Treatment with 2-AAF blocks the small hepatocyte-like progenitor cell response in retrorsine-exposed rats

BACKGROUND/AIMS: Liver regeneration after partial hepatectomy (PH) in retrorsine-exposed rats is accomplished through proliferation and differentiation of small hepatocyte-like progenitor cells (SHPCs). The cells of origin of SHPCs are not known. We investigated the possibility that SHPCs are directly derived from oval cells, a known liver progenitor cell, by combining the retrorsine/PH (RP) model with 2-acetamidofluorene (2-AAF), an anti-mitotic agent that elicits an oval cell reaction in response to liver deficit. METHODS: Male Fischer 344 rats were treated with retrorsine (30 mg/kg ip) at 6 and 8 weeks of age, with PH 5 weeks after the final treatment. Seven days prior to PH, a 21-day 2-AAF (50mg) time-release pellet was inserted subcutaneously. Livers were harvested at 3, 7, 10, 14, and 21-days post-PH. RESULTS: Liver sections from animals treated with 2-AAF/retrorsine/PH (2-AAF/RP) contain significant numbers of proliferating oval cells, but no SHPCs at 7-days post-PH, while RP animals exhibit significant numbers of SHPCs and minimal oval cell reaction. Between 10 and 14-days post-PH, new hepatocyte clusters appear in 2-AAF/RP treated rats. Labeling of proliferating oval cells with BrdU at 6-days post-PH demonstrated that these new hepatocytes represent the progeny of differentiating oval cells. CONCLUSIONS: The observed differences in progenitor cell responses between 2-AAF/RP and RP animals strongly suggest that SHPCs are not the progeny of oval cell precursors, but represent an independent liver progenitor cell population.     

Bax-mediated apoptosis in the livers of rats after partial hepatectomy in the retrorsine model of hepatocellular injury

Retrorsine is a member of the pyrrolizidine alkaloid family of compounds whose toxic effects on the liver include a long-lasting inhibition of the proliferative capacity of hepatocytes. Despite the retrorsine-induced blockade of hepatocyte proliferation, retrorsine-exposed rats are able to reconstitute completely their liver mass after surgical partial hepatectomy (PH) via the sustained proliferation of a population of small, incompletely differentiated hepatocyte-like progenitor cells (SHPCs). The extensive proliferation of SHPCs in retrorsine-injured livers is accompanied by the progressive loss of irreversibly injured megalocytes. To study the mechanism by which retrorsine-damaged hepatocytes are removed after PH, we performed TUNEL analysis to establish apoptotic indices for hepatocytes in the livers of retrorsine-exposed and control rats up to 14 days post-PH. Apoptotic indices are highest (approximately 6.0%) in the livers of retrorsine-exposed rats at 1 day post-PH, gradually declining thereafter, yet remaining significantly elevated (approximately 1%) over control rats (<0.1%) at 14 days post-PH (P <.05). After PH, levels of the proapoptotic protein Bax are increased in livers from retrorsine-exposed rats relative to the levels observed in control livers. Similarly, levels of the antiapoptotic protein Bcl-x(L) are significantly decreased (P <.05) compared with controls at t = 0 resulting in an increased (approximately 3.5-fold) Bax/Bcl-x protein ratio that is significantly elevated (P <.05) compared with controls. Finally, increased levels of Bax protein are localized to the mitochondria of retrorsine-exposed rat livers after PH during the same time that cytochrome c is released. These observations combine to suggest that retrorsine-injured hepatocytes are removed after PH via apoptotic pathways dependent on relative levels and localization of Bax and Bcl-x(L) protein.     

The sources of parenchymal regeneration after chronic hepatocellular liver injury in mice

After liver injury, parenchymal regeneration occurs through hepatocyte replication. However, during regenerative stress, oval cells (OCs) and small hepatocyte like progenitor cells (SHPCs) contribute to the process. We systematically studied the intra-hepatic and extra-hepatic sources of liver cell replacement in the hepatitis B surface antigen (HBsAg-tg) mouse model of chronic liver injury. Female HBsAg-tg mice received a bone marrow (BM) transplant from male HBsAg-negative mice, and half of these animals received retrorsine to block indigenous hepatocyte proliferation. Livers were examined 3 and 6 months post-BM transplantation for evidence of BM-derived hepatocytes, OCs, and SHPCs. In animals that did not receive retrorsine, parenchymal regeneration occurred through hepatocyte replication, and the BM very rarely contributed to hepatocyte regeneration. In mice receiving retrorsine, 4.8% of hepatocytes were Y chromosome positive at 3 months, but this was frequently attributable to cell fusion between indigenous hepatocytes and donor BM, and their frequency decreased to 1.6% by 6 months, as florid OC reactions and nodules of SHPCs developed. By analyzing serial sections and reconstructing a 3-dimensional map, continuous streams of OCs could be seen that surrounded and entered deep into the nodules of SHPCs, connecting directly with SHPCs, suggesting a conversion of OCs into SHPCs. In conclusion, during regenerative stress, the contribution to parenchymal regeneration from the BM is minor and frequently attributable to cell fusion. OCs and SHPCs are of intrinsic hepatic origin, and OCs can form SHPC nodules.     

Regulatory effects of corticosterone on ornithine decarboxylase activity during liver regeneration in rats

AIMS: The regulation of ornithine decarboxylase (ODC) gene expression and enzyme activity by corticosterone during rat liver regeneration induced by partial hepatectomy (PH) was evaluated. METHODS: Bilateral adrenalectomies were performed on ether-anesthetized rats 3 days before PH. Corticosterone in sesame oil was injected subcutaneously to adrenalectomized rats. ODC mRNA, ODC protein and enzyme activity were detected by in situ hybridization, Western blot and high performance liquid chromatography (HPLC), respectively. RESULTS: The ODC mRNA levels, protein accumulation and enzyme activity were lower in the intact liver compared to the regenerating liver. After PH, mRNA levels were remarkably enhanced in all groups and peaked at 5 h post-PH, and presented a persistent increase only in adrenalectomy rats during the regeneration process. Corticosterone treatment resulted in a dose-dependent decrease in ODC mRNA content after 5 h post-PH. ODC protein accumulation in adrenalectomy rats was higher than that in sham-adrenalectomy rats, but it decreased in corticosterone-treated (10 mg/kg) rats until 24 h post-PH, with a strong decline seen in 40 mg/kg corticosterone-treated rats. ODC activity was rapidly promoted, and the highest levels were observed at 6 h after PH in all groups. After corticosterone treatment, the activities declined significantly at 6 h post-PH, with the lowest value found in the 40 mg/kg group. CONCLUSIONS: Corticosterone treatment results in dose-dependent decreases in ODC mRNA and enzyme protein both in the intact liver and the regenerating liver. The change in ODC activity is partially related to alterations of ODC mRNA and protein accumulation.     

The role of p28GANK in rat oval cells activation and proliferation

Abstract: Background: Human gankyrin gene product (p28^GANK) is a novel oncogenic protein ubiquitously overexpressed in hepatocellular carcinoma and also plays a role in cell cycle progression in normal hepatocytes and liver regeneration. However, little is known about the physiological role of p28^GANK in the liver oval cell activation and proliferation. We investigated the possible involvement of p28^GANK in oval cell‐mediated liver regeneration and cell cycle progression. Methods: We examined the different p28^GANK expression in 2‐acetylaminofuorene/partial heptectomy (2‐AAF/PH) rats, as a model of oval cell activation, and PH rats by Western blot and immunohistochemistry. Oval cells isolated from 2‐AAF/PH rat model were cultured in our study. p28^GANK expression was examined in the oval cells after mitogenic stimulation. Results: In 2‐AAF/PH rats, p28^GANK was expressed in the activated oval cells and located in the nucleus. p28^GANK protein expression was increased in 2‐AFF/PH rats after hepatectomy lasting for 96 h when retinoblastoma maintained hyperphosphorylation status at Ser‐795. The isolated oval cells express AFP, OV6, CK19, CD34, CD45, c‐kit and albumin. After epidermal growth factor stimulation, p28^GANK protein was up‐regulated in oval cells from 24 to 72 h, which coincided with increased expression of CyclinD1, CDK4 and decreased of Rb protein. Conclusions: p28^GANK expression was increased in oval cell‐mediated liver regeneration and oval cells after mitogenic stimulation. Thus, p28^GANK may play a role in oval cell‐mediated liver regeneration and liver oval cell cycle progression.     

Mature hepatocytes are the source of small hepatocyte-like progenitor cells in the retrorsine model of liver injury

BACKGROUND/AIMS: Mature hepatocytes divide to restore liver mass after injury. However, when hepatocyte division is impaired by retrorsine poisoning, regeneration proceeds from another cell type: the small hepatocyte-like progenitor cells (SHPCs). Our aim was to test whether SHPCs could originate from mature hepatocytes. METHODS: Mature hepatocytes were genetically labeled using retroviral vectors harboring the beta-galactosidase gene. After labeling, retrorsine was administered to rats followed by a partial hepatectomy to trigger regeneration. A liver biopsy was performed one month after surgery and rats were sacrificed one month later. RESULTS: We observed the proliferation of small hepatocytes arranged in clusters in liver biopsies. These cells expressed Ki67 antigen and displayed a high mitotic index. At sacrifice, regeneration was completed and clusters had merged. A significant proportion of clusters also expressed beta-galactosidase demonstrating their origin from labeled mature hepatocytes. Finally, the overall proportion of beta-galactosidase positive cells was identical at the time of hepatectomy as well as in liver biopsy and at sacrifice. CONCLUSIONS: The constant proportion of beta-galactosidase positive cells during the regeneration process demonstrates that mature hepatocytes are randomly recruited to proliferate and compensate parenchyma loss in this model. Furthermore, mature hepatocytes are the source of SHPC after retrorsine injury.     

Progenitor cells in diseased human liver

Hepatic progenitor cells are immature epithelial cells that reside in the smallest ramifications of the biliary tree in human liver. These cells are capable of differentiating toward the biliary and the hepatocytic lineages and represent the human counterpart of the oval cells in murine liver. An increased number of progenitor cells (referred to as "activation") and differentiation of the same toward hepatocytes or bile duct epithelial cells, or both, is a component of virtually all human liver diseases. The extent of progenitor cell activation and the direction of differentiation are correlated with the severity of the disease and the type of mature epithelial cell (hepatocyte or bile duct epithelial cell), respectively, that is damaged. Analogous to findings in animal models of hepatocarcinogenesis, human hepatic progenitor cells most likely can give rise to hepatocellular carcinoma. The factors that govern human hepatic progenitor cell activation and differentiation are beginning to be identified.     

Vascular medial hyperplasia following chronic, intermittent exposure to 4,4′-methylenedianiline

4,4'-Methylenedianiline (DAPM) is an aromatic amine used in the synthesis of polyurethanes and epoxy resins. Acute exposure to DAPM produces hepatobiliary toxicity in humans as well as animal models. However, the toxic effects of intermittent DAPM exposure have not been explored. We treated male and female rats with 25 mg DAPM/kg or vehicle once per week for 17-22 wk. Though concentric fibrosis around bile ducts of the liver was noted, vascular medial hyperplasia was also prominent. Morphometric analysis of histologic sections revealed that in male rats, vessel wall area increased relative to lumen area in hepatic arteries by 22 wk. However, in female rats, wall areas of both hepatic and pulmonary arteries increased relative to lumen area by 17 wk. In both male and female rats, increased wall thickness was localized to the medial layer; no intimal changes were noted. In vitro treatment of vascular smooth muscle cells (VSMC) with 25-100 microM DAPM resulted in increased DNA synthesis and VSMC proliferation. To test whether the observed alterations in cell cycle control involved VSMC-mediated metabolism of DAPM to electrophilic intermediates, cells were treated with DAPM or DAPM plus 50 microM N-acetylcysteine (NAC). Coincubation with NAC afforded dramatic protection against DAPM-induced VSMC proliferation. Though DAPM had no appreciable effect on levels of reduced glutathione, oxidized glutathione, or oxidant production, DAPM increased glutathione-S-transferase activity in VSMC. These data indicate that DAPM can initiate VSMC proliferation, possibly via VSMC-mediated metabolism of DAPM to reactive intermediates.     

胞外基质Matrilin-2在肝再生中与大鼠卵圆细胞的关系

目的:探讨肝脏胞外基质Matrilin-2在肝再生中与卵圆细胞的关系及作用.方法:采用改良的Soft-Farber建立大鼠肝脏卵圆细胞增殖模型,对照组灌喂生理盐水.分别取术后2、4、6、9、12、15 d大鼠肝组织,采用免疫组织化学以及Western blot的方法动态观察大鼠卵圆细胞增殖模型中肝脏胞外基质成分Matrilin-2的变化与卵圆细胞的关系.结果:肝脏部分切除术(partial hepatectomy,PH)后第2天,卵圆细胞开始向门静脉周围区域增殖,Matrilin-2主要出现在门静脉周围的肝窦状隙内;术后第9天,卵圆细胞进一步向肝实质内增殖,Matrilin-2表达增加;术后第12天,随着卵圆细胞分化为小肝细胞结节,大多数Matrilin-2位于结节周边,少数出现在结节内.Matrilin-2的含量自肝切除后第2天开始升高,第9天达到高峰,第12天后逐步恢复生理水平.结论:肝脏胞外基质成分Matrilin-2与卵圆细胞介导的肝脏再生存在紧密联系并发挥重要的调控作用.     

Physiological variations of stem cell factor and stromal‐derived factor‐1 in murine models of liver injury and regeneration

Background/Aims: Stem cell factor (SCF) and stromal‐derived factor‐1 (SDF‐1) regulate the regenerative response to liver injury, possibly through activation of liver progenitor ‘oval’ cells and recruitment of circulating, marrow‐derived progenitors. Methods: We performed a detailed analysis of SCF, SDF‐1 and oval cell proliferation induced by tyrosinaemia, 3,5‐diethoxycarbonyl‐1,4‐dihydrocollidine (DDC) or liver irradiation in mice by ELISA and immunofluorescence. Results: Liver injury in the tyrosinaemia mouse is characterized by a dramatic decline in plasma SCF and absence of oval cell proliferation. In contrast, DDC induces bile duct (BD) and oval cell proliferation, and a modest decline in plasma SCF. Focal liver irradiation increases plasma SCF, but not oval cell density. In normal mouse liver, SCF is localized primarily to Kupffer cells, cholangiocytes and arterial smooth muscle, with little or no expression in hepatocytes. However, SCF appears in hepatocyte nuclei after injury, where its function is unknown. In all three models, SDF‐1 is expressed exclusively in BD epithelium, indicating that tissue SDF‐1 levels are proportional to the total mass of oval cells and cholangiocytes. However, increased plasma levels of SDF‐1 in fumaryl acetoacetate hydroxylase‐null mice were not accompanied by oval cell proliferation. Conclusion: Changes in SCF and SDF‐1 varied with the nature of liver injury and were not directly related to oval cell proliferation.     

Expression of anti-OV6 antibody and anti-N-CAM antibody along the biliary line of normal and diseased human livers

Following hepatic injury, proliferation of anastomosing ductules can be observed. The origin of this ductular reaction is not completely clear, although there is considerable evidence for proliferation of a putative hepatic progenitor cell, reported to be located in the canals of Hering (CoH) and showing morphologic similarities with rat oval cells. In this study, we analyzed the immunophenotype of solitary oval cell-like cells (SOC), intralobular groups of cuboidal cells that might represent lining cells of CoH, bile ductular cells (BDC), bile duct epithelial cells (BEC), and hepatocytes. We used the antibodies OV6, CK19, and CD56 (NCAM) in a double-staining method in a series of 111 liver specimens. The series consisted of a variety of liver diseases, primary liver tumors, and normal livers. In normal livers, SOC, CoH, BDC, and BEC were uniformly and predominantly CK19+, OV6+, and CD56-. In diseased livers SOC and BDC were CK19+, OV6+, and also CD56+. Occasionally, BEC was CD56+ in damaged bile ducts in diseased liver, e.g., PSC. CoH lining cells were not present in cirrhotic nodules and were indistinguishable from BDC in the fibrous septa. The consistent and uniform staining patterns of SOC, CoH, and BDC support the concept that these cells share the same biliary lineage and might represent one biliary structure. The expression of CD56 on these cells in diseased livers indicates that CD56 is a useful marker for a reparative or regenerative state of the biliary liver-cell constituents but not to discriminate a putative hepatic stem cell.     

Genomewide microRNA down-regulation as a negative feedback mechanism in the early phases of liver regeneration

The liver is one of the few organs that have the capacity to regenerate in response to injury. We carried out genomewide microRNA (miRNA) microarray studies during liver regeneration in rats after 70% partial hepatectomy (PH) at early and mid time points to more thoroughly understand their role. At 3, 12, and 18 hours post-PH ～40% of the miRNAs tested were up-regulated. Conversely, at 24 hours post-PH, ～70% of miRNAs were down-regulated. Furthermore, we established that the genomewide down-regulation of miRNA expression at 24 hours was also correlated with decreased expression of genes, such as Rnasen, Dgcr8, Dicer, Tarbp2, and Prkra, associated with miRNA biogenesis. To determine whether a potential negative feedback loop between miRNAs and their regulatory genes exists, 11 candidate miRNAs predicted to target the above-mentioned genes were examined and found to be up-regulated at 3 hours post-PH. Using reporter and functional assays, we determined that expression of these miRNA-processing genes could be regulated by a subset of miRNAs and that some miRNAs could target multiple miRNA biogenesis genes simultaneously. We also demonstrated that overexpression of these miRNAs inhibited cell proliferation and modulated cell cycle in both Huh-7 human hepatoma cells and primary rat hepatocytes. From these observations, we postulated that selective up-regulation of miRNAs in the early phase after PH was involved in the priming and commitment to liver regeneration, whereas the subsequent genomewide down-regulation of miRNAs was required for efficient recovery of liver cell mass. CONCLUSION: Our data suggest that miRNA changes are regulated by negative feedback loops between miRNAs and their regulatory genes that may play an important role in the steady-state regulation of liver regeneration.     

Comparative sequential changes in serum and biliary levels of bile acid components after a single dose of D-galactosamine or partial hepatectomy in the rat

In order to characterize changes in bile acid profile during liver cell damage and regeneration, levels of bile acids in serum and bile were determined by high performance liquid chromatography (HPLC) in F344 rats treated with a single dose of D-galactosamine (galactosamine, 300 mg/kg, i.p.) or subjected to two-thirds partial hepatectomy (PH). In the serum, galactosamine caused elevation of conjugated bile acids such as taurocholic acid (TCA) and tauro-beta-muricholic acid (T beta MCA) at the 24 and 48-h time points, whereas unconjugated bile acids including cholic acid (CA) at 24 h and hyodeoxycholic acid (HDCA) at 48 h were increased after PH. In the bile, elevation of TCA showed most remarkable elevation at the 24-h time point in the galactosamine-treated group. All components of biliary bile acids showed rapid decreases from 24 to 48 h. The results demonstrated that while liver tissue damaged by galactosamine is able to conjugate bile acids it allows leakage into the blood stream. In contrast, the results for rats subjected to PH indicated that liver cells during DNA synthesis are not capable of conjugating all free bile acids with taurine although a similar leakage occurs. It is concluded that obvious elevation of serum TCA or CA and biliary T beta MCA could be a useful indicator of hepatocellular proliferation.     

Novel hepatic progenitor cell surface markers in the adult rat liver

Hepatic progenitor/oval cells appear in injured livers when hepatocyte proliferation is impaired. These cells can differentiate into hepatocytes and cholangiocytes and could be useful for cell and gene therapy applications. In this work, we studied progenitor/oval cell surface markers in the liver of rats subjected to 2-acetylaminofluorene treatment followed by partial hepatectomy (2-AAF/PH) by using rat genome 230 2.0 Array chips and subsequent RT-PCR, immunofluorescent (IF), immunohistochemical (IHC) and in situ hybridization (ISH) analyses. We also studied expression of the identified novel cell surface markers in fetal rat liver progenitor cells and FAO-1 hepatoma cells. Novel cell surface markers in adult progenitor cells included tight junction proteins, integrins, cadherins, cell adhesion molecules, receptors, membrane channels and other transmembrane proteins. From the panel of 21 cell surface markers, 9 were overexpressed in fetal progenitor cells, 6 in FAO-1 cells and 6 are unique for the adult progenitors (CD133, claudin-7, cadherin 22, mucin-1, ros-1, Gabrp). The specificity of progenitor/oval cell surface markers was confirmed by ISH and double IF analyses. Moreover, study of progenitor cells purified with Ep-CAM antibodies from D-galactosamine injured rat liver, a noncarcinogenic model of progenitor cell activation, verified that progenitor cells expressed these markers. CONCLUSION: We identified novel cell surface markers specific for hepatic progenitor/oval cells, which offers powerful tool for their identification, isolation and studies of their physiology and pathophysiology. Our studies also reveal the mesenchymal/epithelial phenotype of these cells and the existence of species diversity in the hepatic progenitor cell identity.     

急性肝损伤大鼠肝卵圆细胞活化增殖的研究

目的　用D-氨基半乳糖 (D-galactosamine ,D-GalN)联合胆总管结扎 (CommonBiliaryDuctLigation ,CBDL)建立大鼠急性肝损伤模型 ,观察肝损伤后再生过程中肝卵圆细胞 (HepaticOvelCell,HOC)的活化和增殖。 方法　雄性SD大鼠 ,胆总管结扎离断术后予腹腔注射D-GalN 2 .0 g/kg ,对照组不做任何处理。处理后第 1、2、3、4、5及 6天 6个时间点测血清肝功能 ,取肝组织分别行苏木精 伊红染色、电镜、免疫组织化学及RT-PCR检测 ,并对符合HOC形态学特征且胞浆OV-6阳性染色的细胞进行计数。结果　肝功能损害以第 2天明显 (P <0 .0 1) ;对照组肝组织内未见HOC ,处理组各时间点均见有不同程度的HOC增殖反应 ,以第 3天HOC计数最多 (P <0 .0 5 ) ;HOC胞质AFP、OV 6染色阳性 ,胞核BrdU染色阳性 ;RT-PCR示模型组CGT mRNA表达明显增多。结论　用D GalN2 .0 g/kg联合CBDL可获得较满意的大鼠HOC增殖模型 ,在急性肝损伤时HOC被活化和不同程度的增殖 ,参与了肝再生过程     

Use of an asialoglycoprotein receptor-targeted magnetic resonance contrast agent to study changes in receptor biology during liver regeneration and endotoxemia in rats

The hepatic asialoglycoprotein receptor is responsible for rapid clearance of desiaylated glycoproteins from the circulation by receptor- mediated endocytosis. Previous in vitro studies in hepatocyte preparations from rats subjected to partial hepatectomy (PH) of 70% to stimulate hepatic regeneration showed decreased asialoglycoprotein (ASGP) receptor binding. We used an ASGP receptor-targeted hepatic magnetic resonance imaging (MRI) agent, BMS 180550, to demonstrate similar changes in receptor biology in vivo. BMS 180550 is an arabinogalactan-coated ultrasmall superparamagnetic iron oxide preparation. Arabinogalactan is a ligand for the ASGP receptor and, thereby, targets the contrast agent exclusively to hepatocytes. Hepatic uptake of BMS 180550 was assessed by sequential precontrast and post- contrast MRI in rats subjected to PH of 70%. In regenerating liver 1 and 3 days after PH, the maximum decrease in hepatic signal intensity (62.2% +/- 6.1 and 59.4% +/- 3.8, respectively) was significantly less than the maximum decrease seen in sham-operated animals at 1 and 3 days postsurgery (39.5% +/- 2.5 and 44% +/- 1.0, respectively). The time necessary to reach 80% of the maximum decrease in hepatic signal intensity, (t₈₀), was less than 2 minutes in control rats and increased to 7.5 +/- 1.3 min and 11.0 +/- 2.3 minutes at 1 and 3 days post-PH, respectively. By 7 days post-PH, contrast-enhanced MRI no longer detected a difference in regenerating liver. Because BMS 180550 is taken up exclusively by the liver, clearance of the agent from the blood was used as a measure of hepatic clearance. Concentration-time curves constructed by measuring changes in blood T2 after an intravenous dose of BMS 180550 were used to determine clearance of the agent. Blood clearance of BMS 180550 in normal liver (15.4 +/- 1.08 mL/min) obeyed first-order kinetics and did not vary over the dose range tested (10 to 100 micromol/L/kg iron). One, 3, 7, and 14 days post-PH, clearance varied with dose, suggesting ASGP receptor saturation. As regeneration proceeded, the dose of contrast agent needed to cause a deviation from first-order kinetics increased, suggesting gradual recovery of ASGP receptor function. Hepatic relaxation was determined by in vitro spectroscopy 60 minutes after administration of graded doses of BMS 180550 and showed dose-dependent increases in relaxation. Kinetic analysis at 1 day post-PH demonstrated a decrease in the apparent k(m) and the maximum response, R(_max), suggesting a decrease in the number of functional asialoglycoprotein receptors with concomitant increase in receptor affinity. Systemic endotoxemia, which normally accompanies hepatic regeneration induced by PH, also decreased clearance of BMS 180550 and slowed hepatic uptake of the contrast agent. Altered BMS 180550 pharmacokinetics in endotoxin- treated rats was enhanced by prior administration of small doses of competing ligand. Our studies document the value of BMS 180550 in following changes in ASGP function that accompany PH or systemic endotoxemia. This agent may be useful in assessing the degree of hepatic regeneration in patients with clinical liver disease. (Hepatology 1996 Jun;23(6):1631-41)     

Bile duct changes in alcoholic liver disease

ABSTRACT— The histologic significance of various changes in the bile ductal structures as observed by cytokeratin immunoperoxidase assay was studied in 122 patients with alcoholic liver disease (ALD) as a part of a large Veterans Administration Cooperative Study on alcoholic hepatitis. Four types of morphologic changes in the biliary structures were observed: 1) proliferation of interlobular bile ducts in the portal tracts; 2) marginal bile ductular proliferation at the periphery of the portal tracts; 3) appearance of bile duct type cells (“oval cells”) in the liver parenchyma; and 4) metaplasia of bile duct epithelium to cells resembling hepatocytes. These bile ductal changes correlated strongly with liver fibrosis (p = 0.0003; 0.0003; 0.05; 0.0035, for 1, 2, 3, and 4, respectively), cirrhosis (p<0.0001 for all four parameters), portal inflammation (p<0.0001 for 1, 2, and 4; p = 0.0024 for “oval cells“), and with overall histologic severity scores (p<0.0001; p = 0.0001; p = 0.0017; p = 0.0005, respectively). However, these changes did not correlate significantly with fatty change, parenchymal degeneration and necrosis, cellular infiltrate or Kupffer cell hyperplasia, suggesting that they are probably not the direct consequences of liver cell necrosis. Periportal piecemeal necrosis correlated significantly with both portal bile duct (p = 0.0041) and marginal (p = 0.0078) bile ductular proliferation. Among all these changes, only marginal bile ductular proliferation correlated significantly with Mallory bodies present both in the hepatocytes (p = 0.05) and the bile ducts (p = 0.01). Both marginal bile ductular proliferation and “oval cells” correlated significantly with clinical severity of the liver disease as determined by high serum bilirubin and prolonged prothrombin time (Maddrey's discriminant function). This study suggests that: 1) a variety of important morphologic changes occur in the bile ductal structures in ALD, particularly when fibrosis and cirrhosis develop; 2) “oval cells” and bile duct metaplasia are frequent in ALD and appear to be significantly related to the development of fibrosis and cirrhosis; 3) bile ductules are an integral component of piecemeal necrosis in ALD; 4) some of the bile ductal changes may influence the clinical outcome of patients with ALD.