Epigenomic Evaluation of Cholangiocyte Transforming Growth Factor-β Signaling Identifies a Selective Role for Histone 3 Lysine 9 Acetylation in Biliary Fibrosis

BACKGROUND & AIMS

Transforming growth factor β (TGFβ) upregulates cholangiocyte-derived signals that activate myofibroblasts and promote fibrosis. Using epigenomic and transcriptomic approaches, we sought to distinguish the epigenetic activation mechanisms downstream of TGFβ that mediate transcription of fibrogenic signals.

METHODS

Chromatin immunoprecipitation (ChIP)-seq and RNA-seq were performed to assess histone modifications and transcriptional changes following TGFβ stimulation. Histone modifications and acetyltransferase occupancy were confirmed using ChIP assays. Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) was used to investigate changes in chromatin accessibility. Cholangiocyte cell lines and primary cholangiocytes were used for in vitro studies. Mdr2-/- and 3,5-diethoxycarboncyl-1,4-dihydrocollidine (DDC)-fed mice were used as animal models.

RESULTS

TGFβ stimulation caused widespread changes in histone 3 lysine 27 acetylation (H3K27ac), and was associated with global TGFβ-mediated transcription. In contrast, H3K9ac was gained in a smaller group of chromatin sites and was associated with fibrosis pathways. These pathways included overexpression of hepatic stellate cell (HSC) activators such as fibronectin 1 (FN1) and SERPINE1. The promoters of these genes showed H3K9ac enrichment following TGFβ. Of the acetyltransferases responsible for H3K9ac, cholangiocytes predominantly express Lysine Acetyltransferases 2A (KAT2A). Small interfering RNA knockdown of KAT2A or H3K9ac inhibition prevented the TGFβ-mediated increase in FN1 and SERPINE1. SMAD3 ChIP-seq and ATAC-seq suggested that TGFβ-mediated H3K9ac occurs through SMAD signaling, which was confirmed using colocalization and genetic knockdown studies. Pharmacologic inhibition or cholangiocyte-selective deletion of Kat2a was protective in mouse models of biliary fibrosis.

CONCLUSIONS

Cholangiocyte expression of HSC-activating signals occurs through SMAD-dependent, KAT2A-mediated, H3K9ac, and can be targeted to prevent biliary fibrosis.

Aberrant TGF-β1 signaling contributes to the development of primary biliary cirrhosis in murine model

AIM: To investigate whether transforming growth factor-β1 (TGF-β1) signaling pathway is involved in the pathogenesis of primary biliary cirrhosis (PBC).

METHODS: A murine model of PBC was developed by injection of polyinosinic polycytidylic acids (poly I: C) in C57BL/6 mice, and the liver expressions of TGF β1, TGF-β receptor I (TβRI), TGF-β receptor II (TβRII), p-Smad2/3, monoclonal α-smooth muscle actin antibody (α-SMA) and α1 (I) collagen in the mouse model and control mice were evaluated by immunohistochemistry, immunoblotting and real-time polymerase chain reaction (RT-PCR). Lymphocyte subsets in liver were analyzed using flow cytometry.

RESULTS: The mouse model had several key phenotypic features of human PBC, including elevated levels of alkaline phosphatase, antimitochondrial antibodies, portal bile ducts inflammation, and progressive collagen deposition. Compared with control mice, protein and mRNA levels of TGF β1, TβRI, TβRII, p-Smad2/3, α-SMA and α1 (I) collagen in liver (1.7 ± 0.4 vs 8.9 ± 1.8, 0.8 ± 0.2 vs 5.1 ± 1.5, 0.6 ± 0.01 vs 5.1 ± 0.1, 0.6 ± 0.3 vs 2.0 ± 0.3, 0.9 ± 0.4 vs 3.4 ± 0.6, 0.8 ± 0.4 vs 1.7 ± 0.3, 1.1 ± 1.2 vs 11.8 ± 0.6, P < 0.05), and the total number and percentage of CD4⁺ CD25⁺ FOXP3⁺ and CD8⁺ lymphocytes (0.01 ± 0.001 vs 0.004 ± 0.00, 0.12 ± 0.04 vs 0.52 ± 0.23, P < 0.01) were higher in the mouse model.

CONCLUSION: TGFβ1 might play a dual role in the development of PBC: it suppresses inflammatory response but operates to enhance fibrogenesis. The aberrant activity of TGF-β1 signaling contributes to the development of PBC.

Identification of potential cytokine pathways for therapeutic intervention in murine primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is considered a model autoimmune disease, with the most highly directed and specific autoantibody in both murine and human autoimmunity, the anti-mitochondrial autoantibody (AMA). However, therapeutic advances in this disease have lagged behind. Herein we have taken advantage of our unique model of murine PBC in which mice immunized with 2-octynoic acid coupled to BSA (2OA-BSA), a compound identified by quantitative structure activity relationships (QSAR) of human AMA binding, develop an intense inflammatory cholangitis with striking similarities to humans with PBC. In particular, we have constructed several unique gene-deleted mice, including mice deleted of IL-12p40, IL-12p35, IFN-γ, IL-23p19, IL-17A, IL-17F and IL-22, immunized these animals with 2OA-BSA and followed the natural history of immunopathology to identify key pathways that might provide clues for successful therapy. Our data indicate that whereas both IL-12/Th1 and IL-23/Th17 are involved in cholangitis, it is the IL-12/Th1 signaling pathway that elicits pathology. In fact, deletion of IFN-γ prevents disease and suppresses autoantibodies. Importantly, deletion of the Th17 cytokines IL-17A and IL-22, but not IL-17F, reduces biliary damage; IL-17A-knockout mice have reduced levels of anti-mitochondrial antibody. We further demonstrate that the production of IFN-γ is significantly decreased in the liver of IL-23p19(-/-), IL-17A(-/-) and IL-22(-/-) mice compared with controls. However, the ability of T cells to produce IFN-γ was not affected in Th17 cytokine-deficient mice. Our data indicate that a deficient Th17 pathway suppresses the accumulation of IFN-γ producing cells in liver during the early phase of cholangitis. In conclusion, whereas IFN-γ has a pivotal role in the early events involved in the pathogenesis of autoimmune cholangitis induced by 2OA-BSA, the IL-23/Th17 pathway potentiates the effects of IL-12/IFN-γ-mediated immunopathology.

Effect of allogeneic bone marrow-derived mesenchymal stem cells transplantation in a polyI:C-induced primary biliary cirrhosis mouse model

Primary biliary cirrhosis (PBC) is a slowly progressive autoimmune disease of unknown mechanism. We established a PBC animal model by injecting C57BL/6 mice with polyinosinic-polycytidylic acid sodium (polyI:C) to investigate the therapeutic effect of bone marrow-derived mesenchymal stem cells (BM-MSC) on this model. After 6 weeks of MSC infusion, serum aminotransferase and autoimmune antibodies declined, and histological examination by hematoxylin and eosin staining showed significant amelioration of monocytes infiltration around bile ducts of mice treated with BM-MSC. Interestingly, allogeneic BM-MSC transplantation markedly increased CD4(+)Foxp3(+) regulatory T cells in peripheral blood as well as in lymph nodes when analyzed by flow cytometry. Further examination showed serum TGF-β1 increased but IFN-γ decreased significantly in PBC mice treated with MSC, while with no obvious change in IL-10 expression. Our results for the first time suggested that BM-MSC transplantation could regulate systemic immune response and enhance recovery in liver inflammation of PBC mice, raising the possibility for clinical application of allogeneic MSC in treatment of early-stage PBC patients.

Resistance to activation-induced cell death and elevated FLIPL expression of CD4+ T cells in a polyI:C-induced primary biliary cirrhosis mouse model

Primary biliary cirrhosis (PBC) is a type of organ-specific autoimmune disease in which immune tolerance is impaired by an unknown mechanism. We established a PBC animal model by injecting C57BL/6 mice with polyI:C to study activation-induced cell death (AICD) in CD4+ T lymphocytes and changes of apoptosis-associated molecules as a first step to understand the immune tolerance of PBC mice. Obvious inflammatory cell infiltration was observed in the portal area of the liver tissues in model mice and antimitochondrial antibodies (AMA) positive rate was 80%. The AICD level in both splenic and hepatic CD4+ T cells in the model group were all lower than those in controls, and in the model group the level for hepatic CD4+ T cells were significantly lower than that for splenic CD4+ T cells. Quantitative PCR revealed that FasL mRNA and TRAIL expression in CD4+ T cells in the model group decreased significantly compared with that in the control group. Western blots revealed that the expression of the anti-apoptotic protein FLIP(L) in the model group increased significantly with the FLIP(L) expression in hepatic CD4+ T cells significantly higher than that in splenic CD4+ T cells. There was a positive linear correlation between the number of infiltrated portal areas and relative expression of FLIP(L) in splenic CD4+ T cells in model group. There were no obvious changes for caspase-8 in either group. These results show that the anti-apoptotic ability of CD4+ T lymphocytes play an important role in immune tolerance in the PBC mouse model, and elevated FLIP(L) expression may enhance this ability. The inhibition of FasL and TRAIL expression may also help enhance this anti-apoptotic ability in CD4+ T lymphocytes and contribute to the aggravation of portal area inflammation.

Primary biliary cirrhosis following chemotherapy for Hodgkin's lymphoma

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease primarily affecting middle-aged women. Although little is known about the etiology of PBC, it may be induced by an autoimmune response. Here, we describe a rare case of appearance of PBC following chemotherapy for Hodgkin's lymphoma.

Induction of primary biliary cirrhosis in guinea pigs following chemical xenobiotic immunization

Although significant advances have been made in dissecting the effector mechanisms in autoimmunity, the major stumbling block remains defining the etiological events that precede disease. Primary biliary cirrhosis (PBC) illustrates this paradigm because of its high degree of heritability, its female predominance, and its extraordinarily specific and defined immune response and target destruction. In PBC, the major autoantigens belong to E2 components of the 2-oxo-acid dehydrogenase family of mitochondrially located enzymes that share a lipoylated peptide sequence that is the immunodominant target. Our previous work has demonstrated that synthetic mimics of the lipoate molecule such as 6-bromohexoanate demonstrate a high degree of reactivity with PBC sera prompted us to immunize groups of guinea pigs with 6-bromohexanoate conjugated to BSA. In this study, we provide serologic and immunohistochemical evidence that such immunized guinea pigs not only develop antimitochondrial autoantibody responses similar to human PBC, but also develop autoimmune cholangitis after 18 mo. Xenobiotic-immunized guinea pigs are the first induced model of PBC and suggest an etiology that has implications for the causation of other human autoimmune diseases. The data also reflect the likelihood that, in PBC, the multilineage antimitochondrial response is a pathogenic mechanism and that loss of tolerance and subsequent development of biliary lesions depends on either modification of the host mitochondrial Ag or a similar breakdown due to molecular mimicry.

A new xenobiotic-induced mouse model of sclerosing cholangitis and biliary fibrosis

Xenobiotics and drugs may lead to cholangiopathies and biliary fibrosis, but the underlying mechanisms are largely unknown. Therefore, we aimed to characterize the cause and consequences of hepatobiliary injury and biliary fibrosis in 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice as a novel model of xenobiotic-induced cholangiopathy. Liver morphology, markers of inflammation, cell proliferation, fibrosis, bile formation, biliary porphyrin secretion, and hepatobiliary transporter expression were studied longitudinally in DDC- and control diet-fed Swiss albino mice. DDC feeding led to increased biliary porphyrin secretion and induction of vascular cell adhesion molecule, osteopontin, and tumor necrosis factor-alpha expression in bile duct epithelial cells. This was associated with a pronounced pericholangitis with a significantly increased number of CD11b-positive cells, ductular reaction, and activation of periductal myofibroblasts, leading to large duct disease and a biliary type of liver fibrosis. After 4 weeks, we constantly observed intraductal porphyrin pigment plugs. Glutathione and phospholipid excretion significantly decreased over time. Expression of Ntcp, Oatp4, and Mrp2 was significantly reduced, whereas Bsep expression remained unchanged and adaptive Mrp3 and Mrp4 expression was significantly induced. We demonstrate that DDC feeding in mice leads to i) a reactive phenotype of cholangiocytes and bile duct injury, ii) pericholangitis, periductal fibrosis, ductular reaction, and consequently portal-portal bridging, iii) down-regulation of Mrp2 and impaired glutathione excretion, and iv) segmental bile duct obstruction. This model may be valuable to investigate the mechanisms of xenobiotic-induced chronic cholangiopathies and its sequels including biliary fibrosis.

Systemic Multifocal Epithelial Inflammations Associated with PBC-like Bile Duct Damage in Chronic Colitis Harboring TCR / xAIM / Mice: Does Lipoteichoic Acid Affect the Pathogenesis of Epithelial Inflammation Followed by Fibrosis?

Autoimmune disorder and associated multifocal organ inflammations such as dry gland syndrome are occasionally observed; however, their etiologies are not clearly understood. We previously reported that chronic colitis-harboring TCR alpha(-/-) x AIM(-/-) mice show primary biliary cirrhosis (PBC)-like bile duct damage in the liver. Gram-positive bacterial infection is one of the candidates for the pathogenesis of PBC. We also reported that the bacterial cell wall component lipoteichoic acid (LTA) was detected at the sites of inflammation around damaged bile ducts in PBC patients. On the basis of these facts, we hypothesized that LTA might affect the pathogenesis of bile duct damage in the livers of TCR alpha(-/-) x AIM(-/-) mice. LTA was detected not only in the portal area with inflammation in the liver but also throughout the gastrointestinal tract, from the stomach to the colon, and especially in the epithelium at sites of inflammation. In addition, LTA was detected around both pancreatic ducts with inflammation and at the distal renal tubules with inflammation in TCR alpha(-/-) x AIM(-/-) mice. Furthermore, in the liver, pancreas, kidney, and colon, fibrous stroma were detected at the sites of LTA-positive inflammation foci. Bacterial LTA might affect the pathogenesis of epithelial inflammation followed by fibrosis in systemic multifocal epithelial inflammations in chronic colitis-harboring TCR alpha(-/-) x AIM(-/-) mice with PBC-like bile duct damage.

Identification of 2-nonynoic acid, a cosmetic component, as a potential trigger of primary biliary cirrhosis

Antimitochondrial antibodies (AMA) are unique among autoimmune serologic reactants because of their extremely high association with the index disease primary biliary cirrhosis (PBC). This autoantibody response is specifically directed only to the lipoyl domain of the mitochondrial 2-oxo-acid dehydrogenase complexes, which prompted us to search for environmental mimotopes in the form of xenobiotics and led to our identification of 2-octynoic acid as a high-affinity reactant for AMA. To focus on the chemical characteristics requisite for binding of AMA to the xenobiotic-modified self-peptide, quantitative structure-activity relationship (QSAR) studies were performed using a panel of alkynoic compounds, including examination of the length of the carbon chain and the location of the triple bond in the identified mimotope. Analyses of octynamides that varied in the position of the triple bond demonstrated that only the 2-octynamide reacted strongly with PBC sera. Furthermore, among 2-alkynamides with varying carbon chain length, 2-octyn-, 2-nonyn- (particularly) and 2-decynamide exhibited the highest reactivity. Thus, an optimal chemical structure of the xenobiotically modified epitope recognized by AMA-positive PBC sera is provided by 2-nonynoic acid. The methyl ester of this compound is ranked 2,324th out of 12,945 compounds to which there is occupational exposure, with an 80% female prevalence due to its use in cosmetic products. Our findings illustrate an unusual polyreactivity of anti-PDC-E2 and support the idea of epitope mimicry in the genesis of this autoantibody and perhaps of PBC itself.

Early development of primary biliary cirrhosis in female C57BL/6 mice because of poly I:C administration

BACKGROUND

Primary biliary cirrhosis (PBC) is one of the organ-specific autoimmune diseases characterized by destruction of the biliary epithelial cells, cholestasis, liver cirrhosis, and liver failure. With the postulation that induction of the autoimmune process might induce PBC-like cholangitis, here we used polyinosinic polycytidylic acid (poly I:C), an inducer of type-1 interferon (IFN), to generate an autoimmune cholangitis animal model.

METHODS

Female C57BL/6 mice were injected with 5 mg/kg of poly I:C twice a week for 28 consecutive weeks. Liver specimens were collected to evaluate the degree of cell infiltration. Autoantibodies, including antimitochondrial antibody (AMA), were assayed by immunofluorescence, enzyme-linked immunosorbent assay (ELISA) and immunoblotting. IFN-alpha was estimated in the sera by an ELISA method. Poly I:C injection induced IFN-alpha.

RESULTS

Mononuclear cells were detected at the portal areas 8 weeks after the start of poly I:C injection, which progressed up to 16 weeks. Autoantibodies, including AMA, were detected in the sera from all poly I:C-injected mice.

CONCLUSIONS

In conclusion, we show an early development of a PBC-like cholangitis in a genetically susceptible mouse strain because of poly I:C administration. This model would be helpful to study PBC immunopathogenesis and to evaluate the effectiveness of newly developed therapeutic regimens for PBC.

Ikterus und schwere Leberfunktionsst�rung bei der hormonablativen Behandlung des Prostatakarzinoms

Flutamide is an antiandrogen and frequently used for the treatment of prostatic cancer. Severe hepatotoxicity occurs in few patients but may be fatal. We report on two patients with prostatic cancer who received a therapy with flutamide. They showed different degrees of liver damage. One patient recovered completely after withdrawal of Flutamide under medication with steroids. Clinical symptoms and laboratory findings returned to normal within four weeks. Despite immediate withdrawal of Flutamide, the other patient showed a severe course with progressive liver dysfunction and hepatorenal syndrome. He finally died under the clinical picture of fulminant hepatic coma. This case represents the first death associated with flutamide in Germany. The literature concerning the metabolism of flutamide and the published cases of hepatotoxicity of this drug are reviewed.

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.

Ramipril-associated hepatotoxicity

CONTEXT

Angiotensin-converting enzyme inhibitors are prescribed for many cardiovascular and renal diseases. Adverse hepatic events, especially cholestasis, have rarely been reported with captopril, enalapril, lisinopril, and fosinopril. To date, hepatic injury associated with ramipril has not been reported.

OBJECTIVE

To describe 3 patients who developed hepatitis, with or without jaundice, after receiving ramipril.

DESIGN

Medical records and liver biopsies of the 3 patients were reviewed. Clinical, laboratory, and histologic findings were compared with findings in other cases of angiotensin-converting enzyme inhibitor-induced liver injury reported in the literature.

RESULTS

The 3 patients were middle-aged men. In 2 patients, jaundice appeared 4 and 8 weeks after starting ramipril. Bilirubin levels peaked at 15.5 and 5 mg/dL, and alkaline phosphatase values peaked at 957 and 507 U/L. Aminotransferase levels were mildly elevated. Endoscopic retrograde cholangiopancreatography and ultrasonography showed no bile duct obstruction. Liver biopsies from the jaundiced patients were similar, with cholestasis, duct necrosis, and extravasation of bile, ductular proliferation, and portal inflammation. Cholestasis improved in 1 patient 6 weeks after stopping ramipril and was prolonged for 14 months in the other, in whom biliary cirrhosis was present on biopsy. The third patient developed hepatitis without jaundice 3 weeks after starting ramipril; symptoms resolved after stopping the drug. Ramipril-associated liver injury is similar to that seen with other angiotensin-converting enzyme inhibitors, but liver biopsy findings of duct necrosis and extravasation of bile have not been reported previously.

CONCLUSION

Prolonged cholestatic hepatitis and biliary cirrhosis may result from the use of ramipril. Monitoring of liver enzymes is advisable for patients starting on ramipril.

Prolonged cholestasis and ductopenia associated with tenoxicam

Cholestatic liver diseases leading to progressive destruction of intra-hepatic bile ducts and ductopenia encompass multiple etiologies. Pathophysiology and natural history of drug-induced cholangiopathies remain unclear. We report a case of prolonged ductopenia attributed to Tenoxicam (Tilcotil o--a non-steroidal anti-inflammatory drug of the oxicam family) ingested at therapeutic dose. A 36 year-old male patient was admitted for jaundice and Lyell syndrome starting 1 week after the ingestion of Tenoxicam. Liver biopsy showed cholestasis, non-suppurative cholangitis and polymorphous inflammatory infiltrate of the portal tracts (round cells, macrophages an eosinophils). Treatment with ursodesoxycholic acid and cholestyramine was instituted and the patient was asymptomatic 1 year after. Three years later mild biological cholestasis persisted and ductopenia was evidenced on liver biopsy. In this report we found that: (1) The toxicity of tenoxicam was probably mediated by an immunoallergic mechanism (Lyell syndrome and eosinophils on histology); (2) ductopenia was secondary to inflammatory cholangitis. Factors responsible for this chronic evolution are still unknown (genetic predisposition, vascular factors, etc.); and (3) the presence of ductopenia contrasted with the "clinical recovery" of the disease suggesting accessory bile drainage by cholangioles or partial reconstruction of the biliary tree.

A novel autoimmune pancreatitis model in MRL mice treated with polyinosinic:polycytidylic acid

In this study we established a new animal model for exploring the pathogenesis of autoimmune pancreatitis. We have found previously that MRL/Mp-+/+(MRL/+) mice develop pancreatitis spontaneously by an autoimmune mechanism but only when they are more than 34 weeks old. Because this disease might be a model of multi-factorial diseases controlled by genetic and environmental factors, beginning at 6 weeks old, we injected polyinosinic:polycytidylic acid (poly I:C) into MRL/+ mice and in addition, into MRL/Mp mice bearing the Fas deletion mutant gene, lpr (MRL/lpr). Poly I:C induced chronic severe pancreatitis in all the MRL/+ mice and to a lesser extent in the MRL/lpr mice by 18 weeks of age. There was no pancreatitis in control mice of both strains at the same age. Other than chronic pancreatitis, no severe autoimmune diseases were observed in MRL/+ mice. Immunohistochemical examinations revealed predominant infiltration of CD4+ T cells and Mac-2+ activated macrophages in the pancreatic lesions. Splenic expression of the mRNAs for TNF-alpha and IL-10, which is known to suppress the development of pancreatitis, were increased in both strains of mice. These findings suggest that an MRL strain of mice treated with poly I:C might be a good model for developing new approaches to the study of the pathogenesis of autoimmune pancreatitis.

Hepatic sinusoidal obstruction after gemtuzumab ozogamicin (Mylotarg) therapy

Gemtuzumab ozogamicin (Mylotarg) targets leukemia cells expressing the CD33 receptor by means of a monoclonal antibody conjugated to a cytotoxic agent, calicheamicin. Treatment of acute myeloid leukemia (AML) with gemtuzumab ozogamicin may result in liver injury. We reviewed the course of 23 patients who were given gemtuzumab ozogamicin for AML that had relapsed after hematopoietic cell transplantation. Liver toxicity was assessed through physical examination, serum tests, histologic examination, and hepatic venous pressure measurements. Liver injury developed in 11 patients after gemtuzumab ozogamicin administration; it was manifested as weight gain, ascites, and jaundice in 7 patients. Seven patients died with persistent liver dysfunction and either multiorgan failure or sepsis at a median of 40 days after gemtuzumab ozogamicin infusion. Portal pressure measurements were elevated in 2 patients. Results of liver histologic examination in 5 patients showed sinusoidal injury with extensive sinusoidal fibrosis, centrilobular congestion, and hepatocyte necrosis. Six patients experienced AML remission that was sustained for at least 60 days after gemtuzumab ozogamicin infusion. In summary, hepatic sinusoidal liver injury developed after gemtuzumab ozogamicin infusion. Histology showed striking deposition of sinusoidal collagen, suggesting that gemtuzumab ozogamicin targets CD33(+) cells residing in hepatic sinusoids as the mechanism for its hepatic toxicity.

Management of hepatic sinusoidal obstruction syndrome following treatment with gemtuzumab ozogamicin (Mylotarg)

Gemtuzumab ozogamicin (Mylotarg) therapy may cause sinusoidal obstruction syndrome (SOS), the mechanism of which probably involves targeting of CD33+ cells in the sinusoids of the liver, activation of stellate cells, damage to sinusoidal endothelial cells, sinusoidal vasoconstriction, and ischemic hepatocyte necrosis. The clinical manifestations of this liver injury are hepatomegaly, weight gain, ascites, jaundice, and elevation of serum aminotransferase enzymes. An approach to patient management includes being certain that SOS is the correct diagnosis; ensuring that liver blood flow is optimized; and managing the accumulation of fluid in the peritoneal cavity, pleural spaces, and pulmonary interstitium. Currently, there is no specific therapy that is directed at the sinusoidal pathology caused by gemtuzumab ozogamicin. There are, however, several rational therapies that might be tried in patients who exhibit adverse prognostic signs early in the course of SOS. There is also considerable ongoing hepatology research dealing with stellate cell and sinusoidal endothelial cell biology and regulation of sinusoidal blood flow that can be brought to bear on this problem in the future.

Hepatitis C virus-related fibrosing cholestatic hepatitis after cardiac transplantation: is azathioprine a contributory factor?

We report a patient who acquired hepatitis C virus (HCV) infection at cardiac transplantation, developing fibrosing cholestatic hepatitis (FCH) with early liver failure and a fatal outcome. FCH is a recently described clinicopathological entity characterized by a cholestatic pattern of serum liver enzyme abnormalities, a progressive course leading to liver failure, and a pathological picture defined by periportal fibrosis, neutrophilic infiltrates and signs of histological cholestasis. Although it was initially described secondary to hepatitis B virus infection, it has also been recently related to HCV infection. Some histopathological features consistent with azathioprine hepatotoxicity like cholestasis, perisinusoidal fibrosis, veno-subocclusive lesions and nodular regenerative hyperplasia were also observed in this case. Therefore, a direct cytopathic effect of HCV and the concurrent pathogenic role of azathioprine hepatotoxicity may be involved in the development of this complication of transplantation.

Acute carbon tetrachloride feeding selectively damages large, but not small, cholangiocytes from normal rat liver

The aim of this study was to develop a model of selective duct damage restricted to hormone-responsive segments corresponding to the ducts damaged in primary biliary cirrhosis (PBC). Carbon tetrachloride (CCl4) was fed by gavage to rats, and 2, 7, 14, and 28 days later, small and large cholangiocytes were isolated. Apoptosis was determined in situ by morphology and in purified cholangiocytes by assessment of nuclear fragmentation by 4, 6-diamidino-2-phenylindole (DAPI) staining. Cholangiocyte proliferation was evaluated in situ by morphometry of liver sections stained for cytokeratin-19 (CK-19) and by proliferating cellular nuclear antigen (PCNA) staining in liver sections and in purified cholangiocytes by PCNA gene expression. Ductal secretion was assessed by measurement of secretin receptor (SR) gene expression and secretin-induced cyclic adenosine 3',5'-monophosphate (cAMP) synthesis and secretin-induced choleresis. Two days after CCl4 administration, there was an increased number of small ducts, but a reduction of large ducts. Apoptosis, observed only in large ducts, was associated with decreased DNA synthesis and ductal secretion. Conversely, small cholangiocytes expressed de novo the SR gene and secretin-stimulated cAMP synthesis 2 days after CCl4 treatment. Proliferation of large cholangiocytes was delayed until 7 days, which was associated with a transient increase in ductal secretion in vivo. CCl4 effects on cholangiocytes were reversed by day 28. CCl4 treatment causes a decrease in large duct mass as a result of a higher rate of apoptosis and absence of initial proliferation in large cholangiocytes. These processes were concomitant with a decrease of ductal secretion in large cholangiocytes. Small cholangiocytes appear resistant to CCl4-induced apoptosis, and proliferate and transiently compensate for loss of proliferative and secretory activity of large cholangiocytes.

The effect of endothelin and its antagonist Bosentan on hemodynamics and microvascular exchange in cirrhotic rat liver

BACKGROUND/AIMS

To characterize the effects of endothelin-1 and of Bosentan, a mixed endothelin antagonist, on hepatic hemodynamics in cirrhotic animals in vivo and on hepatic microvascular exchange in the perfused rat liver.

METHODS

Biliary cirrhosis was induced by bile duct ligation, and micronodular cirrhosis by chronic exposure to phenobarbital/CCl4 in male rats. Hepatic hemodynamics were studied under basal conditions and after administration of Bosentan (3-30 mg/kg) by the microsphere technique. Microvascular exchange was assessed in the in situ perfused rat liver by the multiple indicator dilution technique.

RESULTS

Bosentan lowered portal pressure in a dose-dependent fashion; at the highest dose tested, this decrease averaged -29+/-11 and -26+/-8% in biliary and micronodular cirrhosis, respectively (p<0.01). This was achieved mainly via a marked decrease in hepatic arterial flow. In the perfused liver, endothelin-1 induced a dose-dependent vasoconstriction; up to 10(-9) mol/l; this was not associated with any effect on viability. At this dose, endothelin-1 markedly decreased extravascular albumin space in both controls and micronodular cirrhosis; this could be antagonized by Bosentan 10(-5) mol/l.

CONCLUSIONS

Endothelin-1 affects hepatic microvascular exchange, presumably by a direct effect on hepatic sinusoidal endothelial cells. A mixed endothelin antagonist lowers portal pressure in vivo, presumably by acting on hepatic stellate cells, and counteracts the microvascular effects of endothelin-1 in vitro. These properties could prove useful in treatment of portal hypertension.

Effects of Ursodeoxycholate and cholate feeding on liver disease in FVB mice with a disrupted mdr2 P-glycoprotein gene

BACKGROUND & AIMS

The mouse mdr2 gene encodes a P-glycoprotein expressed in the hepatocanalicular membrane. Inactivation of this gene causes lack of biliary phospholipid and cholesterol secretion and non-suppurative cholangitis. The aim of this study was to investigate the role of bile salt hydrophobicity in induction of liver pathology in mdr2 (-/-) mice.

METHODS

Mice (+/+) wild type or (-/-) knockout for the mdr2 gene were fed with either purified control diet or this diet supplemented with cholate (0.1%) or ursodeoxycholate (0.5%) for 3, 6, or 22 weeks after weaning. Liver histology was semiquantitatively scored.

RESULTS

Each mouse fed bile acid became the major constituent of the bile salt pool. The cholate diet during 22 weeks induced only very mild liver pathology in (+/+) mice. By contrast, lever histology had already deteriorated after 3 weeks in the (-/-) mice and caused pronounced inflammatory nonsuppurative cholangitis and fibrosis in the 75% of mice that survived. Dietary ursodeoxycholate had no effect on histology in (+/+) mice but improved liver pathology significantly in (-/-) mice compared with purified control diet; the decrease of ductular proliferation and portal inflammation was most prominent after 22 weeks.

CONCLUSIONS

The cholangiolitis and its sequelae in the mdr2 knockout mice depend on bile salt hydrophobicity.

An experimental animal model of primary biliary cirrhosis induced by lipopolysaccharide and pyruvate dehydrogenase

Previously, we found that the antibody titer belonging to the IgM class produced against the bacterial antigen (Lipid A) was elevated in sera from patients with primary biliary cirrhosis (PBC). On the other hand, the targets of the mitochondrial autoantibodies have been identified as being components of the pyruvate dehydrogenase complex (PDH). We tried to produce an experimental animal model for the investigation of the association between hepatic bile duct alteration and bacterial infection. Female C57/BL mice, aged 4 weeks, were used. An emulsion consisting of lipopolysaccharide (LPS) derived from Salmonella minnesota Re595, PDH, and Freund's adjuvant was prepared. This emulsion was subcutaneously injected on the back of the mice. The mice were divided into a control group (n = 5), a group given LPS (n = 5) alone, those given PDH alone (n = 5), and those given a combination of LPS and PDH (n = 5). The antigens were administered once a week every week with a maximum duration of administration of 24 weeks. The serum levels of IgM after 24 weeks in the LPS and LPS + PDH groups were 2.5 times higher than those in the control and PDH groups. The light microscopic findings of liver tissue revealed that infiltration of lymphocytes and plasma cells in the portal area, proliferation of the bile duct, and degeneration of the biliary epithelial cells were more prominent in the PDH and LPS + PDH groups than in the other groups. These results indicate that our animal model may be useful in investing the pathogenesis of PBC.

Primary biliary cirrhosis induced by interferon-alpha therapy for hepatitis C virus infection

Interferon-alpha is known to exacerbate and in some cases induce a variety of autoimmune disorders. In this report we describe the onset of primary biliary cirrhosis in a 55-year-old woman without evidence of preexisting autoimmune diseases receiving recombinant interferon-alpha 2a for chronic active hepatitis C. Shortly after discontinuing interferon therapy, alkaline phosphatase levels started to rise up to three times the normal range. Anti-mitochondrial antibodies were found to be positive at a high titer, and liver biopsy showed a picture of chronic active hepatitis along with primary biliary cirrhosis features (overlap syndrome). Primary biliary cirrhosis should be considered in the differential diagnosis in any patient treated with interferon-alpha with unexplained elevation of serum alkaline phosphatase.

[Experimental model of induction in the rat of rapidly developing biliary cirrhosis in peripartal nodular cirrhosis]

The treatment with CCl4 and progesterone subsequent the common biliary duct ligature induced, in the rat, after 4-5 weeks, a cirrhotic picture characterized by an early and strong biliary epithelium proliferation followed by a perilobular fibrosis with a concentric sclerosis as in true perilobular cirrhosis.

A case of drug-induced ductopenia resulting in fatal biliary cirrhosis

A 50-year-old woman suffered from a diffuse skin rash, high fever and jaundice immediately after a second injection of glutathion and Stronger Neo-minophagen C which contains glycyrrhizin. Liver biopsy performed 11 months after the onset showed mild spotty hepatocyte necrosis, marked cholestasis in parenchyma, and some lymphocyte infiltration in the portal area. Interlobular bile ducts had undergone vacuolar degeneration or were absent in some portal tracts. In her hospital course, unremitting jaundice persisted and biliary cirrhosis developed with signs of portal hypertension; she died from liver failure 26 months after the onset. A liver specimen at her death revealed that most of the interlobular bile ducts had vanished. Based on the clinical course and pathology, drug-induced ductopenia, possibly due to an adverse reaction to glycyrrhizin, is the most likely diagnosis. While drug-related biliary cirrhosis is rarely fatal, this case presented an unusually rapid course of fatal biliary cirrhosis.

Canalicular bile flow and bile salt secretion are maintained in rats with liver cirrhosis. Further evidence for the intact cell hypothesis

Different aspects of biliary physiology were studied in rat model of liver cirrhosis induced by CCl4/phenobarbitone. We measured bile flow, bile salt secretion, biliary secretion pressure and bile-to-plasma ratios of inert solutes under basal conditions and during infusion of taurocholate (0.4 and 0.8 mumol.min-1.100 g body wt.-1) in 11 cirrhotic and 10 control male Sprague-Dawley rats. Bile flow and biliary bile salt secretion did not differ between the two groups. Analyzing the relationship between bile salt secretion and bile flow, however, we found an increased slope (P less than 0.02) in the cirrhotic animals, suggesting a higher apparent osmotic activity of the bile salts secreted. Maximal biliary secretion pressure was maintained in cirrhotic animals (22.5 +/- 2.5 vs. 25.0 +/- 2.9 cmH2O) in the absence of exogenous bile salt. During taurocholate infusion it decreased to a lesser extent (P less than 0.001) in cirrhotic animals (13.5 +/- 3.4 vs. 19.3 +/- 3.8 cmH2O). Bile-to-plasma ratios of [3H]sucrose and [14C]ferrocyanide were markedly increased in cirrhotic rats. Biliary [14C]erythritol clearance was equal to bile flow in both groups. In the cirrhotic group, the [3H]sucrose bile/plasma ratio was positively correlated with spleen weight (r = 0.744, P less than 0.01), serum concentration of alkaline phosphatase (r = 0.583, P less than 0.05) and basal maximum biliary secretion pressure (r = 0.801, P less than 0.001). We conclude that chronic portal hypertension is associated with increased permeability of the blood/bile barrier. Nevertheless, bile flow and bile salt secretion are maintained in cirrhotic rats, giving support to the intact cell hypothesis for this important hepatocellular function.

Sclerosing cholangitis from intraarterial floxuridine

The development of biliary strictures simulating sclerosing cholangitis is now well-known. We report a patient undergoing intraarterial chemotherapy for metastatic colon cancer of the liver in whom segmental intrahepatic biliary strictures occurred remote from known metastases. The patient remains alive 3-4 years after documented liver metastases with severe progressive portal hypertension, hypersplenism, and fat malabsorption. A table of cases so far reported is given.

Drug-induced hepatotoxicity

Drug-induced injury to the liver can mimic any form of acute or chronic liver disease. Acute injury to the liver frequently is due to the action of cytochrome P450, which breaks down drugs into electrophiles or free radicals; these reactive metabolites can covalently bind to protein and unsaturated fatty acids or induce lipid peroxidation, respectively. These events may impair vital functions of the cell, such as maintenance of calcium homeostasis, leading to death; or hypothetically they may elicit a hypersensitivity reaction directed mainly at the liver. Glutathione and tocopherol play critical roles in cellular defense. Cholestatic disease caused by drugs results from a selective disturbance in bile secretion. Agents such as estrogens, chlorpromazine, and monohydroxy bile acids alter the chemical and physical properties of membranes, leading to impaired activity of carriers and pumps for bile acids and electrolytes. Certain drugs produce chronic liver disease that is pathologically identical to chronic active hepatitis, biliary cirrhosis, or alcoholic liver disease.

Biliary cirrhosis and tumors induced by chronic administration of thiobenzamide to rats

Thiobenzamide (TB), a thiono-containing compound, was administered for 38 weeks to female Sprague-Dawley rats at a dose of 1 g/kg standard diet; the resulting liver pathology was followed up to 8 months after withdrawal of the compound from the diet. TB administration induced the appearance of biliary cirrhosis. In the first weeks of intoxication the progressive distortion of the liver architecture was mainly due to significant proliferation of the bile ductules. Later, the liver assumed a macronodular appearance. In addition to regenerative and degenerative changes of the hepatocytes, preneoplastic lesions were also detected, and some enzymic markers of the mixed-function monooxygenase system were decreased. Cholangiofibrotic areas were evident, and many biliary tubules within them showed mucous metaplasia. At the end of the intoxication period, as well as 4 months after drug suspension, large portions of the liver or entire lobes were substituted by connective tissue surrounding nests of bile ductules and atrophied hepatocellular nodules. Four months later, in the virtual absence of cirrhotic changes, each animal harboured one or more tumors (mainly cholangiomas).

Studies of alpha-napthylisothiocyanate-induced hepatic disturbance

In order to clarify the mechanism of alpha-naphthylisothiocyanate (ANIT) induced cholestasis in rats, a few hepatic changes seen after administration of ANIT 80 mg/kg body weight were examined in relation to time. To clarify changes in the bile production system and bile flow, the concentrations of bile acid and bicarbonate, as well as of sodium in the bile, were measured after infusion of secretin and taurocholic acid. The canalicular bile flow was estimated by measuring the biliary clearance of erythritol-C14. To assess hepatocellular injury, the levels of cytochrome P-450 in the microsome of hepatocytes and protein synthesis in the liver were estimated. It seems that ANIT is activated in the drug metabolising system through cytochrome P-450 in the liver, and significant changes are produced in both the bile acid metabolism and its transport system. Bile acid-independent bile flow in the canaliculus was inhibited, too. Hence, both the bile ductules and the bile ducts are functionally and histologically disturbed.

Prolonged cholestasis and progressive hepatic fibrosis following imipramine therapy

This report describes a middle-aged female who received imipramine for 7 days, developed severe cholestatic jaundice with features similar to primary biliary cirrhosis, and then improved clinically over the next 12 mo. Biochemical and histologic abnormalities persisted over a 14-yr period of follow-up, though subsequent administration of haloperidol may have influenced the long-term course. High levels of circulating immune complexes were also found 14 yr later, which raises questions about the relationship of primary biliary cirrhosis to drug-induced liver injury. A review of the literature on imipramine- and phenothiazine-related hepatic injuries reveals multiple similarities, and this case provides further evidence for a common hepatic reaction to the two drugs.

Primary biliary cirrhosis after long-term practolol administration

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