Nik Hirani

Interstitial lung disease guideline: the British Thoracic Society in collaboration with the Thoracic Society of Australia and New Zealand and the Irish Thoracic Society.

### 1.1 An overview of the ILD guideline Since the publication of the first BTS guidelines for diffuse lung disease nearly 10 years ago,1 the specialty has seen considerable change. The early discussions of the Guideline Group centred upon whether the revised document might consist of the 1999 document with minor adaptations. However, it was considered that too much change had taken place in the intervening years to justify a simple editorial approach. The last decade had seen the development of a new consensus terminology for the idiopathic interstitial pneumonias (IIP)2 stimulated, in part, by the identification of non-specific interstitial pneumonia (NSIP) as a discrete histological pattern with increasingly recognised clinical correlates.3 The better prognosis seen in fibrotic NSIP than in idiopathic pulmonary fibrosis (IPF)4 5 fuelled a more intense approach to diagnosis in cases of suspected IPF. This in turn has led to a radical change in accepted diagnostic gold standards, which have become increasingly multidisciplinary and dependent equally upon the skills of pathologists, radiologists and clinicians.6 NSIP, as a new entity, has posed particular difficulties. With more detailed studies of outcome specific to individual IIPs, especially IPF and fibrotic NSIP, the prognostic weighting given to pulmonary function impairment has been refined, especially with regard to longitudinal functional trends.7 Most important, with the standardisation of terminology, it became possible to recruit patients into multicentre treatment studies.8–10 With regard to IPF in particular, the last 3 years have seen more studies of treatment than in the previous history of the speciality, yet there is no universally accepted “best current treatment”. ### 1.2 Methodology for constructing guidelines and making recommendations The overall process for generating BTS guidelines has been addressed in numerous recently published documents (available at http://www.brit-thoracic.org.uk/guidelines.html). The methodology applied herein is broadly similar and is not therefore described in detail. However, there are specific aspects in the …

Human circulating eosinophils secrete macrophage migration inhibitory factor (MIF). Potential role in asthma.

Macrophage migration inhibitory factor (MIF) is a potent proinflammatory mediator that has been shown to potentiate lethal endotoxemia and to play a potentially important regulatory role in human acute respiratory distress syndrome (ARDS). We have investigated whether eosinophils are an important source of MIF and whether MIF may be involved in the pathophysiology of asthma. Unstimulated human circulating eosinophils were found to contain preformed MIF. Stimulation of human eosinophils with phorbol myristate acetate in vitro yielded significant release of MIF protein. For example, eosinophils stimulated with phorbol myristate acetate (100 nM, 8 h, 37 degreesC) released 1,539+/-435 pg/10(6) cells of MIF, whereas unstimulated cells released barely detectable levels (< 142 pg/10(6) cells, mean+/-SEM, n = 8). This stimulated release was shown to be (a) concentration- and time-dependent, (b) partially blocked by the protein synthesis inhibitor cycloheximide, and (c) significantly inhibited by the protein kinase C inhibitor Ro-31,8220. In addition, we show that the physiological stimuli C5a and IL-5 also cause significant MIF release. Furthermore, bronchoalveolar lavage fluid obtained from asthmatic patients contains significantly elevated levels of MIF as compared to nonatopic normal volunteers (asthmatic, 797.5+/-92 pg/ml; controls, 274+/-91 pg/ml). These results highlight the potential importance of MIF in asthma and other eosinophil-dependent inflammatory disorders.

The Toll-like Receptor 3 L412F Polymorphism and Disease Progression in Idiopathic Pulmonary Fibrosis

RATIONALE Idiopathic pulmonary fibrosis (IPF) is a fatal progressive interstitial pneumonia. The innate immune system provides a crucial function in the recognition of tissue injury and infection. Toll-like receptor 3 (TLR3) is an innate immune system receptor. We investigated the role of a functional TLR3 single-nucleotide polymorphism in IPF. OBJECTIVES To characterize the effects of the TLR3 Leu412Phe polymorphism in primary pulmonary fibroblasts from patients with IPF and disease progression in two independent IPF patient cohorts. To investigate the role of TLR3 in a murine model of pulmonary fibrosis. METHODS TLR3-mediated cytokine, type 1 IFN, and fibroproliferative responses were examined in TLR3 wild-type (Leu/Leu), heterozygote (Leu/Phe), and homozygote (Phe/Phe) primary IPF pulmonary fibroblasts by ELISA, real-time polymerase chain reaction, and proliferation assays. A murine model of bleomycin-induced pulmonary fibrosis was used in TLR3 wild-type (tlr3(+/+)) and TLR3 knockout mice (tlr3(-/-)). A genotyping approach was used to investigate the role of the TLR3 L412F polymorphism in disease progression in IPF using survival analysis and longitudinal decline in FVC. MEASUREMENTS AND MAIN RESULTS Activation of TLR3 in primary lung fibroblasts from TLR3 L412F-variant patients with IPF resulted in defective cytokine, type I IFN, and fibroproliferative responses. We demonstrate increased collagen and profibrotic cytokines in TLR3 knockout mice (tlr3(-/-)) compared with wild-type mice (tlr3(+/+)). TLR3 L412F was also associated with a significantly greater risk of mortality and an accelerated decline in FVC in patients with IPF. CONCLUSIONS This study reveals the crucial role of defective TLR3 function in promoting progressive IPF.

Nacystelyn inhibits oxidant-mediated interleukin-8 expression and NF-κB nuclear binding in alveolar epithelial cells

Nacystelyn (NAL), a recently developed lysine salt of N-acetyl-L-cytokine (NAC) has mucolytic and antioxidant properties. In this study, we investigated the effect of NAL upon oxidant-mediated interleukin (IL)-8 release and the activation of the redox-sensitive transcription factors AP-1, NF-kappaB, and C/EBP in a human alveolar epithelial cell line (A549). NAL (5 mM) enhanced intracellular glutathione (GSH) after 4 h and abolished H(2)O(2)-induced IL-8 release from A549 cells. This was associated with inhibition of NF-kappaB and C/EBP DNA-binding, measured by the Electrophoretic Mobility Shift Assay (EMSA). NAL also abolished the transcriptional activation of IL-8 in an IL-8-chloramphenicol acetyl transferase (CAT) reporter system, transfected into A549 cells. Supernatants obtained from H(2)O(2)-treated A549 cells induced chemotaxis of polymorphonuclear neutrophils, which could be inhibited by co-incubation with NAL. These data indicate that NAL may be used to modulate pro-inflammatory process by inhibiting cytokine release in the lungs and thus has therapeutic potential in inflammatory lung diseases.

Monocytes Control Second-Phase Neutrophil Emigration in Established Lipopolysaccharide-induced Murine Lung Injury

RATIONALE Acute lung injury (ALI) is an important cause of morbidity and mortality, with no currently effective pharmacological therapies. Neutrophils have been specifically implicated in the pathogenesis of ALI, and there has been significant research into the mechanisms of early neutrophil recruitment, but those controlling the later phases of neutrophil emigration that characterize disease are poorly understood. OBJECTIVES To determine the influence of peripheral blood monocytes (PBMs) in established ALI. METHODS In a murine model of LPS-induced ALI, three separate models of conditional monocyte ablation were used: systemic liposomal clodronate (sLC), inducible depletion using CD11b diphtheria toxin receptor (CD11b DTR) transgenic mice, and antibody-dependent ablation of CCR2(hi) monocytes. MEASUREMENTS AND MAIN RESULTS PBMs play a critical role in regulating neutrophil emigration in established murine LPS-induced lung injury. Gr1(hi) and Gr1(lo) PBM subpopulations contribute to this process. PBM depletion is associated with a significant reduction in measures of lung injury. The specificity of PBM depletion was demonstrated by replenishment studies in which the effects were reversed by systemic PBM infusion but not by systemic or local pulmonary infusion of mature macrophages or lymphocytes. CONCLUSIONS These results suggest that PBMs, or the mechanisms by which they influence pulmonary neutrophil emigration, could represent therapeutic targets in established ALI.

Induction of eosinophil apoptosis by the cyclin-dependent kinase inhibitor AT7519 promotes the resolution of eosinophil-dominant allergic inflammation.

Background Eosinophils not only defend the body against parasitic infection but are also involved in pathological inflammatory allergic diseases such as asthma, allergic rhinitis and contact dermatitis. Clearance of apoptotic eosinophils by macrophages is a key process responsible for driving the resolution of eosinophilic inflammation and can be defective in allergic diseases. However, enhanced resolution of eosinophilic inflammation by deliberate induction of eosinophil apoptosis using pharmacological agents has not been previously demonstrated. Here we investigated the effect of a novel cyclin-dependent kinase inhibitor drug, AT7519, on human and mouse eosinophil apoptosis and examined whether it could enhance the resolution of a murine model of eosinophil-dominant inflammation in vivo. Methodology/Principal Findings Eosinophils from blood of healthy donors were treated with AT7519 and apoptosis assessed morphologically and by flow-cytometric detection of annexin-V/propidium iodide staining. AT7519 induced eosinophil apoptosis in a concentration dependent manner. Therapeutic administration of AT7519 in eosinophil-dominant allergic inflammation was investigated using an established ovalbumin-sensitised mouse model of allergic pleurisy. Following ovalbumin challenge AT7519 was administered systemically at the peak of pleural inflammation and inflammatory cell infiltrate, apoptosis and evidence of macrophage phagocytosis of apoptotic eosinophils assessed at appropriate time points. Administration of AT7519 dramatically enhanced the resolution of allergic pleurisy via direct induction of eosinophil apoptosis without detriment to macrophage clearance of these cells. This enhanced resolution of inflammation was shown to be caspase-dependent as the effects of AT7519 were reduced by treatment with a broad spectrum caspase inhibitor (z-vad-fmk). Conclusions Our data show that AT7519 induces human eosinophil apoptosis and enhances the resolution of a murine model of allergic pleurisy by inducing caspase-dependent eosinophil apoptosis and enhancing macrophage ingestion of apoptotic eosinophils. These findings demonstrate the utility of cyclin-dependent kinase inhibitors such as AT7519 as potential therapeutic agents for the treatment of eosinophil dominant allergic disorders.

A novel subpopulation of monocyte-like cells in the human lung after lipopolysaccharide inhalation

The co-ordinated recruitment of monocyte subpopulations, neutrophils and regulatory T-cells (Tregs) during the early stages of human acute lung inflammation remains poorly understood. We therefore performed a detailed characterisation of these lineages in the blood and lungs in a model of human acute lung inflammation. Healthy volunteers inhaled lipopolysaccharide (LPS) or saline (n=6 for each group). Blood was collected at 0, 2, 4, 6 and 8 h and bronchoscopy with bronchoalveolar lavage (BAL) performed at 8 h. Multiparameter flow cytometry was used to characterise monocyte subpopulations, neutrophils and Tregs in the blood and lung. Inhalation of LPS was associated with significant blood and BAL fluid neutrophilia. Blood populations of monocyte subpopulations and Tregs were unaltered by LPS. In contrast, LPS induced an accumulation of a pulmonary monocyte-like cell (PMLC) population, which was further subdivided into “inducible” CD14++CD16- and “resident” CD14++CD16+ subsets. Inducible PMLCs were significantly increased following LPS inhalation (p=0.0046), whereas resident PMLCs were unchanged. In addition, we noted a significant decrease in Tregs in BAL fluid with LPS inhalation (p=0.027). The early stages of LPS-induced inflammation in humans is characterised by pulmonary accumulation of a novel inducible monocyte-like subpopulation, accompanied by significant changes in both neutrophil and Treg numbers.

Oxygen levels determine the ability of glucocorticoids to influence neutrophil survival in inflammatory environments

GCs are highly effective in treating a wide range of inflammatory diseases but are limited in their ability to control neutrophilic lung inflammation in conditions such as COPD. Neutrophil apoptosis, a central feature of inflammation resolution, is delayed in response to microenvironmental cues, such as hypoxia and inflammatory cytokines, present at inflamed sites. GCs delay neutrophil apoptosis in vitro, and this may therefore limit the ability of GCs to control neutrophilic inflammation. This study assesses the effect GCs have on hypoxia‐ and inflammatory cytokine‐induced neutrophil survival. Human neutrophils were treated with GCs in the presence or absence of GM‐CSF or inflammatory macrophage‐CM at a range of oxygen concentrations (21–1% oxygen). Neutrophil apoptosis and survival were assessed by flow cytometry and morphological analysis and neutrophil function, by stimulus‐induced shape change and respiratory burst. Dexamethasone promoted neutrophil survival at 21%, 10%, and 5% oxygen but not at 1% oxygen. Interestingly, GM‐CSF and inflammatory CM increased neutrophil survival significantly, even at 1% oxygen, with cells remaining functionally active at 96 h. Dexamethasone was able to reduce the prosurvival effect of GM‐CSF and inflammatory CM in a hypoxic environment. In conclusion, we found that GCs do not augment neutrophil survival in the presence of severe hypoxia or proinflammatory mediators. This suggests that GCs would not promote neutrophil survival at sites of inflammation under these conditions.

In search of the fibrotic epithelial cell: opportunities for a collaborative network

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease of unknown aetiology. It has a very poor prognosis and no effective treatment. There are two major barriers to the development of novel treatments in IPF: an incomplete understanding of its pathogenesis and the fact that current models of the disease are poorly predictive of therapeutic response. Recent studies suggest an important role for the alveolar epithelium in the pathogenesis of IPF. However, practical limitations associated with isolation and culture of primary alveolar epithelial cells have hampered progress towards further elucidating their role in the pathogenesis of the disease or developing disease models that accurately reflect the epithelial contribution. The practical limitations of primary alveolar epithelial cell culture can be divided into technical, logistical and regulatory hurdles that need to be overcome to ensure rapid progress towards improved treatment for patients with IPF. To develop a strategy to facilitate alveolar epithelial cell harvest, retrieval and sharing between IPF research groups and to determine how these cells contribute to IPF, a workshop was organised to discuss the central issues surrounding epithelial cells in IPF (ECIPF). The central themes discussed in the workshop have been compiled as the proceedings of the ECIPF.

Genetic variants associated with susceptibility to idiopathic pulmonary fibrosis in people of European ancestry: a genome-wide association study

Summary Background Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with high mortality, uncertain cause, and few treatment options. Studies have identified a significant genetic risk associated with the development of IPF; however, mechanisms by which genetic risk factors promote IPF remain unclear. We aimed to identify genetic variants associated with IPF susceptibility and provide mechanistic insight using gene and protein expression analyses. Methods We used a two-stage approach: a genome-wide association study in patients with IPF of European ancestry recruited from nine different centres in the UK and controls selected from UK Biobank (stage 1) matched for age, sex, and smoking status; and a follow-up of associated genetic variants in independent datasets of patients with IPF and controls from two independent US samples from the Chicago consortium and the Colorado consortium (stage 2). We investigated the effect of novel signals on gene expression in large transcriptomic and genomic data resources, and examined expression using lung tissue samples from patients with IPF and controls. Findings 602 patients with IPF and 3366 controls were selected for stage 1. For stage 2, 2158 patients with IPF and 5195 controls were selected. We identified a novel genome-wide significant signal of association with IPF susceptibility near A-kinase anchoring protein 13 (AKAP13; rs62025270, odds ratio [OR] 1·27 [95% CI 1·18–1·37], p=1·32 × 10−9) and confirmed previously reported signals, including in mucin 5B (MUC5B; rs35705950, OR 2·89 [2·56–3·26], p=1·12 × 10−66) and desmoplakin (DSP; rs2076295, OR 1·44 [1·35–1·54], p=7·81 × 10−28). For rs62025270, the allele A associated with increased susceptibility to IPF was also associated with increased expression of AKAP13 mRNA in lung tissue from patients who had lung resection procedures (n=1111). We showed that AKAP13 is expressed in the alveolar epithelium and lymphoid follicles from patients with IPF, and AKAP13 mRNA expression was 1·42-times higher in lung tissue from patients with IPF (n=46) than that in lung tissue from controls (n=51). Interpretation AKAP13 is a Rho guanine nucleotide exchange factor regulating activation of RhoA, which is known to be involved in profibrotic signalling pathways. The identification of AKAP13 as a susceptibility gene for IPF increases the prospect of successfully targeting RhoA pathway inhibitors in patients with IPF. Funding UK Medical Research Council, National Heart, Lung, and Blood Institute of the US National Institutes of Health, Agencia Canaria de Investigación, Innovación y Sociedad de la Información, Spain, UK National Institute for Health Research, and the British Lung Foundation.