Inhibition airway remodeling and transforming growth factor-β1/Smad signaling pathway by astragalus extract in asthmatic mice

Int J Mol Med. 2012 Apr;29(4):564-8. doi: 10.3892/ijmm.2011.868. Epub 2011 Dec 23.

Abstract

Airway remodeling is characterized by airway wall thickening, subepithelial fibrosis, increased smooth muscle mass, angiogenesis and increased mucous glands, which can lead to a chronic and obstinate asthma with pulmonary function depression. In the present study, we investigated whether the astragalus extract inhibits airway remodeling in a mouse asthma model and observed the effects of astragalus extract on the transforming growth factor-β1 (TGF-β1)/Smad signaling pathway in ovalbumin-sensitized mice. Mice were sensitized and challenged by ovalbumin to establish a model of asthma. Treatments included the astragalus extract and budesonide. Lung tissues were obtained for hematoxylin and eosin staining and Periodic acid-Schiff staining after the final ovalbumin challenge. Levels of TGF-β1 were assessed by immunohistology and ELISA, levels of TGF-β1 mRNA were measured by RT-PCR, and levels of P-Smad2/3 and T-Smad2/3 were assessed by western blotting. Astragalus extract and budesonide reduced allergen-induced increases in the thickness of bronchial airway and mucous gland hypertrophy, goblet cell hyperplasia and collagen deposition. Levels of lung TGF-β1, TGF-β1 mRNA and P-Smad2/3 were significantly reduced in mice treated with astragalus extract and budesonide. Astragalus extract improved asthma airway remodeling by inhibiting the expression of the TGF-β1/Smad signaling pathway, and may be a potential drug for the treatment of patients with a severe asthma airway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Airway Remodeling / drug effects*
  • Allergens / adverse effects
  • Animals
  • Asthma / drug therapy*
  • Asthma / physiopathology
  • Astragalus Plant / chemistry*
  • Bronchi / drug effects
  • Bronchi / pathology
  • Budesonide / pharmacology
  • Disease Models, Animal
  • Female
  • Goblet Cells / drug effects
  • Goblet Cells / pathology
  • Lung / chemistry
  • Lung / pathology
  • Mice
  • Mice, Inbred BALB C
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / metabolism
  • Ovalbumin / metabolism
  • Plant Extracts / pharmacology*
  • Signal Transduction / drug effects*
  • Smad Proteins, Receptor-Regulated / genetics
  • Smad Proteins, Receptor-Regulated / metabolism
  • Transforming Growth Factor beta1 / antagonists & inhibitors*
  • Transforming Growth Factor beta1 / genetics
  • Transforming Growth Factor beta1 / metabolism

Substances

  • Allergens
  • Plant Extracts
  • Smad Proteins, Receptor-Regulated
  • Transforming Growth Factor beta1
  • Budesonide
  • Ovalbumin