Effect Of AST On Mice Liver Fibrosis Of Schistosomiasis Japonica And The Expression Of TGF-β1 And Its Receptors

Background and Objective Liver fibrosis of Schistosomiasis japonica is one of the major reasons that leads to hypertension of portal vein,ascites and upper gastrointestinal hemorrhage;it is also the main reason that leads to the death of these patients with Schistosomiasis japonica.The strategy of anti-schistosomal liver fibrosis mainly aims to kill insects,inhibit periovular granulomas,control or even to prevent liver fibrosis.Even though efficacious schistosomicides are given,periovular granulomas and liver fibrosis are still developed.At present,there still have no ideal anti-hepatofibrotic drugs.Astrogalosides(AST) is a new effective anti-hepatofibrotic drug,which is the active compound extract from the root of Astragalus membranaceus, and previous studies have shown its significant anti-inflammatory,anti-hepatic injury, anti-hepatofibrotic and immunomodulatory effects.Up to now,there have no reports on the effect of AST on liver fibrosis of Schistosomiasis japonica in vivo,especially the effect on liver fibrosis after efficacious schistosomicides were given.Studies indicated that liver fibrosis of Schistosomiasis japonica is related to the activation of hepatic stellate cells(HSCs) and portal fibroblasts(PF),it is also known that transforming growth factor- beta 1(TGF-β1) is the strongest factor which activates HSCs and PF and promotes liver fibrosis.In this study,on the basis of understanding the pathologic changes of schistosomal liver fibrosis of mice,the effect of AST on liver fibrosis and the possible mechanisms through the altered expression of TGF-β1 and its receptors were studied. Methods One hundred and twenty ICR mice were infected with cercarie of Schistosoma japonicum.The infected mice were divided randomly into four groups at the end of the 5^th week after infection:model group,high dose astrogaloside group(20 mg/kg per day),low dose astrogaloside group(10 mg/kg per day) and liver protection tablet(Hugan pian) group(540 mg/kg per day) as positive drug control group.Forty days after infection,the four groups were treated with praziquantel(500 mg/kg per day) for 2 days.Thirty healthy ICR mice were used in this study as normal control group. Ten mice in each group were sacrificed at the end of the 6^th,10^th and 14^th week, respectively.Meanwhile,the liver index,hematoxylin and eosin stain and Sirius red stain were used to evaluate the mean area of periovular nodules and the degree of liver fibrosis.Smooth muscle actin(α-SMA),typeⅠandⅢcollagen,TGF-β1 and its receptors(TGF-β1 typeⅠandⅡreceptors)on tissue microarray sections were detected by immunohistochemistry.Quantitative image analysis were employed to study the expression levels of typeⅠandⅢcollagen,TGF-β1 and its receptors,in which mean optical density(MOD) values was used to refer the results.Results(1) At the end of 6^th week after infection with schistosoma japonicum,there are Scattered of acute periovular nodule in mice liver tissues.At the end of 10^th week,it presented chronic periovular granulomas which characterized by fibroblasts,monocytes and massive collagen fibers deposited around periovular nodule.It presented mainly fibrotic nodule and collagen fiber extension along portal area and linked with each other then formation pipe-stem liver fibrosis at the end of 14^th week.(2) At the end of either the 10^th or the 14^th week in groups receiving two different doses of astrogalosides,the mean area of periovular nodule was decreased significantly,the degree of liver fibrosis and the expression of typesⅠandⅢcollagen(P＜0.01 or P＜0.05) were also reduced in comparison with those in the model group.Meanwhile,there was a significant difference in the protein expression of typeⅢcollagen between the high and low dose astrogaloside groups at the end of the 10^th week(P＜0.01).(3) At the end of either the 10^th or the 14^th week in groups receiving two different doses of astrogalosides,the positive reaction ofα-SMA was also reduced in comparison with those in the model group.(4) At the end of either the 10^th or the 14^th week in groups receiving two different doses of astrogalosides,TGF-β1 expression was also reduced as compared with those in the model group;But there were no signifance difference in the expression of TGF-β1 typeⅠandⅡreceptors.(5) At the end of the 6^th week,there were not any differences in all the above parameters among the different groups.Conclusions(1) In this study we success in making mice liver fibrosis model of schistosomiasis japonica.(2) Liver fibrosis of schistosomiasis japonica is related to increasing of myofibroblast,mainly activated HSCs,synthesis of typeⅠand typeⅢcollagen and expression of TGF-β1 and its receptor typeⅠandⅡ.(3) Astrogaloside exerts its effect on hepatic fibrosis in ICR mice with schistosomiasis japonica as these two follow possible mechanisms:a) inhibiting periovular granulomas and reducing the synthesis of typeⅠandⅢcollagen;b)inhibiting HSCs activation and proliferation and down-regulating TGF-β1 expression.