IL-23 and the Th17 pathway promote inflammation and impair antifungal immune resistance

Although inflammation is an essential component of the protective response to fungi, its dysregulation may significantly worsen fungal diseases. We found here that the IL-23/IL-17 developmental pathway acted as a negative regulator of the Th1-mediated immune resistance to fungi and played an inflammatory role previously attributed to uncontrolled Th1 cell responses. Both inflammation and infection were exacerbated by a heightened Th17 response against Candida albicans and Aspergillus fumigatus, two major human fungal pathogens. IL-23 acted as a molecular connection between uncontrolled fungal growth and inflammation, being produced by dendritic cells in response to a high fungal burden and counter-regulating IL-12p70 production. Both IL-23 and IL-17 subverted the inflammatory program of neutrophils, which resulted in severe tissue inflammatory pathology associated with infection. Our data are the first demonstrating that the IL-23/IL-17 pathway promotes inflammation and susceptibility in an infectious disease model. As IL-23-driven inflammation promotes infection and impairs antifungal resistance, modulation of the inflammatory response represents a potential strategy to stimulate protective immune responses to fungi.

Pneumopericardium due to invasive pulmonary aspergillosis

We describe a 59-year-old female patient with leukemia who developed pneumopericardium as a complication of invasive pulmonary aspergillosis. Spiral computed tomography (CT) was very helpful for the detection of such complications.

[LTR retrotransposons from genomes of Aspergillus fumigatus and A. nidulans]

Fungi Aspergillus spp. are able to infect all tissues and organs and often cause invasive mycosis (aspergillosis), which is usually a fatal disease, especially in the patients with compromised immune system. Microbiological monitoring of these infectious agents is necessary in modem medical facilities. Mobile elements can be used as markers for identification of species and strains of Aspergillus found indoors as well as in aspergillosis diagnostics. Genomic sequences of two representative Aspergillus species, A. fumigatus and A. nidulans, were analysed in silico in order to detect LTR retrotransposons. We found considerable differences in the composition of retrotransposon families between two studied species. One of the detected families, which is present in both studied Aspergillus species, is phylogenetically quite different from all other known fungal retrotransposons. The majority of elements are represented by damaged copies. Nevertheless, we describe for the first time allegedly non-damaged LTR copies that contain intact ORFs and could be active.

Role of Toll-like receptors in lung innate defense against invasive aspergillosis. Distinct impact in immunocompetent and immunocompromized hosts

Toll-like receptors are key to pathogen recognition by a host and to the subsequent triggering of an innate immune response. Experimental and clinical evidence shows that defects in Toll-like receptors or in signaling pathways downstream from these receptors render hosts susceptible to various types of infection, including aspergillosis. Patients receiving an immunosuppressive regimen, including corticosteroid therapy or cytotoxic chemotherapy, are also susceptible to infections. Aspergillus fumigatus is an opportunistic pathogen that infects the lungs of immunosuppressed hosts. Here, we review the evidence that experimental inactivation of various Toll-like receptors and of their signaling pathways may worsen cases of invasive pulmonary aspergillosis. Moreover, the literature clearly indicates that the type of immunosuppression is very important, as it influences whether or not Toll-like receptors contribute to infection. The involvement of Toll-like receptors, based on the immunological status of the patient, should be considered if an immunosuppressive treatment must be administered.

Effectsof Aspergillus fumigatusgliotoxin and methylprednisolone on human neutrophils: implications for the pathogenesis of invasive aspergillosis

Aspergillus fumigatus (AF) is a ubiquitous mold and the most common cause of invasive aspergillosis (IA) in immunocompromised patients. In stem cell transplant recipients, IA now occurs most frequently in the setting of therapy with corticosteroids, including methylprednisolone (MP). We showed previously that gliotoxin (GT), an AF-derived mycotoxin, induces apoptosis in monocytes and dendritic cells, resulting in the suppression of AF-specific T cell responses. We examined the ability of GT to induce apoptosis in polymorphonuclear leukocytes (PMN) and assessed GT effects on important neutrophil functions, including phagocytic function, degranulation, myeloperoxidase activity, and the production of reactive oxygen species (ROS). In contrast to its effects on monocytes, PMN remained resistant to GT-mediated apoptosis. Although many essential neutrophil functions were unaffected, GT inhibited phagocytosis and also induced a decrease in ROS generation by PMN. In contrast, MP therapy potentiated ROS production, suggesting a mechanism that may facilitate tissue injury in IA. Distinct from its effects on untreated PMN, GT augmented ROS production in MP-treated PMN. Our results suggest that although GT may suppress the adaptive immune response, GT may also serve to increase PMN-mediated inflammation, which is likely to play an important role in tissue destruction in the setting of IA.

Successful early voriconazole treatment of Aspergillus infection in two non immunocompromised patients in Intensive Care Unit

We report two cases of respiratory Aspergillus infection that occurred in patients admitted to the Intensive Care Unit of a teaching hospital during renovation works and treated with new triazole voriconazole (Vfend). The first patient was affected with cerebral hemorrhage, the second with polytrauma and both developed Aspergillus Pneumonia during their ICU stay. Bronchoalveolar lavage, dosage with anti-Aspergillus antibodies, antigen measurements and galactomannan research with Sanofi Platelia were performed. Therapy was carried out with voriconazole for 12 days. Chest X-ray and laboratory tests showed complete resolution after 12 days of therapy; clinical symptoms were negative after 4 days. Aspergillus infection can be observed frequently in non-immunocompromised patients during ward renovation or in hospitals near building areas. Since treatment is often unsuccessful, we preferred to immediately employ new agents to reduce the impact of this disease.

[Bronchopulmonary aspergillosis infections in the non-immunocompromised patient]

The definition of broncho-pulmonary aspergillosis infections in non-immunocompromised patients remains vague and a wide range of clinical, radiological and pathological entities have been described with a variety of names, i.e. simple aspergilloma, complex aspergilloma, semi-invasive aspergillosis, chronic necrotizing pulmonary aspergillosis, chronic cavitary and fibrosing pulmonary and pleural aspergillosis, pseudomembranous tracheobronchitis caused by Aspergillus, and invasive aspergillosis. However, these disease entities share common characteristics suggesting that they belong to the same group of pulmonary aspergillosis infectious disorders: 1- a specific diathesis responsible for the deterioration in local or systemic defenses against infection (alcohol, tobacco abuse, or diabetes); 2- an underlying bronchopulmonary disease responsible or not for the presence of a residual pleural or bronchopulmonary cavity (active tuberculosis or tuberculosis sequelae, bronchial dilatation, sarcoidosis, COPD); 3- generally, the prolonged use of low-dose oral or inhaled corticosteroids and 4- little or no vascular invasion, a granulomatous reaction and a low tendency for metastasis. There are no established treatment guidelines for broncho-pulmonary aspergillosis infection in non-immunocompromised patients, except for invasive aspergillosis. Bronchial artery embolization may stop hemoptysis in certain cases. Surgery is generally impossible because of impaired respiratory function or the severity of the comorbidity and when it is possible morbidity and mortality are very high. Numerous clinical cases and short retrospective series have reported the effect over time of the various antifungal agents available. Oral triazoles, i.e. itraconazole, and in particular voriconazole, appear to provide suitable treatment for broncho-pulmonary aspergillosis infections in non-immunocompromised patients.

Common variable immune deficiency and lung transplantation

We report on a male patient with bronchiectasis secondary to common variable immune deficiency (CVID) receiving lung transplantation. The patient had been diagnosed with CVID many y prior to right-sided single lung transplantation and was receiving appropriate immunoglobulin substitution therapy. He received antithymocyte globulin induction and maintenance triple therapy with cyclosporine, azathioprine and prednisolone. The early post-operative course was complicated by the development of severe acute cellular rejection and organizing pneumonia. Despite immunoglobulin replacement and antifungal prophylaxis and treatment, Aspergillus fumigatus was repeatedly cultured from bronchoalveolar lavage fluid, 18 months after transplantation. The patient died following a protracted period of repeated hospital admissions, 46 months after transplantation. A review of the literature suggests that many CVID patients appear to have had a complicated post-operative course after lung- and other solid-organ transplantation, and highlights the need for the establishment of international registries for transplanted patients with uncommon conditions.

Invasive fungal infections in allogeneic and autologous stem cell transplant recipients: a single-center study of 166 transplanted patients

OBJECTIVES

Invasive fungal infections (IFIs) remain a major cause of infection-related morbidity and mortality following hematopoietic stem cell transplantation (HSCT).

PATIENTS AND METHODS

We retrospectively analyzed the incidence of IFIs in 166 patients undergoing either allogeneic or autologous HSCT at our institution between January 2000 and December 2003.

RESULTS

Incidence of invasive aspergillosis (IA) and invasive candidiasis among allogeneic HSCT recipients was 23% (16-32%, 95% confidence interval [CI]) and 3% (1-9%, 95% CI), respectively. Duration of neutropenia and reduced-intensity conditioning were the only risk factors for IA in the multivariate model. Patients with IA had significantly reduced overall survival (8% versus 56%, P=0.01) due to higher transplant-related mortality (63% versus 31%, P=0.03). Following autologous HSCT, incidence of IA and invasive candidiasis was 8% (4-19%, 95% CI) and 2% (0.2-11%, 95% CI), respectively. Duration of neutropenia was the only risk factor for the development of IA following autologous HSCT. Overall survival of autologous HSCT recipients with IA was similar to that of patients without IA. Seventeen percent of autologous HSCT recipients were colonized with Candida species. Compared with non-colonized patients these patients had significantly reduced overall survival (72% versus 23%, P=0.004), due to increased treatment-related mortality (23% versus 9%, P=0.02).

CONCLUSION

Diagnosis of IA following allogeneic HSCT and Candida colonization in the setting of autologous HSCT defines patient populations with poor outcome but primarily not as a result of the fungal pathogen. Regarding the incidence of IA, duration of neutropenia is the main risk factor, and dose-reduced conditioning is an additional risk factor for the development of IA following allogeneic HSCT, probably owing to increased recipient age in this patient cohort, requiring further studies in this transplantation setting.

Thymosin alpha1: an endogenous regulator of inflammation, immunity, and tolerance

Thymosin alpha1 (Talpha1), first described and characterized by Allan Goldstein in 1972, is used worldwide for the treatment of some immunodeficiencies, malignancies, and infections. Although Talpha1 has shown a variety of effects on cells and pathways of the immune system, its central role in modulating dendritic cell (DC) function has only recently been appreciated. As DCs have the ability to sense infection and tissue stress and to translate collectively this information into an appropriate immune response, an action on DCs would predict a central role for Talpha1 in inducing different forms of immunity and tolerance. Recent results have shown that Talpha1: (a) primed DCs for antifungal Th1 resistance through Toll-like receptor (TLR)/MyD88-dependent signaling and this translated in vivo in protection against aspergillosis; (b) activated plasmacytoid DCs (pDC) via the TLR9/MyD88-dependent viral recognition, thus leading to the activation of interferon regulatory factor 7 and the promotion of the IFN-alpha/IFN-gamma-dependent effector pathway, which resulted in vivo in protection against primary murine cytomegalovirus infection; (c) induced indoleamine 2,3-dioxygenase activity in DCs, thus affecting tolerization toward self as well as microbial non-self-antigens, and this resulted in vivo in transplantation tolerance and protection from inflammatory allergy. Talpha1 is produced in vivo by cleavage of prothymosin alpha in diverse mammalian tissues. Our data qualify Talpha1 as an endogenous regulator of immune homeostasis and suggest that instructive immunotherapy with Talpha1, via DCs and tryptophan catabolism, could be at work to control inflammation, immunity, and tolerance in a variety of clinical settings.

Two children with invasive gastrointestinal aspergillosis

We report two immunocompromised infants aged six and four months with invasive gastrointestinal aspergillosis. Both patients presented with weight loss and diarrhea. The underlying disorders were combined immunodeficiency and transient hypogammaglobulinemia of infancy. The diagnosis of gastrointestinal aspergillosis was established by gastrointestinal endoscopy and histopathological examination of the tissue specimens. Both children responded well to Amphotericin B.

Susceptibility to opportunistic infections in HIV-infected patients with increased CD4 T-cell counts on antiretroviral therapy may be predicted by markers of dysfunctional effector memory CD4 T cells and B cells

OBJECTIVES

HIV-infected patients responding to combination antiretroviral therapy (ART) after experiencing severe immunodeficiency may exhibit persistent immune defects and occasionally experience opportunistic infections (OIs) despite increased CD4 T-cell counts. The investigation of immune defects in such patients was examined in this study.

METHODS

CD4 effector memory T-cell (T(em)-cell) function [assessed by blood cytomegalovirus (CMV) interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot-forming cell assay (ELISPOT) counts] and B-cell dysregulation [assessed by serum immunoglobulin A (IgA) and IgE levels] were examined in 27 patients with increased CD4 T-cell counts after receiving ART for over 2 years. Two of these patients and one other had developed OIs on ART and are described in detail.

RESULTS

Serum levels of IgA and IgE were higher than reference intervals (P<0.001) and CMV IFN-gamma ELISPOT counts were lower than those in non-HIV-infected controls (P<0.001) in the HIV-infected patients. Low CMV IFN-gamma ELISPOT counts were associated with high IgA levels (r=-0.5, P=0.01, Spearman's correlation test) and segregated with high IgE levels (P=0.06, Fisher's test). CMV IFN-gamma ELISPOT counts and serum IgA and IgE levels did not change significantly over a median time of 35 (range 8-60) months after the first measurement, whereas CD4 T-cell counts increased. All three patients who experienced OIs had repeatedly low CMV IFN-gamma ELISPOT counts and increased serum levels of IgA and/or IgE.

CONCLUSION

Low CD4 T(em)-cell function and B-cell dysregulation are immune defects that may persist independently of changes in the CD4 T-cell count in HIV-1-infected patients responding to ART and are associated with an increased risk of developing an OI.

In vitro infection of human dendritic cells by Aspergillus fumigatus conidia triggers the secretion of chemokines for neutrophil and Th1 lymphocyte recruitment

Given the role played by chemokines in the selective homing of immune cells, we sought to characterize the profile of chemokines produced by human dendritic cells (DC) following in vitro Aspergillus fumigatus infection and their ability to recruit cells involved in the antifungal defense. At the onset of A. fumigatus infection, DC released elevated amounts of CXCL8 that promote the migration of polymorphonuclear cells (PMN). Moreover, soluble factors released from A. fumigatus-infected DC increased also the surface expression of two activation markers, CD11b and CD18, on PMN. A. fumigatus infection resulted also in CCL3, CCL4, CXCL10 and CCL20 productions that induce the migration of effector memory Th1 cells. Moreover, the late expression of CCL19 suggests that A. fumigatus-infected DC could be implicated in the migration of CCR7+ naïve T cells and mature DC in lymph nodes. Together these results suggested the involvement of human DC in the regulation of innate and adaptive immunity against A. fumigatus through the recruitment of cells active in the fungal destruction.

Protective role of mannan-binding lectin in a murine model of invasive pulmonary aspergillosis

Innate immune molecules such as lung collectins and serum pentraxins have evolved as important host defence proteins against Aspergillus fumigatus, a medically important opportunistic fungal pathogen. Mannan-binding lectin (MBL), an opsonin and lectin complement pathway activator, constitutes another vital player of innate immunity against several pathogenic organisms in the serum. Studies have reported significant binding of MBL to A. fumigatus; however, the protective role of MBL against A. fumigatus-mediated invasive disease remains elusive. Henceforth, we investigated the contribution of externally administered recombinant human (rh) MBL towards anti-fungal defence in invasive pulmonary aspergillosis (IPA) by in vivo and in vitro studies. In murine models of IPA with corticosteroid-induced immunosuppression, rhMBL-treated mice showed 80% survival compared to untreated IPA mice with no survivors. Treated IPA mice also showed a marked increase in tumour necrosis factor (TNF)-alpha and interleukin (IL)-1alpha and a significant decrease in pulmonary fungal hyphae and IL-10. In vitro, rhMBL-bound A. fumigatus conidia showed a dose-dependent increase in the deposition of C4b, the first product of the lectin pathway. There was an enhanced uptake of A. fumigatus conidia by the polymorphonuclear cells (PMNs) in the presence of rhMBL that increased further in the presence of MBL supplemented with MBL-deficient serum. However, an increase in the oxidative burst of PMNs and A. fumigatus killing were observed only when MBL was supplemented with MBL-deficient serum. The study suggests a therapeutic role of ex vivo-administered MBL in host defence against aspergillosis, possibly through MBL-mediated complement activation and other protective mechanisms aimed both directly at the pathogen, and indirectly through modulation of the host inflammatory responses.

Interleukin-10 promoter polymorphism as risk factor to develop invasive pulmonary aspergillosis

This present study was undertaken to examine the role of the host response to Aspergillus fumigatus in the development of clinical symptoms of invasive pulmonary aspergillosis (IPA). The natural outcome and response to IPA infection varies between individuals. Whereas some variation may be attributable to fungi and environmental variables, it is probable that host genetic background also plays a significant role. Interleukin (IL)-10 has a key function in the regulation of cellular immune responses and is involved in various inflammatory diseases. IL-10 promoter carries a polymorphism that has been associated to production levels. Our aim was to investigate the role of this polymorphism in susceptibility to develop IPA infection. The study included 120 haematological patients and 124 age and sex-matched controls and bi-allelic IL-10 -1082(G/A) polymorphism was examined. Genotypic (p=0.385) and allelic frequencies (p=0.527, OR=0.89, 95% CI=0.78-1.60) were similar between patients and healthy controls. IPA was diagnosed in 59 of the 120 patients according to consensus criteria published by the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group (EORTC/IFICG). Our results provide evidence that IL-10 -1082(AA) genotype is associated with resistance to develop IPA (p=0.001). Allele frequency of IL-10 -1082A allele was weakly associated with susceptibility to develop IPA infection (p=0.052). In conclusion, these results suggest that differential production of IL-10 may alter the risk for IPA in haematological patients.

Rapidly progressive invasive pulmonary aspergillosis in a diabetic man

A 45-year-old man was admitted to our hospital with high fever and a large amount of gray sputum. His initial chest X-ray showed broncho-bronchiolitis and thickening of the large bronchus, and he was subsequently diagnosed with pulmonary aspergillosis based on his sputum culture, polymerase chain reaction for Aspergillus fumigatus, and mannan antigen for Aspergillus. His immune responses, including neutrophil phagocytosis function and neutrophil sterilizing function, were normal as far as we could determine. He was treated with itraconazole, amphotericin B, and meropenem trihydrate, but died of respiratory failure on the twenty-fifth hospital day. Chest X-ray showed rapidly progressive invasive shadows in both lung fields, resulting in multiple cavity formation. This was a rare case of invasive pulmonary aspergillosis in a diabetic man with normal neutrophil phagocytosis function and neutrophil sterilizing function.

Galactomannan antigen enzyme-linked immunosorbent assay for diagnosis of invasive aspergillosis after hematopoietic stem cell transplantation

Invasive aspergillosis is difficult to diagnose in patients undergoing hematopoietic stem cell transplantation (HSCT). In 2003, a serum enzyme-linked immunosorbent assay (ELISA) test for the detection of galactomannan (a glycoprotein found on the Aspergillus cell wall) became available in the United States. In 2004, patients undergoing HSCT were screened biweekly with the galactomannan ELISA at our institution. We performed a retrospective chart review of 121 SCT patients who underwent galactomannan testing. Thirteen of the patients (10.7%) had at least 1 positive galactomannan ELISA, and 4 had multiple positive tests. When calculated in reference to a proved or probable diagnosis of aspergillosis, the galactomannan ELISA had a sensitivity of 0.50 and a specificity of 0.94. The positive predictive value was 0.46, and the negative predictive value was 0.94. Galactomannan ELISA had fewer false-positive and false-negative results in pediatric patients than in adult patients. In 4 of the 12 cases of invasive aspergillosis, the galactomannan ELISA was positive before other microbiologic evidence of aspergillosis was available. In these cases, a positive ELISA predated culture and cytologic evidence of invasive aspergillosis by a mean of 5 days (range, 1-8 days). Our findings indicate that a biweekly serum galactomannan ELISA is a highly specific diagnostic tool for detecting invasive aspergillosis in patients undergoing HSCT. When used regularly, the ELISA may allow for earlier diagnosis of invasive aspergillosis in some patients. The test is troubled by a low sensitivity and high frequency of false-negative tests.

Efficacy of intravenous itraconazole against invasive pulmonary aspergillosis in neutropenic mice

The efficacy of itraconazole (ITZ) solubilized in hydroxypropyl-beta-cyclodextrin (ITZ-IV) was examined in a murine model of invasive pulmonary aspergillosis (IPA). Immunosuppressed mice were infected by the intratracheal inoculation of Aspergillus fumigatus conidia (2 x 10(6) conidia/mouse). Their body weight rapidly decreased and they died within 6 days after infection. Intravenous administration of various doses of ITZ-IV was started 24 h after infection and was continued once a day for 4 days. ITZ-IV at daily doses of 10, 20, or 40 mg/kg was as effective as the intraperitoneal administration of amphotericin B (AMPH) at a dosage of 1 mg/kg daily in improving survival. ITZ-IV (20 mg/kg per day), as well as AMPH (1 mg/kg per day) significantly lowered the fungal burden in the pulmonary tissues. Histological improvement was seen within 2 days after the beginning of administration of ITZ-IV (20 mg/kg per day). In mice intravenously given a single dose of ITZ-IV (20 mg/kg), the blood level and pulmonary tissue level of ITZ plus its active metabolites, mainly hydroxyitraconazole (OH-ITZ), decreased gradually after the injection, but after 4 h their concentration was still between 1.4 microg/ml (ITZ) and 1.9 microg/ml (OH-ITZ), concentrations that were approximately 10 to 20 times greater than the minimum inhibitory concentration (MIC) of ITZ for challenging the strain of A. fumigatus (0.16 microg/ml). These results support the clinical usefulness of ITZ-IV for the treatment of IPA in immunocompromised patients.

Aspergillusiris granuloma in a young male: A case report with review of literature

Endogenous aspergillosis is a rare occurrence. Endogenous Aspergillus endophthalmitis is a rare but devastating infection usually associated with disseminated aspergillosis or with intravenous drug abuse. We report a case of an isolated Aspergillus iris granuloma in a young immunocompetent male patient with review of the literature.