In Fungal Intracellular Pathogenesis, Form Determines Fate

ABSTRACT For pathogenic microbes to survive ingestion by macrophages, they must subvert powerful microbicidal mechanisms within the phagolysosome. After ingestion, Candida albicans undergoes a morphological transition producing hyphae, while the surrounding phagosome exhibits a loss of phagosomal acidity. However, how these two events are related has remained enigmatic. Now Westman et al. (mBio 9:e01226-18, 2018, https://doi.org/10.1128/mBio.01226-18) report that phagosomal neutralization results from disruption of phagosomal membrane integrity by the enlarging hyphae, directly implicating the morphological transition in physical damage that promotes intracellular survival. The C. albicans intracellular strategy shows parallels with another fungal pathogen, Cryptococcus neoformans, where a morphological changed involving capsular enlargement intracellularly is associated with loss of membrane integrity and death of the host cell. These similarities among distantly related pathogenic fungi suggest that morphological transitions that are common in fungi directly affect the outcome of the fungal cell-macrophage interaction. For this class of organisms, form determines fate in the intracellular environment.

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Simple Carbohydrate Derivatives Diminish the Formation of Biofilm of the Pathogenic Yeast Candida albicans

Antibiotics ◽

10.3390/antibiotics9010010 ◽

2019 ◽

Vol 9 (1) ◽

pp. 10 ◽

Cited By ~ 1

Author(s):

Olena P. Ishchuk ◽

Olov Sterner ◽

Ulf Ellervik ◽

Sophie Manner

Keyword(s):

Candida Albicans ◽

Fungal Pathogen ◽

Biofilm Formation ◽

Untreated Control ◽

Morphological Transition ◽

Pathogenic Yeast ◽

Yeast Form ◽

Human Fungal Pathogen ◽

Morphological Transitions ◽

Simple Carbohydrate

The opportunistic human fungal pathogen Candida albicans relies on cell morphological transitions to develop biofilm and invade the host. In the current study, we developed new regulatory molecules, which inhibit the morphological transition of C. albicans from yeast-form cells to cells forming hyphae. These compounds, benzyl α-l-fucopyranoside and benzyl β-d-xylopyranoside, inhibit the hyphae formation and adhesion of C. albicans to a polystyrene surface, resulting in a reduced biofilm formation. The addition of cAMP to cells treated with α-l-fucopyranoside restored the yeast-hyphae switch and the biofilm level to that of the untreated control. In the β-d-xylopyranoside treated cells, the biofilm level was only partially restored by the addition of cAMP, and these cells remained mainly as yeast-form cells.

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Simple Carbohydrate Derivatives Diminish the Formation of Biofilm of Candida albicans

10.21203/rs.2.16042/v2 ◽

2019 ◽

Author(s):

Olena P. Ishchuk ◽

Olov Sterner ◽

Ulf Ellervik ◽

Sophie Manner

Keyword(s):

Candida Albicans ◽

Fungal Pathogen ◽

Biofilm Formation ◽

Untreated Control ◽

Morphological Transition ◽

Yeast Form ◽

Polystyrene Surface ◽

Human Fungal Pathogen ◽

Morphological Transitions ◽

Simple Carbohydrate

Abstract The opportunistic human fungal pathogen Candida albicans rely on cell morphological transitions to develop biofilm and invade the host. In the current study, we developed new regulatory molecules, which inhibit the morphological transition of C. albicans from yeast-form cells to cells forming hyphae. These compounds, benzyl α-L-fucopyranoside and benzyl β-D-xylopyranoside, inhibit the morphological switching and adhesion of C. albicans to a polystyrene surface, resulting in a reduced biofilm formation. The addition of cAMP to cells treated with α-L-fucopyranoside restored the yeast-hyphae switch and the biofilm level to that of the untreated control. In the β-D-xylopyranoside treated cells, the biofilm level was only partially restored by the addition of cAMP, and these cells remained mainly as yeast-form cells.

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Simple Carbohydrate Derivatives Diminish the Formation of Biofilm of Candida albicans

10.21203/rs.2.16042/v1 ◽

2019 ◽

Author(s):

Olena P. Ishchuk ◽

Olov Sterner ◽

Ulf Ellervik ◽

Sophie Manner

Keyword(s):

Candida Albicans ◽

Fungal Pathogen ◽

Biofilm Formation ◽

Untreated Control ◽

Morphological Transition ◽

Yeast Form ◽

Polystyrene Surface ◽

Human Fungal Pathogen ◽

Morphological Transitions ◽

Simple Carbohydrate

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The Cek1 and Hog1 Mitogen-Activated Protein Kinases Play Complementary Roles in Cell Wall Biogenesis and Chlamydospore Formation in the Fungal Pathogen Candida albicans

Eukaryotic Cell ◽

10.1128/ec.5.2.347-358.2006 ◽

2006 ◽

Vol 5 (2) ◽

pp. 347-358 ◽

Cited By ~ 109

Author(s):

B. Eisman ◽

R. Alonso-Monge ◽

E. Román ◽

D. Arana ◽

C. Nombela ◽

...

Keyword(s):

Cell Wall ◽

Candida Albicans ◽

Map Kinase ◽

Fungal Pathogen ◽

Hog Pathway ◽

Cell Wall Biogenesis ◽

Chlamydospore Formation ◽

Mitogen Activated Protein ◽

Morphological Transitions ◽

Relationship Of

ABSTRACT The Hog1 mitogen-activated protein (MAP) kinase mediates an adaptive response to both osmotic and oxidative stress in the fungal pathogen Candida albicans. This protein also participates in two distinct morphogenetic processes, namely the yeast-to-hypha transition (as a repressor) and chlamydospore formation (as an inducer). We show here that repression of filamentous growth occurs both under serum limitation and under other partially inducing conditions, such as low temperature, low pH, or nitrogen starvation. To understand the relationship of the HOG pathway to other MAP kinase cascades that also play a role in morphological transitions, we have constructed and characterized a set of double mutants in which we deleted both the HOG1 gene and other signaling elements (the CST20, CLA4, and HST7 kinases, the CPH1 and EFG1 transcription factors, and the CPP1 protein phosphatase). We also show that Hog1 prevents the yeast-to-hypha switch independent of all the elements analyzed and that the inability of the hog1 mutants to form chlamydospores is suppressed when additional elements of the CEK1 pathway (CST20 or HST7) are altered. Finally, we report that Hog1 represses the activation of the Cek1 MAP kinase under basal conditions and that Cek1 activation correlates with resistance to certain cell wall inhibitors (such as Congo red), demonstrating a role for this pathway in cell wall biogenesis.

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Two Polyketides Produced by Endophytic Penicillium citrinum DBR-9 From Medicinal Plant Stephania kwangsiensis and Their Antifungal Activity Against Plant Pathogenic Fungi

Natural Product Communications ◽

10.1177/1934578x19846795 ◽

2019 ◽

Vol 14 (5) ◽

pp. 1934578X1984679 ◽

Cited By ~ 2

Author(s):

Haiyu Luo ◽

Zhen Qing ◽

Yecheng Deng ◽

Zhiyong Deng ◽

Xia’an Tang ◽

...

Keyword(s):

Medicinal Plant ◽

Membrane Integrity ◽

Pathogenic Fungi ◽

Significant Inhibition ◽

Penicillium Citrinum ◽

Plant Pathogenic Fungi ◽

Fungal Cell ◽

Cell Membrane Integrity ◽

Chinese Medicinal Plant

Endophytic fungi, especially those found in medicinal plants, are widely studied as producers of secondary metabolites of biotechnological interest. In this study, on the basis of an activity-directed isolation method and spectroscopic analysis, two active polyketides, citrinin (1) and emodin (2), were isolated and identified from the fermentation of the endophytic fungus Penicillium citrinum DBR-9. This fungus was isolated from the root tubers of the traditional Chinese medicinal plant Stephania kwangsiensis. In vitro antifungal assay showed that the two polyketides displayed significant inhibition on hypha growth of tested plant pathogenic fungi with IC50 values ranging from 3.1 to 123.1 μg/mL and 3.0 to 141.0 μg/mL, respectively. In addition, the mechanism of the effects of emodin (2) on the pathogen revealed it could affect the colony morphology, destroy cell membrane integrity, and influence the protein synthesis of the tested fungal cell. This work is the first report of two polyketides-producing endophytic P. citrinum DBR-9 from the medicinal plant S. kwangsiensis. Our results present new opportunities to deeply understand the potential of these two polyketides as natural antifungal agents to control phytopathogens in agriculture.

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Candida albicans Chitin Increases Arginase-1 Activity in Human Macrophages, with an Impact on Macrophage Antimicrobial Functions

mBio ◽

10.1128/mbio.01820-16 ◽

2017 ◽

Vol 8 (1) ◽

Cited By ~ 37

Author(s):

Jeanette Wagener ◽

Donna M. MacCallum ◽

Gordon D. Brown ◽

Neil A. R. Gow

Keyword(s):

Nitric Oxide ◽

Candida Albicans ◽

Fungal Pathogen ◽

Arginase Activity ◽

Nitric Oxide Production ◽

Fungal Cell ◽

Oxide Production ◽

Arginase 1 ◽

Oxide Synthase ◽

Inducible Nitric Oxide

ABSTRACT The opportunistic human fungal pathogen Candida albicans can cause a variety of diseases, ranging from superficial mucosal infections to life-threatening systemic infections. Phagocytic cells of the innate immune response, such as neutrophils and macrophages, are important first-line responders to an infection and generate reactive oxygen and nitrogen species as part of their protective antimicrobial response. During an infection, host cells generate nitric oxide through the enzyme inducible nitric oxide synthase (iNOS) to kill the invading pathogen. Inside the phagocyte, iNOS competes with the enzyme arginase-1 for a common substrate, the amino acid l -arginine. Several pathogenic species, including bacteria and parasitic protozoans, actively modulate the production of nitric oxide by inducing their own arginases or the host’s arginase activity to prevent the conversion of l -arginine to nitric oxide. We report here that C. albicans blocks nitric oxide production in human-monocyte-derived macrophages by induction of host arginase activity. We further determined that purified chitin (a fungal cell wall polysaccharide) and increased chitin exposure at the fungal cell wall surface induces this host arginase activity. Blocking the C. albicans -induced arginase activity with the arginase-specific substrate inhibitor N ω-hydroxy-nor-arginine (nor-NOHA) or the chitinase inhibitor bisdionin F restored nitric oxide production and increased the efficiency of fungal killing. Moreover, we determined that C. albicans influences macrophage polarization from a classically activated phenotype toward an alternatively activated phenotype, thereby reducing antimicrobial functions and mediating fungal survival. Therefore, C. albicans modulates l -arginine metabolism in macrophages during an infection, potentiating its own survival. IMPORTANCE The availability and metabolism of amino acids are increasingly recognized as crucial regulators of immune functions. In acute infections, the conversion of the “conditionally essential” amino acid l -arginine by the inducible nitric oxide synthase to nitric oxide is a resistance factor that is produced by the host to fight pathogens. Manipulation of these host defense mechanisms by the pathogen can be key to successful host invasion. We show here that the human opportunistic fungal pathogen Candida albicans influences l -arginine availability for nitric oxide production by induction of the substrate-competing host enzyme arginase-1. This led to a reduced production of nitric oxide and, moreover, reduced eradication of the fungus by human macrophages. We demonstrate that blocking of host arginase-1 activity restored nitric oxide production and increased the killing potential of macrophages. These results highlight the therapeutic potential of l -arginine metabolism in fungal diseases.

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Antifungal and Antibiofilm Activities and the Mechanism of Action of Repeating Lysine-Tryptophan Peptides against Candida albicans

Microorganisms ◽

10.3390/microorganisms8050758 ◽

2020 ◽

Vol 8 (5) ◽

pp. 758

Author(s):

Gopal Ramamourthy ◽

Jonggwan Park ◽

Changho Seo ◽

Hans J. Vogel ◽

Yoonkyung Park

Keyword(s):

Candida Albicans ◽

Antifungal Activity ◽

Laser Scanning ◽

Membrane Integrity ◽

Laser Scanning Confocal Microscopy ◽

Health Concern ◽

Cellular Functions ◽

Fungal Cell ◽

Scanning Confocal Microscopy ◽

Keratinocyte Cell

The rapid increase in the emergence of antifungal-resistant Candida albicans strains is becoming a serious health concern. Because antimicrobial peptides (AMPs) may provide a potential alternative to conventional antifungal agents, we have synthesized a series of peptides with a varying number of lysine and tryptophan repeats (KWn-NH2). The antifungal activity of these peptides increased with peptide length, but only the longest KW5 peptide displayed cytotoxicity towards a human keratinocyte cell line. The KW4 and KW5 peptides exhibited strong antifungal activity against C. albicans, even under conditions of high-salt and acidic pH, or the addition of fungal cell wall components. Moreover, KW4 inhibited biofilm formation by a fluconazole-resistant C. albicans strain. Circular dichroism and fluorescence spectroscopy indicated that fungal liposomes could interact with the longer peptides but that they did not release the fluorescent dye calcein. Subsequently, fluorescence assays with different dyes revealed that KW4 did not disrupt the membrane integrity of intact fungal cells. Scanning electron microscopy showed no changes in fungal morphology, while laser-scanning confocal microscopy indicated that KW4 can localize into the cytosol of C. albicans. Gel retardation assays revealed that KW4 can bind to fungal RNA as a potential intracellular target. Taken together, our data indicate that KW4 can inhibit cellular functions by binding to RNA and DNA after it has been translocated into the cell, resulting in the eradication of C. albicans.

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Induction of theCandida albicansFilamentous Growth Program by Relief of Transcriptional Repression: A Genome-wide Analysis

Molecular Biology of the Cell ◽

10.1091/mbc.e05-01-0073 ◽

2005 ◽

Vol 16 (6) ◽

pp. 2903-2912 ◽

Cited By ~ 207

Author(s):

David Kadosh ◽

Alexander D. Johnson

Keyword(s):

Candida Albicans ◽

Transcriptional Repression ◽

Fungal Pathogen ◽

Morphological Transition ◽

Whole Genome ◽

Transcriptional Repressors ◽

Genome Wide Analysis ◽

Human Fungal Pathogen ◽

Genome Wide ◽

A Genome

Candida albicans, the major human fungal pathogen, undergoes a reversible morphological transition from blastospores (round budding cells) to filaments (elongated cells attached end-to-end). This transition, which is induced upon exposure of C. albicans cells to a number of host conditions, including serum and body temperature (37°C), is required for virulence. Using whole-genome DNA microarray analysis, we describe 61 genes that are significantly induced (≥2-fold) during the blastospore to filament transition that takes place in response to exposure to serum and 37°C. We next show that approximately half of these genes are transcriptionally repressed in the blastospore state by three transcriptional repressors, Rfg1, Nrg1, and Tup1. We conclude that the relief of this transcriptional repression plays a key role in bringing the C. albicans filamentous growth program into play, and we describe the framework of this transcriptional circuit.

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Extracellular aspartic protease SAP2 of Candida albicans yeast cleaves human kininogens and releases proinflammatory peptides, Met-Lys-bradykinin and des-Arg9-Met-Lys-bradykinin

Biological Chemistry ◽

10.1515/hsz-2012-0157 ◽

2012 ◽

Vol 393 (8) ◽

pp. 829-839 ◽

Cited By ~ 17

Author(s):

Grazyna Bras ◽

Oliwia Bochenska ◽

Maria Rapala-Kozik ◽

Ibeth Guevara-Lora ◽

Alexander Faussner ◽

...

Keyword(s):

Candida Albicans ◽

Fungal Pathogen ◽

Aspartic Protease ◽

Lower Yield ◽

Fungal Cell ◽

Mediators Of Inflammation ◽

Microbial Infections ◽

Secreted Proteases ◽

Generating System ◽

Mass Form

Abstract Bradykinin-related peptides, universal mediators of inflammation collectively referred to as the kinins, are often produced in excessive amounts during microbial infections. We have recently shown that the yeast Candida albicans, the major fungal pathogen to humans, can exploit two mechanisms to enhance kinin levels at the sites of candidial infection, one depending on adsorption and activation of the endogenous kinin-generating system of the host on the fungal cell wall and the other relying on cleavage of kinin precursors, the kininogens, by pathogen-secreted proteases. This work aimed at assigning this kininogenase activity to the major secreted aspartic protease of C. albicans (SAP2). The purified SAP2 was shown to cleave human kininogens, preferably the low molecular mass form (LK) and optimally in an acidic environment (pH 3.5–4.0), and to produce two kinins, Met-Lys-bradykinin and its derivative, [Hydroxyproline3]-Met-Lys-bradykinin, both of which are capable of interacting with cellular bradykinin receptors of the B2 subtype. Additionally, albeit with a lower yield, des-Arg9-Met-Lys-bradykinin, an effective agonist of B1-subtype receptors, was released. The pathophysiological potential of these kinins and des-Arg-kinin was also proven by presenting their ability to stimulate human promonocytic cells U937 to release proinflammatory interleukin 1β (IL-1β) and IL-6.

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Antifungal Activity of Mammalian Serum Amyloid A1 against Candida albicans

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01975-19 ◽

2019 ◽

Vol 64 (1) ◽

Cited By ~ 2

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.

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