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.     

Treatment strategies for asthma

Asthma is characterized by variable and reversible airflow limitation and bronchial hyperresponsiveness due to chronic airway inflammation. Asthma treatment is based on the patients' asthma control status. Central to treatment recommendations is anti-inflammatory therapy with inhaled corticosteroids plus a rapid-acting β(2)-agonist as required. If this is not sufficient to achieve at least partial asthma control, the dose of the inhaled corticosteroid should be increased and a long-acting β(2)-agonist should be added. Other controllers, such as leukotriene antagonists or slow-release theophylline are alternative or additive options. Systemic treatment with corticosteroids and/or the monoclonal anti-IgE antibody omalizumab are reserved for patients with severe asthma. Strategies aimed at preventing airway irritation, reducing exposure to exogenous allergens and inhaled irritants as well as asthma education are other key elements of asthma management.     

Effect of procaterol, a beta(2) selective adrenergic receptor agonist, on airway inflammation and hyperresponsiveness.

BACKGROUND: beta-agonists are frequently used as bronchodilators for asthma as not only a reliever but also a controller, and their utility has increased with the development of long-acting beta(2) selective drugs. Although anti-inflammatory effects of beta(2) selective-agonists have been reported in vitro, side effects on augmentation of airway hyperresponsiveness by chronic use of beta(2) selective-agonists have been described in several reports. In this study, we investigated the effects of procaterol, a second-generation beta(2)-agonist, on airway inflammation in vivo using an antigen-specific murine model of asthma. METHODS: Mice immunized with ovalbumin (OVA) + alum and challenged with inhaled ovalbumin were orally administered procaterol during the challenge. After inhalation, the mice were tracheostomized and placed in a body box under controlled ventilation to measure airway resistance before and after acetylcholine inhalation. RESULTS: Administration of procaterol at a clinical dose equivalent did not augment airway hyperresponsiveness, inflammation of the airway wall, or subsequent airway wall thickening induced by OVA inhalation. BALF cell analysis revealed that the eosinophil number in the BALF was significantly reduced in procaterol-treated mice compared to untreated mice. CONCLUSIONS: Oral administration of procaterol at a clinical dose did not augment airway responsiveness, but did reduce eosinophil inflammation.     

Inhibitory Effects of Anti-Immunoglobulin E Antibodies on Airway Remodeling in A Murine Model of Chronic Asthma

Background: Airway remodeling is one of the cardinal features of asthma and is thought to play a pivotal role in refractory or persistent asthma. Immunoglobulin E (IgE) has a major effect on the pathogenesis of asthma. The aim of this study was to investigate the effects of anti-IgE antibody not only on airway inflammation and bronchial hyperresponsiveness, but also on airway remodeling in a murine model of chronic asthma. Methods: The authors developed a mouse model of chronic asthma in which ovalbumin (OVA)-sensitized female BALB/c-mice were exposed to intranasal OVA administration twice a week for 3 months. Anti-IgE antibodies were administered intravenously starting on the 38th day and once a month thereafter for 3 months during the intranasal OVA challenge. Results: Mice that were chronically exposed to OVA developed sustained eosinophilic airway inflammation and airway hyperresponsiveness (AHR) to methacholine and showed increased levels of collagen, hydroxyproline, and α-smooth muscle actin, as compared with control mice. Treatment with anti-IgE antibody inhibited the development of AHR, eosinophilic inflammation, and airway remodeling. Moreover, anti-IgE antibody treatment reduced the levels of interleukin (IL)-5 and IL-13 in the bronchoalveolar lavage fluids, although it did not affect the levels of IL-10, transforming growth factor-β, and activin A. Conclusion: These results suggest that anti-IgE antibody treatment modulates the airway inflammation and remodeling associated with chronic allergen challenge. The inhibition of inflammation may be related to the regulation of Th2 cytokines. However, the mechanisms underlying the blocking of airway remodeling by anti-IgE antibody remain to be elucidated.     

Therapiestrategien bei Asthma

Asthma is characterized by variable and reversible airflow limitation and bronchial hyperresponsiveness due to chronic airway inflammation. Asthma treatment is based on the patients’ asthma control status. Central to treatment recommendations is anti-inflammatory therapy with inhaled corticosteroids plus a rapid-acting β₂-agonist as required. If this is not sufficient to achieve at least partial asthma control, the dose of the inhaled corticosteroid should be increased and a long-acting β₂-agonist should be added. Other controllers, such as leukotriene antagonists or slow-release theophylline are alternative or additive options. Systemic treatment with corticosteroids and/or the monoclonal anti-IgE antibody omalizumab are reserved for patients with severe asthma. Strategies aimed at preventing airway irritation, reducing exposure to exogenous allergens and inhaled irritants as well as asthma education are other key elements of asthma management.     

Group 2 innate lymphoid cells in human asthma

Asthma is characterized by increased airway hyperresponsiveness, reversible airflow limitation, and remodeling due to allergic airway inflammation. Asthma has been proposed to be classified into various phenotypes by cluster analyses integrating clinical information and laboratory data. Recently, asthma has been classified into two major endotypes, Type 2-high and Type 2-low asthma, and various subtypes based on the underlying molecular mechanisms. In Type 2-high asthma, Th2 cells, together with group 2 innate lymphoid cells (ILC2s), produce type 2 cytokines such as IL-4, IL-5, IL-9, and IL-13, which play crucial roles in causing airway inflammation. The roles of ILC2s in asthma pathogenesis have been analyzed primarily in murine models, demonstrating their importance not only in IL-33- or papain-induced innate asthma models but also in house dust mite (HDM)- or ovalbumin (OVA)-induced acquired asthma models evoked in an antigen-specific manner. Recently, evidence regarding the roles of ILC2s in human asthma is also accumulating. This minireview summarizes the roles of ILC2s in asthma, emphasizing human studies.     

CpG-寡核苷酸与支气管哮喘

Th1／Th2失衡是支气管哮喘的重要免疫学发病机制,近年在支气管哮喘的发病机制中取得较大进展,CD4^＋T辅助细胞按其分泌的细胞因子不同分为Th1和Th2细胞,Th1反应可以抑制Th2反应,抑制气遭慢性炎症,含有未甲基化CpG结构的寡核苷酸是近年研究较多的一种调节Th1／Th2平衡的免疫制剂,本文就其调节Th1／Th2平衡在支气管哮喘治疗中的应用前景作一综述。     

Calcium channel blocker prevents T helper type 2 cell-mediated airway inflammation

RATIONALE: Ca(2+) signaling controls the production of T helper (Th) type 2 cytokines known to be deleterious in asthma. Recently, we showed that Ca(2+) signaling was dihydropyridine (DHP)-sensitive in Th2 lymphocytes and that the DHP derivate, nicardipine, used in the treatment of cardiovascular pathologies, prevents Th2-dependent B cell polyclonal activation. OBJECTIVES: We tested the effect of nicardipine in experimental allergic asthma. METHODS: BALB/c mice immunized with ovalbumin (OVA) in alum and challenged with intranasal OVA were treated with nicardipine once the Th2 response, or even airway inflammation, was induced. We also tested the effect of nicardipine in asthma induced by transferring OVA-specific Th2 cells in BALB/c mice exposed to intranasal OVA. We checked the impact of nicardipine on T-cell responses and airway inflammation. MEASUREMENTS AND MAIN RESULTS: Nicardipine inhibited in vitro Ca(2+) response in Th2 cells. In vivo, it impeded the development of Th2-mediated airway inflammation and reduced the capacity of lymphocytes from lung-draining lymph nodes to secrete Th2, but not Th1, cytokines. Nicardipine did not affect antigen presentation to CD4(+) T lymphocytes, nor the initial localization of Th2 cells into the lungs of mice exposed to intranasal OVA; however, it reduced the production of type 2 cytokines and the amplification of the Th2 response in mice with asthma. Conversely, nicardipine had no effect on Th1-mediated airway inflammation. CONCLUSIONS: Nicardipine improves experimental asthma by impairing Th2-dependent inflammation. This study could provide a rationale for developing drugs selectively targeting DHP receptors of Th2 lymphocytes, potentially beneficial in the treatment of asthma.     

Immune response to hepatitis B vaccine in asthmatic children

Asthma is a disease that demonstrates chronic Th2 lymphocyte-mediated pulmonary inflammation. We hypothesized that cytokines produced by asthmatic lung inflammation bias the immune response to antigens administered systemically toward a Th2 response, as assessed by serum IgE antibody and lymphocyte-secreted IL-4 and IL-5. We also hypothesized that treatment of asthmatic children with local anti-inflammatory agents reduces this cytokine-mediated Th2 influence. We systemically immunized groups of asthmatic children (n=29) who were participating in a long-term, randomized, placebo-controlled clinical trial of inhaled anti-inflammatory therapy (Childhood Asthma Management Program) and nonasthmatic children (n=12) with hepatitis B (Hep B) antigen, and examined their antigen-specific antibody and lymphocyte cytokine secretion profiles. The asthmatic population demonstrated an increased amount of Th2-mediated serum IgE anti-Hep B antibody, as compared to nonasthmatic children; but comparable amounts of IgG1, IgG2, IgG3, IgA, and IgM anti-Hep B antibody and lymphocyte IFNgamma, IL4, and IL5. There was no significant difference of antibody isotype or cytokine production between asthmatic subjects receiving treatment with budesonide or nedocromil, as compared to placebo. In conclusion, there is a subtle bias in responses to systemic immunization in children with asthma, but anti-inflammatory therapy does not affect this bias. The findings support the concept that the Th2 bias may be largely genetic. Importantly, we confirmed that children with asthma, including even those on inhaled corticosteroids, responded to Hep B immunization as well as did nonasthmatic children with the major isotypes of anti-Hep B antibody, suggesting that vaccine protection against hepatitis B is not influenced by inhaled steroid therapy.     

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.     

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.     

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.     

Treating asthma: is there a place for leukotriene receptor antagonists?

Asthma is a chronic disorder, characterized by airway hyperresponsiveness (AHR), airway inflammation and airway remodelling. Evidence has been provided for a relationship between pathophysiology, airway inflammation and remodelling. Moreover, these asthma features have been shown to respond to anti-inflammatory therapy. According to current guidelines, monitoring of asthma is predominantly based on symptoms and lung function data. However, these parameters appeared as poor indices for asthma control. Alternatively, asthma control relates well to exacerbations and (anamnestic) surrogate biomarkers of airway inflammation. Hence, appropriate treatment of asthma should primarily target the airway inflammation. According to current guidelines for asthma management, anti-inflammatory therapy with inhaled corticosteroids (ICS) is the cornerstone in the treatment of persistent asthma. To further optimize asthma control, add-on therapy with long-acting beta2-agonists (LABA) or leukotriene receptor antagonists (LTRA) should be combined with low to high doses of ICS. While the first combination focuses on optimal control of symptoms and lung function, the second provides a more complete suppression of the airway inflammation. In this paper we discuss treatment of asthma according to current guidelines versus new insights, addressing practical issues.     

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.     

不同内型哮喘小鼠模型中的小气道功能研究及其机制初探

目的 探讨不同内型哮喘小鼠模型中,小气道功能是否存在异常及其相关机制.方法 卵清蛋白(OVA)致敏、激发建立T2型哮喘模型,OVA联合臭氧暴露(OVA+ozone)建立非T2型哮喘模型.模拟强迫振荡系统检测小鼠小气道功能,激发试验检测气道反应性.酶联免疫吸附试验法检测支气管肺泡灌洗液(BALF)中的细胞因子;苏木精-伊...     

A protective role for the fifth complement component (c5) in allergic airway disease

RATIONALE: Reports from our laboratory, as well as those from others, have documented the importance of complement activation, the C3a anaphylatoxin, and its receptor, C3aR, in promoting Th2 effector functions in a mouse model of bronchopulmonary allergy. Although deficiency in the fifth complement component (C5) has been linked to enhanced airway hyperresponsiveness in mice, the contribution of C5 to other major biological hallmarks of asthma has not been evaluated. OBJECTIVE: Accordingly, congenic C5-sufficient and C5-deficient mice were subjected to a mouse model of bronchopulmonary allergy to assess the impact of C5 on pulmonary inflammation and Th2 effector functions in experimental asthma. METHODS AND MAIN RESULTS: In contrast to observations reported for C3- and C3aR-deficient animals, C5-deficient mice exhibited significantly increased airway hyperresponsiveness relative to wild-type congenic control mice after antigen challenge. Moreover, challenged C5-deficient mice had a 3.4-fold and 2.7-fold increase in the levels of airway eosinophils and lung interleukin (IL)-4-producing cells, respectively, compared with challenged wild-type mice. Consistent with the numbers of IL-4-producing cells, C5-deficient mice also had increased bronchoalveolar lavage levels of the Th2 cytokines IL-5 and IL-13 and elevated serum levels of total and antigen-specific IgE. CONCLUSIONS: These data indicate that C5 plays an important protective role in allergic lung disease by suppressing inflammatory responses and Th2 effector functions observed in this experimental model. The protection provided by the presence of C5 is likely mediated by C5a, suggesting that C5a may play a significant role in tempering inflammation in Th2-driven diseases such as asthma.     

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.