Observational study of the natural history of eosinophilic bronchitis

Narrative Review: how long should patients with cough variant asthma or non-asthmatic eosinophilic bronchitis be treated?

The causes of chronic cough can be categorized into eosinophilic and noneosinophilic disorders, and approximately 30% to 50% of people with chronic cough have eosinophilic airway inflammation, the presence of which can be confirmed by sputum eosinophilia or elevated exhaled nitric-oxide levels. Cough variant asthma (CVA) is a phenotype of asthma which lacks wheezing or dyspnea, and consistently one of the most common causes of chronic cough worldwide. CVA and non-asthmatic eosinophilic bronchitis (NAEB) shares common feature such as chronic dry cough, eosinophilic inflammation, and development of chronic airflow obstruction (CAO) and asthma in a subset of patients. The distinctive characteristic of these conditions is the presence of airway hyperresponsiveness in CVA but not in NAEB. Coughing is responsive to bronchodilators such as beta-agonists in CVA, but such feature has not been clarified in NAEB. Inhaled corticosteroids (ICSs) are the first-line treatment, and leukotriene receptor antagonists are also effective, in patients with both CVA and NAEB. This review will give an outline of clinical and physiological features, and prognosis and its determinants of CVA and EBNA. Further, the rationale and evidence, despite limited, for the need of long-term treatment will be discussed. The development of airway remodeling due to mechanical stress to the airways exerted by long-standing coughing will also be discussed.

Characterization of Occupational Eosinophilic Bronchitis in a Multicenter Cohort of Subjects with Work-Related Asthma Symptoms

BACKGROUND

Occupational eosinophilic bronchitis (OEB) has been described only as anecdotal case reports.

OBJECTIVE

We investigated the clinical and inflammatory characteristics of subjects with OEB identified in a cohort of subjects who completed a specific inhalation challenge (SIC) with occupational agents.

METHODS

In this retrospective multicenter study, OEB was defined by (1) a fall in FEV1 less than 15% during the SIC and the absence of nonspecific bronchial hyperresponsiveness both before and after the SIC and (2) a postchallenge increase of 3% or more in sputum eosinophils. The subjects who fulfilled these criteria were compared with 226 subjects with a negative SIC and 30 subjects with a positive SIC who failed to show baseline nonspecific bronchial hyperresponsiveness.

RESULTS

An isolated increase in postchallenge sputum eosinophils was documented in 33 of 259 subjects (13%) with a negative SIC. These subjects reported significantly more often an isolated cough at work compared with the negative and positive SIC controls. When compared with positive SIC controls, the subjects with OEB experienced less frequently work-related wheezing and reported a shorter duration of symptoms at work. The sensitivity of the post-SIC increase in fractional exhaled nitric oxide in identifying OEB among subjects with a negative SIC was low, ranging from 43% to 24% using cutoff values of 8 ppb to 17.5 ppb, whereas the specificity was high (90%-97%).

CONCLUSIONS

This study highlights the relevance of induced sputum analysis in the investigation of work-related asthma symptoms to identify isolated increases in sputum eosinophils that are consistent with a diagnosis of OEB.

Cough and Eosinophilia

Eosinophilic airway inflammation is observed in 30% to 50% of chronic cough sufferers. It is a common feature of asthma and upper airway cough syndrome, and it is required in the diagnosis of nonasthmatic eosinophilic bronchitis. Our understanding of the mechanisms underlying allergic and nonallergic eosinophilic inflammation have evolved tremendously in the last 2 decades, but the cause of this inflammation in any individual is often uncertain. Inhaled corticosteroids are the mainstay therapy for cough due to asthma or nonasthmatic eosinophilic bronchitis, and response is related to the presence of biomarkers of eosinophilic airway inflammation. In upper airway cough syndrome, nasal topical corticosteroids are beneficial in allergic rhinitis and chronic rhinosinusitis with polyposis. This review will describe the diagnosis, current and possible future treatments, and prognosis of chronic cough in adults with eosinophilic inflammation.

Perspectives on chronic cough in Korea

Chronic cough is a common condition, and generally affects about 3% of Korean adults with a significant influence on quality of life (QoL). Despite continued clinical and academic efforts, there are unmet needs for chronic cough prevention and management in Korea. Epidemiologically, there are two major challenges: an aging population and air pollution. Korea is one of the most rapidly aging countries, and the relative proportion of elderly to younger people is expected to double within the next two decades. Air pollution is a major concern, but there is very limited evidence on the effects of air pollutant on cough in Korean patients. Clinically, upper and lower airway diseases, such as rhinitis/rhinosinusitis and cough variant asthma/eosinophilic bronchitis, are reported to account for about 75% of chronic cough in Korean adults, which formed the basis in formulating clinical practice guidelines. However, further studies are warranted to resolve clinical uncertainty, particularly for the evaluation and treatment of upper airway conditions in chronic cough. The prevalence of gastroesophageal reflux disease (GERD) is increasing, thus its relevance to cough among Koreans may warrant re-evaluation. Infection-associated chronic cough, such as tuberculosis, is another continuing concern. The proportion of chronic refractory or unexplained cough is assumed to be 10–20% among patients visiting referral clinics for chronic cough. This review presents our perspectives on current epidemiological and clinical issues of chronic cough in Korea, and addresses major knowledge gaps and future research priorities.

Duration of treatment with inhaled corticosteroids in nonasthmatic eosinophilic bronchitis: a randomized open label trial

BACKGROUND

Nonasthmatic eosinophilic bronchitis (NAEB) responds well to inhaled corticosteroids (ICS), while recurrence is common after discontinuing treatment. There are no data available to show whether treatment duration of ICS in patients with NAEB is related to recurrence. We aim to evaluate the effect of different duration of treatment with ICS on relapse of NAEB.

METHODS

A total of 101 patients with NAEB were recruited to the open label, randomized, parallel-group trial. Patients were randomized to receive 1-month, 2-month, or 4-month treatment with inhaled budesonide (200 μg, twice daily). Sputum induction, cough visual analogue scale (VAS), and cough symptom score (CSS) were conducted at baseline and after completion of treatment. The patients were followed up for 1 year after treatment. The primary outcome was the relapse rate of NAEB in 1 year.

RESULTS

ICS significantly decreased cough VAS, CSS, and sputum eosinophilia among these groups. There were no statistically significant between-group differences in cough VAS, CSS scores, and sputum eosinophil counts at the end of treatment, and no significant between-group differences in those changes from baseline to post-treatment. Significantly, more participants in the 1-month treatment group experienced a recurring episode of NAEB than those in the 3-month treatment group (41.9% versus 12.0%, p = 0.0137) at 1-year follow-up. The 2-month treatment group showed a lower tendency, with a relapse rate of 20.0% (p = 0.0644).

CONCLUSIONS

Our results suggest that inhaled corticosteroids should be administrated for at least 2 months to reduce the relapse of NAEB.

CLINICAL TRIAL REGISTRATION

The study was registered on ClinicalTrials.gov (NCT02002715). The reviews of this paper are available via the supplemental material section.

Managing Chronic Cough Due to Asthma and NAEB in Adults and Adolescents: CHEST Guideline and Expert Panel Report

BACKGROUND

Asthma and non-asthmatic eosinophilic bronchitis (NAEB) are among the commonest causes of chronic cough in adults. We sought to determine the role of non-invasive measurements of airway inflammation, including induced sputum and fractional exhaled nitric oxide, in the evaluation of cough associated with asthma, and what the best treatment is for cough due to asthma or NAEB.

METHODS

We undertook three systematic reviews of randomized controlled trials and observational trials of adults and adolescents > 12 years of age with a chronic cough due to asthma or NAEB. Eligible studies were identified in MEDLINE, CENTRAL, and SCOPUS and assessed for relevance and quality. Guidelines were developed and voted upon using CHEST guideline methodology.

RESULTS

Of the citations reviewed, 3/1,175, 53/656, and 6/134 were identified as being eligible for inclusion in the three systematic reviews, respectively. In contrast to established guidelines for asthma therapies in general and the inclusion in some guidelines for a role of biomarkers of airway inflammation to guide treatment in severe disease, the evidence of specific benefit related to the use of non-invasive biomarkers in patients with chronic cough due to asthma was weak. The best therapeutic option for cough in asthma or NAEB is inhaled corticosteroids followed by leukotriene receptor antagonism.

CONCLUSIONS

This guideline offers recommendations on the role of non-invasive measurements of airway inflammation and treatment for cough due to asthma or NAEB based on the available literature, and identifies gaps in knowledge and areas for future research.

Response to bronchodilator and clinical, pathophysiological features in patients with nonasthmatic eosinophilic bronchitis

INTRODUCTION

Whether nonasthmatic eosinophilic bronchitis (NAEB) shows response to bronchodilator (RB) remains unclear.

OBJECTIVES

To investigate the RB and its relationship with clinical and pathophysiological features in NAEB.

METHODS

Fifty-one patients with NAEB were assigned in a 2:1 ratio to receive oral bambuterol hydrochloride (n = 34, 10 mg, once daily, for 3 days) or matched placebo (n = 17) randomly, of whom 48 patients (32 with bronchodilator and 16 with placebo) completed the study. Sputum induction, spirometry and cough reflex sensitivity were measured. RB was considered when cough Visual analogue scale (VAS) score decreased 30% or more after treatment. Cough reflex sensitivity was defined as the lowest concentration of capsaicin inducing five coughings or more (C5), and presented as Log C5.

RESULTS

The responsive rate of patients with bronchodilator was significantly higher than that with placebo (34.4% vs 6.3%, P < 0.05). The VAS score decreased significantly in patients with bronchodilator (median: 6.0-3.0, P < 0.01). There was a significantly higher median Log C5 (2.7 vs 1.3, P < 0.05), and a higher trend of decline in FEV₁ % predicted and MMEF% predicted after bronchial provocation in patients with RB as compared with patients without RB. No significant differences in baseline percentages of sputum eosinophil were found between patients with RB and that without RB.

CONCLUSIONS

One third of patients with NAEB respond well to bronchodilator treatment, which are related with lower cough reflex sensitivity and increased airway responsiveness. The relationship between NAEB and asthma needs to be investigated further.

Chronic rhinosinusitis with nasal polyps: insights into mechanisms of disease from emerging biological therapies

Introduction: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex disease of the upper airway, with long-term morbidity. With detailed mechanistic studies currently lacking, understanding of the immunopathogenesis is still limited. However, outcomes from CRSwNP clinical studies using biologics that block key mediators or cells may provide some insights into how immune signaling pathways potentially integrate and modulate each other and contribute to disease. Current treatments are often ineffective and there is an urgent unmet clinical need for effective therapeutic strategies. Emerging biologics hold promise. Areas covered: This review covers the biology of CRSwNP in terms of the clinical outcomes reported from blocking immune cascades with available biologics. Immune amplification mechanisms and how biologics can potentially modulate such 'master' cytokines and signaling proteins that drive inflammation and contribute to tissue remodeling in CRSwNP are discussed. Expert commentary: Biologics have the potential to transform CRSwNP treatment. The ability to predict clinical response in a complex disease as CRSwNP to a biologic cannot necessarily be predicted by measuring a single protein or cell as a biomarker of disease. Further studies with biologics must be carefully undertaken to fully evaluate wider biomarker associated pheno-endotype responses along with any associated asthma outcome measures.

Clinical Outcome of Eosinophilic Airway Inflammation in Chronic Airway Diseases Including Nonasthmatic Eosinophilic Bronchitis

We enrolled patients with confirmed sputum eosinophilia who had visited our tertiary referral hospital between 2012 and 2015. We evaluated the incidence and predictors of exacerbations in patients with nonasthmatic eosinophilic bronchitis (NAEB), and investigated predictors of improvement in eosinophilic inflammation in chronic airway diseases with or without persistent airflow limitation. In total, 398 patients with sputum eosinophilia were enrolled. Of these, 152 (38.2%) had NAEB. The incidence rate of exacerbations requiring treatment with antibiotics, systemic corticosteroids, or hospital admission was 0.13 per patient-year (95% CI, 0.06-0.19) in NAEB. Inhaled corticosteroid (ICS) did not affect the risk of exacerbations, even in an analysis of propensity score. One hundred seventy-six patients had chronic airway diseases; in 37 of these (21.0%), sputum eosinophilia had improved at the 1-year follow-up. Patients who had persistent airflow limitation were less likely to show an improvement in eosinophilic inflammation (aOR, 0.26; 95% CI, 0.09-0.77) when they were treated with ICSs for less than 75% of the follow-up days. Exacerbations requiring systemic corticosteroids, antibiotics, or hospitalization did occur, although infrequently, in NAEB patients. Among patients with chronic airway diseases, those with persistent airflow limitation were less likely to show an improvement in eosinophilic airway inflammation.

Non-astmatic Eosinophilic Bronchitis

Non-asthmatic eosinophilic bronchitis (NAEB) is eosinophilic inflammation of the respiratory tract, without any bronchospasm. In this article, we want to draw attention to the NAEB. It should also be considered in differential diagnosis of chronic cough. Eosinophilia is present in all induced or spontaneous sputum samples of NAEB patients. NAEB patients and asthmatic patients have similar airway inflammation. Remarkably, NAEB mainly occurs in the lower airways. Unlike asthma, mast cells in NAEB are active in the bronchial epithelium. Diagnosis is based on the clinical, radiological, and spirometric measurements of other causes of chronic cough (Post-nasal discharge syndrome, asthma, gastroesophageal reflux etc.) and the assessment of inflammation in the lower respiratory tract. Airway inflammation can be assessed by sputum induction. The main treatment is anti-inflammatory therapy with inhaled corticosteroids and taking protective measures if inflammation is due to occupational exposure or allergen inhalation. If NAEB is untreated, it may be transient, episodic, or persistent; rarely, long-term oral steroid treatment may be required in patients. There is a requirement for studies that investigate the role of non-invasive markers of chronic inflammation associated with NAEB and the effectiveness of other treatments.

Characteristics of non-smoking adult asthma patients with chronic airflow limitation

OBJECTIVE

Chronic airflow limitation (CAL) can develop in a subgroup of patients with asthma. Characterising these patients is important because reduced lung function is a risk factor for adverse asthma outcomes. We hypothesised that heterogeneity in patients with CAL may be influenced by age at asthma onset. We first compared never-smoking asthma patients with and without CAL, and subsequently examined the differences between patients with late and early-onset asthma within the CAL cohort.

METHODS

Patients seen in our hospital's respiratory clinic between 1 Jan 2015 and 31 December 2015 were recruited to the study. CAL was defined as post-bronchodilator forced expiratory volume in 1 second (FEV1)<80% predicted, in the presence of post-bronchodilator ratio <70%. Variables independently associated with CAL were determined using a multivariate logistic regression model. Comparisons between patients with late-onset asthma (age ≥18 years) and early-onset asthma were made within the CAL cohort.

RESULTS

247 patients were included in the study. Age was the only variable independently associated with CAL after regression analysis, with an increase in odds of 3.8% (95% CI 0.4-7.3%) for every 1 year increase in age, p = 0.027. 63.2% of patients with CAL had late-onset asthma. Compared to patients with early-onset asthma, those with late-onset asthma had higher fractional exhaled nitric oxide levels (43 ± 32 ppb vs 20 ± 8 pb, p = 0.008).

CONCLUSIONS

An increase in age is associated with CAL in never-smoking asthma patients. In addition, age at asthma onset appears to influence airway inflammation in patients with CAL.

Causes of Chronic Cough in Non-smoking Patients

Chronic cough is a common medical problem. The aim of the study was to analyze chronic cough causes in non-smoking patients and to search for demographic factors associated with different cough reasons. The etiology of cough was determined by medical history, diagnostic tests and response to specific treatment. Patients with significant abnormalities in the chest radiograph or spirometry were not included. The study included 131 non-smoking patients; median age 54 years, 77 % female. The most frequent causes of cough were gastroesophageal reflux disease (GERD) (62 %) and upper airway cough syndrome (UACS) (46 %). Cough variant asthma and non-asthmatic eosinophilic bronchitis (NAEB) were diagnosed in 32 (25 %) and 19 (15 %) patients, respectively. Other cough causes were found in 27 patients (21 %). Asthma was a significantly more common cause of chronic cough in women than in men (31 % vs. 3 %, p = 0.005). A reverse relationship was demonstrated for UACS (39 % vs. 67 %, p = 0.01). Patients with chronic cough aged >50 yrs were more likely to be diagnosed with less common cough causes. In conclusion, the most common chronic cough reasons are GERD and UACS. Asthma-related cough is diagnosed more frequently in females, while UACS-related cough is more frequent in males.

Will nonasthmatic eosinophilic bronchitis develop into chronic airway obstruction?: a prospective, observational study

OBJECTIVE

The long-term prognosis of nonasthmatic eosinophilic bronchitis (NAEB) is still unclear. The aim of this study was to observe the frequency of relapse among patients with NAEB and the likelihood of NAEB developing into chronic airflow obstruction over time.

METHODS

Patients with NAEB were followed for at least 1 year between 2003 and 2013. During this period, we evaluated clinical symptoms, sputum eosinophil count, spirometry, and bronchial hyperresponsiveness. A linear mixed model was adopted to determine the relationship between time and lung function.

RESULTS

A total of 234 patients with NAEB were identified, of whom 141 were followed for > 1 year (median, 4.1 years). Up to 59.6% of patients had a relapse after treatment. Both allergic rhinitis (OR, 4.37; 95% CI, 1.049-18.203; P = .043) and sputum eosinophilia after 4 weeks of treatment with inhaled corticosteroids (OR, 9.493; 95% CI, 2.381-37.850; P = .001) were risk factors for relapse. Among the 141 patients, mild asthma developed in eight (5.7%). During the follow-up period, no progressive decline in FVC, FEV1, and FEV1/FVC were observed (P > .05). Although the proportion of small airway dysfunction (maximum midexpiratory flow [MMEF] < 65%) significantly increased at the last visit in all groups (all P < .05), only the relapse group showed an MMEF decline at the end of follow-up (P < .05) in the linear mixed model.

CONCLUSIONS

More than 50% of patients with NAEB have repeated episodes associated with persistent sputum eosinophilia after treatment and allergic rhinitis. In the current cohort, chronic airway obstruction does not develop despite small airway dysfunction increases over time.

Efficacy of add-on montelukast in nonasthmatic eosinophilic bronchitis: the additive effect on airway inflammation, cough and life quality

Background:

The efficacy of montelukast (MONT), a cysteinyl leukotriene receptor antagonist, in nonasthmatic eosinophilic bronchitis (NAEB), especially its influence on cough associated life quality is still indefinite. We evaluated the efficacy of MONT combined with budesonide (BUD) as compared to BUD monotherapy in improving life quality, suppressing airway eosinophilia and cough remission in NAEB.

Methods:

A prospective, open-labeled, multicenter, randomized controlled trial was conducted. Patients with NAEB (aged 18-75 years) were randomized to inhaled BUD (200 μg, bid) or BUD plus oral MONT (10 μg, qn) for 4 weeks. Leicester cough questionnaire (LCQ) life quality scores, cough visual analog scale (CVAS) scores, eosinophil differential ratio (Eos), and eosinophil cationic protein (ECP) in induced sputum were monitored and compared.

Results:

The control and MONT groups contained 33 and 32 patients, respectively, with similar baseline characteristics. Significant with-in group improvement in CVAS, LCQ scores, Eos, and ECP was observed in both groups during treatment. After 2-week treatment, add-on treatment of MONT was significantly more effective than BUD monotherapy for CVAS decrease and LCQ scores improvement (both P < 0.05). Similar results were seen at 4-week assessment (both P < 0.05). 4-week add-on therapy of MONT also resulted in a higher percentage of patients with normal sputum Eos (<2.5%) and greater decrease of ECP (both P < 0.05).

Conclusions:

MONT combined with BUD was demonstrated cooperative effects in improvement of life quality, suppression of eosinophilic inflammation, and cough remission in patients with NAEB.

Chronic cough - assessment of treatment efficacy based on two questionnaires

INTRODUCTION

Efficacy of chronic cough treatment is ambiguous. The aim of the study was to analyze chronic cough alleviation after specific treatment and the relationship between cough etiology and treatment efficacy.

MATERIAL AND METHODS

A stepwise diagnostic approach was used to diagnose cough etiology in non-smoking adults with chronic cough. In all patients specific treatment was applied. Two different questionnaires - a visual analog scale and a 5-degree scale - were used to assess cough severity before and after 4-6 months of treatment.

RESULTS

A significant correlation between pre-treatment and post-treatment results of both questionnaires was found (Spearman coefficient 0.43, p = 0.0003 and 0.73, p < 0.0001, respectively). Baseline questionnaire analysis revealed no differences in cough severity between patients with different cough causes or multiple cough causes. Although specific treatment resulted in a significant decrease of cough severity in the entire group, only partial improvement was noted. According to the visual analogue scale, a decrease of cough severity by at least 50% was achieved only in 54.4% of patients (37/68). Similarly, satisfactory improvement was noted in only 54.4% (37/68) of patients when using the 5-point scale. There were three sub-groups of patients, in whom no relevant decrease of cough severity was observed despite treatment: patients with 1. three coexisting cough causes, 2. non-asthmatic eosinophilic bronchitis, and 3. chronic idiopathic cough.

CONCLUSIONS

Cough severity does not depend on its etiology. Efficacy of chronic cough treatment in non-smoking patients is only moderate.

Expert opinion on the cough hypersensitivity syndrome in respiratory medicine

In 2011, a European Respiratory Society Task Force embarked on a process to determine the position and clinical relevance of the cough hypersensitivity syndrome, a disorder characterised by troublesome coughing often triggered by low levels of thermal, mechanical or chemical exposure, in the management of patients with chronic cough. A 21-component questionnaire was developed by an iterative process supported by a literature review. 44 key opinion leaders in respiratory medicine were selected and interviewed as to their opinions. There was a high degree of unanimity in the responses obtained, with all opinion leaders supporting the concept of cough hypersensitivity as a clinically useful paradigm. The classic stratification of cough into asthmatic, rhinitic and reflux-related phenotypes was supported. Significant disparity of opinion was seen in the response to two questions concerning the therapy of chronic cough. First, the role of acid suppression in reflux cough was questioned. Secondly, the opinion leaders were split as to whether a trial of oral steroids was indicated to establish a diagnosis of eosinophilic cough. The cough hypersensitivity syndrome was clearly endorsed by the opinion leaders as a valid and useful concept. They considered that support of patients with chronic cough was inadequate and the Task Force recommends that further work is urgently required in this neglected area.

Chronic cough: an update

Cough persisting beyond 8 weeks (ie, chronic cough) is one of the most common reasons for an outpatient visit. A protracted cough can negatively affect one's quality of life by causing anxiety, physical discomfort, social isolation, and personal embarrassment. Herein, the anatomy and physiology of the cough reflex are reviewed. Upper airway cough syndrome, asthma, eosinophilic bronchitis, and gastroesophageal reflux disease account for most chronic cough after excluding smoking, angiotensin-converting enzyme inhibitor use, and chronic bronchitis. Many patients have more than one reason for chronic cough. Treating the underlying cause(s) resolves cough in most instances. There are some coughs that seem refractory despite an extensive work-up. The possibility of a hypersensitive cough reflex response has been proposed to explain these cases. Several clinical algorithms to evaluate chronic cough are presented.

Re-challenge with ovalbumin failed to induce bronchial asthma in mice with eosinophilic bronchitis

OBJECTIVE

To investigate whether eosinophilic bronchitis without airway hyperresponsiveness will develop bronchial asthma in allergic mice.

METHODS

Mice were sensitized with OVA on days 0, 7, and 14, challenged on days 21 to 23 (1(st) OVA challenge), and re-challenged on days 46 to 48 (2(nd) OVA challenge), intranasally with 10 (the EB group) and 200 (the AS group) μg OVA. Lung resistance (RL) was assessed 24 h after each challenge and on day 45 followed by analysis of leukocyte distribution in the bronchoalveolar lavage (BAL) fluid and histological examination.

RESULTS

Twenty-four hours after the 1(st) OVA challenge, aerosolized methacholine caused a dose-dependent increase in RL in all groups. At doses ≥1.56 mg/mL, RL in the AS group was significantly higher than that of the NS-1 group (P<0.01 or 0.05) and at doses ≥12.5 mg/mL, RL was markedly higher in the AS group than that of the EB group (P<0.01). The percentage of eosinophils in both the EB group and the AS group was markedly higher than that of the control group. Twenty-four hours after the 2(nd) OVA challenge, at doses ≤12.5 mg/mL, there was no significant difference in RL among all groups (P>0.05). At doses ≥12.5 mg/mL, RL in the AS group was significantly higher than that of the control group and EB group (P<0.01 or 0.05). The percentage of eosinophils in the AS group was noticeably higher than that of the EB group(P<0.05). Furthermore, there was apparent infiltration by inflammatory cells, predominantly eosinophils, into the sub-epithelial region of the bronchus and the bronchioles and around the vessels in the EB and AS group.

CONCLUSION

Re-challenge with low doses of ovalbumin did not increase airway reactivity and failed to induce bronchial asthma in mice with ovalbumin-induced EB.

Eosinophils as diagnostic tools in chronic lung disease

Chronic lung diseases are very common and form a major threat to large proportions of the population with increased morbidity and mortality. Asthma is one of the most common eosinophilic airway diseases. However, there is growing evidence that eosinophilic inflammation is also important in subgroups of patients with chronic obstructive pulmonary disease, chronic cough and idiopathic pulmonary fibrosis. Several studies have shown that sputum eosinophilia is associated with a favorable response to treatment of corticosteroids in both asthma and chronic obstructive pulmonary disease, and tailored strategies aimed to normalize sputum eosinophils have resulted in a significant reduction in exacerbation rates. In this article, the authors review the role of eosinophilic inflammation in the diagnosis and management of chronic respiratory diseases.

Phenotyping airways disease: an A to E approach

The airway diseases asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous conditions with overlapping pathophysiological and clinical features. It has previously been proposed that this heterogeneity may be characterized in terms of five relatively independent domains labelled from A to E, namely airway hyperresponsiveness (AHR), bronchitis, cough reflex hypersensitivity, damage to the airways and surrounding lung parenchyma, and extrapulmonary factors. Airway hyperresponsiveness occurs in both asthma and COPD, accounting for variable day to day symptoms, although the mechanisms most likely differ between the two conditions. Bronchitis, or airway inflammation, may be predominantly eosinophilic or neutrophilic, with different treatments required for each. Cough reflex hypersensitivity is thought to underlie the chronic dry cough out of proportion to other symptoms that can occur in association with airways disease. Structural changes associated with airway disease (damage) include bronchial wall thickening, airway smooth muscle hypertrophy, bronchiectasis and emphysema. Finally, a variety of extrapulmonary factors may impact upon airway disease, including rhinosinusitis, gastroesophageal reflux disease, obesity and dysfunctional breathing. This article discusses the A to E concept in detail and describes how this framework may be used to assess and treat patients with airway diseases in the clinic.

Usefulness of impulse oscillometry and fractional exhaled nitric oxide in children with Eosinophilic bronchitis

BACKGROUND

Eosinophilic bronchitis (EB) is a common cause of chronic cough. Although EB shares many immunopathologic features with asthma, it does not show airway hyperresponsiveness or reversible airway obstruction by spirometry.

OBJECTIVE

Compared to healthy children without pulmonary disease, we hypothesized that EB patients would demonstrate abnormal pulmonary function and inflammation with impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO), which are more sensitive tests of these parameters than spirometry.

METHODS

A total of 232 children with asthma, 109 with EB, and 115 control subjects were enrolled. We compared pulmonary function parameters and FeNO levels among the three groups. Additionally, we designated a screening cutoff value of FeNO combined with IOS parameters to distinguish EB from the control group, and identify which children with EB have more asthmatic characteristics.

RESULTS

By IOS, the bronchodilator response of the EB and asthma groups increased significantly compared to controls for both reactance at 5 Hz (Δ X5) and reactance area (Δ AX) (P < 0.0001). Cutoff values to distinguish EB from controls were a Δ X5 of -20% (sensitivity, 77.5%; specificity, 49.6%), and Δ AX of -30% (sensitivity, 75.0%; specificity, 46.0%), when the FeNO is 20 ppb.

CONCLUSIONS

Reversible airway obstruction in IOS and elevated FeNO levels can be detected in children with EB. This would support that EB in children shows airway characteristics similar to those of asthma, and that a continuum exists between asthma and EB.

Classification of chronic cough by systematic treatment cascade trial starting with beta agonist

Background

Chronic cough is one of the most challenging symptoms to diagnose and treat, not only because of the variety of underlying disorders but also its varying susceptibility to treatments. Etiological studies of chronic cough vary depending on the clinical settings and the particular interests of investigators.

Objectives

The purposes of this study were first to categorize the etiology of chronic cough by its response to systematic diagnostic treatments starting from the β₂ agonist and second to sub-categorize β₂ agonist responsive cough (BRC) by the airway hyperresponsiveness.

Methods

One hundred and eighty-four never-smokers received the maximal dose of procaterol to diagnose BRC. BRC was sub-categorized into two groups with or without airway hyperresponsiveness measured by the methacholine challenge test. Sinobronchial syndrome (SBS) was diagnosed by postnasal drip symptoms and by the response to clarythromycin and carbocysteine. Atopic cough (AC) was diagnosed by the evidence of atopy and the response to cetirizine hydrochloride. Gastroesophageal reflux disease (GERD) was diagnosed by the response to rabeprazole sodium. Since we did not investigate eosinophil counts in the tissue or in the induced sputum, no diagnosis of eosinophilic bronchitis was made.

Results

One hundred and nine patients had BRC. Twenty-three of them had bronchial asthma (BA), 53 had cough variant asthma (CVA) and 33 had non-hyperresponsive BRC (NHBRC). Thirty-one patients had GERD, 27 had AC and 14 had SBS. Twenty-five patients had more than one diagnosis in combination, while 6 had other miscellaneous diseases. Twelve patients were undiagnosed and 11 dropped out of the study.

Conclusions

The majority of chronic cough was BRC. NHBRC was a new chronic cough entity. GERD is a common cause of chronic cough in Japan, as in Western countries. AC and SBS are also causes of chronic cough in Japan.

Trial registration

University hospital medical information network (UMIN 000007483)

Add-on montelukast vs double-dose budesonide in nonasthmatic eosinophilic bronchitis: a pilot study

BACKGROUND

Budesonide at 800 μg/d is generally suggested for treatment of nonasthmatic eosinophilic bronchitis (NAEB). In asthma, adjunctive therapy with montelukast has been shown to confer addictive anti-inflammatory effects to inhaled corticosteroid (ICS). However, whether such effects could be extrapolated to NAEB is not known.

OBJECTIVES

To study the efficacy and tolerability of add-on therapy with montelukast as compared to double-dose ICS in suppressing airway eosinophilia and decreasing cough severity in NAEB.

METHODS

In a randomized controlled trial, 26 nonsmoking, steroid-naïve NAEB patients presenting with chronic cough were treated with 800 μg/d budesonide or 400 μg/d budesonide plus montelukast 10 mg/d for 4 weeks. Cough visual analogue scale (CVAS) and eosinophil differential ratio in induced sputum (Eos) were monitored at baseline, Week 1, 2 and 4. Adverse events during treatment were recorded.

RESULTS

The two groups were comparable in age, gender distribution, cough duration, FEV(1)% predicted, FEV(1)/FEV ratio, baseline CVAS and geometric mean of Eos. Both regimens significantly reduced Eos and CVAS throughout the treatment course, with abrogation of sputum eosinophilia at end of therapy. There was no significant difference between the two groups in reduction of Eos and CVAS at all time points. Both regimens were well tolerated.

CONCLUSIONS

This preliminary study demonstrated that add-on montelukast might be an effective and well tolerated alternative to the generally suggested dose of ICS in treating steroid-naive NAEB, with suppression of eosinophilic inflammation, reduction of cough severity and sparing of ICS doses. (NCT01121016).

Definitions and classification of work-related asthma

The workplace can trigger or induce asthma and cause the onset of different types of work-related asthma (WRA). Based on current knowledge of clinical features, pathophysiologic mechanisms, and evidence supporting a causal relationship, the following conditions should be distinguished in the spectrum of WRA: (1) immunologic occupational asthma (OA), (2) nonimmunologic OA, (3) work-exacerbated asthma, and (4) variant syndromes, including eosinophilic bronchitis, potroom asthma, and asthmalike disorders caused by organic dusts. The rationale, issues, and controversies relating to this approach are critically reviewed to stimulate the development of a consensus on operational definitions of the various phenotypes of WRA.

Cough: an unmet clinical need

Cough is among the most common complaints for which patients worldwide seek medical attention. Thus, the evaluation and treatment of cough result in tremendous financial expenditure and consumption of health care resources. Yet, despite the clinical significance of cough, research efforts aimed at improving diagnostic capabilities and developing more effective therapeutic agents have been, to date, disappointing in their limited scope and outcomes. Acute cough due to the common cold represents the most common type of cough. Currently, available medications for the symptomatic management of acute cough are inadequate due to lack of proven efficacy and/or their association with undesirable or intolerable side effects at anti-tussive doses. Subacute cough, often representing a prolonged post-viral response, is typically refractory to standard anti-tussive therapy. Few clinical trials have evaluated therapeutic options for subacute cough. Diagnostic challenges facing the clinician in the management of chronic cough include the determination of whether symptoms of upper airway cough syndrome (formerly, postnasal drip syndrome) or gastro-oesophageal reflux disease are indeed the underlying cause of cough. Chronic, refractory unexplained (formerly, idiopathic) cough must be distinguished from cough that has not been fully evaluated and treated according to current guideline recommendations. Eagerly awaited are new safe and effective anti-tussive agents for use when cough suppression is desired, regardless of underlying aetiology of cough, as well as practical, validated ambulatory cough counters to aid clinical assessment and future research in the field of cough.

Cough and Asthma

Cough is the most common complaint for which patients seek medical attention. Cough variant asthma (CVA) is a form of asthma, which presents solely with cough. CVA is one of the most common causes of chronic cough. More importantly, 30 to 40% of adult patients with CVA, unless adequately treated, may progress to classic asthma. CVA shares a number of pathophysiological features with classic asthma such as atopy, airway hyper-responsiveness, eosinophilic airway inflammation and various features of airway remodeling. Inhaled corticosteroids remain the most important form of treatment of CVA as they improve cough and reduce the risk of progression to classic asthma most likely through their prevention of airway remodeling and chronic airflow obstruction.

Eosinophils, bronchitis and asthma: pathogenesis of cough and airflow obstruction

Eosinophilic airway inflammation is commonly observed in chronic cough in patients with asthma and non-asthmatic eosinophilic bronchitis. Indeed asthma and non-asthmatic eosinophilic bronchitis are amongst the commonest causes of chronic cough accounting for about 25 and 10% of cases respectively. In most cases the trigger that causes the cough is uncertain; however removal of potential triggers is important to consider in particular with respect to occupational exposure to known sensitizers. In both conditions the cough improves subjectively and objectively following treatment with corticosteroids. This improvement is associated with the presence of an airway eosinophilia, but whether eosinophilic inflammation is the cause of cough or an epiphenomenon is uncertain. The success of anti-IL5 to reduce eosinophilic inflammation and asthma exacerbations contrasts with the lack of efficacy to modify cough in asthma and therefore challenges a causal association. Both asthma and non-asthmatic eosinophilic bronchitis can lead onto airway remodeling and result in persistent airflow obstruction. However, response to corticosteroid therapy in both conditions is generally very good and the limited long term data available suggests that both usually have a benign course. Interestingly, improvement in airway remodeling in response to anti-IL5 observed using CT imaging and analysis of sub-epithelial matrix deposition does suggest that the eosinophil may play a causal role in airway remodeling.

Chronic cough: Stepwise application in primary care practice of the ACCP guidelines for diagnosis and management of cough

PURPOSE

To illustrate decision points encountered when using evidence-based guidelines for diagnosis and management of chronic cough by means of a composite case study based on primary care practice.

DATA SOURCE

The American College of Chest Physicians (ACCP) Evidence-Based Clinical Practice Guidelines for Diagnosis and Management of Cough, and review of the scientific literature on cough and related topics.

CONCLUSIONS

The ACCP guidelines offer a systematic approach that uses trials of empirical therapies to diagnose and resolve the very common, often perplexing complaint of chronic cough. The major diagnoses reached are upper airway cough syndrome, cough-variant asthma, gastroesophageal reflux disease, and nonasthmatic eosinophilic bronchitis.

IMPLICATIONS FOR PRACTICE

Cough is the most common reason that patients seek an office visit. Many coughs resolve spontaneously, but coughs that persist significantly impair the quality of life. Use of the ACCP guidelines allows a stepwise empirical approach to the problem of unexplained chronic cough. This approach greatly increases the percentage of chronic coughs that are accurately diagnosed and effectively treated, and avoids unnecessary diagnostic testing.

Antitussive effects of the leukotriene receptor antagonist montelukast in patients with cough variant asthma and atopic cough

BACKGROUND

Chronic cough is the only symptom of cough variant asthma (CVA) and atopic cough (AC). Cysteinyl leukotriene receptor antagonists have been shown to be effective in CVA, but there are no reports on their effectiveness in AC. To evaluate the antitussive effect of montelukast, a leukotriene receptor antagonist, in CVA and AC.

METHODS

Seventy-five patients with chronic cough received diagnostic bronchodilator therapy with oral clenbuterol hydrochloride for 6 days. Of the 75 patients, 48 and 27 met the simplified diagnostic criteria for CVA and AC, respectively. Patients with CVA were randomly divided into 3 groups: montelukast, clenbuterol, and montelukast plus clenbuterol. Patients with AC were randomly divided into 2 groups: montelukast and placebo. The efficacy of cough treatment was assessed with a subjective cough symptom scale (0 meant "no cough" and 10 denoted "cough as bad as at first visit"). The cough scale, pulmonary function test, and peak expiratory flow rate (PEF) were evaluated before and after 2 weeks of treatment.

RESULTS

In patients with CVA, 2-week treatment with montelukast, clenbuterol, and montelukast plus clenbuterol all significantly decreased cough scores and treatment with montelukast plus clenbuterol was superior to treatment with montelukast alone. In the montelukast plus clenbuterol group, PEF values in the morning and evening significantly increased after 2 weeks compared with values before treatment. In patients with AC, scores on the cough scale did not differ significantly between the montelukast group and the placebo group.

CONCLUSIONS

Montelukast was confirmed to suppress chronic non-productive cough in CVA, whereas it was not effective in non-productive cough in AC.

Cough due to asthma, cough-variant asthma and non-asthmatic eosinophilic bronchitis

Among the most common causes of chronic cough are asthma (25%) and nonasthmatic eosinophilic bronchitis (10%). In asthma, cough may present as an isolated symptom, in which case it is known as cough variant asthma. Variable airflow obstruction and airway hyper-responsiveness are cardinal features of asthma, which are absent in nonasthmatic eosinophilic bronchitis. The presence of eosinophilic airway inflammation is a common feature of asthma and is a diagnostic criterion for nonasthmatic eosinophilic bronchitis. At a cellular level, mast cell infiltration into the airway smooth muscle bundle, narrowing of the airway wall, and increased interleukin-13 expression are features of asthma and not nonasthmatic eosinophilic bronchitis. In most cases, the trigger that causes the cough is uncertain, but occasionally occupational exposure to a sensitizer is identified, and avoidance is recommended. In both conditions, there is improvement following treatment with inhaled corticosteroids, which is associated with the presence of an airway eosinophilia and increased exhaled nitric oxide. Generally, response to therapy in both conditions is very good, and the limited long-term data available suggest that both usually have a benign course, although in some cases fixed airflow obstruction may occur.

Cough: a worldwide problem

Cough is a common and important respiratory symptom that can produce significant complications for patients and be a diagnostic challenge for physicians. An organized approach to evaluating cough begins with classifying it as acute, subacute, or chronic in duration. Acute cough lasting less than 3 weeks may indicate an acute underlying cardiorespiratory disorder but is most commonly caused by a self-limited viral upper respiratory tract infection (eg, common cold). Subacute cough lasting 3 to 8 weeks commonly has a postinfectious origin; among the causes, Bordetella pertussis infection should be included in the differential diagnosis. Chronic cough lasts longer than 8 weeks. When a patient is a nonsmoker, is not taking an angiotensin-converting enzyme inhibitor, and has a normal or near-normal chest radiograph, chronic cough is most commonly caused by upper airway cough syndrome, asthma, nonasthmatic eosinophilic bronchitis, or gastroesophageal reflux disease alone or in combination.

Noninvasive methods for assessment of airway inflammation in occupational settings

The present document is a consensus statement reached by a panel of experts on noninvasive methods for assessment of airway inflammation in the investigation of occupational respiratory diseases, such as occupational rhinitis, occupational asthma, and nonasthmatic eosinophilic bronchitis. Both the upper and the lower airway inflammation have been reviewed and appraised reinforcing the concept of 'united airway disease' in the occupational settings. The most widely used noninvasive methods to assess bronchial inflammation are covered: induced sputum, fractional exhaled nitric oxide (FeNO) concentration, and exhaled breath condensate. Nasal inflammation may be assessed by noninvasive approaches such as nasal cytology and nasal lavage, which provide information on different aspects of inflammatory processes (cellular vs mediators). Key messages and suggestions on the use of noninvasive methods for assessment of airway inflammation in the investigation and diagnosis of occupational airway diseases are issued.

Dyspnea and wheezing after adenosine injection in a patient with eosinophilic bronchitis

A 58-year-old nonsmoker female was referred for evaluation of chronic cough of 13 months duration. After an initial work-up, the patient was diagnosed to have chronic cough due to eosinophilic bronchitis. The diagnostic work-up for eosinophilic bronchitis and bronchial biopsy is discussed. Eosinophilic bronchitis is differentiated from asthma. In addition, the patient developed dyspnea, flushing, and wheezing after the administration of adenosine during a cardiac stress test in spite of a negative methacholine challenge. This indirect stimulus of airway hyperresponsiveness suggests the possible involvement of mast cells in eosinophilic bronchitis.

Cough due to asthma and nonasthmatic eosinophilic bronchitis

Asthma and nonasthmatic eosinophilic bronchitis are among the most common causes of chronic cough, accounting for about 25 and 10% of cases, respectively. Chronic cough due to asthma may present in isolation in which case it is known as cough-variant asthma. Nonasthmatic eosinophilic bronchitis is characterized by the presence of eosinophilic airway inflammation in the absence of variable airflow obstruction or airway hyperresponsiveness. Both conditions share many immunopathological features with the exceptions to date of mast cell infiltration into the airway smooth muscle, increased IL-13 expression, and narrowing and thickening of the airway wall, which are features reserved to asthma. In most cases the trigger that causes the cough is uncertain. However, removal of potential triggers is important to consider, in particular with respect to occupational exposure to known sensitisers. In both conditions there is subjective and objective improvement following treatment with inhaled corticosteroids, which is associated with the presence of an airway eosinophilia. Whether eosinophilic inflammation is the cause of cough or an epiphenomenon is uncertain, but the failure of anti-IL-5 to modify cough in asthma has questioned a causal association. In asthma, beta-agonist theophylline, leukotriene receptor antagonist, and oral corticosteroid therapy improve cough. In noneosinophilic bronchitis, some patients require oral corticosteroids but the benefit of other additional therapies is unknown. In general, response to therapy in both conditions is very good and the limited long-term data available suggest that both usually have a benign course, although in some cases persistent airflow obstruction may occur.

Airway wall geometry in asthma and nonasthmatic eosinophilic bronchitis

BACKGROUND

Variable airflow obstruction and airway hyperresponsiveness (AHR) are features of asthma, which are absent in nonasthmatic eosinophilic bronchitis (EB). Airway remodelling is characteristic of both conditions suggesting that remodelling and airway dysfunction are disassociated, but whether the airway geometry differs between asthma and nonasthmatic EB is uncertain.

METHODS

We assessed airway geometry by computed tomography (CT) imaging in asthma vs EB. A total of 12 subjects with mild-moderate asthma, 14 subjects with refractory asthma, 10 subjects with EB and 11 healthy volunteers were recruited. Subjects had a narrow collimation (0.75 mm) CT scan from the aortic arch to the carina to capture the right upper lobe apical segmental bronchus (RB1). In subjects with asthma and EB, CT scans were performed before and after a 2-week course of oral prednisolone (0.5 mg/kg).

RESULTS

Mild-moderate and refractory asthma were associated with RB1 wall thickening in contrast to subjects with nonasthmatic EB who had maintained RB1 patency without wall thickening [mean (SD) % wall area and luminal area mild-t0-moderate asthma 67.7 (7.3)% and 6.6 (2.8) mm(2)/m(2), refractory asthma 67.3 (5.6)% and 6.7 (3.4) mm(2)/m(2), healthy control group 59.7 (6.3)% and 8.7 (3.8) mm(2)/m(2), EB 61.4 (7.8)% and 11.1 (4.6) mm(2)/m(2) respectively; P < 0.05]. Airway wall thickening of non-RB1 airways generation three to six was a feature of asthma only. There was no change in airway geometry of RB1 after prednisolone. Proximal airway wall thickening was associated with AHR in asthma (r = -0.56; P = 0.02).

CONCLUSIONS

Maintained airway patency in EB may protect against the development of AHR, whereas airway wall thickening may promote AHR in asthma.

Eosinophilic airway disorders associated with chronic cough

Chronic cough is a major clinical problem. The causes of chronic cough can be categorized into eosinophilic and noneosinophilic disorders, the former being comprised of asthma, cough variant asthma (CVA), atopic cough (AC) and non-asthmatic eosinophilic bronchitis (NAEB). Cough is one of the major symptoms of asthma. Cough in asthma can be classified into three categories; 1) CVA: asthma presenting solely with coughing, 2) cough-predominant asthma: asthma predominantly presenting with coughing but also with dyspnea and/or wheezing, and 3) cough remaining after treatment with inhaled corticosteroid (ICS) and beta2-agonists in patients with classical asthma, despite control of other symptoms. There may be two subtypes in the last category; one is cough responsive to anti-mediator drugs such as leukotriene receptor antagonists and histamine H1 receptor antagonists, and the other is cough due to co-morbid conditions such as gastroesophageal reflux. CVA is one of the commonest causes of chronic isolated cough. It shares a number of pathophysiological features with classical asthma with wheezing such as atopy, airway hyperresponsiveness (AHR), eosinophilic airway inflammation and various features of airway remodeling. One third of adult patients may develop wheezing and progress to classical asthma. As established in classical asthma, ICS is considered the first-line treatment, which improves cough and may also reduce the risk of progression to classical asthma. AC proposed by Fujimura et al. presents with bronchodilator-resistant dry cough associated with an atopic constitution. It involves eosinophilic tracheobronchitis and cough hypersensitivity and responds to ICS treatment, while lacking in AHR and variable airflow obstruction. These features are shared by non-asthmatic eosinophilic bronchitis (NAEB). However, atopic cough does not involve bronchoalveolar eosinophilia, has no evidence of airway remodeling, and rarely progresses to classical asthma, unlike CVA and NAEB. Histamine H1 antagonists are effective in atopic cough, but their efficacy in NAEB is unknown. AHR of NAEB may improve with ICS within the normal range. Taken together, NAEB significantly overlaps with atopic cough, but might also include milder cases of CVA with very modest AHR. The similarity and difference of these related entities presenting with chronic cough and characterized by airway eosinophilia will be discussed.

Chronic cough – occupational considerations

Chronic cough is a common symptom in a wide range of respiratory conditions, and may also occur as a result of upper airway or gastro-esophageal problems. Whilst chronic cough of any cause may be exacerbated by work, in some cases it has a direct occupational cause, resulting from a harmful acute or chronic workplace exposure. Such occupational conditions may only be suspected by taking a detailed occupational history, and directly asking employed patients whether their cough improves away from work. Early and accurate diagnosis, linked with tailored drug therapy, modification of workplace exposures, and expert compensation advice is likely to offer the best outcome for this group of patients.

Exhaled nitric oxide levels in patients with atopic cough and cough variant asthma

BACKGROUND AND OBJECTIVE

Atopic cough (AC) is an established clinical entity in Japan, in which patients present with a chronic persistent non-productive cough. Exhaled nitric oxide (NO) is a biomarker of eosinophilic airway inflammation. The present study examined whether exhaled NO levels were increased in AC in comparison with cough variant asthma (CVA) and bronchial asthma (BA).

METHODS

Consecutive patients presenting with an isolated cough lasting at least 8 weeks were enrolled in the study. The aetiology of the chronic cough was determined according to the Japanese Respiratory Society guidelines for management of cough. Exhaled NO, capsaicin cough sensitivity (capsaicin concentration eliciting five or more coughs (C5)) and bronchial reversibility were measured at the patients' first visit. Bronchial responsiveness (PC20 to methacholine) was measured at their second visit following a 6-day course of bronchodilator therapy.

RESULTS

There were 58 patients recruited and fully investigated; of these 9 and 11 patients were diagnosed with AC and CVA, respectively, as single causes of chronic cough. Ten patients with BA who had not received corticosteroid therapy in the previous 4 weeks and who attended the same clinic in the same time period acted as controls. Exhaled NO levels in patients with AC were significantly lower than those in patients with CVA and BA. There was no significant difference in the exhaled NO levels between patients with CVA and BA.

CONCLUSIONS

Exhaled NO may reflect eosinophilic inflammation of peripheral airways and its measurement may be useful in differentiating CVA from AC and other causes of chronic non-productive cough.

Eosinophilic bronchitis-like lesion as the cause of death in a Macaca mulatta: a first case report

BACKGROUND

Eosinophilic bronchitis is a recently described, relatively benign condition in humans that is characterized by a corticosteroid-responsive chronic cough and sputum eosinophilia without the abnormalities of airway function seen in asthma. The exact cause of this condition is currently unknown, however has been associated with various occupational exposures in humans. It has also been reported to progress to irreversible airway obstruction. This disease has been reported in dogs and horses, but not in non-human primates.

METHODS

Gross examination of an otherwise healthy 13-year-old, colony-born Macaca mulatta, which died of severe non-responsive respiratory distress revealed that the lungs were markedly inflated and moist.

RESULTS

Hematoxylin and eosin-stained sections from the lungs contained widespread accumulation of eosinophils, sloughed epithelial cells, and mucus centered around bronchioles and adjacent airways. There was no evidence of mast cell infiltration of peribronchiolar smooth muscle, goblet cell hyperplasia, or basement membrane thickening.

CONCLUSIONS

This ruled out recurrent episodes as would be expected in asthma, favoring the diagnosis of an eosinophilic bronchitis-like lesion. We report a first case of eosinophilic bronchitis-like features in a M. mulatta.

Clinical usefulness of fractional exhaled nitric oxide for diagnosing prolonged cough

BACKGROUND

Prolonged cough is one of the troublesome symptoms commonly seen in daily practice. Especially, detection of allergic cough such as bronchial asthma (BA), cough variant asthma (CVA) and eosinophilic bronchitis without asthma (EB) is important because the prevalence of these disorders are high. We previously reported fractional exhaled nitric oxide (FeNO) can be a non-invasive marker of allergic airway inflammation. We examined whether FeNO could be applicable for the proper diagnosis of prolonged cough.

METHOD

About 71 consecutive subjects complaining prolonged cough who gave informed consent for the study were enrolled. FeNO, pulmonary function tests, bronchial hyperresponsiveness (BHR), IgE, and eosinophils in induced sputum and peripheral blood were measured. Final diagnosis of the subjects was 30 with BA, 18 with CVA, 8 with EB, and 15 with other respiratory disorders (Others).

RESULT

FeNO had significant correlations with non-specific IgE, mite-specific IgE, FEV/FVC, BHR, and eosinophils. The level of cedar-specific IgE was significantly higher in subjects with EB than CVA. FeNO levels in BA and CVA were significantly higher than those in EB and Others. The optimal cutoff level of FeNO was 38.8 ppb with sensitivity of 79.2% and specificity of 91.3% for distinguishing BA and CVA from EB and Others.

CONCLUSION

FeNO could be used as a diagnostic marker of prolonged cough, especially for the differential diagnosis BA and CVA from EB and others.

Eosinophilic bronchitis without asthma

BACKGROUND

Eosinophilic bronchitis without asthma causes chronic coughs without the physiologic features of asthma. The aim of this study was to review the clinical features, pathogenesis, diagnosis, treatment and prognosis of this condition.

METHODS

The current literature was reviewed using Pubmed for all studies published in the English language using the search term 'eosinophilic bronchitis'.

RESULTS

Eosinophilic bronchitis presents as normal spirometry, without evidence of airway hyperresponsiveness, and normal peak expiratory flow variability. When compared with asthma, mast cell recruitment to the superficial airways and mast cell activation appear to be a feature of eosinophilic bronchitis. In contrast, mast cell infiltration in the smooth muscle is significantly higher in asthma patients than in either eosinophilic bronchitis patients or healthy control subjects. In this condition, the absence of high IL-13 expression can contribute to the normal airway reactivity. The cough usually responds well to inhaled corticosteroids but dose and duration of treatment remain unclear. The condition can be transient, episodic or persistent unless treated, and occasionally, patients may require long-term treatment with oral corticosteroids.

CONCLUSIONS

The condition is an important cause of chronic coughs which are corticosteroid responsive. The study of eosinophilic bronchitis suggests that eosinophil-dependent mechanisms are generally not important in the pathogenesis of asthma.