Particulate Aspergillus fumigatus antigens elicit a TH2 response in BALB/c mice

Insights into the Role of Commensal-Specific T Cells in Intestinal Inflammation

Trillions of microorganisms exist in the human intestine as commensals and contribute to homeostasis through their interactions with the immune system. In this review, we use previous evidence from published papers to elucidate the involvement of commensal-specific T cells (CSTCs) in regulating intestinal inflammatory responses. CSTCs are generated centrally in the thymus or peripherally at mucosal interfaces and present as CD4+ or CD8+ T cells. Bacteria, fungi, and even viruses act commensally with humans, warranting consideration of CSTCs in this critical relationship. Dysregulation of this immunological balance can result in both intestinal inflammation or damaging autoimmune responses elsewhere in the body. Given the relative novelty of CSTCs in the literature, we aim to introduce the importance of their role in maintaining immune homeostasis at barrier sites such as the intestine.

Group 2 Innate Lymphoid Cells and the House Dust Mite-Induced Asthma Mouse Model

Asthma is an important issue not only in health but also in economics worldwide. Therefore, asthma animal models have been frequently used to understand the pathogenesis of asthma. Recently, in addition to acquired immunity, innate immunity has also been thought to be involved in asthma. Among innate immune cells, group 2 innate lymphoid cells (ILC2s) have been considered to be crucial for eosinophilic airway inflammation by releasing T helper 2 cytokines. Moreover, house dust mites (HDMs) belonging to group 1 act on airway epithelial cells not only as allergens but also as cysteine proteases. The production of interleukin-25 (IL-25), IL-33, and thymic stromal lymphopoietin (TSLP) from airway epithelial cells was induced by the protease activity of HDMs. These cytokines activate ILC2s, and activated ILC2s produce IL-5, IL-9, IL-13, and amphiregulin. Hence, the HDM-induced asthma mouse model greatly contributes to understanding asthma pathogenesis. In this review, we highlight the relationship between ILC2s and the HDM in the asthma mouse model to help researchers and clinicians not only choose a proper asthma mouse model but also to understand the molecular mechanisms underlying HDM-induced asthma.

Th2 cells promote eosinophil-independent pathology in a murine model of allergic bronchopulmonary aspergillosis

Repeated inhalation of airborne conidia derived from the fungus Aspergillus fumigatus (Af) can lead to a severe eosinophil-dominated inflammatory condition of the lung termed allergic bronchopulmonary aspergillosis (ABPA). ABPA affects about 5 million individuals worldwide and the mechanisms regulating lung pathology in ABPA are poorly understood. Here, we used a mouse model of ABPA to investigate the role of eosinophils and T cell-derived IL-4/IL-13 for induction of allergic lung inflammation. Selective deletion of IL-4/IL-13 in T cells blunted the Af-induced lung eosinophilia and further resulted in lower expression of STAT6-regulated chemokines and effector proteins such as Arginase 1, Relm-α, Relm-β, and Muc5a/c. Eosinophil-deficient ΔdblGata mice showed lower IL-4 expression in the lung and the number of Th2 cells in the lung parenchyma was reduced. However, expression of the goblet cell markers Clca1 and Muc5a/c, abundance of mucin-positive cells, as well as weight gain of lungs were comparable between Af-challenged ΔdblGata and WT mice. Based on these results, we conclude that T cell-derived IL-4/IL-13 is essential for Af-induced lung eosinophilia and inflammation while eosinophils may play a more subtle immunomodulatory role and should not simply be regarded as pro-inflammatory effector cells in ABPA.

Clinical relevance of Aspergillus fumigatus sensitization in cystic fibrosis

RATIONALE

The clinical relevance of sensitization to Aspergillus (A) fumigatus in cystic fibrosis (CF) is unclear. Some researchers propose that specific A fumigatus IgE is an innocent bystander, whereas others describe it as the major cause of TH-2-driven asthma-like disease.

OBJECTIVES

Lung function parameters in mild CF patients may be different in patients with and without A fumigatus sensitization. We aimed to ascertain whether allergen exposure to A fumigatus by bronchial allergen provocation (BAP) induces TH-2 inflammation comparable to an asthma-like disease.

METHODS

A total of 35 patients, aged 14.8 ± 8.5 years, and 20 healthy controls were investigated prospectively. The patients were divided into two groups: group 1 (n = 18): specific (s)IgE negative, and group 2 (n = 17): sIgE positive (≥0.7 KU/L) for A fumigatus. Lung function, exhaled NO, and induced sputum were analysed. All sensitized patients with an FEV1 > 75% (n = 13) underwent BAP with A fumigatus, and cell counts, and the expression of IL-5, IL-13, INF-γ, and IL-8 as well as transcription factors T-bet, GATA-3, and FoxP3, were measured.

RESULTS

Lung function parameters decreased significantly compared to controls, but not within the CF patient group. After BAP, 8 of 13 patients (61%) had a significant asthmatic response and increased eNO 24 hours later. In addition, marked TH-2-mediated inflammation involving eosinophils, IL-5, IL-13, and FoxP3 became apparent in induced sputum cells.

CONCLUSION

Our study demonstrated the clinical relevance of A fumigatus for the majority of sensitized CF patients. A distinct IgE/TH-2-dominated inflammation was found in induced sputum after A fumigatus exposure.

Bach2 Controls Homeostasis of Eosinophils by Restricting the Type-2 Helper Function of T Cells

Bach2 is a transcription factor which represses its target genes and plays important roles in the differentiation of B and T lymphoid cells. Bach2-deficient (KO) mice develop severe pulmonary alveolar proteinosis, which is associated with increased numbers of granulocytes and T cells. Bach2 is essential for the regulation of T cells, but its role in the regulation of granulocytes is not clear. Here, we observed increased numbers of eosinophils but not neutrophils in the bone marrow, spleen, peripheral blood, and bronchoalveolar lavage fluids of Bach2 KO mice compared with those of wild-type (WT) mice. Upon co-transplantation of the bone marrow cells from CD45.2 Bach2 KO and CD45.1/CD45.2 double-positive WT mice to irradiated WT CD45.1/CD45.2 mice, the reconstituted numbers of eosinophils were similar between Bach2 KO and WT cells. These results showed that the deficiency of Bach2 in eosinophils did not directly drive the differentiation of eosinophils. To investigate the effect of Bach2 KO CD4⁺ T cells upon eosinophils, we analyzed Rag2/Bach2-double deficient (dKO) mice which lack lymphocytes including CD4⁺ T cells. Rag2/Bach2 dKO mice did not show any increase in the numbers of eosinophils. Importantly, Bach2 KO mice showed an increase of interleukin-5 (Il-5) in the sera compared with WT mice. These results suggest that up-regulated functions of CD4⁺ T cells including secretion of Il-5 resulted in proliferation and/or migration to peripheral tissues of eosinophils in Bach2 KO mice. We propose that Bach2 controls homeostasis of eosinophils via restricting the production of Il-5 in CD4⁺ T cells.

Aspergillus in chronic lung disease: Modeling what goes on in the airways

Aspergillus species cause a range of respiratory diseases in humans. While immunocompromised patients are at risk for the development of invasive infection with these opportunistic molds, patients with underlying pulmonary disease can develop chronic airway infection with Aspergillus species. These conditions span a range of inflammatory and allergic diseases including Aspergillus bronchitis, allergic bronchopulmonary aspergillosis, and severe asthma with fungal sensitization. Animal models are invaluable tools for the study of the molecular mechanism underlying the colonization of airways by Aspergillus and the host response to these non-invasive infections. In this review we summarize the state-of-the-art with respect to the available animal models of noninvasive and allergic Aspergillus airway disease; the key findings of host-pathogen interaction studies using these models; and the limitations and future directions that should guide the development and use of models for the study of these important pulmonary conditions.

Repeated Mouse Lung Exposures to Stachybotrys chartarum Shift Immune Response from Type 1 to Type 2

After a single or multiple intratracheal instillations of Stachybotrys chartarum (S. chartarum or black mold) spores in BALB/c mice, we characterized cytokine production, metabolites, and inflammatory patterns by analyzing mouse bronchoalveolar lavage (BAL), lung tissue, and plasma. We found marked differences in BAL cell counts, especially large increases in lymphocytes and eosinophils in multiple-dosed mice. Formation of eosinophil-rich granulomas and airway goblet cell metaplasia were prevalent in the lungs of multiple-dosed mice but not in single- or saline-dosed groups. We detected changes in the cytokine expression profiles in both the BAL and plasma. Multiple pulmonary exposures to S. chartarum induced significant metabolic changes in the lungs but not in the plasma. These changes suggest a shift from type 1 inflammation after an acute exposure to type 2 inflammation after multiple exposures to S. chartarum. Eotaxin, vascular endothelial growth factor (VEGF), MIP-1α, MIP-1β, TNF-α, and the IL-8 analogs macrophage inflammatory protein-2 (MIP-2) and keratinocyte chemoattractant (KC), had more dramatic changes in multiple- than in single-dosed mice, and parallel the cytokines that characterize humans with histories of mold exposures versus unexposed control subjects. This repeated exposure model allows us to more realistically characterize responses to mold, such as cytokine, metabolic, and cellular changes.

Evolution of the Immune Response to Chronic Airway Colonization with Aspergillus fumigatus Hyphae

Airway colonization by the mold Aspergillus fumigatus is common in patients with underlying lung disease and is associated with chronic airway inflammation. Studies probing the inflammatory response to colonization with A. fumigatus hyphae have been hampered by the lack of a model of chronic colonization in immunocompetent mice. By infecting mice intratracheally with conidia embedded in agar beads (Af beads), we have established an in vivo model to study the natural history of airway colonization with live A. fumigatus hyphae. Histopathological examination and galactomannan assay of lung homogenates demonstrated that hyphae exited beads and persisted in the lungs of mice up to 28 days postinfection without invasive disease. Fungal lesions within the airways were surrounded by a robust neutrophilic inflammatory reaction and peribronchial infiltration of lymphocytes. Whole-lung cytokine analysis from Af bead-infected mice revealed an increase in proinflammatory cytokines and chemokines early in infection. Evidence of a Th2 type response was observed only early in the course of colonization, including increased levels of interleukin-4 (IL-4), elevated IgE levels in serum, and a mild increase in airway responsiveness. Pulmonary T cell subset analysis during infection mirrored these results with an initial transient increase in IL-4-producing CD4(+) T cells, followed by a rise in IL-17 and Foxp3(+) cells by day 14. These results provide the first report of the evolution of the immune response to A. fumigatus hyphal colonization.

Role of prostaglandin D2 /CRTH2 pathway on asthma exacerbation induced by Aspergillus fumigatus

Aspergillus fumigatus is often associated in asthmatic patients with the exacerbation of asthma symptoms. The pathomechanism of this phenomenon has not been fully understood. Here, we evaluated the immunological mechanisms and the role of the prostaglandin D2 / Chemoattractant Receptor-Homologous Molecule Expressed on Th2 Cells (CRTH2) pathway in the development of Aspergillus-associated asthma exacerbation. We studied the effects of A. fumigatus on airway inflammation and bronchial hyper-responsiveness in a rat model of chronic asthma. Inhalation delivery of A. fumigatus conidia increased the airway eosinophilia and bronchial hyper-responsiveness in ovalbumin-sensitized, challenged rats. These changes were associated with prostaglandin D2 synthesis and CRTH2 expression in the lungs. Direct inflammation occurred in ovalbumin-sensitized, challenged animals, whereas pre-treatment with an antagonist against CRTH2 nearly completely eliminated the A. fumigatus-induced worsening of airway eosinophilia and bronchial hyper-responsiveness. Our data demonstrate that production of prostaglandin D2 followed by eosinophil recruitment into the airways via a CRTH2 receptor are the major pathogenic factors responsible for the A. fumigatus-induced enhancement of airway inflammation and responsiveness.

Immune response to n-terminal and c-terminal deletion mutants of Aspergillus fumigatus major allergen ASP F 3

The ubiquitous fungus Aspergillus fumigatus causes allergic rhinitis, asthma, sinusitis and allergic bronchopulmonary aspergillosis. A number of major allergens from A. fumigatus are purified, but their structure-function role in the pathogenesis of disease is not known. Such information is essential for devising alternative therapy of fungal allergic diseases. In the present study, N-terminal and C-terminal deletion mutants ofAsp f 3 were constructed and their immunopathological responses studied in a mice model of allergy. Three mutants viz,Asp f 3 (aa 33-168), (aa 1-142), and (aa 23-142) were made by deleting certain amino acids from epitopic regions of full lengthAsp f 3, a major allergen of A. furnigatus. TheAsp f 3 and three mutated proteins were expressed in pET vector. The C-terminal deletion mutantAsp f 3 (aa 1-142) induced elevated IFN-γ but low levels of IL-4 by spleen cells. This mutant also showed significant downregulation of peripheral blood eosinophils and lung inflammation in immunized mice. The N-terminal deletion mutantAsp f 3 (aa 33-168) also exhibited an immuno-suppressive effect in terms of IgE production and induction of Th2 cytokine. The results indicate thatrAsp f 3 and its deletion mutants induced distinct immune-inflammatory responses in mice on challenge with these proteins. The non-IgE binding deletion mutants ofAsp f 3 (aa 1-142 and aa 33-168) could deviate Th2 immune response with a concomitant reduction in airway inflammation and infiltration of inflammatory cells.

Clinical relevance of peripheral blood eosinophil count in allergic bronchopulmonary aspergillosis

BACKGROUND AND AIMS

Currently, there is not a uniform consensus regarding the number of criteria or specific cut-off values for the variety of tests that are used to diagnose allergic bronchopulmonary aspergillosis (ABPA). Traditionally, an eosinophil count >1000 cells/μl is considered an important criterion in the diagnosis of ABPA. The goal of this study was to delineate the significance of the peripheral blood eosinophil count in the diagnosis of ABPA, and the relationship between eosinophil counts and lung function and immunological and radiological parameters.

METHODS

This study was a retrospective analysis of the data from ABPA patients who were managed in our chest clinic. Based on their eosinophil count, the patients were classified into the following three categories: <500, 500-1000 and >1000 cells/μl. The spirometric, immunological and radiological characteristics were also assessed.

RESULTS

We studied 108 males and 101 females with a combined mean (±SD) age of 34.1±12.5years. The median (IQR) eosinophil count at diagnosis was 850 (510-1541)cells/μl, and 60% of the patients had an eosinophil count of <1000 cells/μl. We found no relationship between eosinophil count and lung function using spirometry and other immunological parameters. The median eosinophil count was higher in patients with an high resolution computed tomography (HRCT) chest finding of bronchiectasis (986 vs. 620, p<0.001) vs. those without and in patients with high-attenuation mucus (1200 vs. 800, p<0.001) compared to those without high-attenuation mucus.

CONCLUSIONS

A peripheral blood eosinophil count has limited utility in the diagnosis of ABPA, and there is no relationship between eosinophil count and lung function or other immunological parameters. The higher eosinophil count that we observed in patients with central bronchiectasis or high-attenuation mucus suggests that eosinophils are primary mediators of inflammatory activity in ABPA.

Immunopathology and immunogenetics of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a Th2 hypersensitivity lung disease in response to Aspergillus fumigatus that affects asthmatic and cystic fibrosis (CF) patients. Sensitization to A. fumigatus is common in both atopic asthmatic and CF patients, yet only 1%–2% of asthmatic and 7%–9% of CF patients develop ABPA. ABPA is characterized by wheezing and pulmonary infiltrates which may lead to pulmonary fibrosis and/or bronchiectasis. The inflammatory response is characterized by Th2 responses to Aspergillus allergens, increased serum IgE, and eosinophilia. A number of genetic risks have recently been identified in the development of ABPA. These include HLA-DR and HLA-DQ, IL-4 receptor alpha chain (IL-4RA) polymorphisms, IL-10 −1082GA promoter polymorphisms, surfactant protein A2 (SP-A2) polymorphisms, and cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations. The studies indicate that ABPA patients are genetically at risk to develop skewed and heightened Th2 responses to A. fumigatus antigens. These genetic risk studies and their consequences of elevated biologic markers may aid in identifying asthmatic and CF patients who are at risk to the development of ABPA. Furthermore, these studies suggest that immune modulation with medications such as anti-IgE, anti-IL-4, and/or IL-13 monoclonal antibodies may be helpful in the treatment of ABPA.

Allergic bronchopulmonary aspergillosis in asthma and cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a Th2 hypersensitivity lung disease in response to Aspergillus fumigatus that affects asthmatic and cystic fibrosis (CF) patients. Sensitization to A. fumigatus is common in both atopic asthmatic and CF patients, yet only 1-2% of asthmatic and 7-9% of CF patients develop ABPA. ABPA is characterized by wheezing and pulmonary infiltrates which may lead to pulmonary fibrosis and/or bronchiectasis. The inflammatory response is characterized by Th2 responses to Aspergillus allergens, increased serum IgE and eosinophilia. A number of genetic risks have recently been identified in the development of ABPA. These include HLA-DR and HLA-DQ, IL-4 receptor alpha chain (IL-4RA) polymorphisms, IL-10-1082GA promoter polymorphisms, surfactant protein A2 (SP-A2) polymorphisms, and cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations. The studies indicate that ABPA patients are genetically at risk to develop skewed and heightened Th2 responses to A. fumigatus antigens. These genetic risk studies and their consequences of elevated biologic markers may aid in identifying asthmatic and CF patients who are at risk to the development of ABPA. Furthermore, these studies suggest that immune modulation with medications such as anti-IgE, anti-IL-4 and/or IL-13 monoclonal antibodies may be helpful in the treatment of ABPA.

Aspergillus fumigatus regulates mite allergen-pulsed dendritic cells in the development of asthma

BACKGROUND

The role in allergic asthma development of the immune response against fungi with concomitant exposure to other common aeroallergens has yet to be determined. In particular, there is little understanding of how inhaled fungi affect the host response to mite allergens.

OBJECTIVE

To characterize the in vitro and in vivo effects of concurrent exposure of Aspergillus fumigatus (Af) and Dermatophagoides farinae (Derf) on dendritic cells (DCs) in the development of allergic asthma.

METHODS

Murine bone marrow-derived DCs were pulsed with Derf and/or live or heat-inactivated Af. Cytokine production and the expression of pathogen recognition receptors (PRRs) were determined in vitro. Subsequently, these DCs were inoculated into the airway of naïve mice to assess the development of allergic airway inflammation in vivo. The effect of antibodies against PRRs was also evaluated.

RESULTS

Live Af significantly enhanced IL-10 production and the expression of Toll-like receptor (TLR) 2 and Dectin-1 in Derf-pulsed DCs. Live Af infection significantly attenuated Derf-pulsed DC-induced allergic airway inflammation in vivo. Antibodies against either TLR2 or Dectin-1 significantly reversed the inhibitory effects of live Af in the development of Derf-pulsed DC-induced allergic airway inflammation.

CONCLUSION

Concurrent exposure of DCs to fungal antigens has profound influences on the subsequent mite allergen-induced allergic airway inflammation. Live Af could regulate the functions of airway DCs in the development of mite allergen-induced allergic airway inflammation via regulation of their PRRs. Our results suggest that concurrent exposure to pathogens such as fungi and mite allergens has profound influences on the subsequent allergen-induced allergic airway inflammation. Furthermore, modulating PRR signalling could provide a therapeutic regimen for the development of asthma.

A comparison between intratracheal and inhalation delivery of Aspergillus fumigatus conidia in the development of fungal allergic asthma in C57BL/6 mice

Allergic asthma is a debilitating disease of the airways characterized by airway hyperresponsiveness, eosinophilic inflammation, goblet cell metaplasia with associated mucus hypersecretion, and airway wall remodelling events, particularly subepithelial fibrosis and smooth muscle cell hyperplasia. Animal models that accurately mimic these hallmarks of allergic airways disease are critical for studying mechanisms associated with the cellular and structural changes that lead to disease pathogenesis. Aspergillus fumigatus, is a common aeroallergen of human asthmatics. The intratracheal (IT) delivery of A. fumigatus conidia into the airways of sensitized mice has been described as a model of allergic disease. Here, we compared the IT model with a newly developed inhalation (IH) challenge model. The IH model allowed multiple fungal exposures, which resulted in an exacerbation to the allergic asthma phenotype. Increased recruitment of eosinophils and lymphocytes, the hallmark leukocytes of asthma, was noted with the IH model as compared to the IT model in which macrophages and neutrophils were more prominent. Immunoglobulin E (IgE) production was significantly greater after IH challenge, while that of IgG(2a) was higher after IT challenge. Airway wall remodelling was pronounced in IH-treated mice, particularly after multiple allergen challenges. Although the IT model may be appropriate for the examination of the played by innate cells in the acute response to fungus, it fails to consistently reproduce the chronic remodelling hallmarks of allergic asthma. The ability of the IH challenge to mimic these characteristics recommends it as a model suited to study these important events.

Bone marrow cell derived arginase I is the major source of allergen-induced lung arginase but is not required for airway hyperresponsiveness, remodeling and lung inflammatory responses in mice

Background

Arginase is significantly upregulated in the lungs in murine models of asthma, as well as in human asthma, but its role in allergic airway inflammation has not been fully elucidated in mice.

Results

In order to test the hypothesis that arginase has a role in allergic airway inflammation we generated arginase I-deficient bone marrow (BM) chimeric mice. Following transfer of arginase I-deficient BM into irradiated recipient mice, arginase I expression was not required for hematopoietic reconstitution and baseline immunity. Arginase I deficiency in bone marrow-derived cells decreased allergen-induced lung arginase by 85.8 ± 5.6%. In contrast, arginase II-deficient mice had increased lung arginase activity following allergen challenge to a similar level to wild type mice. BM-derived arginase I was not required for allergen-elicited sensitization, recruitment of inflammatory cells in the lung, and proliferation of cells. Furthermore, allergen-induced airway hyperresponsiveness and collagen deposition were similar in arginase-deficient and wild type mice. Additionally, arginase II-deficient mice respond similarly to their control wild type mice with allergen-induced inflammation, airway hyperresponsiveness, proliferation and collagen deposition.

Conclusion

Bone marrow cell derived arginase I is the predominant source of allergen-induced lung arginase but is not required for allergen-induced inflammation, airway hyperresponsiveness or collagen deposition.

MicroRNA-21 is up-regulated in allergic airway inflammation and regulates IL-12p35 expression

Allergic airway inflammation is characterized by marked in situ changes in gene and protein expression, yet the role of microRNAs (miRNAs), a new family of key mRNA regulatory molecules, in this process has not yet been reported. Using a highly sensitive microarray-based approach, we identified 21 miRNAs with differential expression between doxycycline-induced lung-specific IL-13 transgenic mice (with allergic airway inflammation) and control mice. In particular, we observed overexpression of miR-21 and underexpression of miR-1 in the induced IL-13 transgenic mice compared with control mice. These findings were validated in two independent models of allergen-induced allergic airway inflammation and in IL-4 lung transgenic mice. Although IL-13-induced miR-21 expression was IL-13Ralpha1 dependent, allergen-induced miR-21 expression was mediated mainly independent of IL-13Ralpha1 and STAT6. Notably, predictive algorithms identified potential direct miR-21 targets among IL-13-regulated lung transcripts, such as IL-12p35 mRNA, which was decreased in IL-13 transgenic mice. Introduction of pre-miR-21 dose dependently inhibited cellular expression of a reporter vector harboring the 3'-untranslated region of IL-12p35. Moreover, mutating miR-21 binding sites in IL-12p35 3'-untranslated region abrogated miR-21-mediated repression. In summary, we have identified a miRNA signature in allergic airway inflammation, which includes miR-21 that modulates IL-12, a molecule germane to Th cell polarization.

Immunological mechanisms behind the cystic fibrosis-ABPA link

Allergic bronchopulmonary aspergillosis (ABPA), a pulmonary hypersensitivity disease mediated by an allergic response to Aspergillus fumigatus (A. fumigatus), occurs preferentially in disease conditions with an impaired pulmonary immunity, especially in cystic fibrosis (CF) and allergic asthma. The pathophysiological mechanisms underlying the link between CF and ABPA are poorly understood. Animal and human data support a critical role for chemokines, especially CCL17 and its receptor CCR4, in ABPA. A summary and discussion of the immunological mechanism involved in the pathogenesis of ABPA with a focus on CF lung disease and the role of chemokines is presented here.

Eosinophilic granulocytes and damage-associated molecular pattern molecules (DAMPs): role in the inflammatory response within tumors

The development of a tumor over many years typically leads to reciprocal alternations in the host and the tumor, enabling tumor growth paradoxically in the setting of substantial necrosis and inflammation. When evaluating a tumor, it is important to assess 3 elements: (1) the quantity and quality of tumor-associated leukocytes, (2) their state of activation, and (3) tumor microenvironment. Peripheral blood eosinophilia and tumor-associated tissue eosinophilia are frequently associated with some tumor types and also found after immunotherapy with IL-2, IL-4, granulocyte-macrophage colony-stimulating factor, and antibody to CTLA-4. Within several tumor types including gastrointestinal tumors, tumor-associated tissue eosinophilia is associated with a significantly better prognosis. The converse is true in other tumor types such as differentiated oral squamous cell carcinoma. On the basis of the emergent data, tumor-associated eosinophils have at least 2 dominant nonoverlapping activities: (1) destructive effector functions potentially limiting tumor growth as well as causing recruitment and activation of other leukocytes, (2) immunoregulative and remodeling activities which suppress immune response and promote tumor proliferation. The mechanism by which eosinophils in particular are recruited into tumor tissue is largely unknown. Candidates for causing eosinophil chemotaxis into tumor tissue are the released damage-associated molecular pattern molecules (DAMPs) including the nuclear protein high mobility group box 1. High mobility group box 1 is released upon necrotic cell death and secreted by many cells, particularly during periods of nutrient, hypoxic, or oxidant stress. This overview on eosinophil biology in the context of cancer and necrosis, introduces intriguing and novel strategies targeting eosinophils to enable more effective biologic therapy for cancer patients.

Aspergillus fumigatus challenge increases cytokine levels in nasal lavage fluid

Several studies have shown an association between exposure in moisture-damaged buildings and adverse health effects. There are several indicator microbes of moisture damage, but Aspergillus fumigatus is one of the best-documented molds provoking health problems in different occupational conditions. We assessed whether inhalation of a commercial A. fumigatus solution would affect cytokine levels (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-4, IL-6, interferon [IFN]-gamma) in nasal lavage fluid (NAL) compared with that evoked by placebo challenge. Twenty-seven subjects were studied: 13 had occupational exposure in a moisture-damaged building, 4 were atopic, and 10 were considered as controls. In all the subjects, the IL-1beta levels were increased significantly both at 6 (p = 0.013) and 24 h (p = .005) after the A. fumigatus challenge compared to placebo. In subjects with previous occupational exposure in a moisture-damaged building, IL-4 concentrations were increased significantly both at 6 (p =.046) and 24 h (p =.008) after the A. fumigatus challenge compared with placebo. Furthermore, in the control group, TNF-alpha levels were significantly increased at 6 h after the A. fumigatus challenge compared to placebo (p = .028). Thus, these data show a link between markers of inflammation in NAL and experimental A. fumigatus challenge.

Effect of a CD4-depleting antibody on the development of Cryptococcus neoformans-induced allergic bronchopulmonary mycosis in mice

Allergic bronchopulmonary mycosis (ABPM) is a hypersensitivity lung disease in which fungal colonization is accompanied by an allergic response to the fungus. Using a mouse model of ABPM caused by Cryptococcus neoformans infection of C57BL/6 mice, the goal of the present studies was to determine the effect of the CD4-depleting monoclonal antibody GK1.5 on the development of the allergic responses seen during active fungal infection. These results would provide insight into the role of CD4(+) T cells in this disease. Our results show that GK1.5 treatment resulted in attenuation of pulmonary inflammation and eosinophilia in these animals. These mice also had reduced T2 cytokine production and no serum immunoglobulin E production. Absence of CD4(+) T cells did not affect recruitment of CD8(+) T cells to the site of infection; however, the numbers of CD19(+) B cells were severely reduced in the lungs of CD4(+) T-cell-depleted animals. We also examined changes in the pulmonary architecture and found that depletion of CD4(+) T cells was associated with a significant reduction in mucus production and goblet cell metaplasia in these mice. Interestingly, attenuation of Th2 responses in CD4(+) T-cell-depleted animals did not increase the fungal load in their lungs. We also compared development of ABPM in young and mature mice and did not find any differences at any of the time points. Overall, our results show that depletion of CD4(+) T cells prevents the development of Th2 responses seen during ABPM.

A murine model of invasive aspergillosis: variable benefit of interferon-gamma administration under in vitro and in vivo conditions

BACKGROUND

Interferon-gamma modulates host defense in a number of infectious diseases. Previous studies have shown that systemic administration of interferon-gamma (IFN-gamma) can enhance survival in experimental invasive aspergillosis (IA).

METHODS

Using a novel model of murine IA that is characterized by primary pulmonary infection, we investigated the role of IFN-gamma in the phagocytosis and killing of Aspergillus fumigatus by murine neutrophils and pulmonary alveolar macrophages in vitro and the impact of systemic and regional administration of IFN-gamma on the course of IA in glucocorticoid-treated mice.

RESULTS

In vitro, IFN-gamma significantly enhanced phagocytosis and killing function of both neutrophils and alveolar macrophages from normal animals, but not cortisone-treated animals. In vivo, intravenous administration of IFN-gamma did not improve phagocyte recruitment, in vivo killing, or mortality from IA. Regional (intranasal) administration of IFN-gamma to the lungs enhanced recruitment of phagocytic cells to the lungs and improved in vivo killing, but did not alter (and actually worsened) mortality from IA.

CONCLUSIONS

The in vitro and in vivo effects of IFN-gamma in IA are contingent on many variables, including the route of administration and the specific pathogenesis of infection.

Allergic bronchopulmonary aspergillosis in paediatric cystic fibrosis patients

Allergic bronchopulmonary aspergillosis (ABPA) is a severe complication in children, adolescents and adults with cystic fibrosis (CF), the prevalence of which ranges from 6-25%. The disease is the result of the colonisation of the respiratory tract by fungi of the genus Aspergillus, commonly Aspergillus fumigatus, and subsequent host sensitisation to fungal antigens, accompanied by a Th2 CD4 type response mediated by the production of specific IgE. The consequent inflammatory and obstructive bronchopulmonary injury can progress to fibrosis. The diagnosis should be considered early in patients with CF who show wheezing, transient pulmonary infiltrates and reduced lung function. The objective diagnosis is not straightforward because of overlapping clinical and radiological signs, particularly the progression of bronchiectasis. Specific criteria are needed for the diagnosis of ABPA in patients with CF, such as those proposed by the Cystic Fibrosis Foundation. The study of specific IgE against recombinant antigens of A. fumigatus has contributed to the early diagnosis of ABPA with high sensitivity and specificity. The technique has also shown promise in the follow-up of patients after steroid therapy and the early detection of recurrences. Treatment consists of long-term systemic corticosteroid usage, the monitoring of their adverse effects, and of the measurement of total serum IgE levels. The concomitant use of oral itraconazole seems to promote a better control of the disease and to reduce the duration of systemic steroid therapy but its use continues to be controversial. Controlled studies involving larger numbers of patients are necessary if we are to better understand the management of ABPA.

Distinct CD4+-T-cell responses to live and heat-inactivated Aspergillus fumigatus conidia

Aspergillus fumigatus is an important fungal pathogen that causes invasive pulmonary disease in immunocompromised hosts. Respiratory exposure to A. fumigatus spores also causes allergic bronchopulmonary aspergillosis, a Th2 CD4+-T-cell-mediated disease that accompanies asthma. The microbial factors that influence the differentiation of A. fumigatus-specific CD4+ T lymphocytes into Th1 versus Th2 cells remain incompletely defined. We therefore examined CD4+-T-cell responses of immunologically intact mice to intratracheal challenge with live or heat-inactivated A. fumigatus spores. Live but not heat-inactivated fungal spores resulted in recruitment of gamma interferon (IFN-gamma)-producing, fungus-specific CD4+ T cells to lung airways, achieving A. fumigatus-specific frequencies exceeding 5% of total CD4+ T cells. While heat-inactivated spores did not induce detectable levels of IFN-gamma-producing, A. fumigatus-specific CD4+ T cells in the airways, they did prime CD4+ T-cell responses in draining lymph nodes that produced greater amounts of interleukin 4 (IL-4) and IL-13 than T cells responding to live conidia. While immunization with live fungal spores induced antibody responses, we found a marked decrease in isotype-switched, A. fumigatus-specific antibodies in sera of mice following immunization with heat-inactivated spores. Our studies demonstrate that robust Th1 T-cell and humoral responses are restricted to challenge with fungal spores that have the potential to germinate and cause invasive infection. How the adaptive immune system distinguishes between metabolically active and inactive fungal spores remains an important question.

Comparative studies of mitogen- and antigen-induced lymphocyte proliferation in four captive rhinoceros species

Cellular immune function in four rhinoceros species was evaluated by way of in vitro lymphocyte proliferation responses to mitogenic and antigenic stimuli to establish normative data on white blood cell activity for each species and to identify species-specific differences that might help explain the predisposition of black rhinoceroses (Diceros bicornis) to disease. A cross section of the U.S. rhinoceros population encompassing all four captive species was sampled, including the Sumatran rhinoceros (Dicerorhinus sumatrensis) (n = 3); Indian rhinoceros (Rhinoceros unicornis) (n = 4); African black rhinoceros (n = 16); and African white rhinoceros (Ceratotherium simum) (n = 10). Of the four species evaluated, African black rhinoceroses exhibited the weakest (P < 0.05) lymphocyte proliferative responses to the mitogens: pokeweed (0.1 microg/ml), phytohemagglutinin (0.3 microg/ml), and concanavalin A (5.0 microg/ml). Total cell density at the end of culture was only 70% of that achieved with lymphocytes isolated from African white rhinoceroses, Indian rhinoceroses, and Sumatran rhinoceroses. However, lymphocyte response to bacterial endotoxin lipopolysaccharide was similar (P > 0.05) across species. Antigenic stimulation produced much weaker responses than mitogenic stimulation. No differences (P > 0.05) were observed among rhinoceros species in response to 1 and 10 microg/ml of Leptospira icterohemorrhagiae or Leptospira gryppotyphosa. Lymphocytes from African white rhinoceroses proliferated weakly in the presence of Aspergillus fumigatus filtrate, whereas lymphocytes from the southern black rhinoceros subspecies appeared slightly suppressed in the presence of increasing doses (0.1, 1, and 10 microg/ml) of Aspergillus filtrate. This comparative data set characterizing lymphocyte proliferation in the rhinoceros reveals several differences in immune cell responses among rhinoceros species and provides some evidence that lymphocytes of captive African black rhinoceroses are less vigorous than those of the other rhinoceros species.

Immunopathogenesis of allergic bronchopulmonary aspergillosis in cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity lung disease mediated by an allergic late-phase inflammatory response to Aspergillus fumigatus antigens. ABPA is characterized by markedly elevated Aspergillus-specific and total IgE levels and eosinophilia, and manifested by wheezing, pulmonary infiltrates, and bronchiectasis and fibrosis, which afflict asthmatic and cystic fibrosis (CF) patients. We propose that ABPA develops in genetically susceptible CF patients due to HLA-DR2 and DR5 restriction, increased sensitivity to IL-4 stimulation, and increased A. fumigatus allergen-specific Th2 CD4+ T-cell-mediated responses. In addition, A. fumigatus proteases play a role in facilitation of antigen transport across the epithelial cell layer by damaging the epithelial integrity and by a direct interaction with epithelial cell surface receptors, resulting in pro-inflammatory cytokine production and corresponding inflammatory responses.

Chemokines and cytokines: axis and allies in asthma and allergy

Allergic asthma can be precipitated by many factors. For the atopic person, fungus, pollen, dust mites, cockroach antigens, and diesel exhaust are all agents that may trigger an allergic attack. Cytokines and chemokines are integral mediators of fungal asthma. From the earliest time points, they recruit and activate the cells required for the clearance of fungus as well as being critical factors involved in the immunopathology of this disease. In the final analysis, it is clear that these mediators can act to the benefit or the detriment of the host.

Transcript signatures in experimental asthma: identification of STAT6-dependent and -independent pathways

The analysis of polygenic diseases such as asthma poses a challenging problem. In an effort to provide unbiased insight into disease pathogenesis, we took an empirical approach involving transcript expression profiling of lung tissue from mice with experimental asthma. Asthmatic responses were found to involve sequential induction of 4.7% of the tested genome; notably, there was ectopic expression of a series of genes not previously implicated in allergic or pulmonary responses. Genes were widely distributed throughout all chromosomes, but preferentially included genes involved in immunity, development, and homeostasis. When asthma was induced by two independent experimental regimens, unique gene transcript profiles were found depending upon the mode of disease induction. However, the majority of genes were common to both models representing an asthma signature genome. Analysis of STAT6-deficient mice revealed that an unexpectedly large segment of the asthma genes were STAT6 independent; this correlated with sustained inflammatory events in these mice. Notably, induction of asthma in STAT6-deficient mice resulted in gene induction not seen in wild-type mice. These results raise concern that therapeutic blockade of STAT6 in the asthmatic setting may reprogram the genetic signature, resulting in alternative lung pathology, which we indeed observed in STAT6-deficient mice. These results provide unprecedented insight into the complex steps involved in the pathogenesis of allergic airway responses; as such, these results have significant therapeutic and clinical implications.

Use of a synthetic peptide epitope of Asp f 1, a major allergen or antigen of Aspergillus fumigatus, for improved immunodiagnosis of allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is an immunologically complex allergic disorder caused by the fungal pathogen Aspergillus fumigatus. Elevated levels of total immunoglobulin E (IgE), specific IgE, and IgG antibodies in sera are important immunodiagnostic criteria for ABPA. International reference standards or standardized immunodiagnostic assays are not available due to a lack of well-defined diagnostic antigens. The present study was carried out to identify and evaluate the immunodiagnostic relevance of synthetic epitopic peptides of Asp f 1, a major allergen, antigen, or cytotoxin of A. fumigatus. Five overlapping peptides were synthesized from the N terminus of Asp f 1, one of the potential immunodominant regions predicted by algorithmic programs. The 11-amino-acid synthetic peptide (P1) significantly inhibited both IgG binding (89.10% +/- 4.45%) and IgE binding (77.32% +/- 3.38%) of the standardized diagnostic antigen (SDA) (a well-defined pool of diagnostically relevant allergens and antigens of A. fumigatus). With a panel of sera of ABPA patients, allergic patients with skin test negativity to A. fumigatus, and healthy individuals, P1 showed a higher diagnostic efficiency than SDA (specific IgG, 100%; specific IgE, 98.3%). The diagnostic efficiency of P1 could be attributed to the presence of homologous epitopes in various immunodominant allergens or antigens of A. fumigatus. The ability of P1 to induce histamine release from sensitized mast cells and a Th2 type of cytokine profile in peripheral blood mononuclear cells of ABPA patients suggests its potential for use in intradermal testing. P1 could be further explored for development of a standardized, specific, and sensitive immunodiagnostic test for aspergillosis.

Vaccinate against aspergillosis! A call to arms of the immune system

Invasive aspergillosis is a devastating and increasingly common disease, seen almost exclusively in immunosuppressed patients. Immunizing an immunocompromised host would seem to be a formidable task; however, virulence factors and immunogens of the pathogen have now been identified and could be targeted, mapping of the genome sequence of the pathogen will soon be completed, and the protective host immune responses and cytokine networking are better understood. These facts, together with recent advances in vaccine science, make consideration of such an approach now possible. Some populations that are at risk for aspergillosis might be likely candidates for receiving the first vaccinations against aspergillosis, or vaccination of a stem cell donor might be considered in some circumstances. Successful immunizations have been demonstrated in turkeys and mice.

Mannose-binding lectin deficiency alters the development of fungal asthma: effects on airway response, inflammation, and cytokine profile

Aspergillus fumigatus is a major fungal pathogen that may be fatal to immunocompromised individuals and causes airway hyperreactivity and remodeling in sensitized individuals. Herein, we examined the role of mannose-binding lectin (MBL), a complement-activating plasma protein, during pulmonary innate and allergic immune responses directed against A. fumigatus spores or conidia. Neither group of nonsensitized MBL-A-sufficient (MBL-A+/+) nor -deficient (MBL-A-/-) mice challenged with an intravenous or intratracheal (i.t.) bolus of A. fumigatus spores experienced fungus-induced mortality, but marked airway remodeling was observed in MBL-A-/- mice challenged i.t. with conidia. In a model of chronic fungal asthma, MBL-A+/+ and MBL-A-/- A. fumigatus-sensitized mice were examined at days 4 and 28 after an i.t. challenge with A. fumigatus conidia. Airway hyperresponsiveness in sensitized MBL-A-/- mice was significantly decreased at both times after conidia challenge compared with the sensitized MBL-A+/+ group. In the sensitized MBL-A-/- mice, whole lung T helper cell type 2 cytokine levels were significantly decreased at day 4 after conidia, and whole lung interferon-gamma levels were significantly increased at day 28 after conidia when compared with controls. However, histological evidence showed similar airway remodeling at day 28 after conidia (i.e., subepithelial fibrosis and goblet cell metaplasia) in the two groups of mice. Thus, these findings show that MBL-A is not required for mouse survival following exposure to A. fumigatus conidia, and this murine collectin isoform contributes to the development and maintenance of airway hyperresponsiveness but not chronic airway remodeling during chronic fungal asthma.

Desloratadine inhibits allergen-induced airway inflammation and bronchial hyperresponsiveness and alters T-cell responses in murine models of asthma

BACKGROUND

Histamine elicits many features of immediate hypersensitivity reactions. Recent evidence indicates that H1 receptors modulate immune responses to antigens. Desloratadine (DL), a new, long-acting, H1 receptor antagonist, has both a potent antihistaminic function and anti-inflammatory properties.

OBJECTIVE

We sought to evaluate the effect of DL on allergic-airway responses in mice after inhalation of the naturally occurring aeroallergen Aspergillus fumigatus (Af ) and to examine the effects of DL on specific immune responses to a defined protein antigen with the use of an ovalbumin (OVA) model of asthma.

METHODS

Mice were subjected either to repeated, intranasal application of Af extract or to intraperitoneal immunization with OVA, followed by inhalation challenge. DL or a control fluid was given daily throughout the sensitization process. Immunoglobulin E (IgE) levels, bronchoalveolar lavage-fluid cytokines and cytology, lung histology, and physiologic responses to methacholine were assessed in the allergen-treated mice. Anti-OVA IgE responses and OVA-driven T-cell cytokine production were examined.

RESULTS

Treatment with DL did not impair IgE production but did inhibit bronchial inflammation and bronchial hyperresponsiveness in both Af- and OVA-treated mice. This inhibition required that DL be administered concurrently with allergen sensitization, indicating that the attenuation of bronchial hyperresponsiveness and inflammation was not caused by anticholinergic receptor effects. OVA-responsive T cells from DL-treated mice exhibited depressed production of IL-4, IL-5, and IL-13 and normal amounts of interferon-gamma. The amounts of IL-5 and IL-13 were also diminished in the bronchoalveolar lavage fluid.

CONCLUSION

DL, given at the time of exposure to the allergen, inhibits T(H)2 responses, the induction of allergic pulmonary inflammation, and bronchial hyperresponsiveness. These results suggest that DL or similar agents given during times of antigen exposure might alter disease progression in patients with respiratory allergy.

Dissection of experimental asthma with DNA microarray analysis identifies arginase in asthma pathogenesis

Asthma is on the rise despite intense, ongoing research underscoring the need for new scientific inquiry. In an effort to provide unbiased insight into disease pathogenesis, we took an approach involving expression profiling of lung tissue from mice with experimental asthma. Employing asthma models induced by different allergens and protocols, we identified 6.5% of the tested genome whose expression was altered in an asthmatic lung. Notably, two phenotypically similar models of experimental asthma were shown to have distinct transcript profiles. Genes related to metabolism of basic amino acids, specifically the cationic amino acid transporter 2, arginase I, and arginase II, were particularly prominent among the asthma signature genes. In situ hybridization demonstrated marked staining of arginase I, predominantly in submucosal inflammatory lesions. Arginase activity was increased in allergen-challenged lungs, as demonstrated by increased enzyme activity, and increased levels of putrescine, a downstream product. Lung arginase activity and mRNA expression were strongly induced by IL-4 and IL-13, and were differentially dependent on signal transducer and activator of transcription 6. Analysis of patients with asthma supported the importance of this pathway in human disease. Based on the ability of arginase to regulate generation of NO, polyamines, and collagen, these results provide a basis for pharmacologically targeting arginine metabolism in allergic disorders.

Animal models of allergic bronchopulmonary aspergillosis

Among the allergic fungi, Aspergillus fumigatus, a saprophytic mold, distributed widely in the environment is a frequently recognized etiologic agent in a number of allergic conditions. Among the different allergic diseases caused by this fungus, allergic bronchopulmonary aspergillosis (ABPA) is by far the most significant one. The immunopathogenesis of this disease is not fully understood. Although several immunomodulatory treatments are available for allergic disease, none of them are applicable or relevant or useful in fungal induced allergy. It is essential to understand the pathogenesis of the disease including the antigen induced immunoregulation and the resulting factors, such as cytokine, chemokines, pathways activating factors, inflammatory and airway remodeling factors need to be understood for intervening with appropriate treatment. Animal models are essential in understanding these features of the disease. Several models of allergic aspergillosis have been developed in recent years in various animals. However, murine models have been studied more carefully and extensively. The exposure to antigen in mice leads to allergy very similar to ABPA with high IgE, elevated peripheral blood and lung eosinophils, pulmonary inflammation, and airway hyperreactivity. The role of various cytokines and chemokines and their receptors were also studied. In addition, immunotherapy and vaccination have been attempted in recent years using the murine model of ABPA. This review covers the murine model of Aspergillus induced allergy and asthma and presented critically our current understanding of the subject and the potential application of such a model in future for developing treatment modalities.

Eotaxin/CCL11 is involved in acute, but not chronic, allergic airway responses to Aspergillus fumigatus

Eotaxin/CCL11 is a major chemoattractant for eosinophils and Th2 cells. As such, it represents an attractive target in the treatment of allergic disease. The present study addresses the role of eotaxin/CCL11 during acute and chronic allergic airway responses to the fungus Aspergillus fumigatus. Mice lacking the eotaxin gene (Eo-/-) and wild-type mice (Eo+/+) were sensitized to A. fumigatus and received either an intratracheal challenge with soluble A. fumigatus antigens (acute model) or an intratracheal challenge with live A. fumigatus spores or conidia (chronic model). Airway hyperresponsiveness and eosinophil, but not T cell, recruitment were significantly decreased at 24 h after the soluble allergen in A. fumigatus-sensitized Eo-/- mice compared with similarly sensitized Eo+/+ mice. In contrast, the development of chronic allergic airway disease due to A. fumigatus conidia was not altered by the lack of eotaxin. Together, these data suggest that eotaxin initiates allergic airway disease due to A. fumigatus, but this chemokine did not appear to contribute to the maintenance of A. fumigatus-induced allergic airway disease.

Altered immune response to liposomal allergens of Aspergillus fumigatus in mice

Aspergillus fumigatus has been implicated as the major pathogenic fungus causing Aspergillus-mediated disorders. It secretes complex glycoprotein antigens and allergens, which induce type I and type III mediated hypersensitivity reactions. The immune response to these allergens/antigens in allergic disorders is characterized by elevated levels of specific IgE, Th2 cytokines and eosinophilia. In the current study, the ability of negatively charged liposomes entrapped with glycoprotein antigens and allergens of A. fumigatus to modulate the immune response was studied. Immune response in mice was evaluated with both free and liposomal formulations. Liposome entrapped glycoprotein antigens/allergens of A. fumigatus elicited a Th1 type response with increased levels of TNF-alpha (5.5-folds), IFN-gamma (four-folds), specific IgG (three-folds) and IgG2a (2.4-folds), low titers of specific IgG1 (2.2-folds decrease) and IgE (three-folds decrease), and decreased peripheral eosinophilia by four-folds in comparison to mice receiving free glycoprotein allergens/antigens of A. fumigatus. Histopathological examination of lung tissue sections clearly indicated reduced eosinophil infiltration in mice immunized with liposomal formulations. These results suggest potential of liposomal formulations for A. fumigatus allergens/antigens for exploration in immunotherapy.

The association of airway hyperresponsiveness and tuberculin responses

BACKGROUND

The balance between the two subsets of T cell is pivotal for allergic sensitization.

OBJECTIVE

We conducted a cross-sectional study of 486 children vaccinated with bacillus Calmette-Guérin (BCG), aged 10-13 years, to evaluate whether tuberculin responses may contribute to airway hyperresponsiveness (AHR).

METHODS

Tuberculin skin test, allergic skin test, and methacholine challenge test were done. The methacholine concentration causing a 20% fall (PC20) in forced expiratory volume in 1 second (FEV1) was used as a threshold of AHR. Atopy was defined as a reaction showing a mean wheal size of > or = 3 mm to one or more allergens on skin prick test (SPT). Two tuberculin units of polysorbate-stabilized purified protein derivatives (PPD) were injected intradermally into the volar surface of the forearm. Reactions were read at 48-72 h as the transverse diameter in millimeters of induration.

RESULTS

Of the children in the study, 12.3% (60/486) had PPD induration; 7.8% (38/486) of children had PPD induration of greater than 10 mm. The PPD induration size was 10.5 +/- 1.03 mm (confidence interval (CI) 7.19-12.33) in atopic children and 11.2 +/- 0.76 mm (CI 7.89-13.1) in nonatopic children. The differences of PPD induration diameter between the two groups were not significant. There was no difference of log PC20 between PPD induration > or = 10 mm and < 10 mm (0.13 +/- 0.18 vs. 0.42 +/- 0.05). The difference of log PC20 between positive and negative tuberculin response was not significant. Children with atopy had lower log PC20 than those without atopy (0.16 +/- 0.07 vs. 0.51 +/- 0.05, P = 0.001). After adjusting for sex, age, height, weight, tuberculin response, atopy was associated with AHR in multivariate analyses (odds ratio = 1.895, CI 1.285-2.505, P = 0.002).

CONCLUSION

These data suggested that a tuberculin response due to mycobacterial infection status have no effect on AHR in schoolchildren.

Do T helpers 1 and 2 recognize different class II MHC molecules? Humoral and cellular immune responses to soluble allergen from Aspergillus fumigatus Asp f2

Cellular signals leading to T helper (Th)1/Th2 shift are not well known. Here we demonstrate that Th1 possibly recognizes peptides presented by the IE molecule of MHC class II while Th2 is activated by the recognition of peptides presented by the IA molecule. BALB/c mice immunized with Asp f2 developed stable IA-restricted Th2 immune response to the 12th day after immunization, as analyzed by IL-2 production. On the contrary, early Th0 cells did not secrete IL-2 upon Asp f2 stimulation but did produce a high level of IL-2 if stimulated in the presence of anti-IA Abs. This effect of anti-IA Abs on early Th0 cells was both MHC IE and CD4(+) cell restricted. In vivo blocking of Asp f2 peptide presentation by the IA molecule led to the formation of antigen-specific cytotoxicity as demonstrated using immune splenocytes as effector cells and Asp f2 loaded P815 cells as targets.

T cell proliferation and cytokine secretion to T cell epitopes of Asp f 2 in ABPA patients

The pathogenesis of allergic bronchopulmonary aspergillosis (ABPA) involves specific cytokines secreted by lymphocytes in response to Aspergillus fumigatus (Af) allergens. To gain information about the lymphoproliferative response and cytokine production against a major Af allergen, Asp f 2, we studied Asp-f-2-specific T cell clones (TCCs) from ABPA patients. TCCs were stimulated with rAsp f 2, its deletion mutants, and synthetic peptides to identify the T cell epitope(s) and to understand cytokine production. PBMCs from four of five ABPA patients showed proliferation in response to Asp f 2. Three TCCs from one patient showed higher IL-5 secretion compared to IL-4 and IFN-gamma. Two TCCs from the second patient showed a mixed Th1/Th2 response, as evidenced by production of IL-4, IL-5, and IFN-gamma. An epitope from the N-terminal region of Asp f 2 induced only IL-5 secretion. High IL-5 secretion might explain the marked eosinophilia observed in ABPA patients.

Modulation of inhaled antigen-induced IgE tolerance by ongoing Th2 responses in the lung

The normal response to inhaled Ag is the absence of Ag-specific IgE and cytokine production to later Ag challenges. Although the mechanism of this aerosol-induced IgE tolerance is not completely understood, it may prevent sensitization to inhaled Ags, which could otherwise lead to allergy and asthma. We examined the consequences of ongoing Th1 and Th2 responses in the lungs of mice during OVA inhalation to mimic conditions that may subvert tolerance and lead to sensitization. We found that concurrent, secondary Th2 lung responses to keyhole limpet hemocyanin or primary responses to Nippostrongylus larvae or Asperigillus fumagatus extract prevented establishment of IgE tolerance to aerosolized OVA. Intranasal rIL-4 given before OVA aerosolization also prevented establishment of tolerance, whereas concurrent Th1 responses to influenza virus or Mycobacterium bovis bacillus Calmette-Guérin had no effect. However, once established, aerosol tolerance to OVA could not be completely broken by OVA rechallenge concurrent with a secondary Th2 response to keyhole limpet hemocyanin or A. fumagatus extract, or by intranasal rIL-4. These data suggest that the immune status of the lung of an individual may profoundly influence the initial response to inhaled Ag, and that aerosol-induced IgE tolerance may not be appropriately established in individuals undergoing concurrent, Th2-mediated responses to Ags or pathogens.

Interleukin-5-mediated allergic airway inflammation inhibits the human surfactant protein C promoter in transgenic mice

Allergen challenge in the lung of humans and animals is associated with surfactant dysfunction, but the mechanism of this effect has not been established. By using a murine model of asthma we now report the effect of allergen-induced airway inflammation on the expression of transgenes regulated by the human surfactant protein (hSP)-C promoter. The hSP-C 3.7-kilobase pair promoter was used to direct the expression of eotaxin, an eosinophil-selective chemokine, into the lungs of several transgenic lines. As expected, the transgenic mice expressed increased amounts of eotaxin mRNA and protein compared with wild-type mice. Surprisingly, following allergen challenge, there was a marked down-regulation of transgene mRNA in three independent transgenic lines. The down-regulation was in contrast to other related proteins such as endogenous eotaxin and surfactant protein D levels, which were both increased following allergen challenge. Consistent with specific down-regulation of the eotaxin transgene, there was no increase in pulmonary eosinophil levels in the transgenic mice above that found in wild-type mice. Analysis of hSP-C transgenic mice with distinct reporter genes and 3'-untranslated regions revealed that allergen challenge was directly affecting the hSP-C promoter. We hypothesized that allergen-induced down-regulation of the hSP-C promoter was related to the eosinophilic inflammation. To test this, we blocked eosinophilic inflammation in the lungs by treating mice with neutralizing antiserum against interleukin-5. Interestingly, this treatment also blocked allergen-induced inhibition of the hSP-C promoter. These results establish that allergic airway inflammation is associated with up-regulation of the surfactant proteins primarily involved in immunity, whereas down-regulation of the surfactant protein primarily involved in maintaining airway patency. Furthermore, the marked down-regulation of the hSP-C promoter is interleukin-5-dependent, implying a critical role for eosinophilic inflammation. These results suggest that alterations in surfactant protein levels may contribute to immune and airway dysfunction in asthma.

Purified recombinant A. fumigatus allergens induce different responses in mice

Aspergillus fumigatus an opportunistic fungus is associated with a number of diseases in humans. Allergy resulting from exposure to the A. fumigatus allergens has been recognized frequently. The damage caused by the disease is very striking in patients with atopy and those with cystic fibrosis. Avoidance to exposure is not feasible because A. fumigatus spores are ubiquitously distributed in the environment. Hence, immunotherapeutic regimens in severe forms of A. fumigatus allergy may have a high potential. However, before such forms of therapy can be envisaged, it is essential to understand the immunopathogenesis. In the present study, we investigated the role of purified A. fumigatus allergens in the development of allergic asthma in mice. We have used four major recombinant A. fumigatus allergens in the murine model. Mice exposed to Asp f 1, f 3, and f 4 showed inflammatory changes in the lungs and airway hyperreactivity. The immune responses, including elevated serum IgE, enhanced eosinophils, recruitment in the peripheral blood and lungs, and expression of regulatory cytokines, are characteristic of a Th2 response. Asp f 6 demonstrated only a reduced response in these animals. The results suggest that the pathology induced by crude A. fumigatus extract results from the cumulative effects of the allergens and the individual responses varied considerably with different purified antigens.

Surfactant proteins A and D protect mice against pulmonary hypersensitivity induced by Aspergillus fumigatus antigens and allergens

Allergic bronchopulmonary aspergillosis (ABPA) is an allergic disorder caused by an opportunistic fungal pathogen, Aspergillus fumigatus (AFU:). Lung surfactant proteins SP-A and SP-D can interact with the glycosylated antigens and allergens of AFU:, inhibit specific IgE binding to these allergens, and block histamine release from sensitized basophils. We have now examined the therapeutic effect of exogenous administration of human SP-A, SP-D, and a recombinant fragment of SP-D (rSP-D), in a murine model of pulmonary hypersensitivity induced by AFU: antigens and allergens, which resembles human ABPA immunologically. The ABPA mice exhibited high levels of AFU:-specific IgG and IgE, blood eosinophilia, extensive infiltration of lymphocytes and eosinophils in the lung sections, and a Th2 cytokine response. Treatment with SP-A, SP-D, and rSP-D lowered blood eosinophilia, pulmonary infiltration, and specific Ab levels considerably, which persisted up to 4 days in the SP-A-treated ABPA mice, and up to 16 days in the SP-D- or rSP-D-treated ABPA mice. The levels of IL-2, IL-4, and IL-5 were decreased, while the level of IFN-gamma was raised in the splenic supernatants of the treated mice, indicating a marked shift from Th2 to Th1 response. These results clearly implicate pulmonary SP-A and SP-D in the modulation of allergic reactions.

Fine particles of widely different composition have an adjuvant effect on the production of allergen-specific antibodies

Diesel exhaust particles (DEP) are reported to increase the specific IgE response to allergens, and results from our laboratory suggest that the particle core of DEP contribute to this adjuvant activity. The purpose of the present study was to explore further the adjuvant effect of particles per se, that is particles by themselves. NIH/Ola mice were given two intraperitoneal injections with ovalbumin (OVA; 10 microg) alone or OVA in combination with PSP, polytetrafluoroethylene (teflon), titanium dioxide (TiO(2)) or amorphous silica particles (2.8x10(10)-2.8x10(12)). Blood samples were drawn 7 days after the last injection, and serum levels of allergen-specific and total IgE and IgG2a were measured. All types of particles gave increased levels of allergen-specific IgE and IgG2a. Similar results were obtained after intranasal or intratracheal instillation with OVA plus PSP or silica. Our results indicate that fine particles of widely different composition may have an adjuvant effect on the production of allergen-specific antibodies.

Peyer's patch eosinophils: identification, characterization, and regulation by mucosal allergen exposure, interleukin-5, and eotaxin

The gastrointestinal immune system is traditionally thought to be composed of lymphocytes located within Peyer's patches and the lamina propria. We have recently reported that eosinophils also reside in the gastrointestinal tract during healthy states, in particular, within the lamina propria, and that these cells substantially increase after oral allergen exposure. We now demonstrate the presence of eosinophils in Peyer's patches and characterize the signals that regulate the accumulation of eosinophils in Peyer's patches. In contrast to the lamina propria, intestinal Peyer's patches have very low levels of eosinophils under healthy states. However, elevated levels of interleukin-5 (IL-5), generated by transgenic or pharmacologic approaches, result in a dramatic increase in eosinophil levels in Peyer's patches. Most eosinophils are located in the outer cortex and interfollicular regions of the Peyer's patches. To dissect the mechanism of eosinophil trafficking to Peyer's patches, the role of eotaxin was examined. Mice transgenic for IL-5 and genetically deficient in eotaxin were found to have reduced levels of eosinophils in Peyer's patches compared with IL-5-transgenic mice. To prove that eosinophils also traffic to Peyer's patches in wild-type mice, allergic hypersensitivity was induced and Peyer's patches were examined. Exposure to mucosal allergen promoted marked accumulation of eosinophils in Peyer's patches and this process was attenuated in eotaxin-deficient mice. In summary, these data demonstrate that elevated levels of IL-5 and mucosal allergen exposure promote eotaxin-dependent eosinophil trafficking to Peyer's patches. These studies suggest that eosinophils may cooperate with lymphocytes in the development of mucosal immune responses in the gastrointestinal tract.

Peyer's patch eosinophils: identification, characterization, and regulation by mucosal allergen exposure, interleukin-5, and eotaxin

The gastrointestinal immune system is traditionally thought to be composed of lymphocytes located within Peyer's patches and the lamina propria. We have recently reported that eosinophils also reside in the gastrointestinal tract during healthy states, in particular, within the lamina propria, and that these cells substantially increase after oral allergen exposure. We now demonstrate the presence of eosinophils in Peyer's patches and characterize the signals that regulate the accumulation of eosinophils in Peyer's patches. In contrast to the lamina propria, intestinal Peyer's patches have very low levels of eosinophils under healthy states. However, elevated levels of interleukin-5 (IL-5), generated by transgenic or pharmacologic approaches, result in a dramatic increase in eosinophil levels in Peyer's patches. Most eosinophils are located in the outer cortex and interfollicular regions of the Peyer's patches. To dissect the mechanism of eosinophil trafficking to Peyer's patches, the role of eotaxin was examined. Mice transgenic for IL-5 and genetically deficient in eotaxin were found to have reduced levels of eosinophils in Peyer's patches compared with IL-5-transgenic mice. To prove that eosinophils also traffic to Peyer's patches in wild-type mice, allergic hypersensitivity was induced and Peyer's patches were examined. Exposure to mucosal allergen promoted marked accumulation of eosinophils in Peyer's patches and this process was attenuated in eotaxin-deficient mice. In summary, these data demonstrate that elevated levels of IL-5 and mucosal allergen exposure promote eotaxin-dependent eosinophil trafficking to Peyer's patches. These studies suggest that eosinophils may cooperate with lymphocytes in the development of mucosal immune responses in the gastrointestinal tract.

Biologic markers of airway inflammation in asthma

Asthma is a serious chronic disease of the airways that affects approximately 14% of the population in the United States. The fundamental pathophysiologic component of asthma is airway narrowing, which causes airflow obstruction. Both inflammation and bronchoconstriction contribute to airway narrowing. The pathogenesis of airway inflammation in asthma and the natural history of the disease are the subject of intense research and study in many countries of the world. The mechanisms of airway inflammation are only partially understood but are the basis for the devastating symptoms that affect the quality of life of millions of people. Treatment of asthma is directed at decreasing airway inflammation to gain long-term control of the disease.

Repeated intratracheal challenge with particulate antigen modulates murine lung cytokines

When lungs of experimental animals are repeatedly challenged with Ag, pulmonary inflammation wanes via unknown mechanisms. We hypothesized that changes in the balance of lung cytokines are responsible for immune down-regulation to repeated Ag challenge. We used intratracheal (IT) challenge of primed C57BL/6 mice with SRBC and on various days after single (1IT) or triple (3IT) challenge counted lung inflammatory cells and measured whole-lung cytokine mRNA and protein concentrations using RT-PCR and ELISA. We found that lung lymphocyte numbers and parenchymal lung inflammation decreased significantly at days 6 and 9 after final Ag challenge in 3IT mice compared with 1IT mice. Lungs of 3IT mice showed the following changes in relative mRNA expression: an earlier peak in IL-10, decreased IL-1beta, and a change from a Th2 response in 1IT mice to a Th1 response in 3IT mice (with pronounced increases in IL-12, IL-18, and IFN-gamma and decreased IL-4, IL-13, and IL-5). Similar types of changes were seen in whole-lung protein concentrations for TNF-alpha, IL-10, IL-12 p40, IFN-gamma, and IL-4. Additionally, mRNA expression of the endothelial selectins CD62E and CD62P decreased and lung lymphocyte apoptosis increased in the 3IT group. Thus, physiologic down-regulation of the pulmonary immune response to repeated Ag exposure is characterized by increased anti- and decreased proinflammatory cytokines that accompanies Th1 polarization. Similar mechanisms may act to minimize chronic lung inflammation in the majority of normal humans who do not develop progressive lung pathology when repeatedly exposed to inhaled or aspirated environmental Ags.

Antibody responses, cytokine levels and protection of mice immunised with HSV-2 antigens formulated into NISV or ISCOM delivery systems

The immunogenicity of a type 2 herpes simplex virus (HSV-2) antigen preparation following its formulation into immunostimulating complexes (ISCOMs) or non-ionic surfactant vesicles (NISV) was investigated in a murine model. The immune responses induced by each formulation were characterised by antigen specific total and subclass serum responses, and by lymphocyte proliferation and cytokine (interleukin-2 (IL-2), interleukin-4 (IL-4) and interferon-gamma (IFN-gamma)) production by in vitro restimulated spleen cells. The degree of protection afforded to mice by these various HSV-2 vaccine preparations against homologous (HSV-2) and heterologous (HSV-1) challenge infection was also determined. The findings suggest that formulation of the HSV-2 glycoprotein antigens with ISCOM or NISV delivery vehicles, and the methods used to prepare these formulations, influenced the immunogenicity of the final preparation. Higher IgG2a and neutralising antibody levels, IL-2 and IFN-gamma levels and lymphoproliferative responses were noted in mice immunised with the HSV-2 ISCOM formulated vaccine preparation. Furthermore, although HSV-2 antigens formulated in dehydration-rehydration NISV, or entrapped in NISV by freeze-thawing at 30 degrees C (HSV-2 NISV 30), also elicited relatively high antibody, IL-2 and IFN-gamma levels and relatively high lymphoproliferative responses, formulation of HSV-2 antigens by freeze-thawing with NISV at 60 degrees C (HSV-2 NISV 60) did not. There were no differences between any of the HSV-2 vaccine formulations in terms of IL-4 induction in in vitro stimulated spleen cell cultures. Almost complete protection against HSV-2 challenge was afforded by the HSV-2 ISCOM preparation, while partial protection against challenge infection was afforded by the HSV-2 NISV 30 vaccine formulation. The findings are discussed in relation to the nature of the immune mechanisms, particularly Th1- or Th2-like responses, that may be elicited by HSV-2 antigen preparations formulated into various delivery systems and the relevance of these immune responses to protection against HSV infection in the murine model.