Clinical science (London, England : 1979) | 26 Jul 2014
A Bergqvist, CK Andersson, M Mori, AF Walls, L Bjermer and JS Erjefält
Real-word evaluation studies have shown that many patients with asthma remain symptomatic despite treatment with inhaled corticosteroids (ICS). As conventional ICS have poor access to the peripheral airways, the aim of present study was to study the relationship between peripheral airway inflammation and clinical control in allergic asthma. Consequently, bronchial and transbronchial biopsies were obtained from poorly controlled asthmatics (n=12, Asthma Control Test (ACT) score <20), well-controlled asthmatics (n=12, ACT score ≥20) and healthy controls (n=8). Tissue sections were immunostained to assess multiple leukocyte populations. To determine the degree of T helper type 2 (Th2) immunity, the logarithmic value of the ratio between Th2 cells/mm2 and Th1 cells/mm2 was used as a surrogate score for Th2 skewed immunity. In the bronchi, the leukocyte infiltration pattern and the Th2-score were similar between well-controlled and poorly controlled asthmatics. In contrast, in the alveolar parenchyma the expression of T helper cells was significant higher in poorly controlled asthmatics compared to well-controlled asthmatics (p<0.01). Furthermore, the alveolar Th2-score was significantly higher in poorly controlled asthma (median 0.4) compared to the controlled patients (median -0.10, p<0.05). Additionally, in contrast to bronchial Th2-score, the alveolar Th2-score correlated significantly with ACT score (rs=-0.56, p<0.01) in the pooled asthma group. Collectively, our data reveal an alveolar Th2-skewed inflammation specifically in asthma patients that are poorly controlled with ICS and suggest that pharmacological targeting of the peripheral airways may be beneficial in this large patient category.
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