Defective immunoregulation in primary biliary cirrhosis: CD4+, Leu-8+ T cells have abnormal activation and suppressor function in vitro

Evidence of angiogenesis in primary biliary cirrhosis: an immunohistochemical descriptive study

BACKGROUND/AIMS

The intrahepatic inflammatory process occurring during primary biliary cirrhosis contributes to bile duct destruction, but the cellular and molecular pathways involved are largely unknown. Furthermore, additional pathogenetic mechanisms may exist. We aimed at evaluating the cellular infiltrate phenotype; the expression of lymphocyte activation, antigen recognition and cell-adhesion molecules; the occurrence of hepatic angiogenesis and the molecules involved.

METHODS

Immunohistochemical investigations were performed in frozen liver biopsy sections from primary biliary cirrhosis patients.

RESULTS

CD8+ and CD69+ T cells were predominant in inflammatory infiltrates around damaged cholangiocytes; beta2-microglobulin conformational epitope and intercellular adhesion molecule-1 expression were enhanced in bile ducts and hepatocytes. Inflamed portal areas showed vascular cell adhesion molecule-1 up-regulation; formation of tubule-like structures (neovessels) by endothelial cells expressing vascular endothelial-cadherin and CD-31; vascular endothelial growth factor expression in surrounding sinusoidal endothelial cells; and enhanced expression of angiopoietins 1 and 2, their receptor Tie-2 and endoglin, suggesting their involvement in new vascular structure formation.

CONCLUSIONS

The inflammatory infiltrate in primary biliary cirrhosis shows an increased reactivity for lymphocyte activation, antigen recognition and cell- and vascular-adhesion molecules. Additionally, intrahepatic angiogenesis occurs, involving vascular endothelial growth factor, angiopoietins 1 and 2, Tie-2 and endoglin in neovessel formation.

Immunohistochemical localization of antigen presenting cells in liver from patients with primary biliary cirrhosis; highly restricted distribution of CD83-positive activated dendritic cells

In order to have insights into the abnormal immune regulation in primary biliary cirrhosis (PBC), different types of antigen presenting cells (APC) were localized immunohistochemically in liver specimens from 26 patients with PBC and compared with the distributions of APC from 11 and 10 patients with chronic hepatitis C (CH-C) and large bile duct obstruction, respectively. In all diagnostic conditions, 30-90% of the infiltrating cells were positive for HLA DR. In PBC, the numbers of interdigitating cells (IDC) were significantly higher than the numbers of CD83-positive dendritic cells (DC) (34.0 +/- 38.8 vs. 5.5 +/- 7.1/specimen, mean +/- SD, p < 0.05). On the other hand, the numbers of IDC (14.2 +/- 20.0/specimen) and CD83-positive DC (7.9 +/- 8.7/specimen) were almost similar in CH-C (p > 0.05). Positive stainings for IDC and CD83-positive DC were rarely seen in large bile duct obstruction. This is the first report on the existence of activated CD83-positive DC in PBC. The significantly increased numbers of IDC and the highly restricted distributions of CD83-positive DC in PBC indicate that activated DC may play a role in the abnormal immune pathogenesis of PBC.

Increased nitric oxide (NO) production by antigen-presenting dendritic cells is responsible for low allogeneic mixed leucocyte reaction (MLR) in primary biliary cirrhosis (PBC)

The levels of blastogenesis in allogeneic MLR containing T cells from one normal volunteer and irradiated dendritic cells from 29 patients with PBC, 17 patients with chronic hepatitis type C (CH-C) and 22 allogeneic normal controls were compared to see if there is any role of antigen-presenting cells (APC) in the pathogenesis of PBC. The stimulatory capacity of dendritic cells from PBC was significantly lower compared with that of dendritic cells from CH-C (P < 0.05) and normal controls (P < 0.05), which could not be attributable either to the levels of expression of surface molecules, such as HLA-DR and CD86 on dendritic cells, or to the levels of cytokines, such as IL-10 and IL-12. Significantly higher levels of NO were seen in the allogeneic MLR supernatants containing dendritic cells from PBC compared with the supernatants from cultures containing dendritic cells from CH-C (P < 0.001) or normal controls (P < 0.001). Moreover, dendritic cells from PBC produced 10 times more NO compared with dendritic cells from CH-C and normal controls (21.9 +/- 2.8 microM versus 1.6 +/- 0.3 microM and 1.6 +/- 0.3 microM, respectively; P < 0.001). The addition of N(G)-monomethyl-L-arginine monoacetate (L-NMMA), a known inhibitor of NO in allogeneic MLR containing dendritic cells from PBC, resulted in a significant decrease of NO and increase of blastogenesis. The selective impairment of dendritic cell function, increased production of NO by dendritic cells and restoration of blastogenesis using NO inhibitor in PBC have suggested a role for NO and dysfunction of dendritic cells in the pathogenesis of PBC. This inspires optimism that modulating the function of dendritic cells and controlling NO production, an improved therapeutic approach, might be planned for PBC.

Idiopathic thrombocytopenic purpura in a liver transplant recipient with previous primary biliary cirrhosis

The loss of immunotolerance has been implicated in the pathogenesis of both primary biliary cirrhosis (PBC) and idiopathic, immune-mediated thrombocytopenic purpura (ITP). An association between these two autoimmune diseases has been well described. We describe a 41-year-old woman in whom ITP developed 457 days after liver transplantation for PBC while receiving immunosuppressive medications sufficient to maintain allograft function. Our case report, the first to describe post-transplant ITP in association with PBC, demonstrates the persistence of the underlying immune dysregulation of PBC after transplantation. The practice of decreasing the dosage of immunosuppressive medication to maintenance levels after transplantation may unmask the effects of this defect in immunotolerance.

Primary biliary cirrhosis in The Netherlands. An analysis of associated diseases, cardiovascular risk, and malignancies on the basis of mortality figures

BACKGROUND/METHODS

In 1979 death rate registration for primary biliary cirrhosis (PBC) became available in The Netherlands. In the 14-year period 1979-92, 417 persons died of and 179 with PBC. We investigated secondary causes of death using standardized mortality ratios (SMR) (1.0 as reference, P < 0.001 regarded as significant).

RESULTS

Median age was 70-74 (35 to > 85) years. Secondary causes of death originated from the circulatory, digestive, and respiratory tracts and malignancies. Younger persons (< 60 years), dying of PBC, more often died with "toxicity related to immunosuppression' than older persons (P < 0.01). Younger persons (< 60) dying with PBC, more often died of hepatocellular carcinoma (HCC) than older ones (P < 0.05). In patients with PBC the frequency of HCC (SMR, 25.5; P < 0.0001) and diseases of the musculoskeletal system/connective tissue (SMR, 5.1; P < 0.0001) was higher than in the general population. Malignancies in general (SMR, 0.7), pancreatic carcinoma (SMR, 2.5), breast cancer (SMR, 0.1) and diseases of the circulatory system (SMR, 0.8) differed but not significantly (P < 0.05 - < 0.01). No difference existed in the localization of malignancies in patients dying of as compared with those dying with PBC.

CONCLUSIONS

Deaths occurred predominantly in the older age classes, with an age-related difference in some associated disorders. Patients with PBC showed an increased risk of HCC and diseases of the musculoskeletal system. Similar studies from different countries are needed.

Defective proliferation and regulatory function of CD4+ T cells bearing Leu-8 homing receptor in primary biliary cirrhosis. Phorbol myristate acetate enhances T-cell function

The majority of circulating CD4+ T cells express the Leu-8 peripheral lymph node homing receptor, and these cells have previously been shown to have suppressor-inducer and suppressor function. In the present study, it was found that CD4+, Leu-8+ T cells from patients with primary biliary cirrhosis (PBC) have a significantly (P < 0.01) lower proliferative response when stimulated with phytohemagglutinin (PHA), concanavalin A (Con A), or pokeweed mitogen (PWM) compared to normal controls. The proliferative response of CD4+, Leu-8- T cells was similar in patients and controls. However, the proliferative responses of CD4+, Leu-8+ from patients with PBC was normal when cells were stimulated with PHA, Con A, anti-CD3 monoclonal antibody, or ionomycin in combination with phorbol myristate acetate (PMA). CD4+ T cells from patients with PBC mediated normal helper function for PWM-stimulated immunoglobulin synthesis at high T/B ratios and their regulatory function was similar to that of normal CD4+ T cells that had been irradiated to inactivate their suppressor activity. When CD4+ T cells from patients with PBC were precultured with the combination of Con A and PMA, they mediated potent inhibitory activity similar to that of normal CD4+ T cells. Thus, CD4+, Leu-8+ T cells from patients with PBC have a defect of proliferation and suppressor function that is reversed by coculture with PMA. This finding suggests that impairment of a PMA-inducible lymphocyte activation pathway contributes to abnormal lymphocyte function in PBC.

Is there recurrence of primary biliary cirrhosis after liver transplantation? A clinicopathologic study in long-term survivors

Liver transplantation has been accepted as a successful therapeutic tool for irreversible liver diseases such as primary biliary cirrhosis. However, removal of the diseased liver may not eliminate this autoimmune disease, and recurrence of primary biliary cirrhosis in the liver graft has been reported as early as within the first posttransplant year. We studied whether or not primary biliary cirrhosis recurs after liver transplantation in follow-up biopsies of 19 primary biliary cirrhosis patients. Biopsies of 14 non-primary biliary cirrhosis patients served as controls. The median follow-up period was 5 years (range 1-11 years). Both groups of patients were selected according to strict criteria which excluded pre- and posttransplant diseases which could mimic primary biliary cirrhosis. The follow-up biopsies were taken according to a protocol at yearly intervals. Established histologic criteria for primary biliary cirrhosis were assessed semi-quantitatively in 119 biopsies in a coded fashion. A longitudinal study was performed after decoding the biopsies, to document the course of morphological changes in time per patient. In addition to data on liver tests and immunosuppression, anti-mitochondrial antibodies including the primary biliary cirrhosis specific subtypes (anti-PDH-E2 and BCKD-E2) were determined in freeze-stored serum samples. The biopsies showed a striking concordance between the primary biliary cirrhosis and non-primary biliary cirrhosis groups and few overt histologic abnormalities. There was no significant difference in liver-test results and immunosuppression. Overall anti-mitochondrial antibodies remained present in decreased titers.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoreactivity to M2 proteins in antimitochondrial antibody-negative patients with primary biliary cirrhosis

Although antimitochondrial auto-antibodies are characteristically present in the serum of patients with primary biliary cirrhosis (PBC), there is a discrepancy between the positivity for antimitochondrial antibody (AMA) and that for anti-M2 auto-antibody. In an attempt to explain the discrepancy, this study investigates the relationship between the AMA titre, determined by indirect immunofluorescence, and immunoreactivity to four inner mitochondrial membrane proteins (M2 proteins) with molecular weights of 70, 50, 47, and 40 kDa in 129 patients with PBC. Antimitochondrial antibody positivity was identified in 114 (88%) of 129 patients with clinically and histologically confirmed PBC. There were no significant differences between the AMA-negative and AMA-positive groups in clinical characteristics or histologically determined disease stage. Immunoblot analysis showed that all patients had anti-M2 auto-antibodies to one or more of the four M2 proteins. Nine (60%) of the 15 AMA-negative patients had antibodies to only one M2 protein (either 70 or 47 kDa). In contrast, 34 (53%) of the 64 patients with high AMA titres (> or = 1:320) had antibodies to all four M2 proteins. There was a significant rank correlation between the AMA titre and the number of antibodies to M2 proteins (P < 0.01). These findings indicate that the AMA titre is not influenced by the immunogenicity of M2 proteins but by the number of M2 proteins that elicit an antibody response and that decreased immunoreactivity to M2 proteins may induce AMA negativity in PBC serum samples.

High serum levels of CD8 antigen in primary biliary cirrhosis: a possible cause of suppressor cell dysfunction?

Reduced suppressor cell number and function have been described in a number of autoimmune diseases and this may contribute to pathogenesis. Suppressor cell function depends upon the interaction of the CD8 antigen expressed on suppressor cells with other limbs of the immune system. Recently, soluble membrane antigens including CD8 have been identified in serum and it is possible that the loss of such antigens from viable cells could result in functional deficit. In order to examine whether the decreased suppressor cell function reported in autoimmune type of chronic liver disease is associated with soluble serum CD8 levels, sera from 23 patients with primary biliary cirrhosis (PBC), 12 with autoimmune chronic active hepatitis (AI-CAH) and 21 healthy controls were tested using a commercially available enzyme immunoassay. The proportion of cells expressing the CD8 antigen and the intensity of its display were also determined using an immunofluorescent technique and an ELISA, respectively, for 12 PBC and 10 healthy controls. The soluble serum CD8 levels were significantly higher in PBC (mean U/ml +/- s.d., 777 +/- 331), and AI-CAH (575 +/- 291) than controls (322 +/- 115) (P less than 0.001 and P = 0.004, respectively). While the intensity of CD8 antigen expression on suppressor/cytotoxic populations was not significantly different in PBC (347 +/- 125 per 10(4) cells) compared with controls (441 +/- 206), the mean proportion of CD8 positive cells was significantly less in PBC (14.1 +/- 6.8%) than controls (20 +/- 4.7%) (P less than 0.05). These data suggest that the apparent reduction in suppressor cell number found for patients with PBC and AI-CAH may be a consequence of the shedding or secretion of CD8 antigen from cell membrane of CD8 positive lymphocyte. It is also possible that the loss of this antigen is responsible for the reduced suppressor cell function seen in these conditions.