Combination of glycopyrronium and indacaterol inhibits carbachol-induced ERK5 signal in fibrotic processes

Background

Airway fibrosis is one of the pathological features of chronic obstructive pulmonary disease (COPD), and recent studies revealed that acetylcholine plays an important role in the development of airway remodeling by stimulating proliferation and collagen synthesis of lung fibroblasts. This study was designed to examine the effects of a long-acting muscarinic receptor antagonist (LAMA) glycopyrronium and a long-acting β2 adrenergic receptor agonist (LABA) indacaterol on acetylcholine-mediated fibrotic responses in lung fibroblasts.

Methods

After carbachol (CCh) or transforming growth factor-β1 (TGF-β1) exposure, the response to glycopyrronium and indacaterol was determined in vitro in fibroblasts isolated from mild-to-moderate COPD lung tissue. The ability of fibroblasts to mediate the contraction of collagen gels was assessed. The expression of α-smooth muscle actin (α-SMA) and the phosphorylation of extracellular-signal-regulated kinase 5 (ERK5) were determined by immunoblot. TGF-β1 was quantified by ELISA and acetylcholine was quantified by liquid chromatography tandem-mass spectrometry.

Results

CCh stimulated fibroblast-mediated collagen gel contraction and α-SMA expression and TGF-β1 release by fibroblasts. Blockade of autocrine TGF-β1 attenuated CCh-mediated fibrotic responses, while TGF-β1 did not stimulate acetylcholine release. Glycopyrronium plus indacaterol significantly attenuated CCh- and TGF-β1-mediated fibrotic responses through inhibition of ERK5 phosphorylation. Notably, the magnitudes of CCh- and TGF-β1-stimulated gel contraction, CCh-induced TGF-β1 release, and ERK5 phosphorylation were greater in fibroblasts isolated from COPD subjects than in those from non-smokers.

Conclusions

CCh induced TGF-β1 self-sustaining signaling loops by potentiating ERK5 signaling and promoted myofibroblast activity. This autocrine signaling mechanism may be an attractive therapeutic target to block the fibrotic response, which was modulated by the combination of glycopyrronium and indacaterol.

Comparison of airway dimensions with once daily tiotropium plus indacaterol versus twice daily Advair(®) in chronic obstructive pulmonary disease

BACKGROUND

Current guidelines recommend combining long-acting bronchodilators with different modes of action in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). We evaluated the effects of airway dimensions and pulmonary function with tiotropium plus indacaterol versus Advair(®).

METHODS

Subjects (n = 46) were randomized to receive tiotropium (18 μg once daily) plus indacaterol (150 μg once daily) or Advair(®) (50/250 μg twice daily) for 16 weeks. Airway geometry was determined by quantitative computed tomography (luminal area, Ai; total area of the airway, Ao; wall area, WA; and percentage wall area, WA/Ao and wall thickness, T). Spirometry (forced expiratory volume in 1 s, FEV1; forced vital capacity, FVC and inspiratory capacity, IC) and St. George's Respiratory Questionnaire (SGRQ) were evaluated.

RESULTS

Tiotropium plus indacaterol significantly increased CT-indices including Ai corrected for body surface area (Ai/BSA), and decreased WA/BSA, WA/Ao and T/√BSA compared with Advair(®) (p < 0.05, respectively). In physiological parameters, mean difference in IC was significantly higher under treatment with tiotropium plus indacaterol than Advair(®) (p < 0.05). The changes in Ai/BSA, WA/BSA, WA/Ao and T/√BSA were significantly correlated with changes in IC (r = 0.535, p = 0.011; r = -0.688, p < 0.001; r = -0.555, p = 0.002 and r = -0.542, p = 0.007; respectively). There were more significant improvements in SGRQ scores after treatment with tiotropium plus indacaterol than Advair(®).

CONCLUSIONS

These findings suggest that dual bronchodilation with tiotropium plus indacaterol is superior in airway geometry and lung function compared with Advair(®) in COPD.