Primary Study On The Relationship Between The Phenomena Of The Formation Of Stone In Bile Duct Following Liver Transplantation And Mucin As Pro-nucleating Factor

The biliary complications following orthotopic liver transplantation(OLT) is a main factor to affect long survival of patients. It includes biliary stone,sludge and biliary cast syndrome and so on.Though biliary cast was distinguished from biliary stone following OLT by physical and chemical characteristics, the former finally forms stone-like material in bile duct.Since these two complications have the formation of calculi in bile duct,thus in our study we regard them as a kind of biliary complication with the process of formation of calculi in bile duct after OLT.Many evidences have suggested that mucin, a pro-nucleating factor in bile, is related to formation of biliary stone. Mucin is divided into two types.One is transmembrane binding type,another is secreted type. Mucin is located in reticulation, it's easy to bind to granule of bilirubin or exfoliative cell, resulting in accumulation and formation of calculi.Thus, mucin acts as bridge and skeleton in the process of the formation of calculi.Myristoylated alanine-rich C-kinase substrate(MARCKS) is the major substrate of protein kinase C, it has been shown that MARCKS is a key molecule to regulate mucin secretion in human airway, via promoting coordination of granule of mucin with cytoskeletal protein and secrection of mucin granules through extocysis.Presently, ischemia-reperfusion(IR) injury is an unavoidable pathological course, the bile duct of donor is a sensitive target of IR, it experienced multistrike such as warm ischemia, cold preservation damage and reperfusion damage.During these process, the expression levels of TNF-α, 11-2 and I1-6 are upregulation. Many evidences have indicated that the secretion of mucin is associated with inflammatory cytokine such as TNF-αand oxygen free radicals.Therefore, we focus on two questions, firstly we try to understand the relationship between mucin and the formation of biliary stone or cast after OLT, secondly we try to observe the effect of cold preservation and IR of OLT on the secretion of mucin. Firstly, we used chemical quantitive method to investigate the components of the clinical specimens of biliary stone and cast following OLT. We found that bilirubin was the major component. Meanwhile we studied this sample by scan electron microscope, we noticed that cholesterol crystal and granule of bilirubin accumulated over the matrix which was constituted mainly by mucin. We used immunofluoresence to detect the expression of mucinl and mucin4 in frozen slice of biliary stone and cast after OLT.Besides, Western blot and PCR demonstrated that synthesis and secrection of mucin by hepatobiliary system elevated obviously.Therefor, mucinl and mucin4 were associated with the phenomena of the formation of stone following OLT. Thus,we hypothesized that mucin played critical role in the formation of biliary stone and cast after OLT.Then, Wistar rat was used to establish rat orthotopic liver transplantation model with hepatic arterial reconstruction and biliary out-drainage, the mean anhaepatic phase was 16.3±2.4min, the operational successful rate was 94.67%, mortality was 5.33%, no thrombus was found in cuff. This animal model was a ideal model with high stability and reproducibility to investigate biliary complication after OLT. By using this model we observed the effect of different time of cold preservation and postoperation on mucin secretion after OLT and explored the possible regulating mechanism.The expression of mucin in bile following rat OLT was positive correlated with prolonging time of cold presavation and postoperation, it reached peak at postoperation day 7, especially in group CP12h represented obviously. Meanwhile, the positive expression of mucinl and mucin4 of rat hepatobiliary tract after OLT by immnohistochemistry was consistent with the change of mucins in bile. Western blot and RT-PCR showed that the expressiong level of protein of mucinl and mucin4 and mRNA of mucinl in rat liver were increased, the results indicated that the change was associated with time of cold presavation and postoperation.Therefore, cold presavation and ischemia reperfusion were important factors to affect the synthesis and secrection of mucin.Finally, we used immnohistochemistry to detect the expression level of MARCKS, both in patients of biliary complication and rats after OLT. MARCKS expression level was increased.The result was coincide with mucin's, but the relationshiop between mucin and MARCKS needed more research.In summary, mucin is related with the formation of stone in bile duct following OLT, cold preservation and ischemia reperfusion injury induced MARCKS may play important roles in this process.