New Insight into Amphotericin B Resistance in Aspergillus terreus

ABSTRACTAmphotericin B (AMB) is the predominant antifungal drug, but the mechanism of resistance is not well understood. We compared thein vivovirulence of an AMB-resistantAspergillus terreus(ATR) isolate with that of an AMB-susceptibleA. terreusisolate (ATS) using a murine model for disseminated aspergillosis. Furthermore, we analyzed the molecular basis of intrinsic AMB resistancein vitroby comparing the ergosterol content, cell-associated AMB levels, AMB-induced intracellular efflux, and prooxidant effects between ATR and ATS. Infection of immunosuppressed mice with ATS or ATR showed that the ATS strain was more lethal than the ATR strain. However, AMB treatment improved the outcome in ATS-infected mice while having no positive effect on the animals infected with ATR. Thein vitrodata demonstrated that ergosterol content is not the molecular basis for AMB resistance. ATR absorbed less AMB, discharged more intracellular compounds, and had better protection against oxidative damage than the susceptible strain. Our experiments showed that ergosterol content plays a minor role in intrinsic AMB resistance and is not directly associated with intracellular cell-associated AMB content. AMB might exert its antifungal activity by oxidative injury rather than by an increase in membrane permeation.

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Surface-Engineered Dendrimeric Nanoconjugates for Macrophage-Targeted Delivery of Amphotericin B: Formulation Development andIn VitroandIn VivoEvaluation

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04213-14 ◽

2015 ◽

Vol 59 (5) ◽

pp. 2479-2487 ◽

Cited By ~ 40

Author(s):

Keerti Jain ◽

Ashwni Kumar Verma ◽

Prabhat Ranjan Mishra ◽

Narendra Kumar Jain

Keyword(s):

Drug Release ◽

Amphotericin B ◽

Human Erythrocytes ◽

Antileishmanial Activity ◽

Cell Uptake ◽

Antiparasitic Activity ◽

Content Type ◽

Drug Localization

ABSTRACTThe present study aimed to develop an optimized dendrimeric delivery system for amphotericin B (AmB). Fifth-generation (5.0G) poly(propylene imine) (PPI) dendrimers were synthesized, conjugated with mannose, and characterized by use of various analytical techniques, including Fourier transform infrared spectroscopy (FTIR),1H nuclear magnetic resonance (1H-NMR) spectroscopic analysis, and atomic force microscopy (AFM). Mannose-conjugated 5.0G PPI (MPPI) dendrimers were loaded with AmB and evaluated for drug loading efficiency,in vitrodrug release profile, stability, hemolytic toxicity to human erythrocytes, cytotoxicity to and cell uptake by J774A.1 macrophage cells, antiparasitic activity against intracellularLeishmania donovaniamastigotes,in vivopharmacokinetic and biodistribution profiles, drug localization index, toxicity, and antileishmanial activity. AFM showed the nanometric size of the MPPI dendrimers, with a nearly globular architecture. The conjugate showed a good entrapment efficiency for AmB, along with pH-sensitive drug release. Highly significant reductions in toxicity toward human erythrocytes and macrophage cells, without compromising the antiparasitic activity of AmB, were observed. The dendrimeric formulation of AmB showed a significant enhancement of the parasiticidal activity of AmB toward intramacrophagicL. donovaniamastigotes. In thein vitrocell uptake studies, the formulation showed selectivity toward macrophages, with significant intracellular uptake. Further pharmacokinetic and organ distribution studies elucidated the controlled delivery behavior of the formulation. The drug localization index was found to increase significantly in macrophage-rich organs.In vivostudies showed a biocompatible behavior of MPPIA, with negligible toxicity even at higher doses, and promising antileishmanial activity. From the results, we concluded that surface-engineered dendrimers may serve as optimized delivery vehicles for AmB with enhanced activity and low or negligible toxicity.

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New Triazole NT-a9 Has Potent Antifungal Efficacy against Cryptococcus neoformans In Vitro and In Vivo

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01628-19 ◽

2019 ◽

Vol 64 (2) ◽

Cited By ~ 1

Author(s):

Ren-Yi Lu ◽

Ting-Jun-Hong Ni ◽

Jing Wu ◽

Lan Yan ◽

Quan-Zhen Lv ◽

...

Keyword(s):

Cryptococcus Neoformans ◽

Amphotericin B ◽

Pathogenic Fungi ◽

Control Group ◽

Survival Times ◽

Content Type ◽

Fungal Burden ◽

Wide Range

ABSTRACT In the past decades, the incidence of cryptococcosis has increased dramatically, which poses a new threat to human health. However, only a few drugs are available for the treatment of cryptococcosis. Here, we described a leading compound, NT-a9, an analogue of isavuconazole, that showed strong antifungal activities in vitro and in vivo. NT-a9 showed a wide range of activities against several pathogenic fungi in vitro, including Cryptococcus neoformans, Cryptococcus gattii, Candida albicans, Candida krusei, Candida tropicalis, Candida glabrata, and Candida parapsilosis, with MICs ranging from 0.002 to 1 μg/ml. In particular, NT-a9 exhibited excellent efficacy against C. neoformans, with a MIC as low as 0.002 μg/ml. NT-a9 treatment resulted in changes in the sterol contents in C. neoformans, similarly to fluconazole. In addition, NT-a9 possessed relatively low cytotoxicity and a high selectivity index. The in vivo efficacy of NT-a9 was assessed using a murine disseminated-cryptococcosis model. Mice were infected intravenously with 1.8 × 106 CFU of C. neoformans strain H99. In the survival study, NT-a9 significantly prolonged the survival times of mice compared with the survival times of the control group or the isavuconazole-, fluconazole-, or amphotericin B-treated groups. Of note, 4 and 8 mg/kg of body weight of NT-a9 rescued all the mice, with a survival rate of 100%. In the fungal-burden study, NT-a9 also significantly reduced the fungal burdens in brains and lungs, while fluconazole and amphotericin B only reduced the fungal burden in lungs. Taken together, these data suggested that NT-a9 is a promising antifungal candidate for the treatment of cryptococcosis infection.

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In Vitro and In Vivo Biology of Recombinant Adenovirus Vectors with E1, E1/E2A, or E1/E4 Deleted

Journal of Virology ◽

10.1128/jvi.72.3.2022-2032.1998 ◽

1998 ◽

Vol 72 (3) ◽

pp. 2022-2032 ◽

Cited By ~ 170

Author(s):

M. Lusky ◽

M. Christ ◽

K. Rittner ◽

A. Dieterle ◽

D. Dreyer ◽

...

Keyword(s):

Recombinant Adenovirus ◽

Virus Genome ◽

Minor Role ◽

Immunodeficient Mice ◽

Viral Genomes ◽

Viral Genes ◽

Adenovirus Vectors ◽

A Minor

ABSTRACT Isogenic, E3-deleted adenovirus vectors defective in E1, E1 and E2A, or E1 and E4 were generated in complementation cell lines expressing E1, E1 and E2A, or E1 and E4 and characterized in vitro and in vivo. In the absence of complementation, deletion of both E1 and E2A completely abolished expression of early and late viral genes, while deletion of E1 and E4 impaired expression of viral genes, although at a lower level than the E1/E2A deletion. The in vivo persistence of these three types of vectors was monitored in selected strains of mice with viral genomes devoid of transgenes to exclude any interference by immunogenic transgene-encoded products. Our studies showed no significant differences among the vectors in the short-term maintenance and long-term (4-month) persistence of viral DNA in liver and lung cells of immunocompetent and immunodeficient mice. Furthermore, all vectors induced similar antibody responses and comparable levels of adenovirus-specific cytotoxic T lymphocytes. These results suggest that in the absence of transgenes, the progressive deletion of the adenovirus genome does not extend the in vivo persistence of the transduced cells and does not reduce the antivirus immune response. In addition, our data confirm that, in the absence of transgene expression, mouse cellular immunity to viral antigens plays a minor role in the progressive elimination of the virus genome.

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In Vitro Evaluation of Radiolabeled Amphotericin B for Molecular Imaging of Mold Infections

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02377-19 ◽

2020 ◽

Vol 64 (7) ◽

Cited By ~ 1

Author(s):

Lukas Page ◽

Andrew J. Ullmann ◽

Fabian Schadt ◽

Sebastian Wurster ◽

Samuel Samnick

Keyword(s):

Molecular Imaging ◽

Amphotericin B ◽

Invasive Pulmonary Aspergillosis ◽

Nuclear Imaging ◽

Molecular Probes ◽

Content Type ◽

Diagnostic Potential ◽

Gallium 68

ABSTRACT Invasive pulmonary aspergillosis and mucormycosis are life-threatening complications in immunocompromised patients. A rapid diagnosis followed by early antifungal treatment is essential for patient survival. Given the limited spectrum of biomarkers for invasive mold infections, recent studies have proposed the use of radiolabeled siderophores or antibodies as molecular probes to increase the specificity of radiological findings by nuclear imaging modalities. While holding enormous diagnostic potential, most of the currently available molecular probes are tailored to the detection of Aspergillus species, and their cost-intensive and sophisticated implementation restricts their accessibility at less specialized centers. In order to develop cost-efficient and broadly applicable tracers for pulmonary mold infections, this study established streamlined and high-yielding protocols to radiolabel amphotericin B (AMB) with the gamma emitter technetium-99m (99mTc-AMB) and the positron emitter gallium-68 (68Ga-AMB). The radiochemical purity of the resulting tracers consistently exceeded 99%, and both probes displayed excellent stability in human serum (>98% after 60 to 240 min at 37°C). The uptake kinetics by representative mold pathogens were assessed in an in vitro Transwell assay using infected endothelial cell layers. Both tracers accumulated intensively and specifically in Transwell inserts infected with Aspergillus fumigatus, Rhizopus arrhizus, and other clinically relevant mold pathogens compared with their accumulation in uninfected inserts and inserts infected with bacterial controls. Inoculum-dependent enrichment was confirmed by gamma counting and autoradiographic imaging. Taken together, this pilot in vitro study proposes 99mTc-AMB and 68Ga-AMB to be facile, stable, and specific probes, meriting further preclinical in vivo evaluation of radiolabeled amphotericin B for molecular imaging in invasive mycoses.

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In VitroCombination of Isavuconazole with Micafungin or Amphotericin B Deoxycholate against Medically Important Molds

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03261-14 ◽

2014 ◽

Vol 58 (11) ◽

pp. 6934-6937 ◽

Cited By ~ 25

Author(s):

Aspasia Katragkou ◽

Matthew McCarthy ◽

Joseph Meletiadis ◽

Vidmantas Petraitis ◽

Patriss W. Moradi ◽

...

Keyword(s):

Combination Therapy ◽

Invasive Aspergillosis ◽

Amphotericin B ◽

Aspergillus Flavus ◽

Aspergillus Terreus ◽

Synergistic Activity ◽

Content Type ◽

Amphotericin B Deoxycholate ◽

Combination Studies

ABSTRACTWhether isavuconazole, an extended-spectrum triazole, possesses synergistic activity in combination therapy with echinocandins or amphotericin B for the treatment of invasive molds infections has not been studied. Ourin vitrocombination studies showed that isavuconazole and micafungin are synergistically active againstAspergillus fumigatus,Aspergillus flavus,Aspergillus terreus, andCunninghamella bertholletiae. These results suggest that isavuconazole, in combination with micafungin, may have a role in the treatment of invasive aspergillosis and warrants further investigation.

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Endothelial nitric oxide synthase plays a minor role in inhibition of arterial thrombus formation

Thrombosis and Haemostasis ◽

10.1160/th03-09-0588 ◽

2005 ◽

Vol 93 (06) ◽

pp. 1161-1167 ◽

Cited By ~ 50

Author(s):

Burcin Özüyaman ◽

Susanne Küsters ◽

Elisabeth Kirchhoff ◽

Rüdiger Scharf ◽

Jürgen Schrader ◽

...

Keyword(s):

Platelet Aggregation ◽

Thrombus Formation ◽

Surface Expression ◽

No Synthase ◽

Minor Role ◽

Endothelial No Synthase ◽

Tail Tip ◽

A Minor

SummaryEndothelial NO synthase (eNOS) expressed in the vascular en-dothelium or formed within platelets was postulated to inhibit platelet activation and aggregation. We have assessed the role of eNOS in platelet aggregation in vitro and in vivo by comparison of WT and eNOS-/- mice. Aggregometer studies revealed that collagen over a concentration range of 0.36–10 µg aggregated WT and eNOS-/- platelets to the same extent (10 µg: WT 86.7±4.7%, eNOS-/- 91±12%, n=6). Collagen treatment did not result in a significant increase in cGMP formation and VASP phosphorylation. Thrombin-induced P-selectin surface expression was unchanged in eNOS-/- platelets. In line with these findings no eNOS protein was detectable within the platelets of WT mice. In vivo, bleeding time after tail tip resection tended to be shorter in eNOS/- mice (WT: 116±35 s; eNOS-/- 109±37 s, n.s). Similarly, time to occlusion of the A.carotis after focal induction of thrombosis was 501±76 s (WT) and 457±95 s (eNOS-/-) (n.s.). These data demonstrate that eNOS-deficiency minimally affects platelet aggregation and is not associated with accelerated arterial thrombosis in vivo. Thus, in the mouse endothelial NO synthase does not play a major role in the autocrine modulation of platelet function and in thrombosis of conduit vessels in vivo.

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Investigation of the Efficacy of Micafungin in the Treatment of Histoplasmosis Using Two North American Strains of Histoplasma capsulatum

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01681-10 ◽

2011 ◽

Vol 55 (9) ◽

pp. 4447-4450 ◽

Cited By ~ 15

Author(s):

Chadi A. Hage ◽

Patricia Connolly ◽

Daniel Horan ◽

Michelle Durkin ◽

Melinda Smedema ◽

...

Keyword(s):

Amphotericin B ◽

North American ◽

Liposomal Amphotericin ◽

Histoplasma Capsulatum ◽

Liposomal Amphotericin B ◽

Content Type ◽

Yeast Form

ABSTRACTMicafungin alone and combined with liposomal amphotericin B was evaluated against two strains ofHistoplasma capsulatum. Micafungin was activein vitroagainst the mold but not the yeast form but was ineffectivein vivo. Micafungin appears to be ineffective in treatment of histoplasmosis.

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Amphotericin B- and Voriconazole-Echinocandin Combinations against Aspergillus spp.: Effect of Serum on Inhibitory and Fungicidal Interactions

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00597-13 ◽

2013 ◽

Vol 57 (10) ◽

pp. 4656-4663 ◽

Cited By ~ 21

Author(s):

Antigoni Elefanti ◽

Johan W. Mouton ◽

Paul E. Verweij ◽

Athanassios Tsakris ◽

Loukia Zerva ◽

...

Keyword(s):

Amphotericin B ◽

Colorimetric Method ◽

Antifungal Drugs ◽

Content Type ◽

Synergistic Interactions ◽

Inhibitory Activities ◽

Additive Interactions ◽

Species Specific

ABSTRACTAntifungal combination therapy with voriconazole or amphotericin B and an echinocandin is often employed as primary or salvage therapy for management particularly of refractory aspergillosis. The pharmacodynamic interactions of amphotericin B- and voriconazole-based combinations with the three echinocandins caspofungin, micafungin, and anidulafungin in the presence of serum were tested against 15Aspergillus fumigatuscomplex,A. flavuscomplex, andA. terreuscomplex isolates to assess both their growth-inhibitory and fungicidal activities. Thein vitroactivity of each drug alone and in combination at a 1:1 fixed concentration ratio was tested with a broth microdilution colorimetric method, and interactions were assessed by isobolographic analysis. Synergy was found for all amphotericin B- and voriconazole-based combinations, with amphotericin B-based combinations showing strong inhibitory synergistic interactions (interaction indices of 0.20 to 0.52) and with voriconazole-based combinations demonstrating strong fungicidal synergistic interactions (interaction indices of 0.10 to 0.29) (P< 0.001). Drug- and species-specific differences were found, with caspofungin and theA. fumigatuscomplex exhibiting the weakest synergistic interactions. In the presence of serum, the synergistic interactions were reduced in the order (from largest to smallest decrease) micafungin > anidulafungin > caspofungin, andA. flavuscomplex >A. fumigatuscomplex >A. terreuscomplex, resulting in additive interactions, particularly for inhibitory activities of amphotericin B-echinocandin combinations and fungicidal activities of voriconazole-echinocandin combinations. Drug- and species-specific differences were found in the presence of serum for inhibitory activities of antifungal drugs, with the lowest interaction indices being observed for amphotericin B-caspofungin (median, 0.77) and for theA. terreuscomplex (median, 0.56). The presentin vitrodata showed that serum had a major impact on synergistic interactions of amphotericin B-echinocandin and voriconazole-echinocandin combinations, resulting in additive interactions and explaining the indifferent outcomes usually observedin vivo.

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Dynamic Interaction between Fluconazole and Amphotericin B against Cryptococcus gattii

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.06098-11 ◽

2012 ◽

Vol 56 (5) ◽

pp. 2553-2558 ◽

Cited By ~ 29

Author(s):

Julliana Ribeiro Alves Santos ◽

Ludmila Ferreira Gouveia ◽

Erika Linzi Silva Taylor ◽

Maria Aparecida Resende-Stoianoff ◽

Gerson Antônio Pianetti ◽

...

Keyword(s):

Amphotericin B ◽

Cryptococcus Gattii ◽

Content Type ◽

Antagonistic Interaction ◽

Ergosterol Content ◽

Kill Curve ◽

Time Kill ◽

Postantifungal Effect

ABSTRACTCryptococcus gattiiis the main pathogen of cryptococcosis in healthy patients and is treated mainly with fluconazole and amphotericin B. The combination of these drugs has been questioned because the mechanisms of action could lead to a theoretical antagonistic interaction. We evaluated distinct parameters involved in thein vitrocombination of fluconazole and amphotericin B againstCryptococcus gattii. Fourteen strains ofC. gattiiwere used for the determination of MIC, fractional inhibitory concentration, time-kill curve, and postantifungal effect (PAFE). Ergosterol quantification was performed to evaluate the influence of ergosterol content on the interaction between these antifungals. Interaction between the drugs varied from synergistic to antagonistic depending on the strain and concentration tested. Increasing fluconazole levels were correlated with an antagonistic interaction. A total of 48 h was necessary for reducing the fungal viability in the presence of fluconazole, while 12 h were required for amphotericin B. When these antifungals were tested in combination, fluconazole impaired the amphotericin B activity. The ergosterol content decreased with the increase of fluconazole levels and it was correlated with the lower activity of amphotericin B. The PAFE found varied from 1 to 4 h for fluconazole and from 1 to 3 h for amphotericin B. The interaction of fluconazole and amphotericin B was concentration-dependent and special attention should be directed when these drugs are used in combination againstC. gattii.

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Estrogen Receptor Antagonists Are Anti-Cryptococcal Agents That Directly Bind EF Hand Proteins and Synergize with Fluconazole In Vivo

mBio ◽

10.1128/mbio.00765-13 ◽

2014 ◽

Vol 5 (1) ◽

Cited By ~ 58

Author(s):

Arielle Butts ◽

Kristy Koselny ◽

Yeissa Chabrier-Roselló ◽

Camile P. Semighini ◽

Jessica C. S. Brown ◽

...

Keyword(s):

Breast Cancer ◽

Estrogen Receptor ◽

Amphotericin B ◽

Receptor Antagonists ◽

Content Type ◽

New Therapies ◽

Ef Hand ◽

Estrogen Receptor Antagonists

ABSTRACT Cryptococcosis is an infectious disease of global significance for which new therapies are needed. Repurposing previously developed drugs for new indications can expedite the translation of new therapies from bench to beside. Here, we characterized the anti-cryptococcal activity and antifungal mechanism of estrogen receptor antagonists related to the breast cancer drugs tamoxifen and toremifene. Tamoxifen and toremifene are fungicidal and synergize with fluconazole and amphotericin B in vitro. In a mouse model of disseminated cryptococcosis, tamoxifen at concentrations achievable in humans combines with fluconazole to decrease brain burden by ~1 log10. In addition, these drugs inhibit the growth of Cryptococcus neoformans within macrophages, a niche not accessible by current antifungal drugs. Toremifene and tamoxifen directly bind to the essential EF hand protein calmodulin, as determined by thermal shift assays with purified C. neoformans calmodulin (Cam1), prevent Cam1 from binding to its well-characterized substrate calcineurin (Cna1), and block Cna1 activation. In whole cells, toremifene and tamoxifen block the calcineurin-dependent nuclear localization of the transcription factor Crz1. A large-scale chemical genetic screen with a library of C. neoformans deletion mutants identified a second EF hand-containing protein, which we have named calmodulin-like protein 1 (CNAG_05655), as a potential target, and further analysis showed that toremifene directly binds Cml1 and modulates its ability to bind and activate Cna1. Importantly, tamoxifen analogs (idoxifene and methylene-idoxifene) with increased calmodulin antagonism display improved anti-cryptococcal activity, indicating that calmodulin inhibition can be used to guide a systematic optimization of the anti-cryptococcal activity of the triphenylethylene scaffold. IMPORTANCE Worldwide, cryptococcosis affects approximately 1 million people annually and kills more HIV/AIDS patients per year than tuberculosis. The gold standard therapy for cryptococcosis is amphotericin B plus 5-flucytosine, but this regimen is not readily available in regions where resources are limited and where the burden of disease is highest. Herein, we show that molecules related to the breast cancer drug tamoxifen are fungicidal for Cryptococcus and display a number of pharmacological properties desirable for an anti-cryptococcal drug, including synergistic fungicidal activity with fluconazole in vitro and in vivo, oral bioavailability, and activity within macrophages. We have also demonstrated that this class of molecules targets calmodulin as part of their mechanism of action and that tamoxifen analogs with increased calmodulin antagonism have improved anti-cryptococcal activity. Taken together, these results indicate that tamoxifen is a pharmacologically attractive scaffold for the development of new anti-cryptococcal drugs and provide a mechanistic basis for its further optimization.

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