Novel acute hypersensitivity pneumonitis model induced by airway mycosis and high dose lipopolysaccharide

BACKGROUND

Inhalation of fungal spores is a strong risk factor for severe asthma and experimentally leads to development of airway mycosis and asthma-like disease in mice. However, in addition to fungal spores, humans are simultaneously exposed to other inflammatory agents such as lipopolysaccharide (LPS), with uncertain relevance to disease expression. To determine how high dose inhalation of LPS influences the expression of allergic airway disease induced by the allergenic mold Aspergillus niger (A. niger).

METHODS

C57BL/6J mice were intranasally challenged with the viable spores of A. niger with and without 1 μg of LPS over two weeks. Changes in airway hyperreactivity, airway and lung inflammatory cell recruitment, antigen-specific immunoglobulins, and histopathology were determined.

RESULTS

In comparison to mice challenged only with A. niger, addition of LPS (1 μg) to A. niger abrogated airway hyperresponsiveness and strongly attenuated airway eosinophilia, PAS+ goblet cells and TH2 responses while enhancing TH1 and TH17 cell recruitment to lung. Addition of LPS resulted in more severe, diffuse lung inflammation with scattered, loosely-formed parenchymal granulomas, but failed to alter fungus-induced IgE and IgG antibodies.

CONCLUSIONS

In contrast to the strongly allergic lung phenotype induced by fungal spores alone, addition of a relatively high dose of LPS abrogates asthma-like features, replacing them with a phenotype more consistent with acute hypersensitivity pneumonitis (HP). These findings extend the already established link between airway mycosis and asthma to HP and describe a robust model for further dissecting the pathophysiology of HP.

Microbial characteristics in homes of asthmatic and non-asthmatic adults in the ECRHS cohort

Microbial exposures in homes of asthmatic adults have been rarely investigated; specificities and implications for respiratory health are not well understood. The objectives of this study were to investigate associations of microbial levels with asthma status, asthma symptoms, bronchial hyperresponsiveness (BHR), and atopy. Mattress dust samples of 199 asthmatics and 198 control subjects from 7 European countries participating in the European Community Respiratory Health Survey II study were analyzed for fungal and bacterial cell wall components and individual taxa. We observed trends for protective associations of higher levels of mostly bacterial markers. Increased levels of muramic acid, a cell wall component predominant in Gram-positive bacteria, tended to be inversely associated with asthma (OR's for different quartiles: II 0.71 [0.39-1.30], III 0.44 [0.23-0.82], and IV 0.60 [0.31-1.18] P for trend .07) and with asthma score (P for trend .06) and with atopy (P for trend .02). These associations were more pronounced in northern Europe. This study among adults across Europe supports a potential protective effect of Gram-positive bacteria in mattress dust and points out that this may be more pronounced in areas where microbial exposure levels are generally lower.

Immunomodulatory effects of Escherichia coli ATCC 25922 on allergic airway inflammation in a mouse model

Background

Hygiene hypothesis demonstrates that the lack of microbial exposure would promote the development of allergic airway disease (AAD). Therefore, the gut microbiota, including Escherichia coli (E. coli), would probably offer a potential strategy for AAD.

Objective

To investigate whether E. coli infection is able to suppress the induction of AAD and to elucidate the underlying mechanisms.

Methods

Nonpathogenic E. coli ATCC 25922 was infected by gavage before AAD phase in three patterns: 10⁸ or 10⁶ CFU in neonates or 10⁸ CFU in adults. Then mice were sensitized and challenged with ovalbumin (OVA) to induce allergic inflammation in both the upper and lower airways. Hallmarks of AAD, in terms of eosinophil infiltration and goblet cell metaplasia in subepithelial mucosa, Th2 skewing of the immune response, and levels of T regulate cells (Tregs), were examined by histological analysis, ELISA, and flow cytometry, respectively.

Results

E. coli, especially neonatally infected with an optimal dose, attenuated allergic responses, including a decrease in nasal rubbing and sneezing, a reduction in eosinophil inflammation and goblet cell metaplasia in subepithelial mucosa, decreased serum levels of OVA-specific IgE, and reduced Th2 (IL-4) cytokines. In contrast, this effect came with an increase of Th1 (IFN-r and IL-2) cytokines, and an enhancement of IL-10-secreting Tregs in paratracheal lymph nodes (PTLN).

Conclusion

E. coli suppresses allergic responses in mice, probably via a shift from Th1 to Th2 and/or induction of Tregs. Moreover, this infection is age- and dose-dependent, which may open up novel possibilities for new therapeutic interventions.

An inactivated Pseudomonas aeruginosa medicament inhibits airway allergic inflammation and improves epithelial functions

The features of asthma are airway hyperresponsiveness (AHR), excess production of Th2 cytokines, and eosinophil accumulation in the lungs. To investigate the antiasthmatic potential of an inactivated Pseudomonas aeruginosa medicament (PPA), as well as the underlying mechanism involved, we studied the effects of PPA on airway and epithelial functions. Airway resistance, cell enumeration, and IL-4, IFN-γ, and IL-17 secretion in bronchoalveolar lavage fluid were assayed on an OVA-sensitized AHR animal model. Flow cytometry was used to observe the effects of PPA on cell proliferation, real-time PCR was used to test the expressions of toll like receptor 4 and 5, and Th17 signal molecules Act1, NF-kB negative regulator A20, and western blot were used to detect NF-kB expression on cultured human bronchial epithelial cells (BECs). PPA-treated animals had suppressed airway resistance, eosinophil and lymphocytes infiltration, and IL-4 and IL-17 secretion. PPA can stimulate toll-like receptor-4 and 5 expressions, promote cell proliferation in normal and OVA-treated BECs, significantly decrease Act1 and NF-kB, and increase A20 expression in BECs treated by OVA. Our data suggest the therapeutic mechanism by which PPA effectively treats allergic inflammation on reductions of airway responsiveness, eosinophil infiltration, IL-4 and IL-17 secretion, and improvements of epithelial functions.

Pneumocystis elicits a STAT6-dependent, strain-specific innate immune response and airway hyperresponsiveness

It is widely held that exposure to pathogens such as fungi can be an agent of comorbidity, such as exacerbation of asthma or chronic obstructive pulmonary disease. Although many studies have examined allergic responses to fungi and their effects on pulmonary function, the possible pathologic implications of the early innate responses to fungal pathogens have not been explored. We examined early responses to the atypical fungus Pneumocystis in two common strains of mice in terms of overall immunological response and related pathology, such as cell damage and airway hyperresponsiveness (AHR). We found a strong strain-specific response in BALB/c mice that included recruitment of neutrophils, NK, NKT, and CD4 T cells. This response was accompanied by elevated indicators of lung damage (bronchoalveolar lavage fluid albumin and LDH) and profound AHR. This early response was absent in C57BL/6 mice, although both strains exhibited a later response associated with the clearance of Pneumocystis. We found that this AHR could not be attributed exclusively to the presence of recruited neutrophils, NKT, NK, or CD4 cells or to the actions of IFN-γ or IL-4. However, in the absence of STAT6 signaling, AHR and inflammatory cell recruitment were virtually absent. Gene expression analysis indicated that this early response included activation of several transcription factors that could be involved in pulmonary remodeling. These results show that exposure to a fungus such as Pneumocystis can elicit pulmonary responses that may contribute to morbidity, even without prior sensitization, in the context of certain genetic backgrounds.

Early-life chlamydial lung infection enhances allergic airways disease through age-dependent differences in immunopathology

BACKGROUND

Asthma typically originates in early-life, and the impact of infection during immunologic maturation is a critical factor in disease pathogenesis. The progression of aberrant T(H)2 cell responses and disease development has been attributed to a lack of infections. However, exposure to specific pathogens such as Chlamydia may alter immunologic programming and predispose to asthma.

OBJECTIVE

To investigate the effects of chlamydial infection at different ages on allergic airways disease in later life.

METHODS

Neonatal, infant, or adult BALB/c mice were infected and 6 weeks later were sensitized and subsequently challenged with ovalbumin. Hallmark features of allergic airways disease were compared with uninfected allergic and nonallergic controls.

RESULTS

Early-life (neonatal and infant) but not adult chlamydial infection enhanced the development of hallmark features of asthma in ovalbumin-induced allergic airways disease. Notably early-life infection increased mucus-secreting cell numbers, IL-13 expression, and airway hyperresponsiveness. Neonatal infection attenuated eosinophil influx and ovalbumin-specific T(H)2 cytokine release and numbers of activated myeloid dendritic cells (DCs) in lymph nodes. By contrast, infant infection augmented features of allergic inflammation with increased airway eosinophils, T(H)2 cytokine, and DC responses. Both neonatal and infant infection increased systemic DC-induced IL-13 release from CD4(+) T cells. The timing of infection had significant effects on lung structure because neonatal but not infant or adult infection induced increases in alveolar diameter.

CONCLUSION

Early-life respiratory chlamydial infections modulate immune responses, alter lung function and structure, and enhance the severity of allergic airways disease in later life.

Asthma, bronchial hyper-responsiveness and Chlamydophila (Chlamydia) pneumonia infection in adult Thai population

BACKGROUND

The associations between Chlamydophila (Chlamydia) pneumonia infection and chronic asthma or bronchial hyper-responsiveness (BHR) have been inconclusive.

OBJECTIVE

We aimed to determine the association between C. pneumonia infection and asthma as well as BHR in the adult Thai population.

MATERIAL AND METHOD

This nested case-control study retrieved the data from a nation-wide Respiratory Health Survey (2001-02) in the adult population (age 20-44 year) in Thailand. Each subject underwent questionnaire interview, spirometry, bronchoprovocative test, skin prick test for common aeroallergens and venous blood collection. Subjects with BHR (n = 79) including those with asthma (n = 52), were randomly selected as cases. Subjects without BHR or asthma were also randomly selected as the control (n = 137). We used the stored serums for the C. pneumonia serologic assay including IgA, IgG and IgM by microimmunofluorescence (MIF) technique.

RESULTS

There is no significant relationship between chronic Chlamydia infection (IgG > or = 1:512 and IgA > or = 1:40) and BHR or asthma. Higher IgM was found in subjects with BHR when compared with the control group (p = 0.04). The IgM titer > or = 1:10 was associated with BHR with borderline significance (odds ratio 1.98; 95% CI 0.98-4.00; p = 0.05). Logistic regression analysis revealed no evidence of confounding effects for age, sex and atopy. However mite allergy seems to be an effect modifier of the relationship between the recent Chlamydia infection and BHR.

CONCLUSION

The present study does not support the hypothesis about the association between persistent C. pneumonia infection and chronic asthma. However the recent infection may be related with bronchial hyper-responsiveness particularly in those without allergy to house dust mite.

T-bet deficiency facilitates airway colonization by Mycoplasma pulmonis in a murine model of asthma

Epidemiological and clinical evidence suggest a correlation between asthma and infection with atypical bacterial respiratory pathogens. However, the cellular and molecular underpinnings of this correlation remain unclear. Using the T-bet-deficient (T-bet(-/-)) murine model of asthma and the natural murine pathogen Mycoplasma pulmonis, we provide a mechanistic explanation for this correlation. In this study, we demonstrate the capacity of asthmatic airways to facilitate colonization by M. pulmonis and the capacity of M. pulmonis to exacerbate symptoms associated with acute and chronic asthma. This mutual synergism results from an inability of T-bet(-/-) mice to mount an effective immune defense against respiratory infection through release of IFN-gamma and the ability of M. pulmonis to trigger the production of Th2-type cytokines (e.g., IL-4 and IL-5), and Abs (e.g., IgG1, IgE, and IgA), eosinophilia, airway remodeling, and hyperresponsiveness; all pathophysiological hallmarks of asthma. The capacity of respiratory pathogens such as Mycoplasma spp. to dramatically augment the pathological changes associated with asthma likely explains their association with acute asthmatic episodes in juvenile patients and with adult chronic asthmatics, >50% of whom are found to be PCR positive for M. pneumoniae. In conclusion, our study demonstrates that in mice genetically predisposed to asthma, M. pulmonis infection elicits an inflammatory milieu in the lungs that skews the immune response toward the Th2-type, thus exacerbating the pathophysiological changes associated with asthma. For its part, airways exhibiting an asthmatic phenotype provide a fertile environment that promotes colonization by Mycoplasma spp. and one which is ill-equipped to kill and clear respiratory pathogens.

[Could Legionella pneumophila infection cause bronchial hyperreactivity]

11 children with bronchial hyperreactivity were tested for Legionella pneumophila serotype 1 and 2-14, including 3 girls, who were treated a year before because of atypical pneumonia, probably caused by Legionella pneumophila, 2 brothers of the girls and 6 children from a different village as well as 5 adults--parents of the girls. In all of them a significant level of antibodies against Legionella pneumophila serotype 2-14 was detected with indirect immunofluorescence. One of previously treated girls presented with increased level of IgG antibodies (ELISA), the remaining two had increased levels of IgA against Legionella pneumophila serotype 1. Other patients in the group presented no IgM, IgA or IgG against Legionella pneumophila serotype 1. Patients with bronchial hypersensitivity received clarithromycin and inhalation steroids with good clinical effect.

Effect of microbial heat shock proteins on airway inflammation and hyperresponsiveness

Microbial heat shock proteins (hsp) have been associated with the generation and induction of Th1-type immune responses. We tested the effects of treatment with five different microbial hsp (Mycobacterium leprae, Streptococcus pneumoniae, Helicobacter pylori, bacillus Calmette-Guérin, and Mycobacterium tuberculosis) in a murine model of allergic airway inflammation and airway hyperresponsiveness (AHR). Mice were sensitized to OVA by i.p. injection and then challenged by OVA inhalation. Hsp were administered to each group by i.p. injection before sensitization and challenge. Sensitized and challenged mice developed increased serum levels of OVA-specific IgE with significant airway eosinophilia and heightened responsiveness to methacholine when compared with nonsensitized animals. Administration of M. leprae hsp prevented both development of AHR as well as bronchoalveolar lavage fluid eosinophilia in a dose-dependent manner. Treatment with M. leprae hsp also resulted in suppression of IL-4 and IL-5 production in bronchoalveolar lavage fluid, while IL-10 and IFN-gamma production were increased. Furthermore, M. leprae hsp treatment significantly suppressed OVA-specific IgE production and goblet cell hyperplasia/mucin hyperproduction. In contrast, treatment with the other hsp failed to prevent changes in airway responsiveness, lung eosinophilia, or cytokine production. Depletion of gamma/delta T lymphocytes before sensitization and challenge abolished the effect of M. leprae hsp treatment on AHR. These results indicate selective and distinctive properties among the hsp, and that M. leprae hsp may have a potential therapeutic role in the treatment of allergic airway inflammation and altered airway function.

Chlamydia pneumoniae immunoglobulin A reactivation and airway inflammation in acute asthma

Infection with Chlamydia pneumoniae can trigger acute asthma and is associated with severe chronic asthma. The aim of the present study was to examine the relationship between airway inflammation and serological response to C. pneumoniae in acute severe asthma. Subjects (n=54) were recruited within 4 h of presentation to the emergency department with an acute exacerbation of asthma. Clinical history taking, sputum induction (0.9% saline), spirometry and acute and convalescent serology for C. pneumoniae immunoglobulins A and G were performed. At presentation, 47% of subjects had antibodies directed against C. pneumoniae, and 38% (20) demonstrated an increase in C. pneumoniae antibody levels, with 15 demonstrating a rise in immunoglobulin A concentration. C. pneumoniae responders exhibited significantly higher sputum neutrophil levels (4.6 x 10(6) cells x mL(-1)) compared to nonresponders (1.2 x 10(6) cells x mL(-1), p=0.02) and elevated sputum eosinophil cationic protein concentration (3,981 versus 1,122 ng x mL(-1), p=0.02). An acute antibody response to Chlamydia pneumoniae is common in exacerbations of asthma. The serological features suggest that Chlamydia pneumoniae reactivation may trigger neutrophilic airway inflammation in acute asthma.

Airway hyperresponsiveness, but not airway remodeling, is attenuated during chronic pulmonary allergic responses to Aspergillus in CCR4-/- mice

The role of CC chemokine receptor 4 (CCR4) during the development and maintenance of Th2-type allergic airway disease is controversial. In this study, we examined the role of CCR4 in the chronic allergic airway response to live Aspergillus fumigatus spores, or conidia, in A. fumigatus-sensitized mice. After the conidia challenge, mice lacking CCR4 (CCR4-/- mice) exhibited significantly increased numbers of airway neutrophils and macrophages, and conidia were more rapidly eliminated from these mice compared with control CCR4 wild-type (CCR4+/+) mice. Significant airway hyperresponsiveness to intravenous methacholine was observed at day 3 in CCR4-/- mice, whereas at days 7 and 30, airway hyperresponsiveness was attenuated in these mice compared with control mice. A major reduction in peribronchial and airway eosinophilia was observed in CCR4-/- mice at all times after conidia challenge in contrast to CCR4+/+ mice. Further, whole lung levels of interleukin (IL) 4 and IL-5 were significantly increased in CCR4-/- mice at day 3, whereas these Th2 cytokines and IL-13 were significantly decreased at day 30 in CCR4-/- mice compared with their wild-type counterparts. Peribronchial fibrosis and goblet cell hyperplasia were similar in both groups of mice throughout the course of this model. In summary, CCR4 modulates both innate and acquired immune responses associated with chronic fungal asthma.

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.

Mycoplasma pneumoniae induces chronic respiratory infection, airway hyperreactivity, and pulmonary inflammation: a murine model of infection-associated chronic reactive airway disease

Because chronic Mycoplasma pneumoniae respiratory infection is hypothesized to play a role in asthma, the potential of M. pneumoniae to establish chronic respiratory infection with associated pulmonary disease was investigated in a murine model. BALB/c mice were intranasally inoculated once with M. pneumoniae and examined at 109, 150, 245, 368, and 530 days postinoculation. M. pneumoniae was detected in bronchoalveolar lavage fluid by culture or PCR in 70 and 22% of mice at 109 and 530 days postinoculation, respectively. Lung histopathology was normal up to 368 days postinoculation. At 530 days, however, 78% of the mice inoculated with M. pneumoniae demonstrated abnormal histopathology characterized by peribronchial and perivascular mononuclear infiltrates. A mean histopathologic score (HPS) at 530 days of 5.1 was significantly greater (P < 0.01) than that for controls (HPS score of 0). Serum anti-M. pneumoniae immunoglobulin G was detectable in all of the mice inoculated with M. pneumoniae and was inversely correlated with HPS (r = -0.95, P = 0.01) at 530 days postinoculation. Unrestrained whole-body plethysmography measurement of enhanced pause revealed significantly elevated airway methacholine reactivity in M. pneumoniae-inoculated mice compared with that in controls at 245 days (P = 0.03) and increased airway obstruction at 530 days (P = 0.01). Murine M. pneumoniae respiratory infection can lead to chronic pulmonary disease characterized by airway hyperreactivity, airway obstruction, and histologic inflammation.

CXCR2 is necessary for the development and persistence of chronic fungal asthma in mice

The role of CXCR during allergic airway and asthmatic diseases is yet to be fully characterized. Therefore, the present study addressed the role of CXCR2 during Aspergillus fumigatus-induced asthma. Mice deficient in CXCR2 (CXCR2-/-) and wild-type counterparts (CXCR2+/+) were sensitized to A. fumigatus Ags and challenged with A. fumigatus conidia, and the resulting allergic airway disease was monitored for up to 37 days. At days 3 and 7 after conidia, CXCR2-/- mice exhibited significantly greater methacholine-induced airway hyperreactivity than did CXCR2+/+ mice. In contrast, CXCR2-deficient mice exhibited significantly less airway hyperresponsiveness than the wild-type control groups at days 14 and 37 after conidia. At all times after conidia, whole lung levels of IL-4, IL-5, and eotaxin/CC chemokine ligand 11 were significantly lower in CXCR2-/- mice than in the wild-type controls. Eosinophil and T cell, but not neutrophil, recruitment into the airways of A. fumigatus-sensitized CXCR2-/- mice was significantly impaired compared with wild-type controls at all times after the conidia challenge. Whole lung levels of IFN-gamma, inflammatory protein-10/CXC ligand (CXCL) 10, and monokine induced by IFN-gamma (MIG)/CXCL9 were significantly increased in CXCR2-/- mice compared with CXCR2+/+ mice at various times after conidia. Interestingly, at day 3 after conidia, neutrophil recruitment and airway hyperresponsiveness in CXCR2-/- mice was mediated by inflammatory protein-10/CXCL10 and, to a lesser degree, MIG/CXCL9. Taken together, these data suggest that CXCR2 contributes to the persistence of asthmatic disease due to A. fumigatus.

Antifungal and airway remodeling roles for murine monocyte chemoattractant protein-1/CCL2 during pulmonary exposure to Asperigillus fumigatus conidia

Asperigillus fumigatus spores or conidia are quickly eliminated from the airways of nonsensitized individuals but persist in individuals with allergic pulmonary responsiveness to fungus. A. fumigatus-induced allergic airway disease is characterized by persistent airway hyperreactivity, inflammation, and fibrosis. The present study explored the role of CCR2 ligands in the murine airway response to A. fumigatus conidia. Nonsensitized and A. fumigatus-sensitized CBA/J mice received an intratracheal challenge of A. fumigatus conidia, and pulmonary changes were analyzed at various times after conidia. Whole lung levels of monocyte chemoattractant protein-1 (MCP-1/CCL2), but neither MCP-3/CCL7 nor MCP-5/CCL12, were significantly elevated at days 3 and 7 after conidia in nonsensitized mice. MCP-1/CCL2 was significantly increased in lung samples from A. fumigatus-sensitized mice at days 14 and 30 after a conidia challenge. Administration of anti-MCP-1/CCL2 antiserum to nonsensitized mice for14 days after the conidia challenge attenuated the clearance of conidia and significantly increased airway hyperreactivity, eosinophilia, and peribronchial fibrosis compared with nonsensitized mice that received conidia and normal serum. Adenovirus-directed overexpression of MCP-1/CCL2 in A. fumigatus-sensitized mice markedly reduced the number of conidia, airway inflammation, and airway hyperresponsiveness at day 7 after the conidia challenge in these mice. Immunoneutralization of MCP-1/CCL2 levels in A. fumigatus-sensitized mice during days14-30 after the conidia challenge did not affect the conidia burden but significantly reduced airway hyperreactivity, lung IL-4 levels, and lymphocyte recruitment into the airways compared with the control group. These data suggest that MCP-1/CCL2 participates in the pulmonary antifungal and allergic responses to A. fumigatus conidia.

Airway remodeling is absent in CCR1-/- mice during chronic fungal allergic airway disease

Asthmatic-like reactions characterized by elevated IgE, Th2 cytokines, C-C chemokines, eosinophilic inflammation, and persistent airway hyperresponsiveness follow pulmonary exposure to the spores or conidia from Aspergillus fumigatus fungus in sensitized individuals. In addition to these features, subepithelial fibrosis and goblet cell hyperplasia characterizes fungal-induced allergic airway disease in mice. Because lung concentrations of macrophage inflammatory protein-1alpha and RANTES were significantly elevated after A. fumigatus-sensitized mice received an intrapulmonary challenge with A. fumigatus spores or conidia, the present study addressed the role of their receptor, C-C chemokine receptor 1 (CCR1), in this model. A. fumigatus-sensitized CCR1 wild-type (+/+) and CCR1 knockout (-/-) mice exhibited similar increases in serum IgE and polymorphonuclear leukocyte numbers in the bronchoalveolar lavage. Airway hyperresponsiveness was prominent in both groups of mice at 30 days after an intrapulmonary challenge with A. fumigatus spores or conidia. However, whole lung levels of IFN-gamma were significantly higher whereas IL-4, IL-13, and Th2-inducible chemokines such as C10, eotaxin, and macrophage-derived chemokine were significantly lower in whole lung samples from CCR1-/- mice compared with CCR1+/+ mice at 30 days after the conidia challenge. Likewise, significantly fewer goblet cells and less subepithelial fibrosis were observed around large airways in CCR1-/- mice at the same time after the conidia challenge. Thus, these findings demonstrate that CCR1 is a major contributor to the airway remodeling responses that arise from A. fumigatus-induced allergic airway disease.

Bronchial mucoid impaction due to the monokaryotic mycelium of Schizophyllum commune

We report, to our knowledge, the first case of mucoid impaction of the bronchi due to a hypersensitivity reaction to the monokaryotic mycelium of Schizophyllum commune. The patient was hospitalized because of mild asthma attacks, persistent cough, peripheral eosinophilia, and "gloved finger" shadows on a chest roentgenogram. Bronchoscopic examination disclosed mucoid impactions that consisted of accumulations of eosinophils, Charcot-Leyden crystals, and nondichotomously branched hyphae in B3, B9, and B10 of the left lung. Cultures of the mucous plugs and sputum samples yielded white, felt-like mycelial colonies that were later identified as the monokaryotic mycelium of S. commune by use of mating tests with established monokaryotic and dikaryotic strains of S. commune. The results of tests for serum antibody to S. commune cytosol antigen were positive. Repeated bronchoscopies for performing bronchial toilet were effective in removing the mucous plugs and relieving the patient's symptoms. We suggest that the monokaryotic mycelium of S. commune should be considered as one of the fungi that can cause hypersensitivity-related lung diseases.

Virus-induced airway inflammation and hyperresponsiveness in the guinea-pig is inhibited by levodropropizine

Intratracheal Parainfluenza type 3 (PI-3) virus inoculation of guinea pigs leads to a non-specific airway hyperresponsiveness in vivo and in vitro which coincides with a significant increase in the number of inflammatory cells in the broncho-alveolar lavage fluid (90% increase, 4 days after inoculation). The activity of the bronchoalveolar cells, as measured by the chemiluminescence production of infected animals is significantly diminished (34.2%, 4 days after inoculation) after renewed stimulation with PI-3 virus in vitro as compared to the chemiluminescence production by bronchoalveolar cells obtained from control guinea pigs. Pretreatment of the guinea-pigs with the antitussive agent levodropropizine, administered intra-peritoneally twice a day for five successive days at a dose of 10 mg/kg, prevents the virus-induced airway hyperresponsiveness in vivo and in vitro, and inhibits the influx of broncho-alveolar cells. Levodropropizine at a dose of 1 mg/kg did not modulate these responses. Further, the decrease in chemiluminescence production of broncho-alveolar cells obtained from virus-infected animals after PI-3 virus stimulation in vitro was inhibited by levodropropizine (10 mg/kg). These data demonstrate the ability of levodropropizine to counteract the hyperresponsiveness phenomenon and the associated inflammatory event induced by PI-3 virus, an effect which may be due to its capacity to act on the peptidergic system or may be due to the anti-allergic/bronchoconstrictor property of this compound.

Virus-induced airway hyperresponsiveness in man

Airway hyperresponsiveness is the most prominent functional abnormality in asthma. Although its aetiology is still unclear, it is well-known that allergen exposure and virus infections can temporarily induce or aggravate airway hyperresponsiveness. Among these environmental factors, virus infections appear to be clinically most relevant, since recent epidemiological studies have shown that most asthma exacerbations in children are associated with positive nasopharyngeal viral identification. The pathogenesis of virus-induced airway hyperresponsiveness has been investigated by experimental virus infections in animals and in man. Intranasal inoculation and/or inhalation of live attenuated influenza virus, or certain strains of rhinovirus, have been shown to induce airway hyperresponsiveness to various bronchoconstrictor stimuli in man. This indicates that experimental virus-infection, like allergen challenge, is an appropriate investigational model of asthma. The mechanisms of virus-induced airway hyperresponsiveness are still unclear, but may, in part, be similar to those involved in the pathogenesis of asthma. Currently investigated hypothesis include: epithelial damage or dysfunction, immunological responses, inflammatory mediator release, cholinergic and/or noncholinergic reflexes, and impaired beta-adrenoceptor function. Careful experimental studies, using modern laboratory techniques, are needed to unravel the role of viruses in the development of airway hyperresponsiveness. The results of such studies can potentially lead to an improvement of future asthma management.

Relationship of airway responsiveness to agents causing bronchoconstriction and cough in sensitized guinea-pigs

The relationship between airway responsiveness to bronchoconstrictor- and cough-inducing stimuli has been examined in Ascaris suum-sensitized conscious guinea-pigs. Guinea-pigs were sensitized to Ascaris suum [4000 PNU and 100 mg Al(OH)3 i.p. on days 1 and 7] and then challenged with aerosolized antigen on days 21, 28 and 35. At day 35, antigen-exposure produced an early bronchoconstrictor response (EBR) and in about 50% of the animals also a late bronchoconstrictor response (LBR) commencing 4-8 h later. The bronchial responsiveness to inhaled histamine was increased in sensitized guinea-pigs and increased further 20-24 h after acute antigen challenge. Guinea-pigs developing only EBR were equally sensitive to histamine as those having both EBR and LBR. In contrast, the cough and reflex bronchoconstriction produced by inhaled citric acid (0.40 M, acting on capsaicin-sensitive sensory neurons) and cigarette smoke (3 min exposure; exciting both capsaicin-sensitive neurons and rapidly adapting stretch receptors) were not altered by sensitization. Furthermore, acute antigen challenge did not alter the effect of citric acid as measured 24 h later. The antigen-induced airway hyperresponsiveness to histamine was not accompanied by an altered sensitivity of airway sensory nerves mediating cough (and reflex bronchoconstriction), demonstrating that bronchial- (airway obstruction) and sensory- (cough) hyperresponsiveness involve separate and independent mechanisms.

Viruses as precipitants of asthma symptoms. II. Physiology and mechanisms

The upper and lower airways have complimentary roles in the ultimate object of supplying the body with oxygen whilst removing waste products of metabolism. Pathology in one area may trigger a response in another, the physiology of which, in the case of virus-induced asthma exacerbations remains poorly characterized. Viral infection of the upper airways by common cold viruses frequently triggers a response in the lower airways leading to prolonged morbidity, especially in subjects with significant pre-existing airway disease. The induction or amplification of BHR may be an important mechanism whereby asthmatic symptoms are produced although the cellular and tissue events or reflex mechanisms activated by viral illnesses and underlying BHR changes are poorly defined and may be dependent on the type and the severity of infection. Children and asthmatics tend to develop frequent colds setting in motion a sequence of events culminating in airway obstruction and symptoms of wheezing, coughing and chest tightness. This may reflect independent inflammatory changes caused by a simply additive effect of viral damage to the mucosa superimposed upon pre-existing allergic inflammation (Fig. 1). Few if any symptoms will develop in normal subjects with a mild cold whereas significant symptoms may ensue if the cold is severe and induces marked lower airway swelling, secretions and smooth muscle contraction; pathology to which children who have small calibre airways may be particularly susceptible. In asthmatics even a mild cold frequently induces exacerbation of symptoms, while serious life-threatening asthma attacks may occur associated with a severe cold. Some studies have suggested that this effect is not only additive but also synergistic and brought about by release of the mediators already present in increased quantities, the induction of IgE synthesis, or by the potentiation of neural and epithelial damage. The combined effect of both asthma and viruses may thus be amplified and result in a sustained and refractory period of airway obstruction, severe symptoms and unstable asthma. As most hospital admissions for asthma occur over the winter months and soon after the start of the school terms [115], spread of viruses through the community to susceptible individuals may be the single most important cause of sustained exacerbations of asthma. Definition of the pathological and physiological mechanisms involved will lead to better understanding and may thus provide a basis for prevention and the development of effective forms of treatment for virus-induced asthma.