Patterns of splenic arterial enhancement on computed tomography scan are related to portal venous hypertension.

OBJECTIVES: We have previously shown that patterns of splenic arterial enhancement on computed tomography scan change following liver transplantation. We suggested that this is related to changes in portal venous pressure. The aim of this study was to see if similar patterns occur in patients with and without portal hypertension and in patients before and after portal systemic shunts (transjugular portosystemic shunts). METHODS: We evaluated contrast enhanced computed tomography scans in patients being evaluated for liver disease and compared those from patients with and without portal hypertension. In addition we evaluated patients who had computed tomography scans before and after transjugular portosystemic shunts shunts. Splenic arterial enhancement was evaluated using Hounsfield units (pixel counts). RESULTS: Twenty-four patients with clinically significant portal hypertension were compared to 91 without. Mean splenic pixel count was significantly lower in patients with clinically significant portal hypertension (88.2 ± 17.7 vs. 115.2 ± 21.0; m ± SD, P < 0.01). Computed tomography scans were available in 18 patients pre- and post-transjugular portosystemic shunts. Pixel counts were significantly higher in the post-transjugular portosystemic shunts scans (99.7 ± 20.9 vs. 88.9 ± 26.3; P < 0.05). CONCLUSION: This study supports the hypothesis that changes in portal venous pressure are related to changes in splenic arterial enhancement. We suggest that this reflects changes in the splenic micro-circulation. This mechanism may be part of the innate immune response and may also be important in the pathogenesis of hypersplenism.

The portal vein as a distinct immunological compartment - A comprehensive immune phenotyping study.

Advanced liver diseases are associated with impaired intestinal barrier function, which results in bacterial influx via the portal vein to the liver, causing hepatic and systemic inflammation. Little is known about possible concomitant trafficking of immune cells from the intestines to the liver. We therefore performed a comprehensive immunophenotyping study of the portal venous versus peripheral blood compartment in patients with liver cirrhosis who received a transjugular intrahepatic portosystemic stent shunt (TIPS). Our analysis suggests that the portal vein constitutes a distinct immunological compartment resembling that of the intestines, at least in patients with advanced liver cirrhosis. In detail, significantly lower frequencies of naïve CD4+ T cells, monocytes, dendritic cells and Vδ2 T cells were observed in the portal vein, whereas frequencies of activated CD4+ and CD8+ T cells, as well as of mucosa-associated Vδ1 T cells were significantly higher in portal venous compared to peripheral blood. In conclusion, our data raises interesting questions, e.g. whether liver cirrhosis-associated chronic inflammation of the intestines and portal hypertension promote an influx of activated intestinal immune cells like γδ T cells into the liver.

The differential organogenesis and functionality of two liver-draining lymph nodes in mice.

The liver is an immunological organ. However, fundamental knowledge concerning liver-draining lymph nodes (LNs), which have been newly identified in mice as the portal and celiac LNs, is still lacking. Here, we revealed that the portal LN and celiac LN drain liver lymph through different lymphatic vessels. Although both the portal LN and celiac LN possess typical structures, they have different cell compositions. Interestingly, these two LNs form at different times during fetal development. Moreover, the organogenesis of the celiac LN, but not the portal LN, is controlled by the transcription factor NFIL3. Furthermore, the portal LN and celiac LN also perform different functions. The celiac LN is the predominant site of liver antiviral immune responses, whereas the portal LN functions in the in situ induction of dietary antigen-specific regulatory T cells. In conclusion, the portal LN and celiac LN are two independent liver-draining LNs with different organogenesis histories and separate functions in maintaining immune homeostasis in the liver.

Portal inflammation is independently associated with fibrosis and metabolic syndrome in pediatric nonalcoholic fatty liver disease.

UNLABELLED: Pediatric nonalcoholic fatty liver disease (NAFLD) histology demonstrates variable amounts of portal inflammation, which may be associated with more severe liver disease and fibrosis. We assessed the relationship between portal inflammation, hepatic fibrosis, and the metabolic syndrome in pediatric NAFLD. Children with biopsy-proven NAFLD were eligible for inclusion. Histology was assessed using Kleiner fibrosis stage and the Nonalcoholic Steatohepatitis Clinical Research Network system for portal inflammation. Patients were divided by histology into type 1, type 2, and overlap NAFLD. Multivariable ordinal logistic regression was used to determine factors associated with fibrosis and portal inflammation. The 430 Caucasian children were divided into 52 with type 1, 95 with type 2, and 283 with overlap NAFLD. Those with type 2 had a more severe metabolic phenotype, with higher body mass index z score (2.0 versus 1.6, P < 0.0001), waist circumference centile (96th versus 90th, P < 0.0001), and triglycerides (84 versus 77 mg/dL, P = 0.01) and lower high-density lipoprotein (46 versus 60 mg/dL, P = 0.004) than those with type 1. Similarly, those with overlap NAFLD had a more severe phenotype. Stage 2-3 fibrosis was present in 69/283 (24%) with overlap NAFLD. Portal inflammation was associated with stage 2-3 fibrosis on multivariable analysis (95% confidence interval 1.4-5.2, odds ratio = 3.7). Waist circumference centile was associated with portal inflammation (95% confidence interval 1.2-3.4, odds ratio = 2.0). CONCLUSION: Portal inflammation is associated with more advanced pediatric NAFLD and features of the metabolic syndrome.

Positive C4d staining of the portal vein endothelium in the liver of patients with biliary atresia: a role of humoral immunity in ongoing liver fibrosis.

PURPOSE: This study aimed to clarify the role of complement activation in fibrogenesis in BA. METHODS: In total, 27 paraffin-embedded liver biopsy samples were immunohistochemically analyzed using C4d polyclonal antibody, vascular cell adhesion molecule-1 (VCAM-1), and CD45. The liver samples were obtained from 25 patients during Kasai operation, and two additional specimens were obtained from 2 patients by needle biopsy later at the time of liver function deterioration. The degree of liver fibrosis was histologically graded 1-3. RESULTS: Among the 25 samples, 9 showed C4d-positive immunostaining localized on the endothelia of a few portal veins in the portal tract. The degree of fibrosis was correlated with C4d staining (p = 0.025). The age at Kasai operation correlated with the degree of fibrosis and the C4d positivity. Two needle biopsy samples were positive for C4d. Among 13 samples submitted for VCAM-1 staining, 2 negative samples were C4d negative and all positive C4d samples were VCAM-1 positive with CD45 mononuclear cell infiltration. CONCLUSION: These findings suggest that ongoing cirrhosis could be a result of progressive "vasculopathy" of the portal vein caused by humoral and cell-mediated immune interaction.

Idiopathic non cirrhotic portal hypertension and spleno-portal axis abnormalities in patients with severe primary antibody deficiencies.

BACKGROUND AND AIM: Portal hypertension has been reported in association with acquired and primary immune deficiencies without a comprehensive description of associated spleno-portal axis abnormalities. Pathological mechanisms are poorly defined. METHODS: Observational, single centre study with the aim of assessing the prevalence of spleno-portal axis abnormalities in an unselected cohort of 123 patients with primary antibody deficiencies and without known causes of liver diseases regularly followed up for a mean time of 18 ± 14 years. A cumulative period of 1867 patients-year was analysed. Clinical and immunological data, abdominal ultrasounds, CT scans, and endoscopy features were included in the analysis. RESULTS: Twenty-five percent of patients with primary antibody deficiencies had signs of portal vein enlargement but only 4% of them had portal hypertension, with portal systemic collaterals. Liver biopsies showed liver sinusoids congestive dilatation, endothelization, and micronodularity fulfilling the criteria for noncirrhotic portal hypertension. Patients with portal vein enlargement had severe clinical and immunological phenotypes. CONCLUSIONS: In primary antibody deficient patients, infections, inflammations, splenomegaly, increased blood venous flow, and lymphocyte abnormalities contribute to establishment of liver damage possibly leading to noncirrhotic portal hypertension. Patients with primary antibody deficiency should be considered a good model to give insight into the pathological mechanisms underlying noncirrhotic portal hypertension.

Binding affinity of anti-xylitol antibodies to canine hepatic vessels.

Xylitol is used as a sugar substitute in food products. Dogs have been reported to experience lethal liver injury after accidental ingestion of xylitol. Because liver injury may be a serious consequence of canine immune-mediated reactions, antibodies produced against xylitol may attack the liver. Therefore, in the present study, we evaluated whether binding sites for xylitol antibodies are located at the liver or not. Anti-xylitol antibodies were generated by immunization of rabbits with a xylose-bovine serum albumin conjugate. Immunohistological examination showed that binding sites for the anti-xylitol antibodies were located in the hepatic arteries and the portal veins. Western blotting analyses by using a canine liver homogenate showed 4 protein bands with different molecular weights which reacted with anti-xylitol antibodies. Therefore, binding of anti-xylitol antibodies to the vessels may be the first step in an immune-mediated pathogenic response in xylitol toxicity. Further studies are necessary to determine the effects of anti-xylitol antibodies on the liver in the pathogenesis of xylitol toxicity.

Sinusoidal C4d deposits in liver allografts indicate an antibody-mediated response: diagnostic considerations in the evaluation of liver allografts.

There is a paucity of data concerning the correlation of complement component 4d (C4d) staining in liver allografts and antibody-mediated rejection. Data about the location and character of C4d deposits in native and allograft liver tissues are inconsistent. We performed C4d immunofluorescence (IF) on 141 fresh-frozen liver allograft biopsy samples and native livers, documented the pattern of C4d IF staining, and correlated the findings with the presence of donor-specific alloantibodies (DSAs). A linear/granular sinusoidal pattern of C4d IF was noted in 18 of 28 biopsy samples obtained after transplantation from patients with positive crossmatch and detectable donor-specific alloantibody (pos-XM/DSA) findings. None of the 59 tested biopsy samples from patients with negative crossmatch and detectable donor-specific alloantibody (neg-XM/DSA) findings were C4d-positive (P < 0.001). No significant association was found between pos-XM/DSA and C4d IF staining in other nonsinusoidal liver compartments. To compare the results of sinusoidal C4d staining with IF and 2 immunohistochemistry (IHC) techniques, C4d IHC was performed on 19 liver allograft biopsy samples in which a sinusoidal pattern of C4d IF had been noted. Sinusoidal C4d IHC findings were negative for 17 of the 19 biopsy samples; 2 showed weak and focal staining, and both patients had pos-XM/DSA findings. Portal vein endothelium staining was present in only 1 IF-stained biopsy sample (pos-XM/DSA) but in 11 IHC-stained biopsy samples (2 of the 11 samples had neg-XM/DSA findings). We conclude that sinusoidal C4d deposits detected by IF in frozen tissue samples from liver allograft recipients correlate with the presence of DSAs and an antibody-mediated alloresponse. These observations are similar to findings reported for other solid organ transplants and can provide relevant information for patient management. Further validation of IHC techniques for C4d detection in liver allograft tissue is required.

Hepatic microvascular pressure during anaphylactic shock in anesthetized rats.

OBJECTIVE: Hepatic venoconstriction plays a significant role in anaphylactic hypotension in anesthetized rats. The purpose of this study is to determine whether the primary site of anaphylactic venoconstriction in the liver venous circulation occurs prior to or distal to the sinusoidal capillaries. We also determined whether the hepatic blood volume is increased during anaphylactic hypotension. METHODS: We measured, using a servo-null micropipette pressure-measuring system, the hepatic venular transmural pressure (P micro hv) at the liver surface of anesthetized rats sensitized with the antigen of ovalbumin (1 mg). We also measured the liver lobe thickness, using the ultrasonic crystal dimension measuring system. Anaphylactic hypotension was induced by an intravenous injection of 0.6 mg ovalbumin. RESULTS: When the antigen was injected, the systemic arterial pressure decreased profoundly from 118+/-9 to 45+/-4 mm Hg, which was accompanied by an increase in Ppv and P micro hv: P micro hv only transiently increased from 3.1+/-0.9 to 8.8+/-1.5 cm H(2)O at 1 min and then rapidly returned to the baseline within 2 min, when Ppv continued to increase and reached the peak of 36+/-7 cm H(2)O at 3.5 min after antigen. This greater increase in Ppv-to-P micro hv gradient than that in P micro hv-to-Pcv gradient after antigen indicated that the constriction of the portal veins and the sinusoids much predominates over that of the hepatic veins. Along with this hepatic pre- and sinusoidal constriction, the liver lobe thickness significantly decreased by 4% after antigen. CONCLUSION: Pre-sinusoidal constriction during anaphylactic shock in anaesthetized rats increased the portal venous pressure while the hepatic venular pressure only increased slightly and transiently. This predominant pre-sinusoidal constriction is accompanied by a decrease in liver volume.

Increased CD4+CD25+Foxp3+ regulatory T cells in tolerance induced by portal venous injection.

BACKGROUND: A portal vein injection (PVI) of allogeneic donor antigen is known to prolong the survival of a subsequently transplanted allograft; however, the underlying mechanism remains to be clarified. METHODS: Irradiated C57BL/6 (B6) splenocytes were injected into BALB/c mice via the portal vein. Seven days after injection, the proportions of CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) cells were determined in the blood, liver, and spleen. CD4(+) and CD8(+) T cells were isolated from BALB/c mice that received PVI of B6 splenocytes (PVI mice), adoptively transferred into recipient BALB/c mice 1 day before B6 or third-party C3H heart transplantation, and graft survival was compared. B6 or C3H heart allografts were implanted into anti-CD25 monoclonal antibody (mAb)-treated PVI and untreated PVI mice, and graft survivals were compared. The percentages of CD4(+)CD25(+)Foxp3(+) Treg, cytokine profiles, and ratios of apoptosis were determined in anti-CD25 mAb-treated PVI and untreated PVI mice. RESULTS: PVI of allogeneic cells induced antigen-specific tolerance and increased the percentage of CD4(+)CD25(+)Foxp3(+) Treg. Adoptive transfer of CD4(+) T cells, but not CD8(+) T cells, from PVI mice prolonged B6 heart allograft survival. Depletion of CD4(+)CD25(+) T cells prevented the induction of tolerance and decreased the percentage of CD4(+)CD25(+)Foxp3(+) Treg in the CD3(+) T-cell pool, and thus was associated with decreased production of interleukin (IL)-4 and apoptosis of T cells. CONCLUSION: Increased CD4(+)CD25(+)Foxp3(+) Treg play an important role in portal vein tolerance induction, at least partly via increasing the production of IL-4 and decreasing apoptosis of T cells.

Vascular deposition of complement C4d is increased in liver allografts with chronic rejection.

BACKGROUND: Complement protein C4d has been used as a marker of antibody mediated rejection in kidney allografts. C4d has been shown to be deposited also in chronic kidney allograft rejection, and frequently in acute liver allograft rejection. In chronic liver allograft rejection there is limited data of C4d positivity. METHODS: 7 liver allografts explanted at retransplantation due to chronic rejection were examined for expression of C4d. Immunoperoxidase technique on frozen sections was used. The "zero" biopsies of the same livers at the first transplantation served as controls. RESULTS: Expression of C4d was significantly increased in portal and central veins as well as in the portal stroma of the grafts with chronic rejection when compared to the expression at implantation of the graft. CONCLUSION: The complement system and anti-donor antibodies may contribute to the process of chronic allograft rejection in the liver.

Comparison of the portal vein and kidney subcapsule as sites for primate islet autotransplantation.

To date, the portal vein has been the primary site for clinical islet transplantation. Despite success, potential complications such as portal vein thrombosis still exist. The kidney subcapsule has been used successfully in rodent models of islet transplantation. We hypothesized that the kidney subcapsule as a site for islet transplantation in the nonhuman primate model would be as effective as the portal vein. Diabetes was induced in the primate Macaca fascicularis via a total pancreatectomy. Animals were kept under anesthesia during the isolation procedure. Islet isolation was performed using intraductal infusion with Liberase HI and mechanical digestion in the Ricordi chamber, and were purified using a continuous Ficoll gradient. Purified islets were autotransplanted either into the portal vein (n = 6) or the left kidney subcapsule (n = 5) of pancreatectomized animals. Intravenous glucose tolerance tests were performed prior to pancreatectomy and 10 days following transplantation. Three animals underwent pancreatectomy and served as diabetic controls. Of the six animals receiving islets in the portal vein, one developed portal vein thrombosis. All remaining autotransplanted animals in this group remained normoglycemic with glucose-induced insulin secretion that was not different from that prior to pancreatectomy. Of the five animals undergoing transplantation into the kidney subcapsule, only one maintained normoglycemia and elicited insulin secretion in response to glucose stimulation. The other four animals remained hyperglycemic. We conclude that the portal vein is superior to the kidney subcapsule as a site for islet transplantation in nonhuman primates 10 days posttransplantation.

Periportal and sinusoidal liver dendritic cells suppressing T helper type 1-mediated hepatitis.

BACKGROUND: Recently, we found that portal vein tolerance is associated with generation of Th2 cells and apoptosis of Th1 cells in the liver, which is regulated by antigen (Ag)-presenting dendritic cells (DCs) in the periportal area and sinusoids. AIM: In this study, we tested whether the periportal and sinusoidal DCs, which were loaded with an Ag in vivo, can inhibit liver injury caused by Th1 cells activated by the Ag administered systemically. METHODS: Ag-specific hepatitis model was created by adoptively transferring ovalbumin (OVA)-specific CD4(+) T cells to BALB/c mice and venous injection of OVA-containing liposomes. Liver CD11c(+) cells obtained from mice fed OVA were then transferred into these mice. RESULTS: The transfer of liver CD11c(+) cells from OVA-fed mice completely inhibited hepatic injury, which was associated with apoptosis of OVA-specific CD4(+) T cells and emergence of Th2 cells in the liver. Transfer of CD11c(+) cells and subcutaneous OVA challenge led to enhancement of OVA-specific IgE Ab as well as Th2 cytokine responses in the recipient mice. CONCLUSIONS: Periportal and sinusoidal DCs loaded with an Ag in the portal vein can induce Th2 response in the liver and prevent hepatic injury caused by Th1 cells.

Nomadic or sessile: can Kupffer cells function as portals for malaria sporozoites to the liver?

The initial site of replication for Plasmodium parasites in mammalian hosts are hepatocytes, cells that offer unique advantages for the extensive parasite replication occurring prior to the erythrocytic phase of the life cycle. The liver is the metabolic centre of the body and has an unusual relationship to the immune system. However, to reach hepatocytes, sporozoites must cross the sinusoidal barrier, composed of specialized endothelia and Kupffer cells, the resident macrophages of the liver. Mounting evidence suggests that, instead of taking what would seem a safer route through endothelia, the parasites traverse Kupffer cells yet suffer no harm. Kupffer cells have a broad range of responses towards incoming microorganisms, toxins and antigens which depend on the nature of the intruder, the experimental conditions and the environmental circumstances. Kupffer cells may become activated or remain anergic, produce pro- or anti-inflammatory mediators. Consequently, outcomes are diverse and include development of immunity or tolerance, parenchymal necrosis or regeneration, chronic cirrhotic transformation or acute liver failure. Here we review data concerning the unique structural and functional characteristics of Kupffer cells and their interactions with Plasmodium sporozoites in the context of a model in which these hepatic macrophages function as the sporozoite gate to the liver.

Prognostic significance of CEA levels and detection of CEA mRNA in draining venous blood in patients with colorectal cancer.

BACKGROUND AND OBJECTIVES: The aims of this study were to determine carcinoembryonic antigen (CEA) levels and incidence of tumor cells using the RT-PCR technique in draining venous blood of patients with colorectal cancer, correlate the results with various histopathologic factors and determine their significance as prognostic factors. METHODS: From 1995 to 2000, 108 patients with adenocarcinoma of the colon or rectum, underwent curative surgery and enrolled in this prospective study. RESULTS: The 5-year survival group had significantly lower portal CEA levels compared to the hepatic metastasis outcome group. CEA mRNA was positive in the draining venous blood from 12 (11.1%) out of 108 patients included in the study. The rate of positive tumor cell detection in portal blood was significantly higher in the hepatic metastasis outcome group than in the 5-year survival and recurrence group. The proportion of patients with portal CEA > or =5 ng/ml was greater in patients with higher stage than in patients with lower stage. CONCLUSIONS: Positive CEA mRNA in draining venous blood predicted hepatic metastases and local recurrence with accuracy over 80% but with low sensitivity of 30% and 9%, respectively. Moreover, CEA level was a sensitive indicator in hepatic metastases as sensitivity was 95% and a specific indicator in predicting 5-year survival with specificity 84%.

Allolymphocyte apoptosis induced by soluble liver specific antigen.

OBJECTIVE: To investigate the alloimmunogenicity of liver specific antigen and its effects on allolymphocytes. METHODS: Liver specific antigen isolated from inbred F344 rats was used as immunogen to immunize inbred Lew rats through different immunization pathways such as low-dose long-term hind footpad, high-dose portal vein and thymus immunization. Western blotting, DNA fragments gel electrophoresis, mixed lymphocyte culture (MLC) and mixed lymphocyte hepatocyte culture (MLHC) were employed to analyze the immune state after immunization. RESULTS: At the time point of sampling, different degree of specific low immunoresponses appeared in all immunized groups as well as cyclophosphamide (CY) treated group. Compared with group I, other groups expressed caspase-3 significantly as detected by using Western blotting. DNA fragment gel electrophoresis of splenocytes showed lymphocyte apoptosis. Compared with the group I, MLC of the experimental groups showed no significant changes except that of the group V, whereas MLHC decreased markedly (P<0.05). CONCLUSIONS: Liver specific antigen not only has alloimmunogenicity to induce alloimmunoreaction but induce antigen specific low immunoresponses and antigen specific lymphocyte apoptosis by high-dose or low-dose long-term immunization. It may be an important transplantation antigen that may lead to a novel way to liver transplantation immunotolerance.

Evidence for persistent expression of OX2 as a necessary component of prolonged renal allograft survival following portal vein immunization.

Following portal vein (pv) pretransplant immunization of C3H mice, there is an early (within 2 days) increase in expression of the molecule OX2 seen on host dendritic cells (DC), along with increased survival of C57BL/6 renal allografts transplanted within 24 h of pv immunization. In addition, there is a marked polarization in cytokine production from lymphocytes harvested from the transplanted animals, with preferential production of IL-4, IL-10, and TGFbeta on donor-specific restimulation in vitro, and decreased production of IL-2, IFN-gamma, and TNFalpha compared with non-pv-immunized control transplanted mice. Both the increased renal allograft survival and the altered cytokine production are abolished by infusion of anti-mouse OX2 monoclonal antibody (3B6), even when antibody infusion is begun as late as 10 days following transplantation. Quantitative PCR analysis independently shows that OX2 expression is increased in the spleen and liver of transplanted mice as late as 21 days following pv immunization. In vitro studies with an OX2:Fc immunoadhesion had suggested that immunosuppression induced by this soluble form of the OX2 molecule was dependent primarily upon an early (OX2-dependent) signal. This discrepancy between in vivo and in vitro data possibly reflects a role for OX2 in the in vivo recruitment of other (immunregulatory) cells. Consistent with this hypothesis, regardless of the time (posttransplantation) of in vivo infusion of anti-OX2 antibody, within 2 days we observed a decline in the functional activity of a previously characterized immunoregulatory gammadeltaTCR(+) cell population, which can be monitored by its ability to regulate cytokine production in vitro.