Localization of Haemophilus ducreyi in naturally acquired chancroidal ulcers

Bauer, Margaret E.; Townsend, Carisa A.; Ronald, Allan; Spinola, Stanley M.

doi:10.1016/j.micinf.2006.06.001

Cited by 55 publications

(59 citation statements)

References 16 publications

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“…Experimental pustules and natural ulcers are identical histologically and represent immunological failure. In pustules and ulcers, H. ducreyi colocalizes with macrophages and neutrophils but resists phagocytosis and phagocytic killing and replicates extracellularly (6,7). H. ducreyi secretes two antiphagocytic proteins, LspA1 and LspA2, which inhibit Fc receptor-mediated uptake by macrophage-and neutrophil-like cell lines in vitro (50); a mutant lacking LspA1 and LspA2 expression is attenuated in human volunteers (20).…”

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confidence: 99%

Haemophilus ducreyi-Induced Interleukin-10 Promotes a Mixed M1 and M2 Activation Program in Human Macrophages

Katz

Spinola

2012

Infect Immun

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confidence: 99%

Haemophilus ducreyi-Induced Interleukin-10 Promotes a Mixed M1 and M2 Activation Program in Human Macrophages

Katz

Spinola

2012

Infect Immun

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“…Throughout experimental infection, H. ducreyi organisms are found in the abscess and associate with PMN and macrophages, both of which fail to ingest the organism (7). Similar relationships between H. ducreyi and host cells are maintained in natural ulcers (9). Thus, H. ducreyi must adapt to the hostile environment of an abscess to establish and maintain infection in the human host.…”

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Activation of the CpxRA System by Deletion of cpxA Impairs the Ability of Haemophilus ducreyi To Infect Humans

Fortney²,

et al. 2010

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Haemophilus ducreyi must adapt to the environment of the human host to establish and maintain infection in the skin. Bacteria generally utilize stress response systems, such as the CpxRA two-component system, to adapt to hostile environments. CpxRA is the only obvious two-component system contained in the H. ducreyi genome and negatively regulates the lspB-lspA2 operon, which encodes proteins that enable the organism to resist phagocytosis. We constructed an unmarked, in-frame H. ducreyi cpxA deletion mutant, 35000HP⌬cpxA. In human inoculation experiments, 35000HP⌬cpxA formed papules at a rate and size that were significantly less than its parent and was unable to form pustules compared to the parent. CpxA usually has kinase and phosphatase activities for CpxR, and the deletion of CpxA leads to the accumulation of activated CpxR due to the loss of phosphatase activity and the ability of CpxR to accept phosphate groups from other donors. Using a reporter construct, the lspB-lspA2 promoter was downregulated in 35000HP⌬cpxA, confirming that CpxR was activated. Deletion of cpxA downregulated DsrA, the major determinant of serum resistance in the organism, causing the mutant to become serum susceptible. Complementation in trans restored parental phenotypes. 35000HP⌬cpxA is the first H. ducreyi mutant that is impaired in its ability to form both papules and pustules in humans. Since a major function of CpxRA is to control the flow of protein traffic across the periplasm, uncontrolled activation of this system likely causes dysregulated expression of multiple virulence determinants and cripples the ability of the organism to adapt to the host.

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“…During human disease, H. ducreyi is surrounded by antimicrobial peptide (AP)-secreting cells, including neutrophils and macrophages (7,8,10). APs are small cationic peptides that aid in the killing of microorganisms through membrane disruption or effects on intracellular targets (14).…”

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Deletion of mtrC in Haemophilus ducreyi Increases Sensitivity to Human Antimicrobial Peptides and Activates the CpxRA Regulon

Rinker

Trombley

et al. 2011

Infect Immun

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Haemophilus ducreyi resists killing by antimicrobial peptides encountered during human infection, including cathelicidin LL-37, ␣-defensins, and ␤-defensins. In this study, we examined the role of the proton motive force-dependent multiple transferable resistance (MTR) transporter in antimicrobial peptide resistance in H. ducreyi. We found a proton motive force-dependent effect on H. ducreyi's resistance to LL-37 and ␤-defensin HBD-3, but not ␣-defensin HNP-2. Deletion of the membrane fusion protein MtrC rendered H. ducreyi more sensitive to LL-37 and human ␤-defensins but had relatively little effect on ␣-defensin resistance. The mtrC mutant 35000HPmtrC exhibited phenotypic changes in outer membrane protein profiles, colony morphology, and serum sensitivity, which were restored to wild type by trans-complementation with mtrC. Similar phenotypes were reported in a cpxA mutant; activation of the two-component CpxRA regulator was confirmed by showing transcriptional effects on CpxRA-regulated genes in 35000HPmtrC. A cpxR mutant had wild-type levels of antimicrobial peptide resistance; a cpxA mutation had little effect on defensin resistance but led to increased sensitivity to LL-37. 35000HPmtrC was more sensitive than the cpxA mutant to LL-37, indicating that MTR contributed to LL-37 resistance independent of the CpxRA regulon. The CpxRA regulon did not affect proton motive force-dependent antimicrobial peptide resistance; however, 35000HPmtrC had lost proton motive force-dependent peptide resistance, suggesting that the MTR transporter promotes proton motive forcedependent resistance to LL-37 and human ␤-defensins. This is the first report of a ␤-defensin resistance mechanism in H. ducreyi and shows that LL-37 resistance in H. ducreyi is multifactorial.

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Localization of Haemophilus ducreyi in naturally acquired chancroidal ulcers

Cited by 55 publications

References 16 publications

Haemophilus ducreyi-Induced Interleukin-10 Promotes a Mixed M1 and M2 Activation Program in Human Macrophages

Haemophilus ducreyi-Induced Interleukin-10 Promotes a Mixed M1 and M2 Activation Program in Human Macrophages

Activation of the CpxRA System by Deletion of cpxA Impairs the Ability of Haemophilus ducreyi To Infect Humans

Deletion of mtrC in Haemophilus ducreyi Increases Sensitivity to Human Antimicrobial Peptides and Activates the CpxRA Regulon

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