Macrophages inhibit Aspergillus fumigatus germination and neutrophil-mediated fungal killing

Rosowski, Emily E.; Raffa, Nicholas; Knox, Benjamin P.; Golenberg, Netta; Keller, Nancy P.; Huttenlocher, Anna

doi:10.1371/journal.ppat.1007229

Cited by 91 publications

(186 citation statements)

References 72 publications

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“…These results suggest that neutrophil recruitment and function at the site of infection are important for controlling A. nidulans infection in both vertebrates. Furthermore, results are in agreement with studies on A. fumigatus which show that virulence is as much a strain-dependent as it is a host-dependent trait (24,37,39,51). Furthermore, the tested phenotypes and genome mutations appear to not correlate with strain virulence, although sample size has to be increased in order to confirm this in future studies.…”

Section: Discussionsupporting

confidence: 90%

“…These results are in agreement with studies in A. fumigatus that have described great strain heterogeneity in traits such as growth, fitness and enzyme secretion between different environmental and clinical isolates (24, 37). Indeed, the number of SNPs, obtained during strain pairwise comparison, in the genomes of different A. fumigatus strains, range between ~13,500 (24) and ~50,000 (38, 39). Strain heterogeneity has therefore mainly been investigated in environmental and clinical isolates of A. fumigatus, whereas similar studies have not been carried out for A. nidulans isolates.…”

Section: Resultsmentioning

confidence: 99%

“…Virulence was first characterized in a variety of in vitro conditions. Macrophages play an essential role in clearing Aspergillus spp conidia from the lung (8), whereas neutrophils are predicted to primarily be responsible for eliminating fungal hyphae (39). To determine whether any strain-specific differences exist in macrophage-mediated phagocytosis and killing, the respective assays were carried out for all three strains in the presence of murine wild-type and gp91phox knockout (CGD) macrophages.…”

Section: Resultsmentioning

confidence: 99%

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Functional characterization of clinical isolates of the opportunistic fungal pathogenAspergillus nidulans

Bastos

Valero²,

Silva³

et al. 2020

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AbstractAspergillus nidulans is an opportunistic fungal pathogen in patients with immunodeficiency and virulence of A. nidulans isolates has mainly been studied in the context of the chronic granulomatous disease (CGD), with characterization of clinical isolates obtained from non-CGD patients remaining elusive. This study therefore carried out a detailed biological characterization of two A. nidulans clinical isolates (CIs), obtained from a patient with breast carcinoma and pneumonia and from a patient with cystic fibrosis that underwent lung transplantation, and compared them to the reference, non-clinical A4 strain. Both CIs presented increased growth in comparison to the reference strain in the presence of physiologically-relevant carbon sources. Metabolomic analyses showed that the three strains are metabolically very different from each other in these carbon sources. Furthermore, the CIs were highly susceptible to cell wall perturbing agents but not to other physiologically-relevant stresses. Genome analyses identified several frame-shift variants in genes encoding cell wall integrity (CWI) signalling components. Significant differences in CWI signalling were confirmed by western blotting among the three strains. In vivo virulence studies using several different models revealed that strain MO80069 had significantly higher virulence in hosts with impaired neutrophil function when compared to the other strains. In summary, this study presents detailed biological characterization of two A. nidulans sensu stricto clinical isolates. Just like in A. fumigatus, strain heterogeneity exists in A. nidulans clinical strains that can define virulence traits. Further studies are required to fully characterize A. nidulans strain-specific virulence traits and pathogenicity.ImportanceImmunocompromised patients are susceptible to infections with opportunistic filamentous fungi from the genus Aspergillus. Although A. fumigatus is the main etiological agent of Aspergillus spp.-related infections, other species, such as A. nidulans are prevalent in a condition-specific manner. A. nidulans is a predominant infective agent in patients suffering from chronic granulomatous disease (CGD). A. nidulans isolates have mainly been studied in the context of CGD, although infection with A. nidulans also occurs in non-CGD patients. This study carried out a detailed biological characterization of two non-CGD A. nidulans clinical isolates and compared it to a reference strain. Phenotypic, metabolomic and genomic analyses highlight fundamental differences in carbon source utilization, stress responses and maintenance of cell wall integrity among the strains. One clinical strain had increased virulence in models with impaired neutrophil function. Just as in A. fumigatus, strain heterogeneity exists in A. nidulans clinical strains that can define virulence traits.

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Section: Discussionsupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Functional characterization of clinical isolates of the opportunistic fungal pathogenAspergillus nidulans

Bastos

Valero²,

Silva³

et al. 2020

Preprint

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“…It is only when dormancy is broken and germination occurs that this surface layer is breached and host defenses are activated 17 . Other studies in immunosuppressed mice showed that an A. fumigatus isolate with slower germination survived in macrophages and was more virulent than an isolate with faster germination 18,19 . A bet-hedging strategy built on variation in germination rate could allow slow germinators within a population of A. fumigatus conidia to avoid the host immune system and initiate infection.…”

mentioning

confidence: 96%

Sporulation environment drives phenotypic variation in the pathogenAspergillus fumigatus

Kang

Momany

2019

Preprint

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8Aspergillus fumigatus causes more than 300,000 life-threatening infections annually and is widespread across 9 varied environments with a single colony producing thousands of conidia, genetically-identical dormant spores. 10 Conidia are easily wind-dispersed to new environments where they can germinate and, if inhaled by susceptible 11 hosts, cause disease. Using high-throughput, single-cell analysis we show that germination phenotypes vary 12 among genetically-identical individuals and that the environment of spore production determines the degree of 13 germination heterogeneity. 15Fungal diseases kill over 1.5 million people each year 1, 2 . Rather than spreading patient-to-patient, fungal diseases 16 are acquired from the environment or normal flora. Nine of the ten most common agents of fungal disease can be 17 spread via spores 2, 3 . Breaking dormancy, or germinating, is arguably the most important step in pathogenesis for 18 these fungi. Historically studies have focused on the germination environment, addressing factors such as 19 temperature, inoculum density, carbon source, nitrogen source, and pH 4-8 . However, despite the wide range of 20 environments in which fungal spores are produced and their importance as disease agents, the impact of 21 sporulation environment on germination has been largely ignored. We hypothesized that exposure to specific 22 Dormant conidia produced in all sporulation environments showed very similar forward scatter profiles except for 40 conidia produced at 50C, in which the forward scatter peak shifted slightly to the right, suggesting a larger size. 41 Microscopic examination showed that conidia produced at 37°C were approximately 2-3 µm in diameter, while 42 those produced at 50°C were approximately 1.5 times larger ( Supplementary Fig. 2). 43 44 Not surprisingly, the rate at which conidia broke dormancy and grew varied depending on germination conditions. 45 Conidia germinated in standard media containing sufficient metals (CM, MM) at optimal temperature (37C) 46 showed larger median forward scatter values than conidia germinated in media with metal limitation (-Zn, -Fe), at 47 d Pearson correlation analysis between median forward scatter and observed variation (rCV) within a germination group. r = 62 correlation coefficient.63 e The Kruskall-Wallis test determines whether there is a difference in distribution between multiple groups and is performed on 64 ranked data. H = the Kruskall-Wallis statistic, an indication of the difference between groups; df = degrees of freedom. The p 65 values indicate significance of differences among sporulation environments in the germination condition.66 f Mean rank from Kruskal-Wallis test indicates which sporulation conditions tend to have the greatest values in the germination 67 group.68 g Dunn's multiple comparison test. Mean rank for each sporulation environment in the same germination condition was 69compared to the mean rank of the same sporulation and germination conditions. Dunn's test compares the diff...

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“…We find that A. nidulans is 237 significantly more virulent than A. fumigatus in p22 -/larvae but not in a generally 238 immunocompromised or neutropenic host.Interestingly, A. fumigatus caused only a low level of 239 death in p22 -/larvae despite being the most frequently isolated fungus from CGD patients (King 240 et al, 2016). The relatively weak virulence of A. fumigatus could be a result of strain variation, 241 which can have a significant impact on host survival (Amarsaikhan et al, 2014, Knox et al, 2016, 242 Kowalski et al, 2016,Rizzetto et al, 2013, Rosowski et al, 2018. Remarkably, rescuing p22 phox 243 function specifically in neutrophils was sufficient to reduce invasive fungal growth but did not 244 affect spore germination.…”

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confidence: 99%

Imaging invasive fungal growth and inflammation in NADPH oxidase-deficient zebrafish

Schoen

Rosowski

Knox

et al. 2019

Preprint

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28Neutrophils are primary cells of the innate immune system that generate reactive oxygen species 29 (ROS) and mediate host defense. Deficient phagocyte NADPH oxidase (PHOX) function leads to 30 chronic granulomatous disease (CGD) that is characterized by invasive infections including those 31 by the generally non-pathogenic fungus Aspergillus nidulans. The role of neutrophil ROS in this 32 specific host-pathogen interaction remains unclear. Here, we exploit the optical transparency of 33 zebrafish to image the effects of neutrophil ROS on invasive fungal growth and neutrophil 34 behavior in response to Aspergillus nidulans. In a wild-type host, A. nidulans germinates rapidly 35 and elicits a robust inflammatory response with efficient fungal clearance. PHOX-deficient larvae 36 have increased susceptibility to invasive A. nidulans infection despite robust neutrophil infiltration. 37

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Macrophages inhibit Aspergillus fumigatus germination and neutrophil-mediated fungal killing

Cited by 91 publications

References 72 publications

Functional characterization of clinical isolates of the opportunistic fungal pathogenAspergillus nidulans

Functional characterization of clinical isolates of the opportunistic fungal pathogenAspergillus nidulans

Sporulation environment drives phenotypic variation in the pathogenAspergillus fumigatus

Imaging invasive fungal growth and inflammation in NADPH oxidase-deficient zebrafish

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