Transforming growth factor-β3/Smad2/Smad3 signaling pathway inhibition and autophagy by the Yunpi-Xiefei-Huatan decoction ameliorated airway inflammation and mucus hypersecretion in asthmatic rats.

ETHNOPHARMACOLOGICAL RELEVANCE

The Yunpi-Xiefei-Huatan decoction (YXHD) is a traditional Chinese medicine that can improve asthma-related symptoms, including cough, phlegm in the throat, and shortness of breath. However, the YXHD mechanism on asthma has not yet been elucidated.

STUDY AIM

The aim of this study is to investigate the effect of YXHD on airway inflammation, mucus hypersecretion, and autophagy modulation in asthma.

MATERIALS AND METHODS

The YXHD chemical constituents were observed and analyzed using high-performance liquid chromatography-mass spectrometry. Ovalbumin sensitization and stimulation were used to establish an asthma rat model. A total of 80 Sprague-Dawley (SD) rats were segmented into eight groups at random: a Normal (NC) group, a Model (Mod) group, a YXHD low-dose group (10 g/kg/d), a YXHD moderate-dose group (20 g/kg/d), a YXHD high-dose group (40 g/kg/d), a Rapamycin group (4 mg/kg/d), a 3-methyladenine (3-MA) group (15 mg/kg/d), and a Dexamethasone (DEX) group (0.5 mg/kg/d). Whole-body plethysmography (WBP) detection was used to evaluate airway hyperresponsiveness. An enzyme-linked immunosorbent assay (ELISA) was used to detect inflammatory factors in the peripheral blood. Inflammatory cells in the bronchoalveolar lavage fluid (BALF) were also counted. Pathological changes in the lung tissues were marked using hematoxylin and eosin (H&E) staining and periodic acid-Schiff (PAS) staining. The localization of MUC5AC and the co-localization of LC3B + MUC5AC were observed using immunofluorescence. The expressions of autophagy and the TGF-β3/Smad2/Smad3 pathway in the lung tissues were detected using a Western blot assay (WB) and qPCR, and the autophagosomes in the lung tissues were detected using a transmission electron microscope (TEM).

RESULTS

Twenty signal peaks were identified using ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) technology. The TGF-β3/Smad2/Smad3 signal pathway activation was induced using ovalbumin (OVA) exposure in the rats. The upregulated expression of autophagy, enhanced MUC5AC fluorescence and LC3B fluorescence, and their co-localized expression in the airway epithelium indicated inflammatory cell infiltration and excessive mucus secretion in the lungs. This resulted in airway hyper-responsiveness. The YXHD inhibited the activation of the TGF-β3/Smad2/Smad3 signaling pathway, and autophagy expression reduced inflammatory factors, abnormal mucus secretion, and airway hyperresponsiveness.

CONCLUSION

The YXHD improved lung function, relieved lung inflammation, and inhibited airway mucus secretions in asthmatic rat models. Its mechanism may have been related to the blockage of the TGF-β3/Smad2/Smad3 signaling pathway and autophagy downregulation.