RESUMO
Background: Thymic stromal lymphopoietin (TSLP) orchestrates eosinophilic inflammation, which may increase during asthma exacerbations. In contrast, microRNA-1 (miR-1) inhibits TSLP-mediated eosinophil trafficking in lung endothelium. Whether the balance of TSLP and miR-1 levels determines the response to oral corticosteroids (OCSs) during the treatment of asthma exacerbations remains unknown. Objective: Our aim was to investigate the involvement of TSLP/miR-1 axis in inflammatory response to OCS treatment for asthma exacerbations. Methods: We measured the concentrations of TSLP and other inflammatory cytokines and miR-1 expression during acute asthma exacerbations treated with standard OCSs in a real-life setting. A total of 28 consecutive patients with acute asthma exacerbations treated with OCS (prednisolone 30 mg/d) for 1 week at the emergency department were studied prospectively. Steroid responders were identified by a significant reduction in blood eosinophil counts, whereas paradoxical responders (PRs) showed no markedly decreased or even increased absolute blood eosinophil counts after OCS treatment. Differential white blood cell counts, blood cytokine levels, and miR-1 expression within and between groups were compared before and after OCS treatment. The baseline cytokine concentrations in both groups were compared with those of patients with stable asthma. Results: OCS treatment significantly reduced TSLP levels in steroid responders, whereas this effect did not occur in PRs (P = .006 and P = .742, respectively). In contrast, miR-1 expression was unchanged in steroid responders in response to OCS, whereas it was markedly reduced in the PRs, despite higher expression at baseline than in patients with stable asthma, which may account for slower resolution of the exacerbation. Conclusions: In some asthmatic patients with acute exacerbations who do not suppress eosinophils after a course of OCS, there is a paradoxical decrease in plasma miR-1 level and increase in TSLP level versus in steroid responders, which may result in slower clinical recovery.
RESUMO
Objective: Transforming growth factor-ß-associated kinase 1 (TAK1) mediates non-canonical TGF-ß signalling by promoting adhesive, migratory, proliferative and contractile responses of fibroblasts to TGF-ß1. However, TAK1 expression status in asthmatic patients with or without fixed airway obstruction (FAO) is unknown. Patients and Methods: A total of 60 adult asthmatics with FAO were recruited and compared to 43 those without FAO (nFAO). TGF-ß1 concentrations, and total TAK1 and phosphorylated TAK1 (p-TAK1) levels were determined in sputum supernatants, cytospin, and whole cell lysate by ELISA, immunocytochemistry, and Western blot analysis, respectively, in asthmatics with and without FAO. Results: Asthmatic patients with FAO had much greater sputum TGF-ß1 concentrations than those without FAO. This was independent of airway eosinophilia as there was no significant difference in TGF-ß1 levels between high and low eosinophil counts within FAO and nFAO groups. In contrast, patients with FAO in the presence of sputum eosinophilia had greater expression of TAK1 and p-TAK1 than those without sputum eosinophilia (P=0.0032 and P=0.0061, respectively). The Western Blot data of total TAK1 and p-TAK1 were consistent with the immunocytochemistry, showing upregulation in all sputum cell types (neutrophils, eosinophils, macrophages, lymphocytes and airway epithelial cells). In addition, total TAK1 expression negatively correlated with pre- and post-bronchodilator FEV1/FVC ratio. Conclusion: TAK1 may play a key role in asthmatic patients with fixed airway obstruction, which was independent of eosinophilic airway inflammation. The interruption of TAK1 might have favourable clinical impact.
