PKSP-dependent reduction of phagolysosome fusion and intracellular kill of<i>Aspergillus fumigatus</i>conidia by human monocyte-derived macrophages

Jahn, Bernhard; Langfelder, Kim; Schneider, Ulrike; Schindel, Christine; Brakhage, Axel A.

doi:10.1046/j.1462-5822.2002.00228.x

Cited by 120 publications

(111 citation statements)

References 38 publications

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“…The presence of melanin in A. fumigatus and other fungi is considered to be important for viru-lence because it affects the immune response to fungal infection (38). We observe some dephasing in the aromatic carbon region in the 13 C{ 15 N}REDOR experiments that is consistent with melanin (example structure in Table 1) (39,40), but due to the overlap of 15 N chemical shifts of amides and indoles (near 120 ppm) in the 15 N spectrum, it is not possible to unambiguously identify whether the indole nitrogens are specifically attributed to melanin.…”

Section: Discussionmentioning

confidence: 99%

Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy

et al. 2015

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dAspergillus fumigatus is commonly responsible for lethal fungal infections among immunosuppressed individuals. A. fumigatus forms biofilm communities that are of increasing biomedical interest due to the association of biofilms with chronic infections and their increased resistance to antifungal agents and host immune factors. Understanding the composition of microbial biofilms and the extracellular matrix is important to understanding function and, ultimately, to developing strategies to inhibit biofilm formation. We implemented a solid-state nuclear magnetic resonance (NMR) approach to define compositional parameters of the A. fumigatus extracellular matrix (ECM) when biofilms are formed in RPMI 1640 nutrient medium. Whole biofilm and isolated matrix networks were also characterized by electron microscopy, and matrix proteins were identified through protein gel analysis. The 13 C NMR results defined and quantified the carbon contributions in the insoluble ECM, including carbonyls, aromatic carbons, polysaccharide carbons (anomeric and nonanomerics), aliphatics, etc. Additional 15 N and 31 P NMR spectra permitted more specific annotation of the carbon pools according to C-N and C-P couplings. Together these data show that the A. fumigatus ECM produced under these growth conditions contains approximately 40% protein, 43% polysaccharide, 3% aromatic-containing components, and up to 14% lipid. These fundamental chemical parameters are needed to consider the relationships between composition and function in the A. fumigatus ECM and will enable future comparisons with other organisms and with A. fumigatus grown under alternate conditions. A spergillus fumigatus is the most important etiological agent of human aspergillosis and is recognized as a highly allergenic and opportunistic pathogen, causing acute and chronic infections particularly among immunocompromised individuals (1). Hospital-associated outbreaks of A. fumigatus may occur during periods of construction or renovation (2) or when fungi colonize water distribution systems that then lead to spore aerosolization in patient care areas and patient exposure (1). Additionally, A. fumigatus can cause infections as a result of colonizing medical implant devices, including cardiac pacemakers, joint replacements, and breast implants (3). Despite improvements in diagnostics and the antifungal armamentarium, including broad-spectrum azoles and the echinocandin antifungals, mortality due to A. fumigatus invasive infections remains high.Like many microorganisms, A. fumigatus can also assemble into multicellular communities, termed biofilms, composed of cells plus an extracellular matrix (ECM) (4-9). Although more work is needed to fully understand the functional implications of biofilm formation by A. fumigatus, recent evidence suggests that the ECM may provide the infrastructure for enhancing cell density, controlling disaggregation, and altering nutritional needs, as well as providing a protective physical and chemical barrier that can decrease sensitivity to competi...

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Section: Discussionmentioning

confidence: 99%

Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy

et al. 2015

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“…Recently, we showed that a functional pksP gene is associated with a reduction in phagolysosome fusion in human monocyte-derived macrophages (MDMs). Consistently, the intracellular killing of pksP mutant conidia by MDMs was significantly greater than the intracellular killing of wild-type conidia (25). By using the enhanced green fluorescent protein, it was shown that the pksP gene was expressed during sporulation.…”

mentioning

confidence: 86%

“…Recently, the group of J. Kwon-Chung and our group identified a gene that encodes a pathogenicity determinant. This gene was designated pksP (or alternatively alb1) for polyketide synthase involved in pigment biosynthesis (23,24,25,28,54). Conidia of a pksP mutant strain are white.…”

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confidence: 99%

The Cyclic AMP-Dependent Protein Kinase A Network Regulates Development and Virulence in Aspergillus fumigatus

et al. 2004

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Aspergillus fumigatus is an important pathogen of immunocompromised hosts, causing pneumonia and invasive disseminated disease with high mortality. To determine the importance of the cyclic AMP (cAMP) signaling pathway for virulence, the pkaC1 gene encoding a protein kinase A (PKA) catalytic subunit was cloned and characterized. Deletion of pkaC1 led to reduced conidiation and growth. PKA activity was not detectable in ⌬pkaC1, ⌬gpaB, and ⌬acyA mutant strains. gpaB and acyA encode a G protein ␣ subunit involved in cAMP signal transduction and adenylate cyclase, respectively. Addition of cAMP led to PKA activity in crude extracts of both the ⌬gpaB and ⌬acyA strains but not in crude extracts of the ⌬pkaC1 strain. These findings provide evidence that PKAC1 represents the predominant form of PKA under the conditions tested, and GPAB and ACYA are members of the cAMP signaling cascade. Analysis of a pksPp-lacZ gene fusion indicated that the expression of the pathogenicity determinant-encoding pksP gene was reduced in ⌬pkaC1 mutant strains compared with the expression of the gene fusion in the parental strain. In a low-dose murine inhalation model, conidia of both the ⌬pkaC1 and ⌬gpaB mutant strains were almost avirulent. Taken together, these findings indicate that the cAMP-PKA signal transduction pathway is required for A. fumigatus pathogenicity.Aspergillus fumigatus has become the most important airborne fungal pathogen of humans. Alveolar macrophages form the first line of defense against fungal conidia, the infectious agents, entering the respiratory tract. Neutrophilic granulocytes, the second line of defense, primarily attack hyphae but also attack conidia. An important killing mechanism for both types of immune effector cells consists of the production of reactive oxygen species (ROS) (22,31,42). Improvement in transplant medicine and the therapy of hematological malignancies is often complicated by the threat of invasive aspergillosis. A. fumigatus accounts for approximately 90% of invasive aspergillosis cases. Specific diagnostics are still limited, as are the possibilities of therapeutic intervention, which leads to a high mortality rate (30 to 98%) for invasive aspergillosis (reviewed in references 9 and 31).One of the important questions concerning A. fumigatus is the identification of pathogenicity determinants and their regulation. Recently, the group of J. Kwon-Chung and our group identified a gene that encodes a pathogenicity determinant. This gene was designated pksP (or alternatively alb1) for polyketide synthase involved in pigment biosynthesis (23,24,25,28,54). Conidia of a pksP mutant strain are white. Based on genetic and biochemical data, the conidial pigment consists of dihydroxynaphthalene (DHN)-melanin (7,30,52,53). pksP mutant strains exhibited reduced virulence in a mouse infection model (23,54). pksP mutant conidia were 20-fold more sensitive to ROS than wild-type conidia, suggesting that the pigment is able to scavenge ROS, thereby presumably detoxifying ROS (23,24). Moreover, a key eleme...

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“…neoformans secrete proteins and polysaccharides that lead to the formation of abnormal phagosomes (65)(66)(67). A. fumigatus possesses a surface-bound structure (1,8-dihydroxynaphthalene-like melanin) that has been proposed to inhibit lysosomal fusion in human MDMs (68). Bacterial processes that lead to disruptions of phagosome maturation have been studied in greater detail and might provide hints about the nature of the UV light-indestructible factor of C. glabrata.…”

Section: Glabrata Blocks Phagolysosome Formation and Phagosome Acimentioning

confidence: 99%

The Facultative Intracellular Pathogen Candida glabrata Subverts Macrophage Cytokine Production and Phagolysosome Maturation

Seider

Brunke

Schild

et al. 2011

The Journal of Immunology

184

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Although Candida glabrata is an important human pathogenic yeast, its pathogenicity mechanisms are largely unknown. Immune evasion strategies seem to play key roles during infection, since very little inflammation is observed in mouse models. Furthermore, C. glabrata multiplies intracellularly after engulfment by macrophages. In this study, we sought to identify the strategies that enable C. glabrata to survive phagosome biogenesis and antimicrobial activities within human monocyte-derived macrophages. We show that, despite significant intracellular proliferation, macrophage damage or apoptosis was not apparent, and production of reactive oxygen species was inhibited. Additionally, with the exception of GM-CSF, levels of pro- and anti-inflammatory cytokines were only marginally increased. We demonstrate that adhesion to and internalization by macrophages occur within minutes, and recruitment of endosomal early endosomal Ag 1 and lysosomal-associated membrane protein 1 indicates phagosome maturation. However, phagosomes containing viable C. glabrata, but not heat-killed yeasts, failed to recruit cathepsin D and were only weakly acidified. This inhibition of acidification did not require fungal viability, but it had a heat-sensitive surface attribute. Therefore, C. glabrata modifies the phagosome into a nonacidified environment and multiplies until the host cells finally lyse and release the fungi. Our results suggest persistence of C. glabrata within macrophages as a possible immune evasion strategy.

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PKSP-dependent reduction of phagolysosome fusion and intracellular kill ofAspergillus fumigatusconidia by human monocyte-derived macrophages

Cited by 120 publications

References 38 publications

Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy

Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy

The Cyclic AMP-Dependent Protein Kinase A Network Regulates Development and Virulence in Aspergillus fumigatus

The Facultative Intracellular Pathogen Candida glabrata Subverts Macrophage Cytokine Production and Phagolysosome Maturation

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