Eosinophilic tracheobronchitis and airway cough hypersensitivity in chronic non-productive cough

Prevalence and causes of chronic cough in Japan

BACKGROUND

Chronic cough is one of the most common symptoms of respiratory diseases and can adversely affect patients' quality of life and interfere with social activities, resulting in a significant social burden. A survey is required to elucidate the frequency and treatment effect of chronic cough. However, clinical studies that cover all of Japan have not yet been conducted.

METHODS

Patients who presented with a cough that lasted longer than 8 weeks and visited the respiratory clinics or hospitals affiliated with the Japan Cough Society during the 2-year study period were registered.

RESULTS

A total of 379 patients were enrolled, and those who did not meet the definition of chronic cough were excluded. A total of 334 patients were analyzed: 201 patients had a single cause, and 113 patients had two or more causes. The main causative diseases were cough variant asthma in 92 patients, sinobronchial syndrome (SBS) in 36 patients, atopic cough in 31 patients, and gastroesophageal reflux (GER)-associated cough in 10 patients. The time required to treat undiagnosed patients and those with SBS was significantly longer and the treatment success rate for GER-associated cough was considerably poor.

CONCLUSIONS

We confirmed that the main causes of chronic cough were cough variant asthma, SBS, atopic cough, and their complications. We also showed that complicated GER-associated cough was more likely to become refractory. This is the first nationwide study in Japan of the causes and treatment effects of chronic cough.

A case of atopic cough with aphonia showed a prominent response to a histamine H1 receptor antagonist

A 33-year-old woman admitted to our hospital for further examination of severe non-productive cough lasting for about two months. Her symptom did not ameliorate by treatments including long acting β2 agonists. She had a medical history of drug allergy to non-steroidal anti-inflammatory drugs. At the initial visit, she could not speak at all and communicated with us in writing. Chest auscultation revealed no wheezes, rhonchi and other crackles. Laboratory findings showed a mild eosinophilia with normal total and specific serum immunoglobulin E. The results of an electrocardiogram, a chest X-ray and a chest CT were unremarkable. A fractional exhaled nitric oxide value was within normal limit. Based on these observations, a diagnosis of atopic cough (AC) was suspected, and we started treatment with a histamine H1 receptor antagonist (H1-RA). She had become able to speak again in association with complete disappearance of cough by eight-weeks after treatment initiation, and her symptoms did not recur even after cessation of treatment. By the confirmation of remarkable clinical improvement in response to a H1-RA, a diagnosis of AC was made. To the best of our knowledge, this is the first report of an AC patient who presented severe cough with aphonia. J. Med. Invest. 70 : 281-284, February, 2023.

WAO-ARIA consensus on chronic cough - Part II: Phenotypes and mechanisms of abnormal cough presentation - Updates in COVID-19

BACKGROUND

Chronic cough can be triggered by respiratory and non-respiratory tract illnesses originating mainly from the upper and lower airways, and the GI tract (ie, reflux). Recent findings suggest it can also be a prominent feature in obstructive sleep apnea (OSA), laryngeal hyperresponsiveness, and COVID-19. The classification of chronic cough is constantly updated but lacks clear definition. Epidemiological data on the prevalence of chronic cough are informative but highly variable. The underlying mechanism of chronic cough is a neurogenic inflammation of the cough reflex which becomes hypersensitive, thus the term hypersensitive cough reflex (HCR). A current challenge is to decipher how various infectious and inflammatory airway diseases and esophageal reflux, among others, modulate HCR.

OBJECTIVES

The World Allergy Organization/Allergic Rhinitis and its Impact on Asthma (WAO/ARIA) Joint Committee on Chronic Cough reviewed the current literature on classification, epidemiology, presenting features, and mechanistic pathways of chronic cough in airway- and reflux-related cough phenotypes, OSA, and COVID-19. The interplay of cough reflex sensitivity with other pathogenic mechanisms inherent to airway and reflux-related inflammatory conditions was also analyzed.

OUTCOMES

Currently, it is difficult to clearly ascertain true prevalence rates in epidemiological studies of chronic cough phenotypes. This is likely due to lack of standardized objective measures needed for cough classification and frequent coexistence of multi-organ cough origins. Notwithstanding, we emphasize the important role of HCR as a mechanistic trigger in airway- and reflux-related cough phenotypes. Other concomitant mechanisms can also modulate HCR, including type2/Th1/Th2 inflammation, presence or absence of deep inspiration-bronchoprotective reflex (lower airways), tissue remodeling, and likely cough plasticity, among others.

Differential features of chronic cough according to etiology and the simple decision tree for predicting causes

Finding etiology of chronic cough is an essential part of treatment. Although guidelines include many laboratory tests for diagnosis, these are not possible in many primary care centers. We aimed to identify the characteristics and the differences associated with its cause to develop a clinical prediction model. Adult subjects with chronic cough who completed both Korean version of the Leicester Cough Questionnaire (K-LCQ) and COugh Assessment Test (COAT) were enrolled. Clinical characteristics of each etiology were compared using features included in questionnaires. Decision tree models were built to classify the causes. A total of 246 subjects were included for analysis. Subjects with asthma including cough variant asthma (CVA) suffered from more severe cough in physical and psychological domains. Subjects with eosinophilic bronchitis (EB) presented less severe cough in physical domain. Those with gastro-esophageal reflux disease (GERD) displayed less severe cough in all 3 domains. In logistic regression, voice hoarseness was an independent feature of upper airway cough syndrome (UACS), whereas female sex, tiredness, and hypersensitivity to irritants were predictors of asthma/CVA; less hoarseness was a significant feature of EB, and feeling fed-up and hoarseness were less common characteristics of GERD. The decision tree was built to classify the causes and the accuracy was relatively high for both K-LCQ and COAT, except for UACS. Voice hoarseness, degree of tiredness, hypersensitivity to irritants and feeling fed-up are important features in determining the etiologies. The decision tree may further assists classifying the causes of chronic cough.

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.

The Japanese respiratory society guidelines for the management of cough and sputum (digest edition)

Cough and sputum are common complaints at outpatient visits. In this digest version, we provide a general overview of these two symptoms and discuss the management of acute (up to three weeks) and prolonged/chronic cough (longer than three weeks). Flowcharts are provided, along with a step-by-step explanation of their diagnosis and management. Most cases of acute cough are due to an infection. In chronic respiratory illness, a cough could be a symptom of a respiratory infection such as pulmonary tuberculosis, malignancy such as a pulmonary tumor, asthma, chronic obstructive pulmonary disease, chronic bronchitis, bronchiectasis, drug-induced lung injury, heart failure, nasal sinus disease, sinobronchial syndrome, eosinophilic sinusitis, cough variant asthma (CVA), atopic cough, chronic laryngeal allergy, gastroesophageal reflux (GER), and post-infectious cough. Antibiotics should not be prescribed for over-peak cough but can be considered for atypical infections. The exploration of a single/major cause is recommended for persistent/chronic cough. When sputum is present, a sputum smear/culture (general bacteria, mycobacteria), cytology, cell differentiation, chest computed tomography (CT), and sinus X-ray or CT should be performed. There are two types of rhinosinusitis. Conventional sinusitis and eosinophilic rhinosinusitis present primarily with neutrophilic inflammation and eosinophilic inflammation, respectively. The most common causes of dry cough include CVA, atopic cough/laryngeal allergy (chronic), GER, and post-infectious cough. In the last chapter, future challenges and perspectives are discussed. We hope that the clarification of the pathology of cough hypersensitivity syndrome will lead to further development of "pathology-specific non-specific therapeutic drugs" and provide benefits to patients with chronic refractory cough.

Cough reflex sensitivity and fractional exhaled nitric oxide in children with asthma

Individual studies have suggested the utility of fractional exhaled nitric oxide (FeNO) measurement in detecting cough-variant asthma and eosinophilic bronchitis in patients with chronic cough. The aim of this study was to clarify a correlation of cough reflex sensitivity and fractional exhaled nitric oxide in asthmatic children. 25 children with asthma and 15 controls were submitted to cough reflex sensitivity measurement - capsaicin aerosol in doubling concentrations (from 0.61 to 1250 micromol/l) was inhaled by a single breath method. Concentrations of capsaicin causing two (C2) and five coughs (C5) were reported. Fractional exhaled nitric oxide (FeNO) measurement was included. Asthmatic children' (11 boys and 14 girls, mean age 9+/-1 years) and control group (unconfirmed diagnosis of asthma) (6 boys and 9 girls, mean age 8+/-1 years) were included into the study. FeNO vs. C2 in asthma (Spearman´s rank correlation: -0.146, p=0.49); FENO vs. C5 in asthma (Spearman´s rank correlation: -0.777, p=0.71). We found that there is no correlation between cough reflex sensitivity and fractional exhaled nitric oxide either in children with asthma or in the control group.

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.

Clinical impact of gastroesophageal reflux disease in patients with subacute/chronic cough

BACKGROUND

While gastroesophageal reflux disease (GERD) is one of the commonest causes of subacute/chronic cough along with cough-variant asthma (CVA) and rhinosinusitis, its clinical impact remains unknown. Therefore, we sought to investigate the impact of GERD in patients with subacute/chronic cough.

METHODS

Between April 2012 and March 2018, a total of 312 patients presenting subacute or chronic cough lasting for ≥3 weeks [median cough duration, 4.9 (0.7-434) months] underwent diagnostic tests. GERD symptoms and cough-specific QoL were evaluated through the Frequency Scale for Symptoms of Gastroesophageal reflux (FSSG) and the Japanese version of the Leicester Cough Questionnaire (J-LCQ). According to the FSSG domains, patients with GERD were arbitrarily categorized into 3 groups; acid-reflux predominant, dysmotility predominant, and pauci-symptoms groups, respectively.

RESULTS

The average scores of J-LCQ was 12.5 (SD3.7). One hundred-forty three were diagnosed as having GERD-related cough based on classical reflux symptoms including heartburn and characteristic triggers of cough such as phonation, rinsing, lying, and eating. Most of them (89.8%) had other causative diseases including CVA. Cough lasted longer (p = 0.019) and required a longer time until alleviation (p = 0.003) in patients with GERD than in those without GERD. They also scored lower J-LCQ than counterpart group (p < 0.0001). In terms of symptom stratification, dysmotility predominant group showed significant more response to specific GERD treatments than the remnants (p = 0.002).

CONCLUSIONS

These results indicate that GERD is associated with the aggravation of other causes including CVA. Particularly, dysmotility symptoms may be potential therapeutic target for GERD-related cough.

Airway mycosis in allergic airway disease

The allergic airway diseases, including chronic rhinosinusitis (CRS), asthma, allergic bronchopulmonary mycosis (ABPM) and many others, comprise a heterogeneous collection of inflammatory disorders affecting the upper and lower airways and lung parenchyma that represent the most common chronic diseases of humanity. In addition to their shared tissue tropism, the allergic airway diseases are characterized by a distinct pattern of inflammation involving the accumulation of eosinophils, type 2 macrophages, innate lymphoid cells type 2 (ILC2), IgE-secreting B cells, and T helper type 2 (Th2) cells in airway tissues, and the prominent production of type 2 cytokines including interleukin (IL-) 33, IL-4, IL-5, IL-13, and many others. These factors and related inflammatory molecules induce characteristic remodeling and other changes of the airways that include goblet cell metaplasia, enhanced mucus secretion, smooth muscle hypertrophy, tissue swelling and polyp formation that account for the major clinical manifestations of nasal obstruction, headache, hyposmia, cough, shortness of breath, chest pain, wheezing, and, in the most severe cases of lower airway disease, death due to respiratory failure or disseminated, systemic disease. The syndromic nature of the allergic airway diseases that now include many physiological variants or endotypes suggests that distinct endogenous or environmental factors underlie their expression. However, findings from different perspectives now collectively link these disorders to a single infectious source, the fungi, and a molecular pathogenesis that involves the local production of airway proteinases by these organisms. In this review, we discuss the evidence linking fungi and their proteinases to the surprisingly wide variety of chronic airway and systemic disorders and the immune pathogenesis of these conditions as they relate to environmental fungi. We further discuss the important implications these new findings have for the diagnosis and future therapy of these common conditions.

Traffic-related air pollution induces non-allergic eosinophilic airway inflammation and cough hypersensitivity in guinea-pigs

BACKGROUND

The pathogenesis and pathophysiology of eosinophilia-related chronic cough such as non-asthmatic eosinophilic bronchitis and cough variant asthma are still not clear.

OBJECTIVE

This study is to examine the potential role of traffic-related air pollution (TRAP) in eosinophilic inflammation and cough responses.

METHODS

Non-sensitized guinea-pigs were exposed to TRAP in an urban traffic tunnel or kept in a filtered air environment for 7 or 14 days. Reflexive cough was measured using citric acid and allyl isothiocyanate (AITC) challenges, respectively. Spontaneous cough counting was determined using audio recording and a waveform analysis. Airway inflammation was evaluated using differential cells in bronchoalveolar lavage fluid (BALF) and lung histopathology. To further elucidate the relationship between airway inflammation and cough hypersensitivity, a subgroup of those exposed for 14 days received a dexamethasone treatment.

RESULTS

Compared to reflexive cough count (mean (95% confidence interval) in 10 minutes) provoked by the AITC challenge for the unexposed animals (3.1 (1.7-4.5)), those were increased significantly following both the 7-day (12.0 (6.8-17.2), P < 0.01) and the 14-day (12.0 (6.4-17.6), P < 0.01) TRAP exposure. The effect provoked by the citric acid challenge was more profound following the 14-day exposure (26.0 (19.5-32.5) vs 3.8 (1.5-6.0) for the control, P < 0.001). TRAP exposures enhanced spontaneous cough events, caused a significant increase of eosinophils and neutrophils in BALF and resulted in a dramatic eosinophilic infiltration in submucosal layer of trachea and bronchus, which can be inhibited significantly by dexamethasone treatment.

CONCLUSIONS & CLINICAL RELEVANCE

TRAP exposures induced cough hypersensitivity and non-allergic eosinophilic inflammation of airways in guinea-pigs. This study highlights the potential mechanisms of eosinophilia-related chronic cough that can be induced by traffic-related air pollution.

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.

Occupational and Environmental Contributions to Chronic Cough in Adults: Chest Expert Panel Report

BACKGROUND

In response to occupational and environmental exposures, cough can be an isolated symptom reflecting exposure to an irritant with little physiological consequence, or it can be a manifestation of more significant disease. This document reviews occupational and environmental contributions to chronic cough in adults, focusing on aspects not previously covered in the 2006 ACCP Cough Guideline or our more recent systematic review, and suggests an approach to investigation of these factors when suspected.

METHODS

MEDLINE and TOXLINE literature searches were supplemented by articles identified by the cough panel occupational and environmental subgroup members, to identify occupational and environmental aspects of chronic cough not previously covered in the 2006 ACCP Cough Guideline. Based on the literature reviews and the Delphi methodology, the cough panel occupational and environmental subgroup developed guideline suggestions that were approved after review and voting by the full cough panel.

RESULTS

The literature review identified relevant articles regarding: mechanisms; allergic environmental causes; chronic cough and the recreational and involuntary inhalation of tobacco and marijuana smoke; nonallergic environmental triggers; laryngeal syndromes; and occupational diseases and exposures. Consensus-based statements were developed for the approach to diagnosis due to a lack of strong evidence from published literature.

CONCLUSIONS

Despite increased understanding of cough related to occupational and environmental triggers, there remains a gap between the recommended assessment of occupational and environmental causes of cough and the reported systematic assessment of these factors. There is a need for further documentation of occupational and environmental causes of cough in the future.

Japanese Guideline for Adult Asthma 2014

Adult bronchial asthma (hereinafter, asthma) is characterized by chronic airway inflammation, reversible airway narrowing, and airway hyperresponsiveness. Long-standing asthma induces airway remodeling to cause intractable asthma. The number of patients with asthma has increased, and that of patients who die from asthma has decreased (1.5 per 100,000 patients in 2012). The aim of asthma treatment is to enable patients with asthma to lead a normal life without any symptoms. A good relationship between physicians and patients is indispensable for appropriate treatment. Long-term management with antiasthmatic agents and elimination of the causes and risk factors of asthma are fundamental to its treatment. Four steps in pharmacotherapy differentiate between mild and intensive treatments; each step includes an appropriate daily dose of an inhaled corticosteroid, varying from low to high. Long-acting 02-agonists, leukotriene receptor antagonists, and sustained-release theophylline are recommended as concomitant drugs, while anti-immunoglobulin E antibody therapy has been recently developed for the most severe and persistent asthma involving allergic reactions. Inhaled 02-agonists, aminophylline, corticosteroids, adrenaline, oxygen therapy, and others are used as needed in acute exacerbations by choosing treatment steps for asthma exacerbations depending on the severity of attacks. Allergic rhinitis, chronic obstructive pulmonary disease, aspirin-induced asthma, pregnancy, asthma in athletes, and coughvariant asthma are also important issues that need to be considered.

Increased proportions of CCR4(+) cells among peripheral blood CD4(+) cells and serum levels of allergen-specific IgE antibody in canine chronic rhinitis and bronchitis

Canine chronic rhinitis (CR) and bronchitis (CB) are suspected to be allergic diseases. The present study tested whether dogs diagnosed with CR or CB present an atopic predisposition based on the ratio of CC chemokine receptor 4 (CCR4)-positive cells among peripheral blood CD4-positive cells (CCR4/CD4) and the serum levels of allergen-specific IgE antibodies. We found that most dogs with CR and CB have a possibility of atopic predisposition, and macrolide therapy constitutes an alternative to corticosteroid therapy in controlling the clinical signs.

Atopic cough and fungal allergy

We have shown that some patients presenting with chronic bronchodilator-resistant non-productive cough have a global atopic tendency and cough hypersensitivity without nonspecific bronchial hyperresponsiveness, abbreviated as atopic cough (AC). The cough can be treated successfully with histamine H1 antagonists and/or glucocorticoids. Eosinophilic tracheobronchitis and cough hypersensitivity are pathological and physiological characteristics of AC. Fungus-associated chronic cough (FACC) is defined as chronic cough associated with basidiomycetous (BM) fungi found in induced sputum, and recognition of FACC has provided the possibility of using antifungal drugs as new treatment strategies. Bjerkandera adusta is a wood decay BM fungus, which has attracted attention because of its potential role in enhancing the severity of cough symptoms in FACC patients by sensitization to this fungus. Before making a diagnosis of "idiopathic cough" in cases of chronic refractory cough, remaining intractable cough-related laryngeal sensations, such as "a sensation of mucus in the throat (SMIT)," which is correlated with fungal colonization, should be evaluated and treated appropriately in each patient. The new findings, i.e., the detection of environmental mushroom spores that should not be present in the human airways in addition to the good clinical response of patients to antifungal drugs, may lead to the development of novel strategies for treatment of chronic cough.

Chronic cough management: dealing with a sensation of irritation in the throat

Among the various types of laryngeal paraesthesia suffered by chronic cough patients, we often encounter 'a sensation of irritation in the throat (SIT)'. Our study indicated that capsaicin cough threshold was significantly (P < 0.05) lower in the SIT-positive group (13.9 μmol/L) than in the SIT-negative group (49.6 μmol/L). The establishment of treatment strategies for SIT would be advantageous for treating chronic cough patients suffering from this laryngeal sensation.

Changing the paradigm for cough: does 'cough hypersensitivity' aid our understanding?

Chronic cough is a common reason for patients to seek medication attention. Over the last few decades, we have experienced significant clinical success by applying the paradigm of 'evaluating and treating the causes for chronic cough'. However, we still ask ourselves 'what underlies chronic cough. Indeed in a considerable proportion of patients cough is idiopathic, or unexplained despite vigorous evaluation. Commonly associated conditions such as rhinitis, eosinophilic bronchitis, asthma, or gastroesophageal acidic reflux may not be fundamental to cough, and thus may be triggers rather than causes. The cardinal feature of chronic cough is persistent upregulation the cough reflex, which may be driven by complex interactions between biologic, neurologic, immunologic, genetic, comorbid, and environmental factors. We suggest the new paradigm 'cough hypersensitivity syndrome' should finally bring us further advances in understanding and management of chronic cough.

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)

Clinical experience with low-dose itraconazole in chronic idiopathic cough

BACKGROUND

The presence of basidiomycetous (BM) fungi in induced sputum is an important clinical finding in chronic idiopathic cough (CIC). However, the efficacy of anti-fungal therapy for CIC has not been evaluated.

METHODS

We selected 10 patients with CIC and carried out allergological examinations for Bjerkandera adusta, a BM fungus that has been shown to enhance cough severity. The efficacy of low-dose itraconazole (ITCZ) therapy (50 mg/day) for 14 days as an adjunctive therapy was estimated with use of Cough Visual Analog Scale (Cough VAS) and the Japanese version of the Leicester Cough Questionnaire (J-LCQ). We evaluated whether there was a recognizable clinical or allergological pattern that could predict the efficacy of ITCZ therapy in CIC patients.

RESULTS

Significant changes in Cough VAS and minimal important difference in domains of the J-LCQ were observed in 3 and 5 CIC patients, respectively. The Δ cough scale was correlated with changes in domains of the J-LCQ (total (r = -0.73, P < 0.05), psychological (r = -0.73, P < 0.05), and social (r = -0.71, P < 0.05), respectively. There were significant differences in the change in total score (P < 0.05) and in the domain of social (P < 0.05) and Δ cough scale (P < 0.05) between positive and negative results of immediate skin test for B. adusta. Positive results for improvement of cough-related laryngeal sensation which was represented as a sensation of mucus in the throat (SMIT) were observed in 6 patients in the BM colonization-positive group (85.7%) and none in the BM colonization-negative group (0%). There was a significant difference in the positive ratio for improvement of SMIT between the two groups.

CONCLUSIONS

At present, it is not possible to conclude whether ITCZ therapy provides sufficient relief in CIC patients. However, this study suggested both the possible applicability of low-dose ITCZ therapy for treatment of CIC patients with regard to BM allergy and the necessity of development of a new assessment questionnaire for cough-related laryngeal sensations.

TRIAL REGISTRATION

UMIN-CTR (reference number R000005872; UMIN000004933).

Reversibility of the pulmonary function based on the partial flow-volume curve predicts the efficacy of bronchodilator therapy for treating chronic cough

OBJECTIVE

Partial expiratory flow-volume curves have the potential to detect mild bronchoconstriction because they are not affected by the modulatory effects of deep inspiration. The aim of this study was to investigate the relationship between the efficacy of bronchodilator therapy (BDT) in treating the cough and to assess the increase in the expiratory flow of the partial flow-volume curve at 40% above the residual volume level (PEF40) caused by treatment with a short-acting beta-2 agonist (SABA) in patients with chronic nonproductive cough.

METHODS

We measured the reversibility of PEF40 caused by a SABA in 42 patients with chronic nonproductive cough at visit 1 (day 0). The patients received BDT for six days. The visual analogue scale (VAS) was used to assess the efficacy of BDT in treating coughing at visit 2 (day 7) (0 mm, 'no cough;' 100 mm, 'no change in coughing').

RESULTS

Reversibility of the PEF40 was correlated (r=0.690, p<0.001) with the VAS score determined at visit 2 and was higher in the patients with cough variant asthma (CVA) (44.9 ± 18.3%) than in those with atopic cough (13.4 ± 10.4%) (p<0.01).

CONCLUSION

Reversibility of the PEF40 predicted the efficacy of BDT in patients with chronic nonproductive cough and helped to identify patients with CVA.

Sensitization to Bjerkandera adusta enhances severity of cough symptom in patients with fungus-associated chronic cough (FACC)

OBJECTIVE

The aim of the present study was to clarify the influence of sensitization to Bjerkandera adusta (B. adusta) on the clinical manifestation in patients with fungus-associated chronic cough (FACC).

METHODS

Seventeen patients with FACC who underwent bronchoprovocation tests using an antigenic solution of B. adusta were selected from among 21 FACC patients. We compared the allergological findings and clinical characteristics of the FACC patients who showed a positive reaction to the bronchoprovocation test (Allergic fungal cough sensitized to B. adusta; AFC-Bj) with the remaining FACC patients (non AFC-Bj) retrospectively.

RESULTS

The eleven patients with AFC-Bj had a median age of 52 (range, 22-70) years, and 45.5% were female. The respective values for six patients with non AFC-Bj were 47.5 (range, 36-60) years of age, and 33.3% were female. The positive ratios for an immediate cutaneous reaction (45.5%; p<0.05) and the lymphocyte stimulation test (63.6%; p<0.05) to B. adusta were found to be significantly higher in the AFC-Bj group than in the non AFC-Bj group. The total time required for complete remission of cough symptoms was longer (median 20, range 12-43 weeks; p=0.0009), and the recurrence ratio of coughing was more frequent in the AFC-Bj group in comparison to those in non AFC-Bj group (2, range 1-3 times and 0.5, range 0-1 times, respectively).

CONCLUSIONS

This study demonstrated that B. adusta, a basidiomycetous is an environmental fungus attracting attention because of its possible role in enhancing the cough severity of FACC patients via the sensitization to this fungus.

Involvement of nitric oxide (NO) in cough reflex sensitivity between non-sensitized and OVA-sensitized guinea pigs

Background

Exhaled nitric oxide (ENO) is elevated in bronchial asthma patients, and inhaled corticosteroid therapy lowers the elevated ENO levels in such patients. ENO appears to be an inflammatory marker, but its role in the pathophysiology of cough remains unclear. This study aimed to elucidate the relationship between NO and increased cough reflex sensitivity induced by allergic airway reactions.

Methods

Cough reflex sensitivity to inhaled capsaicin was observed under NO depletion caused by NO synthase (NOS) inhibitors in non-sensitized and ovalbumin (OVA)-sensitized guinea pigs. The bronchoalveolar lavage fluid (BALF) was analyzed in an NO depletion setting using the inducible NOS (iNOS) inhibitor ONO1714 in OVA-sensitized guinea pigs.

Results

NO depletion by the non-selective NOS inhibitor L-NAME suppressed cough reflex sensitivity in non-sensitized guinea pigs and OVA-induced increase in cough reflex sensitivity in sensitized guinea pigs; however, iNOS inhibition caused by ONO1714 partially suppressed the OVA-induced increase in cough reflex sensitivity, but not the normal cough response in non-sensitized guinea pigs. ONO1714 did not change BAL cell components in OVA-sensitized guinea pigs.

Conclusions

The results suggest that NO may be involved not only in the normal cough reflex circuit, but also in the OVA-induced increase in cough reflex sensitivity, possibly via a different mechanism of action. Further studies are needed to clarify the precise mechanism.

Plasma substance P levels in patients with persistent cough

BACKGROUND

Substance P (SP) is involved in the pathogenesis of cough in animal models. However, few studies in humans have been reported and the roles of SP in clinical cough remain obscure.

OBJECTIVES

To clarify the relevance of plasma levels of SP in patients with persistent cough.

METHODS

We studied 82 patients with cough persisting for at least 3 weeks and 15 healthy controls. Patients were classified as having asthmatic cough (cough-variant asthma and cough-predominant asthma; n = 61) or nonasthmatic cough (n = 21; postinfectious cough, n = 6; gastroesophageal reflux disease, n = 5; idiopathic cough, n = 5, and others, n = 5). Correlations were evaluated between plasma SP levels as measured with ELISA and methacholine airway hyperresponsiveness (airway sensitivity and airway reactivity), capsaicin cough sensitivity, sputum eosinophil and neutrophil counts, and pulmonary function.

RESULTS

Plasma SP levels were significantly elevated in patients with both asthmatic and nonasthmatic cough compared with controls [31.1 pg/ml (range 18.0-52.2) and 30.0 pg/ml (range 15.1-50.3) vs. 15.4 pg/ml (range 11.3-23.7); p = 0.003 and p = 0.038, respectively] but did not differ between the two patient groups (p = 0.90). Plasma SP levels correlated with airway sensitivity (threshold dose of methacholine) in the patients with asthmatic cough (r = -0.37, p = 0.005) but not with airway reactivity, cough sensitivity, FEV1 values, or sputum eosinophil and neutrophil counts in either group.

CONCLUSIONS

Increased levels of SP in plasma are associated with persistent cough in humans and might be related to airway sensitivity in asthmatic cough.

Unusual asthma syndromes and their management

Asthma usually presents with symptoms of wheeze, dyspnoea and cough. However, clinicians should be aware of atypical presentation of this disorder when cough is the main or only symptom in conditions such as cough-variant asthma, nonasthmatic eosinophilic bronchitis and atopic cough. Early diagnosis and treatment of these conditions with inhaled corticosteroids improves symptoms in the majority of patients. Up to 10% of patients with asthma remain poorly controlled in spite of optimal standard therapy. These patients have been encompassed under the term 'treatment-refractory asthma' (TRA), have the greatest morbidity and are responsible for more than 50% of healthcare costs. In this review we discuss investigations, management and pathophysiology of the various phenotypes of atypical presentations of asthma as well as novel biological agents licensed and those that have been reported in clinical trials in terms of their efficacy and safety in TRA.

Japanese guideline for adult asthma

Adult bronchial asthma (hereinafter, asthma) is characterized by chronic airway inflammation, reversible airway narrowing, and airway hyperresponsiveness. Long-standing asthma induces airway remodeling to cause an intractable asthma. The number of patients with asthma has increased, while the number of patients who die from asthma has decreased (1.7 per 100,000 patients in 2009). The aim of asthma treatment is to enable patients with asthma to lead a healthy life without any symptoms. A partnership between physicians and patients is indispensable for appropriate treatment. Long-term management with agents and elimination of causes and risk factors are fundamental to asthma treatment. Four steps in pharmacotherapy differentiate mild to intensive treatments; each step includes an appropriate daily dose of an inhaled corticosteroid (ICS), varying from low to high doses. Long-acting β(2) agonists (LABA), leukotriene receptor antagonists, and theophylline sustained-release preparation are recommended as concomitant drugs, while anti-IgE antibody therapy is a new choice for the most severe and persistent asthma. Inhaled β(2) agonists, aminophylline, corticosteroids, adrenaline, oxygen therapy, etc., are used as needed against acute exacerbations. Allergic rhinitis, chronic obstructive pulmonary disease (COPD), aspirin induced asthma, pregnancy, and cough variant asthma are also important factors that need to be considered.

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.

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 variant asthma and atopic cough

Chronic cough has been reported to be the fifth most common complaint seen by primary care physicians in the world, the third in Italy. Chronic cough in non-smoking, non-treated with ACE-inhibitor adults with normal chest radiogram could be a symptom of asthma and can be sub-classified into: cough-variant asthma, atopic cough, and eosinophilic bronchitis. This review discusses the differential diagnosis of these three disorders.

Efficacy of itraconazole in the treatment of patients with chronic cough whose sputa yield basidiomycetous fungi-fungus-associated chronic cough (FACC)

OBJECTIVES

This controlled study was performed to clarify the therapeutic benefit of itraconazole for the treatment of patients with chronic cough, wherein a sputum culture yielded basidiomycetous (BM) fungi.

METHODS

Of the 171 patients who visited our hospital for the diagnosis and treatment of chronic cough, BM was detected in the sputum of 39 patients. Informed consents were obtained from 21 patients who were subsequently enrolled in this trial. After the administration of the standard therapy, all the patients were enrolled in a randomized placebo-controlled study with 2 weeks of treatment with a low dose of itraconazole (50 mg/day) (n = 10) in comparison with a corresponding period of treatment with matched placebo (ambroxol hydrochloride 45 mg/day) (n = 11). Coughing was assessed using subjective cough symptom scale and capsaicin cough challenging.

RESULTS

The treatment with itraconazole, but not placebo (p = 0.17), was associated with a significant improvement in the cough scale (p = 0.0051); moreover, the improvement achieved with itraconazole was significant (p < 0.001) when compared with that of the placebo.

CONCLUSIONS

Low-dose itraconazole was shown to be an effective antitussive in patients with chronic cough in which sputum examination yielded BM fungi. The 21 patients described here entailed the following manifestations: (1) chronic cough; (2) the presence of environmental fungi, particularly basidiomycetous (BM) fungi, in the sputum; and (3) good clinical response to antifungal drugs. These clinical features may constitute a unique disease concept called fungus-associated chronic cough (FACC).

The importance of basidiomycetous fungi cultured from the sputum of chronic idiopathic cough: a study to determine the existence of recognizable clinical patterns to distinguish CIC from non-CIC

BACKGROUND

Recently we have reported 5 cases of allergic fungal cough (AFC), which is intractable and is characterized by sensitization to one of basidiomycetous fungus. Because AFC shows good clinical response to antifungal drugs, diagnosing AFC in patients with CIC may lead to the consequent management of CIC. Therefore, we determined the incidence of CIC among our hospital patients, and the frequency of BM fungi in sputum samples collected from patients with CIC. Furthermore we evaluated whether or not a recognizable clinical pattern that distinguishes CIC from non-CIC exists.

METHODS

The medical records of 70 patients complaining of chronic cough who were referred to our hospital for diagnosis and treatment were analyzed retrospectively.

RESULTS

The primary diagnoses were CIC (27.0%), cough-variant asthma (30.0%), atopic cough (24.3%), sinobronchial syndrome (8.6%), cough-predominant asthma (7.1%), gastro-esophageal reflux (1.4%), and others (1.4%). In CIC patients, the median age, proportion of females, and frequency of acute upper respiratory tract infection did not differ significantly from those in non-CIC patients. CIC patients had a longer median duration of cough (11.0 months vs. 3.5 months). The positive ratio of BM cultured from the sputa of CIC patients (62.5%) was significantly (p=0.0061) higher than that of non-CIC patients (16.7%).

CONCLUSION

The existence of BM fungi in induced sputum may be an important factor for distinguishing the clinical manifestation of CIC from that of non-CIC. The clinical approach from the aspect of fungal allergy may serve as a clue that may aid in the successful management of CIC.

Eosinophilic pneumonia caused by Aspergillus niger: is oral cleansing with amphotericin B efficacious in preventing relapse of allergic pneumonitis?

Eosinophilic pneumonia was confirmed by bronchoalveolar lavage fluid examination and transbronchial lung biopsy. Aspergillus niger was cultured from the patient's pharyngeal swab and bronchoalveolar lavage fluid. Inhalation bronchoprovocation test with A. niger antigen was positive. Although the patient's condition improved promptly with 10 mg/day prednisolone administration, dry cough recurred approximately 2 months after completion of this therapy. Severe coughing disappeared on oral cleansing with 300 mg/day amphotericin B, and he recovered completely on 100 mg/day amphotericin B administration. Oral cleansing with amphotericin B may be efficacious in preventing relapses of eosinophilic pneumonia caused by allergic reaction to fungal antigen.

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.

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 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.

Prevalence, pathogenesis, and causes of chronic cough

Cough is a reflex action of the respiratory tract that is used to clear the upper airways. Chronic cough lasting for more than 8 weeks is common in the community. The causes include cigarette smoking, exposure to cigarette smoke, and exposure to environmental pollution, especially particulates. Diseases causing chronic cough include asthma, eosinophilic bronchitis, gastro-oesophageal reflux disease, postnasal drip syndrome or rhinosinusitis, chronic obstructive pulmonary disease, pulmonary fibrosis, and bronchiectasis. Doctors should always work towards a clear diagnosis, considering common and rare illnesses. In some patients, no cause is identified, leading to the diagnosis of idiopathic cough. Chronic cough is often associated with an increased response to tussive agents such as capsaicin. Plastic changes in intrinsic and synaptic excitability in the brainstem, spine, or airway nerves can enhance the cough reflex, and can persist in the absence of the initiating cough event. Structural and inflammatory airway mucosal changes in non-asthmatic chronic cough could represent the cause or the traumatic response to repetitive coughing. Effective control of cough requires not only controlling the disease causing the cough but also desensitisation of cough pathways.

Comparison of atopic and nonatopic children with chronic cough: bronchoalveolar lavage cell profile

Chronic cough is a common complaint in children and its relationship with asthma is controversial. The aim of the present study was to determine the pattern of airway inflammation in atopic and nonatopic children with chronic cough, and to investigate whether atopy is a predictive factor for eosinophilic inflammation in cough. Bronchoalveolar lavage (BAL; three aliquots of 1 ml/kg saline) was performed in the right middle lobe of 24 (11 atopic and 13 nonatopic) children with persistent cough (8 females, 16 males), mean age 4.7 years (range: 1-11). Atopy was defined as an elevated total serum IgE or a positive RAST test. Both atopic and nonatopic children with persistent cough had an increase in total cells/ml in BAL (atopic: median 39 x 10(4), range: 20-123; nonatopic: median 22 x 10(4), range: 17-132) compared to nonatopic controls (median 11 x 10(4), range 9-30). The increases were mainly in neutrophils (atopic: median 17%, range 2.5-88.5%; nonatopic: median 6%, range 1.0-55.0%) compared to controls (median 1.55%, range 0.5-7.0%; atopics vs. controls, P < 0.005). There were no significant increases in eosinophils, lymphocytes, epithelial cells, or mast cells. Eosinophils were elevated in only 5/11 atopic and none of the nonatopic children. The increased percentage of neutrophils in the BAL fluid of atopic and nonatopic children with persistent cough could be due to an underlying inflammatory process driving the cough, or even conceivably, due to the effect of coughing itself. In this highly selected series, the absence of eosinophilic inflammation in the majority suggests that most would be predicted not to respond to inhaled corticosteroid therapy. This study underscores the need to be cautious about treating coughing children with inhaled corticosteroids, even in the context of a tertiary referral practice.

Selective inhibitors for phosphodiesterase 3 and 4 in antigen-induced increase of cough reflex sensitivity in guinea pigs

Effects of the selective phosphodiesterase 3 (PDE3) inhibitor olprinone and the selective PDE4 inhibitor SB207499 were investigated on antigen-induced increase of cough reflex sensitivity and normal cough response to capsaicin in guinea pigs. Number of coughs elicited by inhalation of capsaicin (10(-8), 10(-6) and 10(-4)M) was counted 24h after an antigen challenge in actively sensitized guinea pigs, and then bronchoalveolar lavage (BAL) was performed. Olprinone (1 or 10mg/kg) or SB207499 (1 or 10mg/kg) was given twice intraperitoneally: One hour after the antigen challenge and 1h before the capsaicin provocation. SB207499, but not olprinone, significantly reduced both antigen-induced increase of cough response to inhaled capsaicin in sensitized animals and normal cough response in non-sensitized animals. SB207499, but not olprinone, also reduced the antigen-induced BAL eosinophilia. PDE4 inhibitors may be useful in treating cough associated with airway allergy via inhibiting both allergic airway inflammation and the common pathway of cough reflex.

Atopic cough-like cough hypersensitivity caused by active sensitization with protein fraction of Aspergillus restrictus strain A-17

We examined the sensitivity of the cough reflex to inhaled citric acid in guinea pigs that had been actively sensitized with the protein fraction of Aspergillus restrictus strain A-17. The number of coughs elicited by an aerosol of 5% citric acid was significantly increased in the sensitized group compared to the non-sensitized group. The number of citric-acid-induced coughs in sensitized guinea pigs was dose-dependently and significantly reduced to the level in non-sensitized guinea pigs when animals were pretreated with fexofenadine, a selective histamine H1 receptor antagonist, 60min before citric acid inhalation. The bronchial responsiveness to inhaled methacholine or histamine in the sensitized group was not significantly heightened compared to the non-sensitized group. These results suggest that active sensitization with the protein fraction of A. restrictus by itself, that is without subsequent allergen challenge, enhances the excitability of cough receptors to tussive stimuli, and the physiologic features of this animal model are consistent with those of atopic cough.

Proton pump inhibitor-responsive chronic cough without acid reflux: a case report

Background

Because 24-h esophageal pH monitoring is quite invasive, the diagnosis of gastroesophageal reflux disease (GERD)-associated cough has usually been made based merely on the clinical efficacy of treatment with proton pump inhibitor (PPI).

Case presentation

We recently encountered two patients with PPI-responsive chronic non-productive cough for whom switching from bronchodilators and glucocorticosteroids to PPI resulted in improvement of cough. The cough returned nearly to pre-administration level a few weeks after discontinuation of PPI. Though GERD-associated cough was suspected, 24-h esophageal pH monitoring revealed that the cough rarely involved gastric acid reflux. Following re-initiation of PPI, the cough disappeared again.

Conclusion

PPI may improve cough unrelated to gastric acid reflux.

Effect of montelukast in a guinea pig model of cough variant asthma

Cough variant asthma is known as a major cause of chronic cough. Fundamental features of cough variant asthma are prolonged non-productive cough responding to bronchodilator therapy, no history of wheezing or dyspnea attack, normal cough sensitivity and slightly increased bronchial responsiveness. Recently, we reported the animal model of cough variant asthma. The aim of this study was to clarify the involvement of cysteinyl leukotrienes (cysLTs) in this model by using a specific leukotriene receptor antagonist, montelukast. Cough number and specific airway resistance (sRaw) were measured during the antigen inhalation (1.5 min) and following 18.5 min, which was carried out 72 h after the first antigen inhalation in actively sensitized guinea pigs, and then total cell number and cell differentials in bronchoalveolar lavage fluid (BALF) were measured. Montelukast significantly reduced the antigen re-inhalation-induced cough, increase in sRaw, and increase in total cell number in BALF. In conclusion, cysLTs may play an important part in antigen-induced cough associated with bronchoconstriction and airway inflammation in cough variant asthma.

Prostaglandin I2 enhances cough reflex sensitivity to capsaicin in the asthmatic airway

Inflammatory mediators are involved in the pathogenesis of airway inflammation, but the role of prostaglandin I2 (PGI2) remains obscure. This study was designed to investigate the role of PGI2 in cough reflex sensitivity of the asthmatic airway, which is characterized by chronic eosinophilic airway inflammation. The effect of beraprost, a chemically and biologically stable analogue of PGI2, on cough response to inhaled capsaicin was examined in 21 patients with stable asthma in a randomized, placebo-controlled cross over study. Capsaicin cough threshold, defined as the lowest concentration of capsaicin eliciting five or more coughs, was measured as an index of airway cough reflex sensitivity. The cough threshold was significantly (p < 0.05) decreased after two weeks of treatment with beraprost [17.8 (GSEM 1.20) microM] compared with placebo [30.3 (GSEM 1.21) microM]. PGI2 increases cough reflex sensitivity of the asthmatic airway, suggesting that inhibition of PGI2 may be a novel therapeutic option for patients with asthma, especially cough predominant asthma.

Geography and cough aetiology

Cough is the most common complaint that leads patients to seek medical attention. Especially chronic persistent cough is annoying, and requires appropriate diagnosis and treatment. Recent cough guidelines and original papers on cough epidemiology from various countries show remarkable differences in the aetiology of chronic cough among countries, especially between US, UK and Japan. Entities associated with rhinosinus disease (post-nasal drip/upper airway cough syndrome reported from the US, rhinitis or rhinosinusitis from the UK, and sinobronchial syndrome from Japan), and eosinophilic lower airway disorders (cough variant asthma, non-asthmatic eosinophilic bronchitis and atopic cough) are most confusing and might involve significant overlap. In this article, issues related to chronic cough aetiology are discussed, including geographic issues, e.g. 'simple' geography or difference in race, and difference in patient characteristics possibly arising from difference in the medical system.