Airway hyperresponsiveness and chronic obstructive pulmonary disease outcomes

[Extracellular molecules controlling the contraction of airway smooth muscle and their potential contribution to bronchial hyperresponsiveness]

INTRODUCTION

A significant portion of symptoms in some lung diseases results from an excessive constriction of airways due to the contraction of smooth muscle and bronchial hyperresponsiveness. A better understanding of the extracellular molecules that control smooth muscle contractility is necessary to identify the underlying causes of the problem.

STATE OF KNOWLEDGE

Almost a hundred molecules, some of which newly identified, influence the contractility of airway smooth muscle. While some molecules activate the contraction, others activate the relaxation, thus acting directly as bronchoconstrictors and bronchodilators, respectively. Other molecules do not affect contraction directly but rather influence it indirectly by modifying the effect of bronchoconstrictors and bronchodilators. These are called bronchomodulators. Some of these bronchomodulators increase the contractile effect of bronchoconstrictors and could thus contribute to bronchial hyperresponsiveness.

PROSPECTS

Considering the high number of molecules potentially involved, as well as the level of functional overlap between some of them, identifying the extracellular molecules responsible for excessive airway constriction in a patient is a major contemporary challenge.

Serum IL-8 and VEGFA are Two Promising Diagnostic Biomarkers of Asthma-COPD Overlap Syndrome

Background

Asthma-COPD overlap (ACO; previously referred to as asthma-COPD overlap syndrome) is characterized by persistent airflow limitation consistent with COPD, together with several distinguishing features of asthma. Asthma-COPD overlap syndrome is a condition of mixing symptoms of asthma and COPD, because of its complexity, it is difficult to find effective diagnostic markers in clinic.

Purpose

Our aims were to detect the expression of serum cytokines in patients with asthma, explore the diagnostic potential of differential serum cytokines in ACOS.

Patients and Methods

Ninety asthmatic patients were divided into ACOS group and non-ACOS group according to the major and minor criteria of ACOS, 15 kinds of cytokines including IL-3, IL-4, IL-8, IL-9, IL-13, IL-17A, VEGFA, VEGFC, VEGFD, bFGF, Fit-1 PIGF, Tie-2 were detected by MSD, and IL-27 and TGF-beta were determined by ELISA assay.

Results

The serum levels of IL-9, VEGFA and PIGF in patients with ACOS were significantly higher than those in non-ACOS group (P<0.05, respectively), while the level of IL-8 and IL-17A in subjects with ACOS was lower than that in the non-ACOS group (P<0.05, respectively). We analyzed the correlation between several difference factors and FEV1/FVC% in the ACOS group, found VEGFA was negatively correlated with FEV1/FVC%, while IL-8 and IL-17A were positively correlated with FEV1/FVC%. Finally, three correlation factors were analyzed by ROC curve for the occurrence of ACOS.

Conclusion

The results suggested that IL-8 was highly sensitive and VEGFA was highly specificity, both of which could be used as biomarkers for the diagnosis of ACOS.

Functional contribution of sphingosine-1-phosphate to airway pathology in cigarette smoke-exposed mice

BACKGROUND AND PURPOSE

A critical role for sphingosine kinase/sphingosine-1-phosphate (S1P) pathway in the control of airway function has been demonstrated in respiratory diseases. Here, we address S1P contribution in a mouse model of mild chronic obstructive pulmonary disease (COPD).

EXPERIMENTAL APPROACH

C57BL/6J mice have been exposed to room air or cigarette smoke up to 11 months and killed at different time points. Functional and molecular studies have been performed.

KEY RESULTS

Cigarette smoke caused emphysematous changes throughout the lung parenchyma coupled to a progressive collagen deposition in both peribronchiolar and peribronchial areas. The high and low airways showed an increased reactivity to cholinergic stimulation and α-smooth muscle actin overexpression. Similarly, an increase in airway reactivity and lung resistances following S1P challenge occurred in smoking mice. A high expression of S1P, Sph-K₂ , and S1P receptors (S1P₂ and S1P₃ ) has been detected in the lung of smoking mice. Sphingosine kinases inhibition reversed the increased cholinergic response in airways of smoking mice.

CONCLUSIONS AND IMPLICATIONS

S1P signalling up-regulation follows the disease progression in smoking mice and is involved in the development of airway hyperresponsiveness. Our study defines a therapeutic potential for S1P inhibitors in management of airways hyperresponsiveness associated to emphysema in smokers with both asthma and COPD.

Airway responsiveness to methacholine and incidence of COPD: an international prospective cohort study

Background

It has been debated, but not yet established, whether increased airway responsiveness can predict COPD. Recognising this link may help in identifying subjects at risk.

Objective

We studied prospectively whether airway responsiveness is associated with the risk of developing COPD.

Methods

We pooled data from two multicentre cohort studies that collected data from three time points using similar methods (European Community Respiratory Health Survey and Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults). We classified subjects (median age 37 years, 1st–3rd quartiles: 29–44) by their level of airway responsiveness using quintiles of methacholine dose–response slope at the first examination (1991–1994). Then, we excluded subjects with airflow obstruction at the second examination (1999–2003) and analysed incidence of COPD (postbronchodilator FEV₁/FVC below the lower limit of normal) at the third examination (2010–2014) as a function of responsiveness, adjusting for sex, age, education, body mass index, history of asthma, smoking, occupational exposures and indicators of airway calibre.

Results

We observed 108 new cases of COPD among 4205 subjects during a median time of 9 years. Compared with the least responsive group (incidence rate 0.6 per 1000/year), adjusted incidence rate ratios for COPD ranged from 1.79 (95% CI 0.52 to 6.13) to 8.91 (95% CI 3.67 to 21.66) for increasing airway responsiveness. Similar dose–response associations were observed between smokers and non-smokers, and stronger associations were found among subjects without a history of asthma or asthma-like symptoms.

Conclusions

Our study suggests that increased airway responsiveness is an independent risk factor for COPD. Further research should clarify whether early treatment in patients with high responsiveness can slow down disease progression.