A cytokeratin immunohistochemical study of cholestatic liver disease: evidence that hepatocytes can express 'bile duct-type' cytokeratins

An Updated Review on Nelumbo Nucifera Gaertn: Chemical Composition, Nutritional Value and Pharmacological Activities

Nelumbo nucifera Gaertn is a recognised herbal plant in ancient medical sciences. Each portion of the plant leaf, flower, seed and rhizome is utilised for nutritional and medicinal purposes. The chemical compositions like phenol, alkaloids, glycoside, terpenoids and steroids have been isolated. The plant contains various nutritional values like lipids, proteins, amino acids, minerals, carbohydrates, and fatty acids. Traditional medicine confirms that the phytochemicals of plants give significant benefits to the treatment of various diseases such as leukoderma, smallpox, dysentery, haematemesis, coughing, haemorrhage, metrorrhagia, haematuria, fever, hyperlipidaemia, cholera, hepatopathy and hyperdipsia. To verify the traditional claims, researchers have conducted scientific biological in vivo and in vitro screenings, which have exhibited that the plant keeps various notable pharmacological activities such as anticancer, hepatoprotective, antioxidant, antiviral, hypolipidemic, anti-obesity, antipyretic, hypoglycaemic, antifungal, anti-inflammatory and antibacterial activities. This review, summaries the nutritional composition, chemical constituents and biological activities substantiated by the researchers done in vivo and in vitro.

Multiple Facets of Cellular Homeostasis and Regeneration of the Mammalian Liver

Liver regeneration occurs in response to diverse injuries and is capable of functionally reestablishing the lost parenchyma. This phenomenon has been known since antiquity, encapsulated in the Greek myth where Prometheus was to be punished by Zeus for sharing the gift of fire with humanity by having an eagle eat his liver daily, only to have the liver regrow back, thus ensuring eternal suffering and punishment. Today, this process is actively leveraged clinically during living donor liver transplantation whereby up to a two-thirds hepatectomy (resection or removal of part of the liver) on a donor is used for transplant to a recipient. The donor liver rapidly regenerates to recover the lost parenchymal mass to form a functional tissue. This astonishing regenerative process and unique capacity of the liver are examined in further detail in this review.

Update on Hepatobiliary Plasticity

The liver field has been debating for decades the contribution of the plasticity of the two epithelial compartments in the liver, hepatocytes and biliary epithelial cells (BECs), to derive each other as a repair mechanism. The hepatobiliary plasticity has been first observed in diseased human livers by the presence of biphenotypic cells expressing hepatocyte and BEC markers within bile ducts and regenerative nodules or budding from strings of proliferative BECs in septa. These observations are not surprising as hepatocytes and BECs derive from a common fetal progenitor, the hepatoblast, and, as such, they are expected to compensate for each other's loss in adults. To investigate the cell origin of regenerated cell compartments and associated molecular mechanisms, numerous murine and zebrafish models with ability to trace cell fates have been extensively developed. This short review summarizes the clinical and preclinical studies illustrating the hepatobiliary plasticity and its potential therapeutic application.

Keratin 7 expression in hepatic cholestatic diseases

We evaluated keratin 7 (K7) hepatocellular expression in 92 patients with common types of acute and chronic cholestatic diseases caused by bile duct obstruction/destruction or parenchymal lesions [acute hepatitis (n=20), mixed/pure cholestasis (n=16), primary biliary cholangitis-PBC (n=35), primary sclerosing cholangitis-PSC (n=10), vanishing bile duct syndrome (n=3), complete large bile duct obstruction due to space-occupying lesions (n=8)]. K7 immunohistochemical hepatocellular expression and ductular reaction (DR) were semi-quantitatively assessed. Results were correlated with liver enzyme serum levels, cholestasis type, histological features, hepatocellular Ki67 labelling index (LI) and HepPar1 expression. Hepatocellular K7 expression was detected in 87% (81/92) cases and in all cholestatic disease types with lowest incidence in pure/mixed cholestasis and highest in incomplete bile duct obstruction (iBDO), reaching 100% in PSC. K7-positive hepatocytes had low Ki67 LI (0-5%) retaining HepPar1 expression, irrespective of disease type. PSC cases had high K7 hepatocellular expression even with intact bile ducts, a feature that may aid differential diagnosis of cholestatic syndromes. K7 hepatocellular expression significantly correlated with cholestasis type, bile duct loss and fibrosis stage. It was higher in milder acute cholestatic hepatitis showing inverse correlation with hepatocyte proliferation and serum transaminase levels. In iBDO, younger age independently correlated with high K7 expression, while serum GGT levels showed a nearly significant correlation. Correlation with DR findings implied that K7-positive hepatocytes may result through metaplasia. In conclusion, K7 hepatocellular expression is a sensitive though non-specific marker of cholestasis. It may represent a cytoprotective reaction of resting hepatocytes in cholestasis of longer duration especially in younger patients.

Chronic cholestasis detection by a novel tool: automated analysis of cytokeratin 7-stained liver specimens

Background

The objective was to build a novel method for automated image analysis to locate and quantify the number of cytokeratin 7 (K7)-positive hepatocytes reflecting cholestasis by applying deep learning neural networks (AI model) in a cohort of 210 liver specimens. We aimed to study the correlation between the AI model’s results and disease progression. The cohort of liver biopsies which served as a model of chronic cholestatic liver disease comprised of patients diagnosed with primary sclerosing cholangitis (PSC).

Methods

In a cohort of patients with PSC identified from the PSC registry of the University Hospital of Helsinki, their K7-stained liver biopsy specimens were scored by a pathologist (human K7 score) and then digitally analyzed for K7-positive hepatocytes (K7%area). The digital analysis was by a K7-AI model created in an Aiforia Technologies cloud platform. For validation, values were human K7 score, stage of disease (Metavir and Nakunuma fibrosis score), and plasma liver enzymes indicating clinical cholestasis, all subjected to correlation analysis.

Results

The K7-AI model results (K7%area) correlated with the human K7 score (0.896; p < 2.2e^− 16). In addition, K7%area correlated with stage of PSC (Metavir 0.446; p < 1.849e^− 10 and Nakanuma 0.424; p < 4.23e^− 10) and with plasma alkaline phosphatase (P-ALP) levels (0.369, p < 5.749e^− 5).

Conclusions

The accuracy of the AI-based analysis was comparable to that of the human K7 score. Automated quantitative image analysis correlated with stage of PSC and with P-ALP. Based on the results of the K7-AI model, we recommend K7 staining in the assessment of cholestasis by means of automated methods that provide fast (9.75 s/specimen) quantitative analysis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01102-6.

If It Looks Like a Duct and Acts Like a Duct: On the Role of Reprogrammed Hepatocytes in Cholangiopathies

Cholangiopathies are chronic, progressive diseases of the biliary tree, and can be either acquired or genetic. The primary target is the cholangiocyte (CC), the cell type lining the bile duct that is responsible for bile modification and transport. Despite advances in our understanding and diagnosis of these diseases in recent years, there are no proven therapeutic treatments for the majority of the cholangiopathies, and liver transplantation is the only life-extending treatment option for patients with end-stage cholestatic liver disease. One potential therapeutic strategy is to facilitate endogenous repair of the biliary system, which may alleviate intrahepatic cholestasis caused by these diseases. During biliary injury, hepatocytes (HC) are known to alter their phenotype and acquire CC-like features, a process known as cellular reprogramming. This brief review discusses the potential ways in which reprogrammed HC may contribute to biliary repair, thereby restoring bile flow and reducing the severity of cholangiopathies. Some of these include modifying bile to reduce toxicity, serving as a source of de novo CC to repair the biliary epithelium, or creating new channels to facilitate bile flow.

Cell Plasticity in Liver Regeneration

The liver, whose major functional cell type is the hepatocyte, is a peculiar organ with remarkable regenerative capacity. The widely held notion that hepatic progenitor cells contribute to injury-induced liver regeneration has long been debated. However, multiple lines of evidence suggest that the plasticity of differentiated cells is a major mechanism for the cell source in injury-induced liver regeneration. Investigating cell plasticity could potentially expand our understanding of liver physiology and facilitate the development of new therapies for liver diseases. In this review, we summarize the cell sources for hepatocyte regeneration and the clinical relevance of cell plasticity for human liver diseases. We focus on mechanistic insights on the injury-induced cell plasticity of hepatocytes and biliary epithelial cells and discuss future directions for investigation. Specifically, we propose the notion of 'reprogramming competence' to explain the plasticity of differentiated hepatocytes.

Influence of Progenitor-Derived Regeneration Markers on Hepatitis C Virus-Related Cirrhosis Outcome (ANRS CO12 CirVir Cohort)

Progenitor-derived regeneration gives rise to the aberrant expression of biliary markers such as cytokeratin 7 (K7) and epithelial cell adhesion molecule (EpCAM) in hepatocytes. We aimed to describe the expression of these molecules in patients with compensated hepatitis C virus (HCV)-related cirrhosis and to investigate its potential influence on cirrhosis complications. Among patients with Child-Pugh A uncomplicated HCV-related cirrhosis enrolled in the prospective ANRS CO12 CirVir cohort, we selected individuals with a liver biopsy collected within 2 years before inclusion in the study. K7 and EpCAM immunostaining identified intermediate hepatobiliary cells. The influence of biliary marker expres-sion in hepatocytes on decompensation events and the occurrence of hepatocellular carcinoma (HCC) was studied using a multivariate Cox proportional hazards regression model. Among the 337 patients eligible for the study (men, 67%; median age, 52 years), 198 (58.8%) had biopsies with K7-positive hepatocytes including extensive staining in 40 (11.9%) and 203 had EpCAM-positive hepatocytes (60.6%). During follow-up (median, 54.2 months), 47 patients (14%) experienced a decompensation event, and HCC was diagnosed in 37 patients (11%). Extensive K7 staining was independently associated with the occurrence of a decompensation event (hazard ratio [HR], 3.00; 95% confidence interval [CI], 1.30-6.89; P = 0.010). EpCAM expression was independently associated with HCC occurrence (HR, 2.37; 95% CI, 1.07-5.23; P =0.033) along with age and a low prothrombin ratio.

CONCLUSION

Progenitor-derived regeneration depicted by K7 and EpCAM immunostaining of hepatocytes in liver biopsies of patients with compensated HCV-related cirrhosis marks a cirrhosis stage more prone to develop complications. (HEPATOLOGY 2018; 68:1534-1548).

Variant syndromes of primary biliary cholangitis

Patients with primary biliary cholangitis (PBC) can show biochemical, serological and/or histological features of autoimmune hepatitis (AIH). The term 'AIH-PBC overlap syndrome' has been used frequently for these cases and implies the coexistence of two separate diseases. However, the boundaries between 'classical' PBC, PBC with features of AIH and 'classical' AIH are difficult to define, and therefore the term 'variant syndrome' should be preferred. A variant syndrome must primarily be assumed in PBC patients showing pronounced hepatitic activity, either expressed by elevated transaminases and raised levels of serum IgG/gammaglobulins or more specifically by liver biopsy showing a modified hepatitis activity index (mHAI) score of >4/18. The presence of AIH-specific autoantibodies also supports the diagnosis of a variant syndrome. The diagnosis must not be missed because individually adapted immunosuppressive treatment, analogous to AIH therapy, appears to have an important beneficial impact on the prognosis and should therefore be offered to these patients.

De novo formation of the biliary system by TGFβ-mediated hepatocyte transdifferentiation

Transdifferentiation is a complete and stable change in cell identity that serves as an alternative to stem-cell-mediated organ regeneration. In adult mammals, findings of transdifferentiation have been limited to the replenishment of cells lost from preexisting structures, in the presence of a fully developed scaffold and niche¹. Here we show that transdifferentiation of hepatocytes in the mouse liver can build a structure that failed to form in development-the biliary system in a mouse model that mimics the hepatic phenotype of human Alagille syndrome (ALGS)². In these mice, hepatocytes convert into mature cholangiocytes and form bile ducts that are effective in draining bile and persist after the cholestatic liver injury is reversed, consistent with transdifferentiation. These findings redefine hepatocyte plasticity, which appeared to be limited to metaplasia, that is, incomplete and transient biliary differentiation as an adaptation to cell injury, based on previous studies in mice with a fully developed biliary system^3-6. In contrast to bile duct development^7-9, we show that de novo bile duct formation by hepatocyte transdifferentiation is independent of NOTCH signalling. We identify TGFβ signalling as the driver of this compensatory mechanism and show that it is active in some patients with ALGS. Furthermore, we show that TGFβ signalling can be targeted to enhance the formation of the biliary system from hepatocytes, and that the transdifferentiation-inducing signals and remodelling capacity of the bile-duct-deficient liver can be harnessed with transplanted hepatocytes. Our results define the regenerative potential of mammalian transdifferentiation and reveal opportunities for the treatment of ALGS and other cholestatic liver diseases.

Autoimmune hepatitis: review of histologic features included in the simplified criteria proposed by the international autoimmune hepatitis group and proposal for new histologic criteria

Simplified criteria for diagnosis of autoimmune hepatitis are based on autoantibodies, serum immunoglobulin G, histologic features, and negative viral serology. A score of 6 points is necessary for the designation of probable autoimmune hepatitis and 7 points or more for definite autoimmune hepatitis. The presence of three histologic features is required for categorizing a case as typical (2 points): interface hepatitis with portal lymphocytic/lymphoplasmacytic cells extending into lobule, emperipolesis, and rosettes. In the absence of all three features, a chronic hepatitis picture is considered compatible with autoimmune hepatitis (1 point). This study examines the validity of these histologic features for the diagnosis of autoimmune hepatitis. Clinical data and liver biopsies were reviewed for 88 autoimmune hepatitis, 20 primary biliary cholangitis, and 13 non-autoimmune acute hepatitis cases. Interface/lobular activity, number of plasma cells, copper/CK7 stains, and presence/absence of biliary features were assessed in autoimmune hepatitis and primary biliary cholangitis cases. The simplified criteria score was calculated. Modified histologic criteria were formulated on the basis of interface/lobular activity, number of plasma cells, and presence/absence of biliary features. Using the proposed histologic features, histologic score of 2 increased from 8 to 77%, while total simplified score of >6 increased from 69 to 86%. There was no increase in total simplified score for primary biliary cholangitis or non-autoimmune acute hepatitis. Rosettes and emperipolesis are difficult to interpret, and lack sensitivity and sensitivity for autoimmune hepatitis diagnosis. The current histologic criteria used in the current simplified score lead to underscoring of autoimmune hepatitis cases. The modified histologic criteria based on the inflammatory activity, extent of plasma cells, and results of copper/CK7 staining increased the histologic score in autoimmune hepatitis and led to a probable/definite diagnosis of autoimmune hepatitis in 17% of cases that would have otherwise been classified as non- autoimmune hepatitis by simplified score.

Surgical Pathologic Diagnosis

Surgical pathology results can play a crucial role in the management of immunocompromised patients. Here we highlight factors that differ between immunocompromised and immunocompetent hosts, such as variation in inflammatory response. Conditions that are covered include drug reactions, disease within solid organ allografts, immune reconstitution inflammatory syndrome, specific immunodeficiency syndromes, neoplasms related to viral infections, and viral, bacterial, fungal, and parasitic infections. Special techniques including immunohistochemistry, in situ hybridization and molecular detection of pathogen nucleic acid from formalin-fixed, paraffin-embedded tissue are discussed.

Primary-like human hepatocytes genetically engineered to obtain proliferation competence display hepatic differentiation characteristics in monolayer and organotypical spheroid cultures

Primary human hepatocytes are in great demand during drug development and in hepatology. However, both scarcity of tissue supply and donor variability of primary cells create a need for the development of alternative hepatocyte systems. By using a lentivirus vector system to transfer coding sequences of Upcyte® proliferation genes, we generated non-transformed stable hepatocyte cultures from human liver tissue samples. Here, we show data on newly generated proliferation-competent HepaFH3 cells investigated as conventional two-dimensional monolayer and as organotypical three-dimensional (3D) spheroid culture. In monolayer culture, HepaFH3 cells show typical cobblestone-like hepatocyte morphology and anchorage-dependent growth for at least 20 passages. Immunofluorescence staining revealed that characteristic hepatocyte marker proteins cytokeratin 8, human serum albumin, and cytochrome P450 (CYP) 3A4 were expressed. Quantitative real-time PCR analyses showed that expression levels of analyzed phase I CYP enzymes were at similar levels compared to those of cultured primary human hepatocytes and considerably higher than in the liver carcinoma cell line HepG2. Additionally, transcripts for phase II liver enzymes and transporter proteins OATP-C, MRP2, Oct1, and BSEP were present in HepaFH3. The cells produced urea and converted model compounds such as testosterone, diclofenac, and 7-OH-coumarin into phases I and II metabolites. Interestingly, phases I and II enzymes were expressed at about the same levels in convenient monolayer cultures and complex 3D spheroids. In conclusion, HepaFH3 cells and related primary-like hepatocyte lines seem to be promising tools for in vitro research of liver functions and as test system in drug development and toxicology analysis.

Cytokeratin 7/19 expression in N-diethylnitrosamine-induced mouse hepatocellular lesions: implications for histogenesis

Hepatocellular carcinoma (HCC) is a common malignancy with poor clinical outcome, whose histogenesis is the subject of intense debate. Specifically, expression of cytokeratins (CKs) 7 and 19, associated with aggressive biological behaviour, is proposed to reflect a possible progenitor cell origin or tumour dedifferentiation towards a primitive phenotype. This work addresses that problem by studying CKs 7 and 19 expression in N-diethylnitrosamine (DEN)-induced mouse HCCs. ICR mice were divided into six DEN-exposed and six matched control groups. Samples were taken from each group at consecutive time points. Hyperplastic foci (13 lesions) occurred at 29-40 weeks (groups 8, 10 and 12) with diffuse dysplastic areas (19 lesions) and with one hepatocellular adenoma (HCA) (at 29 weeks). HCCs (4 lesions) were observed 40 weeks after the first DEN administration (group 12). CKs 7 and 19 showed identical expression patterns and located to large, mature hepatocytes, isolated or in small clusters. Hyperplastic foci and the single HCA were consistently negative for both markers, while dysplastic areas and HCCs were positive. These results support the hypothesis that CKs 7 and 19 expression in hepatocellular malignancies results from a dedifferentiation process rather than from a possible progenitor cell origin.

Frequency of hepatocellular fibrillar inclusions in European flounder (Platichthys flesus) from the Douro River estuary, Portugal

Liver lesions in wild fish have been associated with xenobiotic exposure. Facing reports of pollution in the Douro River estuary (north of Portugal), we have been making field surveys using fishes and targeting histopathological biomarkers of exposure and effect. Herein, we intended to better characterize and report the rate of one poorly understood lesion-hepatocellular fibrillar inclusions (HFI)-found in European flounder (Platichthys flesus). With this report, we aimed to establish sound baseline data that could be viewed as a starting point for future biomonitoring, while offering the world's second only pool of field data on such a liver toxicopathic lesion, which could be compared with data available from the UK estuaries. Sampling was done in the Douro River estuary over 1 year. A total of 72 animals were fished with nets, in spring-summer (SS) and autumn-winter (AW) campaigns. Livers were processed for histopathology and both routine and special staining procedures (alcian blue, periodic acid Schiff (PAS), tetrazonium coupling reaction). Immunohistochemistry targeted AE1/AE3 (pan cytokeratins). The severity of the HFI extent was graded using a system with four levels, varying from 0 (absence of HFI) to 3 (high relative density of cells with HFI). Cells (isolated/groups) with HFI appeared in 35 % or more of the fish, in the total samples of each season, and over 40 % in more homogeneous sub-samples. There were no significant differences when comparing samples versus sub-samples or SS versus AW. When merging the data sets from the two seasons, the frequency of fish with HFI was ≈36 % for the total sample and ≈49 % for the sub-sample. The extreme group (biggest and smallest fish) revealed a HFI frequency of only 16 %, which differed significantly from the total and sub-sampled groups. Immunostaining and PAS were negative for the HFI, and alcian blue could, at times, faintly stain the inclusions. These were positive with the tetrazonium reaction. We showed the presence of HFI in European flounder from the Douro River estuary, proving that they are essentially protein in nature, that no seasonal changes existed in the HFI frequency, and that it was rarer in the smallest and biggest fish groups. Within the ranges of weight/size of our total sample, we estimate that the frequency of HFI in the local flounder is ≈35 %. That rate stands as a baseline value for future assessments, namely for biomonitoring purposes targeting correlations with the estuary pollution status.

Histopathologic distinction between fibrosing cholestatic hepatitis C and biliary obstruction

The histopathologic distinction between posttransplantation fibrosing cholestatic hepatitis C (FCH-C) and biliary obstruction (BO) is challenging. We sought to identify histopathologic features that could be useful in the differential diagnosis between these 2 entities. A total of 38 cases of hepatitis C virus (HCV)-negative, cholangiography-proven BO (including 16 posttransplant and 22 nontransplant patients) and 13 patients with posttransplantation FCH-C were included. FCH-C patients were characterized by cholestatic disease, high HCV viral load, no evidence of biliary tract obstruction on imaging, and typical histopathologic findings (≥3 of the following: 1, prominent ductular reaction; 2, hepatocyte swelling with lobular disarray; 3, periportal sinusoidal fibrosis, and 4, cholestasis). Biopsies were evaluated with hematoxylin and eosin, Masson trichrome, Victoria blue, and rhodanine stains. Cytokeratin 7 (CK7) immunohistochemistry was used to assess for the presence of CK7+ intermediate hepatobiliary cells. We found that portal edema (63.1% vs. 7.6%; P<0.0001), bile duct dilatation (26.3% vs. 0%; P=0.0003), acute cholangitis (15.7% vs. 0%; P=0.008), bile infarcts (10.5% vs. 0%; P=0.03), periductal fibrosis (23.6% vs. 0%; P=0.0007), and periportal copper deposition (60.5% vs. 15.3%; P=0.0006) are significantly more common in BO, whereas hepatocellular swelling with lobular disarray (84.6% vs. 5.2%; P<0.0001) and periportal sinusoidal fibrosis (34.2% vs. 100%; P<0.0001) are seen more frequently in FCH-C. Furthermore, marked ductular reaction with rare or absent CK7+ intermediate cells is highly suggestive of FCH-C in this context (73.6% vs. 7.6%; P<0.0001). In summary, this study offers a comprehensive characterization of the histologic features discriminating FCH-C from BO.

Transdifferentiation of mature hepatocytes into bile duct/ductule cells within a collagen gel matrix

The phenotype of hepatocytes has been thought to be fixed once they are terminally differentiated. However, we and other investigators have demonstrated that mature hepatocytes can transform into bile duct/ductule cells in various experimental conditions in vitro. Since the normal bile duct system is almost invariably surrounded by dense periportal collagenous matrices, we placed isolated hepatocytes in a collagen-rich environment to address whether mature hepatocytes can transform into ductular cells. Here, we describe in detail our three-dimensional collagen culture method for the induction of transdifferentiation of mature rat hepatocytes into bile ductular cells. Our in vitro system might be useful for the elucidation of the mechanisms of the aberrant differentiation of hepatocytes in the diseased liver.

Morphometrical and immunohistochemical study of intrahepatic bile ducts in biliary atresia

BACKGROUND

Extrahepatic biliary atresia results from a progressive destruction of the bile ducts by an inflammatory fibrosing process which leads ultimately to cirrhosis of biliary type. The etiology of the disorder remains unknown. The histological features include cholestasis, ductular proliferation, eventual loss of intrahepatic bile ducts, and ducts with primitive embryonic shape (ductal plate malformation).

PURPOSE

To examine the morphological changes of the biliary intrahepatic ducts, we aimed at investigating the cell proliferation and the diameter of the interlobular bile ducts in extrahepatic biliary atresia, and in normal liver children.

METHODS

Liver samples from 35 patients with biliary atresia and 10 from control normal children were used. Immunoexpression of cytokeratin 19 was evaluated and a double-staining procedure was performed with cytokeratin 8/proliferating cell nuclear antigen. The stereological measurements of the intrahepatic bile ducts diameter were evaluated by a computerized system of image analysis.

RESULTS

The patterns of intrahepatic cholangiopathy in biliary atresia were obstructive features (42.86%), paucity of intrahepatic bile ducts (20%), ductal plate malformation (28.57%), and ductal plate malformation associated with paucity of intrahepatic bile ducts (8.57%). The average external diameter of interlobular bile ducts in biliary atresia was smaller than that of the control infant livers. Among the four patterns of biliary atresia cholangiopathies, those associated with ductopenia showed the smallest bile duct diameter. There was a negative correlation between the bile duct to portal space ratio and the age of the child at the time of Kasai portoenterostomy. Only in biliary atresia are the bile duct cells stained with proliferating cell nuclear antigen.

CONCLUSION

(i) In biliary atresia, both ductular metaplasia and ductular proliferation were observed; (ii) biliary atresia associated with ductopenia showed narrowing of interlobular ducts, probably as a consequence of degeneration with atrophy and fibrosis.

Ductal plates in hepatic ductular reactions. Hypothesis and implications. III. Implications for liver pathology

This article discusses on the basis of the ductal plate hypothesis the implication of the concept for several liver abnormalities. The occurrence of ductal plates (DP) during liver growth in childhood would explain the paraportal and parenchymal localizations of von Meyenburg complexes in postnatally developed parts of the liver, and their higher incidence in adulthood versus childhood. It partly clarifies the lack of postnatal intrahepatic bile duct development in Alagille syndrome and the reduced number of portal tracts in this disease. Ductular reactions (DRs) in DP configuration are the predominant type of progenitor cell reaction in fulminant necro-inflammatory liver disease, when lack of sufficient parenchymal regeneration results in liver failure. The concept of dissecting DRs explains the micronodular pattern of advanced biliary and alcoholic cirrhosis. The concept explains the DP patterns of bile ducts in several cases of biliary atresia, with implications for diagnosis and prognosis. The hypothesis also has an impact on concepts about stem/progenitor cells and their niche.

Aberrant expression of cytokeratin 7 in perivenular hepatocytes correlates with a cholestatic chemistry profile in patients with heart failure

A cholestatic liver chemistry profile (elevations in alkaline phosphatase and bilirubin) is commonly encountered in patients with hepatic venous outflow obstruction due to right heart failure. Liver biopsies from these patients demonstrate varying degrees of sinusoidal dilatation, red blood cell extravasation and sinusoidal congestion. Recently, a bile ductular reaction mimicking biliary tract disease has been identified in ∼ 50% of patients with venous outflow obstruction possibly explaining the cholestatic profile encountered in these patients. In this study, we evaluated the liver biopsies from 22 patients with heart failure. Marked sinusoidal dilatation involving zones 2 and 3 was observed in 15 patients. Similar to a previous study, 7 of 22 patients had histologic evidence of a mild ductular reaction. Cytokeratin 7 immunohistochemistry revealed a mild ductular reaction in an additional two cases. Strikingly, CK7 was aberrantly expressed in perivenular hepatocytes in 20 of 22 cases. Perivenular CK7 immunoreactivity was focal in most cases; however, in five cases it was quite extensive and extended into zone 2. There was no significant association between marked sinusoidal dilatation and extensive perivenular CK7 positivity. Extensive perivenular CK7 positivity was significantly associated with both elevated bilirubin, as well as the presence of fibrosis. However, a ductular reaction was not associated with a cholestatic liver chemistry profile.

Disparate cellular basis of improved liver repair in beta-catenin-overexpressing mice after long-term exposure to 3,5-diethoxycarbonyl-1,4-dihydrocollidine

Administration of a hepatotoxic diet containing 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) induces biliary damage followed by hepatocyte injury, which is repaired through atypical ductular proliferation and oval cells and their subsequent differentiation to bile duct cells and hepatocytes. In this study, we examine whether excess β-catenin in transgenic (TG) mice would provide any reparative advantage in response to DDC. No differences in appearance or numbers of total A6-positive oval cells were observed after DDC administration. However, an increase in A6-positive "atypical hepatocytes" in the TG livers was observed after 14 and 28 days, coinciding with an increase in proliferating cell nuclear antigen-positive hepatocytes. Intriguingly, after chronic DDC administration for 150 days, a further increase in atypical hepatocytes was evident in TG mice, with higher numbers of proliferating cell nuclear antigen-positive hepatocytes exhibiting cytoplasmic/nuclear β-catenin and α-fetoprotein but not CK19, HNF1β, or Trop-2. Coincidently, we observed an improvement in intrahepatic cholestasis as seen by decreases in both serum bilirubin and alkaline phosphatase levels in TG mice, indicating an overall improvement in hepatic repair. TG mice exposed to DDC for 4 weeks followed by 2 days of normal chow showed decreases in alkaline phosphatase, atypical ductular proliferation, and periportal inflammation compared with wild-type animals, verifying improved biliary repair in TG livers. Thus, we report a potential role of β-catenin in liver repair, especially in enhancing the resolution of intrahepatic cholestasis after DDC injury.

Fibrolamellar Hepatocellular Carcinoma: An Immunohistochemical Comparison With Conventional Hepatocellular Carcinoma

The fibrolamellar variant of hepatocellular carcinoma (FLC) differs from conventional hepatocellular carcinoma (HCC) in some clinical and pathological features. The authors investigated possible differences in reactivity between FLCs and HCCs using glypican-3 (GPC3), an oncofetal protein, and survivin, an antiapoptotic protein. They also compared staining of FLC and HCC with antibodies to cytokeratins 7 (CK7) and 19 (CK19) and CD34. GPC3 was significantly more often and more strongly expressed in HCCs (72%) than in FLCs (17%). Survivin nuclear translocation in tumor cells did not differ between HCCs (10%) and FLCs (9%). There was more abundant expression of CK7 in FLCs (92%) than in HCCs (33%), whereas CK19 was more often found in HCCs (20%) than in FLCs (5%). All tumors had CD34-positive sinusoids. This study shows that FLCs and HCCs differ in the expression of GPC3, CK7, and CK19 and that there is a lack of difference as regards survivin and CD34.

The amazing universe of hepatic microstructure

An informal review is presented by the author of his 50 years of involvement in practice and research in hepatopathology. Some background for the author's attitude and meandering pathway into his professional career serves as introduction to a short discussion of the main topics of his interest and expertise. Histogenesis of liver cancer was the theme of early work for a Ph.D. thesis, the results of which were lost into oblivion due to local rules and circumstances, but were rescued three decades later. His conclusions about the cells of origin of liver cancer remain concordant with the newer concepts in the field after nearly half a century. Studies in the field of chronic hepatitis became a long saga, involving the first classification of this syndrome by "the Gnomes" in 1968, histochemical investigations of viral antigens, lymphocyte subsets and adhesion molecules, and a quarter century later, the creation of a new classification presently in use. Cholestasis was a broadening field in diagnostic entities and involved the study of liver lesions, comprising pathways of bile regurgitation (including reversed secretory polarity of hepatocytes) and so-called ductular reaction. The latter topic has a high importance for the various roles it plays in modulating liver tissue of chronic cholestasis into biliary cirrhosis, and as the territory of hepatic progenitor cells, crucial for liver regeneration in adverse conditions and in development of liver cancer. Study of the embryology of intrahepatic bile ducts helped to clarify the strange appearance of the ducts in "ductal plate configuration" in several conditions, including some forms of biliary atresia with poor prognosis and all varieties of fibrocystic bile duct diseases with "ductal plate malformation" as the basic morphologic lesion.

Secondary sclerosing cholangitis after intensive care unit treatment: clues to the histopathological differential diagnosis

Secondary sclerosing cholangitis (SSC) is a chronic cholestatic disorder caused by mechanical, infectious, toxic, or ischemic factors. A new variant of SSC occurring after long-term treatment in intensive care units (ICU) has been recently described and characterized from the clinical point of view. The aim of this study was the histomorphological characterization of ICU-treatment-related SSC (ICU-SSC) and the definition of histological changes occurring over time based on the morphological findings. Liver biopsies of ten patients affected by ICU-SSC obtained at different time points (1.5 to 57 months) after the initial injury were analyzed. The main morphological alterations included degenerative changes of portal bile ducts, portal edema, inflammation, and fibrosis as well as biliary interface activity and bilirubinostasis. Perivenular necroses and bile infarcts were found in eight and six patients, respectively. Bile duct loss was not observed. No correlation between morphological features of biopsies and liver chemistry tests or outcome could be established. Based on the morphological observation, a possible disease-progression model starting with an initial damage of portal bile ducts (primary insult) with associated portal/periportal changes (inflammation, ductular reaction) and resulting in secondary parenchymal changes is proposed.

Interlobular bile duct loss in pediatric cholestatic disease is associated with aberrant cytokeratin 7 expression by hepatocytes

The objective of this study was to determine whether aberrant hepatic expression of cytokeratin 7 (CK7) and/or other putative stem cell markers is seen in pediatric cholestatic diseases. Eighteen liver biopsies and 14 liver explants from pediatric patients with extrahepatic biliary atresia (EHBA), Alagille syndrome (AGS), primary sclerosing cholangitis (PSC), inborn errors of bile acid synthesis, and progressive familial intrahepatic cholestasis (PFIC) were examined along with 5 histologically normal control liver biopsies. Immumohistochemical stains (CK7, CD56, and OV6) were performed on paraffin-embedded tissue. Staining of interlobular bile ducts (ILBD), proliferating bile ductules, and hepatocytes was scored using a semiquantitative scale. There were significant differences in CK7 staining of hepatocytes among the cholestatic diseases (P < 0.006). All cases with AGS showed CK7 hepatocyte staining, while EHBA and PSC had variable hepatocyte staining. Patients with PFIC had prominent CK7 hepatocyte staining, while those with inborn errors of bile acid synthesis had little. Control biopsies showed rare hepatocyte staining. Analysis based on the presence or absence of ILBD revealed significantly more CK7 hepatocyte staining in cases with loss of ILBD (P < 0.001). CD56 staining of hepatocytes was also present more frequently in cases with absent or reduced ILBD. Regardless of underlying disease, loss of ILBD is a major determinant of aberrant expression of CK7 by hepatocytes. Aberrant CK7 expression may reflect a metaplastic change to a "stem cell" phenotype induced by loss of contact with the more distal biliary tree.

An in vivo look at vertebrate liver architecture: three-dimensional reconstructions from medaka (Oryzias latipes)

Understanding three-dimensional (3D) hepatobiliary architecture is fundamental to elucidating structure/function relationships relevant to hepatobiliary metabolism, transport, and toxicity. To date, factual information on vertebrate liver architecture in 3 dimensions has remained limited. Applying noninvasive in vivo imaging to a living small fish animal model we elucidated, and present here, the 3D architecture of this lower vertebrate liver. Our investigations show that hepatobiliary architecture in medaka is based on a polyhedral (hexagonal) structural motif, that the intrahepatic biliary system is an interconnected network of canaliculi and bile-preductules, and that parenchymal architecture in this lower vertebrate is more related to that of the mammalian liver than previously believed. The in vivo findings presented advance our comparative 3D understanding of vertebrate liver structure/function, help clarify previous discrepancies among vertebrate liver conceptual models, and pose interesting questions regarding the "functional unit" of the vertebrate liver.

Plasticity of hepatic cell differentiation: bipotential adult mouse liver clonal cell lines competent to differentiate in vitro and in vivo

In fetal liver, bipotential hepatoblasts differentiate into hepatocytes and bile duct cells (cholangiocytes). The persistence of such progenitor cells in adult mouse liver is still debated. In damaged liver of adult murine animals, when hepatocyte proliferation is compromised, bipotential oval cells emerge, probably from bile ducts, proliferate, and differentiate to regenerate the liver. However, treatment to elicit oval cell proliferation is not necessary to obtain bipotential stem cells from adult mouse liver. Here, we have isolated bipotential clonal cell lines from healthy liver of 8-10-week-old C57BL/6 mice. Primary cultures established from hepatocyte-enriched suspensions were characterized by time-lapse image acquisition, immunocytology, and RNA transcript analysis. Although hepatocytes dedifferentiated with loss of apical polarity and other hepatocyte markers, they rapidly activated expression of bile duct/oval cell markers. Reversibility of these processes was achieved in part by culture under dilute Matrigel or by aging of confluent cultures. Cell lines were obtained at high frequency from mass cultures, from isolated colonies, and by primary cloning of the hepatocyte-enriched suspension. Cells of the clonal cell lines do not grow in soft agar and are nontumorigenic, and they express cytokeratin 19, A6 antigen, and alpha6 integrin, as well as a large panel of hepatocyte functions. Furthermore, they can participate in liver regeneration in albumin-urokinase-type plasminogen activator/severe combined immune-deficient mice, where they differentiate in clusters of hepatocytes and occasionally bile ducts. These results demonstrate the existence, in normal adult mouse liver, of a significant pool of clonogenic cells that are (or can become) bipotential.

Serum CYFRA 21-1 level reflects hepatocellular carcinoma metastasis: study in nude mice model and clinical patients

Our previous proteomics study on human hepatocellular carcinoma (HCC) cell strains revealed that cytokeratin 19 (CK19) was expressed in cells with high metastasis potential; we further studied serum CK19 fragment CYFRA 21-1 level in HCC patients and nude mice model of HCC metastasis. HCC cell line HCCLM3 was injected subcutaneously into 30 nude mice which were then randomized into 6 groups of 5 mice each. The murine serum CYFRA 21-1 and pulmonary metastases were determined 2, 3, 4, 5, 6, and 7 weeks after injection. Serum CYFRA 21-1 levels of 101 normal controls and 108 HCC patients were also determined. In nude mice model, CYFRA 21-1 level increased significantly when pulmonary metastases occurred. Among 108 HCC patients, 24 (22.2%) had increased serum CYFRA 21-1 level. The presence of portal vein tumor emboli was significantly higher in CYFRA 21-1 increased cases (33.3%, 6/24) than in CYFRA 21-1 normal cases (6.0%, 5/84) (x2=7.403, P < 0.01). In addition, the percentage of TNM stage III/IV tumor was significantly higher in CYFRA 21-1 increased patients (54.2%, 13/24) than in CYFRA 21-1 normal cases (21.4%, 18/84) (x2=9.776, P < 0.005). These results suggest that CK19 may play an important role in HCC metastasis.

Diagnosis of focal nodular hyperplasia of the liver by needle biopsy

Focal nodular hyperplasia (FNH) of the liver can be a difficult diagnosis to establish in limited diagnostic samples such as a needle-core tissue biopsy, especially for pathologists with limited experience with the lesion. To characterize the features that can be used to make the diagnosis, we reviewed and analyzed the clinicopathologic features of 100 consecutive cases submitted for consultation in which we were confident of the diagnosis of FNH in needle biopsy material. A diagnosis of FNH was correctly made by the contributing pathologist in 24 of the 100 referred cases. Most of the patients (81%) were women of childbearing age with a mean age of 36.75 +/- 9.82 years. Most of the patients (70%) were asymptomatic at diagnosis. The most consistent diagnostic histological feature of FNH in needle biopsy was the presence of ductular reaction with varied intensity at the junction of the fibrous septa with the hepatocellular component, which was present in all 100 cases. Thick abnormal arteries were seen in all but 2 cases (n = 98). Features of chronic cholestasis with cholate stasis and accumulation of copper (demonstrable by the rhodanine stain) and copper-binding protein (demonstrable with the Victoria blue stain) were nearly as common (n = 94). A confident diagnosis of FNH can be made with a needle biopsy, especially if the biopsy is known to come from a mass, and the lesion contains characteristic fibrosis with ductules at the interface between hepatocytes and the fibrous region, prominent arteries, and benign hepatocytes with features of chronic cholestasis.

Peripheral Bile Duct Paucity and Cholestasis in the Liver of a Patient With Alagille Syndrome

Alagille syndrome (AGS) is a developmental, multiorgan disease caused by mutations of the Jagged1 gene. The liver is one of the major organs affected in AGS, and the hallmark of liver pathology in AGS is an age-related increase in the proportion of portal tracts that have no bile duct, but without evidence of prominent bile duct damage. The pathogenesis of this bile duct paucity is currently not well understood. (Immuno)histochemical and molecular analyses were performed on several liver biopsies that were taken during macroscopic examination of the explant liver of a 17-year-old AGS patient. The liver periphery was macroscopically pale and was microscopically characterized by complete absence of bile ducts and presence of severe cholestasis, but there was no ductular reaction. Conversely, the central, hilar portion contained normally developed bile ducts showing no or minimal damage and cholestasis. A missense mutation in the Jagged1 gene was present in both parts of the liver, indicating that mosaicism did not cause this peculiar picture. There was also a hypertrophy of the hepatic arterial branches in the liver periphery. Together with previous indirect findings, the current study of the explant liver of an AGS patient strongly suggests that a lack of branching and elongation of bile ducts during postnatal liver growth is the mechanism by which peripheral bile duct paucity and cholestasis develops in AGS. Our findings also suggest that anomalies of the intrahepatic arterial branches may be part of AGS in some patients.

Perfusion of medium with supplemented growth factors changes metabolic activities and cell morphology of hepatocyte-nonparenchymal cell coculture

To develop a feasible perfusion-type bioartificial liver device, perfusion of hepatocyte-nonparenchymal cell (NPC) cocultures with medium supplemented with hepatocyte growth factor (HGF) and heparin-binding epidermal growth factor-like growth factor (HB-EGF) was carried out. On day 1 of culture, perfusion at a constant shear stress of 1.3 dyn/cm2 enhanced ammonia metabolic and urea synthetic activities of hepatocytes. These enhanced activities were sustained up to day 7 only when growth factors were present. In contrast, no beneficial effects of growth factors on these activities were observed in static cultures. In perfusion cultures, three-dimensional cell aggregates were formed. On the surface of these aggregates, flattened cell layers composed mainly of NPCs were found, and the central cluster of cell aggregates was composed of round-shaped hepatocytes and reticulin fibrils. These observations strongly suggested that the reconstruction of different types of liver cells and connective tissues formed tissue-mimicking cell aggregates in the perfusion culture that was able to modulate the liver-specific functions of hepatocytes. Thus, perfusion culture conditions of the hepatocyte--NPC coculture system should be appropriately designed to induce suitable reconstruction of the cultured cells for use as a bioartificial liver device.

Transdifferentiation of rat hepatocytes into biliary cells after bile duct ligation and toxic biliary injury

Rats with chimeric livers were generated by using the protocol of injecting hepatocytes from dipeptidyl peptidase IV (DPPIV)-positive donors into retrorsine-treated DPPIV-negative recipients subjected to partial hepatectomy. Rats with established chimeric livers were subjected to bile duct ligation, with or without pretreatment with the biliary toxin methylene diamiline (DAPM). Ductules bearing the donor hepatocyte marker DPPIV were seen at 30 days after bile duct ligation. The frequency of the ductules derived from the donor hepatocytes was dramatically enhanced (36-fold) by the pretreatment with DAPM. In conclusion, our results show that hepatocytes can function as facultative stem cells and rescue the biliary epithelium during repair from injury when its proliferative capacity is being compromised.

The keratin cytoskeleton in liver diseases

The keratin intermediate filament (IF) cytoskeleton of hepatocytes has continuously gained medical relevance over the last two decades. Originally it was mainly recognized as a differentiation marker for diagnostic purposes in pathology. However, keratin IFs were soon identified as major cellular structures to be affected in a variety of chronic liver diseases, such as alcoholic and non-alcoholic steatohepatitis (ASH, NASH), copper toxicosis, and cholestasis. Based on observations in keratin gene knock-out mice, the insight into the functional role of keratins was extended from a mere structural role providing mechanical stability to hepatocytes, to an additional role as target and modulator of toxic stress and apoptosis. The functional relevance of keratins in human diseases has recently been underlined by the identification of mutations in keratin genes in patients with liver cirrhosis.

Progenitor cell expansion: an important source of hepatocyte regeneration in chronic hepatitis

BACKGROUND/AIMS

Progenitor cell activation with subsequent maturation to hepatocytes and cells of the biliary lineage has been demonstrated in a variety of chronic liver diseases but the kinetics and magnitude of the progenitor cell response has not been adequately studied in detail in chronic hepatitis. We undertook this study to evaluate factors responsible for the progenitor cell/ductular response and further dissect the role of disease grade and stage as determinants of hepatocellular differentiation of bipotential progenitor cells in chronic hepatitis.

METHODS

Cytokeratin 7 (and 19) stained biopsies from patients with chronic hepatitis C (n = 47), hepatitis B (n = 20), and autoimmune hepatitis (n = 20) were studied. Ploidy analysis and proliferation indices were evaluated in a subset of cases.

RESULTS

Ductular reactions were present in the majority of cases (97%), appeared early in disease, and correlated with disease activity, while progenitor cell derived hepatocyes appeared later in disease and their extent correlated with disease stage. Proliferation indices of all cell types correlated with disease activity.

CONCLUSIONS

Progenitor cell derived hepatocytes accrue in chronic hepatitis, possibly related to native hepatocellular dysfunction. However, the fate of these hepatocytes is unclear.

Computerized morphometry of the cirrhotic liver: Comparative analysis in primary biliary cirrhosis, alcoholic cirrhosis, and posthepatitic cirrhosis

Fibrosis and nodular regeneration are the hallmarks of liver cirrhosis. To assess the degree of fibrosis and the severity of the structural changes affecting parenchymal and extraparenchymal components in liver cirrhosis, a computerized morphometric model has been applied to liver specimens from patients undergoing liver transplantation for primary biliary cirrhosis, posthepatitic and alcoholic cirrhosis. Fifty-eight hepatectomy specimens from patients undergoing liver transplantation for cirrhosis were analyzed: 17 alcoholic, 28 posthepatitic (HBV-related and HCV-related cirrhosis), and 13 primary biliary cirrhoses. Liver specimens were fixed in 10% neutral-buffered formalin and embedded in paraffin. Sections were stained with chromotrope-aniline blue method and monoclonal antibodies against cytokeratin 7 and CD31. Volume fractions of parenchymal compartment and fibrosis were stereologically determined on the specimens stained with chromotrope-aniline blue method. Volume fractions of portal bile ducts, proliferated bile ductules, and hepatocytes with biliary metaplasia were measured on cytokeratin 7 stains, while volume fractions of capillary units have been evaluated on CD31 staining. Volume fraction of fibrosis was higher in primary biliary cirrhosis than in the other disease-induced cirrhosis. The main differences were related to immunohistochemical staining. Volume fraction of hepatocytes with biliary metaplasia was higher in HCV-related cirrhosis, whereas volume fractions of biliary structures were more prominent in HBV-related cirrhosis. Primary biliary cirrhosis was characterized by a reduced number of bile ducts and by a wider expression of cytokeratin 7 into periportal hepatocytes. Capillary units were more prominent in primary biliary cirrhosis than alcoholic and posthepatitic cirrhosis. Our computerized morphometric model well describes and quantifies the morphological alterations of the liver and it could represent an adjunctive tool to evaluate the degree of dysplastic phenomena involving parenchymal and extraparenchymal compartments.

Simultaneous segmental obstruction of bile duct and portal vein markedly changes a population of biliary and hepatic cells in human liver

BACKGROUND AND AIMS

No studies have investigated histologic changes caused by simultaneous segmental obstruction of the bile duct and portal vein in human liver.

PATIENTS/METHODS

Liver tissues with simultaneous obstruction of the segmental bile duct and portal vein (O(+/+) liver), with segmental bile duct obstruction alone (O(+/-) liver), and without obstruction (O(-/-) liver) were obtained from patients who underwent hepatectomy, and studied morphologically and immunohistochemically.

RESULTS

In O(+/+) liver, the proportional area consisting of hepatocytes was significantly less (31.0+/-25.8%) than in O(+/-) liver (78.4+/-18.9%) or O(-/-) liver (86.5+/-9.2%). In contrast, the proportional area consisting of biliary epithelial cells was significantly higher in O(+/+) liver (9.1+/-6.1%) than in O(+/-) liver (1.6+/-1.5%) or O(-/-) liver (0.7+/-0.6%). The proportional area consisting of fibrous tissue also was significantly higher in O(+/+) liver than in the other two groups. In O(+/+) liver, some cells located at the periphery of hepatocyte areas were immunoreactive for both hepatocyte and biliary epithelial cell markers.

CONCLUSION

Simultaneous segmental obstruction of the bile duct and portal vein induces a marked ductular increase, periportal fibrosis, and a reduction in the number of hepatocytes in human liver tissue.

Cytokeratin 7 staining of hepatocytes predicts progression to more severe fibrosis in alcohol-fed baboons

BACKGROUND/AIMS

Not all alcoholic patients develop severe liver disease with fibrosis progressing to cirrhosis. It is of practical importance to determine whether some markers can predict progression of liver fibrosis.

METHODS

We used a baboon model that mimics human alcoholic liver disease. Cytokeratin 7 and 19 expression and fat deposition were investigated in serial liver biopsies of 18 animals undergoing prolonged alcohol administration (range 2-17 years) and in four controls. Fibrosis was graded histologically and was also assessed quantitatively by image analysis.

RESULTS

Ten animals did not show a progression of liver disease even after 17 years of alcohol administration, but eight animals fed alcohol exhibited a progression of liver disease from no fibrosis or perivenular fibrosis to septal fibrosis or cirrhosis within 7 years. In normal liver, cytokeratin 7 and cytokeratin 19 immunostaining is restricted to bile duct cells. Hepatocellular cytokeratin 7 was observed only in those animals which progressed to more severe stages of fibrosis and it anticipated this progression by 4.2 years on average.

CONCLUSIONS

In alcohol-fed baboons, cytokeratin 7 staining of hepatocytes (but not cytokeratin 19, nor fat deposition) predicts with a high degree of sensitivity and specificity progression to more severe liver disease.

Laminin induces the expression of cytokeratin 19 in hepatocellular carcinoma cells growing in culture

AIM: To study the abnormal cytokeratin (CK) expression, emergence of CK19 with or without CK7, in liver parenchymal cells and the role of laminin (LN), a basement membrane protein, in this process.

METHODS: Six hepatocellular carcinoma (HCC) cell lines were examined for different CKs, LN and its receptor by immunocytochemistry and Western blotting. Double immunofluorescent reaction, laser-scanning confocal microscopy and an in vitro induction procedure were used to demonstrate the role of LN in regulating CK19 expression in these cells.

RESULTS: Immunoreactivities for CK8, CK18, CK7 and the receptor for LN were observed in all the six HCC cell lines examined. However, CK19 was merely found in four of the six cell lines, and was in any case associated with LN expression. Laser-scanning confocal microscopy demonstrated the concomitant presence of these two molecules in most of the positive cells. In the two HCC cell lines, originally negative for CK19, addition of LN to the culture medium resulted in an induction of CK19 in a dose-dependent manner. Both the artificially induced and the intrinsic production of CK19 were completely blocked by an antibody to LN.

CONCLUSION: LN can induce expression of CK19 in HCC cells in vitro, providing direct evidence for our hypothesis that the abnormal hepatocytic CK19 expression in situ is due to pathologic LN deposition.

Mallory body formation in primary biliary cirrhosis is associated with increased amounts and abnormal phosphorylation and ubiquitination of cytokeratins

BACKGROUND/AIMS

Animal studies revealed a key role of toxic bile acids in the regulation of hepatocytic cytokeratin (CK) expression and Mallory body (MB) formation. In this study, we compared CK expression, phosphorylation, and ubiquitination in primary biliary cirrhosis (PBC), chronic hepatitis C (CHC) and control livers to determine whether bile acid-induced CK alterations are associated with cytoskeletal alterations and MB formation in a prototypic chronic cholestatic liver disease.

METHODS

CK 8 and CK 18 mRNA and protein levels were investigated by reverse transcriptase-polymerase chain reaction and Western blotting. Intermediate filament (IF) cytoskeletal alterations were assessed by immunofluorescence microscopy using antibodies against CKs, CK phosphoepitopes, MBs, and ubiquitin.

RESULTS

Despite unchanged mRNA levels, CK 8 and CK 18 protein levels were significantly elevated in PBC suggesting stabilization of CKs, possibly due to decreased degradation. CK-IF alterations in PBC comprised increased density with abnormal phosphorylation of the IF network of hepatocytes in acinar zone 1 and in the periphery of cirrhotic nodules. In addition, in these areas hepatocytes with diminished IF network containing MBs consisting of abnormally phosphorylated and ubiquitinated CK were observed.

CONCLUSIONS

These findings support our concept that IF cytoskeletal alterations and MB formation in cholestatic liver diseases are related to bile acid-induced cell stress.

Coexpression of neural cell adhesion molecules and bcl-2 in intrahepatic cholangiocarcinoma originated from viral hepatitis: relationship to atypical reactive bile ductule

It has been shown that atypical reactive bile ductules (ARBD) display positive immunoreactivity of neural cell adhesion molecules (NCAM) and bcl-2. We investigated the clinicopathological features of intrahepatic cholangiocarcinoma (CC) arising in cases of viral hepatitis B or C (VHBC) and examined their relation to ARBD by means of immunohistochemical analysis. Sixty-eight surgical cases with CC were included in this study. The cause of the background liver disease was hepatitis B surface antigen (HBsAg)(+) in eight cases, antihepatitis C virus antibody (HCVAb)(+) in 13 cases, both HBsAg(+) and HCVAb(+) in one case, and both HBsAg(-) and HCVAb(-) in 46 cases. The average age of patients with CC arising in the HBsAg(+) group was significantly less than that of patients with CC in the HCVAb(+) group (P = 0.0192). Immunohistochemically, CC arising in the HBsAg(+) and HCVAb(+) groups was correlated with coexpression of NCAM/bcl-2 in the tumor cells (P = 0.0068 and P = 0.0382, respectively). Among the 12 cases of CC coexpressing NCAM/bcl-2, 11 were of mass-forming and peripheral type (P = 0.0437), and lymph node metastasis was a rare finding compared with CC showing negative coexpression of NCAM/bcl-2 (P = 0.0213). The tumor cells of CCs arising in VHBC have some characteristics of ARBD. In such tumors, because lymph node metastases were rarely seen and lymph node dissection did not improve patient's survival, lymph node dissection can be limited.

Cytokeratins as targets for bile acid-induced toxicity

Cholestasis is associated with retention of potentially toxic bile acids and profound cytoskeletal alterations of hepatocytes. Given the well-established cytoprotective role of hepatocyte keratins this study aimed to determine the effects of cholestasis on the cytokeratin (CK) intermediate filament network in mouse liver. Mice were subjected to common bile duct ligation or sham operation. Mice were also fed a cholic acid or ursodeoxycholic acid (UDCA)-supplemented diet (0.1%, 0.5%, and 1%) or control diet for 7 days. CK 8 and CK 18 expression was studied by competitive reverse transcriptase-polymerase chain reaction, in situ hybridization, Western blot analysis, and immunofluorescence microscopy. Common bile duct ligation and cholic acid feeding significantly stimulated CK 8 and CK 18 mRNA and protein levels compared to controls, whereas UDCA had no effect. CK overexpression was accompanied by pronounced phosphorylation. Our results show that potentially toxic bile acids induce hepatocytic CK 8 and CK 18 expression and phosphorylation whereas nontoxic UDCA has no effect on CKs. Thus, increased hepatocellular CK expression and phosphorylation in cholestasis may be caused by retention of toxic bile acids and reflect a hepatocellular stress response with potential beneficial effects.

Portal tract eosinophils and hepatocyte cytokeratin 7 immunoreactivity helps distinguish early-stage, mildly active primary biliary cirrhosis and autoimmune hepatitis

We studied nondiagnostic liver biopsy specimens from 20 patients with definite primary biliary cirrhosis (PBC) and 18 with definite autoimmune hepatitis (AIH) to identify distinguishing features. All patients had early-stage disease; biopsy specimens were devoid of granulomas or diagnostic features of PBC or AIH. Diagnoses were based on serologic and clinical variables. Sixteen specimens from each group were immunostained with cytokeratin 7. The density of portal tract eosinophils and number with cytokeratin 7-reactive periportal hepatocytes were quantified. Sixteen of 18 patients with AIH and 13 of 20 with PBC had no or minimal bile duct injury. Histologic activity index scores were 5.8 in AIH and 5.7 in PBC. The mean portal eosinophil score was greater in PBC than in AIH. Cytokeratin 7 identified many central bile ducts that were obscured by portal inflammation. The mean periportal cytokeratin 7-reactive hepatocyte score was greater in PBC than in AIH. Portal eosinophils and cytokeratin 7 reactivity in periportal hepatocytes are supportive of PBC rather than AIH. No morphologic features were supportive of AIH. Cytokeratin 7 reactivity in periportal hepatocytes may be an early response to PBC-induced biliary obstruction in other regions of the liver.

Anti-cytokeratin antibodies in sera of the patients with autoimmune hepatitis

Antibodies to cytokeratin (CK) are found in some patients with autoimmune hepatitis (AIH). We hypothesized that serum antibodies to CK8, CK18 and CK19 may be formed in patients with AIH. We established an enzyme-linked immunosorbent assay (ELISA) to quantify anti-CK8, anti-CK18 and anti-CK19 antibodies in sera of patients with AIH. In addition, we quantified circulating CK8:anti-CK8 antibody as well as CK18:anti-CK18 antibody immune complexes in patients' sera, by an enzyme-linked immunosorbent assay (ELISA). Furthermore, to evaluate the expression of CK8, CK18 and CK19 in liver tissue, immunohistochemical stainings were performed. Significantly high levels of anti-CK8, anti-CK18 and anti-CK19 antibodies were demonstrated in patients with AIH compared with normal volunteers and patients with chronic active hepatitis C (CH-C). In addition, these antibodies were significantly decreased after steroid treatment. Levels of CK8:anti-CK8 and CK18:anti-CK18 immune complexes in sera of patients with AIH were significantly high compared with those of patients with CH-C and normal volunteers. Immunohistochemically, CK8 or CK18 were absent from some hepatocytes of AIH. CK19 was aberrantly expressed in periportal hepatocytes in patients with AIH, but not CH-C. This is the first study to quantify anti-CK8, anti-CK18, anti-CK19 antibodies and immune complexes in patients with AIH. The clinical significance of anti-CK antibodies and their immune complexes of AIH is also discussed.

Cholangiocytic apoptosis in chronic ductopenic rejection

The significance of cholangiocytic apoptosis as a mechanism of ductopenia in liver rejection remains controversial. In a previous study, the presence but not the extent of ductal apoptosis was assessed by electron microscopy. Other previously published studies using an in situ hybridization method (in situ end labeling) produced conflicting results (no apoptosis v massive apoptosis). We studied 47 liver needle biopsies from 8 patients with chronic ductopenic rejection confirmed by pathologic examination of the failed grafts. These biopsies were performed because of graft dysfunction, during a period of several months before retransplantation, and they showed cholangiocytic injury with progressive ductal paucity. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling (TUNEL) was used to detect apoptosis (tissue digestion with proteinase K 20 microg/mL for 20 minutes). The interlobular bile ducts did not show labeling, even in lymphocytic cholangitis with obvious epithelial injury. However, there was minimal staining of ductular nuclei. Lymphocytic nuclei were also labeled. Apoptosis was not detectable in the vanishing interlobular bile ducts, even when more representative samples were studied and a more sensitive method was used. Unless apoptosis of cholangiocytes is an exceptionally rapid process escaping detection by conventional methods, ductopenia results mainly from ordinary, nonprogrammed cholangiocytic death. Apoptosis could still be involved in the pathogenesis of ductopenia by depleting cholangiocytic precursors, generally presumed to reside in ductules. This is a possible mechanism suggested by the following: (1) the established role of apoptosis in the homeostatic control of immature/progenitor cells, (2) the paucity of ductular proliferation in chronic rejection, (3) the previously reported decrease of ductular bcl-2 expression in rejection, and (4) the sporadic ductular TUNEL labeling seen in this study.

Cytokeratin subtypes in biliary atresia: immunohistochemical study

The etiology of biliary atresia (BA) remains unknown, but ductal-plate malformation and insufficient ductal-plate remodeling have been suggested to play important roles, so it is beneficial to examine the maturation and differentiation of bile ducts in BA. Different epithelial types are characterized by the expression of specific cytokeratin (CK) subtypes. CK can therefore serve as a 'lineage marker' of epithelial cells. CK subtypes have not been previously examined in BA. In this study, we examined the maturation of bile-duct cells in BA (n = 45) using immunohistochemistry of CK subtypes, with mouse monoclonal antibodies to CAM5.2, and CK subtypes 7, 8, 13, 14, 17, 19 and 20. We then compared these findings with pediatric non-BA (n = 11) and fetal (n = 21) liver. We semiquantitatively evaluated the findings using a H score method. In the fetal liver, immunoreactivity for CAM5.2, CK-7, CK-8 and CK-19 was detected in bile-duct cells, and CAM5.2 and CK-8 immunoreactivity was also detected in hepatocytes. The distribution of these CK subtypes was the same in fetal, pediatric non-BA and BA liver. However, CK-7 immunoreactivity was markedly weaker in bile ducts of fetal (H scores: ductal plate 0 +/- 0; remodeling 9.5 +/- 40.3; remodeled 37.3 +/- 60.8) and BA (H score: 200.9 +/- 55.3) liver compared to non-BA liver (H score: 251.1 +/- 33.5). In addition, CK-20 was detected in the bile ducts of the fetal and BA liver, but not in non-BA liver. These findings suggest that the expression patterns of CK subtypes in bile-duct cells in BA are similar to that in developing bile-duct cells, which is indicative of bile-duct cell immaturity.

Immature hepatic tumor of bimodal differentiation in a young adult patient: a novel lesion expressing beta-catenin and mimicking a distinct phase of hepatogenesis

PATIENT AND METHODS

A large right-sided liver tumor was incidentally discovered and totally resected in a 21-year-old female patient without chronic liver disease. Histopathologic examination revealed that this malignant tumor does not fit any of the known types of primary liver tumors reported thus far.

RESULTS

The lesion chiefly consisted of numerous solid nests composed of immature epithelial cells disclosing a marker profile typical for hepatocytes and strongly expressing beta-catenin. These nests were tightly associated with abnormal duct-like profiles exhibiting features of bile duct cells.

CONCLUSIONS

The finding of numerous neoplastic hepatobiliary units ('liverlets') suggests that this tumor may mimic a distinct developmental phase of hepatogenesis close to ductal plate formation.

Deep intralobular extension of human hepatic 'progenitor cells' correlates with parenchymal inflammation in chronic viral hepatitis: can 'progenitor cells' migrate?

Ductular reaction and putative progenitor cells (or 'progenitor cells'), which are presumed to be the human counterpart of the oval cells in rat liver, have been discerned in various human liver diseases, including chronic viral hepatitis. Since in experimental models of chronic hepatitis the activation of oval cells is correlated with the inflammatory infiltrate, this study investigated whether there is a correlation in chronic viral hepatitis between the number of 'progenitor cells' extending into the lobule and the severity of parenchymal inflammation, on the one hand, and the extent of ductular reaction and the severity of interface hepatitis, on the other hand. Liver biopsies of 55 patients with chronic hepatitis B and/or C were used. The severity of parenchymal inflammation and of interface hepatitis was semiquantitatively graded on a haematoxylin and eosin-stained paraffin section, while the number of 'progenitor cells' and the extent of the ductular reaction were assessed on a serial section stained for cytokeratin (CK) 7. In addition, more extensive phenotyping of 'progenitor cells' was performed on sections from frozen material from five patients, using antibodies against CK7, CK8, CK18, CK19, chromogranin-A, and the rat oval cell marker OV-6. The number of more centrally located 'progenitor cells' correlated significantly with the severity of the parenchymal inflammation, while the extent of the ductular reaction correlated significantly with the severity of interface hepatitis. These findings suggest that in chronic viral hepatitis, inflammation plays a role in 'progenitor cell' activation and its topography. In cases with moderate and severe lobular inflammation, 'progenitor cells' were strikingly scattered throughout the parenchyma and surrounded by intermediate hepatocyte-like cells, suggesting their migration into the parenchyma and their differentiation towards the hepatocytic lineage.

Aberrant expression of cytokeratin 7 as a histological marker of progression in primary biliary cirrhosis

AIM

We evaluated the aberrant expression of cytokeratin 7 (CK-7) in hepatocytes as a marker of cholestasis and progression in primary biliary cirrhosis (PBC).

PATIENTS AND METHODS

The expression of CK-7 was studied by immunohistochemistry in 83 cases of PBC. This expression was compared with biochemical data, the deposition of copper-associated protein, and previous histological classifications.

RESULTS

In normal liver, CK-7 was expressed exclusively in bile duct epithelial cells (BDE). In PBC, the expression was also observed in hepatocytes. The expression pattern was classified as follows: Grade 0, BDE as in normal; Grade 1, proliferated bile ductules; Grade 2, periportal hepatocytes in addition to proliferated bile ductules; Grade 3, intralobular hepatocytes; Grade 4, the majority of hepatocytes. The grades correlated with serum bilirubin levels but not with serum levels of biliary enzymes. A discrepancy between the CK-7 grading and Ludwig's classification was noted in cases with Stage 1 of the CK-7 grading who were considered Stage 2 or 3 in Ludwig's classification, suggesting that cholestasis and inflammatory activity might be independent events.

CONCLUSIONS

These results suggest that the aberrant expression of CK-7 in hepatocytes may be a marker of chronic cholestasis and progression in PBC.

Elevation of cytokeratin 19 fragment in serum in patients with hepatoma: its clinical significance

OBJECTIVES

Cytokeratin 19 fragment (CK19) levels in serum have already been documented as a useful tumour marker for lung cancer. In the present study, we hypothesize that CK19 may be increased in serum from patients with hepatoma.

METHODS

We measured the CK19 levels in serum from patients with hepatoma and evaluated the correlation between CK19 level and each clinical parameter. We studied 70 patients diagnosed with hepatoma, and used 14 patients with chronic hepatitis C and 45 patients with liver cirrhosis as controls.

RESULTS

In 33 of 70 patients (47.1%) with hepatoma, the serum CK19 level was elevated to above the normal range. CK19 levels in serum from patients with hepatoma were significantly correlated with levels of alpha-fetoprotein and prothrombin induced by vitamin K absence for factor II (PIVKA-II). In 57 patients with hepatoma in whom both CK19 and alpha-fetoprotein were measured, only CK19 was elevated in seven patients (12.3%). Immunohistochemical studies using hepatoma tissues demonstrated that hepatoma cells were stained by anti-human CK19 antibody. We also demonstrated that the HepG2 cell line expressed CK1 9.

CONCLUSIONS

Our data demonstrate that hepatomas aberrantly express CK19, and that measurement of CK19 might be a useful tumour marker in diagnosing hepatoma.