The Experimental Study About Effect Of Budesonide Treatment On Asthmatic Mice

Objective:To investigate the effects of Budesonide treatment on airway inflammation, airway remodeling, pulmonary surfactant system, TGFβsignal transduction pathway and their relationships in asthmatic mice.Methods:Forty female KM mice were divided into four groups: asthmatic model group(group A), therapeutic control group(group B), Budesonide treated group(group C), normal control group(group D), with 10 mice in each group. Mice were sensitized on days 0 and 14 by Ovalbumin(OVA) intraperitoneal injection and challenged from days 21 to 35 by OVA repeated inhalation to establish a murine model of asthma. To assess the effect of Budesonide on asthmatic mice, animals were treated with aerosolized Budesonide(1mg per day) before OVA challenge. Twenty-four hours after the final antigen challenge, all mice were sacrificed. The levels of TGF-β₁, IL-12 and IL-13 in bronchoalveolar lavage fluid(BALF) were analyzed by ELISA. Eosinophil(EOS) count, degree of mucus secretion and area of collagen deposition around airway were measured by HE, PAS, VG staining and computerized image analysis system. The expressions of TGF-β₁, TGFβtypeâ… receptor, TGFβtypeâ…¡receptor, Smad2/3, Smad4, Smad7, SP-A, SP-B, and Dendritic cell(DC) count were measured by immunochemistry technique and computerized image analysis system. The pathologic changes of type II pneumocyte were observed by electron microscope.Results:1. In group A, EOS count, DC count and the degree of mucus secretion around airway were increased when compared with group D, but show no difference when compared with group B. In group C, EOS count, DC count and the degree of mucus secretion around airway were decreased when compared with group A.2. In group A, the levels of IL-12, IL-13 and TGF-β₁ in BALF show no difference when compared with group B. The levels of IL-13 and TGF-β₁ were increased, but the levels of IL-12 were decreased when compared with group D. In group C, the levels of IL-13 were decreased when compared with group A. However, the levels of IL-12 and TGF-β₁ show no difference when compared with group A.3. In group A, the expressions of TGF-β₁ and the areas of collagen deposition around airway were increased when compared with group D, but show no difference when compared with group B. In group C, the areas of collagen deposition around airway were decreased when compared with group A, but increased when compared with group D. However, the expressions of TGF-β₁ show no difference when compared with group A. A positive correlation between TGF-β₁ and the areas of collagen deposition around airway was observed in group A.4. In group A, The expressions of TGF-β₁, TGFβtypeâ… receptor, TGFβtype II receptor, Smad2/3, Smad4 and Smad7 around airway show no difference when compared with group B. In group C, The expressions of TGFβtypeâ… receptor were decreased, but the expressions of Smad7 were increased when compared with group A. However, the expressions of TGFβtype II receptor, Smad2/3 and Smad4 show no difference when compared with group A. A positive correlation between TGFβtypeâ… r eceptor and the areas of collagen deposition around airway was observed in group A. A negative correlation between Smad7 and the areas of collagen deposition around airway was observed in group A.5. In group A, the expressions of SP-A and SP-B around alveolar epithelium were decreased when compared with group D, but show no difference when compared with group B. In group C, the expressions of SP-A and SP-B were increased when compared with group A, but decreased when compared with group D. The expressions of TGF-β₁ and TGFβtypeâ… r eceptor were negative correlation with the expressions of SP-A and SP-B in group A. The expressions of Smad7 were positive correlation with the expressions of SP-A and SP-B in group A.6. In group A, the ultrastructural changes of type II pneumocyte included evacuation of lamellar bodies and partial cell desquamation. The above changes were improved in group C.Conclusion:1. Early Budesonide inhaled treatment inhibits the development of airway inflammation through inhibition of imbalance of IL-12/IL-13 and reduction of EOS infiltration, mucus secretion and DC count around airway. However, Budesonide treatment can not inhibit the overproduction of TGF-β₁ in asthmatic mice.2. Early Budesonide inhaled treatment inhibits TGFβ-induced airway remodeling through up-regulation of Smad7 expression and down-regulation of TGFβtypeâ… receptor expression, but only partially inhibits airway remodeling in asthmatic mice.3. Early Budesonide inhaled treatment inhibits TGFβ-induced reduction of SP-A and SP-B expressions through inhibition of active TGFβ/Smad signal transduction in asthmatic mice.