呼吸道合胞病毒感染小鼠Th17细胞亚群的变化

目的观察辅助性T淋巴细胞17（Th17）在呼吸道合胞病毒（RSV）感染小鼠肺部炎症中的变化,探讨其在RSV感染后宿主免疫机制中的作用。方法 30只3～5周龄雌性BALB/c小鼠随机分为实验组（18只）和对照组（12只）。实验组每只小鼠鼻腔滴入0.1 mL滴度为107.5TCID 50/mL的病毒液,对照组鼻腔滴入0.1 mL的2.5%灭活鸡血清的DMEM维持液。在处理后的第1、4、8 d分别处死小鼠,并留取肺脏和肺门淋巴结。用HE染色观察RSV感染后肺组织病理变化;实时定量聚合酶链反应（RT-PCR）检测肺组织中RSV-F、IL-17A、IL-17F和IL-23p19 mRNA表达水平;流式细胞术检测小鼠肺门淋巴结中Th17细胞水平。结果在RSV感染后第4 d小鼠肺组织出现典型间质性肺炎表现,第8 d炎性细胞明显减少;肺组织中RSV病毒的相对表达量在第4 d为9.208±0.548,较第1 d显著增多（P〈0.01）,到第8 d则较第4 d显著减少（P〈0.01）;肺组织中IL-23p19和IL-17A等细胞因子的表达在RSV感染后也呈现增高的趋势,并在第4 d达到高峰,但IL-17F mRNA表达在RSV感染后不同时间点与对照组比较无显著变化（P〉0.05）;RSV感染后第4 d和第8 d小鼠肺门淋巴结Th17亚群比例分别为（0.370±0.043）%和（0.853±0.048）%,均明显高于相应的对照组（P〈0.05）,而且第8 d的Th17比例也显著高于第4 d（P〈0.01）。结论在RSV感染小鼠导致的肺部炎症反应过程中,出现肺组织中IL-17A的表达增加和肺门淋巴结Th17细胞水平增高,说明Th17细胞可能参与宿主的抗病毒免疫过程。

Changes of Th17 Cells in Mice with Respiratory Syncytial Virus Infection

Objective To observe the immune responses of T helper cells 17 （Thl7） to respiratory syncytial virus （RSV） infection induced lung inflammation in mice, and explore its roles on the host immune responses to RSV. Methods Female BALB/c mice aged 3 to 5 weeks were randomly divided into a RSV group （n = 18） and a control group （n = 12）. The mice were intranasally administrated by a 1075 50% tissue culture infective dose （TCID50） of RSV in 0. 1 mL of culture medium. Sterile medium （0. 1 mL/ mouse） was used as control. After infected on 1 ~t ,4,h, 8,h day, the mice were sacrificed, and specimens from the lungs and lymph nodes were collected. The lung sections were stained by hematoxylin-eosin to observe the changes of lung inflammation after RSV infection. IL-17A, IL-17F and IL-23p19 mRNA expressions in the lung tissue were determined by real-time PCR. The frequencies of Thl7 subsets in hilar lymph node were analyzed by flow cytometry. Results On 4th day after RSV infection, a typical lung interstitial inflammation was observed. However,this inflammation was alleviated on 8th day after RSV infection. The viral load in the lung tissue on 4th day after RSV infection were 9. 208 ± 0. 548, which was the highest among all RSV subgroups （P〈0. 001）. IL-23p19 and IL-17A cytokine expressions in the lung tissue were significantly increased on 4th day and 8th day after RSV infection compared with control groups （P 〈 0. O1 ）, and the peak was on 4~h day. However,IL-17F mRNA expression in the lung tissue on different day after RSV infection had no significant difference compared with the control group （P 〉 0.05 ）. Ttle frequencies of Thl7 subsets in hilar lymph node on 4th day and 8th day after RSV infection were （0. 37 ± 0. 043 ） % and （0. 853 ± 0. 048 ） % respectively,which were higher than those in control groups （P 〈0.05 ）. The frequencies of Thl7 on 8th day after RSV infection were significantly higher than that on 4th day after RSV infection （ P 〈 0. 01 ）. Conclusions The expression of IL-17A in the lung tissue is increased and the level of Th17 cells in hilar lymph nodes is also elevated in the lung infected by RSV, which indicates that Thl7 cells might be involved in host antiviral immune.