人脐带间充质干细胞移植对支气管哮喘小鼠气道炎症的作用及其机制

Effects of human mesenchymal stem cells on airway inflammation in allergic asthma mice and the underlying mechanism

目的 探讨人脐带间充质干细胞（hUC-MSCs）移植对支气管哮喘（简称哮喘）小鼠气道炎症的作用及其机制.方法 将24只BALB/c小鼠按随机数字表法均分为四组：正常对照组、哮喘模型组[用卵白蛋白（OVA）制备过敏性哮喘动物模型]、hUC-MSCs治疗组（在哮喘模型动物气管内注射hUC-MSCs 50μl）和hUC-MSCs对照组（在正常对照动物气管内注射hUC-MSCs 50μl）.hUC-MSCs从健康胎儿脐带组织分离培养,经表征检测后,细胞移植到哮喘小鼠气管中,分别对各组小鼠气道的组织病理学变化、支气管肺泡灌洗液（BALF）中白细胞、肥大细胞计数、白细胞介素（IL）-6、转化生长因子β（TGF-β）和IL-17＋ CD4＋T细胞（Th17细胞）表达水平进行评价.结果 哮喘模型组动物小支气管/气道变小、气道、血管旁有大量炎症细胞浸润,部分气道管腔有黏液堵塞;BALF中白细胞总数计数和肥大细胞计数显著升高（P＜0.05）.哮喘模型组肺组织中Th17细胞比例显著高于对照组（2.90％比0.76％,P＜0.05）.正常对照组及hUC-MSCs对照组无气道炎症表现.hUC-MSCs治疗组BALF中白细胞总数、肥大细胞及Th17细胞比例显著低于哮喘模型组（例如Th17细胞：0.24％比2.90％,均P＜0.05）;肺组织中的IL-6 mRNA和TGF-β mRNA相对表达量均显著低于哮喘模型组（0.23比2.30和0.56比6.60,P＜0.01）.此外,hUC-MSCs治疗组的肺组织炎性细胞浸润显著轻于哮喘模型组.结论 hUC-MSCs移植可有效地改善OVA诱导的哮喘小鼠的气道炎症反应;其机制可能是通过抑制Th17细胞以及下调炎症因子的分泌.

Objectives To investigate the effects of human umbilical cord mesenchymal stem cells （hUC-MSCs） on airway inflammation in an ovalbumin （OVA） induced asthma mouse model and the underlying mechanism.Methods Twenty-four BALB/c mice were randomly divided into four equal groups：normal control group,OVA-induced asthmatic model group,hUC-MSCs treated group （50 μl of hUC-MSCs was transplanted into the trachea of asthmatic mice） and hUC-MSCs control group （50 μl of hUC-MSCs was transplanted into the trachea of control mice）.Human umbilical cord mesenchymal stem cells from umbilical cord of healthy new born babies were used as the source of hUC-MSCs for this study.The asthmatic conditions of the airways and the lungs were assessed by examining：（1） histopathological changes of the airways and the lungs;（2） expression of cytokines IL-6 and TGF-β mRNA by real-time PCR;（3） total leukocytes and mast cell count in bronchoalveolar lavage fluid （BALF） and number of IL-17-expressing CD4 ＋ cells （Th17 cells） in the lung tissue using flow cytometry.Results Typical histopathological changes of asthma were confirmed in the asthmatic model group.These changes included intensive inflammatory cell infiltration around the airways and patchy airway occlusion by hyperviscous mucus.The number of total leukocytes and mast cells in BALF were significantly increased in the asthmatic mice when compared with the control group （P 〈 0.05）.Mice in the asthmatic model group had significantly higher percentage of Th17 cells in lung tissues when compared with the control group （2.90% vs 0.76%,P 〈 0.05）.In contrast,in the asthmatic mice treated with hUC-MSCs,the inflammatory cell infiltration was significantly reduced compared with asthmatic mice,as observed by significantly lower leukocytes and mast cells in BALF （P 〈 0.05） and significant reduction in the percentage of Th17 cells in the lung of OVA-challenged mice following hUC-MSCs treatment （percentage of Th17 cells：0.24% vs 2.90%,P 〈 0.05）.The expression of mRNA for IL-6 and TGF-β was significantly suppressed in the hUC-MSCs treatment group （0.23 vs 2.30 and 0.56 vs 6.60,both P 〈0.01）.No asthmatic pathological changes in both normal and hUC-MSCs control groups were observed.Conclusions hUC-MSCs significantly inhibit the airway inflammation in OVA-induced asthmatic mice.This inhibition is associated with the suppression of Th17 cells and the down-regulation of inflammatory factors such as IL-6 and TGF-β in the lungs.