泡球蚴感染中期小鼠肝脏病灶周围肉芽肿TGF-β1及其受体TβRⅠ和p-Smad2/3的表达及意义

The expression and significance of TGF-β1,TβRⅠ,and p-Smad2/3 during the middle stages of infection in BALB/c mice infected with Echinococcus multilocularis

目的观察泡球蚴感染中期BALB/c小鼠病灶周围肉芽肿中转化生长因子（TGF-β1）及其Ⅰ型受体（TβRⅠ）和p-Smad2/3蛋白的表达及意义。方法 8~10周龄雌性BALB/c小鼠随机分为实验组和对照组。将BALB/c小鼠开腹,肉眼直视下肝左叶注射100μl泡球蚴混悬液,建立小鼠肝泡球蚴感染模型,对照组以相同方法注射等量的生理盐水。于造模第12周时处死小鼠,取肝脏组织,4%甲醛固定、石蜡包埋,4μm连续切片,HE和Masson染色,光镜下观察泡球蚴感染病灶周围病理改变和纤维化程度,采用免疫组织化学技术检测肉芽肿TGF-β1、TβRⅠ受体及p-Smad2/3蛋白的表达。结果实验组小鼠病灶周围以形成典型的大小和形状各异的囊泡为主要特征,囊泡外周纤维结缔组织增生明显,存在不同程度的纤维化。囊泡外围肉芽肿TGF-β1、TβRI和p-Smad2/3的显色指数分别为3.90±1.39、3.18±0.95和3.60±0.93,对照组分别为0.28±0.18、0.32±0.18和0.20±0.14,差异均有统计学意义（P均〈0.01）。结论囊泡外围组织纤维化较重部位TGF-β1、TβRI和p-Smad2/3表达也相应较高,提示TGFβ1/Smad信号通路可能参与泡球蚴感染小鼠病灶纤维化过程。

Objective To observe the expression of TGFβ1,TβRⅠ and p-Smad2/3 in the granuloma of mice infected with Echinococcus multilocularis during the middle stages of infection（12 weeks）.Methods BALB/c mice were randomly divided into an experimental group and control group.The abdomen of mice in the experimental group was opened and mice were injected with 0.1 ml of an E.multilocularis metacestode suspension in the left lobe of the liver;control mice were injected with 0.1 ml saline using the same surgical procedure.Mice were sacrificed at 12 weeks.Liver samples were formalin-fixed and embedded in paraffin and were cut into 4-μm-thick sections.Pathological changes and the extent of liver fibrosis were observed in all of the samples using HE and Masson staining.Expression of TGF-β1,TβRⅠ,and p-Smad2/3 was observed immunohistochemically.Results The experimental group had lesions characterized by many metacestode vesicles with different sizes and shapes.Hyperplasia of fibroconnective tissue with different degrees of fibrosis was apparent around metacestode vesicles.The level of expression of TGFβ1（（3.9±1.39）vs.（0.28±0.18））,TβR I（（3.18±0.95） vs.（0.32±0.18））,and p-Smad2/3（（3.60±0.93）vs.（0.20±0.14）） was higher in periparasitic granulomas in comparison to the control group.Conclusion Pathological injury,fibrosis,and up-regulation of TGF-β1,TβRⅠ,and p-Smad2/3 expression occurred in the mouse liver as a result of E.multilocularis infection,which may indicate that the TGF-β/Smad pathway is involved in parasite-induced hepatic fibrosis in mice.