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The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative “strength” of local immune responses. Paradoxically, necro-inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell–mediated rejection have redirected focus on long-term allograft structural integrity. Understanding of insults should enable decades of morbidity-free survival after liver replacement because of these tolerogenic properties. Studies of long-term survivors show low-grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor-specific antibodies, and T cell–mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The “balance” is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low-level, including allo-antibody-mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system.

The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative “strength” of local immune responses. Paradoxically, necro‐inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell–mediated rejection have redirected focus on long‐term allograft structural integrity. Understanding of insults should enable decades of morbidity‐free survival after liver replacement because of these tolerogenic properties. Studies of long‐term survivors show low‐grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor‐specific antibodies, and T cell–mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The “balance” is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low‐level, including allo‐antibody‐mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system. The authors review the immune structural anatomy of the liver as an allograft and compare it to other solid organ allografts, emphasizing the microvasculature, mononuclear phagocytic system and tolerogenic properties to provide a perspective on operational tolerance and interactions with alloantibodies.

The outcomes of primary sclerosing cholangitis (PSC) after living donor liver transplantation (LDLT) in a large series have not been reported. We aimed to determine long‐term patient and graft survival, risk factors for PSC recurrence, and the significance of recurrence after LDLT in a Japanese registry. Questionnaires concerning patient characteristics, treatments, and clinical courses were used. Data of 114 patients undergoing primary LDLT for PSC from July 1996 to December 2008 in 29 institutions were evaluated. For strict diagnoses of recurrence, patients with hepatic artery thrombosis (n = 8), ABO‐blood‐type‐incompatible transplantation (n = 8), and established ductopenic rejection (n = 2) were excluded and 96 patients were analyzed for risk factors. Recurrence was diagnosed in 26 patients (27%) at 8 to 79 months after transplantation. Patient, graft, and recurrence‐free survivals were 78, 74 and 57% at 5 years after LDLT, respectively. The graft loss rate was 69 versus 23% in patients with versus without recurrence, respectively. Multivariate analysis revealed that high MELD scores, first‐degree‐relative donors, postoperative CMV infection, and early biliary anastomotic complications were significant risk factors for recurrence. PSC recurrence was a significant risk factor of graft loss but not patient death. PSC recurrence was frequent and had significant impacts on outcomes after LDLT.

The outcomes of primary sclerosing cholangitis (PSC) after living donor liver transplantation (LDLT) in a large series have not been reported. We aimed to determine long-term patient and graft survival, risk factors for PSC recurrence, and the significance of recurrence after LDLT in a Japanese registry. Questionnaires concerning patient characteristics, treatments, and clinical courses were used. Data of 114 patients undergoing primary LDLT for PSC from July 1996 to December 2008 in 29 institutions were evaluated. For strict diagnoses of recurrence, patients with hepatic artery thrombosis (n = 8), ABO-blood-type-incompatible transplantation (n = 8), and established ductopenic rejection (n = 2) were excluded and 96 patients were analyzed for risk factors. Recurrence was diagnosed in 26 patients (27%) at 8 to 79 months after transplantation. Patient, graft, and recurrence-free survivals were 78, 74 and 57% at 5 years after LDLT, respectively. The graft loss rate was 69 versus 23% in patients with versus without recurrence, respectively. Multivariate analysis revealed that high MELD scores, first-degree-relative donors, postoperative CMV infection, and early biliary anastomotic complications were significant risk factors for recurrence. PSC recurrence was a significant risk factor of graft loss but not patient death. PSC recurrence was frequent and had significant impacts on outcomes after LDLT.

Background & Aims:: Previous work has suggested that CD4^+ CD28^- or costimulation-independent T cells are increased in autoimmune diseases. In this study, we compared frequency and qualitative characteristics of autoreactive costimulation-independent or CD4^+ CD28^- T cells in primary biliary cirrhosis (PBC) by taking advantage of the well-defined immunodominant autoepitope of the E2 component of pyruvate dehydrogenase (PDC-E2). Methods:: We determined the frequency of costimulation-independent autoreactive T cells that respond to PDC-E2 163-176 and the frequency of CD4^+ CD28^- T cells. Finally, we determined the role of biliary epithelial cells (BEC) as both an antigen-presenting cell or, alternatively, as a target cell for T-cell-mediated cytotoxicity. Results:: The precursor frequency of costimulation-independent CD4^+ T cells that respond to PDC-E2 163-176 and the frequency of CD4^+ CD28^- T cells were dramatically elevated in PBC. Furthermore, 2 types of T-cell clones that respond to PDC-E2 163-176 emerged from this study. One type was costimulation dependent and the other costimulation independent. Both types of clones lyse BEC in a similar effector target (E/T) ratio distribution. However, BEC did not help the proliferation of any T-cell clones. Furthermore, costimulation-independent T-cell clones do not become anergic by BEC. Conclusions:: In PBC, costimulation-independent autoreactive T cells, which do not become anergic, increase and maintain the autoimmune response. In controls, although autoantigens are expressed on BEC and autoantigen-reactive T cells exist around BEC, autoantigen-reactive T cells are costimulation dependent and will become anergic and maintain peripheral tolerance.

The monocyte chemotactic proteins (MCPs) form a distinct structurally related subclass of C-C chemokines. MCPs select specific target cells due to binding to a distinct set of chemokine receptors and because of their effects on monocytes, and may participate in the process of granuloma formation during bacterial and/or mycobacterial infections. The aetiology of primary biliary cirrhosis (PBC) is still unclear, although bacterial infection and autoimmune processes have been implicated. In this study, the expression of three of the most potent monocyte chemoattractants, MCP-1, -2, and -3, was examined in patients with PBC and the data were compared with results for other liver diseases including primary sclerosing cholangitis (PSC), chronic viral hepatitis C, hepatic sarcoidosis, and normal liver. MCP-1 was expressed mainly in biliary epithelial cells of all liver specimens, irrespective of the cause of disease. Some mononuclear leukocytes in the portal tract expressed MCP-1 in all the disease groups examined and there were no significant differences in frequency between these groups. In contrast, more than 80% of PBC livers showed MCP-2- and MCP-3-positive mononuclear leukocyte infiltration in portal tracts, particularly around the bile ducts, whereas such cells were far less frequent in the other disease groups or in normal livers. Epithelioid granulomata of PBC patients contained MCP-2- and MCP-3-positive cells at their edge. In double staining experiments, more than 60% of the MCP-positive mononuclear cells co-expressed CD68, suggesting that a proportion of MCP-2- and MCP-3-positive cells are derived from monocytes. These monocytes expressing MCP-2 and MCP-3 may be responsible for the chemotactic activity of more monocytes. Such an expression pattern of MCP-1, -2 and -3 in portal tracts seems to be distinctive for PBC. This pattern underlines the importance of MCP-1, -2, and -3 in the recruitment of monocytes and possibly T lymphocytes into portal tracts, around the injured bile ducts, and into epithelioid granulomata in PBC. The data further implicate bacterial materials derived from bile in the overall pathogenesis of PBC. Copyright © 2000 John Wiley & Sons, Ltd.

In primary biliary cirrhosis, biliary epithelial cell death by apoptosis results in progressive bile duct loss. We examined immuno-histochemically 4 apoptosis-regulating bcl-2 familial proteins (bcl-2, mcl-1, bcl-X, and bax) in the biliary epithelium in 19 cases of primary biliary cirrhosis. Ten cases of chronic hepatitis C, 9 cases of extrahepatic biliary obstruction, and 10 cases of normal liver were used as a control. Bcl-2 and mcl-1 are inhibitors of apoptosis, bcl-X, probably bcl-X"L in biliary epithelial cells, an inhibitor, and bax, a promoter of apoptosis. First, we clarified the distribution of bcl-2 familial proteins on the intrahepatic biliary tree in normal livers. Bcl-2 was detected in the interlobular bile ducts and bile ductules, but not in the large and septal bile ducts in all cases examined. Mcl-1, bcl-X, and bax were diffusely detectable at the any level of the intrahepatic biliary tree with a staining pattern that was diffuse and cytoplasmic. This distribution pattern was preserved in extrahepatic biliary obstruction. Bcl-2 expression was lost or markedly reduced in the damaged interlobular bile ducts in primary biliary cirrhosis, whereas the reduction was only focal or mild in the bile ducts with hepatitis-associated damage in chronic hepatitis C. Expression levels of mcl-1, bcl-X, and bax were similarly reduced to that of bcl-2 in these 2 diseases. These findings suggest that bax is not important as a proapoptotic factor in the damaged bile ducts and that downregulation of bcl-2 and mcl-1, and probably that of bcl-X"L, leads to a decrease in the threshold of apoptosis and increase in the vulnerability to apoptotic stimuli in these bile ducts, followed by the progressive apoptotic loss of interlobular bile ducts, in primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) and graft-versus-host disease (GVHD) are thought to have common immunopathologic features and previous studies have reported that 5.2 to 81% of patients with chronic GVHD after allogeneic hematopoietic cell transplant have anti-mitochondrial antibodies (AMA). We studied a total of 89 patients with chronic GVHD and 60 controls for AMA reactivity by ELISA and immunoblotting using recombinant PDC-E2, BCOADC-E2, and OGDC-E2, immunoblotting of beef heart mitochondrial proteins, and reactivity to nuclei, smooth muscle (ASMA), ribonucleoprotein JO-1, extractable nuclear antigen, nuclear proteins SSA/SSB, ribonucleic P proteinase III, cardiolipin (ACA), liver kidney microsomal, thyroid microsomal, myeloperoxidase, and the reactivity of rheumatoid factor. A subset of 60 chronic GVHD sera were tested for reactivity to gp210 and LBR. Finally, liver tissue from patients with chronic GVHD and PBC was studied by immunohistochemistry to determine whether there was comparable abnormal apical staining of biliary epithelial cells using PDC-E2-specific monoclonal antibodies. Surprisingly, there were no AMA found in the sera from the 89 patients with chronic GVHD. Review of published data on AMA in GVHD suggests that previous results were primarily false positives. In contrast, sera from the patients with GVHD did have a variety of other autoantibodies and, in particular, 20/89 (22.4%) positive ANA, 23/89 (25.8%) positive ASMA, and 9/89 (10.1%) positive ACA. The other autoantibodies assayed were not statistically different from controls. Finally, abnormal biliary epithelial luminal staining of bile ducts was found, as expected, in liver tissue of patients with PBC but was absent in chronic GVHD.

Borderline hepatocellular nodules (BHN), atypical adenomatous hyperplasia, macroregenerative nodule type II or dysplastic nodules in the cirrhotic liver are considered to be important prcancerous lesions transforming to hepatocellular carcinoma (HCC). In order to evaluate the uni- or multicentric origin of BHN and HCC arising from BN, we surveyed 30 cirrhotic livers with BHNs that had been surgically resected or autopsied during 1973–1993. Among the 30 cirrhotic livers with BHNs, two or more BHNs were present in a single cirrhotic liver in 10 (33%) cases, while only one BHN was present in a single cirrhotic liver in the remaining 20 (67%) cases. The mean number of BHN in a cirrhotic liver with multiple BHNs was 3.5. Carcinomatous foci were present within BHN in 6 (60%) of the 10 cirrhotic livers with multiple BHNs, while they were present in 4 (20%) of the 20 cirrhotic livers with a single BHN; this difference was statistically significant (P<0.05). Coexistance of HCC was noted in 8 (80%) of the 10 cirrhotic livers with multiple BHNs, and in 3 (15%) of the 20 cirrhotic livers with a single BHN; this difference was statistically significant (P<0.01). There were no significant differences in age, sex, aetiology and morphology between cirrhotic livers with multiple BHNs and those with a single BHN. These data suggest that BHN and HCC arising from BHN may be of multicentric origin.

We investigated the expression of transforming growth factor-alpha (TGF-a) and its receptor during human liver development and maturation, using immunohistochemistry. In the fetal liver, strong immunoreactivity for TGF-a and its receptor was noted in intrahepatic bile duct cells of various developmental stages; moderate immunoreactivity for TGF-a and mild immunoreactivity for TGF-a receptor were found in immature hepatocytes. In the postnatal liver, reactivity for TGF-a in hepatocytes decreased gradually and was negative or only weakly positive in the adult liver, while reactivity for TGF-a receptor in hepatocytes increased gradually and was strongly positive in the adult liver. In contrast, immunoreactivity of TGF-a and its receptor in intrahepatic bile duct cells persisted in the postnatal liver and was positive in the adult liver. These data suggest that the system of TGF-a and its receptor has an important role in the proliferation and differentiation of intrahepatic biliary cells and hepatocytes in the fetal liver. The decreasing expression of TGF-a in hepatocytes in the postnatal liver may indicate that proliferative activity of hepatocytes gradually decreases with liver maturation. The presence of TGF-a and its receptor in intrahepatic bile ducts in the postnatal liver suggests that the system of TGF-a and TGF-a receptor is operative postnatally.

Background & Aims: Recent advances in imaging modalities allow the identification of borderline hepatocellular nodules that have the potential for malignant transformation. The aim of this study was to elucidate histological predictive features of borderline nodules by needle biopsy for the evolution to hepatocellular carcinoma (HCC). Methods: Thirty-four hepatocellular nodules diagnosed by needle biopsy were followed up for more than 6 months. Several histological parameters of these nodules that were related to malignant transformation were evaluated. Results: During the follow-up periods (median, 35 months), 5 of 34 nodules evolved to HCC during a follow-up of 6-15 months. Significant prognostic features of malignant transformation were an increased ratio of nuclear density of >1.5, clear cell change, small cell dysplasia, and fatty change of the hepatocytes. In multivariate analysis, an increased ratio of nuclear density of >1.5 and clear cell change were independent. Conclusions: A nodule with an increased ratio of nuclear density, clear cell change, small cell dysplasia, and fatty change should be recognized to be a high risk for evolution to HCC. Particularly, the former two were independent prognostic factors for malignant transformation. GASTROENTEROLOGY 1998;115:1216-1222

Abstract:  There is evidence that mast cells are involved in a number of pathophysiological processes. The significance of mast cells in hepatic fibrosis was examined in 28 patients with histologically normal livers, 34 with acute liver diseases, 51 with chronic liver diseases, and 59 with cholestatic biliary diseases, using immunostaining of the mast cell-specific proteinase, tryptase. Mast cells that were positive for tryptase and for chymase were significantly increased in frequency in fibrotic portal tracts and fibrous septa, particularly in cholestatic/biliary diseases. Mast cells were also increased in frequency around the fibrotic septal and intrahepatic large bile ducts and peribiliary glands of biliary diseases. However, they were less common or even rare in the sclerotic bile ducts and in scarred portal or septal fibrosis. More than half of these more numerous mast cells were positive for histamine, and some were also positive for basic fibroblast growth factor. These two substances were detectable by immunoelectron microscopic in the cytoplasmic granules of mast cells. In contrast, mast cell numbers were not significantly increased in acute viral or drug-induced hepatitis, or in zones 2 and 3 of the hepatic acinus with respect to pericellular and perivenular fibrosis in chronic liver diseases. These findings suggest that mast cells increase in number in cholestatic/biliary diseases, and to a lesser degree in chronic liver diseases, and are involved in the active fibrous enlargement of portal tract and fibrous septa formation and also in the fibrosis of the intrahepatic bile ducts as they display fibrosis-promoting factors such as tryptase, fibroblast growth factor and histamine.

We report a carcinosarcoma arising in a nonparasitic simple cyst of the liver. Sequential imaging findings revealed that the tumour originated in a hepatic cyst and was composed of well-differentiated tubular adenocarcinoma and high-grade spindle cell sarcoma without apparent transition between the two. At the margin of the tumour, a single layer of benign cuboidal epithelium and outer fibrous bands were present, suggesting that the tumour had arisen from a nonparasitic simple cyst of the liver. Immunohistochemically, carcinoma cells were positive for cytokeratins, epithelial membrane antigen and CA 19-9 and negative for vimentin, while sarcomatous cells were positive for vimentin and negative for cytokeratins, epithelial membrane antigen and CA 19-9. Sarcomatous cells did not show any immunophenotypic features of smooth muscle cells, striated muscle cells, histiocytes, lipocytes, nerve cells, Schwann cells or endothelial cells. Ultrastructurally, no specific differentiation was seen in the sarcomatous cells.

Morphologic changes of the intrahepatic bile ducts after induction of bile stasis and bacterial infection of the biliary tract in two lobes of the liver in mongrel dogs were studied to examine the pathophysiology of hepatolithiasis. Three groups of dogs were prepared by cannulation of the bile duct branch draining the left lateral lobes of the liver and were treated as follows: in group 1 the cannula was clamped after injection of 107 Escherichia coli (aerobic bacteria) and 107 Bacteroides fragilis (anaerobic bacteria) organisms; in group 2 the cannula was clamped after injection of E. coli only; and in group 3 the cannula was clamped without injection of bacteria. Three months later the livers of killed dogs were examined. In group 1 epithelial adenomatous hyperplasia was noted in association with chronic cholangitis characterized by moderate to severe periductal fibrosis with a large number of inflammatory cells. In group 2 periductal fibrosis was severe, but epithelial hyperplasia was found to a much lesser degree than in group 1. In group 3 no periductal fibrosis or epithelial adenomatous hyperplasia was demonstrated. These findings suggest that adenomatous hyperplasia of the bile duct epithelium may be caused by bacterial infection of the biliary tract in combination with bile stasis.

The expression and localization of the pancreatic and salivary isozymes of alpha-amylase in the intrahepatic biliary epithelium and hepatocytes were examined by the immunohistochemical method with polyclonal and monoclonal antibodies in 45 normal autopsied human livers. Immunoelectron microscopic studies with the protein A-gold method were performed with the monoclonal antibodies (MAb) on seven of the livers. The intrahepatic biliary system was divided into large ducts, septal ducts, interlobular ducts, bile ductules, and peribiliary glands. Immunohistochemically, pancreatic isozyme was observed in the supranuclear cytoplasm of the epithelium of large ducts, septal ducts, and peribiliary glands in almost all livers. Interlobular ducts expressed pancreatic isozyme in only four (9%) livers. Bile ductules and hepatocytes were negative for pancreatic isozyme in all cases. Expression of salivary isozyme was observed in the supranuclear cytoplasm of the epithelium of large ducts, septal ducts, interlobular ducts, bile ductules, and peribiliary glands in almost all livers, although the expression in interlobular ducts and bile ductules was weak. Hepatocytes were weakly positive for salivary isozyme. Immunoelectron microscopy revealed that both pancreatic and salivary isozymes were located in the supranuclear cytoplasm of the epithelium of large ducts, septal ducts, and peribiliary glands, and that hepatocytes had no pancreatic isozyme but contained salivary isozyme. These data suggest that pancreatic and salivary isozymes of alpha-amylase are produced by the intrahepatic biliary epithelium and secreted into intrahepatic biliary lumens, and that they may play an important role in the physiology of the intrahepatic biliary tree and hepatic bile. It is also suggested that hepatocytes produce a small amount of salivary alpha-amylase that may be secreted into the biliary tree.

We previously developed a model in which rabbit gallbladder epithelial cells in collagen gels proliferated and formed multicellular spherical cysts after 2 to 4 days,. In the present study, we examined in depth the dynamic processes of loss and reestablisment of cell polarity of rabbit gallbladder epithelial cells isolated and cultured in collagen gel. Six hours after being placed in culture, the isolated epithelial cells had lost the morphologic features and phenotypic markers inherent in the in vivo gallbladder mucosa, and autophagic vacuoles appeared transiently, reflecting epithelial cell injury, or remodelling, or both. After 12 hours, mucin dots appeared in clumps of epithelial cells and gradually became larger, and the epithelial cell clumps were transformed into multicellular cysts after 1 to 2 days. The luminal surfaces of the mucin dots (intracytoplasmic inclusions or small lumens sealed by several epithelial cells) and multicellular cysts were covered by microvilli and presented profiles of mucus glycoprotein and carbohydrate residues shared with the in vivo gallbladder mucosa. The presence ofcellular adhesion structures and the distribution ofcellular organelles toward the luminal surface implied the reestablishment ofepithelial cell polarity. The addition ofcytochalasin B induced many mucin-positive cytoplasmic inclusions covered by microvilli in the epithelial cells ofthe multicellular cysts, while the addition of transforming growth factor beta 1 promoted maturation of the multicellular cysts. This short term culture is useful for the analysis of the polarity of biliary epithelial cells and for examining disorders in this polarity.

The abnormal expression of blood group related antigens has been reported in many malignant tumours; however, such expression in cholangiocarcinoma has not been examined systematically. The expression of blood group‐related antigens (A, B, H, Lewisa, Lewisb, Lewisx, Lewisy, carbohydrate antigen 19‐9 and carcinoembryonic antigen) was investigated immunohistochemically in 75 cases of cholangiocarcinoma (31 peripheral type and 44 hilar type). In non‐neoplastic bile ducts, A, B, and H antigens were expressed in large bile ducts, while Lewisa,b,yand carbohydrate antigen 19‐9 were variably expressed in both large and small bile ducts. Lewisxand carcinoembryonic antigen was not found in non‐neoplastic bile ducts. In cholangiocarcinomas, A, B, and H, antigens were more frequent in the hilar type than in the peripheral type, although the difference was not significant. The expression of the blood‐group related antigens, particularly A, Lewisa,b,y, carcinoembryonic antigen, and carbohydrate antigen 19‐9, was frequent in the tumour cells in well differentiated adenocarcinomas, while their immunoreactivity was less frequent in poorly differentiated adenocarcinomas. The superanuclear and luminal expression of these antigens in carcinoma cells was frequent in well differentiated adenocarcinomas, and the diffuse, cell membranous and stromal expression of these antigens was relatively frequent in poorly differentiated adenocarcinomas and adenosquamous carcinoma. The A, B, and H immunoreactivity of both non‐neoplastic bile ducts and cholangiocarcinomas was consistent with the host blood group type. These findings suggest that both the expression and intracellular distribution of blood group‐related antigens in cholangiocarcinoma are related to the differentiation of cholangiocarcinoma and, possibly, to the parent structure.

Accumulating evidence implicates tumor necrosis factor (TNF) and Fas systems in liver injury, although the interaction between these two systems remains to be investigated. In this study, we examined Propionibacterium acnes-primed TNF receptor p55-deficient (TNFRp55-/-) or Fas-deficient MRL/MpJ Lpr/Lpr mice challenged with lipopolysaccharide (LPS). Priming with P. acnes caused mononuclear cell infiltration into the hepatic lobules and granuloma formation in the livers of TNFRp55 wild-type mice. Subsequent LPS challenge caused massive liver injury and a marked increase in transaminase levels, leading to acute lethality in control wild-type mice. In contrast, the same treatment caused few pathological changes in livers of TNFRp55-/- mice, and all animals survived. P. acnes and subsequent LPS challenge induced granuloma formation and apoptotic changes, respectively, in livers of MRL/MpJ Lpr/Lpr mice. However, liver injury was 50% of that in control MRL/MpJ +/+ mice, suggesting some role of the Fas-Fas ligand system in this liver injury model. On the other hand, an agonistic anti-Fas antibody caused massive apoptosis and hemorrhagic changes of the liver without any priming with P. acnes, leading to death in both TNFRp55-/- and control wild-type mice. These results suggest that TNFRp55 but not Fas was involved in P. acnes-induced granuloma formation as well as subsequent LPS-induced liver injury and that TNFRp55 and Fas independently induced apoptosis of hepatocytes in vivo.

Acute lethality was induced in rabbits by the sequential injection of Propionibacterium acnes and lipopolysaccharide (LPS). P. acnes induced the infiltration of inflammatory cells into the liver lobules during the early phase, and LPS in the late phase caused death in association with pathological changes mimicking hepatocellular necrosis or degeneration around infiltrated mononuclear cells and fibrin deposition in the liver, lung, and kidney, suggestive of a systemic Schwartzman-like reaction. These pathological changes were accompanied by the elevation of plasma tumor necrosis factor (TNF) and interleukin-8 (IL-8) levels. A neutralizing antibody to a leukocyte adhesion molecule, integrin beta 2 (CD18), administered at the time of LPS challenge, prevented reduced the elevation of plasma TNF and IL-8 levels. An anti-TNF alpha antibody but not an anti-IL-8 mediator in this model. These results indicate that CD18 is critically involved in vivo in activating leukocytes to produce cytokines in response to LPS.

Acute lethality was induced in rabbits by the sequential injection of Propionibacterium acnes and lipopolysaccharide (LPS). P. acnes induced the infiltration of inflammatory cells into the liver lobules during the early phase, and LPS in the late phase caused death in association with pathological changes mimicking hepatocellular necrosis or degeneration around infiltrated mononuclear cells and fibrin deposition in the liver, lung, and kidney, suggestive of a systemic Schwartzman-like reaction. These pathological changes were accompanied by the elevation of plasma tumor necrosis factor (TNF) and interleukin-8 (IL-8) levels. A neutralizing antibody to a leukocyte adhesion molecule, integrin beta 2 (CD18), administered at the time of LPS challenge, prevented reduced the elevation of plasma TNF and IL-8 levels. An anti-TNF alpha antibody but not an anti-IL-8 mediator in this model. These results indicate that CD18 is critically involved in vivo in activating leukocytes to produce cytokines in response to LPS.

Accumulating evidence implicates tumor necrosis factor (TNF) and Fas systems in liver injury, although the interaction between these two systems remains to be investigated. In this study, we examined Propionibacterium acnes-primed TNF receptor p55-deficient (TNFRp55-/-) or Fas-deficient MRL/MpJ Lpr/Lpr mice challenged with lipopolysaccharide (LPS). Priming with P. acnes caused mononuclear cell infiltration into the hepatic lobules and granuloma formation in the livers of TNFRp55 wild-type mice. Subsequent LPS challenge caused massive liver injury and a marked increase in transaminase levels, leading to acute lethality in control wild-type mice. In contrast, the same treatment caused few pathological changes in livers of TNFRp55-/- mice, and all animals survived. P. acnes and subsequent LPS challenge induced granuloma formation and apoptotic changes, respectively, in livers of MRL/MpJ Lpr/Lpr mice. However, liver injury was 50% of that in control MRL/MpJ +/+ mice, suggesting some role of the Fas-Fas ligand system in this liver injury model. On the other hand, an agonistic anti-Fas antibody caused massive apoptosis and hemorrhagic changes of the liver without any priming with P. acnes, leading to death in both TNFRp55-/- and control wild-type mice. These results suggest that TNFRp55 but not Fas was involved in P. acnes-induced granuloma formation as well as subsequent LPS-induced liver injury and that TNFRp55 and Fas independently induced apoptosis of hepatocytes in vivo.