Eosinophilic Bronchial Disorders Presenting Chronic Cough; Atopic Cough, Cough Variant Asthma and Non-Asthmatic Eosinophilic Bronchitis

Fujimura M Kasahara K

doi:10.4172/2157-7412.1000217

Abstract

Chronic persistent non-productive cough is troublesome, whereas productive cough is physiologic and acts to remove abnormal secretions and foreign bodies from the lower respiratory tract. Atopic cough is a new clinical entity for bronchodilator-resistant non-productive cough associated with generalized atopy. Pathological characteristics of atopic cough included trachea bronchitis without Broncho Alveolar Lavage (BAL) eosinophilia, and the physiological characteristics included hypersensitivity of the cough reflex without bronchial hyper reactivity. Patients with atopic cough have eosinophilia of the nebulized hypertonic saline-induced sputum but normal spirometry findings and no variability of Peak Expiratory Flow (PEF). These features of atopic cough are distinct from those of cough variant asthma, since these patients have mild bronchial hyper reactivity and eosinophilic inflammation of the central and peripheral airways and their cough is responsive to bronchodilator treatment. Moreover cough-variant asthma is a precursor of typical asthma, while atopic cough is not, because nearly 30% of patients with cough-variant asthma eventually develop typical asthma but patients with atopic cough do not. Although nearly 60% of patients with atopic cough can be successfully treated with histamine H1-receptor antagonists, but other still require additional corticosteroid therapy because bronchoscopic study indicate that bronchial eosinophilic inflammation is more severe in the H1-receptor antagonist-resistant group. Further investigations are required for the clinical entity of eosinophilic bronchitis without asthma, since it seems to resemble to atopic cough and there seems to be considerable overlap of these two clinical entities.

Highlights

Cough is one of the most frequently encountered symptoms in general practice and the respiratory clinic
Atopic cough Atopic cough is a relatively new clinical entity whose pathogenesis has been investigated since first being reported in 1989 by Fujimura and their colleagues [10,11,12,13,14,15,16,17]. This entity was proposed because the existence of a bronchodilator-resistant non-productive cough associated atopy and characterized by the eosinophilic tracheobronchitis without Broncho Alveolar Lavage (BAL) eosinophilia, cough hypersensitivity without Bronchial Hyper Responsiveness (BHR) [14]
Exhaled Nitric Oxide (NO), a biomarker of eosinophilic inflammation of lower airways, in patients of atopic cough were significantly lower than those in patients with cough variant asthma and bronchial asthma [20]. These findings indicate that in atopic cough, eosinophilic inflammation does not involve the peripheral airways, a finding quite different than in cough-variant asthma [21]

Summary

Introduction

Cough is one of the most frequently encountered symptoms in general practice and the respiratory clinic. Atopic cough Atopic cough is a relatively new clinical entity whose pathogenesis has been investigated since first being reported in 1989 by Fujimura and their colleagues [10,11,12,13,14,15,16,17]. This entity was proposed because the existence of a bronchodilator-resistant non-productive cough associated atopy and characterized by the eosinophilic tracheobronchitis without Broncho Alveolar Lavage (BAL) eosinophilia, cough hypersensitivity without Bronchial Hyper Responsiveness (BHR) [14]. The term “atopic predisposition” does not mean production of Immunoglobrin E (IgE) antibodies in the more narrow sense, and was signified a predisposition to past, present, or future development of an allergic disorder [10,11,12,13,14,15,16,17]

Eosinophilic Disorders

Normal pulmonary function

Findings

Conclusions