The relation between bronchial infiltration of eosinophils and bronchial hyperresponsiveness in two cases of eosinophilic pneumonia]

We evaluated the bronchial hyperresponsiveness to methacholine in the two cases of eosinophilic pneumonia with infiltration of eosinophils into bronchial mucosa. Bronchial responsiveness was not increased in either case in spite of marked infiltration of eosinophils into the bronchial mucosa and submucosa. Hypodense eosinophils are reported in the sputum of patients with bronchial asthma. This suggests that infiltration of activated eosinophils into the bronchial mucosa is an essential factor in bronchial hyperresponsiveness.     

气道上皮屏障功能异常在支气管哮喘发病中的作用

支气管哮喘(哮喘)的主要表现为咳嗽、咳痰、胸闷和喘息,这些症状的病理生理学基础是气道高反应性和气道慢性嗜酸粒细胞炎症。气道上皮细胞是呼吸道的第一道防线,环境因素和炎症作用的影响引起气道上皮反复损伤、修复和再生导致气道黏膜上皮的组织学改变和功能异常。气道上皮的屏障功能与气道上皮细胞因子胸腺基质淋巴细胞生成素,白细胞介素25和白细胞介素33密切相关,哮喘患者气道上皮屏障的损害增强了气道上皮黏膜对异物的通透性,引起气道上皮细胞、树突状细胞和先天性固有淋巴样细胞(ILC2s)的激活。气道上皮细胞的功能异常以及树突状细胞、Th2细胞和ILC2s的激活形成一个免疫病理单元,引起过敏性气道炎症,在哮喘的发病中发挥重要作用。     

Features and treatment of immediate and late asthmatic responses]

In atopic asthma, the antigen-induced airway reaction consists of three phases; (1) immediate asthmatic response, LAR, (2) late asthmatic response, LAR, and (3) post-late asthmatic response, pLAR. Election microscopic examination of biopsy specimens of the bronchial mucosa, and examination of desquamated bronchial epithelial cells in sputum after antigen challenge showed that eosinophil infiltration in the bronchial epithelium contributes to airway hyperresponsiveness in asthma. Since LAR and pLAR are considered to be inflammatory responses caused by eosinophil infiltration, suppression of the inflammation by anti-allergic drugs and corticosteroids is effective in the treatment of LAR and pLAR. PAF antagonists and immunosuppressive agents have been investigated for their use in asthma treatment because of their anti-inflammatory effects. In addition to these anti-inflammatory agents, an antagonist of leukotriene C4 and D4 which are potent bronchoconstricting mediators has been shown to suppress both IAR and LAR, suggesting its possible use in asthma treatment.     

Benefit from anti-inflammatory treatment during clinical remission of atopic asthma

STUDY OBJECTIVES: Subjects with atopic asthma often experience a disappearance of symptoms around puberty. However, airway inflammation and remodeling may persist. It is unknown whether those findings warrant prolonged anti-inflammatory treatment despite the absence of symptoms. In this study, we investigated whether a short course of combined anti-inflammatory treatment would, also in this specific patient population, diminish airway inflammation and/or remodeling. DESIGN: A double-blind, randomized placebo-controlled trial was conducted in 28 asymptomatic subjects with a history of atopic asthma, with established bronchial hyperresponsiveness to methacholine (MCh) as non-invasive indicator of ongoing airway pathology. INTERVENTIONS: Intervention consisted of the salmeterol/fluticasone propionate combination (SFC) product (50/250 microg bid via the Diskus inhaler) or placebo for 3 months. MEASUREMENTS: The change in lung function (FEV1), bronchial response to MCh and adenosine monophosphate (AMP), the fraction of nitric oxide in exhaled air (FENO) and quality of life (QOL) scores were measured. Also, bronchial biopsies were taken and cryo sections immunostained for eosinophils (major basic protein, MBP) and mast cells (tryptase and chymase) before and after treatment. The change in reticular basement membrane (RBM) thickness, one of the parameters of airway remodeling, was also determined. RESULTS: SFC treatment improved hyperresponsiveness to MCh (P = 0.014) as well as AMP (P = 0.011), and reduced FENO (P < 0.001) significantly as compared with placebo. Lung function tended to improve (NS). Furthermore, SFC treatment reduced tryptase in the subepithelium of bronchial biopsy specimens (P = 0.01), and slightly reduced RBM thickness (P = 0.05). However, eosinophils in (sub)epithelium were not significantly affected; neither were chymase levels, blood eosinophils or QOL scores. CONCLUSIONS: We found that 3 months of treatment with fluticasone propionate and salmeterol reduced airway hyperresponsiveness, FENO and tryptase density in the airway mucosa as markers of airway inflammation. MBP density in the airway mucosa and QOL were, however, unchanged. The clinical relevance of these findings, especially with respect to the long-term outcome, has not been determined yet.     

Inflammatory markers in bronchoalveolar lavage and in bronchial biopsy in asthma during remission

Bronchoalveolar lavage and BB were performed in 13 asthmatic and six healthy subjects to characterize cellular markers of inflammation in BAL and BB; to compare cellular profile of BAL with cell infiltration in BB; to examine the relationship between bronchial responsiveness and markers of inflammation in BAL and BB. Eosinophils and mast cells were increased in BAL in asthmatic subjects; eosinophils were positively correlated with neutrophils and mast cells. Epithelial shedding was present in nine asthmatic and five control subjects. Intraepithelial cells and cells in submucosa were increased in asthmatic subjects. Eosinophils and intraepithelial mast cells were higher. Thickened basement membrane was associated with more marked cell infiltration in submucosa. Ciliated cells in BAL relate to intraepithelial cells; cells in BAL broadly reflect cell infiltration of submucosa. In the asthmatic group, the degree of bronchial responsiveness correlated with ciliated cells in BAL and with intra-epithelial cells in BB. Marked airway inflammation is associated with stable asthma; inflammatory changes within bronchial epithelium may be linked to the development of bronchial hyperresponsiveness.     

Understanding asthma pathophysiology.

Asthma is best described as a chronic disease that involves inflammation of the pulmonary airways and bronchial hyperresponsiveness that results in the clinical expression of a lower airway obstruction that usually is reversible. Physiologically, bronchial hyperresponsiveness is documented by decreased bronchial airflow after bronchoprovocation with methacholine or histamine. Other triggers that provoke airway obstruction include cold air, exercise, viral upper respiratory infection, cigarette smoke, and respiratory allergens. Bronchial provocation with allergen induces a prompt early phase immunoglobulin E (IgE)-mediated decrease in bronchial airflow (forced expiratory volume in 1 second) followed in many patients by a late-phase IgE-mediated reaction with a decrease in bronchial airflow for 4-8 hours. The gross pathology of asthmatic airways displays lung hyperinflation, smooth muscle hypertrophy, lamina reticularis thickening, mucosal edema, epithelial cell sloughing, cilia cell disruption, and mucus gland hypersecretion. Microscopically, asthma is characterized by the presence of increased numbers of eosinophils, neutrophils, lymphocytes, and plasma cells in the bronchial tissues, bronchial secretions, and mucus. Initially, there is recruitment of leukocytes from the bloodstream to the airway by activated CD4 T-lymphocytes. The activated T-lymphocytes also direct the release of inflammatory mediators from eosinophils, mast cells, and lymphocytes. In addition, the subclass 2 helper T-lymphocytes subset of activated T-lymphocytes produces interleukin (IL)-4, IL-5, and IL-13. IL-4 in conjunction with IL-13 signals the switch from IgM to IgE antibodies. The cross-linkage of two IgE molecules by allergen causes mast cells to degranulate, releasing histamine, leukotrienes, and other mediators that perpetuate the airway inflammation. IL-5 activates the recruitment and activation of eosinophils. The activated mast cells and eosinophils also generate their cytokines that help to perpetuate the inflammation. Regardless of the triggers of asthma, the repeated cycles of inflammation in the lungs with injury to the pulmonary tissues followed by repair may produce long-term structural changes ("remodeling") of the airways. This review will discuss in greater detail the relationships of inflammation and airway hyperresponsiveness to the pathophysiology of asthma.     

Cellular localization of interleukin 13 receptor alpha2 in human primary bronchial epithelial cells and fibroblasts.

BACKGROUND: Interleukin (IL) 13 is a key cytokine in asthma, regulating fibrosis, airway remodeling, induction of immunoglobulin E synthesis by B cells, bronchial hyperresponsiveness, and mucus production. IL-13 signals through the type II IL-4 receptor (IL-4R), which is composed of the IL-4Ralpha and the IL-13Ralpha1 chains. Another IL-13 binding chain, IL-13Ralpha2, binds IL-13 with high affinity but has no known signaling capability and is thought to serve as a decoy receptor providing tight regulation of IL-13 responses. METHODS: In this study, we investigated the cellular localization of IL-13Ralpha2 in human primary bronchial epithelial cells and fibroblasts using flow cytometry and confocal microscopy, as well as the in vivo expression of IL-13Ralpha2 in the human bronchial mucosa by means of immunohistochemistry. RESULTS: IL-13Ralpha2 is predominantly an intracellular rather than a membrane-bound molecule in both human primary bronchial epithelial cells and fibroblasts and displays a diffuse granular cytoplasmic distribution in both cell types. IL-13Ralpha2 protein is expressed in vivo in the human bronchial mucosa with its expression being higher in bronchial epithelial cells than bronchial fibroblasts both in vivo and in vitro. CONCLUSIONS: IL-13Ralpha2 is expressed by both human primary bronchial epithelial cells and fibroblasts as an intracellular protein with a diffuse cytoplasmic distribution. In vivo, IL-13Ralpha2 is expressed in the human airway mucosa mainly by bronchial epithelial cells.     

Effects of treatment with anti-immunoglobulin E antibody omalizumab on airway inflammation in allergic asthma

IgE plays an important role in allergic asthma. We hypothesized that reducing IgE in the airway mucosa would reduce airway inflammation. Forty-five patients with mild to moderate persistent asthma with sputum eosinophilia of 2% or more were treated with humanized monoclonal antibody against IgE (omalizumab) (n = 22) or placebo (n = 23) for 16 weeks. Outcomes included inflammatory cells in induced sputum and bronchial biopsies, and methacholine responsiveness. Treatment with omalizumab resulted in marked reduction of serum IgE and a reduction of IgE+ cells in the airway mucosa. The mean percentage sputum eosinophil count decreased significantly (p < 0.001) from 6.6 to 1.7% in the omalizumab group, a reduction significantly (p = 0.05) greater than with placebo (8.5 to 7.0%). This was associated with a significant reduction in tissue eosinophils; cells positive for the high-affinity Fc receptor for IgE; CD3+, CD4+, and CD8+ T lymphocytes; B lymphocytes; and cells staining for interleukin-4, but not with improvement in airway hyperresponsiveness to methacholine. This study shows antiinflammatory effects of omalizumab treatment and provides clues for mechanisms whereby omalizumab reduces asthma exacerbations and other asthma outcomes in more severe asthma. The lack of effect of omalizumab on methacholine responsiveness suggests that IgE or eosinophils may not be causally linked to airway hyperresponsiveness to methacholine in mild to moderate asthma.     

Eosinophils and mast cells in bronchoalveolar lavage in subjects with mild asthma. Relationship to bronchial hyperreactivity

We have performed bronchoalveolar lavage (BAL) on 17 subjects with mild atopic asthma (9 symptomatic, 8 asymptomatic) and 14 nonasthmatic control subjects (6 hay fever, 8 nonatopic). There was a significant increase in the percentage of mast cells in both groups of asthmatics although the counts were no different from those previously reported for a number of other respiratory diseases. Asthmatics with airway hyperreactivity (PC20 less than 4 mg/ml) had significant increases in spontaneous histamine release. There was a significant elevation in the eosinophil count and the concentration of major basic protein (MBP) in BAL fluid in the symptomatic asthmatics. Furthermore, there was a significant correlation between the amounts of MBP recovered and the percentage of eosinophils in the BAL. These changes were even more marked when asthmatics with airway hyperreactivity were compared with subjects with normoreactive airways. In addition, there was a significant increase in the percentage of epithelial cells in the hyperreactive asthmatics. There was an inverse correlation between the PC20 and the percentage of mast cells (p less than 0.01), eosinophils (p less than 0.05), and epithelial cells (p less than 0.05) and amount of MBP in BAL (p less than 0.01). This study supports the hypothesis that bronchial hyperresponsiveness is secondary to epithelial cell damage mediated through eosinophil-derived granule products.     

Mechanisms of airway remodeling in asthma.

Asthma is a chronic inflammatory disease characterized by reversible airflow limitation and airway hyperresponsiveness. Persistent inflammation in airway tissues may lead to structural changes known as airway remodeling and consequently airway obstruction that is not fully reversible and progressive loss of lung function over time. It is generally accepted that airway remodeling is closely related to progression of airway hyperresponsiveness, and the severity of asthma. The structural changes observed in chronic persistent asthma, which includes airway smooth muscle hypertrophy and hyperplasia, collagen deposition to sub-epithelial basement membrane, hyperplasia of goblet cells, thickening of airway mucosa and an increase in vascularity, are derived from airway inflammation. For instance, the thickened airway mucosa might be produced by cytokines and growth factors released from inflammatory cells and airway epithelial cells, and associated with bronchial hyperreactivity and asthma severity. To date, many studies have identified candidate mechanisms and mediators for these observed structural changes, which are thus potential targets in the treatment of asthma. In this review, we describe the recent knowledge of the mechanisms and clinical implications of airway remodeling in asthma.     

Bronchial hyperresponsiveness in asthmatic children. Correlation with macrophages and eosinophils in broncholavage fluid

Bronchial responsiveness assessed by histamine bronchial challenge testing in 22 children with chronic stable asthma was compared with the number of inflammatory cells per milliliter of broncholavage fluid obtained by fiberoptic bronchoscopy. Hyperresponsiveness was closely correlated with increased counts of eosinophils and macrophages and with the ratio of eosinophils to macrophages. There was no correlation of neutrophil or lymphocyte counts with bronchial hyperresponsiveness and none of the cell types was correlated with airway obstruction. Our findings support the hypotheses that macrophages may be important in the development of bronchial hyperresponsiveness in children with asthma and that they may modulate bronchial responsiveness both directly and by recruitment of eosinophils.     

Immunohistochemical analysis of bronchial mucosa in severe asthmatics treated with long-term, high-dose inhaled BDP]

To analyze specific mucosal changes in asthmatic patients receiving long-term, high-dose beclomethazone dipropionate (BDP) inhalation therapy, we performed bronchial mucosal biopsies and immunohistochemical analysis of patients who had been treated with or without BDP-inhalation. Our study enrolled 6 chronic severe asthmatics who were treated with 1,800 micrograms/day or more of BDP with regular use for more than 3 years (HD-BDP group), 6 mild asthmatics who were not treated with BDP (non-BDP group), and 6 control subjects. Specimens of bronchial mucosa were stained with anti-EG 2 (eosinophils), anti-UCHLA-1 (T lymphocytes) and anti-tryptase (mast cells). Although limited eosinophil infiltration was observed in the HD-BDP and control groups, a significant increase was noted in the non-BDP group. The infiltration of both T lymphocytes and mast cells exhibited a statistically significant increase in the non-BDP group compared to the HD-BDP and control groups. In chronic severe asthmatics, airway mucosal cell infiltration was reduced by high-dose and long-term inhaled BDP therapy, and BDP also relieved their asthmatic symptoms. However, in mild asthmatics, bronchial mucosal cell infiltration remained high. For such patients, we concluded that initiating BDP therapy from an early stage may bring clinical improvement and help prevent cell infiltration.     

Histological changes of the liver in experimental graft-versus-host disease across minor histocompatibility barriers. VIII. Role of eosinophil infiltration

Abstract: Although eosinophil infiltrate has been recognized in hepatic graft-versus-host disease, its significance in relation to hepatic graft-versus-host disease lesions is unknown. In the present study, we analyzed hepatic eosinophil infiltration in relation to bile duct damage in experimental mouse graft-versus-host disease across minor histocompatibility barriers up to 14 months after transplantation. Portal eosinophil infiltration was found from 1 week after transplantation throughout the entire 14-month observation period. It was most striking during the early chronic stage of hepatic graft-versus-host disease between 2 to 7 months, with a peak at 5 months after transplantation. Microscopic and electron microscopic study revealed eosinophils infiltrated around the bile duct as well as in the bile duct epithelial layer. They were commonly found together with lymphocytes but were also occasionally found singly around the bile duct and in the bile duct epithelial layer. Bile duct epithelial cells in contact with and in the vicinity of eosinophils showed a variety of degenerative changes, occasionally associated with the presence of extracellular eosinophil granules. Bile duct epithelial cells with eosinophil infiltration just beneath the basement membrane frequently showed further characteristic severe degenerative changes with shedding or dropping-off into the lumen, which features were quite similar to those seen in the bronchial epithelium in asthma patients. These results indicate that not only lymphocytes but also eosinophils may be involved in the production of the bile duct injury in hepatic graft-versus-host disease, especially in its early chronic stage.     

儿童百日咳与支气管哮喘关系的研究进展

支气管哮喘(哮喘)是一种多因素异质性疾病,严重影响儿童的身心健康。对于其发病原因及机制的研究一直是学者们关注的重点。近年来,呼吸道合胞病毒、鼻病毒、肺炎支原体等病原体感染与哮喘的关系逐渐明确,但是百日咳与哮喘之间的关系尚不明确。有研究认为百日咳杆菌感染后可诱导IgE的产生、激活Th2细胞并诱导Th17免疫应答,加强中性...     

水通道蛋白敲除对支气管哮喘小鼠气道黏蛋白谱表达的影响

目的水通道蛋白5（aquaporin5,AQP5）敲除对支气管哮喘（简称哮喘）小鼠气道黏蛋白（MUC）谱表达的影响。方法用卵白蛋白致敏和激发制备AQP5敲除鼠的哮喘高分泌模型。用苏木精-伊红染色观察气道及血管周围炎性细胞浸润。阿辛兰-过碘酸雪夫检测显示气道上皮细胞总黏液分泌,免疫组织化学检测气道上皮MUC5AC,MUC5B,MUC2的表达情况。结果哮喘小鼠气道和血管周围可见大量中性粒细胞,淋巴细胞和嗜酸粒细胞浸润,气道上皮有大量的紫红色中性黏液分布,其中以AQP5敲除鼠总黏液分布更多。免疫组织化学显示小鼠哮喘高分泌模型中MUC谱主要为MUC5AC和MUC5B,未见MUC2分布。与野生型哮喘小鼠比较,MUC5AC、MUC5B在AQP5敲除鼠中表达更丰富。结论AQP5基因缺失可能使小鼠气道对过敏原的应激性提高,从而促进黏液高分泌。     

Effect of cessation of exposure to toluene diisocyanate (TDI) on bronchial mucosa of subjects with TDI-induced asthma.

The effect of cessation of exposure to toluene diisocyanate (TDI) was studied in six patients with TDI-induced asthma, proved by a positive inhalation challenge with TDI. Bronchial challenges with TDI and methacholine were performed, and lobar bronchial biopsies were taken at diagnosis and 6 months later, after cessation of exposure. Biopsies from four nonasthmatic control subjects were also examined. At diagnosis, asthmatic subjects had thickened reticular basement membrane (p less than 0.05) and increased numbers of mononuclear cells (p less than 0.05) and eosinophils (p less than 0.05) in the lamina propria when compared with control subjects. Electron microscopy showed degranulation of eosinophils and mast cells in asthmatics. Six months after cessation of exposure, the thickness of reticular basement membrane was significantly reduced compared with that at diagnosis (p less than 0.05), and it decreased to values similar to those of control biopsies. Inflammatory cell numbers in bronchial mucosa of asthmatic subjects did not change significantly 6 months after removal from exposure, and degranulation of eosinophils and mast cells was still present. At the end of the study, airway hyperresponsiveness to methacholine and/or sensitivity to TDI persisted in most of the asthmatic patients despite the cessation of exposure and the disappearance of asthmatic symptoms. In conclusion, in patients with occupational asthma induced by TDI, the avoidance of exposure to the sensitizing agent for 6 months is able to reverse the reticular basement membrane thickening in the bronchial mucosa, but the inflammatory cell infiltrate, the specific sensitivity to TDI, and the nonspecific airway hyperreactivity may persist.     

A case of allergic bronchopulmonary aspergillosis with no history of bronchial asthma]

A 53-year-old male was admitted to our hospital because of an abnormal shadow in the left upper lung. Bronchofiberscopy revealed edematous mucosa and pus at the orifice of the left upper lobe bronchus. Pathological examination revealed bronchial inflammatory change with infiltration of eosinophils and also the existence of aspergillus in the pus. Mild eosinophilia and elevation of serum IgE level were observed in the peripheral blood, and serum precipitin against Aspergillus fumigatus was positive. Bronchogram showed central bronchiectasis, and the diagnosis of allergic bronchopulmonary aspergillosis (ABPA) was made. In cases of ABPA, bronchial asthma is usually present prior to presentation, but this patient had no history of asthma even though airway hyperresponsiveness to methacholine was confirmed.     

Chronic inflammation is associated with an increased proportion of goblet cells recovered by bronchial lavage

To evaluate the possibility that bronchoalveolar lavage could provide sufficient respiratory epithelial cells to quantify changes in epithelial cell types associated with chronic inflammation, we examined the epithelial cells obtained in the first infused (20 ml) aliquots that were processed separately from later aliquots, a process known to enrich for bronchial contents. Epithelial cells, including ciliated cells, goblet cells, and fragments of desquamated epithelium, were easily identified after preparation by cytocentrifugation and staining with a modified Giemsa stain. Quantification of the columnar cell types revealed that those with chronic bronchitis and asymptomatic smokers have increased goblet cells as a percentage of the total columnar epithelial cells (chronic bronchitics 36 +/- 2 percent, asymptomatic smokers 22 +/- 2 percent) compared with normal subjects (9 +/- 1 percent, p less than 0.001, ANOVA). Significantly, the goblet cell percentage was strongly correlated with other measures of bronchitis and measures of airflow obstruction such as the bronchitis index, a visually derived score at bronchoscopy of airway inflammation (r = 0.72, p less than 0.001), the percent neutrophils in the first infused aliquots (r = 0.44, p less than 0.05), and the FEV1 percent (r = -0.74, p less than 0.001). Thus, bronchoalveolar lavage is capable of providing sufficient bronchial epithelial cells for analysis, and the changes seen in the spectrum of columnar epithelial cells may reflect important underlying pathologic changes.     

神经生长因子与支气管哮喘

神经生长因子(nerve growth factor,NGF)对神经细胞的生长、分化、存活、维持均起着重要作用,NGF还通过调节多种免疫细胞,促进炎性介质释放,导致气道炎症,诱导神经元可塑性.NGF水平在支气管哮喘患者血清、痰液、支气管肺泡灌洗液、支气管黏膜中均有明显升高.本文就NGF的生物学特征、调节以及与支气管哮喘的3个主要特征气道炎症、气道高反应性和气道重塑的关系作一综述.     

Quantitation of mast cells and eosinophils in the bronchial mucosa of symptomatic atopic asthmatics and healthy control subjects using immunohistochemistry

We have used fiberoptic bronchoscopy to obtain endobronchial biopsies in which mast cells and eosinophils were enumerated using monoclonal antibodies directed against mast cell tryptase (AA1) and the eosinophil cationic protein (EG2). Eleven symptomatic atopic asthmatics treated with beta 2-agonists alone and six normal subjects were studied. Over a period of 2 wk prior to bronchoscopy, patients recorded asthma symptom scores, bronchodilator usage, and twice-daily peak expiratory flow. Five days before bronchoscopy, methacholine responsiveness was assessed. Two biopsies were taken from the subcarinae, one of which was processed into araldite for immunostaining by the streptavidin biotin immunoperoxidase method and the other into Spurr resin for electron microscopy. The number of AA1 staining mast cells present in the bronchial mucosa was not significantly different in the epithelium or submucosa between the asthmatic and the normal subjects. However, in the biopsies from asthmatics, there were significantly greater numbers of EG2-staining eosinophils in the epithelium (median, 1.2/mm versus zero; p less than 0.005) and in the submucosa (median, 50/mm2 versus 1/mm2; p less than 0.001). Electron microscopy showed morphologic features of mast cell and eosinophil degranulation in the asthmatics. No correlation could be established between mast cell or eosinophil numbers and indices of disease activity of PC20 methacholine, which points to the complexity of mechanisms responsible for the symptoms and the airway hyperresponsiveness of asthma.