华支睾吸虫感染小鼠肝组织细胞因子动态变化的初步观察

A preliminary study on the dynamic changes of cytokines in liver of mice infected with Clonorchis sinensis

目的观察小鼠感染华支睾吸虫囊蚴后肝脏病理学特征及IFN-γ、IL-4、IL-12表达情况，探讨IFN-γ、IL-4、IL-12在免疫调控中的作用及意义。方法分别在感染后的不同时段剖杀小鼠，取其肝脏，采用石蜡切片，H—E染色，光镜观察肝脏病理变化情况；采用SABC免疫组织化学染色法测定IFN-γ、IL-4、IL-12在华支睾吸虫感染小鼠肝脏组织中表达水平的动态变化。结果H—E染色：感染后1天，小鼠肝脏无明显变化。感染后4天，小鼠肝脏轻度肿胀，肝脏汇管区表现为轻度炎症反应。随着病程的发展病理改变趋于严重。免疫组织化学结果：Th1细胞凶子IL-12和IFN-γ的表达呈现大致相同的趋势，在感染后1周开始上升，在4周达高峰，随后下降，至第12周仍高于正常组水平（P〈0．05）。而IL-4的表达水平则自感染后第1周开始持续上升，-直持续至感染后第12周实验观察结束，且随感染时问延长而明显升高。结论免疫组织化学检测结果提示细胞因子IFN-γ、IL-12和IL-4的阳性表达主要在汇管区、肝小叶坏死区的淋巴细胞和巨噬细胞的胞质，肝细胞未见阳性表达。华支睾吸虫感染的免疫应答发生了由Th1免疫应答向Th2免疫应答转变的趋势；华支睾吸虫病前期Th1细胞免疫应答占优势，后期Th2细胞免疫应答占优势。

Objective To investigate the pathological characteristics of the liver in mice infected with metacercariae of Clonorchis sinensis as well as the expression of IFN-γ, IL-4 and IL- 12, and to explore the roles and significance of IFN -γ, IL -4 and IL - 12 in the immune regulation. Methods Mice infected with metacercariae of Clonorchis sinensis were sacrificed and the livers were obtained, followed by preparation of paraffin sections, H - E staining and light microscopy for the observation of pathological changes of the liver tissues. Immunohistochemical SABC staining was used to detect the dynamic variations of the expression of interferon -γ （IFN -γ）, interleukin -4 （IL- 4） and interleu- kin - 12 （ IL - 12） in the hepatic tissues of mice infected with Clonorchis sinensis. Results H - E staining revealed that there were no significant changes in the liver tissues on the 1st day after infection, while slight swelling with mild inflam- marion in portal areas were evident on the 4th day after infection, and the pathological changes tended to be serious with the progression of the disease, hnmunohistochemical results showed that the expressions of Thl type cytokines IL - 12 and IFN -γ/had similar tendency, which began to rise at week 1 post - infection, reached the peak at week 4 post - infection and then began to decrease till week 12 post - infection at a higher level compared with the normal control groups （P 〈 0.05）. The expression levels of the Th2 type cytokine IL -4 began to rise from the week 1 post - infection and continued to increase till the end of experiment at week 12. The expression levels increased with the duration of infection. Conclu- sion The immunohistochemical results suggested that the positive expression of cytokines IFN - ~, IL - 12 and IL -4 occurred mainly in the cytoplasm of the lyphoeytes and maerophages in the portal area and hepatic lobule with necrosis, whereas in the liver cells there was no positive. The dynamic changes of IL -4, IL - 12, IFN -γ in liver tissues in the infection of Clonorchis sinensis showed a tendency of immunological reaction from Thl type predominant response to Th2 type predominant response along with the prolongation of the infection.