2599. Studying the Effects of Altering Histone Modification on Aspergillus fumigatus Virulence

Abstract Background As there are few drugs for treating invasive aspergillosis, there is an urgent need for new antifungal agents. Enzymes involved in histone modification are possible antifungal drug targets. We set out to investigate whether genes whose products are involved in histone modifications influence the virulence of Aspergillus fumigatus (Af). Methods Genes whose products were likely involved in histone modification were deleted in strain Af293 using CRISPR-Cas9. Virulence was assessed in a triamcinolone-treated mouse model of invasive pulmonary aspergillosis. The extent of Af-induced damage to the A549 pulmonary epithelial cell line was determined by Cr51 release assay. Results Af genes were selected for investigation based on their homology to genes encoding known histone modifying proteins and their high expression level in vivo. The genes were predicted to encode members of the COMPASS histone methyltransferase complex (cclA/bre2, set2/Afu5g06000), the SAGA histone acetyltransferase complex (spt3, spt8), and the RPDL histone deacetylase complex (hosA). The ΔcclA and Δset2 mutants had significant growth defects on rich media and were not tested further. The Δspt3 and Δspt8 mutants grew normally and had mild conidiation defects. The ΔhosA mutant had wild-type (WT) growth and conidiation in vitro. Mice infected with the WT strain had 100% mortality within 9 days whereas mice infected the Δspt3, Δspt8, and ΔhosA mutants had only 40% mortality by 21 days. The ΔhosA mutant also had impaired capacity to damage pulmonary epithelial cells in vitro. Conclusion Ccla and Set2, components of the COMPASS complex, are required for normal growth in vitro. Spt3 and Spt8, members of the SAGA complex, are required for normal conidiation and virulence. HosA, part of the RPD3L complex, is necessary for maximal virulence and induction of host cell damage. Our results suggest that the HosA histone deacetylase may be a promising drug target for treating invasive aspergillosis. Disclosures All authors: No reported disclosures.

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Efficient Clearance of Aspergillus fumigatus in Murine Lungs by an Ultrashort Antimicrobial Lipopeptide, Palmitoyl-Lys-Ala-dAla-Lys

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00526-08 ◽

2008 ◽

Vol 52 (9) ◽

pp. 3118-3126 ◽

Cited By ~ 29

Author(s):

Alexandra Vallon-Eberhard ◽

Arik Makovitzki ◽

Anne Beauvais ◽

Jean-Paul Latgé ◽

Steffen Jung ◽

...

Keyword(s):

Invasive Aspergillosis ◽

Aspergillus Fumigatus ◽

Microscopic Analysis ◽

Current Standard ◽

New Family ◽

Therapeutic Properties ◽

Survival Assay ◽

Opportunistic Fungal Pathogen

ABSTRACT Aspergillus fumigatus is an opportunistic fungal pathogen responsible for invasive aspergillosis in immunocompromised individuals. The inefficiency of antifungal agents and high mortality rate resulting from invasive aspergillosis remain major clinical concerns. Recently, we reported on a new family of ultrashort cationic lipopeptides active in vitro against fungi. Mode of action studies supported a membranolytic or a detergent-like effect. Here, we screened several lipopeptides in vitro for their anti-A. fumigatus activity. To investigate the therapeutic properties of the selected peptides in vivo, we challenged immunosuppressed C57BL/6 wild-type mice intranasally with DsRed-labeled A. fumigatus conidia and subsequently treated the animals locally with the lipopeptides. Confocal microscopic analysis revealed the degradation of DsRed-labeled hyphal forms and residual conidia in the lungs of the mice. The most efficient peptide was tested further using a survival assay and was found to significantly prolong the life of the treated animals, whereas no mice survived with the current standard antifungal treatment with amphotericin B. Moreover, as opposed to the drug-treated lungs, the peptide-treated lungs did not display any toxicity of the peptide. Our results highlight the potential of this family of lipopeptides for the treatment of pulmonary invasive aspergillosis.

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Aspergillus fumigatus inhibits angiogenesis through the production of gliotoxin and other secondary metabolites

Blood ◽

10.1182/blood-2009-07-231209 ◽

2009 ◽

Vol 114 (26) ◽

pp. 5393-5399 ◽

Cited By ~ 78

Author(s):

Ronen Ben-Ami ◽

Russell E. Lewis ◽

Konstantinos Leventakos ◽

Dimitrios P. Kontoyiannis

Keyword(s):

Invasive Aspergillosis ◽

Aspergillus Fumigatus ◽

Capillary Tube ◽

Umbilical Vein ◽

Tube Formation ◽

Dependent Manner ◽

Antiangiogenic Effect ◽

Umbilical Vein Endothelial Cells

AbstractIn susceptible hosts, angioinvasion by Aspergillus fumigatus triggers thrombosis, hypoxia, and proinflammatory cytokine release, all of which are stimuli for angiogenesis. We sought to determine whether A fumigatus directly modulates angiogenesis. A fumigatus culture filtrates profoundly inhibited the differentiation, migration, and capillary tube formation of human umbilical vein endothelial cells in vitro. To measure angiogenesis at the site of infection, we devised an in vivo Matrigel assay in cyclophosphamide-treated BALB/c mice with cutaneous invasive aspergillosis. Angiogenesis was significantly suppressed in Matrigel plugs implanted in A fumigatus–infected mice compared with plugs from uninfected control mice. The antiangiogenic effect of A fumigatus was completely abolished by deletion of the global regulator of secondary metabolism, laeA, and to a lesser extent by deletion of gliP, which controls gliotoxin production. Moreover, pure gliotoxin potently inhibited angiogenesis in vitro in a dose-dependent manner. Finally, overexpression of multiple angiogenesis mediator–encoding genes was observed in the lungs of cortisone-treated mice during early invasive aspergillosis, whereas gene expression returned rapidly to baseline levels in cyclophosphamide/cortisone-treated mice. Taken together, these results indicate that suppression of angiogenesis by A fumigatus both in vitro and in a neutropenic mouse model is mediated through secondary metabolite production.

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Antifungal effect of all-trans retinoic acid against Aspergillus fumigatus in vitro and in a pulmonary aspergillosis in vivo model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01874-20 ◽

2020 ◽

Author(s):

Elena Campione ◽

Roberta Gaziano ◽

Elena Doldo ◽

Daniele Marino ◽

Mattia Falconi ◽

...

Keyword(s):

Retinoic Acid ◽

Aspergillus Fumigatus ◽

Rat Model ◽

Fungal Infections ◽

Invasive Pulmonary Aspergillosis ◽

Antifungal Drugs ◽

Pulmonary Aspergillosis ◽

Fungistatic Activity

AIM: Aspergillus fumigatus is the most common opportunistic fungal pathogen and causes invasive pulmonary aspergillosis (IPA), with high mortality among immunosuppressed patients. Fungistatic activity of all-trans retinoic acid (ATRA) has been recently described in vitro. We evaluated the efficacy of ATRA in vivo and its potential synergistic interaction with other antifungal drugs. MATERIALS AND METHODS: A rat model of IPA and in vitro experiments were performed to assess the efficacy of ATRA against Aspergillus in association with classical antifungal drugs and in silico studies used to clarify its mechanism of action. RESULTS: ATRA (0.5 and 1 mM) displayed a strong fungistatic activity in Aspergillus cultures, while at lower concentrations, synergistically potentiated fungistatic efficacy of sub-inhibitory concentration of Amphotericin B (AmB) and Posaconazole (POS). ATRA also enhanced macrophagic phagocytosis of conidia. In a rat model of IPA, ATRA reduced mortality similarly to Posaconazole. CONCLUSION: Fungistatic efficacy of ATRA alone and synergistically with other antifungal drugs was documented in vitro, likely by inhibiting fungal Hsp90 expression and Hsp90-related genes. ATRA reduced mortality in a model of IPA in vivo. Those findings suggest ATRA as suitable fungistatic agent, also to reduce dosage and adverse reaction of classical antifungal drugs, and new therapeutic strategies against IPA and systemic fungal infections.

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In Vivo Analysis of Aspergillus fumigatus Developmental Gene Expression Determined by Real-Time Reverse Transcription-PCR

Infection and Immunity ◽

10.1128/iai.01483-07 ◽

2008 ◽

Vol 76 (8) ◽

pp. 3632-3639 ◽

Cited By ~ 38

Author(s):

Fabrice N. Gravelat ◽

Thomas Doedt ◽

Lisa Y. Chiang ◽

Hong Liu ◽

Scott G. Filler ◽

...

Keyword(s):

Gene Expression ◽

Aspergillus Fumigatus ◽

Real Time ◽

Reverse Transcription ◽

Invasive Pulmonary Aspergillosis ◽

Pcr Analysis ◽

Invasive Infection ◽

Reverse Transcription Pcr

ABSTRACT Very little is known about the developmental stages of Aspergillus fumigatus during invasive aspergillosis. We performed real-time reverse transcription-PCR analysis on lung samples from mice with invasive pulmonary aspergillosis to determine the expression of A. fumigatus genes that are expressed at specific stages of development. In established infection, A. fumigatus exhibited mRNA expression of genes specific to developmentally competent hyphae, such as stuA. In contrast, mRNA of genes expressed by conidia and precompetent hyphae was not detected. Many genes required for mycotoxin synthesis, including aspHS, gliP, mitF, and metAP, are known to be expressed by developmentally competent hyphae in vitro. Interestingly, each of these genes was expressed at significantly higher levels during invasive infection than in vitro. The expression of gliP mRNA in vitro was found to be highly dependent on culture conditions. Furthermore, gliP expression was found to be dependent on the transcription factor StuA both in vitro and in vivo. Therefore, developmentally competent hyphae predominate during established invasive infection, and many mycotoxin genes are expressed at high levels in vivo. These results highlight the importance of the evaluation of putative virulence factors expressed by competent hyphae and analysis of gene expression levels during invasive infection rather than in vitro alone.

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Heterogeneity among Isolates Reveals that Fitness in Low Oxygen Correlates withAspergillus fumigatusVirulence

mBio ◽

10.1128/mbio.01515-16 ◽

2016 ◽

Vol 7 (5) ◽

Cited By ~ 57

Author(s):

Caitlin H. Kowalski ◽

Sarah R. Beattie ◽

Kevin K. Fuller ◽

Elizabeth A. McGurk ◽

Yi-Wei Tang ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Experimental Evolution ◽

Invasive Pulmonary Aspergillosis ◽

Clinical Isolates ◽

Low Oxygen ◽

Single Strain ◽

Hypoxia Exposure ◽

Significant Difference

ABSTRACTPrevious work has shown that environmental and clinical isolates ofAspergillus fumigatusrepresent a diverse population that occupies a variety of niches, has extensive genetic diversity, and exhibits virulence heterogeneity in a number of animal models of invasive pulmonary aspergillosis (IPA). However, mechanisms explaining differences in virulence amongA. fumigatusisolates remain enigmatic. Here, we report a significant difference in virulence of two common lab strains, CEA10 and AF293, in the murine triamcinolone immunosuppression model of IPA, in which we previously identified severe low oxygen microenvironments surrounding fungal lesions. Therefore, we hypothesize that the ability to thrive within these lesions of low oxygen promotes virulence ofA. fumigatusin this model. To test this hypothesis, we performedin vitrofitness andin vivovirulence analyses in the triamcinolone murine model of IPA with 14 environmental and clinical isolates ofA. fumigatus. Among these isolates, we observed a strong correlation between fitness in low oxygenin vitroand virulence. In further support of our hypothesis, experimental evolution of AF293, a strain that exhibits reduced fitness in low oxygen and reduced virulence in the triamcinolone model of IPA, results in a strain (EVOL20) that has increased hypoxia fitness and a corresponding increase in virulence. Thus, the ability to thrive in low oxygen correlates with virulence ofA. fumigatusisolates in the context of steroid-mediated murine immunosuppression.IMPORTANCEAspergillus fumigatusoccupies multiple environmental niches, likely contributing to the genotypic and phenotypic heterogeneity among isolates. Despite reports of virulence heterogeneity, pathogenesis studies often utilize a single strain for the identification and characterization of virulence and immunity factors. Here, we describe significant variation betweenA. fumigatusisolates in hypoxia fitness and virulence, highlighting the advantage of including multiple strains in future studies. We also illustrate that hypoxia fitness correlates strongly with increased virulence exclusively in the nonleukopenic murine triamcinolone immunosuppression model of IPA. Through an experimental evolution experiment, we observe that chronic hypoxia exposure results in increased virulence ofA. fumigatus. We describe here the first observation of a model-specific virulence phenotype correlative within vitrofitness in hypoxia and pave the way for identification of hypoxia-mediated mechanisms of virulence in the fungal pathogenA. fumigatus.

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Effect of Quarum Sensing Molecules on Aspergillus fumigatus

Walailak Journal of Science and Technology (WJST) ◽

10.48048/wjst.2020.6172 ◽

2019 ◽

Vol 17 (4) ◽

pp. 348-358

Author(s):

Thanwa WONGSUK ◽

Passanesh SUKPHOPETCH

Keyword(s):

Aspergillus Fumigatus ◽

Biofilm Formation ◽

Cell Damage ◽

A549 Cells ◽

Alveolar Epithelial Cells ◽

Cytotoxic Activities ◽

Solid Media ◽

Opportunistic Fungal Pathogen

Aspergillus fumigatus is an opportunistic fungal pathogen to which immunocompromised patients are especially susceptible. A. fumigatus can form biofilms both in vitro and in vivo. Quorum sensing molecules (QSMs) have activity against some fungi. This study aimed to determine the activity of the QSMs farnesol, tyrosol, phenylethanol and tryptophol against the growth A. fumigatus on solid media, and against its ability to form biofilms. The activity of each QSM against planktonic A. fumigatus growth was assessed using the CLSI M38-A2 broth microdilution assay, while QSM inhibition of A. fumigatus’s biofilm formation was measured in crystal violet, and 2, 3-bis (2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-caboxanilide (XTT) assays. The QSMs reduced the colony diameter of the studied strains in a QSM-dependent pattern. Tryptophol showed the best effect and tyrosol showed the poorest effect. The minimum inhibitory concentrations (MICs) for farnesol, tyrosol, phenylethanol and tryptophol tested against A. fumigatus were > 32, > 32, 16 and 8 mM, respectively. The effective concentration each QSM required to inhibit A. fumigatus biofilm formation were higher than the planktonic MICs. In this study, the performance of QSMs against A. fumigatus ranked from best to worst as follows: tryptophol, phenylethanol, farnesol and tyrosol. Because of phenylethanol and tryptophol showed the strongest effect to the growth and biofilm formation of A. fumigatus. Therefore, the cytotoxic activities of phenylethanol and tryptophol in A549 cells (lung alveolar epithelial cells) were determined. However, phenylethanol and tryptophol induced A549 cell damage (at MIC level), as demonstrated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) and lactate dehydrogenase (LDH) assays.

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Determining Aspergillus fumigatus transcription factor expression and function during invasion of the mammalian lung

10.1101/2020.12.23.424128 ◽

2020 ◽

Author(s):

Hong Liu ◽

Wenjie Xu ◽

Vincent M. Bruno ◽

Quynh T. Phan ◽

Norma V. Solis ◽

...

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Secondary Metabolites ◽

Invasive Aspergillosis ◽

Aspergillus Fumigatus ◽

Transcriptional Profiling ◽

Transcriptional Response ◽

Transcription Factor Genes

AbstractTo gain a better understanding of the transcriptional response of Aspergillus fumigatus during invasive pulmonary infection, we used a NanoString nCounter to assess the transcript levels of 467 A. fumigatus genes during growth in the lungs of immunosuppressed mice. These genes included ones known to respond to diverse environmental conditions and those encoding most transcription factors in the A. fumigatus genome. We found that invasive growth in vivo induces a unique transcriptional profile as the organism responds to nutrient limitation and attack by host phagocytes. This in vivo transcriptional response is largely mimicked by in vitro growth in Aspergillus minimal medium that is deficient in nitrogen, iron, and/or zinc. From the transcriptional profiling data, we selected 9 transcription factor genes that were either highly expressed or strongly up-regulated during in vivo growth. Deletion mutants were constructed for each of these genes and assessed for virulence in mice. Two transcription factor genes were found to be required for maximal virulence. One was rlmA, which governs the ability of the organism to proliferate in the lung. The other was ace1, which regulates of the expression of multiple secondary metabolite gene clusters and mycotoxin genes independently of laeA. Using deletion and overexpression mutants, we determined that the attenuated virulence of the Δace1 mutant is due to decreased expression aspf1, which specifies a ribotoxin, but is not mediated by reduced expression of the fumigaclavine gene cluster or the fumagillin-pseruotin supercluster. Thus, in vivo transcriptional profiling focused on transcription factors genes provides a facile approach to identifying novel virulence regulators.Author summaryAlthough A. fumigatus causes the majority of cases of invasive aspergillosis, the function of most of the genes in its genome remains unknown. To identify genes encoding transcription factors that may be important for virulence, we used a NanoString nCounter to measure the mRNA levels of A. fumigatus transcription factor genes in the lungs of mice with invasive aspergillosis. The transcriptional profiling data indicate that the organism is exposed to nutrient limitation and stress during growth in the lungs, and that it responds by up-regulating genes that encode mycotoxins and secondary metabolites. In vitro, this response was most closely mimicked by growth in medium that was deficient in nitrogen, iron and/or zinc. Using the transcriptional profiling data, we identified two transcription factors that govern A. fumigatus virulence. These were RlmA, which is governs proliferation in the lung and Ace1, which controls the production of mycotoxins and secondary metabolites.

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In Vitro Activities at pH 5.0 and pH 7.0 and In Vivo Efficacy of Flucytosine against Aspergillus fumigatus

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00491-08 ◽

2008 ◽

Vol 52 (12) ◽

pp. 4483-4485 ◽

Cited By ~ 9

Author(s):

Paul E. Verweij ◽

Debbie T. A. Te Dorsthorst ◽

Willem H. P. Janssen ◽

Jacques F. G. M. Meis ◽

Johan W. Mouton

Keyword(s):

Invasive Aspergillosis ◽

Aspergillus Fumigatus ◽

Murine Model ◽

Antifungal Agent ◽

In Vivo Efficacy

ABSTRACT The antifungal agent flucytosine was found to be active in vitro against Aspergillus fumigatus isolates when the MIC was determined at pH 5.0 instead of pH 7.0. The in vitro MIC at pH 5.0 corresponded to the in vivo efficacy of flucytosine monotherapy in a murine model of invasive aspergillosis.

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Combined Action of Shiga Toxin Type 2 and Subtilase Cytotoxin in the Pathogenesis of Hemolytic Uremic Syndrome

Toxins ◽

10.3390/toxins13080536 ◽

2021 ◽

Vol 13 (8) ◽

pp. 536

Author(s):

Romina S. Álvarez ◽

Fernando D. Gómez ◽

Elsa Zotta ◽

Adrienne W. Paton ◽

James C. Paton ◽

...

Keyword(s):

Shiga Toxin ◽

Cell Damage ◽

Tubular Epithelial Cell ◽

The Body ◽

Epithelial Cell Line ◽

Morphological Alterations ◽

Proximal Tubular ◽

Subtilase Cytotoxin

Shiga toxin-producing E. coli (STEC) produces Stx1 and/or Stx2, and Subtilase cytotoxin (SubAB). Since these toxins may be present simultaneously during STEC infections, the purpose of this work was to study the co-action of Stx2 and SubAB. Stx2 + SubAB was assayed in vitro on monocultures and cocultures of human glomerular endothelial cells (HGEC) with a human proximal tubular epithelial cell line (HK-2) and in vivo in mice after weaning. The effects in vitro of both toxins, co-incubated and individually, were similar, showing that Stx2 and SubAB contribute similarly to renal cell damage. However, in vivo, co-injection of toxins lethal doses reduced the survival time of mice by 24 h and mice also suffered a strong decrease in the body weight associated with a lowered food intake. Co-injected mice also exhibited more severe histological renal alterations and a worsening in renal function that was not as evident in mice treated with each toxin separately. Furthermore, co-treatment induced numerous erythrocyte morphological alterations and an increase of free hemoglobin. This work shows, for the first time, the in vivo effects of Stx2 and SubAB acting together and provides valuable information about their contribution to the damage caused in STEC infections.

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Itraconazole resistance in Aspergillus fumigatus.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.6.1364 ◽

1997 ◽

Vol 41 (6) ◽

pp. 1364-1368 ◽

Cited By ~ 307

Author(s):

D W Denning ◽

K Venkateswarlu ◽

K L Oakley ◽

M J Anderson ◽

N J Manning ◽

...

Keyword(s):

Invasive Aspergillosis ◽

Aspergillus Fumigatus ◽

Dna Analysis ◽

Ergosterol Biosynthesis ◽

Wild Type ◽

Mechanisms Of Resistance ◽

Random Amplification ◽

Susceptible Isolate

Invasive aspergillosis is an increasingly frequent opportunistic infection in immunocompromised patients. Only two agents, amphotericin B and itraconazole, are licensed for therapy. Itraconazole acts through inhibition of a P-450 enzyme undertaking sterol 14alpha demethylation. In vitro resistance in Aspergillus fumigatus to itraconazole correlated with in vivo outcome has not been previously described. For three isolates (AF72, AF90, and AF91) of A. fumigatus from two patients with invasive aspergillosis itraconazole MICs were elevated. A neutropenic murine model was used to establish the validity of the MICs. The isolates were typed by random amplification of polymorphic DNA. Analysis of sterols, inhibition of cell-free sterol biosynthesis from [14C] mevalonate, quantitation of P-450 content, and [3H]itraconazole concentration in mycelial pellets were used to determine the mechanisms of resistance. The MICs for the three resistant isolates were >16 microg/ml. In vitro resistance was confirmed in vivo for all three isolates. Molecular typing showed the isolates from the two patients to be genetically distinct. Compared to the susceptible isolate from patient 1, AF72 had a reduced ergosterol content, greater quantities of sterol intermediates, a similar susceptibility to itraconazole in cell-free ergosterol biosynthesis, and a reduced intracellular [3H]itraconazole concentration. In contrast, AF91 and AF92 had slightly higher ergosterol and lower intermediate sterol concentrations, fivefold increased resistance in cell-free systems to the effect of itraconazole on sterol 14alpha demethylation, and intracellular [3H] itraconazole concentrations found in susceptible isolates. Resistance to itraconazole in A. fumigatus is detectable in vitro and is present in wild-type isolates, and at least two mechanisms of resistance are responsible.

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