Change in bronchial responsiveness and cough reflex sensitivity in patients with cough variant asthma: effect of inhaled corticosteroids

Retrospective, observational study of different medication regimens and outcome in children with cough variant asthma

OBJECTIVE

This retrospective longitudinal cohort study aimed to explore the best therapeutic regimen and treatment duration of cough variant asthma (CVA) in children.

METHODS

A total of 314 children with CVA were divided into receive inhaled corticosteroids (ICS) combined with long-acting beta2-agonist (LABA) group, ICS combined with leukotriene receptor antagonists (LTRA) group, ICS monotherapy group and LTRA monotherapy group. All clinical data were statistically analyzed. Logistic regression model was used to compare the advantages and disadvantages of different treatment schemes at each follow-up time point and the best treatment scheme. The Cox proportional hazard regression model based on inverse probability weighting was used to compare the effects of different medication regimens on adverse outcomes with asthma recurrence or progression as the end point.

RESULTS

(1) After comprehensive analysis, ICS + LABA group was the preferred control regimen for CVA within 8 weeks. After 8 weeks of diagnosis, the efficacy of ICS group or LTRA group was comparable to that of ICS + LABA group and ICS + LTRA group. (2) The ICS + LABA group showed a significant improvement in cough at an early stage, particularly at 4 weeks; the symptoms of ICS + LTRA and ICS groups were significantly improved at 36 weeks. The LTRA group alone showed significant improvement at 20 weeks.

CONCLUSION

ICS + LABA, ICS + LTRA, ICS alone and LTRA alone can effectively treat CVA. ICS + LABA could improve the symptoms most quickly within 8 weeks after CVA diagnosis, followed by ICS + LATR group. After 8 weeks, it can be reduced to ICS alone to control CVA for at least 36 weeks based on the remission of symptoms in children.

Cough and cough hypersensitivity as treatable traits of asthma

Cough is a common and troublesome symptom in people with asthma and is often associated with poorer asthma control and exacerbations. Apart from asthma, other causes or comorbidities might underlie cough in asthma, such as rhinosinusitis and bronchiectasis. Eosinophilic inflammation and bronchoconstriction can lead to an acute episode of cough or worsen chronic cough. Cough hypersensitivity with laryngeal paraesthesia, allotussia, and hypertussia might underlie the cough of asthma through augmented sensory nerve excitability of upper-airway vagal sensory nerves. Cough associated with bronchoconstriction and type 2 inflammation should respond to inhaled corticosteroids and long-acting β-adrenoceptor agonist therapy. For cough hypersensitivity in adults, speech and language therapy and neuromodulators (eg, gabapentin) could be considered. In children, there is no consistent association of asthma with cough sensitivity or between cough and asthma severity. Further research is needed to realise the potential of cough as a measure of asthma control, to understand the mechanisms of cough in asthma, and to develop safe, effective treatments and a precision-medicine approach to the management of cough in asthma in children and adults.

The Reaction of Airways of Employees Working in the Environments Polluted with Heavy Metals in Mine Kosovo

This paper is studied the respiratory function as a result of the impact of air pollution in the environment of the sector of exploitation of heavy minerals such Pb, Zn, Au, Ag, Bi, Cd, PM in the mines of Trepça, Kosovo. Lung function parameters are determined by Body plethysmography. Airway resistance (Raw) was recorded and Intra-Thoracic Gas Volume (ITGV) was measured and specific resistance (SRaw) and airway specific conductance (SGaw) were calculated. The research was done in two groups, the control group and the experimental one. The control group consisted of 24 healthy people, while the experimental one is made up of 52 mining workers for the exploitation of minerals in the Trepçamine, Kosovo. The results obtained from this research indicate that the mean value of specific resistance (SRaw) is significantly higher in the experimental group (p<0.01), compared to the control group (p>0.1). Also, in this study it was confirmed that smoking favors the negative effects of air contamination in the mineral exploitation sector, the changes are significant (p<0.01). Respiratory system parameters of the control group and the experimental group were measured before and after bronchoprovocation with histamine-aerosol (1 mg/ml). The differences between these two groups after provocation were statistically significant (p<0.01). Respiratory changes from air pollution with noxae in mines where metals are mined, it takes a long time for changes in respiratory function to appear. Therefore, exposure of workers to these conditions poses a risk to their health, causing bronchial reactivity, bronchial asthma or, obstructive pulmonary syndrome.

Characteristics of different asthma phenotypes associated with cough: a prospective, multicenter survey in China

Background

Asthma is a heterogeneous disease with variable symptoms, which presents with cough either as the sole or predominant symptom with or without wheezing. We compared the clinical and pathophysiological characteristics of cough predominant asthma (CPA), cough variant asthma (CVA) and classic asthma (CA) in order to determine any differential phenotypic traits.

Methods

In 20 clinics across China, a total of 2088 patients were finally recruited, including 327 CVA, 1041 CPA and 720 CA patients. We recorded cough and wheezing visual analogue scale, Leicester cough questionnaire (LCQ) and asthma control test scores. Fractional exhaled nitric oxide (FeNO), induced sputum cell counts, and capsaicin cough challenge were also measured and compared.

Results

CPA patients more frequently presented with cough as the initial symptom, and laryngeal symptoms (p < 0.001), had less symptoms related with rhinitis/sinusitis and gastroesophageal reflux (p < 0.05) than CA patients. Comorbidities including rhinitis and gastroesophageal reflux were similar, while the proportion of COPD and bronchiectasis was higher in CA patients. There were no differences in FeNO levels, sputum eosinophil and neutrophil counts, FEV1 (%pred) decreased from CVA to CPA to CA patients (p < 0.001). Cough sensitivity was higher in CVA and CPA compared to CA (p < 0.001), and was positively correlated with LCQ scores.

Conclusions

CVA, CPA and CA can be distinguished by the presence of laryngeal symptoms, cough sensitivity and airflow obstruction. Asthma-associated chronic cough was not associated with airway inflammation or comorbidities in our cohort.

Trial registration The Chinese Clinical Trial Registration Center, ChiCTR-POC-17011646, 13 June 2017

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02104-8.

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.

Manifestation of bronchial hyperreactivity from exposure to heavy and precious metal vapors among the ore smeltery workers of Zveçan, Kosovo

Context:

Kosovo is a region in the Western Balkans that is rich in minerals and coal, so pollution is a serious public health problem there. Workers in the heavy and precious metal smeltery in Zveqan, Kosovo, were studied with regard to the roles that vapor from the smelting of metals (Pb, Zn, Au, Ag, P, and Cu) and particulate matter play in causing bronchial hyperreactivity.

Objectives:

The purpose of the article was to measure the parameters of lung function as determined by body plethysmography, diagnosis of respiratory diseases, and assessment of respiratory function using a histamine bronchoprovocation test.

Settings and Design:

The present study was conducted in two groups of participants: A control group, which included 25 healthy persons, and a smeltery worker group, which included 45 mine workers (15 smokers and 30 nonsmokers) holding permanent jobs in the mineral foundry of Zvecan, Kosovo.

Subjects and Methods:

Pulmonary function parameters (specific airway resistance [Raw] and intrathoracic gas volume) were measured and used to calculate the specific resistance (SRaw)and specific conductance (SGaw) of the airways, and a histamine bronchoprovocation test was conducted.

Statistical Analysis Used:

The data were entered and analyzed using the Microsoft Excel and INSTAT 3 software.

Results:

Airway specific resistance (SRaw) was significantly higher in the smeltery worker group (P < 0.01) as compared to the control group (P > 0.1).

Conclusion:

These results suggest that occupational exposure to vapors during the metal refining process poses a risk to the workers' health and can cause bronchial hyperreactivity, bronchial asthma, or chronic obstructive pulmonary disease.

Methacholine-Induced Cough in the Absence of Asthma: Insights From Impulse Oscillometry

Introduction

The pathophysiologic differences between methacholine-induced cough but normal airway sensitivity (COUGH) and healthy individuals (CONTROL) are incompletely understood and may be due to differences in the bronchodilating effect of deep inspirations (DIs). The purpose of this study is to compare the bronchodilating effect of DIs in individuals with classic asthma (CA), cough variant asthma (CVA), and COUGH with CONTROL and to assess impulse oscillometry (IOS) measures as predictors of the bronchodilating effect of DIs.

Methods

A total of 43 adults [18 female; 44.8 ± 12.3 years (mean ± SD); n = 11 CA, n = 10 CVA, n = 7 COUGH, n = 15 CONTROL] underwent modified high-dose methacholine challenge, with IOS and partial/maximal expiratory flow volume (PEFV/MEFV) maneuvers (used to calculate DI Index) to a maximum change (Δ) in FEV₁ of 50% from baseline (MAX). Cough count and dyspnea were measured at each dose. The relation between IOS parameters and DI Index was assessed at baseline and MAX using multivariable linear regression analysis.

Results

Cough frequency, dyspnea intensity, and baseline peripheral resistance (R5-R20) were significantly greater in COUGH compared with CONTROL (p = 0.006, p = 0.029, and p = 0.035, respectively). At MAX, the DI Index was significantly lower in COUGH (0.01 ± 0.36) compared with CA (0.67 ± 0.97, p = 0.008), CVA (0.51 ± 0.73, p = 0.012), and CONTROL (0.68 ± 0.45, p = 0.005). Fres and R5-R20 were independent IOS predictors of the DI Index.

Conclusion

The bronchodilating effect is impaired in COUGH and preserved in mild CA, CVA, and CONTROL. Increased peripheral airway resistance and decreased resonant frequency are associated with a decreased DI Index. COUGH is a clinical phenotype distinct from healthy normals and asthma.

[The cough variant asthma]

Cough variant asthma (CVA) was first described by W. Corrao. CVA was described as the isolated chronic cough as the only presenting symptom responsive to bronchodilator therapy.This phenotype of asthma is present with airway hyperresponsiveness, eosinophilic inflammation airways and bronchodilator responsive coughing without typical manifestation of asthma such as wheezing or dyspnea. CVA shares common features with classic asthma such as eosinophilic inflammation and airway remodeling. Because of that, CVA is clinically considered as a variant type of asthma.

Interfering with airway nerves in cough associated with asthma

Cough is a troublesome and often refractory symptom of asthma, which is associated with poor control of disease. The pathogenesis of asthmatic cough has mainly been attributed to bronchoconstriction, but recent evidence indicate that cough reflex hypersensitivity or neuronal dysfunction is a feature of asthma, even in those with mild stable disease. This is likely resistant to the mainstay treatment ICS/LABA which inhibits classic asthmatic response. Such refractory cough might manifest more predominantly in the day-time rather than night-time. Treatment options of such refractory cough or cough reflex hypersensitivity in asthma targeting the nerves (LTRAs, tiotropium, and potentially bronchial thermoplasty) are discussed.

Small-airway obstruction, dynamic hyperinflation, and gas trapping despite normal airway sensitivity to methacholine in adults with chronic cough

The clinical relevance of cough during methacholine challenge in individuals with normal airway sensitivity is unknown. We compared responses of individuals with chronic cough who cough during high-dose methacholine bronchoprovocation and have normal versus increased airway sensitivity to healthy controls. Fifteen healthy participants (CONTROL) aged 26 ± 7 yr (mean ± SD) and 32 participants aged 42 ± 14 yr with chronic cough and suspected asthma completed high-dose methacholine challenge testing. Three participants who did not cough and had normal airway sensitivity were excluded. Spirometry and lung volumes were compared at the maximum response (MAX) among 1) ASTHMA [ n = 15, provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (FEV₁) from baseline (PC₂₀) 4.71 ± 1.37 mg/ml], 2) methacholine-induced cough with normal airway sensitivity (COUGH, n = 14, PC₂₀ 41.2 ± 18.7 mg/ml for 3 participants with a measurable PC₂₀), and 3) CONTROL ( n = 15; PC₂₀ 93.4 ± 95.4 mg/ml for 4 participants with a measurable PC₂₀). Esophageal pressure-derived pulmonary mechanics were compared at MAX for the ASTHMA and COUGH groups. From baseline to MAX, FEV₁ and forced expiratory flow between 25% and 75% of forced vital capacity decreased more in ASTHMA (-36.2 ± 3.8 %pr; -47.1 ± 6.9 %pr, respectively) than COUGH (-12.2 ± 3.0 %pr ( P < 0.001); -24.7 ± 6.5 %pr ( P < 0.001), respectively) and CONTROL (-13.7 ± 2.0 %pr ( P < 0.001); -32.8 ± 5.4 %pr ( P < 0.017), respectively). In both ASTHMA and COUGH, inspiratory capacity decreased by 500-800 ml, and functional residual capacity and residual volume increased by ~800 ml. Individuals with COUGH develop dynamic hyperinflation and gas trapping comparable to individuals with ASTHMA despite less bronchoconstriction and smaller reductions in mid-to-late expiratory flows, which leads us to believe that COUGH is a distinct phenotype. NEW & NOTEWORTHY Healthy individuals and individuals with chronic cough who demonstrate normal airway sensitivity but cough during methacholine bronchoprovocation bronchoconstrict less than individuals with mild asthma. However, those who cough and have normal airway sensitivity develop dynamic hyperinflation and gas trapping comparable to individuals with mild asthma. Thus, methacholine-induced cough with normal airway sensitivity may be clinically relevant, related to reversible small airway obstruction and preservation of the bronchodilating and/or bronchoprotective effects of deep inspirations.

Bronchodilating effect of deep inspirations in asthma and chronic cough

The pathophysiologic processes distinguishing classic asthma (CA), cough-variant asthma (CVA), and methacholine (MCh)-induced cough but normal airway sensitivity (COUGH) are inadequately understood and may be a result of differences in the ability to bronchodilate following a deep inspiration (DI). The purpose of this study was to compare the bronchodilating effect of DIs in individuals with CA, CVA, and COUGH using high-dose MCh. Individuals aged 18-65 yr with CA or suspected CVA completed high-dose MCh testing to a maximum change in forced expiratory volume in 1 s (FEV1) of 50% from baseline (MAX). Impulse oscillometry (IOS) measurements and partial and maximal-flow volume curves (used to calculate a DI index) were recorded at baseline and at each dose of MCh. Body plethysmography was performed at baseline and MAX. Twenty-eight subjects [25 women, 39.8 ± 11.9 yr (means ± SD)] were studied (n = 11 CA, n = 10 CVA, and n = 7 COUGH). At MAX, the percent change in FEV1 was greater in subjects with CA compared with those with CVA (P < 0.001) and COUGH (P < 0.001), and the percent change in forced vital capacity was greater in those with CA than with COUGH (P = 0.017). Subjects with CA and CVA developed dynamic hyperinflation and gas trapping. In subjects with CA and CVA, all IOS parameters were significantly increased from baseline to MAX, except for central respiratory resistance (R20). In individuals with COUGH, total respiratory resistance, R20, and resonant frequency were significantly increased from baseline. At MAX, the DI index was positive in all groups, suggesting preserved bronchodilation (CA, 0.67 ± 0.97; CVA, 0.51 ± 0.73; COUGH, 0.01 ± 0.36; P = 0.211). We conclude that the bronchodilating effect of DIs is preserved in individuals with CA, CVA, and borderline with COUGH; however, hyperinflation and gas trapping are avoided in subjects with COUGH alone.

Budesonide suspension nebulization treatment in Chinese pediatric patients with cough variant asthma: a multi-center observational study

OBJECTIVE

To describe the impact of nebulized budesonide inhalation suspension (BIS) on guardian-reported symptoms in Chinese pediatric patients with cough variant asthma (CVA).

METHODS

This was a secondary analysis of a prospective, non-interventional study conducted at 39 Chinese sites. Patients with CVA aged ≤5 years were classified according to the severity of baseline symptoms: mild (symptom score ≤3) or severe (symptom score >3). Daytime and night-time symptom scores, disease control, use of bronchodilators, and improvements in symptoms control were compared after 1, 3, 5 and 7 weeks of treatment between groups.

RESULTS

Among 914 patients, 821 (89.8%) completed the 7-week treatment. Among all patients, 368 (40.3%) were classified as mild CVA and 529 (57.9%), as severe CVA. Symptom scores in the severe group were higher than those in the mild group at weeks 1, 3, and 5 (p < 0.05), but not at week 7 (p > 0.05). Further, more patients in the mild group achieved disease control at any time point (98.6% at 3 weeks and 99.7% at 7 weeks), compared with the patients in the severe group (p < 0.001). The proportion of patients requiring bronchodilators differed between the groups until week 5 (p < 0.001). No severe or drug-related adverse events were reported.

CONCLUSIONS

Individualized BIS treatment should be formulated according to the severity of baseline symptoms in CVA patients. Patients with mild CVA showed improvement after a shorter treatment time, while patients with severe CVA might require a longer time to respond to the treatment.

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.

Effects of regular treatment with combination of salmeterol/fluticasone propionate and salmeterol alone in cough variant asthma

OBJECTIVE

Cough variant asthma (CVA) is an important cause of chronic cough, and pathophysiological features of the disease appear to be similar to typical asthma. Because CVA is recognized as a precursor of asthma, early intervention with long-term anti-inflammatory agents may be recommended. However, the role of combination therapy with inhaled corticosteroid and β2-agonist in the treatment of CVA has not been elucidated. To evaluate the effectiveness of the combination therapy, we investigated the clinical impact of regular treatment with salmeterol/fliticasone propionate combination (SFC) and inhaled salmeterol (SAL) alone in patients with CVA.

METHODS

The study was a randomized, controlled, parallel-group multi-center trial. Forty-three CVA patients were assigned to SFC (50/100 µg once daily) or SAL (50 µg twice daily) for 12 weeks. Then, these medications were stopped for the next 24 weeks. Main outcome measures were cough symptoms, pulmonary function and airway inflammation.

RESULTS

Treatment with each of SFC and SAL significantly decreased cough scores and increased FEV1 and PEF, where the efficacy was more pronounced with SFC than SAL. SFC also decreased sputum eosinophil counts and eosinophil cationic protein contents, whereas SAL had no effect. After discontinuation of the treatment, cough scores increased, pulmonary function and eosinophilic airway inflammation were aggravated and returned to the baseline levels.

CONCLUSIONS

Maintenance therapy with SFC provides further improvements in cough symptoms, pulmonary function and airway inflammation, and discontinuation of the therapy causes worsening of the disease, indicating that stopping or interrupting anti-inflammatory therapy may not be advisable in patients with CVA.

Chronic cough: a respiratory viewpoint

PURPOSE OF REVIEW

This article reviews the common causes and investigation of chronic cough and explores unexplained cough and its relationship to cough hypersensitivity.

RECENT FINDINGS

Cough plays a critical role in airway protection and clearance of secretions. Chronic cough, however, is a debilitating symptom that can significantly interfere with quality of life. Despite their limitations cough guidelines have raised the awareness of chronic cough as an important problem and provided a framework for a logical care pathway. The use of a systematic approach to diagnosis and management in a specialist clinic can result in successful identification as to the cause, with subsequent relief of symptoms. In a proportion of patients no diagnosis is reached or treatment fails. A common finding among these patients is cough reflex hypersensitivity and this is an important feature irrespective of the underlying diagnosis. The majority of patients referred to tertiary cough clinics are females. Women appear to have an intrinsically heightened cough response with augmented cough challenge and a high frequency of ACE-inhibitor cough.

SUMMARY

The way in which we review cough has undergone radical change in the last decade. A distinct population of patients with chronic idiopathic cough is emerging in whom cough reflex hypersensitivity is a feature. Extended co-operation between clinicians, scientists and the pharmaceutical industry is required to better understand the pathophysiology of the enhanced cough reflex and the development of more effective antitussive therapies.

Cough, asthma, and cysteinyl-leukotrienes

Asthma is a chronic inflammatory disease of the lower airways, involving various cells such as eosinophils, and cytokines and mediators. Cyteinyl-leukotrienes (cys-LTs) are one of the chemical mediators that play major pathophysiological roles in asthma. They are produced by eosinophils and mast cells, and induce bronchoconstriction, mucous hypersecretion, microvascular leakage, eosinophil chemotaxis and airway remodeling. Anti-leukotrienes, including leukotriene receptor antagonists (LTRAs) which block cysLT1 receptors, exert both bronchodilatory and anti-inflammatory effects and are utilized as second- to third-line controller medication of persistent asthma. Cough is a major symptom of asthma, and cough variant asthma (CVA) is an asthma phenotype that solely presents with coughing. Sputum levels of cys-LTs are increased in patients with CVA. Antitussive effects of monotherapy with LTRAs in patients with CVA have been reported. We have recently demonstrated that 4 weeks' treatment with an LTRA montelukast exerted anti-inflammatory effect as proved by a decrease of sputum eosinophils, in addition to attenuation of cough VAS and capsaicin cough sensitivity, as reported previously. Spirometry, airway responsiveness, and impulse oscillation indices (respiratory resistance and reactance) were unchanged. These results suggested that the antitussive effect of montelukast in CVA might be attributable to its anti-inflammatory ability rather than bronchodilation. The treatment did not affect sputum levels of mediators (cys-LTs, LTB4, PGD2, PGE2, PGF2α, and TXB2). Since inhaled corticosteroid does not seem to affect cough sensitivity while attenuating cough in patients with CVA, LTRAs may involve different mechanism(s) from that of corticosteroid. LTRAs must theoretically be effective against cough of asthmatic subjects through its "anti-asthma" effects, while evidence supporting direct antitussive effects of cys-LTs on "cough receptors" is scarce. An important clinical question is that whether LTRAs involve non-specific antitussive effects. While a definite answer is not available yet, this possibility seems unlikely at the moment, although some secondary anti-inflammatory properties have been reported for montelukast. This issue needs to be clarified by future research to avoid overuse of this expensive class of medication.

Capability of hypertonic saline cough provocation test to predict the response to inhaled corticosteroids in chronic cough: a prospective, open-label study

BACKGROUND

Many patients with chronic cough respond to treatment with inhaled corticosteroids but it is difficult to predict which patients are likely to respond. The primary aim of the present study was to define the capability of hypertonic saline cough provocation test to predict the responsiveness to inhaled corticosteroids in chronic cough. The secondary aim was to assess the ability of the saline test to monitor the healing of cough during corticosteroid treatment.

METHODS

Forty-three patients with chronic cough were recruited. Before therapy, spirometry, ambulatory peak flow monitoring, nitric oxide measurement, histamine airway challenge, and saline test were performed. Those responding to the first saline test repeated it and the nitric oxide measurement during the subsequent visits. The patients used inhaled budesonide, 400 ug twice daily, for twelve weeks. The treatment response was assessed by Leicester Cough Questionnaire at baseline, and at one, four, and twelve weeks.

RESULTS

Seventy-seven % of the patients demonstrated the minimal important difference in the Leicester Cough Questionnaire indicating a symptomatic response. Neither the response magnitude nor the speed was predicted by the saline test. Histamine challenge showed the strongest predictive ability: The maximal improvement in Leicester Cough Questionnaire total score was 5.08 (3.76 - 6.40) points in the histamine positive and 2.78 (1.55 - 4.01) points in the histamine negative subjects (p = 0.006). Baseline nitric oxide level also associated with the improvement in Leicester Cough Questionnaire total score (p = 0.02). During the treatment, the cough sensitivity to saline gradually decreased among the budesonide responders but not in the non-responders. Nitric oxide levels decreased very rapidly among the responders.

CONCLUSIONS

Saline test cannot predict the responsiveness to inhaled corticosteroids in chronic cough but it may be utilized to monitor the effect of this treatment.

TRIAL REGISTRATION

The study was registered in ClinicalTrials.gov database (KUH5801112). ClinicalTrials.gov Identifier: NCT00859274.

Inflammatory mediators in induced sputum and airway hyperresponsiveness in cough variant asthma during long-term inhaled corticosteroid treatment

Objective. This study aimed to investigate improvements in inflammatory mediator levels in induced sputum and airway hyperresponsiveness (AHR) in cough variant asthma (CVA) during long-term inhaled corticosteroid (ICS) treatment. Patients and Methods. Patients with CVA (N = 35) and classic asthma (N = 26) and healthy subjects (N = 24) were recruited into this study. All patients were treated with budesonide (400 μg/day). Measurement of inflammatory mediators in induced sputum and PD20-FEV₁ (the accumulated provocative dose resulting in a 20% decrease in FEV₁) in histamine-challenged subjects was performed every three months after the start of medication. Interleukin- (IL-) 5 and IL-10 were assayed by ELISA, and the percentage of eosinophils was detected with Giemsa stain. Trends during the follow-up period were analyzed using a general linear model. Results. Inflammatory mediator levels in induced sputum and PD20-FEV₁ in patients with CVA and classic asthma differed from those in the control group, although no differences were found in the two asthmatic groups. PD20-FEV₁ significantly increased in CVA patients after ICS treatment for 3 months, while classic asthma patients exhibited a delayed change in AHR. After ICS treatment, levels of IL-5 and IL-10 as well as the percentage of eosinophils in the CVA group were altered at 3 months and 6 months, respectively. Accordingly, the level of inflammatory mediators in classic asthma changed more slowly. Conclusion. CVA has a greater improvement in airway inflammation and airway hyperresponsiveness (AHR) than classic asthma with respect to inhaled corticosteroid (ICS). Short-term ICS considerably reduces AHR although longer treatment is required for complete control of airway inflammation.

Clinical, physiological and anti-inflammatory effect of montelukast in patients with cough variant asthma

BACKGROUND

Cough variant asthma (CVA) is a phenotype of asthma presenting solely with coughing, characterized by airway hyperresponsiveness, eosinophilic inflammation and a cough response to bronchodilators. Leukotriene receptor antagonists (LTRAs) are antiasthma medications with anti-inflammatory and bronchodilatory properties. Although LTRAs exert antitussive effects in CVA, the mechanisms involved are unknown.

OBJECTIVES

This study aimed to clarify the antitussive mechanisms of LTRAs in CVA patients.

METHODS

We prospectively observed the effect of montelukast (10 mg) daily for 4 weeks in 23 consecutive nonsmoking adults with anti-inflammatory treatment-naive CVA. We evaluated, before and after treatment, the cough visual analogue scale (VAS), pulmonary function (spirometry and impulse oscillation), methacholine airway responsiveness, cough receptor sensitivity, expressed by the concentration of capsaicin inducing 2 or more (C2) and 5 or more (C5) coughs, sputum eosinophil counts and levels of inflammatory mediators, including cysteinyl leukotrienes, leukotriene B(4), prostaglandin (PG) D(2), PGE(2), PGF(2)(α) and thromboxane B(2). We compared the baseline characteristics of the patients based on the symptomatic response to montelukast, defined as a decrease in the cough VAS of >25% (n = 15) or ≤25% (n = 8).

RESULTS

Montelukast significantly decreased the cough VAS (p = 0.0008), sputum eosinophil count (p = 0.013) and cough sensitivity (C2: p = 0.007; C5: p = 0.039), whereas pulmonary function, airway responsiveness and sputum mediator levels remained unchanged. Multivariate analysis showed that a better response to montelukast was associated solely with younger age (p = 0.032).

CONCLUSION

The antitussive effect of montelukast in CVA may be attributed to the attenuation of eosinophilic inflammation rather than its bronchodilatory properties.

Cough response to isocapnic hyperpnoea of dry air and hypertonic saline are interrelated

Background

Mechanisms behind asthmatic cough are largely unknown. It is known that hyperosmolar challenges provoke cough in asthmatic but not in the healthy subjects. It has been postulated that isocapnic hyperpnea of dry air (IHDA) and hypertonic aerosols act via similar mechanisms in asthma to cause bronchoconstriction. We investigated whether there is an association between cough response induced by IHDA and hypertonic saline (HS) challenges.

Methods

Thirty-six asthmatic and 14 healthy subjects inhaled HS solutions with increasing osmolalities administered via ultrasonic nebuliser until 15 cumulative coughs were recorded. The IHDA consisted of three three-minute ventilation steps: 30%, 60% and 100% of maximal voluntary ventilation with an end-point of 30 cumulative coughs. The challenges were performed on separate days at least 48 hours between them and within one week. Inhaled salbutamol (400 mcg) was administered before the challenges to prevent bronchoconstriction. The cough response was expressed as the cough-to-dose ratio (CDR) which is the total number of coughs divided by the maximal osmolality inhaled or the maximal ventilation achieved.

Results

Cough response to IHDA correlated with the HS challenge (Rs = 0.59, p < 0.001). Cough response to IHDA was at its strongest during the first minute after the challenge. IHDA induced more cough among asthmatic than healthy subjects CDR being (mean ± SD) 0.464 ± 0.514 and 0.011 ± 0.024 coughs/MVV%, p < 0.001, respectively. Salbutamol effectively prevented bronchoconstriction to both challenges.

Conclusions

Asthmatic patients are hypersensitive to the cough-provoking effect of hyperpnoea, as they are to hypertonicity. Cough response induced by IHDA and HS correlated well suggesting similar mechanisms behind the responses.

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.

Cough in asthma

Asthma is one of the most common causes of chronic cough, and cough may be the sole or predominant symptom of asthma. The mechanisms of cough in asthma are complex and presumbably multi-factorial. In particular, the pathophysiologic basis of cough variant versus classic asthma is poorly understood. Recent research utilizing various inhalation challenge tests suggests that preservation of the bronchodilating and bronchoprotective effects of deep inspirations is a distinguishing feature of cough variant asthma. This review outlines the tussive agents used in cough research (including tussive and direct, indirect and combined bronchoconstrictive stimuli), their mechanisms of action, the receptors involved in eliciting cough, and characteristic responses in classic asthma and cough variant asthma.

Sensitivity to environmental irritants and capsaicin cough reaction in patients with a positive methacholine provocation test before and after treatment with inhaled corticosteroids

BACKGROUND

Increasing evidence points to a potential role for members of the transient receptor potential family of cation channels on several features of asthmatic disease. The cough sensitivity to inhaled capsaicin is known to reflect the reactivity of these airway sensory nerves.

OBJECTIVE

The aim was to study, among patients having a positive methacholine provocation and diagnosed with asthma, capsaicin cough sensitivity, sensitivity to methacholine, and levels of exhaled nitric oxide before and after treatment with inhaled steroids, and further, to measure the self-reported impact from environmental irritants.

METHODS

Eighteen steroid-naïve patients with a positive methacholine test underwent capsaicin inhalation provocation on two occasions, before and after regular use of inhaled steroids over at least 3 months. Comparisons were made to 21 healthy controls. Sensitivity to methacholine and levels of exhaled nitric oxide were measured before and after the treatment. The participants also answered a validated questionnaire regarding environmental irritants.

RESULTS

The patients displayed higher capsaicin cough sensitivity than the controls before the treatment period, but not afterward. Before treatment, capsaicin cough answer correlated significantly with levels of exhaled nitric oxide, but not with methacholine sensitivity. After treatment with inhaled corticosteroids, the capsaicin cough sensitivity and the inflammatory parameters were normalized. In comparison to the control group, the patients reported more affective reactions to and behavioral disruptions induced by environmental irritants.

CONCLUSIONS

In steroid-naïve patients with a positive methacholine test, there is a link between that part of the airway inflammation that is reflected by exhaled nitric oxide and that followed by an augmented reactivity of capsaicin-sensitive sensory nerves. This association disappears after steroid treatment.

Interrupting the cough reflex in asthma

PURPOSE OF REVIEW

Although cough is one of the defining symptoms of asthma, wheeze, chest tightness and breathlessness have generally received more attention. The impact of coughing for patients may be more important than currently appreciated and has been rated more troublesome than wheeze, chest tightness or disturbance of sleep.

RECENT FINDINGS

Studies objectively measuring cough in asthma reveal that cough frequencies vary from those similar to healthy volunteers to cough counts comparable to patients presenting with chronic cough, but the potential triggers for cough in asthma are poorly understood. This review discusses our current knowledge of cough in asthma, potential mechanisms that may provoke coughing, the effect of current treatments and possible future therapeutics.

SUMMARY

Cough in some asthma patients is a significant problem, deserving further attention in both clinical practice and clinical research.

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.

Common causes and current guidelines

Chronic cough is a common and disabling symptom. Recent guidelines have attempted to provide direction in the clinical management of cough in both primary and secondary care. They have also provided a critical review of the available literature and identified gaps in current knowledge. Despite this they have been criticized for a reliance on a low quality evidence base. In this review, we summarize the current consensus on the clinical management of chronic cough and attempt to rationalize this based on recent evidence. We have also provided an overview of the likely pathophysiological mechanisms responsible for cough and highlighted areas, where knowledge deficits exist and suggest directions for future research. Such progress will be critical in the search for new and effective treatments for cough.

Pharmacotherapy of cough-variant asthma

Cough-variant asthma is considered as an asthma subset in which chronic cough is the only symptom. It is believed to be more frequent and, hence, sometimes overdiagnosed in children, and shares with typical asthma eosinophilic airway inflammation and consequent bronchial hyper-responsiveness. Presently available therapies consist of bronchodilators, inhaled or oral corticosteroids, or leukotriene modifiers. However, the long-term efficacy of these agents in adults and children is not known. This review focuses on current therapies used for cough variant asthma, also highlighting potential therapeutic targets for this condition.

Wheeze detection as a measure of bronchial challenge in young children with cough-variant asthma and with classic asthma

AIM

Tracheal and chest auscultation for wheeze and transcutaneous oximetry have both been suggested as outcome measures of bronchial provocation tests in young children. The aims of this study were to compare the sensitivity of these two techniques as endpoints for methacholine challenge in young children with cough-variant asthma (CVA) and with classic asthma (CA), and to investigate whether oxygen saturation levels at the presence of wheezing differ in these two groups.

METHODS

We performed a retrospective analysis of methacholine challenge test data from 4- to 6-year-old children with CVA (n = 41) and from those with CA (n = 53). The challenges used a modified auscultation method that set wheeze detection and/or oxygen desaturation for determining the endpoint.

RESULTS

The frequency of wheeze detection at the endpoint was significantly lower than that of oxygen desaturation (46.3% vs. 78.0%) in the CVA group, which contrasted with findings (75.5% vs. 50.9%) in the CA group. Oxygen saturation levels at the presence of wheezing were significantly lower in the CVA group than in the CA group (94.5 +/- 1.5% vs. 95.9 +/- 1.8%, p = 0.006).

CONCLUSION

Wheeze detection is a less sensitive outcome measure than oxygen desaturation and is associated with a lower oxygen saturation level in young children with CVA, compared to those with CA.

Airway wall thickening in patients with cough variant asthma and nonasthmatic chronic cough

BACKGROUND

Chronic cough, which may be of asthmatic or nonasthmatic origin, is an important clinical issue. Airway inflammation, and remodeling demonstrated by subbasement membrane thickening has been associated with cough variant asthma (CVA) as well as with nonasthmatic chronic cough (NAC). CT studies have shown airway wall thickening in patients with asthma who wheeze. We examined airway wall thickness by CT in adult patients with chronic cough and examined its pathophysiologic implication.

METHODS

Nonsmoking, steroid-naïve patients with CVA (n = 27), NAC (n = 26), and healthy control subjects (n = 15) were studied. Airway dimensions were assessed by a validated CT technique, in which we measured airway wall area (WA) corrected by body surface area (BSA), the ratio of WA to outer wall area (percentage of wall area [WA%]), absolute wall thickness (T)/ square root BSA, and airway luminal area/BSA of a segmental bronchus. Correlations between CT parameters and clinical indexes such as disease duration and cough sensitivity were examined.

RESULTS

In patients with CVA, WA/BSA, WA%, and T/ square root BSA were all significantly greater than those in control subjects. In patients with NAC, WA/BSA and T/ square root BSA were significantly greater than in control subjects. The increase of WA/BSA and T/ square root BSA of NAC patients was less than that of CVA patients. In a subset of patients with NAC, WA% correlated with capsaicin cough sensitivity (n = 9, r = 0.75, p = 0.034).

CONCLUSIONS

Walls of central airways are thickened in patients with CVA, and also to a lesser degree in patients with NAC. Airway wall thickening in NAC may be associated with cough hypersensitivity.

Analysis and evaluation of environmental tobacco smoke exposure as a risk factor for chronic cough

Exposure to environmental tobacco smoke (ETS) and active tobacco smoking has been shown to increase symptoms of bronchial asthma such as bronchoconstriction but effects on other respiratory symptoms remain poorly assessed. Current levels of exposure to tobacco smoke may also be responsible for the development of chronic cough in both children and adults. The present study analyses the effects of tobacco smoke exposure as potential causes of chronic cough. A panel of PubMed-based searches was performed relating the symptom of cough to various forms of tobacco smoke exposure. It was found that especially prenatal and postnatal exposures to ETS have an important influence on children's respiratory health including the symptom of cough. These effects may be prevented if children and pregnant women are protected from exposure to ETS. Whereas the total number of studies adressing the relationship between cough and ETS exposure is relatively small, the present study demonstrated that there is a critical amout of data pointing to a causative role of environmental ETS exposure for the respiratory symptom of cough. Since research efforts have only targeted this effect to a minor extent, future epidemiological and experimental studies are needed to further unravel the relation between ETS and cough.

Cough and asthma

PURPOSE OF REVIEW

The intention of this article is to discuss and place into perspective recent articles on cough and asthma.

RECENT FINDINGS

Asthma continues to be a major diagnosis in most studies of cough. The first prospective study of sub-acute cough demonstrated an asthma incidence lower than that for chronic cough, a logical finding; upper airway cough syndrome often causes cough in the postinfectious state. The first prospective study of cough in infants suggested asthma to be a minor cause of cough in infants, but methodological flaws make the conclusions uncertain. Efforts to separate cough-variant asthma from classic asthma continue. One group has demonstrated that the maximal bronchoconstrictor response in cough-variant asthma is blunted when compared with classic asthma, a possible explanation for the absence of wheeze and dyspnea in cough-variant asthma. Another look at airway resistance showed a less rapid rate of rise in resistance in cough-variant asthma with increasing methacholine dosing than in classic asthma. On the biochemical front, a group has demonstrated differences in vascular endothelial growth factor, which may be the underpinnings of differences between cough-variant asthma and classic asthma.

SUMMARY

Recent data suggest that cough-variant asthma is part of a continuum in the expression of asthma symptoms and in the asthmatic inflammatory response.

Analysis of airway secretions in a model of sulfur dioxide induced chronic obstructive pulmonary disease (COPD)

Hypersecretion and chronic phlegm are major symptoms of chronic obstructive pulmonary disease (COPD) but animal models of COPD with a defined functional hypersecretion have not been established so far. To identify an animal model of combined morphological signs of airway inflammation and functional hypersecretion, rats were continuously exposed to different levels of sulfur dioxide (SO2, 5 ppm, 10 ppm, 20 ppm, 40 ppm, 80 ppm) for 3 (short-term) or 20–25 (long-term) days. Histology revealed a dose-dependent increase in edema formation and inflammatory cell infiltration in short-term-exposed animals. The submucosal edema was replaced by fibrosis after long-term-exposure. The basal secretory activity was only significantly increased in the 20 ppm group. Also, stimulated secretion was significantly increased only after exposure to 20 ppm. BrdU-assays and AgNOR-analysis demonstrated cellular metaplasia and glandular hypertrophy rather than hyperplasia as the underlying morphological correlate of the hypersecretion.

In summary, SO2-exposure can lead to characteristic airway remodeling and changes in mucus secretion in rats. As only long-term exposure to 20 ppm leads to a combination of hypersecretion and airway inflammation, only this mode of exposure should be used to mimic human COPD. Concentrations less or higher than 20 ppm or short term exposure do not induce the respiratory symptom of hypersecretion. The present model may be used to characterize the effects of new compounds on mucus secretion in the background of experimental COPD.