Objective: To investigate the pathogenic mechanisms of airway inflammation and recurrent wheezing induced by recurrent respiratory virus infection after respiratory syncytial virus (RSV) infection.
Methods: Sixty-four female BALB/c mice (aged 6-8 weeks) were randomly divided into four groups: control, RSV, Poly(I:C), and RSV+Poly(I:C) (n=16 each). The bronchoalveolar lavage fluid (BALF) was collected on the 3rd day after Poly(I:C) administration, and the total cell number and differential counts in BALF were determined. Hematoxylin-eosin staining was used to observe pulmonary pathological changes. The airway responsiveness was detected. ELISA was used to measure the levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-13 (IL-13), matrix metallopeptidase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in BALF.
Results: Compared with the other three groups, the RSV+Poly(I:C) group had significant increases in the total number of inflammatory infiltrating cells in the airway, airway responsiveness, and MMP-9 level in BALF (P<0.05). The RSV+Poly(I:C) group showed more severe pulmonary tissue injuries compared with the control and RSV groups (P<0.01). Compared with the RSV group, the RSV+Poly(I:C) group showed significant reductions in the levels of IL-4 and TIMP-1 in BALF (P<0.01).
Conclusions: Viral re-infection in the late stage of RSV infection may cause an imbalance of MMP-9/TIMP-1 expression and thus contribute to aggravated airway inflammation.
目的: 探讨呼吸道合胞病毒(RSV)感染后再发呼吸道病毒感染时诱发气道炎症及反复喘息的致病机制。
方法: 64只6~8周雌性BALB/c小鼠随机分为对照组、RSV组、Poly(I:C)组及RSV+Poly(I:C)组(n=16)。收集各组肺泡灌洗液(BALF), 计数BALF中细胞总数及分类计数, 苏木精-伊红(HE)染色观察肺部病理损伤, 检测小鼠气道反应性(AHR), ELISA法检测BALF中IFN-γ、IL-4、IL-13、基质金属蛋白酸9(MMP-9)及基质金属蛋白酶抑制物-1(TIMP-1)水平。
结果: RSV+Poly(I:C)组小鼠的气道炎症细胞浸润总数及AHR较其他3组显著增高(P＜0.05)。RSV+Poly(I:C)组小鼠的肺组织病理损伤较对照组及RSV组加重(P＜0.01);BALF中MMP-9水平较其他3组明显升高(P＜0.05), IL-4及TIMP-1显著低于RSV组(P＜0.01)。
结论: RSV感染后病毒再感染可能引起MMP-9/TIMP-1表达失衡, 加重气道炎症反应。