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  • American Society for Microbiology  (6)
  • 2005-2009  (6)
  • 1
    In: Infection and Immunity, American Society for Microbiology, Vol. 75, No. 12 ( 2007-12), p. 5686-5697
    Abstract: In experimentally infected human volunteers, the cutaneous immune response to Haemophilus ducreyi is orchestrated by serum, polymorphonuclear leukocytes, macrophages, T cells, and myeloid dendritic cells (DC). This response either leads to spontaneous resolution of infection or progresses to pustule formation, which is associated with the failure of phagocytes to ingest the organism and the presence of Th1 and regulatory T cells. In volunteers who are challenged twice, some subjects form at least one pustule twice (PP group), while others have all inoculated sites resolve twice (RR group). Here, we infected PP and RR subjects with H. ducreyi and used microarrays to profile gene expression in infected and wounded skin. The PP and RR groups shared a core response to H. ducreyi . Additional transcripts that signified effective immune function were differentially expressed in RR infected sites, while those that signified a hyperinflammatory, dysregulated response were differentially expressed in PP infected sites. To examine whether DC drove these responses, we profiled gene expression in H. ducreyi -infected and uninfected monocyte-derived DC. Both groups had a common response that was typical of a type 1 DC (DC1) response. RR DC exclusively expressed many additional transcripts indicative of DC1. PP DC exclusively expressed differentially regulated transcripts characteristic of DC1 and regulatory DC. The data suggest that DC from the PP and RR groups respond differentially to H. ducreyi. PP DC may promote a dysregulated T-cell response that contributes to phagocytic failure, while RR DC may promote a Th1 response that facilitates bacterial clearance.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1483247-1
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  • 2
    In: Infection and Immunity, American Society for Microbiology, Vol. 74, No. 5 ( 2006-05), p. 2651-2658
    Abstract: Haemophilus ducreyi , the etiologic agent of the sexually transmitted genital ulcer disease chancroid, has been shown to associate with dermal collagen fibers within infected skin lesions. Here we describe NcaA, a previously uncharacterized outer membrane protein that is important for H. ducreyi collagen binding and host colonization. An H. ducreyi strain lacking the ncaA gene was impaired in adherence to type I collagen but not fibronectin (plasma or cellular form) or heparin. The mutation had no effect on serum resistance or binding to HaCaT keratinocytes or human foreskin fibroblasts in vitro. Escherichia coli expressing H. ducreyi NcaA bound to type I collagen, demonstrating that NcaA is sufficient to confer collagen attachment. The importance of NcaA in H. ducreyi pathogenesis was assessed using both swine and human experimental models of chancroid. In the swine model, 20% of lesions from sites inoculated with the ncaA mutant were culture positive for H. ducreyi 7 days after inoculation, compared to 73% of wild-type-inoculated sites. The average number of CFU recovered from mutant-inoculated lesions was also significantly reduced compared to that recovered from wild-type-inoculated sites at both 2 and 7 days after inoculation. In the human challenge model, 8 of 30 sites inoculated with wild-type H. ducreyi progressed to the pustular stage, compared to 0 of 30 sites inoculated with the ncaA mutant. Together these results demonstrate that the collagen binding protein NcaA is required for H. ducreyi infection.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2006
    detail.hit.zdb_id: 1483247-1
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  • 3
    In: Infection and Immunity, American Society for Microbiology, Vol. 73, No. 7 ( 2005-07), p. 3896-3902
    Abstract: T-cell homing to infected skin is not well studied in humans. We examined sites experimentally infected with Haemophilus ducreyi by immunohistochemistry and flow cytometry for expression of receptors and ligands involved in cutaneous T-cell homing and determined the phenotypes of the T cells that trafficked to skin. Endothelial cells expressed E-selectin in infected but not uninfected skin, while peripheral node addressin (PNAd) was minimally expressed in all samples. CC chemokine ligand 27 (CCL27) was expressed in the epidermis and endothelium of both infected and uninfected skin. Interestingly, CCL21, a chemokine thought to be associated principally with T-cell trafficking in the lymphatic compartment, was highly expressed on the endothelium of infected skin. Few naive cells were present in experimental lesions, emphasizing the combined role of PNAd and CCL21 in trafficking of this subset. Memory cells (CD45RA − ) dominated both CD4 and CD8 T-cell populations at the site of infection. Effector memory (CD45RA − CD27 − ) CD4 + and CD8 + T cells were enriched in lesions. Although the CC chemokine receptor 7-positive (CCR7 + ) population of both central memory (CD45RA − CD27 + ) and effector memory cells was not enriched in the skin compared to peripheral blood, CCR7 + cells were not precluded from entering infected skin. Taken together with our previous work (D. Soler, T. L. Humphreys, S. M. Spinola, and J. J. Campbell, Blood 101:1677-1683, 2003), these studies led us to propose a model of memory T-cell trafficking to skin in response to experimental H. ducreyi infection.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2005
    detail.hit.zdb_id: 1483247-1
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  • 4
    Online Resource
    Online Resource
    American Society for Microbiology ; 2008
    In:  Infection and Immunity Vol. 76, No. 4 ( 2008-04), p. 1608-1616
    In: Infection and Immunity, American Society for Microbiology, Vol. 76, No. 4 ( 2008-04), p. 1608-1616
    Abstract: The ability to bind extracellular matrix proteins is a critical virulence determinant for skin pathogens. Haemophilus ducreyi , the etiological agent of the genital ulcer disease chancroid, binds extracellular matrix components, including fibronectin (FN). We investigated H. ducreyi FN binding and report several important findings about this interaction. First, FN binding by H. ducreyi was greatly increased in bacteria grown on heme and almost completely inhibited by hemoglobin. Second, wild-type strain 35000HP bound significantly more FN than did a dsrA mutant in two different FN binding assays. Third, the expression of dsrA in the dsrA mutant restored FN binding and conferred the ability to bind FN to a non-FN-binding Haemophilus influenzae strain. Fourth, an anti-DsrA monoclonal antibody partially blocked FN binding by H. ducreyi . The hemoglobin receptor, the collagen-binding protein, the H. ducreyi lectin, the fine-tangle pili, and the outer membrane protein OmpA2 were not involved in H. ducreyi FN binding, since single mutants bound FN as well as the parent strain did. However, the major outer membrane protein may have a minor role in FN binding by H. ducreyi , since a double dsrA momp mutant bound less FN than did the single dsrA mutant. Finally, despite major sequence differences, DsrA proteins from both class I and class II H. ducreyi strains mediated FN and vitronectin binding. We concluded that DsrA is the major factor involved in FN binding by both classes of H. ducreyi strains.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2008
    detail.hit.zdb_id: 1483247-1
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  • 5
    Online Resource
    Online Resource
    American Society for Microbiology ; 2007
    In:  Infection and Immunity Vol. 75, No. 12 ( 2007-12), p. 5678-5685
    In: Infection and Immunity, American Society for Microbiology, Vol. 75, No. 12 ( 2007-12), p. 5678-5685
    Abstract: Dendritic cells (DC) orchestrate innate and adaptive immune responses to bacteria. How Haemophilus ducreyi , which causes genital ulcers and regional lymphadenitis, interacts with DC is unknown. H. ducreyi evades uptake by polymorphonuclear leukocyte and macrophage-like cell lines by secreting LspA1 and LspA2. Many H. ducreyi strains express cytolethal distending toxin (CDT), and recombinant CDT causes apoptosis of DC in vitro. Here, we examined interactions between DC and H. ducreyi 35000HP, which produces LspA1, LspA2, and CDT. In human volunteers infected with 35000HP, the ratio of myeloid DC to plasmacytoid DC was 2.8:1 in lesions, compared to a ratio of 1:1 in peripheral blood. Using myeloid DC derived from monocytes as surrogates for lesional DC, we found that DC infected with 35000HP remained as viable as uninfected DC for up to 48 h. Gentamicin protection and confocal microscopy assays demonstrated that DC ingested and killed 35000HP, but killing was incomplete at 48 h. The expression of LspA1 and LspA2 did not inhibit the uptake of H. ducreyi , despite inactivating Src kinases. Infection of DC with live 35000HP caused less cell surface marker activation than infection with heat-killed 35000HP and lipopolysaccharide (LPS) and inhibited maturation by LPS. However, infection of DC with live bacteria caused the secretion of significantly higher levels of interleukin-6 and tumor necrosis factor alpha than infection with heat-killed bacteria and LPS. The survival of H. ducreyi in DC may provide a mechanism by which the organism traffics to lymph nodes. Partial activation of DC may abrogate the establishment of a full Th1 response and an environment that promotes phagocytosis.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1483247-1
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  • 6
    Online Resource
    Online Resource
    American Society for Microbiology ; 2006
    In:  Infection and Immunity Vol. 74, No. 2 ( 2006-02), p. 1394-1397
    In: Infection and Immunity, American Society for Microbiology, Vol. 74, No. 2 ( 2006-02), p. 1394-1397
    Abstract: Haemophilus ducreyi produces two outer membrane proteins, called DltA ( H. ducreyi lectin A) and DsrA ( H. ducreyi serum resistance A), that contribute to the ability of the organism to evade complement-mediated serum killing. In contrast to their isogenic parent strain, 35000HP, the DsrA mutant FX517 exhibits 0% survival in 50% normal human serum and the DltA mutant FX533 exhibits 23% survival. Compared to 35000HP, FX517 does not cause pustule formation in human volunteers. To test whether DltA was required for virulence in humans, seven volunteers were experimentally infected with 35000HP and FX533. Four subjects were inoculated with fixed doses of 35000HP (101 CFU or 130 CFU) at three sites on one arm and escalating doses of FX533 (range, 46 CFU to 915 CFU) at three sites on the other arm. Pustules only developed at mutant-injected sites at doses nearly twofold higher than that of the parent, suggesting that FX533 was partially attenuated. Three subjects were inoculated with similar doses of the parent (67 CFU) and mutant (104 CFU) at three sites. Pustules formed at five of nine parent sites and one of nine mutant sites. Overall, the papule and pustule formation rates for 35000HP and FX533 were similar for the trial. However, for the five subjects who received similar doses of the parent and mutant, pustules developed at 7 of 15 sites (46.7%; 95% confidence interval [CI], 16.9% to 76.5%) inoculated with the parent and at 1 of 15 (6.7%; 95% CI, 0.1% to 18.4%) sites inoculated with the mutant ( P = 0.043). We concluded that the DltA mutant was attenuated in its ability to cause disease at doses similar to that of the parent.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2006
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
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