Interstitial lung diseases of unknown cause. Disorders characterized by chronic inflammation of the lower respiratory tract (first of two parts)

Computed tomography measure of lung injury and future interstitial features: the CARDIA Lung Study

Introduction

Visually normal areas of the lung with high attenuation on computed tomography (CT) imaging, termed CT lung injury, may represent injured but not yet remodelled lung parenchyma. This prospective cohort study examined if CT lung injury is associated with future interstitial features on CT and restrictive spirometry abnormality among participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study.

Methods

CARDIA is a population-based cohort study. CT scans obtained at two time points were assessed objectively for amount of lung tissue characterised as CT lung injury and interstitial features. Restrictive spirometry was defined as having a forced vital capacity (FVC) <80% predicted with forced expiratory volume in 1 s/FVC ratio >70%.

Results

Among 2213 participants, the median percentage of lung tissue characterised as CT lung injury at a mean age of 40 years was 3.4% (interquartile range 0.8-18.0%). After adjustment for covariates, a 10% higher amount of CT lung injury at mean age 40 years was associated with a 4.37% (95% CI 3.99-4.74%) higher amount of lung tissue characterised as interstitial features at mean age 50 years. Compared to those with the lowest quartile of CT lung injury at mean age 40 years, there were higher odds of incident restrictive spirometry at mean age 55 years in quartile 2 (OR 2.05, 95% CI 1.20-3.48), quartile 3 (OR 2.80, 95% CI 1.66-4.72) and quartile 4 (OR 3.77, 95% CI 2.24-6.33).

Conclusions

CT lung injury is an early objective measure that indicates risk of future lung impairment.

Rethinking Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease for patients and their loved ones. Since initial efforts to characterize this disease in the 1960s, understanding of IPF has evolved considerably. Such evolution has continually challenged prior diagnostic and treatment paradigms, ushering in an era of higher confidence diagnoses with less invasive procedures and more effective treatments. This review details how research and clinical experience over the past half century have led to a rethinking of IPF. Here, the evolution in understanding of IPF pathogenesis, diagnostic evaluation and treatment approach is discussed.

Danshensu alleviates bleomycin-induced pulmonary fibrosis by inhibiting lung fibroblast-to-myofibroblast transition via the MEK/ERK signaling pathway

Pulmonary fibrosis (PF) is a chronic pulmonary interstitial disease, and its pathological process is closely related to fibroblast-myofibroblast differentiation. Danshensu (DSS) has been reported to exert an anti-fibrotic effect in heart and liver. However, it is unknown whether DSS has an equally anti-fibrotic effect on lungs. To evaluate the effect of DSS on PF and demonstrate its possible molecular mechanisms, we established an in vitro model on TGF-β1 (5 ng/mL)-stimulated NIH3T3 cells and in vivo model on bleomycin (BLM) (5 mg/kg)-induced PF mice. In vitro, our results revealed that 50 μM DSS effectively inhibited the fibroblast proliferation, migration and differentiation into myofibroblast. In vivo, our results showed that DSS (28 and 56 mg/kg) reduced damaged lung structures, infiltrated inflammatory cells and accumulated areas of collagen deposition. Moreover, we showed that DSS decreased the fibroblast-specific protein 1 (FSP-1) - and α-SMA-positive areas. Meanwhile, we indicated that DSS reduced the expression of TGF-β1, α-SMA and COL-I in the lung tissues of mice. To further explore the mechanism of DSS on alleviating PF, we detected the MEK/ERK signaling pathway. Our results showed that DSS reduced the phosphorylation of MEK1/2 and ERK1/2, indicating that DSS might inhibit the MEK/ERK signaling pathway. Taken together, these results demonstrated that DSS could suppress lung fibroblast proliferation, migration and differentiation to myofibroblasts, possibly through suppressing the MEK/ERK signaling pathway, which suggested that DSS might be a potential therapeutic drug for PF treatment.

The prevalence of obstructive sleep apnea in interstitial lung disease: a systematic review and meta-analysis

PURPOSE

To evaluate the overall prevalence of obstructive sleep apnea (OSA) in interstitial lung disease (ILD).

METHODS

We performed a systematic search of the academic literature while adhering to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines on four scientific databases including EMBASE, CENTRAL, Scopus, and MEDLINE. We performed a meta-analysis to evaluate the prevalence and severity of OSA. Severity was defined by apnea-hypopnea index (AHI) as mild (AHI ≥ 5 to < 15/h), moderate (AHI ≥ 15 to < 30/h), and severe (AHI ≥ 30/h).

RESULTS

From 1397 studies, we found 10 eligible studies with 569 patients with ILD (mean age: 65.3 ± 6.0 years). Among these patients, 332 (61%) suffered from OSA with 32% categorized as mild, 17% moderate, and 9% severe.  CONCLUSION: This systematic review and meta-analysis provides preliminary evidence regarding the high prevalence of OSA in ILD.

Dysregulation of club cell biology in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, chronic fibrotic lung disease with an irreversible decline of lung function. "Bronchiolization", characterized by ectopic appearance of airway epithelial cells in the alveolar regions, is one of the characteristic features in the IPF lung. Based on the knowledge that club cells are the major epithelial secretory cells in human small airways, and their major secretory product uteroglobin (SCGB1A1) is significantly increased in both serum and epithelial lining fluid of IPF lung, we hypothesize that human airway club cells contribute to the pathogenesis of IPF. By assessing the transcriptomes of the single cells from human lung of control donors and IPF patients, we identified two SCGB1A1+ club cell subpopulations, highly expressing MUC5B, a significant genetic risk factor strongly associated with IPF, and SCGB3A2, a marker heterogeneously expressed in the club cells, respectively. Interestingly, the cellular proportion of SCGB1A1+MUC5B+ club cells was significantly increased in IPF patients, and this club cell subpopulation highly expressed genes related to mucous production and immune cell chemotaxis. In contrast, though the cellular proportion did not change, the molecular phenotype of the SCGB1A1+SCGB3A2high club cell subpopulation was significantly altered in IPF lung, with increased expression of mucins, cytokine and extracellular matrix genes. The single cell transcriptomic analysis reveals the cellular and molecular heterogeneity of club cells, and provide novel insights into the biological functions of club cells in the pathogenesis of IPF.

Emodin inhibiting neutrophil elastase-induced epithelial-mesenchymal transition through Notch1 signalling in alveolar epithelial cells

The transition of alveolar type II epithelial cells into fibroblasts has been reported to cause and/or aggravate pulmonary fibrosis (PF), which is characterized by fibroblast proliferation, an enhanced production and accumulation of ECM (extracellular matrix), alveolar wall damage and functional capillary unit loss. Traditional Chinese medicine Emodin has been reported to inhibit TGF‐β‐induced epithelial‐mesenchymal transition (EMT) in alveolar epithelial cells through Notch signalling. In the present study, neutrophil elastase (NE, also known as ELA2) treatment promoted EMT, Notch1 cleavage (NICD/Notch1 ratio increase) and NICD nuclear translocation in RLE‐6TN cells and A549 cells. The promotive roles of NE treatment in these events were significantly reversed by Notch1 knockdown. Traditional Chinese medicine Emodin treatment remarkably inhibited the enzyme activity of NE, suppressed EMT, Notch1 cleavage and NICD nuclear translocation within RLE‐6TN and A549 cells, while NE treatment significantly reversed the effects of Emodin. Moreover, in RLE‐6TN, the effects of NE on EMT, Notch1 cleavage and NICD nuclear translocation were remarkably attenuated by Emodin treatment and more attenuated by the combination of Emodin and neutrophil elastase inhibitor Sivelestat or notch signal pathway inhibitor DAPT. In conclusion, we revealed the involvement of NE‐induced Notch1 cleavage in the functions of Emodin suppressing NE‐caused EMT in RLE‐6TN cells and A549 cells. This novel mechanism of Emodin inhibiting EMT might extend the application of Emodin in PF treatment.

Transcriptomic Evaluation of Pulmonary Fibrosis-Related Genes: Utilization of Transgenic Mice with Modifying p38 Signal in the Lungs

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrosing lung disease that is caused by the dysregulation of alveolar epithelial type II cells (AEC II). The mechanisms involved in the progression of IPF remain incompletely understood, although the immune response accompanied by p38 mitogen-activated protein kinase (MAPK) activation may contribute to some of them. This study aimed to examine the association of p38 activity in the lungs with bleomycin (BLM)-induced pulmonary fibrosis and its transcriptomic profiling. Accordingly, we evaluated BLM-induced pulmonary fibrosis during an active fibrosis phase in three genotypes of mice carrying stepwise variations in intrinsic p38 activity in the AEC II and performed RNA sequencing of their lungs. Stepwise elevation of p38 signaling in the lungs of the three genotypes was correlated with increased severity of BLM-induced pulmonary fibrosis exhibiting reduced static compliance and higher collagen content. Transcriptome analysis of these lung samples also showed that the enhanced p38 signaling in the lungs was associated with increased transcription of the genes driving the p38 MAPK pathway and differentially expressed genes elicited by BLM, including those related to fibrosis as well as the immune system. Our findings underscore the significance of p38 MAPK in the progression of pulmonary fibrosis.

Increased flux through the mevalonate pathway mediates fibrotic repair without injury

Macrophages are important in mounting an innate immune response to injury as well as in repair of injury. Gene expression of Rho proteins is known to be increased in fibrotic models; however, the role of these proteins in idiopathic pulmonary fibrosis (IPF) is not known. Here, we show that BAL cells from patients with IPF have a profibrotic phenotype secondary to increased activation of the small GTPase Rac1. Rac1 activation requires a posttranslational modification, geranylgeranylation, of the C-terminal cysteine residue. We found that by supplying more substrate for geranylgeranylation, Rac1 activation was substantially increased, resulting in profibrotic polarization by increasing flux through the mevalonate pathway. The increased flux was secondary to greater levels of acetyl-CoA from metabolic reprogramming to β oxidation. The polarization mediated fibrotic repair in the absence of injury by enhancing macrophage/fibroblast signaling. These observations suggest that targeting the mevalonate pathway may abrogate the role of macrophages in dysregulated fibrotic repair.

Diagnostic Accuracy of Multidetector CT in Detection of Early Interstitial Lung Disease With Its Role in Characterization

Background

Multidetector CT (MDCT) has emerged as a useful option for early diagnosis of interstitial lung disease (ILD) with adequate accuracy.

Methods

A total of 80 patients with restricted pulmonary functions and clinical suspicion of ILD were enrolled in the study. MDCT evaluation was done using Siemens Somatom Force 384 slice multidetector computer tomography machine. Pattern analysis for reticular opacities, nodules and lung opacities was done to reach at a diagnosis. Final diagnosis was based on correlation of radiological and clinicopathological findings. Diagnostic efficacy of MDCT was evaluated in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detection of ILD.

Results

Mean age of patients was 58 ± 8.75 years. Majority were females (51.3%). History of chronic obstructive pulmonary disease (COPD), tuberculosis and bronchial asthma was revealed in 31 (38.8%), 26 (32.5%) and 16 (20%) patients, respectively. There were 30 (37.5%) patients having no history of respiratory diseases. MDCT diagnosed ILD in 45 (56.3%) cases. On final diagnosis, ILD was diagnosed in 35 (43.8%) cases (15 usual interstitial pneumonia [UIP], 9 cryptogenic organizing pneumonia [COP], 8 nonspecific interstitial pneumonia [NSIP] and 3 respiratory bronchiolitis associated interstitial lung disease [RBILD]). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of MDCT in detection of ILD was 91.4%, 71.1%, 71.1%, 91.4% and 80%, respectively.

Conclusion

MDCT as a single modality had a high sensitivity for detection of ILD and could be recommended as first line diagnostic imaging technique.

Efficacy of recombinant human soluble thrombomodulin for acute exacerbation of idiopathic pulmonary fibrosis: A systematic review and meta-analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing lung disease of unknown etiology. Recombinant human soluble thrombomodulin (rhTM) is used for the management of acute exacerbation (AE) of IPF. The present review aimed to summarize the evidence and perform a meta-analysis of the efficacy and safety of rhTM in the management of AE-IPF. An electronic search of titles and abstracts published until 31st August 2019 was performed in the PubMed, Biomed Central, Scopus and Embase databases. Studies comparing rhTM-treated and control subjects with AE-IPF and assessing mortality and adverse events were included. Six studies met the inclusion criteria. A total of 145 patients received rhTM, while 146 patients served as controls. The meta-analysis indicated that rhTM resulted in a reduction in 28-day [odds ratio (OR), 0.25; 95% CI, 0.08-0.77; P=0.02; I²=0%] and 90-day mortality (OR, 0.29; 95% CI, 0.17-0.49; P<0.00001; I²=0%) compared with the controls. Adverse events were pooled and no difference was determined between rhTM and control groups (OR, 1.07; 95% CI, 0.45-2.51; P=0.88; I²=0%). It was indicated that administration of rhTM may reduce the short-term mortality in patients with AE-IPF; however, the quality of evidence was not high. The drug appears to be safe without any enhanced risk of adverse events, although high-quality randomized controlled trials with a large sample size are required to further support its use in the treatment of IPF.

Transcriptional regulatory model of fibrosis progression in the human lung

To develop a systems biology model of fibrosis progression within the human lung we performed RNA sequencing and microRNA analysis on 95 samples obtained from 10 idiopathic pulmonary fibrosis (IPF) and 6 control lungs. Extent of fibrosis in each sample was assessed by microCT-measured alveolar surface density (ASD) and confirmed by histology. Regulatory gene expression networks were identified using linear mixed-effect models and dynamic regulatory events miner (DREM). Differential gene expression analysis identified a core set of genes increased or decreased before fibrosis was histologically evident that continued to change with advanced fibrosis. DREM generated a systems biology model (www.sb.cs.cmu.edu/IPFReg) that identified progressively divergent gene expression tracks with microRNAs and transcription factors that specifically regulate mild or advanced fibrosis. We confirmed model predictions by demonstrating that expression of POU2AF1, previously unassociated with lung fibrosis but proposed by the model as regulator, is increased in B lymphocytes in IPF lungs and that POU2AF1-knockout mice were protected from bleomycin-induced lung fibrosis. Our results reveal distinct regulation of gene expression changes in IPF tissue that remained structurally normal compared with moderate or advanced fibrosis and suggest distinct regulatory mechanisms for each stage.

What's in a name? That which we call IPF, by any other name would act the same

Idiopathic pulmonary fibrosis (IPF) remains a truly idiopathic fibrotic disease, with a modest genetic predilection and candidate triggers but no overall explanation for the development of disease in non-familial cases. Agreement on terminology has contributed to major clinical and translational advances since the millennium. It is likely that the entity currently captured by the term “IPF” will be radically reclassified over the next decade, either through “splitting” (into IPF subgroups responding selectively to individual disease-modifying agents) or through “lumping” of IPF with other forms of progressive fibrotic lung disease (with shared pathogenetic mechanisms and IPF-like disease behaviour). In this perspective, we summarise the clinical and pathogenetic justification for a focus on “the progressive fibrotic phenotype” in future clinical and translational research. By this means, we can hope to address the needs of non-IPF patients with inexorably progressive fibrotic disease, currently disenfranchised by lack of access to agents that are efficacious in IPF. In this regard, ongoing trials of anti-fibrotic therapies in non-IPF patients with progressive fibrosis may be highly influential. Future revision of IPF nomenclature may be warranted if there are major conceptual changes but without compelling justification, the benefits of renaming IPF are likely to be outweighed by the resulting confusion.

The Efficacy and Mechanism Evaluation of Treating Idiopathic Pulmonary fibrosis with the Addition of Co-trimoxazole (EME-TIPAC): study protocol for a randomised controlled trial

BACKGROUND

We hypothesise, based upon the findings from our previous trial, that the addition of co-trimoxazole to standard therapy is beneficial to patients with moderate to severe idiopathic pulmonary fibrosis (IPF). We aim to investigate this by assessing unplanned hospitalisation-free survival (defined as time from randomisation to first non-elective hospitalisation, lung transplant or death) and to determine whether any effect relates to changes in infection and/or markers of disease control and neutrophil activity.

METHODS/DESIGN

The EME-TIPAC trial is a double-blind, placebo-controlled, randomised, multicentre clinical trial. A total of 330 symptomatic patients, aged 40 years old or older, with IPF diagnosed by a multidisciplinary team (MDT) according to international guidelines and a FVC ≤ 75% predicted will be enrolled. Patients are randomised equally to receive either two tablets of co-trimoxazole 480 mg or two placebo tablets twice daily over a median treatment period of 27 (range 12-42) months. All patients receive folic acid 5 mg daily whilst on the trial IMP to reduce the risk of bone marrow depression. The primary outcome for the trial is a composite endpoint consisting of the time to death, transplant or first non-elective hospital admission and will be determined from adverse event reporting, hospital databases and the Office of National Statistics with active tracing of patients missing appointments. Secondary outcomes include the individual components of the primary outcome, (1) King's Brief Interstitial Lung Disease Questionnaire, (2) MRC Dyspnoea Score, (3) EQ5D, (4) spirometry, (5) total lung-diffusing capacity and (6) routine sputum microbiology. Blood will be taken for cell count, biochemistry and analysis of biomarkers including C-reactive protein and markers of disease. The trial will last for 4 years. Recruitment will take place in a network of approximately 40 sites throughout the UK (see Table 1 for a full list of participating sites). We expect recruitment for 30 months, follow-up for 12 months and trial analysis and reporting to take 4 months.

DISCUSSION

The trial is designed to test the hypothesis that treating IPF patients with co-trimoxazole will increase the time to death (all causes), lung transplant or first non-elective hospital admission compared to standard care ( https://www.nice.org.uk/guidance/cg163 ), in patients with moderate to severe disease. The mechanistic aims are to investigate the effect on lung microbiota and other measures of infection, markers of epithelial injury and markers of neutrophil activity.

TRIAL REGISTRATION

International Standard Randomised Controlled Trials Number (ISRCTN) Registry, ID: 17464641 . Registered on 29 January 2015.

Arterial Carboxyhemoglobin Measurement Is Useful for Evaluating Pulmonary Inflammation in Subjects with Interstitial Lung Disease

Objective The arterial concentration of carboxyhemoglobin (CO-Hb) in subjects with inflammatory pulmonary disease is higher than that in healthy individuals. We retrospectively analyzed the relationship between the CO-Hb concentration and established markers of disease severity in subjects with interstitial lung disease (ILD). Methods The CO-Hb concentration was measured in subjects with newly diagnosed or untreated ILD and the relationships between the CO-Hb concentration and the serum biomarker levels, lung function, high-resolution CT (HRCT) findings, and the uptake in gallium-67 (⁶⁷Ga) scintigraphy were evaluated. Results Eighty-one non-smoking subjects were studied (mean age, 67 years). Among these subjects, (A) 17 had stable idiopathic pulmonary fibrosis (IPF), (B) 9 had an acute exacerbation of IPF, (C) 44 had stable non-IPF, and (D) 11 had an exacerbation of non-IPF. The CO-Hb concentrations of these subjects were (A) 1.5±0.5%, (B) 2.1±0.5%, (C) 1.2±0.4%, and (D) 1.7±0.5%. The CO-Hb concentration was positively correlated with the serum levels of surfactant protein (SP)-A (r=0.38), SP-D (r=0.39), and the inflammation index (calculated from HRCT; r=0.57) and was negatively correlated with the partial pressure of oxygen in the arterial blood (r=-0.56) and the predicted diffusion capacity of carbon monoxide (r=-0.61). The CO-Hb concentrations in subjects with a negative heart sign on ⁶⁷Ga scintigraphy were higher than those in subjects without a negative heart sign (1.4±0.5% vs. 1.1±0.3%, p=0.018). Conclusion The CO-Hb levels of subjects with ILD were increased, particularly during an exacerbation, and were correlated with the parameters that reflect pulmonary inflammation.

Drug-Induced Lung Toxicity

The number of blood-borne chemotherapeutic agents implicated in drug-induced lung toxicity continues to increase, although problems in detection remain. The initiation of drug-induced lung injury can have an immunologic or nonimmunologic basis. If endothelial cells are injured, interstitial pulmonary edema may result. Regardless of the source of injury, the progression of drug-induced lung toxicity is often quite similar, involving (1) parenchymal damage, (2) recruitment of inflammatory cells, and (3) progression of the inflammatory process. If the inflammatory reponse is sufficiently severe and disperse, increased collagen can be deposited in interstitial and intra-alveolar areas. The resulting attenuation of gas exchange can induce dyspnea and possibly death. Recent research suggests mediation of the fibrogenic process via cytokines such as transforming growth factor-β and tumor necrosis factor. Preliminary results demonstrating amelioration of cytokine mediated lung-induced fibrosis in animal models with appropriate antibodies suggest a possible future modality of therapy. Certain amphiphilic drugs are capable of eliciting a more specific form of lung toxicity. This class of drugs can interfere with phospholipid metabolism in pulmonary macrophages. In these cases, phospholipidosis results from phospholipid accumulation. The physiologic sequelae in human phospholipidosis is still uncertain.

Pulmonary Sarcoidosis

Sarcoidosis is a systemic disease, with lung involvement in almost all cases. Abnormal chest radiography is usually a key step for considering diagnosis. Lung impact is investigated through imaging; pulmonary function; and, when required, 6-minute walk test, cardiopulmonary exercise testing, or right heart catheterization. There is usually a reduction of lung volumes, and forced vital capacity is the most accurate parameter to reflect the impact of pulmonary sarcoidosis with or without pulmonary infiltration at imaging. Various evolution patterns have been described. Increased risk of death is associated with advanced pulmonary fibrosis or cor pulmonale, particularly in African American patients.

Immune Inflammation and Disease Progression in Idiopathic Pulmonary Fibrosis

The clinical course in idiopathic pulmonary fibrosis (IPF) is highly heterogeneous, with some patients having a slow progression and others an accelerated clinical and functional decline. This study aims to clinically characterize the type of progression in IPF and to investigate the pathological basis that might account for the observed differences in disease behavior. Clinical and functional data were analyzed in 73 IPF patients, followed long-time as candidates for lung transplantation. The forced vital capacity (FVC) change/year (< or ≥10% predicted) was used to define “slow” or “rapid” disease progression. Pathological abnormalities were quantified in the explanted lung of 41 out of 73 patients undergoing lung transplantation. At diagnosis, slow progressors (n = 48) showed longer duration of symptoms and lower FVC than rapid progressors (n = 25). Eleven slow and 3 rapid progressors developed an acute exacerbation (AE) during follow-up. Quantitative lung pathology showed a severe innate and adaptive inflammatory infiltrate in rapid progressors, markedly increased compared to slow progressors and similar to that observed in patients experiencing AE. The extent of inflammation was correlated with the yearly FVC decline (r = 0.52, p = 0.005). In conclusion an innate and adaptive inflammation appears to be a prominent feature in the lung of patients with IPF and could contribute to determining of the rate of disease progression.

The pathologist's view of silicosis in 1930 and in 2015. The Johannesburg Conference legacy

The 1930 International Labour Office Conference on silicosis in Johannesburg was a turning point in the history of silicosis and in the recognition of the associated pathologic patterns. Since 1930, pneumoconioses such as silicosis have become much rarer in developed countries and can now be diagnosed at an early stage based on clinical and radiologic criteria. However, in spite of these advances, pathologists must remember to look for silica in tissues, particularly when clinical and radiologic findings are more uncertain. Furthermore, nowadays pathologists essentially observe silicotic lesions as incidental findings adjacent to lung cancers. In addition to identifying the characteristic lesions, pathologists must also try to identify their causative agent, in the case of crystalline silica firstly by using polarized light examination, followed as appropriate by more sophisticated devices. Finally, pathologists and clinicians must always keep in mind the various implications of exposure to silica compounds in a wide range of diseases.

Amelioration of bleomycin-induced pulmonary fibrosis in a mouse model by a combination therapy of bosentan and imatinib

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) is characterized by alveolitis, progressing into fibrosis. Due to the involvement of both endothelin and platelet-derived growth factor signaling in IPF, combination effects of a bosentan and imatinib were studied in mouse model of bleomycin-induced pulmonary fibrosis.

METHODS

Mice subjected to bleomycin instillation (0.05 U) and were administered with either bosentan (100 mg/kg) and/or imatinib (50 mg/kg). Inflammatory cell count, total protein estimation in bronchoalveolar lavage fluid, lung edema, superoxide dismutase, catalase, myeloperoxidase activities, and Hematoxylin & Eosin staining were performed on day 7. Hydroxyproline content, α-smooth muscle actin (SMA), collagens I and III gene expression analysis, immunohistochemistry, matrix metalloproteinases-9 and -2 activities, trichrome and sirius red staining were performed on day 21.

RESULTS

Combination treatment with bosentan and imatinib prevented bleomycin-induced mortality and loss of body weight more than the individual agents. On day 7, the combination therapy attenuated bleomycin-induced increase of total and differential inflammatory cell counts, total proteins, lung wet/dry weight ratio, myeloperoxidase activity, lung inflammatory cell infiltration more than individual agents alone. Bosentan but not imatinib ameliorated superoxide dismutase and catalase activities, which were lowered following bleomycin instillation. On day 21, combination therapy ameliorated bleomycin-induced increase of fibrosis score, collagen deposition, protein and gene expression of SMA, mRNA levels of collagens-I and -III, matrix metalloproteinase-9 and -2 activities more than monotherapy.

CONCLUSION

Combination of bosentan and imatinib exerted more enhanced protection against bleomycin-induced inflammation and fibrosis than either of the agents alone.

HFE gene variants and iron-induced oxygen radical generation in idiopathic pulmonary fibrosis

In idiopathic pulmonary fibrosis (IPF), lung accumulation of excessive extracellular iron and macrophage haemosiderin may suggest disordered iron homeostasis leading to recurring microscopic injury and fibrosing damage. The current study population comprised 89 consistent IPF patients and 107 controls. 54 patients and 11 controls underwent bronchoalveolar lavage (BAL). Haemosiderin was assessed by Perls' stain, BAL fluid malondialdehyde (MDA) by high-performance liquid chromatography, BAL cell iron-dependent oxygen radical generation by fluorimetry and the frequency of hereditary haemochromatosis HFE gene variants by reverse dot blot hybridisation. Macrophage haemosiderin, BAL fluid MDA and BAL cell unstimulated iron-dependent oxygen radical generation were all significantly increased above controls (p<0.05). The frequency of C282Y, S65C and H63D HFE allelic variants was markedly higher in IPF compared with controls (40.4% versus 22.4%, OR 2.35, p=0.008) and was associated with higher iron-dependent oxygen radical generation (HFE variant 107.4±56.0, HFE wild type (wt) 59.4±36.4 and controls 16.7±11.8 fluorescence units per 10(5) BAL cells; p=0.028 HFE variant versus HFE wt, p=0.006 HFE wt versus controls). The data suggest iron dysregulation associated with HFE allelic variants may play an important role in increasing susceptibility to environmental exposures, leading to recurring injury and fibrosis in IPF.

Passion fruit peel extract attenuates bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis is a progressive fatal lung disease characterized by excessive collagen deposition, with no effective treatments. We investigated the efficacy of natural products with high anti-inflammatory activity, such as passion fruit peel extract (PFPE), in a mouse model of bleomycin-induced pulmonary fibrosis (PF). C57BL/6J mice were subjected to a single intratracheal instillation of bleomycin to induce PF. Daily PFPE treatment significantly reduced loss of body mass and mortality rate in mice compared with those treated with bleomycin. While bleomycin-induced PF resulted in elevated total numbers of inflammatory cells, macrophages, lymphocytes, and neutrophils in bronchoalveolar lavage fluid on both days 7 and 21, PFPE administration significantly attenuated these phenomena compared with bleomycin group. On day 7, the decreased superoxide dismutase and myeloperoxidase activities observed in the bleomycin group were significantly restored with PFPE treatment. On day 21, enhanced hydroxyproline deposition in the bleomycin group was also suppressed by PFPE administration. PFPE treatment significantly attenuated extensive inflammatory cell infiltration and accumulation of collagen in lung tissue sections of bleomycin-induced mice on days 7 and 21, respectively. Our results indicate that administration of PFPE decreased bleomycin-induced PF because of anti-inflammatory and antioxidant activities.

Factors limiting exercise tolerance in chronic lung diseases

The major limitation to exercise performance in patients with chronic lung diseases is an issue of great importance since identifying the factors that prevent these patients from carrying out activities of daily living provides an important perspective for the choice of the appropriate therapeutic strategy. The factors that limit exercise capacity may be different in patients with different disease entities (i.e., chronic obstructive, restrictive or pulmonary vascular lung disease) or disease severity and ultimately depend on the degree of malfunction or miss coordination between the different physiological systems (i.e., respiratory, cardiovascular and peripheral muscles). This review focuses on patients with chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD) and pulmonary vascular disease (PVD). ILD and PVD are included because there is sufficient experimental evidence for the factors that limit exercise capacity and because these disorders are representative of restrictive and pulmonary vascular disorders, respectively. A great deal of emphasis is given, however, to causes of exercise intolerance in COPD mainly because of the plethora of research findings that have been published in this area and also because exercise intolerance in COPD has been used as a model for understanding the interactions of different pathophysiologic mechanisms in exercise limitation. As exercise intolerance in COPD is recognized as being multifactorial, the impacts of the following factors on patients' exercise capacity are explored from an integrative physiological perspective: (i) imbalance between the ventilatory capacity and requirement; (ii) imbalance between energy demands and supplies to working respiratory and peripheral muscles; and (iii) peripheral muscle intrinsic dysfunction/weakness.

Type V collagen induced tolerance suppresses collagen deposition, TGF-β and associated transcripts in pulmonary fibrosis

RATIONALE

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by progressive scarring and matrix deposition. Recent reports highlight an autoimmune component in IPF pathogenesis. We have reported anti-col(V) immunity in IPF patients. The objective of our study was to determine the specificity of col(V) expression profile and anti-col(V) immunity relative to col(I) in clinical IPF and the efficacy of nebulized col(V) in pre-clinical IPF models.

METHODS

Col(V) and col(I) expression profile was analyzed in normal human and IPF tissues. C57-BL6 mice were intratracheally instilled with bleomycin (0.025 U) followed by col(V) nebulization at pre-/post-fibrotic stage and analyzed for systemic and local responses.

RESULTS

Compared to normal lungs, IPF lungs had higher protein and transcript expression of the alpha 1 chain of col(V) and col(I). Systemic anti-col(V) antibody concentrations, but not of anti-col(I), were higher in IPF patients. Nebulized col(V), but not col(I), prevented bleomycin-induced fibrosis, collagen deposition, and myofibroblast differentiation. Col(V) treatment suppressed systemic levels of anti-col(V) antibodies, IL-6 and TNF-α; and local Il-17a transcripts. Compared to controls, nebulized col(V)-induced tolerance abrogated antigen-specific proliferation in mediastinal lymphocytes and production of IL-17A, IL-6, TNF-α and IFN-γ. In a clinically relevant established fibrosis model, nebulized col(V) decreased collagen deposition. mRNA array revealed downregulation of genes specific to fibrosis (Tgf-β, Il-1β, Pdgfb), matrix (Acta2, Col1a2, Col3a1, Lox, Itgb1/6, Itga2/3) and members of the TGF-β superfamily (Tgfbr1/2, Smad2/3, Ltbp1, Serpine1, Nfkb/Sp1/Cebpb).

CONCLUSIONS

Anti-col(V) immunity is pathogenic in IPF, and col(V)-induced tolerance abrogates bleomycin-induced fibrogenesis and down regulates TGF- β-related signaling pathways.

Proliferative phenotype of pulmonary microvascular endothelial cells plays a critical role in the overexpression of CTGF in the bleomycin-injured rat

The pathogenesis of idiopathic pulmonary fibrosis (IPF) is not very clear, with evidence for the involvement of both inflammation and aberrant vascular remodeling (associated with angiogenesis). Pulmonary microvascular endothelial cells (PMVECs), which play a major role in inflammation, secrete cytokines that promote the transformation and collagen synthesis of fibroblasts. Moreover, angiogenesis is characterized by PMVEC proliferation. The main aim of this study was to confirm the role of PMVECs in pulmonary fibrosis. Accordingly, we observed the functional changes in PMVECs in bleomycin (BLM)-treated rats (pulmonary fibrosis model) in vivo, and compared them with those of rats with pneumonia. The proliferation phenotype and intracellular ionized calcium concentration ([Ca(2+)]i) of PMVECs from BLM-treated rats were also investigated. The functioning of PMVECs was abnormal in BLM-injured rats, particularly with regard to their proliferation and secretion of connective tissue growth factor (CTGF). [Ca(2+)]i was increased in the proliferated PMVECs from BLM-treated rats. The findings suggest that dysfunction of PMVECs characterized by overexpression of CTGF is critical in rat pulmonary injury induced by BLM, and is probably related with the proliferative phenotype and [Ca(2+)]i overload. It can be concluded from the results that proliferation of PMVECs plays an important role in the pathogenesis of BLM-induced PF.

Idiopathic pulmonary fibrosis: diagnosis and epidemiology

In 2000, the American Thoracic Society and European Respiratory Society published the first consensus statement providing guidelines on the diagnosis and treatment of idiopathic pulmonary fibrosis (IPF). This statement presented, for the first time, diagnostic criteria for IPF and recommendations for treatment. Results from several studies have reshaped the thinking on IPF, and as a result, the guidelines have been recently revised using an evidence-based approach. Meanwhile, several epidemiologic studies have yielded data that identify potential risk factors and that better define the societal burden of IPF. This article summarizes the approach to diagnosing IPF and reviews epidemiologic data on IPF.

Deficiency of tumour necrosis factor-related apoptosis-inducing ligand exacerbates lung injury and fibrosis

BACKGROUND

The death receptor ligand tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) shows considerable clinical promise as a therapeutic agent. TRAIL induces leukocyte apoptosis, reducing acute inflammatory responses in the lung. It is not known whether TRAIL modifies chronic lung injury or whether TRAIL has a role in human idiopathic pulmonary fibrosis (IPF). We therefore explored the capacity of TRAIL to modify chronic inflammatory lung injury and studied TRAIL expression in patients with IPF.

METHODS

TRAIL(-/-) and wild-type mice were instilled with bleomycin and inflammation assessed at various time points by bronchoalveolar lavage and histology. Collagen deposition was measured by tissue hydroxyproline content. TRAIL expression in human IPF lung samples was assessed by immunohistochemistry and peripheral blood TRAIL measured by ELISA.

RESULTS

TRAIL(-/-) mice had an exaggerated delayed inflammatory response to bleomycin, with increased neutrophil numbers (mean 3.19±0.8 wild type vs 11.5±5.4×10(4) TRAIL(-/-), p<0.0001), reduced neutrophil apoptosis (5.42±1.6% wild type vs 2.47±0.5% TRAIL(-/-), p=0.0003) and increased collagen (3.45±0.2 wild type vs 5.8±1.3 mg TRAIL(-/-), p=0.005). Immunohistochemical analysis showed induction of TRAIL in bleomycin-treated wild-type mice. Patients with IPF demonstrated lower levels of TRAIL expression than in control lung biopsies and their serum levels of TRAIL were significantly lower compared with matched controls (38.1±9.6 controls vs 32.3±7.2 pg/ml patients with IPF, p=0.002).

CONCLUSION

These data suggest TRAIL may exert beneficial, anti-inflammatory actions in chronic pulmonary inflammation in murine models and that these mechanisms may be compromised in human IPF.

Bronchoalveolar lavage and other methods to define the human respiratory tract milieu in health and disease

During fiber-optic bronchoscopy (FOB), surface sampling of the human respiratory airways and alveolar unit can be done with bronchoalveolar lavage (BAL), plus selective sites can be brushed for cells and transbronchial biopsies made in adjacent tissue. This permits analysis of the respiratory tract's milieu in healthy normals, in those with disease, and in control subjects. These combined procedures have been an established approach for obtaining specimens for research and for clinical assessment for over four decades. However, now new less invasive sampling methods are emerging. This review emphasizes BAL and the cellular and noncellular components recovered in fluid that have contributed to improving knowledge of how the respiratory tree's innate immunity can protect, and how airway structures can become deranged and manifest disease. After a discussion of training for FOB and procedural issues, a spectrum of respiratory diseases studied with BAL is presented, including airway illness (asthma and chronic obstructive pulmonary disease), diffuse interstitial lung diseases [idiopathic pulmonary fibrosis, rheumatoid interstitial lung disease (ILD), granulomatous ILDs], lung infections, lung malignancy, and upper and lower tract airway problems. Some recent studies with exhaled breath condensate analyses are given.

Pulmonary fibrosis: pathogenesis, etiology and regulation

Pulmonary fibrosis and architectural remodeling of tissues can severely disrupt lung function, often with fatal consequences. The etiology of pulmonary fibrotic diseases is varied, with an array of triggers including allergens, chemicals, radiation and environmental particles. However, the cause of one of the most common pulmonary fibrotic conditions, idiopathic pulmonary fibrosis (IPF), is still unclear. This review examines common mechanisms of pulmonary wound-healing responses following lung injury, and highlights the pathogenesis of some of the most widespread pulmonary fibrotic diseases. A three phase model of wound repair is reviewed that includes; (1) injury; (2) inflammation; and (3) repair. In most pulmonary fibrotic conditions dysregulation at one or more of these phases has been reported. Chronic inflammation can lead to an imbalance in the production of chemokines, cytokines, growth factors, and disrupt cellular recruitment. These changes coupled with excessive pro-fibrotic IL-13 and/or TGFbeta1 production can turn a well-controlled healing response into a pathogenic fibrotic response. Endogenous regulatory mechanisms are discussed including novel areas of therapeutic intervention. Restoring homeostasis to these dysregulated healing responses, or simply neutralizing the key pro-fibrotic mediators may prevent or slow the progression of pulmonary fibrosis.

New perspectives in the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most frequent idiopathic interstitial pneumonia with a prevalence ranging from 5 to 15 per 100,000 persons, and above 175 per 100,000 in the older population. IPF is a relentlessly progressive fibrotic lung disorder leading to death within a median duration of 3 years. It was hypothesized in the 1970s that pulmonary fibrosis initiates as an "alveolitis" progressing to interstitial fibrosis with connective tissue deposition, derangement of the lung architecture and functional impairment. However, in vitro studies indicated that alveolar/bronchiolar injured epithelial cells can drive the fibrotic process in the absence of macrophages and with minimal inflammation. This, together with the inability of classic immunosuppressive therapy to cure IPF, generated new pathogenesis paradigms and intense research into the role of the lack or the excessive production of anti-fibrotic or profibrotic mediators, oxidant injury, exaggerated coagulation, thus leading to investigate new treatment strategies. Preliminary results of some of such trials have shown significant reductions in lung function decline, disease exacerbation and mortality.

Smoking-related interstitial lung disease

Pulmonary diseases associated with tobacco smoking are a complex group of disorders ranging from chronic obstructive pulmonary disease (COPD) to lung cancer. Interstitial lung diseases (ILDs) have only recently been linked to smoking. The ILDs related to smoking include respiratory bronchiolitis-associated interstitial lung disease, desquamative interstitial pneumonia, and pulmonary Langerhans cell histiocytosis. The relationship of smoking with each of these entities has been largely established on the weight of epidemiologic evidence. Although they have been retained as distinct and separate conditions in various classifications of interstitial lung diseases, these 3 entities share a number of clinical, radiologic, and pathologic features suggesting that they represent a spectrum of patterns of interstitial lung disease occurring in predisposed individuals who smoke. Evaluation of histologic features, particularly in surgical lung biopsy samples, is important in making the distinction between these disorders. However, even after tissue biopsy, it may sometimes be difficult to clearly separate these entities. The importance of making the distinction between them lies in the different clinical management strategies used. Further experimental evidence, including genetic information, may be important in improving our understanding of these diseases.

Morphological and molecular markers in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis is a progressive, lethal, interstitial lung disease with no proven effective therapy other than lung transplantation. A definitive diagnosis of the disease requires surgical lung biopsy to show a histological appearance of usual interstitial pneumonia. The main histological features include temporal and spatial heterogeneity, fibroblastic foci, extracellular matrix deposition with vessel remodeling and honeycomb changes. There are some morphological aspects that have recently been taken into account as possible prognostic markers for disease progression. Although the cellular and molecular pathways driving disease pathogenesis are complex and not fully delineated, increasing evidence suggests that a key event is ongoing alveolar epithelial injury in association with an abnormal host repair response. Inflammation seems to play a less important role and remains largely debated while increased attention has been on the role of noninflammatory structural cells, such as fibroblasts, epithelial cells and endothelial cells. The modifications and interactions among these cells are complex and regulated by various molecular factors. This article reviews the morphology of the disease, focusing on some new facets and on the principal molecular factors involved in the different aspects of parenchymal remodeling.

Attenuation of bleomycin-induced lung injury and oxidative stress by N-acetylcysteine plus deferoxamine

Reactive oxygen species (ROS) play an important role in the pathogenesis of pulmonary injury and antioxidant therapy may be useful with impaired oxidative defense mechanism. This study examines the effect of N-acetylcysteine (NAC) and deferoxamine (DFX) on inflammatory indicators and oxidative stress in the lungs of mice exposed to bleomycin (BLM). The animals received endotracheally a single dose of BLM (2.5 U/kg body weight dissolved in 0.25 ml of 0.9% NaCl) or saline (0.9% NaCl) and were divided into eight groups (n=8): saline; BLM; saline+NAC; BLM+NAC; saline+DFX; BLM+DFX; saline+NAC+DFX; BLM+NAC+DFX. Treatments with NAC (20mg/kg) or DFX (30 mg/kg) were administered for 60 days after BLM exposure. Lactate dehydrogenase (LDH) activity and total cell count, neutrophil and protein concentration were determined in the bronchoalveolar lavage fluid (BALF). Lipid peroxidation thiobarbituric acid-reactive species (TBARS), oxidative protein damage (carbonyl contents), and catalase and superoxide dismutase activities were determined in the lung tissue. BLM administration resulted in lung lesion as determinated lung histology, which is almost completely prevented by NAC plus DFX. The results of total cell counts and neutrophils and LDH increased after BLM exposure and were reduced with NAC. DFX and NAC plus DFX also caused a significant decrease of LDH activity. The increased malondialdehyde equivalents and carbonyl contents in lung tissue produced by BLM were also prevented by NAC plus DFX. However, the isolated use of NAC increased lipid peroxidation. SOD activity increased after BLM exposure only in the group treated with DFX and catalase activity not was altered in the presence of BLM. Data presented here indicates that the isolated use of NAC had limited effects on BLM-induced pulmonary oxidative stress in mice. The use of DFX improves the defense response and in association with NAC may be a good alternative in the treatment or prevention of diseases that have ROS and iron involved in their pathogenesis.

The role of TGF-beta in pulmonary fibrosis

Pulmonary fibrosis is an irreversible accumulation of connective tissue in the interstitium of the lung. The pathogenesis of pulmonary fibrosis is not well understood. Research on animal models and studies of human lung disease suggest the initiating events may be a combination of pulmonary injury and the recruitment of inflammatory cells, mainly macrophages. A number of well characterized cytokines, including TGF-beta, have been either found in the injured lung or produced by inflammatory cells removed from the lung. In an animal model of pulmonary fibrosis, TGF-beta production is increased prior to collagen synthesis and is mainly produced by alveolar macrophages. In advanced idiopathic pulmonary fibrosis, a human fibrotic lung disease, extensive TGF-beta deposition can be detected by immunohistochemical staining, primarily in epithelial cells in areas of lung regeneration and remodelling. This suggests that the pathogenesis of the progressive fibrosis characteristic of this lung disease may be an aberrant repair process.

Elevated levels of MCP-1, MIP-alpha and MIP-1 beta in the bronchoalveolar lavage (BAL) fluid of patients with mustard gas-induced pulmonary fibrosis

OBJECTIVE

Role of chemokines in the pathogenesis of pulmonary fibrosis (PF) due to sulfur mustard (SM) gas inhalation.

PATIENTS

18 veterans with SM gas-induced PF, 15 patients with IPF and 18 normal as controls.

INTERVENTION

Chest roentgenograms, PFTs, the percentage DLCO, high-resolution CT scans of the chest, and analyses of BAL fluids for chemokines (MCP-1, MIP-1 alpha, and MIP-1 beta) were performed in all cases.

RESULTS

There were significant differences in chemokines (MCP-1, MIP-1 alpha, and MIP-1 beta) levels of BAL fluid between patients with PF and healthy controls (p<0.0006). MCP-1 and MIP-1 alpha levels in BAL fluid correlate only with the percentage and the absolute number lymphocytes of the BAL fluid in patients with PF due to SM gas inhalation (p=0.0006/p=0.03; p=0.04/p=0.02; respectively). The BAL fluid level of MIP-alpha in SM gas-induced PF was significantly correlated with the number of lymphocytes (r=-0.56, p=0.01), neutrophils (r=-0.50, p=0.03) and eosinophils (r=-0.49, p=0.03). A significant negative correlation was observed between the percentage of Dlco and MCP-1 and MIP-1 alpha levels in BAL fluid in patients with PF (r=-0.65, p=0.003; r=-0.48, p=0.04; respectively).

CONCLUSION

Neutrophils alveolitis, presence of eosinophils, and higher concentrations of interleukin MCP-1, MIP-1 alpha, and MIP-1 beta in BAL fluid are associated with the development of fibrosis in SM victims.

Interstitial lung disease in infancy

OBJECTIVE

To describe the clinical profile of interstitial lung disease in infancy.

METHODS

A retrospective analysis of cases diagnosed to have ILD was carried out in Kanchi Kamakoti CHILDS Trust hospital over a period of 2 yr. Infants aged 1 month to 1 yr of age were included if they had (1) respiratory symptoms (Cough, tachypnea or crepitations) for at least 1 month (2) diffuse infiltrates on chest radiography (3) Hypoxemia as defined by oxygen saturation less than 90% by pulse oximetry and (4) High Resolution Computed Tomography (HRCT) of the chest revealing findings of interstitial infiltrates or ground glass pattern. Their case records were analyzed for clinical data, treatment and follow up details.

RESULTS

Of the 9 children, who were diagnosed to have ILD, 5 were boys and 4 were girls. The male: female ratio was 1.25: 1. The median age of onset of symptoms was 5 month. The common clinical features observed were tachypnea associated with chest indrawing (100%), cough (100%), hypoxia (100%), failure to thrive and fever (55%) each. The following radiographic patterns were observed in the chest skiagrams: reticulo-nodular pattern in 6(67%) and ground glass pattern in 3(33%). HRCT showed interstitial infiltrates in 6 (67%) and ground glass pattern in 3(33%). Evidence for cyto megalo virus (CMV) infection was detected in 5(56%), Adenovirus in 1 (11%) and Pneumocystis carinii (PCP) in 1(11%) infant. Open lung biopsy was performed in 2 infants, which detected CMV in 1 and PCP in the other. All children received oxygen therapy and systemic corticosteroids (oral/IV) in addition to specific therapy for infection and 3 of these infants succumbed to respiratory failure.

CONCLUSION

CMV Infection was the commonest cause of ILD in infancy in our study. However, the consequences on long term follow up in these infants need to be ascertained.

A Clinicianʼs Guide to the Diagnosis and Treatment of Interstitial Lung Diseases

Interstitial lung disease (ILD) is a final common pathway for a large number of lung insults. It is characterized by progressive scarring of the lung leading to restriction and diminished oxygen transfer. Clinically, the presenting symptoms of ILD are nonspecific (cough and progressive dyspnea on exertion) and are often attributed to other diseases, thus delaying diagnosis and timely therapy. ILD occurs most commonly in older individuals and is increasingly encountered by internists. Both the diagnosis and treatment can be daunting: patients frequently have irreversibly impaired lung function at diagnosis, and therapeutic modalities are limited and associated with significant adverse effects. This review will assist internists in the recognition and management of ILD, provide a benchmark for pulmonary referrals, and offer guidance in advising patients with this life-threatening disorder.