骨髓间充质干细胞对哮喘小鼠CD4^＋CD25^＋调节性T细胞及气道炎症的影响

Effects of bone marrow mesenchymal stem cells on CD4^+CD25^+ regulatory T cells and airway inflammation in asthmatic mice

背景:CD4+CD25+调节性T细胞功能降低、数量下降已被公认为是哮喘患者免疫失调的重要表现。间充质干细胞具有免疫调节功能,可上调CD4+CD25+调节性T细胞,抑制淋巴细胞增殖,并已在许多免疫性疾病方面成功应用。目的:观察骨髓间充质干细胞移植对哮喘小鼠外周血CD4+CD25+调节性T细胞及气道炎症的影响。设计、时间及地点:随机对照动物实验,于2006-09/2008-05在中山大学附属第二医院中心实验室完成。材料:SPF级BALB/c小鼠34只,其中3～4周龄雄鼠4只,用于制备骨髓间充质干细胞;6周龄雌鼠30只,随机分为正常对照组、模型对照组、细胞移植组,10只/组。方法:模型对照组、细胞移植组以500mg/L卵白蛋白溶液0.2mL腹腔注射致敏,以50g/L卵白蛋白溶液雾化吸入激发建立小鼠哮喘模型。正常对照组以生理盐水代替卵白蛋白溶液,细胞移植组在诱导哮喘的第10天经尾静脉注入体外分离培养的小鼠骨髓间充质干细胞。主要观察指标:流式细胞仪检测小鼠外周血CD4+CD25+调节性T细胞占淋巴细胞的比例,并检测小鼠支气管肺泡灌洗液中的炎症细胞总数,计数嗜酸性粒细胞、淋巴细胞、中性粒细胞,结合病理切片分析气道炎症情况。结果:与正常对照组比较,模型对照组外周血CD4+CD25+调节性T细胞占淋巴细胞的比例明显降低(t=7.742,P<0.05);与模型对照组比较,细胞移植组该比例明显升高(t=7.455,P<0.05)。3组小鼠支气管肺泡灌洗液炎症细胞总数、嗜酸性粒细胞、淋巴细胞、中性粒细胞计数比较差异显著(P均<0.05);两两比较,模型对照组支气管肺泡灌洗液炎症细胞总数高于正常对照组(P<0.05),细胞移植组支气管肺泡灌洗液炎症细胞总数低于模型对照组(P<0.05)。正常对照组小鼠气道无明显炎症改变;模型对照组小鼠支气管、血管粘膜下和周围肺组织有明显炎症细胞浸润、气道上皮增生、气道黏液增多、气道上皮部分断裂脱落;细胞移植组小鼠气道炎症明显减轻。结论:静脉输注骨髓间充质干细胞能上调哮喘小鼠外周血CD4+CD25+调节性T细胞比例,同时可一定程度上抑制哮喘小鼠气道炎症。

BACKGROUND： Decreased function and reduced number of CD4^＋CD25^＋ regulatory T cells have been considered the major manifestation of immunity dysfunction in asthma patients. Mesenchymal stem cells （MSCs） have effects of immunoregulation, which can up-regulate CD4^＋CD25^＋ regulatory T cells, inhibit proliferation of lymphocytes, and have been widely used in many immune diseases. OBJECTIVE： To study the effect of bone marrow mesenchymal stem cell （BMSC） transplantation on the CD4^＋CD25^＋ regulatory T cells of peripheral blood and the airway inflammation in asthmatic mice. DESIGN, TIME AND SETTING： The randomized controlled animal experiment was performed at the Central Laboratory, Second Affiliated Hospital, Sun Yat-sen University from September 2006 to May 2008. MATERIALS： Thirty-four SPF BALB/c mice were selected for this study. Of them, 4 male mice aged 3 4 weeks were used for preparing BMSCs. Thirty female mice aged six weeks were equally and randomly divided into normal control, model control and cell transplantation groups. METHODS： Mice in the model control and cell transplantation groups were sensitized with 0.2 mL 500 mg/L ovalbumin （OVA） by a combination of intraperitoneal injection and repeated 50 g/L OVA solution challenges to establish the mouse asthma model. In the normal control group, normal saline of the equal volume was given instead of OVA. Mice in the cell transplantation group were intravenously administered MSCs at 10 days after sensitization. MAIN OUTCOME MEASURES： The number of CD4＋CD25＊ regulatory T cells in peripheral blood was detected by flow cytometry. The total cell number of bronchoalveolar lavage fluid, the number of eosinophils, lymphocytes and neutrophils were counted to analyze the degree of inflammation of the airway together with pathological section. RESULTS： Compared to the normal control group, the number of CD4^＋CD25^＋ regulatory T cells in peripheral blood was significantly decreased in the model control group （t=7.742, P 〈 0.05）. Compared to the model control group, the number of CD4^＋CD25^＋ regulatory T cells in peripheral blood was significantly increased in the cell transplantation group （t=7.455, P 〈 0.05）. There were significantly differences in the total cell number of bronchoalveolar lavage fluid, the number of eosinophils, lymphocytes and neutrophils （P 〈 0.05）. The total cell number of bronchoalveolar lavage fluid was higher in the model control group compared with the normal control group （P 〈 0.05）. The total cell number of bronchoalveolar lavage fluid was lower in the cell transplantation group compared to the model control group （P 〈 0.05）. There was no obvious infiltration of inflammatory cells in the airways in the normal control group. However, there were a great number of inflammatory cells, epithelial proliferation, partial breakage and defluvium of the airway epithelium in the bronchus, below the vessel mucous membrane and around lung tissues in the model control group. Airway inflammation was significantly relieved in the cell transplantation group. CONCLUSION： MSCs via intravenous infusion can up-regulate CD4^＋CD25^＋ regulatory T cells of peripheral blood in asthmatic mice and relieve the inflammation of the lung in asthmatic mice.