101
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Bruhn KW, Spellberg B. Transferrin-mediated iron sequestration as a novel therapy for bacterial and fungal infections. Curr Opin Microbiol 2015; 27:57-61. [PMID: 26261881 DOI: 10.1016/j.mib.2015.07.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/10/2015] [Indexed: 10/23/2022]
Abstract
Pathogenic microbes must acquire essential nutrients, including iron, from the host in order to proliferate and cause infections. Iron sequestration is an ancient host antimicrobial strategy. Thus, enhancing iron sequestration is a promising, novel anti-infective strategy. Unfortunately, small molecule iron chelators have proven difficult to develop as anti-infective treatments, in part due to unacceptable toxicities. Iron sequestration in mammals is predominantly mediated by the transferrin family of iron-binding proteins. In this review, we explore the possibility of administering supraphysiological levels of exogenous transferrin as an iron sequestering therapy for infections, which could overcome some of the problems associated with small molecule chelation. Recent studies suggest that transferrin delivery may represent a promising approach to augment both natural resistance and traditional antibiotic therapy.
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Affiliation(s)
- Kevin W Bruhn
- Department of Molecular Microbiology & Immunology, Keck School of Medicine at the University of Southern California (USC), Los Angeles, CA, United States.
| | - Brad Spellberg
- Department of Medicine, Keck School of Medicine at USC, Los Angeles, United States
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102
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Miceli MH, Kauffman CA. Treatment Options for Mucormycosis. CURRENT TREATMENT OPTIONS IN INFECTIOUS DISEASES 2015. [DOI: 10.1007/s40506-015-0050-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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103
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Liu M, Lin L, Gebremariam T, Luo G, Skory CD, French SW, Chou TF, Edwards JE, Ibrahim AS. Fob1 and Fob2 Proteins Are Virulence Determinants of Rhizopus oryzae via Facilitating Iron Uptake from Ferrioxamine. PLoS Pathog 2015; 11:e1004842. [PMID: 25974051 PMCID: PMC4431732 DOI: 10.1371/journal.ppat.1004842] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 03/31/2015] [Indexed: 12/20/2022] Open
Abstract
Dialysis patients with chronic renal failure receiving deferoxamine for treating iron overload are uniquely predisposed for mucormycosis, which is most often caused by Rhizopus oryzae. Although the deferoxamine siderophore is not secreted by Mucorales, previous studies established that Rhizopus species utilize iron from ferrioxamine (iron-rich form of deferoxamine). Here we determined that the CBS domain proteins of Fob1 and Fob2 act as receptors on the cell surface of R. oryzae during iron uptake from ferrioxamine. Fob1 and Fob2 cell surface expression was induced in the presence of ferrioxamine and bound radiolabeled ferrioxamine. A R. oryzae strain with targeted reduced Fob1/Fob2 expression was impaired for iron uptake, germinating, and growing on medium with ferrioxamine as the sole source of iron. This strain also exhibited reduced virulence in a deferoxamine-treated, but not the diabetic ketoacidotic (DKA), mouse model of mucormycosis. The mechanism by which R. oryzae obtains iron from ferrioxamine involves the reductase/permease uptake system since the growth on ferrioxamine supplemented medium is associated with elevated reductase activity and the use of the ferrous chelator bathophenanthroline disulfonate abrogates iron uptake and growth on medium supplemented with ferrioxamine as a sole source of iron. Finally, R. oryzae mutants with reduced copies of the high affinity iron permease (FTR1) or with decreased FTR1 expression had an impaired iron uptake from ferrioxamine in vitro and reduced virulence in the deferoxamine-treated mouse model of mucormycosis. These two receptors appear to be conserved in Mucorales, and can be the subject of future novel therapy to maintain the use of deferoxamine for treating iron-overload. Deferoxamine is an iron-chelating agent often used to treat patients with acute iron poisoning, such as seen in dialysis patients with chronic renal failure. These patients are uniquely predisposed to a deadly fungal infection, called mucormycosis, because deferoxamine supplies iron that supports growth of fungi causing this infection. Apart from the important basic knowledge in delineating iron uptake mechanisms in cells, understanding how organisms causing mucormycosis obtain iron from ferrioxamine (deferoxamine bound with iron) is likely to develop strategies to treat mucormycosis infections in patients treated with deferoxamine. In this study we identified two cell surface receptors that bind ferrioxamine and facilitate iron uptake in Rhizopus oryzae, the most causative fungus of mucormycosis. These receptors are required for full virulence of R. oryzae in mice treated with deferoxamine. From genetic and biochemical studies it appears that the fungus binds ferrioxamine via these two receptors then liberates iron through a chemical modification step prior to transporting into the fungal cell without the internalization of deferoxamine.
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Affiliation(s)
- Mingfu Liu
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Lin Lin
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
| | - Teclegiorgis Gebremariam
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Guanpingsheng Luo
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Christopher D Skory
- National Center for Agricultural Utilization Research, United States Department of Agriculture (USDA), Peoria, Illinois, United States of America
| | - Samuel W French
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; Department of Pathology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
| | - Tsui-Fen Chou
- Division of Medical Genetics, Department of Pediatrics, Harbor-University of California, Los Angeles Medical Center and Los Angeles Biomedical Research Institute, Torrance, California, United States of America
| | - John E Edwards
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
| | - Ashraf S Ibrahim
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California, Los Angeles (UCLA) Medical Center, Torrance, California, United States of America; David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, United States of America
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104
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Matthaiou DK, Christodoulopoulou T, Dimopoulos G. How to treat fungal infections in ICU patients. BMC Infect Dis 2015; 15:205. [PMID: 25930035 PMCID: PMC4419464 DOI: 10.1186/s12879-015-0934-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 04/21/2015] [Indexed: 12/22/2022] Open
Abstract
Fungal infections represent a major burden in the critical care setting with increasing morbidity and mortality. Candidiasis is the leading cause of such infections, with C. albicans being the most common causative agent, followed by Aspergillosis and Mucormycosis. The diagnosis of such infections is cumbersome requiring increased clinical vigilance and extensive laboratory testing, including radiology, cultures, biopsies and other indirect methods. However, it is not uncommon for definitive evidence to be unavailable. Risk and host factors indicating the probability of infections may greatly help in the diagnostic approach. Timely and adequate intervention is important for their successful treatment. The available therapeutic armamentarium, although not very extensive, is effective with low resistance rates for the newer antifungal agents. However, timely and prudent use is necessary to maximize favorable outcomes.
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Affiliation(s)
- Dimitrios K Matthaiou
- Department of Critical Care, University Hospital ATTIKON, Medical School, University of Athens, 1 Rimini str, Haidari-Athens, 12462, Greece.
| | - Theodora Christodoulopoulou
- Department of Critical Care, University Hospital ATTIKON, Medical School, University of Athens, 1 Rimini str, Haidari-Athens, 12462, Greece.
| | - George Dimopoulos
- Department of Critical Care, University Hospital ATTIKON, Medical School, University of Athens, 1 Rimini str, Haidari-Athens, 12462, Greece.
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105
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Combination Therapy for the Treatment of Mucormycosis: Examining the Evidence. CURRENT FUNGAL INFECTION REPORTS 2015. [DOI: 10.1007/s12281-015-0222-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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106
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Zanette RA, Bitencourt PER, Kontoyiannis DP, Fighera RA, Flores MM, Kommers GD, Silva PS, Ludwig A, Moretto MB, Alves SH, Santurio JM. Complex interaction of deferasirox and Pythium insidiosum: iron-dependent attenuation of growth in vitro and immunotherapy-like enhancement of immune responses in vivo. PLoS One 2015; 10:e0118932. [PMID: 25738758 PMCID: PMC4349436 DOI: 10.1371/journal.pone.0118932] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 01/07/2015] [Indexed: 12/22/2022] Open
Abstract
Pythium insidiosum iron acquisition mechanisms are unknown. We previously showed that the iron chelator deferasirox had weak activity in vitro and in rabbits with experimental pythiosis. Here we show that deferasirox causes damage to P. insidiosum hyphae in vitro, but that activity is diminished in the presence of exogenous iron. The tissue activity of the proinflammatory enzyme adenosine deaminase and the histological pattern observed in pythiosis lesions of rabbits treated with deferasirox were similar to the ones in animals treated with immunotherapy.
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Affiliation(s)
- Régis A. Zanette
- Graduate Program in Pharmacology, Health Science Center, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Paula E. R. Bitencourt
- Graduate Program in Pharmaceutical Sciences, Health Science Center, UFSM, Santa Maria, RS, Brazil
| | - Dimitrios P. Kontoyiannis
- Department of Infectious Diseases, Infection Control and Employee Health, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Rafael A. Fighera
- Graduate Program in Veterinary Medicine, Health Science Center, UFSM, Santa Maria, RS, Brazil
| | - Mariana M. Flores
- Graduate Program in Veterinary Medicine, Health Science Center, UFSM, Santa Maria, RS, Brazil
| | - Glaucia D. Kommers
- Graduate Program in Veterinary Medicine, Health Science Center, UFSM, Santa Maria, RS, Brazil
| | - Priscila S. Silva
- Graduate Program in Pharmaceutical Sciences, Health Science Center, UFSM, Santa Maria, RS, Brazil
| | - Aline Ludwig
- Graduate Program in Pharmacology, Health Science Center, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Maria B. Moretto
- Graduate Program in Pharmaceutical Sciences, Health Science Center, UFSM, Santa Maria, RS, Brazil
| | - Sydney H. Alves
- Graduate Program in Pharmacology, Health Science Center, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
- Graduate Program in Pharmaceutical Sciences, Health Science Center, UFSM, Santa Maria, RS, Brazil
| | - Janio M. Santurio
- Graduate Program in Pharmacology, Health Science Center, Federal University of Santa Maria (UFSM), Santa Maria, RS, Brazil
- * E-mail:
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107
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ATP exhibits antimicrobial action by inhibiting bacterial utilization of ferric ions. Sci Rep 2015; 5:8610. [PMID: 25712807 PMCID: PMC4339799 DOI: 10.1038/srep08610] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/22/2015] [Indexed: 11/08/2022] Open
Abstract
ATP up-regulates macrophage antimycobacterial activity in a P2X7-dependent manner, but little is known about whether ATP directly exhibits antimicrobial effects against intracellular mycobacteria. In this study, we found that ATP inhibited the growth of various bacteria, including Staphylococcus, Pseudomonas, and mycobacteria, without damaging bacterial surface structures. Using gene technology, we newly established an enterobactin-deficient (entB(-)) mutant from ATP-resistant Klebsiella pneumoniae, and found the recovery of ATP susceptibility in the enterobactin-deleted mutant. Therefore, ATP's antibacterial activity is attributable to its iron-chelating ability. Since ATP distributed in the cytosol of macrophages at high concentrations, ATP appears to augment macrophage's antimicrobial activity by directly attacking intracytosolic and intra-autophagosomal pathogens. Furthermore, ATP exhibited combined effects with some antimicrobials against methicillin-resistant S. aureus (MRSA) and M. intracellulare, suggesting its usefulness as an adjunctive drug in the chemotherapy of certain intractable infections.
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108
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Candoni A, Aversa F, Busca A, Cesaro S, Girmenia C, Luppi M, Rossi G, Venditti A, Nosari AM, Pagano L. Combination antifungal therapy for invasive mould diseases in haematologic patients. An update on clinical data. J Chemother 2014; 27:1-12. [DOI: 10.1179/1973947814y.0000000224] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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109
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Mendoza L, Vilela R, Voelz K, Ibrahim AS, Voigt K, Lee SC. Human Fungal Pathogens of Mucorales and Entomophthorales. Cold Spring Harb Perspect Med 2014; 5:cshperspect.a019562. [PMID: 25377138 DOI: 10.1101/cshperspect.a019562] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In recent years, we have seen an increase in the number of immunocompromised cohorts as a result of infections and/or medical conditions, which has resulted in an increased incidence of fungal infections. Although rare, the incidence of infections caused by fungi belonging to basal fungal lineages is also continuously increasing. Basal fungal lineages diverged at an early point during the evolution of the fungal lineage, in which, in a simplified four-phylum fungal kingdom, Zygomycota and Chytridiomycota belong to the basal fungi, distinguishing them from Ascomycota and Basidiomycota. Currently there are no known human infections caused by fungi in Chytridiomycota; only Zygomycotan fungi are known to infect humans. Hence, infections caused by zygomycetes have been called zygomycosis, and the term "zygomycosis" is often used as a synonym for "mucormycosis." In the four-phylum fungal kingdom system, Zygomycota is classified mainly based on morphology, including the ability to form coenocytic (aseptated) hyphae and zygospores (sexual spores). In the Zygomycota, there are 10 known orders, two of which, the Mucorales and Entomophthorales, contain species that can infect humans, and the infection has historically been known as zygomycosis. However, recent multilocus sequence typing analyses (the fungal tree of life [AFTOL] project) revealed that the Zygomycota forms not a monophyletic clade but instead a polyphyletic clade, whereas Ascomycota and Basidiomycota are monophyletic. Thus, the term "zygomycosis" needed to be further specified, resulting in the terms "mucormycosis" and "entomophthoramycosis." This review covers these two different types of fungal infections.
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Affiliation(s)
- Leonel Mendoza
- Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48424-1031 Biomedical Laboratory Diagnostics, Michigan State University, East Lansing, Michigan 48424-1031
| | - Raquel Vilela
- Biomedical Laboratory Diagnostics, Michigan State University, East Lansing, Michigan 48424-1031 Faculty of Pharmacy, Federal University of Minas Gerais (UFMG), Minas Gerais, CEP33400000 Belo Horizonte, Brazil Belo Horizonte Brazil; Superior Institute of Medicine (ISMD), Minas Gerais, CEP33400000 Belo Horizonte, Brazil
| | - Kerstin Voelz
- Institute of Microbiology and Infection & School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom The National Institute of Health Research Surgical Reconstruction and Microbiology Research Centre, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom B15 2WB
| | - Ashraf S Ibrahim
- Division of Infectious Diseases, Harbor-University of California Los Angeles Medical Center, St. John's Cardiovascular Research Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90502 David Geffen School of Medicine at UCLA, Los Angeles, California 90095
| | - Kerstin Voigt
- Jena Microbial Resource Collection, Leibniz Institute for Natural Product Research and Infection Biology and University of Jena, Faculty of Biology and Pharmacy, Institute of Microbiology, Neugasse 25, 07743 Jena, Germany
| | - Soo Chan Lee
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
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110
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Nairz M, Schroll A, Demetz E, Tancevski I, Theurl I, Weiss G. 'Ride on the ferrous wheel'--the cycle of iron in macrophages in health and disease. Immunobiology 2014; 220:280-94. [PMID: 25240631 DOI: 10.1016/j.imbio.2014.09.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/20/2014] [Accepted: 09/05/2014] [Indexed: 12/16/2022]
Abstract
Iron homeostasis and macrophage biology are closely interconnected. On the one hand, iron exerts multiple effects on macrophage polarization and functionality. On the other hand, macrophages are central for mammalian iron homeostasis. The phagocytosis of senescent erythrocytes and their degradation by macrophages enable efficient recycling of iron and the maintenance of systemic iron balance. Macrophages express multiple molecules and proteins for the acquisition and utilization of iron and many of these pathways are affected by inflammatory signals. Of note, iron availability within macrophages has significant effects on immune effector functions and metabolic pathways within these cells. This review summarizes the physiological and pathophysiological aspects of macrophage iron metabolism and highlights its relevant consequences on immune function and in common diseases such as infection and atherosclerosis.
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Affiliation(s)
- Manfred Nairz
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria.
| | - Andrea Schroll
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Egon Demetz
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Ivan Tancevski
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Igor Theurl
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria
| | - Günter Weiss
- Department of Internal Medicine VI, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Austria.
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111
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Comparative pharmacodynamics of posaconazole in neutropenic murine models of invasive pulmonary aspergillosis and mucormycosis. Antimicrob Agents Chemother 2014; 58:6767-72. [PMID: 25182639 DOI: 10.1128/aac.03569-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We used two established neutropenic murine models of pulmonary aspergillosis and mucormycosis to explore the association between the posaconazole area under the concentration-time curve (AUC)-to-MIC ratio (AUC/MIC) and treatment outcome. Posaconazole serum pharmacokinetics were verified in infected mice to ensure that the studied doses reflected human exposures with the oral suspension, delayed-release tablet, and intravenous formulations of posaconazole. Sinopulmonary infections were then induced in groups of neutropenic mice with Aspergillus fumigatus strain 293 (posaconazole MIC, 0.5 mg/liter) or Rhizopus oryzae strain 969 (posaconazole MIC, 2 mg/liter) and treated with escalating daily dosages of oral posaconazole, which was designed to achieve AUCs ranging from 1.10 to 392 mg · h/liter. After 5 days of treatment, lung fungal burden was analyzed by quantitative real-time PCR. The relationships of the total drug AUC/MIC and the treatment response were similar in both models, with 90% effective concentrations (EC90s) corresponding to an AUC/MIC threshold of 76 (95% confidence interval [CI], 46 to 102) for strain 293 versus 87 (95% CI, 66 to 101) for strain 969. Using a provisional AUC/MIC target of >100, these exposures correlated with minimum serum posaconazole concentrations (Cmins) of 1.25 mg/liter for strain 293 and 4.0 mg/liter for strain 969. The addition of deferasirox, but not liposomal amphotericin or caspofungin, improved the activity of a suboptimal posaconazole regimen (AUC/MIC, 33) in animals with pulmonary mucormycosis. However, no combination was as effective as the high-dose posaconazole monotherapy regimen (AUC/MIC, 184). Our analysis suggests that posaconazole pharmacodynamics are similar for A. fumigatus and R. oryzae when indexed to pathogen MICs.
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112
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Ibrahim AS. Host-iron assimilation: pathogenesis and novel therapies of mucormycosis. Mycoses 2014; 57 Suppl 3:13-7. [PMID: 25178879 DOI: 10.1111/myc.12232] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 01/31/2014] [Indexed: 11/30/2022]
Abstract
Mucormycosis is a fungal infection caused by organisms belonging to the order Mucorales. Although considered uncommon, mucormycosis has been steadily increasing in incidents for the last two decades. Mortality of the disease is unacceptably high despite antifungal therapy and surgical interventions. The lack of understanding of the pathogenesis of the disease and the absence of rapid diagnostic assay contribute to the poor prognosis of mucormycosis. The hyper susceptibility of patients with elevated available serum iron points to the critical role of the ability of Mucorales to acquire host iron as a critical virulence factor. Specifically patients with deferoxamine-therapy, hyperglycaemic with or without ketoacidosis, or other forms of acidosis are uniquely predisposed to mucormycosis. In this review, we discuss the molecular mechanisms of infection in these patient categories in an attempt to identify novel therapies for a disease with poor prognosis. Emphasis on the effect of glucose and free iron on host-pathogen interactions are also covered.
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Affiliation(s)
- Ashraf S Ibrahim
- The Division of Infectious Diseases, Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles (UCLA) Medical Center and the St. John's Cardiovascular Research Center, Torrance, CA, USA; David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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113
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Roilides E, Antachopoulos C, Simitsopoulou M. Pathogenesis and host defence against Mucorales: the role of cytokines and interaction with antifungal drugs. Mycoses 2014; 57 Suppl 3:40-7. [PMID: 25175306 DOI: 10.1111/myc.12236] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 04/21/2014] [Accepted: 04/22/2014] [Indexed: 12/15/2022]
Abstract
Innate immune response, including macrophages, neutrophils and dendritic cells and their respective receptors, plays an important role in host defences against Mucorales with differential activity against specific fungal species, while adaptive immunity is not the first line of defence. A number of endogenous and exogenous factors, such as cytokines and growth factors as well as certain antifungal agents have been found that they influence innate immune response to these organisms. Used alone or especially in combination have been shown to exert antifungal effects against Mucorales species. These findings suggest novel ways of adjunctive therapy for patients with invasive mucormycosis.
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Affiliation(s)
- Emmanuel Roilides
- Infectious Diseases Unit, 3rd Department of Pediatrics, Faculty of Medicine, Aristotle University School of Health Sciences, and Hippokration General Hospital, Thessaloniki, Greece
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114
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Schwartze VU, Winter S, Shelest E, Marcet-Houben M, Horn F, Wehner S, Linde J, Valiante V, Sammeth M, Riege K, Nowrousian M, Kaerger K, Jacobsen ID, Marz M, Brakhage AA, Gabaldón T, Böcker S, Voigt K. Gene expansion shapes genome architecture in the human pathogen Lichtheimia corymbifera: an evolutionary genomics analysis in the ancient terrestrial mucorales (Mucoromycotina). PLoS Genet 2014; 10:e1004496. [PMID: 25121733 PMCID: PMC4133162 DOI: 10.1371/journal.pgen.1004496] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 05/24/2014] [Indexed: 01/12/2023] Open
Abstract
Lichtheimia species are the second most important cause of mucormycosis in Europe. To provide broader insights into the molecular basis of the pathogenicity-associated traits of the basal Mucorales, we report the full genome sequence of L. corymbifera and compared it to the genome of Rhizopus oryzae, the most common cause of mucormycosis worldwide. The genome assembly encompasses 33.6 MB and 12,379 protein-coding genes. This study reveals four major differences of the L. corymbifera genome to R. oryzae: (i) the presence of an highly elevated number of gene duplications which are unlike R. oryzae not due to whole genome duplication (WGD), (ii) despite the relatively high incidence of introns, alternative splicing (AS) is not frequently observed for the generation of paralogs and in response to stress, (iii) the content of repetitive elements is strikingly low (<5%), (iv) L. corymbifera is typically haploid. Novel virulence factors were identified which may be involved in the regulation of the adaptation to iron-limitation, e.g. LCor01340.1 encoding a putative siderophore transporter and LCor00410.1 involved in the siderophore metabolism. Genes encoding the transcription factors LCor08192.1 and LCor01236.1, which are similar to GATA type regulators and to calcineurin regulated CRZ1, respectively, indicating an involvement of the calcineurin pathway in the adaption to iron limitation. Genes encoding MADS-box transcription factors are elevated up to 11 copies compared to the 1-4 copies usually found in other fungi. More findings are: (i) lower content of tRNAs, but unique codons in L. corymbifera, (ii) Over 25% of the proteins are apparently specific for L. corymbifera. (iii) L. corymbifera contains only 2/3 of the proteases (known to be essential virulence factors) in comparison to R. oryzae. On the other hand, the number of secreted proteases, however, is roughly twice as high as in R. oryzae.
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Affiliation(s)
- Volker U. Schwartze
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Sascha Winter
- University of Jena, Department of Bioinformatics, Jena, Germany
| | - Ekaterina Shelest
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Systems Biology/Bioinformatics, Jena, Germany
| | - Marina Marcet-Houben
- Centre for Genomic Regulation (CRG), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Fabian Horn
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Systems Biology/Bioinformatics, Jena, Germany
| | - Stefanie Wehner
- University of Jena, Department of Bioinformatics, Jena, Germany
| | - Jörg Linde
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Systems Biology/Bioinformatics, Jena, Germany
| | - Vito Valiante
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Michael Sammeth
- Centre Nacional d'Anàlisi Genòmica (CNAG), Functional Bioinformatics, Barcelona, Spain
- Laboratório Nacional de Computação Científica (LNCC), Petrópolis, Rio de Janeiro, Brazil
| | | | - Minou Nowrousian
- Ruhr University Bochum, Department of General and Molecular Botany, Bochum, Germany
| | - Kerstin Kaerger
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Ilse D. Jacobsen
- Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Department of Microbial Immunology, Jena, Germany
| | - Manja Marz
- University of Jena, Department of Bioinformatics, Jena, Germany
| | - Axel A. Brakhage
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
| | - Toni Gabaldón
- Centre for Genomic Regulation (CRG), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | | | - Kerstin Voigt
- University of Jena, Institute of Microbiology, Department of Microbiology and Molecular Biology, Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology, Department of Molecular and Applied Microbiology, Hans Knöll Institute, Jena, Germany
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115
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Nairz M, Haschka D, Demetz E, Weiss G. Iron at the interface of immunity and infection. Front Pharmacol 2014; 5:152. [PMID: 25076907 PMCID: PMC4100575 DOI: 10.3389/fphar.2014.00152] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 06/10/2014] [Indexed: 12/18/2022] Open
Abstract
Both, mammalian cells and microbes have an essential need for iron, which is required for many metabolic processes and for microbial pathogenicity. In addition, cross-regulatory interactions between iron homeostasis and immune function are evident. Cytokines and the acute phase protein hepcidin affect iron homeostasis leading to the retention of the metal within macrophages and hypoferremia. This is considered to result from a defense mechanism of the body to limit the availability of iron for extracellular pathogens while on the other hand the reduction of circulating iron results in the development of anemia of inflammation. Opposite, iron and the erythropoiesis inducing hormone erythropoietin affect innate immune responses by influencing interferon-gamma (IFN-γ) mediated (iron) or NF-kB inducible (erythropoietin) immune effector pathways in macrophages. Thus, macrophages loaded with iron lose their ability to kill intracellular pathogens via IFN-γ mediated effector pathways such as nitric oxide (NO) formation. Accordingly, macrophages invaded by the intracellular bacterium Salmonella enterica serovar Typhimurium increase the expression of the iron export protein ferroportin thereby reducing the availability of iron for intramacrophage bacteria while on the other side strengthening anti-microbial macrophage effector pathways via increased formation of NO or TNF-α. In addition, certain innate resistance genes such as natural resistance associated macrophage protein function (Nramp1) or lipocalin-2 exert part of their antimicrobial activity by controlling host and/or microbial iron homeostasis. Consequently, pharmacological or dietary modification of cellular iron trafficking enhances host resistance to intracellular pathogens but may increase susceptibility to microbes in the extracellular compartment and vice versa. Thus, the control over iron homeostasis is a central battlefield in host–pathogen interplay influencing the course of an infectious disease in favor of either the mammalian host or the pathogenic invader.
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Affiliation(s)
- Manfred Nairz
- Department of Internal Medicine VI-Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck Innsbruck, Austria
| | - David Haschka
- Department of Internal Medicine VI-Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck Innsbruck, Austria
| | - Egon Demetz
- Department of Internal Medicine VI-Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck Innsbruck, Austria
| | - Günter Weiss
- Department of Internal Medicine VI-Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck Innsbruck, Austria
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116
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Binder U, Maurer E, Lass-Flörl C. Mucormycosis – from the pathogens to the disease. Clin Microbiol Infect 2014; 20 Suppl 6:60-6. [DOI: 10.1111/1469-0691.12566] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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117
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Abstract
PURPOSE OF REVIEW Mucormycosis is an increasingly common fungal infection with unacceptably high mortality. The recent sequencing genome projects of Mucorales and the development of gene manipulation have enabled significant advances in understanding the pathogenesis of mucormycosis. Therefore, we review the pathogenesis of mucormycosis and highlight potential development of novel diagnostic and therapeutic modalities against this lethal disease. RECENT FINDINGS Much of the work has been focused on the role of iron uptake in the virulence of Mucorales. Additionally, host receptors and fungal ligands involved in the process of tissue invasion as well as sporangiospore size and sex loci and their contribution to virulence of Mucorales are discussed. Finally, the role of innate and adaptive immunity in protection against Mucorales and new evidence about drug-induced apoptosis in these fungi are discussed. SUMMARY Recent discoveries introduce several potentially novel diagnostic and therapeutic modalities, which are likely to improve management and outcome for mucormycosis. Future preclinical and clinical research is warranted to develop these diagnostic and therapeutic strategies.
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118
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Coulter KS, Bariola JR. Current Antifungal Agents for Treatment of Central Nervous System Infections. CURRENT FUNGAL INFECTION REPORTS 2014. [DOI: 10.1007/s12281-014-0186-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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119
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Cornely O, Arikan-Akdagli S, Dannaoui E, Groll A, Lagrou K, Chakrabarti A, Lanternier F, Pagano L, Skiada A, Akova M, Arendrup M, Boekhout T, Chowdhary A, Cuenca-Estrella M, Freiberger T, Guinea J, Guarro J, de Hoog S, Hope W, Johnson E, Kathuria S, Lackner M, Lass-Flörl C, Lortholary O, Meis J, Meletiadis J, Muñoz P, Richardson M, Roilides E, Tortorano A, Ullmann A, van Diepeningen A, Verweij P, Petrikkos G. ESCMID† and ECMM‡ joint clinical guidelines for the diagnosis and management of mucormycosis 2013. Clin Microbiol Infect 2014; 20 Suppl 3:5-26. [DOI: 10.1111/1469-0691.12371] [Citation(s) in RCA: 465] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/09/2013] [Accepted: 08/12/2013] [Indexed: 12/22/2022]
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120
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Lin L, Pantapalangkoor P, Tan B, Bruhn KW, Ho T, Nielsen T, Skaar EP, Zhang Y, Bai R, Wang A, Doherty TM, Spellberg B. Transferrin iron starvation therapy for lethal bacterial and fungal infections. J Infect Dis 2014; 210:254-64. [PMID: 24446527 DOI: 10.1093/infdis/jiu049] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
New strategies to treat antibiotic-resistant infections are urgently needed. We serendipitously discovered that stem cell conditioned media possessed broad antimicrobial properties. Biochemical, functional, and genetic assays confirmed that the antimicrobial effect was mediated by supra-physiological concentrations of transferrin. Human transferrin inhibited growth of gram-positive (Staphylococcus aureus), gram-negative (Acinetobacter baumannii), and fungal (Candida albicans) pathogens by sequestering iron and disrupting membrane potential. Serial passage in subtherapeutic transferrin concentrations resulted in no emergence of resistance. Infected mice treated with intravenous human transferrin had improved survival and reduced microbial burden. Finally, adjunctive transferrin reduced the emergence of rifampin-resistant mutants of S. aureus in infected mice treated with rifampin. Transferrin is a promising, novel antimicrobial agent that merits clinical investigation. These results provide proof of principle that bacterial infections can be treated in vivo by attacking host targets (ie, trace metal availability) rather than microbial targets.
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Affiliation(s)
- Lin Lin
- The Los Angeles Biomedical Research Institute, Torrance, California The Division of General Internal Medicine, Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance The David Geffen School of Medicine at UCLA, Los Angeles
| | | | - Brandon Tan
- The Los Angeles Biomedical Research Institute, Torrance, California
| | - Kevin W Bruhn
- The Los Angeles Biomedical Research Institute, Torrance, California The Division of General Internal Medicine, Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance The David Geffen School of Medicine at UCLA, Los Angeles
| | - Tiffany Ho
- The Los Angeles Biomedical Research Institute, Torrance, California
| | - Travis Nielsen
- The Los Angeles Biomedical Research Institute, Torrance, California
| | - Eric P Skaar
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Yaofang Zhang
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ruipeng Bai
- The Los Angeles Biomedical Research Institute, Torrance, California
| | - Amy Wang
- The Los Angeles Biomedical Research Institute, Torrance, California
| | | | - Brad Spellberg
- The Los Angeles Biomedical Research Institute, Torrance, California The Division of General Internal Medicine, Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance The David Geffen School of Medicine at UCLA, Los Angeles
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121
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Hatipoglu N, Hatipoglu H. Combination antifungal therapy for invasive fungal infections in children and adults. Expert Rev Anti Infect Ther 2014; 11:523-35. [DOI: 10.1586/eri.13.29] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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122
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Crabol Y, Lortholary O. Invasive mold infections in solid organ transplant recipients. SCIENTIFICA 2014; 2014:821969. [PMID: 25525551 PMCID: PMC4261198 DOI: 10.1155/2014/821969] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 11/03/2014] [Indexed: 05/13/2023]
Abstract
Invasive mold infections represent an increasing source of morbidity and mortality in solid organ transplant recipients. Whereas there is a large literature regarding invasive molds infections in hematopoietic stem cell transplants, data in solid organ transplants are scarcer. In this comprehensive review, we focused on invasive mold infection in the specific population of solid organ transplant. We highlighted epidemiology and specific risk factors for these infections and we assessed the main clinical and imaging findings by fungi and by type of solid organ transplant. Finally, we attempted to summarize the diagnostic strategy for detection of these fungi and tried to give an overview of the current prophylaxis treatments and outcomes of these infections in solid organ transplant recipients.
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Affiliation(s)
- Yoann Crabol
- Université Paris Descartes, Sorbonne Paris Cité, Centre d'Infectiologie Necker Pasteur, Institut Imagine, Hôpital Universitaire Necker-Enfants Malades, APHP, 75015 Paris, France
| | - Olivier Lortholary
- Université Paris Descartes, Sorbonne Paris Cité, Centre d'Infectiologie Necker Pasteur, Institut Imagine, Hôpital Universitaire Necker-Enfants Malades, APHP, 75015 Paris, France
- Institut Pasteur, Unité de Mycologie Moléculaire, Centre National de Référence Mycoses Invasives et Antifongiques, CNRS URA3012, 75015 Paris, France
- *Olivier Lortholary:
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123
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Gebremariam T, Liu M, Luo G, Bruno V, Phan QT, Waring AJ, Edwards JE, Filler SG, Yeaman MR, Ibrahim AS. CotH3 mediates fungal invasion of host cells during mucormycosis. J Clin Invest 2013; 124:237-50. [PMID: 24355926 DOI: 10.1172/jci71349] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 10/03/2013] [Indexed: 12/29/2022] Open
Abstract
Angioinvasion is a hallmark of mucormycosis. Previously, we identified endothelial cell glucose-regulated protein 78 (GRP78) as a receptor for Mucorales that mediates host cell invasion. Here we determined that spore coat protein homologs (CotH) of Mucorales act as fungal ligands for GRP78. CotH proteins were widely present in Mucorales and absent from noninvasive pathogens. Heterologous expression of CotH3 and CotH2 in Saccharomyces cerevisiae conferred the ability to invade host cells via binding to GRP78. Homology modeling and computational docking studies indicated structurally compatible interactions between GRP78 and both CotH3 and CotH2. A mutant of Rhizopus oryzae, the most common cause of mucormycosis, with reduced CotH expression was impaired for invading and damaging endothelial cells and CHO cells overexpressing GRP78. This strain also exhibited reduced virulence in a diabetic ketoacidotic (DKA) mouse model of mucormycosis. Treatment with anti-CotH Abs abolished the ability of R. oryzae to invade host cells and protected DKA mice from mucormycosis. The presence of CotH in Mucorales explained the specific susceptibility of DKA patients, who have increased GRP78 levels, to mucormycosis. Together, these data indicate that CotH3 and CotH2 function as invasins that interact with host cell GRP78 to mediate pathogenic host-cell interactions and identify CotH as a promising therapeutic target for mucormycosis.
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124
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Tsoulas C, Tragiannidis A, Groll AH. Medical and Adjunctive Treatment of Mucormycosis in Children: Scientific Rationale and Analysis of Cases Reported in the Literature. CURRENT FUNGAL INFECTION REPORTS 2013. [DOI: 10.1007/s12281-013-0166-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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125
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Combination therapy with iron chelation and vancomycin in treating murine staphylococcemia. Eur J Clin Microbiol Infect Dis 2013; 33:845-51. [PMID: 24292099 DOI: 10.1007/s10096-013-2023-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 11/15/2013] [Indexed: 02/07/2023]
Abstract
Iron acquisition is a virulence factor for Staphylococcus aureus. We assessed the efficacy of the iron chelator, deferasirox (Def), alone or in combination with vancomycin (Van) against two methicillin-resistant S. aureus (MRSA) strains in vitro and in a murine bacteremia model. In vitro time-kill assays were carried out against MRSA or vancomycin-intermediate S. aureus (VISA) strains. The impact of Def on Van binding to the surface of S. aureus was measured by flow cytometry. Furthermore, we compared the efficacy of Def, Van, or both drugs in treating S. aureus bacteremia in a murine model. Combination therapy reduced MRSA and VISA viability in vitro versus either drug alone or untreated controls (p < 0.005); this outcome was correlated with enhanced Van surface binding to S. aureus cells. In vivo, Def + Van combination therapy significantly reduced the bacterial burden in mice kidneys (p = 0.005) and spleen (p < 0.001), and reduced the severity of infection with MRSA or VISA strains compared to placebo-treated mice. Our results show that Def enhances the in vitro and in vivo capacity of Van-mediated MRSA killing via a mechanism that appears to involve increased binding of Van to the staphylococcal surface. Iron chelation is a promising, novel adjunctive therapeutic strategy for MRSA and VISA infections.
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126
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127
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Kontoghiorghe CN, Kolnagou A, Kontoghiorghes GJ. Potential clinical applications of chelating drugs in diseases targeting transferrin-bound iron and other metals. Expert Opin Investig Drugs 2013; 22:591-618. [PMID: 23586878 DOI: 10.1517/13543784.2013.787408] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Iron is essential for normal, neoplasmic and microbial cells. Transferrin (Tf) is responsible for iron transport and its interactions with chelators are of physiological and toxicological importance and could lead to new therapeutic applications. AREAS COVERED Differential interactions of Tf with chelators such as deferiprone (L1) could be used to modify toxicity and disease pathways in relation to iron and other metal metabolism. Iron mobilization by L1 could achieve normal body iron stores in thalassemia patients. Iron mobilization from the reticuloendothelial system by L1 and exchange with Tf could be used to increase the production of hemoglobin in the anemia of chronic disease. Iron accumulation is pathogenic in neurodegenerative, acute kidney and other diseases and could be removed by L1 with therapeutic implications. Deprivation of iron from neoplasmic and microbial cells by chelators could increase the prospect of improved treatments in cancer and infectious diseases. Other applications include metal detoxification and inhibition of oxidative stress-related conditions. EXPERT OPINION Specific mechanisms apply in the interactions of chelators with Tf, which could be used in the design of targeted therapeutic strategies in many conditions. In each case specific chelator protocols have to be designed for achieving optimum therapeutic activity.
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Affiliation(s)
- Christina N Kontoghiorghe
- Postgraduate Research Institute of Science, Technology, Environment and Medicine, Limassol CY 3021, Cyprus.
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128
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Lyons JL. CNS Mold Infections. Curr Infect Dis Rep 2013; 15:569-575. [PMID: 24122369 DOI: 10.1007/s11908-013-0376-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Mold infections of the central nervous system (CNS) present as abscesses, infarcts, hemorrhages, and, less commonly, meningitis. These invasive infections are difficult both to identify and to eradicate given low-sensitivity diagnostics and high-toxicity, low-efficacy antifungal therapies, hence resulting in high rates of morbidity and mortality. Herein, the recent literature on CNS mold infections is reviewed, and updates in diagnosis and management are discussed.
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Affiliation(s)
- Jennifer L Lyons
- Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA,
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129
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Lewis RE, Kontoyiannis DP. Epidemiology and treatment of mucormycosis. Future Microbiol 2013; 8:1163-75. [DOI: 10.2217/fmb.13.78] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mucormycosis is an uncommon but aggressive opportunistic fungal infection that afflicts patients with severe underlying immunosuppression, uncontrolled hyperglycemia and/or ketoacidosis, patients with iron overload resulting from frequent blood transfusions or blood disorders and occasionally healthy patients who are inoculated with fungal spores through traumatic injuries. The clinical presentation of mucormycosis is initially indistinguishable from other common infections, and if not diagnosed early and aggressively treated, it is almost always fatal. In this article we summarize recent changes in the epidemiology of mucormycosis, discuss diagnostic and clinical clues suggestive of the infection and provide a general strategy for managing the infection in the absence of data from well-controlled, prospective clinical trials.
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Affiliation(s)
- Russell E Lewis
- Clinic of Infectious Diseases, Department of Internal Medicine, Geriatrics & Nephrologic Diseases, S’Orsola Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Dimitrios P Kontoyiannis
- Department of Infectious Diseases, Infection Control & Employee Health, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Division of Internal Medicine, Unit 1460, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, 77030, Houston, TX, USA
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130
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Targeting iron acquisition blocks infection with the fungal pathogens Aspergillus fumigatus and Fusarium oxysporum. PLoS Pathog 2013; 9:e1003436. [PMID: 23853581 PMCID: PMC3708856 DOI: 10.1371/journal.ppat.1003436] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 05/02/2013] [Indexed: 12/21/2022] Open
Abstract
Filamentous fungi are an important cause of pulmonary and systemic morbidity and mortality, and also cause corneal blindness and visual impairment worldwide. Utilizing in vitro neutrophil killing assays and a model of fungal infection of the cornea, we demonstrated that Dectin-1 dependent IL-6 production regulates expression of iron chelators, heme and siderophore binding proteins and hepcidin in infected mice. In addition, we show that human neutrophils synthesize lipocalin-1, which sequesters fungal siderophores, and that topical lipocalin-1 or lactoferrin restricts fungal growth in vivo. Conversely, we show that exogenous iron or the xenosiderophore deferroxamine enhances fungal growth in infected mice. By examining mutant Aspergillus and Fusarium strains, we found that fungal transcriptional responses to low iron levels and extracellular siderophores are essential for fungal growth during infection. Further, we showed that targeting fungal iron acquisition or siderophore biosynthesis by topical application of iron chelators or statins reduces fungal growth in the cornea by 60% and that dual therapy with the iron chelator deferiprone and statins further restricts fungal growth by 75%. Together, these studies identify specific host iron-chelating and fungal iron-acquisition mediators that regulate fungal growth, and demonstrate that therapeutic inhibition of fungal iron acquisition can be utilized to treat topical fungal infections.
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131
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Kronstad JW, Hu G, Jung WH. An encapsulation of iron homeostasis and virulence in Cryptococcus neoformans. Trends Microbiol 2013; 21:457-65. [PMID: 23810126 DOI: 10.1016/j.tim.2013.05.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 05/24/2013] [Accepted: 05/29/2013] [Indexed: 02/07/2023]
Abstract
Vertebrate hosts actively sequester iron, and fungal and other pathogens must therefore adapt to a severe limitation in iron availability to cause disease. Recent studies reveal that the pathogenic fungus Cryptococcus neoformans overcomes iron limitation by multiple mechanisms that target transferrin and heme. The regulation of iron uptake is mediated by an interconnected set of transcription factors that include the master iron regulator Cir1 and the pH-responsive factor Rim101. These factors integrate iron homeostasis with a myriad of other functions including pH sensing, nutrient and stress signaling pathways, virulence factor elaboration, and cell wall biogenesis.
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Affiliation(s)
- James W Kronstad
- Department of Microbiology and Immunology, The Michael Smith Laboratories, University of British Columbia, Vancouver BC, V6T 1Z4, Canada.
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132
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Álvarez F, Fernández-Ruiz M, Aguado JM. [Iron and invasive fungal infection]. Rev Iberoam Micol 2013; 30:217-25. [PMID: 23684655 DOI: 10.1016/j.riam.2013.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 04/08/2013] [Accepted: 04/30/2013] [Indexed: 01/19/2023] Open
Abstract
Iron is an essential factor for both the growth and virulence of most of microorganisms. As a part of the innate (or nutritional) immune system, mammals have developed different mechanisms to store and transport this element in order to limit free iron bioavailability. To survive in this hostile environment, pathogenic fungi have specific uptake systems for host iron sources, one of the most important of which is based on the synthesis of siderophores-soluble, low-molecular-mass, high-affinity iron chelators. The increase in free iron that results from iron-overload conditions is a well-established risk factor for invasive fungal infection (IFI) such as mucormycosis or aspergillosis. Therefore, iron chelation may be an appealing therapeutic option for these infections. Nevertheless, deferoxamine -the first approved iron chelator- paradoxically increases the incidence of IFI, as it serves as a xeno-siderophore to Mucorales. On the contrary, the new oral iron chelators (deferiprone and deferasirox) have shown to exert a deleterious effect on fungal growth both in vitro and in animal models. The present review focuses on the role of iron metabolism in the pathogenesis of IFI and summarises the preclinical data, as well as the limited clinical experience so far, in the use of new iron chelators as treatment for mucormycosis and invasive aspergillosis.
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Affiliation(s)
- Florencio Álvarez
- Servicio de Medicina Interna, Hospital Universitario 12 de Octubre, Instituto de Investigación Hospital 12 de Octubre (i+12), Universidad Complutense, Madrid, España
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133
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Efficacy of liposomal amphotericin B and posaconazole in intratracheal models of murine mucormycosis. Antimicrob Agents Chemother 2013; 57:3340-7. [PMID: 23650163 DOI: 10.1128/aac.00313-13] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mucormycosis is a life-threatening fungal infection almost uniformly affecting diabetics in ketoacidosis or other forms of acidosis and/or immunocompromised patients. Inhalation of Mucorales spores provides the most common natural route of entry into the host. In this study, we developed an intratracheal instillation model of pulmonary mucormycosis that hematogenously disseminates into other organs using diabetic ketoacidotic (DKA) or cyclophosphamide-cortisone acetate-treated mice. Various degrees of lethality were achieved for the DKA or cyclophosphamide-cortisone acetate-treated mice when infected with different clinical isolates of Mucorales. In both DKA and cyclophosphamide-cortisone acetate models, liposomal amphotericin B (LAmB) or posaconazole (POS) treatments were effective in improving survival, reducing lungs and brain fungal burdens, and histologically resolving the infection compared with placebo. These models can be used to study mechanisms of infection, develop immunotherapeutic strategies, and evaluate drug efficacies against life-threatening Mucorales infections.
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134
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Left Knee Cellulitis in a 61-Year-Old Carpenter. INFECTIOUS DISEASES IN CLINICAL PRACTICE 2013. [DOI: 10.1097/ipc.0b013e318278f8b7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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135
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Nairz M, Schleicher U, Schroll A, Sonnweber T, Theurl I, Ludwiczek S, Talasz H, Brandacher G, Moser PL, Muckenthaler MU, Fang FC, Bogdan C, Weiss G. Nitric oxide-mediated regulation of ferroportin-1 controls macrophage iron homeostasis and immune function in Salmonella infection. ACTA ACUST UNITED AC 2013; 210:855-73. [PMID: 23630227 PMCID: PMC3646493 DOI: 10.1084/jem.20121946] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
NOS2-derived nitric oxide drives ferroportin-1–mediated iron export in Salmonella-infected macrophages, thus limiting bacterial growth. Nitric oxide (NO) generated by inducible NO synthase 2 (NOS2) affects cellular iron homeostasis, but the underlying molecular mechanisms and implications for NOS2-dependent pathogen control are incompletely understood. In this study, we found that NO up-regulated the expression of ferroportin-1 (Fpn1), the major cellular iron exporter, in mouse and human cells. Nos2−/− macrophages displayed increased iron content due to reduced Fpn1 expression and allowed for an enhanced iron acquisition by the intracellular bacterium Salmonella typhimurium. Nos2 gene disruption or inhibition of NOS2 activity led to an accumulation of iron in the spleen and splenic macrophages. Lack of NO formation resulted in impaired nuclear factor erythroid 2-related factor-2 (Nrf2) expression, resulting in reduced Fpn1 transcription and diminished cellular iron egress. After infection of Nos2−/− macrophages or mice with S. typhimurium, the increased iron accumulation was paralleled by a reduced cytokine (TNF, IL-12, and IFN-γ) expression and impaired pathogen control, all of which were restored upon administration of the iron chelator deferasirox or hyperexpression of Fpn1 or Nrf2. Thus, the accumulation of iron in Nos2−/− macrophages counteracts a proinflammatory host immune response, and the protective effect of NO appears to partially result from its ability to prevent iron overload in macrophages
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Affiliation(s)
- Manfred Nairz
- Department of Internal Medicine VI, Medical University of Innsbruck, 6020 Innsbruck, Austria
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136
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Adams RLC, Bird RJ. Safety and efficacy of deferasirox in the management of transfusion-dependent patients with myelodysplastic syndrome and aplastic anaemia: a perspective review. Ther Adv Hematol 2013; 4:93-102. [PMID: 23610617 DOI: 10.1177/2040620712472355] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Deferasirox is an orally administered, once-daily iron chelator with a generally good safety and efficacy profile. Reported adverse events in the older myelodysplastic population are somewhat different to the more intensively investigated and younger thalassaemic population. Renal impairment is the most concerning adverse event, but this is reversible if identified and the drug is withdrawn early. Gastrointestinal effects, particularly diarrhoea, can be troublesome for older patients, but can be minimized with tailored therapy. Negative iron balance can be achieved in most patients with a median dose of 20 mg/kg/day, and doses up to 40 mg/kg are possible in patients with severe iron overload, who are at risk of cardiac decompensation.
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137
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Hosogaya N, Miyazaki T, Nagi M, Tanabe K, Minematsu A, Nagayoshi Y, Yamauchi S, Nakamura S, Imamura Y, Izumikawa K, Kakeya H, Yanagihara K, Miyazaki Y, Kugiyama K, Kohno S. The heme-binding protein Dap1 links iron homeostasis to azole resistance via the P450 protein Erg11 in Candida glabrata. FEMS Yeast Res 2013; 13:411-21. [PMID: 23496820 DOI: 10.1111/1567-1364.12043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/07/2013] [Accepted: 03/08/2013] [Indexed: 11/29/2022] Open
Abstract
The pathogenic fungus Candida glabrata is relatively resistant to azole antifungals, which target lanosterol 14α-demethylase (Erg11p) in the ergosterol biosynthesis pathway. Our study revealed that C. glabrata exhibits increased azole susceptibility under low-iron conditions. To investigate the molecular basis of this phenomenon, we generated a strain lacking the heme (iron protoporphyrin IX)-binding protein Dap1 in C. glabrata. The Δdap1 mutant displayed growth defects under iron-limited conditions, decreased azole tolerance, decreased production of ergosterol, and increased accumulation of 14α-methylated sterols lanosterol and squalene. All the Δdap1 phenotypes were complemented by wild-type DAP1, but not by DAP1(D91G) , in which a heme-binding site is mutated. Furthermore, azole tolerance of the Δdap1 mutant was rescued by exogenous ergosterol but not by iron supplementation alone. These results suggest that heme binding by Dap1 is crucial for Erg11 activity and ergosterol biosynthesis, thereby being required for azole tolerance. A Dap1-GFP fusion protein predominantly localized to vacuolar membranes and endosomes, and the Δdap1 cells exhibited aberrant vacuole morphologies, suggesting that Dap1 is also involved in the regulation of vacuole structures that could be important for iron storage. Our study demonstrates that Dap1 mediates a functional link between iron homeostasis and azole resistance in C. glabrata.
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Affiliation(s)
- Naoki Hosogaya
- Department of Molecular Microbiology and Immunology, Nagasaki University School of Medicine, Nagasaki, Japan
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138
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Sivgin S, Eser B. The management of iron overload in allogeneic hematopoietic stem cell transplant (alloHSCT) recipients: where do we stand? Ann Hematol 2013; 92:577-86. [PMID: 23430087 DOI: 10.1007/s00277-013-1682-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 01/15/2013] [Indexed: 01/19/2023]
Abstract
Iron overload (IO), primarily related to multiple red blood cell transfusions, is a relatively common complication in hematopoietic stem cell transplant (HSCT) recipients. Elevated pretransplant ferritin levels have been reported to increase the risk of non-relapse mortality following HSCT and might influence the risk of acute and chronic graft versus host disease. IO has been shown to be an important cause of mortality and morbidity in patients who have undergone alloHSCT (Armand et al., Blood 109:4586-4588, 2007; Kim et al., Acta Haematol 120:182-189, 2008; Kataoka et al., Biol Blood Marrow Transplant 15:195-204, 2009). We know that excessive iron accumulation results in tissue damage and organ failure, mainly as a result of the generation of free radicals that cause oxidative damage and organ dysfunction (e.g., hepatotoxicity, cardiotoxicity, and endocrine dysfunction) (Altes et al., Bone Marrow Transplantation 29: 987-989, 2002; Papanikolaou et al., Toxicol Appl Pharmac 202:199-211, 2005). In the last decade, efforts have been directed toward identifying alternative treatment for IO in alloHSCT recipients to maintain improved transplant outcomes.
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Affiliation(s)
- Serdar Sivgin
- Department of Hematology, Faculty of Medicine, Dedeman Stem Cell Transplantation Hospital, Erciyes University, Kayseri, Turkey.
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139
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Zanette RA, Alves SH, Pilotto MB, Weiblen C, Fighera RA, Wolkmer P, Flores MM, Santurio JM. Iron chelation therapy as a treatment for Pythium insidiosum in an animal model. J Antimicrob Chemother 2013; 68:1144-7. [DOI: 10.1093/jac/dks534] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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140
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Emerging therapies for multidrug resistant Acinetobacter baumannii. Trends Microbiol 2013; 21:157-63. [PMID: 23317680 DOI: 10.1016/j.tim.2012.12.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 01/21/2023]
Abstract
The global emergence of multidrug resistant Acinetobacter baumannii has reduced the number of clinically available antibiotics that retain activity against this pathogen. For this reason, the development of novel prevention and treatment strategies for infections caused by A. baumannii is necessary. Several studies have begun to characterize nonantibiotic approaches that utilize novel mechanisms of action to achieve antibacterial activity. Recent advances in phage therapy, iron chelation therapy, antimicrobial peptides, prophylactic vaccination, photodynamic therapy, and nitric oxide (NO)-based therapies have all been shown to have activity against A. baumannii. However, before these approaches can be used clinically there are still limitations and remaining questions that must be addressed.
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141
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Animal Models In Mycology: What Have We Learned Over The Past 30 Years. CURRENT FUNGAL INFECTION REPORTS 2012. [DOI: 10.1007/s12281-012-0126-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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142
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Combination Antifungal Therapy: Is it for everyone and every mycosis? INFECTIO 2012. [DOI: 10.1016/s0123-9392(12)70022-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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143
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Alberto García C, García E, Gómez C, Andrés Castillo S. Mucormicosis gastrointestinal en paciente diabético; reporte de un caso y revisión de la literatura. INFECTIO 2012. [DOI: 10.1016/s0123-9392(12)70035-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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144
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Lui GYL, Obeidy P, Ford SJ, Tselepis C, Sharp DM, Jansson PJ, Kalinowski DS, Kovacevic Z, Lovejoy DB, Richardson DR. The iron chelator, deferasirox, as a novel strategy for cancer treatment: oral activity against human lung tumor xenografts and molecular mechanism of action. Mol Pharmacol 2012; 83:179-90. [PMID: 23074173 DOI: 10.1124/mol.112.081893] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Deferasirox is an orally effective iron (Fe) chelator currently used for the treatment of iron-overload disease and has been implemented as an alternative to the gold standard chelator, desferrioxamine (DFO). Earlier studies demonstrated that DFO exhibits anticancer activity due to its ability to deplete cancer cells of iron. In this investigation, we examined the in vitro and in vivo activity of deferasirox against cells from human solid tumors. To date, there have been no studies to investigate the effect of deferasirox on these types of tumors in vivo. Deferasirox demonstrated similar activity at inhibiting proliferation of DMS-53 lung carcinoma and SK-N-MC neuroepithelioma cell lines compared with DFO. Furthermore, deferasirox was generally similar or slightly more effective than DFO at mobilizing cellular (59)Fe and inhibiting iron uptake from human transferrin depending on the cell type. However, deferasirox potently inhibited DMS-53 xenograft growth in nude mice when given by oral gavage, with no marked alterations in normal tissue histology. To understand the antitumor activity of deferasirox, we investigated its effect on the expression of molecules that play key roles in metastasis, cell cycle control, and apoptosis. We demonstrated that deferasirox increased expression of the metastasis suppressor protein N-myc downstream-regulated gene 1 and upregulated the cyclin-dependent kinase inhibitor p21(CIP1/WAF1) while decreasing cyclin D1 levels. Moreover, this agent increased the expression of apoptosis markers, including cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase 1. Collectively, we demonstrate that deferasirox is an orally effective antitumor agent against solid tumors.
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Affiliation(s)
- Goldie Y L Lui
- Iron Metabolism and Chelation Program, Department of Pathology and Bosch Institute, University of Sydney, Sydney, New South Wales, 2006 Australia
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Bailão EFLC, Parente AFA, Parente JA, Silva-Bailão MG, de Castro KP, Kmetzsch L, Staats CC, Schrank A, Vainstein MH, Borges CL, Bailão AM, de Almeida Soares CM. Metal Acquisition and Homeostasis in Fungi. CURRENT FUNGAL INFECTION REPORTS 2012. [DOI: 10.1007/s12281-012-0108-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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146
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Wermke M, Schmidt A, Middeke JM, Sockel K, von Bonin M, Schönefeldt C, Mair S, Plodeck V, Laniado M, Weiss G, Schetelig J, Ehninger G, Theurl I, Bornhäuser M, Platzbecker U. MRI-Based Liver Iron Content Predicts for Nonrelapse Mortality in MDS and AML Patients Undergoing Allogeneic Stem Cell Transplantation. Clin Cancer Res 2012; 18:6460-8. [DOI: 10.1158/1078-0432.ccr-12-1683] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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147
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Skiada A, Lanternier F, Groll AH, Pagano L, Zimmerli S, Herbrecht R, Lortholary O, Petrikkos GL. Diagnosis and treatment of mucormycosis in patients with hematological malignancies: guidelines from the 3rd European Conference on Infections in Leukemia (ECIL 3). Haematologica 2012; 98:492-504. [PMID: 22983580 DOI: 10.3324/haematol.2012.065110] [Citation(s) in RCA: 232] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Mucormycosis is an emerging cause of infectious morbidity and mortality in patients with hematologic malignancies. However, there are no recommendations to guide diagnosis and management. The European Conference on Infections in Leukemia assigned experts in hematology and infectious diseases to develop evidence-based recommendations for the diagnosis and treatment of mucormycosis. The guidelines were developed using the evidence criteria set forth by the American Infectious Diseases Society and the key recommendations are summarized here. In the absence of validated biomarkers, the diagnosis of mucormycosis relies on histology and/or detection of the organism by culture from involved sites with identification of the isolate at the species level (no grading). Antifungal chemotherapy, control of the underlying predisposing condition, and surgery are the cornerstones of management (level A II). Options for first-line chemotherapy of mucormycosis include liposomal amphotericin B and amphotericin B lipid complex (level B II). Posaconazole and combination therapy of liposomal amphotericin B or amphotericin B lipid complex with caspofungin are the options for second line-treatment (level B II). Surgery is recommended for rhinocerebral and skin and soft tissue disease (level A II). Reversal of underlying risk factors (diabetes control, reversal of neutropenia, discontinuation/taper of glucocorticosteroids, reduction of immunosuppressants, discontinuation of deferroxamine) is important in the treatment of mucormycosis (level A II). The duration of antifungal chemotherapy is not defined but guided by the resolution of all associated symptoms and findings (no grading). Maintenance therapy/secondary prophylaxis must be considered in persistently immunocompromised patients (no grading).
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Affiliation(s)
- Anna Skiada
- Department of Propaedeutic Medicine, Laikon General Hospital, National and Kapodistrian University of Athens, Athens, Greece
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Abstract
INTRODUCTION Since the first application of antibiotics to treat bacterial infections, the development and spread of resistance has been a persistent threat. An ever evolving pipeline of next-generation therapeutics is required for modern medicine to remain one step ahead of pathogens. AREAS COVERED This review describes recent efforts to develop drugs that interrupt the assimilation of iron by bacteria: a process that is vital to cellular homeostasis and is not currently targeted by antibiotics used in the clinic. This review also covers the mechanisms by which bacteria acquire iron for their environment, and details efforts to intervene in these processes, using small molecule inhibitors that target key steps in these pathways, with a special emphasis on recent advances published during the 2010 - 2012 period. EXPERT OPINION For decades, the routes used by bacteria to assimilate iron from host and environmental settings have been the subject of intense study. While numerous investigations have identified inhibitors of these pathways, many have stopped short of translating the in vitro results to in vivo proof of concept experiments. The extension of preliminary findings in this manner will significantly increase the impact of the field.
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Affiliation(s)
- Timothy L Foley
- National Institutes of Health, National Center for Advancing Translational Sciences, Division of Preclinical Innovation, 9800 Medical Center Drive, Bethesda, MD 20892-3370, USA
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149
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In vitro and in vivo biological activities of iron chelators and gallium nitrate against Acinetobacter baumannii. Antimicrob Agents Chemother 2012; 56:5397-400. [PMID: 22825117 DOI: 10.1128/aac.00778-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We investigated the ability of compounds interfering with iron metabolism to inhibit the growth of Acinetobacter baumannii. Iron restriction with transferrin or 2,2-bipyridyl significantly inhibited A. baumannii growth in vitro. Gallium nitrate alone was moderately effective at reducing A. baumannii growth but became bacteriostatic in the presence of serum or transferrin. More importantly, gallium nitrate treatment reduced lung bacterial burdens in mice. The use of gallium-based therapies shows promise for the control of multidrug-resistant A. baumannii.
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150
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An update on iron chelation therapy. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2012; 10:411-22. [PMID: 22790257 DOI: 10.2450/2012.0008-12] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 02/21/2012] [Indexed: 02/07/2023]
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