Interstitial lung disease in systemic sclerosis

Critical Role of LMCD1 in Promoting Profibrotic Characteristics of Lung Myofibroblasts in Experimental and Scleroderma-Associated Lung Fibrosis

OBJECTIVE

Interstitial lung disease (ILD) is a serious complication and leading cause of mortality in patients with systemic sclerosis (SSc). In this study, we explored the role of LIM and cysteine-rich domains protein 1 (LMCD1) as a novel factor in the pathogenesis of SSc-related ILD (SSc-ILD).

METHODS

The expression and effects of LMCD1 were studied in lung tissue samples and fibroblasts from SSc-ILD patients and control subjects as well as in lung tissue samples from animal models.

RESULTS

LMCD1 was consistently elevated in lung tissue samples and in fibroblasts isolated from SSc-ILD patients as compared to controls. Additionally, LMCD1 was found to be highly expressed in the lung in the fibroblast-specific protein (FSP)-driven, constitutively active transforming growth factor β receptor type I (TGFβR1) transgenic mouse model of ILD and the bleomycin-induced mouse model of ILD. In lung fibroblasts from SSc-ILD patients, LMCD1 is an essential factor for the TGFβ-induced generation of type I collagen, fibronectin, and α-smooth muscle actin (α-SMA). Depletion of LMCD1 by small interfering RNA reduced the expression of extracellular matrix proteins and lowered transcriptional activity and expression of α-SMA, as well as decreased the proliferation and contractile activity of SSc-ILD lung fibroblasts. In dense fibrotic areas of affected lung tissue, lung LMCD1 colocalized with α-SMA. In cultured scleroderma lung fibroblasts, LMCD1 colocalized and interacted with serum response factor which mediates LMCD1-induced contractile activity of lung fibroblasts.

CONCLUSION

Our study identifies LMCD1 as a profibrotic molecule contributing to the activation of myofibroblasts and the persistent fibroproliferation observed in SSc-ILD. Thus, LMCD1 may be a potential novel therapeutic target for patients with SSc-ILD.

Machine learning associated with respiratory oscillometry: a computer-aided diagnosis system for the detection of respiratory abnormalities in systemic sclerosis

INTRODUCTION

The use of machine learning (ML) methods would improve the diagnosis of respiratory changes in systemic sclerosis (SSc). This paper evaluates the performance of several ML algorithms associated with the respiratory oscillometry analysis to aid in the diagnostic of respiratory changes in SSc. We also find out the best configuration for this task.

METHODS

Oscillometric and spirometric exams were performed in 82 individuals, including controls (n = 30) and patients with systemic sclerosis with normal (n = 22) and abnormal (n = 30) spirometry. Multiple instance classifiers and different supervised machine learning techniques were investigated, including k-Nearest Neighbors (KNN), Random Forests (RF), AdaBoost with decision trees (ADAB), and Extreme Gradient Boosting (XGB).

RESULTS AND DISCUSSION

The first experiment of this study showed that the best oscillometric parameter (BOP) was dynamic compliance, which provided moderate accuracy (AUC = 0.77) in the scenario control group versus patients with sclerosis and normal spirometry (CGvsPSNS). In the scenario control group versus patients with sclerosis and altered spirometry (CGvsPSAS), the BOP obtained high accuracy (AUC = 0.94). In the second experiment, the ML techniques were used. In CGvsPSNS, KNN achieved the best result (AUC = 0.90), significantly improving the accuracy in comparison with the BOP (p < 0.01), while in CGvsPSAS, RF obtained the best results (AUC = 0.97), also significantly improving the diagnostic accuracy (p < 0.05). In the third, fourth, fifth, and sixth experiments, different feature selection techniques allowed us to spot the best oscillometric parameters. They resulted in a small increase in diagnostic accuracy in CGvsPSNS (respectively, 0.87, 0.86, 0.82, and 0.84), while in the CGvsPSAS, the best classifier's performance remained the same (AUC = 0.97).

CONCLUSIONS

Oscillometric principles combined with machine learning algorithms provide a new method for diagnosing respiratory changes in patients with systemic sclerosis. The present study's findings provide evidence that this combination may help in the early diagnosis of respiratory changes in these patients.

Prevalence and clinical correlates of small airway obstruction in patients with systemic sclerosis

OBJECTIVES

This study aims to assess the prevalence and clinical correlates of small airway obstruction (SAO) in patients with systemic sclerosis (SSc).

METHODS

Sixty-nine consecutive patients with SSc (63 women and 6 men) were included. Lung function tests, including assessment of lung diffusing capacity, were performed in all patients. Patients were considered to have SAO when the maximal expiratory flow at 25% of the forced vital capacity (MEF₂₅) was lower than 60% as predicted. High-resolution computed tomography (HRCT) of the lung was performed in all patients with MEF₂₅ < 60%. We assessed the relationship of SAO in our patients with large airway obstruction, decreased lung diffusing capacity, HRCT findings, disease duration, disease subtype, scleroderma-specific antibodies, and smoking.

RESULTS

SAO was noticed in 46/69 (66.6%) of patients with SSc. Restrictive lung disease was found in 4/69 (5.8%), obstruction of large airways in 18/69 (26.1%), and decreased lung diffusing capacity in 47/69 (68.1%) of patients. No difference in gender, age, disease duration, disease subtype, and scleroderma-specific antibodies was found between patients with and without SAO. Eighteen out of forty-six (39.1%) patients with SAO had decreased forced expiratory volume in 1 sec (FEV₁) and the Tiffeneau-Pinelli index, indicating presence of coexistent large airway obstruction. Twenty out of forty-six (43.5%) patients with SAO had associated decreased lung diffusing capacity, while 8/46 (17.4%) of patients had isolated SAO. HRCT patterns of interstitial lung disease (ILD) were found more frequently in patients with SAO and decreased lung diffusing capacity, compared with patients with SAO and normal diffusing capacity (75% vs 11.5%, p = 0.008). We have noticed that tobacco smokers among SSc patients with SAO have more common associated obstructive lung disease on spirometry (58.8% vs 15.4%, p = 0.004). On the other hand, isolated SAO and SAO associated with impaired diffusing capacity were equally frequent among smokers and non-smokers.

CONCLUSION

Patients with SSc have commonly SAO. It can be considered clinical feature of undiagnosed asthma or chronic obstructive pulmonary disease (COPD), if isolated or associated with large airway obstruction, especially in tobacco smokers. On the other hand, SAO associated with decreased lung diffusing capacity was found to be not related to smoking, and may indicate a possible prominent bronchiolar involvement within SSc-related interstitial lung disease Key Points • Small airway obstruction in patients with systemic sclerosis can be considered a clinical feature of undiagnosed obstructive lung disease, if isolated or associated with large airway obstruction, especially in tobacco smokers. • Obstruction of small airways, associated with decreased lung diffusing capacity, may indicate a possible prominent bronchiolar involvement within systemic sclerosis-related interstitial lung disease.

Expert Perspectives On Clinical Challenges: Expert Perspectives: Challenges in Scleroderma

You are consulted to evaluate a 56-year-old woman with known Raynaud's phenomenon, finger swelling of several; months' duration, and new hypertension with a blood pressure of 160/100 mm/Hg. She also reports progressive shortness of breath. Physical examination reveals telangiectasias, sclerodactyly, and proximal skin sclerosis (thick shiny skin on the chest and upper arms), and bibasilar crackles are found on chest examination. Laboratory tests reveal evidence of microangiopathic hemolytic anemia, thrombocytopenia, and elevation of the serum creatinine level (previously normal), and chest computed tomography shows evidence of ground-glass opacification in both lower lung fields.

Autoantibodies as biomarkers for interstitial lung disease in idiopathic inflammatory myositis and systemic sclerosis: The case of anti-eIF2B antibodies

Objectives

Serum autoantibodies are pivotal for the early detection of systemic autoimmune rheumatic diseases such as Systemic Sclerosis (SSc) and Poly/Dermatomyositis (PM/DM), and in some cases are associated with organ complications such as interstitial lung disease (ILD). A paradigmatic example is provided by the autoantibody against the Eukaryotic Initiation Factor 2B (eIF2B) that has been recently detected in SSc.

Methods

Sera from 118 patients with SSc, 8 Poly/Dermatomyositis, 2 overlap SSc/Polymyositis, 4 undifferentiated connective tissue disease-UCTD and 3 healthy controls were tested first by indirect immunofluorescence for anti-nuclear antibodies-ANA pattern. Further, we employed protein-radioimmunoprecipitation (IP) and IP- Western Blot for the detection and confirmation of anti-eIF2B antibodies. Serum findings were further correlated with the clinical features of patients.

Results

We identified 3 SSc cases (2.5%) positive for anti-eIF2B antibodies while this autoantibody was not detected in control sera. Using protein-IP all three patients manifested the 38kD protein which is the antigenic target of anti-eIF2B antibodies, and this was associated with a cytoplasmic pattern at indirect immunofluorescence. The presence of anti-eIF2B was associated with ILD and a diffuse SSc variant, in one case in association with anti-Scl70/topoI.

Conclusions

Our data confirm that a small subgroup (2.5%) of patients with SSc have detectable anti-eIF2B with cytoplasmic-positive staining at immunofluorescence and this reactivity is associated with ILD.

A methodology for exploring biomarker--phenotype associations: application to flow cytometry data and systemic sclerosis clinical manifestations

Background

This work seeks to develop a methodology for identifying reliable biomarkers of disease activity, progression and outcome through the identification of significant associations between high-throughput flow cytometry (FC) data and interstitial lung disease (ILD) - a systemic sclerosis (SSc, or scleroderma) clinical phenotype which is the leading cause of morbidity and mortality in SSc. A specific aim of the work involves developing a clinically useful screening tool that could yield accurate assessments of disease state such as the risk or presence of SSc-ILD, the activity of lung involvement and the likelihood to respond to therapeutic intervention. Ultimately this instrument could facilitate a refined stratification of SSc patients into clinically relevant subsets at the time of diagnosis and subsequently during the course of the disease and thus help in preventing bad outcomes from disease progression or unnecessary treatment side effects.

The methods utilized in the work involve: (1) clinical and peripheral blood flow cytometry data (Immune Response In Scleroderma, IRIS) from consented patients followed at the Johns Hopkins Scleroderma Center. (2) machine learning (Conditional Random Forests - CRF) coupled with Gene Set Enrichment Analysis (GSEA) to identify subsets of FC variables that are highly effective in classifying ILD patients; and (3) stochastic simulation to design, train and validate ILD risk screening tools.

Results

Our hybrid analysis approach (CRF-GSEA) proved successful in predicting SSc patient ILD status with a high degree of success (>82 % correct classification in validation; 79 patients in the training data set, 40 patients in the validation data set).

Conclusions

IRIS flow cytometry data provides useful information in assessing the ILD status of SSc patients. Our new approach combining Conditional Random Forests and Gene Set Enrichment Analysis was successful in identifying a subset of flow cytometry variables to create a screening tool that proved effective in correctly identifying ILD patients in the training and validation data sets. From a somewhat broader perspective, the identification of subsets of flow cytometry variables that exhibit coordinated movement (i.e., multi-variable up or down regulation) may lead to insights into possible effector pathways and thereby improve the state of knowledge of systemic sclerosis pathogenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-015-0722-x) contains supplementary material, which is available to authorized users.

Cellular interactions in the pathogenesis of interstitial lung diseases

Interstitial lung disease (ILD) encompasses a large and diverse group of pathological conditions that share similar clinical, radiological and pathological manifestations, despite potentially having quite different aetiologies and comorbidities. Idiopathic pulmonary fibrosis (IPF) represents probably the most aggressive form of ILD and systemic sclerosis is a multiorgan fibrotic disease frequently associated with ILD. Although the aetiology of these disorders remains unknown, in this review we analyse the pathogenic mechanisms by cell of interest (fibroblast, fibrocyte, myofibroblast, endothelial and alveolar epithelial cells and immune competent cells). New insights into the complex cellular contributions and interactions will be provided, comparing the role of cell subsets in the pathogenesis of IPF and systemic sclerosis.

Distinct cell populations contribute to the complex pathogenesis of IPF and systemic sclerosis-associated ILDhttp://ow.ly/AjFaz

On the respiratory mechanics measured by forced oscillation technique in patients with systemic sclerosis

Background

Pulmonary complications are the most common cause of death and morbidity in systemic sclerosis (SSc). The forced oscillation technique (FOT) offers a simple and detailed approach to investigate the mechanical properties of the respiratory system. We hypothesized that SSc may introduce changes in the resistive and reactive properties of the respiratory system, and that FOT may help the diagnosis of these abnormalities.

Methodology/Principal Findings

We tested these hypotheses in controls (n = 30) and patients with abnormalities classified using spirometry (n = 52) and pulmonary volumes (n = 29). Resistive data were interpreted with the zero-intercept resistance (Ri) and the slope of the resistance (S) as a function of frequency. Reactance changes were evaluated by the mean reactance between 4 and 32 Hz (Xm) and the dynamic compliance (Crs,dyn). The mechanical load was evaluated using the absolute value of the impedance in 4 Hz (Z4Hz). A compartmental model was used to obtain central (R) and peripheral (Rp) resistances, and alveolar compliance (C). The clinical usefulness was evaluated by investigating the area under the receiver operating characteristic curve (AUC). The presence of expiratory flow limitation (EFL) was also evaluated. For the groups classified using spirometry, SSc resulted in increased values in Ri, R, Rp and Z4Hz (p<0.003) and reductions in Crs,dyn, C and Xm (p<0.004). Z4Hz, C and Crs,dyn exhibited a high diagnostic accuracy (AUC>0.90). In groups classified by pulmonary volume, SSc resulted in reductions in S, Xm, C and Crs,dyn (p<0.01). Xm, C and Crs,dyn exhibited adequate diagnostic accuracy (AUC>0.80). It was also observed that EFL is not common in patients with SSc.

Conclusions/Significance

This study provides evidence that the respiratory resistance and reactance are changed in SSc. This analysis provides a useful description that is of particular significance for understanding respiratory pathophysiology and to ease the diagnosis of respiratory abnormalities in these patients.

The PPARγ Agonist Rosiglitazone Is Antifibrotic for Scleroderma Lung Fibroblasts: Mechanisms of Action and Differential Racial Effects

We present novel data demonstrating that the expression of PPARγ is reduced in lung fibroblasts from black SSc-ILD patients as compared to white patients. Activating PPARγ with the agonist rosiglitazone increased the expression of MMP-1 and inhibited collagen type I in lung fibroblasts isolated from white, but not black, SSc-ILD patients. Blocking the c-Met receptor abolishes rosiglitazone's effects on collagen and MMP-1 in lung fibroblasts isolated from white SSc-ILD patients, while augmenting the expression of the c-Met receptor in fibroblasts from black SSc-ILD patients replicates the effects of rosiglitazone seen in whites. We conclude that PPARγ agonists warrant consideration as potential antifibrotic drugs in patients with SSc-ILD. Differential therapeutic effects might be anticipated especially relative to racial differences and the functional expression of the c-Met receptor.

Efficacy of cyclophospamide in the treatment of interstitial lung disease associated with systemic sclerosis

BACKGROUND

Cyclophosphamide (CYC) stabilizes the parameters of lung function tests (LFT) of patients with (SSc) and interstitial lung disease (ILD) treated for 12 months. There is little information about long-term treatment (24 months). The aim of this study is to analyze the effect of intravenous CYC in LFT parameters in patients with SSc and ILD treated for 24 months.

PATIENTS AND METHOD

Retrospective study of 37 patients with ILD associated with scleroderma treated with intravenous CYC for 24 months and regularly assessed by LFT (at baseline, 6, 12 and 24 months) including forced vital capacity (FVC) and transfer capacity of carbon monoxide (DL(CO)). To evaluate response to treatment the recommendations of the ATS and SEPAR were considered.

RESULTS

The difference between FVC and DL(CO) values performed at baseline and those performed at 6, 12, and 24 months were less than 10%, which meant that CYC stabilized LFT. There were no differences in LFT when patients treated for 6 months were evaluated according to the type of skin involvement of the SSc (diffuse or limited) and the duration of the ILD. Although patients with severe restriction (FVC<70%) showed more improvement, it was less than 10% in all cases.

CONCLUSION

In this series of patients with ILD associated with SSc intravenous CYC was effective in stabilizing LFT in long-term treatment.

Induced sputum as a method for detection of systemic sclerosis-related interstitial lung disease

Inducted sputum (IS) is a non-invasive procedure that can be used for collection of airway secretions. The aim of our study is to evaluate the clinical usefulness of IS for detection of airway inflammation in systemic sclerosis (SSc). Bronchoalveolar lavage and IS were performed to 20 patients with SSc. Eighteen patients who were referred to pulmonary medicine for bronchoalveolar lavage due to other reasons were also recruited for cell counts comparisons. Spirometry, echocardiography and thorax CT (HRCT) imaging were also performed to all patients. Mean macrophage and lymphocyte counts were found to be increased in IS of SSc patients compared with that of control (58.4 ± 14.5% vs. 31.3 ± 16.3%, 30.2 ± 15.4% vs. 15.0 ± 11.5% P < 0.001), whereas mean neutrophil count was lower in the SSc patients (4.1 ± 4.5% vs. 17.2 ± 13.1%, P < 0.05). Significant correlations were noted between BAL and IS findings for macrophage (r = 0.55, P = 0.02) lymphocyte (r = 0.65, P < 0.01) and total cell counts (r = 0.45, P = 0.06). IS is an easy and reliable method for the detection of alveolitis and can be used for early detection of lung involvement in scleroderma.

Coagulation and autoimmunity in scleroderma interstitial lung disease

OBJECTIVES

Interstitial lung disease in systemic sclerosis (SSc-ILD) is often an irreversible and progressive fibrosing process that now is the leading cause of scleroderma-related deaths. In this review we present our current understanding of the role played by coagulation and particularly by thrombin in autoimmune-mediated tissue injury and fibrosis, mainly as it relates to SSc-ILD.

METHODS

We used PubMed to search for articles published up to October 2010 for keywords referring to autoimmunity, coagulation, pulmonary fibrosis, and scleroderma.

RESULTS

SSc-ILD is an autoimmune disease associated with lymphocyte activation and release of various cytokines and growth factors. The production of autoantibodies is a central feature in SSc. Activation of the coagulation cascade with release of thrombin is 1 of the earliest events following tissue injury. Thrombin contributes to autoimmune responses by activating of pathogenic Th2 lymphocyte profile in SSc. Thrombin also modulates tissue repair responses, stimulates transformation of epithelial cells, endothelial cells, and fibroblasts into myofibroblast phenotype, and induces secretion of several pro-immune and profibrotic factors, which serve as antigens for pathogenic autoantibodies production in SSc-ILD.

CONCLUSIONS

The identification of links between autoimmunity and coagulation would provide new insights into the pathogenesis of pulmonary fibrosis associated with autoimmune diseases and further acknowledge the importance of thrombin in the development of SSc-ILD.

Dabigatran, a direct thrombin inhibitor, demonstrates antifibrotic effects on lung fibroblasts

OBJECTIVE

Myofibroblasts are the principal mesenchymal cells responsible for tissue remodeling, collagen deposition, and the restrictive nature of lung parenchyma associated with pulmonary fibrosis. We previously reported that thrombin activates protease-activated receptor 1 (PAR-1) and induces a myofibroblast phenotype in normal lung fibroblasts resembling the phenotype of scleroderma lung myofibroblasts. We undertook this study to investigate whether a selective direct thrombin inhibitor, dabigatran, interferes with signal transduction in human lung fibroblasts induced by thrombin and mediated via PAR-1.

METHODS

Lung fibroblast proliferation was analyzed using the Quick Cell Proliferation Assay. Expression and organization of alpha-smooth muscle actin (alpha-SMA) was studied by immunofluorescence staining and immunoblotting. Contractile activity of lung fibroblasts was measured by a collagen gel contraction assay. Connective tissue growth factor (CTGF) and type I collagen expression was analyzed on Western blots.

RESULTS

Dabigatran, at concentrations of 50-1,000 ng/ml, inhibited thrombin-induced cell proliferation, alpha-SMA expression and organization, and the production of collagen and CTGF in normal lung fibroblasts. Moreover, when treated with dabigatran (1 microg/ml), scleroderma lung myofibroblasts produced 6-fold less alpha-SMA, 3-fold less CTGF, and 2-fold less type I collagen compared with untreated cells.

CONCLUSION

Dabigatran restrains important profibrotic events in lung fibroblasts and warrants study as a potential antifibrotic drug for the treatment of fibrosing lung diseases such as scleroderma lung disease and idiopathic pulmonary fibrosis.

A TGFbeta-responsive gene signature is associated with a subset of diffuse scleroderma with increased disease severity

Systemic sclerosis is a complex disease with widespread skin fibrosis and variable visceral organ involvement. Since transforming growth factor-beta (TGFbeta) has been implicated in driving fibrosis in systemic sclerosis, a mechanism-derived gene expression signature was used to assay TGFbeta-responsive gene expression in the skin of patients with systemic sclerosis (SSc). Primary dermal fibroblasts from patients with diffuse SSc (dSSc) and healthy controls were treated with TGFbeta, and the genome-wide gene expression was measured on DNA microarrays over a time course of 24 hours. Eight hundred and ninety-four probes representing 674 uniquely annotated genes were identified as TGFbeta responsive. Expression of the TGFbeta-responsive signature was examined in skin biopsies from 17 dSSc, seven limited SSc (lSSc), three morphea patients, and six healthy controls. The TGFbeta-responsive signature was expressed in 10 out of 17 dSSc skin biopsies, but was not found in lSSc, morphea, or healthy control biopsies. Expression of dSSC the TGFbeta-responsive signature stratifies patients into two major groups, one of which corresponds to the "diffuse-proliferation" intrinsic subset that showed higher modified Rodnan skin score and a higher likelihood of scleroderma lung disease. The TGFbeta-responsive signature is found in only a subset of dSSc patients who could be targeted by specific therapies.

Spectrum of fibrosing diffuse parenchymal lung disease

The interstitial lung diseases are a heterogeneous group of disorders characterized by inflammation and/or fibrosis of the pulmonary interstitium. In 2002, the American Thoracic Society and the European Respiratory Society revised the classification of interstitial lung diseases and introduced the term diffuse parenchymal lung disease. The idiopathic interstitial pneumonias are a subtype of diffuse parenchymal lung disease. The idiopathic interstitial pneumonias are subdivided into usual interstitial pneumonia (with its clinical counterpart idiopathic interstitial pneumonia), nonspecific interstitial pneumonia, cryptogenic organizing pneumonia, acute interstitial pneumonia, desquamative interstitial pneumonia, respiratory bronchiolitis interstitial lung disease, and lymphocytic pneumonia. Sarcoidosis and hypersensitivity pneumonitis are the 2 most common granulomatous diffuse parenchymal lung diseases. Rheumatoid arthritis, systemic sclerosis, and dermatomyositis/polymyositis (causing antisynthetase syndrome) are diffuse parenchymal lung diseases of known association because these conditions are associated with connective tissue disease. Hermansky-Pudlak syndrome is a rare genetic diffuse parenchymal lung disease characterized by the clinical triad of pulmonary disease, oculocutaneous albinism, and bleeding diathesis. This review provides an overview of the chronic fibrosing diffuse parenchymal lung diseases. Its primary objective is to illuminate the clinical challenges encountered by clinicians who manage the diffuse parenchymal lung diseases regularly and to offer potential solutions to those challenges. Treatment for the diffuse parenchymal lung diseases is limited, and for many patients with end-stage disease, lung transplantation remains the best option. Although much has been learned about the diffuse parenchymal lung diseases during the past decade, research in these diseases is urgently needed.