呼吸道合胞病毒对致敏小鼠气道炎症和CD8^+ T细胞功能的影响

Effects of respiratory syncytial virus(RSV) infection on airway inflammation and the function of CD8^+ T lymphocytes in ovabumin(OVA)-sensitized BALB/c mice

目的观察呼吸道合胞病毒(RSV)对致敏小鼠气道炎症和CD8+T细胞功能的影响。方法BALB/c小鼠40只,随机分成4组,分别为磷酸盐缓冲液(PBS)对照组、鸡卵白蛋白(OVA)组、RSV组、OVA/RSV组;应用OVA腹腔注射致敏、OVA气道雾化结合RSV滴鼻激发哮喘;支气管肺泡灌洗液(BALF)作细胞分类计数;酶联免疫吸附试验(ELISA)测定BALF上清中白细胞介素(IL)-4、IL-5、干扰素(IFN)-γ含量;苏木精-依红(HE)染色观察肺病理变化;采用三色光流式细胞分析法测定气管旁淋巴结(PBLN)中CD4+、CD8+T细胞及细胞内细胞因子IFN-γ、IL-4、IL-5表达与TH2/TH1、Tc2/Tc1比值变化。结果(1)BALF中细胞总数及分类与OVA组比较,OVA/RSV组细胞总数、嗜酸性粒细胞、淋巴细胞均明显增加(分别P<0.01);与RSV组比较,OVA/RSV组细胞总数、嗜酸性粒细胞明显增加(分别P<0.01)。(2)BALF上清中细胞因子含量与OVA组比较,OVA/RSV组IFN-γ、IL-4、IL-5含量均明显升高(分别P<0.01);与RSV组比较,OVA/RSV组IFN-γ无明显变化,而IL-4、IL-5显著上升(分别P<0.01)。(3)肺组织病理OVA/RSV组与其他各组比较气道黏膜增厚,管腔狭窄、收缩,上皮破坏,管壁周围炎症细胞浸润明显加重。(4)PBLN中CD4+(IFN-γ+、IL-4+、IL-5+)、CD8+(IFN-γ+、IL-4+、IL-5+)T细胞各占CD3+T细胞百分比及TH2/TH1、Tc2/Tc1比值变化与OVA组比较,OVA/RSV组CD8+(IFN-γ+、IL-4+、IL-5+)T细胞百分比、Tc2/Tc1比值增加(分别P<0.01),TH2/TH1比值无明显变化。与RSV组比较,OVA/RSV组CD4+(IL-4+、IL-5+)T细胞、TH2/TH1比值、CD8+(IL-4+、IL-5+)T细胞、Tc2/Tc1比值均明显上升(分别P<0.01)。结论(1)OVA致敏小鼠RSV感染后可明显加重气道炎症,TH2、TH1型炎症均加强,且以TH2型炎症加重为主。(2)OVA致敏小鼠RSV感染后可引起CD8+T细胞数量及功能改变,即由产生IFN-γ+为特征的Tc1细胞向产生IL-4+、IL-5+为特征Tc2细胞转化,并可能与气道内IL-4、IL-5升高及嗜酸性粒细胞的大量募集有关。

Objective To study the effect of RSV infection on the development of airway inflammation and the function of CD8^＋ T lymphocyte in OVA-sensitized BALB/c mice. Methods Forty mice were randomly divided into four groups： PBS control group, RSV group, OVA group and OVA/RSV group. Cells in BALF were counted and classified and the supematants of the bronchoalvoelar lavage fluid（BALF） were used for the detection of IL-4, 11-5 and IFN -γ. Histopathological changes were checked by HE staining. The percentage of CD4^＋ （IFN- γ^＋ , IL-4^＋ , IL-5^＋ ）, CD8^＋ （IFN-γ^＋ , IL-4^＋ , IL-5^＋ ） T lymphocyte and the ratio of TB 2/TH 1, Tc2/Tc1 in peribronchial lymph nodes（PBLN） were analysed by three-color flow eytometry method. Results Total BALF cells, eosinophils and lymphoeytes from OVA/RSV group were significantly higher than those in OVA group respectively （ P 〈0.01）; more cosinophils were founde in OVA/RSV group than that in RSV group（ P 〈0.01）. IFN-γ, IL-4 and IL-5 levels in BALF from OVA/RSV group increased greatly as compared with OVA group（ P 〈0.01 respectively） ; meanwhile there is no marked change in IFN-γ level（ P 〉 0.05）, but IL-4, IL-5 levels increased in OVA/ RSV group as eomtmred with RSV group respectively（ P 〈 0.01）. More marked and extensive airway inflammatory cells infiltration in OVA/RST group were observed than that in all the other groups. The percentage of CD8^＋ （IFN- γ^＋, IL-4^＋ , IL-5^＋ ） T lymphocyte and the ratio of Tc2/Tc1 from the OVA/RSV group were significantly higher than those in OVA group respectively（ P 〈 0.01） but there is no marked change in the ratio of TH2/TH1 ; the percentage of CD4^＋ （IL-4^＋ , IL-5^＋ ）, CD8^＋ （IL-4^＋ , IL-5^＋ ） T lymphocyte, the ratio of TH2/TH1 and Tc2/Tc1 from OVA/RST group were higher than those in RSV group respectively （ P 〈 0.01 ）. Condusiem RSV infection in OVA-sensitized BALB/c mice caused severe airway inflammation which resulted in the increase of TH 1-like and TH2-like cytokine response. RSV infection in OVA-sensitized BALB/c mice also induced the increase of the cell count and function change of CD8^＋ T lymphocyte, namely CD8^＋ T lymphocyte transfer from Tcl which is characterized by excreting IFN-γ to Tc2 excreting IL-4 and IL-5, which maybe explain the increase of IL-4, IL-5 and the gathering of eosinophils in the airway.