Tiotropium bromide has a more potent effect than corticosteroid in the acute neutrophilic asthma mouse model.

Background Neutrophilic asthma (NeuA) is usually corticosteroid resistant. Tiotropium bromide (TIO) is a bronchodilator that is used as an add-on therapy to the inhaled corticosteroid and long-acting β2 agonist in asthma. However, the role of TIO in NeuA is not fully known. We conducted this study to evaluate the effect of TIO on NeuA comparing with that of corticosteroids. Methods C57BL/6 female mice were sensitized with ovalbumin and lipopolysaccharide for inducing neutrophilic inflammation. Dexamethasone (DEX) was administered on days 14, 17, 20, and 23. TIO was inhaled on days 21, 21, and 23. On day 24, the mice were sacrificed. Airway hyper-responsiveness (AHR), the level of cytokine in the bronchoalveolar lavage (BAL) and lung homogenates, and the lung tissue histopathology were compared between the groups. Results Neutrophil counts, T helper 2 cells (TH2)/TH17 cytokines, and pro-inflammatory cytokine in BAL fluid were elevated in the NeuA group. TIO group showed lower total cells, neutrophil counts, and eosinophil counts in BAL fluid compared to those of DEX group (p < 0.001, p < 0.05, and p < 0.001, each). Airway resistance was attenuated in the TIO group, which was elevated in the NeuA group (p < 0.001). Total protein, interleukin (IL)-5, and IL-17A in the BAL fluid were lower in the TIO group than those of the NeuA group (p < 0.05, each). Conclusions TIO showed more potent effects than DEX on improving airway inflammation and attenuating airway resistance in NeuA.