| Objective: To observe the expression of occludin and E-cadherin inairway epithelium of asthmatic mice and effects of budesonide on theirexpression,and to further investigate the influence of occludin and E-cadherinon the pathogenesis of asthma and the mechanism of glucocorticoid fortreatmenting asthma. Methods:24BALB/c female mice were randomlydivided into asthma group, budesonide treated group (BUD group) and controlgroup, and there were8mice in each group. The mice in the asthma groupwere sensitized by intraperitoneal injection of0.2mL ovalbumin (OVA),aluminum hydroxide and normal saline suspended solution (including20μgovalbumin and2mg aluminum hydroxide) on days0,7and14, and werechallenged by atomization of1%ovalbumin solution30minute on day2l,once a day, continuous14days, and were atomized an extra2mL normalsaline at1hour before challenge at every time. Mice in the BUD group weresensitized and challenged by the method described as the asthma group, andwere atomized an extra1mg budesonide at1hour before challenge at everytime. The mice in the control group were sensitized and challenged by normalsaline instead of ovalbumin in a same manner. Mice were sacrificed after thefinal ovalbumin or normal saline challenged and the samples were collected.The lung sections were stained with hematoxylin and eosin (HE) forobserving pathomorpho-logical changes. The ultrastructure of airwayepithelium were observed by electron microscope. Goblet cells in airwayepithelium and mucus secretion were identificated with periodic-acid-schiff(PAS) staining. Eosinophils in bronchoalveolar lavage fluid (BALF) werecounted. The expression of occludin and E-cadherin in airway epithelium wereobserved with immuno-histochemical method. The expression of occludinmRNA was evaluated by Real-time PCR. Results:(1) HE staining showedshedding of airway epithelial cells, inflammatory cells infiltration aroundairway mucosa, mucous gland hyperplasia, mucosa thickening, stricture withmucus plug of lumen in the asthma group. The pathomorphological changes inthe BUD group were alleviated compared with the asthma group, whereas thecontrol group exhibited no these features. Underwood’s standard of lunghistopathological scores in3groups were (4.1±0.675),(2.3±0.736) and(0.5±0.506), respectively, and the difference was statistically significant(P<0.05). The score of the BUD group was lower than that of the asthmagroup (P<0.05), but higher than the control group (P<0.05).(2)Electronmicroscope showed airway epithelial cells and cilium in the asthma groupwere obviously shedding, necrotic, discrete and short and microvillus werereduced. It also showed missing or discontinuous of intercellular junction,which led to enlarge cellular interspace. Basilar membrane was discontinuousand collagen fibers were increased. Budesonide intervention could alleviate the above changes, whereas the control group exhibited no these features.(3)Compared with the control group (0.250±0.463), PAS-positive goblet cellsin the asthma group (3.375±0.744) were enhanced and the difference wasstatistically significant (P<0.01). Compared with the asthma group, PASstaining cells were decreased in the BUD group (1.625±0.518) and thedifference was statistically significant (P<0.01).(4) Compared with the controlgroup (0.750±0.707), eosinophils in the asthma group (20.875±1.808) wereenhanced and the difference was statistically significant (P<0.01). Comparedwith the asthma group, eosinophils in the BUD group (10.625±1.302) weresignificantly decreased, but higher than the control group, the difference beingstatistically significant (P<0.01).(5)The occludin and E-cadherin in the controlgroup were observed a continuous positive expression mainly between or onthe surface of the airway epithelium and the discontinuous expression ofoccludin and E-cadherin in the BUD group were still more obvious than that inthe asthma group. The opticaldensity (OD) value of occludin in the asthmagroup (0.126±0.032) was lower than that in the control group (0.656±0.068)and the budesonide group (0.337±0.028), and the difference was statisticallysignificant (P<0.01). The OD value of occludin in the BUD group was stilllower than that in the control group, and the difference was statisticallysignificant (P<0.01). The OD value of E-cadherin in the asthma group(0.173±0.043) was lower than that in the control group (0.656±0.068)(P<0.01)and the BUD group (0.288±0.049)(P<0.01), but the BUD group was still lower than that in the control group, and the difference was statisticallysignificant (P<0.01).(6) The expression of occludin mRNA in three groupswere (7.200±4.959),(3.127±2.030) and (4.772±1.848), respect-ively, but therewas no statistically significant difference (F=1.960, P>0.05). Conclusions:(1)BALB/c mice model of asthma were successfully established.(2) Asthmaticmice were characterized by airway inflammation and damage of theconjunction between airway epithelial cells.(3) The expression of occludinand E-cadherin in airway epithelium of asthmatic mice were decreased, whichmight contribute to the development of asthmatic pathogenetic condition.(4)Budesonide could up-regulate the expression of occludin and E-cadherin inairway epithelium of asthmatic mice, which contributed to improve epithelialbarrier integrity and might provide a new mechanism of glucocorticoid fortreatmenting asthma. |
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