scholarly journals Mucins Suppress Virulence Traits of Candida albicans

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Nicole L. Kavanaugh ◽  
Angela Q. Zhang ◽  
Clarissa J. Nobile ◽  
Alexander D. Johnson ◽  
Katharina Ribbeck
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Therapeutic Potential ◽  
Content Type ◽  
Environmental Signals ◽  
Healthy Humans ◽  
Normal Microbiota ◽  
Life Threatening ◽  
Main Components

ABSTRACTCandida albicansis the most prevalent fungal pathogen of humans, causing a variety of diseases ranging from superficial mucosal infections to deep-seated systemic invasions. Mucus, the gel that coats all wet epithelial surfaces, accommodatesC. albicansas part of the normal microbiota, whereC. albicansresides asymptomatically in healthy humans. Through a series ofin vitroexperiments combined with gene expression analysis, we show that mucin biopolymers, the main gel-forming constituents of mucus, induce a new oval-shaped morphology inC. albicansin which a range of genes related to adhesion, filamentation, and biofilm formation are downregulated. We also show that corresponding traits are suppressed, renderingC. albicansimpaired in forming biofilms on a range of different synthetic surfaces and human epithelial cells. Our data suggest that mucins can manipulateC. albicansphysiology, and we hypothesize that they are key environmental signals for retainingC. albicansin the host-compatible, commensal state.IMPORTANCEThe yeastCandida albicanscauses both superficial infections of the mucosa and life-threatening infections upon entering the bloodstream. However,C. albicansis not always harmful and can exist as part of the normal microbiota without causing disease. Internal body surfaces that are susceptible to infection byC. albicansare coated with mucus, which we hypothesize plays an important role in preventing infections. Here, we show that the main components of mucus, mucin glycoproteins, suppress virulence attributes ofC. albicansat the levels of gene expression and the corresponding morphological traits. Specifically, mucins suppress attachment to plastic surfaces and human cells, the transition to cell-penetrating hyphae, and the formation of biofilms (drug-resistant microbial communities). Additionally, exposure to mucins induces an elongated morphology that physically resembles the mating-competent opaque state but is phenotypically distinct. We suggest that mucins are potent antivirulence molecules that have therapeutic potential for suppressingC. albicansinfections.

scholarly journals Effects of Echinocandins in Combination with Nikkomycin Z against Invasive Candida albicans Bloodstream Isolates and the fks Mutants

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Yuk-Yam Cheung ◽  
Mamie Hui
Keyword(s):  
Candida Albicans ◽  
Therapeutic Potential ◽  
Synergistic Effects ◽  
Rank Test ◽  
Content Type ◽  
Log Rank Test ◽  
Echinocandin Resistance ◽  
Nikkomycin Z

ABSTRACT We evaluated the in vitro and in vivo effects of nikkomycin Z combined with an echinocandin (anidulafungin or micafungin) against two Candida albicans isolates and their lab-derived echinocandin-resistant fks mutants with FKS1 S645Y and FKS1 S645P. Synergistic effects were observed in all tested strains (fractional inhibitory concentration index, <0.5). Enhanced survival was observed in an immunocompromised murine model (log-rank test, P < 0.02). Our study demonstrated the therapeutic potential of nikkomycin Z-echinocandin combinations in managing echinocandin resistance.

scholarly journals The Ferredoxin-Like Protein FerR Regulates PrbP Activity inLiberibacter asiaticus

2018 ◽  
Vol 85 (4) ◽  
Author(s):  
Lei Pan ◽  
Danilo da Silva ◽  
Fernando A. Pagliai ◽  
Natalie A. Harrison ◽  
Claudio F. Gonzalez ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase ◽  
Regulation Of Gene Expression ◽  
Accessory Protein ◽  
Mrna Levels ◽  
Plant Host ◽  
Content Type ◽  
Environmental Signals ◽  
Liberibacter Asiaticus

ABSTRACTInLiberibacter asiaticus, PrbP is an important transcriptional accessory protein that regulates gene expression through interactions with the RNA polymerase β-subunit and a specific sequence on the promoter region. The constitutive expression ofprbPobserved upon chemical inactivation of PrbP-DNA interactionsin vivoindicated that the expression ofprbPwas not autoregulated at the level of transcription. This observation suggested that a modulatory mechanism via protein-protein interactions may be involved.In silicogenome association analysis identified FerR (CLIBASIA_01505), a putative ferredoxin-like protein, as a PrbP-interacting protein. Using a bacterial two-hybrid system and immunoprecipitation assays, interactions between PrbP and FerR were confirmed.In vitrotranscription assays were used to show that FerR can increase the activity of PrbP by 16-fold when present in the PrbP-RNA polymerase reaction mixture. The FerR protein-protein interaction surface was predicted by structural modeling and followed by site-directed mutagenesis. Amino acids V20, V23, and C40 were identified as the most important residues in FerR involved in the modulation of PrbP activityin vitro. The regulatory mechanism of FerR abundance was examined at the transcription level. In contrast toprbPofL. asiaticus(prbPLas), mRNA levels offerRofL. asiaticus(ferRLas) are induced by an increase in osmotic pressure. The results of this study revealed that the activity of the transcriptional activator PrbPLasis modulated via interactions with FerRLas. The induction offerRLasexpression by osmolarity provides insight into the mechanisms of adjusting gene expression in response to host environmental signals inL. asiaticus.IMPORTANCEThe rapid spread and aggressive progression of huanglongbing (HLB) in the major citrus-producing areas have raised global recognition of and vigilance to this disease. As a result, the causative agent,Liberibacter asiaticus, has been investigated from various perspectives. However, gene expression regulatory mechanisms that are important for the survival and persistence of this intracellular pathogen remain largely unexplored. PrbP is a transcriptional accessory protein important forL. asiaticussurvival in the plant host. In this study, we investigated the interactions between PrbP inL. asiaticus(PrbPLas) and a ferredoxin-like protein (FerR) inL. asiaticus, FerRLas. We show that the presence of FerR stabilizes and augments the activity of PrbPLas. In addition, we demonstrate that the expression offerRis induced by increases in osmolarity inLiberibacter crescens. Altogether, these results suggest that FerRLasand PrbPLasmay play important roles in the regulation of gene expression in response to changing environmental signals duringL. asiaticusinfection in the citrus host.

scholarly journals Divergent Targets of Candida albicans Biofilm Regulator Bcr1In VitroandIn Vivo

2012 ◽  
Vol 11 (7) ◽  
pp. 896-904 ◽  
Author(s):  
Saranna Fanning ◽  
Wenjie Xu ◽  
Norma Solis ◽  
Carol A. Woolford ◽  
Scott G. Filler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Stress Response ◽  
Growth Conditions ◽  
Gene Expression Measurement ◽  
Content Type ◽  
New Genes

ABSTRACTCandida albicansis a causative agent of oropharyngeal candidiasis (OPC), a biofilm-like infection of the oral mucosa. Biofilm formation depends upon theC. albicanstranscription factor Bcr1, and previous studies indicate that Bcr1 is required for OPC in a mouse model of infection. Here we have used a nanoString gene expression measurement platform to elucidate the role of Bcr1 in OPC-related gene expression. We chose for assays a panel of 134 genes that represent a range of morphogenetic and cell cycle functions as well as environmental and stress response pathways. We assayed gene expression in whole infected tongue samples. The results sketch a portrait ofC. albicansgene expression in which numerous stress response pathways are activated during OPC. This one set of experiments identifies 64 new genes with significantly altered RNA levels during OPC, thus increasing substantially the number of known genes in this expression class. Thebcr1Δ/Δ mutant had a much more limited gene expression defect during OPC infection than previously reported forin vitrogrowth conditions. Among major functional Bcr1 targets, we observed thatALS3was Bcr1 dependentin vivowhileHWP1was not. We used null mutants and complemented strains to verify that Bcr1 and Hwp1 are required for OPC infection in this model. The role of Als3 is transient and mild, though significant. Our findings suggest that the versatility ofC. albicansas a pathogen may reflect its ability to persist in the face of multiple stresses and underscore that transcriptional circuitry during infection may be distinct from that detailed duringin vitrogrowth.

scholarly journals The Synergistic Effect of Azoles and Fluoxetine against Resistant Candida albicans Strains Is Attributed to Attenuating Fungal Virulence

2016 ◽  
Vol 60 (10) ◽  
pp. 6179-6188 ◽  
Author(s):  
Wenrui Gu ◽  
Dongmei Guo ◽  
Liuping Zhang ◽  
Dongmei Xu ◽  
Shujuan Sun
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Synergistic Effects ◽  
Mechanism Study ◽  
Content Type ◽  
Expression Levels ◽  
Time Kill ◽  
Gene Expression Levels

ABSTRACTThis study evaluated the synergistic effects of the selective serotonin reuptake inhibitor, fluoxetine, in combination with azoles againstCandida albicansbothin vitroandin vivoand explored the underlying mechanism. MICs, sessile MICs, and time-kill curves were determined for resistantC. albicans.Galleria mellonellawas used as a nonvertebrate model for determining the efficacy of the drug combinations againstC. albicansin vivo. For the mechanism study, gene expression levels of theSAPgene family were determined by reverse transcription (RT)-PCR, and extracellular phospholipase activities were detectedin vitroby the egg yolk agar method. The combinations resulted in synergistic activity againstC. albicansstrains, but the same effect was not found for the non-albicans Candidastrains. For the biofilms formed over 4, 8, and 12 h, synergism was seen for the combination of fluconazole and fluoxetine. In addition, the time-kill curves confirmed the synergism dynamically. The results of theG. mellonellastudies agreed with thein vitroanalysis. In the mechanism study, we observed that fluconazole plus fluoxetine caused downregulation of the gene expression levels ofSAP1toSAP4and weakened the extracellular phospholipase activities of resistantC. albicans. The combinations of azoles and fluoxetine showed synergistic effects against resistantC. albicansmay diminish the virulence properties ofC. albicans.

scholarly journals Modulation of Morphogenesis in Candida albicans by Various Small Molecules

2011 ◽  
Vol 10 (8) ◽  
pp. 1004-1012 ◽  
Author(s):  
Julie Shareck ◽  
Pierre Belhumeur
Keyword(s):  
Candida Albicans ◽  
Small Molecules ◽  
Histone Deacetylase Inhibitors ◽  
Therapeutic Potential ◽  
Antifungal Drugs ◽  
Pathogenic Yeast ◽  
Content Type ◽  
Life Threatening ◽  
Experimental Findings ◽  
Cell Cycle Inhibitors

ABSTRACTThe pathogenic yeastCandida albicans, a member of the mucosal microbiota, is responsible for a large spectrum of infections, ranging from benign thrush and vulvovaginitis in both healthy and immunocompromised individuals to severe, life-threatening infections in immunocompromised patients. A striking feature ofC. albicansis its ability to grow as budding yeast and as filamentous forms, including hyphae and pseudohyphae. The yeast-to-hypha transition contributes to the overall virulence ofC. albicansand may even constitute a target for the development of antifungal drugs. Indeed, impairing morphogenesis inC. albicanshas been shown to be a means to treat candidiasis. Additionally, a large number of small molecules such as farnesol, fatty acids, rapamycin, geldanamycin, histone deacetylase inhibitors, and cell cycle inhibitors have been reported to modulate the yeast-to-hypha transition inC. albicans. In this minireview, we take a look at molecules that modulate morphogenesis in this pathogenic yeast. When possible, we address experimental findings regarding their mechanisms of action and their therapeutic potential. We discuss whether or not modulating morphogenesis constitutes a strategy to treatCandidainfections.

scholarly journals Regulatory Role of Glycerol in Candida albicans Biofilm Formation

mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Jigar V. Desai ◽  
Vincent M. Bruno ◽  
Shantanu Ganguly ◽  
Ronald J. Stamper ◽  
Kaitlin F. Mitchell ◽  
...  
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Cell Surface ◽  
Biofilm Formation ◽  
Regulatory Role ◽  
Content Type ◽  
Upregulated Genes ◽  
Implanted Devices

ABSTRACTBiofilm formation byCandida albicanson medically implanted devices poses a significant clinical challenge. Here, we compared biofilm-associated gene expression in two clinicalC. albicansisolates, SC5314 and WO-1, to identify shared gene regulatory responses that may be functionally relevant. Among the 62 genes most highly expressed in biofilms relative to planktonic (suspension-grown) cells, we were able to recover insertion mutations in 25 genes. Twenty mutants had altered biofilm-related properties, including cell substrate adherence, cell-cell signaling, and azole susceptibility. We focused on one of the most highly upregulated genes in our biofilm proles,RHR2, which specifies the glycerol biosynthetic enzyme glycerol-3-phosphatase. Glycerol is 5-fold-more abundant in biofilm cells than in planktonic cells, and anrhr2Δ/Δ strain accumulates 2-fold-less biofilm glycerol than does the wild type. Underin vitroconditions, therhr2Δ/Δ mutant has reduced biofilm biomass and reduced adherence to silicone. Therhr2Δ/Δ mutant is also severely defective in biofilm formationin vivoin a rat catheter infection model. Expression profiling indicates that therhr2Δ/Δ mutant has reduced expression of cell surface adhesin genesALS1,ALS3, andHWP1, as well as many other biofilm-upregulated genes. Reduced adhesin expression may be the cause of therhr2Δ/Δ mutant biofilm defect, because overexpression ofALS1,ALS3, orHWP1restores biofilm formation ability to the mutantin vitroandin vivo. Our findings indicate that internal glycerol has a regulatory role in biofilm gene expression and that adhesin genes are among the main functional Rhr2-regulated genes.IMPORTANCECandida albicansis a major fungal pathogen, and infection can arise from the therapeutically intractable biofilms that it forms on medically implanted devices. It stands to reason that genes whose expression is induced during biofilm growth will function in the process, and our analysis of 25 such genes confirms that expectation. One gene is involved in synthesis of glycerol, a small metabolite that we find is abundant in biofilm cells. The impact of glycerol on biofilm formation is regulatory, not solely metabolic, because it is required for expression of numerous biofilm-associated genes. Restoration of expression of three of these genes that specify cell surface adhesins enables the glycerol-synthetic mutant to create a biofilm. Our findings emphasize the significance of metabolic pathways as therapeutic targets, because their disruption can have both physiological and regulatory consequences.

scholarly journals In VitroAnalyses of the Effects of Heparin and Parabens on Candida albicans Biofilms and Planktonic Cells

2011 ◽  
Vol 56 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Marisa H. Miceli ◽  
Stella M. Bernardo ◽  
T. S. Neil Ku ◽  
Carla Walraven ◽  
Samuel A. Lee
Keyword(s):  
Candida Albicans ◽  
Metabolic Activity ◽  
Biofilm Formation ◽  
High Dose ◽  
Dependent Manner ◽  
Planktonic Cells ◽  
Content Type ◽  
Heparin Sodium ◽  
The Individual

ABSTRACTInfections and thromboses are the most common complications associated with central venous catheters. Suggested strategies for prevention and management of these complications include the use of heparin-coated catheters, heparin locks, and antimicrobial lock therapy. However, the effects of heparin onCandida albicansbiofilms and planktonic cells have not been previously studied. Therefore, we sought to determine thein vitroeffect of a heparin sodium preparation (HP) on biofilms and planktonic cells ofC. albicans. Because HP contains two preservatives, methyl paraben (MP) and propyl paraben (PP), these compounds and heparin sodium without preservatives (Pure-H) were also tested individually. The metabolic activity of the mature biofilm after treatment was assessed using XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction and microscopy. Pure-H, MP, and PP caused up to 75, 85, and 60% reductions of metabolic activity of the mature preformedC. albicansbiofilms, respectively. Maximal efficacy against the mature biofilm was observed with HP (up to 90%) compared to the individual compounds (P< 0.0001). Pure-H, MP, and PP each inhibitedC. albicansbiofilm formation up to 90%. A complete inhibition of biofilm formation was observed with HP at 5,000 U/ml and higher. When tested against planktonic cells, each compound inhibited growth in a dose-dependent manner. These data indicated that HP, MP, PP, and Pure-H havein vitroantifungal activity againstC. albicansmature biofilms, formation of biofilms, and planktonic cells. Investigation of high-dose heparin-based strategies (e.g., heparin locks) in combination with traditional antifungal agents for the treatment and/or prevention ofC. albicansbiofilms is warranted.

scholarly journals Dectin-2-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Suresh Ambati ◽  
Emma C. Ellis ◽  
Jianfeng Lin ◽  
Xiaorong Lin ◽  
Zachary A. Lewis ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Aspergillus Fumigatus ◽  
Effective Dose ◽  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Antifungal Drugs ◽  
Extracellular Matrices ◽  
Content Type ◽  
Order Of Magnitude ◽  
Life Threatening

ABSTRACT Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus cause life-threatening candidiasis, cryptococcosis, and aspergillosis, resulting in several hundred thousand deaths annually. The patients at the greatest risk of developing these life-threatening invasive fungal infections have weakened immune systems. The vulnerable population is increasing due to rising numbers of immunocompromised individuals as a result of HIV infection or immunosuppressed individuals receiving anticancer therapies and/or stem cell or organ transplants. While patients are treated with antifungals such as amphotericin B, all antifungals have serious limitations due to lack of sufficient fungicidal effect and/or host toxicity. Even with treatment, 1-year survival rates are low. We explored methods of increasing drug effectiveness by designing fungicide-loaded liposomes specifically targeted to fungal cells. Most pathogenic fungi are encased in cell walls and exopolysaccharide matrices rich in mannans. Dectin-2 is a mammalian innate immune membrane receptor that binds as a dimer to mannans and signals fungal infection. We coated amphotericin-loaded liposomes with monomers of Dectin-2’s mannan-binding domain, sDectin-2. sDectin monomers were free to float in the lipid membrane and form dimers that bind mannan substrates. sDectin-2-coated liposomes bound orders of magnitude more efficiently to the extracellular matrices of several developmental stages of C. albicans, C. neoformans, and A. fumigatus than untargeted control liposomes. Dectin-2-coated amphotericin B-loaded liposomes reduced the growth and viability of all three species more than an order of magnitude more efficiently than untargeted control liposomes and dramatically decreased the effective dose. Future efforts focus on examining pan-antifungal targeted liposomal drugs in animal models of fungal diseases. IMPORTANCE Invasive fungal diseases caused by Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus have mortality rates ranging from 10 to 95%. Individual patient costs may exceed $100,000 in the United States. All antifungals in current use have serious limitations due to host toxicity and/or insufficient fungal cell killing that results in recurrent infections. Few new antifungal drugs have been introduced in the last 2 decades. Hence, there is a critical need for improved antifungal therapeutics. By targeting antifungal-loaded liposomes to α-mannans in the extracellular matrices secreted by these fungi, we dramatically reduced the effective dose of drug. Dectin-2-coated liposomes loaded with amphotericin B bound 50- to 150-fold more strongly to C. albicans, C. neoformans, and A. fumigatus than untargeted liposomes and killed these fungi more than an order of magnitude more efficiently. Targeting drug-loaded liposomes specifically to fungal cells has the potential to greatly enhance the efficacy of most antifungal drugs.

scholarly journals ZN148 Is a Modular Synthetic Metallo-β-Lactamase Inhibitor That Reverses Carbapenem Resistance in Gram-Negative Pathogens In Vivo

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Ørjan Samuelsen ◽  
Ove Alexander Høgmoen Åstrand ◽  
Christopher Fröhlich ◽  
Adam Heikal ◽  
Susann Skagseth ◽  
...  
Keyword(s):  
Active Site ◽  
Therapeutic Potential ◽  
Treatment Options ◽  
Carbapenem Resistance ◽  
Functional Space ◽  
Bactericidal Effect ◽  
Gram Negative ◽  
Content Type

ABSTRACT Carbapenem-resistant Gram-negative pathogens are a critical public health threat and there is an urgent need for new treatments. Carbapenemases (β-lactamases able to inactivate carbapenems) have been identified in both serine β-lactamase (SBL) and metallo-β-lactamase (MBL) families. The recent introduction of SBL carbapenemase inhibitors has provided alternative therapeutic options. Unfortunately, there are no approved inhibitors of MBL-mediated carbapenem-resistance and treatment options for infections caused by MBL-producing Gram-negatives are limited. Here, we present ZN148, a zinc-chelating MBL-inhibitor capable of restoring the bactericidal effect of meropenem and in vitro clinical susceptibility to carbapenems in >98% of a large international collection of MBL-producing clinical Enterobacterales strains (n = 234). Moreover, ZN148 was able to potentiate the effect of meropenem against NDM-1-producing Klebsiella pneumoniae in a murine neutropenic peritonitis model. ZN148 showed no inhibition of the human zinc-containing enzyme glyoxylase II at 500 μM, and no acute toxicity was observed in an in vivo mouse model with cumulative dosages up to 128 mg/kg. Biochemical analysis showed a time-dependent inhibition of MBLs by ZN148 and removal of zinc ions from the active site. Addition of exogenous zinc after ZN148 exposure only restored MBL activity by ∼30%, suggesting an irreversible mechanism of inhibition. Mass-spectrometry and molecular modeling indicated potential oxidation of the active site Cys221 residue. Overall, these results demonstrate the therapeutic potential of a ZN148-carbapenem combination against MBL-producing Gram-negative pathogens and that ZN148 is a highly promising MBL inhibitor that is capable of operating in a functional space not presently filled by any clinically approved compound.

scholarly journals The Novel Arylamidine T-2307 MaintainsIn VitroandIn VivoActivity against Echinocandin-Resistant Candida albicans

2014 ◽  
Vol 59 (2) ◽  
pp. 1341-1343 ◽  
Author(s):  
Nathan P. Wiederhold ◽  
Laura K. Najvar ◽  
Annette W. Fothergill ◽  
Rosie Bocanegra ◽  
Marcos Olivo ◽  
...  
Keyword(s):  
Body Weight ◽  
Candida Albicans ◽  
Invasive Candidiasis ◽  
Placebo Control ◽  
The Novel ◽  
Content Type ◽  
Fungal Burden ◽  
Potential Use

ABSTRACTWe evaluated thein vitroandin vivoactivities of the investigational arylamidine T-2307 against echinocandin-resistantCandida albicans. T-2307 demonstrated potentin vitroactivity, and daily subcutaneous doses between 0.75 and 6 mg/kg of body weight significantly improved survival and reduced fungal burden compared to placebo control and caspofungin (10 mg/kg/day) in mice with invasive candidiasis caused by an echinocandin-resistant strain. Thus, T-2307 may have potential use in the treatment of echinocandin-resistantC. albicansinfections.

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