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  • 1
    Online Resource
    Online Resource
    American Society for Microbiology ; 1997
    In:  Infection and Immunity Vol. 65, No. 6 ( 1997-06), p. 2094-2099
    In: Infection and Immunity, American Society for Microbiology, Vol. 65, No. 6 ( 1997-06), p. 2094-2099
    Abstract: The virulence mechanism of Neisseria gonorrhoeae in pelvic inflammatory disease (PID) is not well understood, and an objective diagnostic method to identify patients with PID is lacking. We investigated the hypothesis that development of PID was associated with a C1q-dependent virulence property of gonococcal strains. Recent development of a C1q-dependent experimental model of gonococcal infection (S. Nowicki, M. Martens, and B. Nowicki, Infect. Immun. 63:4790-4794, 1995) created an opportunity to evaluate this hypothesis in vivo. Therefore, the virulence of 32 clinical isolates (18 PID isolates and 14 local infection [LI] isolates) was evaluated in experimental rat pups. A serum bactericidal assay was used to characterize a gonococcal serum-resistant (ser(r)) phenotype. PCR primers designed to amplify a suitable-size gonococcal sac-4 DNA fragment (unique for serum-resistant donor JC1) were used to evaluate the association of serum-resistant genotype sac-4 with two phenotypes: C1q-dependent virulence expressed in vivo and resistance to bactericidal activity of human serum expressed in vitro. Strains were also characterized by auxotyping and serotyping. Of 32 gonococcal strains, 15 (46.7%) caused C1q-dependent bacteremia in rat pups and were sac-4 positive and ser(r). However, of the 15 isolates, 13 (87%) represented strains associated with human PID and 2 (13%) were associated with LI. None of the strains that were completely serum-sensitive (ser(s)) and sac-4 negative produced C1q-dependent bacteremia in rat pups, suggesting that both ser(r) and sac-4 were required for infection. The serum-resistant recombinant recipient of sac-4 produced C1q-dependent bacteremia in the rat model similarly to the serum-resistant donor of sac-4; the serum-sensitive parent strain did not produce bacteremia. These data suggest that sac-4-mediated serum resistance conferred C1q-dependent virulence and is a unique characteristic associated with PID. These newly identified features may contribute to the understanding of the pathogenic mechanism of PID-associated strains and open perspectives for establishing novel diagnostic methods.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
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    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1997
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  • 2
    Online Resource
    Online Resource
    American Society for Microbiology ; 2000
    In:  Infection and Immunity Vol. 68, No. 3 ( 2000-03), p. 1391-1399
    In: Infection and Immunity, American Society for Microbiology, Vol. 68, No. 3 ( 2000-03), p. 1391-1399
    Abstract: Dr-fimbriated Escherichia coli capable of invading epithelial cells recognizes human decay-accelerating factor (DAF) as its cellular receptor. The role of extracellular domains and the glycosylphosphatidylinositol anchor of DAF in the process of internalization of Dr + E. coli was characterized in a cell-cell interaction model. Binding of Dr + E. coli to the short consensus repeat 3 domain of DAF expressed by Chinese hamster ovary cells was critical for internalization to occur. Deletion of short consensus repeat 3 domain or replacement of Ser 165 by Leu in this domain, or the use of a monoclonal antibody to this region abolished internalization. Replacing the glycosylphosphatidylinositol anchor of DAF with the transmembrane anchor of membrane cofactor protein or HLA-B44 resulted in abolition or reduction of internalization respectively. Cells expressing glycosylphosphatidylinositol-anchored DAF but not the transmembrane-anchored DAF internalized Dr + E. coli through a glycolipid pathway, since the former cells were more sensitive to inhibition by methyl-β-cyclodextrin, a sterol-chelating agent. Electron microscopic studies revealed that the intracellular vacuoles containing the internalized Dr + E. coli were morphologically distinct between the anchor variants of DAF. The cells expressing glycosylphosphatidylinositol-anchored DAF contained a single bacterium in tight-fitting vacuoles, while the cells expressing transmembrane-anchored DAF contained multiple (two or three) bacteria in spacious phagosomes. This finding suggests that distinct postendocytic events operate in the cells expressing anchor variants of DAF. We provide direct evidence for the DAF-mediated internalization of Dr + E. coli and demonstrate the significance of the glycosylphosphatidylinositol anchor, which determines the ability and efficiency of the internalization event.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2000
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  • 3
    In: Journal of Clinical Investigation, American Society for Clinical Investigation, Vol. 99, No. 7 ( 1997-4-1), p. 1662-1672
    Type of Medium: Online Resource
    ISSN: 0021-9738
    Language: English
    Publisher: American Society for Clinical Investigation
    Publication Date: 1997
    detail.hit.zdb_id: 2018375-6
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  • 4
    In: Infection and Immunity, American Society for Microbiology, Vol. 73, No. 11 ( 2005-11), p. 7597-7601
    Abstract: Escherichia coli bearing adhesins of the Dr/Afa family frequently causes urogenital infections during pregnancy in humans and has been associated with mortality in pregnant rats. Two components of the adhesin, Dra/AfaE and Dra/AfaD, considered virulence factors, are responsible for bacterial binding and internalization. We hypothesize that gestational mortality caused by Dr/Afa + E. coli is mediated by one of these two proteins, Dra/AfaE or Dra/AfaD. In this study, using afaE and/or afaD mutants, we investigated the role of the afaE and afaD genes in the mortality of pregnant rats from intrauterine infection. Sprague-Dawley rats, on the 17th day of pregnancy, were infected with the E. coli afaE + afaD and afaE afaD + mutants. The clinical E. coli strain ( afaE + afaD + ) and the afaE afaD double mutant were used as positive and negative controls, respectively. The mortality rate was evaluated 24 h after infection. The highest maternal mortality was observed in the group infected with the afaE + afaD + strain, followed by the group infected with the afaE + afaD strain. The mortality was dose dependent. The afaE afaD double mutant did not cause maternal mortality, even with the highest infection dose. The in vivo studies corresponded with the invasion assay, where the afaE + strains were the most invasive ( afaE + afaD strain 〉 afaE + afaD + strain), while the afaE mutant strains ( afaE afaD + and afaE afaD strains) seemed to be noninvasive. This study shows for the first time that the afaE gene coding for the AfaE subunit of Dr/Afa adhesin is involved in the lethal outcome of gestational infection in rats. This lethal effect associated with AfaE correlates with the invasiveness of afaE + E. coli strains in vitro.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
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    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2005
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  • 5
    In: Infection and Immunity, American Society for Microbiology, Vol. 67, No. 8 ( 1999-08), p. 3989-3997
    Abstract: Escherichia coli strains expressing Dr fimbriae are able to enter epithelial cells by interacting with a complement-regulatory protein, decay-accelerating factor. This model of bacterial internalization, with a well-characterized bacterial ligand and host receptor, provides a unique opportunity to investigate the early stages of invasion. We used immunofluorescence staining techniques to examine the distribution of receptor and cytoskeletal proteins in HeLa cells infected with E. coli recombinant strains that expressed Dr family of adhesins: Dr, Dr-II, F1845, AFA-I, and AFA-III. A major rearrangement of decay-accelerating factor was found at the adherence sites of recombinant strains expressing Dr, Dr-II, and F1845 adhesins. The changes in the distribution of receptor were significantly smaller on HeLa cells infected with E. coli bearing AFA-I or AFA-III afimbrial adhesins. Receptor aggregation was associated with the redistribution of cytoskeleton-associated proteins such as actin, α-actinin, ezrin, and occasionally tropomyosin. Purified Dr fimbriae coated on polystyrene beads were capable of triggering clustering of receptor and accumulating actin at the adhesion sites of beads to HeLa cells. Using scanning and transmission electron microscopic techniques, we have shown that beads coated with Dr fimbriae, as opposed to beads coated with bovine serum albumin, were enwrapped by cellular microvilli and ultimately internalized into HeLa cells. This indicates that interaction of Dr fimbriae with decay-accelerating factor is associated with redistribution of receptor and is sufficient to promote bacterial internalization.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
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  • 6
    Online Resource
    Online Resource
    American Society for Microbiology ; 1996
    In:  Infection and Immunity Vol. 64, No. 2 ( 1996-02), p. 611-615
    In: Infection and Immunity, American Society for Microbiology, Vol. 64, No. 2 ( 1996-02), p. 611-615
    Abstract: The mechanisms of developing infection in young, noncompromised individuals are well understood. Colonization is prerequisite for the development of infection. In human, ligands serving bacterial colonization belong to common antigens. Consequently, a majority of individuals should be sensitive to infection at all times. We hypothesize that the temporal patterns of some infections and sensitivity to them are associated with sudden changes in the density and accessibility of common receptors. Endometrial samples from women having normal menstrual cycles were examined for histological location, receptor density, and in situ hybridization of Dr (decaying-accelerating factor) ligands for Escherichia coli Dr fimbriae. Significant up-regulation and luminal expression of Dr ligands occurred during the secretory phase, whereas receptors were expressed in the basement membrane and in smaller quantities during the proliferative phase. This observation agrees with our hypotheses that some ligands recognized by bacterial adhesins change their compartmentalization and, most importantly, that they up-regulate expression at specific times.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1996
    detail.hit.zdb_id: 1483247-1
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  • 7
    Online Resource
    Online Resource
    The American Association of Immunologists ; 1997
    In:  The Journal of Immunology Vol. 159, No. 6 ( 1997-09-15), p. 3016-3023
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 159, No. 6 ( 1997-09-15), p. 3016-3023
    Abstract: Myasthenia gravis (MG) is a T cell-dependent, Ab-mediated autoimmune disease. T cells reactive to a dominant peptide alpha 146-162 of acetylcholine receptor (AChR) alpha subunit participate in murine MG pathogenesis. To suppress the autoimmune response to AChR, a high dose of alpha146-162 peptide in IFA was administered parenterally as a tolerogen, after the development of a primary T cell immune response to AChR. This form of AChR T cell peptide tolerance suppressed the in vitro T cell proliferative response to AChR and its dominant alpha146-162 and subdominant alpha182-198 peptides through epitope spread. Administration of alpha146-162 peptide in IFA after the primary immune response to AChR also significantly suppressed the serum anti-AChR Ab of the IgG2b isotype and clinical incidence of MG in C57BL/6 mice. Furthermore, the production of IFN-gamma, IL-2, and IL-10 cytokines by AChR, alpha146-162, and alpha182-198 peptide-reactive cells was suppressed by alpha146-162 peptide tolerance, and the epitope spread observed could be attributed to the reduction in the above cytokine production. Therefore, AChR T cell-dominant peptide tolerance could be adapted in the Ag-specific therapy of MG.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1997
    detail.hit.zdb_id: 1475085-5
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  • 8
    Online Resource
    Online Resource
    The American Association of Immunologists ; 1995
    In:  The Journal of Immunology Vol. 154, No. 11 ( 1995-06-01), p. 6203-6208
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 154, No. 11 ( 1995-06-01), p. 6203-6208
    Abstract: Myasthenia gravis (MG) is an Ab-mediated autoimmune neuromuscular disease and is linked to MHC class II beta-chain polymorphism. Corticosteroids and azathioprine are the primary immunosuppressive drugs used in the treatment of MG. These drugs have significant side effects and have limited efficacy. Therefore, drugs with fewer side effects and greater efficacy are being sought. IFN-alpha is a potent immunomodulator and has been shown to down-regulate MHC class II expression on lymphoid cells. MHC class II expression is critical for the development of experimental autoimmune myasthenia gravis (EAMG). Because of the immunomodulating effects of IFN-alpha and its effect on the MHC class II expression, we tested the therapeutic efficacy of IFN-alpha on EAMG induced by immunization with acetylcholine receptor (AChR) in CFA. IFN-alpha (10(5) IU three times weekly for 5 wk) treatment started 1 wk after the second immunization with AChR in CFA, when autoimmunity to AChR is well established, reduced the incidence of clinical EAMG by more than 50% in two separate experiments (p = 0.04 and 0.008). Therefore, IFN-alpha could be a potential agent for the control of MG, and other Ab-mediated autoimmune diseases.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    RVK:
    RVK:
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1995
    detail.hit.zdb_id: 1475085-5
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  • 9
    Online Resource
    Online Resource
    The American Association of Immunologists ; 1994
    In:  The Journal of Immunology Vol. 152, No. 6 ( 1994-03-15), p. 3152-3157
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 152, No. 6 ( 1994-03-15), p. 3152-3157
    Abstract: To analyze the impact of lack of MHC class II gene expression, and to demonstrate the direct genetic evidence for the involvement of the MHC class II gene product in the development of experimental autoimmune myasthenia gravis (EAMG), MHC class II gene-disrupted C57BL6 mutant (-/-) and EAMG-susceptible MHC class II wild-type C57BL6 mice (+/+) were evaluated for the clinical and immunopathologic manifestations of EAMG. The deficiency of MHC class II, and therefore, CD4+ T cells, completely prevented the C57BL6 MHC class II mutant (-/-) mice from mounting an autoimmune response to the nicotinic acetylcholine receptor. Further, the mutant (-/-) mice failed to show any immunopathologic and clinical manifestations of EAMG. The data unequivocally provide direct genetic evidence for the essential role of MHC class II molecules in the induction of EAMG, and rule out any pathogenic effector role for MHC class I-restricted CD8+ T cells, gamma delta TCR-bearing cells, or NK cells, which are intact in the MHC class II mutant mice in the induction of EAMG.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    RVK:
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1994
    detail.hit.zdb_id: 1475085-5
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  • 10
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 158, No. 12 ( 1997-06-15), p. 6006-6012
    Abstract: Multiple TCRBV genes have been implicated in experimental autoimmune myasthenia gravis (EAMG) pathogenesis in susceptible H-2(b) strains of mice. We studied the contribution of specific TCRBV and AV genes in EAMG pathogenesis using B10.BV8S2 transgenic mice (H-2[b]). The TCR transgenic mice predominantly have TCRBV8S2 transgene, but can use any of the endogenous AV gene repertoire. The transgenic mice were immunized with acetylcholine receptor (AChR) in CFA and evaluated for EAMG pathogenesis. Although the lymphocyte responses to AChR in B10.BV8S2 transgenic and nontransgenic TCR wild-type mice were equivalent, a marked reduction in lymphocyte response to the dominant AChR alpha chain peptide 146-162 was observed in the TCR transgenic mice. After boosting with AChR in CFA, anti-AChR Abs were detected in the serum, and 14 of 42 (33%) of the TCR transgenic mice developed clinical EAMG. Furthermore, EAMG in TCR transgenic mice was prevented by treatment with mAb to TCRBV8, which depleted BV8-expressing T cells. Cloning and sequencing of TCRAV genes from AChR-reactive T cells from B10.BV8S2 transgenic mice revealed a pattern of restricted TCRAV gene usage. The majority (60%) of the clones sequenced showed a sequence identical with that of the TCRAV1S8 gene. In the normal spleen cells of TCR transgenic mice, AV gene usage was more random. Thus, despite the presence of a complete endogenous TCRAV repertoire in B10.BV8S2 transgenic mice, T cells responding to AChR preferentially used a single endogenous TCRAV gene, thus implicating the involvement of the TCRAV1S8 gene in EAMG pathogenesis.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    RVK:
    RVK:
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1997
    detail.hit.zdb_id: 1475085-5
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