Douglas C. Cowan

Effects of steroid therapy on inflammatory cell subtypes in asthma

Rationale Airway inflammation in asthma is heterogeneous with different phenotypes. The inflammatory cell phenotype is modified by corticosteroids and smoking. Steroid therapy is beneficial in eosinophilic asthma (EA), but evidence is conflicting regarding non-eosinophilic asthma (NEA). Objectives To assess the inflammatory cell phenotypes in asthma after eliminating potentially confounding effects; to compare steroid response in EA versus NEA; and to investigate changes in sputum cells with inhaled corticosteroid (ICS). Methods Subjects undertook ICS withdrawal until loss of control or 28 days. Those with airway hyper-responsiveness (AHR) took inhaled fluticasone 1000 μg daily for 28+ days. Cut-off points were ≥/<2% for sputum eosinophils and ≥/<61% for neutrophils. Results After steroid withdrawal (n=94), 67% of subjects were eosinophilic, 31% paucigranulocytic and 2% mixed; there were no neutrophilic subjects. With ICS (n=88), 39% were eosinophilic, 46% paucigranulocytic, 3% mixed and 5% neutrophilic. Sputum neutrophils increased from 19.3% to 27.7% (p=0.024). The treatment response was greater in EA for symptoms (p<0.001), quality of life (p=0.012), AHR (p=0.036) and exhaled nitric oxide (p=0.007). Lesser but significant changes occurred in NEA (ie, paucigranulocytic asthma). Exhaled nitric oxide was the best predictor of steroid response in NEA for AHR (area under the curve 0.810), with an optimum cut-off point of 33 ppb. Conclusions After eliminating the effects of ICS and smoking, a neutrophilic phenotype could be identified in patients with moderate stable asthma. ICS use led to phenotype misclassification. Steroid responsiveness was greater in EA, but the absence of eosinophilia did not indicate the absence of a steroid response. In NEA this was best predicted by baseline exhaled nitric oxide.

Sputum gene expression signature of 6 biomarkers discriminates asthma inflammatory phenotypes

BACKGROUND Airway inflammation is associated with asthma exacerbation risk, treatment response, and disease mechanisms. OBJECTIVE This study aimed to identify and validate a sputum gene expression signature that discriminates asthma inflammatory phenotypes. METHODS An asthma phenotype biomarker discovery study generated gene expression profiles from induced sputum of 47 asthmatic patients. A clinical validation study (n = 59 asthmatic patients) confirmed differential expression of key genes. A 6-gene signature was identified and evaluated for reproducibility (n = 30 asthmatic patients and n = 20 control subjects) and prediction of inhaled corticosteroid (ICS) response (n = 71 asthmatic patients). Receiver operating characteristic curves were calculated, and area under the curve (AUC) values were reported. RESULTS From 277 differentially expressed genes between asthma inflammatory phenotypes, we identified 23 genes that showed highly significant differential expression in both the discovery and validation populations. A signature of 6 genes, including Charcot-Leydon crystal protein (CLC); carboxypeptidase A3 (CPA3); deoxyribonuclease I-like 3 (DNASE1L3); IL-1β (IL1B); alkaline phosphatase, tissue-nonspecific isozyme (ALPL); and chemokine (C-X-C motif) receptor 2 (CXCR2), was reproducible and could significantly (P < .0001) discriminate eosinophilic asthma from other phenotypes, including patients with noneosinophilic asthma (AUC, 89.6%), paucigranulocytic asthma (AUC, 92.6%), or neutrophilic asthma (AUC, 91.4%) and healthy control subjects (AUC, 97.6%), as well as discriminating patients with neutrophilic asthma from those with paucigranulocytic asthma (AUC, 85.7%) and healthy control subjects (AUC, 90.8). The 6-gene signature predicted ICS response (>12% change in FEV1; AUC, 91.5%). ICS treatment reduced the expression of CLC, CPA3, and DNASE1L3 in patients with eosinophilic asthma. CONCLUSIONS A sputum gene expression signature of 6 biomarkers reproducibly and significantly discriminates inflammatory phenotypes of asthma and predicts ICS treatment response. This signature has the potential to become a useful diagnostic tool to assist in the clinical diagnosis and management of asthma.

Simvastatin in the treatment of asthma: lack of steroid-sparing effect.

Background Statins have anti-inflammatory actions which in theory are potentially beneficial in asthma. Small trials have failed to show a significant benefit, but a systematic study to evaluate the steroid-sparing effect of statin treatment has not been carried out. Methods A randomised, placebo-controlled, crossover trial was conducted of simvastatin 40 mg at night with simultaneous stepwise reduction of fluticasone propionate dose until loss of control occurred, followed by an increase until regain of control (‘minimum’ dose required) in 51 patients with asthma and sputum eosinophils (steroid-free) ≥2%. Results 43 patients completed the study. There was no significant difference in ‘minimum’ inhaled corticosteroid (ICS) dose requirement between simvastatin and placebo: (median (IQR) 50 μg daily (0–250) vs 100 μg daily (0–250), p=0.931). ‘Minimum’ dose distribution was similar (p=0.269). The fluticasone dose at which loss of control occurred did not differ significantly between simvastatin and placebo (p=0.404). In patients with loss of control in both treatment arms, fluticasone dose at loss of control was similar with simvastatin and placebo (median (IQR) 50 μg daily (0–100) for both, p=0.620). In those patients who reached 0 μg/day (n=18), Astma Control Questionnaire (ACQ) was lower (p=0.037), forced expiratory volume in 1 s (FEV1) higher (p<0.01) and sputum eosinophils lower with simvastatin compared with placebo (9.5% compared with 25.4%, p=0.033). Conclusions Simvastatin does not have clinically important steroid-sparing effects in patients with eosinophilic asthma. In the absence of steroid, simvastatin is associated with minor improvements in symptoms and lung function, and a reduction in sputum eosinophils. Clinical trial number ACTRN12606000531516.

Research in progress: Medical Research Council United Kingdom Refractory Asthma Stratification Programme (RASP-UK)

The UK Refractory Asthma Stratification Programme (RASP-UK) will explore novel biomarker stratification strategies in severe asthma to improve clinical management and accelerate development of new therapies. Prior asthma mechanistic studies have not stratified on inflammatory phenotype and the understanding of pathophysiological mechanisms in asthma without Type 2 cytokine inflammation is limited. RASP-UK will objectively assess adherence to corticosteroids (CS) and examine a novel composite biomarker strategy to optimise CS dose; this will also address what proportion of patients with severe asthma have persistent symptoms without eosinophilic airways inflammation after progressive CS withdrawal. There will be interactive partnership with the pharmaceutical industry to facilitate access to stratified populations for novel therapeutic studies.

Medical research council united kingdom refractory asthma stratification programme (RASP-UK)

The UK Refractory Asthma Stratification Programme (RASP-UK) will explore novel biomarker stratification strategies in severe asthma to improve clinical management and accelerate development of new therapies. Prior asthma mechanistic studies have not stratified on inflammatory phenotype and the understanding of pathophysiological mechanisms in asthma without Type 2 cytokine inflammation is limited. RASP-UK will objectively assess adherence to corticosteroids (CS) and examine a novel composite biomarker strategy to optimise CS dose; this will also address what proportion of patients with severe asthma have persistent symptoms without eosinophilic airways inflammation after progressive CS withdrawal. There will be interactive partnership with the pharmaceutical industry to facilitate access to stratified populations for novel therapeutic studies.

Asthma phenotypes: consistency of classification using induced sputum.

Background and objective:  Asthma can be classified as eosinophilic or non‐eosinophilic based on the cell profile of induced sputum. This classification can help determine whether corticosteroid treatment is indicated. We assessed the stability of these phenotypes over time and with different treatment regimens.

Obstructive sleep apnoea syndrome and weight loss: review.

Obstructive sleep apnoea (OSA) syndrome is common, and obesity is a major risk factor. Increased peripharyngeal and central adiposity result in increased pharyngeal collapsibility, through increased mechanical loading around the upper airway, reduced tracheal traction on the pharynx, and reduced neuromuscular activity, particularly during sleep. Significant and sustained weight loss, if achieved, is likely to be a useful therapeutic option in the management of OSA and may be attempted by behavioural, pharmacological, and surgical approaches. Behavioural therapy programs that focus on aspects such as dietary intervention, exercise prescription patients and general lifestyle counselling have been tested. Bariatric surgery is an option in the severely obese when nonsurgical measures have failed, and laparoscopic adjustable gastric banding and Roux-en-Y gastric bypass are the most commonly employed techniques in the United Kingdom. Most evidence for efficacy of surgery comes from cohort studies. The role of sibutramine in OSA in the obese patients has been investigated, however, there are concerns regarding associated cardiovascular risk. In this paper the links between obesity and OSA are discussed, and the recent studies evaluating the behavioural, pharmacological and surgical approaches to weight loss in OSA are reviewed.

Predicting sleep disordered breathing in outpatients with suspected OSA

Objective To validate the utilities of Berlin, STOP and STOP-BANG Questionnaires, other patient characteristics, comorbidities, Epworth Sleepiness Scale (ESS), fractional exhaled nitric oxide (FENO) and blood markers for the prediction of sleep disordered breathing (SDB) on limited polygraphy. Setting North Glasgow Sleep Service (a tertiary referral centre). Participants 129 consecutive patients, aged ≥16 years, referred to the sleep clinic for assessment of possible obstructive sleep apnoea. Interventions We selected cut-points of apnoea hypopnoea index (AHI) of ≥5 and ≥15/h from their home polygraphy and determined associations of these with individual symptoms, questionnaire scores and other results. Receiver operating characteristic analysis and univariate and multivariate logistic regression were used to explore these. Primary and secondary outcomes measures Primary: The utility of STOP, STOP-BANG and Berlin Questionnaires for prediction of SDB. Secondary: The utility of other measures for prediction of SDB. Results AHI was ≥5 in 97 patients and ≥15 in 56 patients. STOP and STOP-BANG scores were associated with both AHI cut-points but results with ESS and Berlin Questionnaire scores were negative. STOP-BANG had a negative predictive value 1.00 (0.77–1.00) for an AHI ≥15 with a score ≥3 predicting AHI ≥5 with sensitivity 0.93 (95% CI 0.84 to 0.98) and accuracy 79%, while a score ≥6 predicted AHI ≥15 with specificity 0.78 (0.65 to 0.88) and accuracy 72%. Neck circumference ≥17 inch and presence of witnessed apnoeas were independent predictors of SDB. Conclusions STOP and STOP-BANG Questionnaires have utility for the prediction of SDB in the sleep clinic population. Modification of the STOP-BANG Questionnaire merits further study in this and other patient groups.

Exercise-induced wheeze: Fraction of exhaled nitric oxide-directed management

Background and objective:  Exercise‐induced wheeze (EIW) is common. Several treatment options exist. Patients with low fraction of exhaled nitric oxide (FENO) are unlikely to be steroid‐responsive and might benefit from non‐steroidal therapies. We assessed: the efficacy of cromoglycate, formoterol and montelukast in patients with EIW and low FENO (<35 ppb) in a randomized cross‐over trial, and the efficacy of inhaled corticosteroid in a high FENO (>35 ppb) group.

Sputum mast cell subtypes relate to eosinophilia and corticosteroid response in asthma.

Mast cells are a resident inflammatory cell of the airways, involved in both the innate and adaptive immune response. The relationship between mast cells and inflammatory phenotypes and treatment response of asthma is not clear. Clinical characteristics of subjects with stable asthma (n=55), inflammatory cell counts and gene expression microarrays in induced sputum were analysed. Sputum mast cell subtypes were determined by molecular phenotyping based on expression of mast cell biomarkers (tryptase (TPSAB1), chymase (CMA1) and carboxypeptidase A3 (CPA3)). Effects of mast cell subtypes on steroid response were observed in a prospective cohort study (n=50). MCT (n=18) and MCT/CPA3 (mRNA expression of TPSAB1 and CPA3; n=29) subtypes were identified, as well as a group without mast cell gene expression (n=8). The MCT/CPA3 subtype had elevated exhaled nitric oxide fraction, sputum eosinophils, bronchial sensitivity and reactivity, and poorer asthma control. This was accompanied by upregulation of 13 genes. Multivariable logistic regression identified CPA3 (OR 1.21, p=0.004) rather than TPSAB1 (OR 0.92, p=0.502) as a determinant of eosinophilic asthma. The MCT/CPA3 subtype had a better clinical response and reduced signature gene expression with corticosteroid treatment. Sputum mast cell subtypes of asthma can be defined by a molecular phenotyping approach. The MCT/CPA3 subtype demonstrated increased bronchial sensitivity and reactivity, and signature gene expression, which was associated with airway eosinophilia and greater corticosteroid responsiveness. Mast cell subtypes detected in sputum relate to eosinophilic inflammation and treatment responsiveness in asthma http://ow.ly/UsEIE