The role of urotensin II in airway remodeling of asthma

Objective To observe the change of urotensin Ⅱ (U-Ⅱ) expression in airways of rat asthmatic models, and of patients with asthma, and therefore to investigate the role of U-Ⅱ in the pathogenesis of asthma and airway remodeling. Methods Twenty Wistar rats were divided into a control group (10 rats) and an asthmatic group (10 rats). The animal model of asthma was established by ovalbumin intraperitoneal injection and aerosolization. The internal perimeter of bronchi (Pi), bronchial wall area (WA) and the area of bronchial smooth muscle (WAm) were measured by a computerized image analyzer, and the WA/Pi and WAm/Pi were calculated to express airway remodeling. Autopsy lung tissues from 5 patients with asthma and 5 normal human controls died of car accident were collected, stained with hematoxylin and eosin stain, and the streptavidin peroxidase method. The expression level of U-Ⅱ and the percentage of positive U-Ⅱ cell in the airways of rats and patients with asthma were measured. Results Rats exposed to ovalbumin developed asthma and airway remodeling: the WA/Pi and WAm/Pi [(24.1±2.4) μm2/μm, (5.3±1.9) μm2/μm] were increased, as compared with the normal group [(16.5±1.7) μm2/μm, (3.8±1.2) μm2/μm], the difference being significant (t=3.892, 3.785, all P0.01). The expression level of U-Ⅱ in asthmatic rats was 2.46±0.15, while in the control group was 1.26±0.11, the difference being significant (t=6.236, P0.01). There was a positive correlation between the level of U-Ⅱ and WAm/Pi (r=0.712,P0.01). The percentage of positive U-Ⅱ cells in the asthmatic rats was (82±8)%, while in the control rats was (22±8)%, the difference being significant (t=19.102, P0.01). The expression level of U-Ⅱ in patients with asthma was 2.61±0.19, while in the control group was 1.36±0.12, the difference being significant (t=7.374, P0.01). The percentage of positive U-Ⅱ cells in patients with asthma was (75±9)%, while in the controls was (27±7)%, the difference being significant (t=16.236, P0.01). Conclusion The expression of U-Ⅱ is increased in airways of rat asthmatic models and of patients with asthma. It may play an important role in the pathogenesis of asthma and airway remodeling.