In vitro anti-mitochondrial antibody synthesis in patients with primary biliary cirrhosis

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.

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.

Effect of colchicine on lymphocyte and monocyte function and its relation to fibroblast proliferation in primary biliary cirrhosis

Lymphocyte and monocyte function was investigated in eight patients with primary biliary cirrhosis and in age-matched and sex-matched controls. In three of the eight cirrhotic patients, two were in the late stage of the disease (stage III) and concanavalin A-induced suppressor cell function was markedly decreased; it returned to normal levels after 1 mo of treatment consisting of 5 mg per week of orally administered colchicine. The relative percentage of T cell subsets (CD3, CD4 and CD8) and the mean percentage of the helper and the suppressor phenotype were similar in cirrhotic patients and in controls. Basal production of interleukin-1 activity by a monocyte-enriched fraction of peripheral blood mononuclear cells of cirrhotic patients was three-fold above control values: after stimulation with endotoxin, interleukin-1 values increased tenfold above basal levels in monocyte-enriched fraction of peripheral blood mononuclear cells of both normal and cirrhotic patients. Colchicine normalized the basal production of interleukin-1 and inhibited its stimulation by endotoxin by 50%. Culture supernatants of endotoxin-stimulated monocyte-enriched fraction of peripheral blood mononuclear cells increased the proliferation of cultured human skin fibroblasts by 50%. In contrast, supernatants from stimulated monocyte-enriched fraction of peripheral blood mononuclear cells obtained from colchicine-treated patients significantly inhibited fibroblast proliferation. These findings suggest that stimulated chronic inflammatory cells may play an important role in liver fibrosis. Some of the actions of colchicine could be related to its effects on lymphocyte and monocyte function.

Abnormalities of B cell activation and immunoregulation in patients with chronic inflammatory liver diseases

The immunoglobulin production capacities of peripheral blood lymphocytes obtained from patients with various chronic inflammatory liver diseases and from normal individuals were compared. Using a reverse hemolytic plaque assay, immunoglobulin-secreting cells (ISC) were counted immediately after isolation (immediate ISC) and again after 6-day, in vitro cultivation without stimulant (spontaneous ISC) or in the presence of pokeweed mitogen, PWM (PWM-induced ISC). An increased number of immediate ISC were observed in patients with chronic active hepatitis (CAH) of the autoimmune type (n = 7) or with CAH type B (n = 32), probably reflecting a defect of the in vivo suppressor cell system as previously demonstrated. In vitro preincubation of cells with 5 x 10(-8) M prednisolone reduced the increase in the number of immediate ISC in patients with CAH of the autoimmune type. On the other hand, lymphocytes obtained from patients with CAH-type NANB (n = 9) and with primary biliary cirrhosis (PBC) (n = 12) showed an impaired capacity to generate ISC upon stimulation with PWM. Spontaneous ISC from patients' lymphocytes were not significantly different from those of normal individuals. Using allogeneic co-cultures with lymphocytes from normal individuals and from patients with CAH NANB hepatitis or primary biliary cirrhosis, we observed no increase in suppressor cell activity. Therefore, the diminished responses to PWM are probably attributable to an alteration in the peripheral helper T-cell compartment.

Immunology of primary biliary cirrhosis

(1) The serological diagnosis of PBC is possible in almost 100% of cases when appropriate methods and specific antigen preparations are used such as the purified ATPase fraction by ELISA for the detection of anti-M2, sonicated mitochondria by immunodiffusion for the demonstration of precipitating antibodies against M-A or M-B, and cell cultures by immunofluorescence for the detection of antibodies against nuclear dots. (2) The establishment of AMA profiles obtained by ELISA and CFT seems to be a sensitive approach to a better definition of the natural course of PBC. A distinction between a rather benign and a more progressive course seems especially possible in the presence of the AMA profiles A and B (anti-M9 and/or anti-M2-positive only by ELISA) versus D (anti-M2-, anti-M4-, anti-M8-positive in the CFT). (3) The analysis of cellular immune reactions in vitro and in vivo suggests an activation of cytotoxic T cells as well as a defect in the function of T suppressor cells. (4) Although the aetiology of PBC is unknown, the detection of MHC Class II antigens on bile duct epithelial cells in liver biopsies of patients with PBC but not of normal individuals may imply that an infectious agent being exposed in association with these MHC structures may trigger the disease. The inability of the immune system in controlling this infectious process would then lead to an ongoing inflammatory reaction which is responsible for the continuous destruction of bile ducts within portal triads.