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Biomedical subjects

M E Gershwin

Publications and source records attributed to M E Gershwin.

At least 19 recordsLinked to original sources
PubMed2001

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.

Amino Acid Sequence↗
PubMed2001

State of complementary and alternative medicine in cardiovascular, lung, and blood research: executive summary of a workshop.

The National Heart, Lung, and Blood Institute and the National Center for Complementary and Alternative Medicine recently cosponsored a workshop on the use of complementary and alternative medicine (CAM) in cardiovascular, lung, and blood research. In view of the increasing use of CAM by the general public, it is imperative to promote credible research by the established biomedical community. The goal of this workshop was to enhance the exchange of information and ideas between alternative medicine practitioners and scientists in cardiovascular, lung, and blood research and to foster collaborative research among these researchers. The workshop focused on 5 areas of research, including a historical and cultural perspective of CAM, methodological issues in clinical trials, herbal medicine, chelation therapy, mind/body (meditation) therapy, and acupuncture. CAM has become widely used without rigorously proven efficacy and safety. To protect the public, it was recommended that the fundamental mechanistic research for these CAM approaches be vigorously pursued and that any large-scale clinical trial be carefully executed to avoid any waste of resources and any unnecessary risk. It was felt that standardization of botanical products and procedure-based CAM intervention, such as acupuncture and meditation, is essential for meaningful basic and clinical research. Although botanical products properly consumed are perceived as generally safe, potential herb-drug interactions are a major safety concern. Clearly, many challenges need to be addressed by the scientific community before the public can be assured of the proper use of CAM.

Acupuncture↗
PubMed2001

Monocyte chemotactic protein-1, -2, and -3 are distinctively expressed in portal tracts and granulomata in primary biliary cirrhosis: implications for pathogenesis.

The monocyte chemotactic proteins (MCPs) form a distinct structurally related subclass of C-C chemokines. MCPs select specific target cells due to binding to a distinct set of chemokine receptors and because of their effects on monocytes, and may participate in the process of granuloma formation during bacterial and/or mycobacterial infections. The aetiology of primary biliary cirrhosis (PBC) is still unclear, although bacterial infection and autoimmune processes have been implicated. In this study, the expression of three of the most potent monocyte chemoattractants, MCP-1, -2, and -3, was examined in patients with PBC and the data were compared with results for other liver diseases including primary sclerosing cholangitis (PSC), chronic viral hepatitis C, hepatic sarcoidosis, and normal liver. MCP-1 was expressed mainly in biliary epithelial cells of all liver specimens, irrespective of the cause of disease. Some mononuclear leukocytes in the portal tract expressed MCP-1 in all the disease groups examined and there were no significant differences in frequency between these groups. In contrast, more than 80% of PBC livers showed MCP-2- and MCP-3-positive mononuclear leukocyte infiltration in portal tracts, particularly around the bile ducts, whereas such cells were far less frequent in the other disease groups or in normal livers. Epithelioid granulomata of PBC patients contained MCP-2- and MCP-3-positive cells at their edge. In double staining experiments, more than 60% of the MCP-positive mononuclear cells co-expressed CD68, suggesting that a proportion of MCP-2- and MCP-3-positive cells are derived from monocytes. These monocytes expressing MCP-2 and MCP-3 may be responsible for the chemotactic activity of more monocytes. Such an expression pattern of MCP-1, -2 and -3 in portal tracts seems to be distinctive for PBC. This pattern underlines the importance of MCP-1, -2, and -3 in the recruitment of monocytes and possibly T lymphocytes into portal tracts, around the injured bile ducts, and into epithelioid granulomata in PBC. The data further implicate bacterial materials derived from bile in the overall pathogenesis of PBC.

Adult↗
PubMed2001

Increased expression of mXBP-1 (TREB-5) in thymic B cells in New Zealand mice.

New Zealand Black mice as well as several other murine models of murine lupus are well known for premature degeneration of thymus and development of autoimmunity. To focus on molecular events unique to murine lupus, we performed differential display using arbitrary primer pairs to distinguish NZB versus BALB/c thymus at 5 weeks of age. Following an extensive analysis of DNA bands that were either consistently up or downregulated and from studies of expression pattern of thymic genes by in situ nucleic acid hybridization, we focused on one clone that was consistently differentially expressed between NZB and BALB/c thymus. This clone was isolated, sequenced, and identified as the murine homologue of the human X box binding protein (hXBP-1), also known as TREB 5. mXBP-1 was found to be consistently upregulated in B cells in the thymic cortex of NZB and (NZBxNZW)F1, but not BALB/c, C3H/HeJ or C57BL/6 mice. In addition, it was dramatically elevated in MRL/ lpr but not MRL/++ mice; similarly, it was increased in BXSB/ Yaa male but not BXSB female thymic cortex. Of particular interest was an absence of mXBP-1 expression in the thymus of NZB/ Bln- Igh6(null)homozygotes. mXBP-1 has several putative functions, including the regulation of MHC class II expression and by virtue of its ability to recognize CRE-like elements shown to be involved in HTLV-1 transcription.

Animals↗
PubMed2001

B cells are selectively associated with thymic cortical but not medullary pathology in NZB mice.

Abnormal expansion of autoantibody-synthesizing B cells and self-reactive T cells, which most likely escape negative selection within the thymus, have both been characterized and reasoned to play a role in the pathogenesis of autoimmunity in NZB mice. Support for this thesis has been our observation that NZB mice have severe cortical and medullary thymic microarchitectural defects. As a means to dissect the roles of T and B cells in the induction of such abnormalities, B cell-deficient NZB mice were bred by backcrossing the Igh6(null)allele on to the NZB background (NZB-muMT mice). Such mice showed undetectable levels of autoantibodies. NZB-muMT mice, as compared to wild-type NZB mice, had lower absolute numbers of CD4(+)T cells. Furthermore, thymic abnormalities in NZB-muMT mice were restricted to the medulla. These data suggest that, while B cells may play a role in thymic cortical abnormalities, the medullary abnormalities are induced by other mechanisms.

Animals↗
PubMed2001

Genomic analysis of differentially expressed genes in liver and biliary epithelial cells of patients with primary biliary cirrhosis.

The characterization of differentially expressed genes provides a powerful tool for identifying molecules that may be involved in the pathogenesis of disease. We have used two independent techniques to identify overexpressed transcripts in bile duct cells and in liver from patients with primary biliary cirrhosis (PBC). In the first method, we used suppressive subtractive hybridization to compare mRNA from isolated PBC bile duct epithelial cells (BECs) to normal BECs and identified 71 clones as transcribed at higher levels in PBC-BECs. Amongst these clones, 62/71 had matches in a non-redundant nucleotide database and 9/71 had matches in an EST database. Of the 62 clones, 51/62 include a complexity of genes involved in cell proliferation, signal transduction, transcription regulation, RNA processing, carbohydrate metabolism and hypothetical/unknown proteins; 4/62 were identified as interstitial collagenase and collagenase precursors, 4/62 as ribosomal proteins, 3/62 as mitochondrial DNA. The mitochondrial cDNA sequences included cytochrome c oxidase, Wnt-13, and the pHL gene, a c-myc oncogene containing coxIII sequence. In the second method, we constructed cDNA libraries from three different PBC livers and sequenced a total of 12,324 independent clones. These 12,324 clones underwent virtual subtraction with 2,814,148 independent clones from Incyte LifeSeq libraries. Twenty one sequences were identified as unique to PBC liver. Collectively, these approaches identified a number of genes involved in signalling, RNA processing, mitochondrial function, inflammation, and fibrosis. Interestingly, both Wnt-13 and Notch transcripts are overexpressed in PBC liver. Further studies are needed to focus on the significance of these genes during the natural history of disease.

Bile Ducts↗
PubMed2001

Single nucleotide polymorphisms of the mannose-binding lectin are associated with susceptibility to primary biliary cirrhosis.

Although the immunopathogenesis of primary biliary cirrhosis (PBC) remains unknown, familial clustering of patients with PBC suggests an important role for genetic factors. In addition, recent data support the thesis that the mucosal immune response against intraluminal pathogens may be involved with the onset of PBC. Mannose-binding lectin (MBL) is a key factor in innate mucosal defenses and has several key single nucleotide polymorphisms (SNPs). To study whether MBL gene SNPs are associated with susceptibility to PBC, we studied 65 patients with PBC and 218 controls by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequence specific priming-polymerase chain reaction (SSP-PCR) to examine four polymorphic loci: two (H/L and X/Y) within the promoter region and the other two (P/Q and A/B) within exon-1. We also analyzed serum MBL concentrations. Interestingly, the prevalence of haplotype HYPA, leading to hyper-production of MBL, as well as HYPA/HYPA genotype were significantly increased in PBC compared to controls (0.53 vs. 0.44, P=0.031; 33.9%vs. 17.0%, P=0.003, respectively). Furthermore, individuals homozygous for HYPA had a significantly increased risk for PBC (odds ratio (OR)=2.51, 95% confidence interval (CI)=1.34-4.66). Our results demonstrate that the MBL genotype can be significantly associated with increased risk for PBC, and further, that increased production of MBL plays a critical role in immunopathogenesis.

Carrier Proteins↗
PubMed2001

The follow-up of asymptomatic persons with antibodies to pyruvate dehydrogenase in adult population samples.

PURPOSE: The presence of antimitochondrial antibodies (AMA), the hallmark of primary biliary cirrhosis (PBC), precedes the clinical manifestation of the disease for many years. The main mitochondrial autoantigen is the E2 component of the pyruvate dehydrogenase complex (PDC). The aim of this study was to identify anti-PDC-positive persons from two Estonian populations by different methodologies and to follow up the positive cases. METHODS: Enzyme-linked immunosorbent assay (ELISA) tests for antibodies to native PDC and recombinant PDC-E2 fusion protein were performed in 1461 persons (age range, 15-95 years) from Karksi-Nuia (plus 104 volunteers from the neighborhood) and to native PDC in 497 persons (age range, 50-91 years) from Abja-Paluoja (plus 28 volunteers from that neighborhood). Positive cases were tested with an enzyme inhibition assay. RESULTS: We identified 14 asymptomatic persons with antibodies to native PDC and/or recombinant PDC-E2 from these two population samples. Eight of the 14 were available for follow-up. Three of the 8 developed abnormal liver biochemical test results by the ninth year of follow-up. These persons also had, or developed, during the follow-up, a positive AMA immunofluorescence test, inhibitory antibodies to PDC, and anti-PDC of at least IgG and IgA class. Five of the 8 persons with low levels of anti-PDC, of only one immunoglobulin class reacting with only one PDC preparation, did not show any signs of cholestasis or changes in their immunoreactivity during follow-up. CONCLUSIONS: A significant number of asymptomatic patients found to have antibodies to PDC are at high risk of developing primary biliary cirrhosis.

Adult↗
PubMed2001

Primary biliary cirrhosis: lessons learned from an organ-specific disease.

Primary biliary cirrhosis is an autoimmune liver disease that predominantly affects women and is characterized by chronic progressive destruction of small intrahepatic bile ducts with portal inflammation and subsequent fibrosis. The serological hallmark is the presence of antimitochondrial antibodies, which are found in 95% of patients. These antibodies are directed against the 2-oxo-acid dehydrogenase complexes located on the inner membrane of mitochondria. Although the role of antimitochondrial antibodies in the pathogenesis is unknown, the presence of antibodies has allowed detailed immunological definition of the antigenic epitopes, the autoantibodies, and the T-cell response. Theories have been proposed regarding the mechanism of immune-mediated bile duct damage in primary biliary cirrhosis, including the possible role of T-cell-mediated cytotoxicity and molecular mimicry. Primary biliary cirrhosis is usually diagnosed based on the triad of elevated alkaline phosphatase, antimitochondrial antibodies, and characteristic histological changes on liver biopsy. Biochemical liver abnormalities are consistent with the presence of cholestasis and include an elevation of both serum alkaline phosphatase and gamma-glutamyl transpeptidase, with or without elevation of aminotransferase levels. Ursodeoxycholic acid, a dihydroxy bile acid, appears to be the only effective therapy in preventing or delaying the need for liver transplantation. However, a number of patients receiving ursodeoxycholic acid still develop progressive disease and require transplantation; at present, liver transplantation is the only effective therapy for end-stage primary biliary cirrhosis.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed2001

Chronic idiopathic urticaria.

Chronic idiopathic urticaria is a disabling disease that affects many facets of life. Management requires knowledge of the etiology, as well as the treatment protocol. Physicians should also be aware of the overlap between chronic urticaria and idiopathic angioedema.

Chronic Disease↗
PubMed2001

Scavenger cells with gram-positive bacterial lipoteichoic acid infiltrate around the damaged interlobular bile ducts of primary biliary cirrhosis.

BACKGROUND/AIMS: Gram-positive bacterial DNA is frequently detectable in gallbladder bile of primary biliary cirrhosis (PBC) patients. To advance these findings, lipoteichoic acid (LTA) of gram-positive bacteria with high antigenicity was examined in liver specimens and bile from PBC patients and controls. METHODS: LTA was examined by Western blotting in the gallbladder bile from 15 PBC, 11 cholecystolithiasis and six normal subjects, and by immunohistochemistry in liver specimens from 16 PBC, six primary sclerosing cholangitis (PSC), eight chronic viral hepatitis C (CVH-C) and five normal subjects. RESULTS: In the gallbladder bile, there was no significant difference in the positive rate of LTA between PBC and controls. LTA-containing mononuclear cells were frequently detected in the portal tracts, particularly around the bile ducts and in hepatic sinusoids in PBC, while they were infrequent or occasional in control livers. These LTA-containing cells were sinusoidal endothelial cells and Kupffer cells, and portal monocytes, which frequently expressed scavenger receptor class B type 1. CONCLUSIONS: LTA derived from bacterial fragments may reach the bile, not only in the diseased state but also under normal conditions. Such LTA may be involved in the development and progression of portal tract lesions, particularly bile duct lesions, in PBC.

Adult↗
PubMed2001

A case of autoimmune hepatitis with a high titer of antimitochondrial antibody and normal gamma-globulinemia.

We report here a patient with chronic active hepatitis who had no markers for hepatitis viruses and no hyper-gamma-globulinemia, but had high titers of antimitochondrial antibody. Serum levels of alkaline phosphatase were normal, and antinuclear antibody, antismooth muscle antibody, and antiliver kidney microsome antibody tested negative. The titers of antimitochondrial antibody exceeded 1:640, and the positivity for anti-M2 was ascertained by using both ELISA and immunoblot with beef-heart mitochondria and a recombinant pyruvate dehydrogenase E2 subunit as antigens. This patient responded to ursodeoxycholic acid (UDCA) therapy in the beginning, but her hepatitis flared up during UDCA therapy. In contrast, she responded completely to corticosteroid therapy. The clinical course and histological findings of this patient strongly suggest that this patient has autoimmune hepatitis.

Aged↗
PubMed2001

The lymphoid liver: considerations on pathways to autoimmune injury.

Immunologic injury in the liver involves immigrant T and B lymphocytes and a resident lymphoid population that comprises distinct lymphocytic cells and accessory cells. The forerunner to autoimmunity is breaching of natural self-tolerance and hence the disruption of a fundamental property of the immune system. Such breaching occurs by processes that include inflammatory activation of immunocytes and macrophages, spillage of intracellular constituents, and epitope mimicry by constituents of microorganisms, with these acting on a genetically conditional phenotype; compounding factors include aberrations of apoptosis, whether insufficient or excess. The downstream end requires specifically directed inflammatory leukocyte traffic as an essential component of autoimmune expressions in the liver. The culmination is an orchestrated attack on hepatocytes or biliary epithelial cells by multiple effector pathways. Progress in type 1 autoimmune hepatitis still requires knowledge of a disease-specific autoantigen(s) involved in T-cell reactivity, although such knowledge in type 2 autoimmune hepatitis, in which the known autoantigen is cytochrome P4502D6, has not yet been integrated into a clearly defined scheme of pathogenesis. For PBC there has been a very promising amalgamation of molecular knowledge of the mitochondrial autoantigens. Future insights require deeper analysis of molecular, genetic, macroenvironmental, and microenvironmental elements in predisposition.

Animals↗
PubMed2001

Risk factors for primary biliary cirrhosis in a cohort of patients from the united states.

Although the etiology of primary biliary cirrhosis (PBC) remains unknown, environmental factors may act to trigger the disease in genetically susceptible hosts. To assess specific risk factors, we conducted a survey using standardized NHANES questions to 241 PBC patients in the United States, 261 of their siblings, and 141 friends without PBC. The overall response rate was 199 of 241 (83%) among PBC cases, 171 of 261 (67%) among siblings, and 141 of 225 (62. 7%) among friend controls. The female-to-male ratio among cases in this sample was approximately 10:1; the mean age was 53 years, and 97% were Caucasian. Other autoimmune diseases reported most frequently by PBC cases included Sjogren's syndrome (17.4%) and Raynaud's syndrome (12.5%). Approximately 6% of cases reported at least one family member with PBC. Adjusted odds ratios (OR) were elevated for cases compared with friends for other autoimmune diseases (OR = 4.92, 95% confidence interval [CI] = 2.38, 10.18), smoking (OR = 2.04, 95% CI = 1.10, 3.78), tonsillectomy (OR = 1.86, 95% CI = 1.02, 3.39), and vaginal or urinary tract infection (UTI) in females only (OR = 2.12, 95% CI = 1.10, 4.07). Similarly elevated ORs were observed for these risk factors when cases were compared with their siblings. The higher rate of UTI among cases is particularly interesting in light of previous data, and raises the possibility of an infectious etiology for PBC and of molecular mimicry as an etiologic mechanism. The significance of smoking in the multivariate models supports the findings of previous studies and raises the issue of the influence of smoking on a Th1 response.

Adult↗
PubMed2001

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.

Amino Acid Sequence↗
PubMed2001

Detection of antimitochondrial autoantibodies in immunofluorescent AMA-negative patients with primary biliary cirrhosis using recombinant autoantigens.

Antimitochondrial antibodies (AMA) are the serologic hallmark of primary biliary cirrhosis (PBC). However, depending on the clinical laboratory, from 5% to 17% of PBC patients are consistently AMA-negative, using native mitochondrial antigens and a variety of conventional assays including immunofluorescence (IMF) and enzyme-linked immunosorbent assay (ELISA). The major immunoreactive mitochondrial autoantigens are the E2 members of the 2-oxo-acid dehydrogenase complex family, including pyruvate dehydrogenase complex-E2 (PDC-E2), branched chain 2-oxo acid dehydrogenase complex-E2 (BCOADC-E2), and oxo-glutarate dehydrogenase complex-E2 (OGDC-E2); cDNAs of these proteins have now been cloned, sequenced, and their B-cell epitopes defined. In the present study, we cloned cDNAs encoding these proteins from human, not bovine, sources, and expressed the recombinant proteins in a newly developed ELISA that employs a unique Escherichia coli buffer, and compared the data with previous assays using both AMA-positive and -negative patients. Using this new assay and our criteria for positive as an optical density (OD) greater than 10 SD above the mean of control sera, the AMA-positive rate of 191 PBC sera was 94% (179 of 191) compared with 84% (161 of 191) by IMF. None of the 316 control sera were reactive. Using our recombinant assays, we focused attention on the 30 IMF-AMA-negative patients. Twenty-two of 30 (73%) of these patients were positive using this new ELISA. The group of 30 IMF-AMA-negative/ELISA-positive patients did not differ significantly from a comparable population of IMF-AMA-positive patients with respect to age, sex distribution, liver function tests, elevation of serum IgM, or pathologic stage.

Autoantibodies↗