Interferon-gamma and tumor necrosis factor-alpha protect mice from invasive aspergillosis

KSRP Deficiency Attenuates the Course of Pulmonary Aspergillosis and Is Associated with the Elevated Pathogen-Killing Activity of Innate Myeloid Immune Cells

The mRNA-binding protein KSRP (KH-type splicing regulatory protein) is known to modulate immune cell functions post-transcriptionally, e.g., by reducing the mRNA stability of cytokines. It is known that KSRP binds the AU-rich motifs (ARE) that are often located in the 3'-untranslated part of mRNA species, encoding dynamically regulated proteins as, for example, cytokines. Innate myeloid immune cells, such as polymorphonuclear neutrophils (PMNs) and macrophages (MACs), eliminate pathogens by multiple mechanisms, including phagocytosis and the secretion of chemo- and cytokines. Here, we investigated the role of KSRP in the phenotype and functions of both innate immune cell types in the mouse model of invasive pulmonary aspergillosis (IPA). Here, KSRP-/- mice showed lower levels of Aspergillus fumigatus conidia (AFC) and an increase in the frequencies of PMNs and MACs in the lungs. Our results showed that PMNs and MACs from KSRP-/- mice exhibited an enhanced phagocytic uptake of AFC, accompanied by increased ROS production in PMNs upon stimulation. A comparison of RNA sequencing data revealed that 64 genes related to inflammatory and immune responses were shared between PMNs and MACs. The majority of genes upregulated in PMNs were involved in metabolic processes, cell cycles, and DNA repair. Similarly, KSRP-deficient PMNs displayed reduced levels of apoptosis. In conclusion, our results indicate that KSRP serves as a critical negative regulator of PMN and MAC anti-pathogen activity.

Diagnosis, Prognosticators, and Management of Acute Invasive Fungal Rhinosinusitis: Multidisciplinary Consensus Statement and Evidence-Based Review with Recommendations

BACKGROUND

Acute invasive fungal sinusitis (AIFS) is an aggressive disease that requires prompt diagnosis and multidisciplinary treatment given its rapid progression. However, there is currently no consensus on diagnosis, prognosis, and management strategies for AIFS, with multiple modalities routinely employed. The purpose of this multi-institutional and multidisciplinary evidence-based review with recommendations (EBRR) is to thoroughly review the literature on AIFS, summarize the existing evidence, and provide recommendations on the management of AIFS.

METHODS

The PubMed, EMBASE, and Cochrane databases were systematically reviewed from inception through January 2022. Studies evaluating management for orbital, non-sinonasal head and neck, and intracranial manifestations of AIFS were included. An iterative review process was utilized in accordance with EBRR guidelines. Levels of evidence and recommendations on management principles for AIFS were generated.

RESULTS

A review and evaluation of published literature was performed on 12 topics surrounding AIFS (signs and symptoms, laboratory and microbiology diagnostics, endoscopy, imaging, pathology, surgery, medical therapy, management of extrasinus extension, reversing immunosuppression, and outcomes and survival). The aggregate quality of evidence was varied across reviewed domains.

CONCLUSION

Based on the currently available evidence, judicious utilization of a combination of history and physical examination, laboratory and histopathologic techniques, and endoscopy provide the cornerstone for accurate diagnosis of AIFS. In addition, AIFS is optimally managed by a multidisciplinary team via a combination of surgery (including resection whenever possible), antifungal therapy, and correcting sources of immunosuppression. Higher quality (i.e., prospective) studies are needed to better define the roles of each modality and determine diagnosis and treatment algorithms.

Fungal infections: Immune defense, immunotherapies and vaccines

Invasive fungal infection is an under recognized and emerging global health threat. Recently, the World Health Organization (WHO) released the first ever list of health-threatening fungi to guide research and public health interventions to strengthen global response to fungi infections and antifungal resistance. Currently, antifungal drugs only demonstrate partial success in improving prognosis of infected patients, and this is compounded by the rapid evolution of drug resistance among fungi species. The increased prevalence of fungal infections in individuals with underlying immunological deficiencies reflects the importance of an intact host immune system in controlling mycoses, and further highlights immunomodulation as a potential new avenue for the treatment of disseminated fungal diseases. In this review, we will summarize how host innate immune cells sense invading fungi through their pattern recognition receptors, and subsequently initiate a series of effector mechanisms and adaptive immune responses to mediate fungal clearance. In addition, we will discuss emerging preclinical and clinical data on antifungal immunotherapies and fungal vaccines which can potentially expand our antifungal armamentarium in future.

Protective role of host complement system in Aspergillus fumigatus infection

Invasive aspergillosis (IA) is a life-threatening fungal infection for immunocompromised hosts. It is, therefore, necessary to understand the immune pathways that control this infection. Although the primary infection site is the lungs, aspergillosis can disseminate to other organs through unknown mechanisms. Herein we have examined the in vivo role of various complement pathways as well as the complement receptors C3aR and C5aR1 during experimental systemic infection by Aspergillus fumigatus, the main species responsible for IA. We show that C3 knockout (C3^-/-) mice are highly susceptible to systemic infection of A. fumigatus. Intriguingly, C4^-/- and factor B (FB)^-/- mice showed susceptibility similar to the wild-type mice, suggesting that either the complement pathways display functional redundancy during infection (i.e., one pathway compensates for the loss of the other), or complement is activated non-canonically by A. fumigatus protease. Our in vitro study substantiates the presence of C3 and C5 cleaving proteases in A. fumigatus. Examination of the importance of the terminal complement pathway employing C5^-/- and C5aR1^-/- mice reveals that it plays a vital role in the conidial clearance. This, in part, is due to the increased conidial uptake by phagocytes. Together, our data suggest that the complement deficiency enhances the susceptibility to systemic infection by A. fumigatus.

Cytokine Profile of Invasive Pulmonary Aspergillosis in Severe COVID-19 and Possible Therapeutic Targets

During the SARS-CoV-2 pandemic, a higher incidence of invasive pulmonary aspergillosis was observed in patients affected by Coronavirus disease 2019 (COVID-19), leading to the delineation of a new entity named COVID-19 associated pulmonary aspergillosis (CAPA). A predisposition to invasive infection caused by Aspergillus spp. in SARS-CoV-2 infected patients can be ascribed either to the direct viral-mediated damage of the respiratory epithelium, as already observed in influenza H1N1 virus infections, or to the dysregulated immunity associated with COVID-19. This narrative review focuses on the impact of immune impairment, particularly due to cytokine dysregulation caused by Aspergillus spp. superinfection in COVID-19 for a more in-depth understanding of the molecular pathways implicated in CAPA. As immune competence has proven to be essential in protecting against CAPA onset, a role already threatened by SARS-CoV-2 infection itself, preventive strategies should focus on reducing factors that could further target the host immune system. We also aimed to focus on well-known and less-known risk factors for IPA in COVID-19 patients, related to the main causes of immune suppression, both virus-mediated and iatrogenic, including treatments currently indicated for COVID-19. Lastly, possible preventive strategies aimed at reducing morbidity and mortality due to CAPA could be implemented.

Antifungal Activity of Sodium New Houttuyfonate Against Aspergillus fumigatus in vitro and in vivo

Aspergillus fumigatus is an important pathogen causing invasive aspergillosis, which is associated with high morbidity and mortality in immunocompromised people. However, the treatment of A. fumigatus infection is a growing challenge, owing to the limited availability antifungal agents and the continual emergence of drug-resistant strains. Drug repurposing is a potential strategy to solve this current problem. Sodium new houttuyfonate (SNH), derived from houttuynin, extracted from Houttuynia cordata, has anti-bacterial and anti-Candida albicans effects. However, whether it has anti-A. fumigatus activity had not been reported. In this study, the antifungal properties of SNH against A. fumigatus, including the standard strain AF293, itraconazole resistant clinical strains, and voriconazole resistant clinical strains, were evaluated in vitro and in vivo. Moreover, the potential mechanism of SNH was characterized. SNH exhibited significant fungicidal activity toward various A. fumigatus strains. SNH also inhibited fungal growth, sporulation, conidial germination and pigment formation, and biofilm formation. Further investigations revealed that SNH interfered with the A. fumigatus cell steroid synthesis pathway, as indicated by transcriptomic and quantitative real-time polymerase chain reaction analyses, and inhibited ergosterol synthesis, as indicated by cell membrane stress assays and ergosterol quantification. Moreover, daily gastric gavage of SNH significantly decreased the fungal burden in mice with disseminated infection (kidney, liver, and lung) and local tissue damage. In addition, the application of SNH downregulated the production of IL-6 and IL-17A. Together, these findings provided the first confirmation that SNH may be a promising antifungal agent for the treatment of A. fumigatus infection.

Genetic Vaccination as a Flexible Tool to Overcome the Immunological Complexity of Invasive Fungal Infections

The COVID-19 pandemic has highlighted genetic vaccination as a powerful and cost-effective tool to counteract infectious diseases. Invasive fungal infections (IFI) remain a major challenge among immune compromised patients, particularly those undergoing allogeneic hematopoietic bone marrow transplantation (HSCT) or solid organ transplant (SOT) both presenting high morbidity and mortality rates. Candidiasis and Aspergillosis are the major fungal infections among these patients and the failure of current antifungal therapies call for new therapeutic aids. Vaccination represents a valid alternative, and proof of concept of the efficacy of this approach has been provided at clinical level. This review will analyze current understanding of antifungal immunology, with a particular focus on genetic vaccination as a suitable strategy to counteract these diseases.

IFN-γ Mediated Signaling Improves Fungal Clearance in Experimental Pulmonary Mucormycosis

We established three immunocompetent murine models of pulmonary mucormycosis to determine the involvement of the adaptive immune response in host resistance in pulmonary mucormycosis, a rapidly fatal disease caused mainly by Rhizopus spp. Immunocompetent inbred (C57BL/6, BALB/c) and outbred (Swiss) strains of mice were inoculated with R. oryzae via the intratracheal route. The inoculation resulted in a disseminated infection that spread to the brain, spleen, kidney, and liver. After 7 and 30 days of R. oryzae infection, BALB/c mice showed the lowest fungal load and highest production of IFN-γ and IL-2 by splenocytes. Swiss mice showed a higher fungal load 30 days p.i. and was associated with a weak development of the Th-1 profile. To confirm our findings, R. oryzae-infected IFN-γ⁻/⁻ mice were evaluated after 60 days, where the mice still showed viable fungi in the lungs. This study showed, for the first time, that pulmonary mucormycosis in three widely used mouse strains resulted in an acute fungal dissemination without immunosuppression whose outcome varies according to the genetic background of the mice. We also identified the partial role of IFN-γ in the efficient elimination of R. oryzae during pulmonary infection.

Microbiome in human cancers

A microbiome is defined as the aggregate of all microbiota that reside in human digestive system and other tissues. This microbiota includes viruses, bacteria, fungi that live in various human organs and tissues like stomach, guts, oesophagus, mouth cavity, urinary tract, vagina, lungs, and skin. Almost 20 % of malignant cancers worldwide are related to microbial infections including bacteria, parasites, and viruses. The human body is constantly being attacked by microbes during its lifetime and microbial pathogens that have tumorigenic effects in 15-20 % of reported cancer cases. Recent scientific advances and the discovery of the effect of microbes on cancer as a pathogen or as a drug have significantly contributed to our understanding of the complex relationship between microbiome and cancer. The aim of this study is to overview some microbiomes that reside in the human body and their roles in cancer.

Fungal vaccines

Invasive fungal disease continues to be a cause of significant life-threatening morbidity and mortality in humans, particularly in those with a diminished immune system, such as with haematological malignancies. The mainstay of treating such life-threatening fungal infection has been antifungal drugs, including azoles, echinocandins and macrocyclic polyenes. However, like antibiotic resistance, antifungal resistance is beginning to emerge, potentially jeopardizing the effectiveness of these molecules in the treatment of fungal disease. One strategy to avoid this is the development of fungal vaccines. However, the inability to provoke a sufficient immune response in the most vulnerable immunocompromised groups has hindered translation from bench to bedside. This review will assess the latest available data and will investigate potential Aspergillus antigens and feasible vaccine techniques, particularly for vaccination of high-risk groups, including immunocompromised and immunosuppressed populations.

Navigating the uncertainties of COVID-19 associated aspergillosis (CAPA): A comparison with influenza associated aspergillosis (IAPA)

Invasive pulmonary aspergillosis (IPA) is increasingly recognized as a life-threatening superinfection of severe respiratory viral infections, such as influenza. The pandemic of Coronavirus Disease 2019 (COVID-19) due to emerging SARS-CoV-2 rose concern about the eventuality of IPA complicating COVID-19 in intensive care unit mechanically-ventilated patients. While the association between severe influenza and IPA has been demonstrated, it remains unclear whether SARS-CoV-2 infection represents a specific risk factor for IPA. A variable incidence of such complication has been previously reported, which can be partly attributed to differences in diagnostic strategy and IPA definitions, and possibly local environmental/epidemiological factors. In this article, we discuss the similarities and differences between influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA). Compared to IAPA, the majority of CAPA cases have been classified as putative rather than proven/probable IPA, in the absence of positive serum galactomannan or histopathologic evidence of angio-invasion. Discrimination between Aspergillus airways colonization and CAPA is difficult. Distinct physiopathology and cytokine profiles of influenza and COVID-19 may explain these discrepancies. Whether CAPA represents a distinct entity is still debatable and many questions remain unanswered, such as its actual incidence, the predisposing role of corticosteroids or immunomodulatory drugs, and the indications for antifungal therapy.

Type I Natural Killer T Cells as Key Regulators of the Immune Response to Infectious Diseases

The immune system must work in an orchestrated way to achieve an optimal response upon detection of antigens. The cells comprising the immune response are traditionally divided into two major subsets, innate and adaptive, with particular characteristics for each type. Type I natural killer T (iNKT) cells are defined as innate-like T cells sharing features with both traditional adaptive and innate cells, such as the expression of an invariant T cell receptor (TCR) and several NK receptors. The invariant TCR in iNKT cells interacts with CD1d, a major histocompatibility complex class I (MHC-I)-like molecule. CD1d can bind and present antigens of lipid nature and induce the activation of iNKT cells, leading to the secretion of various cytokines, such as gamma interferon (IFN-γ) and interleukin 4 (IL-4). These cytokines will aid in the activation of other immune cells following stimulation of iNKT cells. Several molecules with the capacity to bind to CD1d have been discovered, including α-galactosylceramide. Likewise, several molecules have been synthesized that are capable of polarizing iNKT cells into different profiles, either pro- or anti-inflammatory. This versatility allows NKT cells to either aid or impair the clearance of pathogens or to even control or increase the symptoms associated with pathogenic infections. Such diverse contributions of NKT cells to infectious diseases are supported by several publications showing either a beneficial or detrimental role of these cells during diseases. In this article, we discuss current data relative to iNKT cells and their features, with an emphasis on their driving role in diseases produced by pathogenic agents in an organ-oriented fashion.

Role for IL-1 Family Cytokines in Fungal Infections

Fungal pathogens kill approximately 1.5 million individuals per year and represent a severe disease burden worldwide. It is estimated over 150 million people have serious fungal disease such as recurrent mucosal infections or life-threatening systemic infections. Disease can ensue from commensal fungi or new infection and involves different fungal morphologies and the expression of virulence factors. Therefore, anti-fungal immunity is complex and requires coordination between multiple facets of the immune system. IL-1 family cytokines are associated with acute and chronic inflammation and are essential for the innate response to infection. Recent research indicates IL-1 cytokines play a key role mediating immunity against different fungal infections. During mucosal disease, IL-1R and IL-36R are required for neutrophil recruitment and protective Th17 responses, but function through different mechanisms. During systemic disease, IL-18 drives protective Th1 responses, while IL-33 promotes Th2 and suppresses Th1 immunity. The IL-1 family represents an attractive anti-fungal immunotherapy target. There is a need for novel anti-fungal therapeutics, as current therapies are ineffective, toxic and encounter resistance, and no anti-fungal vaccine exists. Furthering our understanding of the IL-1 family cytokines and their complex role during fungal infection may aid the development of novel therapies. As such, this review will discuss the role for IL-1 family cytokines in fungal infections.

Fungal natural products galaxy: Biochemistry and molecular genetics toward blockbuster drugs discovery

Secondary metabolites synthesized by fungi have become a precious source of inspiration for the design of novel drugs. Indeed, fungi are prolific producers of fascinating, diverse, structurally complex, and low-molecular-mass natural products with high therapeutic leads, such as novel antimicrobial compounds, anticancer compounds, immunosuppressive agents, among others. Given that these microorganisms possess the extraordinary capacity to secrete diverse chemical scaffolds, they have been highly exploited by the giant pharma companies to generate small molecules. This has been made possible because the isolation of metabolites from fungal natural sources is feasible and surpasses the organic synthesis of compounds, which otherwise remains a significant bottleneck in the drug discovery process. Here in this comprehensive review, we have discussed recent studies on different fungi (pathogenic, non-pathogenic, commensal, and endophytic/symbiotic) from different habitats (terrestrial and marines), the specialized metabolites they biosynthesize, and the drugs derived from these specialized metabolites. Moreover, we have unveiled the logic behind the biosynthesis of vital chemical scaffolds, such as NRPS, PKS, PKS-NRPS hybrid, RiPPS, terpenoids, indole alkaloids, and their genetic mechanisms. Besides, we have provided a glimpse of the concept behind mycotoxins, virulence factor, and host immune response based on fungal infections.

Novel Antifungal Agents and Their Activity against Aspergillus Species

There is a need for new antifungal agents, mainly due to increased incidence of invasive fungal infections (IFI), high frequency of associated morbidity and mortality and limitations of the current antifungal agents (e.g., toxicity, drug-drug interactions, and resistance). The clinically available antifungals for IFI are restricted to four main classes: polyenes, flucytosine, triazoles, and echinocandins. Several antifungals are hampered by multiple resistance mechanisms being present in fungi. Consequently, novel antifungal agents with new targets and modified chemical structures are required to combat fungal infections. This review will describe novel antifungals, with a focus on the Aspergillus species.

Immunomodulation for the Treatment of Fungal Infections: Opportunities and Challenges

Opportunistic fungal infections are major causes of morbidity and mortality in patients with single or multiple defects in their immunity. Antifungal agents targeting the pathogen remain the treatment of choice for fungal infections. However, antifungal agents are toxic to the host mainly due to the close evolutionary similarity of fungi and humans. Moreover, antifungal therapy is ineffective in patients with immunosuppression. For this reason, there is an increased demand to develop novel strategies to enhance immune function and augment the existing antifungal drugs. In recent times, targeting the immune system to improve impaired host immune responses becomes a reasonable approach to improve the effectiveness of antifungal drugs. In this regard, immunomodulating therapeutic agents that turn up the immune response in the fight against fungal infections hold promise for enhancing the efficacy and safety of conventional antifungal therapy. In general, immunomodulating therapies are safe with decreased risk of resistance and broad spectrum of activity. In this review, therefore, clinical evidences supporting the opportunities and challenges of immunomodulation therapies in the treatment of invasive fungal infections are included.

Influenza Suppresses Neutrophil Recruitment to the Lung and Exacerbates Secondary Invasive Pulmonary Aspergillosis

Aspergillus fumigatus is an environmental fungus that can cause invasive pulmonary aspergillosis when spores are inhaled into the respiratory tract and invade airway or lung tissue. Influenza is a common respiratory virus that can cause severe respiratory disease, and postinfluenza invasive pulmonary aspergillosis, which is becoming a well-recognized clinical problem, typically occurs in critically ill patients. Mice challenged with influenza A PR/8/34 H1N1 and subsequently challenged with A. fumigatus had increased fungal burden, viral burden, inflammation, and mortality compared with single infected mice. Neutrophil recruitment in the lung of superinfected mice was decreased; however, mice were not neutropenic, and there was no difference in absolute blood neutrophils between groups. Additionally, CXCL1 and CXCL2 were decreased in lungs of superinfected mice compared with controls. IFN levels were increased in mice that received influenza, and deletion of STAT1 resulted in decreased fungal burden, increased airway and lung neutrophils, and increased CXCL1 compared with wild-type mice, whereas deletion of STAT2 did not change fungal burden or airway neutrophilia compared with wild-type mice. These data demonstrate a mechanism by which influenza A-induced STAT1 signaling inhibits neutrophil recruitment and increases susceptibility to postinfluenza invasive pulmonary aspergillosis.

Immunotherapy as an Antifungal Strategy in Immune Compromised Hosts

Purpose of Review

IFIs cause high morbidity and mortality in the immunocompromised host worldwide. Although highly effective, conventional antifungal chemotherapy faces new challenges due to late diagnosis and increasing numbers of drug-resistant fungal strains. Thus, antifungal immunotherapy represents a viable treatment option, and recent advances in the field are summarized in this review.

Recent Findings

Antifungal immunotherapies include application of immune cells as well as the administration of cytokines, growth factors, and antibodies. Novel strategies to treat IFIs in the immunocompromised host target intracellular signaling pathways using SMTs such as checkpoint inhibitors.

Summary

Studies using cytokines or chemokines exerted a potential adjuvant role to conventional antifungal therapy, but issues on toxicity for some agents have to be resolved. Cell-based immunotherapies are very labor-intense and costly, but NK cell transfer and CAR T cell therapy provide exciting strategies to combat IFIs. Antibody-mediated protection and checkpoint inhibition are additional novel immunotherapeutic approaches.

Aspergillus fumigatus Infection in Humans With STAT3-Deficiency Is Associated With Defective Interferon-Gamma and Th17 Responses

In humans, loss-of-function mutation in the Signal Transducer and Activator of Transcription 3 (STAT3) gene is frequently associated with susceptibility to bacterial as well as fungal infections including aspergillosis, although its pathogenesis remains largely unknown. In the present study, we investigated the immune responses obtained after stimulation with Aspergillus fumigatus in STAT3-deficient patients. A. fumigatus conidial killing efficiencies of both monocytes and neutrophils isolated from whole blood samples of STAT3-deficient patients were not different compared to those of healthy controls. After stimulation with A. fumigatus conidia, lower concentrations of adaptive cytokines (IFN-γ, IL-17 and IL-22) were secreted by peripheral blood mononuclear cells from STAT3-deficient patients compared to those from healthy controls. Moreover, the frequency of IFN-γ and IL-17 producing CD4+ T cells was lower in STAT3-deficient patients vs. healthy controls. Among the STAT3-deficient patients, those with aspergillosis showed further lower secretion of IFN-γ upon stimulation of their PBMCs with A. fumigatus conidia compared to the patients without aspergillosis. Together, our study indicated that STAT3-deficiency leads to a defective adaptive immune response against A. fumigatus infection, particularly with a lower IFN-γ and IL-17 responses in those with aspergillosis, suggesting potential therapeutic benefit of recombinant IFN-γ in STAT3-deficient patients with aspergillosis.

Invasive Aspergillosis in solid-organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated AST-IDCOP guidelines provide information on epidemiology, diagnosis, and management of Aspergillus after organ transplantation. Aspergillus is the most common invasive mold infection in solid-organ transplant (SOT) recipients, and it is the most common invasive fungal infection among lung transplant recipients. Time from transplant to diagnosis of invasive aspergillosis (IA) is variable, but most cases present within the first year post-transplant, with shortest time to onset among liver and heart transplant recipients. The overall 12-week mortality of IA in SOT exceeds 20%; prognosis is worse among those with central nervous system involvement or disseminated disease. Bronchoalveolar lavage galactomannan is preferred for the diagnosis of IA in lung and non-lung transplant recipients, in combination with other diagnostic modalities (eg, chest CT scan, culture). Voriconazole remains the drug of choice to treat IA, with isavuconazole and lipid formulations of amphotericin B regarded as alternative agents. The role of combination antifungals for primary therapy of IA remains controversial. Either universal prophylaxis or preemptive therapy is recommended in lung transplant recipients, whereas targeted prophylaxis is favored in liver and heart transplant recipients. In these guidelines, we also discuss newer antifungals and diagnostic tests, antifungal susceptibility testing, and special patient populations.

Immunomodulation as a Therapy for Aspergillus Infection: Current Status and Future Perspectives

Invasive aspergillosis (IA) is the most serious life-threatening infectious complication of intensive remission induction chemotherapy and allogeneic stem cell transplantation in patients with a variety of hematological malignancies. Aspergillus fumigatus is the most commonly isolated species from cases of IA. Despite the various improvements that have been made with preventative strategies and the development of antifungal drugs, there is an urgent need for new therapeutic approaches that focus on strategies to boost the host’s immune response, since immunological recovery is recognized as being the major determinant of the outcome of IA. Here, we aim to summarize current knowledge about a broad variety of immunotherapeutic approaches against IA, including therapies based on the transfer of distinct immune cell populations, and the administration of cytokines and antibodies.

Aspergillus fumigatus conidia stimulate lung epithelial cells (TC-1 JHU-1) to produce IL-12, IFNγ, IL-13 and IL-17 cytokines: Modulatory effect of propolis extract

Aspergillus fumigatus conidia are the most prevalent indoors fungal allergens. The interaction between Aspergillus antigens and lung epithelial cells (LECs) result in innate immune functions. The association between Aspergillus conidia and allergic reactions, like allergic bronchopulmonary aspergillosis (ABPA) and asthma have been repeatedly reported. Since conventional therapies for allergy and asthma are limited, finding new promising treatments are inevitable. This study was designed to evaluate the effect of A. fumigatus conidia on IL-12, IFNγ, IL-13 and IL-17 release from mouse LECs and to investigate the effect of propolis on cytokines modulation. Cells were divided to two groups, one was exposed to 3×10⁴ conidia of Aspergillus fumigatus and another group was treated by propolis (25μg/mL) as well as exposed to A. fumigatus conidia. Cytokines IL-13, IL-12, IFNγ and IL-17 were measured at times 0, 6 and 12hours after exposure using ELISA assay. The results indicated that A. fumigatus could increase the release of the cytokines with IL-13 and IL-17 being the most affected ones whilst treatment with propolis decreased the effects of A. fumigatus on IL-13 and IL-17 production. The results showed that propolis has down regulatory effects on Th2 cytokine, IL-13, and IL-17 production, whereas it caused a significant induction of IL-12, as an important Th1 cytokines by LECs. With respect to the obtained results, propolis extract might be contributed to decrease Th2 responses in allergic asthma phenomenon. However more investigations must be done in future to fully understand its efficacy.

Adjunctive interferon-γ immunotherapy in a pediatric case of Aspergillus terreus infection

Aspergillus terreus causes invasive aspergillosis (IA) in immunocompromised patients. Treatment is complicated by intrinsic resistance to amphotericin B and thereby contributing to a high mortality. Therefore, we conducted in vitro studies to investigate the effectivity of adjunctive recombinant interferon-γ immunotherapy. We describe a pediatric patient with A. terreus IA who received adjunctive recombinant interferon-γ (rIFNγ) immunotherapy. In vitro studies were conducted to investigate the capacity of rIFNγ to improve antifungal host defense in terms of fungal killing ability and the release of pro-inflammatory cytokines in cells of the patient as well as healthy controls. An 8-year-old female pediatric patient with leukemia developed A. terreus IA. She clinically deteriorated and had high serum galactomannan levels despite broad antifungal therapy. Therefore, adjunctive immune stimulatory therapy with rIFNγ was initiated. After 3 weeks of treatment, galactomannan levels decreased and the patient clinically showed improvement. Addition of rIFNγ boosted the capacity of monocytes of healthy volunteers to mount TNFα and IL-1β cytokine responses to Escherichia coli LPS, and increased TNFα response to both A. terreus and Aspergillus fumigatus. Monocytes isolated from the patient's blood demonstrated a similar augmented cytokine induction in response to rIFNγ. In addition, rIFNγ increased the capacity of monocytes from healthy volunteers as well as monocytes from the patient to kill A. terreus spores. Adjuvant immunotherapy with rIFNγ might be a promising additional treatment strategy that could be used to improve outcome in patients with refractory invasive A. terreus infections or other resistant invasive Aspergillus infections.

Emerging IL-12 family cytokines in the fight against fungal infections

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IL-12 and IL-23 have established roles during anti-fungal immunity.

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IL-27 promotes regulatory effector responses during fungal infections.

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IL-35 drives T cell differentiation to produce anti-inflammatory responses.

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Increasing evidence for IL-12 family cytokines in maintaining anti-fungal immune homeostasis.

Invasive fungal infections cause approximately 1.5 million deaths per year worldwide and are a growing threat to human health. Current anti-fungal therapies are often insufficient, therefore studies into host-pathogen interactions are critical for the development of novel therapies to improve mortality rates. Myeloid cells, such as macrophages and dendritic cells, express pattern recognition receptor (PRRs), which are important for fungal recognition. Engagement of these PRRs by fungal pathogens induces multiple cytokines, which in turn activate T effector responses. Interleukin (IL)-12 family members (IL-12p70, IL-23, IL-27 and IL-35) link innate immunity with the development of adaptive immunity and are also important for regulating T cell responses. IL-12 and IL-23 have established roles during anti-fungal immunity, whereas emerging roles for IL-27 and IL-35 have recently been reported. Here, we discuss the IL-12 family, focusing on IL-27 and IL-35 during anti-fungal immune responses to pathogens such as Candida and Aspergillus.

Quantitative Simulations Predict Treatment Strategies Against Fungal Infections in Virtual Neutropenic Patients

The condition of neutropenia, i.e., a reduced absolute neutrophil count in blood, constitutes a major risk factor for severe infections in the affected patients. Candida albicans and Candida glabrata are opportunistic pathogens and the most prevalent fungal species in the human microbiota. In immunocompromised patients, they can become pathogenic and cause infections with high mortality rates. In this study, we use a previously established approach that combines experiments and computational models to investigate the innate immune response during blood stream infections with the two fungal pathogens C. albicans and C. glabrata. First, we determine immune-reaction rates and migration parameters under healthy conditions. Based on these findings, we simulate virtual patients and investigate the impact of neutropenic conditions on the infection outcome with the respective pathogen. Furthermore, we perform in silico treatments of these virtual patients by simulating a medical treatment that enhances neutrophil activity in terms of phagocytosis and migration. We quantify the infection outcome by comparing the response to the two fungal pathogens relative to non-neutropenic individuals. The analysis reveals that these fungal infections in neutropenic patients can be successfully cleared by cytokine treatment of the remaining neutrophils; and that this treatment is more effective for C. glabrata than for C. albicans.

Investigation of Aspergillus flavus in animal virulence

Aspergillus flavus is a common fungal pathogen of plants, animals and humans. Recently, many genes of A. flavus have been reported involving in regulation of pathogenesis in crops, but whether these genes are involved in animal virulence is still unknown. Here, we used a previous easy-to-use infection model for A. flavus based on mouse model by intravenous inoculation of A. flavus conidia. The outcome of infections in mice model showed that A. flavus NRRL3357 and laboratory strain CA14 PTS were both in dose dependent manner and highly reproducible. The progress of disease could be monitored by mice survival and histology analysis. Fungal burden analysis indicated it was gradually decreased within 7 days after infection. Moreover, aspergillosis caused by A. flavus significantly up-regulated gene expression levels of immune response mediators, including INF-γ, TNF-α, Dectin-1 and TLR2. Furthermore, the defined deletion A. flavus strains that previously displayed virulence in crop infection were also determined in this mouse model, and the results showed comparable degrees of infection in mice. Our results suggested that intravenous inoculation of conidia could be a suitable model for testing different A. flavus mutants in animal virulence. We hope to use this model to determine distinct A. flavus strains virulence in animals and study novel therapeutic methods to help control fungus diseases in the future.

Fungal melanin stimulates surfactant protein D-mediated opsonization of and host immune response to Aspergillus fumigatus spores

Surfactant protein D (SP-D), a C-type lectin and pattern-recognition soluble factor, plays an important role in immune surveillance to detect and eliminate human pulmonary pathogens. SP-D has been shown to protect against infections with the most ubiquitous airborne fungal pathogen, Aspergillus fumigatus, but the fungal surface component(s) interacting with SP-D is unknown. Here, we show that SP-D binds to melanin pigment on the surface of A. fumigatus dormant spores (conidia). SP-D also exhibited an affinity to two cell-wall polysaccharides of A. fumigatus, galactomannan (GM) and galactosaminogalactan (GAG). The immunolabeling pattern of SP-D was punctate on the conidial surface and was uniform on germinating conidia, in accordance with the localization of melanin, GM, and GAG. We also found that the collagen-like domain of SP-D is involved in its interaction with melanin, whereas its carbohydrate-recognition domain recognized GM and GAG. Unlike un-opsonized conidia, SP-D-opsonized conidia were phagocytosed more efficiently and stimulated the secretion of proinflammatory cytokines by human monocyte-derived macrophages. Furthermore, SP-D^-/- mice challenged intranasally with wildtype conidia or melanin ghosts (i.e. hollow melanin spheres) displayed significantly reduced proinflammatory cytokines in the lung compared with wildtype mice. In summary, SP-D binds to melanin present on the dormant A. fumigatus conidial surface, facilitates conidial phagocytosis, and stimulates the host immune response.

Natural Killer Cells in Antifungal Immunity

Invasive fungal infections are still an important cause of morbidity and mortality in immunocompromised patients such as patients suffering from hematological malignancies or patients undergoing hematopoietic stem cell transplantion. In addition, other populations such as human immunodeficiency virus-patients are at higher risk for invasive fungal infection. Despite the availability of new antifungal compounds and better supportive care measures, the fatality rate of invasive fungal infection remained unacceptably high. It is therefore of major interest to improve our understanding of the host-pathogen interaction to develop new therapeutic approaches such as adoptive immunotherapy. As experimental methodologies have improved and we now better understand the complex network of the immune system, the insight in the interaction of the host with the fungus has significantly increased. It has become clear that host resistance to fungal infections is not only associated with strong innate immunity but that adaptive immunity (e.g., T cells) also plays an important role. The antifungal activity of natural killer (NK) cells has been underestimated for a long time. In vitro studies demonstrated that NK cells from murine and human origin are able to attack fungi of different genera and species. NK cells exhibit not only a direct antifungal activity via cytotoxic molecules but also an indirect antifungal activity via cytokines. However, it has been show that fungi exert immunosuppressive effects on NK cells. Whereas clinical data are scarce, animal models have clearly demonstrated that NK cells play an important role in the host response against invasive fungal infections. In this review, we summarize clinical data as well as results from in vitro and animal studies on the impact of NK cells on fungal pathogens.

The Multifaceted Role of T-Helper Responses in Host Defense against Aspergillus fumigatus

The ubiquitous opportunistic fungal pathogen Aspergillus fumigatus rarely causes infections in immunocompetent individuals. A healthy functional innate immune system plays a crucial role in preventing Aspergillus-infection. This pivotal role for the innate immune system makes it a main research focus in studying the pathogenesis of aspergillosis. Although sometimes overshadowed by the innate immune response, the adaptive immune response, and in particular T-helper responses, also represents a key player in host defense against Aspergillus. Virtually all T-helper subsets have been described to play a role during aspergillosis, with the Th1 response being crucial for fungal clearance. However; morbidity and mortality of aspergillosis can also be partly attributed to detrimental immune responses resulting from adaptive immune activation. Th2 responses benefit fungal persistence; and are the foundation of allergic forms of aspergillosis. The Th17 response has two sides; although crucial for granulocyte recruitment, it can be involved in detrimental immunopathology. Regulatory T-cells, the endogenous regulators of inflammatory responses, play a key role in controlling detrimental inflammatory responses during aspergillosis. The current knowledge of the adaptive immune response against A. fumigatus is summarized in this review. A better understanding on how T-helper responses facilitate clearance of Aspergillus-infection and control inflammation can be the fundamental basis for understanding the pathogenesis of aspergillosis and for the development of novel host-directed therapies.

Immunotherapeutic approaches to treatment of fungal diseases

Fungal infections cause morbidity worldwide and are associated with an unacceptably high mortality despite the availability of antifungal drugs. The incidence of mycoses is rising because of the HIV pandemic and because immunomodulatory drugs are increasingly used to treat autoimmune diseases and cancer. New classes of antifungal drugs have only been partly successful in improving the prognosis for patients with fungal infection. Adjunctive host-directed therapy is therefore believed to be the only option to further improve patient outcomes. Recent advances in the understanding of complex interactions between fungi and host have led to the design and exploration of novel therapeutic strategies in cytokine therapy, vaccines, and cellular immunotherapy, each of which might become viable adjuncts to existing antifungal regimens. In this report, we discuss immunotherapeutic approaches-the rationale behind their design, the challenges in their use, and the progress that is so urgently needed to overcome the devastating effect of fungal diseases.

Polymorphisms in Host Immunity-Modulating Genes and Risk of Invasive Aspergillosis: Results from the AspBIOmics Consortium

Recent studies suggest that immune-modulating single-nucleotide polymorphisms (SNPs) influence the risk of developing cancer-related infections. Here, we evaluated whether 36 SNPs within 14 immune-related genes are associated with the risk of invasive aspergillosis (IA) and whether genotyping of these variants might improve disease risk prediction. We conducted a case-control association study of 781 immunocompromised patients, 149 of whom were diagnosed with IA. Association analysis showed that the IL4Rrs2107356 and IL8rs2227307 SNPs (using dbSNP numbering) were associated with an increased risk of IA (IL4Rrs2107356 odds ratio [OR], 1.92; 95% confidence interval [CI], 1.20 to 3.09; IL8rs2227307 OR, 1.73; 95% CI, 1.06 to 2.81), whereas the IL12Brs3212227 and IFNγrs2069705 variants were significantly associated with a decreased risk of developing the infection (IL12Brs3212227 OR, 0.60; 95% CI, 0.38 to 0.96; IFNγrs2069705 OR, 0.63; 95% CI, 0.41 to 0.97). An allogeneic hematopoietic stem cell transplantation (allo-HSCT)-stratified analysis revealed that the effect observed for the IL4Rrs2107356 and IFNγrs2069705 SNPs was stronger in allo-HSCT (IL4Rrs2107356 OR, 5.63; 95% CI, 1.20 to 3.09; IFNγrs2069705 OR, 0.24; 95% CI, 0.10 to 0.59) than in non-HSCT patients, suggesting that the presence of these SNPs renders patients more vulnerable to infection, especially under severe and prolonged immunosuppressive conditions. Importantly, in vitro studies revealed that carriers of the IFNγrs2069705C allele showed a significantly increased macrophage-mediated neutralization of fungal conidia (P = 0.0003) and, under stimulation conditions, produced higher levels of gamma interferon (IFNγ) mRNA (P = 0.049) and IFNγ and tumor necrosis factor alpha (TNF-α) cytokines (P value for 96 h of treatment with lipopolysaccharide [PLPS-96 h], 0.057; P value for 96 h of treatment with phytohemagglutinin [PPHA-96 h], 0.036; PLPS+PHA-96 h = 0.030; PPHA-72 h = 0.045; PLPS+PHA-72 h = 0.018; PLPS-96 h = 0.058; PLPS+PHA-96 h = 0.0058). Finally, we also observed that the addition of SNPs significantly associated with IA to a model including clinical variables led to a substantial improvement in the discriminatory ability to predict disease (area under the concentration-time curve [AUC] of 0.659 versus AUC of 0.564; P-2 log likehood ratio test = 5.2 · 10(-4) and P50.000 permutation test = 9.34 · 10(-5)). These findings suggest that the IFNγrs2069705 SNP influences the risk of IA and that predictive models built with IFNγ, IL8, IL12p70, and VEGFA variants can used to predict disease risk and to implement risk-adapted prophylaxis or diagnostic strategies.

Stimulation with lysates of Aspergillus terreus, Candida krusei and Rhizopus oryzae maximizes cross-reactivity of anti-fungal T cells

BACKGROUND AIMS

Invasive fungal diseases caused by filamentous fungi and yeasts are significant causes of morbidity and mortality in immunosuppressed hematology patients. We previously published a method to expand Aspergillus fumigatus-specific T cells for clinical cell therapy. In the present study, we investigated expansion of T cells specific for other fungal pathogens and creation of a broadly reactive panfungal T-cell product.

METHODS

Fungal strains selected were those frequently observed in the clinical hematology setting and included Aspergillus, Candida, Fusarium, Rhizopus and Lomentospora/Scedosporium. Four T-cell cultures specific to each fungus were established. We selected lysates of Aspergillus terreus, Candida krusei and Rhizopus oryzae to expand panfungal T cells. Allelic restriction of anti-fungal activity was determined through the use of specific major histocompatibility complex class II-blocking antibodies.

RESULTS

Individual T-cell cultures specific to each fungus could be expanded in vitro, generating predominantly CD4(+) T cells of which 8% to 20% were fungus-specific. We successfully expanded panfungal T cells from the peripheral blood (n = 8) and granulocyte-colony-stimulating factor-primed stem cell products (n = 3) of normal donors by using a combination of lysates from Aspergillus terreus, Candida krusei and Rhizopus oryzae. Anti-fungal activity was mediated through human leukocyte antigen (HLA)-DR alleles and was maintained when antigen-presenting cells from partially HLA-DRB1-matched donors were used to stimulate T cells.

CONCLUSIONS

We demonstrate a method to manufacture panfungal T-cell products with specificity against a range of clinical fungal pathogens by use of the blood and stem cells of healthy donors as the starting material. The safety and efficacy of these products will need to be tested clinically.

Human Invariant Natural Killer T cells possess immune-modulating functions during Aspergillus infection

Aspergillus fumigatus is the most common cause for invasive fungal infections, a disease associated with high mortality in immune-compromised patients. CD1d-restricted invariant natural killer T (iNKT) cells compose a small subset of T cells known to impact the immune response toward various infectious pathogens. To investigate the role of human iNKT cells during A. fumigatus infection, we studied their activation as determined by CD69 expression and cytokine production in response to distinct fungal morphotypes in the presence of different CD1d(+) antigen presenting cells using flow cytometry and multiplex enzyme-linked immunosorbent assay (ELISA). Among CD1d(+) subpopulations, CD1d(+)CD1c(+) mDCs showed the highest potential to activate iNKT cells on a per cell basis. The presence of A. fumigatus decreased this effect of CD1d(+)CD1c(+) mDCs on iNKT cells and led to reduced secretion of TNF-α, G-CSF and RANTES. Production of other Th1 and Th2 cytokines was not affected by the fungus, suggesting an immune-modulating function for human iNKT cells during A. fumigatus infection.

Adoptive T-cell therapy for fungal infections in haematology patients

The prolonged immune deficiency resulting from haematopoietic stem cell transplant and chemotherapy predisposes to a high risk of invasive fungal infections. Despite the recent advances in molecular diagnostic testing, early initiation of pre-emptive antifungal therapy and the use of combination pharmacotherapy, mortality from invasive mould infections remain high among recipients of allogeneic stem cell transplant. The increasing incidences of previously rare and drug-resistant strains of fungi present a further clinical challenge. Therefore, there is a need for novel strategies to combat fungal infections in the immunocompromised. Adoptive therapy using in vitro-expanded fungus-specific CD4 cells of the Th-1 type has shown clinical efficacy in murine studies and in a small human clinical study. Several techniques for the isolation and expansion of fungus-specific T cells have been successfully applied. Here we discuss the incidence and changing patterns of invasive fungal diseases, clinical evidence supporting the role of T cells in fungal immunity, methods to expand fungus-specific T cells in the laboratory and considerations surrounding the use of T cells for fungal immunotherapy.

Nebulised amphotericin B-polymethacrylic acid nanoparticle prophylaxis prevents invasive aspergillosis

Aspergillus species are the major life threatening fungal pathogens in transplant patients. Germination of inhaled fungal spores initiates infection, causes severe pneumonia, and has a mortality of > 50%. This is leading to the consideration of pre-exposure prophylaxis to prevent infection. We made a very low MWt amphotericin B-polymethacrylic acid nanoparticle. It was not toxic to lung epithelial cells or monocyte-derived-macrophages in-vitro, or in an in-vivo transplant immuno-suppression mouse model of life threatening invasive aspergillosis. Three days of nebuliser based prophylaxis delivered the nanoparticle effectively to lung and prevented both fungal growth and lung inflammation. Protection from disease was associated with > 99% killing of the Aspergillus and a 90% reduction in lung TNF-α; the primary driver of tissue destructive immuno-pathology. This study provides in-vivo proof-of-principle that very small and cost-effective nanoparticles can be made simply, and delivered safely and effectively to lung by the aerosol route to prevent fungal infections.

From the Clinical Editor

Aspergillus is an opportunistic pathogen, which affects immunocompromised patients. One novel way to help fight against this infection is pre-exposure prophylaxis. The authors here made PMA based anionic hydrogels carrying amphotericin B, with mucoadhesive behavior. They showed that aerosol route of the drug was very effective in protecting against the disease in an in-vivo model and should provide a stepping-stone towards clinical trials in the future.

Adaptive immunity to fungi

Life-threatening fungal infections have risen sharply in recent years, owing to the advances and intensity of medical care that may blunt immunity in patients. This emerging crisis has created the growing need to clarify immune defense mechanisms against fungi with the ultimate goal of therapeutic intervention. We describe recent insights in understanding the mammalian immune defenses that are deployed against pathogenic fungi. We focus on adaptive immunity to the major medically important fungi and emphasize three elements that coordinate the response: (1) dendritic cells and subsets that are mobilized against fungi in various anatomical compartments; (2) fungal molecular patterns and their corresponding receptors that signal responses and shape the differentiation of T-cell subsets and B cells; and, ultimately (3) the effector and regulatory mechanisms that eliminate these invaders while constraining collateral damage to vital tissue. These insights create a foundation for the development of new, immune-based strategies for prevention or enhanced clearance of systemic fungal diseases.

Cytokine milieu in renal cavities of immunocompetent mice in response to intravenous challenge of Aspergillus flavus leading to aspergillosis

Investigations in mice have demonstrated that Aspergillus flavus is more virulent than all other Aspergillus species except A. tamari. However, there is a complete lack of information on the immune responses elicited by A. flavus in systemic model. This communication reports the progression of infection and cytokine profile in BALB/c mice in response to intravenous challenge of A. flavus. The pathogenesis of infection was evaluated morphologically and by the analysis of Colony Forming Units (CFUs) in kidney homogenates. The kinetics of regulated cytokines was determined in kidneys by cytokine-specific murine ELISA. During the initial phase of infection the rate of clearance of A. flavus was high, most likely through recruited neutrophils and the resident renal macrophages with concurrent significant release of pro-inflammatory cytokines (IFN-γ, TNF-α, IL-12/IL-23p40, IL-6) indicating antifungal innate immune response to be active at the site. However, at 24h PI there was a significant rise of IL-17 and IL-23 suggesting the activation of IL-17/IL-23 axis of inflammation resulting in rise of CFU. The lack of significant induction in the anti-inflammatory cytokines like IL-4 and IL-10 confirmed the absence of Th2 type of response. In the late phase, after 3days post-infection, there was a rise in the number of pathogen in the kidneys as determined by histopathology and CFU counts. The A. flavus hyphae were evident in the renal pelvis and ureter and we propose the production of blastoconidia by metamorphosed hyphae.

Invasive aspergillosis in a renal transplant recipient successfully treated with interferon-gamma

Invasive aspergillosis is a serious complication of solid organ transplantation. An early diagnosis is hampered by the lack of reliable serum markers and, even if appropriately diagnosed and treated with current antifungal agents, has a high mortality rate. We report a case of invasive pulmonary and cerebral aspergillosis in a renal transplant patient treated with IFN-γ in conjunction with combination anti-fungal therapy for six weeks in whom complete resolution of the fungal infection was achieved. Renal function remained intact throughout the treatment period. Surveillance CT scans of the chest and head showed resolution of prior disease but revealed a new left upper lobe mass four months after completion of treatment with IFN-γ. Biopsy of the lesion was positive for primary lung adenocarcinoma, for which she underwent left upper lobe resection. The pathology report confirmed clear surgical margins and lymph nodes and no evidence of fungal hyphae. IFN-γ should be considered early in the management of invasive aspergillosis in renal transplant patients. To date, allograft rejection has not been encountered.

Host immune defense against Aspergillus fumigatus: insight from experimental systemic (disseminated) infection

Model of systemic Aspergillus fumigatus infection induced by intravenous application of conidia is suitable for studying important aspects of invasive aspergillosis including relationship between infection and mortality, dissemination of infection and immune mechanisms involved in host resistance to this fungus. Use of this model allows the investigation of both innate and adaptive immune response characteristics in resistant/susceptible host, and investigating the contribution of genetic background and cytokine gene deficiency improves the knowledge of the diversity of mechanisms of immune response to Aspergillus infection. Studying of various aspects of systemic aspergillosis contributes to development of antifungal drugs.

Immunotherapy against invasive mold infections

Invasive infections due to filamentous fungi, such as Aspergillus spp., Zygomycetes, Scedosporium and Fusarium spp., cause significant morbidity and mortality in immunocompromised patients with hematological malignancies, recipients of hematopoietic stem cell transplants and those with chronic granulomatous disease. Despite antifungal therapy, the outcome is often unfavorable in these patients; immune restoration is considered as the cornerstone of successful treatment. Important aspects of human immune response against fungi include effective innate immune response expressed as effective phagocytic functions and a balance between proinflammatory and regulatory adaptive immune responses. A number of immunomodulatory approaches, including the administration of enhancing cytokines, adoptive transfer of pathogen-specific T lymphocytes and granulocyte transfusions have been investigated as adjunctive treatments against serious mold infections. Despite encouraging in vitro and in vivo data, current clinical evidence is not sufficient to allow firm recommendations on the use of these immunomodulatory modalities in serious mold infections.

Cytokines and the regulation of fungus-specific CD4 T cell differentiation

CD4 T cells play important and non-redundant roles in protection against infection with diverse fungi. Distinct CD4 T cell subsets can mediate protection against fungal disease where Th1 and Th17 CD4 T cell subsets have been found to promote fungal clearance and protective immunity against diverse fungal pathogens. The differentiation of naïve CD4 T cells into Th1 or Th17 cells is crucially controlled by their interaction with dendritic cells and instructed by cytokines. IL-12 and IFN-γ promote Th1 differentiation while TGF-β, IL-6, IL-1, IL-21 and IL-23 promote Th17 differentiation and maintenance. The production of these cytokines by DCs is in turn regulated by innate receptors triggered in response to fungal infection. In this review we will discuss the contributions of cytokines found to influence fungus-specific CD4 T cell differentiation and their role in defense against fungal disease. We will also highlight the contributions of innate receptors involved in recognition of fungi and how they shape cytokine secretion and CD4 T cell differentiation.

Pulmonary aspergillosis: a clinical review

Aspergillus is a mould which may lead to a variety of infectious, allergic diseases depending on the host's immune status or pulmonary structure. Invasive pulmonary aspergillosis occurs primarily in patients with severe immunodeficiency. The significance of this infection has dramatically increased with growing numbers of patients with impaired immune state associated with the management of malignancy, organ transplantation, autoimmune and inflammatory conditions; critically ill patients and those with chronic obstructive pulmonary disease appear to be at an increased risk. The introduction of new noninvasive tests, combined with more effective and better-tolerated antifungal agents, has resulted in lower mortality rates associated with this infection. Chronic necrotising aspergillosis is a locally invasive disease described in patients with chronic lung disease or mild immunodeficiency. Aspergilloma is usually found in patients with previously formed cavities in the lung, whereas allergic bronchopulmonary aspergillosis, a hypersensitivity reaction to Aspergillus antigens, is generally seen in patients with atopy, asthma or cystic fibrosis. This review provides an update on the evolving epidemiology and risk factors of the major manifestations of Aspergillus lung disease and the clinical manifestations that should prompt the clinician to consider these conditions. Current approaches for the diagnosis and management of these syndromes are discussed.

Human NK cells display important antifungal activity against Aspergillus fumigatus, which is directly mediated by IFN-γ release

Despite the strong interest in the NK cell-mediated immunity toward malignant cells and viruses, there is a relative lack of data on the interplay between NK cells and filamentous fungi, especially Aspergillus fumigatus, which is the major cause of invasive aspergillosis. By studying the in vitro interaction between human NK cells and A. fumigatus, we found only germinated morphologies to be highly immunogenic, able to induce a Th1-like response, and capable of upregulating cytokines such as IFN-γ and TNF-α. Moreover, priming NK cells with human rIL-2 and stimulating NK cells by direct NK cell-pathogen contact were essential to induce damage against A. fumigatus. However, the most interesting finding was that NK cells did not mediate anti-Aspergillus cytotoxicity through degranulation of their cytotoxic proteins (perforin, granzymes, granulysine), but via an alternative mechanism involving soluble factor(s). To our knowledge, our study is the first to demonstrate that IFN-γ, released by NK cells, directly damages A. fumigatus, attributing new properties to both human NK cells and IFN-γ and suggesting them as possible therapeutic tools against IA.