Aspergillus fumigatus antigen induced eosinophilia in mice is abrogated by anti-IL-5 antibody

Successful treatment with mepolizumab in a case of allergic bronchopulmonary aspergillosis complicated with nontuberculous mycobacterial infection

Allergic bronchopulmonary aspergillosis (ABPA) is a complex hypersensitivity reaction that is associated with an allergic immunological response to Aspergillus species via Th2-related inflammation. The long-term use of a systemic corticosteroid is often needed for the treatment of ABPA. However, systemic corticosteroid treatment imposes a risk of the onset of a nontuberculous mycobacterial infection. Here we report the case of a patient with ABPA who required the long-term use of an oral corticosteroid because her repeated asthmatic attacks were successfully treated with mepolizumab, an anti-interleukin-5 monoclonal antibody. The patient, a 60-year-old Japanese female, had been treated with an oral corticoid and itraconazole. Despite the success of the initial treatment for ABPA, it was difficult to discontinue the use of the oral corticosteroid. In addition, Mycobacterium avium was detected from her bronchial lavage. We initiated mepolizumab treatment to taper the amount of corticosteroid and control the asthma condition. The patient's number of blood eosinophils, serum IgE level, fractional exhaled nitric oxide level, dosage of oral prednisolone, and need for inhaled budesonide/formoterol all improved, without an exacerbation of her asthma attacks. Although further research regarding mepolizumab treatment is needed, we believe that mepolizumab could be considered one of the agents for treating refractory ABPA.

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.

Role of eosinophils and their clinical significance in allergic inflammation

Eosinophils are believed to play roles in the pathophysiology of allergic inflammation, such as bronchial asthma. However, recent studies on anti-interleukin-5 monoclonal antibody treatment of asthmatic patients raised the possibility that eosinophils may play only a limited role. More recent studies established that eosinophils are essentially involved in the development of airway remodeling. Moreover, it is theoretically conceivable that eosinophils are a cellular source of lipid mediators, such as cysteinyl leukotrienes or platelet-activating factor in asthma. Even in the absence of interleukin-5, it is likely that the 'T-helper Type 2 network', including a cascade of vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, CC chemokines, granulocyte-macrophage colony-stimulating factor, for example, can maintain sufficient eosinophilic infiltration and effector functions, such as superoxide anion generation and degranulation. Long-term studies, wherein tissue eosinophils are eliminated effectively will be required to establish the exact roles of these cells in asthma. Finally, the authors will demonstrate that eosinophils have the potential for not only playing detrimental roles but also beneficial ones.

Preventive and therapeutic anti-inflammatory properties of the sesquiterpene alpha-humulene in experimental airways allergic inflammation

BACKGROUND AND PURPOSE

alpha-Humulene and trans-caryophyllene are plant sesquiterpenes with pronounced anti-inflammatory properties. Here, we evaluated the effects of these compounds in an experimental model of airways allergic inflammation.

EXPERIMENTAL APPROACH

Female BALB/c mice, sensitized to and challenged with ovalbumin received daily alpha-humulene or trans-caryophyllene (50 mg.kg(-1), orally) or alpha-humulene (1 mg.mL(-1), by aerosol) as either a preventive (for 22 days) or therapeutic (from the 18th to the 22nd day) treatment. Dexamethasone or budesonide was used as a positive control drug. Inflammation was determined on day 22 post-immunization by leukocyte recruitment, interleukin-5 (IL-5), CCL11, interferon-gamma (IFN-gamma) and leukotriene (LT)B(4) levels in bronchoalveolar lavage fluid (BALF). In addition, transcription factors [nuclear factor kappaB (NF-kappaB), activator protein 1 (AP-1)] and P-selectin in lung tissue were measured by immunohistochemistry and mucus secretion by histochemistry.

KEY RESULTS

Preventive or therapeutic treatments with alpha-humulene, but not with trans-caryophyllene, significantly reduced the eosinophil recruitment to the BALF. In addition, alpha-humulene recovery INF-gamma and reduced the IL-5, CCL11 and LTB(4) levels in BALF, as well as the IL-5 production in mediastinal lymph nodes (in vitro assay). Furthermore, alpha-humulene decreased the NF-kB and the AP-1 activation, the expression of P-selectin and the increased mucus secretion in the lung.

CONCLUSIONS AND IMPLICATIONS

alpha-Humulene, given either orally or by aerosol, exhibited marked anti-inflammatory properties in a murine model of airways allergic inflammation, an effect that seemed to be mediated via reduction of inflammatory mediators, adhesion molecule expression and transcription factors activation.

Extravascular inflammation does not increase atherosclerosis in apoE-deficient mice

There is much speculation whether extravascular inflammation accelerates atherosclerosis. We tested this hypothesis in apoE(-/-) mice using three well-characterized models of non-autoimmune chronic inflammation: croton oil-induced skin inflammation, Aspergillus fumigatus antigen-induced allergic lung disease, and A. fumigatus antigen-induced peritonitis. The croton oil model produced recurrent inflammatory skin ulceration, and marked increases in plasma levels of IL-6 and serum amyloid A (SAA). The allergic lung disease model showed strong local inflammation with eosinophilic infiltration and serum IgE induction. The recurrent peritonitis model was accompanied by mild elevation in plasma SAA levels. Aortic atherosclerosis was quantified by computer-assisted morphometry of en face arteries in apoE(-/-) mice at 34 weeks for the croton oil model, 26 and 42 weeks for the allergic lung disease model, and 26 weeks for the peritonitis model. We found that all three forms of chronic extravascular inflammation had no effect on the rate of atherosclerosis development.

Modulation of eosinophil generation and migration by Mangifera indica L. extract (Vimang)

The effects of Vimang, an aqueous extract of the stem bark of Mangifera indica L. (Anacardiaceae), on cell migration in an experimental model of asthma was investigated. In vivo treatment of Toxocara canis-infected BALB/c mice for 18 days with 50 mg/kg Vimang reduced eosinophil migration into the bronchoalveolar space and peritoneal cavity. Also, eosinophil generation in bone marrow and blood eosinophilia were inhibited in infected mice treated with Vimang. This reduction was associated with inhibition of IL-5 production in serum and eotaxin in lung homogenates. In all these cases the effects of Vimang were more selective than those observed with dexamethasone. Moreover, Vimang treatment is not toxic for the animals, as demonstrated by the normal body weight increase during infection. These data confirm the potent anti-inflammatory effect of Vimang and support its potential use as an alternative therapeutic drug to the treatment of eosinophilic disorders including those caused by nematodes and allergic diseases.

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.

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.

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.

Elevated levels of thymus- and activation-regulated chemokine in bronchoalveolar lavage fluid from patients with eosinophilic pneumonia

Thymus- and activation-regulated chemokine (TARC/CCL17) is a lymphocyte-directed CC chemokine, which plays a role in the recruitment of CC chemokine receptor-4 positive T helper 2 (Th2) cells. In this study, we measured concentrations of TARC and Th2 cell-derived cytokines in bronchoalveolar lavage (BAL) fluid, as well as TARC concentrations in serum from patients with eosinophilic pneumonia and other interstitial lung diseases. TARC was significantly elevated in BAL fluids from patients with eosinophilic pneumonia (median, 240 pg/ml), whereas TARC was undetectable (< 7 pg/ml) in most cases of hypersensitivity pneumonitis, sarcoidosis, and idiopathic pulmonary fibrosis, as well as in healthy control subjects. Also, when present, quantities were less than 20 pg/ml. Elevated concentrations of interleukin (IL)-4, IL-5, and IL-13 were also detected in BAL fluid from patients with eosinophilic pneumonia. Interestingly, TARC concentrations in BAL fluids were closely correlated with the concentrations of IL-5 and IL-13. A serial examination showed that elevated TARC in BAL fluid rapidly fell to below detectable limits preceding decreases in IL-5 concentration and eosinophil percentage. Our results, in concordance with previous studies, demonstrate the potential activity of TARC for recruiting Th2 cells to the lungs and suggest a significant role for TARC in the pathogenesis of eosinophilic pneumonia.

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.

Enhanced pulmonary allergic responses to Aspergillus in CCR2-/- mice

Allergic responses to Aspergillus species exacerbate asthma and cystic fibrosis. The natural defense against live Aspergillus fumigatus spores or conidia depends on the recruitment and activation of mononuclear and polymorphonuclear leukocytes, events that are dependent on chemotactic cytokines. In this study, we explored the relative contribution of the monocyte chemoattractant protein-1 receptor, CCR2, in the pulmonary response to A. fumigatus conidia. Following sensitization to soluble A. fumigatus Ags, mice lacking CCR2 due to targeted deletion were markedly more susceptible to the injurious effects of an intrapulmonary challenge with live conidia compared with mice that expressed CCR2 or CCR2+/+. CCR2-/- mice exhibited a major defect in the recruitment of polymorphonuclear cells, but these mice also had significantly more eosinophils and lymphocytes in bronchoalveolar lavage samples. CCR2-/- mice also had significant increases in serum levels of total IgE and whole lung levels of IL-5, IL-13, eotaxin, and RANTES compared with CCR2+/+ mice. Airway inflammation, hyper-responsiveness to spasmogens, and subepithelial fibrosis were significantly enhanced in CCR2-/- mice compared with CCR2+/+ mice after the conidia challenge. Thus, these findings demonstrate that CCR2 plays an important role in the immune response against A. fumigatus, thereby limiting the allergic airway inflammatory and remodeling responses to this fungus.

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.

A murine model of allergic rhinitis: studies on the role of IgE in pathogenesis and analysis of the eosinophil influx elicited by allergen and eotaxin

BACKGROUND

Allergic rhinitis is a prevalent disease with significant morbidity. Studies of its pathophysiology in human subjects have been limited. Nasal biopsy specimens are difficult to obtain, and nasal secretions incompletely reflect the cellular and molecular events in the mucosa. IgE-mediated mast cell activation and the elaboration of factors promoting eosinophil development and chemotaxis are likely to participate in pathogenesis.

OBJECTIVES

We sought to develop a murine model of allergic rhinitis, to use it to assess the role of IgE in pathogenesis, and to study the effects of IL-5 and eotaxin in the nasal mucosa.

METHODS

A protein extract of Aspergillus fumigatus (Af) was instilled intranasally in mice. Histologic changes were examined in wild-type and IgE-deficient (IgE-/-) animals. The effect of eotaxin administration was assessed in wild-type and IL-5 transgenic mice.

RESULTS

Af-treated mice developed a nasal mucosal eosinophil influx comparable to that described for humans. This histology was distinct from that observed in a murine model of Af-induced asthma. The pathology appeared over a time course similar to that reported for human subjects. There was no difference in the intensity of the mucosal inflammatory infiltrate of Af-treated IgE-/- mice compared with wild-type mice. Eotaxin was able to recruit eosinophils to the mucosa but only in IL-5 transgenic animals.

CONCLUSION

We describe a murine model for allergic rhinitis with an eosinophilic infiltrate comparable to that found in human disease and have demonstrated that rhinitis can arise in the absence of IgE. We have shown that the eosinophil influx can be induced by eotaxin in the presence of IL-5.

IL-5 Is Required for Eosinophil Recruitment, Crystal Deposition, and Mononuclear Cell Recruitment During a Pulmonary Cryptococcus neoformans Infection in Genetically Susceptible Mice (C57BL/6)

CBA/J (highly resistant), BALB/c (moderately resistant), and C57BL/6 (susceptible) mice displayed three resistance patterns following intratracheal inoculation of Cryptococcus neoformans 52. The inability to clear the infection correlated with the duration of the eosinophil infiltrate in the lungs. The role of IL-5 in promoting the pulmonary eosinophilia and subsequent inflammatory damage in susceptible C57BL/6 mice was investigated. C57BL/6 mice developed a chronic alveolar, peribronchiolar, and perivascular eosinophilia following C. neoformans infection. This resulted in the accumulation of intracellular Charcot-Leyden-like crystals in alveolar macrophages by wk 4 and the extracellular deposition of these crystals in the bronchioles with associated destruction of airway epithelium by wk 6. IL-5 mRNA was expressed in the lungs, and injections of anti-IL-5 mAb prevented eosinophil recruitment and crystal deposition but did not alter cryptococcal clearance. Depletion of CD4+ T cells (but not CD8+) ablated IL-5 production by lung leukocytes in vitro and eosinophil recruitment in vivo. Neutralization of IL-5 also inhibited the recruitment of macrophages, CD8+ T lymphocytes, and B lymphocytes by 47 to 57%. Anti-IL-5 mAb inhibited CD4+ T lymphocyte recruitment by 30% but did not affect neutrophil recruitment. Thus, the development of a chronic eosinophil infiltrate in the lungs of C. neoformans-infected C57BL/6 mice is a nonprotective immune response that causes significant lung pathology. Furthermore, IL-5 promotes the recruitment and activation of eosinophils, resulting in the recruitment of additional macrophages and lymphocytes into the lungs.

Anti-interleukin (IL)-4 and -IL-5 antibodies downregulate IgE and eosinophilia in mice exposed to Aspergillus antigens

The effect of multiple divided doses compared with single-dose injections of antibodies to murine interleukin (IL)-4 and IL-5 in their respective downregulation of IgE and eosinophilia developing in a model of allergic aspergillosis is investigated. BALB/c mice were exposed to Aspergillus fumigatus antigens (Af) before and along with anticytokine antibodies. The kinetics of blood eosinophils, eosinophil peroxidase (EPO) in bone-marrow cells, serum levels of IgE and Af-specific antibodies, Af-induced cytokine production and mRNA, and lung histology were studied. The results indicate that only multiple anti-IL-5 antibodies were effective in maintaining baseline levels of blood eosinophils. Multiple anti-IL-4 antibodies also downregulated eosinophils in the bone marrow, lung, and peripheral blood, although to a lesser extent than in anti-IL-5 antibody-injected mice. Significant correlation between the EPO activity and the eosinophil numbers in anticytokine antibody-treated mice was observed. The different anti-IL-4 antibody treatments downregulated IgE to the same extent. We conclude that multiple divided doses of anti-IL-5 antibodies are required to sustain normal eosinophil levels in murine allergic aspergillosis. This information may be significant in the therapy of pulmonary allergic diseases.

Immunopathologic responses to Aspergillus antigen in interleukin-4 knockout mice

Two strains of interleukin-4 (IL-4) gene knockout mice were studied and compared with wild strains to determine the role of IL-4 in the immunopathogenesis of murine allergic aspergillosis. Animals immunized intraperitoneally were subsequently challenged with Aspergillus antigen intranasally. The animals were evaluated for total serum immunoglobulin E (IgE) levels, Aspergillus-specific IgG antibody isotypes, peripheral blood eosinophils, cytokine and chemokine mRNA transcripts in spleen cells, and pulmonary histology. No serum IgE was detected in animals deficient in the IL-4 gene. Aspergillus-specific IgG1 was detected in all animals, while enhanced levels of IgG2a were detected in IL-4 knockout animals challenged with A. fumigatus antigen. There were no differences in the peripheral blood or lung eosinophils in the two groups of mice exposed to A. fumigatus. These results indicate that lung injury in Aspergillus-antigen challenged animals may be the result of the eosinophil mediators and that IgE-mediated injury may not be significant in this model, which may be a significant variation between the model and human allergic aspergillosis.

Development of bone marrow eosinophilia in mice induced by Aspergillus fumigatus antigens

A model of allergic bronchopulmonary aspergillosis (ABPA) developed by exposing mice to Aspergillus fumigatus antigen (Af) exhibits peripheral blood (PB), lung, and bone marrow (BM) eosinophilia. Because the BM is a site of eosinophilopoiesis, we have investigated the role of Af in the induction of this process in the BM. Groups of mice were exposed intranasally (i.n.) or intraperitoneally (i.p.) to Af. BM cells from mice were cultured with either Af or allogenic spleen cell supernatant stimulated with Af. Eosinophil counts in different lymphoid compartments, eosinophil peroxidase (EPO), and mRNA for cytokines and IgE in BM cells were studied. Results indicate that the eosinophil numbers were significantly elevated in PB and BM of all Af-exposed mice. Lung lavage eosinophils increased only in the i.n. group. Af induced EPO activity only in BM cultures from Af-exposed mice. The EPO activity was further enhanced by supernatants from spleen cells from Af-exposed mice. mRNA transcription of IL-3 and IL-5 were measurable in BM cells of the ip exposed mice. These findings suggest that Af mediates eosinophil development in BM of mice and this process is promoted by hematopoietic factors generated within the BM and in other lymphoid tissue such as the spleen.

Inhibition of interleukin-5 with a monoclonal antibody attenuates allergic inflammation

IL-5 is a prominent and perhaps an essential element in the induction of allergic inflammation in human asthma and other allergic diseases. Despite the strong biochemical and clinical correlates between lung eosinophilia and asthma, there is no clear understanding of how eosinophils exacerbate asthma. Antigen administration to sensitized animals produces eosinophilic infiltration that is very similar to that in man, and is prevented by administration of a neutralizing monoclonal antibody against IL-5. Mice in which the IL-5 gene is absent are unable to mount eosinophilic responses to antigen and do not sustain lung damage, but otherwise develop normally. The study of the biology of IL-5 has not only clarified the links between eosinophilia and airway hyperreactivity, but also strongly suggests that anti-IL-5 therapy may be an effective, safe, and novel way of treating human asthma and perhaps other eosinophilic diseases. There are many different potential approaches to the inhibition of IL-5, but the one most likely to provide "proof of principle" in "asthma in the wild" in man is a monoclonal antibody against IL-5.

Detection of IL-5 and IL-1 receptor antagonist in bronchoalveolar lavage fluid in acute eosinophilic pneumonia

BACKGROUND

Acute eosinophilic pneumonia is an idiopathic cause of respiratory failure, characterized by very high numbers of alveolar eosinophils without significant blood eosinophilia.

OBJECTIVE

The purpose of this study was to determine which cytokines are associated with acute eosinophilic pneumonia.

METHODS

Soluble IL-1 type II receptor and the cytokines IL-1 beta, IL-1ra, IL-3, IL-5, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor-alpha were measured in serum and in bronchoalveolar lavage fluid from two patients with acute eosinophilic pneumonia during both acute and convalescent phases.

RESULTS

Compared with patients with adult respiratory distress syndrome, the patients with acute eosinophilic pneumonia had high bronchoalveolar lavage fluid levels of IL-5, IL-1ra, and soluble type II IL-1 receptor but not IL-1 beta, tumor necrosis factor-alpha, IL-3, or granulocyte-macrophage colony-stimulating factor. Bronchoalveolar lavage fluid levels of IL-5 and IL-1ra fell after resolution of symptoms. In the serum of patients with acute eosinophilic pneumonia, IL-5 was not detectable, and IL-1ra was initially high but fell after corticosteroid treatment.

CONCLUSION

Acute eosinophilic pneumonia is characterized by locally high levels of IL-5, IL-1ra, and soluble type II IL-1 receptor in the alveolar space.

Immunohistochemical detection of GM-CSF, IL-4 and IL-5 in a murine model of allergic bronchopulmonary aspergillosis

BACKGROUND

Granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin-4 (IL-4) and IL-5 are important in tissue eosinophil accumulation and high IgE production in allergic inflammatory reaction.

OBJECTIVE

We examine lung GM-CSF, IL-4 and IL-5 expression in a murine model of allergic bronchopulmonary aspergillosis (ABPA) characterized by eosinophil and lymphocyte lung infiltration and elevated serum IgE level.

METHODS

C57BL/6 mice were intranasally treated three times a week for 1, 2 or 3 week(s) with Aspergillus fumigatus (Af) antigen or saline and were sacrificed on days 7, 14 and 21. Immunohistochemical analyses for GM-CSF, IL-4 and IL-5 were performed on lung sections.

RESULTS

Af treatment induced a remarkable pulmonary eosinophil influx. Increased numbers of lung T lymphocytes and GM-CSF positive cells were observed on days 14 and 21. IL-4 and IL-5 positive cells were increased significantly only on day 14. Immunostained serial sections showed that most (> or = 98%) cytokine positive cells were CD3 positive. Few eosinophils (< 2% of cytokine positive cells) were immunoreactive for GM-CSF and IL-5. Significant correlations were found between the number of GM-CSF and IL-5 positive cells, and the number of eosinophils in Af-treated lung (r = 0.62, P < 0.05 and r = 0.52, P < 0.05 respectively), and between the number of IL-4 positive cells and the serum total IgE level (r = 0.64, P < 0.01).

CONCLUSIONS

Our data suggest a role for T lymphocyte GM-CSF, IL-4 and IL-5 in Af-induced mouse pulmonary eosinophilia and increased serum IgE production and further support the importance of T helper (TH2) cells in the pathogenesis of ABPA.

Increased expression of intercellular adhesion molecule-1 (ICAM-1) in a murine model of pulmonary eosinophilia and high IgE level

T lymphocytes and eosinophils are probably involved in the pathogenesis of allergic bronchopulmonary aspergillosis (ABPA), a disease characterized by pulmonary eosinophilia and high serum and lavage IgE levels. We recently developed a murine model of ABPA. To investigate the mechanisms of T lymphocyte and eosinophil recruitment to the lung in this disease, we examined the expression of ICAM-1 in the lung tissue of mouse challenged with Aspergillus fumigatus (Af) antigen. C57B1/6 mice were intranasally exposed to Af (Af group) or saline (control group) three times a week for 1, 2 or 3 weeks. On days 4, 7, 14 and 21, mice were killed and lung tissue was fixed in acetone and embedded in glycol methacrylate. Serial 2-microns sections were stained with chromotrope 2R and MoAbs against ICAM-1, CD11a/CD18 (LFA-1) and CD3. Af-challenged mice presented significant increases in eosinophil, T lymphocyte and LFA-1-positive cell count and up-regulated expression of ICAM-1 in the lung tissue at all the time points examined. ICAM-1 expression intensity correlated with the number of T lymphocytes (r = 0.59, P < 0.01), LFA-1-positive cells (r = 0.68, P < 0.001), but not of eosinophils (r = -0.24, P > 0.05). These findings suggest that up-regulation of ICAM-1 expression is involved in the inflammatory process of this murine model of ABPA, and that this up-regulation may be more relevant to the the T lymphocyte accumulation in the lung.