Expression of angiopoietin-1 and its tyrosine kinase receptor Tie-2 in the airway of asthmatic rats

Abstract:

ObjectiveTo study the effect of dexamethasone on airway morphology and on the expression of angiopoietin1 (Ang1) and its tyrosine kinase receptor Tie2 in the airway of asthmatic rats.MethodsFortyfive SpragueDawley rats were randomly divided into control, asthmatic, and dexamethasonetreated asthmatic groups. Asthma was induced by repeated sensitization and challenge with ovalbumin in the latter two groups. The dexamethasone intervention group received an intraperitonea injection of dexamethasone (2 mg/kg) before asthma challenge. Immunohistochemistry was used to measure the expression of Ang1 and Tie2 in the airway. Airway thickness was estimated by a computerized digital image analyzer. ResultsAirway thickness in the asthmatic group (33.9333±8.3791 μm2/μm) increased significantly compared with that in the control group (21.1333±2.7740 μm2/μm) (P<0.01). The dexamethasone intervention group also showed increased thickness of the airway (27.4000 ± 4.6105 μm2/μm) compared with the control group (P<0.01), but the airway thickness in the dexamethasone intervention group was significantly reduced compared with that in the untreated asthmatic group (P<0.01). The expression of Ang1 (103.9487±8.2914 vs 76.0320±3.7728; P<0.01) and Tie2 (99.2307±8.1913 vs 75.3153±3.7321; P<0.01) in the airway increased significantly in the asthmatic group compared to controls. The expression of Ang1 and Tie2 in the airway of the dexamethasone intervention group (90.6180±5.2339 and 86.6633±3.7321, respectively) was statistically higher than that in the control group (P<0.01) but statistically lower than that in the untreated asthmatic group (P<0.01). Ang1 and Tie2 expression in the airway was positively correlated with the thickness of airway (rAng1=0.719，rTie2=0.746，P<0.01). There was also a positive correlation between Ang1 and Tie2 expression (r=0.742，P<0.01). ConclusionsThe expression of Ang1 and Tie2 in the airway increased in asthmatic rats and was positively correlated with the thickness of the airway. Ang1 and Tie2 may participate in the process of airway remodeling in asthma. Dexamethasone can decrease the expression of Ang1 and Tie2 in the airway and relieve the changes of airway morphology.