scholarly journals Antifungal Properties of Cationic Phenylene Ethynylenes and Their Impact on β-Glucan Exposure

2016 ◽  
Vol 60 (8) ◽  
pp. 4519-4529 ◽  
Author(s):  
Harry C. Pappas ◽  
Rina Sylejmani ◽  
Matthew S. Graus ◽  
Patrick L. Donabedian ◽  
David G. Whitten ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Membrane Integrity ◽  
Significant Risk ◽  
Yeast Cells ◽  
Size Difference ◽  
Phenylene Ethynylene ◽  
Biocidal Activity ◽  
Content Type ◽  
Antifungal Properties ◽  
Phenylene Ethynylenes

ABSTRACTCandidaspecies are the cause of many bloodstream infections through contamination of indwelling medical devices. These infections account for a 40% mortality rate, posing a significant risk to immunocompromised patients. Traditional treatments againstCandidainfections include amphotericin B and various azole treatments. Unfortunately, these treatments are associated with high toxicity, and resistant strains have become more prevalent. As a new frontier, light-activated phenylene ethynylenes have shown promising biocidal activity against Gram-positive and -negative bacterial pathogens, as well as the environmental yeastSaccharomyces cerevisiae. In this study, we monitored the viability ofCandidaspecies after treatment with a cationic conjugated polymer [poly(p-phenylene ethynylene); PPE] or oligomer [“end-only” oligo(p-phenylene ethynylene); EO-OPE] by flow cytometry in order to explore the antifungal properties of these compounds. The oligomer was found to disruptCandida albicansyeast membrane integrity independent of light activation, while PPE is able to do so only in the presence of light, allowing for some control as to the manner in which cytotoxic effects are induced. The contrast in killing efficacy between the two compounds is likely related to their size difference and their intrinsic abilities to penetrate the fungal cell wall. Unlike EO-OPE-DABCO (where DABCO is quaternized diazabicyclo[2,2,2]octane), PPE-DABCO displayed a strong propensity to associate with soluble β-glucan, which is expected to inhibit its ability to access and perturb the inner cell membrane ofCandidayeast. Furthermore, treatment with PPE-DABCO unmaskedCandida albicansβ-glucan and increased phagocytosis by Dectin-1-expressing HEK-293 cells. In summary, cationic phenylene ethynylenes show promising biocidal activity against pathogenicCandidayeast cells while also exhibiting immunostimulatory effects.

scholarly journals Altered Dynamics of Candida albicans Phagocytosis by Macrophages and PMNs When Both Phagocyte Subsets Are Present

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Fiona M. Rudkin ◽  
Judith M. Bain ◽  
Catriona Walls ◽  
Leanne E. Lewis ◽  
Neil A. R. Gow ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Immune System ◽  
Innate Immune System ◽  
Video Microscopy ◽  
Innate Immune ◽  
Live Cell ◽  
Yeast Cells ◽  
Polymorphonuclear Cells ◽  
Fungal Cell ◽  
Content Type

ABSTRACT An important first line of defense against Candida albicans infections is the killing of fungal cells by professional phagocytes of the innate immune system, such as polymorphonuclear cells (PMNs) and macrophages. In this study, we employed live-cell video microscopy coupled with dynamic image analysis tools to provide insights into the complexity of C. albicans phagocytosis when macrophages and PMNs were incubated with C. albicans alone and when both phagocyte subsets were present. When C. albicans cells were incubated with only one phagocyte subtype, PMNs had a lower overall phagocytic capacity than macrophages, despite engulfing fungal cells at a higher rate once fungal cells were bound to the phagocyte surface. PMNs were more susceptible to C. albicans-mediated killing than macrophages, irrespective of the number of C. albicans cells ingested. In contrast, when both phagocyte subsets were studied in coculture, the two cell types phagocytosed and cleared C. albicans at equal rates and were equally susceptible to killing by the fungus. The increase in macrophage susceptibility to C. albicans-mediated killing was a consequence of macrophages taking up a higher proportion of hyphal cells under these conditions. In the presence of both PMNs and macrophages, C. albicans yeast cells were predominantly cleared by PMNs, which migrated at a greater speed toward fungal cells and engulfed bound cells more rapidly. These observations demonstrate that the phagocytosis of fungal pathogens depends on, and is modified by, the specific phagocyte subsets present at the site of infection. IMPORTANCE Extensive work investigating fungal cell phagocytosis by macrophages and PMNs of the innate immune system has been carried out. These studies have been informative but have examined this phenomenon only when one phagocyte subset is present. The current study employed live-cell video microscopy to break down C. albicans phagocytosis into its component parts and examine the effect of a single phagocyte subset, versus a mixed phagocyte population, on these individual stages. Through this approach, we identified that the rate of fungal cell engulfment and rate of phagocyte killing altered significantly when both macrophages and PMNs were incubated in coculture with C. albicans compared to the rate of either phagocyte subset incubated alone with the fungus. This research highlights the significance of studying pathogen-host cell interactions with a combination of phagocytes in order to gain a greater understanding of the interactions that occur between cells of the host immune system in response to fungal invasion.

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

2012 ◽  
Vol 11 (10) ◽  
pp. 1257-1267 ◽  
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.

scholarly journals Identification of a Cell Death Pathway in Candida albicans during the Response to Pheromone

2010 ◽  
Vol 9 (11) ◽  
pp. 1690-1701 ◽  
Author(s):  
Kevin Alby ◽  
Dana Schaefer ◽  
Racquel Kim Sherwood ◽  
Stephen K. Jones ◽  
Richard J. Bennett
Keyword(s):  
Cell Death ◽  
Candida Albicans ◽  
Laboratory Strain ◽  
Opportunistic Pathogen ◽  
Cell Types ◽  
Yeast Cells ◽  
Phenotypic Switching ◽  
Morphological Response ◽  
Content Type ◽  
Cell Death Pathway

ABSTRACT Mating in hemiascomycete yeasts involves the secretion of pheromones that induce sexual differentiation in cells of the opposite mating type. Studies in Saccharomyces cerevisiae have revealed that a subpopulation of cells experiences cell death during exposure to pheromone. In this work, we tested whether the phenomenon of pheromone-induced death (PID) also occurs in the opportunistic pathogen Candida albicans. Mating in C. albicans is uniquely regulated by white-opaque phenotypic switching; both cell types respond to pheromone, but only opaque cells undergo the morphological transition and cell conjugation. We show that approximately 20% of opaque cells, but not white cells, of laboratory strain SC5314 experience pheromone-induced death. Furthermore, analysis of mutant strains revealed that PID was significantly reduced in strains lacking Fig1 or Fus1 transmembrane proteins that are induced during the mating process and, we now show, are necessary for efficient mating in C. albicans. The level of PID was also Ca2+ dependent, as chelation of Ca2+ ions increased cell death to almost 50% of the population. However, in contrast to S. cerevisiae PID, pheromone-induced killing of C. albicans cells was largely independent of signaling via the Ca2+-dependent protein phosphatase calcineurin, even when combined with the loss of Cmk1 and Cmk2 proteins. Finally, we demonstrate that levels of PID vary widely between clinical isolates of C. albicans, with some strains experiencing close to 70% cell death. We discuss these findings in light of the role of prodeath and prosurvival pathways operating in yeast cells undergoing the morphological response to pheromone.

scholarly journals Zap1 Control of Cell-Cell Signaling in Candida albicans Biofilms

2011 ◽  
Vol 10 (11) ◽  
pp. 1448-1454 ◽  
Author(s):  
Shantanu Ganguly ◽  
Andrew C. Bishop ◽  
Wenjie Xu ◽  
Suman Ghosh ◽  
Kenneth W. Nickerson ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Yeast Cells ◽  
Gas Chromatography Mass Spectrometry ◽  
Wild Type ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Hypha Formation ◽  
Dependent Signal ◽  
Reporter Strains ◽  
Biosensor Strain

ABSTRACTBiofilms ofCandida albicansinclude both yeast cells and hyphae. Prior studies indicated that azap1Δ/Δ mutant, defective in zinc regulator Zap1, has increased accumulation of yeast cells in biofilms. This altered yeast-hypha balance may arise from internal regulatory alterations or from an effect on the production of diffusible quorum-sensing (QS) molecules. Here, we develop biosensor reporter strains that express yeast-specificYWP1-RFPor hypha-specificHWP1-RFP, along with a constitutiveTDH3-GFPnormalization standard. Seeding these biosensor strains into biofilms allows a biological activity assay of the surrounding biofilm milieu. Azap1Δ/Δ biofilm induces the yeast-specificYWP1-RFPreporter in a wild-type biosensor strain, as determined by both quantitative reverse transcription-PCR (qRT-PCR) gene expression measurements and confocal microscopy. Remediation of thezap1Δ/Δ zinc uptake defect through zinc transporter geneZRT2overexpression reverses induction of the yeast-specificYWP1-RFPreporter. Gas chromatography-mass spectrometry (GC-MS) measurements of known organic QS molecules show that thezap1Δ/Δ mutant accumulates significantly less farnesol than wild-type or complemented strains and thatZRT2overexpression does not affect farnesol accumulation. Farnesol is a well-characterized inhibitor of hypha formation; hence, a reduction in farnesol levels inzap1Δ/Δ biofilms is unexpected. Our findings argue that a Zap1- and zinc-dependent signal affects the yeast-hypha balance and that it is operative in the low-farnesol environment of thezap1Δ/Δ biofilm. In addition, our results indicate that Zap1 is a positive regulator of farnesol accumulation.

scholarly journals The Transcriptional Regulator Nrg1p Controls Candida albicans Biofilm Formation and Dispersion

2010 ◽  
Vol 9 (10) ◽  
pp. 1531-1537 ◽  
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.

scholarly journals Antifungal Activity of Mammalian Serum Amyloid A1 against Candida albicans

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Jiao Gong ◽  
Jun Wu ◽  
Melanie Ikeh ◽  
Li Tao ◽  
Yulong Zhang ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Antifungal Activity ◽  
Membrane Integrity ◽  
Systemic Infection ◽  
Serum Amyloid ◽  
Infection Model ◽  
Fungal Cell ◽  
Content Type ◽  
Cell Membrane Integrity ◽  
Amyloid A

ABSTRACT Mammalian serum amyloid A (SAA) is a major acute phase protein that shows a massive increase in plasma concentration during inflammation. In the present study, we demonstrate that the expression of mouse SAA1 in serum was increased when infected with Candida albicans, a major human fungal pathogen, in a systemic infection model. We then set out to investigate the antifungal activity of SAA proteins against C. albicans. Recombinant human and mouse SAA1 (rhSAA1 and rmSAA1) were expressed and purified in Escherichia coli. Both rhSAA1 and rmSAA1 exhibited a potent antifungal activity against C. albicans. We further demonstrate that rhSAA1 binds to the cell surface of C. albicans, disrupts cell membrane integrity, and induces rapid fungal cell death in C. albicans. Our finding expands the known functions of SAA1 and provides new insight into host-Candida interactions during fungal infection.

scholarly journals Impact of a Cross-Kingdom Signaling Molecule of Candida albicans on Acinetobacter baumannii Physiology

2015 ◽  
Vol 60 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Xenia Kostoulias ◽  
Gerald L. Murray ◽  
Gustavo M. Cerqueira ◽  
Jason B. Kong ◽  
Farkad Bantun ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Cell Membrane ◽  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Defense Mechanism ◽  
Membrane Integrity ◽  
Efflux Pumps ◽  
Signaling Molecule ◽  
Content Type ◽  
Antagonistic Interactions

ABSTRACTMultidrug-resistant (MDR)Acinetobacter baumanniiis an opportunistic human pathogen that has become highly problematic in the clinical environment. Novel therapies are desperately required. To assist in identifying new therapeutic targets, the antagonistic interactions betweenA. baumanniiand the most common human fungal pathogen,Candida albicans, were studied. We have observed that theC. albicansquorum-sensing molecule, farnesol, has cross-kingdom interactions, affecting the viability ofA. baumannii. To gain an understanding of its mechanism, the transcriptional profile ofA. baumanniiexposed to farnesol was examined. Farnesol caused dysregulation of a large number of genes involved in cell membrane biogenesis, multidrug efflux pumps (AcrAB-like and AdeIJK-like), andA. baumanniivirulence traits such as biofilm formation (csuA,csuB, andompA) and motility (pilZandpilH). We also observed a strong induction in genes involved in cell division (minD,minE,ftsK,ftsB, andftsL). These transcriptional data were supported by functional assays showing that farnesol disruptsA. baumanniicell membrane integrity, alters cell morphology, and impairs virulence characteristics such as biofilm formation and twitching motility. Moreover, we showed thatA. baumanniiuses efflux pumps as a defense mechanism against this eukaryotic signaling molecule. Owing to its effects on membrane integrity, farnesol was tested to see if it potentiated the activity of the membrane-acting polymyxin antibiotic colistin. When coadministered, farnesol increased sensitivity to colistin for otherwise resistant strains. These data provide mechanistic understanding of the antagonistic interactions between diverse pathogens and may provide important insights into novel therapeutic strategies.

scholarly journals The Als3 Cell Wall Adhesin Plays a Critical Role in Human Serum Amyloid A1-Induced Cell Death and Aggregation in Candida albicans

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Jiao Gong ◽  
Jian Bing ◽  
Guobo Guan ◽  
Clarissa J. Nobile ◽  
Guanghua Huang
Keyword(s):  
Cell Death ◽  
Cell Wall ◽  
Candida Albicans ◽  
Critical Role ◽  
Membrane Integrity ◽  
Cell Aggregation ◽  
Serum Amyloid ◽  
Mouse Serum ◽  
Content Type ◽  
Serum Amyloid A1

ABSTRACT Antimicrobial peptides and proteins play critical roles in the host defense against invading pathogens. We recently discovered that recombinantly expressed human and mouse serum amyloid A1 (rhSAA1 and rmSAA1, respectively) proteins have potent antifungal activities against the major human fungal pathogen Candida albicans. At high concentrations, rhSAA1 disrupts C. albicans membrane integrity and induces rapid fungal cell death. In the present study, we find that rhSAA1 promotes cell aggregation and targets the C. albicans cell wall adhesin Als3. Inactivation of ALS3 in C. albicans leads to a striking decrease in cell aggregation and cell death upon rhSAA1 treatment, suggesting that Als3 plays a critical role in SAA1 sensing. We further demonstrate that deletion of the transcriptional regulators controlling the expression of ALS3, such as AHR1, BCR1, and EFG1, in C. albicans results in similar effects to that of the als3/als3 mutant upon rhSAA1 treatment. Global gene expression profiling indicates that rhSAA1 has a discernible impact on the expression of cell wall- and metabolism-related genes, suggesting that rhSAA1 treatment could lead to a nutrient starvation effect on C. albicans cells.

scholarly journals Inactivation of the Antifungal and Immunomodulatory Properties of Human Cathelicidin LL-37 by Aspartic Proteases Produced by the Pathogenic Yeast Candida albicans

2015 ◽  
Vol 83 (6) ◽  
pp. 2518-2530 ◽  
Author(s):  
Maria Rapala-Kozik ◽  
Oliwia Bochenska ◽  
Marcin Zawrotniak ◽  
Natalia Wolak ◽  
Grzegorz Trebacz ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Phorbol Esters ◽  
Proteolytic Processing ◽  
Yeast Cells ◽  
Calcium Flux ◽  
Fungal Colonization ◽  
Pathogenic Yeast ◽  
Aspartic Proteases ◽  
Content Type ◽  
Immunomodulatory Properties

Constant cross talk betweenCandida albicansyeast cells and their human host determines the outcome of fungal colonization and, eventually, the progress of infectious disease (candidiasis). An effective weapon used byC. albicansto cope with the host defense system is the release of 10 distinct secreted aspartic proteases (SAPs). Here, we validate a hypothesis that neutrophils and epithelial cells use the antimicrobial peptide LL-37 to inactivateC. albicansat sites of candidal infection and thatC. albicansuses SAPs to effectively degrade LL-37. LL-37 is cleaved into multiple products by SAP1 to -4, SAP8, and SAP9, and this proteolytic processing is correlated with the gradual decrease in the antifungal activity of LL-37. Moreover, a major intermediate of LL-37 cleavage—the LL-25 peptide—is antifungal but devoid of the immunomodulatory properties of LL-37. In contrast to LL-37, LL-25 did not affect the generation of reactive oxygen species by neutrophils upon treatment with phorbol esters. Stimulating neutrophils with LL-25 (rather than LL-37) significantly decreased calcium flux and interleukin-8 production, resulting in lower chemotactic activity of the peptide against neutrophils, which may decrease the recruitment of neutrophils to infection foci. LL-25 also lost the function of LL-37 as an inhibitor of neutrophil apoptosis, thereby reducing the life span of these defense cells. This study indicates thatC. albicanscan effectively use aspartic proteases to destroy the antimicrobial and immunomodulatory properties of LL-37, thus enabling the pathogen to survive and propagate.

scholarly journals Sustained Nitric Oxide-Releasing Nanoparticles Induce Cell Death in Candida albicans Yeast and Hyphal Cells, Preventing Biofilm FormationIn Vitroand in a Rodent Central Venous Catheter Model

2016 ◽  
Vol 60 (4) ◽  
pp. 2185-2194 ◽  
Author(s):  
Mohammed S. Ahmadi ◽  
Hiu Ham Lee ◽  
David A. Sanchez ◽  
Adam J. Friedman ◽  
Moses T. Tar ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Candida Albicans ◽  
Flow Cytometric Analysis ◽  
Extracellular Polysaccharide ◽  
Host Cells ◽  
Yeast Cells ◽  
Central Venous ◽  
Content Type ◽  
Biofilm Development

ABSTRACTCandida albicansis a leading nosocomial pathogen. Today, candidal biofilms are a significant cause of catheter infections, and such infections are becoming increasingly responsible for the failure of medical-implanted devices.C. albicansforms biofilms in which fungal cells are encased in an autoproduced extracellular polysaccharide matrix. Consequently, the enclosed fungi are protected from antimicrobial agents and host cells, providing a unique niche conducive to robust microbial growth and a harbor for recurring infections. Here we demonstrate that a recently developed platform comprised of nanoparticles that release therapeutic levels of nitric oxide (NO-np) inhibits candidal biofilm formation, destroys the extracellular polysaccharide matrices of mature fungal biofilms, and hinders biofilm development on surface biomaterials such as the lumen of catheters. We found NO-np to decrease both the metabolic activity of biofilms and the cell viability ofC. albicansin vitroandin vivo. Furthermore, flow cytometric analysis found NO-np to induce apoptosis in biofilm yeast cellsin vitro. Moreover, NO-np behave synergistically when used in combination with established antifungal drug therapies. Here we propose NO-np as a novel treatment modality, especially in combination with standard antifungals, for the prevention and/or remediation of fungal biofilms on central venous catheters and other medical devices.

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