Effect of lipopolysaccharide on the responsiveness of equine bronchial tissue.

Recurrent airway obstruction (RAO) is a main characteristic of horses with severe equine asthma syndrome. The presence of bacterial lipopolysaccharide (LPS) in the airways of horses is thought to play a crucial role in the clinical expression of this disorder. This study pharmacologically characterized the effect of LPS on the responsiveness of equine bronchial tissue. Equine isolated bronchi were incubated overnight with LPS (0.1-100 ng/ml) and then stimulated by electrical field stimulation (EFS). The role of capsaicin sensitive-sensory nerves (capsaicin desensitization treatment), neurokinin-2 (NK2) receptors (blocked by GR159897), transient receptor potential vanilloid type 1 receptors (TRPV1; blocked by SB366791), and neurokinin A (NKA) were investigated. Untreated bronchi were used as control tissues. LPS (1 ng/ml) significantly increased the EFS-evoked contractility of equine bronchi compared with control tissues (+742 ± 123 mg; P < 0.001). At higher concentrations LPS induced desensitization to airways hyperresponsiveness (AHR; EC50: 5.9 ±â€¯2.6 ng/ml). Capsaicin desensitization and GR159897 significantly prevented AHR induced by LPS at EFS1-50Hz (-197 ±â€¯25%; P < 0.01). SB366791 inhibited AHR at very low EFS frequency (EFS1Hz -193 ±â€¯29%; P < 0.01 vs. LPS-treated bronchi). LPS (1 ng/ml) significantly (P < 0.01) increased 3.7 ±â€¯0.7 fold the release of NKA compared with control bronchi. LPS induces biphasic dysfunctional bronchial contractility due to the stimulation of capsaicin sensitive-sensory nerves, increased release of NKA, and activation of NK2 receptors, whereas TRPV1 receptors appear to play a marginal role in this response. The overnight challenge with low concentrations of LPS represents a suitable model to investigate pharmacological options that may be of value in the treatment of equine RAO.

Protein disulfide isomerase-endoplasmic reticulum resident protein 57 regulates allergen-induced airways inflammation, fibrosis, and hyperresponsiveness.

BACKGROUND: Evidence for association between asthma and the unfolded protein response is emerging. Endoplasmic reticulum resident protein 57 (ERp57) is an endoplasmic reticulum-localized redox chaperone involved in folding and secretion of glycoproteins. We have previously demonstrated that ERp57 is upregulated in allergen-challenged human and murine lung epithelial cells. However, the role of ERp57 in asthma pathophysiology is unknown. OBJECTIVES: Here we sought to examine the contribution of airway epithelium-specific ERp57 in the pathogenesis of allergic asthma. METHODS: We examined the expression of ERp57 in human asthmatic airway epithelium and used murine models of allergic asthma to evaluate the relevance of epithelium-specific ERp57. RESULTS: Lung biopsy specimens from asthmatic and nonasthmatic patients revealed a predominant increase in ERp57 levels in epithelium of asthmatic patients. Deletion of ERp57 resulted in a significant decrease in inflammatory cell counts and airways resistance in a murine model of allergic asthma. Furthermore, we observed that disulfide bridges in eotaxin, epidermal growth factor, and periostin were also decreased in the lungs of house dust mite-challenged ERp57-deleted mice. Fibrotic markers, such as collagen and α smooth muscle actin, were also significantly decreased in the lungs of ERp57-deleted mice. Furthermore, adaptive immune responses were dispensable for house dust mite-induced endoplasmic reticulum stress and airways fibrosis. CONCLUSIONS: Here we show that ERp57 levels are increased in the airway epithelium of asthmatic patients and in mice with allergic airways disease. The ERp57 level increase is associated with redox modification of proinflammatory, apoptotic, and fibrotic mediators and contributes to airways hyperresponsiveness. The strategies to inhibit ERp57 specifically within the airways epithelium might provide an opportunity to alleviate the allergic asthma phenotype.

Pulmonary edema measured by MRI correlates with late-phase response to allergen challenge.

PURPOSE: Asthma is associated with reversible airway obstruction, leucocyte infiltration, airways hyperresponsiveness (AHR), and airways remodeling. Fluid accumulation causes pulmonary edema contributing to airways obstruction. We examined the temporal relationship between the late asthmatic response (LAR) following allergen challenge of sensitized guinea-pigs and pulmonary edema measured by magnetic resonance imaging (MRI). MATERIALS AND METHODS: Ovalbumin (OVA) sensitized guinea-pigs received either a single OVA inhalation (acute) or nine OVA inhalations at 48 h intervals (chronic). Airways obstruction was measured as specific airways conductance (sG(aw)) by whole body plethysmography. AHR to inhaled histamine and bronchoalveolar lavage for leucocyte counts were measured 24 h after a single or the final chronic ovalbumin challenges. MRI was performed at intervals after OVA challenge and high-intensity edemic signals were quantified. RESULTS: Ovalbumin caused early bronchoconstriction, followed at 7 h by an LAR and at 24 h AHR and leucocyte influx. The bright-intensity MRI edema signal, peaking at 7 h, was significantly (P < .05) greater after chronic (9.0 ± 0.7 × 10(3) mm(3)) than acute OVA (7.6 ± 0.2 × 10(3) mm(3)). Dexamethasone treatment before acute OVA abolished the AHR and LAR and significantly reduced eosinophils and the bright-intensity MRI edema from 9.1 ± 1.0 to 6.4 ± 0.3 × 10(3) mm(3). CONCLUSION: We show a temporal relationship between edema and the LAR and their parallel reduction, along with eosinophils and AHR, by dexamethasone. This suggests a close causative association between pulmonary edema and impaired airways function.

IL-2-inducible T-cell kinase modulates TH2-mediated allergic airway inflammation by suppressing IFN-γ in naive CD4+ T cells.

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-12Rß1. 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.

Cigarette smoke aggravates asthma via altering airways inflammation phenotypes and remodelling.

INTRODUCTION: Many asthmatic patients are exposed to cigarette smoke actively or passively, which contributes to asthma exacerbation and poor control. This study is to explore the effects of cigarette smoke on pathological changes in murine surrogate of asthma. METHODS: C57BL/6 mice were sensitised and challenged with ovalbumin (OVA) to establish a surrogate of asthma and then administered with cigarette smoke extract (CSE). Airways hyperresponsiveness (AHR) was measured using the Flexivent system. Histological staining (haematoxylin-eosin [HE], periodic acid Schiff [PAS], Congo red and Masson's trichrome) was employed to measure pathological changes in sections of lung tissue of experimental mice. Enzyme-linked immunosorbent assay (ELISA) was used to measure the concentrations of total and OVA-specific IgE, cytokines and chemokines (eotaxin-1, IL-13, IL-1ß, TNF-α, IL-17A, IL-33) in the lung tissue homogenates. Immunoreactivity for vWF and α-SMA in lung tissue sections was detected by immunohistochemistry. RESULTS: Exposure of the animals to CSE significantly reduced OVA-induced AHR, the number of eosinophils in bronchoalveolar lavage fluid (BALF) and eosinophils infiltrating into the lung tissue, as well as concentrations of some cytokines in lung homogenate. In contrast, it significantly enhanced the number of macrophages and M2 in BALF, as well as collagen deposition, smooth muscle thickness and alveolar destruction in lung tissue. CONCLUSION: CSE inhibits OVA-induced AHR, changes inflammation 'phenotypes', while accelerates some aspects of airways remodelling, which might contribute to worse symptoms and be refractory to anti-inflammation therapies for asthmatics.

Predictors of exercise-induced bronchoconstriction in subjects with mild asthma.

BACKGROUND: Physical effort is capable of triggering airway obstruction in asthmatics, the so-called exercise-induced bronchoconstriction in asthma (EIBa). This study was performed in subjects with mild persistent asthma, aiming to find predictors for developing EIBa. METHODS: In 20 subjects with mild asthma, measurements of baseline functional respiratory parameters and airways responsiveness by a methacholine challenge were obtained on the first day. A maximal, symptom-limited incremental cardiopulmonary exercise test (CPExT) was performed the day after, with subsequent, repeated maneuvers of maximal full forced expiration to monitor the FEV1 change at 1,3,5,7,10 and 15 min after the end of the exercise. RESULTS: 19 subjects completed the two-days protocol. No functional parameters both at rest and during effort were useful to predict EIBa after stopping exercise. In asthmatics with EIBa, mean Inspiratory Capacity (IC) did not increase with increasing ventilatory requirements during CPExT because 6 of them (50%) displayed dynamic pulmonary hyperinflation (DH), as documented by their progressive increase of end-expiratory lung volume. This subgroup, showing earlier post-exercise FEV1 fall, had significantly lower forced mean expiratory flow between 25% and 75% of forced vital capacity (FEF25-75%) at rest (p < 0.05) and higher airways responsiveness, expressed as PD20FEV1 (p < 0.05) as compared with other asthmatics with EIBa. CONCLUSIONS: No functional respiratory parameters seem to predict EIBa in mild asthmatics. However, in those with EIBa, a subgroup developed DH during exercise, and this was associated with a baseline reduced forced expiratory flow rates at lower lung volumes and higher airway hyperresponsiveness, suggesting a prominent small airways impairment.

Adjustment of sensitisation and challenge protocols restores functional and inflammatory responses to ovalbumin in guinea-pigs.

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.

Climate change and air pollution: Effects on pollen allergy and other allergic respiratory diseases.

The observational evidence indicates that recent regional changes in climate, particularly temperature increases, have already affected a diverse set of physical and biological systems in many parts of the world. Allergens patterns are also changing in response to climate change and air pollution can modify the allergenic potential of pollen grains especially in the presence of specific weather conditions. Although genetic factors are important in the development of asthma and allergic diseases, their rising trend can be explained only by changes occurring in the environment and urban air pollution by motor vehicles has been indicated as one of the major risk factors responsible for this increase. Despite some differences in the air pollution profile and decreasing trends of some key air pollutants, air quality is an important concern for public health in the cities throughout the world. Due to climate change, air pollution patterns are changing in several urbanized areas of the world with a significant effect on respiratory health. The underlying mechanisms of all these interactions are not well known yet. The consequences on health vary from decreases in lung function to allergic diseases, new onset of diseases, and exacerbation of chronic respiratory diseases. In addition, it is important to recall that an individual's response to pollution exposure depends on the source and components of air pollution, as well as meteorological conditions. Indeed, some air pollution-related incidents with asthma aggravation do not depend only on the increased production of air pollution, but rather on atmospheric factors that favor the accumulation of air pollutants at ground level. Associations between thunderstorms and asthma morbidity of pollinosis-affected people have also been identified in multiple locations around the world (Fig.1). Cite this as D'Amato G, Bergmann KC, Cecchi L, Annesi-Maesano I, Sanduzzi A, Liccardi G, Vitale C, Stanziola A, D'Amato M. Climate change and air pollution - Effects on pollen allergy and other allergic respiratory diseases. Allergo J Int 2014; 23: 17-23 DOI 10.1007/s40629-014-0003-7 A factor clouding the problem is that laboratory evaluations do not reflect what happens during natural exposition. Considering these aspects, governments worldwide, international organizations, and cooperations such as the World Health Organization (WHO) and the European Health Policy of the European Union (EU) are facing a growing problem of the respiratory effects induced by gaseous and particulate pollutants arising from motor vehicle emissions.