Bronchial asthma as neurogenic paroxysmal inflammatory disease: do some antiepileptic drugs have antiasthmatic properties?

Bronchial asthma is an inflammatory disease, and neurogenic inflammation may play important role in asthma mechanisms. But asthma also is an inflammatory disease with paroxysmal clinical picture. It is known that migraine and trigeminal neuralgia also are inflammatory diseases with paroxysmal clinical picture, and neurogenic inflammation plays important role in their mechanisms. Antiepileptic drugs are highly effective in pharmacotherapy of migraine and trigeminal neuralgia, and these drugs completely prevent attacks of migraine and trigeminal pain in great majority of cases. Due to this it is possible that some antiepileptic drugs may be highly effective in pharmacotherapy of asthma. Bronchial asthma can be considered as peripheral paroxysmal and inflammatory disease with definite central neurogenic mechanism. It is also possible that some antiepileptic drugs can suppress inflammatory processes in asthma through the central neural influence, like in therapy of migraine and trigeminal neuralgia.     

β2-Agonists and bronchial hyperresponsiveness

Bronchial hyperresponsiveness (BHR) is a characteristic feature of asthma, and individuals with this disease respond to a range of physiological and chemical insults that are otherwise innocuous to healthy subjects, suggesting that the mechanisms underlying this phenomenon are characteristic of the asthma phenotype. BHR can be increased following exposure to environmental allergens in suitably sensitized individuals, pollutants, and certain viruses and can also be exacerbated by exposure to certain drugs, including nonsteroidal anti-inflammatory agents and β-blockers. Although β₂-agonists administered acutely remain the treatment for the symptoms of asthma, paradoxically, regular treatment with these drugs can result in an increase in BHR, and this has been suggested to contribute to the increase in asthma morbidity and mortality that has been reported by numerous investigators. This article highlights our current understanding of this phenomenon and examines the potential mechanisms responsible for this effect.     

Beta2-agonists and bronchial hyperresponsiveness

Bronchial hyperresponsiveness (BHR) is a characteristic feature of asthma, and individuals with this disease respond to a range of physiological and chemical insults that are otherwise innocuous to healthy subjects, suggesting that the mechanisms underlying this phenomenon are characteristic of the asthma phenotype. BHR can be increased following exposure to environmental allergens in suitably sensitized individuals, pollutants, and certain viruses and can also be exacerbated by exposure to certain drugs, including nonsteroidal anti-inflammatory agents and beta-blockers. Although beta2-agonists administered acutely remain the treatment for the symptoms of asthma, paradoxically, regular treatment with these drugs can result in an increase in BHR, and this has been suggested to contribute to the increase in asthma morbidity and mortality that has been reported by numerous investigators. This article highlights our current understanding of this phenomenon and examines the potential mechanisms responsible for this effect.     

Asthma deaths; persistent and preventable mortality

Bronchial asthma remains a significant cause of mortality at all ages, despite the increased understanding of its pathogenesis and the range of drugs available for its treatment. Changes in therapeutic management can influence death rates and constant surveillance, combined with high-quality post mortem investigations, is essential. Disease severity, poor disease management and adverse psychosocial circumstances are all risk factors for asthma mortality. Bronchial asthma causes characteristic histological changes in the mucosa of the airways which are present even before the clinical diagnosis of asthma can be made. These include fibrous thickening of the lamina reticularis of the epithelial basement membrane, smooth muscle hypertrophy and hyperplasia, increased mucosal vascularity and an eosinophil-rich inflammatory cell infiltrate. In addition, mucoid plugging of the airway lumen is frequently associated with fatal asthma. The recognition of these changes can allow the diagnosis of asthma to be made for the first time at autopsy, in those cases where asthma goes undiagnosed in life. Acute severe asthma may be accompanied by pneumothorax and surgical emphysema of the mediastinum. Disorders which may mimic asthma include pulmonary embolism, chronic obstructive pulmonary disease and anaphylaxis, but careful post mortem examination and appropriate investigations should reveal the true cause of death.     

Increased T-cell receptor vbeta8+ T cells in bronchoalveolar lavage fluid of subjects with poorly controlled asthma: a potential role for microbial superantigens.

BACKGROUND: T cells are thought to play an important role in the pathogenesis of chronic asthma. The immunologic triggers that contribute to poorly controlled asthma are unknown but may include infectious agents. Superantigens (SAgs), which stimulate T cells expressing selected T-cell receptor (TCR) beta-chain variable (Vbeta) regions, are known to be an important mechanism by which microbes can contribute to T-cell activation and disease pathogenesis. OBJECTIVE: We sought to determine the potential role of SAgs in T-cell activation of patients with poorly controlled asthma. METHODS: We studied the TCR-Vbeta repertoire of bronchoalveolar lavage (BAL) cells and PBMCs from 9 subjects with poorly controlled asthma (FEV1 <75%), 7 subjects with well-controlled asthma (FEV1 >80%), and 8 normal control subjects with the use of anti-TCR-Vbeta-specific mAbs and flow cytometry. RESULTS: Subjects with poorly controlled asthma had a significantly higher expression of Vbeta8(+) T cells in BAL fluid than subjects with well-controlled asthma and normal control subjects (P <.01) and autologous PBMCs (P <.05). Increased Vbeta8(+) BAL T cells were present in CD4(+) (P <.01) and CD8(+) (P <.05) subsets, suggesting activation by SAgs. CONCLUSION: These results indicate that SAgs are a potential trigger of T-cell activation in poorly controlled asthma.     

T cells and eosinophils cooperate in the induction of bronchial epithelial cell apoptosis in asthma

BACKGROUND: Asthma is an inflammatory airway disease associated with an infiltration of T cells and eosinophils, increased levels of pro-inflammatory cytokines, and shedding of bronchial epithelial cells (ECs). OBJECTIVE: Shedding of bronchial ECs is characterized by loss of the normal bronchial pseudostratified epithelium and the maintenance of a few basal cells on a thickened basement membrane. The aim of this study was to investigate whether, and by which mechanism, T cells and eosinophils can cause damage to airway ECs. METHODS: Bronchial ECs, cultured and exposed to cytokines, eosinophil cationic protein, activated T cells, and eosinophils were studied for the expression of apoptosis receptors (flow cytometry, immunoblotting, and RNA expression) and for the susceptibility for undergoing apoptosis. In addition, bronchial biopsy specimens from patients with asthma were evaluated for EC apoptosis. RESULTS: We demonstrate herein that the respiratory epithelium is an essential target of the inflammatory attack by T cells and eosinophils. Bronchial ECs underwent cytokine-induced cell death with DNA fragmentation and morphologic characteristics of apoptosis mediated by activated T cells and eosinophils. T cell- and eosinophil-induced EC apoptosis was blocked by inhibition of IFN-alpha and TNF-alpha; the Fas ligand-Fas pathway appears to be less important. Recombinant eosinophil cationic protein induced mainly necrosis of ECs. Furthermore, we demonstrated in situ apoptotic features of ECs in bronchial biopsy specimens of asthmatic patients. CONCLUSION: T cell- and eosinophil-induced apoptosis represents a key pathogenic event leading to EC shedding in asthma.     

Functional and phenotypic characteristics of bronchial epithelial cells obtained by brushing from asthmatic and normal subjects

Bronchial epithelial cells may be involved in the pathogenesis of asthma releasing several inflammatory mediators such as interleukins and lipoxygenase products. In this study we evaluated the spontaneous and A23128-induced release of IS-HETE, PGE2 and fibronectin as well as the spontaneous expression of HLA-DR and ICAM-1 molecules by bronchial epithelial cells obtained by bronchial brushing from 35 asthmatic and 27 normal subjects. The release of fibronectin and 15-HETE was studied using the EIA and RIA techniques. The expression of HLA-DR and ICAM-1 molecules was studied using the APAAP and the immunofluorescence methods. Bronchial epithelial cells from asthmatics released higher amounts of IS-HETE and fibronectin both spontaneously (p <0.002, p <0.05, respectively) or after stimulation with calcium ionophore compared with normals. On the other hand, PGE2 release was significantly higher only after stimulation with calcium ionophore (p <0.002). The spontaneous expression of HLA-DR and ICAM-1 (p <0.001) was significantly higher on epithelial cells from asthmatics than in normal subjects. Finally, the severity of asthma significantly correlated with the release of LS-HETE (p<0.02) and the expression of HLA-DR and ICAM- I respectively (p <0.001 and p <0.002, respectively). This study indicates that bronchial epithelial cells are in an activated state in asthma and that the degree of activation is correlated to the severity of the disease.     

支气管哮喘与Th1/Th2/Th17的相关性分析

支气管哮喘是一种涉及多种临床症状,例如咳嗽、气喘、呼吸困难等常见的呼吸系统疾病,其发病率之高严重威胁着人类的健康.哮喘的发病与遗传和环境都有着密切的联系,因其发病机制十分复杂至今尚未明了.众多的细胞及其细胞因子均参与了哮喘的发病过程,其中辅助性T细胞(Thelper,Th)及其亚群(Th1、Th2和Th17)已被证实与支气管哮喘的发生有着十分密切的关系.     

Inflammatory processes in asthma

Bronchial inflammation is a characteristic of asthma, but, although postmortem and rare bronchoscopic studies had been performed, it is only after 1980 that many experiments were done. Electron microscopy, immunohistochemistry and molecular biology have enhanced our knowledge. As bronchial biopsies and bronchoalveolar lavage present drawbacks, it is favorable to combine both to obtain the best insights into inflammation. The epithelium is rarely intact in asthmatic patients, the cells being both 'fragile' and activated. Eosinophil inflammation is highly important and likely involved in the damage of the epithelium and submucosa. Airway macrophages and monocytes are present in greater amounts and are activated in the bronchi, and they are certainly involved in the pathogenesis of asthma. Mast cells are activated and some emphasis has been put on lymphocytes. Therefore, asthma appears to be a desquamative bronchitis with mixed cell infiltrate.     

Airway hyperresponsiveness

Bronchial hyperresponsiveness (BHR) is an essential part of the definition of asthma. Although our understanding of the allergic inflammatory and immunologic mechanisms of asthma have markedly increased, the mechanism of BHR remains to be elucidated. Increased BHR is associated temporally with exposure to allergens, certain respiratory viruses, pollutants such as ozone, and certain occupational chemicals. An important research use of determining the degree of BHR to direct and indirect challenge is to determine the efficacy of pharmacologic and immunodulatory agents. Beta-adrenergic agents inhibit BHR and certain genetic polymorphisms of the beta-adrenergic receptor are associated with increased BHR. When β-adrenergic receptors are blocked, sensitivity to allergens is markedly increased in patients with asthma and animal models of asthma. Allergen challenge and clinical asthma are associated with synthesis and release of pro-inflammatory cytokines such as IL-1 and TNF-α which have been shown to decrease the response to β-agonists and increased the reactivity to methacholine and the airways neutrophils and alveolar macrophages. The Th2 cytokine IL-13 is increased in the airways of asthmatics and increases BHR in normal unsensitized animals. The mechanisms of this effect of IL-13 are being intensively investigated. Our group has shown that IL-13 induced BHR persisted for at least 7 days and the soluble receptor IL-13R2α protected against their BHR. Other investigators have demonstrated that IL-13 is necessary and sufficient for the induction of BHR and that eosinophilic airway inflammation in the absence of IL-13 fails to induce BHR. These studies indicate that treatment of human asthma with antagonists of IL-13 may be very effective.     

Anti-inflammatory drugs do not alleviate bronchial hyperreactivity in Sjögren's syndrome

Bronchial hyperreactivity (BHR) is found in Sjögren's syndrome, as in a number of other conditions such as asthma. BHR associated with asthma can be effectively treated with corticosteroids or sodium cromoglycate. We treated 19 Sjögren's syndrome patients with BHR with inhaled budesonide and inhaled cromoglycate for 6 weeks each. None of the treatments had any significant effect on symptoms of hyperreactivity or lung function. There was no effect on BHR measured as methacholine reactivity. Primary Sjögren's syndrome is a disease with inflammation not only in the salivary and lacrimal glands but also in the pulmonary alveoli and the bronchi. The main inflammatory cell is the lymphocyte, whereas, in the bronchi in asthma, the eosinophil granulocyte is the characteristic inflammatory cell. The cause of the discrepancy with regard to treatability of BHR in asthma and in Sjögren's syndrome is not known. Possibly not all BHR is caused by inflammation. There is not a perfect correlation between inflammation and hyperreactivity even in asthma. Even if the bronchial inflammation and the asthma symptoms are easy to treat with anti-inflammatory medicines, a considerable component of BHR usually still remains, as measured with methacholine or histamine.     

非特异性免疫疗法在支气管哮喘治疗中的应用进展

支气管哮喘是呼吸系统的常见病及多发病之一,其是由嗜酸性粒细胞、肥大细胞、T淋巴细胞、中性粒细胞等多种细胞及细胞组分参与的气道慢性过敏反应炎症性疾病,在全球范围内的发病率及死亡率不断上升,严重影响公众健康和患者生活质量。研究发现,支气管哮喘的发病涉及机体免疫紊乱,Th1/Th2细胞比例失衡是哮喘发病的重要机制,在此基础上,支气管哮喘的免疫疗法取得一定进展,本文基于支气管哮喘的免疫学机制,对非特异性免疫疗法在支气管哮喘治疗中的研究及应用进展进行综述,以期为支气管哮喘的治疗提供新的方向和思路。     

Papain-induced asthma—physiological and immunological features

Increasing reports of respiratory disease associated with exposure to papain prompted clinical, physiological, and immunological studies of the supervisor of a meat tenderizer factory who developed asthma after long-term contact with papain dust. His symptoms were worse at work and better on weekends and vacations. Bronchial inhalation challenges produced both immediate and late asthma to papain but not to the other ingredients in the food product. Immunological studies revealed the presence of specific IgE antibodies by direct and passive transfer skin tests and the radioallergosorbent test, and specific precipitating antibodies by immunodiffusion tests. These findings are indicative of a dual type I and III hypersensitivity. Papain acting as an allergen in an occupational setting is a risk factor for eliciting asthma even in a nonatopic individual.     

Immunopathogenesis of bronchial asthma

Bronchial asthma is a common immune-mediated disorder characterized by reversible airway inflammation, mucus production, and variable airflow obstruction with airway hyperresponsiveness. Allergen exposure results in the activation of numerous cells of the immune system, of which dendritic cells (DCs) and Th2 lymphocytes are of paramount importance. Although the epithelium was initially considered to function solely as a physical barrier, it is now evident that it plays a central role in the Th2-cell sensitization process due to its ability to activate DCs. Cytokines are inevitable factors in driving immune responses. To the list of numerous cytokines already known to be involved in the regulation of allergic reactions, new cytokines were added, such as TSLP, IL-25, and IL-33. IgE is also a central player in the allergic response. The activity of IgE is associated with a network of proteins, especially with its high- and low-affinity Fc receptors. Understanding the cellular and molecular mechanisms of allergic reactions helps us not only to understand the mechanisms of current treatments, but is also important for the identification of new targets for biological intervention. An IgE-specific monoclonal antibody, omalizumab, has already reached the clinic and similar biological agents will surely follow.     

Dendritic cells in normal and asthmatic airways: expression of the α subunit of the high affinity immunoglobulin E receptor (FcεRI-α)

Background Immunoglobulin E (IgE) plays an important role in asthma, with total serum IgE levels closely related to both clinical expression of the disease and airway hyperresponsiveness. IgE binds to a high affinity cell-surface receptor (FcεRI) which is present on mast cells and which has also recently been demonstrated on cutaneous dendritic cells. If pulmonary dendritic cells were also able to express this receptor, this would have important implications with regard to their potential role in asthma. Objectives The aims of the study were to investigate the expression of the α subunit of the high affinity IgE receptor (FcεRI-α) in normal and asthmatic airways, and to analyse its cellular provenance with particular emphasis on the dendritic cell. Methods Bronchial biopsy specimens were obtained using fibreoptic bronchoscopy from 10 atopic asthmatics and nine non-atopic non-asthmatic control subjects. Specimens were processed into glycolmethacrylate resin and analysed by immunohistochemistry using specific monoclonal antibodies against FcεRI-α. and against tryptase and CDla. markers for mast cells and dendritic cells, respectively. Results The numbers of dendritic cells were significantly higher in the airways of asthmatics compared with those of control subjects (P<0.02). Analysis of sequential sections revealed that the α subunit of FcεRI was localized to both mast eells and dendritic cells. The proportion of dendritic cells expressing FcεRI-α was significantly inereased in the asthmatic group (P < 0.003). Conclusion These results support the hypothesis that dendritic cells play an important role in allergic asthma although the functional significance of FcεRI-α expression needs further investigation.     

The bronchial microcirculation in asthma

Airway wall remodelling in asthma involves a number of changes including increased vascularity, vasodilation and microvascular leakage. Evidence suggests that the number and size of bronchial vessels is increased in patients with asthma compared with normal controls. In particular, there may be increased numbers of vessels in patients with fatal asthma. Treatment with inhaled corticosteroids is now known to reduce this vascularity. Bronchial vessels may undergo proliferation in response to inflammatory stimuli. Many factors can induce angiogenesis including a range of mediators and growth factors. Others can cause a vascular response by causing vasodilation and microvascular leakage. Airway wall oedema is likely to be important in asthma but has not yet been quantified. It is thought that mast cells play a key role in modulating these vascular remodelling changes by releasing cytokines and growth factors. Many key issues remain to be resolved before we fully understand the role of the bronchial microcirculation in asthma. In the future, novel therapies may be directed towards angiogenesis, vasodilation and microvascular leakage.     

Expression of adhesion molecules in allergic lung diseases

Endothelial adherence and migration of leukocytes into tissue is mediated by different sets of adhesion molecules. The expression of these sets might not only preselect the types of leukocytes that enter the inflammatory sites, but also activate these leukocytes, induce adherence to epithelial cells, and cause the release of cytokines. Atopic asthma, extrinsic allergic alveolitis, and sarcoidosis as examples of immunologic lung diseases were investigated for the expression of adhesion molecules. Bronchial biopsies in chronic obstructive lung disease (COPD) and resected lung tissue of juvenile emphysema were chosen for controls. Immunohistochemistry was done on sections from bronchial and transbronchial biopsies and on smears from bronchoalveolar lavage cells. In all three types of immune disorders, lymphocytes expressed the integrins alpha4/beta1 (VLA4) and ICAM3, whereas lymphocytes in COPD bronchitis and in emphysema controls were unreactive. Eosinophils in atopic asthma bronchitis in contrast to COPD bronchitis also expressed both VLA4 and ICAM3. The expression of VCAM1 on endothelial cells was only seen in atopic asthma and was related to disease activity. The expression of other adhesion molecules was nonspecific. Expression of VCAM1 on endothelial cells and its ligand VLA4 on lymphocytes and eosinophils seems to be a specific event in atopic asthma. Expression of VLA4 and ICAM3 on lymphocytes, however, might be a specific event in all three immune reactions.     

The role of endogenous and exogenous AMP in asthma and chronic obstructive pulmonary disease

Bronchial hyperresponsiveness is present in virtually all patients with asthma and in more than two thirds of patients with chronic obstructive pulmonary disease. Thus far, methacholine and histamine are usually used to measure bronchial hyperresponsiveness. Both are direct stimuli, because they act directly on airway smooth muscle. Another possible stimulus to measure bronchial hyperresponsiveness is AMP. AMP is an indirect stimulus, because it acts via the release of histamine and other mediators from immunologically primed mast cells. There is increasing interest in the role of AMP as a bronchoconstrictor stimulus because it has been suggested that the concentration of AMP causing the FEV 1 to decrease by 20% (PC 20 AMP) may be used as a noninvasive marker of airway inflammation. The aim of this article was to review the literature assessing AMP's value in asthma and chronic obstructive pulmonary disease.     

The involvement of matrix metalloproteinase-9 in airway inflammation of patients with acute asthma

BACKGROUND: Bronchial asthma is an inflammatory disease of the airway characterized by airway remodelling, and is due at least in part to an excess of extracellular matrix (ECM) deposition in the airway wall, which leads to subepithelial collagen deposition. Matrix metalloproteinase-9 (MMP-9) is the major proteolytic enzyme that induces bronchial remodelling in asthma. MMP-9 is also important in the migration of inflammatory cells through basement membrane components. OBJECTIVES: We evaluated whether airway inflammatory cells correlated with levels of MMP-9 in acute asthma and we examined the time course of sputum levels of MMP-9 activity in patients with spontaneous asthma exacerbation. METHODS: We performed zymographic analysis and checked levels of MMP-9 by means of enzyme immunoassay. MMP-9 levels were also evaluated during a spontaneous attack of asthma. RESULTS: Pro-MMP-9 activities and concentrations of MMP-9 in asthmatic patients significantly exceeded those of control subjects (P < 0.01). The activities of pro-MMP-9 were significantly higher in acute asthmatic patients than in stable asthmatic patients (P < 0.01). The elevated MMP-9 activities significantly decreased after 7 and 28 days of therapy. In acute asthmatic patients, the levels of sputum MMP-9 significantly correlated with the total macrophage + neutrophil + eosinophil cell numbers. CONCLUSION: These data suggest that airway inflammation after asthma exacerbation correlates with the overproduction of MMP-9, which then leads to airway remodelling.     

Effects of suplatast tosilate on allergic eosinophilic airway inflammation in patients with mild asthma

BACKGROUND: Bronchial asthma is a chronic inflammatory disease characterized mainly by infiltration of the airway mucosa by various inflammatory cells, notably eosinophils. T(H)2-type cytokines are suggested to be deeply involved in the pathogenesis of asthma. OBJECTIVE: We sought to determine the suppressive effects of suplatast tosilate, an inhibitor of T(H)2-type cytokines, on eosinophilic inflammation of the bronchial mucosa in patients with mild asthma. METHODS: Airway hyperresponsiveness tests, pulmonary function tests, eosinophil measurements in induced sputum, and bronchial mucosa biopsies were performed before and after treatment with suplatast tosilate for 6 weeks in 15 patients with mild asthma and in 13 control patients with mild asthma not receiving suplatast tosilate. This study was performed as a case-controlled open study. RESULTS: In the treatment group a significant improvement in the provocation concentration of histamine was observed (P <.05). Improvements in peak expiratory flow (P <.01) and in symptom score (P <.05) were also noted in the suplatast tosilate-treated group. Moreover, the average number of infiltrating eosinophils and EG2(+) cells significantly decreased (both P <.05), as did the ratios of eosinophils and EG2(+) cells in sputum (both P <.01). The average number of CD4(+) and CD25(+) T lymphocytes also decreased (both P <.05). CONCLUSION: Suplatast tosilate appears to inhibit allergic airway inflammation mediated by T(H)2-type cytokine and to improve clinical symptoms in patients with mild asthma.