Cough variant asthma: lessons learned from deep inspirations

Xiaoqinglong decoction suppresses childhood cough variant asthma and inhibited the body inflammatory response by regulating IL-6/STAT3 signalling pathway

Xiaoqinglong decoction (XQLD) is widely used clinically in the treatment of childhood cough variant asthma (CVA). However, its potential mechanism is still unknown. In the present study, the authors investigate the biological network and signalling pathway of XQLD in treatment of childhood CVA using network pharmacology-based analysis and experimental validation. By using the Bioinformatics Analysis Tool Molecular Mechanism of Traditional Chinese Medicine (BATMAN-TCM) database, the authors confirmed the correlation between XQLD and asthma, and the authors screened 1338 potential target genes of Mahuang and Guizhi, the most active herbs in XQLD. By overlapping "Childhood asthma-related genes" of DisGeNET database, the authors identified 58 intersecting genes of Childhood asthma and 1338 target genes of Mahuang and Guizhi. The intersecting genes were used to construct the protein-to-protein interaction and performed Gene Ontology (GO) functional and the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. Gene Ontology enrichment analysis demonstrated 359 Biological Process terms, 16 Cellular Component terms, and 26 Molecular Function terms. Meantime, 75 terms of Kyoto Encyclopedia of Genes and Genomes signalling pathway were involved in enrichment analysis. These candidates showed a significant correlation with inflammatory response and positive regulation of tyrosine phosphorylation of STAT protein. In addition, XQLD treatment significantly upregulated serum interferon-γ expression, and downregulated serum interlukin-6 expression of CVA mice. XQLD treatment significantly inhibited phosphorylation of STAT3 in bronchial-lung tissues. Our data suggest that XQLD effectively alleviated bronchial-lung tissue damage in CVA mice and inhibited the body inflammatory response by regulating interlukin-6/STAT3 signalling pathway.

Exhaled Nitric Oxide as Biomarker of Type 2 Diseases

Nitric oxide (NO) is a short-lived gas molecule which has been studied for its role as a signaling molecule in the vasculature and later, in a broader view, as a cellular messenger in many other biological processes such as immunity and inflammation, cell survival, apoptosis, and aging. Fractional exhaled nitric oxide (FeNO) is a convenient, easy-to-obtain, and non-invasive method for assessing active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid the diagnosis and monitoring of several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory and/or immunological conditions, including allergic rhinitis, chronic rhinosinusitis with/without nasal polyps, atopic dermatitis, eosinophilic esophagitis, and food allergy. In this review, we aim to provide an extensive overview of the current state of knowledge about FeNO as a biomarker in type 2 inflammation, outlining past and recent data on the application of its measurement in patients affected by a broad variety of atopic/allergic disorders.

WAO-ARIA consensus on chronic cough - Part III: Management strategies in primary and cough-specialty care. Updates in COVID-19

Background

Chronic cough management necessitates a clear integrated care pathway approach. Primary care physicians initially encounter the majority of chronic cough patients, yet their role in proper management can prove challenging due to limited access to advanced diagnostic testing. A multidisciplinary approach involving otolaryngologists and chest physicians, allergists, and gastroenterologists, among others, is central to the optimal diagnosis and treatment of conditions which underly or worsen cough. These include infectious and inflammatory, upper and lower airway pathologies, or gastro-esophageal reflux. Despite the wide armamentarium of ancillary testing conducted in cough multidisciplinary care, such management can improve cough but seldom resolves it completely. This can be due partly to the limited data on the role of tests (eg, spirometry, exhaled nitric oxide), as well as classical pharmacotherapy conducted in multidisciplinary specialties for chronic cough. Other important factors include presence of multiple concomitant cough trigger mechanisms and the central neuronal complexity of chronic cough. Subsequent management conducted by cough specialists aims at control of cough refractory to prior interventions and includes cough-specific behavioral counseling and pharmacotherapy with neuromodulators, among others. Preliminary data on the role of neuromodulators in a proof-of-concept manner are encouraging but lack strong evidence on efficacy and safety.

Objectives

The World Allergy Organization (WAO)/Allergic Rhinitis and its Impact on Asthma (ARIA) Joint Committee on Chronic Cough reviewed the recent literature on management of chronic cough in primary, multidisciplinary, and cough-specialty care. Knowledge gaps in diagnostic testing, classical and neuromodulator pharmacotherapy, in addition to behavioral therapy of chronic cough were also analyzed.

Outcomes

This third part of the WAO/ARIA consensus on chronic cough suggests a management algorithm of chronic cough in an integrated care pathway approach. Insights into the inherent limitations of multidisciplinary cough diagnostic testing, efficacy and safety of currently available antitussive pharmacotherapy, or the recently recognized behavioral therapy, can significantly improve the standards of care in patients with chronic cough.

WAO-ARIA consensus on chronic cough - Part 1: Role of TRP channels in neurogenic inflammation of cough neuronal pathways

BACKGROUND

Cough features a complex peripheral and central neuronal network. The function of the chemosensitive and stretch (afferent) cough receptors is well described but partly understood. It is speculated that chronic cough reflects a neurogenic inflammation of the cough reflex, which becomes hypersensitive. This is mediated by neuromediators, cytokines, inflammatory cells, and a differential expression of neuronal (chemo/stretch) receptors, such as transient receptor potential (TRP) and purinergic P2X ion channels; yet the overall interaction of these mediators in neurogenic inflammation of cough pathways remains unclear.

OBJECTIVES

The World Allergy Organization/Allergic Rhinitis and its Impact on Asthma (WAO/ARIA) Joint Committee on Chronic Cough reviewed the current literature on neuroanatomy and pathophysiology of chronic cough. The role of TRP ion channels in pathogenic mechanisms of the hypersensitive cough reflex was also examined.

OUTCOMES

Chemoreceptors are better studied in cough neuronal pathways compared to stretch receptors, likely due to their anatomical overabundance in the respiratory tract, but also their distinctive functional properties. Central pathways are important in suppressive mechanisms and behavioral/affective aspects of chronic cough. Current evidence strongly suggests neurogenic inflammation induces a hypersensitive cough reflex marked by increased expression of neuromediators, mast cells, and eosinophils, among others. TRP ion channels, mainly TRP V1/A1, are important in the pathogenesis of chronic cough due to their role in mediating chemosensitivity to various endogenous and exogenous triggers, as well as a crosstalk between neurogenic and inflammatory pathways in cough-associated airways diseases.

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.

Herbal Medicine for Adult Patients with Cough Variant Asthma: A Systematic Review and Meta-Analysis

INTRODUCTION

Herbal medicine is commonly used by patients with chronic cough, but the role of herbal medicine for cough variant asthma (CVA) has not yet been clearly defined. For the first time, we performed a meta-analysis to integrate the current evidence of randomized controlled trials (RCTs) on this topic and assess the efficacy of herbal medicine in adults with CVA.

METHODS

A comprehensive search was conducted in electronic databases to identify RCTs of herbal medicine for adult CVA. Cochrane systematic review methods were followed, and the Grading of Recommendations Assessment, Development, and Evaluation was performed to evaluate the quality of evidence.

RESULTS

Twenty-eight RCTs were included. Compared with placebo, moderate-quality evidence from two studies showed that herbal medicine was associated with reduced cough symptom score (CSS) (MD -1.15 points; 95% CI, -1.67 to -0.63) and visual analogue scale (VAS) (MD -1.76 points; 95% CI, -2.66 to -0.86). Compared with montelukast, low- to moderate-quality evidence from 11 studies indicated that herbal medicine was associated with improved Leicester Cough Questionnaire (LCQ) (MD 2.38 points; 95% CI, 1.32 to 3.44), reduced CSS (SMD -0.81 points; 95% CI, -1.09 to -0.53), and VAS (MD -1.34 points; 95% CI, -1.82 to -0.86). There were no significant differences between herbal medicine and ICS plus bronchodilator.

CONCLUSIONS

In adults with CVA, herbal medicine may result in improved quality of life and reduced cough frequency and severity scores compared with placebo or montelukast. Herbal medicine was not better than ICS plus a bronchodilator but the evidence is very uncertain.

Isolated night cough in children: how does it differ from wheeze?

It has been postulated that some children with recurrent cough but no wheeze have a mild form of asthma (cough variant asthma), with similar risk factors and an increased risk of future wheeze.

This longitudinal study compared risk factors for isolated night cough and for wheeze in the Leicester Respiratory Cohort in children aged 1, 4, 6 and 9 years and compared prognosis of children with isolated night cough, children with wheeze and asymptomatic children.

We included 4101 children aged 1 year, 2854 aged 4 years, 2369 aged 6 years and 1688 aged 9 years. The prevalence of isolated night cough was 10% at age 1 year and 18% in older children. Prevalence of wheeze decreased from 35% at 1 year to 13% at 9 years. Although several risk factors were similar for cough and wheeze, day care, reflux and family history of bronchitis were more strongly associated with cough, and male sex and family history of asthma with wheeze. Over one-third of preschool children with cough continued to cough at school age, but their risk of developing wheeze was similar to that of children who were asymptomatic at earlier surveys. Wheeze tracked more strongly throughout childhood than cough.

In conclusion, our study showed that only some risk factors for cough and wheeze were shared but many were not, and there was little evidence for an increased risk of future wheeze in children with isolated night cough. This provides little support for the hypothesis that recurrent cough without wheeze may indicate a variant form of asthma.

Children with isolated night cough do not have an increased risk of future wheeze, and risk factors for cough and wheeze only partially overlap.https://bit.ly/31IbXSC

Methacholine-induced cough as an indicator of bronchodilator-responsive cough

BACKGROUND

Cough variant asthma (CVA) is the most common cause of chronic cough and responds well to bronchodilator therapy. Previous studies on methacholine -induced cough have shown that heightened cough response due to bronchoconstriction is a feature of CVA. The aim of this study was to assess Mch-induced cough as an indicator of bronchodilator-responsive cough (BRC).

METHODS

This was a single-center retrospective study of prolonged/chronic cough cases who underwent evaluation via spirometry, FeNO and bronchial challenge testing using Mch and capsaicin (C5). Resultant bronchoconstriction after Mch challenge was assessed by flow-volume curves measuring the expiratory flow of the partial flow-volume curve 40% above residual volume (PEF₄₀) and FEV₁. BRC was defined as a decrease in cough with bronchodilator therapy by 30% or more on a visual analog scoring scale.

RESULTS

Of the 100 patients evaluated, 63 were diagnosed with BRC. Mch-induced cough at a decrease in PEF₄₀ of 35% (PC₃₅-PEF₄₀) was predictive of BRC on AUROC analysis with an AUC of 0.82 (95% CI 0.73-0.90) and cut-off of 24. The AUC for C5, FeNO and PC₂₀-FEV₁ were 0.65, 0.47, and 0.58, respectively.

CONCLUSION

Compared to C5, FeNO and PC₂₀-FEV₁, Mch-induced cough better supports a diagnosis of BRC.

Repeated bronchoconstriction attenuates the cough response to bronchoconstriction in naïve guinea pigs

BACKGROUND

Cough variant asthma (CVA) is recognized as a precursor of bronchial asthma (BA). However, the cough response to bronchoconstriction differs between these similar diseases. Repeated bronchoconstriction and the resulting imbalance of endogenous lipid mediators may impact the cough response.

METHODS

We investigated the influence of repeated bronchoconstriction on the cough response to bronchoconstriction using naïve guinea pigs. Bronchoconstriction was induced for 3 consecutive days and changes in the cough response and lipid mediators, such as PGE₂, PGI₂, and cysteinyl-LTs (Cys-LTs), in BAL fluid (BALF) were assessed. We investigated the effect of endogenous PGI₂ on the cough response by employing a PGI₂ receptor antagonist. In order to investigate the cough response over a longer period, we re-evaluated the cough response 2 weeks after repeated bronchoconstriction.

RESULTS

The number of coughs induced by bronchoconstriction were significantly decreased by repeated bronchoconstriction. The levels of PGE₂, PGI₂, and Cys-LTs, and the ratio of PGI₂/PGE₂ were significantly increased, following repeated bronchoconstriction. This decrease in the cough response was suppressed by pretreatment with a PGI₂ receptor antagonist. Two weeks after repeated bronchoconstriction, the cough response returned to the same level as before repeated bronchoconstriction along with a concomitant return of lipid mediators, such as PGE₂, PGI₂, and Cys-LTs and the ratio of PGI₂/PGE₂.

CONCLUSIONS

Our results suggest that repeated bronchoconstriction and the resulting imbalance of endogenous lipid mediators contribute to the difference in cough responses to bronchoconstriction in CVA and BA.

Fractional Exhaled Nitric Oxide (FeNO) Combined with Pulmonary Function Parameters Shows Increased Sensitivity and Specificity for the Diagnosis of Cough Variant Asthma in Children

Background

Cough variant asthma in children presents with a dry nonproductive cough. This study aimed to investigate the diagnostic value of fractional exhaled nitric oxide (FeNO) combined with small airway functional parameters in cough variant asthma.

Material/Methods

Children with asthma (n=136) were divided into a cough variant asthma (CVA) group (n=57; mean age, 8.03±2.1 years) and a non-cough variant asthma (nCVA) group (n=79; mean age, 8.61±1.7 years). In both groups, FeNO and other pulmonary function parameters were measured including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), maximum mid-expiratory flow (MMEF), forced expiratory flow (FEF), and maximum expiratory flow at 25%, 50%, and 75% expired volume (MEF25, MEF50, and MEF75). Receiver-operating characteristic (ROC) curve analysis compared the sensitivity and specificity between the diagnostic parameters.

Results

The FeNO values were significantly increased in the CVA group compared with the nCVA group (Z=6.890, p<0.001). The MMEF, MEF25, MEF50, and MEF75 values were significantly lower in the CVA group compared with the nCVA group (p=0.000, p=0.014, p=0.000, and p=0.000, respectively). The FeNO values were negatively correlated with MEF25, MEF50, and MMEF (r=−0.334, r=−0.257 and r=−0.276, respectively). FeNO was significantly more efficient diagnosing cough variant asthma comparing with pulmonary parameters (p<0.05), and was most sensitive and specific when combined with MMEF/MEF50 compared with single diagnostic parameters (p<0.05).

Conclusions

FeNO combined with pulmonary function parameters of MMEF/MEF50 showed increased sensitivity and specificity for the diagnosis of cough variant asthma.

[From acute cough to chronic cough in adults: Overview on a common reason for consultation]

Cough is divided into two categories: acute cough lasting less than 3 weeks, and chronic cough lasting more than 8 weeks. Acute cough is usually triggered by a viral infection of the upper airways. Evidence of treatment effectiveness is low and management of acute cough is complex in clinical practice. Chronic cough is a common reason for consultation in medicine. The most frequent causes are upper airway diseases, gastroesophageal reflux disease, asthma, eosinophilic bronchitis, and drugs. Before investigation, smoking cessation and drug withdrawal must be achieved for 4 to 6 weeks. Once this step is completed, simple investigations have to be performed in order to find common causes of chronic cough (questioning, physical examination, spirometry, chest X-ray). If no causes have been identified or cough remains despite optimal treatment, exhaustive exploration has to be performed to rule out rare causes. A chronic cough hypersensitivity syndrome is suggested if any causes have been found despite exhaustive assessment or if cough remains with optimal treatments. This syndrome is characterized by an increase in the sensitivity of cough peripheral receptors and is not sensitive to usual therapies. The therapeutic options are limited but innovative treatments such as P2X3 receptor antagonists are in development.

Functional changes of airway epithelial cells and mitochondria in rat models of asthenic lung and phlegm blocking combined with cough variant asthma

The aim of this study was to investigated the functional changes of airway epithelial cells and mitochondria in rat models of asthenic lung and phlegm blocking combined with cough variant asthma (CVA). Sixteen Sprague-Dawley rats were randomly divided into two groups: Control and model group, with 8 rats in each group. On the basis of the CVA rat model induced and sensitized by ovalbumin and aluminum hydroxide, the rat models with asthenic lung and phlegm blocking combined with CVA were established via smoking stimulation. The rats in the control group were injected with equivalent normal saline. All rats were sacrificed after the model was successfully prepared. The lung histopathological sections of the two groups of rats were observed, and respiratory control ratio (RCR) of mitochondria and membrane potential changes were compared. The results showed that the rats in the model group had tracheal structure abnormities, epithelial cell damages, cilia structure defects, capillary injection, alveolar exudates, and inflammatory cells compared to those in the control group. RCR of mitochondria and membrane potential of rats in the model group were significantly lower than those of rats in the control group (P<0.05). Damaged lung tissue and decreased mitochondrial activity and membrane potential are detected in the rat models of asthenic lung and phlegm blocking combined with CVA.

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.

Role of prostaglandin E2 in bronchoconstriction-triggered cough response in guinea pigs

A feature of cough variant asthma is a heightened cough response to bronchoconstriction. The mediators of this response are unknown. This study was designed to elucidate the role of lipid mediators in bronchoconstriction-triggered cough response in an experimental animal model. We examined the influence of bronchoconstriction on cell components and mediators including prostaglandin E₂ (PGE₂) in bronchoalveolar lavage fluid (BALF). We studied the cough response to bronchoconstriction (CRB) by measuring the correlation between the increase in enhanced pause (Penh), an index of bronchoconstriction, and cough counts induced by methacholine (Mch) inhalation in conscious guinea pigs. We then examined the effects of intraperitoneal pretreatment with 16, 16-dimethyl-prostaglandin E₂ (dm-PGE₂) on CRB and cough counts. The total number of cells and cell components in the BALF were not influenced by bronchoconstriction. While levels of PGE₂, prostaglandin I₂, and cysteinyl leukotrienes were significantly increased, levels of prostaglandin D₂, thromboxane B₂, and substance P in the BALF were not. Dm-PGE₂ significantly decreased the Mch-induced increase in Penh. Following bronchoconstriction by additional Mch inhalation, dm-PGE₂ produced an increase in CRB and cough counts in a dose-dependent manner. Additionally, the heightened CRB following dm-PGE₂ treatment was suppressed by pretreatment with PGE₂ receptor (E-prostanoid EP) -1 and EP-3 antagonists in a dose-dependent manner, but not by EP-2 and EP-4 antagonists. The EP-1 antagonist also decreased cough counts. These results suggest that PGE₂ acts as an exacerbating factor for bronchoconstriction-triggered cough. EP1 and EP3 may provide new therapeutic targets for cough variant asthma.

Bronchoprotective effect of deep inspirations in cough variant asthma: A distinguishing feature in the spectrum of airway disease?

PURPOSE

To assess the effect of deep inspirations (DIs) on airway behaviour in individuals with classic asthma (CA), cough variant asthma (CVA), and methacholine (MCh)-induced cough but normal airway sensitivity (COUGH) during bronchoprovocation.

METHODS

Twenty-five adults (18 female; 44.8 ± 12.3 years (Mean ± SD); n = 9 CA, n = 9 CVA, and n = 7 COUGH) completed two single-dose MCh challenges, with and without DIs. Bronchoprotection was assessed by comparing changes in bronchoconstriction (FEV₁, FVC, FEV₁/FVC, FEF₅₀, FEF_25-75), gas trapping (RV, RV/TLC) and impulse oscillometry (IOS) measurements.

RESULTS

The% changes in FEV₁ with and without DIs were not significantly different within any group. Decreases in FEF₅₀ and FEF_25-75 were greater in CA (p = 0.041 and p = 0.029), decreases in FVC (% predicted) and FEV₁/FVC(%) were less in CVA (p = 0.048 and p = 0.010), and increases in RV (L) and RV/TLC (% predicted) were less in COUGH (p = 0.007 and p = 0.028), respectively. No differences in IOS measurements were noted.

CONCLUSIONS

DIs triggered bronchoconstriction in CA, bronchoprotection in CVA, and prevented gas trapping in COUGH.

Causes of Chronic Cough in Non-smoking Patients

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

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.

Chronic cough - assessment of treatment efficacy based on two questionnaires

INTRODUCTION

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanisms of cough

PURPOSE OF REVIEW

To review recent developments in the mechanisms of chronic cough.

RECENT FINDINGS

Although cough prevalence is similar across the world, there are significant regional differences in the diseases associated with cough. This may represent regional differences in diet, environmental exposure, and diagnostic assessment and labelling. Cough can be reliably measured using several validated questionnaires and objective tools that monitor cough frequency and cough reflex sensitivity. Cough with eosinophilic bronchitis responds to anti-inflammatory therapy with corticosteroids and montelukast. The absence of airway hyperresponsiveness may be because of the release of a bronchoprotective mediator, prostaglandin E2. Cough with neutrophilic bronchitis is associated with rhinitis and gastroesophageal reflux disease. Laryngeal hypersensitivity (LHS) is an important new concept that explains cough mechanisms, identifies potentially new pharmacotherapies that target neural pathways and also transient receptor channels, and demonstrates how behavioural therapies can be effective in refractory cough. The concept also explains symptoms in a variety of related syndromes such as vocal cord dysfunction.

SUMMARY

New insights into cough mechanisms that focus on LHS help explain cough symptoms and the place of effective therapies including speech pathology intervention and neuromodulators.

Comparison of phenotypes of childhood wheeze and cough in 2 independent cohorts

BACKGROUND

Among children with wheeze and recurrent cough there is great variation in clinical presentation and time course of the disease. We previously distinguished 5 phenotypes of wheeze and cough in early childhood by applying latent class analysis to longitudinal data from a population-based cohort (original cohort).

OBJECTIVE

To validate previously identified phenotypes of childhood cough and wheeze in an independent cohort.

METHODS

We included 903 children reporting wheeze or recurrent cough from an independent population-based cohort (validation cohort). As in the original cohort, we used latent class analysis to identify phenotypes on the basis of symptoms of wheeze and cough at 2 time points (preschool and school age) and objective measurements of atopy, lung function, and airway responsiveness (school age). Prognostic outcomes (wheeze, bronchodilator use, cough apart from colds) 5 years later were compared across phenotypes.

RESULTS

When using a 5-phenotype model, the analysis distinguished 3 phenotypes of wheeze and 2 of cough as in the original cohort. Two phenotypes were closely similar in both cohorts: Atopic persistent wheeze (persistent multiple trigger wheeze and chronic cough, atopy and reduced lung function, poor prognosis) and transient viral wheeze (early-onset transient wheeze with viral triggers, favorable prognosis). The other phenotypes differed more between cohorts. These differences might be explained by differences in age at measurements.

CONCLUSIONS

Applying the same method to 2 different cohorts, we consistently identified 2 phenotypes of wheeze (atopic persistent wheeze, transient viral wheeze), suggesting that these represent distinct disease processes. Differences found in other phenotypes suggest that the age when features are assessed is critical and should be considered carefully when defining phenotypes.