Effect of roxithromycin and dexamethasone upon myofibroblast in rats asthma airway remodeling

Objective To explore the effect of myofibroblast (MF) on bronchial asthma(asthma)airway remodeling. To observe the effect of roxithromycin on asthma airway remodeling,and to compare its effect with dexamethasone. Methods In the experiment,40 Sprague-Dawley(SD) rats were randomly divided into the asthma group(group A), the sodium chloride control group (group C), the dexamethasone group (group D) and the roxithromycin group(group R). There were ten rats in each group. The rats were sensitized with ovalbumin and AI(OH)3 before repeatedly exposed to aerosolized ovaibumin. The α-smooth muscle actin (α-SMA) expressions of MF of bronchial subepithelium in lung tissue were assessed by immunohistochemistry. By image analysis technique, their integral optical density(IOD) was quantitatively analyzed. The histopathology and structural change of pulmonary tissues were observed by light microscope.The following important parameters of intrapulmonary bronchus were measured by image analysis technique,too: the total brochial wall thickness,inner airway wall thickness and the smooth muscle thickness. Results The results of immunohistochemistry and image analysis:the total brochial wall thickness,inner airway wall thickness and the smooth muscle thickness in group A were thicker than those in group C(P <0.01). The inner airway wall thickness and the smooth muscle thickness in group D and group R were thinner than those in group A(P <0.01). But there were no significant difference in the total brochial wall thickness, inner airway wall thickness and the smooth muscle thickness between group D and group R. Compared with group C,the IOD value by quantitative analysis shows that expression of MF's α-SMA in bronchial suhepithelium in group A significantly increased(P<0.01). The expression in group D and group R significantly decreased compared with group A (P < 0. 05). But there was no significant difference in their expression between group D and group R. The results of correlation: there were positive correlations between inner airway wall thickness and expression of MF's α-SMA in bronchial subepithelium(presented by IOD)(r =0. 913, P <0.01, n = 40), also positive correlations between the smooth muscle thickness and expression of MF's α-SMA in bronchial subepithelium(presented by IOD)(r = 0. 626, P < 0. 01, n = 40). Conclusions MF plays an important role in the course of airway remodeling. Both roxithromycin and dexamethasone may inhibit proliferation and expression of MF. So they may be effective drugs to inhibit asthma airway remodeling. Key words: Asthma; Airway remodeling; Myofibroblast; Roxithromyein; Glucocorticoids