scholarly journals Enterococcus faecalis Inhibits Hyphal Morphogenesis and Virulence of Candida albicans

2012 ◽  
Vol 81 (1) ◽  
pp. 189-200 ◽  
Author(s):  
Melissa R. Cruz ◽  
Carrie E. Graham ◽  
Bryce C. Gagliano ◽  
Michael C. Lorenz ◽  
Danielle A. Garsin
Keyword(s):  
Candida Albicans ◽  
Enterococcus Faecalis ◽  
Treatment Strategies ◽  
Content Type ◽  
Biologically Relevant ◽  
System A ◽  
Hyphal Morphogenesis ◽  
Negative Effect ◽  
Hyphal Formation

The Gram-positive bacteriumEnterococcus faecalisand the fungusCandida albicansare both found as commensals in many of the same niches of the human body, such as the oral cavity and gastrointestinal (GI) tract. However, both are opportunistic pathogens and have frequently been found to be coconstituents of polymicrobial infections. Despite these features in common, there has been little investigation into whether these microbes affect one another in a biologically significant manner. Using aCaenorhabditis elegansmodel of polymicrobial infection, we discovered thatE. faecalisandC. albicansnegatively impact each other's virulence. Much of the negative effect ofE. faecalisonC. albicanswas due to the inhibition ofC. albicanshyphal morphogenesis, a developmental program crucial toC. albicanspathogenicity. We discovered that the inhibition was partially dependent on the Fsr quorum-sensing system, a major regulator of virulence inE. faecalis. Specifically, two proteases regulated by Fsr, GelE and SerE, were partially required. Further characterization of the inhibitory signal revealed that it is secreted into the supernatant, is heat resistant, and is between 3 and 10 kDa. The substance was also shown to inhibitC. albicansfilamentation in the context of anin vitrobiofilm. Finally, a screen of anE. faecalistransposon mutant library identified other genes required for suppression ofC. albicanshyphal formation. Overall, we demonstrate a biologically relevant interaction between two clinically important microbes that could affect treatment strategies as well as impact our understanding of interkingdom signaling and sensing in the human-associated microbiome.

scholarly journals The Candida albicans ATO Gene Family Promotes Neutralization of the Macrophage Phagolysosome

2015 ◽  
Vol 83 (11) ◽  
pp. 4416-4426 ◽  
Author(s):  
Heather A. Danhof ◽  
Michael C. Lorenz
Keyword(s):  
Amino Acids ◽  
Candida Albicans ◽  
Hyphal Growth ◽  
Dominant Negative ◽  
Dependent Manner ◽  
Ph Change ◽  
Content Type ◽  
Ammonia Release ◽  
Hyphal Formation

ABSTRACTCandida albicansis an opportunistic human fungal pathogen that causes a variety of diseases, ranging from superficial mucosal to life-threatening systemic infections, the latter particularly in patients with defects in innate immune function.C. albicanscells phagocytosed by macrophages undergo a dramatic change in their metabolism in which amino acids are a key nutrient. We have shown that amino acid catabolism allows the cell to neutralize the phagolysosome and initiate hyphal growth. We show here that members of the 10-geneATOfamily, which are induced by phagocytosis or the presence of amino acids in an Stp2-dependent manner and encode putative acetate or ammonia transporters, are important effectors of this pH changein vitroand in macrophages. When grown with amino acids as the sole carbon source, the deletion ofATO5or the expression of a dominant-negativeATO1G53Dallele results in a delay in alkalinization, a defect in hyphal formation, and a reduction in the amount of ammonia released from the cell. These strains also form fewer hyphae after phagocytosis, have a reduced ability to escape macrophages, and reside in more acidic phagolysosomal compartments than wild-type cells. Furthermore, overexpression of many of the 10ATOgenes accelerates ammonia release, and anato5Δ ATO1G53Ddouble mutant strain has additive alkalinization and ammonia release defects. Taken together, these results indicate that the Ato protein family is a key mediator of the metabolic changes that allowC. albicansto overcome the macrophage innate immunity barrier.

scholarly journals Distinct Roles of Candida albicans Drug Resistance Transcription FactorsTAC1,MRR1, andUPC2in Virulence

2013 ◽  
Vol 13 (1) ◽  
pp. 127-142 ◽  
Author(s):  
Andrea Lohberger ◽  
Alix T. Coste ◽  
Dominique Sanglard
Keyword(s):  
Candida Albicans ◽  
Target Genes ◽  
Negative Impact ◽  
Antifungal Drugs ◽  
Wild Type ◽  
Drug Pressure ◽  
Content Type ◽  
Negative Effect

ABSTRACTAzoles are widely used in antifungal therapy in medicine. Resistance to azoles can occur inCandida albicansprincipally by overexpression of multidrug transporter geneCDR1,CDR2, orMDR1or by overexpression ofERG11, which encodes the azole target. The expression of these genes is controlled by the transcription factors (TFs)TAC1(involved in the control ofCDR1andCDR2),MRR1(involved in the control ofMDR1), andUPC2(involved in the control ofERG11). Several gain-of-function (GOF) mutations are present in hyperactive alleles of these TFs, resulting in the overexpression of target genes. While these mutations are beneficial toC. albicanssurvival in the presence of the antifungal drugs, their effects could potentially alter the fitness and virulence ofC. albicansin the absence of the selective drug pressure. In this work, the effect of GOF mutations onC. albicansvirulence was addressed in a systemic model of intravenous infection by mouse survival and kidney fungal burden assays. We engineered a set of strains with identical genetic backgrounds in which hyperactive alleles were reintroduced in one or two copies at their genomic loci. The results obtained showed that neitherTAC1norMRR1GOF mutations had a significant effect onC. albicansvirulence. In contrast, the presence of two hyperactiveUPC2alleles inC. albicansresulted in a significant decrease in virulence, correlating with diminished kidney colonization compared to that by the wild type. In agreement with the effect on virulence, the decreased fitness of an isolate withUPC2hyperactive alleles was observed in competition experiments with the wild typein vivobut notin vitro. Interestingly,UPC2hyperactivity delayed filamentation ofC. albicansafter phagocytosis by murine macrophages, which may at least partially explain the virulence defects. Combining theUPC2GOF mutation with another hyperactive TF did not compensate for the negative effect ofUPC2on virulence. In conclusion, among the major TFs involved in azole resistance, onlyUPC2had a negative impact on virulence and fitness, which may therefore have consequences for the epidemiology of antifungal resistance.

scholarly journals Phagosomal Neutralization by the Fungal Pathogen Candida albicans Induces Macrophage Pyroptosis

2016 ◽  
Vol 85 (2) ◽  
Author(s):  
Slavena Vylkova ◽  
Michael C. Lorenz
Keyword(s):  
Amino Acids ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Amino Acid ◽  
Content Type ◽  
Caspase 1 ◽  
Ammonia Release ◽  
Hyphal Morphogenesis

ABSTRACT The interaction of Candida albicans with the innate immune system is the key determinant of the pathogen/commensal balance and has selected for adaptations that facilitate the utilization of nutrients commonly found within the host, including proteins and amino acids; many of the catabolic pathways needed to assimilate these compounds are required for persistence in the host. We have shown that C. albicans co-opts amino acid catabolism to generate and excrete ammonia, which raises the extracellular pH, both in vitro and in vivo and induces hyphal morphogenesis. Mutants defective in the uptake or utilization of amino acids, such as those lacking STP2, a transcription factor that regulates the expression of amino acid permeases, are impaired in multiple aspects of fungus-macrophage interactions resulting from an inability to neutralize the phagosome. Here we identified a novel role in amino acid utilization for Ahr1p, a transcription factor previously implicated in regulation of adherence and hyphal morphogenesis. Mutants lacking AHR1 were defective in growth, alkalinization, and ammonia release on amino acid-rich media, similar to stp2Δ and ahr1Δ stp2Δ cells, and occupied more acidic phagosomes. Notably, ahr1Δ and stp2Δ strains did not induce pyroptosis, as measured by caspase-1-dependent interleukin-1β release, though this phenotype could be suppressed by pharmacological neutralization of the phagosome. Altogether, we show that C. albicans-driven neutralization of the phagosome promotes hyphal morphogenesis, sufficient for induction of caspase-1-mediated macrophage lysis.

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 From (p)ppGpp to (pp)pGpp: Characterization of Regulatory Effects of pGpp Synthesized by the Small Alarmone Synthetase of Enterococcus faecalis

2015 ◽  
Vol 197 (18) ◽  
pp. 2908-2919 ◽  
Author(s):  
Anthony O. Gaca ◽  
Pavel Kudrin ◽  
Cristina Colomer-Winter ◽  
Jelena Beljantseva ◽  
Kuanqing Liu ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Enterococcus Faecalis ◽  
Second Messengers ◽  
Stringent Response ◽  
Synthetase Activity ◽  
Protective Effects ◽  
Content Type ◽  
Regulatory Effects ◽  
Complex Target

ABSTRACTThe bacterial stringent response (SR) is a conserved stress tolerance mechanism that orchestrates physiological alterations to enhance cell survival. This response is mediated by the intracellular accumulation of the alarmones pppGpp and ppGpp, collectively called (p)ppGpp. InEnterococcus faecalis, (p)ppGpp metabolism is carried out by the bifunctional synthetase/hydrolaseE. faecalisRel (RelEf) and the small alarmone synthetase (SAS) RelQEf. Although Rel is the main enzyme responsible for SR activation inFirmicutes, there is emerging evidence that SASs can make important contributions to bacterial homeostasis. Here, we showed that RelQEfsynthesizes ppGpp more efficiently than pppGpp without the need for ribosomes, tRNA, or mRNA. In addition to (p)ppGpp synthesis from GDP and GTP, RelQEfalso efficiently utilized GMP to form GMP 3′-diphosphate (pGpp). Based on this observation, we sought to determine if pGpp exerts regulatory effects on cellular processes affected by (p)ppGpp. We found that pGpp, like (p)ppGpp, strongly inhibits the activity ofE. faecalisenzymes involved in GTP biosynthesis and, to a lesser extent, transcription ofrrnBbyEscherichia coliRNA polymerase. Activation ofE. coliRelA synthetase activity was observed in the presence of both pGpp and ppGpp, while RelQEfwas activated only by ppGpp. Furthermore, enzymatic activity of RelQEfis insensitive to relacin, a (p)ppGpp analog developed as an inhibitor of “long” RelA/SpoT homolog (RSH) enzymes. We conclude that pGpp can likely function as a bacterial alarmone with target-specific regulatory effects that are similar to what has been observed for (p)ppGpp.IMPORTANCEAccumulation of the nucleotide second messengers (p)ppGpp in bacteria is an important signal regulating genetic and physiological networks contributing to stress tolerance, antibiotic persistence, and virulence. Understanding the function and regulation of the enzymes involved in (p)ppGpp turnover is therefore critical for designing strategies to eliminate the protective effects of this molecule. While characterizing the (p)ppGpp synthetase RelQ ofEnterococcus faecalis(RelQEf), we found that, in addition to (p)ppGpp, RelQEfis an efficient producer of pGpp (GMP 3′-diphosphate).In vitroanalysis revealed that pGpp exerts complex, target-specific effects on processes known to be modulated by (p)ppGpp. These findings provide a new regulatory feature of RelQEfand suggest that pGpp may represent a new member of the (pp)pGpp family of alarmones.

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.

scholarly journals Antimicrobial Photodynamic Inactivation Inhibits Candida albicans Virulence Factors and ReducesIn VivoPathogenicity

2012 ◽  
Vol 57 (1) ◽  
pp. 445-451 ◽  
Author(s):  
Ilka Tiemy Kato ◽  
Renato Araujo Prates ◽  
Caetano Padial Sabino ◽  
Beth Burgwyn Fuchs ◽  
George P. Tegos ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Virulence Factors ◽  
Sodium Dodecyl ◽  
Systemic Infection ◽  
Tube Formation ◽  
Photodynamic Inactivation ◽  
Content Type ◽  
Daughter Cells

ABSTRACTThe objective of this study was to evaluate whetherCandida albicansexhibits altered pathogenicity characteristics following sublethal antimicrobial photodynamic inactivation (APDI) and if such alterations are maintained in the daughter cells.C. albicanswas exposed to sublethal APDI by using methylene blue (MB) as a photosensitizer (0.05 mM) combined with a GaAlAs diode laser (λ 660 nm, 75 mW/cm2, 9 to 27 J/cm2).In vitro, we evaluated APDI effects onC. albicansgrowth, germ tube formation, sensitivity to oxidative and osmotic stress, cell wall integrity, and fluconazole susceptibility.In vivo, we evaluatedC. albicanspathogenicity with a mouse model of systemic infection. Animal survival was evaluated daily. Sublethal MB-mediated APDI reduced the growth rate and the ability ofC. albicansto form germ tubes compared to untreated cells (P< 0.05). Survival of mice systemically infected withC. albicanspretreated with APDI was significantly increased compared to mice infected with untreated yeast (P< 0.05). APDI increasedC. albicanssensitivity to sodium dodecyl sulfate, caffeine, and hydrogen peroxide. The MIC for fluconazole forC. albicanswas also reduced following sublethal MB-mediated APDI. However, none of those pathogenic parameters was altered in daughter cells ofC. albicanssubmitted to APDI. These data suggest that APDI may inhibit virulence factors and reducein vivopathogenicity ofC. albicans. The absence of alterations in daughter cells indicates that APDI effects are transitory. The MIC reduction for fluconazole following APDI suggests that this antifungal could be combined with APDI to treatC. albicansinfections.

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