Non-astmatic Eosinophilic Bronchitis

Abstract

Non-asthmatic eosinophilic bronchitis (NAEB) is a chronic disease and was first described in a small group of patients by Gibson et al. [1,2] in a relatively recent date. Without bronchospasm, it is defined as eosinophilic inflammation of the respiratory tract and is usually associated with eosinophilia in sputum. It is one of the most important causes of chronic cough [3].When a cough lasting longer than 8 weeks is detected in clinical practice; if chest X-ray is normal, this situation is defined as chronic cough. Chronic cough is a common cause of complaints all over the world, especially at the centers giving outpatient care, and is responsible for about 40% of the applications [4][5][6]. However, the cause(s) leading to this condition can be detected in 75-90% [7][8][9]. NAEB is a disease that should be remembered in the differential diagnosis of chronic cough but it is often ignored [10]. Because the systematic examination of bronchial inflammation can be made rarely, it is probably diagnosed less than it exists [11]. When the other causes that may lead to chronic cough are eliminated in patients applying with the complaint of chronic cough, NAEB should be taken into consideration [12][13][14][15][16][17][18][19].The purpose of this article is to make it possible to consider the differential diagnosis of patients with chronic cough by drawing attention to NAEB, and to compile and present the literature data that is relatively limited. ETIOLOGYAlthough the etiology of NAEB is not clear yet, environmental or occupational factors may be responsible for this situation in some of the patients. In a significant proportion of the diagnosed patients, occupational dust exposure was considered to be possibly etiologically responsible. For this reason, the possibility of occupation-related causes should be considered in patients with chronic cough due to NAEB [20]. Especially resin hardener, welding fume and formaldehyde exposures have been shown to lead to NAEB [21][22][23][24]. Non-asthmatic eosinophilic bronchitis (NAEB) is eosinophilic inflammation of the respiratory tract, without any bronchospasm. In this article, we want to draw attention to the NAEB. It should also be considered in differential diagnosis of chronic cough. Eosinophilia is present in all induced or spontaneous sputum samples of NAEB patients. NAEB patients and asthmatic patients have similar airway inflammation. Remarkably, NAEB mainly occurs in the lower airways. Unlike asthma, mast cells in NAEB are active in the bronchial epithelium. Diagnosis is based on the clinical, radiological, and spirometric measurements of other causes of chronic cough (Post-nasal discharge syndrome, asthma, gastroesophageal reflux etc.) and the assessment of inflammation in the lower respiratory tract. Airway inflammation can be assessed by sputum induction. The main treatment is anti-inflammatory therapy with inhaled corticosteroids and taking protective measures if inflammation is due to occupational exposure or allergen inhalation. If NAEB is untreated, it may be ...

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“…Epidemiological data suggest that non-asthmatic eosinophilic bronchitis (NAEB) represents up to 35% of chronic cough patients in Asia 121 , 122 and can involve children according to a large series. 123 Clinically, NAEB is a cough phenotype which lacks bronchoconstriction and bronchial hyperresponsiveness 124 , 125 ( Table 1 ). Similar to asthma, it is characterized by airway eosinophilia in induced sputum and responds well to anti-inflammatory therapy.…”