[Expression of RAGE in asthmatic rats and the intervention of Roxithromycin]

Objective: To observe the expression of the Receptor of Advanced glycation end products (RAGE) in asthmatic rats, and explore the intervention of Roxithromycin. Methods: A total of 18 Specific Pathogen Free-class Brown Norway male rats were randomly divided into control group, asthma model group and Roxithromycin group, with 6 rats in each group. The asthmatic model was sensitized by intraperitoneal injection of Ovalbumin (OVA)+Al(OH)(3), and challenged with OVA. Rats in Roxithromycin group were given Roxithromycin 30 mg/kg 30 minutes before each challenge. Rats in control group and asthma model group were treated with equal volume of saline. The concentrations of RAGE and interleukin (IL)-4 in serum and bronchoalveolar lavage fluid (BALF) were measured by enzyme-linked immunosorbent (ELISA); the pathological changes of lung tissues were observed by HE-staining; the thickness of airway wall and airway smooth muscle were measured by Image-Pro Plus; the relative expression of RAGE in lung tissues were detected by Western blot. Results: In asthma model group, the concentrations of RAGE and IL-4 in the serum and BALF were obviously higher than those in control group [(494±32) vs (327±45) ng/L; (32.4±5.8) vs (13.1±2.9) ng/L; (553±38) vs (399±56) ng/L; (37.8±3.4) vs (19.4±2.5) ng/L] (all P<0.01); in Roxithromycin group, the concentrations of RAGE and IL-4 in the serum and BALF were obviously lower than those in asthma model group [(438±18) vs (494±32) ng/L; (22.8±6.0) vs (32.4±5.8) ng/L; (444±42) vs (553±38) ng/L; (25.6±4.5) vs (37.8±3.4) ng/L] (all P<0.05). In asthma model group, the bronchial wall was thickened, the lumen was narrow, the mucosal wrinkles were significantly increased, edema appeared under the mucosa, and a large number of inflammatory cells infiltrated and aggregated in the bronchi, perivascular and alveolar spaces; the thickness of airway wall and airway smooth muscle were significantly increased than those in control group (P<0.01); in Roxithromycin group, airway inflammation and remodeling were alleviated compared with those in asthma model group (P<0.05). In asthma model group, the expression of RAGE in lung tissues were significantly increased than those in control group (P<0.01); in Roxithromycin group, the expression of RAGE were significantly decreased than those in asthma model group (P<0.01). There were positive correlations between the expression of RAGE and IL-4 in BALF and serum (r=0.782, 0.804, all P<0.01); there were positive correlations between RAGE and total white cell counts, eosinophil counts, smooth muscle thickness (r=0.897, 0.927, 0.860, all P<0.01). Conclusions: The increasing of RAGE in asthmatic rats are positively correlated with airway inflammation and airway remodeling. Roxithromycin may inhibit the development of asthma by reducing the expression of RAGE.