Role of CD56-expressing immature biliary epithelial cells in biliary atresia

AIM: To analyze the clinical and pathological parameters and expression of the neural cell adhesion molecule(CD56) in patients with biliary atresia(BA).METHODS: Established clinical laboratory markers of hepatic function, including enzyme activity, protein synthesis, and bilirubin metabolism, were evaluated in patients with BA and compared with those in patients with choledochal cysts and neonatal hepatitis. Pathological changes in tissue morphology and fibrosis were examined by histological and tissue collagen staining. Immunohistochemical staining for the biliary epithelial cell markers CD56 and CK19 together with the Notch signaling related molecules Notch1 and Notch2 was performed in the context of alterations in the structure of intrahepatic biliary ducts.RESULTS: Differences in some clinical laboratoryparameters among the three diseases examined were observed, but they did not correlate with the pathological classification of fibrosis in BA. Immunohistochemical staining showed the presence of CD56-positive immature bile ducts in most patients(74.5%) with BA but not in patients with choledochal cysts or neonatal hepatitis. The number of CD56-expressing cells correlated with disease severity, with more positive cells present in the later stages of liver damage(81.8% vs 18.2%). Furthermore, bile plugs were mainly found in CD56-positive immature biliary ducts. Notch signaling was a key regulatory pathway in biliary duct formation and played a role in tissue fibrosis. Notch1 was co-expressed in CD56-positive cells, whereas Notch2 was found exclusively in blood vessels in the portal area of patients with BA. CONCLUSION: The maturation of biliary epithelial cells and the expression of Notch may play a role in the pathogenesis of BA.

Cyclosporine A, FK-506, 40-0-[2-hydroxyethyl]rapamycin and mycophenolate mofetil inhibit proliferation of human intrahepatic biliary epithelial cells in vitro

AIM： To investigate the effect of cyclosporine A （CsA）, FK-506, and mycophenolate mofetil （MMF） and 40-0-[2- hydroxyethyl]rapamycin （RAD） on proliferation of human intrahepatic biliary epithelial cells （BECs） in vitro.METHODS： BECs were isolated from six human liver tissuespecimens with the immunomagnetic separation method and treated with different concentrations of CsA, FK-S06, RAD, and MMF in vitro. Proliferation of the cells was measured by MTT assay at 24 and 48 h after treatment, respectively. One-way analysis of variance was used to analyze the results. Expression of CK 19 in BECs was monitored by flow cytometry and Western blot.RESULTS： Six lines of BECs were established. They survived for 4-18 wk in vitro. Flow cytometry analysis showed that these cells always expressed CK19. CsA, FK-506, RAD, and MMF inhibited proliferation of BECs in a dose-dependent manner. The lowest concentration of CsA, FK-506, RAD, and MMF to inhibit proliferation of BECs （P〈0.05） was 500, 100, 0.25, and 100 pg/L, respectively. However, the expression of CK19 by BECs was not changed.CONCLUSION： CsA, FK-506, RAD, and MMF have an antiproliferative effect on human intrahepatic BECs in vitro, while RAD has the strongest growth-inhibitory effect. Their possible effects on liver regeneration and bile duct injury in transplant patients should be further investigated.

Etiopathogenesis of primary biliary cirrhosis

Primary biliary cirrhosis(PBC) is an autoimmune disease of the liver characterized by progressive bile duct destruction eventually leading to cirrhosis and liver failure.The serological hallmark of the disease is the presence of circulating antimitochondrial antibodies(AMA).These reflect the presence of autoreactive T and B cells to the culprit antigens,the E2 subunits of mitochondrial 2-oxo-acid dehydrogenase enzymes,chiefly pyruvate dehydrogenase(PDC-E2).The disease results from a combination of genetic and environmental risk factors.Genetic predisposition is indicated by the higher familial incidence of the disease particularly among siblings and the high concordance rate among monozygotic twins.Environmental triggering events appear crucial to disrupt a pre-existing unstable immune tolerance of genetic origin allowing,after a long latency,the emergence of clinical disease.Initiating mimetopes of the vulnerable epitope of the PDC-E2 autoantigen can be derived from microbes that utilize the PDC enzyme or,alternatively,environmental xenobiotics/chemical compounds that modify the structure of native proteins to make them immunogenic.A further alternative as a source of antigen is PDC-E2 derived from apoptotic cells.In the effector phase the biliary ductular cell,by reason of itsproclivity to express the antigen PDC-E2 in the course of apoptosis,undergoes a multilineage immune attack comprised of CD4+ and CD8+ T cells and antibody.In this article,we critically review the available evidence on etiopathogenesis of PBC and present interpretations of complex data,new developments and theories,and nominate directions for future research.

Effects of partial portal vein arterialization on the hilar bile duct in a rat model

BACKGROUND: Liver revascularization is frequently required during the enlarged radical operation for hilar cholangio carcinoma involving the hepatic artery. Researchers have carried out a number of experiments applying partial porta vein arterialization (PVA) in clinical practice. In this study we aimed to establish a theoretical basis for clinical application o partial PVA and to investigate the effects of partial PVA on ra hilar bile duct and hepatic functions. METHODS: Thirty rats were randomly and equally assigned into 3 groups: control (group A), hepatic artery ligation+bile duct recanalization (group B), and partial PVA+bile duc recanalization (group C). Proliferation and apoptosis o rat hilar bile duct epithelial cells, arteriolar counts of the peribiliary plexus (PBP) of the bile duct wall, changes in serum biochemistry, and pathologic changes in the bile duc were assessed 1 month after operation. RESULTS: The proliferation of hilar bile duct epithelial cells in group B was greater than in groups A and C (P<0.01). No apoptotic hilar bile duct epithelial cells were detected in any of the groups. The PBP arteriolar counts of the hilar bile duc wall were similar in groups A and C (P>0.05), but the coun was lower in group B than in group A (P<0.01). No statistically significant differences in alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and albumin were found in the 3 groups. The gamma-glutamyltransferase value was higher in group B than in groups A and C (P<0.01) The hepatic tissues of groups A and C showed no significan abnormality. Chronic inflammatory changes in the hilar bile duct walls were observed only in group B. CONCLUSION: Partial PVA can restore the arterial blood supply of the hilar bile duct and significantly extenuate the injury to hilar bile duct epithelial cells resulting from hepatic artery ligation.

Autophagy modulates physiologic and adaptive response in the liver

Autophagy is a physiological process that is ubiquitous and essential to the disposal or recycling of damaged cellular organelles and misfolded proteins to maintain organ homeostasis and survival.Its importance in the regulation of liver function in normal and pathological conditions is increasingly recognized.This review summarizes how autophagy regulates epithelial cell-and non-epithelial cellspecific function in the liver and how it differentially participates in hepatic homeostasis,hepatic injury response to stress-induced liver damage such as cholestasis,sepsis,non-alcoholic and alcohol-associated liver disease,viral hepatitis,hepatic fibrosis,hepatocellular and cholangiocellular carcinoma,and aging.Autophagy-based interventional studies for liver diseases that are currently registered in clinicatrials.gov are summarized.Given the broad and multidirectional autophagy response in the liver,a more refined understanding of the liver cell-specific autophagy activities in a context-dependent manner is necessary。