致敏大鼠气道细胞DNA合成增加与气道重塑关系的实验研究

DNA synthesis of airway cells and airway remodelling in sensitized rats

目的 观察重复过敏原吸入刺激致敏的大鼠气道细胞DNA合成和气道壁结构的改变 ,并探讨气道重塑反应发生的机制。方法 应用SD大鼠建立哮喘模型 ,采用胶原染色、粘液染色和双标免疫组化染色等技术对气道细胞的DNA合成和气道重塑进行研究。结果 (1)模型组和正常组相比 ,气道上皮下胶原组织大量沉积 ,上皮表面粘液层增厚 ,杯状细胞增生 ,并有大量炎性细胞浸润 ;(2 )模型组气道平滑肌细胞DNA合成表达Brdu阳性核计数为 10 3± 2 1,明显高于正常对照组 (7 2±2 1) ,(t=3 6 6 ,P <0 0 1) ;模型组气道上皮细胞的DNA合成表达Brdu阳性核计数为 2 1± 7,亦明显高于正常对照组 (16± 4 ) (t=2 35 ,P <0 0 5 )。结论 (1)重复过敏原刺激可使气道细胞DNA合成增加 ,上皮下胶原沉积和粘液分泌增加。 (2 )

Objective To demonstrate the process of airway remodeling and hyperplasia or hypertrophy of airway cells in vivo, we developed the asthmatic rat models for investigating the relationship between the increase of DNA synthesis of airway cells and airway remodeling. Lung pathology and cell recruitment were investigated for evidence of airway remodelling. Methods Twenty four healthy male SD rats weighing 120-150 g were randomly divided into two groups: normal group and asthmatic model group. The model group was sensitized and challenged with ovalbumin, and the normal group rats were challenged with saline instead. All animals were injected intraperitoneally with the DNA S phase marker bromodeoxyuridine (Brdu) at a dose of 50 mg/kg following each challenge and received a second dose 4-6 h later. General histological characteristics were observed using hematoxylin and eosin stained sections. Collagen and mucus were stained to observe the changes of the airway wall. Double staining immunohistochemical technique was used to determine DNA synthesis of the airway wall. Brdu incorporation into ASM and epithelium was quantified employing computer asisted image analysis. Results (1) There were more inflammatory cells infiltrating the airway in asthmatic model group than those in the normal group. (2) The model group demonstrated obviously an increase of collagen deposition in the subepithelium and marked increase in mucus staining in the airway compared with normal group. (3) The Brdu index in ASM and epithelium of the model group were higher than those of normal group (10.3±2.1 vs 7.2±2.1, t =3.66, P <0.01; 21±7 vs 16±4, t =2.35, P <0.05, respectively). Conclusions (1) DNA synthesis in ASM and epithelial cells increased in sensitized SD rats following repeated allergen challenges, suggesting an increased cell proliferative response to allergen. (2) Pathological changes were also detected including increased subepithelial collagen deposition and elevated levels of mucus in the airway. (3) The mechanism of the airway remodelling may be involved with the changes of the micro environment caused by allergy inflammation.