| Objective: To observe the pathological features of the smooth muscle and collagen deposition in airway wall of the rats model of asthma and evaluate an application of carbazotic acid-Sirius Red staining in the study on collagen deposition; to explore the effect of TGF-B1 on airway wall remodeling; to study the effects of corticosteroid on the TGF-B1 expression and the relationship between TGF-B1 expression and the airway wall remodeling of ashma rat models.Method: In this experiment, the rat model with asthma was established by sensitizing with ip injection of ovalbumin together with A1(OH)3 and Bordetella Pertussis bacilli, then challenging by repeatedly exposing to aerosolized ovalbumin. The rats were randomly divided into the control, asthmatic and steroids group. In each group, the rats were obseved at two time points of one week and two week's respectively. The following parameters were measured by image analysis system: the perimeter of bronchial basement membrane.total bronchial wall area(Wat).inner wall area (Wai) and the area of smooth muscle (Warn). Collagen stained by carbazotic acid-Sirius Red was observed under polarimicroscope, and the thickness of collagen in bronchi were measured by means of image analyzer(Image-pro plus). Immunohistochemistry was employedto observe the expression and localization of TGF-B1 in bronchi and lung tissues, and the light density of TGF-B1 expression was measured by means of image analyzer(Image-pro plus).Results (1) After repeated allergen exposure for one week, airway remodeling in rats were observed characterized by thickening of the airway wall,hyperplasia of smooth muscle and increased of collagen deposition. In the two weeks group, airway remodeling was more noticeble. The expression of TGF-B1 in the epithelial cells of bronchi was significantly higher in the two week group than that of the one week group. (2)Compared with the asthmatic group, there was mild inflammation in steroids group;Wat/Pbm, Wai/Pbm and Wam/Pbm were lower and collagen deposition was scattered significantly. There were no staistically significant differences between the steroids group and the control.(3)A weak but staistically significant correlation was found among Wat/Pbm, Wai/Pbm ,Wam/Pbm and collagen deposition and the expression of TGF-B1 in asthmatic subjects.Conclusions: 1. Repeated exposure of allergen could induced airway inflammation and remodeling. 2. TGF-B1 may play an important role in the airway wall remodeling. 3. Steroids can down regulate the expression of TGF-B1, and may inhibited inflammation and airway remodeling.
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