Inhaled corticosteroid prevents the thickening of airway smooth muscle in murine model of chronic asthma

Airway smooth muscle growth contributes to the mechanism of airway hyperresponsiveness (AHR) in asthma. Although current steroid use demonstrates anti-inflammatory activity, there is little reported on the action of corticosteroid on smooth muscle of the asthmatic airway. The present study investigated the effect of inhaled corticosteroid on the thickening of airway smooth muscle in bronchial asthma. We developed a mouse model of airway remodeling including smooth muscle thickening in which ovalbumin (OVA)-sensitized female BALB/c-mice were repeatedly exposed to intranasal OVA administration twice a week for 3 months. Mice were treated intranasally with fluticasone during the OVA challenge. Mice chronically exposed to OVA developed sustained eosinophilic airway inflammation compared with control mice. In addition, the mice chronically exposed to OVA developed features of airway remodeling, including thickening of the peribronchial smooth muscle layer. Intranasal administration of fluticasone inhibited the development of eosinophilic inflammation, and importantly, thickening of the smooth muscle layer. Moreover, intranasal fluticasone treatment reduced the transforming growth factor (TGF)-beta 1 level in bronchoalveolar lavage fluid and regulated active TGF-beta 1 signaling with a reduction in the expression of phospho-Smad2/3 and the concomitant up-regulation of Smad7 in lung tissue sections. These results suggest that intranasal administration of fluticasone can modulate the remodeling of airway smooth muscle via regulation of TGF-beta 1 production and active TGF-beta 1 signaling.     

Effect of choline chloride in allergen-induced mouse model of airway inflammation.

The incidence of asthma has increased the world over, and current therapies for the disease suffer from potential side-effects. This has created an opportunity to develop novel therapeutic approaches. Here, the anti-inflammatory activity of choline was investigated in a mouse model of allergic airway inflammation. Choline (1 mg.kg(-1)) was administered via oral gavage or intranasally before and after ovalbumin (OVA) challenge in sensitised mice. Airway hyperresponsiveness (AHR) to methacholine was measured in the mice by whole-body plethysmography. Type-2 T-helper cell cytokine and leukotriene levels were estimated in bronchoalveolar lavage fluid (BALF) and spleen culture supernatant by ELISA. Eosinophil peroxidase activity was also determined in the BALF supernatant. Choline treatment in sensitised mice before OVA challenge via oral/intranasal routes significantly inhibited eosinophilic airway inflammation and eosinophil peroxidase activity. It also reduced immunoglobulin E and G1 production and inhibited the release of type-2 T-helper cell cytokines and leukotrienes. However, the development of AHR was prevented effectively by intranasal choline treatment. Most importantly, choline treatment after OVA challenge by both routes could reverse established asthmatic conditions in mice by inhibiting AHR, eosinophilic airway inflammation and other inflammatory parameters. This study provides a new therapeutic approach for controlling as well as preventing asthma exacerbations.     

Anti-interleukin 5 but not anti-IgE prevents airway inflammation and airway hyperresponsiveness.

The role of IL-5 and allergen-specific IgE in the development of eosinophilic airway inflammation and airway hyperresponsiveness (AHR) was investigated in a murine model. BALB/c mice were sensitized to ovalbumin (OVA) by intraperitoneal injection on Days 1 and 14, followed by airway challenge with OVA on Days 28 and 29. Anti-IL-5 (TRFK-5) or anti-IgE (antibody 1-5) was administered before each airway challenge. Sensitized and challenged mice developed increased OVA-specific IgE serum levels, Th2 cytokine production by peribronchial lymph node (PBLN) cells, increased numbers of eosinophils (predominantly located in the peribronchial regions of the lungs), and increased airway responsiveness to methacholine (MCh). Anti-IgE treatment significantly decreased serum anti-OVA IgE levels and prevented the development of anaphylaxis but failed to affect T cell function, eosinophil airway infiltration, and AHR in sensitized and challenged mice. In contrast, treatment with anti-IL-5 antibody did not affect B cell (Ig serum levels), T cell (cytokine production), or mast cell function (immediate cutaneous reactivity) but completely inhibited development of eosinophilic lung inflammation and AHR. These data identify IL-5-mediated eosinophilia as a major target for development of AHR in this model, with little effect resulting from neutralization of IgE.     

Lipopolysaccharides promote a shift from Th2-derived airway eosinophilic inflammation to Th17-derived neutrophilic inflammation in an ovalbumin-sensitized murine asthma model

Introduction: The currently available treatments for severe asthma are insufficient. Infiltration of neutrophils rather than eosinophils into the airways is an important inflammatory characteristic of severe asthma. However, the mechanism of the phenotypic change from eosinophilic to neutrophilic inflammation has not yet been fully elucidated. Methods: In the current study, we examined the effect of lipopolysaccharides (LPS) on eosinophilic asthmatic mice sensitized with ovalbumin (OVA), as well as the roles of interleukin (IL)-17A/T helper (Th) 17 cells on the change in the airway inflammatory phenotype from eosinophilic to neutrophilic inflammation in asthmatic lungs of IL-17A-deficient mice. Results: Following exposure of OVA-induced asthmatic mice to LPS, neutrophil-predominant airway inflammation rather than eosinophil-predominant inflammation was observed, with increases in airway hyperresponsiveness (AHR), the IL-17A level in bronchoalveolar lavage fluid (BALF) and Th17 cells in the spleen and in the pulmonary hilar lymph nodes. Moreover, the neutrophilic asthmatic mice showed decreased mucus production and Th2 cytokine levels (IL-4 and IL-5). In contrast, IL-17A knockout (KO) mice exhibited eosinophil-predominant lung inflammation, decreased AHR, mucus overproduction and increased Th2 cytokine levels and Th2 cells. Conclusion: These findings suggest that the eosinophilic inflammatory phenotype of asthmatic lungs switches to the neutrophilic phenotype following exposure to LPS. The change in the inflammatory phenotype is strongly correlated with the increases in IL-17A and Th17 cells.     

Different roles of interleukin-10 in onset and resolution of asthmatic responses in allergen-challenged mice

OBJECTIVE: Although interleukin (IL)-10 is an immunoregulatory cytokine produced by various cells including T cells, its precise role in asthma remains uncertain. The aim of this study was to investigate the role of IL-10 in experimental asthma using ovalbumin (OVA)-sensitized mice. METHODOLOGY: Mice were challenged with OVA aerosol, and airway responsiveness and inflammation were measured. OVA-specific IL-10-producing CD4+ T cells were counted from lung cells collected by enzymatic digestion and stimulated ex vivo with OVA. The effects of an anti-IL-10 antibody on airway responsiveness and inflammation were also evaluated. RESULTS: The OVA challenge caused airway hyperresponsiveness and eosinophilic inflammation. A significant increase in IL-10-producing CD4+ T cells was observed, mainly in the CD45RB(low) subset, for several days after the OVA challenge. Anti-IL-10 antibody treatment before the OVA challenge did not affect eosinophilic inflammation but significantly inhibited airway hyperresponsiveness 24 h after the OVA challenge. However, anti-IL-10 antibody treatment just before the last OVA challenge significantly attenuated the resolution of eosinophilic inflammation without affecting airway responsiveness 2 weeks after the OVA challenge. CONCLUSIONS: Intrinsic IL-10 may have a distinct role in the early and late phases of asthmatic responses. In the early phase, IL-10 induces airway hyperresponsiveness, while in the late phase IL-10 contributes to the resolution of eosinophilic inflammation.     

Platelets are necessary for airway wall remodeling in a murine model of chronic allergic inflammation

Asthma is associated with airway remodeling. Evidence of platelet recruitment to the lungs of asthmatics after allergen exposure suggests platelets participate in various aspects of asthma; although their importance is unknown in the context of airway remodeling, their involvement in atherosclerosis is established. Studies from our laboratory have shown a requirement for platelets in pulmonary leukocyte recruitment in a murine model of allergic lung inflammation. Presently, the effects of platelet depletion and corticosteroid administration on airway remodeling and lung function were examined. Ovalbumin (OVA)-sensitized mice, exposed to aerosolized OVA for 8 weeks, demonstrated epithelial and smooth muscle thickening, and subepithelial reticular fiber deposition in the distal airways. The depletion of platelets via an immunologic (antiplatelet antisera) or nonimmunologic (busulfan) method, markedly reduced airway remodeling. In contrast, dexamethasone administration did not affect epithelial thickening or subepithelial fibrosis, despite significantly inhibiting leukocyte recruitment. Thus, pathways leading to certain aspects of airway remodeling may not depend on leukocyte recruitment, whereas platelet activation is obligatory. OVA-sensitized mice exhibited airway hyperresponsiveness (AHR) compared with sham-sensitized mice following chronic OVA exposure. Neither platelet depletion nor dexamethasone administration inhibited chronic AHR; thus, mechanisms other than inflammation and airway remodeling may be involved in the pathogenesis of chronic AHR.     

Suppression of heme oxygenase-1 activity reduces airway hyperresponsiveness and inflammation in a mouse model of asthma

Objective: Carbon monoxide (CO) levels in expired gas are higher in patients with bronchial asthma than in healthy individuals. Heme oxygenase-1 (HO-1) is a rate-limiting enzyme that catalyzes the degradation of heme to yield biliverdin, CO and free iron. Thus, HO-1 is implicated in the pathogenesis of bronchial asthma. However, whether HO-1 expression and activity in lung tissue are related to allergic airway inflammation remains unclear. We investigated whether expression of HO-1 is related to allergic airway inflammation in lungs and whether HO-1 could influence airway hyperresponsiveness and eosinophilia in mice sensitized to ovalbumin (OVA). Methods: C57BL/6 mice immunized with OVA were challenged thrice with an aerosol of OVA every second day for 8 days. HO-1-positive cells were identified by immunostaining in lung tissue, and zinc protoporphyrin (Zn-PP), a competitive inhibitor of HO-1, was administered intraperitoneally to OVA-immunized C57BL/6 mice on day 23 (day before inhalation of OVA) and immediately before inhalation on the subsequent 4 days (total five doses). Mice were analyzed for effects of HO-1 on AHR, inflammatory cell infiltration and cytokine levels in lung tissue. Ethical approval was obtained from the concerned institutional review board. Results: Number of HO-1-positive cells increased in the subepithelium of the bronchi after OVA challenge, and HO-1 localized to alveolar macrophages. Zn-PP clearly inhibited AHR, pulmonary eosinophilia and IL-5 and IL-13 expression in the lung tissue. Conclusion: Expression of HO-1 is induced in lung tissue during attacks of allergic bronchial asthma, and its activity likely amplifies and prolongs allergic airway inflammation.     

The Relationship Between Inflammation and Dipalmitoyl Phosphatidycholine in Induced Sputum of Children with Asthma

Background.?Animal studies have shown elevated surfactant production in response to lung injury. In human airways, the contribution of surfactant to the airway epithelial barrier and importance of eosinophilic inflammation is increasingly appreciated. The relationship between blood and sputum inflammatory indices of childhood asthma to surfactant levels is unknown. In this study we hypothesized that the degree of inflammation influences the level of dipalmitoyl phosphatidycholine (DPPC) in airways of children with asthma. Methods.?Sixteen children with asthma (ages 5.5–16 years) underwent venipuncture, skin prick test, spirometry, hypertonic saline challenge, and induced sputum during a nonacute phase. Sputum (sp) and blood (se) markers of inflammation (eosinophils, neutrophils, eosinophilic cationic protein [ECP]), were related to sputum DPPC levels and several markers of asthma severity (airway hyperresponsiveness, quality of life, FEV₁). Results.?On multiple regression, sp-DPPC significantly correlated to sp-ECP (r = 0.53, P = 0.0048). Se-ECP, se-Eo, sp-eosinophils, sp-neutrophils, se-neutrophils, and inhaled steroids dose did not significantly influence sp-DPPC. Exposure to smoke did not influence inflammatory markers. FEV₁ and quality of life data did not relate to any blood or sputum variable. A significant association between AHR and se-eosinophils, but not between AHR and se-ECP, sp-eosinophils, or sp-ECP was found. Conclusion.?Elevated DPPC levels occur in the presence of chronic eosinophilic inflammation in airways of children with stable asthma. Whether this represents an inherent lung mechanism for epithelial protection remains to be elucidated.     

Chitin induces steroid-resistant airway inflammation and airway hyperresponsiveness in mice

BackgroundPrevious reports have shown that pathogen-associated patterns (PAMPs) induce the production of interleukin (IL)-1β in macrophages. Moreover, studies using mouse models also suggest that chitin, which acts as a PAMP, induces adjuvant effects and eosinophilic infiltration in the lung. Thus, we investigated the effects of inhaled chitin in mouse models.MethodsWe developed mouse models of inhaled chitin particle-induced airway inflammation and steroid-resistant ovalbumin (OVA)-induced airway inflammation. Some experimental groups of mice were treated additionally with dexamethasone (DEX). Murine alveolar macrophages (AMs), which were purified from bronchoalveolar lavage (BAL) fluids, were incubated with chitin, and treated with or without DEX.ResultsThe numbers of total cells, AMs, lymphocytes, eosinophils, and neutrophils among BAL-derived cells, as well as the IL-1β levels in BAL fluids and the numbers of IL-1β-positive cells in lung, were significantly increased by chitin stimulation. Airway hyperresponsiveness (AHR) was aggravated in mice of the chitin inflammation model compared to control animals. The production of IL-1β was significantly increased in murine AMs by chitin treatment, but DEX administration did not inhibit this chitin-induced IL-1β production. Furthermore, in mouse models, DEX treatment inhibited the OVA-induced airway inflammation and AHR but not the airway inflammation and AHR induced by chitin or the combination of OVA and chitin.ConclusionsThese results suggest that inhaled chitin induces airway inflammation, AHR, and the production of IL-1β. Furthermore, our findings demonstrate for the first time that inhaled chitin induces steroid-resistant airway inflammation and AHR. Inhaled chitin may contribute to features of steroid-resistant asthma.     

FENO and AHR mannitol in patients referred to an out-of-hospital asthma clinic: a real-life study

Objective: Ongoing airway inflammation measured by fractional exhaled nitric oxide (FENO) and airway hyperresponsiveness (AHR) to mannitol are associated in selected asthma patients, but no evidence exists of this association in unselected asthma patients. The aim was to investigate the association between FENO and AHR to mannitol in unselected individuals with possible asthma. Methods: A real-life study on patients with possible asthma referred to a specialized asthma clinic. Data on asthma history, FEV1, FENO, atopy, smoking, treatment and AHR to mannitol were collected. Results: In 217 unselected patients with symptoms suggestive of asthma, FENO and response to mannitol were tested. Of the 141 who underwent both tests, 32 (23%) had FENO >?25?ppb, and 58 (41%) had AHR to mannitol. A significant association between high FENO and AHR was found (p?r?=?0.32, p?Conclusion: In a large sample of patients referred to an asthma clinic, an association was found between FENO and AHR to mannitol. However, a significant proportion of asthma patients had a normal FENO despite having AHR, suggesting that in some patients, AHR to mannitol is not driven by eosinophilic airway inflammation.     

Eosinophilic airway disorders associated with chronic cough

Chronic cough is a major clinical problem. The causes of chronic cough can be categorized into eosinophilic and noneosinophilic disorders, the former being comprised of asthma, cough variant asthma (CVA), atopic cough (AC) and non-asthmatic eosinophilic bronchitis (NAEB).Cough is one of the major symptoms of asthma. Cough in asthma can be classified into three categories; 1) CVA: asthma presenting solely with coughing, 2) cough-predominant asthma: asthma predominantly presenting with coughing but also with dyspnea and/or wheezing, and 3) cough remaining after treatment with inhaled corticosteroid (ICS) and β2-agonists in patients with classical asthma, despite control of other symptoms. There may be two subtypes in the last category; one is cough responsive to anti-mediator drugs such as leukotriene receptor antagonists and histamine H1 receptor antagonists, and the other is cough due to co-morbid conditions such as gastroesophageal reflux.CVA is one of the commonest causes of chronic isolated cough. It shares a number of pathophysiological features with classical asthma with wheezing such as atopy, airway hyperresponsiveness (AHR), eosinophilic airway inflammation and various features of airway remodeling. One third of adult patients may develop wheezing and progress to classical asthma. As established in classical asthma, ICS is considered the first-line treatment, which improves cough and may also reduce the risk of progression to classical asthma.AC proposed by Fujimura et al. presents with bronchodilator-resistant dry cough associated with an atopic constitution. It involves eosinophilic tracheobronchitis and cough hypersensitivity and responds to ICS treatment, while lacking in AHR and variable airflow obstruction. These features are shared by non-asthmatic eosinophilic bronchitis (NAEB). However, atopic cough does not involve bronchoalveolar eosinophilia, has no evidence of airway remodeling, and rarely progresses to classical asthma, unlike CVA and NAEB. Histamine H1 antagonists are effective in atopic cough, but their efficacy in NAEB is unknown. AHR of NAEB may improve with ICS within the normal range. Taken together, NAEB significantly overlaps with atopic cough, but might also include milder cases of CVA with very modest AHR. The similarity and difference of these related entities presenting with chronic cough and characterized by airway eosinophilia will be discussed.     

Modulation of the airway smooth muscle phenotype in a murine asthma model and effects of nuclear factor-κB inhibition

Objective: Phenotype modulation of airway smooth muscle (ASM) is a unique characteristic of asthma and is considered to regulate airway remodeling, airway hyperresponsiveness (AHR) and inflammation. The nuclear factor-κB (NF-κB) signaling pathway plays a crucial role in phenotypic modulation. Thus, models of acute and chronic asthma were established and pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor was delivered by intraperitoneal injection. Methods: The Penh value was measured using the BUXCO WBP system. Lung tissues were subjected to histologic analysis. Phenotypic markers of ASM and COL1A1 mRNA levels were measured by RT-PCR. Expression levels of phosphorylated p65 (pP65) and α-SMA were detected by Western blot. Serum cytokine levels were quantified by RayBiotech ELISA array. Results: PDTC intervention decreased the Penh values in both the acute and chronic models. The ASM area and the airway collagen area were decreased in the PDTC intervention group. A decrease in phenotypic markers were detected in both the acute and chronic models in time-dependent manner, and PDTC intervention partially reversed the phenotypic modulation. The effect of PDTC intervention on systemic inflammation was also verified. Conclusion: These results revealed the existence of a dynamic ASM phenotype modulation procedure in asthma development and that targeting NF-κB by PDTC was effective to mitigate ASM phenotype modulation and major asthmatic pathological features.     

Anti-nerve growth factor antibody improves airway hyperresponsiveness by down-regulating RhoA

Background: The pathogenesis of asthma is complex and continues to be considered as a challenging subject. Some studies have shown that nerve growth factor (NGF) participates in the pathogenesis of asthma, but the mechanism of airway contraction caused by NGF is still unclear. Objective: Our aim was to discuss the effect of anti-NGF antibody on RhoA expression, and further explore the role of NGF in airway hyperresponsiveness (AHR). Methods: Thirty female BALB/c mice were divided into three groups randomly: control group (group C, n = 10), asthma group (group A, n = 10) and anti-NGF antibody intervention group (group N, n = 10). The asthmatic mice were stimulated by OVA suspension, the intervention mice were given nasal instillation of anti-NGF antibody before the stimulation. Airway responsiveness, eosinophils, IL-13, IFN-γ were measured. The protein expression and mRNA level of NGF and RhoA were detected by immunohistochemical and Real Time-PCR (RT-PCR) analyses. Results: Airway responsiveness, eosinophils and IL-13 levels in group A were significantly increased compare with the other groups, and significantly decreased in group N than those in group A. IFN-γ level was significantly reduced in group A and increased in group N. Immunohistochemistry and RT-PCR analyses showed that the protein expression and mRNA level of NGF and RhoA were significantly increased in group A and significantly decreased in group N. Conclusion: NGF participates in the pathogenesis of asthma in mice. Anti-NGF antibody can inhibit airway inflammation and alleviate AHR by down-regulating the protein expression and mRNA level of RhoA.     

A comparison of antiasthma drugs between acute and chronic ovalbumin-challenged guinea-pig models of asthma

Pre-clinical evaluation of asthma therapies requires animal models of chronic airways inflammation, airway hyperresponsiveness (AHR) and lung remodelling that accurately predict drug effectiveness in human asthma. However, most animal models focus on acute allergen challenges where chronic inflammation and airway remodelling are absent. Chronic allergen challenge models have been developed in mice but few studies use guinea-pigs which may be more relevant to humans. We tested the hypothesis that a chronic rather than acute pulmonary inflammation model would best predict clinical outcome for asthma treatments. Guinea-pigs sensitized with ovalbumin (OVA) received single (acute) or nine OVA inhalation challenges at 48 h intervals (chronic). Airways function was recorded as specific airways conductance (sG_aw) in conscious animals for 12 h after OVA challenge. AHR to inhaled histamine, inflammatory cell influx and lung histology were determined 24 h after the single or 9th OVA exposure. The inhaled corticosteroid, fluticasone propionate (FP), the phosphodiesterase 4 inhibitor, roflumilast, and the inducible nitric oxide synthase (iNOS) inhibitor, GW274150, orally, were administered 24 and 0.5 h before and 6 h after the single or final chronic OVA exposure. Both models displayed early (EAR) and late (LAR) asthmatic responses to OVA challenge, as falls in sG_aw, AHR, as increased histamine-induced bronchoconstriction, and inflammatory cell influx. Tissue remodelling, seen as increased collagen and goblet cell hyperplasia, occurred after multiple OVA challenge. Treatment with FP and roflumilast inhibited the LAR, cell influx and AHR in both models, and the remodelling in the chronic model. GW274150 also inhibited the LAR, AHR and eosinophil influx in the acute model, but not, together with the remodelling, in the chronic model. In the clinical setting, inhaled corticosteroids and phosphodiesterase 4 inhibitors are relatively effective against most features of asthma whereas the iNOS inhibitor GW274150 was ineffective. Thus, while there remain certain differences between our data and clinical effectiveness of these antiasthma drugs, a chronic pulmonary inflammation guinea-pig model does appear to be a better pre-clinical predictor of potential asthma therapeutics than an acute model.     

T helper 1 cells stimulated with ovalbumin and IL-18 induce airway hyperresponsiveness and lung fibrosis by IFN-gamma and IL-13 production

We previously reported that ovalbumin (OVA) and IL-18 nasally administered act on memory type T helper (Th)1 cells to induce airway hyperresponsiveness (AHR) and inflammation, which is characterized by peribronchial infiltration with neutrophils and eosinophils. Here, we report this administration also induces lung fibrosis in an IL-13-dependent manner. Th1 cells secrete several cytokines, including IFN-gamma and bronchogenic cytokine IL-13, when stimulated with antigen (Ag) and IL-18. However, IL-13 blockade failed to attenuate AHR, although this treatment inhibited eosinophilic infiltration. To understand the mechanism by which Th1 cells induce AHR after Ag plus IL-18 challenge, we established "passive" and "active" Th1 mice by transferring OVA-specific Th1 cells into na?ve BALB/c mice or by immunizing na?ve BALB/c mice with OVA/complete Freund's adjuvant, respectively. Administration of Ag and IL-18 induced both types of Th1 mice to develop AHR, airway inflammation, and lung fibrosis. Furthermore, this treatment induced deposition of periostin, a novel component of lung fibrosis. Neutralization of IL-13 or IFN-gamma during Ag plus IL-18 challenges inhibited the combination of eosinophilic infiltration, lung fibrosis, and periostin deposition or the combination of neutrophilic infiltration and AHR, respectively. We also found that coadministration of OVA and LPS into Th1 mice induced AHR and airway inflammation via endogenous IL-18. Thus, IL-18 becomes a key target molecule for the development of a therapeutic regimen for the treatment of Th1-cell-induced bronchial asthma.     

Airway hyper-responsiveness in young adults with asthma that remitted either during or before adolescence

Background and objective: More than 50% of patients with childhood asthma enter clinical remission by puberty, although 40–50% of these people will probably develop asthma symptoms during early adulthood. The mechanism of relapsing asthma in early adulthood remains unclear. This study determined the characteristics of young adults whose asthma remitted either during or before adolescence. Methods: A comparative study was performed on 24 students whose childhood asthma had gone into clinical remission by puberty (remission group), 25 atopic students with no history of asthma (atopy group) and 19 non‐atopic students without allergic diseases (control group). Examinations included spirometry, levels of serum‐specific IgE‐antibodies, airway responsiveness to methacholine, exhaled nitric oxide (eNO) and evidence of airway inflammation in induced sputum. Results: Airway responsiveness (P < 0.01), eosinophil counts in sputum (P < 0.05) and the prevalence of sensitization to Dermatophagoides forinae (P < 0.01) were significantly higher, and FEF_25–75% and FEF_75% (P < 0.01) were significantly lower in the remission group than in the atopy and control groups. Furthermore, 50% and 33% of the remission group had airway hyper‐responsiveness (AHR) and sputum eosinophilia, respectively. The eNO levels in the remission (P < 0.01) and atopy (P < 0.05) groups were significantly higher than in controls. Remission group members with AHR had a significantly longer period of childhood asthma, a shorter period of remission and greater airway eosinophilic inflammation than those without AHR (P < 0.05). Conclusion: One half of young adults with childhood asthma that remitted either during or before adolescence continued to have evidence of AHR and airway eosinophilic inflammation, and might be at risk of future relapse.     

Important roles for L-selectin and ICAM-1 in the development of allergic airway inflammation in asthma.

Airway inflammation and airway hyperresponsiveness (AHR) are fundamental features of asthma. Migration of inflammatory cells from the circulation into the lungs is dependent upon adhesion molecule interactions. The cell surface adhesion molecules L-selectin and intercellular adhesion molecule (ICAM)-1 have been demonstrated to mediate leukocyte rolling on inflamed pulmonary endothelium, and ICAM-1 has also been shown to mediate capillary sequestration in inflamed lung. However, their roles in the development of airway inflammation and AHR in asthma have not been directly examined. We have characterised the roles of L-selectin and ICAM-1 in the recruitment of inflammatory cells to the lung and in the development of airway hyperresponsiveness using an ovalbumin (OVA)-induced allergic airway disease model of asthma and adhesion molecule-deficient mice. OVA-sensitized/challenged ICAM-1-deficient mice have dramatically reduced inflammatory influx into the airway/lung and a corresponding attenuation of AHR as compared to wild-type controls. OVA-sensitized/challenged L-selectin-deficient mice demonstrate significantly reduced numbers of CD3(+)lymphocytes and increased numbers of B220(+)lymphocytes in BAL as compared to wild-type mice (P< 0.05). However, other parameters of airway/lung inflammation in OVA-sensitized/challenged L-selectin-deficient mice were equivalent to wild-type control mice. Remarkably, despite a fulminant inflammatory response in the airway/lung, AHR was completely abrogated in OVA-sensitized/challenged L-selectin-deficient mice. These findings suggest a crucial role for ICAM-1 in the development of airway inflammation and AHR in asthma. In contrast, L-selectin plays a more selective role in the development of airway hyperresponsiveness but not allergic inflammation in this animal model of asthma. Thus, L-selectin and ICAM-1 represent potential targets for novel asthma therapies specifically aimed at controlling airway inflammation and/or airway hyperresponsiveness. Copyright Academic Press.     

Endogenous and Exogenous Thioredoxin 1 Prevents Goblet Cell Hyperplasia in a Chronic Antigen Exposure Asthma Model

BackgroundGoblet cell hyperplasia with mucus hypersecretion contribute to increased morbidity and mortality in bronchial asthma. We have reported that thioredoxin 1 (TRX1), a redox (reduction/oxidation)-active protein acting as a strong antioxidant, inhibits pulmonary eosinophilic inflammation and production of chemoki- nes and Th2 cytokines in the lungs, thus decreasing airway hyperresponsiveness (AHR) and airway remodeling in mouse asthma models. In the present study, we investigated whether endogenous or exogenous TRX1 inhibits goblet cell hyperplasia in a mouse asthma model involving chronic exposure to antigen.MethodsWe used wild-type Balb/c mice and Balb/c background human TRX1-transgenic mice constitutively overproducing human TRX1 protein in the lungs. Mice were sensitized 7 times (days 0 to 12) and then challenged 9 times with ovalbumin (OVA) (days 19 to 45). Every second day from days 18 to 44 (14 times) or days 35 to 45 (6 times), Balb/c mice were treated with 40 μg recombinant human TRX1 (rhTRX1) protein. Goblet cells in the lungs were examined quantitatively on day 34 or 45.ResultsGoblet cell hyperplasia was significantly prevented in TRX1-transgenic mice in comparison with TRX1 transgene-negative mice. rhTRX1 administration during OVA challenge (days 18 to 44) significantly inhibited goblet cell hyperplasia in OVA-sensitized and -challenged wild-type mice. Moreover, rhTRX1 administration after the establishment of goblet cell hyperplasia (days 35 to 45) also significantly ameliorated goblet cell hyperplasia in OVA-sensitized and -challenged wild-type mice.ConclusionsOur results suggest that TRX1 prevents the development of goblet cell hyperplasia, and also ameliorates established goblet cell hyperplasia.     

Inflammatory Subtypes in Asthma are Related to Airway Hyperresponsiveness to Mannitol and Exhaled NO

Asthma may be defined as eosinophilic or non-eosinophilic based on the presence of eosinophils in sputum. Recently a further classification into four inflammatory subtypes has been suggested. The aim of the present study was to describe the association between these inflammatory subtypes and markers of airway inflammation and hyperresponsiveness. In 62 adult non-smoking asthmatics, (18–65 yr) not taking inhaled steroids, sputum induction, bronchial challenge with mannitol and measurement of exhaled NO (eNO) were performed. Based on the eosinophil and neutrophil proportions in sputum, subjects were categorised into four inflammatory subtypes: Eosinophilic asthma: i.e., sputum eosinophils > 1.0%. Neutrophilic asthma: i.e., sputum neutrophils > 61%. Mixed granulocytic asthma: both increased eosinophils and neutrophils. Paucigranulocytic asthma: i.e., normal levels of both eosinophils and neutrophils. Among subjects with non-eosinophilic asthma, neutrophilic asthma was associated with low levels of eNO (Median (IQR): 12 ppb (8–27 ppb), whereas subjects with non-eosinophilic asthma of the paucigranulocytic subtype had levels of eNO (48 ppb (29–65 ppb)) that were comparable to subjects with eosinophilic asthma of the mixed granulocytic type (47 ppb (33–112 ppb). Purely eosinophilic asthma was associated with higher levels of eNO (77 ppb (37–122 ppb)). Furthermore, a low degree of airway hyperresponsiveness to mannitol was observed in neutrophilic asthma (PD₁₅: (Median (IQR) 512 mg (291–610 mg))), whereas it was moderate in paucigranulocytic asthma (238 mg (77–467 mg)) and comparable to eosinophilic asthma of the mixed granulocytic subtype (186 mg (35–355 mg)). The highest degree of AHR to mannitol was observed in purely eosinophilic asthma (107 mg (68–245 mg)). In conclusion, further subclassification of eosinophilic and non-eosinophilic asthma showed significant differences in airway hyperresponsiveness to mannitol and exhaled NO levels among the four inflammatory subtypes.     

Prophylactic Vaccination with Adjuvant Monophosphoryl Lipid A Prevents Th2-Mediated Murine Asthmatic Responses

Objective. Asthma is a chronic respiratory disorder characterized by airway hyperreactivity, eosinophilic infiltration, high titer of allergen-specific IgE, and overproduction of T helper 2 (Th2) cytokines. Antigen combined with an appropriate adjuvant and administrated through the proper route can elicit suitable immunological responses to protect humans and animals from diseases. Antigen formulated with monophosphoryl lipid A (MPLA) can produce priming of Th1-mediated immune responses. The purpose of this study was to examine the utility of MPLA as an adjuvant to prevent asthma. Methods. BALB/c mice were immunized with ovalbumin (OVA) formulated with or without MPLA by intraperitoneal, footpad, or subcutaneous injection. Vaccinated mice were challenged with OVA aerosol to estimate the protective efficacy of MPLA in comparison to Th2-adjuvant aluminum hydroxide (Alum). Airway hyperresponsiveness to methacholine, eosinophilia in bronchoalveolar lavage fluid (BALF), circulating titers of OVA-specific antibodies, and stimulating levels of IFN-γ and IL-4 cytokines from splenocytes were evaluated. Results. Mice immunized by all injection routes with OVA formulated with MPLA increased the ratio of Th1/Th2 responses compared to mice receiving antigen alone. For prophylactic vaccination purpose, MPLA reduced airway responsiveness and eosinophilic inflammation in the lung, decreased serum OVA-specific IgE level, and increased the serum ratio of OVA-specific IgG2a/IgG1 and the ratio of IFN-γ/IL4 from OVA-activated splenocytes compared with mice vaccinated with Alum. Conclusion. MPLA may be clinically useful in the vaccination of individuals predisposed to asthma.