Peter H. Howarth

Mepolizumab for severe eosinophilic asthma (DREAM): a multicentre, double-blind, placebo-controlled trial

BACKGROUND Some patients with severe asthma have recurrent asthma exacerbations associated with eosinophilic airway inflammation. Early studies suggest that inhibition of eosinophilic airway inflammation with mepolizumab-a monoclonal antibody against interleukin 5-is associated with a reduced risk of exacerbations. We aimed to establish efficacy, safety, and patient characteristics associated with the response to mepolizumab. METHODS We undertook a multicentre, double-blind, placebo-controlled trial at 81 centres in 13 countries between Nov 9, 2009, and Dec 5, 2011. Eligible patients were aged 12-74 years, had a history of recurrent severe asthma exacerbations, and had signs of eosinophilic inflammation. They were randomly assigned (in a 1:1:1:1 ratio) to receive one of three doses of intravenous mepolizumab (75 mg, 250 mg, or 750 mg) or matched placebo (100 mL 0·9% NaCl) with a central telephone-based system and computer-generated randomly permuted block schedule stratified by whether treatment with oral corticosteroids was required. Patients received 13 infusions at 4-week intervals. The primary outcome was the rate of clinically significant asthma exacerbations, which were defined as validated episodes of acute asthma requiring treatment with oral corticosteroids, admission, or a visit to an emergency department. Patients, clinicians, and data analysts were masked to treatment assignment. Analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01000506. FINDINGS 621 patients were randomised: 159 were assigned to placebo, 154 to 75 mg mepolizumab, 152 to 250 mg mepolizumab, and 156 to 750 mg mepolizumab. 776 exacerbations were deemed to be clinically significant. The rate of clinically significant exacerbations was 2·40 per patient per year in the placebo group, 1·24 in the 75 mg mepolizumab group (48% reduction, 95% CI 31-61%; p<0·0001), 1·46 in the 250 mg mepolizumab group (39% reduction, 19-54%; p=0·0005), and 1·15 in the 750 mg mepolizumab group (52% reduction, 36-64%; p<0·0001). Three patients died during the study, but the deaths were not deemed to be related to treatment. INTERPRETATION Mepolizumab is an effective and well tolerated treatment that reduces the risk of asthma exacerbations in patients with severe eosinophilic asthma. FUNDING GlaxoSmithKline.

Induction of nitric oxide synthase in asthma

Nitric oxide (NO) is a mediator of vasodilatation and bronchodilatation synthesised from L-arginine by the enzyme NO synthase, which is either constitutive or induced by lipopolysaccharides and/or cytokines. The presence and function of NO synthase in normal or diseased lung is not yet clear. Asthma is characterised by bronchial hyperresponsiveness, epithelial damage, inflammation, and increased cytokine production. To investigate the presence of NO synthase in asthma, we immunostained bronchial biopsies from non-steroid-treated people with asthma and non-asthmatic controls with specific polyvalent antisera to purified inducible NO synthase and to a selected peptide sequence of the same enzyme. Immunoreactivity was seen in the epithelium and some inflammatory cells in 22 of 23 biopsies from people with asthma, but in only 2 of 20 controls. To assess the relation of cytokines to NO synthase induction, bronchial epithelial cells in culture were stimulated with tumour necrosis factor (TNF alpha). Inducible enzyme immunoreactivity was found only in the treated cells. The existence of inducible NO synthase in human lungs suggests that increased production of NO, probably induced by cytokines, may be relevant to the pathology of asthma.

Consensus statement on the treatment of allergic rhinitis.

Allergic rhinitis (AR) is a high-prevalence disease in many developed countries, affecting about 10±20% of the general population (1±5). Several studies based on questionnaire and objective testing or medical examination indicate an increasing prevalence of AR in European countries over the last decades (6, 7). AR is characterized by nasal itching, sneezing, watery rhinorrhoea, and nasal obstruction. Additional symptoms such as headache, impaired smell, and conjunctival symptoms can be associated. According to the time of exposure, AR can be subdivided into perennial, seasonal, and occupational disease. Perennial AR (PAR) is most frequently caused by dust mites and animal dander. Seasonal AR (SAR) is related to a wide variety of pollen allergens including grasses, Parietaria, Ambrosia, Artemisia, birch, olive, hazelnut, and cypress. The morbidity of SAR obviously depends on the geographic region, the pollen season of the plants, and the local climate. Several other conditions can cause similar symptoms and are referred to as nonallergic (noninfectious) rhinitis: NARES (nonallergic rhinitis with eosinophilia syndrome); aspirin sensitivity; endocrine, occupational, postinfectious, and side-effects of systemic drugs; abuse of topical decongestants (rhinitis medicamentosa); and idiopathic rhinitis. Furthermore, diseases such as nasal polyposis, chronic sinusitis, cystic ®brosis, Wegeners disease, benign or malignant tumours, etc. have to be excluded carefully. Therefore, current guidelines (4) emphasize the importance of an accurate diagnosis of patients presenting with rhinitis symptoms. In fact, several causes may commonly coexist in the same *European Academy of Allergology and Clinical Immunology. Allergy 2000: 55: 116±134 Printed in UK. All rights reserved Copyright # Munksgaard 2000

Involvement of the epidermal growth factor receptor in epithelial repair in asthma

Epithelial damage and airway remodeling are consistent features of bronchial asthma and are correlated with disease chronicity, severity, and bronchial hyperreactivity. To examine the mechanisms that control bronchial epithelial repair, we investigated expression of the epidermal growth factor receptor (c‐erbB1, EGFR) in asthmatic bronchial mucosa and studied repair responses in vitro. In biopsies from asthmatic subjects, areas of epithelial damage were frequently observed and exhibited strong EGFR immunostaining. EGFR expression was also high in morphologically intact asthmatic epithelium. Using image analysis, EGFR immunoreactivity (% of total epithelial area, median (range) was found to increase from 9.4 (4.1‐20.4) in normal subjects (n=10) to 18.4 (9.3‐28.9) in mild asthmatics (P<0.01, n=13) and 25.4 (15.4‐31.8) in severe asthmatics (P<0.00, n=5). Epithelial EGFR immunoreactivity remained elevated in patients treated with corticosteroids and was positively correlated with subepithelial reticular membrane thickening. Using 16HBE 14o‐ bronchial epithelial cells, we found that EGF accelerated repair of scrape‐wounded monolayers and that the EGFR‐selective inhibitor, tyrphostin AG1478, inhibited both EGF‐stimulated and basal wound closure whereas dexamethasone was without effect. Intrinsic activation of the EGFR was confirmed by analysis of tyrosine phosphorylated proteins, which revealed a rapid, damage‐induced phosphorylation of the EGFR, irrespective of the presence of exogenous EGF. To assess the relationship between EGFR‐mediated repair and tissue remodeling, release of the profibrogenic mediator TGF‐β2 was also measured. Scrape wounding increased release of TGF‐β2 from epithelial monolayers and EGF had no additional stimulatory effect. However, when repair was retarded with AG1478, the amount of TGF‐β2 increased significantly. These data indicate that the EGFR may play an important role in bronchial epithelial repair in asthma and that impairment of this function may augment airway remodeling.—Puddicombe, S. M., Polosa, R., Richter, A., Krishna, M. T., Howarth, P. H., Holgate, S. T., Davies, D. E. Involvement of the epidermal growth factor receptor in epithelial repair in asthma. FASEB J. 14, 1362–1374 (2000)

Tumour necrosis factor (TNFα) as a novel therapeutic target in symptomatic corticosteroid dependent asthma

Background: Tumour necrosis factor α (TNFα) is a major therapeutic target in a range of chronic inflammatory disorders characterised by a Th1 type immune response in which TNFα is generated in excess. By contrast, asthma is regarded as a Th2 type disorder, especially when associated with atopy. However, as asthma becomes more severe and chronic, it adopts additional characteristics including corticosteroid refractoriness and involvement of neutrophils suggestive of an altered inflammatory profile towards a Th1 type response, incriminating cytokines such as TNFα. Methods: TNFα levels in bronchoalveolar lavage (BAL) fluid of 26 healthy controls, 42 subjects with mild asthma and 20 with severe asthma were measured by immunoassay, and TNFα gene expression was determined in endobronchial biopsy specimens from 14 patients with mild asthma and 14 with severe asthma. The cellular localisation of TNFα was assessed by immunohistochemistry. An open label uncontrolled clinical study was then undertaken in 17 subjects with severe asthma to evaluate the effect of 12 weeks of treatment with the soluble TNFα receptor-IgG1Fc fusion protein, etanercept. Results: TNFα levels in BAL fluid, TNFα gene expression and TNFα immunoreative cells were increased in subjects with severe corticosteroid dependent asthma. Etanercept treatment was associated with improvement in asthma symptoms, lung function, and bronchial hyperresponsiveness. Conclusions: These findings may be of clinical significance in identifying TNFα as a new therapeutic target in subjects with severe asthma. The effects of anti-TNF treatment now require confirmation in placebo controlled studies.

Effect of Bronchoconstriction on Airway Remodeling in Asthma

BACKGROUND Asthma is characterized pathologically by structural changes in the airway, termed airway remodeling. These changes are associated with worse long-term clinical outcomes and have been attributed to eosinophilic inflammation. In vitro studies indicate, however, that the compressive mechanical forces that arise during bronchoconstriction may induce remodeling independently of inflammation. We evaluated the influence of repeated experimentally induced bronchoconstriction on airway structural changes in patients with asthma. METHODS We randomly assigned 48 subjects with asthma to one of four inhalation challenge protocols involving a series of three challenges with one type of inhaled agent presented at 48-hour intervals. The two active challenges were with either a dust-mite allergen (which causes bronchoconstriction and eosinophilic inflammation) or methacholine (which causes bronchoconstriction without eosinophilic inflammation); the two control challenges (neither of which causes bronchoconstriction) were either saline alone or albuterol followed by methacholine (to control for nonbronchoconstrictor effects of methacholine). Bronchial-biopsy specimens were obtained before and 4 days after completion of the challenges. RESULTS Allergen and methacholine immediately induced similar levels of bronchoconstriction. Eosinophilic inflammation of the airways increased only in the allergen group, whereas both the allergen and the methacholine groups had significant airway remodeling not seen in the two control groups. Subepithelial collagen-band thickness increased by a median of 2.17 μm in the allergen group (interquartile range [IQR], 0.70 to 3.67) and 1.94 μm in the methacholine group (IQR, 0.37 to 3.24) (P<0.001 for the comparison of the two challenge groups with the two control groups); periodic acid-Schiff staining of epithelium (mucus glands) also increased, by a median of 2.17 percentage points in the allergen group (IQR, 1.03 to 4.77) and 2.13 percentage points in the methacholine group (IQR, 1.14 to 7.96) (P=0.003 for the comparison with controls). There were no significant differences between the allergen and methacholine groups. CONCLUSIONS Bronchoconstriction without additional inflammation induces airway remodeling in patients with asthma. These findings have potential implications for management.

Defective epithelial barrier function in asthma

BACKGROUND Asthma is a complex disease involving gene and environment interactions. Although atopy is a strong predisposing risk factor for asthma, local tissue susceptibilities are required for disease expression. The bronchial epithelium forms the interface with the external environment and is pivotally involved in controlling tissue homeostasis through provision of a physical barrier controlled by tight junction (TJ) complexes. OBJECTIVES To explain the link between environment exposures and airway vulnerability, we hypothesized that epithelial TJs are abnormal in asthma, leading to increased susceptibility to environmental agents. METHODS Localization of TJs in bronchial biopsies and differentiated epithelial cultures was assessed by electron microscopy or immunostaining. Baseline permeability and the effect of cigarette smoke and growth factor were assessed by measurement of transepithelial electrical resistance and passage of fluorescently labeled dextrans. RESULTS By using immunostaining, we found that bronchial biopsies from asthmatic subjects displayed patchy disruption of TJs. In differentiated bronchial epithelial cultures, TJ formation and transepithelial electrical resistance were significantly lower (P < .05) in cultures from asthmatic donors (n = 43) than from normal controls (n = 40) and inversely correlated with macromolecular permeability. Cultures from asthmatic donors were also more sensitive to disruption by cigarette smoke extract. Epidermal growth factor enhanced basal TJ formation in cultures from asthmatic subjects (P < .01) and protected against cigarette smoke-induced barrier disruption (P < .01). CONCLUSIONS Our results show that the bronchial epithelial barrier in asthma is compromised. This defect may facilitate the passage of allergens and other agents into the airway tissue, leading to immune activation and may thus contribute to the end organ expression of asthma.

Eridothelin immunoreactivity of airway epithelium in asthmatic patients

There is extensive pharmacological and physiological evidence that endothelin-1 influences airway calibre. In mammals, endothelin receptor occur on airway smooth muscle, local storage and release of the peptide have been demonstrated, and inhalation of endothelin-1 induces bronchoconstriction. To investigate the relation between endothelins and asthma the expression of this peptide in endobronchial biopsy specimens was examined immunohistochemically with an antiserum against endothelin-1. Biopsy specimens from 17 asthmatic patients and 11 atopic and non-atopic healthy controls revealed striking differences, with endothelin expression being evident in airways epithelium and vascular endothelium in 11 of the 17 asthmatic patients but in only 1 of 11 controls. These results suggest that endothelins may play a part in the exaggerated bronchomotor tone of asthma.

Asthma in adults and its association with chronic rhinosinusitis: the GA2LEN survey in Europe

To cite this article: Jarvis D, Newson R, Lotvall J, Hastan D, Tomassen P, Keil T, Gjomarkaj M, Forsberg B, Gunnbjornsdottir M, Minov J, Brozek G, Dahlen SE, Toskala E, Kowalski ML, Olze H, Howarth P, Krämer U, Baelum J, Loureiro C, Kasper L, Bousquet PJ, Bousquet J, Bachert C, Fokkens W, Burney P. Asthma in adults and its association with chronic rhinosinusitis: The GA2LEN survey in Europe. Allergy 2012; 67: 91–98.

BSACI guidelines for the management of allergic and non-allergic rhinitis.

This guidance for the management of patients with allergic and non‐allergic rhinitis has been prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is for use by both adult physicians and paediatricians practicing in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a web‐based system. Their comments and suggestions were carefully considered by the SOCC. Where evidence was lacking, consensus was reached by the experts on the committee. Included in this guideline are clinical classification of rhinitis, aetiology, diagnosis, investigations and management including subcutaneous and sublingual immunotherapy. There are also special sections for children, co‐morbid associations and pregnancy. Finally, we have made recommendations for potential areas of future research.