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Introduction: Inhalation of antigen in atopic asthma induces early (EAR) and late asthmatic responses (LARs), inflammatory cell infiltration and airways hyperresponsiveness (AHR). Previously, we have established a protocol of sensitisation and subsequent ovalbumin (Ova) inhalation challenge in guinea-pigs which induced these 4 features (Smith & Broadley, 2007). However, the responses of guinea-pigs to Ova challenge have recently declined, producing no LAR or AHR and diminished EAR and cells. By making cumulative modifications to the protocol, we sought to restore these features., Methods: Guinea-pigs were sensitised with Ova (i.p. 100 or 150 μg) on days 1 and 5 or days 1, 4 and 7 and challenged with nebulised Ova (100 or 300 μg/ml, 1h) on day 15. Airway function was measured in conscious guinea-pigs by whole-body plethysmography to record specific airway conductance (sGaw). Airway responsiveness to aerosolized histamine (0.3mM) was determined before and 24h after Ova challenge. Bronchoalveolar lavage was performed for total and differential inflammatory cell counts. Lung sections were stained for counting of eosinophils., Results: Lack of AHR and LAR with the original protocol was confirmed. Increasing the Ova challenge concentration from 100 to 300 μg/ml restored AHR and eosinophils and increased the peak of the EAR. Increasing the number of sensitisation injections from 2 to 3 did not alter the responses. Increasing the Ova sensitisation concentration from 100 to 150 μg significantly increased total cells, particularly eosinophils. A LAR was revealed and lymphocytes and eosinophils increased when either the Al(OH)3 concentration was increased or the duration between the final sensitisation injection and Ova challenge was extended from 15 to 21 days., Discussion: This study has shown that declining allergic responses to Ova in guinea-pigs could be restored by increasing the sensitisation and challenge conditions. It has also demonstrated an important dissociation between EAR, LAR, AHR and inflammation., (Copyright © 2014. Published by Elsevier Inc.)

Background: Asthma is a predominantly TH2 cell-dominated inflammatory disease characterized by airway inflammation and a major public health concern affecting millions of persons. The Tec family tyrosine kinase IL-2-inducible T-cell kinase (Itk) is primarily expressed in T cells and critical for the function and differentiation of TH cells. Itk(-/-) mice have a defective TH2 response and are not susceptible to allergic asthma., Objective: We sought to better understand the role of Itk signaling in TH differentiation programs and in the development and molecular pathology of allergic asthma., Methods: Using a murine model of allergic airway inflammation, we dissected the role of Itk in regulating TH cell differentiation through genetic ablation of critical genes, chromatin immunoprecipitation assays, and house dust mite-driven allergic airway inflammation., Results: Peripheral naive Itk(-/-) CD4(+) T cells have substantially increased transcripts and expression of the prototypic TH1 genes Eomesodermin, IFN-γ, T-box transcription factor (T-bet), and IL-12Rβ1. Removal of IFN-γ on the Itk(-/-) background rescues expression of TH2-related genes in TH cells and allergic airway inflammation in Itk(-/-) mice. Furthermore, small hairpin RNA-mediated knockdown of Itk in human peripheral blood T cells results in increased expression of mRNA for IFN-γ and T-bet and reduction in expression of IL-4., Conclusion: Our results indicate that Itk signals suppress the expression of IFN-γ in naive CD4(+) T cells, which in a positive feed-forward loop regulates the expression of TH1 factors, such as T-bet and Eomesodermin, and suppress development of TH2 cells and allergic airway inflammation., (Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Chronic inflammation is a hallmark of pulmonary diseases, which leads to lung parenchyma destruction (emphysema) and obstructive bronchiolitis occurring in both chronic obstructive pulmonary disease and asthma. Inflammation is strongly correlated with low intracellular cAMP levels and increase in specific cAMP hydrolyzing activity. The aim of the present study was to investigate the role of the cyclic phosphodiesterase type 4 (PDE4) in human lung and to determine the effects of NCS 613, a new PDE4 inhibitor, on lung inflammation and bronchial hyperresponsiveness. High cAMP-PDE activities were found in the cytosoluble fractions from human lung parenchyma and distal bronchi. PDE4 (rolipram sensitive) represented 40% and 56% of total cAMP-PDE activities in the above-corresponding tissues. Moreover, PDE4A, PDE4B, PDE4C, and PDE4D isoforms were detected in all three subcellular fractions (cytosolic, microsomal, and nuclear) with differential distributions according to specific variants. Pharmacological treatments with NCS 613 significantly decreased PDE4 activity and reduced IκBα degradation in cultured parenchyma, both of which are usually correlated with a lower inflammation status. Moreover, NCS 613 pretreatment potentiated isoproterenol-induced relaxations in human distal bronchi, while reducing TNF-α-induced hyperresponsiveness in cultured bronchi, as assessed in the presence of methacholine, U-46619, or histamine. This reducing effect of NCS 613 on human bronchi hyperresponsiveness triggered by TNF-α was related to a lower expression level of PDE4B and PDE4C, as well as a downregulation of the phosphorylated forms of p38-MAPK, CPI-17, and MYPT-1, which are known to control tone. In conclusion, specific PDE4 inhibitors, such as NCS 613, may represent an alternative and isoform-specific approach toward reducing human lung inflammation and airway overreactivity. [ABSTRACT FROM AUTHOR]

Exposure to diesel exhaust particulate matter (DEP) exacerbates asthma. Likewise, similar effects have been reported with exposure to the oxidizing air pollutant ozone (O3). Since levels of both pollutants in ambient air tend to be simultaneously elevated, we investigated the possible synergistic effect of these agents on the exacerbation of allergic airways disease in mice. Male BALB/c mice were sensitized ip with ovalbumin (Ova) or vehicle only, then exposed once per week for 4 wk via nose-only inhalation (4 h) to the PM2.5 fraction of DEP (2 mg/m3), O3 (0.5 ppm), DEP and O3, or filtered air, and then challenged with aerosolized ovalbumin. Ova sensitization in air-exposed mice enhanced pulmonary inflammatory cell infiltration, several indicators of injury in the lung (lactate dehydrogenase, albumin and total protein), and lung resistance (RL) and elastance (EL) in response to methacholine (MCh) aerosol challenge. DEP exposure did not enhance the Ova-induced increase in pulmonary cell infiltration, indicators of injury, or RL and EL. O3 exposure enhanced the Ova-induced increase in inflammatory cell infiltration and N-acetylglucosaminidase (NAG) in the lung, but had no effect on RL or EL. DEP co-exposure significantly attenuated the O3-induced increase in cell infiltration and indicators of injury; co-exposure had no effect on EL relative to air-exposed Ova-sensitized mice. However, only DEP-O3 co-exposure significantly increased the Ova-induced increase in RL. Thus, O3 and DEP co-exposure exacerbated airways hyperresponsiveness, a response that was not associated with parallel increases in pulmonary inflammation and one that may be mediated by a unique mechanism. [ABSTRACT FROM AUTHOR]

Allergic inflammation is known to cause airway hyperresponsiveness in mice. However, it is not known whether inflammation affects the stiffness of the airway wall, which would alter the load against which the circumscribing smooth muscle shortens when activated. Accordingly, we measured the time course of airway resistance immediately following intravenous methacholine injection in acutely and chronically allergically inflamed mice. We estimated the effective stiffness of the airway wall in these animals by fitting to the airway resistance profiles a computational model of a dynamically narrowing airway embedded in elastic parenchyma. Effective airway wall stiffness was estimated from the model fit and was found not to change from control in either the acute or chronic inflammatory groups. However, the acutely inflamed mice were hyperresponsive compared with controls, which we interpret as reflecting increased delivery of methacholine to the airway smooth muscle through a leaky pulmonary endothelium. These results support the notion that acutely inflamed BALB/c mice represent an animal model of functionally normal airway smooth muscle in a transiently abnormal lung. [ABSTRACT FROM AUTHOR]

Chronic Iipopolysaccharide (LPS) inhalation in rodents recapitulates many classic features of chronic obstructive pulmonary disease seen in humans, including airways hyperresponsiveness, neutrophilic inflammation, cytokine production in the lung, and small airways remodeling. CD14-deficient mice (C57BL/6CD14-/-) have an altered response to systemic LPS, and yet the role of CD14 in the response to inhaled LPS has not been defined. We observed that C57BL/6CD14-/- mice demonstrate no discernable physiological or inflammatory response to a single LPS inhalation challenge. However, the physiological (airways hyperresponsiveness) and inflammatory (presence of neutrophils and TNF-α in whole lung lavage fluid) responsiveness to inhaled LPS in C57BL/6CD14-/- mice was restored by instilling soluble CD14 intratracheally. Intratracheal instillation of wild-type macrophages into C57BL/6CD14-/- mice restored neutrophilic inflammation only and failed to restore airways hyperresponsiveness or TNF-α protein in whole lung lavage. These findings demonstrate that CD14 is critical to LPS-induced airway disease and that macrophage CD14 is sufficient to initiate neutrophil recruitment into the airways but that CD14 may need to interact with other cell types as well for the development of airways hyperresponsiveness and for cytokine production. [ABSTRACT FROM AUTHOR]

Abstract: PDE4 (phosphodiesterase-4) plays a critical role in pathogenesis of allergic asthma and chronic obstructive pulmonary disease (COPD). PDE4 inhibitors are presently under clinical development for the treatment of asthma and/or COPD. Ciclamilast, a new PDE4 inhibitor, is a piclamilast (RP 73401) structural analogue, but has a more potent inhibitory effect on PDE4 and inflammation in the airway tissues and less side effects than that of piclamilast. In this study, we elucidate primarily on the roles of compound on PDE4 enzyme in physiological and pathological processes in a mouse model of asthma. The sensitized/challenged mice were reexposed to ovalbumin and airway response to inhaled methacholine was monitored. Orally administration of ciclamilast, in a dose-dependent manner, significantly inhibited changes in lung resistance and lung dynamic compliance, as well as upregulation of cAMP-PDE activity, increase of PDE4D mRNA expression, but not PDE4B from lung tissue in the murine model. In addition, the compound dose-dependently reduced mRNA expression of eotaxin, tumor necrosis factor (TNF)-α and interleukin (IL)-4, but slightly increased mRNA expression of interferon (IFN)-γ from lung tissue. Further, levels of eotaxin, TNF-α and IL-4, and eosinophil and neutrophil accumulation in bronchoalveolar lavage fluid were also significantly reduced. Pathological examination, goblet cell hyperplasia and inflammatory cells infiltration in lung tissue were suppressed by treatment with ciclamilast. A significant correlation was observed between the increases in PDE4D mRNA expression and airway hyperresponsiveness. These studies confirm that inhibitory effect of ciclamilast on airway hyperresponsiveness includes its inhibiting PDE4D mRNA expression, down-modulating PDE4 activity, anti-inflammation and anti-mucus hypersecretion, and ciclamilast may have therapeutic potential for the treatment of asthma. [Copyright &y& Elsevier]