Implications of altered maternal cytokine concentrations on infant outcomes in children with prenatal alcohol exposure

Excessive alcohol consumption has been shown to increase serum plasma levels of numerous immune cytokines. Maternal immune activation and elevated cytokines have been implicated in certain neurological disorders (e.g., autism and schizophrenia) in the offspring. We investigated the hypothesis that elevated cytokines during pregnancy are a risk factor in women who gave birth to a child with Fetal Alcohol Spectrum Disorder (FASD) or a child with neurobehavioral impairment, regardless of prenatal alcohol exposure. Moderate to heavy alcohol-exposed (AE) (N = 149) and low or no alcohol-exposed (LNA) (N = 92) women were recruited into the study during mid pregnancy (mean of 19.8 ± 5.8 weeks' gestation) in two regions of Ukraine: Khmelnytsky and Rivne. Maternal blood samples were obtained at enrollment into the study at early to mid-pregnancy and during a third-trimester follow-up visit and analyzed for plasma cytokines. Children were examined at 6 and/or 12 months of age and were classified as having FASD if their mothers reported alcohol use and if they had at least one standardized score (Bayley Scales of Infant Development II Mental Development Index [MDI], or Psychomotor Development Index [PDI]) below 85 with the presence or absence of physical features of FASD. In multivariate analyses of maternal cytokine levels in relation to infant MDI and PDI scores in the entire sample, increases in the ratio of TNF-α/IL-10 and IL-6/IL-10 were negatively associated with PDI scores at 6 months (p = 0.020 and p = 0.036, respectively) and 12 months (p = 0.043 and p = 0.029, respectively), and with MDI scores at 12 months (p = 0.013 and p = 0.050, respectively). A reduction in the odds ratio of having an FASD child was observed with increasing levels of IL-1β, IL-2, IL-4, IL-6, and IL-10 in early to mid-pregnancy and IL-1β and IL-10 during late pregnancy. However, women that failed to increase IL-10 levels in the third trimester in order to maintain the balance of pro- and anti-inflammatory cytokines had an elevated risk of having an FASD child, specifically a significant increase in the odds ratio of FASD with every one-unit log increase in late pregnancy TNF-α/IL-10 levels (aOR: 1.654, CI: 1.096-2.495, p = 0.017). These data support the concept that disruptions in the balance between pro- and anti-inflammatory cytokines may contribute to neurobehavioral impairment and alter the risk of FASD.

Anti-brain antibodies are associated with more severe cognitive and behavioral profiles in Italian children with Autism Spectrum Disorder

Circulating 45 and 62kDa antibodies targeting the cerebellum were previously associated with Autism Spectrum Disorder (ASD), lower adaptive/cognitive function and aberrant behaviors. Moreover, 37, 39 and 73kDa maternal antibodies (mAb) targeting the fetal brain were previously correlated with broad autism spectrum, irritability, abnormal brain enlargement and impaired expressive language. The present study aims towards clinically characterizing individuals with brain-targeted IgG and/or exposed to maternal antibrain antibodies in a large sample of Italian autistic children (N=355), their unaffected siblings (N=142) and mothers (N=333). The presence of patient- and mother-produced anti-brain antibodies does not confer increased risk of autism within the same sibship. However, the 45 and 62kDa antibodies are correlated with autism severity: the 45kDa Ab is associated with cognitive impairment and lower scores at the Vineland Adaptive Behavior Scales, the 62kDa Ab with motor stereotypies, while both correlate with larger head circumference (all P<0.05). On the other hand, maternal 37, 39 and 73kDa antibrain antibodies, either alone or in combination, are correlated with impaired verbal and non-verbal language development, neurodevelopmental delay and sleep/wake cycle disturbances in their autistic children (P<0.05). Presence of the 62kDa autoAb in the child is significantly associated with presence of the 39 and/or 73kDa antibodies in his/her mother. Our results confirm and extend previous observations in an ethnically distinct sample, providing further evidence of a pathomorphic role for anti-brain antibodies in autism while demonstrating their familial clustering.

Maternal antibodies from mothers of children with autism alter brain growth and social behavior development in the rhesus monkey

Antibodies directed against fetal brain proteins of 37 and 73 kDa molecular weight are found in approximately 12% of mothers who have children with autism spectrum disorder (ASD), but not in mothers of typically developing children. This finding has raised the possibility that these immunoglobulin G (IgG) class antibodies cross the placenta during pregnancy and impact brain development, leading to one form of ASD. We evaluated the pathogenic potential of these antibodies by using a nonhuman primate model. IgG was isolated from mothers of children with ASD (IgG-ASD) and of typically developing children (IgG-CON). The purified IgG was administered to two groups of female rhesus monkeys (IgG-ASD; n=8 and IgG-CON; n=8) during the first and second trimesters of pregnancy. Another control group of pregnant monkeys (n=8) was untreated. Brain and behavioral development of the offspring were assessed for 2 years. Behavioral differences were first detected when the macaque mothers responded to their IgG-ASD offspring with heightened protectiveness during early development. As they matured, IgG-ASD offspring consistently deviated from species-typical social norms by more frequently approaching familiar peers. The increased approach was not reciprocated and did not lead to sustained social interactions. Even more striking, IgG-ASD offspring displayed inappropriate approach behavior to unfamiliar peers, clearly deviating from normal macaque social behavior. Longitudinal magnetic resonance imaging analyses revealed that male IgG-ASD offspring had enlarged brain volume compared with controls. White matter volume increases appeared to be driving the brain differences in the IgG-ASD offspring and these differences were most pronounced in the frontal lobes.

Association of a MET genetic variant with autism-associated maternal autoantibodies to fetal brain proteins and cytokine expression

The contribution of peripheral immunity to autism spectrum disorders (ASDs) risk is debated and poorly understood. Some mothers of children with ASD have autoantibodies that react to fetal brain proteins, raising the possibility that a subset of ASD cases may be associated with a maternal antibody response during gestation. The mechanism by which the maternal immune system breaks tolerance has not been addressed. We hypothesized that the mechanism may involve decreased expression of the MET receptor tyrosine kinase, an ASD risk gene that also serves as a key negative regulator of immune responsiveness. In a sample of 365 mothers, including 202 mothers of children with ASD, the functional MET promoter variant rs1858830 C allele was strongly associated with the presence of an ASD-specific 37+73-kDa band pattern of maternal autoantibodies to fetal brain proteins (P=0.003). To determine the mechanism of this genetic association, we measured MET protein and cytokine production in freshly prepared peripheral blood mononuclear cells from 76 mothers of ASD and typically developing children. The MET rs1858830 C allele was significantly associated with MET protein expression (P=0.025). Moreover, decreased expression of the regulatory cytokine IL-10 was associated with both the MET gene C allele (P=0.001) and reduced MET protein levels (P=0.002). These results indicate genetic distinction among mothers who produce ASD-associated antibodies to fetal brain proteins, and suggest a potential mechanism for how a genetically determined decrease in MET protein production may lead to a reduction in immune regulation.

Fatty acid compositions of red blood cell phospholipids in children with autism

We compared the compositions of fatty acids including n-3, n-6 polyunsaturated fatty acids, trans- and cis-monounsaturated fatty acids, and saturated fatty acids in the red blood cell membranes of 40 children with autism (20 with early onset autism and 20 with developmental regression) and age-matched, 20 typically developing controls and 20 subjects with non-autistic developmental disabilities. The main findings include increased levels of eicosenoic acid (20:1n9) and erucic acid (22:1n9) in autistic subjects with developmental regression when compared with typically developing controls. In addition, an increase in 20:2n6 and a decrease in 16:1n7t were observed in children with clinical regression compared to those with early onset autism. Our results do not provide strong evidence for the hypothesis that abnormal fatty acid metabolism plays a role in the pathogenesis of autism spectrum disorder, although they suggest some metabolic or dietary abnormalities in the regressive form of autism.

Effects of a Spirulina-based dietary supplement on cytokine production from allergic rhinitis patients

Spirulina represents a blue-green alga that is widely produced and commercialized as a dietary supplement for modulating immune functions, as well as ameliorating a variety of diseases. We have previously shown that the in vitro culture of Spirulina with human peripheral blood mononuclear cells (PBMCs) modulated the production of cytokines. In the present study, we evaluated the impact of a Spirulina-based dietary supplement (Earthrise Nutritionals, Inc., Irvine, CA) on patients with allergic rhinitis by assessing the production of cytokines [interleukin (IL)-4, interferon (IFN)-gamma, and IL-2] critical in regulating immunoglobulin E-mediated allergy. In a randomized double-blinded crossover study versus placebo, allergic individuals were fed daily with either placebo or Spirulina, at 1,000 mg or 2,000 mg, for 12 weeks. PBMCs isolated before and after the Spirulina feeding were stimulated with phytohemagglutinin (PHA) prior to determining the levels of cytokine from cell culture supernatants. Although Spirulina seemed to be ineffective at modulating the secretion of Th1 cytokines (IFN-gamma and IL-2), we discovered that Spirulina, administered at 2,000 mg/day, significantly reduced IL-4 levels by 32% from PHA-stimulated cells. These results indicate that Spirulina can modulate the Th profile in patients with allergic rhinitis by suppressing the differentiation of Th2 cells mediated, in part, by inhibiting the production of IL-4. To our knowledge, this is the first human feeding study that demonstrates the protective effects of Spirulina towards allergic rhinitis.

Effect of cocoa flavanols and their related oligomers on the secretion of interleukin-5 in peripheral blood mononuclear cells

We previously showed that flavanols and their related oligomers (FLO) isolated from cocoa can have immunomodulatory effects on production of the cytokines interleukin-1beta (IL-1beta), IL-2, and IL-4. In the present study, we examined whether selected FLO fractions isolated from cocoa (monomer through decamer) modulate IL-5 protein secretion from resting and phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC). Although FLO fractions were unstimulatory for IL-5 secretion in resting cells, PHA-induced IL-5 release from PBMC was markedly affected by certain FLO fractions. The monomeric and small oligomeric (dimer and trimer) fractions enhanced PHA stimulation by 50%, 54%, and 43%, respectively. In contrast, the larger oligomeric fractions (hexamer through decamer) inhibited IL-5 release in the range of 18% to 39%; the tetramer and pentamer showed intermediate effects. The increment in IL-5 suggests that FLO may preferentially stimulate immunoglobulin A. We suggest that in the oral cavity this could result in reduction in the risk for dental caries and periodontal disease. This work offers additional data for consideration of the health benefits of dietary FLO from a variety of foods, including those benefits associated specifically with consumption of some cocoas and chocolates.

Immunoreactivity of organic mimeotopes of the E2 component of pyruvate dehydrogenase: connecting xenobiotics with primary biliary cirrhosis

In primary biliary cirrhosis (PBC), the major autoepitope recognized by both T and B cells is the inner lipoyl domain of the E2 component of pyruvate dehydrogenase. To address the hypothesis that PBC is induced by xenobiotic exposure, we took advantage of ab initio quantum chemistry and synthesized the inner lipoyl domain of E2 component of pyruvate dehydrogenase, replacing the lipoic acid moiety with synthetic structures designed to mimic a xenobiotically modified lipoyl hapten, and we quantitated the reactivity of these structures with sera from PBC patients. Interestingly, antimitochondrial Abs from all seropositive patients with PBC, but no controls, reacted against 3 of the 18 organic modified autoepitopes significantly better than to the native domain. By structural analysis, the features that correlated with autoantibody binding included synthetic domain peptides with a halide or methyl halide in the meta or para position containing no strong hydrogen bond accepting groups on the phenyl ring of the lysine substituents, and synthetic domain peptides with a relatively low rotation barrier about the linkage bond. Many chemicals including pharmaceuticals and household detergents have the potential to form such halogenated derivatives as metabolites. These data reflect the first time that an organic compound has been shown to serve as a mimeotope for an autoantigen and further provide evidence for a potential mechanism by which environmental organic compounds may cause PBC.

Heterogeneous response of antimitochondrial autoantibodies and bile duct apical staining monoclonal antibodies to pyruvate dehydrogenase complex E2: the molecule versus the mimic

The 2-oxo-acid dehydrogenase complexes and, in particular, the E2 component of the pyruvate dehydrogenase complex (PDC) are the target of antimitochondrial antibodies (AMA). More than 95% of primary biliary cirrhosis (PBC) patients have detectable levels of autoantibodies to PDC-E2 and in general these react with a region of the molecule that contains the prosthetic group lipoic acid (LA). LA is vital to the function of the enzyme, although there is conflicting evidence as to whether its presence is required for PDC-E2 recognition by AMA. Some, but not all, monoclonal antibodies (mAbs) to PDC-E2 produce an intense staining pattern at the apical surface of bile duct epithelial cells (BEC) in patients with PBC, and it has been argued that the molecule at the apical surface of PBC bile duct cells is a modified form of PDC-E2 or a cross-reactive molecule, acting as a molecular mimic. Herein, we characterize the epitopes recognized by 4 anti-PDC-E2 mAbs that give apical staining patterns (3 mouse and 1 human). In particular, by using a combination of recombinant antigens, competitive inhibition assays, and a unique peptide-on-bead assay, we determined that these apically staining mAbs recognize 3 or 4 distinct epitopes on PDC-E2. More importantly, this suggests that a portion spanning the entire inner lipoyl domain of PDC-E2 can be found at the BEC apical surface. In addition, competition assays with patient sera and a PDC-E2-specific mAb showed significant epitope overlap with only 1 of the 3 mouse mAbs and showed a differential response to the peptide bound to beads. These findings further highlight the heterogeneous response of patient autoantibodies to the inner lipoyl domain of PDC-E2.

The effect of cocoa procyanidins on the transcription and secretion of interleukin 1 beta in peripheral blood mononuclear cells

Recent data has demonstrated that cacao liquor polyphenols (procyanidins) have antioxidant activity, inhibit mRNA expression of interleukin-2 and are potent inhibitors of acute inflammation. Given the widespread ingestion of cocoa in many cultures, we investigated whether cocoa, in its isolated procyanidin fractions (monomer through decamer), would modulate synthesis of the pro-inflammatory cytokine, interleukin-1 beta. Both resting and phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) were investigated at the levels of transcription and protein secretion. Individual cocoa fractions were shown to augment constitutive IL-1 beta gene expression, although values varied between subjects. Interestingly, the smaller fractions of cocoa (monomer-tetramer) consistently reduced IL-1 beta expression of PHA-stimulated cells by 1-15%, while the larger oligomers (pentamer-decamer) increased expression by 4-52%. These data, observed at the transcription level, were reflected in protein levels in PHA-induced PBMC. The presence or absence of PHA did not alter the effects of the cocoa procyanidins with the exception of the pentamer. This study offers additional data for the consideration of the health-benefits of dietary polyphenols from a wide variety of foods, including those benefits associated specifically with cocoa and chocolate consumption.

The immunopathogenesis of primary biliary cirrhosis

There have been several recent advances in our understanding of primary biliary cirrhosis. Foremost amongst these has been the cloning and identification of the mitochondrial autoantigens as members of the 2-oxo-dehydrogenase complex. These include the E2 components of PBC, BCKD and OGDC. The immunodominant autoepitopes of the autoantigens have been mapped and, in all cases, correspond to the inner lipoyl domain. Limited progress has also been made on T cells, particularly the CD4 response. However, the fundamental mechanisms and the role, if any, of CD8 cells are unknown. Finally, at least 2 groups have identified a molecule that cross-reacts with PDC-E2, i.e., a mimic, on the luminal surface of biliary epithelium in PBC but not controls. The identification of this molecule will be critical in further understanding the immune response of this disease.

Evidence for the role of environmental agents in the initiation or progression of autoimmune conditions

The concordance of autoimmune disease among identical twins is virtually always less than 50% and often in the 25-40% range. This observation, as well as epidemic clustering of some autoimmune diseases following xenobiotic exposure, reinforces the thesis that autoimmune disease is secondary to both genetic and environmental factors. Because nonliving agents do not have genomes, disease characteristics involving nonliving xenobiotics are primarily secondary to host phenotype and function. In addition, because of individual genetic susceptibilities based not only on major histocompatibility complex differences but also on differences in toxin metabolism, lifestyles, and exposure rates, individuals will react differently to the same chemicals. With these comments in mind it is important to note that there have been associations of a number of xenobiotics with human autoimmune disease, including mercury, iodine, vinyl chloride, canavanine, organic solvents, silica, l-tryptophan, particulates, ultraviolet radiation, and ozone. In addition, there is discussion in the literature that raises the possibility that xenobiotics may also exacerbate an existing autoimmune disease. In this article we discuss these issues and, in particular, the evidence for the role of environmental agents in the initiation or progression of autoimmune conditions. With the worldwide deterioration of the environment, this is a particularly important subject for human health.

Is there a serological difference between men and women with primary biliary cirrhosis?

OBJECTIVE

Primary biliary cirrhosis (PBC) is an autoimmune disease affecting small intrahepatic bile ducts of the liver, causing destruction of the epithelium that results in eventual fibrosis and scarring. We still lack a complete epidemiological description of this disease, although interesting geographic differences in prevalence have been described. One consistent feature has been the relative scarcity of men with PBC. In fact, published ratios of women to men range from 3:1 to as high as 22:1. Thus far, the only clinical difference reported between men and women with PBC is a putative higher risk of hepatocarcinoma in men. Previous serological studies have shown that about 95% of all patients possess antimitochondrial antibodies to members of the highly conserved 2-oxo-acid dehydrogenase family of proteins, namely pyruvate dehydrogenase complex E2 (PDC-E2), branched-chain 2-oxo-acid dehydrogenase complex E2 (BCOADC-E2), and 2-oxo glutarate dehydrogenase complex E2 (OGDC-E2). However, there has been no information as to whether there is a difference in serological response between men and women. Using the serological hallmark of antimitochondrial antibodies (AMAs) and taking advantage of the availability of recombinant mitochondrial autoantigens, investigations were performed to determine if there were any serological differences between men and women with PBC.

METHODS

Sera were collected from 88 patients with PBC, of whom 46 were men and 42 were women. Using a combination of immunoblotting and enzyme-linked immunoabsorbent assay (ELISA) against beef heart mitochondria (BHM), recombinant PDC-E2, BCOADC-E2, and OGDC-E2, we determined the relative autoantibody reactivities of our study population.

RESULTS

Both men and women with PBC produced high titer antimitochondrial antibodies. The frequency of reactivity was similar in both groups and included, in descending order, PDC-E2, E3BP (Protein X), BCOADC-E2, and finally OGDC-E2. More importantly, antigenic specificity was nearly identical regardless of gender.

CONCLUSIONS

AMAs are the serological hallmark of PBC in both men and women, and there is no significant difference in reactivity between the two groups of patients.

The influence of chronic yogurt consumption on immunity

There has been increased interest in the study of nutrition and immunity. This is especially true with respect to the hypothesis that consumption of specific foods may reduce an individual's susceptibility to the establishment and/or progression of immunologic disease. Although an increased intake of a specific food may improve health status in select cases, chronic consumption of large amounts of one specific food may in fact be detrimental. The studies described here examined the long-term effect of yogurt consumption on two different age populations, young adults (20-40 y) and senior adults (55-70 y). There were three study groups per age group, live-culture yogurt, pasteurized yogurt and control (no yogurt), given 200 g/d of yogurt for 1 y. The subjects completed a questionnaire detailing health parameters on a weekly basis and a 4-d food record was taken monthly. Blood was taken every 3 mo and complete blood chemistry, blood count, total and specific immunoglobulin (Ig)E, and interferon-gamma (IFN-gamma) production measured. Yogurt consumption, especially for the live-culture groups, was associated with a decrease in allergic symptoms in both age groups. Seniors in the control group experienced an increase in both total and LDL cholesterol, whereas those in the yogurt groups remained stable during the course of the study. There was little effect on IFN-gamma and IgE production, although seniors in the yogurt group had lower levels of total IgE throughout the year.

Autoepitope mapping and reactivity of autoantibodies to the dihydrolipoamide dehydrogenase-binding protein (E3BP) and the glycine cleavage proteins in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by the presence of antimitochondrial antibodies (AMA) directed primarily against the E2 subunits of the pyruvate dehydrogenase complex, the branched chain 2-oxo-acid dehydrogenase complex, the 2-oxoglutarate dehydrogenase complex, as well as the dihydrolipoamide dehydrogenase-binding protein (E3BP) of pyruvate dehydrogenase complex. The autoantibody response to each E2 subunit is directed to the lipoic acid binding domain. However, hitherto, the epitope recognized by autoantibodies to E3BP has not been mapped. In this study, we have taken advantage of the recently available full-length human E3BP complementary DNA (cDNA) to map this epitope. In addition, another lipoic binding protein, the H-protein of the glycine cleavage complex, was also studied as a potential autoantigen recognized by AMA. Firstly, the sequence corresponding to the lipoic domain of E3BP (E3BP-LD) was amplified by polymerase chain reaction and recombinant protein and then purified. Immunoreactivity of 45 PBC sera (and 52 control sera) against the purified recombinant E3BP-LD was analyzed by enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Secondly, reactivity of PBC sera was similarly analyzed by immunoblotting against H-protein. It is interesting that preabsorption of patient sera with the lipoic acid binding domain of E3BP completely removed all reactivity with the entire protein by immunoblotting analysis, suggesting that autoantibodies to E3BP are directed solely to its lipoic acid binding domain. Fifty-three percent of PBC sera reacted with E3BP-LD, with the majority of the response being of the immunoglobulin G (IgG) isotype (95%). Surprisingly, there was little IgM response to the E3BP-LD suggesting that the immune response was secondary because of determinant spreading. In contrast, H-protein does not appear to possess (or expose) autoepitopes recognized by PBC sera. This observation is consistent with structural data on this moiety.

Generation of monoclonal antibodies to murine bile duct epithelial cells: identification of annexin V as a new marker of small intrahepatic bile ducts

Biliary epithelial cells (BECs) are distributed along the length of both the extrahepatic and intrahepatic biliary tree, but have distinctly different phenotypes and functions according to their anatomical location. It has been reasoned that the distinct appearance of pathogenic lesions in different biliary diseases may be associated with the expression of distinct proteins. These data prompted us to immunize rats with cultured murine BECs with the objective of determining if there are unique antigens on BECs. Of the 45 monoclonal antibodies (mAbs) produced, 12 mAbs (MBEC 1-12) were selected for detailed study based on their classification into three major groups. These groups included four antibodies (MBEC 1-4) that reacted in a staining pattern typical of mucin. A second group of mAbs, MBECs 5 to 8, reacted strongly along the biliary tract and by immunoblot analysis, reacted with several bands ranging from 44 kd to 64 kd. These antibodies were considered as markers of pan BECs and their staining pattern proved similar to that of a control polyclonal pan-cytokeratin. The final group of mAbs, MBECs 9 to 12, recognized a 36-kd antigen using lysates of murine BECs. These antibodies also predominantly stained small peripheral bile ducts. The reactive antigen was purified by immunoprecipitation and microsequenced; the peptides sequenced showed 100% homology with murine annexin V. The identification of annexin V with predominantly intrahepatic bile ducts, is of significant interest because of the multiple roles of annexin V, including that of membrane cytoskeletal interactions during transport and apoptosis.

Autoantibodies in human chronic graft-versus-host disease after hematopoietic cell transplantation

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 antimitochondrial 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.

Identification and precursor frequency analysis of a common T cell epitope motif in mitochondrial autoantigens in primary biliary cirrhosis

The immunodominant antimitochondrial antibody response in patients with primary biliary cirrhosis (PBC) is directed against the E2 component of the pyruvate dehydrogenase complex (PDC-E2). Based on our earlier observations regarding peripheral blood mononuclear cell (PBMC) T cell epitopes, we reasoned that a comparative analysis of the precursor frequencies of PDC-E2 163-176-specific T cells isolated from PBMC, regional hepatic lymph nodes, and from the liver of PBC patients would provide insight regarding the role of T cells in PBC. Results showed a disease-specific 100-150-fold increase in the precursor frequency of PDC-E2 163-176-specific T cells in the hilar lymph nodes and liver when compared with PBMC from PBC patients. Interestingly, autoreactive T cells and autoantibodies from PBC patients both recognize the same dominant epitope. In addition, we demonstrated cross-reactivity of PDC-E2 peptide 163-176-specific T cell clones with PDC-E2 peptide 36-49 and OGDC-E2 peptide 100-113 thereby identifying a common T cell epitope "motif" ExETDK. The peptide 163-176-specific T cell clones also reacted with purified native PDC-E2, suggesting that this epitope is not a cryptic determinant. These data provide evidence for a major role for PDC-E2 peptide 163-176 and/or peptides bearing a similar motif in the pathogenesis of PBC.

Monoclonal antibodies to mitochondrial E2 components define autoepitopes in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by the presence of antimitochondrial Abs (AMA). The autoantigens recognized by AMA are the E2 components of the pyruvate dehydrogenase complex (PDC-E2), the branched chain 2-oxoacid dehydrogenase complex E (BCOADC-E2), and the 2-oxoglutarate dehydrogenase complex E (OGDC-E2). Previous studies using murine monoclonal and human combinatorial Abs to PDC-E2 have demonstrated an intense linear staining pattern in the apical region of biliary epithelial cells (BEC) in PBC but not control liver. We therefore examined whether mAbs to the other mitochondrial autoantigens BCOADC-E2 and OGDC-E2 demonstrated disease-specific patterns of reactivity. Using an expressed recombinant "trihybrid" protein containing the lipoyl domains of PDC-E2, OGDC-E2, and BCOADC-E2, we immunized BALB/c mice to produce 35 mAbs specific for one or more of the above mitochondrial autoantigens. Seven of these mAbs uniquely stained the apical region of BEC in PBC. Of these seven, one was reactive to PDC-E2, two recognized BCOADC-E2, three were reactive to OGDC-E2, and one recognized all three Ags. Our current data demonstrate that, similar to our previous studies regarding PDC-E2, mAbs to BCOADC-E2 and OGDC-E2, or a molecule that cross-reacts with the inner lipoyl domain of all three enzymes, also show a uniquely intense staining pattern in the apical region of BEC in patients with PBC when compared with diseased controls. The abundance of such disease-specific determinants in the target cells of PBC raises interesting possibilities regarding the role of these autoantigens in the pathogenesis of this disease.

Induction and persistence of immune-mediated cholangiohepatitis in neonatally thymectomized mice

The availability of recombinant autoantigens allows the experimental study of the relationships between primary biliary cirrhosis (PBC) and mitochondrial antigens. We took advantage of these recombinant autoantigens and attempted to induce autoimmune cholangitis by immunizing neonatally thymectomized (NTx) lipopolysaccharide (LPS)-treated A/J mice, known to be prone to organ-specific autoimmune diseases. We employed a recombinant protein containing a dual-headed molecule that coexpresses the immunodominant epitope of the E2 subunits of the pyruvate dehydrogenase complex and the branched-chain keto-acid dehydrogenase complex. We report herein that an immune-mediated cholangiohepatitis was induced by such immunization and the concurrent injection of LPS into NTx mice. The incidence of cholangitis was 79% in the NTx, immunized, LPS group compared to 14% in the NTx, nonimmunized, LPS group. The histopathology ranged from mild to severe and included bile duct damage, focal hepatic necrosis, and endotheliitis, but no granulomas. Moreover, almost all such lesions persisted for 12 weeks after the discontinuation of immunization and LPS injections in the NTx mice. Interestingly, we were successful (89%) in transferring the cholangiohepatitis by injection of liver infiltrating mononuclear cells from the NTx, immunized, LPS mice into congenic nonimmunized NTx mice; such lesions could not be transferred with spleen cells. Although the pathology is not typical of PBC, this model offers a unique venue for the study of immune-mediated hepatobiliary injury.

Penetration and co-localization in MDCK cell mitochondria of IgA derived from patients with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic autoimmune liver disease of unknown etiology characterized by high-titer anti-mitochondrial antibodies. The major autoantigen has been identified as the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2). The fact that PDC-E2 is present in all nucleated cells, but autoimmune damage is confined to biliary epithelial cells, prompted us to investigate the possibility that mucosally-derived IgA may be pathogenic for biliary epithelial cells. Serum IgA was purified from six patients with PBC and its localization and ability to penetrate cells was studied using Madine-Darby canine kidney (MDCK) cells transfected with the human IgA receptor (MDCK-pIgR). The potential of IgA to be transported through the cells was studied by a combination of immunohistochemistry and dual color fluorescent microscopy. Interestingly, IgA from all PBC patients co-localized with PDC-E2 (the major autoantigen of PBC) inside the cells; this was demonstrated by dual staining with anti-human IgA and a mouse monoclonal antibody directed to PDC-E2. In contrast, no co-localization was observed for IgA controls. Furthermore, dual staining of liver sections from PBC patients demonstrated co-localization of IgA and PDC-E2, both cytoplasmically and at the apical surface. We postulate that there may be a direct effect of these autoantibodies on the mitochondrial function of biliary epithelial cells.

Detection of retroviral antibodies in primary biliary cirrhosis and other idiopathic biliary disorders

BACKGROUND

Retroviruses have been implicated in the aetiology of various autoimmune diseases. We used immunoblots as a surrogate test to find out whether retroviruses play a part in the development of primary biliary cirrhosis.

METHODS

We did western blot tests for HIV-1 and the human intracisternal A-type particle (HIAP), on serum samples from 77 patients with primary biliary cirrhosis, 126 patients with chronic liver disease, 48 patients with systemic lupus erythematosus, and 25 healthy volunteers.

FINDINGS

HIV-1 p24 gag seroreactivity was found in 27 (35%) of 77 patients with primary biliary cirrhosis, 14 (29%) of 48 patients with systemic lupus erythematosus, 14 (50%) of 28 patients with chronic viral hepatitis, and nine (39%) of 23 patients with either primary sclerosing cholangitis or biliary atresia, compared with only one (4%) of 24 patients with alcohol-related liver disease or alpha1-antitrypsin-deficiency liver disease, and only one (4%) of 25 healthy volunteers (p=0.003). Western blot reactivity to more than two HIAP proteins was found in 37 (51%) of patients with primary biliary cirrhosis, in 28 (58%) of patients with systemic lupus erythematosus, in 15 (20%) of patients with chronic viral hepatitis, and in four (17%) of those with other biliary diseases. None of the 23 patients with either alcohol-related liver disease or alpha1-antitrypsin deficiency, and only one of the healthy controls showed the same reactivity to HIAP proteins (p<0.0001). Our results showed a strong association between HIAP seroreactivity and the detection of autoantibodies to double-stranded DNA. HIAP seroreactivity was also strongly associated with the detection of mitochondrial, nuclear, and extractable nuclear antigens.

INTERPRETATION

The HIV-1 and HIAP antibody reactivity found in patients with primary biliary cirrhosis and other biliary disorders may be attributable either to an autoimmune response to antigenically related cellular proteins or to an immune response to uncharacterised viral proteins that share antigenic determinants with these retroviruses.

Characterization of antimitochondrial antibodies in health adults

The detection of antimitochondrial antibodies (AMAs) is an important criterion for the diagnosis of primary biliary cirrhosis (PBC). During the last decade, the mitochondrial autoantigens have been cloned, sequenced, and identified as members of the 2-oxo-acid dehydrogenase pathway, including the E2 subunits of pyruvate dehydrogenase (PDC-E2), branched-chain 2-oxo-acid dehydrogenase (BCOADC-E2), and 2-oxo-glutarate dehydrogenase (OGDC-E2). We have developed a rapid and sensitive diagnostic test for use in PBC based on a triple hybrid recombinant molecule (r-MIT3) that contains the autoepitopes of PDC-E2, BCOADC-E2, and OGDC-E2. To help understand the frequency and antigen specificity of AMAs in an asymptomatic population and to identify patients with early disease, we investigated the prevalence of AMA, by enzyme-linked immunosorbent assay (ELISA), in a cohort of 1,530 people from northern Italy. Positive sera were further analyzed for immunoglobulin (Ig) isotypes, subclasses, and epitopes of AMA by a combination of ELISA and immunoblotting. In this cohort of 1,530 people, 9 (0.5%) reacted to r-MIT3 by ELISA. Of the 9 reactive sera, 2 recognized PDC-E2, 2 of 9 recognized BCOADC-E2, 1 of 9 recognized OGDC-E2, 2 of 9 recognized both PDC-E2 and BCOADC-E2, and 1 of 9 recognized PDC-E2 and OGDC-E2. AMA reactivity was primarily IgM and IgA. Epitope mapping revealed an AMA pattern of reactivity to PDC-E2 that differed from that found in patients with histologically proven PBC in most of the sera. However, 1 sera of a 72-year-old female with a normal alkaline phosphatase had an AMA profile identical to typical PBC. After a variable follow-up period (8-14 months), sera from 8 of 9 of these people were re-obtained for AMA and relative epitope mapping. Interestingly, the reactivity had a wider AMA pattern than before.

Clinicopathological study of primary biliary cirrhosis negative for antimitochondrial antibodies

Primary biliary cirrhosis (PBC) is characterized by the occurrence of antimitochondrial antibodies (AMA) and the progressive destruction of intrahepatic bile ducts, followed by biliary cirrhosis. However, there are about 5% of PBC patients who show clinicopathological features of PBC but are negative for AMA. In this study, clinicopathological features, as well as antibody reactivity against recombinant (r)-mitochondrial polypeptides, were examined in 30 AMA negative PBC patients and 38 AMA positive PBC patients, in whom the presence of AMA had been determined by indirect immunofluorescence (IF). There were few differences in the clinical and serological features between both groups. Histopathologic features, including staging, bile duct lesions and granuloma, were also similar in both groups. Among the 30 IF-tested AMA negative patients, 29 were also negative against beef heart mitochondrial proteins, but 24 reacted to one or more of the following r-polypeptides, as determined by immunoblotting: E1 alpha of pyruvate dehydrogenase complex, the E2 subunit of pyruvate dehydrogenase complex, and the branched-chain 2-oxo-acid dehydrogenase complex. The remaining six AMA-negative patients were asymptomatic, and histologically resembled having stage 1 of the disease, with relatively mild lymphocytic piecemeal necrosis. One case was positive for anti-smooth muscle antibody. The other clinicopathological features of these patients were similar to those of other AMA negative patients. The present study found that a majority of the AMA-negative patients fulfilling other clinicopathological criteria of PBC, had features similar to the AMA-positive PBC patients, and that a majority of IF AMA-negative patients were positive for r-polypeptides of the 2-oxo-acid dehydrogenase complex. It seems that nearly all the AMA negative patients possess a broad spectrum of antibody profile of AMA, in addition to clinicopathological and serological features.

Persistence of autoantibodies against recombinant mitochondrial and nuclear pore proteins after orthotopic liver transplantation for primary biliary cirrhosis

Primary biliary cirrhosis is an autoimmune disease characterized by high titer autoantibodies predominantly against mitochondrial antigens PDC-E2, BCOADC-E2 and OGDC-E2. Currently orthotopic liver transplant (OLT) is the major form of treatment for end-stage primary biliary cirrhosis (PBC), but it is still unclear whether the autoimmune response continues post-transplantation. In this study we took advantage of a well-defined collection of sera collected serially before and after liver transplantation. We assayed these sera for quantitative and isotype-specific titers of antibodies against a set of recombinant mitochondrial autoantigens. We also studied reactivity to gp210. Serum samples were taken before transplantation and at intervals of 6 months, 1, 2, and 3 years after OLT. Before OLT 24/35 patients were AMA-positive, including seven out of the 35 to PDC-E2 alone, eight to both PDC-E2 and OGDC-E2, six to both PDC-E2 and BCOADC-E2, two to BCOADC-E2 alone and one to OGDC-E2. Following OLT, the frequency of sera that responded to PDC-E2 alone increased from seven to 12/35. Similarly, reactivity to BCOADC-E2 slightly increased from two to four out of 35. However, there was an overall decrease in sera that responded to more than one antigen. Neither Ig isotype nor subclass of the autoimmune response changed following OLT. Findings with gp210 were similar, in that reactivity to gp210 was found in nine out of 35 patients pre-OLT; following OLT the frequency decreased to seven out of 35 patients. Overall, the titers of AMAs decline slightly during the first year post-OLT, but are equivalent to pre-OLT values by 6 months. Moreover, the antibody subclass/ isotype remained unchanged. These data suggest that the removal of a diseased PBC liver has little, if any, impact on the serological characteristics of PBC. Moreover, it provides information regarding the natural history of PBC, particularly on the long latency time for disease development.

Comparative studies of antimitochondrial autoantibodies in sera and bile in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by destruction of intrahepatic bile ducts. Although the pathogenesis of this disease is still unknown, high titers of antimitochondrial autoantibodies (AMA) have long been recognized in patient sera. However, little is known about the presence of AMA in bile. In this study, we investigated bile and sera from patients with PBC and healthy controls for the presence of AMA and mitochondrial autoantigens. AMA were detected in the bile of 17 of 19 patients (89.4%) with PBC; they were specifically directed against the pyruvate dehydrogenase complex (PDC-E2) in 15 of 19 patients (78.9%), to the branched-chain 2-oxo-acid dehydrogenase complex E2 (BCOADC-E2) in 6 of 19 patients (31.6%), and to the 2-oxoglutarate dehydrogenase complex E2 (OGDC-E2) in 1 of 19 patients (5.3%). In a comparative study of sera from the same patients, anti-PDC-E2 antibodies were found in 19 of 19 patients (100%), anti-BCOADC in 9 of 19 patients (47.3%), and anti-OGDC-E2 in 4 of 19 patients (21.1%) patients. AMA in bile were always found together with antibodies of corresponding specificities in the serum from the same patient. Immunoglobulin (Ig)A AMA were found in the bile of 9 of 19 patients (47.7%) with PBC; they were specifically directed against PDC-E2 in 8 of 19 patients (42.1%) and to BCOADC in 2 of 19 patients (10.5%). Epitope mapping of IgA anti-PDC-E2 antibodies indicated that, like serum autoantibodies, the immunodominant epitope is directed against the inner lipoyl domain of PDC-E2. The prevalence and antigen reactivity of IgA AMA in sera correlated completely with IgA AMA in bile. Autoantibodies against nuclear envelope pore proteins (gp210) were found in 1 of 8 (12.5%) sera of patients with PBC, but not in bile. Furthermore, and of particular interest, we detected the autoantigens, PDC-E2, OGDC-E2, and BCOADC-E2, in the bile of 12 of 19 patients (63.2%), 9 of 19 patients (47.4%), and 9 of 19 patients (47.4%), respectively; PDC-E2 was found in only 1 of 17 (5.9%) disease controls. Although the presence of AMA in bile may merely reflect the presence of these antibodies in sera, the simultaneous detection of mitochondrial autoantigens in bile suggests an increase of mitochondrial autoantigens at inflammatory sites. Such autoantigens, coupled with AMA, may augment the local immune response and disease progression.

The role of T cells in primary biliary cirrhosis

While fervently studied by several laboratories, the role of T cells in the pathogenesis of primary biliary cirrhosis (PBC) still remains a mystery. The studies concerning cell phenotype, antigen specificity, and major histocompatibility complex (MHC)-T-cell receptor (TCR) interaction gathered thus far all address important aspects of this intriguing conundrum. However, the lack of an animal model and the genetic diversity of the human population with PBC make this task even more difficult. The possibilities regarding immune therapy resulting from such studies are of great importance. Future work concerning the T-cell epitopes--for both the pyruvate dehydrogenase complex (PDC), its related mitochondrial autoantigens, and any as yet unidentified PBC-specific autoantigens--may provide valuable information with regard to disease therapy. In addition, knowledge with regard to TCR usage and MHC association will help to clarify the pathogenic mechanisms of this enigmatic disease.

In situ nucleic acid hybridization of cytokines in primary biliary cirrhosis: predominance of the Th1 subset

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by destruction of the intrahepatic bile ducts. It is generally believed that cellular immune mechanisms, particularly involving T cells, result in this bile duct damage. The relative strength of Th1 and Th2 responses has recently been proposed to be an important factor in the pathophysiology of various autoimmune diseases. In this study, we have attempted to identify the Th subset balance in PBC, by detection of cytokines specific to the two T-cell subsets, i.e., interferon gamma (IFN-gamma) for Th1 cells and interleukin-4 (IL-4) for Th2 cells. We analyzed IFN-gamma and IL-4 messenger RNA (mRNA) positive cells in liver sections from 18 patients with PBC and 35 disease controls including chronic active hepatitis C, extrahepatic biliary obstruction (EBO), and normal liver, using nonisotopic in situ hybridization and immunohistochemistry. Mononuclear cells expressing IFN-gamma and IL-4 mRNA were aggregated in inflamed portal tracts in PBC livers, but were rarely present in extrahepatic biliary obstruction, alcoholic fibrosis, or normal liver sections. The IFN-gamma and IL-4 mRNA positive cells in PBC livers were detected in significantly higher numbers than in control livers (P < .01). Moreover, IFN-gamma mRNA expression was more commonly detected than IL-4 expression in PBC livers, and the levels of IFN-gamma mRNA expression were highly correlated with the degree of portal inflammatory activity. IFN-gamma mRNA-positive cells were detected primarily around damaged bile ducts that were surrounded by lymphoid aggregates. The data indicate that Th1 cells are the more prominent T-cell subset in the lymphoid infiltrates in PBC.

A study of antimitochondrial antibodies in a random population in Estonia

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by the spontaneous destruction of the small intrahepatic bile ducts. The hallmark serologic feature of PBC is the presence of high-titer antimitochondrial antibodies (AMA). Both the incidence and prevalence of PBC varies geographically; epidemiological data may provide valuable insight regarding the pathogenic mechanisms and etiology of disease. Thus far, the majority of studies on the occurrence of PBC and AMAs have been derived from autopsy, mortality figures, or hospital admission records. The numbers reported reflect only those patients with clinical disease. To address this issue, an adult population sample representing all age groups in the village of Karksi-Nuia in southern Estonia was selected for a study of AMA incidence. This village has unique features that make it ideal for such a study. First, the village is remote and a substantial number of families have lived in the area for generations. There is also a limited influx of new families into the village, therefore providing a limited genetic repertoire. In this unselected adult population, we examined AMA incidence by both immunoblot and ELISA, using native and recombinant antigens. Of the 1461 people studied, 13 (0.89%) were AMA positive. A similar frequency (0.96%) was found among 104 persons from a neighboring village, who subsequently joined the study. Our study suggests that the presence of AMA in Estonia is in agreement with the reported incidence of less than 1% AMA in a mixed hospital population.

In situ nucleic acid hybridization of pyruvate dehydrogenase complex-E2 in primary biliary cirrhosis: pyruvate dehydrogenase complex-E2 messenger RNA is expressed in hepatocytes but not in biliary epithelium

Pyruvate dehydrogenase-E2, or a cross-reactive molecule, has been shown by a variety of immunohistochemical methods to be present in increased amounts in biliary epithelial cells (BEC) in primary biliary cirrhosis (PBC). In this study, to further understand the nature of the immunoreactive molecule in BEC, we examined the expression of pyruvate dehydrogenase complex-E2 (PDC-E2) messenger RNA (mRNA) and PDC-E2 protein in sections of livers from patients and controls to help identify the molecule found in BEC. We performed in situ hybridization using an antisense probe against the major epitope of PDC-E2. The data were very striking and suggested that there was no increased production of PDC-E2 in BEC. For example, in livers from patients with PBC, PDC-E2 mRNA was found in periportal hepatocytes in 16 of 17 cases (94%). In contrast, interlobular bile ducts and septal bile ducts had detectable levels of PDC-E2 mRNA in only 1 of 17 (6%) and 3 of 8 (38%) cases, respectively. Interestingly, proliferating bile ductules contained detectable levels of mRNA in 12 of 15 cases (80%). In control liver, periportal hepatocytes were positive in 15 of 17 cases (88%). Interlobular bile ducts, septal bile ducts, and proliferating bile ductules expressed mRNA signals in 4 of 17 (24%), 2 of 10 (20%), and 14 of 16 (88%), respectively. When formalin-fixed, paraffin-embedded sections were examined by immunohistochemical staining with anti-PDC-E2 monoclonal antibody (mAb) C355.1, the interlobular bile ducts showed typical aberrant apical staining in all 10 PBC cases, but 0 of 9 liver controls. Periportal hepatocytes, proliferating bile ductules and infiltrating mononuclear cells stained with C355.1 but in a characteristic mitochondrial staining pattern. The presence of a PDC-E2-like molecule recognized by C355.1 is not reflected by the expression levels of PDC-E2 mRNA in the BEC of patients with PBC.

Cryptic antigenic determinants on the extracellular pyruvate dehydrogenase complex/mimeotope found in primary biliary cirrhosis. A probe by affinity mass spectrometry

Affinity mass spectrometry (AMS) was used to evaluate the structural diversity of the E2 component of pyruvate dehydrogenase complex (PDC) in normal and diseased liver cells, including those from patients with the autoimmune disease primary biliary cirrhosis (PBC). Two different antibodies to PDC-E2, the immunodominant mitochondrial autoantigen in patients with PBC, were used. AMS was performed directly on frozen liver sections and purified bile duct epithelial cells. Mass spectrometric signals associated with the molecular recognition of PBC-specific antigenic determinants were enhanced by an in situ enzyme-linked signal amplification process. Samples from patients with PBC gave strong positive signals for the antigen(s) recognized by the monoclonal antibody C355.1. Conversely, tissues from normal and disease controls showed only a minimal signal. AMS was used to identify specific antigenic determinants within the E2 component of PDC for comparison with unknown antigenic determinants observed by affinity capture with C355.1 monoclonal antibody from PBC samples. PDC components bound to C355.1 were mapped and identified by mass before dissociation from the E2 component. A similar approach was used to identify unknown antigenic determinants associated with PBC. We believe AMS may be an important new approach with wide application to the identification of molecules associated with a number of disease states.

Inhibition of PDC-E2 human combinatorial autoantibodies by peptide mimotopes

Immunohistochemical studies have shown that a unique immunoreactive molecule is present near the apical region of human biliary epithelial (BE) cells in patients with primary biliary cirrhosis (PBC). This can be visualized by confocal microscopy in PBC livers using a number of unique monoclonal antibodies to the E2 component of pyruvate dehydrogenase complex (PDC-E2), the autoantigen most commonly recognized by antimitochondrial antibodies (AMA). One such antibody, the murine mAb C355.1 was used to identify peptide mimotopes of PDC-E2 by screening a random dodecapeptide phage library ON 159.2 to identify the possible biochemical nature of this apical staining molecule. Out of 36 independent clones, 29 showed a common sequence and seven other sequences were singly represented. Three common amino acid motifs (SYP, TYVS and VRH) were found among these eight sequences. Similar to C355.1, the human combinatorial antibodies derived from a patient with PBC, SP1 and SP4, recognize the inner lipoyl domain of PDC-E2. However, when these antibodies are used to stain PBC BE cells, SP4 stains the apical region of PBC BE cells with high intensity whereas SP1 produces only cytoplasmic staining. Competitive inhibition of immunohistochemical staining using PDC-E2 specific human combinatorial antibodies SP1 and SP4 was performed using five of the above dodecapeptides. Interestingly, the peptides selected with C355.1 differentially inhibited the binding of SP1 and SP4 to PBC BE cells. Finally, rabbit sera raised against one such peptide (WMSYPDRTLRTS) stained BE cells from patients with PBC with a higher intensity than controls. Comparable data was obtained with immunoelectronmicroscopy. These data suggest that a molecular mimic of PDC-E2 is present at the external aspect of PBC BE cells.

Immunohistochemical evidence of disease recurrence after liver transplantation for primary biliary cirrhosis

Whether primary biliary cirrhosis (PBC) recurs after liver transplantation has remained an interesting and controversial issue; rejection, viral hepatitis, and drug effects all may mimic recurrent PBC histologically and biochemically. Furthermore, reliable clinical criteria for PBC recurrence are lacking. In this study, the issue of disease recurrence using a well-characterized monoclonal antibody (MAb), C355.1, that reacts with the immunodominant mitochondrial autoantigen of PBC (pyruvate dehydrogenase complex [PDC-E2]) was addressed. When used in an immunohistochemical assay, C355.1 produces intense apical staining of bile duct epithelium specifically in liver sections of patients with PBC and may be the earliest known marker of PBC. Immunohistochemical and histological analysis of serial liver biopsy specimens of 67 patients pre- and post-orthotopic liver transplantation (OLT), including 38 patients with PBC and 29 non-PBC liver disease controls, was performed. Sections were stained with MAb C355.1 or the control MAb C315 and analyzed to determine whether there was a recurrence of apical reactivity in the bile ducts of the posttransplantation biopsy specimens. The immunohistochemical staining was correlated with the histological findings and serum biochemistries at the time of the biopsy. Our data indicate that a significant number of patients who underwent transplantation for PBC (28 of 38) but not controls (0 of 29) develop a staining pattern of liver bile duct epithelium with MAb C355.1 that is indistinguishable from the pretransplantation pattern. Of the 28 patients with this apical staining pattern, 8 were characterized histologically as possible recurrent PBC, 2 as chronic rejection, 2 as acute rejection, 9 as nonspecific changes, 4 as normal or near normal, and 3 had other histological changes. Only 50% of the patients with apical C355.1 staining had liver enzyme levels suggestive of cholestasis. Thus, there appears to be immunohistochemical evidence that supports the concept of recurrence of PBC after OLT. The appearance of biliary epithelial abnormalities before the clinical appearance of disease is important not only for liver transplantation but also for understanding the natural history of PBC.

Random phage mimotopes recognized by monoclonal antibodies against the pyruvate dehydrogenase complex-E2 (PDC-E2)

Dihydrolipoamide acetyltransferase, the E2 component of the pyruvate dehydrogenase complex (PDC-E2), is the autoantigen most commonly recognized by autoantibodies in primary biliary cirrhosis (PBC). We identified a peptide mimotope(s) of PDC-E2 by screening a phage-epitope library expressing random dodecapeptides in the pIII coat protein of fd phage using C355.1, a murine monoclonal antibody (mAb) that recognizes a conformation-dependent epitope in the inner lipoyl domain of PDC-E2 and uniquely stains the apical region of bile duct epithelium (BDE) only in patients with PBC. Eight different sequences were identified in 36 phage clones. WMSYPDRTLRTS was present in 29 clones; WESYPFRVGTSL, APKTYVSVSGMV, LTYVSLQGRQGH, LDYVPLKHRHRH, AALWGVKVRHVS, KVLNRIMAGVRH and GNVALVSSRVNA were singly represented. Three common amino acid motifs (W-SYP, TYVS, and VRH) were shared among all peptide sequences. Competitive inhibition of the immunohistochemical staining of PBC BDE was performed by incubating the peptides WMSYPDRTLRTS, WESYPDRTLRTS, APKTYVSVSGMV, and AALWGVKVRHVS with either C355.1 or a second PDC-E2-specific mAb, C150.1. Both mAbs were originally generated to PDC-E2 but map to distinct regions of PDC-E2. Two of the peptides, although selected by reaction with C355.1, strongly inhibited the staining of BDE by C150.1, whereas the peptide APKTYVSVSGMV consistently inhibited the staining of C355.1 on biliary duct epithelium more strongly than the typical mitochondrial staining of hepatocytes. Rabbit sera raised against the peptide WMSYPDRTLRTS stained BDE of livers and isolated bile duct epithelial cells of PBC patients more intensively than controls. The rabbit sera stained all size ducts in normals, but only small/medium-sized ductules in PBC livers. These studies provide evidence that the antigen present in BDE is a molecular mimic of PDC-E2, and not PDC-E2 itself.

Molecular aspects and the pathological basis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) has been considered to be a 'model auto-immune disease' for more than two decades. However, the underlying pathophysiology of PBC and the relationship with the associated serological abnormalities have been hitherto elusive. Beginning in 1987 with the cloning and subsequent identification of the mitochondrial autoantigens of PBC, progress has come rapidly and we can now sketch several potential pathogenic pathways through which disease occurs. More than 90% of patients with PBC produce autoantibodies to mitochondria, and the antoantigens involved have been identified as related components of the 2-oxo-acid dehydrogenase complexes (OADC), including the E2 subunits of the pyruvate dehydrogenase complex (PDC-E2), the branched chain 2-oxo-acid dehdrogenase complex and 2-oxo-glutarate dehydrogenase complex, Protein X and E1 alpha. The cDNAs of each of the E2 subunits of OADC have been cloned and characterized. Moreover, the epitopes of the antimitochondrial antibodies (AMA) have been mapped at the highly conserved lipoyl domain E2 subunits. The use of recombinant peptides produced by these clones has greatly facilitated the detection of AMA. In addition, nucleotide sequence analysis of PDC-E2 specific human monoclonals and combinatorial Fabs strongly suggests that these autoantibodies are derived from clonal selection of a restricted set of somatically mutated immunoglobulin germline genes. Most interestingly, however, the use of monoclonal reagents to PDC-E2 has demonstrated that there is an increased expression of either PDC-E2, or a cross-reactive molecule, on the luminal surface of biliary epithelial cells in patients with PBC. These data provide a scenario to explain the tissue specific pathology associated with PBC and several interesting underlying pathophysiological mechanisms.

Mononuclear cells isolated from fibrotic skin lesions in avian scleroderma constitutively produce fibroblast-activating cytokines and immunoglobulin M

University of California, Davis line 200 and 206 chickens develop an inherited autoimmune fibrotic disease associated with autoantibodies and other features similar to human scleroderma. Early in life, line 200/206 chickens develop mononuclear cell (MNC) infiltrates in the skin, followed by severe dermal fibrosis and vascular occlusions. Cultured fibroblasts derived from fibrotic skin lesions of line 200/206 chickens display an activated phenotype producing elevated quantities of collagen and glycosaminoglycan (GAG) compared to fibroblasts derived from normal chicken skin. To demonstrate a link between skin mononuclear cell infiltration and fibroblast activation, we cultured MNC isolated from developing fibrotic skin lesions, normal appearing skin, and peripheral blood of line 206 chickens for 24-72 h. Subsequent assay of MNC culture supernatants for effect on the collagen and GAG production of normal chicken skin fibroblasts demonstrated that only fibrotic lesion MNC supernatants contained significant collagen and GAG synthesis stimulatory activity. Both stimulatory activities were constitutively produced, undialyzable, heat and protease sensitive, and coeluted on gel filtration with a M(r) of 24-32 kD. Gel filtration also revealed that fibrotic lesion MNC secrete a protein > 250 kD, which we have identified as immunoglobulin (Ig) M by Western blot analysis. These results demonstrate that skin infiltrating MNC secrete both fibroblast-activating cytokines and IgM and thus they likely play an important role as effector cells in the development of dermal fibrosis and autoantibodies in this avian model of scleroderma.

Thymic microenvironmental abnormalities in MRL/MP-lpr/lpr, BXSB/MpJ Yaa and C3H HeJ-gld/gld mice

Efforts to define the stromal architecture of thymic tissues of normal mice have used a panel of monoclonal antibodies (MTS series) to examine the localization of cell subtypes, including reagents that define thymic epithelial and stromal elements. Recent work with these MTS mAbs disclosed significant abnormalities in the thymic cortex of New Zealand mice including the appearance of medullary type epithelial cells in the cortical areas and the presence of epithelial free spaces or 'cortical holes'. To determine whether such abnormalities are unique to NZB mice or are found in other models of murine lupus, we examined the thymi of MRL/MP-lpr/lpr BXSB/MpJ Yaa, C3H/HeJ-gld/gld and C57BL/6 control mice. Thymi from all models of murine lupus showed dramatic alterations in the thymic microarchitecture. For example, staining with MTS10, a mAb which is specific for subcapsular and medullary epithelia, was decreased in the subcapsular and medullary regions. Moreover, there was increased staining in the thymic cortex, suggesting an abnormality in the localization of MTS10-reactive cells. Moreover, all three murine lupus strains demonstrated 'cortical holes' or cortical epithelial cell-free regions. By using MTS33, MTS35 and flow cytometry, both C3H/gld and BXSB/Yaa, but not MRL/lpr mice, showed decreased cortical thymocyte frequencies. Possible defects in the maturation of double-positive thymocytes to single-positive status in C3H/gld mice is implied by abnormally high levels of double-positive cells and low levels of single-positive cells. Finally, MRL/lpr thymocytes had lowered frequencies of CD3-4+8+ and increased levels of TCR-alpha/beta high cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal expression of the E2 component of the pyruvate dehydrogenase complex on the luminal surface of biliary epithelium occurs before major histocompatibility complex class II and BB1/B7 expression

Primary biliary cirrhosis (PBC) is a chronic autoimmune liver disease characterized histologically by nonsuppurative destructive cholangitis. Sera from patients with PBC react with a series of intramitochondrial enzymes with the immunodominant response directed against the E2 component of the pyruvate dehydrogenase complex (PDC-E2). Recently, using tissue sections of late-stage PBC, we showed that there is increased expression in biliary epithelial cells of patients with PDC-E2 or a molecule cross-reactive with PDC-E2. Previous work has shown that biliary epithelial cells of patients with PBC express an increased amount of class II. To address the sequence of events in the evolution of PBC, we have focused our attention in this study on early biliary epithelial lesions. In particular, we have studied the liver of 22 female patients with PBC that was diagnosed as either stage I or stage II using both a mouse monoclonal antibody that has reactivity similar to human autoantibodies as well as a human Fab combinatorial prepared from the lymph node of a PBC patient. Tissues were simultaneously stained using antibodies to PDC-E2, class II, and BB1/B7. As a positive control, tissues from late-stage PBC were studied concurrently. By determining the order of expression among the three molecules, PDC-E2, class II, and BB1/B7, we report that the expression of PDC-E2 or a PDC-E2-like molecule on biliary duct epithelium of patients with PBC precedes the expression of BB1/B7 and major histocompatibility complex (MHC) class II molecules. The alteration of an autoantigen in biliary duct epithelium may be the earliest lesion in PBC.

Immunohistochemical analysis of adhesion molecules in the micro-environment of portal tracts in relation to aberrant expression of PDC-E2 and HLA-DR on the bile ducts in primary biliary cirrhosis

We have examined immunohistochemically the expression of adhesion molecules in the micro-environment of portal tracts and their relationship to the expression of the pyruvate dehydrogenase E2 complex (PDC-E2) and HLA-DR in liver biopsy specimens. Ten cases of primary biliary cirrhosis (PBC) and 19 controls were examined, including four cases of extrahepatic biliary obstruction, six of chronic viral hepatitis, and nine normal livers. In PBC, the damaged small bile ducts demonstrated an increased expression of PDC-E2 and an aberrant expression of HLA-DR; about half of these damaged bile ducts also expressed intercellular adhesion molecules (ICAM)-1 and a few expressed vascular adhesion molecule (VCAM)-1. In addition, lymphocyte function-associated antigen (LFA)-1 and very late antigen (VLA)-4 were expressed on infiltrating lymphocytes around these bile ducts. In contrast, in control livers, these alterations in antigen expression on the bile ducts were either not observed or were only focal and weak, when present. These findings suggest that ICAM-1/LFA-1 and also VCAM-1/VLA-4 linkages between the damaged bile ducts and lymphocytes may facilitate antigen-specific reactions such as the presentation of antigens, possibly PDC-E2, to the periductal lymphocytes in PBC. ICAM-1, VCAM-1, and E-selectin were strongly expressed on the endothelial cells of some vessels in the portal tracts in PBC, suggesting the facilitation of the recruitment of lymphocytes around the bile ducts of PBC. VCAM-1, a member of the immunoglobulin superfamily, has not hitherto been reported on bile ducts.

Heterogeneity of autoreactive T cell clones specific for the E2 component of the pyruvate dehydrogenase complex in primary biliary cirrhosis

The extraordinary specificity of bile duct destruction in primary biliary cirrhosis (PBC) and the presence of T cell infiltrates in the portal tracts have suggested that biliary epithelial cells are the targets of an autoimmune response. The immunodominant antimitochondrial response in patients with PBC is directed against the E2 component of pyruvate dehydrogenase (PDC-E2). Hitherto, there have only been limited reports on the characterization and V beta usage of PDC-E2-specific cloned T cell lines. In this study, we examined peripheral blood mononuclear cells (PBMC) for their reactivity to the entire PDC complex as well as to the E1- and E2-specific components. We also examined the phenotype, lymphokine profile, and V beta usage of PDC-specific T cell clones isolated from cellular infiltrates from the livers of PBC patients. We report that PBMC from 16/19 patients with PBC, but not 12 control patients, respond to the PDC-E2 subunit. Interestingly, this response was directed to the inner and/or the outer lipoyl domains, despite the serologic observation that the autoantibody response is directed predominantly to the inner lipoyl domain. Additionally, lymphokine analysis of interleukin (IL) 2/IL-4/interferon gamma production from individual liver-derived autoantigen-specific T cell clones suggests that both T helper cell Th1- and Th2-like clones are present in the liver. Moreover, there was considerable heterogeneity in the T cell receptor for antigen (TCR) V beta usage of these antigen-specific autoreactive T cell clones. This is in contrast to murine studies in which animals are induced to develop autoimmunity by specific immunization and have an extremely limited T cell V beta repertoire. Thus, our data suggest that in human organ-specific autoimmune diseases, such as PBC, the TCR V beta repertoire is heterogenous.

Biliary epithelial expression of pyruvate dehydrogenase complex in primary biliary cirrhosis: an immunohistochemical and immunoelectron microscopic study

It has been reported recently that there is a unique distribution of the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2) on biliary epithelial cells in patients with primary biliary cirrhosis (PBC) but not primary sclerosing cholangitis. This distribution has been demonstrated using a mouse monoclonal antibody, coined C355.1. The epitope recognized by C355.1 is near the lipoic acid binding site of PDC-E2. C355.1 inhibits PDC-E2 activity in vitro and, unlike a panel of other monoclonal antibodies against different regions of PDC-E2, appears to bind not only to mitochondria but also to a unique antigen expressed predominantly on the luminal side of biliary epithelial cells in PBC. We have extended these observations by studying the subcellular reactivity of C355.1 using postembedding immunoelectron microscopy on the intrahepatic small bile ducts of PBC livers, extrahepatic biliary obstruction (EBO) livers, and normal livers. We report that the reactivity of C355.1 can be classified into two categories. The first category is characterized by small foci of reaction products that were randomly dispersed in cytoplasm, particularly in supranuclear areas; the ultrastructural characterization of these foci was impossible to define but was similar in PBC and EBO. However, of particular interest was the second category of reactivity, which was characterized by deposition of reaction products around the biliary lumen, including microvilli and adjacent subluminal ectoplasm and secretory substances in the biliary lumen. This staining pattern was frequent in PBC livers, only occasionally evident in EBO livers, and not found in normal livers. These data further define and highlight the unique subcellular distribution of PDC-E2 around the biliary lumen in PBC livers and suggest that this abnormality is related to the pathogenesis of bile duct lesions.

Hepatitic bile duct injuries in chronic hepatitis C: histopathologic and immunohistochemical studies

Interlobular bile ducts are reported to be damaged in viral hepatitis. Such damages are called hepatitic duct injuries and mimic chronic nonsuppurative destructive cholangitis of primary biliary cirrhosis. In this study, hepatitic bile duct injuries were evaluated histopathologically and immunohistochemically in 149 needle liver biopsy specimens from patients with chronic hepatitis C and compared immunohistochemically with primary biliary cirrhosis. Fifty-one of the needle biopsies from patients with chronic hepatitis C (34.2%) showed hepatitic bile duct injuries which were distributed focally in the liver and showed variable epithelial damages such as cytoplasmic swelling, vacuolation and acidophilia, nuclear pleomorphism, and loss of nuclear polarity. Some of the injured bile ducts were embedded within lymphoid aggregates, whereas others were surrounded by lymphocytes as well as other inflammatory cells to varied degrees. The majority of lymphoid cells around hepatitic bile duct injury were B- and T-cells mixed in various proportions, and activated T-cells were occasionally found within the biliary epithelial layer. Histopathologic and serial section studies disclosed that bile duct loss was rare in chronic hepatitis C. Statistical analysis revealed that advancement of chronic hepatitis and the degree of necroinflammatory processes of the liver, particularly in the portal tracts, were positively correlated with the occurrence of hepatitic bile duct injuries. Immunohistochemical studies demonstrated that, whereas strong ectopic expression of HLA-DR and enhanced expression of HLA-A,B,C, and pyruvate dehydrogenase E2-complex in biliary epithelial cells were frequently observed in chronic nonsuppurative destructive cholangitis of primary biliary cirrhosis, such unusual expressions were generally absent or mild, even if present, in bile duct injuries in chronic hepatitis C.(ABSTRACT TRUNCATED AT 250 WORDS)

Human combinatorial autoantibodies and mouse monoclonal antibodies to PDC-E2 produce abnormal apical staining of salivary glands in patients with coexistent primary biliary cirrhosis and Sjögren's syndrome

An increase in the incidence of Sjögren's syndrome in patients with primary biliary cirrhosis has been noted. Indeed, primary biliary cirrhosis has been described as a ductal disease with involvement not only of the biliary tract but of epithelial ductal cells in other organs. We have previously reported the development of a panel of mouse monoclonal antibodies directed at PDC-E2, the major autoantigen of primary biliary cirrhosis. One such antibody, C355.1, but none of the other monoclonal antibodies, reacted not only with mitochondria but also with the apical region of biliary epithelium of patients with primary biliary cirrhosis but not in similar specimens from patients with other liver disease or normal human liver. In addition, we have reported the development of human combinatorial antibodies specific for PDC-E2; these reagents also reacted uniquely with the biliary epithelium of patients with primary biliary cirrhosis. In this paper, we have performed a similar study and have compared the staining of monoclonal antibody C355.1 and a human combinatorial antibody, SP4, with control monoclonal antibodies with respect to their reactivity of salivary glands in 9 patients with primary biliary cirrhosis associated with Sjögren's syndrome, 11 patients with Sjögren's syndrome alone and 7 control patients. Interestingly, the apical region of the salivary gland epithelial cells of approximately 50% of patients with coexisting primary biliary cirrhosis and Sjögren's syndrome had a staining pattern similar to that seen in primary biliary cirrhosis biliary epithelium. In contrast, we did not observe this reactivity in any patient with Sjögren's syndrome alone or in any control patient.(ABSTRACT TRUNCATED AT 250 WORDS)