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Asthma imposes considerable patient and economic burdens, with the most severe cases causing the greatest affliction. Identifying stimuli that worsen asthma severity is an essential step to controlling both disease morbidity and the lessening economic impact. This study provides the first mechanistic investigation into how acute ethanol exposure will increase asthma severity in a murine model of mild cockroach allergen (CRA)-induced asthma. Outbred mice were sensitized to induce mild allergic asthma, with intratracheal CRA exposures on days 0 and 14. On day 21 mice were gavaged with water or 32% ethanol, and the third allergen exposure was given 30 min post-gavage. Asthmatic responses were measured at several time-points up to 42 h after the third allergen challenge. Ethanol-gavaged mice showed increased asthma severity within 90 min post-allergen challenge, with exacerbations lasting for 24 h. Ethanol caused greater airways obstruction, including an eightfold increase in epithelial cell mucin and increased mucus plugs, resulting in a 50% reduction in bronchiole patency. Ethanol gavage also induced significant increases in airways hyperreactivity. While T helper type 1 (Th1) and Th2 cytokines were not altered by ethanol gavage, pulmonary neutrophil and eosinophil recruitment were augmented. This increase was associated with increased chemokine production. Administration 2 h prior to ethanol gavage of a neutralizing antibody cocktail to keratinocyte-derived chemokine, macrophage inflammatory protein-2, eotaxin-1 and eotaxin-2 prevented ethanol-induced eosinophil recruitment and airways hyperreactivity. These data provide evidence that acute alcohol exposure immediately prior to a mild allergen-triggered asthmatic episode will exacerbate asthma severity mediated by increased production of chemokines., (© 2012 British Society for Immunology.)

Asthma may be triggered by multiple mediators, including allergen-IgE cross-linking and non-IgE mechanisms. Several clinical studies have shown acute ethanol consumption exacerbates asthma, yet no animal model exists to study this process. We developed a model of ethanol-triggered asthma in allergen-sensitized mice to evaluate the mechanisms of ethanol inducing asthma-like responses. Outbred mice were exposed to cockroach allergens on Days 0 and 14; and on Day 21, mice received ethanol by oral gavage. Tracer studies confirmed alcohol aspiration did not occur. Within 30 minutes, alcohol induced degranulation of over 74% of mast cells, and multiple parameters of asthma-like pulmonary inflammation were triggered. Ethanol-gavaged mice had a fivefold increased production of eotaxin-2 (534 pg/mL) and a sevenfold increase in bronchoalveolar eosinophils (70,080 cells). Ethanol induced a 10-fold increase in IL-13, from 84 pg/mL in sensitized mice to 845 pg/mL in ethanol-gavaged sensitized mice. In cockroach allergen-sensitized mice, ethanol triggered asthma-like changes in respiratory physiology and a significant fivefold increase in airway mucin production. Importantly, none of these asthmatic exacerbations were observed in normal mice gavaged with ethanol. Cromolyn sodium effectively stabilized mast cells, yet increased mucin production and bronchoalveolar eosinophil recruitment. Together, these data show a single oral alcohol exposure will trigger asthma-like pulmonary inflammation in allergen-sensitized mice, providing a novel asthma model., (Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Objectives: The aim of this study is to define the kinetics of the pulmonary inflammatory response in cockroach allergen (CRA) sensitized and challenged outbred mice., Methods: Asthma-like pulmonary inflammation was induced with three pulmonary exposures to CRA, without the use of adjuvants. Mice were sacrificed at multiple time points and asthma-like pulmonary inflammation quantified., Results: Several pulmonary parameters showed a pronounced biphasic inflammatory response with an early stage (1.5 hours post challenge) and late stage (24 hours). The initial phase was characterized by the production of multiple inflammatory mediators, including CXC chemokines, and the recruitment of neutrophils to the lung. The number of pulmonary eosinophils decreased in the early phase but quickly rebounded. Both the early and late phases had increases in TNF production in addition to airways hyperreactivity. The model also demonstrated early production of mucin with clearance by 12 hours followed by new accumulation of mucin in the pulmonary epithelial cells. Eotaxins within the lung peaked at about 12 hours and the numbers of eosinophils in the lung remained constant throughout the 48 hours of the study., Conclusions: The pulmonary inflammatory parameters in response to a clinically relevant allergen define a biphasic response. These data may be used to investigate the pathogenesis of the disease and develop targeted therapies for the distinct phases.

Particulate matter heavily pollutes the urban atmosphere, and several studies show a link between increased ambient particulate air pollution and exacerbation of pre-existing pulmonary diseases, including asthma. We investigated how diesel exhaust particulates (DEPs) aggravate asthma-like pulmonary inflammation in a mouse model of asthma induced by a house dust extract (HDE) containing cockroach allergens and endotoxin. BALB/c mice were exposed to three pulmonary challenges via hypopharyngeal administration of an HDE collected from the home of an asthmatic child. One hour before each pulmonary challenge, mice were exposed to DEP or PBS. Pulmonary inflammation was assessed by histological features, oxidative stress, respiratory physiological features, inflammatory cell recruitment, and local CXC chemokine production. To prove the role of CXC chemokines in the augmented inflammation, CXC chemokine-specific antibodies were delivered to the lungs before DEP exposure. DEP exacerbated HDE-induced airway inflammation, with increased airway mucus production, oxidative stress, inflammatory cell infiltration, bronchoalveolar lavage concentrations of CXC chemokines, and airway hyperreactivity. Neutralization of airway keratinocyte-derived chemokine and macrophage inflammatory protein-2 significantly improves the respiratory function in addition to decreasing the infiltration of neutrophils and eosinophils. Blocking the chemokines also decreased airway mucus production. These results demonstrate that DEP exacerbates airway inflammation induced by allergen through increased pulmonary expression of the CXC chemokines (keratinocyte-derived chemokine and macrophage inflammatory protein-2)., (Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Outbred mice traditionally are considered to display high variability, thereby limiting their use in some studies. Researchers frequently are encouraged to use inbred strains of mice because of the greater homogeneity of these experimental animals. We compared the pulmonary inflammatory response of inbred BALB/cJ mice to that of outbred HSD-ICR mice by measuring multiple variables, including cytokines, chemokines, number of pulmonary inflammatory cells, and respiratory parameters. Cockroach allergens induced significant pulmonary inflammation in both BALB and ICR mice. Our comparisons of the coefficients of variance for 148 discrete data sets for each strain or stock indicated that BALB and ICR mice have roughly equivalent intrastrain or -stock variability in our model of asthma-like pulmonary inflammation. The average coefficient of variance, calculated as the ratio of the SD to the mean of a data set, was 0.35 ± 0.34 for BALB mice compared with 0.31 ± 0.32 for ICR mice. In conclusion, inbred BALB and outbred ICR mice have roughly equivalent intrastrain or -stock variability in a murine model of asthma-like pulmonary inflammation.

Background: Antigen desensitization through oral tolerance is becoming an increasingly attractive treatment option for allergic diseases. However, the mechanism(s) by which tolerization is achieved remain poorly defined. In this study we endeavored to induce oral tolerance to cockroach allergen (CRA: a complex mixture of insect components) in order to ameliorate asthma-like, allergic pulmonary inflammation., Methods: We compared the pulmonary inflammation of mice which had received four CRA feedings prior to intratracheal allergen sensitization and challenge to mice fed PBS on the same time course. Respiratory parameters were assessed by whole body unrestrained plethysmography and mechanical ventilation with forced oscillation. Bronchoalveolar lavage fluid (BAL) and lung homogenate (LH) were assessed for cytokines and chemokines by ELISA. BAL inflammatory cells were also collected and examined by light microscopy., Results: CRA feeding prior to allergen sensitization and challenge led to a significant improvement in respiratory health. Airways hyperreactivity measured indirectly via enhanced pause (Penh) was meaningfully reduced in the CRA-fed mice compared to the PBS fed mice (2.3 ± 0.4 vs 3.9 ± 0.6; p = 0.03). Directly measured airways resistance confirmed this trend when comparing the CRA-fed to the PBS-fed animals (2.97 ± 0.98 vs 4.95 ± 1.41). This effect was not due to reduced traditional inflammatory cell chemotactic factors, Th2 or other cytokines and chemokines. The mechanism of improved respiratory health in the tolerized mice was due to significantly reduced eosinophil numbers in the bronchoalveolar lavage fluid (43300 ± 11445 vs 158786 ± 38908; p = 0.007) and eosinophil specific peroxidase activity in the lung homogenate (0.59 ± 0.13 vs 1.19 ± 0.19; p = 0.017). The decreased eosinophilia was likely the result of increased IL-10 in the lung homogenate of the tolerized mice (6320 ± 354 ng/mL vs 5190 ± 404 ng/mL, p = 0.02)., Conclusion: Our results show that oral tolerization to CRA can improve the respiratory health of experimental mice in a CRA-induced model of asthma-like pulmonary inflammation by reducing pulmonary eosinophilia.

Pulmonary inflammation causes multiple alterations within the lung, including mucus production, recruitment of inflammatory cells, and airway hyperreactivity (AHR). Measurement of AHR by direct, invasive means (eg, mechanical ventilation) or noninvasive techniques, like whole body plethysmography (WBP), assesses the severity of pulmonary inflammation in animal models of inflammatory lung disease. Direct measurement of AHR is acknowledged as the most accurate method for assessing airway mechanics, but analysis of all data obtained from WBP may offer insights into which inflammatory aspects of the lung are altered along with AHR. Using WBP, we compared the respiratory parameters of two groups of mice sensitized with cockroach allergen. One group was treated with dexamethasone (Dex) before final challenge (Dex-Asthma), while the other group received vehicle treatment (Asthma). Respiratory parameters from plethysmography revealed that Dex-Asthma mice compensated to maintain high minute ventilation, whereas Asthma mice showed significant impairment in minute ventilation despite increased peak expiratory flow (103 ± 5 ml/min vs. 69 ± 70 ml/min). The WBP data suggest that enhanced air exchange in the Dex-Asthma mice results from significant decreases in airway mucus production. Additional studies with quantitative morphometry of histological sections confirmed that Dex reduced airway mucus. In conclusion, a detailed examination of WBP parameters can accurately assess the respiratory health of mice and will help direct additional studies.