The role of the innate immune recognition system in the pathogenesis of primary biliary cirrhosis: a conceptual view.

The aetiology of primary biliary cirrhosis (PBC) remains unknown. Infectious and non-infectious noxious insults in combination with tissue-specific factors may precipitate PBC. Activation of innate immune response because of impending danger signals seems to be a key event in early PBC, as evidenced by granuloma formation, eosinophilic reaction and IgM elevation. Aberrant mitophagy in 'stressed' biliary epithelia cells may initiate the immune response against mitochondrial antigens. Antimitochondrial autoantibodies recognize evolutionarily conserved molecules. The question arises, whether they are pathogenic or rather an expression of beneficial autoimmunity. The generally stable course of PBC suggests that stimulatory and inhibitory autoimmune reactions govern the inflammatory biliary process. Tissue repair and defense are the heart of innate immunity. But continuous exposure of exogenous stimuli may precipitate functional antireceptor autoantibodies that are no more protective but rather harmful. Mitophagy, apoptosis and bile duct proliferation define the inflammatory response within bile ducts. Autoantigens may be clustered in different blebs on the surface of apoptotic cells targeting a variety of membrane and non-membrane-associated antigens. Thus, the autoantibody response in PBC may target, for instance, the pro- and anti-apoptotic proteins of the Bcl-2 family or receptors of the adrenergic or cholinergic system, hereby interfering with the programme of apoptosis and the proliferation of biliary epithelial cells. Consideration of there being functional autoantibodies into the pathogenesis of PBC may help to improve our understanding of the aetiopathogenesis of PBC.

Autoantibodies to muscarinic acetylcholine receptors found in patients with primary biliary cirrhosis.

BACKGROUND: Autoantibodies to the human muscarinic acetylcholine receptor of the M3 type (hmAchR M3) have been suggested to play an etiopathogenic role in Sjögren's syndrome. Primary biliary cirrhosis (PBC) often is associated with this syndrome. Therefore, we studied the co-presence of hmAchR M3 autoantibodies in patients with PBC. METHODS: Frequency of hmAchR M3 autoantibodies was assessed by Western blotting analysis as well as by an ELISA using a 25-mer peptide of the 2nd extracellular loop of hmAchR M3. Co-localization of hmAchR M3/PBC-specific autoantibodies was studied by confocal laser scanning microscopy. Finally, sera from patients with PBC as well as from healthy controls were tested. RESULTS: Western blotting analysis as well as results from ELISA testing revealed a significantly enhanced IgG reactivity in PBC patients in contrast to healthy controls. Co-localization of autoantibodies with the hmAchR M3 receptor-specific autoantibodies was observed in 10 out of 12 PBC-patients but none of the 5 healthy controls. Antibodies of the IgM type were not found to be affected. CONCLUSIONS: For the first time, our data demonstrate the presence of autoantibodies to the hmAchR M3 in PBC patients. These findings might contribute to the understanding of the pathogenesis of this disease. Further studies have to focus on the functionality of hmAchR M3 autoantibodies in PBC patients.

Distinct enzyme profiles in patients with cryptogenic cirrhosis reflect heterogeneous causes with different outcomes after liver transplantation (OLT): a long-term documentation before and after OLT.

BACKGROUND: Sound information is lacking about the clinical presentation of cryptogenic cirrhosis and its outcome after orthotopic liver transplantation (OLT). METHODS: Among 856 patients who have been transplanted at our center, 40 patients had no evidence of any known etiologies and were therefore defined as suffering from cryptogenic cirrhosis. Their median follow-up period before OLT was 78 months (range, 1-264), and after OLT 97 months (range, 1-132). Laboratory and histological data were evaluated according to features being compatible either with a toxic, hepatitic, or cholestatic condition. RESULTS: The clinical and histological findings differed specifically between these three groups. The toxic-like group (GGT 4-18 x upper limit of normal [ULN]) expressed significantly higher IgA levels, had histologically more often fatty liver changes, and risk factors for non-alcoholic steatohepatitis predominated (56% compared with 3% in the other groups, P=0.01). The hepatitic-like group (ALT 2-18 x ULN) showed histologically features of chronic hepatitis or hepatitic cirrhosis, and only among these patients a median International Autoimmune Hepatitis (IAH) score of 13 was found suggesting autoimmune hepatitis (AiH). In the cholestatic group (AP 2-8 x ULN) histology was compatible with a non-toxic inflammatory process but IAH score excluded AiH in all. After OLT, actuarial graft and patients survival was 90% at 5 years. Mild or moderate graft hepatitis occurred in 9 patients (23%) and was significantly associated with a pre-OLT IAH score >or= 10 (P =0.008). CONCLUSIONS: This study provides arguments that cryptogenic cirrhosis is a heterogeneous disease in which autoimmune mechanisms might be predominately involved and being responsible for recurrence of chronic liver disease observed in some instances after OLT.

Analysis of the effect of IL-12 therapy on immunoregulatory T-cell subsets in patients with chronic hepatitis C infection.

BACKGROUND/AIMS: Aim of this study was to investigate the influence of IL-12 therapy on the production of immunoregulatory type 1/type 2-cytokines by peripheral blood mononuclear cells from patients with chronic hepatitis C. METHODOLOGY: Peripheral blood mononuclear cells were isolated from 12 patients with chronic HCV infection before and after eight weeks of IL-12 application (0.03-0.5 micrograms/kg body weight). Peripheral blood mononuclear cells from 40 healthy blood donors served as a control group. The peripheral blood mononuclear cells were incubated for seven days with antigens stimulating specifically type 1 (tuberculin purified protein derivative) or type 2 T-cells (tetanus-toxoid). Furthermore, BCG (bacille Calmette-Guérin) was added to the cultures known to activate macrophages/antigen-presenting cells. Supernatants of peripheral blood mononuclear cells were analyzed for tuberculin purified protein derivative-induced production of the type 1 cytokine IFN-gamma, tetanus-toxoid-induced production of the type 2 cytokine IL-5 and the BCG-induced production of TNF-alpha by a double sandwich ELISA. RESULTS: IL-12 therapy hardly influenced the regulatory type 1/type 2 T-cell reactivity. In contrast, BCG induced secretion of TNF-alpha was significantly higher after eight weeks of IL-12 therapy (4348 +/- 3083 pg/mL) than before treatment (1559 +/- 988 pgmL, p < 0.01). Clinically, serum alanine transaminase levels significantly decreased during IL-12 treatment but HCV-RNA persisted in all patients. CONCLUSIONS: IL-12 therapy in patients with HCV does not alter the production of regulatory cytokines produced by type 1/type 2 TH cells. The significantly enhanced production of BCG-induced TNF-alpha may, however, indicate an activation of antigen presenting cells or natural killer cells.

Effects of a lectin- and a viscotoxin-rich mistletoe preparation on clinical and hematologic parameters: a placebo-controlled evaluation in healthy subjects.

BACKGROUND AND OBJECTIVES: Mistletoe preparations, which are widely used among patients with cancer in Germany, have immunomodulating properties in vitro and in vivo. The aim of this evaluation was to determine and compare the effects of a lectin-rich (Iscador Qu [IQ] special, Weleda Company, Schwäbisch, Gmünd, Germany.) and a lectin-poor but viscotoxin-rich (Iscador Pini [IP] Weleda Company) mistletoe preparation on clinical and hematologic parameters in healthy subjects. DESIGN: In a double-blinded study, 48 volunteers were randomized to one of three groups: 16 received IQ or IP in increasing doses or placebo twice per week subcutaneously for 12 weeks. The differential blood count and the acute phase markers haptoglobin and C-reactive protein were examined weekly and the symptoms were scored using standardized questionnaires. RESULTS: IQ resulted in significant eosinophilia (315 +/- 109) beginning at week 5 (until week 12) compared to IP (183 +/- 120) or placebo (200 +/- 179). Furthermore, the acute phase marker haptoglobin was significantly increased in the IQ group during week 4. Dose-dependent local reactions (LRs) at the injection site occurred in all subjects who received mistletoe preparations but were stronger in the IQ-treated subjects than in the IP-treated group. The LRs observed in the IQ-treated group were characterized by stronger itching and longer latency than LRs in the IP-treated group (p < 0.05). Severe side-effects did not occur in any of the probands. CONCLUSIONS: IQ but not IP can induce eosinophilia in healthy individuals, and this may be related to its content of mistletoe lectins. In contrast, exposure to the viscotoxin-enriched extract IP did not result in specific changes of hematologic parameters. Furthermore, intensity and time course of local reactions seemed to depend on the concentration of mistletoe lectins in those extracts.

Demonstration of PDC-E1 subunits as major antigens in the complement-fixing fraction M4 and re-evaluation of PDC-E1-specific antibodies in PBC patients.

BACKGROUND: Primary biliary cirrhosis (PBC) is characterized by the presence of antimitochondrial antibodies (AMA). Autoantibodies specific for the mitochondrial M4 antigen can be detected by a complement fixation test (CFT) but not by immunoblotting. The aim of this study was to elucidate the identity of the M4 antigen. PATIENTS AND METHODS: M4 proteins were purified by affinity chromatography using IgG fractions of PBC marker sera being CFT positive (n=5) or negative (n=5) and identified by Western blotting, silver staining and sequence analysis. Further, a cohort of 57 PBC patients was tested for the reactivity to M4 and pyruvate dehydrogenase complex (PDC). RESULTS: Two AMA patterns of the marker sera were visualized: CFT-positive sera were defined as PDC-E2(+)/E1(+) and the CFT-negative sera as PDC-E2(+)/E1(-). The major proteins in the M4 fraction could be related to the PDC-E1 subunits. A clear-cut association between anti-M4 reactivity in the CFT and the reactivity to both PDC subunits could also be documented in the cohort of 57 PBC patients showing anti-PDC-E1alpha and E1beta antibodies at a frequency of 74% and 67%. CONCLUSIONS: CFT reactivity against M4 antigens could be preferentially identified as a reaction against PDC-E1. As PDC-E1 subunits as compared with PDC-E2 lack lipoyl-binding sites, they probably have to be considered as an independent and important target.