哮喘小鼠气道重塑过程中CD4+CD25+调节性T细胞和Th17细胞表达的动态变化

Dynamic changes in percentages of CD4+ CD25+ regulatory T cells and Th17 cells in process of airway remodeling in mouse model of asthma

摘要:

目的 探讨哮喘小鼠Th17 细胞和CD4⁺CD25⁺ 调节性T 细胞(Treg)在脾组织中表达水平的变化规律及与气道重塑的关系。方法 将SPF 级雌性 Balb/c 小鼠48 只随机分为对照组和哮喘组,利用腹腔注射卵清蛋白(OVA)和氢氧化铝混悬液致敏及雾化吸入OVA 激发制备哮喘气道重塑模型,对照组应用生理盐水替代。两组分别在雾化2 周、4 周及8 周后的24 h 内随机处死8 只小鼠,左肺组织病理切片观察肺气道重塑程度;流式细胞仪测定脾组织中Th17、CD4⁺CD25⁺Treg 细胞占CD4⁺T 细胞的百分比。结果 随着激发时间的延长,哮喘组支气管总管壁面积(Wat/Pbm)及支气管平滑肌面积(Wam/Pbm)逐渐增厚(P<0.01);脾组织细胞悬液中Th17 细胞水平逐渐升高,与气道重塑的程度呈正相关(P<0.01),而CD4⁺CD25⁺Treg 细胞水平逐渐降低,与气道重塑程度均呈负相关(P<0.01)。结论 哮喘小鼠气道重塑是动态变化的过程,激发的时间越长,气道重塑越严重,Th17 细胞表达越高,CD4⁺CD25⁺Treg 细胞表达越低,两者间免疫失衡可能是哮喘气道重塑发生的重要因素之一。

Abstract:

Objective To study the dynamic changes in Th17 cells and CD4⁺ CD25⁺ regulatory T cells (Treg) in the spleen and to analyze their relationship with airway remodeling.Methods A total of 48 female specific pathogenfree Balb/c mice were randomly divided into control and asthmatic groups. To establish the asthmatic airway remodeling model, the mice were sensitized to ovalbumin (OVA) through intraperitoneal injection of OVA and aluminum hydroxide suspension and challenged by inhalation of aerosol OVA. The matched control group was treated with normal saline instead. In 24 hours after 2-week, 4-week, and 8-week aerosol inhalation, 8 mice were randomly selected from each group and sacrificed. Then histopathological examination of the left lung was performed to measure the degree of airway remodeling. The percentages of Th17 and CD4⁺ CD25⁺ Treg cells in total CD4⁺ cells from the spleen were determined by flow cytometry.Results In the asthmatic group, the ratios of total bronchial wall area to bronchial basement membrane perimeter (WAt/Pbm) and bronchial smooth muscle area to bronchial basement membrane perimeter (WAm/Pbm) significantly increased as the challenge proceeds (P<0.01). The percentage of Th17 cells derived from the cell suspension of the spleen gradually increased and it was positively correlated with the degree of asthmatic airway remodeling (P<0.01). The percentage of CD4⁺ CD25⁺ Treg cells from the suspension gradually decreased and it was negatively correlated with the degree of asthmatic airway remodeling (P<0.01).Conclusions In mice with asthma, as the challenge proceeds, the airway remodeling becomes more severe, the percentage of Th17 cells increases, and the percentage of CD4⁺ CD25⁺ Treg cells decreases. The immunological imbalance is possibly one of the important factors inducing airway remodeling.