Invasive aspergillosis in primary immunodeficiencies

NT, C. SF, Khatod Y, Jain V, Kumar D, Yadav T. Aspergillus terreus pulmonary infection in a patient with late-onset combined immunodeficiency: a case report with literature review

Common variable immunodeficiency (CVID) is the most common humoral immune deficiency in adults, characterized by recurrent sinopulmonary bacterial infections. Invasive fungal infections are rarely associated with CVID. Late-onset combined immunodeficiency (LOCID) is a recently recognized variant of CVID with low CD4 counts and immunoglobulins deficiency. The current study reveals the first documented case of invasive pulmonary aspergillosis (Aspergillus terreus) in a patient with LOCID. A 52-year-old female with a recurrent history of sinopulmonary infections presented with acute onset fever and shortness of breath. Blood culture and bronchoalveolar lavage culture grew A. terreus. Further evaluation revealed low immunoglobulins (IgG, IgM and IgA). Moreover, she also had low CD4 counts (<200 cells/µL). The patient was successfully treated with voriconazole and immunoglobulin therapy. Finally, the study discusses LOCID as a potential risk factor for invasive fungal infections, which can be easily overlooked and cause poor outcomes.

The Challenge of Diagnosing Invasive Pulmonary Aspergillosis in Children: A Review of Existing and Emerging Tools

Invasive pulmonary aspergillosis remains a major cause of morbidity and mortality for immunocompromised children, particularly for patients with acute leukaemia and those undergoing haematopoietic stem cell transplantation. Timely diagnosis, using a combination of computed tomography (CT) imaging and microbiological testing, is key to improve prognosis, yet there are inherent challenges in this process. For CT imaging, changes in children are generally less specific than those reported in adults and recent data are limited. Respiratory sampling by either bronchoalveolar lavage or lung biopsy is recommended but is not always feasible in children, and serum biomarkers, including galactomannan, have important limitations. In this review we summarise the current paediatric data on available diagnostic tests for IPA and highlight key emerging diagnostic modalities with potential for future use.

Atypical imaging patterns during lung invasive mould diseases: lessons for clinicians

Imaging of pulmonary invasive mould diseases (IMDs), which represents a cornerstone in their work-up, is mainly based on computed tomography (CT). The purpose of this review is to discuss their CT features, mainly those related to aspergillosis and mucormycosis. We will especially focus on atypical radiological presentations that are increasingly observed among non-neutropenic emerging populations of patients at risk, such as those receiving novel anticancer therapies or those in the intensive care unit. We will also discuss the interest of other available imaging techniques, mainly positron emission tomography/CT, that may play a role in the diagnosis as well as evaluation of disease extent and follow-up. We will show that any new airway-centred abnormality or caveated lesion should evoke IMDs in mildly immunocompromised hosts. Limitations in their recognition may be due to potential underlying abnormalities that increase the complexity of interpretation of lung imaging, as well as the non-specificity of imaging features. In this way, the differentials of all morphological/metabolic aspects must be kept in mind for the optimal management of patients, as well as the benefit of evaluation of the vascular status.

A host defense peptide mimetic, brilacidin, potentiates caspofungin antifungal activity against human pathogenic fungi

Fungal infections cause more than 1.5 million deaths a year. Due to emerging antifungal drug resistance, novel strategies are urgently needed to combat life-threatening fungal diseases. Here, we identify the host defense peptide mimetic, brilacidin (BRI) as a synergizer with caspofungin (CAS) against CAS-sensitive and CAS-resistant isolates of Aspergillus fumigatus, Candida albicans, C. auris, and CAS-intrinsically resistant Cryptococcus neoformans. BRI also potentiates azoles against A. fumigatus and several Mucorales fungi. BRI acts in A. fumigatus by affecting cell wall integrity pathway and cell membrane potential. BRI combined with CAS significantly clears A. fumigatus lung infection in an immunosuppressed murine model of invasive pulmonary aspergillosis. BRI alone also decreases A. fumigatus fungal burden and ablates disease development in a murine model of fungal keratitis. Our results indicate that combinations of BRI and antifungal drugs in clinical use are likely to improve the treatment outcome of aspergillosis and other fungal infections.

A B1a-natural IgG-neutrophil axis is impaired in viral- and steroid-associated aspergillosis

The lung naturally resists Aspergillus fumigatus (Af) in healthy individuals, but multiple conditions can disrupt this resistance, leading to lethal invasive infections. Core processes of natural resistance and its breakdown are undefined. We investigated three distinct conditions predisposing to lethal aspergillosis-severe SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection, influenza A viral pneumonia, and systemic corticosteroid use-in human patients and murine models. We found a conserved and essential coupling of innate B1a lymphocytes, Af-binding natural immunoglobulin G antibodies, and lung neutrophils. Failure of this axis concealed Af from neutrophils, allowing rapid fungal invasion and disease. Reconstituting the axis with immunoglobulin therapy reestablished resistance, thus representing a realistic pathway to repurpose currently available therapies. Together, we report a vital host resistance pathway that is responsible for protecting against life-threatening aspergillosis in the context of distinct susceptibilities.

Invasive Aspergillosis in the Intensive Care Unit

Invasive pulmonary aspergillosis (IPA) is a serious condition resulting in significant mortality and morbidity among patients in intensive care units (ICUs). There is a growing number of at-risk patients for this condition with the increasing use of immunosuppressive therapies. The diagnosis of IPA can be difficult in ICUs, and relies on integration of clinical, radiological, and microbiological features. In this review, we discuss patient populations at risk for IPA, as well as the diagnostic criteria employed. We review the fungal biomarkers used, as well as the challenges in distinguishing colonization with Aspergillus from invasive disease. We also address the growing concern of multidrug-resistant Aspergillosis and review the new and novel therapeutics which are in development to combat this.

Chronic cavitary pulmonary aspergillosis in an immunocompetent child

Chronic pulmonary aspergillosis (CPA) is a progressive and destructive disease of the lung parenchyma. We report a 9-year-old boy diagnosed with CPA with a positive Aspergillus IgG and chest imaging of cavitary lung lesions. He was treated with oral Itraconazole with significant improvement. This shows that an index of suspicion should be heightened in the paediatric population with cavitary lung lesions because not all cavitary lung lesions are caused by Mycobacterium tuberculosis.

Fatal invasive aspergillosis in a child with chronic granulomatous disease

Patients with chronic granulomatous disease, a primary immunodeficiency, experience granulomatous complications and recurrent life-threatening opportunistic bacterial and fungal infections. In this article, we report on a case of invasive aspergillosis in an eight-year-old boy with chronic granulomatous disease, who presented with pleural effusion and pneumonia, cerebral venous sinus thrombosis, and unusual skin lesions caused by Aspergillus fumigatus. Antifungal treatment with itraconazole and other antifungal agents, along with interferon-γ, was ineffective and the patient eventually died from cerebral venous sinus thrombosis, and intracerebral haemorrhage following increased intracranial pressure after one month. The diagnosis of invasive aspergillosis should be considered early in children presenting with invasive fungal infections, particularly those involving the central nervous system.

Acute respiratory failure due to Aspergillus niger infection with acute fibrinous and organazing pneumonia: A case report

A 59-year-old woman complaining of wet cough, hemoptysis, slight fever, anorexia, and malaise was admitted to hospital with suspected lobar pneumonia. She received treatment for myocardial infarction and deep venous thrombosis caused by familial protein C deficiency. Rapid deterioration due to respiratory failure occurred despite intensive care with broad-spectrum antibiotics. At a later date, sputum examination revealed the presence of Aspergillus niger. Based on clinical and autopsy findings, she was diagnosed with acute respiratory failure due to pulmonary aspergillosis with acute fibrinous and organizing pneumonia. This is the first reported case of pulmonary aspergillosis with acute fibrinous and organizing pneumonia complicated by calcium oxalate resulting from Aspergillus niger infection, leading to severe inflammation and tissue injury in the lungs.

The OxrA Protein of Aspergillus fumigatus Is Required for the Oxidative Stress Response and Fungal Pathogenesis

An efficient reactive oxygen species (ROS) detoxification system is vital for the survival of the pathogenic fungus Aspergillus fumigatus within the host high-ROS environment of the host. Therefore, identifying and targeting factors essential for oxidative stress response is one approach to developing novel treatments for fungal infections. The oxidation resistance 1 (Oxr1) protein is essential for protection against oxidative stress in mammals, but its functions in pathogenic fungi remain unknown. The present study aimed to characterize the role of an Oxr1 homolog in A. fumigatus. The results indicated that the OxrA protein plays an important role in oxidative stress resistance by regulating the catalase function in A. fumigatus, and overexpression of catalase can rescue the phenotype associated with OxrA deficiency. Importantly, the deficiency of oxrA decreased the virulence of A. fumigatus and altered the host immune response. Using the Aspergillus-induced lung infection model, we demonstrated that the ΔoxrA mutant strain induced less tissue damage along with decreased levels of lactate dehydrogenase (LDH) and albumin release. Additionally, the ΔoxrA mutant caused inflammation at a lower degree, along with a markedly reduced influx of neutrophils to the lungs and a decreased secretion of cytokine usually associated with recruitment of neutrophils in mice. These results characterize the role of OxrA in A. fumigatus as a core regulator of oxidative stress resistance and fungal pathogenesis. IMPORTANCE Knowledge of ROS detoxification in fungal pathogens is useful in the design of new antifungal drugs and could aid in the study of oxidative stress resistance mechanisms. In this study, we demonstrate that OxrA protein localizes to the mitochondria and functions to protect against oxidative damage. We demonstrate that OxrA contributes to oxidative stress resistance by regulating catalase function, and overexpression of catalase (CatA or CatB) can rescue the phenotype that is associated with OxrA deficiency. Remarkably, a loss of OxrA attenuated the fungal virulence in a mouse model of invasive pulmonary aspergillosis and altered the host immune response. Therefore, our finding indicates that inhibition of OxrA might be an effective approach for alleviating A. fumigatus infection. The present study is, to the best of our knowledge, a pioneer in reporting the vital role of Oxr1 protein in pathogenic fungi.

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.

Screening of Chemical Libraries for New Antifungal Drugs against Aspergillus fumigatus Reveals Sphingolipids Are Involved in the Mechanism of Action of Miltefosine

Aspergillus fumigatus is an important fungal pathogen and the main etiological agent of aspergillosis, a disease characterized by a noninvasive process that can evolve to a more severe clinical manifestation, called invasive pulmonary aspergillosis (IPA), in immunocompromised patients. The antifungal arsenal to threat aspergillosis is very restricted. Azoles are the main therapeutic approach to control IPA, but the emergence of azole-resistant A. fumigatus isolates has significantly increased over recent decades. Therefore, new strategies are necessary to combat aspergillosis, and drug repurposing has emerged as an efficient and alternative approach for identifying new antifungal drugs. Here, we used a screening approach to analyze A. fumigatus in vitro susceptibility to 1,127 compounds. A. fumigatus was susceptible to 10 compounds, including miltefosine, a drug that displayed fungicidal activity against A. fumigatus. By screening an A. fumigatus transcription factor null library, we identified a single mutant, which has the smiA (sensitive to miltefosine) gene deleted, conferring a phenotype of susceptibility to miltefosine. The transcriptional profiling (RNA-seq) of the wild-type and ΔsmiA strains and chromatin immunoprecipitation coupled to next-generation sequencing (ChIP-Seq) of an SmiA-tagged strain exposed to miltefosine revealed genes of the sphingolipid pathway that are directly or indirectly regulated by SmiA. Sphingolipid analysis demonstrated that the mutant has overall decreased levels of sphingolipids when growing in the presence of miltefosine. The identification of SmiA represents the first genetic element described and characterized that plays a direct role in miltefosine response in fungi. IMPORTANCE The filamentous fungus Aspergillus fumigatus causes a group of diseases named aspergillosis, and their development occurs after the inhalation of conidia dispersed in the environment. Very few classes of antifungal drugs are available for aspergillosis treatment, e.g., azoles, but the emergence of global resistance to azoles in A. fumigatus clinical isolates has increased over recent decades. Repositioning or repurposing drugs already available on the market is an interesting and faster opportunity for the identification of novel antifungal agents. By using a repurposing strategy, we identified 10 different compounds that impact A. fumigatus survival. One of these compounds, miltefosine, demonstrated fungicidal activity against A. fumigatus. The mechanism of action of miltefosine is unknown, and, aiming to get more insights about it, we identified a transcription factor, SmiA (sensitive to miltefosine), important for miltefosine resistance. Our results suggest that miltefosine displays antifungal activity against A. fumigatus, interfering in sphingolipid biosynthesis.

Challenges and Opportunities in Understanding Genetics of Fungal Diseases: Towards a Functional Genomics Approach

Infectious diseases are a leading cause of morbidity and mortality worldwide, and human pathogens have long been recognized as one of the main sources of evolutionary pressure, resulting in a high variable genetic background in immune-related genes. The study of the genetic contribution to infectious diseases has undergone tremendous advances over the last decades. Here, focusing on genetic predisposition to fungal diseases, we provide an overview of the available approaches for studying human genetic susceptibility to infections, reviewing current methodological and practical limitations. We describe how the classical methods available, such as family-based studies and candidate gene studies, have contributed to the discovery of crucial susceptibility factors for fungal infections. We will also discuss the contribution of novel unbiased approaches to the field, highlighting their success but also their limitations for the fungal immunology field. Finally, we show how a systems genomics approach can overcome those limitations and can lead to efficient prioritization and identification of genes and pathways with a critical role in susceptibility to fungal diseases. This knowledge will help to stratify at-risk patient groups and, subsequently, develop early appropriate prophylactic and treatment strategies.

A rare infective cause of stroke in an immunocompetent child

BACKGROUND

Infections are a common cause of childhood stroke with variable presentation. The current case describes a rare infective cause of venous and arterial stroke in an immunocompetent girl with management implications.

CASE DESCRIPTION

A 12 year old girl, presented with history of fever for 10 days, painful swelling of right eye for 7 days and altered sensorium for 2 days. On examination, she had right eye orbital cellulitis and fullness of right paranasal area. On nervous system examination, she was delirious, had right eye ophthalmoparesis, left upper motor neuron facial palsy and signs of meningeal inflammation. Her contrast enhanced CT head and subsequent MRI brain with arteriography and venography revealed right cavernous sinus and distal internal carotid artery thrombosis. She was started on intravenous ceftriaxone and vancomycin and subcutaneous heparin. In view of persistent symptoms, endoscopic debridement of right nasal cavity was done, which showed growth of aspergillus flavus. Subsequently, she was started on intravenous voriconazole. Within a week, she was afebrile, her inflammatory and neurological signs started improving. She was discharged after 3 weeks of intravenous voriconazole which was continued for 3 more weeks orally. Her procoagulant and immunodeficiency work up were normal. At 4 months follow up, she showed both clinical and radiological resolution.

CONCLUSIONS

Despite high mortality described in sino-orbital aspergillosis, early and appropriate treatment led to optimal outcome. In deep seated infections, isolation of etiological organism should be attempted, particularly when patient doesn't respond to conventional antimicrobial therapy.

BCGitis as the primary manifestation of chronic granulomatous disease

Patients with primary immunodeficiency disease (PID) are not only vulnerable to mycobacterial disease, but are also more likely to develop adverse events following BCG vaccination. These events can range from regional disease (BCGitis) to disseminated disease (BCGosis). Chronic granulomatous disease (CGD), which is characterized by impaired leukocyte phagocytic function, is one of the many inherited PIDs that increase the body's susceptibility to recurrent bacterial and fungal infections. Here, we report a 6-year-old boy with no significant past medical history who presented with progressive lymphadenopathy six years after BCG vaccination. He was later diagnosed with CGD on further evaluation.

The first rare and fatal case of invasive aspergillosis of spinal cord due to Aspergillus nidulans in an Iranian child with chronic granulomatosis disease: review of literature

Background and Purpose:

Invasive aspergillosis (IA) of the central nervous system (CNS) is a devastating complication which is rarely reported in immunocompromised children.

In this case presentation, we reported a rare and fatal IA with spinal cord involvement in a 10-year-old child with X-linked chronic granulomatosis disease (CGD).

Case report:

The child had a previous history of pulmonary tuberculosis. A cervical spine X-ray revealed the involvement of cervical vertebrae (T4/T5) and ribs causing spinal cord compression and epidural abscess. The patient underwent a decompressive laminectomy and mass removal. The histopathology and culture results suggested IA. Despite the aggressive and prolonged therapy, he died within one year. Aspergillus nidulans was identified as the causative agent based on morphological and molecular studies.

Conclusion:

This synopsis represents the aggressive behavior of infection caused by A. nidulans in the CGD patient.

Humoral immunodeficiencies: conferred risk of infections and benefits of immunoglobulin replacement therapy

Primary immunodeficiency (PID) diseases result from genetic defects of the immune system that increase a patient's susceptibility to infections. The types of infections that occur in patients with PID diseases are dictated largely by the nature of the immunodeficiency, which can be defined by dysfunction of cellular or humoral defenses. An increasing number of PID diseases, including those with both cellular and humoral defects, have antibody deficiency as a major feature, and as a result can benefit from immunoglobulin replacement therapy. In fact, the most common PID diseases worldwide are antibody deficiencies and include common variable immunodeficiency, congenital agammaglobulinemia, hyper‐IgM syndrome, specific antibody deficiency, and Good syndrome. Although immunoglobulin replacement therapy is the cornerstone of treatment for the majority of these conditions, a thorough understanding of the specific infections for which these patients are at increased risk can hasten diagnosis and guide additional therapies. Moreover, the infection trends in some patients with PID disease who have profound defects of cellular immunity, such as autosomal‐dominant hyper‐IgE syndrome (Job/Buckley syndrome) or dedicator of cytokinesis 8 (DOCK8) deficiency, suggest that select patients might benefit from immunoglobulin replacement therapy even if their immunodeficiency is not limited to antibody defects. In this review, we provide an overview of the predisposition to infections seen in PID disease that may benefit from immunoglobulin replacement therapy.

Exogenous Stimulation of Type I Interferon Protects Mice with Chronic Granulomatous Disease from Aspergillosis through Early Recruitment of Host-Protective Neutrophils into the Lung

Invasive aspergillosis (IA) remains the primary cause of morbidity and mortality in chronic granulomatous disease (CGD) patients, often due to infection by Aspergillus species refractory to antifungals. This motivates the search for alternative treatments, including immunotherapy. We investigated the effect of exogenous type I interferon (IFN) activation on the outcome of IA caused by three Aspergillus species, A. fumigatus, A. nidulans, and A. tanneri, in CGD mice. The animals were treated with poly(I):poly(C) carboxymethyl cellulose poly-l-lysine (PICLC), a mimetic of double-stranded RNA, 24 h preinfection and postinfection. The survival rates and lung fungal burdens were markedly improved by PICLC immunotherapy in animals infected with any one of the three Aspergillus species. While protection from IA was remarkable, PICLC induction of type I IFN in the lungs surged 24 h posttreatment and returned to baseline levels by 48 h, suggesting that PICLC altered early events in protection against IA. Immunophenotyping of recruited leukocytes and histopathological examination of tissue sections showed that PICLC induced similar cellular infiltrates as those in untreated-infected mice, in both cases dominated by monocytic cells and neutrophils. However, the PICLC immunotherapy resulted in a marked earlier recruitment of the leukocytes. Unlike with conidia, infection with A. nidulans germlings reduced the protective effect of PICLC immunotherapy. Additionally, antibody depletion of neutrophils totally reversed the protection, suggesting that neutrophils are crucial for PICLC-mediated protection. Together, these data show that prophylactic PICLC immunotherapy prerecruits these cells, enabling them to attack the conidia and thus resulting in a profound protection from IA.IMPORTANCE Patients with chronic granulomatous disease (CGD) are highly susceptible to invasive aspergillosis (IA). While Aspergillus fumigatus is the most-studied Aspergillus species, CGD patients often suffer IA caused by A. nidulans, A. tanneri, and other rare species. These non-fumigatus Aspergillus species are more resistant to antifungal drugs and cause higher fatality rates than A. fumigatus Therefore, alternative therapies are needed to protect CGD patients. We report an effective immunotherapy of mice infected with three Aspergillus species via PICLC dosing. While protection from IA was long lasting, PICLC induction of type I IFN surged but quickly returned to baseline levels, suggesting that PICLC was altering early events in IA. Interestingly, we found responding immune cells to be similar between PICLC-treated and untreated-infected mice. However, PICLC immunotherapy resulted in an earlier recruitment of the leukocytes and suppressed fungal growth. This study highlights the value of type I IFN induction in CGD patients.

Triazole Resistance Is Still Not Emerging in Aspergillus fumigatus Isolates Causing Invasive Aspergillosis in Brazilian Patients

Aspergillus fumigatus azole resistance has emerged as a global health problem. We evaluated the in vitro antifungal susceptibility of 221 clinical A. fumigatus isolates according to CLSI guidelines. Sixty-one isolates exhibiting MICs at the epidemiological cutoff value (ECV) for itraconazole or above the ECV for any triazole were checked for CYP51A mutations. No mutations were documented, even for the isolates (1.8%) with high voriconazole MICs, indicating that triazoles may be used safely to treat aspergillosis in Brazil.

Triazole Resistance in Aspergillus Species: An Emerging Problem

Aspergillus species are ubiquitous fungal saprophytes found in diverse ecological niches worldwide. Among them, Aspergillus fumigatus is the most prevalent and is largely responsible for the increased incidence of invasive aspergillosis with high mortality rates in some immunocompromised hosts. Azoles are the first-line drugs in treating diseases caused by Aspergillus spp. However, increasing reports in A. fumigatus azole resistance, both in the clinical setting and in the environment, are threatening the effectiveness of clinical and agricultural azole drugs. The azole target is the 14-α sterol demethylase encoded by cyp51A gene and the main mechanisms of resistance involve the integration of tandem repeats in its promoter and/or single point mutations in this gene. In A. fumigatus, azole resistance can emerge in two different scenarios: a medical route in which azole resistance is generated during long periods of azole treatment in the clinical setting and a route of resistance derived from environmental origin due to extended use of demethylation inhibitors in agriculture. The understanding of A. fumigatus azole resistance development and its evolution is needed in order to prevent or minimize its impact. In this article, we review the current situation of azole resistance epidemiology and the predominant molecular mechanisms described based on the resistance acquisition routes. In addition, the clinical implications of A. fumigatus azole resistance and future research are discussed.

Aspergillus fumigatus virulence through the lens of transcription factors

Invasive aspergillosis (IA), most commonly caused by the filamentous fungus Aspergillus fumigatus, occurs in immune compromised individuals. The ability of A. fumigatus to proliferate in a multitude of environments is hypothesized to contribute to its pathogenicity and virulence. Transcription factors (TF) have long been recognized as critical proteins for fungal pathogenicity, as many are known to play important roles in the transcriptional regulation of pathways implicated in virulence. Such pathways include regulation of conidiation and development, adhesion, nutrient acquisition, adaptation to environmental stress, and interactions with the host immune system among others. In both murine and insect models of IA, TF loss of function in A. fumigatus results in cases of hyper- and hypovirulence as determined through host survival, fungal burden, and immune response analyses. Consequently, the study of specific TFs in A. fumigatus has revealed important insights into mechanisms of pathogenicity and virulence. Although in vitro studies have identified virulence-related functions of specific TFs, the full picture of their in vivo functions remain largely enigmatic and an exciting area of current research. Moreover, the vast majority of TFs remain to be characterized and studied in this important human pathogen. Here in this mini-review we provide an overview of selected TFs in A. fumigatus and their contribution to our understanding of this important human pathogen's pathogenicity and virulence.

Hemoptysis in a Patient with Elevated Immunoglobulin E

Recurrent pneumonia with cavitation leading to pneumatoceles, secondary fungal infections, and hemoptysis are major causes of mortality and morbidity in patients with hyper-IgE syndrome. Prevention and aggressive treatment of pneumonia in these patients are essential to prevent further lung damage, but treatment may be delayed because the classic signs/symptoms of infection such as fever, chills, or rigors may be lacking. Early imaging to identify infection is essential for diagnosis and treatment. The mainstay of therapy is continuous, full-dose daily trimethoprim-sulfamethoxazole and commonly fungal coverage. Because hyper-IgE syndrome is a progressive disease, patients' condition may worsen despite compliance with prophylactic therapy.

Pulmonary manifestations of primary immunodeficiency disorders in children

Primary immunodeficiencies (PIDs) are inherited disorders in which one or several components of immune system are decreased, missing, or of non-appropriate function. These diseases affect the development, function, or morphology of the immune system. The group of PID comprises more than 200 different disorders and syndromes and the number of newly recognized and revealed deficiencies is still increasing. Their clinical presentation and complications depend on the type of defects and there is a great variability in the relationship between genotypes and phenotypes. A variation of clinical presentation across various age categories is also presented and children could widely differ from adult patients with PID. Respiratory symptoms and complications present a significant cause of morbidity and also mortality among patients suffering from different forms of PIDs and they are observed both in children and adults. They can affect primarily either upper airways (e.g., sinusitis and otitis media) or lower respiratory tract [e.g., pneumonia, bronchitis, bronchiectasis, and interstitial lung diseases (ILDs)]. The complications from lower respiratory tract are usually considered to be more important and also more specific for PIDs and they determinate patients' prognosis. The spectrum of the causal pathogens usually demonstrates typical pattern characteristic for each PID category. The respiratory signs of PIDs can be divided into infectious (upper and lower respiratory tract infections and complications) and non-infectious (ILDs, bronchial abnormalities - especially bronchiectasis, malignancies, and benign lymphoproliferation). Early diagnosis and appropriate therapy can prevent or at least slow down the development and course of respiratory complications of PIDs.

Pulmonary manifestations of chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited disorder, characterized by defects in superoxide-generating NADPH oxidase of phagocytes. The genetic defects in CGD induce failure to activate the respiratory burst in the phagocytes, leading to severe recurrent infections and unexplained prolonged inflammatory reactions that may produce granulomatous lesions. A noble advance in curative therapy for CGD is hematopoietic stem cell transplantation. Since the most common site of involvement in CGD is the lung, the pulmonologists (pediatrics or adult) may be among the first to recognize the pattern of infection, inflammation and granuloma formation, leading to diagnosis of CGD. Pulmonologists need to be aware of different lung manifestations of CGD.

Invasive fungal infections in patients with chronic granulomatous disease

Invasive fungal infections are a major threat for chronic granulomatous disease (CGD) patients. The present study provides a comprehensive overview of published invasive fungal infections in the CGD host through an extensive review of epidemiological, clinical, diagnostic and therapeutic data. In addition to the often mild clinical presentation, the currently used diagnostics for invasive aspergillosis have low sensitivity in CGD patients and cannot be easily translated to this non-neutropenic host. Aspergillus fumigatus and A. nidulans are the most commonly isolated species. A. nidulans infections are seldom reported in other immunocompromised patients, indicating a unique interaction between this fungus and the CGD host. The occurrence of mucormycosis is mainly noted in the setting of treatment of inflammatory complications with immunosuppressive drugs. Candida infections are infrequently seen and do not cause mucocutaneous disease but do show an age-dependent clinical presentation. The CGD patient is susceptible to a wide range of fungal pathogens, indicating the need to determine the causative fungus, often by invasive diagnostics, to guide optimal and rational treatment. This review summarizes current understanding of invasive fungal infections in patients with CGD and will serve as a starting point to guide optimal treatment strategies and to direct further research aimed at improving outcomes.

Bacillus Calmette-Guérin (BCG) complications associated with primary immunodeficiency diseases

Primary immunodeficiency diseases (PIDs) are a group of inherited disorders, characterized by defects of the immune system predisposing individuals to variety of manifestations, including recurrent infections and unusual vaccine complications. There are a number of PIDs prone to Bacillus Calmette-Guérin (BCG) complications. This review presents an update on our understanding about the BCGosis-susceptible PIDs, including severe combined immunodeficiency, chronic granulomatous disease, and Mendelian susceptibility to mycobacterial diseases.

Phagocyte responses towards Aspergillus fumigatus

The saprophytic fungus Aspergillus fumigatus is a mold which is ubiquitously present in the environment. It produces large numbers of spores, called conidia that we constantly inhale with the breathing air. Healthy individuals normally do not suffer from true fungal infections with this pathogen. A normally robust resistance against Aspergillus is based on the presence of a very effective immunological defense system in the vertebrate body. Inhaled conidia are first encountered by lung-resident alveolar macrophages and then by neutrophil granulocytes. Both cell types are able to effectively ingest and destroy the fungus. Although some responses of the adaptive immune system develop, the key protection is mediated by innate immunity. The importance of phagocytes for defense against aspergillosis is also supported by large numbers of animal studies. Despite the production of aggressive chemicals that can extracellularly destroy fungal pathogens, the main effector mechanism of the innate immune system is phagocytosis. Very recently, the production of extracellular neutrophil extracellular traps (NETs) consisting of nuclear DNA has been added to the armamentarium that innate immune cells use against infection with Aspergillus. Phagocyte responses to Aspergillus are very broad, and a number of new observations have added to this complexity in recent years. To summarize established and newer findings, we will give an overview on current knowledge of the phagocyte system for the protection against Aspergillus.

Epidemiology and outcome of invasive fungal diseases in patients with chronic granulomatous disease: a multicenter study in France

BACKGROUND

Chronic granulomatous disease (CGD) is a rare inherited phagocytic disorder resulting in an increased susceptibility to infections including invasive fungal diseases (IFDs) and inflammatory complications. This study is aimed at assessing the incidence, prevalence, and outcome of IFDs among CGD patients followed in France.

METHODS

CGD patients were identified through the French national registry for primary immunodeficiencies (PID) held by the French national reference Centre of PID (Centre de Référence Déficits Immunitaires Héréditaires), which comprises a total of 3083 patients including 155 with CGD followed between 1976 and 2008. A questionnaire was filled out for each episode of IFD. Information retrieved included a description of the IFD using the 2008 European Organization for Research and Treatment of Cancer/Mycoses Study Group IFD definition criteria.

RESULTS

Of CGD patients, 42.6% (66/155) developed at least 1 episode of IFD. Overall incidence of IFD was 0.040/patient-years (1862 patient-years of total follow-up). IFD incidence was found to be significant while receiving itraconazole prophylaxis compared with no prophylaxis (0.027 vs. 0.053 IFD/patient-years; P < 0.01). Median age at IFD diagnosis was 6.5 years (3.3-11.3). The most common fungal genus was Aspergillus sp. accounting for 40% of all IFDs. Of the IFDs, 42.5% were proven, 30.0% probable, and 27.5% possible. Of all IFD episodes, 52.5% were treated by antifungal monotherapy, mostly by amphotericin B. Survival was reduced in IFD patients compared with those without it (log-rank 0.04).

CONCLUSIONS

IFDs are a frequent and life-threatening complication in CGD patients. Itraconazole significantly reduces its incidence and should be recommended in absence of better alternatives.

Aspergillus fumigatus stimulates the NLRP3 inflammasome through a pathway requiring ROS production and the Syk tyrosine kinase

Invasive aspergillosis (IA) is a life-threatening disease that occurs in immunodepressed patients when infected with Aspergillus fumigatus. This fungus is the second most-common causative agent of fungal disease after Candida albicans. Nevertheless, much remains to be learned about the mechanisms by which A. fulmigatus activates the innate immune system. We investigated the inflammatory response to conidia and hyphae of A. fumigatus and specifically, their capacity to trigger activation of an inflammasome. Our results show that in contrast to conidia, hyphal fragments induce NLRP3 inflammasome assembly, caspase-1 activation and IL-1β release from a human monocyte cell line. The ability of Aspergillus hyphae to activate the NLRP3 inflammasome in the monocytes requires K⁺ efflux and ROS production. In addition, our data show that NLRP3 inflammasome activation as well as pro-IL-1β expression relies on the Syk tyrosine kinase, which is downstream from the pathogen recognition receptor Dectin-1, reinforcing the importance of Dectin-1 in the innate immune response against fungal infection. Furthermore, we show that treatment of monocytes with corticosteroids inhibits transcription of the gene encoding IL-1β. Thus, our data demonstrate that the innate immune response against A. fumigatus infection involves a two step activation process, with a first signal promoting expression and synthesis of pro-IL-1β; and a second signal, involving Syk-induced activation of the NLRP3 inflammasome and caspase-1, allowing processing and secretion of the mature cytokine.

Aspergillus and the paediatric lung

Aspergillus spp produce a wide range of saprophytic and invasive syndromes in the lungs, including allergic bronchopulmonary aspergillosis (ABPA), aspergilloma and invasive pulmonary aspergillosis (IPA). ABPA results from hypersensitivity to the fungus, and mainly affects patients with asthma or cystic fibrosis (CF). The treatment of choice consists of systemic corticosteroids and itraconazole. Aspergilloma is managed by observation or surgery. IPA is predominantly seen in patients with haematological malignancies, chronic granulomatous disease or immunosuppressive treatment. With the use of aggressive therapies for end-stage CF, such as heart-lung transplantation, the potential for a patient to convert from colonization or ABPA to IPA has increased. Suggestive clinical and radiological findings, supplemented with mycological data using serology and molecular biology, have enhanced the capacity to diagnose IPA in paediatric patients. While voriconazole is considered the first-line therapy in IPA, several other antifungal agents may be appropriate alternatives.

Exogenous pentraxin 3 restores antifungal resistance and restrains inflammation in murine chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by life-threatening bacterial and fungal infections and hyperinflammation. The susceptibility to aspergillosis in experimental CGD (p47(phox-/-) mice) is associated with the failure to control the inherent inflammatory response to the fungus and to restrict the activation of inflammatory Th17 cells. We assessed whether pentraxin (PTX)3, a member of a family of multimeric pattern-recognition proteins with potent anti-Aspergillus activity, could limit pathogenic inflammation in p47(phox-/-) mice by curbing the IL-23/Th17 inflammatory axis in response to the fungus. We found that the production of PTX3 was delayed in CGD mice in infection but exogenous administration of PTX3 early in infection restored antifungal resistance and restrained the inflammatory response to the fungus. This occurred through down-regulation of IL-23 production by dendritic cells and epithelial cells which resulted in limited expansion of IL-23R+ gammadelta+ T cells producing IL-17A and the emergence of Th1/Treg responses with minimum pathology. Thus, PTX3 could be therapeutically used for the exploitation of NADPH-independent mechanism(s) of antifungal immune protection with limited immunopathology in CGD.

Antifungal activities of natural and synthetic iron chelators alone and in combination with azole and polyene antibiotics against Aspergillus fumigatus

Antifungal effects of iron chelators (lactoferrin, deferoxamine, deferiprone, and ciclopirox) were tested alone and in combination with antifungal drugs against Aspergillus fumigatus B5233 conidia. Lactoferrin, ciclopirox, and deferiprone inhibited whereas deferoxamine enhanced fungal growth. Antifungal synergy against conidia was observed for combinations of ketoconazole with ciclopirox or deferiprone, lactoferrin with amphotericin B, and fluconazole with deferiprone. Iron chelation alone or combined with antifungal drugs may be useful for prevention and treatment of mycosis.

Galactomannan antigenemia in pediatric oncology patients with invasive aspergillosis

BACKGROUND

Diagnosing invasive aspergillosis is difficult but might be improved by detection of circulating galactomannan. Although galactomannan antigenemia has been well studied in the detection of invasive aspergillosis in adult patients, little is known about the expression of circulating galactomannan in immunocompromised children with invasive aspergillosis.

METHODS

We studied the expression of galactomannan antigen by enzyme immunoassay (EIA) in 990 serum samples from 56 pediatric oncology patients (ages 3 months to 18 years) of whom 17 had proven or probable invasive aspergillosis defined by the European Organization for Research and Treatment of Cancer-Mycoses Study Group criteria. Any sample with a galactomannan EIA Galactomannan index value of > or = 0.5 was considered positive.

RESULTS

At least 1 serum sample was positive for 11 of 17 pediatric oncology patients (65.7% sensitivity, 95% confidence interval: 38.3-85.7) with invasive aspergillosis. Galactomannan EIA was positive in 99 of 304 samples from patients with proven or probable invasive aspergillosis, and 7 of 686 (1.0%) samples from 39 control subjects resulted in a positive galactomannan EIA result. At least 1 sample tested positive in 5 of the 39 controls (12.8%, 95% confidence interval: 4.3-27.4). No significant association between accuracy and patient age was observed. Among the 7 evaluable galactomannan-positive patients with IA, the galactomannan EIA produced a positive result before clinical or radiographic evidence of infection in 6 cases, with a lead-time to diagnosis ranging from 1 day to 34 days (median: 10 days). In the remaining case, a positive galactomannan was observed on the same day as diagnosis by non-EIA methods.

CONCLUSIONS

The presence of circulating galactomannan is predictive of invasive aspergillosis in most pediatric oncology patients. Galactomannan antigenemia may precede clinical, microbiologic, or radiographic evidence of invasive aspergillosis.

Immunomodulatory effects of voriconazole on monocytes challenged with Aspergillus fumigatus: differential role of Toll-like receptors

Voriconazole (VRC) has activity against Aspergillus fumigatus, the most frequent cause of invasive aspergillosis in immunocompromised patients. The combination of VRC and A. fumigatus hyphae induced a more pronounced profile of expression of genes encoding inflammatory molecules in human monocytes than Aspergillus alone did. Herein, we provide further evidence of the potential mechanism underlying this immunomodulatory effect of VRC on human monocytes in response to A. fumigatus hyphae. A significant additive antifungal effect was shown when VRC was combined with monocytes against A. fumigatus hyphae. Both A. fumigatus hyphae and VRC induced pronounced profiles of mRNA and protein expression of Toll-like receptor 2 (TLR2) as well as tumor necrosis factor alpha (TNF-alpha) in THP-1 monocytic cells compared to untreated cells. The VRC-induced increase was greater than that induced by hyphae. The combination of VRC and hyphae increased mRNA and protein expression of TLR2 and TNF-alpha to even higher levels than did either VRC or hyphae alone. In contrast, TLR4 expression, both at the mRNA and protein levels, was not increased by either VRC or hyphae or their combination. In addition, significantly more NF-kappaB was translocated to the nuclei of THP-1 cells treated with VRC than untreated cells. While VRC induced more NF-kappaB than hyphae did, treatment with the combination of the two factors induced the greatest NF-kappaB expression. The pronounced profile of TLR2 signaling, TNF-alpha expression, and NF-kappaB activation in the presence of VRC suggests an immunomodulatory effect leading to a more efficient response to A. fumigatus.

Genes differentially expressed in conidia and hyphae of Aspergillus fumigatus upon exposure to human neutrophils

BACKGROUND

Aspergillus fumigatus is the most common etiologic agent of invasive aspergillosis in immunocompromised patients. Several studies have addressed the mechanism involved in host defense but only few have investigated the pathogen's response to attack by the host cells. To our knowledge, this is the first study that investigates the genes differentially expressed in conidia vs hyphae of A. fumigatus in response to neutrophils from healthy donors as well as from those with chronic granulomatous disease (CGD) which are defective in the production of reactive oxygen species.

METHODOLOGY/PRINCIPAL FINDINGS

Transcriptional profiles of conidia and hyphae exposed to neutrophils, either from normal donors or from CGD patients, were obtained by using the genome-wide microarray. Upon exposure to either normal or CGD neutrophils, 244 genes were up-regulated in conidia but not in hyphae. Several of these genes are involved in the degradation of fatty acids, peroxisome function and the glyoxylate cycle which suggests that conidia exposed to neutrophils reprogram their metabolism to adjust to the host environment. In addition, the mRNA levels of four genes encoding proteins putatively involved in iron/copper assimilation were found to be higher in conidia and hyphae exposed to normal neutrophils compared to those exposed to CGD neutrophils. Deletants in several of the differentially expressed genes showed phenotypes related to the proposed functions, i.e. deletants of genes involved in fatty acid catabolism showed defective growth on fatty acids and the deletants of iron/copper assimilation showed higher sensitivity to the oxidative agent menadione. None of these deletants, however, showed reduced resistance to neutrophil attack.

CONCLUSION

This work reveals the complex response of the fungus to leukocytes, one of the major host factors involved in antifungal defense, and identifies fungal genes that may be involved in establishing or prolonging infections in humans.

Reduced nicotinamide adenine dinucleotide phosphate oxidase-independent resistance to Aspergillus fumigatus in alveolar macrophages

The fungal pathogen Aspergillus fumigatus is responsible for increasing numbers of fatal infections in immune-compromised humans. Alveolar macrophages (AM) are important in the innate defense against aspergillosis, but little is known about their molecular responses to fungal conidia in vivo. We examined transcriptional changes and superoxide release by AM from C57BL/6 and gp91(phox)(-/-) mice in response to conidia. Following introduction of conidia into the lung, microarray analysis of AM showed the transcripts most strongly up-regulated in vivo to encode chemokines and additional genes that play a critical role in neutrophil and monocyte recruitment, indicating that activation of phagocytes represents a critical early response of AM to fungal conidia. Of the 73 AM genes showing > or = 2-fold changes, 8 were also increased in gp91(phox)(-/-) mice by conidia and in C57BL/6 mice by polystyrene beads, suggesting a common innate response to particulate matter. Ingenuity analysis of the microarray data from C57BL/6 mice revealed immune cell signaling and gene expression as primary mechanisms of this response. Despite the well-established importance of phagocyte NADPH oxidase in resisting aspergillosis, we found no evidence of this mechanism in AM following introduction of conidia into the mouse lung using transcriptional, luminometry, or NBT staining analysis. In support of these findings, we observed that AM from C57BL/6 and gp91(phox)(-/-) mice inhibit conidial germination equally in vitro. Our results indicate that early transcription in mouse AM exposed to conidia in vivo targets neutrophil recruitment, and that NADPH oxidase-independent mechanisms in AM contribute to inhibition of conidial germination.

Fungal infections in primary immunodeficiencies

Patients with phagocytic, cellular, combined and other primary immunodeficiencies exhibit immune deficits that confer increased susceptibility to fungal infections. A number of yeasts and moulds, most commonly Candida and Aspergillus but also Cryptococcus, Histoplasma, Paecilomyces, Scedosporium, Trichosporon, Penicillium and other, rarely isolated, fungal organisms, have been variably implicated in causing disease in patients with chronic granulomatous disease, severe combined immunodeficiency, chronic mucocutaneous candidiasis, hyper-IgE syndrome, myeloperoxidase deficiency, leukocyte adhesion deficiency, defects in the interferon-gamma/interleukin-12 axis, DiGeorge syndrome, X-linked hyper-IgM syndrome, Wiskott-Aldrich syndrome and common variable immunodeficiency. Differences in the spectrum of fungal pathogens as well as in the incidence and clinical presentation of the infections may be observed among patients, depending upon different immune disorders. Fungal infections in these individuals may occasionally be the presenting clinical manifestation of a primary immunodeficiency and can cause significant morbidity and potentially fatal outcome if misdiagnosed or mistreated. A high degree of suspicion is needed and establishment of diagnosis should actively be pursued using appropriate imaging, mycological and histological studies. A number of antifungal agents introduced over the last fifteen years, such as the lipid formulations of amphotericin B, the second-generation triazoles, and the echinocandins, increase the options for medical management of these infections. Surgery may also be needed in some cases, while the role of adjunctive immunotherapy has not been systematically evaluated. The low incidence of primary immunodeficiencies in the general population complicates single-center prospective or retrospective clinical studies aiming to address diagnostic or therapeutic issues pertaining to fungal infections in these patients.

Fulminant mulch pneumonitis: an emergency presentation of chronic granulomatous disease

BACKGROUND

Chronic granulomatous disease (CGD) is associated with multiple and recurrent infections. In patients with CGD, invasive pulmonary infection with Aspergillus species remains the greatest cause of mortality and is typically insidious in onset. Acute fulminant presentations of fungal pneumonia are catastrophic.

METHODS

Case records, radiograph findings, and microbiologic examination findings of patients with CGD who had acute presentations of dyspnea and diffuse pulmonary infiltrates caused by invasive fungal infection were reviewed and excerpted onto a standard format.

RESULTS

From 1991 through 2004, 9 patients who either were known to have CGD or who received a subsequent diagnosis of CGD presented with fever and new onset dyspnea. Eight patients were hypoxic at presentation; bilateral pulmonary infiltrates were noted at presentation in 6 patients and developed within 2 days after initial symptoms in 2 patients. All patients received diagnoses of invasive filamentous fungi; 4 patients had specimens that also grew Streptomyces species on culture. All patients had been exposed to aerosolized mulch or organic material 1-10 days prior to the onset of symptoms. Cases did not occur in the winter. Five patients died. Two patients, 14 years of age and 23 years of age, who had no antecedent history of recognized immunodeficiency, were found to have p47(phox)-deficient CGD.

CONCLUSIONS

Acute fulminant invasive fungal pneumonia in the absence of exogenous immunosuppression is a medical emergency that is highly associated with CGD. Correct diagnosis has important implications for immediate therapy, genetic counseling, and subsequent prophylaxis.

Population pharmacokinetics of micafungin in pediatric patients and implications for antifungal dosing

The echinocandins potentially have an important role in treatment of infections caused by Candida spp. and Aspergillus spp. in immunocompromised children. However, there are no population pharmacokinetic models of the echinocandins for pediatric patients. The safety and descriptive pharmacokinetics of micafungin in children were recently reported. However, a population pharmacokinetic model in children is needed in order to accurately determine the dosage of micafungin that produces an equivalent magnitude of drug exposure to that observed in adults. In order to explore the effect of weight on micafungin pharmacokinetics, a standard two-compartment pharmacokinetic model, a linear model, and an allometric power model were developed. For all three models, the fit to the data was excellent, with comparable measures of precision and bias. However, the superior log-likelihood value of the allometric power model suggested that it best reflected the data and was therefore chosen for a more detailed analysis of the magnitude and pattern of drug exposure which develop following the administration of micafungin. The allometric power model suggested that clearance in smaller children is higher than that predicted on the basis of weight alone. Consequently, a degree of dosage increase is required in smaller children to ensure comparable levels of drug exposure to those observed in larger children and adults. The allometric power model developed in this study enables identification of pediatric dosage regimens of micafungin which, based upon Monte Carlo simulations, result in equivalent drug exposures to those observed in adults, for which antifungal efficacy has been established.