Z. Schaff

Experimental and Human Liver Fibrogenesis

In this work, we provide an overview of our results obtained by studying the role of transforming growth factor beta1 and proteoglycans in liver fibrogenesis. It has been found that transforming growth factor beta1 is one of the most important stimulators of extracellular matrix synthesis in the liver. In chronic liver injury, desmin-positive non-parenchymal liver cells expressed transforming growth factor beta1. The extracellular localization of the growth factor correlated well with types I, III and IV procollagen-alpha, which were detected in the fibrous septa of chronically injured livers. A similar distribution pattern was observed in human specimens. To identify the role of transforming growth factor beta1 in liver extracellular matrix protein synthesis, transforming growth factor beta1-positive transgenic mice were generated. Animals expressing the growth factor in their liver showed spontaneous liver fibrosis. Proteoglycans also participate in fibrogenesis. The majority of liver-specific heparan sulfate proteoglycans, such as syndecan-1 and fibroglycan, are produced by hepatocytes. The extracellular matrix proteoglycans decorin and perlecan are synthesized by non-parenchymal liver cells. The amount of the latter is very low in normal liver, but increases dramatically in liver fibrosis. The effect of regulatory factors on liver proteoglycans seems to be cell type-specific. In contrast to previous observations, elevated amounts of decorin did not inhibit the action of transforming growth factor beta1 in the liver.

Expression of claudin-1, -2, -3, -4, -5 and -7 proteins in benign and malignant canine mammary gland epithelial tumours.

Claudins are tight junction proteins expressed by epithelial and endothelial cells. The present study has evaluated the expression of claudin-1, -2, -3, -4, -5 and -7 in 115 hyperplastic and neoplastic lesions of the canine mammary gland and compared this expression with that of normal mammary epithelium. The lesions studied included lobular hyperplasia (n=15), simple adenoma (n=20), non-infiltrating carcinoma in situ (n=20) and infiltrating carcinomas of histological grades I, II and III (n=20 of each). There was strong expression of claudin-1, -3, -4, -5 and -7 by epithelia within examples of lobular hyperplasia and simple adenoma, and strong expression of claudin-3 and -4 by non-infiltrating carcinomas and all three grades of infiltrating carcinoma. By contrast, there was reduced expression of claudin-5 and -7 by non-infiltrating and infiltrating carcinomas and the expression of these two molecules was inversely correlated with histological grade. Claudin-1 was expressed focally within carcinoma in situ, but this molecule was not detected in any invasive carcinoma. Claudin-2 was weakly expressed within areas of lobular hyperplasia and by simple adenomas, but was not expressed by any carcinoma cells. These results suggest that loss or reduction of expression of claudin-1, -2, -5 and -7 may lead to cellular disorientation, detachment and invasion in canine mammary neoplasia.

Expression pattern of molecular chaperones after liver transplantation in hepatitis C positive recipients. Relation to serum HCV-RNA titers

Abstract Hepatitis C (HCV) is one of the main causes of liver transplantation (OLT). Previously we have reported that high serum C RNA level correlates with the severity of histopathological signs and poor clinical outcome. The core antigen of virus C is known to interfere with chaperones in the hepatocytes, results in an endoplasmic reticulum (ER) stress. In this study HCV positive liver transplanted patients were evaluated, whether there are correlations among chaperone expression, recurrence and viral titer. Patients were enrolled after surviving the first month following OLT. Sera were collected regularly, and biopsies were taken on demand following OLT. The diagnosis of recurrent HCV was proven by Knodell-Ishak scoring. In this case ribavirin+interferon were initiated, and maintained for one year. All chaperones were upregulated in the transplanted liver graft showing recurrent hepatitis C disease. ATF6, GP96, GRP78, CNX and CLR chaperones were upregulated significantly compared to their levels in no...

Human and Experimental Hepatocarcinogenesis

Human liver cancer is increasing worldwide, including in Hungary. The detection of liver tumors in premalignant or early malignant states is essential for successful treatment. MC-29 virus-induced chicken hepatoma and rodent, fish and monkey models for chemical hepatocarcinogenesis were studied and compared to humans. Changes in phenotypic enzyme alterations and in the expression of certain oncogens and growth factors characterize the experimentally induced hepatomas, and might also be characteristic of human premalignant and malignant focal liver lesions. Fish hepatocarcinogenesis is useful for studying compounds in environmental pollution. Increased expression of transforming growth factor á can be observed both in experimental and human liver tumors. Increased tumor incidence was detected in transgene mice containing both transforming growth factor alpha and c-myc genes. Animal models of hepatocarcinogenesis help to understand the development of liver tumors. Methods applied in studies using those models are useful in the study of premalignant and malignant human liver lesions.

Localization of apoptosis proteins and lymphocyte subsets in chronic rejection of human liver allograft

Abstract In chronic liver rejection lymphocyte mediated processes lead to chronic inflammation, necrosis and repair mechanisms. The aim of the present study was to investigate the expression of apoptosis related proteins (FAS/APO-1, FAS-L, Bcl-2, Bax, TNF-α, and INF-γ). ApopTag reaction and immunohistochemistry were performed on liver samples of chronically rejected allografts and compared with normal donor livers. In chronic rejection, apoptosis was detected in pericentral hepatocytes and in the biliary epithelium. Bcl-2 was strongly expressed on lymphocytes around the bile ducts, but not on the biliary epithelium itself. Bax, FAS, TNF-α and INF-γ were present in pericentral areas. T-cells showed up around bile ducts, whereas macrophages around pericentral areas. In pericentral areas apoptosis seems to be fostered through TNF-α and INF-γ and by the lack of Bcl-2. Based on these results both downregulation and upregulation of apoptotic proteins can be observed in chronic liver allograft rejection: FAS is ...

414 IMMUNOHISTOCHEMISTRY FOR AGRIN AND CD34 IN THE DISCRIMINATION OF BENIGN VERSUS MALIGNANT LESIONS OF THE LIVER PARENCHYMA

Background and Aims: Agrin is a recently identified proteoglycan component of vascular and bile duct basement membranes in the liver. The selective deposition of agrin in tumor microvessels versus sinusoidal walls prompted us to investigate whether immunohistochemistry (IHC) for agrin may help to discriminate between benign and malignant hepatocellular lesions. We focused on the differential diagnostic problems often presented by hepatocellular adenomas (HAs) and dysplastic nodules. Our aim was to devise a novel immunohistochemical method that sensitively and selectively detects hepatocellular malignancy. Also, an attempt was made to interpret the observed agrin immunostaining patterns in the context of vascular changes, ductular reaction and parenchymal regeneration. Methods: Eighty-eight formalin-fixed, paraffin-embedded surgical specimens from 68 patients included 24 cirrhotic liver tissues, 10 cases with focal nodular hyperplasia (FNH), 8 large regenerative nodules, 18 lowgrade and 6 high-grade dysplastic nodules (LGDN and HGDN), 6 small HCCs, 21 HCCs, and 29 HAs. Immunoreactions for agrin and, when necessary, for CD34 were evaluated in a semi-quantitative fashion, and the outcome was compared with histological diagnosis. Results: In our method, agrin IHC was complemented with CD34 immunoreaction in ambiguous cases. This combination was found highly informative in the assessment of dignity (sensitivity 92.6%, specificity 91.8%). Whereas most benign lesions (regenerative nodules, LGDN, FNH, HA without cellular atypia) were clearly negative, the strength of immunoreactions and consequent ranking of the sample faithfully reflected the degree and extent of dysplasia in HA and HGDN. Malignant lesions were uniformly positive. Conclusion: Agrin IHC, besides allowing insight into a multitude of nonmalignant pathological processes such as ductular reaction and parenchymal regeneration, is a sensitive indicator of hepatocellular dysplasia and changes in vascular phenotype. Therefore, the admission of agrin to the immunohistochemical panel used in routine liver pathology is worth consideration.