Fractalkine and CX3CR1 are involved in the recruitment of intraepithelial lymphocytes of intrahepatic bile ducts

Fractalkine is a chemokine with both chemoattractant and cell-adhesive functions, and in the intestine it is involved with its receptor CX3CR1 in the chemoattraction and recruitment of intraepithelial lymphocytes. We examined the pathophysiological roles of fractalkine and CX3CR1 in normal and diseased bile ducts. Expression of fractalkine and CX3CR1 were examined in liver tissues from patients with primary biliary cirrhosis (17 cases) and controls (9 cases of primary sclerosing cholangitis, 10 cases of extrahepatic biliary obstruction, 20 cases of chronic viral hepatitis C, and 18 cases of histologically normal livers). Expression of fractalkine in biliary epithelial cells (BECs) in response to cytokine treatments was examined using a human cholangiocarcinoma cell line (HuCC-T1) and human intrahepatic BEC line. The chemotaxis of CX3CR1-expressing monocytes (THP-1) toward fractalkine was assayed using chemotaxis chambers. Fractalkine messenger RNA/protein were expressed on BECs of normal and diseased bile ducts, and their expression was upregulated in injured bile ducts of primary biliary cirrhosis. CX3CR1 was expressed on infiltrating mononuclear cells in portal tracts and on CD3(+), CD4(+), and CD8(+) intraepithelial lymphocytes of injured bile ducts in primary biliary cirrhosis. Fractalkine messenger RNA expression was upregulated in two cultured BECs on treatment with lipopolysaccharide and Th1-cytokines (interleukin 1beta, interferon gamma, and tumor necrosis factor alpha). THP-1 cells showed chemotaxis toward fractalkine secreted by cultured cells. In conclusion, Th1-cytokine predominance and lipopolysaccharide in the microenvironment of injured bile ducts resulting from primary biliary cirrhosis induce the upregulation of fractalkine expression in BECs, followed by the chemoattraction of CX3CR1-expressing mononuclear cells, including CD4(+) and CD8(+) T cells, and their adhesion to BECs and the accumulation of biliary intraepithelial lymphocytes.     

Interaction between Toll-like receptors and natural killer cells in the destruction of bile ducts in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is characterized by chronic nonsuppurative destructive cholangitis (CNSDC) associated with destruction of small bile ducts. Although there have been significant advances in the dissection of the adaptive immune response against the mitochondrial autoantigens, there are increasing data that suggest a contribution of innate immune mechanisms in inducing chronic biliary pathology. We have taken advantage of our ability to isolate subpopulations of liver mononuclear cells (LMC) and examined herein the role of Toll-like receptors (TLRs), their ligands, and natural killer (NK) cells in modulating cytotoxic activity against biliary epithelial cells (BECs). In particular, we demonstrate that Toll-like receptor 4 ligand (TLR4-L)-stimulated NK cells destroy autologous BECs in the presence of interferon alpha (IFN-α) synthesized by TLR 3 ligand (TLR3-L)-stimulated monocytes (Mo). Indeed, IFN-α production by hepatic Mo is significantly increased in patients with PBC compared to disease controls. There were also marked increases in the cytotoxic activity of hepatic NK cells from PBC patients compared to NK cells from controls but only when the NK cells were prepared following ligation of both TLR3-L- and TLR4-L-stimulated LMC. These functional data are supported by the immunohistochemical observation of an increased presence of CD56-positive NK cells scattered around destroyed small bile ducts more frequently in liver tissues from PBC patients than controls. CONCLUSION: These data highlight critical differences in the varied roles of Mo and NK cells following TLR3-L and TLR4-L stimulation.     

Generation of monoclonal antibodies to murine bile duct epithelial cells: identification of annexin V as a new marker of small intrahepatic bile ducts

Biliary epithelial cells (BECs) are distributed along the length of both the extrahepatic and intrahepatic biliary tree, but have distinctly different phenotypes and functions according to their anatomical location. It has been reasoned that the distinct appearance of pathogenic lesions in different biliary diseases may be associated with the expression of distinct proteins. These data prompted us to immunize rats with cultured murine BECs with the objective of determining if there are unique antigens on BECs. Of the 45 monoclonal antibodies (mAbs) produced, 12 mAbs (MBEC 1-12) were selected for detailed study based on their classification into three major groups. These groups included four antibodies (MBEC 1-4) that reacted in a staining pattern typical of mucin. A second group of mAbs, MBECs 5 to 8, reacted strongly along the biliary tract and by immunoblot analysis, reacted with several bands ranging from 44 kd to 64 kd. These antibodies were considered as markers of pan BECs and their staining pattern proved similar to that of a control polyclonal pan-cytokeratin. The final group of mAbs, MBECs 9 to 12, recognized a 36-kd antigen using lysates of murine BECs. These antibodies also predominantly stained small peripheral bile ducts. The reactive antigen was purified by immunoprecipitation and microsequenced; the peptides sequenced showed 100% homology with murine annexin V. The identification of annexin V with predominantly intrahepatic bile ducts, is of significant interest because of the multiple roles of annexin V, including that of membrane cytoskeletal interactions during transport and apoptosis.     

Morphogenesis of primary human biliary epithelial cells: induction in high-density culture or by coculture with autologous human hepatocytes

Although the control of biliary ductular morphogenesis has received some attention particularly using isolated rat biliary epithelial cell models, the regulation of human bile duct formation is not well defined. In the present study, using a 3-dimensional culture model comprising primary human biliary epithelial cells (BECs) and coculture with primary human hepatocytes, we have sought to define the factors involved. We have shown that primary human BECs can be expanded on collagen gels in the absence of growth factors or serum. When plated in high density in double collagen gels, BECs established 3-dimensional structures that subsequently developed into well differentiated polarized luminal ducts. This morphogenic response occurred in the absence of hepatocyte growth factor (HGF) and epidermal growth factor. Strikingly, the addition of growth factors (in the presence of serum) resulted in loss of polarity although the cells retained growth responses to both factors. Coculture of BECs with autologous human hepatocytes enhanced the ability of low-density BECs to undergo ductulogenesis. This effect was mimicked by addition of conditioned medium from previous hepatocyte-BEC cocultures. These findings indicate that for human biliary ductular morphogenesis, epithelial cell-cell interactions are required but that mesenchymally derived factors such as HGF may not be important.     

The continuing importance of bile acids in liver and intestinal disease

Bile acids, the water-soluble, amphipathic end products of cholesterol metabolism, are involved in liver, biliary, and intestinal disease. Formed in the liver, bile acids are absorbed actively from the small intestine, with each molecule undergoing multiple enterohepatic circulations before being excreted. After their synthesis from cholesterol, bile acids are conjugated with glycine or taurine, a process that makes them impermeable to cell membranes and permits high concentrations to persist in bile and intestinal content. The relation between the chemical structure and the multiple physiological functions of bile acids is reviewed. Bile acids induce biliary lipid secretion and solubilize cholesterol in bile, promoting its elimination. In the small intestine, bile acids solubilize dietary lipids promoting their absorption. Bile acids are cytotoxic when present in abnormally high concentrations. This may occur intracellularly, as occurs in the hepatocyte in cholestasis, or extracellularly, as occurs in the colon in patients with bile acid malabsorption. Disturbances in bile acid metabolism can be caused by (1) defective biosynthesis from cholesterol or defective conjugation, (2) defective membrane transport in the hepatocyte or ileal enterocyte, (3) defective transport between organs or biliary diversion, and (4) increased bacterial degradation during enterohepatic cycling. Bile acid therapy involves bile acid replacement in deficiency states or bile acid displacement by ursodeoxycholic acid, a noncytotoxic bile acid. In cholestatic liver disease, administration of ursodeoxycholic acid decreases hepatocyte injury by retained bile acids, improving liver tests, and slowing disease progression. Bile acid malabsorption may lead to high concentrations of bile acids in the colon and impaired colonic mucosal function; bile acid sequestrants provide symptomatic benefit for diarrhea. A knowledge of bile acid physiology and the perturbations of bile acid metabolism in liver and digestive disease should be useful for the internist.     

Significance of periductal Langerhans cells and biliary epithelial cell‐derived macrophage inflammatory protein‐3α in the pathogenesis of primary biliary cirrhosis

Background/aims: To clarify the primary biliary cirrhosis (PBC)‐specific antigen‐presenting mechanism, we examined the distribution and phenotypic characteristics of infiltrating dendritic cells (DCs) with respect to bile ducts and the mechanism of migration in terms of the periductal cytokine milieu and biliary innate immunity. Methods and results: Immunohistochemistry using liver sections from patients with PBC and controls revealed that blood dendritic cell antigen (BDCA)‐2⁺ plasmacytoid DCs were found mainly in the portal tracts in PBC and the controls, but their distribution was not related to bile ducts. BDCA‐1⁺ and CD19^? myeloid DCs were also found in portal tracts in PBC and the controls and, in particular, Langerin+Langerhans cells (LCs) were dominantly scattered around or within biliary epithelial layers of the damaged bile ducts in PBC. Moreover, experiments with cultured human biliary epithelial cells (BECs) showed that an LC‐attracting chemokine, macrophage inflammatory protein‐3α, was produced by BECs in the response to cytokines [interleukin (IL)‐1β, tumour necrosis factor‐α and IL‐17] and pathogen‐associated molecular patterns. Conclusions: LCs existing around or within biliary epithelial layers are important as periductal antigen‐presenting cells in PBC and the migration of LCs into bile ducts is closely associated with the periductal cytokine milieu and biliary innate immunity in PBC.     

Biliary epithelial cells and primary biliary cirrhosis: the role of liver-infiltrating mononuclear cells

Primary biliary cirrhosis (PBC) is characterized by the highly selective autoimmune injury of small intrahepatic bile ducts, despite widespread distribution of mitochondrial autoantigens. On this basis, it has been suggested that the targeted biliary epithelial cells (BECs) play an active role in the perpetuation of autoimmunity by attracting immune cells via chemokine secretion. To address this issue, we challenged BECs from patients with PBC and controls using multiple Toll-like receptor (TLR) ligands as well as autologous liver-infiltrating mononuclear cells (LMNCs) with subsequent measurement of BEC phenotype and chemokine production and LMNC chemotaxis by quantifying specific chemokines. Our data reflect that BECs from PBC patients and controls express similar levels of TLR subtypes, CD40, and human leukocyte antigen DRalpha (HLA-DRalpha) and produce equivalent amounts of chemokines in our experimental conditions. Interestingly, however, BEC-expressed chemokines elicit enhanced transmigration of PBC LMNCs compared with controls. Furthermore, the addition of autologous LMNCs to PBC BECs led to the production of higher levels of chemokines and enhanced the expression of CD40 and HLA-DRalpha. CONCLUSION: We submit that the proinflammatory activity of BECs in PBC is secondary to the intervention of LMNCs and is not determined per se. These data support the hypothesis that BECs are in fact "innocent victims" of autoimmune injury and that the adaptive immune response is critical in PBC.     

Pathology and pathogenesis of intrahepatic bile duct loss

In recent years, the pathology and pathogenesis of bile duct loss have been extensively studied, and a num‐ber of hepatobiliary diseases have been added to the list of ductopenic diseases. In addition, the biology of biliary epithelial cells is now being studied with respect to bile duct loss, as well as biliary epithelial neoplasia. In this review, recent advances in pathogenetic and pathological studies of intrahepatic bile duct loss are described, with an emphasis on immune‐mediated cholangiopathies. The bile duct loss, an acquired and pathologic process that occurs in the biliary tree, is recognizable as an absence of bile duct in an individual portad tract, and also as such absence in the vicinity of parallel running hepatic arterial branches that constitute the portal triad. Immunostaining with biliary cytokeratin and other carbohydrate materials is useful for the identification of biliary elements in the inflamed portal tracts or fibrous septa. The underlying processes responsible for bile duct loss include immunological, ischemic, infectious, metabolic, and toxic processes. Bile duct loss in primary biliary cirrhosis and primary sclerosing cholangitis is immune‐mediated, that in interventional radiology using hepatic arterial branches is related to biliary ischemia, while that in hepatic allograft rejection is related to both immunological and ischemic insults. Bacterial and viral cholangitis with bile duct loss is an example of infectious cholangitis. The biliary tree maintains its homeostasis by renewal and dropout, and bile duct loss occurs mainly via biliary apoptosis. In some patients with bile duct loss, such as occurs in drug‐induced injuries, the bile ducts regenerate and finally redistribute in the liver, while in other types of bile duct loss, the loss is progressive and is followed by vanishing bile duct syndrome, leading to biliary cirrhosis or liver transplantation. More analysis of the biology of biliary epithelial cells is mandatory for the evaluation of the pathobiology of bile duct loss, as well as for the effective restoration of biliary epithelial cells, in ductopenic liver diseases.     

Myeloperoxidase-positive inflammatory cells participate in bile duct damage in primary biliary cirrhosis through nitric oxide-mediated reactions

Previous studies have suggested that increased nitric oxide (NO)-mediated products are found in the livers of subjects with primary biliary cirrhosis (PBC), but the mechanisms involved remain enigmatic. We took advantage of immunohistochemistry and several unique monoclonal antibodies to study inflammatory cells responsible for the generation of NO, the enzymes responsible for NO production, the expression of 3-nitrotyrosine, and the presence of CD68(+) and/or myeloperoxidase (MPO)(+) cells. We examined a total of 113 liver specimens, including 64 with PBC, 19 with primary sclerosing cholangitis (PSC), 6 with non-A, non-B hepatitis, 6 with alcoholic liver disease, 4 with cryptogenic cirrhosis, 4 with biliary atresia, and 10 normal subjects. Twenty-two percent of PBC had elevated expression of 3-nitrotyrosine in their bile duct epithelial cells (BECs) (P =.0316). Furthermore, the BECs in PBC also demonstrated apoptotic changes. MPO-positive inflammatory cells were also noted adjacent to the basement membrane. In contrast, the liver of normal subjects showed few apoptotic changes in the bile ducts, with no evidence of MPO staining in the portal area. Furthermore, sections from livers of subjects with stage I or stage II PBC demonstrated significantly increased inflammatory cell infiltration (P =.0064) and elevated 3-nitrotyrosine expression in BECs (P =.0246) compared with stage III and IV. The presence of 3-nitrotyrosine was closely associated with infiltrating CD68- and/or MPO-positive cells. There was also a stage-associated difference in the presence of bile duct infiltrating cells and 3-nitrotyrosine in PBC with an increase dominant in early stage disease. In conclusion, NO and reactive oxygen species, collectively determined as 3-nitrotyrosine, are associated with bile duct destruction in PBC and are particularly prevalent in early stage disease.     

Intracellular balance of oxidative stress and cytoprotective molecules in damaged interlobular bile ducts in autoimmune hepatitis and primary biliary cirrhosis: In situ detection of 8-hydroxydeoxyguanosine and glutathione-S-transferase-pi

Aim: Bile duct injury has been thought to be absent in autoimmune hepatitis (AIH), but recent studies have indicated that AIH patients do have bile duct injury. In this study, the intracellular balance of oxidative stress and cytoprotection in biliary epithelial cells was investigated to clarify the pathogenesis of bile duct injury in AIH. Methods: The intracellular status of oxidative DNA damage caused by oxidative stress and glutathione, an endogenous cytoprotective molecule, were examined in patients with AIH, primary biliary cirrhosis (PBC), and normal controls by immunostaining of 8-hydroxydeoxyguanosine (8-OHdG) and glutathione-S-transferase-pi. Results: Immunohistochemically, 8-OHdG expression was detected as abundantly in the damaged bile ducts of AIH patients as in PBC patients. Moreover, in AIH, 8-OHdG expression was detected in damaged bile ducts more than in undamaged bile ducts. Glutathione-S-transferase-pi expression was relatively preserved in the damaged bile ducts of AIH patients compared to PBC patients, reflecting preservation of intracellular glutathione. Conclusions: In AIH, oxidative stress and DNA damage may be involved in the pathogenesis of bile duct injury in a manner similar to that found in PBC. However, relatively preserved intracellular glutathione may play a key role in preventing progressive bile duct loss following bile duct injury in AIH.     

Progress and Current Limitations of Materials for Artificial Bile Duct Engineering

Bile duct injury (BDI) and bile tract diseases are regarded as prominent challenges in hepatobiliary surgery due to the risk of severe complications. Hepatobiliary, pancreatic, and gastrointestinal surgery can inadvertently cause iatrogenic BDI. The commonly utilized clinical treatment of BDI is biliary-enteric anastomosis. However, removal of the Oddi sphincter, which serves as a valve control over the unidirectional flow of bile to the intestine, can result in complications such as reflux cholangitis, restenosis of the bile duct, and cholangiocarcinoma. Tissue engineering and biomaterials offer alternative approaches for BDI treatment. Reconstruction of mechanically functional and biomimetic structures to replace bile ducts aims to promote the ingrowth of bile duct cells and realize tissue regeneration of bile ducts. Current research on artificial bile ducts has remained within preclinical animal model experiments. As more research shows artificial bile duct replacements achieving effective mechanical and functional prevention of biliary peritonitis caused by bile leakage or obstructive jaundice after bile duct reconstruction, clinical translation of tissue-engineered bile ducts has become a theoretical possibility. This literature review provides a comprehensive collection of published works in relation to three tissue engineering approaches for biomimetic bile duct construction: mechanical support from scaffold materials, cell seeding methods, and the incorporation of biologically active factors to identify the advancements and current limitations of materials and methods for the development of effective artificial bile ducts that promote tissue regeneration.     

Intestinal synthesis and secretion of bile salts as an adaptation to developmental biliary atresia in the sea lamprey

Bile salt synthesis is a specialized liver function in vertebrates. Bile salts play diverse roles in digestion and signaling, and their homeostasis is maintained by controlling input (biosynthesis) and intestinal conservation. Patients with biliary atresia (i.e., obliteration of the biliary tree) suffer liver fibrosis and cirrhosis. In contrast, sea lamprey thrives despite developmental biliary atresia. We discovered that the sea lamprey adapts to biliary atresia through a unique mechanism of de novo synthesis and secretion of bile salts in intestine after developmental biliary atresia, in addition to known mechanisms, such as the reduction of bile salt synthesis in liver. During and after developmental biliary atresia, expression of cyp7a1 in intestine increased by more than 100-fold (P < 0.001), whereas in liver it decreased by the same magnitude (P < 0.001). Concurrently, bile salt pools changed in similar patterns and magnitudes in these two organs and the composition shifted from C24 bile alcohol sulfates to taurine-conjugated C24 bile acids. In addition, both in vivo and ex vivo experiments showed that aductular sea lamprey secreted taurocholic acid into its intestinal lumen. Our results indicate that the sea lamprey, a jawless vertebrate, may be in an evolutionarily transitional state where bile salt synthesis occurs in both liver and intestine. Understanding the molecular basis of these mechanisms may shed light on the evolution of bile salt synthesis and possible therapy for infant biliary atresia.     

An involvement of Hippo-yes-associated protein pathway in biliary epithelial senescence in primary biliary cholangitis

Background & AimsAccumulating evidence suggest that Hippo-yes-associated protein (YAP) pathway plays important roles in development and repair after injuries in biliary system. We disclosed that senescent biliary epithelial cells (BECs) participate in the pathogenesis of primary biliary cholangitis (PBC). We hypothesized that dysregulation of Hippo-YAP pathway may be associated with biliary epithelial senescence in pathogenesis of PBC.Approach & ResultsCellular senescence was induced in cultured BECs by treatment with serum depletion or glycochenodeoxycholic acid. The expression and activity of YAP1 were significantly decreased in senescent BECs (p<0.01). Cellular senescence and apoptosis were significantly increased (p<0.01) and a proliferation activity and a 3D-cyst formation activity were significantly decreased (p<0.01) by a knockdown of YAP1 in BECs. The expression of YAP1 were immunohistochemically determined in livers taken from the patients with PBC (n = 79) and 79 control diseased and normal livers and its association with senescent markers p16^INK4a and p21^WAF1/Cip1 was analyzed. The nuclear expression of YAP1, which indicates activation of YAP1, was significantly decreased in BECs in small bile ducts involved in cholangitis and ductular reactions in PBC, compared to control livers (p<0.01). The decreased expression of YAP1 was seen in senescent BECs showing expression of p16^INK4a and p21^WAF1/Cip1 in bile duct lesions.ConclusionDysregulation of Hippo-YAP1 pathway may be involved in the pathogenesis of PBC in association with biliary epithelial senescence.     

Isolation,culture and characterization of biliary epithelial cells from different anatomical levels of the intrahepatic and extrahepatic biliary tree from a mouse

ABSTRACT— We developed methods to isolate biliary epithelial cells (BECs) from the gallbladder (GB), common bile duct (CBD), intrahepatic large bile duct (ILBD) and small bile duct (ISBD) of a mouse, simultaneously. ILBD and ISBD were cut from the biliary tree after collagenase perfusion of the liver. BECs from all of these biliary segments were cultured as explants on collagen gel. BECs spread from the explants and formed cellular sheets. Areas of these sheets composed entirely of BECs were cut and placed on other gels as subculture, and this continued for 10 passages. Primary and passage cultured BECs on gel were composed of a monolayer of epithelial cells. Passaged cultured BECs in gel formed a spherical cyst lined by a single epithelial layer. Ultrastructurally, microvilli were dense on the luminal surface, and junctional complex and interdigitation was identifiable on the lateral surfaces. These features were similar in both primary and passaged cultured BECs, irrespective of their anatomical origin. Major histocompatibility complex antigens and intercellular adhesion molecule-1 were induced on the basolateral cell membranes of primary and passaged cultured BECs, by interferon-γ. Although several phenotypic, structural and probable biological features of BECs inherent to each anatomical level may be lost after culture on gel, a combination of this method, several immunological modifications in experimental animals, and addition of immunologically active substances to the culture medium will make the immunopathologic analysis of biliary diseases possible.     

Lack of Concomitant Expression of ICAM-1 and HLA-DR on Bile Duct Cells from Patients with Primary Sclerosing Cholangitis and Primary Biliary Cirrhosis

In both primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) prominent infiltrates of lymphocytes surround the bile ducts, on which an abberrant expression of major histocompatibility complex class II antigens has been found, suggesting that the immune system is involved in the biliary destruction. Since the lymphocytes presumably must adhere to the bile ducts to initiate a cell-to-cell-mediated destruction, we have studied the expression of the lymphocyte function-associated antigen-1 (LFA-1) together with its ligand, the intercellular adhesion molecule-1 (ICAM-1), and the expression of HLA-DR, using immunoperoxidase staining of cryostat sections from patients with PBC (n = 10), PSC (n = 13), and normal healthy controls (n = 6). Most lymphocytes expressed LFA-1. ICAM-1 expression was found on hepatocytes from 9 of 10 PBC and 10 of 13 PSC patients but was not seen on hepatocytes from the controls. Hepatocytes expressing HLA-DR were only found in one patient with PBC. None of the septal bile ducts expressed ICAM-1, and only one PSC patient and three PBC patients expressed ICAM-1 on their interlobular bile ducts. The bile ducts in 22 of 23 patients, however, expressed HLA-DR. Proliferating bile ductules from two PBC patients and three PSC patients showed a concomitant expression of ICAM-1 and HLA-DR. None of the bile ducts from the controls expressed ICAM-1 or HLA-DR. Thus, since most bile ducts involved in the disease process of both PBC and PSC lack expression of ICAM-1, other adhesion molecules must be involved if a cell-to-cell-mediated destruction accounts for the biliary destruction in these two disease states. Furthermore, the lack of concomitant expression of HLA-DR and ICAM-1 on the bile ducts in PBC and PSC indicates that other regulatory mechanisms exist in the biliary epithelium than in most other epithelial cells.     

Bile salts and cholestasis

Bile salts have a crucial role in hepatobiliary and intestinal homeostasis and digestion. Primary bile salts are synthesized by the liver from cholesterol, and may be modified by the intestinal flora to form secondary and tertiary bile salts. Bile salts are efficiently reabsorbed from the intestinal lumen to undergo enterohepatic circulation. In addition to their function as a surfactant involved in the absorption of dietary lipids and fat-soluble vitamins bile salts are potent signaling molecules in both the liver and intestine.Under physiological conditions the bile salt pool is tightly regulated, but the adaptive capacity may fall short under cholestatic conditions. Elevated serum and tissue levels of potentially toxic hydrophobic bile salts during cholestasis may cause mitochondrial damage, apoptosis or necrosis in susceptible cell types.Therapeutic nontoxic bile salts may restore impaired hepatobiliary secretion in cholestatic disorders. The hydrophilic bile salt ursodeoxycholate is today regarded as the effective standard treatment of primary biliary cirrhosis and intrahepatic cholestasis of pregnancy, and is implicated for use in various other cholestatic conditions. Novel therapeutic bile salts that are currently under evaluation may also prove valuable in the treatment of these diseases.     

Ursodeoxycholic acid reduces expression of heat shock proteins in primary biliary cirrhosis

BACKGROUND: To identify injured cells in the liver of patients with primary biliary cirrhosis (PBC) and to determine the effects of ursodeoxycholic acid (UDCA) on these cells, we examined the cellular expression of heat shock proteins (HSPs) in PBC both before and after treatment with UDCA. METHODS: Expression of HSP70 and ubiquitin in PBC livers (n=34) was evaluated immunohistochemically as well as by immunoblot analysis, and compared with chronic viral hepatitis type C (n= 9), primary sclerosing cholangitis (n=8), and controls (n=7). RESULTS: Immunoblot analysis demonstrated a marked expression of HSP70 and ubiquitin in PBC. Immunohistochemical staining for both HSP70 and ubiquitin was observed to be strong in biliary epithelial cells (BECs) and moderate in both hepatocytes and arteries in PBC. Cellular labelling rates for HSP70 and ubiquitin of bile ducts in PBC were significantly higher (p<0.01) than those in chronic viral hepatitis type C, primary sclerosing cholangitis, or controls. The labelling rates for HSP70 and ubiquitin in bile ducts and in hepatocytes were significantly decreased (p<0.01) after treatment with UDCA in PBC. CONCLUSIONS: The present data suggest that BECs and hepatocytes significantly express HSPs even in the early stages of PBC, and that UDCA treatment significantly improves their condition. The immunohistochemical evaluation of HSPs is a valid and sensitive means to identify injured cells in PBC.     

Immunopathogenesis of primary sclerosing cholangitis: possible role of a shared colonic and biliary epithelial antigen

Abstract   Primary sclerosing cholangitis (PSC) is a chronic fibrosing disease of both extrahepatic as well as intrahepatic bile ducts that is strongly associated with inflammatory bowel disease, particularly ulcerative colitis. It is characterized by progressive destruction of the bile ducts leading to widespread biliary obstructions and biliary cirrhosis. PSC is currently one of the more common indications for liver transplantation. It is an immune mediated disorder associated with autoantibodies against both colon epithelium as well as biliary epithelium, infiltration of the portal tract with functional T cells, abnormal expression of HLA molecules on biliary epithelial cells and a restricted T-cell receptor repertoire. Activation of the complement system, following the deposition of antigen-specific autoantibody with biliary epithelial cells, may also contribute to the pathogenesis of PSC. Four different HLA haplotypes have been associated with PSC: three with increased risk of disease and one with reduced risk. Bacterial products entering the biliary epithelium from colon may be a triggering factor strongly associated with ulcerative colitis; however, a further immune mediated chronic inflammation may be associated with cellular antigen(s) which is shown to be shared by human colon and biliary epithelium by molecular mimicry.