The immune interplay between the host and the pathogen in Aspergillus fumigatus lung infection

Pulmonary Aspergillosis in People with Cystic Fibrosis

In the last decade, fungal respiratory diseases have been increasingly investigated for their impact on the clinical course of people with cystic fibrosis (CF), with a particular focus on infections caused by Aspergillus spp. The most common organisms from this genus detected from respiratory cultures are Aspergillus fumigatus and Aspergillus terreus, followed by Aspergillus flavus, Aspergillus niger, and Aspergillus nidulans. These species have been identified to be both chronic colonizers and sources of active infection and may negatively impact lung function in people with CF. This review article discusses definitions of aspergillosis, challenges in clinical practice, and current literature available for laboratory findings, clinical diagnosis, and treatment options for pulmonary diseases caused by Aspergillus spp. in people with CF.

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.

Instillation of Amphotericin B by bronchoscopy combined with systemic voriconazole in advanced non-small cell lung cancer patients with chronic cavitary pulmonary aspergillosis: A case series and literature review

Although the treatment of aspergillosis has been studied for years, the optimal nonsurgical treatment of chronic cavitary pulmonary aspergillosis (CCPA) remains unsatisfactory, especially in lung cancer. We report two advanced non-small cell lung cancer (NSCLC) patients who recovered from CCPA following instillation of Amphotericin B (AmB) by bronchoscopy combined with systemic voriconazole. The first patient was diagnosed with lung adenocarcinoma after right upper lobe resection and was treated with anaplastic lymphoma kinase-targeted therapy. Chest computed tomography (CT) revealed a right pulmonary cavity containing solid materials. The second patient was diagnosed with squamous cell carcinoma and received immunotherapy following surgery, chemotherapy, and radiotherapy. Chest CT tomography revealed a mass in the right lung cavity. Both patients' cultures and next-generation sequencing of their bronchoalveolar lavage (BAL) samples revealed presence of Aspergillus fumigatus. In addition, the galactomannan test of both patients BAL samples was positive. Systemic voriconazole was prescribed based on in vitro susceptibility testing. The chest images and clinical symptoms of both patients did not improve after one month of voriconazole therapy within the therapeutic blood concentration. Considering the low local concentrations of antifungals against CCPA, AmB instillation by bronchoscopy combined with systemic voriconazole was utilized. The chest CT images and clinical symptoms of both patients markedly improved in the following third month. Instillation of AmB combined with systemic voriconazole may be a promising treatment option for NSCLC patients with CCPA who fail voriconazole monotherapy.

Advances in immune response to pulmonary infection: Nonspecificity, specificity and memory

The lung immune response consists of various cells involved in both innate and adaptive immune processes. Innate immunity participates in immune resistance in a nonspecific manner, whereas adaptive immunity effectively eliminates pathogens through specific recognition. It was previously believed that adaptive immune memory plays a leading role during secondary infections; however, innate immunity is also involved in immune memory. Trained immunity refers to the long-term functional reprogramming of innate immune cells caused by the first infection, which alters the immune response during the second challenge. Tissue resilience limits the tissue damage caused by infection by controlling excessive inflammation and promoting tissue repair. In this review, we summarize the impact of host immunity on the pathophysiological processes of pulmonary infections and discuss the latest progress in this regard. In addition to the factors influencing pathogenic microorganisms, we emphasize the importance of the host response.

Serum Cytokine Biomarkers for Use in Diagnosing Pulmonary Tuberculosis versus Chronic Pulmonary Aspergillosis

Background

Aspergillus fumigatus-induced chronic pulmonary aspergillosis (CPA), the most common pulmonary tuberculosis (TB) sequela, tends to occur after pulmonary infection with the intracellular pathogen Mycobacterium tuberculosis (Mtb). Timely and accurate detection of A. fumigatus infection of pulmonary TB patients would undoubtedly greatly improve patient prognosis. Currently, the galactomannan (GM) antigen test is commonly used to detect A. fumigatus infection but has poor sensitivity that renders this assay inadequate for use in clinical practice.

Design or Methods

Given the fact CPA and TB induce different host immune responses, we evaluated serum cytokine level profiles of CPA, TB patients and patients with both diseases (CPA-TB) for multiple cytokines and cytokine combinations.

Results

The results revealed significantly higher serum levels of numerous proinflammatory cytokines, including IL-1β, IL-6, IL-8, IL-12p70, IFN-α, IFN-γ and TNF-α, in peripheral blood of CPA-TB patients versus that of TB patients. IL-8 levels alone provided the best discriminatory performance for distinguishing between TB and either CPA-TB patients (AUC = 0.949) or CPA patients (AUC = 0.964). Moreover, both IL-8 and TNF-α (AUC = 0.996) levels could be used to distinguish between TB and CPA-TB patients. Likewise, IL-8, TNF-α and IL-6 levels together could be used to distinguish between CPA-TB and TB patients.

Conclusion

In this study, multiple cytokines were identified that may serve as potential biomarkers for use in detecting TB patients with CPA. Furthermore, our results should enhance understanding of how immune system dysfunctions influence susceptibility to Mtb and/or A. fumigatus infections.

Immunopathologic Role of Eosinophils in Eosinophilic Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a diverse chronic inflammatory disease of the sinonasal mucosa. CRS manifests itself in a variety of clinical and immunologic patterns. The histological hallmark of eosinophilic CRS (ECRS) is eosinophil infiltration. ECRS is associated with severe disease severity, increased comorbidity, and a higher recurrence rate, as well as thick mucus production. Eosinophils play an important role in these ECRS clinical characteristics. Eosinophils are multipotential effector cells that contribute to host defense against nonphagocytable pathogens, as well as allergic and nonallergic inflammatory diseases. Eosinophils interact with Staphylococcus aureus, Staphylococcal enterotoxin B, and fungi, all of which were found in the tissue of CRS patients. These interactions activate Th2 immune responses in the sinonasal mucosa and exacerbate local inflammation. Activated eosinophils were discovered not only in the tissue but also in the sinonasal cavity secretion. Eosinophil extracellular traps (EETs) are extracellular microbes trapping and killing structures found in the secretions of CRS patients with intact granule protein and filamentous chromatic structures. At the same time, EET has a negative effect by causing an epithelial barrier defect. Eosinophils also influence the local tissue microenvironment by exchanging signals with other immune cells and structural cells. As a result, eosinophils are multifaceted leukocytes that contribute to various physiologic and pathologic processes of the upper respiratory mucosal immune system. The goal of this review is to summarize recent research on the immunopathologic properties and immunologic role of eosinophils in CRS.

Vaccination with Live or Heat-Killed Aspergillus fumigatus ΔsglA Conidia Fully Protects Immunocompromised Mice from Invasive Aspergillosis

Aspergillus fumigatus causes invasive aspergillosis (IA) in immunocompromised patients, resulting in high mortality rates. Currently, no vaccine formulations to promote immune protection in at-risk individuals have been developed. In this work, we deleted the sterylglucosidase-encoding gene, sglA, in Aspergillus fumigatus and investigated its role in fungal virulence and host vaccine protection. The ΔsglA mutant accumulated sterylglucosides (SGs), newly studied immunomodulatory glycolipids, and exhibited reduced hyphal growth and altered compositions of cell wall polysaccharides. Interestingly, the ΔsglA mutant was avirulent in two murine models of IA and was fully eliminated from the lungs. Both corticosteroid-induced immunosuppressed and cyclophosphamide-induced leukopenic mice vaccinated with live or heat-killed ΔsglA conidia were fully protected against a lethal wild-type A. fumigatus challenge. These results highlight the potential of SG-accumulating strains as safe and promising vaccine formulations against invasive fungal infections. IMPORTANCE Infections by Aspergillus fumigatus occur by the inhalation of environmental fungal spores called conidia. We found that live mutant conidia accumulating glycolipids named sterylglucosides are not able to cause disease when injected into the lung. Interestingly, these animals are now protected against a secondary challenge with live wild-type conidia. Remarkably, protection against a secondary challenge persists even with vaccination with heat-killed mutant conidia. These results will significantly advance the field of the research and development of a safe fungal vaccine for protection against the environmental fungus A. fumigatus.

Metagenomic next-generation sequencing for the detection of pathogenic microorganisms in patients with pulmonary infection

OBJECTIVE

To explore the clinical value of metagenomic next-generation sequencing (mNGS) in diagnosing pulmonary infectious diseases.

METHODS

A retrospective analysis was performed on 82 patients with pulmonary infection who were admitted to the Eighth Affiliated Hospital of Guangxi Medical University & Guigang City People's Hospital from January 2020 to December 2021. The pathogens were detected by mNGS and conventional methods (culture and PCR). Then, the type and number of detected pathogens, as well as the specificity and sensitivity, were compared between the two methods. In addition, the positive rates of bacteria, fungi, tubercle bacillus, and mixed infection in bronchoalveolar lavage fluid, sputum, pleural effusion, and blood detected by mNGS, and the advantage in required test time were evaluated.

RESULTS

More types and numbers of pathogens were detected by mNGS with a higher sensitivity but a lower specificity, as compared to the conventional detection methods (all P<0.05). The positive rates and integrity rates of bacteria, fungi, and tubercle bacillus detected by mNGS were higher than those by conventional methods (all P<0.05). Moreover, there was no difference in the overall sensitivity of mNGS among different sample types, but the sensitivities of mNGS in bronchoalveolar lavage fluid and sputum samples were significantly higher than those of conventional methods (both P<0.05). The average test time for mNGS was shorter than that of conventional methods.

CONCLUSION

mNGS can detect more types and numbers of pathogenic microorganisms, improve the detection sensitivity, and reduce the detection time in patients with pulmonary infection.

Lung and gut microbiomes in pulmonary aspergillosis: Exploring adjunctive therapies to combat the disease

Species within the Aspergillus spp. cause a wide range of infections in humans, including invasive pulmonary aspergillosis, chronic pulmonary aspergillosis, and allergic bronchopulmonary aspergillosis, and are associated with high mortality rates. The incidence of pulmonary aspergillosis (PA) is on the rise, and the emergence of triazole-resistant Aspergillus spp. isolates, especially Aspergillus fumigatus, limits the efficacy of mold-active triazoles. Therefore, host-directed and novel adjunctive therapies are required to more effectively combat PA. In this review, we focus on PA from a microbiome perspective. We provide a general overview of the effects of the lung and gut microbiomes on the growth of Aspergillus spp. and host immunity. We highlight the potential of the microbiome as a therapeutic target for PA.

Invasive pulmonary fungal infections in children with severe human adenovirus type 7 pneumonia: A retrospective study

BACKGROUND

There has been a rapid increase in the number of human adenovirus type 7 (HAdV-7) and invasive pulmonary fungal infections (IPFIs) co-infection.

METHODS

In this study, we included patients with confirmed HAdV-7 infection during the period from 2018 to 2019 to explore clinical characteristics of severe HAdV-7 pneumonia combined with IPFIs.

RESULTS

Among the 143 patients, 35 cases were co-infected with IPFIs. Others were assigned to the control group (n Z 108). Patients wereprone to be complicated with respiratory failure, heart failure and hemophagocytic syndromein IPFIs group. Thirty-one species of fungi were detected in the IPFIs group, among whichAspergillus was the most common species. Compared to control group, patients had lowerlevels of WBC, CD3þ T lymphocyte counts and CD19þ B lymphocyte counts in IPFIs group.

CONCLUSION

Aspergillus is the most common species in IPFIs combined with severe HAdV-7 pneumonia. For children with severe HAdV-7 pneumonia who are younger, have a long course of disease, and have been admitted to the ICU, we should predict the occurrence of IPFIs when there is multi-system dysfunction and the reduction of CD3+ T lymphocyte counts and CD19+ B lymphocyte counts in course of their disease.

In Vitro Production of Virulence Factors and Antifungal Susceptibility Pattern of Aspergillus Isolates from Clinical Samples in a Tertiary Care Center

Objectives This study was aimed to investigate the association between virulence factors and antifungal susceptibility pattern among Aspergillus species.

Materials and Methods This study was carried out in the Department of Microbiology, from May 2018 to June 2019. A total of 52 Aspergillus isolates obtained from various clinical samples were speciated based on microscopic identification by lacto phenol cotton blue (LPCB) mount and slide culture technique. The production of virulence factors such as biofilm, lipase, phospholipase, amylase, and hemolysin were detected using standard phenotypic methods with Aspergillus niger ATCC (American Type Culture Collection) 6275 as the control strain. Antifungal susceptibility patterns of all Aspergillus isolates to amphotericin B, itraconazole, voriconazole, and posaconazole were evaluated in line with the Clinical Laboratory Standards Institute (CLSI) M38-A2 guidelines.

Results The percentage of resistance was the highest in itraconazole (48.08%), followed by amphotericin B (28.85%) and voriconazole (9.62%). All amphotericin B-resistant isolates produced biofilm, itraconazole-resistant isolates exhibited phospholipase activity, and voriconazole-resistant isolates produced biofilm and demonstrated phospholipase and hemolytic activities. Regardless of the virulence factors produced, all isolates were susceptible to posaconazole.

Conclusion Understanding the relationship between virulence factors and antifungal resistance aids in the development of new therapeutic approaches involving virulence mechanisms as potential targets for effective antifungal drug development.

Heterogeneous imaging features of Aspergillosis at 18F-FDG PET/CT

Aspergillosis is one of the most frequent fungal infections, whose morbidity can be life-threatening, especially in some categories of patients such as immunocompromised ones. It can have various clinical presentation scenarios and should be considered when making differential diagnosis in patients with pulmonary and extrapulmonary involvement. 18F-FDG PET/CT is a whole-body diagnostic technique that can help in the study of the disease, guiding the patient management thanks to the possibility to recognize infection sites and extension. The aim of this manuscript is to provide an overview of the wide spectrum of disease presentation. Literature regarding 18F-FDG PET/CT in histologically confirmed aspergillosis cases has been revised to describe all its possible features, both usual and unusual to guide imaging interpretation. 18F-FDG PET/CT is a diagnostic tool that can help in the recognition of the heterogenous infection’s presentation, allowing the clinicians to make a prompt diagnosis and to have the most accurate management of the disease. Furthermore, other PET/CT radiopharmaceutical role in Aspergillosis imaging study have been presented.

Recent Advances in Fungal Infections: From Lung Ecology to Therapeutic Strategies With a Focus on Aspergillus spp

Fungal infections are estimated to be the main cause of death for more than 1.5 million people worldwide annually. However, fungal pathogenicity has been largely neglected. This is notably the case for pulmonary fungal infections, which are difficult to diagnose and to treat. We are currently facing a global emergence of antifungal resistance, which decreases the chances of survival for affected patients. New therapeutic approaches are therefore needed to face these life-threatening fungal infections. In this review, we will provide a general overview on respiratory fungal infections, with a focus on fungi of the genus Aspergillus. Next, the immunological and microbiological mechanisms of fungal pathogenesis will be discussed. The role of the respiratory mycobiota and its interactions with the bacterial microbiota on lung fungal infections will be presented from an ecological perspective. Finally, we will focus on existing and future innovative approaches for the treatment of respiratory fungal infections.

Cytoskeletal Alteration Is an Early Cellular Response in Pulmonary Epithelium Infected with Aspergillus fumigatus Rather than Scedosporium apiospermum

Invasive aspergillosis and scedosporiosis are life-threatening fungal infections with similar clinical manifestations in immunocompromised patients. Contrarily, Scedosporium apiospermum is susceptible to some azole derivative but often resistant to amphotericin B. Histopathological examination alone cannot diagnose these two fungal species. Pathogenesis studies could contribute to explore candidate protein markers for new diagnosis and treatment methods leading to a decrease in mortality. In the present study, proteomics was conducted to identify significantly altered proteins in A549 cells infected with or without Aspergillus fumigatus and S. apiospermum as measured at initial invasion. Protein validation was performed with immunogold labelling alongside immunohistochemical techniques in infected A549 cells and lungs from murine models. Further, cytokine production was measured, using the Bio-Plex-Multiplex immunoassay. The cytoskeletal proteins HSPA9, PA2G4, VAT1, PSMA2, PEX1, PTGES3, KRT1, KRT9, CLIP1 and CLEC20A were mainly changed during A. fumigatus infection, while the immunologically activated proteins WNT7A, GAPDH and ANXA2 were principally altered during S. apiospermum infection. These proteins are involved in fungal internalisation and structural destruction leading to pulmonary disorders. Interleukin (IL)-21, IL-1α, IL-22, IL-2, IL-8, IL-12, IL-17A, interferon-γ and tumour necrosis factor-α were upregulated in both aspergillosis and scedosporiosis, although more predominately in the latter, in accordance with chitin synthase-1 and matrix metalloproteinase levels. Our results demonstrated that during invasion, A. fumigatus primarily altered host cellular integrity, whereas S. apiospermum chiefly induced and extensively modulated host immune responses.

Dynamic optimization reveals alveolar epithelial cells as key mediators of host defense in invasive aspergillosis

Aspergillus fumigatus is an important human fungal pathogen and its conidia are constantly inhaled by humans. In immunocompromised individuals, conidia can grow out as hyphae that damage lung epithelium. The resulting invasive aspergillosis is associated with devastating mortality rates. Since infection is a race between the innate immune system and the outgrowth of A. fumigatus conidia, we use dynamic optimization to obtain insight into the recruitment and depletion of alveolar macrophages and neutrophils. Using this model, we obtain key insights into major determinants of infection outcome on host and pathogen side. On the pathogen side, we predict in silico and confirm in vitro that germination speed is an important virulence trait of fungal pathogens due to the vulnerability of conidia against host defense. On the host side, we found that epithelial cells, which have been underappreciated, play a role in fungal clearance and are potent mediators of cytokine release. Both predictions were confirmed by in vitro experiments on established cell lines as well as primary lung cells. Further, our model affirms the importance of neutrophils in invasive aspergillosis and underlines that the role of macrophages remains elusive. We expect that our model will contribute to improvement of treatment protocols by focusing on the critical components of immune response to fungi but also fungal virulence traits.

Chronic Pulmonary Aspergillosis: Disease Severity Using Image Analysis and Correlation with Systemic Proinflammation and Predictors of Clinical Outcome

(1) Background: The presentation of chronic pulmonary aspergillosis (CPA) ranges from single granuloma to fibrosis in the affected lung. CPA can be divided into five categories according to European Respirology Society (ERS) guidance but is usually assessed by clinical physicians. Computer-based quantitative lung parenchyma analysis in CPA and its correlation with clinical manifestations, systemic inflammation, and angiogenesis have never been investigated. (2) Method: Forty-nine patients with CPA and 36 controls were prospectively enrolled. Pulmonary function tests (forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and FEV₁/FCV) and biomarkers in the peripheral blood (the chemokines interleukin (IL)-1B, IL-6, IL-10, IL-8, CRP, ESR, MMP1, MMP7, MMP8, TNF-α, calprotectin, SDF-1α, and VEGFA) were measured before antifungal treatment. The disease severity was categorized into mild, moderate, and severe based on chest computed tomography (CT) images. The oxygen demand and overall mortality until the end of the study were recorded. Quantitative parenchyma analysis was performed using the free software 3Dslicer. (3) Results: The results of quantitative parenchyma analysis concorded with the visual severity from the chest CT, oxygen demand, FVC, and FEV₁ in the study subjects. The decrease in kurtosis and skewness of the lung density histograms on CT, increase in high attenuation area (HAA), and reduced lung volume were significantly correlated with increases in the PMN %, CRP, IL-1B, SDF-1α, MMP1, and Calprotectin in peripheral blood in the multivariable regression analysis. TNF-α and IL-1B at study entry and the CPA severity from either a visual method or computer-based evaluation were predictors of long-term mortality. (4) Conclusion: The computer-based parenchyma analysis in CPA agreed with the categorization on a visual basis and was associated with the clinical outcomes, chemokines, and systemic proinflammation profiles.

Mortality in critically ill patients with coronavirus disease 2019-associated pulmonary aspergillosis: A systematic review and meta-analysis

Reports of COVID-19 associated pulmonary aspergillosis (CAPA) are rising, but the associated mortality and factors affecting it are not well-characterised. We performed a systematic review including 20 peer-reviewed English language studies reporting mortality in CAPA published till 18 February 2021from PubMed, Ovid SP, Web of Science, Embase and CINHAL. The pooled mortality in CAPA was 51.2% (95% CI: 43.1-61.1, I2  = 38%). The leave one out sensitivity analysis and influential case diagnostics revealed one outlier and its exclusion resulted in a mortality estimate of 54% (95% CI: 45-62). Higher odds of mortality: 2.83 (95% CI: 1.8-4.5) were seen in CAPA compared to controls. No significant difference in various subgroups according to the country of study, the continent of study, income category of country and quality of the included study was seen. None of the host risk factors, mycological test results, therapy for COVID-19 and antifungal therapy affected mortality. Thus, patients with CAPA have a high probability of mortality and early diagnosis with prompt therapy must be ensured to optimally manage these patients. However, more prospective studies with global and multi-centre coordination may help to address CAPA in a better way.

Aspergillus fumigatus Influences Gasdermin-D-Dependent Pyroptosis of the Lung via Regulating Toll-Like Receptor 2-Mediated Regulatory T Cell Differentiation

Purpose

Aspergillus fumigatus, as an opportunistic fungus, has developed a series of escape mechanisms under the host's immune response to obtain nutrients and promote fungal growth in the hostile environment. The immune escape of pathogens may be through suppressing the inflammatory response mediated by regulatory T cells (Tregs). The aim of this study was to explore whether A. fumigatus influences Gasdermin-D-dependent pyroptosis of the lung by regulating Toll-like receptor 2-mediated regulatory T cell differentiation.

Methods

Collect peripheral blood from patients with A. fumigatus. ELISA kits we used to detect the expression levels of IL-1β, IL-6, IL-2R, and IL-10 in the serum and flow cytometry to detect the percentage of CD4⁺CD25⁺Foxp3⁺ Tregs in the patients' peripheral blood mononuclear cells (PBMCs). The mouse model of A. fumigatus infection was constructed by tracheal instillation. The pathological changes in the lungs of the mice were observed under a microscope. The fungal load in the lung tissue was determined by the plate colony count. ELISA kit was used to detect the lung tissue homogenate proinflammatory cytokines TNF-α, IL-6, CCL2, and VEGF. Q-PCR was used for the detection of the expression of Foxp3 and TLR2 genes in the lung. Western blot was used for the detection of the expression of TLR2, Gasdermin-D (GSDMD), IL-1α, and IL-1β in the lung. Flow cytometry was used to detect splenic CD4⁺CD25⁺FOXP3⁺ Tregs. Using magnetic beads to extract CD4⁺ T cells from mice spleen, the effects of A. fumigatus conidia or TLR2 inhibitor (C29) to differentiate CD4⁺ T cells in vitro were tested.

Results

The expression of Foxp3 and TLR2 in the lung tissue of mice infected with A. fumigatus increased, and we observed that the proportion of Tregs in both A. fumigatus infection patients and mice was upregulated. After using the CD25 neutralizing antibody, the number of Tregs in the mice spleen was significantly reduced. However, lung damage was reduced and the ability to clear lung fungi was enhanced. We found that the Tregs in TLR2^−/− mice were significantly reduced and the nonlethal dose of A. fumigatus conidia did not cause severe lung damage in TLR2^−/− mice. Compared with that of wild-type mice, the fungal burden in the lung of TLR2-deficient mice was reduced and the knockout of TLR2 changed the expression of GSDMD, IL-1α, and IL-1β in A. fumigatus. In in vitro experiments, we found that the inhibition of TLR2 can reduce Treg differentiation.

Conclusions

A. fumigatus triggers CD4⁺CD25⁺FOXP3⁺ Treg proliferation and differentiation by activating the TLR2 pathway, which may be a potential mechanism for evading host defenses in A. fumigatus. This effect can modulate GSDMD-dependent pyroptosis and may partly involve TRL2 signaling.

In vitro antifungal susceptibility of yeasts and molds isolated from sputum of tuberculosis relapse and retreatment patients

INTRODUCTION

opportunistic fungal infections due to immunosuppression coupled with antifungal drug resistance are an emerging challenge globally. The present study examined the antifungal susceptibility of yeasts and molds from sputum of tuberculosis retreatment and relapse patients at selected reference facilities in Kenya.

METHODS

a total of 340 sputa samples from patients who gave written informed consent were examined. Fungal culture was done on sabouraud dextrose agar (SDA). Molds were identified by macroscopic and microscopic features while yeasts were inoculated on CHROMTMagar Candida and confirmed using API 20C AUXTM. Itraconazole (ICZ), voriconazole (VCZ), fluconazole (FCZ) and amphotericin B (AMB) were tested using broth micro-dilution methods according to Clinical and Laboratory Standards Institute (CLSI).

RESULTS

out of the 340 samples, 14.4% (n=49) and 15.6% (n=53) were positive for yeasts and molds respectively. Candida albicans and C. krusei were the most predominant isolates constituting 49.0% (n=24) and 20.4% (n=10) of the total yeasts respectively. Aspergillus spp. were the most frequent (22.6%) molds and isolates with MICs ≥4μg/ml on the antifungal agents were noted. All the molds except two (n=2) isolates of Scedosporium aspiopermum exhibited MICs >4μg/ml for fluconazole. Overall, molds were more sensitive to AMB and VCZ. Candida albicans had MIC50 <0.06μg/ml, and MIC90<4μg/ml. There was a statistically significant difference (F=3.7, P=0.004<0.05) in the overall sensitivity pattern of molds for the four antifungal agents while there was no significant difference (F=1.7, P=0.154>0.05) in sensitivity exhibited by the yeasts.

CONCLUSION

the study demonstrates the significance of fungal colonization in presumptive tuberculosis retreatment or relapse with evidence of triazole resistance. There is need to strengthen fungal diagnostic and clinical management capabilities in susceptible populations.

TREM1 regulates antifungal immune responses in invasive pulmonary aspergillosis

Pattern recognition receptors (PRRs) are responsible for Aspergillus fumigatus recognition by innate immunity and its subsequent immune signaling. The triggering receptor expressed on myeloid cells 1 (TREM1) is a recently characterized pro-inflammatory receptor constitutively expressed on the surface of neutrophils and macrophages. A soluble form (sTREM1) of this protein that can be detected in human body fluids has been identified. Here we investigated the role of TREM1 during invasive pulmonary aspergillosis (IPA). IPA patients displayed significantly higher levels of sTREM1 in bronchoalveolar lavages when compared to control patients. Functional analysis in TREM1 showed that the levels of sTREM1 and TREM1 pathway-related cytokines were influenced by single nucleotide polymorphisms in TREM1. In addition, we confirmed a role of TREM1 on antifungal host defense against A. fumigatus in a murine model of IPA. TREM1 deficiency increased susceptibility to infection in the immunosuppressed murine host. Deletion of TREM1 showed delayed innate and adaptive immune responses and impaired pro-inflammatory cytokine responses. The absence of TREM1 in primary macrophages attenuated the TLR signaling by altering the expression of both receptor and effector proteins that are critical to the response against A. fumigatus. In this study, and for the first time, we demonstrate the key role for the TREM1 receptor pathway during IPA.

Aspergillus fumigatus Recognition by Dendritic Cells Negatively Regulates Allergic Lung Inflammation through a TLR2/MyD88 Pathway

Aspergillus fumigatus is an opportunistic fungal pathogen responsible for a spectrum of clinical manifestations. Dendritic cells recognize pathogen-associated molecular patterns of Aspergillus via two main receptor families, Toll-like receptors (TLRs) and C-type lectin receptors (CLR). Here, the importance of TLR and CLR signaling in the regulation of T-helper cell type 2 (Th2) responses was analyzed using a mouse model based on the transfer of bone marrow-derived dendritic cells (BMDCs) pulsed with A. fumigatus conidia. BMDCs were generated from mice deficient in either MyD88 or MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1). Both the MyD88 and MALT1 signaling pathway in BMDCs contributed to the production of inflammatory cytokines induced by A. fumigatus conidia. Mice sensitized with MyD88^-/- BMDCs pulsed in vitro with A. fumigatus conidia showed an exacerbated allergic inflammation, with stronger eosinophil recruitment in the BAL and higher Th2 cytokine production compared with mice sensitized with wild-type or MALT1^-/- BMDCs. This exacerbation was not observed when MyD88^-/- BMDCs were pulsed with Cladosporium sphaerospermum, a nonpathogenic mold. A lack of TLR2 signaling recapitulated the exacerbation of the A. fumigatus Th2 response observed in the absence of MyD88 signaling, whereas TLR2 agonist dampened the response induced with A. fumigatus and C. sphaerospermum conidia. IL-10 production by BMDCs in response to A. fumigatus was dependent on the expression of TLR2 and MyD88. IL-10^-/- BMDCs exacerbated, whereas MyD88^-/- BMDCs supplemented with exogenous IL-10 decreased the allergic pulmonary inflammation. These results indicate that TLR2/MyD88-specific recognition of PAMPs from A. fumigatus conidia can upregulate IL-10 production and downregulate lung eosinophilia and the development of a Th2 response.

Novel Biological Functions of the NsdC Transcription Factor in Aspergillus fumigatus

The fungal zinc finger transcription factor NsdC is named after, and is best known for, its essential role in sexual reproduction (never in sexual development). In previous studies with Aspergillus nidulans, it was also shown to have roles in promotion of vegetative growth and suppression of asexual conidiation. In this study, the function of the nsdC homologue in the opportunistic human pathogen A. fumigatus was investigated. NsdC was again found to be essential for sexual development, with deletion of the nsdC gene in both MAT1-1 and MAT1-2 mating partners of a cross leading to complete loss of fertility. However, a functional copy of nsdC in one mating partner was sufficient to allow sexual reproduction. Deletion of nsdC also led to decreased vegetative growth and allowed conidiation in liquid cultures, again consistent with previous findings. However, NsdC in A. fumigatus was shown to have additional biological functions including response to calcium stress, correct organization of cell wall structure, and response to the cell wall stressors. Furthermore, virulence and host immune recognition were affected. Gene expression studies involving chromatin immunoprecipitation (ChIP) of RNA polymerase II (PolII) coupled to next-generation sequencing (Seq) revealed that deletion of nsdC resulted in changes in expression of over 620 genes under basal growth conditions. This demonstrated that this transcription factor mediates the activity of a wide variety of signaling and metabolic pathways and indicates that despite the naming of the gene, the promotion of sexual reproduction is just one among multiple roles of NsdC.IMPORTANCE Aspergillus fumigatus is an opportunistic human fungal pathogen and the main causal agent of invasive aspergillosis, a life-threatening infection especially in immunocompromised patients. A. fumigatus can undergo both asexual and sexual reproductive cycles, and the regulation of both cycles involves several genes and pathways. Here, we have characterized one of these genetic determinants, the NsdC transcription factor, which was initially identified in a screen of transcription factor null mutants showing sensitivity when exposed to high concentrations of calcium. In addition to its known essential roles in sexual reproduction and control of growth rate and asexual reproduction, we have shown in the present study that A. fumigatus NsdC transcription factor has additional previously unrecognized biological functions including calcium tolerance, cell wall stress response, and correct cell wall organization and functions in virulence and host immune recognition. Our results indicate that NsdC can play novel additional biological functions not directly related to its role played during sexual and asexual processes.

Th17 cells are involved in mouse chronic obstructive pulmonary disease complicated with invasive pulmonary aspergillosis

BACKGROUND

The incidence of chronic obstructive pulmonary disease (COPD) complicated with invasive pulmonary aspergillosis (IPA) has increased in the last two decades. The mechanism underpinning susceptibility to and high mortality of COPD complicated with IPA is unclear, and the role of T helper cells 17 (Th17 cells) in the compound disease remains unknown. Therefore, this study aimed to assess the function of Th17 cells in COPD combined with IPA.

METHODS

COPD, IPA, and COPD+IPA mouse models were established in male wild type C57/BL6 mice. The amounts of Th17 cells and retinoic acid-related orphan receptors γt (RORγt) were tested by flow cytometry. Then, serum interleukin (IL)-17 and IL-23 levels were detected by enzyme-linked immunosorbent assay (ELISA) in the control, COPD, IPA and COPD+IPA groups. In addition, COPD+IPA was induced in IL-17 knockout (KO) mice, for determining the role of Th17 cells in COPD+IPA.

RESULTS

Compared with the COPD group, the COPD+IPA group showed higher amounts of blood RORγt ([35.09 ± 16.12]% vs. [17.92 ± 4.91]%, P = 0.02) and serum IL-17 (17.96 ± 9.59 pg/mL vs. 8.05 ± 4.44 pg/mL, P = 0.02), but blood ([5.18 ± 1.09]% vs. [4.15 ± 0.87]%, P = 0.28) and lung levels of Th17 cells ([1.98 ± 0.83]% vs. [2.03 ± 0.98]%, P = 0.91), lung levels of RORγt ([9.58 ± 6.93]% vs. [9.63 ± 5.98]%, P = 0.49) and serum IL-23 (51.55 ± 27.82 pg/mL vs. 68.70 ± 15.20 pg/mL, P = 0.15) showed no significant differences. Compared with the IPA group, the COPD+IPA group displayed lower amounts of blood ([5.18 ± 1.09]% vs. [9.21 ± 3.56]%, P = 0.01) and lung Th17 cells ([1.98 ± 0.83]% vs. [6.29 ± 1.11]%, P = 0.01) and serum IL-23 (51.55 ± 27.82 pg/mL vs. 154.90 ± 64.60 pg/mL, P = 0.01) and IL-17 (17.96 ± 9.59 pg/mL vs. 39.81 ± 22.37 pg/mL, P = 0.02), while comparable blood ([35.09 ± 16.12]% vs. [29.86 ± 15.42]%, P = 0.25) and lung levels of RORγt ([9.58 ± 6.93]% vs. [15.10 ± 2.95]%, P = 0.18) were found in these two groups. Finally, Aspergillus load in IL-17 KO COPD+IPA mice was almost 2 times that of COPD+IPA mice (1,851,687.69 ± 944,480.43 vs. 892,958.10 ± 686,808.80, t = 2.32, P = 0.02).

CONCLUSION

These findings indicate that Th17 cells might be involved in the pathogenesis of COPD combined with IPA, with IL-17 likely playing an antifungal role.

Immunological response to COVID-19 and its role as a predisposing factor in invasive aspergillosis

The world is involved with a pandemic coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2. The clinical manifestations of reported COVID-19-associated pulmonary impairments range from asymptomatic infections to a pneumonia-induced acute respiratory distress syndrome that requires mechanical ventilation. Fungal superinfections complicating the clinical course remain underexplored. Angiotensin-converting enzyme 2, the receptor for COVID-19 that is mainly expressed in airway epithelia and lung parenchyma, is considered an important regulator of innate immunity. With regard to the viral-cell interaction, imbalanced immune regulation between protective and altered responses caused by the exacerbation of inflammatory responses should be considered a major contributor to secondary pulmonary aspergillosis. In addition, the complex inherited factors, age-related changes, and lifestyle may also affect immune responses. The complication and persistence of invasive aspergillosis have been well described in patients with severe influenza or COVID-19. However, there is a scarcity of information about the immunological mechanisms predisposing patients with COVID-19 to fungal co-infections. Therefore, this study was conducted to investigate the aforementioned domain.

Proinflammatory effects of environmental cadmium boost resistance to opportunistic pathogen Aspergillus fumigatus: Implications for sustained low-level pulmonary inflammation?

Cadmium (Cd) is one of the most toxic environmental heavy metals to which the general population is exposed mainly via the oral route. Owing to its immunomodulatory potential, orally acquired Cd affects antimicrobial immune defense in several organs, including the lungs. While there are data concerning Cd and viral and bacterial pulmonary infections, effects on fungal infections are not studied yet. In the present study, the effect of the Cd (5 mg/L for 30 days, in drinking water, the average daily Cd intake 0.641 ± 0.089 mg/kg) on the immune response of rats to pulmonary A. fumigatus infection was examined. Data obtained showed that orally acquired cadmium does not affect the elimination of the fungus in immunocompetent rats owing to the preservation of some aspects of innate immune responses (lung leukocyte infiltration and NBT reduction) and an increase in other (increased numbers of mucus-producing goblet cells, MPO release). Cd does not affect an IFN-γ response in lung leukocytes during the infection (despite suppression of cytokine production in cells of lung-draining lymph nodes), while it stimulates IL-17 and suppresses IL-10 response to the fungus. As a result, the elimination of the fungus occurs in a milieu with the prevailing proinflammatory response in Cd-exposed animals that preserved fungal elimination from the lungs, though with more intense injury to the lung tissue. Therefore, the proinflammatory microenvironment in the lungs created by Cd that sustains inflammatory/immune response to the fungus to which humans are exposed for a lifetime, raises a concern of orally acquired Cd as a risk factor for the development of chronic low-grade pulmonary inflammation.

Longitudinal In Vivo Assessment of Host-Microbe Interactions in a Murine Model of Pulmonary Aspergillosis

The fungus Aspergillus fumigatus is ubiquitous in nature and the most common cause of invasive pulmonary aspergillosis (IPA) in patients with a compromised immune system. The development of IPA in patients under immunosuppressive treatment or in patients with primary immunodeficiency demonstrates the importance of the host immune response in controlling aspergillosis. However, study of the host-microbe interaction has been hampered by the lack of tools for their non-invasive assessment. We developed a methodology to study the response of the host's immune system against IPA longitudinally in vivo by using fluorine-19 magnetic resonance imaging (¹⁹F MRI). We showed the advantage of a perfluorocarbon-based contrast agent for the in vivo labeling of macrophages and dendritic cells, permitting quantification of pulmonary inflammation in different murine IPA models. Our findings reveal the potential of ¹⁹F MRI for the assessment of rapid kinetics of innate immune response against IPA and the permissive niche generated through immunosuppression.

Preparations for Invasion: Modulation of Host Lung Immunity During Pulmonary Aspergillosis by Gliotoxin and Other Fungal Secondary Metabolites

Pulmonary aspergillosis is a severe infectious disease caused by some members of the Aspergillus genus, that affects immunocompetent as well as immunocompromised patients. Among the different disease forms, Invasive Aspergillosis is the one causing the highest mortality, mainly, although not exclusively, affecting neutropenic patients. This genus is very well known by humans, since different sectors like pharmaceutical or food industry have taken advantage of the biological activity of some molecules synthetized by the fungus, known as secondary metabolites, including statins, antibiotics, fermentative compounds or colorants among others. However, during infection, in response to a hostile host environment, the fungal secondary metabolism is activated, producing different virulence factors to increase its survival chances. Some of these factors also contribute to fungal dissemination and invasion of adjacent and distant organs. Among the different secondary metabolites produced by Aspergillus spp. Gliotoxin (GT) is the best known and better characterized virulence factor. It is able to generate reactive oxygen species (ROS) due to the disulfide bridge present in its structure. It also presents immunosuppressive activity related with its ability to kill mammalian cells and/or inactivate critical immune signaling pathways like NFkB. In this comprehensive review, we will briefly give an overview of the lung immune response against Aspergillus as a preface to analyse the effect of different secondary metabolites on the host immune response, with a special attention to GT. We will discuss the results reported in the literature on the context of the animal models employed to analyse the role of GT as virulence factor, which is expected to greatly depend on the immune status of the host: why should you hide when nobody is seeking for you? Finally, GT immunosuppressive activity will be related with different human diseases predisposing to invasive aspergillosis in order to have a global view on the potential of GT to be used as a target to treat IA.

RNA-Seq Profile Reveals Th-1 and Th-17-Type of Immune Responses in Mice Infected Systemically with Aspergillus fumigatus

With the increasing numbers of immunocompromised hosts, Aspergillus fumigatus emerges as a lethal opportunistic fungal pathogen. Understanding innate and acquired immunity responses of the host is important for a better therapeutic strategy to deal with aspergillosis patients. To determine the transcriptome in the kidneys in aspergillosis, we employed RNA-Seq to obtain single 76-base reads of whole-genome transcripts of murine kidneys on a temporal basis (days 0; uninfected, 1, 2, 3 and 8) during invasive aspergillosis. A total of 6284 transcripts were downregulated, and 5602 were upregulated compared to baseline expression. Gene ontology enrichment analysis identified genes involved in innate and adaptive immune response, as well as iron binding and homeostasis, among others. Our results showed activation of pathogen recognition receptors, e.g., β-defensins, C-type lectins (e.g., dectin-1), Toll-like receptors (TLR-2, TLR-3, TLR-8, TLR-9 and TLR-13), as well as Ptx-3 and C-reactive protein among the soluble receptors. Upregulated transcripts encoding various differentiating cytokines and effector proinflammatory cytokines, as well as those encoding for chemokines and chemokine receptors, revealed Th-1 and Th-17-type immune responses. These studies form a basic dataset for experimental prioritization, including other target organs, to determine the global response of the host against Aspergillus infection.

Saccharomyces cerevisiae-Derived Mannan Does Not Alter Immune Responses to Aspergillus Allergens

Severe asthma with fungal sensitization predominates in the population suffering from allergic asthma, to which there is no cure. While corticosteroids are the mainstay in current treatment, other means of controlling inflammation may be beneficial. Herein, we hypothesized that mannan from Saccharomyces cerevisiae would dampen the characteristics of fungal allergic asthma by altering the pulmonary immune responses. Using wild-type and transgenic mice expressing the human mannose receptor on smooth muscle cells, we explored the outcome of mannan administration during allergen exposure on the pathogenesis of fungal asthma through measurement of cardinal features of disease such as inflammation, goblet cell number, and airway hyperresponsiveness. Mannan treatment did not alter most hallmarks of allergic airways disease in wild-type mice. Transgenic mice treated with mannan during allergen exposure had an equivalent response to non-mannan-treated allergic mice except for a prominent granulocytic influx into airways and cytokine availability. Our studies suggest no role for mannan as an inflammatory regulator during fungal allergy.

Human and Murine Innate Immune Cell Populations Display Common and Distinct Response Patterns during Their In Vitro Interaction with the Pathogenic Mold Aspergillus fumigatus

Aspergillus fumigatus is the main cause of invasive fungal infections occurring almost exclusively in immunocompromised patients. An improved understanding of the initial innate immune response is key to the development of better diagnostic tools and new treatment options. Mice are commonly used to study immune defense mechanisms during the infection of the mammalian host with A. fumigatus. However, little is known about functional differences between the human and murine immune response against this fungal pathogen. Thus, we performed a comparative functional analysis of human and murine dendritic cells (DCs), macrophages, and polymorphonuclear cells (PMNs) using standardized and reproducible working conditions, laboratory protocols, and readout assays. A. fumigatus did not provoke identical responses in murine and human immune cells but rather initiated relatively specific responses. While human DCs showed a significantly stronger upregulation of their maturation markers and major histocompatibility complex molecules and phagocytosed A. fumigatus more efficiently compared to their murine counterparts, murine PMNs and macrophages exhibited a significantly stronger release of reactive oxygen species after exposure to A. fumigatus. For all studied cell types, human and murine samples differed in their cytokine response to conidia or germ tubes of A. fumigatus. Furthermore, Dectin-1 showed inverse expression patterns on human and murine DCs after fungal stimulation. These specific differences should be carefully considered and highlight potential limitations in the transferability of murine host–pathogen interaction studies.

The second International Symposium on Fungal Stress: ISFUS

The topic of 'fungal stress' is central to many important disciplines, including medical mycology, chronobiology, plant and insect pathology, industrial microbiology, material sciences, and astrobiology. The International Symposium on Fungal Stress (ISFUS) brought together researchers, who study fungal stress in a variety of fields. The second ISFUS was held in May 8-11 2017 in Goiania, Goiás, Brazil and hosted by the Instituto de Patologia Tropical e Saúde Pública at the Universidade Federal de Goiás. It was supported by grants from CAPES and FAPEG. Twenty-seven speakers from 15 countries presented their research related to fungal stress biology. The Symposium was divided into seven topics: 1. Fungal biology in extreme environments; 2. Stress mechanisms and responses in fungi: molecular biology, biochemistry, biophysics, and cellular biology; 3. Fungal photobiology in the context of stress; 4. Role of stress in fungal pathogenesis; 5. Fungal stress and bioremediation; 6. Fungal stress in agriculture and forestry; and 7. Fungal stress in industrial applications. This article provides an overview of the science presented and discussed at ISFUS-2017.

Immunobiological Activity of Synthetically Prepared Immunodominant Galactomannosides Structurally Mimicking Aspergillus Galactomannan

The study is oriented at the in vitro evaluation of the immunobiological activity and efficacy of synthetically prepared isomeric pentasaccharides representing fragments of Aspergillus fumigatus cell-wall galactomannan and containing β-(1→5)-linked tetragalactofuranoside chain attached to O-6 (GM-1) or O-3 (GM-2) of a spacer-armed mannopyranoside residue. These compounds were studied as biotinylated conjugates which both demonstrated immunomodulatory activities on the RAW 264.7 cell line murine macrophages as in vitro innate immunity cell model. Immunobiological studies revealed time- and concentration-dependent efficient immunomodulation. The proliferation of RAW 264.7 macrophages was induced at higher concentration (100 µg/mL) of studied glycoconjugates and longer exposure (48 h), with more pronounced efficacy for GM-1. The increase of proliferation followed the previous increase of IL-2 production. The cytokine profile of the macrophages treated with the glycoconjugates was predominantly pro-inflammatory Th1 type with significant increase of TNFα, IL-6, and IL-12 release for both glycoconjugates. The RAW 264.7 macrophages production of free radicals was not significantly affected by glycoconjugates stimulation. The phagocytic activity of RAW 264.7 cells was reduced following GM-1 treatment and was significantly increased after 24 h stimulation with GM-2, contrary to 48 h stimulation. Moreover, the synthetically prepared galactomannoside derivatives have been evaluated as efficient serodiagnostic antigens recognized by specific Ig isotypes, and significant presence of specific IgM antibodies in serum of patients suffering from vulvovaginitis was observed.

Fast-track development of an in vitro 3D lung/immune cell model to study Aspergillus infections

To study interactions of airborne pathogens, e.g. Aspergillus (A.) fumigatus with upper and lower respiratory tract epithelial and immune cells, we set up a perfused 3D human bronchial and small airway epithelial cell system. Culturing of normal human bronchial or small airway epithelial (NHBE, SAE) cells under air liquid interphase (ALI) and perfusion resulted in a significantly accelerated development of the lung epithelia associated with higher ciliogenesis, cilia movement, mucus-production and improved barrier function compared to growth under static conditions. Following the accelerated differentiation under perfusion, epithelial cells were transferred into static conditions and antigen-presenting cells (APCs) added to study their functionality upon infection with A. fumigatus. Fungi were efficiently sensed by apically applied macrophages or basolaterally adhered dendritic cells (DCs), as illustrated by phagocytosis, maturation and migration characteristics. We illustrate here that perfusion greatly improves differentiation of primary epithelial cells in vitro, which enables fast-track addition of primary immune cells and significant shortening of experimental procedures. Additionally, co-cultured primary DCs and macrophages were fully functional and fulfilled their tasks of sensing and sampling fungal pathogens present at the apical surface of epithelial cells, thereby promoting novel possibilities to study airborne infections under conditions mimicking the in vivo situation.

Ecology of aspergillosis: insights into the pathogenic potency of Aspergillus fumigatus and some other Aspergillus species

Fungi of the genus Aspergillus are widespread in the environment. Some Aspergillus species, most commonly Aspergillus fumigatus, may lead to a variety of allergic reactions and life-threatening systemic infections in humans. Invasive aspergillosis occurs primarily in patients with severe immunodeficiency, and has dramatically increased in recent years. There are several factors at play that contribute to aspergillosis, including both fungus and host-related factors such as strain virulence and host pulmonary structure/immune status, respectively. The environmental tenacity of Aspergilllus, its dominance in diverse microbial communities/habitats, and its ability to navigate the ecophysiological and biophysical challenges of host infection are attributable, in large part, to a robust stress-tolerance biology and exceptional capacity to generate cell-available energy. Aspects of its stress metabolism, ecology, interactions with diverse animal hosts, clinical presentations and treatment regimens have been well-studied over the past years. Here, we synthesize these findings in relation to the way in which some Aspergillus species have become successful opportunistic pathogens of human- and other animal hosts. We focus on the biophysical capabilities of Aspergillus pathogens, key aspects of their ecophysiology and the flexibility to undergo a sexual cycle or form cryptic species. Additionally, recent advances in diagnosis of the disease are discussed as well as implications in relation to questions that have yet to be resolved.

Molecular Insights into Pathogenesis and Infection with Aspergillus Fumigatus

The virulence of fungi is dependent on multiple factors, including the immune status of patients and biological features of fungi. In particular, the virulence of Aspergillus fumigatus is due to the complex interaction among various molecules involved in thermotolerance (such as ribosomal biogenesis proteins, α-mannosyltransferase and heat shock proteins), pigment production (DHN-melanin), immune evasion (like melanin and hydrophobin) and nutrient uptake (such as siderophores and zinc transporters). Other molecules also play important roles in the virulence of A. fumigatus, including cell wall components and those which maintain its integrity (for instance β-1-3 glucan, α-1-3 glucan, chitin, galactomannan and mannoproteins) and adhesion (such as hydrophobins), as well as various hydrolytic enzymes (such as serine and aspartic protease, phospholipases, metalloproteinase and dipeptidyl peptidases). Signalling molecules (including G-protein, cAMP, Ras protein and calcineurin) also increase the virulence through altering the metabolic response to stress conditions and toxins (such as gliotoxin, fumitremorgins, fumagatin and helvolic acid).

High diversity of airborne fungi in the hospital environment as revealed by meta-sequencing-based microbiome analysis

Invasive fungal infections acquired in the hospital have progressively emerged as an important cause of life-threatening infection. In particular, airborne fungi in hospitals are considered critical pathogens of hospital-associated infections. To identify the causative airborne microorganisms, high-volume air samplers were utilized for collection, and species identification was performed using a culture-based method and DNA sequencing analysis with the Illumina MiSeq and HiSeq 2000 sequencing systems. Few bacteria were grown after cultivation in blood agar. However, using microbiome sequencing, the relative abundance of fungi, Archaea species, bacteria and viruses was determined. The distribution characteristics of fungi were investigated using heat map analysis of four departments, including the Respiratory Intensive Care Unit, Intensive Care Unit, Emergency Room and Outpatient Department. The prevalence of Aspergillus among fungi was the highest at the species level, approximately 17% to 61%, and the prevalence of Aspergillus fumigatus among Aspergillus species was from 34% to 50% in the four departments. Draft genomes of microorganisms isolated from the hospital environment were obtained by sequence analysis, indicating that investigation into the diversity of airborne fungi may provide reliable results for hospital infection control and surveillance.

Dynamic Immune Cell Recruitment After Murine Pulmonary Aspergillus fumigatus Infection under Different Immunosuppressive Regimens

Humans are continuously exposed to airborne spores of the saprophytic fungus Aspergillus fumigatus. However, in healthy individuals pulmonary host defense mechanisms efficiently eliminate the fungus. In contrast, A. fumigatus causes devastating infections in immunocompromised patients. Host immune responses against A. fumigatus lung infections in immunocompromised conditions have remained largely elusive. Given the dynamic changes in immune cell subsets within tissues upon immunosuppressive therapy, we dissected the spatiotemporal pulmonary immune response after A. fumigatus infection to reveal basic immunological events that fail to effectively control invasive fungal disease. In different immunocompromised murine models, myeloid, notably neutrophils, and macrophages, but not lymphoid cells were strongly recruited to the lungs upon infection. Other myeloid cells, particularly dendritic cells and monocytes, were only recruited to lungs of corticosteroid treated mice, which developed a strong pulmonary inflammation after infection. Lymphoid cells, particularly CD4⁺ or CD8⁺ T-cells and NK cells were highly reduced upon immunosuppression and not recruited after A. fumigatus infection. Moreover, adoptive CD11b⁺ myeloid cell transfer rescued cyclophosphamide immunosuppressed mice from lethal A. fumigatus infection but not cortisone and cyclophosphamide immunosuppressed mice. Our findings illustrate that CD11b⁺ myeloid cells are critical for anti-A. fumigatus defense under cyclophosphamide immunosuppressed conditions.

Allergic Inflammation in Aspergillus fumigatus-Induced Fungal Asthma

Although fungi are pervasive in many environments, few cause disease in humans. Of these, Aspergillus fumigatus is particularly well suited to be a pathogen of the human lung. Its physical and biological characteristics combine to provide an organism that can cause tremendous morbidity and high mortality if left unchecked. Luckily, that is rarely the case. However, repeated exposure to inhaled A. fumigatus spores often results in an immune response that carries significant immunopathology, exacerbating asthma and changing the structure of the lung with chronic impacts to pulmonary function. This review focuses on the current understanding of the mechanisms that are associated with fungal exposure, sensitization, and infection in asthmatics, as well as the function of various inflammatory cells associated with severe asthma with fungal sensitization.

Whole genome annotation and comparative genomic analyses of bio-control fungus Purpureocillium lilacinum

Background

The fungus Purpureocillium lilacinum is widely known as a biological control agent against plant parasitic nematodes. This research article consists of genomic annotation of the first draft of whole genome sequence of P. lilacinum. The study aims to decipher the putative genetic components of the fungus involved in nematode pathogenesis by performing comparative genomic analysis with nine closely related fungal species in Hypocreales.

Results

de novo genomic assembly was done and a total of 301 scaffolds were constructed for P. lilacinum genomic DNA. By employing structural genome prediction models, 13, 266 genes coding for proteins were predicted in the genome. Approximately 73 % of the predicted genes were functionally annotated using Blastp, InterProScan and Gene Ontology. A 14.7 % fraction of the predicted genes shared significant homology with genes in the Pathogen Host Interactions (PHI) database. The phylogenomic analysis carried out using maximum likelihood RAxML algorithm provided insight into the evolutionary relationship of P. lilacinum. In congruence with other closely related species in the Hypocreales namely, Metarhizium spp., Pochonia chlamydosporia, Cordyceps militaris, Trichoderma reesei and Fusarium spp., P. lilacinum has large gene sets coding for G-protein coupled receptors (GPCRs), proteases, glycoside hydrolases and carbohydrate esterases that are required for degradation of nematode-egg shell components. Screening of the genome by Antibiotics & Secondary Metabolite Analysis Shell (AntiSMASH) pipeline indicated that the genome potentially codes for a variety of secondary metabolites, possibly required for adaptation to heterogeneous lifestyles reported for P. lilacinum. Significant up-regulation of subtilisin-like serine protease genes in presence of nematode eggs in quantitative real-time analyses suggested potential role of serine proteases in nematode pathogenesis.

Conclusions

The data offer a better understanding of Purpureocillium lilacinum genome and will enhance our understanding on the molecular mechanism involved in nematophagy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2229-2) contains supplementary material, which is available to authorized users.

The Fungal Exopolysaccharide Galactosaminogalactan Mediates Virulence by Enhancing Resistance to Neutrophil Extracellular Traps

Of the over 250 Aspergillus species, Aspergillus fumigatus accounts for up to 80% of invasive human infections. A. fumigatus produces galactosaminogalactan (GAG), an exopolysaccharide composed of galactose and N-acetyl-galactosamine (GalNAc) that mediates adherence and is required for full virulence. Less pathogenic Aspergillus species were found to produce GAG with a lower GalNAc content than A. fumigatus and expressed minimal amounts of cell wall-bound GAG. Increasing the GalNAc content of GAG of the minimally pathogenic A. nidulans, either through overexpression of the A. nidulans epimerase UgeB or by heterologous expression of the A. fumigatus epimerase Uge3 increased the amount of cell wall bound GAG, augmented adherence in vitro and enhanced virulence in corticosteroid-treated mice to levels similar to A. fumigatus. The enhanced virulence of the overexpression strain of A. nidulans was associated with increased resistance to NADPH oxidase-dependent neutrophil extracellular traps (NETs) in vitro, and was not observed in neutropenic mice or mice deficient in NADPH-oxidase that are unable to form NETs. Collectively, these data suggest that cell wall-bound GAG enhances virulence through mediating resistance to NETs.

The ubiquitous mold A. fumigatus is isolated in over 80% of all patients with invasive aspergillosis (IA). A. nidulans is a relatively non-pathogenic species that rarely causes IA except in patients with chronic granulomatous disease (CGD), a hereditary disease characterized by impaired neutrophil function due to mutations in the NADPH oxidase complex. Here, we demonstrate that one factor underlying the differences in the intrinsic virulence between A. fumigatus and A. nidulans is the amount of the exopolysaccharide galactosaminogalactan that is associated with the cell wall of these species. A. fumigatus produces higher amounts of cell wall-associated galactosaminogalactan and is more resistant than A. nidulans to neutrophil killing by NADPH-oxidase dependent extracellular traps (NETs). Increasing cell wall-associated galactosaminogalactan in A. nidulans enhanced resistance to NETs and increased the virulence of this species to the same level as A. fumigatus in mice with intact NET formation. Collectively, these data suggest that A. nidulans is more sensitive than A. fumigatus to NADPH-oxidase dependent NETosis due to lower levels of cell wall-associated GAG.

Pulmonary solid tumor with coexisting pulmonary aspergillosis: case reports and literature review

BACKGROUND AND AIMS

The association of noncavitary untreated lung cancer with coexisting pulmonary Aspergillosis in immunocompetent patients is an extremely rare occurrence. The present paper aims to summarize the clinical data, and gives an overview of the current knowledge on the etiology, diagnosis and treatment of this condition.

METHODS

We report four cases and review seven cases in the literature.

RESULTS

The four cases describe pulmonary solid tumor with coexisting pulmonary Aspergillosis condition. All cases underwent complicated procession for the terminal diagnosis.

CONCLUSION

Clinicians should be alert to underlying malignant disease if airway Aspergillus infection is suspicious in a patient without strong risk factors for invasive fungal disease. On the other hand, when lung cancer is coexisting with airway necrotizing Aspergillosis, clinicians should properly manage these two diseases simultaneously.

Activation and Function of iNKT and MAIT Cells

Over the last two decades, it has been established that peptides are not the only antigens recognized by T lymphocytes. Here, we review information on two T lymphocyte populations that recognize nonpeptide antigens: invariant natural killer T cells (iNKT cells), which respond to glycolipids, and mucosal associated invariant T cells (MAIT cells), which recognize microbial metabolites. These two populations have a number of striking properties that distinguish them from the majority of T cells. First, their cognate antigens are presented by nonclassical class I antigen-presenting molecules; CD1d for iNKT cells and MR1 for MAIT cells. Second, these T lymphocyte populations have a highly restricted diversity of their T cell antigen receptor α chains. Third, these cells respond rapidly to antigen or cytokine stimulation by producing copious amounts of cytokines, such as IFNγ, which normally are only made by highly differentiated effector T lymphocytes. Because of their response characteristics, iNKT and MAIT cells act at the interface of innate and adaptive immunity, participating in both types of responses. In this review, we will compare these two subsets of innate-like T cells, with an emphasis on the various ways that lead to their activation and their participation in antimicrobial responses.

Aspergillus fumigatus and related species

The genus Aspergillus contains etiologic agents of aspergillosis. The clinical manifestations of the disease range from allergic reaction to invasive pulmonary infection. Among the pathogenic aspergilli, Aspergillus fumigatus is most ubiquitous in the environment and is the major cause of the disease, followed by Aspergillus flavus, Aspergillus niger, Aspergillus terreus, Aspergillus nidulans, and several species in the section Fumigati that morphologically resemble A. fumigatus. Patients that are at risk for acquiring aspergillosis are those with an altered immune system. Early diagnosis, species identification, and adequate antifungal therapy are key elements for treatment of the disease, especially in cases of pulmonary invasive aspergillosis that often advance very rapidly. Incorporating knowledge of the basic biology of Aspergillus species to that of the diseases that they cause is fundamental for further progress in the field.

Genetic and virulence variation in an environmental population of the opportunistic pathogen Aspergillus fumigatus

Environmental populations of the opportunistic pathogen Aspergillus fumigatus have been shown to be genotypically diverse and to contain a range of isolates with varying pathogenic potential. In this study, we combined two RAPD primers to investigate the genetic diversity of environmental isolates from Manchester collected monthly over 1 year alongside Dublin environmental isolates and clinical isolates from patients. RAPD analysis revealed a diverse genotype, but with three major clinical isolate clusters. When the pathogenicity of clinical and Dublin isolates was compared with a random selection of Manchester isolates in a Galleria mellonella larvae model, as a group, clinical isolates were significantly more pathogenic than environmental isolates. Moreover, when relative pathogenicity of individual isolates was compared, clinical isolates were the most pathogenic, Dublin isolates were the least pathogenic and Manchester isolates showed a range in pathogenicity. Overall, this suggests that the environmental population is genetically diverse, displaying a range in pathogenicity, and that the most pathogenic strains from the environment are selected during patient infection.