Lung Cancer in Pulmonary Fibrosis: Tales of Epithelial Cell Plasticity

Lung epithelial cells exhibit a high degree of plasticity. Alterations to lung epithelial cell function are critically involved in several chronic lung diseases such as pulmonary fibrosis. Pulmonary fibrosis is characterized by repetitive injury and subsequent impaired repair of epithelial cells, which leads to aberrant growth factor activation and fibroblast accumulation. Increased proliferation and hyper- and metaplasia of epithelial cells upon injury have also been observed in pulmonary fibrosis; this epithelial cell activation might represent the basis for lung cancer development. Indeed, several studies have provided histopathological evidence of an increased incidence of lung cancer in pulmonary fibrosis. The mechanisms involved in the development of cancer in pulmonary fibrosis, however, remain poorly understood. This review highlights recently uncovered molecular mechanisms shared between lung cancer and fibrosis, which extend the current evidence of a common trait of cancer and fibrosis, as provided by histopathological observations. Copyright (C) 2011 S. Karger AG, Base

Aspartic proteinase napsin is a useful marker for diagnosis of primary lung adenocarcinoma

Napsin A is an aspartic proteinase expressed in lung and kidney. We have reported that napsin A is expressed in type II pneumocytes and in adenocarcinomas of the lung. The expression of napsin was examined in 118 lung tissues including 16 metastases by in situ hybridisation. Napsin was expressed in the tumour cell compartment in 33 of 39 adenocarcinomas (84.6%), in two of 11 large cell carcinomas and in one lung metastasis of a renal cell carcinoma. Expression of napsin was found to be associated with a high degree of differentiation in adenocarcinoma. Immunohistochemistry was performed for three proteins currently used as markers for lung adenocarcinoma : surfactant protein-A, surfactant protein-B and thyroid transcription factor-1. Thyroid transcription factor-1 showed the same sensitivity (84.6%) as napsin for adenocarcinoma, whereas surfactant protein-A and surfactant protein-B showed lower sensitivities. Among these markers, napsin showed the highest specificity (94.3%) for adenocarcinoma in nonsmall cell lung carcinoma. We conclude that napsin is a promising marker for the diagnosis of primary lung adenocarcinoma

Localization and potential role of matrix metalloproteinase-1 and tissue inhibitors of metalloproteinase-1 and -2 in different phases of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) can evolve in prematurely born infants who require mechanical ventilation because of hyaline membrane disease (HMD). The development of BPD can be divided in an acute, a regenerative, a transitional, and a chronic phase. During these different phases, extensive remodeling of the lung parenchyma with re-epithelialization of the alveoli and formation of fibrosis occurs. Matrix metalloproteinase-1 (MMP-1) is an enzyme that is involved in re-epithelialization processes, and dysregulation of MMP-1 activity contributes to fibrosis. Localization of MMP-1 and its inhibitors, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2, were investigated in lung tissue obtained from infants who died during different phases of BPD development. In all studied cases (n = 50) type-II pneumocytes were found to be immunoreactive for MMP-1, TIMP-1, and TIMP-2. During the acute and regenerative phase of BPD, type-II pneumocytes re-epithelialize the injured alveoli. This may suggest that MMP-1 and its inhibitors, expressed by type-II pneumocytes, play a role in the re-epithelialization process after acute lung injury. Although MMP-1 staining intensity remained constant in type-II pneumocytes during BPD development, TIMP-1 increased during the chronic fibrotic phase. This relative elevation of TIMP-1 compared with MMP-1 is indicative for reduced collagenolytic activity by type-II pneumocytes in chronic BPD and may contribute to fibrosis. Fibrotic foci in chronic BPD contained fibroblasts immunoreactive for MMP-1 and TIMP-1 and -2. This may indicate that decreased collagen turnover by fibroblasts contributes to fibrosis in BPD development

Expression of HSP47 in Usual Interstitial Pneumonia and Nonspecific Interstitial Pneumonia

BACKGROUND: Heat shock protein (HSP) 47, a collagen-specific molecular chaperone, is involved in the processing and/or secretion of procollagens, and its expression is increased in various fibrotic diseases. The aim of this study was to determine whether quantitative immunohistochemical evaluation of the expression levels of HSP47, type I procollagen and α-smooth muscle actin (SMA) allows the differentiation of idiopathic usual interstitial pneumonia (UIP) from UIP associated with collagen vascular disease (CVD) and idiopathic nonspecific interstitial pneumonia (NSIP). METHODS: We reviewed surgical lung biopsy specimens of 19 patients with idiopathic UIP, 7 with CVD-associated UIP and 16 with idiopathic NSIP and assigned a score for the expression of HSP47, type I procollagen and α-SMA in type II pneumocytes and/or lung fibroblasts (score 0 = no; 1 = weak; 2 = moderate; 3 = strong staining). RESULTS: The expression level of HSP47 in type II pneumocytes of idiopathic UIP was significantly higher than in CVD-associated UIP and idiopathic NSIP. The expression of HSP47 in fibroblasts was significantly higher in idiopathic UIP and idiopathic NSIP than in CVD-associated UIP. The expression of type I procollagen in type II pneumocytes was significantly higher in idiopathic UIP than in idiopathic NSIP. The expression of type I procollagen in fibroblasts was not different in the three groups, while the expression of α-SMA in fibroblasts was significantly higher in idiopathic UIP than in idiopathic NSIP. CONCLUSION: Our results suggest the existence of different fibrotic pathways among these groups involved in the expression of HSP47 and type I procollagen

A Cellular Pathway Involved in Clara Cell to Alveolar Type II Cell Differentiation after Severe Lung Injury

Regeneration of alveolar epithelia following severe pulmonary damage is critical for lung function. We and others have previously shown that Scgb1a1-expressing cells, most likely Clara cells, can give rise to newly generated alveolar type 2 cells (AT2s) in response to severe lung damage induced by either influenza virus infection or bleomycin treatment. In this study, we have investigated cellular pathway underlying the Clara cell to AT2 differentiation. We show that the initial intermediates are bronchiolar epithelial cells that exhibit Clara cell morphology and express Clara cell marker, Scgb1a1, as well as the AT2 cell marker, pro-surfactant protein C (pro-SPC). These cells, referred to as pro-SPC[superscript +] bronchiolar epithelial cells (or SBECs), gradually lose Scgb1a1 expression and give rise to pro-SPC[superscript +] cells in the ring structures in the damaged parenchyma, which appear to differentiate into AT2s via a process sharing some features with that observed during alveolar epithelial development in the embryonic lung. These findings suggest that SBECs are intermediates of Clara cell to AT2 differentiation during the repair of alveolar epithelia following severe pulmonary injury.Singapore-MIT Alliance for Research and Technology Center. Infectious Disease Research Grou

Hepatocyte and keratinocyte growth factors and their receptors in human lung emphysema

BACKGROUND: Hepatocyte and keratinocyte growth factors are key growth factors in the process of alveolar repair. We hypothesized that excessive alveolar destruction observed in lung emphysema involves impaired expression of hepatocyte and keratinocyte growth factors or their respective receptors, c-met and keratinocyte growth factor receptor. The aim of our study was to compare the expression of hepatocyte and keratinocyte growth factors and their receptors in lung samples from 3 groups of patients: emphysema; smokers without emphysema and non-smokers without emphysema. METHODS: Hepatocyte and keratinocyte growth factor proteins were analysed by immunoassay and western blot; mRNA expression was measured by real time quantitative polymerase chain reaction. RESULTS: Hepatocyte and keratinocyte growth factors, c-met and keratinocyte growth factor receptor mRNA levels were similar in emphysema and non-emphysema patients. Hepatocyte growth factor mRNA correlated negatively with FEV1 and the FEV1/FVC ratio both in emphysema patients and in smokers with or without emphysema. Hepatocyte and keratinocyte growth factor protein concentrations were similar in all patients' groups. CONCLUSION: The expression of hepatocyte and keratinocyte growth factors and their receptors is preserved in patients with lung emphysema as compared to patients without emphysema. Hepatocyte growth factor mRNA correlates with the severity of airflow obstruction in smokers

Epimorphin expression in interstitial pneumonia

Epimorphin modulates epithelial morphogenesis in embryonic mouse organs. We previously suggested that epimorphin contributes to repair of bleomycin-induced pulmonary fibrosis in mice via epithelium-mesenchyme interactions. To clarify the role of epimorphin in human lungs, we evaluated epimorphin expression and localization in normal lungs, lungs with nonspecific interstitial pneumonia (NSIP), and lungs with usual interstitial pneumonia (UIP); we also studied the effect of recombinant epimorphin on cultured human alveolar epithelial cells in vitro. Northern and Western blotting analyses revealed that epimorphin expression in NSIP samples were significantly higher than those in control lungs and lungs with UIP. Immunohistochemistry showed strong epimorphin expression in mesenchymal cells of early fibrotic lesions and localization of epimorphin protein on mesenchymal cells and extracellular matrix of early fibrotic lesions in the nonspecific interstitial pneumonia group. Double-labeled fluorescent images revealed expression of matrix metalloproteinase 2 in re-epithelialized cells overlying epimorphin-positive early fibrotic lesions. Immunohistochemistry and metalloproteinase activity assay demonstrated augmented expression of metalloproteinase induced by recombinant epimorphin in human alveolar epithelial cells. These findings suggest that epimorphin contributes to repair of pulmonary fibrosis in nonspecific interstitial pneumonia, perhaps partly by inducing expression of matrix metalloproteinase 2, which is an important proteolytic factor in lung remodeling

The role of endothelin-1 in hyperoxia-induced lung injury in mice

BACKGROUND: As prolonged hyperoxia induces extensive lung tissue damage, we set out to investigate the involvement of endothelin-1 (ET-1) receptors in these adverse changes. METHODS: Experiments were performed on four groups of mice: control animals kept in room air and a group of mice exposed to hyperoxia for 60 h were not subjected to ET-1 receptor blockade, whereas the dual ETA/ETB-receptor blocker tezosantan (TEZ) was administered via an intraperitoneal pump (10 mg/kg/day for 6 days) to other groups of normal and hyperoxic mice. The respiratory system impedance (Zrs) was measured by means of forced oscillations in the anesthetized, paralyzed and mechanically ventilated mice before and after the iv injection of ET-1 (2 μg). Changes in the airway resistance (Raw) and in the tissue damping (G) and elastance (H) of a constant-phase tissue compartment were identified from Zrs by model fitting. RESULTS: The plasma ET-1 level increased in the mice exposed to hyperoxia (3.3 ± 1.6 pg/ml) relative to those exposed to room air (1.6 ± 0.3 pg/ml, p < 0.05). TEZ administration prevented the hyperoxia-induced increases in G (13.1 ± 1.7 vs. 9.6 ± 0.3 cmH(2)O/l, p < 0.05) and H (59 ± 9 vs. 41 ± 5 cmH(2)O/l, p < 0.05) and inhibited the lung responses to ET-1. Hyperoxia decreased the reactivity of the airways to ET-1, whereas it elevated the reactivity of the tissues. CONCLUSION: These findings substantiate the involvement of the ET-1 receptors in the physiopathogenesis of hyperoxia-induced lung damage. Dual ET-1 receptor antagonism may well be of value in the prevention of hyperoxia-induced parenchymal damage

Identification of Human Fibroblast Cell Lines as a Feeder Layer for Human Corneal Epithelial Regeneration

There is a great interest in using epithelium generated in vitro for tissue bioengineering. Mouse 3T3 fibroblasts have been used as a feeder layer to cultivate human epithelia including corneal epithelial cells for more than 3 decades. To avoid the use of xeno-components, we evaluated human fibroblasts as an alternative feeder supporting human corneal epithelial regeneration. Five human fibroblast cell lines were used for evaluation with mouse 3T3 fibroblasts as a control. Human epithelial cells isolated from fresh corneal limbal tissue were seeded on these feeders. Colony forming efficiency (CFE) and cell growth capacity were evaluated on days 5–14. The phenotype of the regenerated epithelia was evaluated by morphology and immunostaining with epithelial markers. cDNA microarray was used to analyze the gene expression profile of the supportive human fibroblasts. Among 5 strains of human fibroblasts evaluated, two newborn foreskin fibroblast cell lines, Hs68 and CCD1112Sk, were identified to strongly support human corneal epithelial growth. Tested for 10 passages, these fibroblasts continually showed a comparative efficiency to the 3T3 feeder layer for CFE and growth capacity of human corneal epithelial cells. Limbal epithelial cells seeded at 1×104 in a 35-mm dish (9.6 cm2) grew to confluence (about 1.87–2.41×106 cells) in 12–14 days, representing 187–241 fold expansion with over 7–8 doublings on these human feeders. The regenerated epithelia expressed K3, K12, connexin 43, p63, EGFR and integrin β1, resembling the phenotype of human corneal epithelium. DNA microarray revealed 3 up-regulated and 10 down-regulated genes, which may be involved in the functions of human fibroblast feeders. These findings demonstrate that commercial human fibroblast cell lines support human corneal epithelial regeneration, and have potential use in tissue bioengineering for corneal reconstruction