共刺激分子OX40/OX40L在小鼠过敏性哮喘发病机制中的作用

Effects of costimulatory pathway OX40/OX40L on the pathogenesis of allergic asthma in mice

目的探讨共刺激分子OX40/OX40L在小鼠过敏性哮喘发病机制中的作用。方法制作BALB/c小鼠哮喘模型,治疗组在致敏阶段给予抗-OX40L单克隆抗体,并设两个对照组:哮喘模型组和IgG抗体组。检测各组支气管肺泡灌洗液中白细胞总数并进行分类记数;ELISA法检测支气管肺泡灌洗液中白细胞介素-4与γ型干扰素水平;光镜观察肺组织形态学改变和OX40的表达情况。结果治疗组支气管肺泡灌洗液中白细胞总数为(26.6±4.6)×106/m l,嗜酸性粒细胞百分数(15.1±2.6)%,淋巴细胞百分数(7.0±0.9)%,均低于两对照组;IL-4水平为(672±58)pg/m l,低于两对照组,而INF-γ水平为(0.86±0.09)pg/m l,高于两对照组,差异均有统计学意义;治疗组肺组织形态学明显改善,OX40的表达弱于两对照组;治疗组小鼠的哮喘症状和体征较两对照组明显改善。结论在哮喘小鼠的致敏阶段给予抗OX40L单克隆抗体,能有效控制Th1/Th2的失衡和肺组织的炎症反应,并能够明显减轻哮喘发作的症状和体征。

Objective Allergic asthma is thought to be mediated by CD4＋T lymphocytes producing the Th2-associated cytokines, which play a critical role in the development of the airway hyperresponsiveness and the eosinophilic inflammatory response. The costimulatory pathway CD28/B7 has been shown to play an important role in CD4＋ T cell activation in allergic asthma, This study was conducted to evaluate the role of another costimulatory pathway OX40/OX40 ligand （L） in the pathogenesis of allergic asthma in BALB/c mice. Methods An allergic asthma model in BALB/c mice was established. Thirty-six BALB/c mice were randomly divided into three groups with 12 in each. Mice in treatment group （group B） were treated with neutralizing anti-OX40L monoclonal antibody （mAb, 300μg per mouse ） during the sensitization period. Mice in two control groups, asthma model group （group A） and IgG antibody group （group C） were treated with normal saline （NS） and control IgG respectively instead of anti-OX40L mAb. Bronchoalveolar lavage fluid （BALF） was collected from the mice of each group for counting the total number of white blood cells （including neutrophil granulocyte, lymphocyte, monocyte and eesinophil granuloctye） and the proportions of these cells. The levels of IL-4 and INF-γ in BALF were measured by ELISA. Lungs were removed for morphological examination after HE and PAS staining, and expression of OX40 in lungs was evaluated by immunohistochemical method. Results （ 1 ） The count of total number of white blood cells in BALF （ × 10^6/ml） was lower in group B than that of group A and group C （26. 6 ±4. 6 vs. 36. 8 ±5. 2 and 34. 3 ± 6. 9, respectively）, the difference between the treatment group （group B） and two control groups （ groups A and C） was significant ; The proportions of eesinophils and lymphocytes in the BALF （ % ） were lower in group B than those in group A and group C （ eosinophils 15.1 ± 2. 6 vs. 20. 0 ± 4. 1 and 19.9±3.9, respectively; lymphocytes 7.0 ± 0.9 vs. 8.9 ± 1.6 and 8.6 ± 1.8, respectively）, the difference between the treatment group and two control groups was significant. （2） The IL-4 level in BALF （pg/ml） was lower in group B than that in group A and group C （672 ±58 vs. 809. 57 ± 106. 00 and 784 ± 58 , respectively）, but the INF-γ levels in BALF （pg/ml） were higher than those in group A and group C （0. 86 ±0. 09 vs. 0.69 ± 0. 15 and 0. 67± 0. 13 respectively）, and all the differences were statistically significant. （3） The expression of OX40 in the lungs of mice in group B were at a lower level than that of group A and group C, and the morphological changes of asthma were ameliorated in the mice of the treatment group. The signs of mice in treatment group were obviously ameliorated as compared to the two control groups. Conclusion Blocking the costimulatory pathway by administering the neutralizing anti-OX40L mAb during the sensitization period of allergic asthma model could balance the Thl/Th2 responses, inhibit lung inflammation and ameliorate the signs of mice model of asthma.