bromochloroacetic-acid and alpha-1-Antitrypsin-Deficiency

Proliferation of preexisting bile ducts, ductular metaplasia of hepatocytes and proliferation and differentiation of liver stem cells are discussed in the pathogenesis of neoductular structures in the liver. Under the condition of experimental bile duct obstruction and in extrahepatic bile duct stenosis neoductular structures are first the result of proliferation and sprouting of preexisting ducts and cholangioles. Especially in later stages of cholestasis but also in other chronic progredient liver diseases such as chronic alcoholic liver disease and chronic active hepatitis periportal hepatocytes may show a phenotypic shift towards ductular epithelia. In postnatal liver diseases hepatocytes first express keratin 7 and later keratin 19 during ductular transdifferentiation. This is in contrast to embryonal cholangiogenesis. In alpha-1-antitrypsin-deficiency, hemochromatosis, Wilson's disease, and chronic active hepatitis B cellular deposites typically located in hepatocytes such as alpha-1-AT, siderin, copper, HBs-Ag, and HBc-Ag can also be found in neoductular cells close to hepatocytes. These deposites seem to be retained during the ductular transdifferentiation of hepatocytes. Expression of bile duct-type integrin subtypes and TGF beta 1 in neoductular cells are involved in the changing parenchymal/mesenchymal interplay during neoductogenesis, resulting in periductular basal membrane and periductular fibrosis. In FNH the ductular transdifferentiation of hepatocytes is integrated in the histogenesis of micronodules and portal tract equivalents of these tumor-like lesions. Ductular structures in hepatoblastomas and especially in combined hepatocellular and cholangiocarcinomas (CHCC) may reflect the common embryologic derivation of hepatocytes and biliary epithelia. Non-neoplastic liver tissue in resection specimens of our CHCC showed a lower rate of cirrhosis, and a significantly higher Ki 67-LI of neoductular cells compared to liver tissue in resection specimens of HCC and liver metastases. 3 of 10 CHCC had developed in alpha-1-AT-deficiency, in which this protease-inhibitor was predominantly retained in periportal hepatocytes. These findings in non-neoplastic tumor-bearing liver tissue suggest that CHCC include a special histogenic type of primary liver carcinoma which in analogy to some experimental liver tumors might develop from periportal parenchymal cells.

Topics: alpha 1-Antitrypsin; alpha 1-Antitrypsin Deficiency; Animals; Bile Ducts; Bile Ducts, Extrahepatic; Carcinoma, Hepatocellular; Cell Differentiation; Cell Division; Cholangiocarcinoma; Cholestasis; Copper; Hepatitis B Core Antigens; Hepatitis B Surface Antigens; Hepatoblastoma; Humans; Hyperplasia; Keratins; Liver; Liver Diseases; Liver Neoplasms; Metaplasia

Ballooned hepatocytes distinguish non-alcoholic steatohepatitis (NASH) from steatosis. Such cells contain dilated endoplasmic reticulum and ubiquitin aggregates, characteristics of endoplasmic reticulum stress. Hepatocyte ballooning increases the risk for fibrosis in NASH, suggesting that ballooned hepatocytes release pro-fibrogenic factors. Hedgehog ligands function as pro-fibrogenic factors in liver diseases, but mechanisms for hedgehog ligand production remain poorly understood. We evaluated the hypothesis that endoplasmic reticulum stress induces hepatocyte production of hedgehog ligands that provide paracrine pro-fibrogenic signals to neighbouring cells. In livers from NASH patients, keratin 8/18 and ubiquitin staining demonstrated enlarged, keratin 8/18-negative/ubiquitin-positive hepatocytes (ballooned hepatocytes) that were positive for Sonic hedgehog. In order to model endoplasmic reticulum stress in vitro, primary mouse hepatocytes were treated with tunicamycin. Compared to vehicle, tunicamycin significantly increased Sonic hedgehog and Indian hedgehog expression. Furthermore, conditioned medium from tunicamycin-treated hepatocytes increased Gli-luciferase reporter activity 14-fold more than conditioned medium from vehicle-treated hepatocytes. Cyclopamine (hedgehog signalling inhibitor) abrogated the effect of conditioned medium from tunicamycin-treated hepatocytes, verifying that soluble hepatocyte-derived factors activate hedgehog signalling. Ballooned hepatocytes in NASH patients did not express the hedgehog target gene, Gli2, α-smooth muscle actin or vimentin, but were surrounded by Gli2-positive stromal cells expressing these myofibroblast markers. Trichrome staining demonstrated the accumulation of ballooned hepatocytes in areas of matrix deposition, and numbers of Sonic hedgehog-positive hepatocytes correlated with the degree of ballooning and fibrosis stage. Hepatocytes undergoing endoplasmic reticiulum stress generate hedgehog ligands which act as paracrine pro-fibrogenic factors for hedgehog-responsive stromal cells. These results help to explain why fibrosis stage correlates with hepatocyte ballooning in NASH.

Topics: Adult; alpha 1-Antitrypsin Deficiency; Animals; Biopsy; Cells, Cultured; Endoplasmic Reticulum; Fatty Liver; Hedgehog Proteins; Hepatocytes; Humans; Keratins; Kruppel-Like Transcription Factors; Ligands; Liver; Mice; Mice, Inbred C57BL; Middle Aged; Myofibroblasts; Nuclear Proteins; Proto-Oncogene Proteins c-akt; Stress, Physiological; Stromal Cells; Tunicamycin; Zinc Finger Protein Gli2

Exposure of cells to stress, particularly oxidative stress, leads to misfolding of proteins and, if they are not refolded or degraded, to cytoplasmic protein aggregates. Protein aggregates are characteristic features of a variety of chronic toxic and degenerative diseases, such as Mallory bodies (MBs) in hepatocytes in alcoholic and non-alcoholic steatohepatitis, neurofibrillary tangles in neurons in Alzheimer's, and Lewy bodies in Parkinson's disease. Using 2D gel electrophoresis and mass spectrometry, we identified p62 as a novel MB component. p62 and cytokeratins (CKs) are major MB constituents; HSP 70, HSP 25, and ubiquitinated CKs are also present. These proteins characterize MBs as a prototype of disease-associated cytoplasmic inclusions generated by stress-induced protein misfolding. As revealed by transfection of tissue culture cells overexpressed p62 did not induce aggregation of regular CK filaments but selectively bound to misfolded and ubiquitinated CKs. The general role of p62 in the cellular response to misfolded proteins was substantiated by detection of p62 in other cytoplasmic inclusions, such as neurofibrillary tangles, Lewy bodies, Rosenthal fibers, intracytoplasmic hyaline bodies in hepatocellular carcinoma, and alpha1-antitrypsin aggregates. The presence of p62 along with other stress proteins and ubiquitin in cytoplasmic inclusions indicates deposition as aggregates as a third line of defense against misfolded proteins in addition to refolding and degradation.

Topics: Adaptor Proteins, Signal Transducing; alpha 1-Antitrypsin Deficiency; Animals; Astrocytoma; Central Nervous System Neoplasms; CHO Cells; Cricetinae; Heat-Shock Proteins; Humans; Inclusion Bodies; Keratins; Liver Diseases; Mice; Neurodegenerative Diseases; Protein Binding; Protein Folding; Proteins; Sequestosome-1 Protein; Stress, Physiological; Ubiquitin

One hundred sixty-four consecutive cases of primary liver carcinoma were evaluated for tumor type, (i.e., hepatocellular carcinoma [HCC], cholangiocarcinoma [CC], and combined hepatocholangiocarcinoma [CHCC]), and for signs of alpha-1-antitrypsin deficiency (AATD) in the surrounding liver tissue. Hepatocellular globular alpha-1-antitrypsin deposits, as detected by a monoclonal antibody to the mutant PiZ alpha-1-antitrypsin (AAT), were seen in 13 cases (7.9%). With regard to tumor type, 4 of 111 HCC cases (3.5%), but 4 of 37 CC cases (10.5%), and even 5 of 16 CHCC cases (30%) were positive for this antitrypsin variant. In all but 1 of 13 cases of alpha-1-antitrypsin deficiency, the carcinoma developed in noncirrhotic liver tissue of elderly people (mean age, 62.9 years). In three patients, a heterozygous state of ATT (PiMZ) could be revealed using isoelectric focusing or direct genetic analysis. We conclude from our findings that CHCC and CC especially might be associated with PiZ alpha-1-antitrypsin deficiency. Primary liver carcinoma might develop even in a heterozygote state of PiZ alpha-1-antitrypsin deficiency without concurrent liver disease. Furthermore, liver cirrhosis is not a precondition for these tumors.

Topics: Adult; Aged; Aged, 80 and over; alpha 1-Antitrypsin; alpha 1-Antitrypsin Deficiency; Female; Humans; Immunohistochemistry; Isoelectric Focusing; Keratins; Liver Neoplasms; Male; Middle Aged

The existence of progenitor (stem) cells in the human liver remains a matter of debate. In rodent models of hepatocarcinogenesis and injury, oval cells proliferate in the periportal regions of the portal tracts and are suggested to derive from a stem cell compartment, because they are capable of differentiating into hepatocytes or biliary epithelial cells. In this study, the rat oval cell marker, OV-6 has been used to investigate the hypothesis that there are stem cells present in fetal and pediatric human liver. The pattern of OV-6 expression was compared with the established adult biliary cell markers human epithelial antigen-125 (HEA-125) and cytokeratin-19 (CK-19). In normal pediatric liver (n = 7), bile ducts and ductules were immunostained with CK-19 and HEA-125, whereas OV-6 staining was consistently negative. In fetal tissue (n = 10), ductal plate cells, primitive bile ducts, and hepatoblasts were stained with CK-19 and HEA-125 although only some of the ductal plate cells and hepatoblasts were OV-6 positive. In biliary atresia (n = 6) and 1, anti-trypsin deficiency (1,AT) (n = 4), CK-19 and HEA-125 immunostained ductular proliferative cells that tended to form finely anastomosing ductules, whereas OV-6 staining was found more on discrete cells confined to portal tract margins. Additionally, in diseased liver, OV-6 was strongly positive in hepatocyte lobules with greatest intensity in the periseptal regions. This widespread hepatocyte OV-6 positivity suggests that the antibody may identify cells of a less differentiated phenotype (transitional hepatocytes) that have replaced the mature cells. Therefore, it is proposed that in human liver, OV-6 is recognizing cells with a progenitor stem cell-like phenotype with the capacity to differentiate into OV-6 positive ductular cells or lobular hepatocytes.

Topics: Adult; alpha 1-Antitrypsin Deficiency; Animals; Antigens, Differentiation; Antigens, Surface; Bile Ducts; Biliary Atresia; Biomarkers; Biomarkers, Tumor; Child; Embryo, Mammalian; Embryonic and Fetal Development; Fetus; Gestational Age; Humans; Keratins; Liver; Liver Diseases; Rats; Stem Cells

The lack of information on the state of fetal liver in PiZZ alpha-1-antitrypsin (AAT) deficiency and a single case report claiming a hypoplasia of interlobular bile ducts in a 20-week PiZZ fetus, instigated this histologic study of the liver in five PiZZ fetuses, 17-20 weeks of gestation and five age-matched controls. We found no difference between the percentage of portal tracts with identifiable bile ducts in the PiZZ (median 22.2%, range 21%-23%) and in the control (median 21.4%, range 20%-24%) on hematoxylin- and eosin-stained sections. Immunostaining with AE1, a monoclonal antibody to cytokeratins restricted to normal bile ducts, doubled the number of recognizable ducts in both PiZZ and control livers. In four PiZZ livers, but in none of the controls, granular deposits of AAT could be detected by specific immunoperoxidase staining. We conclude that an apparent paucity of interlobular bile ducts is normal in the 20-week fetal liver, and our data may be taken as reference for future study dealing with similar material. Except for the cytoplasmic deposition of granules immunoreactive to AAT antiserum, there was no evidence of any developmental anomaly, in particular of the bile duct system in these five PiZZ fetal livers.

Topics: alpha 1-Antitrypsin; alpha 1-Antitrypsin Deficiency; Antibodies, Monoclonal; Bile Ducts; Female; Fetal Diseases; Gestational Age; Humans; Immunoenzyme Techniques; Keratins; Liver; Liver Diseases; Male; Phenotype; Pregnancy