甲氟喹对感染小鼠日本血吸虫虫卵肉芽肿形成影响的初步观察

Preliminary Observation on the Effect of Mefolquine against Egg Granuloma Formation in the Liver of Mice Infected with Schistosoma japonicum

目的探讨甲氟喹对日本血吸虫虫卵肉芽肿形成的影响。方法28只雌性昆明小鼠每鼠感染日本血吸虫尾蚴20条,其中17只小鼠于感染后35 d,用甲氟喹单剂200 mg/kg口服治疗,治疗后3、7、14、21、28和35 d(感染后38、42、49、56、63和70 d),各剖杀2～3只鼠,取肝脏,10%甲醛固定;余11鼠分别于上述时间同时剖杀1～2只,取其肝脏为治疗组的相应对照组。计数各组小鼠肝脏中单个中心含有成熟虫卵的肉芽肿,接目测微计测定其直径,并计算各组肉芽肿平均直径。肝脏切片用苏木素-伊红(HE)、Foot法和Mallory法染色,分别观察虫卵肉芽肿的病理变化、网状纤维和胶原纤维情况。结果感染小鼠口服甲氟喹后3、7、14、21、28和35 d,肝脏单个虫卵肉芽肿平均直径分别为(161±19)、(175±13)、(195±9)、(171±40)、(180±13)和(145±25)μm,均小于各相应对照组[(189±18)、(197±11)、(211±12)、(208±19)、(203±16)和(207±36)μm](P<0.01或P<0.05)。HE染色结果显示,感染小鼠经甲氟喹治疗后,虫卵周围聚集以嗜酸粒细胞为主的炎细胞,可延续至治疗后14～21 d(感染后49～56 d),而对照组的虫卵肉芽肿在感染后42 d已成为纤维性的虫卵肉芽肿;治疗后28～35 d(感染后63～70 d),虫卵肉芽肿均为纤维性,但其边缘较相应对照组的规整。Foot法和Mallory法染色观察可见,经甲氟喹治疗后的14 d内,网状纤维和胶原纤维在虫卵肉芽肿中出现的时间均迟于相应对照组的,纤维量亦明显少于相应对照组;治疗后21 d(感染后56 d),部分虫卵肉芽肿的2种纤维增生情况与相应对照组的无明显差别;但治疗后28～35 d(感染后63～70 d),则鲜见此2种纤维进一步增多和向外延伸。相应对照组的2种纤维则因持续增长而粗密,且向肉芽肿边缘伸展与邻近肉芽肿的纤维相互连接,并分隔肝组织形成网格化。结论甲氟喹对日本血吸虫虫卵肉芽肿的形成具有抑制作用。

Objective To explore whether mefolquine possesses the effect on granuloma formation induced by Schistosoma japonicum eggs. Methods Seventeen out of twenty-eight mice infected with 20 S. japonicum cercariae for 35 days were treated orally with mefloquine at a single dose of 200 mg/kg, and groups of 2-3 mice were sacrificed at various intervals post-treatment. The livers removed from each group of mice were fixed in 10% formaldhyde. While the remained 11 untreated mice divided into 6 groups（1-2 mice per group） were sacrificed at the same time periods as groups of mice treated with mefloquine, and their livers served as untreated corresponding controls. The granulomas with single egg in the center were counted and their diameters were measured using an ocular micrometer. The liver tissue sections were stained with hematoxylin and eosin（HE）, Foot’s or Mallory’s methods for observation on histopathological alteration of egg granulomas, and on the appearance of reticular and collagen fibers within the granulomas. Results After infected mice were treated with mefloquine for 3, 7, 14, 21, 28 and 35 days, i.e., 38, 42, 49, 56, 63, and 70 days post-infection, the mean diameters of granuloma with single egg measured in the liver tissues section were （161±19）, （175±13）, （195±9）, （171±40）, （180±13）, and （145±25） ？滋m, respectively, and each of them was significantly lower than that of its corresponding control group of （189±18）, （197±11）, （211±12）, （208±19）, （203±16）, and （207±36） ？滋m （P〈0.01 or P〈0.05）. Histopatological observation showed that in mice treated with mefloquine, the eosinophil-predominant inflammatory cells around the egg granuloma were sustained to 14-21 d post treatment （49-56 d post infection）, which was significantly different from the corresponding control groups that all the eggs were surrounded by fibroblasts at 42 d post infection. Up to 28-35 d post treatment （63-70 d post infection）, the boundary of egg granulomas distributed in the liver tissues of mefloquine treated groups was neater in comparison to the corresponding control groups. Further observation on the reticular and collagen fibers within the egg granulomas by using specially staining methods demonstrated that in groups of mice treated with mefloquine for 2 weeks, the emergence and amount of the two kinds of fibers were delayed and less in comparison with corresponding control groups. After infected mice treated with mefloquine for 21 d（56 d post infection）, the amount of the two kinds of fibers revealed in some egg granulomas was similar to the corresponding control group, but no further increase in the amount of the fibers, and seldom spread over the boundary of egg granuloma were seen 28 d and 35 d after treatment（63 d and 60 d post infection）. While in corresponding control groups, the two kinds of fibers increased continuously with time post infection to become thick, and spread over the boundary of granuloma to further interconnect with the fibers stretched from the adjacent granuloma, and separate the liver tissue to form the grid-like structure. Conclusion Preliminary observation demonstrates that mefloquine possesses suppressive effect on granuloma formation induced by S. japonicum eggs.