IL-17A通过促进IFN-γ产生或抑制病毒清除参与小鼠呼吸道合胞病毒感染后致病

IL-17A involved in respiratory syncytial virus-associated pathogenesis by promoting IFN-γand inhibiting viral clearance in mice

目的探讨白细胞介素17A(IL-17A)在小鼠呼吸道合胞病毒(respiratory syncytial virus,RSV)感染中的作用。方法6~8周龄雌性野生型C57BL/6小鼠及IL-17A敲除(IL-17A-/-)小鼠各自按随机数字表分为对照组和RSV组,分别滴鼻接种细胞培养上清或RSV A2病毒液。部分小鼠灌取支气管肺泡灌洗液(BALF)并行炎症细胞计数及分类计数;部分小鼠取左肺,HE染色后行组织病理评分;全身体积描记法检测小鼠肺功能;酶联免疫吸附试验(ELISA)检测IFN-γ水平;空斑试验检测RSV病毒滴度。为进一步证实IL-17A与IFN-γ的关系及其在RSV感染中的作用,部分IL-17A-/-小鼠经腹腔注射给予外源性重组IL-17A或重组IFN-γ,部分野生型小鼠经腹腔注射给予特异性IFN-γ单克隆抗体。结果RSV感染后,两种小鼠相比,野生型小鼠BALF中炎症细胞总数、中性粒细胞计数、淋巴细胞计数,气道高反应性,肺组织病理损伤程度、病理评分,IFN-γ水及肺组织中RSV病毒滴度均明显高于IL-17A-/-小鼠。RSV组IL-17A-/-小鼠补充外源性重组IL-17A或重组IFN-γ后,IFN-γ水平明显升高,BALF中炎症细胞计数、气道高反应性、肺组织病理损伤明显增加,外源性重组IL-17A处理后病毒清除显著减少,而外源性重组IFN-γ处理后病毒清除不受影响。RSV组野生型小鼠特异性中和IFN-γ后,BALF中炎症细胞计数、气道高反应性、肺组织病理损伤明显减轻,但病毒清除不受影响。结论IL-17A可能通过促进IFN-γ产生或抑制RSV病毒清除,参与RSV感染后致病。

Objective To identify the role of IL-17A during respiratory syncytial virus(RSV)infection in a mouse model.Methods Female wild-type C57BL/6 mice and IL-17A knockout(IL-17A-/-)mice at the age of 6 to 8 weeks were both randomly divided into two groups:control and RSV groups.Mice in the control groups were given the supernatant of Hep-2 cell culture,while those in the RSV groups were treated with RSV A2 through intranasal administration.Leukocytes in bronchoalveolar lavage fluid(BALF)samples were counted.Left lung tissues were stained with hematoxylin and eosin(HE)to evaluate histopathological scores.Airway hyperresponsiveness(AHR)was measured by whole-body plethysmography.The concentrations of IFN-γwere determined with ELISA.RSV titers were measured by plaque assay.To assess the effects of IL-17A on IFN-γproduction and its role in RSV infection,IL-17A-/-mice were treated with exogenous recombinant murine IFN-γor IL-17A,while wild-type mice were given IFN-γneutralizing antibody intervention.Results The counts of inflammatory cells and neutrophils in BALF,lung tissue histopathological scores,AHR,IFN-γlevels and virus titers of the wild-type group were higher than those of the IL-17A-/-group after RSV infection.IFN-γlevels,inflammatory cell counts in BALF,AHR and lung tissue histopathological scores were significantly increased in RSV-infected IL-17A-/-mice after the intervention of recombinant murine IL-17A or IFN-γ.RSV titers were much higher in the recombinant murine IL-17A-treated group,but not affected by the recombinant murine IFN-γintervention.Inflammatory cell counts in BALF,AHR and lung tissue histopathological scores were significantly decreased in RSV-infected wild-type mice following IFN-γneutralizing antibody treatment,but no significant changes were found in RSV titers.Conclusions IL-17A might be involved in the pathogenesis of pulmonary diseases during RSV infection through promoting IFN-γproduction and inhibiting viral clearance in mice.