Amino sugars influence Aspergillus fumigatus cell wall polysaccharide biosynthesis, and biofilm formation through interfering galactosaminogalactan deacetylation

Aspergillus fumigatus is a ubiquitous fungal pathogen responsible for a significant number of deaths annually due to invasive aspergillosis infection. While the utilization of diverse carbon sources, including amino sugars, has been explored in other fungi, its impact on A. fumigatus remains uncharted territory. In this study, we investigated A. fumigatus responses to glucose (Glc), glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) as carbon sources. GlcN inhibited growth, reduced sporulation and delayed germination, while GlcNAc had no such effects. Both amino sugars induced alterations in cell wall composition, leading to a reduction in glucan and galactomannan levels while increasing chitin and mannan content, rendering A. fumigatus susceptible to cell wall stress and osmotic stress. GlcN repressed biofilm formation via downregulation of galactosaminogalactan (GAG) cluster genes, notably agd3, which encodes a GAG-specific deacetylase. Moreover, GlcN increased biofilm susceptibility to echinocandins, suggesting its potential for enhancing the effectiveness of antifungal treatments. This study sheds light on the multifaceted effects of amino sugars on A. fumigatus, encompassing growth, cell wall biosynthesis, and biofilm formation, offering promising avenues for innovative aspergillosis treatment strategies.

Fungal chitin-binding glycoprotein induces Dectin-2-mediated allergic airway inflammation synergistically with chitin

Although chitin in fungal cell walls is associated with allergic airway inflammation, the precise mechanism underlying this association has yet to be elucidated. Here, we investigated the involvement of fungal chitin-binding protein and chitin in allergic airway inflammation. Recombinant Aspergillus fumigatus LdpA (rLdpA) expressed in Pichia pastoris was shown to be an O-linked glycoprotein containing terminal α-mannose residues recognized by the host C-type lectin receptor, Dectin-2. Chitin particles were shown to induce acute neutrophilic airway inflammation mediated release of interleukin-1α (IL-1α) associated with cell death. Furthermore, rLdpA-Dectin-2 interaction was shown to promote phagocytosis of rLdpA-chitin complex and activation of mouse bone marrow-derived dendritic cells (BMDCs). Moreover, we showed that rLdpA potently induced T helper 2 (Th2)-driven allergic airway inflammation synergistically with chitin, and Dectin-2 deficiency attenuated the rLdpA-chitin complex-induced immune response in vivo. In addition, we showed that serum LdpA-specific immunoglobulin levels were elevated in patients with pulmonary aspergillosis.

Most Azole-Susceptible Isolates of Aspergillus fumigatus in Hokkaido, Japan are Clustered with Worldwide Strains That Do Not Have Tandem Repeats in Cyp51A Promoter

In this study, we analyzed Aspergillus fumigatus short tandem repeat patterns of 106 strains isolated from the outdoor air, clinical specimens, and king penguins (Aptenodytes patagonicus) with aspergillosis in Japan, and compared them with those of 668 strains from AfumID (including six isolates from Japan). The results showed that the isolates were classified into three major groups. Group II contained most of the azole-resistant strains with 34- and 46-bp tandem repeats in cyp51A promoter. As in our previous study, OKH50 and Env1 strains were classified in Group II. Most of the azole-susceptible strains obtained in Japan were classified in Group III.

Rare occurrence of pulmonary coinfection involving Aspergillus fumigatus and Nocardia cyriacigeorgica in immunocompetent patients based on NGS: A case report and literature review

RATIONALE

In our search on PubMed, we found that reports of co-infections involving Aspergillus fumigatus and Nocardia cyriacigeorgica in the literature are notably scarce. Most cases have been documented in patients with compromised immune systems or underlying pulmonary conditions. In contrast, our patient did not present with any of these risk factors. Furthermore, there have been no recent incidents such as near-drowning or other accidents in the patient history. To the best of our knowledge, this case represents a hitherto unreported clinical scenario. To enhance comprehension, we conducted a comprehensive literature review by compiling a total of 20 case reports (spanning from 1984 to 2023) on co-infections involving Aspergillus and Nocardia species, retrieved from PubMed.

PATIENT CONCERNS AND DIAGNOSIS

Chest CT revealed the presence of multiple nodules and clustered high-density shadows in both lungs. Bronchoscopy revealed mucosal congestion and edema in the apical segment of the right upper lobe of the lung, along with the presence of 2 spherical polypoid new organisms. The pathological analysis reported severe chronic inflammation with evidence of Aspergillus within the tissue. Next-Generation Sequencing of bronchoalveolar lavage fluid revealed the presence of reads corresponding to A fumigatus and N cyriacigeorgica. Positive cultures for A fumigatus and the Nocardia genus were yielded by prolonging the incubation of samples in the microbiology laboratory.

INTERVENTIONS

Treatment with voriconazole for A fumigatus and sulfamethoxazole-trimethoprim for N cyriacigeorgica infection was given.

OUTCOMES

The patient improved and was discharged. After 6 months of telephone follow-up, the patient reported no clinical symptoms, discontinued the medication on his own.

LESSONS

A fumigatus and N cyriacigeorgica can manifest as a co-infection in immunocompetent patients. Clinicians should prioritize the significant advantages and value of NGS in detecting rare and mixed pathogens associated with pulmonary infections.

Development of a murine model to study the cerebral pathogenesis of Aspergillus fumigatus

IMPORTANCE

Molds are environmental fungi that can cause disease in immunocompromised individuals. The most common pathogenic mold is Aspergillus fumigatus, which is typically inhaled into the lungs and causes invasive pulmonary disease. In a subset of these patients, this infection can spread from the lungs to other organs including the brain, resulting in cerebral aspergillosis. How A. fumigatus causes brain disease is not well understood and these infections are associated with extremely high mortality rates. Thus, we developed an animal model to study the pathogenesis of cerebral aspergillosis to better understand this disease and develop better treatments for these life-threatening infections.

Endocarditis caused by Aspergillus fumigatus in a patient 9 months after COVID-19 infection recovery: a case report and review of the literature

BACKGROUND

Aspergillus spp. are among the fungal pathogens that can cause life-threatening infections in patients with a history of COVID-19.

CASE PRESENTATION

We present the case of a 58-year-old Iranian woman with post-COVID-19 Aspergillus fumigatus endocarditis complicated by numerous thromboembolisms. She underwent mitral valve replacement surgery and multiple lower extremity embolectomies and was treated with voriconazole, which led to her final recovery.

CONCLUSIONS

Aspergillus endocarditis should be considered in any patient with suspected endocarditis who has a history of COVID-19 infection and does not respond to routine antibiotic and antifungal therapy, as COVID-19 interferes with proper immune function, and lack of underlying cardiac conditions and immunodeficiencies does not preclude the diagnosis. Culture and histopathological evaluation of vegetations and emboli, as well as PCR, can confirm the diagnosis. Early initiation of antifungal therapy and surgical removal of infected valves and emboli can improve prognosis in patients with Aspergillus endocarditis.

Aspergillus Enhances Eosinophil and Neutrophil Extracellular DNA Trap Formation in Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is characterized by inflammatory cell infiltration in the sinonasal mucosa. Eosinophil and neutrophil extracellular traps (EETs and NETs, respectively) are prominently found in CRS. This study aimed to investigate the effect of airborne fungi, Alternaria alternata and Aspergillus fumigatus, on EET and NET formation. Nasal epithelial cells, eosinophils, and neutrophils were isolated from eosinophilic CRS (ECRS), non-ECRS (NECRS), and healthy control. We determined eosinophil and neutrophil transepithelial migration after fungal treatment. We then determined the release of EETs and NETs by fungi using Sytox Green staining and determined the role of reactive oxygen species (ROS) using ROS inhibitors. We identified more abundant EETs and NETs in ECRS than in NECRS. A. alternata and A. fumigatus enhanced eosinophil and neutrophil transepithelial migration. A. fumigatus strongly induced EET and NET formation in CRS and, simultaneously, suppressed fungal metabolic activity. EET formation in CRS is associated with nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase and NET formation with NADPH-oxidase and mitochondrial ROS. A. fumigatus, but not A. alternata, induced EET and NET formation, and peripheral blood eosinophils and neutrophils exhibited different immune responses against A. fumigatus following the inflammatory status of the host. Aspergillus-fumigatus-induced EET and NET formation plays a crucial role in CRS pathogenesis.

Biochemical Characterization of Thermostable Acrylamide Amidohydrolase from Aspergillus fumigatus with Potential Activity for Acrylamide Degradation in Various Food Products

Acrylamide is the major by-product of the Maillard reactions in foods with the overheating processes of L-asparagine-rich foods with reducing sugars that usually allied with neurotoxicity and carcinogenicity. Several approaches have been used to prevent the formation of acrylamide, however, degrading the already formed acrylamide in foods remains unequivocal. Acrylamide hydrolyzing enzyme "amidohydrolase" is one of the most promising enzymes for acrylamide degradation in foods. So, amidohydrolase "amidase" from thermotolerant Aspergillus fumigatus EFBL was purified to their electrophoretic homogeneity by gel-filtration and ion-exchange chromatography, with overall purification folds 2.8 and yield 9.43%. The apparent molecular subunit structure of the purified A. fumigatus amidase was 50 kDa, with highest activity at reaction temperature of 40 °C and pH of 7.5 The enzyme displayed a significant thermal stability as revealed from the value of T1/2 (13.37 h), and thermal denaturation rate (Kr 0.832 × 10-3 min) at 50 °C, with metalloproteinic identity. The purified enzyme had a significant activity for acrylamide degradation in various food products such as meat, cookies, potato chips, and bread as revealed from the HPLC analysis and LC-MS analysis. So, with the purified amidase, the acrylamide in the food products was degraded by about 95% to acrylic acid, ensuring the possibility of using this enzyme in abolishing the toxic acrylamide in the foods products. This is the first report exploring the potency of A. fumigatus amidase for an actual degradation of acrylamide in foods efficiently. Further biochemical analyses are ongoing to assess the affinity of this enzyme for selective hydrolyses of acrylamide in foods, without affecting the beneficial stereochemical related compounds.

Coronavirus disease 2019 (COVID-19)-associated brain abscesses caused by Pseudomonas aeruginosa and Aspergillus fumigatus: two case and a review of the literature

BACKGROUND

Bacterial and fungal superinfections are commonly reported in patients with coronavirus disease 2019.

CASE PRESENTATION

We report the first case of brain and intramedullary abscesses caused by Pseudomonas aeruginosa and a rare case of brain abscesses caused by Aspergillus fumigatus in two post-coronavirus disease 2019 patients. The first patient-34-year-old Iranian woman-presented with weakness of the left upper limb, headaches, and lower limb paresthesia. She had a history of undiagnosed diabetes and had received corticosteroid therapy. The second patient-45-year-old Iranian man-presented with right-sided weakness and had a history of intensive care unit admission. Both patients passed away despite appropriate medical therapy.

CONCLUSION

The immune dysregulation induced by coronavirus disease 2019 and its' treatments can predispose patients, especially immunosuppressed ones, to bacterial and fungal infections with unusual and opportunistic pathogens in the central nervous system. Pseudomonas aeruginosa and Aspergillus fumigatus should be considered as potential causes of brain infection in any coronavirus disease 2019 patient presenting with neurological symptoms and evidence of brain abscess in imaging, regardless of sinonasal involvement. These patients should get started on appropriate antimicrobial therapy as soon as possible, as any delay in diagnosis or treatment can be associated with adverse outcomes.

The rapid emergence of antifungal-resistant human-pathogenic fungi

During recent decades, the emergence of pathogenic fungi has posed an increasing public health threat, particularly given the limited number of antifungal drugs available to treat invasive infections. In this Review, we discuss the global emergence and spread of three emerging antifungal-resistant fungi: Candida auris, driven by global health-care transmission and possibly facilitated by climate change; azole-resistant Aspergillus fumigatus, driven by the selection facilitated by azole fungicide use in agricultural and other settings; and Trichophyton indotineae, driven by the under-regulated use of over-the-counter high-potency corticosteroid-containing antifungal creams. The diversity of the fungi themselves and the drivers of their emergence make it clear that we cannot predict what might emerge next. Therefore, vigilance is critical to monitoring fungal emergence, as well as the rise in overall antifungal resistance.

Senkyunolide B exhibits broad-spectrum antifungal activity against plant and human pathogenic fungi via inhibiting spore germination and destroying the mature biofilm

BACKGROUND

Aspergillus infection seriously jeopardizes the health and safety of life of immunocompromised patients. The emergences of antifungal resistance highlight a demand to find new effective antifungal drugs. Angelica sinensis is a medicine-food herb and phthalides are its characteristic components. A few of the phthalides have been reported to display satisfactory antifungal activities against plant pathogenic fungi. However, the structure-activity relationships and antifungal action mechanism of phthalides remain to be further explored and elucidated.

RESULTS

The antifungal activities of five natural phthalides and four artificial analogs were investigated, and their structure-activity relationships were preliminarily elucidated in the current study. The benzene ring moiety played an essential role in their antifungal activities; the oxygen-containing substituents on the benzene ring obviously impacted their activities, the free hydroxyl was favorable to the activity. Typical phthalide senkyunolide B (SENB) exhibited broad antifungal activities against human and plant pathogenic fungi, especially, Aspergillus fumigatus. SENB affected the spore germination and hyphae growth of Aspergillus fumigatus via down-regulating phosphatidylinositol-PKC-calcineurin axis and the expression of ENG genes. Moreover, SENB disturbed the oxidation-reduction process in Aspergillus fumigatus to destroy the mature biofilms. In vivo experiments indicated SENB significantly prolonged survival and decreased fungal burden in mouse model of invasive pulmonary aspergillosis.

CONCLUSIONS

Phthalides could be considered as the valuable leads for the development of antifungal drug to cure plant and human disease. © 2023 Society of Chemical Industry.

Optimization of the EUCAST reference broth microdilution method for echinocandin susceptibility testing of Aspergillus fumigatus

BACKGROUND

Because of the high inoculum (105 cfu/mL) used in the EUCAST susceptibility testing of Aspergillus spp., determination of the minimal effective concentration (MEC) of echinocandins is challenging as the morphological differences are subtle.

METHODS

The MECs of 10 WT and 4 non-WT Aspergillus fumigatus isolates were determined with the EUCAST E.Def 9.4. Plates were inoculated with increasing inocula (102-105 cfu/mL) and after 24 and 48 h of incubation, MECs were determined macroscopically (magnifying mirror) and microscopically (inverted microscope) by two observers, spectrophotometrically (OD at 405 nm) and colorimetrically (absorbance at 450/630 nm after 2 h incubation with 400 mg/L XTT/6.25 μM menadione). The interobserver (between observers)/intermethod (compared with the microscopic method) essential agreement (EA, ±1 2-fold dilution) and categorical agreement (CA) were determined for each inoculum.

RESULTS

Echinocandin-induced microscopic hyphal alterations or macroscopic changes in turbidity were subtle with a 105 cfu/mL inoculum compared with the lower inocula of 103 and 102 cfu/mL, where more distinct changes in turbidity and formation of characteristic rosettes were obvious at the MEC after 48 h. A 105 cfu/mL inoculum resulted in wider MEC distributions (3-6 dilutions) and lower interobserver EA (69%), macroscopic-microscopic EA (26%) and CA (71%) compared with a 103 cfu/mL inoculum (2-3 dilutions, 100%, 100% and 100%, respectively). Spectrophotometric readings using a 103 cfu/mL inoculum showed good EA (57-93%) and excellent CA (86%-100%), while the XTT assay demonstrated excellent EA (93%) and CA (100%).

CONCLUSIONS

A 48 h incubation using a 103 cfu/mL inoculum improved echinocandin MEC determination for A. fumigatus with the EUCAST method, while the colorimetric assay could allow automation.

Pathogenicity and virulence of Aspergillus fumigatus

Pulmonary infections caused by the mould pathogen Aspergillus fumigatus are a major cause of morbidity and mortality globally. Compromised lung defences arising from immunosuppression, chronic respiratory conditions or more recently, concomitant viral or bacterial pulmonary infections are recognised risks factors for the development of pulmonary aspergillosis. In this review, we will summarise our current knowledge of the mechanistic basis of pulmonary aspergillosis with a focus on emerging at-risk populations.

Unveiling antibacterial and antioxidant activities of zinc phosphate-based nanosheets synthesized by Aspergillus fumigatus and its application in sustainable decolorization of textile wastewater

BACKGROUND

The development of an environment-friendly nanomaterial with promising antimicrobial and antioxidant properties is highly desirable. The decolorization potentiality of toxic dyes using nanoparticles is a progressively serious worldwide issue.

METHODS

The successful biosynthesis of zinc nanoparticles based on phosphates (ZnP-nps) was performed using the extracellular secretions of Aspergillus fumigatus. The antibacterial activity of the biosynthetic ZnP-nps was investigated against Gram-negative bacteria and Gram-positive bacteria using the agar diffusion assay method. The antioxidant property for the biosynthetic nanomaterial was evaluated by DPPH and H2O2 radical scavenging assay.

RESULTS

Remarkable antibacterial and antiradical scavenging activities of ZnP-nps were observed in a dose-dependent manner. The minimum inhibitory concentration (MIC) for Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was 25 µg/ml, however, the MIC for Bacillus subtilis was 12.5 µg/ml. The maximum adsorptive performance of nanomaterial was respectively achieved at initial dye concentration of 200 mg/L and 150 mg/L using methylene blue (MB) and methyl orange (MO), where sorbent dosages were 0.5 g for MB and 0.75 g for MB; pH was 8.0 for MB and 4.0 for MO; temperature was 30 °C; contact time was 120 min. The experimental data was better obeyed with Langmuir's isotherm and pseudo-second-order kinetic model (R2 > 0.999). The maximum adsorption capacity (qmax) of MB and MO dyes on nanomaterial were 178.25 mg/g and 50.10 mg/g, respectively. The regenerated nanomaterial, respectively, persist > 90% and 60% for MB and MO after 6 successive cycles. The adsorption capacity of the prepared zinc phosphate nanosheets crystal toward MB and MO, in the present study, was comparable/superior with other previously engineered adsorbents.

CONCLUSIONS

Based on the above results, the biosynthesized ZnP-nanosheets are promising nanomaterial for their application in sustainable dye decolorization processes and they can be employed in controlling different pathogenic bacteria with a potential application as antiradical scavenging agent. Up to our knowledge, this is probably the first study conducted on the green synthesis of ZnP-nanosheets by filamentous fungus and its significant in sustainable dye decolorization.

Evolution of neuroimaging findings in angioinvasive cerebral aspergillosis in a pediatric patient with leukemia during long-term observation

The central nervous system is one of the most common sites of aspergillosis involvement in immunocompromised people, just after sinopulmonary infections. Neuroimaging modalities are crucial for the diagnosis of cerebral aspergillosis (CA). Here, we describe a rare case of concurrent mixed aspergillosis infection with Aspergillus fumigatus and Aspergillus niger in a 2-year-old leukemic boy. The first neuroimaging finding, which was followed by focal seizures, was recognized as extensive cerebral hemorrhage in the absence of thrombocytopenia and coagulopathy. As the patient survived for more than 4 months after diagnosis, we were able to perform a neuroimaging evaluation during long-term observation. In serial neuroimaging studies, a secondary fungal abscess was observed at the site of hemorrhagic infarctions. Finally, the patient died from bacterial sepsis. In this case study, we try to categorize the neuroimaging findings of CA into distinct phases to better understand how CA changes over time.

Dectin-1/CARD9 induction of the TFEB and TFE3 gene network is dispensable for phagocyte anti-Aspergillus activity in the lung

Myeloid phagocytes of the respiratory immune system, such as neutrophils, monocytes, and alveolar macrophages, are essential for immunity to Aspergillus fumigatus, the most common etiologic agent of mold pneumonia worldwide. Following the engulfment of A. fumigatus conidia, fusion of the phagosome with the lysosome is a critical process for killing conidia. TFEB and TFE3 are transcription factors that regulate lysosomal biogenesis under stress and are activated by inflammatory stimuli in macrophages, but it is unknown whether TFEB and TFE3 contribute to anti-Aspergillus immunity during infection. We found that lung neutrophils express TFEB and TFE3, and their target genes were upregulated during A. fumigatus lung infection. In addition, A. fumigatus infection induced nuclear accumulation of TFEB and TFE3 in macrophages in a process regulated by Dectin-1 and CARD9. Genetic deletion of Tfeb and Tfe3 impaired macrophage killing of A. fumigatus conidia. However, in a murine immune-competent Aspergillus infection model with genetic deficiency of Tfeb and Tfe3 in hematopoietic cells, we surprisingly found that lung myeloid phagocytes had no defects in conidial phagocytosis or killing. Loss of TFEB and TFE3 did not impact murine survival or clearance of A. fumigatus from the lungs. Our findings indicate that myeloid phagocytes activate TFEB and TFE3 in response to A. fumigatus, and while this pathway promotes macrophage fungicidal activity in vitro, genetic loss can be functionally compensated in the lung, resulting in no measurable defect in fungal control and host survival.

Drosophila melanogaster as an organism model for studying cystic fibrosis and its major associated microbial infections

Cystic fibrosis (CF) is a human genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene that encodes a chloride channel. The most severe clinical manifestation is associated with chronic pulmonary infections by pathogenic and opportunistic microbes. Drosophila melanogaster has become the invertebrate model of choice for modeling microbial infections and studying the induced innate immune response. Here, we review its contribution to the understanding of infections with six major pathogens associated with CF (Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia, Mycobacterium abscessus, Streptococcus pneumoniae, and Aspergillus fumigatus) together with the perspectives opened by the recent availability of two CF models in this model organism.

The cytochrome P450 reductase CprA is a rate-limiting factor for Cyp51A-mediated azole resistance in Aspergillus fumigatus

Azole antifungals remain the "gold standard" therapy for invasive aspergillosis. The world-wide emergence of isolates resistant to this drug class, however, developed into a steadily increasing threat to human health over the past years. In Aspergillus fumigatus, major mechanisms of resistance involve increased expression of cyp51A encoding one of two isoenzymes targeted by azoles. Yet, the level of resistance caused by cyp51A upregulation, driven by either clinically relevant tandem repeat mutations within its promoter or the use of high expressing heterologous promoters, is limited. Cytochrome P450 enzymes such as Cyp51A rely on redox partners that provide electrons for their activity. A. fumigatus harbors several genes encoding putative candidate proteins including two paralogous cytochrome P450 reductases, CprA and CprB, and the cytochrome b 5 CybE. In this work, we investigated the contribution of each cprA, cprB, and cybE overexpression to cyp51A-mediated resistance to different medical and agricultural azoles. Using the bidirectional promoter PxylP, we conditionally expressed these genes in combination with cyp51A, revealing cprA as the main limiting factor. Similar to this approach, we overexpressed cprA in an azole-resistant background strain carrying a cyp51A allele with TR34 in its promoter, which led to a further increase in its resistance. Employing sterol measurements, we demonstrate an enhanced eburicol turnover during upregulation of either cprA or cyp51A, which was even more pronounced during their simultaneous overexpression. In summary, our work suggests that mutations leading to increased Cyp51A activity through increased electron supply could be key factors that elevate azole resistance.

Occurrence of Aspergillus fumigatus azole resistance in soils from Switzerland

Aspergillus fumigatus is a fungal species causing diverse diseases in humans. The use of azoles for treatments of A. fumigatus diseases has resulted in azole resistance. Azoles are also widely used in the environment for crop protection, which resulted in azole resistance. Resistance is primarily due to mutations in cyp51A, which encodes the target protein for azoles. Here we addressed the occurrence of azole resistance in soils from a vast part of Switzerland. We aimed to associate the use of azoles in the environment with the occurrence of azole resistance. We targeted sample sites from different agricultural environments as well as sites with no agricultural practice (natural sites and urban sites). Starting from 327 sites, 113 A. fumigatus isolates were recovered (2019-2021), among which 19 were azole-resistant (15 with TR34/L98H and four with TR46/Y121F/T289A resistance mutations in cyp51A). Our results show that azole resistance was not associated with a specific agricultural practice. Azoles could be chemically detected in investigated soils, however, their presence was not associated with the occurrence of azole-resistant isolates. Interestingly, genetic markers of resistance to other fungicides were detected but only in azole-resistant isolates, thus reinforcing the notion that A. fumigatus cross-resistance to fungicides has an environmental origin. In conclusion, this study reveals the spreading of azole resistance in A. fumigatus from the environment in Switzerland. The proximity of agricultural areas to urban centers may facilitate the transmission of resistant strains to at-risk populations. Thus, vigilant surveillance is required to maintain effective treatment options for aspergillosis.

Quercetin protects against Aspergillus fumigatus keratitis by reducing fungal load and inhibiting TLR-4 induced inflammatory response

PURPOSE

To investigate the antifungal and anti-inflammatory effects of quercetin in Aspergillus fumigatus (A. fumigatus) keratitis.

METHODS

Draize eye test was performed in mice to evaluate the toxicity of quercetin, and the antifungal effects on A. fumigatus were assessed via scanning electron microscopy (SEM), propidium iodide uptake, and adherence assay. In fungal keratitis (FK) mouse models, immunostaining was performed for investigating toll-like receptor 4 (TLR-4) expression and macrophage infiltration. Real-time PCR, ELISA, and Western blot were used to evaluate the expression of pro-inflammatory factors IL-1β, TNF-α, and IL-6 in infected RAW264.7 cells. Cells were also treated with TLR-4 siRNA or agonist CRX-527 to investigate mechanisms underlying the anti-inflammatory activity of quercetin.

RESULTS

Quercetin at 32 μM was non-toxic to corneal epithelial and significantly inhibited A. fumigatus growth and adhesion, and also altered the structure and reduced the number of mycelia. Quercetin significantly reduced macrophage infiltration in the mouse cornea, and attenuated the expression of TLR-4 in the corneal epithelium and stroma of mice with keratitis caused by A. fumigatus. In RAW264.7 cells infected by A. fumigatus, quercetin downregulated TLR-4 along with pro-inflammatory factors IL-1β, TNF-α, and IL-6. RAW cells with TLR-4 knockdown had reduced expression of factors after A. fumigatus infection, which was decreased even further with quercetin treatment. In contrast, cells with CRX-527 had elevated inflammatory factors compared to control, which was significantly attenuated in the presence of quercetin.

CONCLUSION

Quercetin plays a protective role in mouse A. fumigatus keratitis by inhibiting fungal load, disrupting hyphae structure, macrophage infiltration, and suppressing inflammation response in macrophages via TLR-4 mediated signaling pathway.

Lung microbiota changes during pulmonary Aspergillus fumigatus infection in rats

Since the realization that the lungs are not sterile but are normally inhabited by various bacterial species, studies have been conducted to define healthy lung microbiota and to investigate whether it changes during lung diseases, infections, and inflammation. Using next-generation sequencing, we investigated bacterial microbiota from whole lungs in two rat strains (previously shown to differ in gut microbiota composition) in a healthy state and during pulmonary infection caused by the opportunistic fungus Aspergillus fumigatus. No differences in alpha diversity indices and microbial composition between DA and AO rats before infection were noted. Fungal infection caused dysbiosis in both rat strains, characterized by increased alpha diversity indices and unchanged beta diversity. The relative abundance of genera and species was increased in DA but decreased in AO rats during infection. Changes in lung microbiota coincided with inflammation (in both rat strains) and oxidative stress (in DA rats). Disparate response of lung microbiota in DA and AO rats to pulmonary fungal infection might render these two rat strains differentially susceptible to a subsequent inflammatory insult.

Long-term follow-up of allergic bronchopulmonary aspergillosis treated with glucocorticoids: A study of 182 subjects

BACKGROUND

The long-term outcomes of allergic bronchopulmonary aspergillosis (ABPA) are poorly characterised.

METHODS

We retrospectively included treatment-naïve subjects of acute stage ABPA-complicating asthma from three randomised trials. All the subjects received oral prednisolone for 4 months and were monitored every 6 weeks for 6 months and then every 6 months. Our primary objective was to estimate the incidence rate and the frequency of subjects experiencing ABPA exacerbation. The key secondary objectives were to evaluate the factors predicting ABPA exacerbation and the changes in serum total IgE seen during treatment.

RESULTS

We included 182 subjects. Eighty-one (44.5%) patients experienced 120 exacerbations during 512 patient-years of follow-up. The incidence rate of ABPA exacerbations was 234/1000 patient-years. Most (73/81, 90.1%) subjects experienced ABPA exacerbation within three years of stopping therapy. On multivariate logistic regression analysis, peripheral blood eosinophil count ≥1000 cells/μL (adjusted odds ratio [aOR] 2.43; 95% confidence interval (CI), 1.26-4.67), the extent of bronchiectasis (aOR 1.10; 95% CI, 1.03-1.18), age (aOR 0.97; 95% CI, 0.94-0.99), and female sex (aOR 2.16; 95% CI, 1.10-4.24) independently predicted ABPA exacerbation after adjusting for serum total IgE and high-attenuation mucus. The best cut-off for serum total IgE after 6 weeks for identifying treatment response and ABPA exacerbations was a 20% decline and a 50% increase, respectively.

CONCLUSIONS

ABPA exacerbations were common within 3 years of stopping treatment. Age, female sex, peripheral blood eosinophilia and the extent of bronchiectasis predicted ABPA exacerbations. The optimal serum total IgE cut-off for defining ABPA response and exacerbations is a 20% decline and a 50% increase, respectively.

Systemic aspergillosis associated with acute enterocolitis in foals

Aspergillosis is an uncommon disease in horses, but it can be fatal. We report two cases of systemic aspergillosis in foals that occurred in a short period in the same region of southern Brazil. In addition, a literature review of similar cases was also performed. Risk factors were attributed to an immunodepression by primary enterocolitis and corticosteroid treatment, the damage in the epithelium, and multiple antibacterial treatments, which allowed local fungal proliferation, tissue invasion and spread of infection, leading to death. Since the antemortem diagnosis of aspergillosis in foals is difficult, our report alerts equine veterinarians regarding the importance of suspecting and investigating fungal co-infections in complicated cases of enterocolitis.

Dysregulated pulmonary inflammatory responses exacerbate the outcome of secondary aspergillosis following influenza

IMPORTANCE

Severe influenza is a risk factor for fatal invasive pulmonary aspergillosis; however, the mechanistic basis for the lethality is unclear. Utilizing an influenza-associated pulmonary aspergillosis (IAPA) model, we found that mice infected with influenza A virus followed by Aspergillus fumigatus had 100% mortality when superinfected during the early stages of influenza but survived at later stages. While superinfected mice had dysregulated pulmonary inflammatory responses compared to controls, they had neither increased inflammation nor extensive fungal growth. Although influenza-infected mice had dampened neutrophil recruitment to the lungs following subsequent challenge with A. fumigatus, influenza did not affect the ability of neutrophils to clear the fungi. Our data suggest that the lethality seen in our model of IAPA is multifactorial with dysregulated inflammation being a greater contributor than uncontrollable microbial growth. If confirmed in humans, our findings provide a rationale for clinical studies of adjuvant anti-inflammatory agents in the treatment of IAPA.