慢性支气管炎大鼠肿瘤坏死因子-α、巨噬细胞炎症蛋白-2及髓过氧化物酶的研究

A study on tumor necrosis factor-α, macrophage inflammatory protein-2 and myeloperoxidase in blood, broncho alveolar fluid and lung tissues of rat chronic bronchitis model

目的 探索慢性支气管炎气道炎症的特点。方法 雄性SD大鼠气管内注入浓度为 1g/L的脂多糖 2 0 0 μl制成大鼠慢性支气管炎模型 ,随机分为健康对照组、模型组、生理盐水组及氟美松组 ,每组 7只。应用ELISA法测定血浆、支气管肺泡灌洗液 (BALF)及肺组织中肿瘤坏死因子 (TNF)α、巨噬细胞炎症蛋白 2 (MIP 2 )含量 ,生化法检测血和肺组织中髓过氧化物酶 (MPO)水平 ,并进行BALF中细胞计数和分类。结果 模型组、生理盐水组及氟美松组BALF和肺组织中TNFα和MIP 2的含量显著高于健康对照组 (P <0 .0 5 ) ;肺组织中MPO的含量 ,模型组 [( 15 .0 0 2 +1.85 7)U/g]和生理盐水组 [( 11 888+0 92 6)U/g]显著高于健康对照组 [( 7 812 +1 0 4 3 )U/g](P <0 .0 5 ) ,而氟美松组[( 6 14 1+0 3 64 )U/g]则显著低于模型组 (P <0 .0 5 ) ;模型组肺组织中MPO与TNFα和MIP 2含量之间呈正相关 (r=0 788,r=0 963 ;P <0 .0 5 ,P <0 .0 0 1)。结论 气道内中性粒细胞聚集是慢性支气管炎的重要特点 ,TNFα和MIP 2参与了中性粒细胞的激活和趋化过程 ,中性粒细胞产生大量的MPO可造成气道损伤。

Objective To study the nature and mechanisms of airway inflammation in chronic bronchitis and observe the effects of inhaled glucocorticoids on inflammatory indices. Methods Rat chronic bronchitis model was established by intratracheal instillation of small dose of lipopolysaccharide (LPS, 1 g/L). Experiments were performed in 28 male Sprague Dawley rats, which comprised four groups in random, i.e. chronic bronchitis model group, normal saline treated group, dexamethasone treated group and healthy control group. The levels of myeloperoxidase (MPO) of blood and lung tissues, and tumor necrosis factor(TNF)α and macrophage inflammatory protein 2 (MIP 2) of plasma, broncho alveolar fluid(BALF) and lung tissues were determined by biochemical and ELISA methods. Total and differential white blood cell counts of BALFwere carried out. Results (1) The levels of TNFα and MIP 2 in BALF and lung tissues, and MPO in lung tissues of chronic bronchitis model group were significantly increased than those of control group ( P <0.05). (2)More significant increase in total white blood cell count and neutrophils in BALF was found in rat chronic bronchitis group than in control group ( P <0.001). (3) Significant positive correlations were observed between the level of MPO and MIP 2 of lung tissues, the level of MPO and TNFα of lung tissue and the total cell counts and the level of MIP 2 of BALF and lung tissue. (4) More significant decrease in total cell counts and neutrophils of BALF and levels of MPO in lung tissue was found in dexamethasone treated group as compared to those of chronic bronchitis group. Conclusion Recruitment and activation of neutrophils seem to be the characteristics of chronic bronchitis. TNFα and MIP 2 may be involved in the process of chemotaxis and activation in airway inflammation in chronic bronchitis. Inhaled steroids might have some effects on chronic bronchitis by limiting the airway inflammation.