Adoptive transfer of CD8(+) T cells from transforming growth factor beta receptor type II (dominant negative form) induces autoimmune cholangitis in mice

We recently reported that mice with a T cell-restricted expression of a dominant negative form of transforming growth factor beta receptor type II (dnTGFbetaRII) spontaneously develop autoimmune cholangitis that resembles human primary biliary cirrhosis (PBC), including antimitochondrial antibodies (AMAs) and extensive portal CD4(+) and CD8(+) lymphocytic infiltrates. On the basis of these data, we performed a series of experiments to determine whether the pathology was secondary to direct dnTGFbetaRII disruption of the liver and/or alternatively the appearance of autoreactive T cells. First, using dnTGFbetaRIIRag1(-/-) mice, we noted a normal hepatic and biliary structure. Hence, we performed a rigorous series of adoptive transfer studies, transferring Ly5.1(+) unfractionated spleen cell CD4(+) or CD8(+) T cells from dnTGFbetaRII mice into B6/Rag(-/-) (Ly 5.2) recipients. In unmanipulated dnTGFbetaRII mice, there was a marked increase in CD4(+) and CD8(+) T cell biliary infiltrates with AMA. Indeed, B6/Rag(-/-) recipients of dnTGFbetaRII unfractionated cells develop features of liver disease similar to PBC, suggesting that splenic loss of self-tolerance alone is sufficient to cause disease in this model and therefore that there is no specific abnormality in the biliary targets required for appearance of disease. More importantly, adoptive transfer of CD8(+) but not CD4(+) T cells into B6/Rag(-/-) mice led to liver histopathology remarkably similar to PBC, emphasizing a prominent role for CD8 T cell-mediated pathogenesis. In contrast, B6/Rag(-/-) recipients of CD4(+) T cells from dnTGFbetaRII mice predominantly developed inflammatory bowel disease associated with higher levels of serum interferon gamma and tumor necrosis factor alpha.

CONCLUSION

These data suggest that in this model of PBC, autoreactive CD8(+) cells destroy bile ducts.

Natural killer T cells exacerbate liver injury in a transforming growth factor beta receptor II dominant-negative mouse model of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an organ-specific autoimmune liver disease characterized by the presence of antimitochondrial antibodies and the destruction of small intrahepatic bile ducts with portal inflammation. In previous studies, we reported that both CD1d expression and the frequency of CD1d-restricted natural killer T (NKT) cells were increased in the livers of patients with PBC. To define a specific role of CD1d-restricted NKT cells in the pathogenesis of PBC, particularly early events, we investigated the function of hepatic CD1d-restricted NKT cells in our transforming growth factor beta (TGF-beta) receptor II dominant-negative (dnTGFbetaRII) mouse model of PBC. We generated CD1d(-/-) and CD1d(+/-) dnTGFbetaRII mice and performed a comparative study of liver immunopathology. We report herein that these dnTGFbetaRII mice demonstrate a massive increase of hyperactive CD1d-restricted NKT cells within the hepatic tissues. CD1d(-/-)dnTGFbetaRII mice, which lack CD1d-restricted CD1d-restricted NKT cells, exhibit significantly decreased hepatic lymphoid cell infiltrates and milder cholangitis compared with CD1d(+/-)dnTGFbetaRII mice. Interestingly, there was a significant increase in the production of interferon-gamma in hepatic CD1d-restricted NKT cells activated by alpha-galactosylceramide in young but not older dnTGFbetaRII mice, suggesting an age-dependent role of CD1d-restricted NKT cells.

CONCLUSION

These data demonstrate that CD1d-restricted NKT cells in dnTGFbetaRII mice are a critical factor in liver injury.

Generation of functionally distinct B lymphocytes from common myeloid progenitors

Current models of adult haematopoiesis propose that haematopoietic stem cells (HSCs) differentiate into common lymphoid (CLP) and common myeloid (CMP) progenitors and establish an early separation between myeloid and lymphoid lineages. Nevertheless, the developmental potential of CMP-associated B cells suggests the existence of alternate pathways for B lymphopoesis. The aim of this study was to compare the developmental and functional properties of CMP- and CLP-derived B cells. While both populations matured through pro-B cell and transitional B cell intermediates in the bone marrow and spleen, respectively, following transfer into irradiated mice, mature CMP- and CLP-derived B cells exhibit distinct functional responses. Specifically, CMP-derived B cells did not respond to mitogenic stimulation to the same degree as their CLP-derived counterparts and secrete lower levels of IgM and the inflammatory cytokines such as interleukin (IL)-6 and IL-10. Together, these data suggest the existence of multiple pathways for generating functionally distinct B cells from bone marrow precursors.

The role of CD11c(+) hepatic dendritic cells in the induction of innate immune responses

The role of the liver in the initiation and maintenance of tolerance is a critical immune function that involves multiple lineages of immune cells. Included within these populations are liver dendritic cells (DCs). Although there has been significant work on the phenotypic and functional roles of splenic and bone marrow dendritic cells, as well as their subsets, comparable studies in liver have often been difficult. To address this issue we have isolated, from C57BL/6 mice, relatively pure populations of DCs and compared phenotype and function to the data from spleen using flow cytometry, cell sorter assisted purification and culture, morphology by cytospin and May-Giemsa staining, cell cycle progression, antigen uptake, cytokine production and allo-activation potential. natural killer (NK)1.1(-)CD11c(+) liver DC subsets (conventional DCs, T cell receptor (TcR)beta(-)NK1.1(-)CD11c(+)B220(-) and plasmacytoid DCs, TcRbeta(-)NK1.1(-)CD11c(+)B220(+)) efficiently endocytose dextran and produce significant levels of tumour necrosis factor (TNF)-alpha, interleukin (IL)-6 and IL-12 p40 in response to Toll-like receptor (TLR) ligands, with responses higher than splenic DCs. There is also a differential capability of hepatic DCs to respond to innate signals. Indeed, CD11c(+) hepatic DCs have a greater capacity to respond to innate stimulation but are less capable of inducing CpG activated-allogeneic T cells. These data suggest that hepatic dendritic cells function as a critical bridge between innate and adaptive immunity and are capable of inducing stronger innate responses with a lower capacity for allo-stimulation than splenic dendritic cells. These properties of liver dendritic cells contribute to their unique role in the induction of tolerance.

The role of CD11c(+) hepatic dendritic cells in the induction of innate immune responses

The role of the liver in the initiation and maintenance of tolerance is a critical immune function that involves multiple lineages of immune cells. Included within these populations are liver dendritic cells (DCs). Although there has been significant work on the phenotypic and functional roles of splenic and bone marrow dendritic cells, as well as their subsets, comparable studies in liver have often been difficult. To address this issue we have isolated, from C57BL/6 mice, relatively pure populations of DCs and compared phenotype and function to the data from spleen using flow cytometry, cell sorter assisted purification and culture, morphology by cytospin and May-Giemsa staining, cell cycle progression, antigen uptake, cytokine production and allo-activation potential. natural killer (NK)1.1(-)CD11c(+) liver DC subsets (conventional DCs, T cell receptor (TcR)beta(-)NK1.1(-)CD11c(+)B220(-) and plasmacytoid DCs, TcRbeta(-)NK1.1(-)CD11c(+)B220(+)) efficiently endocytose dextran and produce significant levels of tumour necrosis factor (TNF)-alpha, interleukin (IL)-6 and IL-12 p40 in response to Toll-like receptor (TLR) ligands, with responses higher than splenic DCs. There is also a differential capability of hepatic DCs to respond to innate signals. Indeed, CD11c(+) hepatic DCs have a greater capacity to respond to innate stimulation but are less capable of inducing CpG activated-allogeneic T cells. These data suggest that hepatic dendritic cells function as a critical bridge between innate and adaptive immunity and are capable of inducing stronger innate responses with a lower capacity for allo-stimulation than splenic dendritic cells. These properties of liver dendritic cells contribute to their unique role in the induction of tolerance.

Autoimmune cholangitis in NOD.c3c4 mice is associated with cholangiocyte-specific Fas antigen deficiency

A major handicap in understanding the pathogenesis of autoimmune cholangitis has been the absence of an informative mouse model. Recently, autoimmune cholangitis, with several features similar to PBC, has been described in NOD.c3c4 mice, including anti-mitochondrial antibodies, lymphocytic portal tract infiltrates, biliary destruction and the adoptive transfer of disease to naïve recipients using liver-derived lymphocytes. A unique feature, and a characteristic quite distinct from human PBC, is the presence of bile cyst formation. We have addressed the issue of cysts in NOD.c3c4 mice by performing comprehensive microarray analysis using cholangiocytes from NOD.c3c4 mice compared to NOD controls. Several key differences in gene expression were noted in NOD.c3c4 cholangiocytes. First, there was consistent impairment in the expression of Fas antigen (CD95). Second, cholangiocytes were PCNA positive but TUNEL negative, suggesting an absence of apoptosis despite abnormal proliferation. In conclusion, we propose that autoimmune cholangitis develops in NOD.c3c4 mice secondary to impaired biliary cell apoptosis with exposure of mitochondrial antigens, loss of tolerance and subsequent development of multi-lineage anti-mitochondrial responses.

Mapping of a disease susceptibility locus in the HLA region for Primary Biliary Cirrhosis in Japan

AIMS

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic disease of unknown pathogenesis. However, several reports have demonstrated the involvement of genetic backgrounds in this syndrome. The aim of this study is to examine the genetic disequilibrium in the HLA region in Japanese patients using six microsatellite markers.

METHODS

Genomic DNAs were obtained from 73 patients with PBC (patient cohort) and 186 healthy volunteers (control cohort). Genetic polymorphisms at six microsatellite markers (D6S1568, DQ.CAR, D6S273, TNF-d, C1-2-A, C3-2-11) were determined using fluorescence-labeled polymerase chain reaction (PCR) genetic analyzer. Allele frequencies were estimated by direct counting and the genotypic differentiation test was performed by the Markov chain method using Genepop software.

RESULTS

Among these six microsatellite markers, four markers in the patients significantly (P < 0.05) deviated from the Hardy-Weinberg equilibrium: DQ.CAR (P = 0.0278), D6S273 (P = 0.0168), TNF-d (P = 0.0089) and C1-2-A (P = 0.0005). Genotypic differentiation test between the patients and controls demonstrated that DQ.CAR (P = 0.0111), TNF-d (P = 0.0051) and C1-2-A (P = 0.0371) were significant. Finally, allelic association test revealed before correction for multiple testing demonstrated allele125 of TNF-d (P = 0.00065, Pc = 0.0052) and allele246 of C1-2-A (P = 0.0026 Pc = 0.033) had significant association after Bonferroni's correction.

CONCLUSION

Disequilibrium mapping using microsatellite markers was a useful method to narrow a disease susceptibility locus. The possible susceptibility gene in the HLA region is thought to be localized around or in the TNF gene. Further studies seem feasible using more closely distributed microsatellite markers or single nucleotide polymorphisms (SNPs) to narrow the susceptibility locus in PBC in Japanese populations.

CD8 T cells Play a Critical Role in Primary Biliary Cirrhosis of dnTGFbetaRII Mice (130.28)

Human primary biliary cirrhosis (PBC) is characterized serologically by antimitochondrial antibodies (AMA) and histologically by an intense T cell portal infiltrate that destroys bile ducts. We have taken advantage of the PBC-like disease exhibited by dnTGFbetaRII mice and focused our attention on the liver T cell infiltrate. One major advantage to this animal model is the ability to perform cell transfer. Therefore to address the issue of T cell effector mechanisms, we isolated dnTGFbetaRII splenic CD4+ or CD8+ T cells and transferred these populations into Rag1 k/o mice. Importantly, the CD8+ T cells transfer group demonstrated a significant expansion of T cells and the presence of portal tract infiltrates in recipient mice. In contrast, although CD4+ T cells did expand in the recipient group, they did not home or focus within the portal tracts. Our results demonstrate that the impaired TGFbeta signaling pathway in these mice leads to a CD8 cytotoxic T cell population that plays a critical role in biliary cell damage. These data have implications not only for understanding TGFbeta signaling and autoimmunity in these mice, but also in developing appropriate focused immunotherapy to prevent biliary damage.

Invariant NKT cells exacerbate liver injury in a TGF-β receptor II dominant-negative mouse model of primary biliary cirrhosis (130.24)

Primary biliary cirrhosis (PBC) is an organ-specific autoimmune liver disease characterized by the presence of anti-mitochondrial antibodies (AMA) and the destruction of small intrahepatic bile ducts with portal inflammation. In previous studies, we reported that both CD1d expression and the frequency of invariant natural killer T (iNKT) cells were increased in the liver of patients with PBC. To define a specific role of iNKT cells in the pathogenesis of PBC, particularly early events, we investigated the function of hepatic iNKT cells in our TGF-β receptor II dominant-negative (dnTGFβRII) mouse model of PBC. We report here that these dnTGFβRII mice demonstrate a massive increase of hyperactive iNKT cells within the hepatic tissues. We generated CD1d−/−and CD1d+/− dnTGFβRII mice and performed a comparative study of liver immunopathology, demonstrating that the CD1d−/−dnTGFβRII mice, lacking iNKT cells, exhibit significantly decreased hepatic lymphoid cell infiltrates and milder cholangitis compared to CD1d+/−dnTGFβRII mice. Interestingly, there was a significant increase in the production of IFN-γ in hepatic iNKT cells activated by α-galactosylceramide (α-GalCer) in young but not older dnTGFβRII mice, suggested an age dependent role of iNKT cells. These data demonstrate that iNKT cells in dnTGFβRII mice are a critical factor in liver injury.

CD11c+ hepatic dendritic cells induce strong innate immune response with reduced capacity to activate allogeneic T cells (128.14)

Splenic and bone marrow dendritic cells (DCs) and their subsets have been shown in multiple studies to play a critical role in maintaining tolerance and also in select differentiation of pathways responsive to infectious agents. Comparable studies in the liver have been lacking primarily due to difficulty in isolation and contradictory data. We have taken advantage of our ability to identify and isolate relatively pure DC populations and have compared the phenotype and function of select subsets of DCs in liver compared to spleen in C57BL/6 mice. Importantly, freshly isolated NK1.1−CD11c+ liver DC subsets (conventional and plasmacytoid DCs) can efficiently endocytose dextran as well as induce significant levels of TNF-α, IL-6 and IL-12 p40 in response to toll-like receptor ligand stimulation. These responses are higher than comparable studies of isolated splenic DCs from the same animals. In addition, there is a relatively higher frequency of pDC populations in liver. Our results suggest that hepatic DCs has differential capability in response to innate signals and that in fact CD11c+ hepatic DCs have a greater capacity to respond to innate stimulation but less capable of inducing CpG activated-allogeneic T cells. Our data emphasize not only the critical difference in hepatic DC subsets, but also highlight the need to study individual DC subsets in understanding the modulation of the immune response in the liver.

Amniotic epithelial cell-derived cholangiocytes in experimental cholestatic ductal hyperplasia

AIM

Bile duct paucity, ductopenia, is a feature of end-stage chronic cholangiopathies such as primary biliary cirrhosis. The limited proliferative ability of cholangiocytes after specific injury is thought to be the principal cause of ductopenia, although the detailed mechanisms involved are unclear. It has been reported that human amniotic epithelial cells (AEC) express differentiation markers of hepatic parenchymal cells, suggesting a resemblance of AEC to hepatic progenitor cells. The aim of the present study was to develop a mouse model of experimental cholestasis to assess the capability of mouse AEC to trans-differentiate into cholangiocytes.

METHODS

Enhanced green fluorescent protein (EGFP)-transgenic C57BL/6 pregnant female mice were used as the source of AEC. At 11.5 gestational days, 1 x 10(5) AEC were isolated from EGFP-transgenic mouse embryos and transferred into C57BL/6 mice. Chronic cholestasis was induced by 0.1%alpha-naphthylisothiocyanate (ANIT) feeding immediately after the transfer of AEC. The proliferation of cholangiocytes in the livers was assessed morphologically and immunohistochemically (cytokeratin 7; CK7). The proliferative activity was also quantified immunohistochemically by proliferating cell nuclear antigen (PCNA) protein expression. EGFP of transferred AEC was confirmed by fluorescent laser microscopy and immunofluorescent staining for EGFP. Also, Notch2 and Hes1 expression was evaluated to examine the roles of the differentiation markers in this process.

RESULTS

Marked proliferation of cholangiocytes was observed in ANIT-fed mice confirmed by quantitative CK7 (3-4 fold vs control) and PCNA (11-20 fold vs control) staining. EGFP and CK7 double positive cells in interlobular bile ducts were confirmed in the livers of AEC-transferred recipients. Positivity of EGFP was further confirmed by the immunofluorescent staining for EGFP. Moreover, both Notch2 and Hes1 expression was confirmed in the proliferative bile duct in this model.

CONCLUSIONS

Significant ductular proliferation was observed in ANIT-fed mice. EGFP-positive cholangiocytes were confirmed in this chronic cholestasis model. AEC transfer was able to contribute to the repopulating of proliferating cholangiocytes under cholestasis, suggesting AEC might be a candidate cell source for stem cell administration in future clinical applications to re-model interlobular bile ducts.

Primary biliary cirrhosis: what we know and what we want to know about human PBC and spontaneous PBC mouse models

Human autoimmune cholangiopathy comprises several intractable liver diseases that ultimately lead to hepatic failure. Primary biliary cirrhosis (PBC), allograft rejection, graft versus host diseases, and, possibly, primary sclerosing cholangitis are representative of immune-mediated cholangiopathies. Among them, PBC is the best-investigated human autoimmune cholangiopathy. The immunological approach to PBC has provided much critical information regarding its pathogenesis. The breakdown of self-tolerance in both B cells and T cells toward E2 components of the pyruvate dehydrogenase complex is evident. However, a number of questions regarding its etiology are unclear, in particular, the mechanisms involved in the selectivity of cholangiocyte destruction. In this brief review, we discuss what we know and we do not know regarding the pathogenesis of PBC.

AMA production in primary biliary cirrhosis is promoted by the TLR9 ligand CpG and suppressed by potassium channel blockers

We previously reported that peripheral blood mononuclear cells (PBMCs) from patients with primary biliary cirrhosis (PBC) produce significantly higher levels of polyclonal IgM than controls after exposure to CpG. Furthermore, the prevalence and unusually high levels of antimitochondrial antibodies (AMAs) in patients with PBC suggest a profound loss ofB cell tolerance. We have addressed the issue of whether CpG will promote the production ofAMAs and whether new experimental agents that inhibit the lymphocyte potassium channels Kv1.3 and KCa3.1 can suppress CpG-mediated B cell activation and AMA production. PBMCs were stimulated with and without CpG and were subsequently analyzed for phenotype, including expression of TLR9, CD86, and KCa3.1 concurrent with measurements of AMA and responses to a control antigen, tetanus toxoid, in supernatants. Additionally, K+ channel expression on B cells from PBC patients and controls was studied using whole-cell patch-clamp technology. In patients with PBC, CpG induces secretion of AMAs in PBMCs andalso up-regulates B cell expression of TLR9, CD86, and KCa3.1. Additionally, K+ channel blockers suppress secretion of AMA without a reduction of CpG-B-enhanced IgM production. Furthermore, there is diminished up-regulation of TLR9 and CD86 without affecting proliferation of B cells, B cell apoptosis, or viability.

CONCLUSION

These data suggest that the hyperresponsiveness of B cells in PBC accelerates B cell-mediated autoimmunity.

IL-2 receptor alpha(-/-) mice and the development of primary biliary cirrhosis

Recently, we identified a child born with a genetic deficiency of IL-2 receptor alpha (IL-2Ralpha, CD25) expression who had several clinical manifestations of primary biliary cirrhosis (PBC). In addition, there has been suggestive evidence in both patients with PBC and their first-degree relatives that a deficiency of regulatory T cells (Tregs) is an integral component for susceptibility to PBC. Based on these observations, we generated IL-2Ralpha/CD25 deficient (IL-2Ralpha(-/-)) mice and wild-type littermate controls and followed them longitudinally for the natural history of liver immunopathology and appearance of antimitochondrial antibodies (AMAs). The analyses included immunohistochemical staining of liver and portal tract infiltrates as well as FACS profiles of lymphoid subpopulations in liver and spleen. In addition, serum cytokine profiles were quantitated. Importantly, IL-2Ralpha(-/-), but not littermate controls, develop portal inflammation and biliary ductular damage similar to human patients with PBC. CD4(+) and CD8(+) T cells predominate among portal cell infiltrates and sera reflect a Th1 cytokine bias with increased levels of IFN-gamma, TNF-alpha, IL-2 and IL-12p40. Of importance is the finding that the IL-2Ralpha(-/-) mice not only develop significantly increased serum levels of IgG and IgA, but they also develop AMAs with specificity for PDC-E2, which maps to the inner lipoyl domain of the autoantigen, all characteristics which are hallmarks of human PBC. In conclusion, the IL-2Ralpha(-/-) mice should facilitate studies of the early events in PBC and especially the tantalizing connection between Treg deficiency and autoimmunity specifically directed to mitochondrially located PDC-E2 and subsequent biliary ductular cell damage.

B cells and autoimmune liver diseases

Autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are the three major autoimmune diseases affecting the liver. They are all characterized by the presence of a variety of autoantibodies, some of which are found in all three diseases, whereas others are restricted to one or two of them or are even specific for the particular disease. In this review we will first provide details of the serological features of these three autoimmune diseases that target the liver. In addition, we will highlight the possible pathogenic roles of autoreactive B cells, focusing on their immunological functions as autoantibody producing cells and as antigen-presenting cells for T cell priming. As well, we will describe the contribution of toll-like receptor (TLR) signaling to the activation of autoimmune B cells and the putative role of defects in regulatory T cell function in the development of autoimmune liver diseases.

Lack of evidence that bone marrow cells contribute to cholangiocyte repopulation during experimental cholestatic ductal hyperplasia

BACKGROUND

Ductopenia is observed in end-stage human cholestatic diseases. The limited capability of cholangiocytes for proliferation is suggested to be the principal reason. Recently, bone marrow cells (BMCs) have been reported to behave as hepatic stem cells; however, their capability to differentiate into cholangiocytes in cholestasis remains unclear.

METHODS

Normal mice were lethally irradiated to suppress the proliferation of self-BMCs; thereafter, the BMCs from enhanced green fluorescent protein (EGFP)-transgenic mice were transferred to recipients. Chronic cholestasis was induced by 0.1%alpha-naphtylisothiocyanate (ANIT) feeding. The proliferation of cholangiocytes and oval cells was assessed morphologically and immunohistchemically (cytokeratin-7 (CK-7), A6). Proliferative activity (proliferating cell nuclear antigen (PCNA) protein expression), hepatic growth factor (HGF) receptor (c-Met), stem cell factor receptor (c-kit), Notch2 and Hes1 expression were also evaluated.

RESULTS

Marked cholangiocyte proliferation was observed in ANIT-fed mice. However, no EGFP/CK-7 double positive cells were identified in any of the liver specimens after BMCs transfer (Tx). In hepatic parenchyma, there were scattered EGFP-positive cells, although none of them were positive for CK-7.

CONCLUSIONS

In spite of the significant ductular proliferations after ANIT feeding, no EGFP-positive cholangiocytes were confirmed by any other means in this chronic cholestasis model. Thus, different from hepatocytes, BMCs Tx seems not to contribute to the differentiation of cholangiocytes. Future studies are feasible to clarify the origin of proliferative cholangiocytes observed in this chronic cholestatic ductular hyperplasia model.

Liver-targeted and peripheral blood alterations of regulatory T cells in primary biliary cirrhosis

CD4+CD25high regulatory T cells (Tregs) play a critical role in self-tolerance, as seen in murine autoimmunity. Studies on Tregs in human autoimmunity have focused primarily on peripheral blood samples. A study targeting diseased tissue should identify direct relationships between Tregs and autoimmunity. Peripheral blood samples were collected from 91 patients with primary biliary cirrhosis (PBC), 28 immediate relatives, and 41 healthy controls, and Treg frequencies were determined as a percentage of CD4+CD25high T cells in CD4+TCR-alphabeta+ T cells. A tissue-targeted determination of frequency and distribution of FoxP3+ Tregs was also performed on 90 different liver tissue specimens exhibiting PBC (n = 52), chronic hepatitis C (CHC) (n = 30), and autoimmune hepatitis (AIH) (n = 8). Treg suppression studies were performed on 50 PBC patients and 27 controls. Patients with PBC demonstrated a relative reduction of Tregs compared with controls (P < .0002). Interestingly, a deficiency in CD4+CD25+ Tregs was also found in the daughters and sisters of PBC patients compared with controls (P < .0007). However, functional studies did not reveal a global PBC Treg defect. The level of FoxP3-expressing Tregs was markedly lower in affected PBC portal tracts compared with CHC and AIH (P < .001). In addition, the CD8+T cell/FoxP3+ Treg ratio was significantly higher in livers of late-stage PBC compared with those of CHC (P < .001) and early-stage AIH (P < .001). In conclusion, these data provide support for a genetic modulation of Treg frequency and illustrate the role Tregs play in the loss of tolerance in PBC.

Differential expressions of aquaporin proteins in human cholestatic liver diseases

Aquaporins (AQPs) are the channel forming membranous proteins involved in the biliary physiological homeostasis. Recently, we have reported the heterogeneous expression of AQPs in intrahepatic biliary epithelial cells or cholangiocytes in mice. However, the involvements of AQPs in hepatobiliary disorder are still unclear. Thus, we hypothesized that the AQP protein expressions are altered in human cholestatic disorders.

METHODS

The AQP expressions of the immortalized human cholangiocytes cell line (H69) were assessed by immunoblotting. The expression of AQPs in liver biopsy specimens from various human cholestatic diseases as well as viral hepatitis were evaluated immunohistochemically. The degrees of staining were classified into four grades by comparison with staining intensity from controls.

RESULTS

AQP1 expression, predominantly membranous, was confirmed by immunoblotting analysis. However, the other subtypes of AQP expression were not detected. In human pathological tissues, AQP1 expression by interlobular bile ducts was similar to normal and viral hepatitis, although this expression was attenuated according to bile duct injuries in PBC. On the contrary, the AQP1 expression by proliferating bile ductile (equivalent for small cholangiocytes) was enhanced. In intrahepatic cholestasis, AQP1 expressions were diminished, which was further associated with the aberrant expressions by periportal hepatocytes.

CONCLUSIONS

AQP1 was expressed intensely in smaller proliferating bile ducts in human cholestatic liver disease. Also, the AQP1 expression was decreased in injured duct cells undergoing degeneration in PBC. The AQP1 expression was decreased in intrahepatic cholestasis probably due to negative feed back of the decreased bile flow. The role of AQP expression profiles may help the understanding of the pathogenesis of human cholestatic liver diseases.

Plasmacytoid dendritic cells of different origins have distinct characteristics and function: studies of lymphoid progenitors versus myeloid progenitors

Plasmacytoid dendritic cells (pDCs) play a central role in host innate and adaptive immunity and are thought to be of lymphoid origin. However, in IL-7Ralpha-/- mice, which are deficient in T and B lymphocytes, pDCs are still found in lymphoid organs, which suggests that there is a lymphoid-independent pathway for the development of pDCs. Previous work has demonstrated that pDCs originate from both lymphoid and myeloid progenitors (MPs). However, it is not clear whether the function of pDCs is different relative to their origin. In an effort to compare the characteristics and functions between pDCs generated from different progenitors, we performed adoptive transfer studies using highly enriched populations of common lymphoid progenitors (CLPs) and MPs from the bone marrow of control mice and examined their potential and developmental kinetics for the generation of pDCs. Interestingly, although CLPs were polarized to generate pDCs, MPs were polarized to generate conventional dendritic cells and the kinetics of pDC generation from MPs was reached earlier than from CLPs. Furthermore, CLPs have the potential to generate more pDCs on a per cell basis. Moreover, MP-derived pDCs produce relatively higher levels of IFN-alpha than CLP-derived pDCs following CpG stimulation. These data indicate that MPs are multipotential and have the capacity to develop into not only myeloid cells, but also pDCs, which have distinct characteristics and function compared to that of lymphoid origin and, therefore, imply a more important role for MP-derived pDCs in conditions where the function of lymphoid progenitors is impaired or compromised.

Increased levels of chemokine receptor CXCR3 and chemokines IP-10 and MIG in patients with primary biliary cirrhosis and their first degree relatives

Infiltrating memory T cells play an important role in the destruction of the biliary tract in primary biliary cirrhosis (PBC) and inflammatory chemokines control lymphocyte traffic through their interactions with T cell chemokine receptors. In the present study, we measured plasma levels of chemokines interferon-gamma-inducible protein-10 (IP-10) and monokine induced by gamma interferon (MIG), and also studied the expression of CXCR3 chemokine receptors in 105 subjects, including 53 patients with PBC, 26 first degree relatives and 26 healthy controls. Interestingly, plasma IP-10 and MIG levels in PBC were increased significantly compared to controls and appeared to increase with disease progression. By immunohistochemistry, IP-10 and MIG expressions were evident in the portal areas in PBC. Further, the frequency of CXCR3-expressing cells in peripheral blood was also significantly higher in PBC, and CXCR3-positive cells were also found in the portal areas of diseased livers, primarily on CD4+ cells. Finally, the daughters and sisters of PBC patients also demonstrated increased plasma levels of IP-10 and MIG, but, in contrast, displayed normal frequency of CXCR3+ expressing peripheral blood lymphocytes. Our data imply a role for specific chemokine-chemokine receptor interactions in the pathogenesis of PBC and also highlight the familial risk factor.

Living Related Liver Transplantation for Acute Fulminant Hepatitis B: Experience from Two Possible Hyper-Acute Cases

Fulminant hepatic failure, which is represented by fulminant hepatitis, is fatal in most cases unless prompt liver transplantation is performed. Even if liver transplantation is performed, irreversible neurological damage is often complicated. In this case report, we describe two cases of fulminant hepatitis induced by acute hepatitis B virus infection, both of which were successfully rescued by living related liver transplantation without significant complications. The case 1 was a 45-year-old Japanese male. He complained general malaise and anorexia. His local physician diagnosed him as acute hepatitis B, and referred to our hospital. Due to severe coagulopathy, plasma exchange was performed 3 times. However, his hepatic coma progressed rapidly along with rapid decrease of both his direct/indirect bilirubin (D/T) ratio and serum blood urea nitrogen (BUN) levels. Living related liver transplantation was performed under the diagnosis of acute fulminant hepatitis B. The case 2 was a 34-year-old Japanese male. His complaints were fever and skin rush. He was referred to our hospital under the diagnosis of acute hepatitis B. On the second day after admission, he developed grade II hepatic coma, which deteriorated into grade III in spite of intensive therapy including plasma exchange. He also demonstrated rapid decrease of both D/T ratio and serum BUN level. Living related liver transplantation was performed on the next day. Both cases recovered without any evidence of neurological sequelae. In general, it is extremely difficult to rescue fulminant hepatitis by conservative treatments, particularly in cases with rapid progression. Although emergency liver transplantation may be an only option to rescue in such a case, living related liver transplantation has an advantage in view of urgent organ donation over cadeveric transplantation.

Lack of common mutation in the alfa-subunit of the mitochondrial trifunctional protein and the polymorphism of CYP2E1 in three Japanese women with acute fatty liver of pregnancy/HELLP syndrome

BACKGROUND:: Acute fatty liver of pregnancy (AFLP) and the HELLP syndrome are the serious disorders during pregnancy. The aim of this study is to clarify the prevalence of common mutation in the alpha-subunit of the mitochondrial tri-functional protein: hydroxyacyl-CoA dehydrogenase (LCHAD)/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase as well as to determine the correlation with the polymorphism of microsomal cytochrome P4502E1 (CYP2E1) in these conditions. METHODS:: Genomic DNA was extracted from three patients with AFLP/the HELLP syndrome. Exon 15 of LCHAD and 5'-flanking lesion of CYP2E1 was amplified by PCR and analyzed by RFLP with either of Pst I or the combination of Pst I and Rsa I, respectively. RESULTS:: None of the patients demonstrated the 1528G-C mutation in LCHAD gene. All the patients had homozygous wild-type genotype (c1/c1) in the 5'-flanking lesion of CYP2E1. CONCLUSIONS:: Although limited size of study, our observations suggest the low incidence rate of LCHAD common mutation among Japanese patients with AFLP/HELLP syndrome. Moreover, all of the patients had wild-type genotype of CYP2E1 in this study. Considering with the fact that the neonates from these patients has been in good health for at least 6 years from birth, there might be diverse etiologic factors of Japanese patients with AFLP/HELLP syndrome other than reported genetic mutations.

Evaluation of differential gene expression by microarray analysis in small and large cholangiocytes isolated from normal mice

AIMS

We have shown that large and small cholangiocytes, which reside primarily in large and small intrahepatic bile ducts, respectively, have different functions and responses to injuries. However, there are no systematic studies of the molecular differences between small and large cholangiocytes, which would explain cholangiocyte heterogeneity. To evaluate the differential gene expression between small and large cholangiocytes, microarray analysis was performed.

METHODS

Primary cultures of small and large cholangiocytes were isolated from normal mice (BALB/c), and immortalized by the introduction of the SV40 large T antigen gene. After cloning, small and large cholangiocyte cell lines were established. Their characteristic features were confirmed by electron microscopy (EM) and measurement of transepithelial electrical resistance (TER), and secretin-stimulated cAMP levels. Isolated total RNAs were hybridized with microarrays (Atlas Glass Array Mouse 1.0 and 3.8), which detects 4850 cDNA expressions. After hybridization, the fluorescent signals were scanned by a GenePix fluorescent scanner and analyzed using ArrayGauge software.

RESULTS

EM, TER and secretin-stimulated cAMP synthesis are consistent with the concept that small and large immortalized cholangiocytes originate from small and large ducts, respectively. When a cut-off value at the expression signal difference of 3.0 times was employed, 230 cDNAs among 4850 cDNAs (4.74%) were differentially expressed between small and large cholangiocytes. Of these 230 cDNAs, aquaporin 8, IL-2 receptor beta chain and caspase 9 were more strongly expressed by large cholangiocytes.

CONCLUSIONS

Microarray successfully displayed characteristic differential cDNA expression between small and large cholangiocytes. This technique provides molecular information, which further supports our hypothesis that small and large bile ducts have different functions.