Immunohistochemical and immunoelectron microscopic analyses of alpha-amylase isozymes in human intrahepatic biliary epithelium and hepatocytes.

The expression and localization of the pancreatic and salivary isozymes of alpha-amylase in the intrahepatic biliary epithelium and hepatocytes were examined by the immunohistochemical method with polyclonal and monoclonal antibodies in 45 normal autopsied human livers. Immunoelectron microscopic studies with the protein A-gold method were performed with the monoclonal antibodies (MAb) on seven of the livers. The intrahepatic biliary system was divided into large ducts, septal ducts, interlobular ducts, bile ductules, and peribiliary glands. Immunohistochemically, pancreatic isozyme was observed in the supranuclear cytoplasm of the epithelium of large ducts, septal ducts, and peribiliary glands in almost all livers. Interlobular ducts expressed pancreatic isozyme in only four (9%) livers. Bile ductules and hepatocytes were negative for pancreatic isozyme in all cases. Expression of salivary isozyme was observed in the supranuclear cytoplasm of the epithelium of large ducts, septal ducts, interlobular ducts, bile ductules, and peribiliary glands in almost all livers, although the expression in interlobular ducts and bile ductules was weak. Hepatocytes were weakly positive for salivary isozyme. Immunoelectron microscopy revealed that both pancreatic and salivary isozymes were located in the supranuclear cytoplasm of the epithelium of large ducts, septal ducts, and peribiliary glands, and that hepatocytes had no pancreatic isozyme but contained salivary isozyme. These data suggest that pancreatic and salivary isozymes of alpha-amylase are produced by the intrahepatic biliary epithelium and secreted into intrahepatic biliary lumens, and that they may play an important role in the physiology of the intrahepatic biliary tree and hepatic bile. It is also suggested that hepatocytes produce a small amount of salivary alpha-amylase that may be secreted into the biliary tree.     

Involvement of Ras in extraembryonic endoderm differentiation of embryonic stem cells

Embryonic stem (ES) cells, derived from the inner cell mass of blastocyst can differentiate into multiple cell lineages. In this study, we examined the possible involvement of Ras in ES cell differentiation. We found that Ras was activated upon formation of embryoid bodies (EBs), an initial step in ES cell differentiation. When expressed during EB differentiation, a dominant-negative mutant of Ras suppressed induction of marker genes for extraembryonic endoderm differentiation, including GATA-4, GATA-6, alpha-fetoprotein, and hepatocyte nuclear factor 3beta, while an activated mutant promoted their induction. Expression of a Ras mutant that selectively activates the Raf/MEK/Erk pathway also enhanced induction of extraembryonic endoderm markers, and treatment with a MEK inhibitor resulted in their decreased expression. In addition, Ras stimulated downregulation of Nanog, a suppressor of endoderm differentiation in ES cells. These data suggest that Ras activation during EB differentiation plays a crucial role in initiation of extraembryonic endoderm differentiation.     

Biliary papillary neoplasm of the liver

Biliary papillary neoplasia of the liver characterized by intraductal papillary growth of neoplastic biliary epithelia with a fine fibrovascular stalk has been sporadically reported, and includes intraductal growing cholangiocarcinoma and biliary papillomatosis. In addition, biliary papillary dysplasia and in situ and microinvasive carcinoma with papillary configuration reported in hepatolithiasis and in other chronic biliary diseases, could be included in this category. Usually, they arise in the intrahepatic large bile ducts, and the neoplastic and non-neoplastic parts of the intrahepatic biliary tree show saccular and segmental dilatation with mucin hypersecretion. This neoplasia frequently shows intraductal spreading and peribiliary glandular involvement. Acute repeated episodes of cholangitis or obstructive jaundice are a frequent clinical manifestation. Gastroenteric metaplasia with aberrant expression of cytokeratin 20, MUC2, MUC5AC, and/or MUC6, is frequent in the neoplastic parts, and biliary epithelial dysplasia with such metaplasia may give rise to in situ and then invasive carcinoma in hepatolithiasis. Interestingly, this type tends to contain foci of mucinous carcinoma elements, and this element may be predominant (mucinous carcinoma). Some may progress to "mucinous biliary cystadenocarcinoma" without ovarian mesenchymal stroma and with intraluminal continuous growth into the neighboring bile duct lumens. Interestingly, the biliary papillary neoplasm resembles histologically, phenotypically and clinically intraductal papillary mucinous neoplasm of the pancreas which is now being established as an infrequent, slow-growing pancreatic neoplasm. Recognition of such biliary papillary neoplasm with respect to the pancreatic equivalent may lead to a better understanding and further studies of the intrahepatic biliary neoplasm.     

Expression profiles of MUC mucins and trefoil factor family (TFF) peptides in the intrahepatic biliary system: physiological distribution and pathological significance

Mucin secreted by mucosal epithelial cells plays a role in the protection of the mucosal surface and also is involved in pathological processes. So far, MUC1-4, 5AC, 5B, 6-8, 11-13 and 15-17 genes coding the backbone mucin core protein have been identified in humans. Their diverse physiological distribution and pathological alterations have been reported. Trefoil factor family (TFF) peptides are mucin-associated molecules co-expressed with MUC mucins and involved in the maintenance of mucosal barrier and the biological behavior of epithelial and carcinoma cells. Intrahepatic biliary system is a route linking the bile canaliculi and the extrahepatic bile duct for the excretion of bile synthesized by hepatocytes. Biliary epithelial cells line in the intrahepatic biliary system, secreting mucin and other molecules involved in the maintenance and regulation of the system. In this review, the latest information regarding properties, expression profiles and regulation of MUC mucins and TFF peptides in the intrahepatic biliary system is summarized. In particular, we focus on the expression profiles and their significance of MUC mucins in developmental and normal livers, various hepatobiliary diseases and intrahepatic cholangiocarcinoma.     

Clinical course after corticosteroid therapy in IgG4-related aortitis/periaortitis and periarteritis: a retrospective multicenter study

Introduction

Immunoglobulin G4 (IgG4)–related aortitis/periaortitis and periarteritis are vascular manifestations of IgG4-related disease. In this disease, the affected aneurysmal lesion has been suspected to be at risk of rupture. In this study, we aimed to clarify the clinical course after corticosteroid therapy in IgG4-related aortitis/periaortitis and periarteritis.

Methods

We retrospectively evaluated clinical features, including laboratory data, imaging findings and the course after corticosteroid therapy, in 40 patients diagnosed with IgG4-related aortitis/periaortitis and periarteritis on the basis of periaortic/periarterial radiological findings, satisfaction of the comprehensive diagnostic criteria or each organ-specific diagnostic criteria, and exclusion of other diseases.

Results

The patients were mainly elderly, with an average age of 66.4 years and with a marked male predominance and extensive other organ involvement. Subjective symptoms were scanty, and only a small proportion had elevated serum C-reactive protein levels. The affected aorta/artery were the abdominal aortas or the iliac arteries in most cases. Thirty-six patients were treated with prednisolone, and the periaortic/periarterial lesions improved in most of them during the follow-up period. Two (50.0%) of four patients with luminal dilatation of the affected lesions before corticosteroid therapy had exacerbations of luminal dilatation after therapy, whereas none of the twenty-six patients without it had a new appearance of luminal dilatation after therapy.

Conclusions

The results of this retrospective multicenter study highlight three important points: (1) the possibility of latent existence and progression of periaortic/periarterial lesions, (2) the efficacy of corticosteroid therapy in preventing new aneurysm formation in patients without luminal dilatation of periaortic/periarterial lesions and (3) the possibility that a small proportion of patients may actually develop luminal dilatation of periaortic/periarterial lesions in IgG4-related aortitis/periaortitis and periarteritis. A larger-scale prospective study is required to confirm the efficacy and safety of corticosteroid therapy in patients with versus those without luminal dilatation and to devise a more useful and safe treatment strategy, including administration of other immunosuppressants.     

Proinflammatory cytokine-induced cellular senescence of biliary epithelial cells is mediated via oxidative stress and activation of ATM pathway: a culture study

Cellular senescence is reportedly involved in cholangiopathy in primary biliary cirrhosis and oxidative stress is proposed as a pathogenetic factor in biliary epithelial cells (BECs). This study investigated the involvement of proinflammatory cytokines (IFN-beta, IFN-gamma and TNF-alpha) and ataxia telangiectasia-mutated (ATM)/p53/ p21(WAF1/Cip1) pathway with respect to oxidative stress in cellular senescence of BECs. H(2)O(2) treatment (oxidative stress) induced phosphorylation (activation) of ATM and p53 and also p21(WAF1/Cip1) expression in BECs. Treatment with inflammatory cytokines generated reactive oxygen species (ROS) in cultured BECs followed by activation of the ATM/p53/p21(WAF1/Cip1) pathway and the induction of cellular senescence. Pre-treatment with ATM inhibitor (2-aminopurine) and antioxidant (N-acetylcysteine) significantly blocked the cellular senescence of BECs induced by oxidative stress or inflammatory cytokines. In conclusion, proinflammatory cytokines induce ROS generation and activate the ATM/p53/p21(WAF1/Cip1) pathway, followed by biliary epithelial senescence. This senescent process may be involved in the development of destructive cholangiopathy in humans.     

Effects of autophagy inducers on recombinant antibody production in insect cells

Insect cells have recently proven to be an excellent platform for the high-level production of functional recombinant proteins. Autophagy is an important mechanism that promotes cell survival by eliminating damaged organelles and protein aggregates, and it also may influence recombinant protein production. In the present study, we compared the effects that autophagy inducers rapamycin, everolimus, and lithium chloride exert on recombinant lepidopteran insect cells that secrete an engineered antibody molecule. Compared with nontreatment, treatment with either rapamycin or everolimus prolonged cell growth to allow high cell density, improved viability in the declining phase, and then increased the yield of secreted antibodies. These positive effects appeared to be induced via autophagy since autophagosomes were clearly detected, particularly in cells treated with rapamycin or everolimus. Unlike rapamycin, another autophagy inducer, FK506, was ineffective in insect cells. The addition of an appropriate autophagy inducer may be effective in increasing the productivity of recombinant proteins in insect cells.

     

Apical Membrane Expression of Distinct Sulfated Glycans Is a Characteristic Feature of Ductules and Their Reactive and Neoplastic Counterparts

Intrahepatic bile ducts transport bile between bile canaliculi and the extrahepatic bile duct. The luminal surface of this tract is lined by a layer of biliary epithelial cells, or cholangiocytes, which secrete mucins consisting of scaffold proteins and O-glycosidically linked carbohydrate side chains. Although mucin core proteins have been extensively investigated, the structure and function of carbohydrate side chains have not. Here, we demonstrate that distinct sulfated glycans positive for MECA-79, R-10G, and 297-11A, but not 5D4, monoclonal antibodies are expressed in the cytoplasm of cells of large-sized ducts and in the apical membrane of cells in ductules, and that R-10G immunolabeling is partially eliminated by endo-β-galactosidase digestion, supporting the presence of N-acetylglucosamine-6-O-sulfated N-acetyllactosamine structures. We observed comparable apical membrane-predominant staining in ductular reactions seen during regeneration that occurs in various liver diseases and in cholangiolocarcinoma, a subtype of small duct-type intrahepatic cholangiocarcinoma (iCCA). Apical membrane expression of distinct sulfated glycans in large duct-type iCCA was negligible. Intriguingly, under pathological conditions, endo-β-galactosidase digestion almost completely eliminated R-10G immunoreactivity. These findings suggest that apical membrane expression of distinct sulfated glycans is a characteristic feature of ductules and their reactive and neoplastic counterparts     

GNAS and KRAS Mutations are Common in Intraductal Papillary Neoplasms of the Bile Duct

Intraductal papillary neoplasms of the bile duct (IPNB) shows favorable prognosis and is regarded as a biliary counterpart of intraductal papillary mucinous neoplasm (IPMN) of the pancreas. Although activating point mutations of GNAS at codon 201 have been detected in approximately two thirds of IPMNs of the pancreas, there have been few studies on GNAS mutations in IPNBs. This study investigates the status of GNAS and KRAS mutations and their association with clinicopathological factors in IPNBs. We examined the status of GNAS mutation at codon 201 and KRAS mutation at codon 12&13, degree of mucin production and immunohistochemical expressions of MUC mucin core proteins in 29 patients (M/F = 15/14) with IPNB in intrahepatic and perihilar bile ducts (perihilar IPNB) and 6 patients (M/F = 5/1) with IPNB in distal bile ducts (distal IPNB). GNAS mutations and KRAS mutations were detected in 50% and 46.2% of IPNBs, respectively. There was no significant correlation between the status of GNAS mutation and clinicopathological factors in IPNBs, whereas, the status of KRAS mutation was significantly inversely correlated with the degree of MUC2 expression in IPNBs (p<0.05). All IPNBs with GNAS mutation only showed high-mucin production. Degree of mucin production was significantly higher in perihilar IPNBs than distal IPNBs (p<0.05). MUC2 and MUC5AC expression was significantly higher in IPNBs with high-mucin production than those with low-mucin production (p<0.01 and p<0.05, respectively). In conclusions, this study firstly disclosed frequent GNAS mutations in IPNBs, similarly to IPMNs. This may suggest a common histopathogenesis of IPNBs and IPMNs. The status of KRAS mutations was inversely correlated to MUC2 expression and this may suggest heterogeneous properties of IPNBs. IPNBs with high-mucin production are characterized by perihilar location and high expression of MUC2 and MUC5AC, irrespective of the status of GNAS and KRAS mutations.     

Activation of the PI3K/mTOR Pathway Is Involved in Cystic Proliferation of Cholangiocytes of the PCK Rat

The polycystic kidney (PCK) rat is an animal model of Caroli’s disease as well as autosomal recessive polycystic kidney disease (ARPKD). The signaling pathways involving the mammalian target of rapamycin (mTOR) are aberrantly activated in ARPKD. This study investigated the effects of inhibitors for the cell signaling pathways including mTOR on cholangiocyte proliferation of the PCK rat. Cultured PCK cholangiocytes were treated with rapamycin and everolimus [inhibitors of mTOR complex 1 (mTOC1)], {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 [an inhibitor of phosphatidylinositol 3-kinase (PI3K)] and NVP-BEZ235 (an inhibitor of PI3K and mTORC1/2), and the cell proliferative activity was determined in relation to autophagy and apoptosis. The expression of phosphorylated (p)-mTOR, p-Akt, and PI3K was increased in PCK cholangiocytes compared to normal cholangiocytes. All inhibitors significantly inhibited the cell proliferative activity of PCK cholangiocytes, where NVP-BEZ235 had the most prominent effect. NVP-BEZ235, but not rapamycin and everolimus, further inhibited biliary cyst formation in the three-dimensional cell culture system. Rapamycin and everolimus induced apoptosis in PCK cholangiocytes, whereas NVP-BEZ235 inhibited cholangiocyte apoptosis. Notably, the autophagic response was significantly induced following the treatment with NVP-BEZ235, but not rapamycin and everolimus. Inhibition of autophagy using siRNA against protein-light chain3 and 3-methyladenine significantly increased the cell proliferative activity of PCK cholangiocytes treated with NVP-BEZ235. In vivo, treatment of the PCK rat with NVP-BEZ235 attenuated cystic dilatation of the intrahepatic bile ducts, whereas renal cyst development was unaffected. These results suggest that the aberrant activation of the PI3K/mTOR pathway is involved in cystic proliferation of cholangiocytes of the PCK rat, and inhibition of the pathway can reduce cholangiocyte proliferation via the mechanism involving apoptosis and/or autophagy.