| objective:Glucocorticoids are widely regarded as the most effective vailable treatment for asthma, inhaled corticosteroids is still a major treatment to control asthma airway inflammation. The aim of the present study was to investigate the effect of inhaled budesonide on the antibacterial host defense of asthma through the establishment of Pseudomonas aeruginosa infection model in mice, and explore the relevant mechanism in the process. Methods:50 female mice(6-7 wk old) were randomly divided into control group, asthma group, asthma and infection group, inhalation of the budesonide group, inhaled budesonide and infection group, each group has 10 mice. mice were sensitized and challenged with ovalbumin (OVA),control group were treated with the same dose of PBS. Followed by inhaled budesonide and infection, mice were killed, the collection and separation of serum and lung tissue removed were kept. Lung homogenates were plated for bacterial quantification. The HE staining of lung tissue sections were examined and divided into four scoring groups under light microscopy to analysis the level of invasion of inflammatory cells. The protein expression of cathelin-related antimicrobial peptide(CRAMP) was determined by immunohistochemical staining and western blot. The levels of the cytokines IL-4 and IFN-y in blood serum were measured by enzyme-linked immunosorbent assay. Results:1. Murine general observation:asthma group mice appear the emergence of increase of nasal secretions, scratching the nose, shortness of breath and hair lost its luster, hair erection or other symptoms. Budesonide group was obviously relieved.24 hours after P. aeruginosa infection, asthma and infection group appeared to move slowly, eyes closed, rolled a ball, increase of nasal secretions, ear temperature cold,budesonide and infection group had not the above performance, but also obvious chills, get together and squeeze as a ball, appetite decreased. significantly.2. Pulmonary changes in airway inflammation:Asthma group was characterized by reduced bronchial and alveolar spaces, widened alveolar septum, extensive infiltration of eosinophils mostly and other inflammatory cells around bronchioles, alveolus and blood vessels,effusion was increased, epithelium mucosae of bronchiole and bronchus were partly necrosis or amotic, and goblet cell was proliferated. Inhaled budesonide group was significantly lighter than airway inflammation in asthma group, the drug treatment significantly reduced the airway inflammation.24 hours after P. aeruginosa infection, in asthma and infection group, the pathological sections of lung were reduced the alveolar space completely, widened alveolar septum, bronchial wall and lung mesenchyme can be seen a large number of infiltration of inflammatory cells,bronchi, bronchioles and alveolar spaces were extensive exudate. Budesonide and infection group was established by the absolute diminution of bronchial and alveolar spaces, and some of them were completely disappeared, bronchi, bronchioles and alveolar spaces were all of exudate, bronchus were partly necrosis or amotic. According inflammatory score, asthma group was significantly higer compared with the control group(cp <0.01), budesonide group was lower compared with the asthma (cp<0.01), budesonide and infection group have a significantly extensive infiltration of inflammatory,bp<0.001 compared to the OVA/P.a. group.3. Lung bacterial quantification:after infection with P. aeruginosa, budesonide treated animals have significantly more viable bacteria compared with the ova-sensitized animals(B2). Bars indicate a significant difference of p<0.05.4.Detection of CRAMP expression in lung:the CRAMP expression in BUD/P.a. group by immunohistochemical was significantly lower than OVA/P.a.,the protein expression of CRAMP by western blotting was analysed by Quantity One softwall, after postbacterial inoculation, the CRAMP expression in budesonide treated group was significantly attenuated as compared with OVA-sensitized group(p<0.05).5. Detection of IL-4 and IFN-γlevels in blood serum:the level of IL-4 in asthmatic mice was more higher than control mice(P<0.01), the level of IFN-γwere significantly lower (P<0.01). The level of IL-4 in budesonide group showed significantly decreased as compared the asthma group (P<0.01), but The level of IFN-γbetween the two groups was not significant difference (P>0.05).After infection with P. aeruginosa, OVA-sensitized and budesonide treated animals showed significantly decreased IFN-γand increased IL-4 in blood serum,the bars indicates a significant difference of P<0.01 compared with control group. Conclusions:1. The level of IL-4 in asthmatic mice was more higher than control mice, the level of IFN-γwere significantly lower. It is confirmed that Th1/Th2 imbalance play an important role in the pathogenesis of asthma. 2.Inhaled budesonide can reduce airway inflammation in asthmatic mice,but fails to improve significantly Th1/Th2 imbalance.3. Inhaled budesonide aggravates allergen-induce and bacteria exposed airway inflammation, fails to the clearance of a pulmonary infection,and reduces the produce of CRAMP in the antibacterial immune response of asthma. Inhaled budesonide suppresses pulmonary antibacterial host defense... |
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