Conditions affecting the amphotericin B mediated inhibition of Candida albicans attachment to cell cultures

1989 ◽  
Vol 35 (2) ◽  
pp. 260-264 ◽  
Author(s):  
Glenn J. Merkel ◽  
Charles L. Phelps
Keyword(s):  
Candida Albicans ◽  
Amphotericin B ◽  
Mammalian Cell ◽  
Cell Cultures ◽  
Growth Phase ◽  
Mammalian Cells ◽  
Exponential Phase ◽  
Cell Interactions ◽  
Germ Tubes

Sublethal amounts of amphotericin B inhibited the attachment of Candida albicans to cultured mammalian cells. The extent of inhibition was influenced by the concentration of serum and the growth phase of the yeasts used to inoculate the cell cultures. Yeasts which were in their exponential phase of growth or had formed germ tubes were the most sensitive to amphotericin B. Equivalent amounts of amphotericin B inhibited yeast – mammalian cell interactions to different degrees depending upon the culture's tissue origin.Key words: Candida, amphotericin, polyenes, attachment, yeasts.

Effects of amphotericin B on glucose metabolism inCandida albicansblastospores evidenced by13C NMR

1996 ◽  
Vol 42 (7) ◽  
pp. 705-710 ◽  
Author(s):  
Françoise Rabaste ◽  
Martine Sancelme ◽  
Anne-Marie Delort
Keyword(s):  
Candida Albicans ◽  
Glucose Metabolism ◽  
Stationary Phase ◽  
Amphotericin B ◽  
Nmr Spectra ◽  
Exponential Phase ◽  
Yeast Suspension ◽  
C Nmr

Candida albicans blastospores harvested from 8- (exponential phase) or 48-h (stationary phase) cultures were incubated with 60 × 10−3 M [1-13C]glucose with or without 10−4 M amphotericin B (AmB). The utilization of [1-13C]glucose was monitored by in vivo13C NMR under anaerobiosis. With exponential phase cells, in the presence of AmB, the consumption of glucose and the production of ethanol, trehalose, and glycerol continuously decreased with time, and after 25 min, the metabolism was blocked. On stationary phase cells AmB had almost no effect on glucose metabolism. Comparison with previous experiments evidenced that AmB induced first K+leakage, then acidification, and finally a stop of the metabolism. In parallel, in vitro13C NMR spectra were performed on supernatants and cell-free extracts of yeast suspension incubated under the same conditions. For both exponential and stationary phase cells, AmB induced an increase in the membrane permeability to glycerol; no change was observed for the other metabolites.Key words: Candida albicans,13C NMR, amphotericin B, glucose metabolism, glycerol.

scholarly journals Network rewiring: physiological consequences of reciprocally exchanging the physical locations and growth-phase-dependent expression patterns of the Salmonella fis and dps genes

2020 ◽  
Author(s):  
Marina M Bogue ◽  
Aalap Mogre ◽  
Michael C Beckett ◽  
Nicholas R Thomson ◽  
Charles J Dorman
Keyword(s):  
Gene Expression ◽  
Protein Binding ◽  
Stationary Phase ◽  
Growth Phase ◽  
Regulatory Network ◽  
Mammalian Cells ◽  
Expression Patterns ◽  
Virulence Gene ◽  
Exponential Phase ◽  
Virulence Gene Expression

ABSTRACTThe Fis nucleoid-associated protein controls the expression of a large and diverse regulon of genes in Gram-negative bacteria. Fis production is normally maximal in bacteria during the early exponential phase of batch culture growth, becoming almost undetectable by the onset of stationary phase. We tested the effect on the Fis regulatory network in Salmonella of moving the complete fis gene from its usual location near the origin of chromosomal replication to the position normally occupied by the dps gene in the Right macrodomain of the chromosome, and vice versa, creating the strain GX. In a parallel experiment, we tested the effect of rewiring the Fis regulatory network by placing the fis open reading frame under the control of the stationary-phase-activated dps promoter at the dps genetic location within Ter, and vice versa, creating the strain OX. ChIP-seq was used to measure global Fis protein binding and gene expression patterns. Strain GX showed few changes when compared with the wild type, although we did detect increased Fis binding at Ter, accompanied by reduced binding at Ori. Strain OX displayed a more pronounced version of this distorted Fis protein-binding pattern together with numerous alterations in the expression of genes in the Fis regulon. OX, but not GX, had a reduced ability to infect cultured mammalian cells. These findings illustrate the inherent robustness of the Fis regulatory network to rewiring based on gene repositioning alone and emphasise the importance of fis expression signals in phenotypic determination.IMPORTANCEWe assessed the impacts on Salmonella physiology of reciprocally translocating the genes encoding the Fis and Dps nucleoid-associated proteins (NAPs), and of inverting their growth phase production patterns such that Fis is produced in stationary phase (like Dps) and Dps is produced in exponential phase (like Fis). Changes to peak binding of Fis were detected by ChIP-seq on the chromosome, as were widespread impacts on the transcriptome, especially when Fis production mimicked Dps. Virulence gene expression and the expression of a virulence phenotype were altered. Overall, these radical changes to NAP gene expression were well tolerated, revealing the robust and well-buffered nature of global gene regulation networks in the bacterium.

scholarly journals Local delivery polymer provides sustained antifungal activity of amphotericin B with reduced cytotoxicity

2019 ◽  
Vol 244 (6) ◽  
pp. 526-533 ◽  
Author(s):  
Rebecca M Haley ◽  
Sean T Zuckerman ◽  
Catherine A Gormley ◽  
Julius N Korley ◽  
Horst A von Recum
Keyword(s):  
Antifungal Activity ◽  
Side Effects ◽  
Amphotericin B ◽  
Mammalian Cell ◽  
Mammalian Cells ◽  
Fungal Infections ◽  
Mammalian Cell Culture ◽  
Local Delivery ◽  
Host Cells ◽  
Diverse Range

A diverse range of clinical infections are on the increase, resulting in part from disruption of the natural microbiome, or even mycobiome, as a result of many different medical interventions. Amphotericin B (AmB) is a leading drug for the treatment of clinical fungal infections. However, AmB is extremely cytotoxic to mammalian cells, making use of the drug problematic. In this work, a drug delivery system made of polymerized cyclodextrin (pCD) allows for the localized administration of AmB, reducing the toxicity to host cells while retaining antifungal activity. A slow, sustained delivery rate of AmB was achieved through exploiting molecular interactions between the CD pockets and the drug. Surface plasmon resonance (SPR) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the interaction between AmB and cyclodextrins (CDs). Through these methods, it was found that amphotericin binds strongly ([Formula: see text]M−1) to β-cyclodextrin. Release studies showed slow, sustained release of AmB from pCD disks. Antifungal activity was tested against Saccharomyces cerevisiae in assays for zone of inhibition, contact killing, and solution killing. In all assays, AmB-loaded pCD disks were found to exhibit significant antifungal activity. These results indicate that AmB-loaded pCD disks are capable of both the prevention of fungal growth and the elimination of established colonies. Additionally, results suggest that AmB exhibits antifungal activity whether associated with or released from pCD. The usage of pCD as a delivery vehicle also significantly reduces the toxic side effects of AmB, as seen in mammalian cell culture studies. These results show that in addition to reducing side-effects from systemic dosing, local delivery of AmB from pCD disks has the potential to improve its usage both in antifungal efficacy and reduced mammalian cell toxicity. Impact statement Amphotericin B (AmB) is an effective and commonly used antifungal agent. However, nephrotoxicity and poor solubility limits its usage. The proposed polymerized cyclodextrin (pCD) system therefore is an attractive method for AmB delivery, as it retains the antifungal activity of AmB while decreasing toxicity, and confining drug release to the local environment. This system could potentially be used for both prevention and treatment of established fungal infections, as AmB is toxic to fungus whether associated or released from pCD.

Antifungal Activity Directed Toward the Cell Wall by 2-Cyclohexylidenhydrazo- 4-Phenyl-Thiazole Against Candida albicans

2019 ◽  
Vol 19 (4) ◽  
pp. 428-438 ◽  
Author(s):  
Nívea P. de Sá ◽  
Ana P. Pôssa ◽  
Pilar Perez ◽  
Jaqueline M.S. Ferreira ◽  
Nayara C. Fonseca ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Antifungal Activity ◽  
Mammalian Cells ◽  
C Elegans ◽  
Buccal Epithelial Cells ◽  
Mutant Strains ◽  
Low Toxicity ◽  
High Concentrations ◽  
Mic Value

<p>Background: The increasing incidence of invasive forms of candidiasis and resistance to antifungal therapy leads us to seek new and more effective antifungal compounds. </P><P> Objective: To investigate the antifungal activity and toxicity as well as to evaluate the potential targets of 2- cyclohexylidenhydrazo-4-phenyl-thiazole (CPT) in Candida albicans. </P><P> Methods: The antifungal activity of CPT against the survival of C. albicans was investigated in Caenorhabditis elegans. Additionally, we determined the effect of CPT on the inhibition of C. albicans adhesion capacity to buccal epithelial cells (BECs), the toxicity of CPT in mammalian cells, and the potential targets of CPT in C. albicans. </P><P> Results: CPT exhibited a minimum inhibitory concentration (MIC) value of 0.4-1.9 µg/mL. Furthermore, CPT at high concentrations (>60 x MIC) showed no or low toxicity in HepG2 cells and <1% haemolysis in human erythrocytes. In addition, CPT decreased the adhesion capacity of yeasts to the BECs and prolonged the survival of C. elegans infected with C. albicans. Analysis of CPT-treated cells showed that their cell wall was thinner than that of untreated cells, especially the glucan layer. We found that there was a significantly lower quantity of 1,3-β-D-glucan present in CPT-treated cells than that in untreated cells. Assays performed on several mutant strains showed that the MIC value of CPT was high for its antifungal activity on yeasts with defective 1,3-β-glucan synthase. </P><P> Conclusion: In conclusion, CPT appears to target the cell wall of C. albicans, exhibits low toxicity in mammalian cells, and prolongs the survival of C. elegans infected with C. albicans.</p>

scholarly journals Sublethal Injury and Resuscitation of Candida albicans after Amphotericin B Treatment

2003 ◽  
Vol 47 (4) ◽  
pp. 1200-1206 ◽  
Author(s):  
Robert S. Liao ◽  
Robert P. Rennie ◽  
James A. Talbot
Keyword(s):  
Cell Death ◽  
Candida Albicans ◽  
Amphotericin B ◽  
Antifungal Agents ◽  
Sybr Green ◽  
Sequential Treatment ◽  
Tetrazolium Salt ◽  
Fungal Cell ◽  
Sublethal Injury

ABSTRACT Amphotericin B treatment was previously shown to inhibit Candida albicans reproduction and reduce the fluorescence of vitality-specific dyes without causing a corresponding increase in the fluorescence of the mortality-specific dyes bis-(1,3-dibutylbarbituric acid)trimethine oxonol and SYBR Green Ι. In the present study, we have confirmed these results and have shown that the numbers of CFU are reduced by 99.9% by treatment with 0.5 μg of amphotericin B per ml for 10 h at 35°C. This reduction was not due to fungal cell death. First, the level of reduction of the tetrazolium salt 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide increased in the presence of concentrations of amphotericin B that caused greater than 90% reductions in the numbers of CFU. Second, fungal cells treated with amphotericin B at a concentration of 0.5 μg/ml were resuscitated by further incubation at 22°C for 15 h in the continued presence of amphotericin B. Third, recovery of the ability to replicate was prevented by sequential treatment with 20 μg of miconazole per ml, which also increased the fluorescence of mortality-specific dyes to near the maximal levels achieved with 0.9 μg of amphotericin B per ml. Sequential treatment with fluconazole and flucytosine did not increase the levels of staining with the mortality-specific dyes. Itraconazole was less effective than ketoconazole, which was less effective than miconazole. The practice of equating the loss of the capacity of C. albicans to form colonies with fungal cell death may give incorrect results in assays with amphotericin B, and the results of assays with caution with other antifungal agents that are lipophilic or that possess significant postantifungal effects may need to be interpreted.

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 Bioactive Coatings with Ag-Camphorimine Complexes to Prevent Surface Colonization by the Pathogenic Yeast Candida albicans

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 638
Author(s):  
M. Joana F. Pinheiro ◽  
Joana P. Costa ◽  
Fernanda Marques ◽  
Nuno P. Mira ◽  
M. Fernanda N. N. Carvalho ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Medical Devices ◽  
Mammalian Cells ◽  
Surface Engineering ◽  
Pathogenic Yeast ◽  
Bioactive Coatings ◽  
Clinical Strains ◽  
Persistent Infections ◽  
Compound Q ◽  
Significant Step

Currently there is a gap between the rate of new antifungal development and the emergence of resistance among Candida clinical strains, particularly threatened by the extreme adhesiveness of C. albicans to indwelling medical devices. Two silver camphorimine complexes, [Ag(OH){OC10H14N(C6H4)2NC10H14O}] (compound P) and [{Ag(OC10H14NC6H4CH3-p)}2(μ-O)] (compound Q), are herein demonstrated as having high inhibiting activity towards the growth of Candida albicans and Candida glabrata clinical strains resistant to azoles, the frontline antifungals used in clinical practice. Compounds P and Q were also explored as bioactive coatings to prevent colonization by C. albicans and colonize the surface of indwelling medical devices, resulting in persistent infections. Functionalization of stainless steel with polycaprolactone (PCL) matrix embedded with compounds P or Q was reported for the first time to inhibit the colonization of C. albicans by 82% and 75%, respectively. The coating of PCL loaded with Q or P did not cause cytotoxic effects in mammalian cells, demonstrating the biocompatibility of the explored approach. The identification and further exploration of new approaches for surface engineering based on new molecules that can sensitize resistant strains, as herein demonstrated for complexes P and Q, is a significant step forward to improve the successful treatment of candidiasis.

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