NHLBI workshop summaries. Pleural cell biology in health and disease

Multi-dimensional radiomics analysis to predict visceral pleural invasion in lung adenocarcinoma of ≤3 cm maximum diameter

AIM

To explore the value of radiomics analysis in preoperatively predicting visceral pleural invasion (VPI) of lung adenocarcinoma (LAC) with ≤3 cm maximum diameter and to compare the performance of two-dimensional (2D) and three-dimensional (3D) computed tomography (CT) radiomics models.

MATERIALS AND METHODS

A total of 391 LAC patients were enrolled retrospectively, of whom 142 were VPI (+) and 249 were VPI (-). Radiomics features were extracted from 2D and 3D regions of interest (ROIs) of tumours in CT images. 2D and 3D radiomics models were developed combining the optimal radiomics features by using the logistic regression machine-learning method and radiomics scores (rad-scores) were calculated. Nomograms were constructed by integrating independent risk factors and rad-scores. The performance of each model was evaluated by using the receiver operator characteristic (ROC) curve, decision curve analysis (DCA), clinical impact curve (CIC), and calculating the area under the curve (AUC).

RESULTS

There was no difference in the VPI prediction between 2D and 3D radiomics models (training group: 2D AUC=0.835, 3D AUC=0.836, p=0.896; validation group: 2D AUC=0.803, 3D AUC=0.794, p=0.567). The 2D and 3D nomograms performed similarly regarding discrimination (training group: 2D AUC=0.867, 3D AUC=0.862, p=0.409, validation group: 2D AUC=0.835, 3D AUC=0.827, p=0.558), and outperformed their corresponding radiomics models and the clinical model. DCA and CIC revealed that the 2D nomogram had slightly better clinical utility.

CONCLUSION

The 2D radiomics model has a similar discrimination capability compared with the 3D radiomics model. The 2D nomogram performs slightly better for individual VPI prediction in LAC.

A Nomogram Combined Radiomics and Clinical Features as Imaging Biomarkers for Prediction of Visceral Pleural Invasion in Lung Adenocarcinoma

Objectives

To develop and validate a nomogram model based on radiomics features for preoperative prediction of visceral pleural invasion (VPI) in patients with lung adenocarcinoma.

Methods

A total of 659 patients with surgically pathologically confirmed lung adenocarcinoma underwent CT examination. All cases were divided into a training cohort (n = 466) and a validation cohort (n = 193). CT features were analyzed by two chest radiologists. CT radiomics features were extracted from CT images. LASSO regression analysis was applied to determine the most useful radiomics features and construct radiomics score (radscore). A nomogram model was developed by combining the optimal clinical and CT features and the radscore. The model performance was evaluated using ROC analysis, calibration curve and decision curve analysis (DCA).

Results

A total of 1316 radiomics features were extracted. A radiomics signature model with a selection of the six optimal features was developed to identify patients with or without VPI. There was a significant difference in the radscore between the two groups of patients. Five clinical features were retained and contributed as clinical feature models. The nomogram combining clinical features and radiomics features showed improved accuracy, specificity, positive predictive value, and AUC for predicting VPI, compared to the radiomics model alone (specificity: training cohort: 0.89, validation cohort: 0.88, accuracy: training cohort: 0.84, validation cohort: 0.83, AUC: training cohort: 0.89, validation cohort: 0.89). The calibration curve and decision curve analyses suggested that the nomogram with clinical features is beyond the traditional clinical and radiomics features.

Conclusion

A nomogram model combining radiomics and clinical features is effective in non-invasively prediction of VPI in patients with lung adenocarcinoma.

Heparan sulfate chains contribute to the anticoagulant milieu in malignant pleural effusion

Background

While malignant pleural effusion (MPE) is a common and significant cause of morbidity in patients with cancer, current treatment options are limited. Human heparanase, involved in angiogenesis and metastasis, cleaves heparan sulfate (HS) side chains on the cell surface.

Aims

To explore the coagulation milieu in MPE and infectious pleural effusion (IPE) focusing on the involvement of heparanase.

Methods

Samples of 30 patients with MPE and 44 patients with IPE were evaluated in comparison to those of 33 patients with transudate pleural effusions, using heparanase ELISA, heparanase procoagulant activity assay, thrombin and factor Xa chromogenic assays and thromboelastography. A cell proliferation assay was performed. EMT-6 breast cancer cells were injected to the pleural cavity of mice. A peptide inhibiting heparanase activity was administered subcutaneously.

Results

Levels of heparanase, factor Xa and thrombin were significantly higher in exudate than transudate. Thromboelastography detected almost no thrombus formation in the whole blood, mainly on MPE addition. This effect was completely reversed by bacterial heparinase. Direct measurement revealed high levels of HS chains in pleural effusions. Higher proliferation was observed in tumour cell lines incubated with exudate than with transudate and it was reduced when bacterial heparinase was added. The tumour size in the pleural cavity of mice treated with the heparanase inhibitor were significantly smaller compared with control (p=0.005).

Conclusions

HS chains released by heparanase form an anticoagulant milieu in MPE, preventing local thrombosis and enabling tumour cell proliferation. Inhibition of heparanase might provide a therapeutic option for patients with recurrent MPE.

Clinical Significance of Pleural Attachment and Indentation of Subsolid Nodule Lung Cancer

Purpose

Lung cancers presenting as subsolid nodule commonly have peripheral location, making the cancer-pleura relationship noteworthy. We aimed to evaluate the effect of pleural attachment and/or indentation on visceral pleural invasion (VPI) and recurrence-free survival.

Materials and Methods

Patients who underwent curative resection of lung cancer as subsolid nodules from April 2007 to January 2016 were retrospectively evaluated. They were divided into four groups according to their relationship with the pleura. Clinical, radiographical, and pathological findings were analyzed.

Results

Among 404 patients with malignant subsolid nodule, 120 (29.7%) had neither pleural attachment nor indentation, 26 (6.4%) had attachment only, 117 (29.0%) had indentation only, and 141 (34.9%) had both. VPI was observed in nodules of 36 patients (8.9%), but absent in nonsolid nodules and in those without pleural attachment and/or indentation. Compared to subsolid nodules with concurrent pleural attachment and indentation, those with attachment only (odds ratio, 0.12; 95% confidence interval [CI], 0.02 to 0.98) and indentation only (odds ratio, 0.10; 95% CI, 0.03 to 0.31) revealed lower odds of VPI. On subgroup analysis, the size of the solid portion was associated with VPI among those with pleural attachment and indentation (p=0.021). Such high-risk features for VPI were associated with earlier lung cancer recurrence (adjusted hazard ratio, 3.31; 95% CI, 1.58 to 6.91).

Conclusion

Concurrent pleural attachment and indentation are risk factors for VPI, and the odds increase with larger solid portion in subsolid nodules. Considering the risk of recurrence, early surgical resection could be encouraged in these patients.

Doxycycline attenuates paraquat-induced pulmonary fibrosis by downregulating the TGF-β signaling pathway

Background

Paraquat (PQ) is a highly efficient herbicide that remains widely used in agriculture. However, the inappropriate application of this herbicide may cause multiple organ injuries including pulmonary injury. In this study, we report that doxycycline (Doxy) treats PQ-induced pulmonary fibrosis (PF).

Methods

Mice with PQ-induced PF were treated with different doses of Doxy by intragastric administration. Human lung cancer cell line A549 pre-treated with TGF-β1 (5 ng/mL) were treated with Doxy hydrochloride (3.4 µM).

Results

PF was observed from day 28 in PQ-treated group and Doxy treatments significantly reduced pulmonary coefficient, histopathological score and collagen content in a dose-dependent manner. Doxy can inhibit the expression levels of plasma inflammation cytokines at day 28 after modeling and reduced inflammatory response at early stage of PQ-induced lung injury. Immunohistochemical staining assay and proteomic analysis indicated that Doxy could restore ectopic epithelial-mesenchymal transition (EMT) induced by PQ-treatment by regulating numerous TGF-β signaling related proteins.

Conclusions

The findings suggest that Doxy can restore the balance of epithelial-mesenchymal cells and attenuate PQ-induced PF by downregulating the TGF-β signaling pathway.

Pleural mesothelial cells in pleural and lung diseases

During development, the mesoderm maintains a complex relationship with the developing endoderm giving rise to the mature lung. Pleural mesothelial cells (PMCs) derived from the mesoderm play a key role during the development of the lung. The pleural mesothelium differentiates to give rise to the endothelium and smooth muscle cells via epithelial-to-mesenchymal transition (EMT). An aberrant recapitulation of such developmental pathways can play an important role in the pathogenesis of disease processes such as idiopathic pulmonary fibrosis (IPF). The PMC is the central component of the immune responses of the pleura. When exposed to noxious stimuli, it demonstrates innate immune responses such as Toll-like receptor (TLR) recognition of pathogen associated molecular patterns as well as causes the release of several cytokines to activate adaptive immune responses. Development of pleural effusions occurs due to an imbalance in the dynamic interaction between junctional proteins, n-cadherin and β-catenin, and phosphorylation of adherens junctions between PMCs, which is caused in part by vascular endothelial growth factor (VEGF) released by PMCs. PMCs play an important role in defense mechanisms against bacterial and mycobacterial pleural infections, and in pathogenesis of malignant pleural effusion, asbestos related pleural disease and malignant pleural mesothelioma. PMCs also play a key role in the resolution of inflammation, which can occur with or without fibrosis. Fibrosis occurs as a result of disordered fibrin turnover and due to the effects of cytokines such as transforming growth factor-β, platelet-derived growth factor (PDGF), and basic fibroblast growth factor; which are released by PMCs. Recent studies have demonstrated a role for PMCs in the pathogenesis of IPF suggesting their potential as a cellular biomarker of disease activity and as a possible therapeutic target. Pleural-based therapies targeting PMCs for treatment of IPF and other lung diseases need further exploration.

The rate of pleural fluid drainage as a criterion for the timing of chest tube removal: theoretical and practical considerations

Clinicians place chest tubes approximately 1 million times each year in the United States, but little information is available to guide their management. Specifically, use of the rate of pleural fluid drainage as a criterion for tube removal is not standardized. Absent such tubes, pleural fluid drains primarily through parietal pleural lymphatics at rates approaching 500 mL of fluid per day or more for each hemithorax. Early removal of tubes does not appear to be harmful. A noninferiority randomized trial currently in progress comparing removal without considering the drainage rate to a conservative threshold (2 mL/kg body weight in 24 hours) may better inform tube management.

Aromatic-aromatic interactions: analysis of π-π interactions in interleukins and TNF proteins

Aromatic-aromatic hydrogen bonds are important in many areas of chemistry, biology and materials science. In this study we have analyzed the roles played by the π-π interactions in interleukins (ILs) and tumor necrosis factor (TNF) proteins. Majority of π-π interacting residues are conserved in ILs and TNF proteins. The accessible surface area calculations in these proteins reveal that these interactions might be important in stabilizing the inner core regions of these proteins. In addition to π-π interactions, the aromatic residues also form π-networks in ILs and TNF proteins. The results obtained in the present study indicate that π-π interactions and π-π networks play important roles in the structural stability of ILs and TNF proteins.

Are elastic stain and specialty sign out necessary to evaluate pleural invasion in lung cancers?

The seventh edition of American Joint Committee on Cancer (AJCC) staging system assigns lung cancers with visceral pleural invasion in the tumor size of 3 cm or less than 3 cm as T2 and without pleural invasion as T1. However, it may be difficult to distinguish with certainty between PL0 (no pleural invasion) and PL1 (extends through the elastic layer) on routine hematoxylin and eosin (H&E) stain. In this study, 25 cases of peripherally located lung adenocarcinoma were retrieved from the surgical pathology archives at the Asan Medical Center from May through June 2009. One representative H&E-stained slide was selected from each case and circulated to 31 pathology trainees and board-certified pathologists at Asan Medical Center who evaluated presence or absence of pleural invasion on H&E-stained slides. Elastic stain was used to determine the final status of pleural invasion for each case. The concordance rate of all pathologists with elastic stain results was, overall, 60.5%. The concordance rate of 2 lung specialists was 64%, better than the remaining faculty (54.7%). Fellows' and residents' evaluations were slightly more concordant than those of faculty responses (faculty overall, 56.4%; fellows, 62%; residents, 63.6%), but this difference was not statistically significant (P = .228). Our results confirm that pleural invasion status is difficult to discern with certainty on H&E-stained sections alone. Therefore, we recommend the routine use of elastic stain in evaluation of pleural invasion in all peripherally located lung cancers. Furthermore, our study indicates that subspecialty sign out may be preferable in evaluation of pleural invasion status.

Thoracoscopic assessment of pleural tumor burden in patients with malignant pleural effusion: prognostic and therapeutic implications

BACKGROUND

Malignant pleural effusion (MPE) is encountered at an advanced stage of disease progression and often heralds a poor prognosis. The most reliable predictive factor of survival in such patients is the primary tumor. Thoracoscopy is often performed for accurate diagnosis and/or thoracoscopic talc insufflation as a therapeutic modality. It remains unknown whether pleural tumor burden, as visualized on thoracoscopy, has potential prognostic value. The objective of this study was to determine the prognostic accuracy of pleural tumor extent and localization (parietal, visceral, or diaphragmatic involvement), as assessed during medical thoracoscopy.

METHODS

Medical records of all patients who underwent thoracoscopy for suspicion of MPE between 2001 and 2008 at a tertiary care referral hospital were reviewed. Patients were included if pleural metastatic invasion was confirmed on tissue biopsy and survival status ascertained.

RESULTS

Four hundred twenty-one patients underwent diagnostic or therapeutic medical thoracoscopy at our referral center. Among them, 122 had confirmed metastatic pleural spread, but survival data were lacking in 15. Primary tumor consisted of non-mall cell lung cancer in 56, breast cancer in 23, melanoma in eight, and other malignancies in 20. Median survival of the entire population was 9.4 months. On univariate analysis, the following variables were significantly associated with reduced median overall survival: pleural metastatic melanoma, age less than 60 years, bloody MPE, extensive pleural adhesions, and widespread visceral pleural nodules (p < 0.05). On multivariate analysis, only melanoma as a primary tumor, pleural fluid appearance and extent of pleural adhesions remained independent and significant predictors of survival.

CONCLUSION

No significant association was found between the extent or localization of pleural tumor burden and overall survival.

A histochemical approach to the diagnosis of visceral pleural infiltration by non-small cell lung cancer

INTRODUCTION

Although invasion of the visceral pleura (VPI) by non-small cell lung cancer (NSCLC) is a TNM-relevant diagnostic criterion and is known to affect the patients' prognoses, until recently there were no standardized or internationally accepted guidelines. This resulted in a diagnostic ambiguity leading to different tumor staging systems and to hardly comparable patient collectives in research studies world wide. The major problem in this issue is to exactly define what constitutes for the diagnosis of VPI with respect to anatomical landmarks.

METHODS

In order to address this problem we investigated the pleural infiltration depth of 173 NSCLC specimens without lymph node metastases and proven tumor-related death using elastic stains and a scoring system referring to prominent pleural elastic layers, the lamina elastica externa and interna, as anatomical landmarks.

RESULTS

Performing comparative Kaplan-Meier survival analyses for each patient collective we could not find any significant difference in the patients' survival. This indicates that a differential evaluation of the tumor infiltration depth according to the elastic layers is not practicable.

CONCLUSIONS

Our findings support the consequent application of the recently proposed, pragmatic approach of the international staging committee for lung cancer (IASLC) to define an internationally accepted and standardized staging system for VPI.

Mesothelioma: Do asbestos and carbon nanotubes pose the same health risk?

Carbon nanotubes (CNTs), the product of new technology, may be used in a wide range of applications. Because they present similarities to asbestos fibres in terms of their shape and size, it is legitimate to raise the question of their safety for human health. Recent animal and cellular studies suggest that CNTs elicit tissue and cell responses similar to those observed with asbestos fibres, which increases concern about the adverse biological effects of CNTs. While asbestos fibres' mechanisms of action are not fully understood, sufficient results are available to develop hypotheses about the significant factors underlying their damaging effects. This review will summarize the current state of knowledge about the biological effects of CNTs and will discuss to what extent they present similarities to those of asbestos fibres. Finally, the characteristics of asbestos known to be associated with toxicity will be analyzed to address the possible impact of CNTs.

Pathophysiology of the pleura

The pleural mesothelial cell is an essential cell in maintaining the normal homeostasis of the pleural space and it is also a central component of the pathophysiologic processes affecting the pleural space. In this review, we will review the defense mechanisms of the pleural mesothelium and changes in pleural physiology as a result of inflammatory, infectious, and malignant conditions with a focus on cytokine and chemokine networks. We will also review the processes involved in the pathogenesis of pleural fibrosis.

Impact of Elastic Staining on the Staging of Peripheral Lung Cancers

Accurate staging of lung cancer has a profound impact on patient management. For stage I nonsmall cell lung carcinomas (NSCLCs), the absence (stage IA) or presence (stage IB) of visceral pleural invasion represents a critical therapeutic branch point: patients with stage IB NSCLC benefit from adjuvant chemotherapy, whereas patients with stage IA NSCLC do not. Elastic staining has been advocated as a simple method for visualizing pleural invasion. The purpose of this study was to determine whether routine elastic staining of the resected peripheral NSCLCs alters tumor staging in a meaningful way. The study cases consisted of 100 consecutive peripheral NSCLCs resections that were pathologically staged as IA based on routine histologic assessment. Each case was stained with the Movats pentachrome elastic stain to aid identification of visceral pleural invasion. To assess current standards of surgical pathology practice, members of the American Association of Directors of Anatomic and Surgical Pathology were asked whether they never, sometimes, or always order elastic stains for peripheral NSCLCs that abut the pleura. Elastic staining resulted in a change of tumor stage from IA to IB in 19 (19%) cases. Of the 49 pathologists that responded to the survey, 25 (51%) never, 14 (29%) sometimes, and 10 (20%) always order an elastic stain for NSCLCs abutting the pleura. Elastic staining is currently not standard surgical pathology practice for the evaluation of peripheral NSCLCs, but it should be. Invasion of the pleura is an elusive finding that is best appreciated with an elastic stain. Our experience suggests that routine elastic tissue staining should be performed as a standard method of assessing pleural involvement for pleural-based nonsmall cell lung carcinomas.

Pleural fibrosis

Pleural fibrosis can result from a variety of inflammatory processes. The response of the pleural mesothelial cell to injury and the ability to maintain its integrity are crucial in determining whether normal healing or pleural fibrosis occurs. The pleural mesothelial cell, various cytokines, and disordered fibrin turnover are involved in the pathogenesis of pleural fibrosis. The roles of these mediators in producing pleural fibrosis are examined. This article reviews the most common clinical conditions associated with the development of pleural fibrosis. Fibrothorax and trapped lung are two unique and uncommon consequences of pleural fibrosis. The management of pleural fibrosis, including fibrothorax and trapped lung, is discussed.

The effects of erythromycin on the viability and the secretion of TNF-alpha and TGF-beta1 and expression of connexin43 by human pleural mesothelial cells

OBJECTIVE

The mechanism by which erythromycin produces pleurodesis remains unknown. The purpose of this study was to investigate the effects of erythromycin on human pleural mesothelial cell (HPMC) viability, the secretion of tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta(1) (TGF-beta(1)) and the level of expression of connexin43.

METHODOLOGY

HPMC were incubated with different concentrations of erythromycin. The inhibitory effects of erythromycin on HPMC growth were measured using a tetrazolium-based colorimetric assay. The levels of TNF-alpha and TGF-beta(1) in supernatants were measured by ELISA and levels of connexin43 were assessed by Western blot.

RESULTS

Erythromycin injured HPMC in a dose and time-dependent manner. The secretion of both TNF-alpha and TGF-beta(1) by HMPC increased significantly when they were incubated with 100 mg/L erythromycin for 3 or 5 days. The levels of connexin43 in HPMC decreased after incubation with 100 mg/L erythromycin and no relationship was observed between the levels and incubation time.

CONCLUSIONS

Erythromycin injures HPMC in a dose- and time-dependent manner and results in the secretion of TNF-alpha and TGF-beta(1). This is one possible mechanism of pleurodesis with erythromycin. Furthermore, erythromycin decreased the levels of connexin43 in HPMC, which could possibly affect the response of HPMC to pleurodesis with erythromycin.

Angiogenic factors and angiogenesis inhibitors in exudative pleural effusions

The angiogenesis system has been implicated in inflammatory and neoplastic processes; nevertheless, it has been little studied in relation to the pleural space. Our aim is to analyze pleural and plasma levels of the activators--vascular endothelial growth factor, basic fibroblastic growth factor, and inhibitors--endostatin and thrombospondin-1 and to estimate the association between these factors and related biochemical markers. We analyzed pleural fluid from 105 patients with one of the following types of pleural effusion: empyema or complicated parapneumonic, non-complicated parapneumonic, tuberculous, neoplastic and transudative. Angiogenesis activators were higher in exudates than in transudates (p < 0.001) and in empyema than in non-complicated parapneumonic patients (p < 0.001). Endostatin showed no significant differences. Trombospondin-1 showed higher levels in exudates than in transudates and in empyema than in non-complicated parapneumonic effusions (p < 0.001). In pleural exudates there was a positive correlation of angiogenesis activators and trombospondin-1 with low glucose and pH and high LDH. There was no correlation between pleural and plasma levels of the angiogenesis factors. We conclude that exudative pleural effusions showed higher vascular endothelial growth factor, basic-fibroblastic growth factor and trombospondin-1 values than transudative effusions that associated to low glucose and pH, and high LDH. There was no correlation between pleural and plasma concentrations, suggesting a compartmentalized response.

Visceral pleural invasion in lung cancer: recognizing histologic parameters that impact staging and prognosis

Visceral pleural involvement (VPI) is a critical component in the staging of non-small cell lung carcinoma (NSCLC). Tumors < or =3 cm that involve the visceral pleura are classified as T2 lesions, underscoring the prognostic significance of this histologic parameter. Accurate staging of small NSCLCs depends on appropriately assessing the presence or absence of VPI. Elastic stains can be instrumental in detecting disruptions of the visceral pleural elastic layer by tumor, a finding that has prognostic and staging implications similar to tumor that is present on the visceral pleural surface.

Intrapleural Injection of Transforming Growth Factor-β Antibody Inhibits Pleural Fibrosis in Empyema

STUDY OBJECTIVES

Transforming growth factor (TGF)-beta is a cytokine that has been demonstrated to be an important modulator of inflammation and angiogenesis, as well as a potent stimulator of pleural fluid production and fibrosis. We previously demonstrated that rising levels of pleural fluid TGF-beta(1) correlate with pleural fibrosis in experimental empyema in rabbits. In this study, our hypothesis is that neutralization of TGF-beta with an intrapleural injection of a monoclonal antibody to TGF-beta will decrease pleural fibrosis in empyema.

DESIGN

Prospective, randomized, blinded study.

SETTING

Animal research laboratory.

SUBJECTS

Nineteen rabbits.

INTERVENTIONS

An empyema was induced in 19 rabbits by intrapleural injection of Pasteurella multocida. A panspecific monoclonal antibody to TGF-beta was injected into the pleural space on 2 subsequent concurrent days in nine rabbits. Ten rabbits received intrapleural injections of bacteria alone and served as controls. All animals were then killed on day 6. Immunohistochemistry, using the antibody to TGF-beta, was performed on pleural tissue specimens from the control rabbits.

MEASUREMENTS AND RESULTS

Immunohistochemistry revealed localization of TGF-beta to macrophages in the exudative material and the visceral pleura. After injection of the antibody to TGF-beta, the amount of purulent, exudative material in the pleural space of the nine experimental animals was markedly decreased at autopsy on day 6, relative to control animals. All markers of empyema and pleural fibrosis were also significantly decreased in the rabbits receiving intrapleural anti-TGF-beta.

CONCLUSIONS

TGF-beta localizes to macrophages in experimental empyema. Early intrapleural injection of an antibody to TGF-beta inhibits empyema formation and significantly decreases pleural fibrosis in experimental empyema.

Gene transfer to the pleural mesothelium as a strategy to deliver proteins to the lung parenchyma

The pleura covers the lung parenchyma, chest wall, and diaphragm with a single layer of flat cells that are easy to genetically modify with adenovirus (Ad) vectors. Although intrapleural gene therapy has been used to treat intrapleural disorders, we hypothesized that it may also be used to deliver extracellular gene products to the lung parenchyma. In this context, this study is based on the concept that administration of adenovirus gene transfer vectors into the pleural cavity will mediate expression of gene products in mesothelial cells, and that the extracellular products produced by these genetically modified cells will reach the lung parenchyma. To assess this concept, Ad(beta)gal (expressing beta-galactosidase [beta-Gal]) or AdLuc (expressing luciferase) was administered into the right pleural cavity of BALB/c mice, as compared with intravenous injection via the jugular vein or the intratracheal route. Histologic assessment of lungs and pleural surface after intrapleural administration of Ad(beta)gal demonstrated beta-Gal expression limited to the pleural mesothelium and cells adjacent to the pleural surface. Right intrapleural administration of AdLuc showed higher level of luciferase in both the right and left lung (right vs. left, p > 0.8), compared with the intratracheal (p < 0.05) or intravenous routes (p < 0.02), that is, unilateral intrapleural administration is sufficient to transfer genes bilaterally to the pleura. To assess the ability of intrapleural gene transfer to modify lung parenchymal processes, CT26.CL25 tumor cells (3 x 10(5)) were injected via the jugular vein to generate tumor metastases in the lung parenchyma followed 24 hr later by administration to the right pleura of 5 x 10(8) PFU of Adsflt (an Ad "antiangiogenesis" vector expressing a soluble, secreted, extracellular portion of the Flt-1 receptor for vascular endothelial growth factor). Compared with phosphate-buffered saline, or the control vector AdNull (no transgene), mice receiving Adsflt by the intrapleural route had a marked suppression of tumor growth in the parenchyma of both lungs as assessed 12 days after tumor administration (p < 0.005). Treatment of preestablished lung metastases with Adsflt administered by the intrapleural route significantly improved long-term survival as compared with control animals (p < 0.0001). Thus, although intrapleural administration of an Ad vector encoding an intracellular protein mediates gene expression only in mesothelial cells and the local tissues, intrapleural delivery of a vector expressing a secreted protein can be used to modify processes throughout the lung parenchyma. In the context that intravascular gene transfer is an ineffective strategy to deliver gene products to the lung parenchyma, and that intratracheal administration is associated with alveolar inflammation secondary to host defenses against Ad vectors, these findings demonstrate that intrapleural administration represents a strategy that can be used to effectively deliver extracellular gene products to the lung parenchyma via a site that is readily accessible, and where inflammation against the vector will not have significant pathophysiologic consequences.

Diagnostic value of interleukin-1alpha, interleukin-6, and tumor necrosis factor in pleural effusions

STUDY OBJECTIVES

Interleukin (IL)-1alpha, IL-6, and tumor necrosis factor (TNF)-alpha were measured in pleural fluid from 57 patients with pleural effusion in order to evaluate the diagnostic utility of these cytokines. We studied 20 patients with malignant pleural effusion, 11 patients with parapneumonic pleural effusion, 9 patients with tuberculous pleural effusion, and 17 patients with transudative pleural effusion. Cytokines were measured by radioimmunoassay.

SETTING

University tertiary hospital.

RESULTS

The mean values of the three cytokines measured in pleural fluid or in serum were significantly higher in patients with exudates than with transudates (p < 0.05). The ratio of IL-6 in pleural fluid to serum was significantly higher in exudates than in transudates (p < 0.05). The level of IL-6 in pleural fluid was significantly higher in tuberculous than malignant (p < 0.007) or parapneumonic pleural effusions (p < 0.04). No significant difference between the three types of exudates was found in pleural fluid levels of IL-1alpha or TNF-alpha.

CONCLUSIONS

Serum levels of IL-1alpha, TNF-alpha, and in particular IL-6 can distinguish exudates from transudates, while pleural fluid IL-6 levels could be useful as an additional marker in the differential diagnosis of tuberculous, malignant, and parapneumonic exudates. Finally, our results suggest that there is local cytokine production in exudative pleural effusions.

The many faces of transforming growth factor-beta in pleural diseases

Transforming growth factor (TGF)-beta is responsible for critical regulatory functions in many physiologic and pathologic processes. Emerging evidence suggests that these roles also apply to a multitude of pleural diseases. Both mesothelial cells and infiltrating cells in the pleural space can produce TGFbeta, and elevated TGFbeta concentrations have been found in pleural effusions and in pleural tissues during disease processes. Recent animal studies have suggested that TGFbeta can induce significant pleurodesis and probably plays a central role in the pathogenesis of pleural fibrosis. Paradoxically, TGFbeta may also stimulate increased pleural fluid formation, in part by inducing the production of vascular endothelial growth factor. TGFbeta also participates in the regulation of pleural inflammation and cell proliferation. Further research into the roles of TGFbeta in the pathogenesis of various pleural diseases is needed and may lead to the development of novel treatment strategies.

Use of cytokeratin fragments 19.1 and 19.21 (Cyfra 21-1) in the differentiation of malignant and benign pleural effusions

BACKGROUND

Differentiation between malignant and benign pleural effusions is often difficult. Serum level of Cyfra 21-1, a marker of cytokeratin 19 fragments, has been used in the diagnosis and monitoring of epithelial tumours, especially bronchogenic carcinomas.

AIM

This study is designed to establish the usefulness of effusion Cyfra 21-1 level in differentiating malignant from benign effusions.

METHODS

Forty-eight malignant effusion aspirates (proven by cytology or pleural biopsy) and 34 benign samples were compared. Cyfra 21-1 concentration was measured by a solid phase sandwich radioimmunoassay (Centocur, USA).

RESULTS

Cyfra 21-1 level was significantly higher in malignant effusions (geometric mean 123.6 ng/mL, 95% confidence interval [CI] 76.6-199.4) than in benign ones (geometric mean 14.3 ng/mL, 95% CI 8.5-23.9), p<0.00005. By Receiver Operating Characteristics curve analysis, the sensitivity is 77% for a specificity of 79% if the cut-off is set at 32 ng/mL. No significant difference was observed (p=0.1) in Cyfra 21-1 concentration between adenocarcinoma and mesothelioma effusions. Cyfra 21-1 level was not influenced by the effusion protein concentration (r=0.29), or by renal function as measured by serum creatinine (r=0.1). There was no significant difference between Cyfra 21-1 levels in benign exudate and transudate effusions, p=0.28.

CONCLUSIONS

Cyfra 21-1 is a useful adjunct in the workup of effusions but should not replace conventional investigations as there is considerable overlap in levels between benign and malignant groups. It is unable to differentiate between subgroups of malignancies.

Presence and potent immunosuppressive role of interleukin-10 in malignant pleural effusion due to lung cancer

The presence and possible role of interleukin (IL)-10 were examined in malignant pleural effusion due to lung cancer. In 37 out of 55 cases examined, IL-10 was detectable in pleural effusion and the mean level with standard error was 62.1+/-12.1 pg/ ml. Spontaneous and lipopolysaccharide-induced production of anti-tumor cytokines such as IL-1beta and tumor necrosis factor (TNF)-alpha, by pleural macrophages, obtained from five patients with malignant pleurisy, were suppressed by IL-10. These findings suggest that IL-10 is present in the tumor-growing site and acts as a suppressive factor of local anti-tumor immunity in humans.

MMP and TIMP expression pattern in pleural effusions of different origins

The matrix metalloproteinases (MMP) are proteolytic enzymes that are essentially involved in the turnover of the extracellular matrix (ECM). Their activity is counterbalanced by specific antagonists, the tissue inhibitors of metalloproteinases (TIMP). In this study, we sought to analyze the expression of MMP and TIMP isoforms in pleural effusions from 88 patients. We compared MMP and TIMP isoform expression in transudates (n = 21) and exudates (n = 67), the latter divided into exudates of paraneoplastic (n = 46) or parainfectious (n = 21) origin. Zymographic and Western blot analyses revealed constant expression of interstitial collagenase (MMP-1), gelatinase-A (MMP-2), and TIMP-1 in all 88 samples. In contrast, analyses of gelatinase-B (MMP-9) demonstrated a specific expression pattern, with high expression in exudates and lack of expression in transudates. Neutrophil collagenase (MMP-8) was detected in trace amounts, and correlated with the number of neutrophils in the effusion. Low levels of TIMP-2 were detected only in exudates and not in transudates. Quantitative analysis of the expression ratio of gelatinase-B to gelatinase-A revealed statistically significant differences between effusions of different origin. The ratio was highest in exudates of paraneoplastic origin and lowest in transudates. Our data thus suggest that interstitial collagenase, gelatinase-A, and TIMP-1 play a role in homeostasis of the pleural space in vivo as constitutively expressed proteins, whereas gelatinase-B and TIMP-2 expression are induced in specific disease states. These observations contribute to the understanding of the pathophysiology of pleural effusions, and may help to characterize and possibly distinguish effusions of different origin.

Tissue factor expression in mesothelial cells: induction both in vivo and in vitro

Exudative pleural effusions are characterized by a high protein content and frequently progress to loculation and fibrosis. To test the hypothesis that tissue factor (TF) plays an integral role in this process, we investigated the expression of TF by human mesothelial cells (HMC) both in vivo and in vitro, and measured the effect of serum on HMC expression of TF in vitro. In vivo TF expression was not detected in HMC of normal pleura, but was detected in HMC of pleura overlying inflamed lung. In vitro, quiescent HMC demonstrated negligible levels of TF expression; however, upon serum stimulation there was a marked induction in both TF protein level and activity, peaking at 8-9 h. In contrast, treating quiescent HMC with plasma resulted in a further small, but significant, decrease in TF expression. This serum-induced rise in TF was also reflected in TF mRNA levels and did not require de novo protein synthesis. These results suggest that induction of HMC TF expression may be important in triggering both the intrapleural activation of prothrombin and the deposition of fibrin characteristic of inflammatory effusions.

Elevation of interleukin-10 levels in malignant pleural effusion

STUDY OBJECTIVE

Human immunity has been found to have two major components, cellular and humoral immunity. T-helper type 1 (Th1) pathway favors cellular immunity and Th2 pathway favors humoral immunity. Early determination toward Th1 and Th2 cells in the immune response is dependent on the balance between interleukin-12 (IL-12), which favors Th1 responses, and IL-4, which favors Th2 responses. IL-2 and interferon-gamma (IFN-gamma) are produced in the Th1 pathway, and IL-4 and IL-10 are produced in the Th2 pathway. Lack of cellular immunity, IL-2, and IFN-gamma had been reported in malignant pleural effusions. However, to our knowledge, there are no previous reports on other cytokine components involving Th1 or Th2 pathway. The present study was designed to answer these questions.

DESIGN

Cytokine levels in peripheral blood and pleural fluid of 21 patients with malignant pleural effusion, including IL-4, IL-10, and IL-12, were analyzed with enzyme-linked immunosorbent assays. Lymphocyte subpopulations of peripheral blood and pleural effusion were also studied by using flow cytometry.

MEASUREMENTS AND RESULTS

The results showed a significant increase in IL-10 level as compared with blood samples. IL-4 and IL-12 were below minimal detectable concentrations both in the blood and the effusion. The ratio of pleural helper T cells was significantly higher than in the blood (p = 0.0002). The ratio of pleural natural killer (NK) cells was significantly lower than in the blood (p = 0.0001). The ratio of pleural suppressor T cells was lower than blood with borderline significance (p = 0.0522). No significant change in B-lymphocyte ratio between blood and pleural effusion was found (p = 0.2471). There was no correlation between difference in IL-10 level and lymphocyte subpopulation of pleural effusion and blood samples.

CONCLUSIONS

Helper T-cell subpopulations were increased while NK and suppressor T-cell subpopulations were decreased in malignant pleural effusions. The decrease in NK cell subpopulations with elevated IL-10 and minimal IL-12 concentration in neoplastic pleural effusion would suggest the usage of IL-12 or antibody of IL-10 to improve local cellular immunity. Further study is needed.