regenerative epithelium. Increased expression of tenascin-C mRNA was seen below the alveolar and bronchiolar epithelia in RDS and BPD. The cells in these locations showed alpha-smooth muscle actin immunoreactivity, suggesting a myofibroblast phenotype. In conclusion, tenascin-C is highly expressed in the walls of alveoli and bronchioli in RDS and BPD, suggesting an association between the expression of this protein and the presence of these disorders.

Overexpression of peroxiredoxins I, II, III, V, and VI in malignant mesothelioma

Peroxiredoxins (Prxs) are a recently characterized group of thiol-containing proteins with efficient antioxidant capacity, capable of consuming hydrogen peroxide in living cells. Altogether six distinct Prxs have been characterized in mammalian tissues. Their expression was investigated in histological samples of mesothelioma and in cell lines established from the tumours of mesothelioma patients. Four cases with histopathologically healthy pleura from non-smokers were used as controls. Healthy pleural mesothelium was negative or very weakly positive for all Prxs. In mesothelioma, the most prominent reactivity was observed with Prxs I, II, V, and VI. Prx I was highly or moderately expressed in 25/36 cases, the corresponding figures for Prxs II-VI being 27/36 (Prx II), 13/36 (Prx III), 2/36 (Prx IV), 24/36 (Prx V), and 30/36 (Prx VI). Positive staining was observed both in the cytosolic and the nuclear compartment, with the exception of Prx III, which showed no nuclear reactivity. The staining pattern of Prxs III and V was granular. Immunoelectron microscopic localization of Prxs was in accordance with the immunohistochemical findings, showing diffuse cytoplasmic localization for Prxs I, II, IV, and VI and distinct mitochondrial labelling for Prxs III and V. There was no significant association between the extent of staining and different Prxs. It appeared that Prxs may not have prognostic significance, but being prominently expressed in most mesotheliomas these proteins, at least in theory, may play a role in the primary drug resistance of 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 of gamma-glutamyl cysteine synthetase in nonsmall cell lung carcinoma

BACKGROUND

The purpose of this study was to investigate expression of gamma glutamyl cysteine synthetase (gamma GCS), the rate-limiting enzyme in glutathione synthesis in nonsmall cell lung carcinoma (NSCLC).

METHODS

Eighty-five samples of NSCLC were studied using immunohistochemistry with polyclonal antibodies to the heavy and light subunits of gamma GCS (gamma GCS-h, gamma GCS-l), and the expressions were correlated with apoptosis and patients survival. Further studies were conducted in cultured cells also to investigate the effects of gamma GSC inhibition with buthionine sulfoximine on the cell survival.

RESULTS

In the biopsies, gamma GCS-h positivity was found in 71% and gamma GCS-l positivity in 67% of NSCLCs, and they were expressed in all cell lines studied. There was a strong association between the expression of the heavy and light subunits of gamma GCS in NSCLC (P = 0.003). Strong or moderate gamma GCS-h expression was found significantly more often in squamous cell carcinomas (P = 0.00013) and in Grade 1-2 tumors (P = 0.008). There was a significantly higher extent of apoptosis in tumors with a low gamma GCS-h expression (P = 0.016). A similar tendency was observed with gamma GCS-l (P = 0.073). No association was found between patient survival and high or low expression of gamma GCS-l or gamma GCS-h in NSCLCs (P = 0.34 and P = 0.47, respectively).

CONCLUSIONS

The results show that gamma GCS is strongly expressed in NSCLCs and probably takes part in the defense of the tumor cells against oxidative damage. This is reflected by the lower extent of apoptosis in tumors with a high gamma GCS expression. Because expression of gamma GCS has been connected with chemoresistance, downregulation of its activity by inhibitors in NSCLC might have putative therapeutic potential in the treatment of lung carcinoma.

Cell-specific expression of manganese superoxide dismutase protein in the lungs of patients with respiratory distress syndrome, chronic lung disease, or persistent pulmonary hypertension

The developmental profile of manganese superoxide dismutase (MnSOD) and its regulation in hyperoxia vary between species. We hypothesized that MnSOD increases in human lung in response to oxygen treatment, although this response could be restricted to certain cell types and depend on gestational age. Therefore, the cell-specific expression of pulmonary immunoreactive MnSOD protein was investigated during development, and in patients with respiratory distress syndrome (RDS), chronic lung disease (CLD), or persistent pulmonary hypertension (PPHN). Throughout ontogenesis, all cell types expressed MnSOD, but the most intense positivity was found in bronchiolar epithelium and (pre-) type-II pneumocytes. MnSOD protein did not increase during development. The MnSOD staining pattern in arterial endothelium was more intense in RDS patients than in age-matched controls, but this may be related to induction of MnSOD by increased blood flow rather than by oxygen. MnSOD expression in other cell types of RDS, CLD, or PPHN patients did not differ from that in age-matched controls. We conclude that, in terms of mitochondrial enzymatic superoxide scavenging capacity, preterm infants are not more vulnerable than term infants to oxygen-induced lung injury at physiological oxygen concentrations. However, the inability to induce MnSOD in response to oxygen treatment may result in a poor outcome.

The expression of P-glycoprotein and multidrug resistance proteins 1 and 2 (MRP1 and MRP2) in human malignant mesothelioma

BACKGROUND

Malignant mesothelioma is a malignancy with a primary resistance to chemo- and radiotherapies for reasons which are still unclear. Multidrug resistance proteins might explain the observed resistance, but no studies have assessed their expression in mesothelioma.

PATIENTS AND METHODS

Immunohistochemical expression of P-glycoprotein (P-gp), and the multidrug resistance proteins 1 and 2 (MRP1 and MRP2) were investigated in 36 cases of malignant mesothelioma and in samples from normal mesothelium.

RESULTS

P-gp immunopositivity was found in 61%, MRP1 immunopositivity in 58% and MRP2 positivity in 33% of the cases. Normal mesothelium did not express these multidrug-resistant proteins. There was a significant association between P-gp and MRP2 (P = 0.022) expression. No or weak P-gp, MRP1 or MRP2 immunostaining was significantly more frequent in sarcomatoid mesothelimas than in epithelial or biphasic mesotheliomas (P = 0.031, P = 0.034 and P = 0.024, respectively). There was no significant association between patient survival and expression of the multidrug-resistant proteins.

CONCLUSIONS

The results show that P-gp, MRP1 and MRP2 are induced and expressed in malignant mesothelial cells. Regardless of their expression no association with survival of the patients was seen, suggesting that the primary resistance of malignant mesotheliomas is not solely dependent on their expression or function.

Distribution and mRNA expression of tenascin-C in developing human lung

Tenascin-C is an extracellular matrix glycoprotein that is spatially expressed during organogenesis, in inflammatory and fibrotic disorders, and in neoplasms. The aim of this study was to analyze its expression in developing human lung tissues during pseudoglandular, canalicular, saccular, and alveolar periods corresponding to Weeks 12 to 40. Lung tissues were obtained at autopsy from 34 nonmalformed cases. An immunohistochemical analysis and a messenger RNA (mRNA) in situ hybridization method combined with light microscopy were used. The extent of tenascin-C immunoreactivity was scored as absent, low, moderate, or strong in and around different types of pulmonary cells. The immunohistochemical expression for tenascin-C was strong beneath the airway epithelium, especially at the sites of airway subdivision during Weeks 12 to 23, whereas its expression was moderate or weak underneath alveolar and bronchiolar epithelia between Weeks 24 and 40. The expression for tenascin-C was strong in the intima of veins, especially in the canalicular period, i.e., Weeks 17 to 28. A moderate or strong immunoreactivity for tenascin-C was also observed around chondrocytes in every case studied during all periods. The increased expression of tenascin-C mRNA was most often seen in the cells below the airway epithelium. Taken together, tenascin-C is expressed in human lung during all developmental periods, and its expression is especially strong below the airway epithelium at the sites of airway subdivision.

Widespread expression of thioredoxin and thioredoxin reductase in non-small cell lung carcinoma

We investigated the expression of thioredoxin (Trx) and thioredoxin reductase (TrxR) in 89 non-small cell lung carcinomas. Additionally, immortalized human bronchial epithelial cells (BEAS 2B) and four human lung carcinoma cells lines (A549, SK-MES-1, CALU-6, and A427) were studied by Western blot and reverse transcription-PCR for the synthesis of Trx and TrxR protein and mRNA expression in vitro. The histological samples were also studied for immunohistochemical p53 and proliferating cell nuclear antigen expression and apoptosis. In non-neoplastic lung, Trx and TrxR expression was seen in bronchial epithelial cells and alveolar macrophages, metaplastic alveolar epithelial cells, and chondrocytes of the bronchus. In non-small cell lung carcinomas, there was a widespread expression of Trx and TrxR with only three and eight cases negative, respectively. Trx and TrxR expression was located in both cytoplasmic and nuclear compartments of the cells. There was a statistical association between cytoplasmic and nuclear Trx or TrxR expression. Grade I-II tumors showed stronger cytoplasmic and nuclear Trx and TrxR immunoreactivity than grade III tumors. No association was found between p53 and proliferating cell nuclear antigen expression and Trx or TrxR immunoreactivity. However, apoptosis was inversely associated with nuclear Trx and TrxR positivity. In the cell lines studied, both non-neoplastic BEAS 2B cells and all of the carcinoma cell lines expressed Trx and TrxR proteins and mRNA. The results show that these redox-regulating proteins are highly expressed in lung carcinomas taking part in activation of transcriptional factors and regulation of apoptosis in non-small cell lung carcinoma. In high-grade tumors, Trx and TrxR expression is diminished, suggesting loss of redox regulation in tumors with low differentiation.

Expression and prognostic significance of catalase in malignant mesothelioma

BACKGROUND

Free radicals and antioxidant enzymes (AOEs) may play a critical role in cell proliferation and in the resistance of malignant cells against cytotoxic drugs and radiation. Malignant mesothelioma is a resistant tumor with high levels of manganese superoxide dismutase, a central superoxide scavenging AOE. In the current study, the authors assessed the expression and prognostic role of catalase, an important hydrogen peroxide scavenging AOE, in malignant pleural mesothelioma.

METHODS

Catalase expression was investigated by immunohistochemistry in 5 cases of nonmalignant healthy pleura and in tumor tissue of 32 mesothelioma patients, and by Western blot in 7 continuous human mesothelioma cell lines. The distribution of catalase in mesothelioma cells was assessed by immunoelectron microscopy. Furthermore, to investigate the effect of catalase inhibition in the drug resistance of these cells in vitro, the authors exposed mesothelioma cells with the highest catalase level to epirubicin with and without aminotriazole pretreatment.

RESULTS

Nonmalignant mesothelial cells showed no catalase immunoreactivity whereas most mesothelioma cases (24 of 32, 75%) were catalase positive, 17 cases (53%) showing moderate or high expression. Higher catalase expression in mesothelioma was associated with a better prognosis, mean survival rate from diagnosis being 6 and 24 months for negative/low expression and moderate/high expression, respectively. Furthermore, a coordinately high expression of both manganese-superoxide dismutase (Mn-SOD) and catalase predicted even more favorable outcome of the mesothelioma patients. Catalase also could be detected in all mesothelioma cell lines, the most resistant cell line showing the highest protein expression and compartmentalization of catalase mainly to peroxisomes. Aminotriazole inhibition of catalase had a marginal effect on the toxicity caused by epirubicin.

CONCLUSIONS

Catalase may have multifactorial effects in malignant cells; high catalase and/or coordinated high expression of Mn-SOD and catalase may decrease tumor progression by modulating the cellular redox state, but enhanced antioxidant capacity of mesothelioma cells also may protect tumor cells against exogenous oxidants, at least in vitro.

Tenascin expression and distribution in pleural inflammatory and fibrotic diseases

We hypothesized that tenascin expression is increased in pleural inflammatory and fibrotic diseases and that its expression can be used as a marker of active pleural involvement. For this purpose we analyzed 71 histological samples of inflammatory and fibrotic pleura from patients with asbestos-induced pleural reaction (n = 6), postcardiac injury syndrome (n = 6), parapneumonic infection and/or empyema (n = 23), tuberculosis (n = 5, rheumatoid disease (n = 1), and fibrosis with inflammation of unknown etiology (n = 30). All 71 cases were studied by immunohistochemistry for tenascin. In 19 selected cases tenascin mRNA in situ hybridization was also performed. In every case, tenascin was increased by immunohistochemistry. Most prominent immunoreactivity was detected in areas of newly formed fibrosis. Increased tenascin mRNA expression by in situ hybridization was detected in the individual cells of the newly formed fibrosis underneath the fibrinous exudate. The tenascin mRNA-positive cells localized in areas in which by immunohistochemical studies the cells were positive for alpha-smooth muscle actin, desmin, and vimentin, suggesting a myofibroblast phenotype. Tenascin mRNA expression was also seen less frequently in areas in which some cells were positive for cytokeratin. These cells might represent mesothelial cells entrapped in the inflammatory lesion. Alternatively, they might represent fibroblast-type cells with aberrant cytokeratin expression. We conclude that in pleural inflammatory and fibrotic diseases tenascin immunoreactivity is increased and tenascin mRNA-positive cells localized mainly in the areas of myofibroblast- and, less often, mesothelial-type cells, suggesting that mainly myofibroblasts and, less commonly, also mesothelial cells might be responsible for tenascin expression in pleural inflammatory and fibrotic diseases. (J Histochem Cytochem 48:1257-1268, 2000)

Tenascin mRNA expression at the foci of recent injury in usual interstitial pneumonia

To elucidate which cells are synthesizing tenascin in usual interstitial pneumonia (UIP) we have analyzed thoracoscopic or open lung biopsies from 30 patients with UIP by mRNA in situ hybridization, using (35)S-labeled tenascin RNA probes. The phenotype of the cells expressing tenascin mRNA was confirmed by immunohistochemical stainings of serial sections with antibodies against alpha-smooth muscle actin and human cytokeratin. The results demonstrate that tenascin is expressed at the foci of recent lesions consisting of intralumenal or incorporating loose fibrotic buds. The cells expressing tenascin mRNA were located in and underneath the newly formed epithelium. Immunohistochemical stainings showed that the cells in the newly formed epithelium were strongly cytokeratin positive, and thus evidently regenerating type 2 pneumocytes, while the cells underneath the newly formed epithelium were alpha-smooth muscle actin positive and apparently myofibroblasts. Tenascin mRNA expression was clearly stronger and more frequent in myofibroblasts than in type 2 pneumocytes, however. Weak tenascin mRNA expression was also found in metaplastic bronchiolar-type epithelium and alveolar macrophages. Our results are thus in good agreement with the previous studies showing that tenascin is actively synthesized at the early fibrotic lesions in UIP. Furthermore, results demonstrate that the interaction between the epithelium and the underlying connective tissue plays a significant role in tenascin synthesis and that myofibroblasts are mainly responsible for its synthesis in fibroblastic foci of UIP.

Apoptosis and expression of apoptosis regulating proteins bcl-2, mcl-1, bcl-X, and bax in malignant mesothelioma

We investigated apoptosis and the expression of bcl-2, mcl-1, bcl-X, and bax in histological sections from 35 malignant mesotheliomas and 21 metastatic adenocarcinomas. Moreover, the expression of bcl-2, mcl-1, bcl-X, and bax were assessed by Western blotting in nonmalignant human mesothelial cells (Met5A) and seven malignant cell lines. The apoptotic index in mesotheliomas was 1.07+/-1.14%. Patients with mesotheliomas showing a high apoptotic index (> or =0.75%) had a worse prognosis (P = 0.008). bcl-2 positivity was observed in only seven cases, but bcl-X, mcl-1, and bax positivity was seen in all of them. In immunoblotting experiments, all mesothelioma cell lines were negative for bcl-2 but positive for bcl-X, mcl-1, and bax. The apoptotic index in bcl-2-negative mesotheliomas was 1.25+/-1.24% and in bcl-2-positive ones, 0.47+/-0.42% (P = 0.014). The apoptotic index did not significantly associate with bcl-X, mcl-1, or bax expression (P = 0.19, P = 0.25, and P = 0.46, respectively). No significant difference was observed in apoptosis or expression of bcl-2, bcl-X, or bax between malignant mesotheliomas and metastatic adenocarcinomas. The former, however, showed more often weak mcl-1 immunoreactivity (P = 0.01). The results show that the extent of apoptosis may influence patient prognosis. bcl-2 is inversely associated with the apoptotic index but is relatively infrequently expressed in malignant mesotheliomas. Widespread expression of bcl-X, mcl-1, and bax suggests that these proteins may also take part in apoptosis regulation in mesotheliomas.

Intraluminal fibromyxoid lesions in bronchiolitis obliterans organizing pneumonia are highly capillarized

Bronchiolitis obliterans organizing pneumonia (BOOP) and usual interstitial pneumonia (UIP; ie, cryptogenic fibrosing alveolitis of mural type, CFA) are clinically and histologically distinguishable interstitial lung diseases. Both contain intraluminal lesions of newly formed fibromyxoid connective tissue. In BOOP, the fibromyxoid lesions are susceptible to complete reversal, but in UIP they are supposed to participate in the remodeling of the interstitium. Our hypothesis was that capillarization of the intraluminal fibromyxoid lesions is more frequent in BOOP compared with UIP. In this study, we stained diagnostic thoracoscopic or open lung biopsy specimens of patients with BOOP (n = 9) and UIP (n = 10) with antibodies against human laminin, von Willebrand factor, and CD34 to reveal the microvasculature of intraluminal fibromyxoid lesions. Our results show that in BOOP there is abundant capillarization in the newly formed intraluminal fibromyxoid lesions often reminiscent of granulation tissue. The mean number of capillaries per area unit (mm2) was 107 +/- SD 74 in samples stained for laminin, 103 +/- SD 46 for von Willebrand factor, and 63 +/- SD 36 for CD34. In marked contrast, in UIP, the corresponding accounts were significantly lower, being 14 +/- SD 15 for laminin (P < .003), 11 +/- SD 14 for von Willebrand factor (P < .001) and 6 +/- SD 6 for CD34 (P < .001). The intraobserver (P < .001) and interobserver correlations (P < .002) were highly significant, showing that our results are reproducible. We conclude that the content and nature of the newly formed intraluminal connective tissue, for example, in the form of vascular growth factors, are different in BOOP and in UIP, and this partly leads to the different clinical course of these diseases.

Tenascin is increased in epithelial lining fluid in fibrotic lung disorders

Tenascin is an extracellular matrix glycoprotein increased immunohistochemically in tumorous and fibrotic lung tissues as demonstrated by immunohistochemistry. We hypothesized that in bronchoalveolar lavage (BAL) fluid also the tenascin concentration would be elevated in patients with various fibrotic lung disorders. The aim of our study was to investigate whether BAL fluid tenascin would be increased compared with serum tenascin in patients with usual interstitial pneumonia (UIP), sarcoidosis, and extrinsic allergic bronchioloalveolitis. For this purpose BAL fluid was collected from five patients with UIP, 12 patients with sarcoidosis, five patients with extrinsic allergic bronchioloalveolitis, and six patients in a control group. BAL fluid and serum tenascin concentrations were detected by the enzyme immunoassay method. The BAL fluid results were expressed as tenascin concentrations in the epithelial lining fluid (ELF), as estimated by the urea method. The ELF tenascin concentration was increased in the patients with fibrotic lung disorders relative to the control group (mean 0.12 microg/ml) and was highest in the UIP group (mean 5.72 microg/ml) and sarcoidosis group (mean 4.76 microg/ml). It is concluded that the tenascin concentration in the ELF is increased in patients with UIP, sarcoidosis, and extrinsic allergic bronchioloalveolitis, suggesting active synthesis of tenascin in the lower respiratory tract in such disorders.

Tenascin immunoreactivity as a prognostic marker in usual interstitial pneumonia

In this investigation, tenascin (Tn) expression was studied in 51 cases of different types of fibrotic lung disorders originating for years 1981 to 1995. Our aim was to test if accumulation of Tn at the site of lung injury in usual interstitial pneumonia (UIP) could correlate with the prognosis. Lung biopsies taken from 28 patients with UIP, six with desquamative interstitial pneumonia (DIP), six with sarcoidosis, five with extrinsic allergic bronchioloalveolitis, five with bronchiolitis obliterans organizing pneumonia (BOOP), and one with nonspecific interstitial pneumonia were studied for the expression of Tn by using an immunohistochemical technique. In addition to Tn immunohistochemistry, selected cases were also studied by immunoelectron microscopy and Western blotting. For prognostic studies in UIP the clinical follow-up information was obtained from the patient records. The expression of Tn was increased in each type of fibrosis, especially in UIP. In immunoelectron microscopy the most prominent labeling in UIP was found in association with collagen fibers and within the type 2 pneumocytes. Every studied case of UIP showed reactivity for a polypeptide of M(r) approximately equal to 200,000 by Western blotting. In patients with UIP, increased Tn expression, especially under metaplastic bronchiolar-type epithelium, was associated with a shortened survival time. Immunoelectron microscopic findings support the idea that Tn in UIP is synthesized by the regenerating epithelial rather than interstitial cells in response to pulmonary interstitial inflammation.