| Obstructive jaundice is a common clinical disease with cholestasis,which caused by intrahepatic or extrahepatic biliary mechanical obstruction,the influence of complications including hyperbilirubinemia,endotoxemia,bacteremia and changes of oxidative stress state on liver,intestinal barrier injury and other organ dysfunction,which has been a hot issue of concern.Studies on liver injury of obstructive jaundice have been made great progress,but there are still many mechanisms are not fully understood,even greater breaktroughs and discoveries need further studies.Modern researches have gradually realized that mucin is expressed specifically by intrahepatic bile duct under normal circumstances,which plays an important role in maintaining liver barrier homeostasis.More and more researches have found the abnormal expression and altered distribution of MUC in the intrahepatic bile duct exertes great influence on development and prognosis of biliary tract disease.The study found that chronic proliferative cholangitis that caused by excessive secretion of MUC5 and MUC2 in the intrahepatic bile duct was the main pathogenic factor of intrahepatic biliary stone formation.Among the identified secreted gel-forming mucins,especially MUC2 is the main composition of intestinal mucous layer,and involves in composing the protective barrier of mucosa.A large number of O-glycosylation chains provide better adhesion function,and different glycosylations of the adjacent glycan chains which are connected by molecular covalent bonds promot the formation of gels.Previous researches of MUC2 focus on gastrointestinal tract,in normal intestinal mucus,MUC2 played a crucial role in the protection on the intestinal barrier.Many studies have confirmed that the intestinal mucosal barrier injuried in obstructive jaundice,intestinal mucus imparired,lead to changes of MUC2 protein expression,the steady imbalance occurred caused by bacteria in the intestinal mucosa,so made inflammation worse.In addition,abnormal expression of MUC2 in the intrahepatic bile ducts of inflammatory biliary diseases was pay attention to the damage effected on the liver barrier.Currently no studies on expression of MUC2 in the intrahepatic bile duct in OJ rats are found.So it is of important clinical significance to carry out research projects on liver barrier injury and expression of intrahepatic bile duct MUC2 in rats with OJ.For patients with obstuctive jaundice,surgery is still the main treatment method,but it is generally considered to be associated with a higher incidence of complications and mortality,most scholars support that preoperative biliary drainage is regarding its benefits in reducing the complications,whereas the operation itself will also increase the risk of complications.Therefore there are still debates over whether perform in patients with malignant OJ.Furthermore,it is also controversial which is the appropriate drainage method,internal biliary drainage(ID)or external biliary drainage(ED).So the present study is designed to explore the effect of internal and external biliary drainage on expression of intrahepatic bile duct MUC2 in rats with OJ,which provides more guidance for clinical treatment of patients with OJ.The experiment contents are as follows:Objective: to explore the relevance of liver barrier injury and expression of intrahepatic bile duct MUC2 in rats with OJ,along with the influence and significance of internal and external biliary drainage on expression of intrahepatic bile duct MUC2 in rats with OJ.Methods: The pathological morphological changes of liver and intrahepatic bile ducts were observed by hematoxylin and eosin(HE)staining.The distributions and expressions of MUC2 in the intrahepatic bile duct were evaluated by immunohistochemistry(IHC)and Real time-PCR.Results:1 The TBIL levels of OJ group(107.440±18.150?mol/L)were significantly higher than SH group(21.130±3.230?mol/L)(*P<0.01).However,no significant difference was noted between ID group(30.230±11.860?mol/L)and ED group(35.640±11.860?mol/L)(P=0.454).Compared with SH group(40.460±9.430U/L),the ALT levels of OJ group(122.390±35.310U/L)were strongly increased(*P<0.01).Results showed that ID group(56.500±19.190U/L)and ED group(59.690±19.700U/L)could decrease the ALT levels,but no significant difference occurred among various bile drainages(P=0.793).The AST levels of OJ group(409.760±72.500U/L)were significantly higher than SH group(89.050±28.840U/L)(*P<0.01).ID group(178.910± 66.870U/L)and ED group(109.340±37.900U/L)were obviously lower compared to OJ group(?P<0.01).There was significant difference between ID group and ED group(#P<0.05).2 The serum endotoxin levels of OJ group rats(0.940±0.290EU/ml)were significance higher than SH group rats(0.160±0.100EU/ml)(*P<0.01).However the serum endotoxin levels of ID group(0.230±0.120EU/ml)and ED group(0.450±0.180EU/ml)were obviously lower compared to OJ group(?P<0.01).ID group is lower than ED group(#P<0.05).3 Hisological examination showed liver and intrahepatic bile duct.It showed normal liver lobules and regular distribution of intrahepatic bile duct in SH group.Compared with SH group,there were some alterations in OJ group that included disappearing of liver lobules,intrahepatic bile duct hyperplasia and disordered arrangement,fibrosis and inflammatory cells infiltration.In ID group and ED group,there was a certain recovery of liver lobules and inflammatory cells infiltration compared with OJ group,but a part of fibrosis and intrahepatic bile duct hyperplasia still existed.The degree of fibrosis and inflammatory cells infiltration in ED group was more obvious than ID group.4 According to immunohistochemical staining,the overexpression of MUC2 was significantly detected in the intrahepatic smaller bile duct in OJ group(OD 0.022±0.003),compared to SH group(OD 0.004±0.002)(*p<0.01).In OJ group it was found the positive particles were widely distributed and deeperly stained,however the expression of MUC2 in the intrahepatic bile duct was weaker in SH group,the positive particles showed lower density and weaker color.The expressions of ID group(OD 0.008±0.002)and ED group(OD 0.014±0.001)were significantly lower than OJ group(?P<0.01).The expression of MUC2 in ED group was increased than ID group,the differences were statistical significance(#P<0.05).5 According to the results of Real time-PCR,the expression of MUC2 m RNA in the intrahepatic bile duct in OJ group(0.390±0.080)was higher than SH group(0.100±0.030),the differences were significant(*P<0.01).ID group(0.170±0.010)and ED group(0.240±0.050)were lower than OJ group(?P<0.01).The expression of MUC2 m RNA in the intrahepatic bile duct in ED group was higher than ID group,and the differences were statistical significance(#P<0.05).Conclusion:1 Obstructive jaundice might induce serious endotoxemia,which could lead to liver barrier damage.Hisological examination showed there were some alterations in OJ group that included disappearing of liver lobules,intrahepatic bile duct hyperplasia and disordered arrangement,fibrosis and inflammatory cells infiltration,and the expression of MUC2 in the intrahepatic smaller bile duct with OJ rats was significantly enhanced,it could indicate abnormal overexpression of MUC2 intrahepatic bile duct might involve in the process of liver barrier injury in OJ rats.2 Internal drainage and external drainage could significantly reduce the endotoxemia,and liver barrier injury was improved in different extent.Hisological examination showed there was a part of fibrosis and intrahepatic bile duct hyperplasia still existed and inflammatory cells infiltration through bile drainage reduced,and the expression of MUC2 protein and gene in the intrahepatic smaller bile duct was significantly inhibited.Furthermore,internal drainage could reverse the pathology in greater degree relative to external drainage,which indicated the mechanism of internal drainage superior to external drainage might be related to the regulation of MUC2 expression in the intrahepatic bile duct. |
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