Interactions of Candida albicans Yeast Cells, Germ Tubes and Hyphae with Human Polymorphonuclear Leucocytes in vitro

Despite an abundance of data describing expression of genes in the Candida albicans ALS (agglutinin-like sequence) gene family, little is known about the production of Als proteins on individual cells, their spatial localization or stability. Als proteins are most commonly discussed with respect to function in adhesion of C. albicans to host and abiotic surfaces. Development of a mAb specific for Als1, one of the eight large glycoproteins encoded by the ALS family, provided the opportunity to detect Als1 during growth of yeast and hyphae, both in vitro and in vivo, and to demonstrate the utility of the mAb in blocking C. albicans adhesion to host cells. Although most C. albicans yeast cells in a saturated culture are Als1-negative by indirect immunofluorescence, Als1 is detected on the surface of nearly all cells shortly after transfer into fresh growth medium. Als1 covers the yeast cell surface, with the exception of bud scars. Daughters of the inoculum cells, and sometimes granddaughters, also have detectable Als1, but Als1 is not detectable on cells from subsequent generations. On germ tubes and hyphae, most Als1 is localized proximal to the mother yeast. Once deposited on yeasts or hyphae, Als1 persists long after the culture has reached saturation. Growth stage-dependent production of Als1, coupled with its persistence on the cell surface, results in a heterogeneous population of cells within a C. albicans culture. Anti-Als1 immunolabelling patterns vary depending on the source of the C. albicans cells, with obvious differences between cells recovered from culture and those from a murine model of disseminated candidiasis. Results from this work highlight the temporal parallels for ALS1 expression and Als1 production in yeasts and germ tubes, the specialized spatial localization and persistence of Als1 on the C. albicans cell surface, and the differences in Als1 localization that occur in vitro and in vivo.

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The ultrastructure of Candida albicans infections

Canadian Journal of Microbiology ◽

10.1139/m81-181 ◽

1981 ◽

Vol 27 (11) ◽

pp. 1156-1164 ◽

Cited By ~ 36

Author(s):

Thomas J. Marrie ◽

J. William Costerton

Keyword(s):

Candida Albicans ◽

Oral Candidiasis ◽

Ruthenium Red ◽

Host Cells ◽

Yeast Cells ◽

Positive Matrix ◽

Urine Sediment ◽

Bacteria Adhesion

Scrapings of Candida albicans plaques from the tongue and buccal mucosa of patients with oral candidiasis were examined electron microscopy. In addition, urine sediment from patients with infection of their catheterized urinary tracts was similar examined. Three types of C. albicans – oral epithelial cell interactions were noted: a loose adherence apparently mediated by ruthenium red positive matrix, a "tight" adherence where no space could be seen between the host and yeast cell, and invasions host cells by yeast hyphal elements. Adhesion of Candida blastospores to hyphal elements and adhesion of bacteria to Candida cells was also frequently observed.Urine sediments from patients with mixed bacteria–yeast infections demonstrated adhesion of the bacteria to the yeast cells. This phenomenon was also demonstrated in in vitro experiments and fibrous ruthenium red material invariably occupied the zo*** of adhesion.Phagocytosis of yeast by polymorphonuclear leukocytes was found in urinary, but not in oral, candidiasis. Our in vivo and vitro observations indicate that a ruthenium red positive matrix covers the surfaces involved in the yeast to yeast, yeast to ho and yeast to bacteria adhesion.

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The “Finger,” a Unique Multicellular Morphology of Candida albicans Induced by CO2and Dependent upon the Ras1-Cyclic AMP Pathway

Eukaryotic Cell ◽

10.1128/ec.00217-12 ◽

2012 ◽

Vol 11 (10) ◽

pp. 1257-1267 ◽

Cited By ~ 7

Author(s):

Karla J. Daniels ◽

Claude Pujol ◽

Thyagarajan Srikantha ◽

David R. Soll

Keyword(s):

Candida Albicans ◽

Cyclic Amp ◽

Mutational Analysis ◽

Cell Monolayer ◽

Yeast Cells ◽

Content Type ◽

Dispersal Mechanism ◽

Basal Bulb ◽

High Doses

ABSTRACTMost experiments exploring the basic biology of pathogenic microbes are performedin vitrounder conditions that do not usually mimic those of their host niche. Hence, developmental programs initiated by specific host cues may be missedin vitro. We have tested the effects of growing low-density agar cultures of the yeast pathogenCandida albicansin concentrations of CO2found in the gastrointestinal tract. It is demonstrated that in physiological concentrations of CO2at 37°C, yeast cells form a heretofore undescribed multicellular “finger” morphology distinct from a previously described stalk-like structure induced by high doses of UV irradiation that kills more than 99.99% of cells. The finger extends aerially, is uniform in diameter, and is visible to the naked eye, attaining lengths of 3 mm. It is composed of a basal yeast cell monolayer adhering to a semispherical crater formed in the agar and connected to a basal bulb of yeast cells at a fragile interface. The bulb extends into the long shaft. We propose that a single, centrally located hypha extending the length of the shaft forms buds at compartment junctions that serve as the source of the yeast cells in the shaft. A mutational analysis reveals finger formation is dependent upon the pathway Ras1→Cdc35→cyclic AMP (cAMP) (PDE2—|)→Tpk2→Tec1. Because of the mechanically fragile interface and the compactness of bulb and shaft, we suggest that the finger may function as a multicellular dispersal mechanism produced in host niches containing high levels of CO2.

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Anti-Candidal Activity and In Vitro Cytotoxicity Assessment of Graphene Nanoplatelets Decorated with Zinc Oxide Nanorods

Nanomaterials ◽

10.3390/nano8100752 ◽

2018 ◽

Vol 8 (10) ◽

pp. 752 ◽

Cited By ~ 8

Author(s):

Graziella Ficociello ◽

Maria De Caris ◽

Giusy Trillò ◽

Domenico Cavallini ◽

Maria Sarto ◽

...

Keyword(s):

Zinc Oxide ◽

Candida Albicans ◽

Pathogenic Fungus ◽

In Vitro Cytotoxicity ◽

Yeast Cells ◽

Zinc Oxide Nanorods ◽

Aggregation State ◽

Oxide Nanorods ◽

Biofilm Development

Candida albicans is the most common pathogenic fungus that is isolated in nosocomial infections in medically and immune-compromised patients. The ability of C. albicans to convert its form from yeast to hyphal morphology contributes to biofilm development that effectively shelters Candida against the action of antifungals molecules. In the last years, nanocomposites are the most promising solutions against drug-resistant microorganisms. The aim of this study was to investigate the antifungal activity of graphene nanoplateles decorated with zinc oxide nanorods (ZNGs) against the human pathogen Candida albicans. We observed that ZNGs were able to induce a significant mortality in fungal cells, as well as to affect the main virulence factors of this fungus or rather the hyphal development and biofilm formation. Reactive Oxygen Species (ROS) formation in yeast cells resulted one of the mechanisms of ZNGs to induce mortality. Finally, the toxicity of this nanomaterial was tested also on human keratinocyte cell line HaCaT. Our data indicated that ZNGs resulted not toxic when their aggregation state decreased by adding glycerol as emulsifier to ZNGs suspensions or when HaCaT cells were grown on ZNGs-coated glasses. Overall, the results that were obtained indicated that ZNGs could be exploited as an antifungal nanomaterial with a high degree of biocompatibility on human cells.

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Effect of fluconazole on viability of Candida albicans over extended periods of time.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.40.11.2622 ◽

1996 ◽

Vol 40 (11) ◽

pp. 2622-2625 ◽

Cited By ~ 13

Author(s):

P G Sohnle ◽

B L Hahn ◽

M D Erdmann

Keyword(s):

Candida Albicans ◽

Marked Reduction ◽

Culture Medium ◽

Antimicrobial Agents ◽

Yeast Cells ◽

In Vitro Susceptibility ◽

Fungistatic Activity ◽

Susceptibility Tests ◽

Infecting Organisms

The treatment of chronic mycoses may expose the infecting organisms to antimicrobial agents for extended periods of time. It is possible that an azole antifungal drug such as fluconazole, with primarily fungistatic activity in standard in vitro susceptibility tests, might be able to damage the fungal cells and reduce their viability over prolonged incubations under nonproliferating conditions. To test this possibility, Candida albicans yeast cells were exposed to various concentrations of fluconazole in RPMI 1640 tissue culture medium for 4 h at 37 degrees C, washed free of the drug, and then incubated at 37 degrees C for a 28-day period; enumeration of the remaining CFU at various times during this period revealed no increased loss of viability for the fluconazole-exposed organisms. However, when fluconazole was added to the organisms maintained in distilled water (with or without pretreatment with the drug), a marked reduction of viability was found. At 14 days of incubation with two strains of C. albicans, negative cultures were found for 7 of 10 and 10 of 11 samples, respectively, containing 1.0 microgram of fluconazole per ml versus 0 of 10 and 1 of 11 control samples (P of < 0.01 and 0.001, respectively). The effect of fluconazole on fungal viability under these conditions became noticeable at approximately 7 days and was greater when the samples were incubated at 37 degrees C rather than 25 degrees C. These findings suggest that fluconazole may have fungicidal effects on fungal cells during prolonged exposures under conditions in which the organisms are prevented from proliferating by lack of nutrients.

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The Transcriptional Regulator Nrg1p Controls Candida albicans Biofilm Formation and Dispersion

Eukaryotic Cell ◽

10.1128/ec.00111-10 ◽

2010 ◽

Vol 9 (10) ◽

pp. 1531-1537 ◽

Cited By ~ 59

Author(s):

Priya Uppuluri ◽

Christopher G. Pierce ◽

Derek P. Thomas ◽

Sarah S. Bubeck ◽

Stephen P. Saville ◽

...

Keyword(s):

Candida Albicans ◽

Biofilm Formation ◽

Structural Integrity ◽

Genetically Engineered ◽

Negative Regulator ◽

Yeast Cells ◽

Developmental Cycle ◽

Content Type ◽

Adhesive Interactions

ABSTRACT The ability of Candida albicans to reversibly switch morphologies is important for biofilm formation and dispersion. In this pathogen, Nrg1p functions as a key negative regulator of the yeast-to-hypha morphogenetic transition. We have previously described a genetically engineered C. albicans tet-NRG1 strain in which NRG1 expression levels can be manipulated by the presence or absence of doxycycline (DOX). Here, we have used this strain to ascertain the role of Nrg1p in regulating the different stages of the C. albicans biofilm developmental cycle. In an in vitro model of biofilm formation, the C. albicans tet-NRG1 strain was able to form mature biofilms only when DOX was present in the medium, but not in the absence of DOX, when high levels of NRG1 expression blocked the yeast-to-hypha transition. However, in a biofilm cell retention assay in which biofilms were developed with mixtures of C. albicans tet-NRG1 and SC5314 strains, tet-NRG1 yeast cells were still incorporated into the mixed biofilms, in which an intricate network of hyphae of the wild-type strain provided for biofilm structural integrity and adhesive interactions. Also, utilizing an in vitro biofilm model under conditions of flow, we demonstrated that C. albicans Nrg1p exerts an exquisite control of the dispersal process, as overexpression of NRG1 leads to increases in dispersion of yeast cells from the biofilms. Our results demonstrate that manipulation of NRG1 gene expression has a profound influence on biofilm formation and biofilm dispersal, thus identifying Nrg1p as a key regulator of the C. albicans biofilm life cycle.

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Metabolism of inositol 1,4,5-trisphosphate in Candida albicans: significance as a precursor of inositol polyphosphates and in signal transduction during the dimorphic transition from yeast cells to germ tubes

Microbiology ◽

10.1099/00221287-143-2-437 ◽

1997 ◽

Vol 143 (2) ◽

pp. 437-448 ◽

Cited By ~ 8

Author(s):

G. M. Gadd ◽

S. A. Foster

Keyword(s):

Signal Transduction ◽

Candida Albicans ◽

Yeast Cells ◽

Inositol Polyphosphates ◽

Dimorphic Transition ◽

Inositol 1,4,5 Trisphosphate ◽

Germ Tubes

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Effect of Prolonged Fluconazole Treatment on Candida albicans in Diffusion Chambers Implanted into Mice

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.10.3175-3179.2002 ◽

2002 ◽

Vol 46 (10) ◽

pp. 3175-3179

Author(s):

Peter G. Sohnle ◽

Beth L. Hahn

Keyword(s):

Candida Albicans ◽

Inflammatory Response ◽

Inflammatory Cells ◽

Model System ◽

Antifungal Drugs ◽

Yeast Cells ◽

In Vitro Susceptibility ◽

Bonferroni Test

ABSTRACT Fluconazole is an azole agent with primarily fungistatic activity in standard in vitro susceptibility tests. The present study was undertaken to develop a diffusion chamber model system in mice in order to study the in vivo effects of prolonged fluconazole treatment on Candida albicans. Chambers containing 100 C. albicans yeast cells were implanted subcutaneously on the flanks of C57BL/6 mice and were then retrieved 6 or 14 weeks later (after fluconazole treatment for 4 or 12 weeks, respectively). Leukocyte counts demonstrated that implantation of the chambers did elicit an inflammatory response but that only small numbers of inflammatory cells were able to enter the chamber interior. Treatment with fluconazole at 10 mg/kg of body weight/day for 12 weeks not only reduced the numbers of viable organisms within the chambers compared to those in untreated mice (mean ± standard deviation of log10 CFU of 0.7 ± 1.2 versus 2.3 ± 2.0; P < 0.001 by the Bonferroni test) but also increased the numbers of chambers that became sterile over the treatment period (14 of 16 versus 6 of 19; P = 0.0009 by the chi-square test). However, treatment for only 4 weeks had minimal effects on the numbers of chamber CFU, and none of the chambers became sterile during this period. Distribution of retrieved organisms between interior fluid and the chamber filters was approximately equal in all the treatment groups. This model system appears to be useful for evaluating the effects of antifungal drugs over prolonged periods in vivo. Its use in the present study demonstrates that fluconazole can increase the rate of sterilization of C. albicans foci that are protected from the host's inflammatory response.

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Candida albicans SNO1 and SNZ1 expressed in stationary-phase planktonic yeast cells and base of biofilm

Microbiology ◽

10.1099/mic.0.28745-0 ◽

2006 ◽

Vol 152 (7) ◽

pp. 2031-2038 ◽

Cited By ~ 18

Author(s):

Priya Uppuluri ◽

Bhaskarjyoti Sarmah ◽

W. LaJean Chaffin

Keyword(s):

Candida Albicans ◽

Stationary Phase ◽

Fluorescent Protein ◽

Protein Localization ◽

Expression Patterns ◽

Yellow Fluorescent Protein ◽

Growth Conditions ◽

Yeast Cells ◽

Yeast Culture

The Candida albicans homologues of the most studied Saccharomyces cerevisiae stationary-phase genes, SNO1 and SNZ1, were used to test the hypothesis that, within a biofilm, some cells reach stationary phase within continuously fed, as well as static, C. albicans biofilms grown on dental acrylic. The authors first studied the expression patterns of these two genes in planktonic growth conditions. Using real-time RT-PCR (RT-RTPCR), increased peak expression of both SNZ1 and SNO1 was observed at 5 and 6 days, respectively, in C. albicans grown in suspension culture. SNZ1–yellow fluorescent protein (YFP) and SNO1–YFP were constructed to study expression at the cellular level and protein localization in C. albicans. Snz1p–YFP and Sno1p–YFP localized to the cytoplasm with maximum expression (>90 %) at 5 and 6 days, respectively, in planktonic conditions. When yeast growth was reinitiated, loss of fluorescence began immediately. Germ tubes and hyphae were non-fluorescent. Pseudohyphae began appearing at 9 days in planktonic yeast culture and expressed each protein by 11 days; however, the cells budding from pseudohyphae were not fluorescent. Biofilm was formed in vitro under either static or continuously fed conditions. Increased expression of the two genes was shown by RT-RTPCR, beginning by day 3 and increasing through to day 15 (continuously fed biofilm). Only the bottommost layer of acrylic-adhered cells in the biofilm showed 25 and 40 % fluorescence at 6 and 15 days, respectively. These observations suggest that only a few cells in C. albicans biofilms express genes associated with the planktonic stationary phase and that these are found at the bottom of the biofilm adhered to the surface.

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Impaired immune response to Candida albicans in aged mice

Journal of Medical Microbiology ◽

10.1099/jmm.0.46740-0 ◽

2006 ◽

Vol 55 (12) ◽

pp. 1649-1656 ◽

Cited By ~ 25

Author(s):

Celia Murciano ◽

Eva Villamón ◽

Alberto Yáñez ◽

José-Enrique O'Connor ◽

Daniel Gozalbo ◽

...

Keyword(s):

Immune Response ◽

Candida Albicans ◽

Fungal Infections ◽

Acquired Resistance ◽

Yeast Cells ◽

T Helper 1 ◽

Aged Mice ◽

Old Mice ◽

Young Mice

The prevalence of opportunistic fungal infections has increased dramatically among the aged population in recent years. This work investigated the effect of ageing on murine defences against Candida albicans. Aged C57BL/6 mice that were experimentally infected intravenously had a significantly impaired survival and a higher tissue fungal burden compared with young mice. In vitro production of tumour necrosis factor (TNF)-α by macrophages from aged mice in response to yeast cells and hyphae of C. albicans was significantly lower than production by macrophages from young mice. In vitro production of cytokines, such as TNF-α and gamma interferon (IFN-γ), by antigen-stimulated splenocytes from mice intravenously infected with C. albicans cells was also diminished in old mice. This decrease in production of T helper 1 cytokines in old mice correlated with a diminished frequency of IFN-γ-producing CD4+ T lymphocytes, although the ability to develop an acquired resistance upon vaccination (primary sublethal infection) of mice with the low-virulence PCA2 strain was not affected in aged mice. The diversity of antigens recognized by C. albicans-specific antibodies in sera from infected aged mice was clearly diminished when compared with that from infected young mice. Taken together, these data show that aged mice develop an altered innate and adaptive immune response to C. albicans and are more susceptible to systemic primary candidiasis.

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