Interleukin-4 causes susceptibility to invasive pulmonary aspergillosis through suppression of protective type I responses

Aspergillus fumigatus, an opportunistic fungal pathogen, causes multiple allergic and nonallergic airway diseases. Invasive pulmonary aspergillosis (IPA) is a nonallergic, life-threatening disease of immunocompromised patients. In a murine model of IPA, interleukin (IL)-4-deficient (IL-4-/-) BALB/c mice were used to examine the role of IL-4 in lung pathology and immune responses. IL-4-/- mice were more resistant than wild-type mice to infection caused by multiple intranasal injections of viable A. fumigatus conidia. Resistance was associated with decreased lung inflammatory pathology, impaired T helper (Th)-2 responses (including lung eosinophilia), and an IL-12-dependent Th1 response. In contrast, development of host-detrimental antifungal Th2 cells occurred in IL-12-/- and interferon-gamma-/- mice and in IL-4-/- mice when subjected to IL-12 neutralization. These results demonstrate that IL-4 renders mice susceptible to infection with A. fumigatus by inhibition of protective Th1 responses. IL-4 appears to have a distinct role in the pathogenesis of allergic and nonallergic lung diseases caused by the fungus.

[Chronic septic granulomatous disease. 14 cases]

OBJECTIVES

Chronic granulomatous disease (CGD) is a rare inherited immunodeficiency. Affected children are mostly boys. The most common clinical features are recurrent bacterial and fungal infections starting at early childhood. We report 14 cases, including 5 girls, of CGD in Tunisian children.

PATIENTS AND METHODS

This retrospective study concerned 14 clinical observations of CGD recorded between April 1988 and December 1998. The diagnosis was established upon determination of a defective respiratory burst in the patients' neutrophils at the tetrazolium nitroblue test (NBT). In 4 cases, the diagnosis was also confirmed by chemiluminescence assay.

RESULTS

The patients (9 boys and 5 girls) belonged to 12 families, 75% of which were consanguineous. In 6 families, there had been several deaths in early childhood. The mean age at onset of clinical signs was 6.8 months (7 days to 24 months). Clinical signs included lung (10 cases), nodal (8 cases), skin (7 cases), and intestinal (7 cases) infections. Seven patients developed invasive pulmonary aspergillosis with parietal extension in 4 cases. Salmonella and Staphylococcus infections were rare in our series. Six children (42.8%) including 2 girls, died. Aspergillosis was fatal in 4 cases.

CONCLUSION

Recurrent infections are the main clinical fetus of chronic granulomatous disease. Prognosis has been improved by the use of prophylactic antibiotics. Early diagnosis of the disease is crucial.

New perspectives in the diagnosis of systemic fungal infections

Profound and prolonged neutropenia following chemotherapy is a major risk factor for systemic fungal infections. Mortality associated with disseminated fungal infection is high, and treatment with conventional amphotericin B is complicated by renal toxicity. Candida and Aspergillus are among the major pathogens in these patients. Many patients remaining neutropenic over a prolonged period of time will receive empirical antifungal therapy. The clinical and laboratory diagnoses of these infections are neither sensitive nor specific and are generally limited in the early detection of invasive fungal infection. However, several new approaches to diagnosis are being developed, which should be translated into routine practice, based on a greater understanding of the pathogenesis of systemic fungal infection and virulence determinants of fungal pathogens. These include antigen detection and polymerase chain reaction. Patients with presumed fungal infection require more intense and accurate monitoring for signs of disseminated infection. Early diagnosis may guide appropriate treatment and prevent mortality. Continued development of commercial tests should help achieve the objective of definitive diagnostic tests for systemic fungal infections.

Absence of protection against challenge with aspergillus fumigatus by adoptive transfer of splenocytes from convalescent turkeys

Only limited protective immunity against aspergillosis after experimental immunization of turkeys has been previously demonstrated. No studies evaluating the efficacy of transfer of immunity in preventing aspergillosis in birds have been reported. This study consisted of two trials assessing the level of protection against Aspergillus fumigatus challenge afforded by transfer of splenocytes from convalescent turkeys. Three treatment groups of 12-to-14-wk-old Beltsville small white (BSW) turkeys comprising the splenocyte donors were prepared by one of the following: 1) intra-air sac (IA) challenge with A. fumigatus conidia 5 wk prior to transfer; 2) IA challenge and then intravenous (i.v.) injection of killed conidia 1 wk prior to transfer; or 3) sham inoculations. Splenocytes from each group were pooled, enriched for mononuclear leukocytes by density gradient centrifugation, and diluted in cell culture medium (CM). Cell viability was assessed by dye exclusion. Each splenocyte preparation was administered intravenously to one of three recipient groups consisting of 10 BSW turkeys each. A control group (n = 10) was given cell-free CM. Recipients were challenged with viable A. fumigatus conidia 16 hr after splenocyte transfer by unilateral IA (trial 1) or i.v. (trial 2) inoculation. Lesion scores postchallenge revealed no differences between turkeys given splenocytes from convalescent vs. naive (control) turkeys. IA exposure produced ipsilateral lesions in air sacs and lung, whereas i.v. exposure produced severe miliary hepatitis. Donor cell function was confirmed by mitogen blastogenesis; however, cells were nonresponsive to A. fumigatus antigens, regardless of previous exposure status.

The use of an in-house modified double antibody sandwich ELISA to detect Aspergillus antigens in sera of immunosuppressed patients

AIM

The purpose of this study was to retrospectively detect Aspergillus antigens in sera obtained from immunocompromised host using an in-house modified double antibody sandwich ELISA.

MATERIALS AND METHODS

The ELISA employed the use of polyclonal antibodies raised against a water-soluble (WS) mycelial component of a clinical isolate of Aspergillus fumigatus. Rabbit and guinea-pig anti-WS antibodies were used as the capture and detector antibodies respectively. This was followed by the addition of anti-guinea pig antibodies conjugated to horse radish peroxidase and orthophenylenediamine.

RESULTS

Of 143 specimens obtained from 140 patients, only 5 (3.5%) specimens demonstrated the presence of antigen. The 5 antigen-positive sera were from three patients. One was a confirmed case of paranasal aspergillosis and the other two were probable cases of invasive aspergillosis.

CONCLUSION

The clinical validity of the ELISA should be determined by prospective detection of Aspergillus antigens in multiple serum samples collected from proven cases of invasive aspergillosis.

Cytokine and chemokine responses following pulmonary challenge with Aspergillus fumigatus: obligatory role of TNF-alpha and GM-CSF in neutrophil recruitment

Aspergillus fumigatus causes life-threatening invasive pulmonary aspergillosis in the immunocompromised patient. In this study we have used a murine model of intratracheal challenge with A. fumigatus to investigate the recruitment of inflammatory cells in the lung and the expression of proinflammatory cytokines and chemokines. Our results show that A. fumigatus causes an acute pulmonary inflammatory response which is dominated by neutrophils and to a lesser extent macrophages. During the peak of infection, proinflammatory cytokines (TNF-alpha, GM-CSF and IL-1beta) and chemokines (MIP-1alpha, MCP-1 and MIP-2), are induced within the lung. Furthermore, treatment of mice with neutralizing anti-TNF-alpha and anti-GM-CSF mAbs reduced the influx of neutrophils into the lung and delayed fungal clearance. Our observations show that Aspergillus conidia are effective inducers of host chemokine responses both in vitro and in vivo. Furthermore, TNF-alpha and GM-CSF play a central role in the recruitment of neutrophils into the lung in response to this clinically important pathogen.

Extent of surgical intervention in primary soft-tissue aspergillosis

Primary invasive Aspergillus Infection of the soft tissue is rare and typically affects immunocompromised patients in several distinct patterns of clinical presentation. In general, the role of surgery in the treatment of this disease is the removal of infected or necrotic tissue to prevent dissemination and mortality. However, the specific surgical recommendations have varied widely among reports due to the varied clinical circumstances in each series. The authors present the case of a patient with a primary invasive Aspergillus infection. They review the reported surgical experience with this disease, and discuss outcomes and surgical approaches in the context of several variations in clinical presentation. In all situations, antifungal therapy and prompt surgical intervention are critical in treating these initially localized but potentially lethal infections. The extent of intervention can range from minor debridement to amputation, and is based on the presence of persistent immunocompromise, the presence and extent of tissue necrosis, and the rate of progression during antifungal therapy.

Invasive aspergillosis in neutropenic patients: rapid neutrophil recovery is a risk factor for severe pulmonary complications

BACKGROUND

In invasive aspergillosis, the duration of neutropenia is an accepted risk factor, and recovery from neutropenia is generally associated with a favourable outcome. However, the rapidity of granulocyte recovery may rarely be associated with adverse sequelae. The purpose of this study was to define the relationship between neutrophil (polymorphonuclear, PMN) recovery after chemotherapy-induced bone marrow aplasia and the occurrence of severe pulmonary complications (haemoptysis, pneumothorax and death) in patients with haematological malignancies who developed invasive fungal pneumonias.

METHODS

Twenty consecutive patients were retrospectively studied; eight of them had developed pulmonary events between 5 and 11 days after neutrophil recovery that followed deep neutropenia (PMN < 100 microL-1).

RESULTS

Five patients had haemoptysis (one of these also had pneumothorax) and three had pneumothorax. According to the multiplicative logistic model, the odds of occurrence of a pulmonary event increased significantly with increasing PMN count on the fifth day (P < 0.001). Five of the eight patients who had pulmonary complications died. Also, the risk of death was larger in the presence of rapid neutrophil recovery, although the difference was not statistically significant (P = 0.111). Analysis of clinical and laboratory data showed that the risk of pulmonary complications significantly increased when the neutrophil concentration was > 4500 microL-1 on day 5 after deep granulocyte neutropenia (PMN < 100 microL-1). There was no correlation between pulmonary complications, dosage of amphotericin B and deaths.

CONCLUSION

The occurrence of life-threatening complications in patients with invasive fungal pneumonia is closely related to rapid PMN recovery.

Aspergillus fumigatus and aspergillosis

Aspergillus fumigatus is one of the most ubiquitous of the airborne saprophytic fungi. Humans and animals constantly inhale numerous conidia of this fungus. The conidia are normally eliminated in the immunocompetent host by innate immune mechanisms, and aspergilloma and allergic bronchopulmonary aspergillosis, uncommon clinical syndromes, are the only infections observed in such hosts. Thus, A. fumigatus was considered for years to be a weak pathogen. With increases in the number of immunosuppressed patients, however, there has been a dramatic increase in severe and usually fatal invasive aspergillosis, now the most common mold infection worldwide. In this review, the focus is on the biology of A. fumigatus and the diseases it causes. Included are discussions of (i) genomic and molecular characterization of the organism, (ii) clinical and laboratory methods available for the diagnosis of aspergillosis in immunocompetent and immunocompromised hosts, (iii) identification of host and fungal factors that play a role in the establishment of the fungus in vivo, and (iv) problems associated with antifungal therapy.

Production of specific monoclonal antibodies to Aspergillus species and their use in immunohistochemical identification of aspergillosis

Two anti-Aspergillus murine monoclonal antibodies (MAbs), designated 164G and 611F, have been produced; both specifically recognize cytoplasmic antigens of A. fumigatus, A. flavus, and A. niger by enzyme-linked immunosorbent assay. The MAbs can identify Aspergillus spp. both in frozen sections by immunofluorescence and in paraffin-embedded clinical specimens by immunofluorescence and immunoperoxidase staining.

Intrabronchial Aspergillus nidulans infection in an immunocompetent man

We describe the first report of intrabronchial Aspergillus nidulans infection in an immunocompetent patient, which fit the description of bronchocentric granulomatosis. The patient had a history of accidental aspiration of light grade oil. Fiberoptic bronchoscopy revealed that the right B4aii alpha was obstructed. Endobronchial biopsy specimens contained fungal hyphae. The fungus was confirmed to be Aspergillus nidulans by culture. We suspected that aspiration of light grade oil had injured the bronchial mucosa, after which airborne Aspergillus nidulans had entered the lesion and multiplied. Intrabronchial fungal infection can occur in a healthy person without immunologic abnormalities, if a bronchial lesion provides an entry portal.

Role of TNF-alpha in pulmonary host defense in murine invasive aspergillosis

Invasive pulmonary aspergillosis is a common and devastating complication of immunosuppression, whose incidence has increased dramatically in tandem with the increase in the number of immunocompromised patients. Given the role of TNF-alpha in other pulmonary infections, we hypothesized that TNF-alpha is an important proximal signal in murine invasive pulmonary aspergillosis. Intratracheal challenge with Aspergillus fumigatus conidia in both neutropenic (cyclophosphamide-treated) and nonneutropenic BALB/c mice resulted in the time-dependent increase in lung TNF-alpha levels, which correlated with the histologic development of a patchy, peribronchial infiltration of mononuclear and polymorphonuclear cells. Ab-mediated neutralization of TNF-alpha resulted in an increase in mortality in both normal and cyclophosphamide-treated animals, which was associated with increased lung fungal burden as determined by histology and as quantified by chitin content. Depletion of TNF-alpha resulted in a reduced lung neutrophil influx in both normal and cyclophosphamide-treated animals, which occurred in association with a decrease in lung levels of the C-X-C chemokine, macrophage inflammatory protein-2 and the C-C chemokines macrophage inflammatory protein-1alpha and JE. In cyclophosphamide-treated animals, intratracheal administration of a TNF-alpha agonist peptide (TNF70-80) 3 days before, but not concomitant with, the administration of Aspergillus conidia resulted in improved survival from 9% in control mice to 55% in TNF70-80-treated animals. These studies indicate that TNF-alpha is a critical component of innate immunity in both immunocompromised and immunocompetent hosts, and that pretreatment with a TNF-alpha agonist peptide in a compartmentalized fashion can significantly enhance resistance to A. fumigatus in neutropenic animals.

Comparison between PCR and detection of antigen in sera for diagnosis of pulmonary aspergillosis

We evaluated the usefulness of PCR and antigen detection for the diagnosis of pulmonary aspergillosis. Forty-four serum samples from patients with pulmonary aspergillosis (33 with pulmonary aspergilloma, 4 with allergic bronchopulmonary aspergillosis, 4 with invasive pulmonary aspergillosis, and 3 with aspergillus pyothorax) were used in this study. PCR detection of Aspergillus DNA in serum samples was successful in 39 patients. Galactomannan antigen was detected by sandwich enzyme-linked immunosorbent assay in 25 patients and by latex agglutination test in 13 patients. Detection of Aspergillus DNA in serum samples by nested PCR had the highest sensitivity of the three methods tested for the diagnosis of pulmonary aspergillosis.

Fungal mastoiditis in immunocompromised children

The immunocompromised host is subject to a variety of opportunistic infections. Mycotic infections, including invasive fungal sinusitis, are a dreaded complication in immune deficient children. Fungal mastoiditis has rarely been described in this population. Our experience with 2 cases of fungal mastoiditis in immunocompromised children is reviewed. Case histories describing aggressive medical management with and without surgical intervention and a review of the literature are presented.

Studies on pulmonary and systemic Aspergillus fumigatus-specific IgE and IgG antibodies in horses affected with chronic obstructive pulmonary disease (COPD)

Inhalant exposure to Aspergillus fumigatus (Asp. f.) antigens induces marked inflammatory and immunological alterations in the lungs of horses affected with chronic obstructive pulmonary disease (COPD). In this study we investigated the role of specific allergen(s) present in Asp. f. on systemic and pulmonary IgE and IgG responses in control and COPD-affected horses, using an enzyme-linked immunosorbent assay (ELISA) and immunoblotting techniques. Compared with controls, horses affected with COPD had significantly higher levels of BALF IgE and IgG to somatic Asp. f. antigens as well as to the allergen 1/a (Asp. f. 1/a). Serum levels of IgE and IgG against these antigens did not differ between control and COPD-affected horses. Antigen specific IgE and IgG levels did not correlate between BALF and serum. Scanning of Asp. f. and IgE and IgG blots revealed bands that are recognised by both IgE- and IgG-specific antibodies. Additionally, all horses responded with BALF IgE- and IgG-specific for 93, 35, 31 and 23 kDa allergens, suggesting that these antigens are involved in the induction of airway IgE and IgG responses. These allergens may have the potential to be used as biomarkers for the diagnosis of Asp. f. related exacerbations of equine COPD.

Improved immunodiagnosis of human candidiasis by an enzyme-linked immunosorbent assay using a Candida albicans 52-kilodalton metallopeptidase

An immunogenic aminopeptidase of Candida albicans was purified by high-performance liquid chromatography. It was then used for the development of an enzyme-linked immunosorbent assay to detect antibodies directed against this antigen in sera from patients with candidiasis. This enzyme specifically cleaves the L-Arg-7-amino-4-methyl-coumarin substrate at pH 7.4 and was detected in the crude extract of different C. albicans isolates. Sera used for this study were obtained from healthy blood donors or from patients with one of the following: systemic candidiasis, aspergillosis, cryptococcosis, toxoplasmosis, or malaria. The statistical analysis demonstrates significant differences between absorbency values obtained with sera from patients with candidiasis and with sera from the other groups (P = 0.000001). Diagnostic parameters show high diagnostic specificity of 97% and a sensitivity of 83% at a cutoff value of 0.425 and suggest the usefulness of this aminopeptidase for the diagnosis of systemic candidiasis.

False-positive results in premature infants with the Platelia Aspergillus sandwich enzyme-linked immunosorbent assay

The sensitivity of a sandwich enzyme-linked immunosorbent assay (ELISA) for detecting Aspergillus galactomannan was tested using 783 serum samples obtained from 247 patients (1-15 sera per patient) with severe underlying diseases (haematological malignancies or intensive care unit stay). We selected 146 serum samples from 50 patients for retesting. Serum samples were frozen after routine testing at -18 degrees C until retesting. All patients charts were checked for signs of Aspergillus infection, such as pneumonia or sinusitis. Adult patients were divided into four groups: proven (5), probable (6), suspected (8) or unlikely (25) Aspergillus infection. The results of Platelia ELISA were 100% in proven, 33% in probable and 50% in suspected Aspergillus infection. Patients with unlikely infection had no positive results with Platelia ELISA. Group 5 consists of six paediatric patients with prolonged ICU stay and a birth weight of 400-1320 g. In five out of six infants we found positive results with Platelia ELISA. All positive results in this group of patients are considered as false positive (83.3%).

Kinetic study of host defense and inflammatory response to Aspergillus fumigatus in steroid-induced immunosuppressed mice

The sequential pathogenesis of pulmonary aspergillosis was studied and the role of inflammatory cytokines in host response to Aspergillus fumigatus was characterized in immunocompetent and immunosuppressed mice. Two distinct phases were observed in immunocompetent mice: First, an intense clearance of A. fumigatus occurred, possibly through alveolar macrophages and recruited neutrophils (PMNL), accompanied by rapid release of tumor necrosis factor-alpha, interleukin (IL)-6, and IL-1beta, and second, cellular and fungal debris were cleaned by recruited monocytes, cytokine production rapidly decreased, and pneumonia self-healed. In contrast, cortisone-treated animals had, first, an altered clearance of conidia and delayed cytokine production and inflammatory cell recruitment; second, an invasive process in lungs, recruitment of PMNL, and release of IL-6 and IL-1beta; and third, widespread tissue necrosis, sustained release of IL-6 and IL-1beta, further increases in PMNL trafficking but no monocyte recruitment, respiratory failure, and 100% mortality within 5 days. These insights may be useful in the development of new treatment strategies for pulmonary aspergillosis.

[Evaluation of an ELISA for the detection of anti-Aspergillus fumigatus antibodies]

An indirect MicroELISA system for the detection of anti-Aspergillus fumigatus antibodies using human anti-IgG conjugated to peroxidase was standardized. Serum samples of two patients having an aspergilloma diagnosed by clinical, microbiological, and serological criteria were used as positive controls. In addition, 119 serum samples of blood donors and 216 serum samples of patients having chronic pneumopathies were also studied. The standardized system may be used as a diagnostic complement for it is able to discriminate between antibody levels (IgG) in different clinical forms of aspergillosis and in those individuals having respiratory diseases which may favour the colonization by this pathogen.

Aspergillus and lung transplant recipients: a mycologic and molecular epidemiologic study

BACKGROUND

After lung transplantation, filamentous fungi and more particularly Aspergillus fumigatus are commonly isolated, although the origin of contamination is unclear.

METHODS

To investigate the fungal flora in bronchoscopic fluids, we retrospectively reviewed 20 cases of lung transplant recipients. Using sequence-specific DNA primers analysis, we typed the clinical strains of A. fumigatus isolated from 6 lung transplant recipients. For 4 of them, the strains of this species were isolated from their environment.

RESULTS

At least once 90% of patients had filamentous fungi, and A. fumigatus was the most frequently isolated. Bronchial colonization was detected in 14 patients, invasive bronchial mycosis was diagnosed in 4 others, and no case of invasive pulmonary fungal infection was detected. Genome typing of the 47 clinical strains revealed that a given patient could be affected by several different strains. A very extensive polymorphism existed among the 38 environmental strains. Origin of contamination at home was possible in 1 case and in the hospital in 3 cases.

CONCLUSIONS

Bronchial colonization is frequent after lung transplantation. Although the clinical strains show a polymorphism, it is less widespread than the polymorphism of environmental strains. The origin of acquisition may be in the patient's community.

Granulocyte colony-stimulating factor and azole antifungal therapy in murine aspergillosis: role of immune suppression

Outbred ICR mice were immune suppressed either with hydrocortisone or with 5-fluorouracil and were infected intranasally with Aspergillus fumigatus. Beginning 3 days before infection some groups of mice were given recombinant human granulocyte colony-stimulating factor (G-CSF), SCH56592 (an antifungal triazole), or both. Corticosteroid-pretreated mice responded to SCH56592 and had reduced counts in lung tissue and prolonged survival. In these mice, G-CSF strongly antagonized the antifungal activity of SCH56592. Animals treated with both agents developed large lung abscesses with polymorphonuclear leukocytes and large amounts of Aspergillus. In contrast, mice made neutropenic with 5-fluorouracil and then infected with A. fumigatus conidia benefited from either G-CSF or triazoles, and the effect of the combination was additive rather than antagonistic. Host predisposing factors contribute in different ways to the outcome of growth factor therapy in aspergillosis.

PCR-ELISA for the early diagnosis of invasive pulmonary aspergillus infection in neutropenic patients

AIM

To evaluate a newly developed aspergillus mitochondrial gene PCR-ELISA assay for the early diagnosis of invasive pulmonary aspergillosis (IPA) in neutropenic patients.

METHODS

The aspergillus mitochondrial gene was chosen for the amplification target for use with a solution hybridisation assay with colorimetric end stage detection in microtitre plate format (PCR-ELISA). The study group comprised neutropenic patients undergoing febrile episodes not responding to standard antibacterial antibiotics. Patients underwent computed tomography and bronchoscopy. Bronchoalveolar lavage (BAL) fluids were examined by culture and PCR.

RESULTS

The aspergillus mitochondrial gene PCR-ELISA was both sensitive (100%) and specific (100%) for IPA in neutropenic patients. All 12 patients with definite or probable IPA had PCR positive BAL fluids. None of the patients with undiagnosed or confirmed infections of other aetiologies were mitochondrial PCR positive. Speciation based upon amplicon size difference was possible.

CONCLUSIONS

Aspergillus mitochondrial DNA PCR-ELISA on BAL fluid is useful in the early diagnosis of IPA in neutropenic patients alone or, potentially, as an indication for thoracic computed tomography.