A role for cardiopulmonary exercise testing in detecting physiological changes underlying health status in Idiopathic pulmonary fibrosis: a feasibility study.

INTRODUCTION: There is limited data available on the use of CPET as a predictive tool for disease outcomes in the setting of IPF. We investigated the feasibility of undertaking CPET and the relationship between CPET and quality of life measurements in a well-defined population of mild and moderate IPF patients. METHODS: A prospective, single-centre observational study. RESULTS: Thirty-two IPF patients (mild n = 23, moderate n = 9) participated in the study, n = 13 mild patients attended for repeat CPET testing at 12 months. At baseline, total K-BILD scores and total IPF-PROM scores significantly correlated with 6MWT distance, but not with baseline FVC % predicted, TLco % predicted, baseline or minimum SpO2. VO2 peak/kg at AT positively correlated with total scores, breathlessness/activity and chest domains of the K-BILD questionnaire (p < 0.05). VO2 peak significantly correlated with total IPF PROM scores and wellbeing domains (p < 0.05), with a trend towards statistical significance for total IPF-PROM and VO2 peak/kg at anaerobic threshold (p = 0.06). There was a statistically significant reduction in FVC% predicted at 12 months follow up, although the mean absolute decline was < 10% (p < 0.05). During this period VO2 peak significantly reduced (21.6 ml/kg/min ± 2.9 vs 19.1 ± 2.8; p = 0.017), with corresponding reductions in total K-BILD and breathlessness/activity domains that exceeded the MCID for responsiveness. Lower baseline VO2 peak/kg at anaerobic threshold correlated with greater declines in total K-BILD scores (r = - 0.62, 0.024) at 12 months. Whilst baseline FVC% predicted or TLco % predicted did not predict change in health status, CONCLUSION: We have shown that it is feasible to undertake CPET in patients with mild to moderate IPF. CPET measures of VO2 peak correlated with both baseline and change in K-BILD measurements at 1 year, despite relatively stable standard lung function (declines of < 10% in FVC), suggesting its potential sensitivity to detect physiological changes underlying health status.

Duration of benefit following completion of pulmonary rehabilitation in interstitial lung disease-an observational study.

BACKGROUND: It remains unclear for how long the benefits of pulmonary rehabilitation (PR) last in interstitial lung disease (ILD). An increasing number of ILD patients complete PR and it is vital they be offered the most beneficial approaches. METHODS: This is a retrospective, observational study of a cohort with ILD who had completed PR. Incremental shuttle walk (ISWT) and chronic respiratory disease questionnaire (CRDQ) were compared before PR, at course completion, and 6/12 months follow-up. Focus group discussions with ILD participants who had completed PR and their carers established qualitative views on existing and potential future PR provision. RESULTS: 79 participants with ILD were identified at course completion, with 39 followed to 12 months. 11 participants died during follow-up. Initial benefits from PR were not sustained at 6 months (ISWT change 0.0m (95% CI-23.2 to 23.2 m), CRDQ change 2.5 (95% CI-2.4 to 7.4)) and 12 months (ISWT change-0.7 m (95% CI-37.3 to 35.9 m), CRDQ change 4.0 (95% CI-2.2 to 10.2)). Continued home exercise gave longer lasting benefit in exercise capacity. Focus group discussions highlighted the value attached to PR and suggested areas for improvement. CONCLUSIONS: Standard PR gives initial benefits in participants with ILD who complete the course, however these are not sustained. Tailored approaches to this group would be appreciated by this group and should be explored.

Lung function in pulmonary hypertension.

Breathlessness is a common symptom in pulmonary hypertension (PH) and an important cause of morbidity. Though this has been attributed to the well described pulmonary vascular abnormalities and subsequent cardiac remodelling, changes in the airways of these patients have also been reported and may contribute to symptoms. Our understanding of these airway abnormalities is poor with conflicting findings in many studies. The present review evaluates these studies for the major PH groups. In addition we describe the role of cardiopulmonary exercise testing in the assessment of pulmonary arterial hypertension (PAH) by evaluating cardiopulmonary interaction during exercise. As yet, the reasons for the abnormalities in lung function are unclear, but potential causes and the possible role of inflammation are discussed. Future research is required to provide a better understanding of this to help improve the management of these patients.

The role of biologics in treatment of connective tissue disease-associated interstitial lung disease.

With an increased understanding of the molecular pathways of inflammation and autoimmunity, the development of targeted biological agents has revolutionized the management of connective tissue diseases (CTDs). There has been an explosion in the development of these drugs in the last decade, targeting diseases in diverse fields including: allergic disorders, oncology, neuroinflammatory disorders, inflammatory bowel disease, macular degeneration and CTDs. In this last field, commonly applied biologics fall into two categories: cytokine inhibitors and lymphocyte-targeted therapies. The former group includes the antitumour necrosis factor alpha (TNF-α), anti-interleukin (IL)-6 receptor monoclonal antibodies and IL-1 receptor antagonists, whilst the latter encompasses the anti-CD20, B-cell depleting, monoclonal antibody (mAb), Rituximab and the anti-T-cell activation agent, Abatacept. This review will examine our developing experience in the use of these agents in the treatment of CTD-related interstitial lung diseases, with a particular focus on B-cell depletion.

Vascular endothelial growth factor in acute lung injury and acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is the most severe form of lung injury, characterised by alveolar oedema and vascular permeability, in part due to disruption of the alveolar capillary membrane integrity. Vascular endothelial growth factor (VEGF) was originally identified as a vascular permeability factor and has been implicated in the pathogenesis of acute lung injury/ARDS. This review describes our current knowledge of VEGF biology and summarises the literature investigating the potential role VEGF may play in normal lung maintenance and in the development of lung injury.

VEGF and sVEGFR-1 in malignant pleural effusions: association with survival and pleurodesis outcomes.

VEGF is a key mediator of tumour growth and metastasis and is considered central to the formation of exudative pleural effusions. This study examined the relationship between levels of VEGF and its soluble receptor, sVEGFR-1 in the pleural fluid and plasma of patients with malignant pleural effusions and their association with pleurodesis outcomes and survival. 103 patients with malignant pleural effusions were recruited at their first presentation. Follow-up was to 6 months or death. Survival and pleurodesis outcomes were robustly ascertained. VEGF and sVEGFR-1 were measured in pleural fluid and plasma by ELISA. VEGF and sVEGFR-1 were present in significantly higher concentrations in pleural fluid than plasma. There was no significant correlation between mediators within or between sample types. There was no association between baseline pleural fluid VEGF or sVEGFR-1 levels and pleurodesis failure. In both sample types, survival was inversely associated with sVEGFR-1 and within the non-small cell lung cancer sub-group (n=26), a highly significant association between increased pleural fluid VEGF and sVEGFR-1 and reduced survival was demonstrated (p=0.02 and 0.004 respectively). In conclusion, we have shown for the first time that sVEGFR-1 can be reproducibly measured in pleural fluid from malignant effusions. High levels at presentation in those with non-small cell carcinoma are strongly associated with poor outcomes.

Tumour necrosis factor-alpha processing in interstitial lung disease: a potential role for exogenous proteinase-3.

Tumour necrosis factor (TNF) blockade has become an important immunomodulatory therapy, particularly in patients refractory to conventional immunosuppression, but responses can be unpredictable. Understanding the complex biology of TNF processing may be key to predicting such responses and reduce unwanted side effects. TNF bioavailability is regulated partly by TNF-alpha converting enzyme (TACE) cleavage; however, it can also be cleaved by proteinase-3 (PR-3). We have demonstrated this mechanism previously in healthy human alveolar macrophages (AM), leading us to hypothesize that PR-3-mediated TNF processing may be an important mechanism in inflammatory lung disease. Furthermore, this may be more apparent in diseases with a neutrophil component typical of usual interstitial pneumonia (UIP), compared with sarcoidosis, where lymphocytes predominate. We isolated AM from patients with UIP and sarcoidosis and healthy subjects. We found increased TACE expression on AM in sarcoidosis. In contrast, TACE was not increased in UIP; we found increased cleavage of glutathione S-transferase-proTNF) substrate, relative to both sarcoidosis and healthy controls. Furthermore, cleavage was subject to inhibition by serine protease inhibitor, rather than a TACE inhibitor BB-3103. Cleavage was proportional to the number of neutrophils isolated from bronchoalveolar lavage, whereas there was an inverse relationship between neutrophils and BB-3103 inhibition. There was also increased PR-3 on the AM surface in UIP relative to healthy controls. These data provide evidence for PR-3-mediated cleavage in UIP, which may have implications for future therapeutic targeting of TACE.

Genetic variants of microsomal epoxide hydrolase and glutamate-cysteine ligase in COPD.

The genetic factors that contribute to the development of chronic obstructive pulmonary disease (COPD) are poorly understood. Many candidate genes have been proposed, including enzymes that protect the lung against oxidative stress, such as microsomal epoxide hydrolase (EPHX1) and glutamate-cysteine ligase (GCL). To date, most reported findings have been for EPHX1, particularly in relation to functional variants associated with fast and slow metabolism of epoxide intermediates. The present study aimed to identify any association of variation in these genes with COPD susceptibility or severity. In total, 1,017 white COPD patients and 912 nondiseased age and sex matched smoking controls were genotyped for six single nucleotide polymorphisms (SNPs) in EPHX1 (including the fast and slow variants and associated haplotypes), and eight SNPs in the two genes encoding GCL. GCL is a rate-limiting enzyme in the synthesis of glutathione, a major contributor to anti-oxidant protection in the lung. No association of variation was found in EPHX1 or GCL with susceptibility to COPD or disease severity. This is the largest reported study to date and is well powered to detect associations that have been previously suggested. The current data indicate that these genetic variants are unlikely to be related to susceptibility or disease severity in white chronic obstructive pulmonary disease patients.

Vascular endothelial growth factor (VEGF) in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS): paradox or paradigm?

Acute respiratory distress syndrome (ARDS), the most severe form of acute lung injury (ALI), remains a devastating condition with a high mortality. It is characterised by alveolar injury and increased pulmonary vascular permeability. Vascular endothelial cell growth factor (VEGF) was identified by its properties to increase permeability and act as a cellular growth factor, hence its potential for a key role in the pathogenesis of ALI/ARDS. This review describes the basic biology of VEGF and its receptors as an essential prerequisite to discussing the available and sometimes paradoxical published data, before considering a paradigm for the role of VEGF in the human lung.

Vascular endothelial growth factor gene polymorphism and acute respiratory distress syndrome.

BACKGROUND: Non-cardiogenic pulmonary oedema is a characteristic feature of the acute respiratory distress syndrome (ARDS). The properties of vascular endothelial growth factor (VEGF) as a potent vascular permogen and mitogen have led to investigation of its potential role in this condition. Lower VEGF plasma levels have been linked to the presence of the T allele in the +936 CT polymorphism. We hypothesised that the presence of the T allele would be associated with the development and severity of ARDS. METHODS: A cohort of 137 normal subjects, 117 ventilated patients with ARDS, and 103 "at risk" of ARDS were genotyped for the VEGF+936 CT polymorphism. The severity of physiological disturbance and mortality was determined in the ventilated cohorts. RESULTS: The CT and TT genotype frequencies were increased in ARDS patients compared with both normal subjects (OR 2.01, 95% CI 1.13 to 3.58, p = 0.02) and those "at risk" (OR 2.05, 95% CI 1.02 to 2.20, p = 0.03). In patients with ARDS but not those "at risk", CT and TT genotypes were associated with a higher mean APACHE III score (80.9 (4.3) v 69.3 (2.9), p<0.05). CONCLUSION: These data support a role for VEGF in the pathogenesis of ARDS and its associated physiological derangement.

Differential expression of Toll-like receptor (TLR)-2 and TLR-4 on monocytes in human sepsis.

Toll-like receptors (TLRs) are a recently described family of immune receptors involved in the recognition of pathogen-associated molecular patterns (PAMPs). The central role of TLR-2 and TLR-4 in microbial responses suggests they may be implicated in the pathogenesis of human sepsis. We hypothesized that the incidence and outcome of sepsis would be influenced by the expression of TLR-2 and TLR-4 on monocytes. We have examined the expression of TLR-2 and TLR-4 mRNA and protein and their response to pro- and anti-inflammatory agents on monocytes from subjects in the intensive therapy unit (ITU) with and without Gram-negative, Gram-positive or polymicrobial sepsis. We compared these data to ITU and healthy control subjects. TLR-2 mRNA was significantly up-regulated on monocytes from subjects with both Gram-positive and Gram-negative sepsis. Similarly, we detected increased levels of TLR-2 protein on the surface of monocytes from sepsis subjects relative to ITU controls. TLR-4 mRNA was increased in Gram-positive subjects; however, there was no corresponding increase in TLR-4 protein. Although TLR-4 mRNA expression in healthy control monocytes could be modulated in vitro by culture with lipopolysaccharide or interleukin-10, this was not observed in monocytes obtained from sepsis and ITU control subjects, suggesting that septic and ITU control milieus may alter the immunoregulation of TLR-4 mRNA expression on monocytes. TLR-2 mRNA was not modulated in culture by any stimulus in any group. We suggest that expression and regulatory response of monocyte TLR-2, and to a lesser extent TLR-4 may be abnormal in human sepsis.

Analysis of an IL-10 polymorphism in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrotic disorder of the lung parenchyma. We have demonstrated changes in IL-10 protein production by alveolar macrophages (AMs) from patients with IPF, which we hypothesise could be because of an IL-10 gene polymorphism. We have screened the coding sequence and 3' untranslated region of IL-10 for polymorphisms using single-standard conformational polymorphism analysis. A novel polymorphism was identified resulting in a G to A substitution of +43 nucleotides from the start codon changing glycine to arginine at amino acid 15 of the signal peptide sequence. We have introduced the signal peptide mutation into the IL-10 gene and compared secretion of the mutant and wild-type forms after transient transfection of COS-7 cells. Our studies showed that the signal peptide mutation did not have a significant effect on secretion at 24 h post-transfection (P=0.4529 by Mann-Whitney test). However, by 48 h there are significantly lower levels of mutant IL-10 (P=0.0515). There were no differences in the level of cell-associated IL-10 at either 24 or 48 h (P=0.9296 and 0.4268). We suggest that the mutation could affect the efficiency of protein translocation and signal peptide cleavage resulting in lower levels of IL-10 protein secretion.

What is the role of the insulin-like growth factor system in the pathophysiology of cancer cachexia, and how is it regulated?

OBJECTIVE AND BACKGROUND: The cancer cachexia syndrome is characterized by anorexia, weight loss with muscle wasting and increased energy expenditure. It is associated with increased morbidity and mortality, but its aetiology is poorly understood and no effective therapeutic intervention is available. It may result from an imbalance between the activity or effect of anabolic and catabolic hormones, mediated by the inflammatory cytokines. IGF-I is a potent anabolic agent, with therapeutic potential. Our objective was to investigate the role and regulation of the IGF system in cancer cachexia. DESIGN AND PATIENTS: We set up a prospective study of 30 patients with newly diagnosed unresectable non-small cell lung cancer, together with a cross-sectional comparison group of healthy volunteers. MEASUREMENTS: We examined the relationship between aspects of the IGF system, including IGFBP-3 proteolysis (using Western ligand and immunoblotting and an in vitro IGFBP-3 protease assay); the inflammatory cytokines and their soluble receptors; and food intake and nutritional status (including biochemical and anthropometric assessments). RESULTS: Although we did not observe a marked reduction in food intake in the cancer patients, the majority lost weight and functionally important lean body mass. We observed GH resistance in the cancer patients, and intermittent proteolysis of IGFBP-3, which correlated with the circulating interleukin-6 (IL-6) concentration. The pattern of IGFBP-3 proteolysis was unusual, with a prominent 17-kDa fragment. Less IGFBP-3 proteolysis was associated with more weight loss, suggesting that this could be a protective counter-regulatory mechanism, increasing IGF-I bioavailability to the tissues. CONCLUSIONS: Cancer cachexia in humans is a complex condition. Patients tend to be GH resistant. The significance of the intermittent increases in IGFBP-3 proteolysis, which may be regulated by IL-6, remains uncertain. A better understanding of the pathophysiology should enable the development of novel therapeutic approaches.

The role of small airways in lung disease.

The small airways constitute one of the least understood areas of the lungs. They play a role in many lung diseases, and small airway pathology results in significant morbidity New approaches to their evaluation may provide insights into this major area of lung disease. Asthma is well recognized as a disease of both large and small airways. Physiological and pathological evidence, from techniques such as post-mortem tissue histological analysis, induced sputum and transbronchial biopsies, has reinforced the concept of the involvement of the entire bronchial tree n the inflammatory process in asthma, In addition to describing the airway pathology in asthma, th s review focuses on the pathogenesis and role of small airway obstruction n other diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), sarcoidosis and obliterative bronchiolitis (OB). COPD is characterized by the presence of airflow obstruction resulting from lesions in the small airways. In addition, features compatible with small airways disease are common in IPF, sarcoidosis and OB. Recent advances in pulmonary imaging, such as high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) with hyperpolarized 3He, have allowed non-invasive reproducible measurements of structure-function relationships to be made for the small airways. These techniques have great potential for diagnosing changes in small airway function and for assessing responses to treatment. New insights into the contribution of small airways to a range of lung diseases may lead to the development of therapies targeted at this part of the bronchial anatomy.

Vascular endothelial growth factor may contribute to increased vascular permeability in acute respiratory distress syndrome.

The development of noncardiogenic pulmonary edema is a characteristic feature of acute respiratory distress syndrome (ARDS). We hypothesized that vascular endothelial growth factor (VEGF) would play an important role in this process. Plasma VEGF was measured in 40 patients with ARDS, 28 at-risk patients, 14 normal control subjects, and 9 ventilated control subjects. Cultured peripheral blood mononuclear cells (PBM) supernatant VEGF was measured in 21 patients with ARDS and 12 at-risk patients, respectively. The functional importance of VEGF as a mediator of endothelial permeability was assessed by measuring albumin flux across human pulmonary endothelial cell monolayers. Plasma VEGF was significantly elevated in patients with ARDS compared with at-risk patients, normal control subjects, and ventilated control subjects (p = 0.01, p = 0.0001, and p = 0.002, respectively). PBM from patients with ARDS produced significantly more VEGF in vitro than at-risk patients (p = 0.05). Albumin flux across human pulmonary endothelial cell monolayers was significantly increased following the addition of plasma from patients with ARDS compared with plasma from normal control subjects (p = 0.008). When VEGF activity in plasma was neutralized by the addition of a soluble VEGF inhibitor, the albumin flux induced by ARDS plasma was reduced by 48%. We conclude that VEGF makes a significant contribution to the endothelial cell permeability-inducing activity in plasma from patients with ARDS, and may play an important role in the development of noncardiogenic pulmonary edema in ARDS.

The balance between collagen synthesis and degradation in diffuse lung disease.

Diffuse interstitial lung disease (DLD) is characterised by varying degrees of inflammation and fibrosis that result in derangement of the gas-exchanging units of the lung. A hallmark of these diseases is the abnormal deposition of collagen, which is a prime determinant of clinical course. This review considers the current information concerning collagen turnover in diffuse fibrotic lung disease. Considerable experimental evidence implicates both increased collagen production and reduced degradation in these diseases. Reduced degradation may result from both reduced production of collagenases and increased inhibition by tissue inhibitors. The known effects upon collagen turnover of novel therapeutic agents for pulmonary fibrosis (pirfenidone and interferon gamma) are discussed.

The 3' untranslated region of tumor necrosis factor-alpha is highly conserved in idiopathic pulmonary fibrosis (IPF).

Tumour necrosis factor alpha (TNF-alpha), a pro-inflammatory cytokine essential for the function of the immune system, has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Production of TNF-alpha is regulated at both the transcriptional and post-transcriptional levels by a number of factors including interleukin-10 (IL-10). We have shown that there is significant TNF-alpha activity in patients with IPF, despite the presence of significant amounts of IL-10 and Il-10R. IL-10 is thought to influence the tight translational repression of TNF-alpha mRNA in pulmonary macrophages. The essential element in this regulation is the AU-rich element (ARE) present in the 3' untranslated region of TNF-alpha. We hypothesised that polymorphism in the 3' UTR region of TNF-alpha explains the apparent failure of IL-10 to down regulate TNF-alpha in patients with IPF. Using single strand conformation polymorphism (SSCP) analysis, we have screened this region in 96 patients with IPF, using nine sets of overlapping PCR primers. All samples were successfully amplified for each primer set, but SSCP analysis was unable to detect point mutations or polymorphisms in the patients in any of the nine fragments. Results from this study suggest that the 3' UTR region of TNF-alpha is highly conserved in IPF and mutation of this region is unlikely to be involved in the pathogenesis of IPF.

Reduced production of interleukin 12 by interferon gamma primed alveolar macrophages from atopic asthmatic subjects.

BACKGROUND: Asthma is characterised pathologically by an inflammatory pulmonary infiltrate rich in T helper (Th) 2 cells and eosinophils. Interleukin (IL)-12 is a heterodimeric cytokine critical for driving the development of uncommitted Th cells to express a Th 1 phenotype. Reduced pulmonary production of IL-12 may therefore play a role in the pathogenesis of asthma by contributing to the pulmonary cytokine imbalance seen in asthma. METHODS: IL-12 p70 protein levels in bronchoalveolar lavage fluid and p70 protein levels and IL-12 messenger RNA in alveolar macrophage cultures from normal and atopic asthmatic subjects were measured. RESULTS: There was a significant difference between the mean IL-12 p70 protein level in the bronchoalveolar lavage fluid from asthmatic subjects (37.5 pg/ml) and from normal subjects (131 pg/ml, p = 0.04). Alveolar macrophages from asthmatic subjects produced significantly less IL-12 protein (30 pg/ml) and messenger RNA than those from normal subjects (69.5 pg/ml, p<0.005). These differences were not caused by inhibition of IL-12 production by IL-10 nor to generalised hyporesponsiveness of asthmatic alveolar macrophages from subjects to the effects of interferon (IFN)-gamma. CONCLUSIONS: Pulmonary IL-12 production is lower in asthmatic subjects. This reduction is not the result of generalised hyporesponsiveness to IFN-gamma. Reduced IL-12 levels may contribute to the development of asthmatic pulmonary inflammation through dysregulation of Th cell development.