Relation of epidermal growth factor receptor expression to mucus hypersecretion in diffuse panbronchiolitis

STUDY OBJECT: Diffuse panbronchiolitis (DPB) is a hypersecretory airway disease, and the mechanism of mucus hypersecretion in DPB is poorly understood. Moreover, mucin synthesis in the airways has been reported to be regulated by neutrophilic inflammation-induced epidermal growth factor receptor (EGFR) expression, and the degranulation of goblet cells is known to be mediated by neutrophilic elastase. In this study, we examined the relationship between EGFR expression in the bronchiolar epithelium with neutrophilic inflammation and mucus hypersecretion in the tissues of DPB patients. DESIGN: The tissue specimens of 13 DPB patients and 6 healthy control subjects were examined by alcian blue/periodic acid-Schiff (AB/PAS) staining for mucous glycoconjugates, and by immunohistochemical staining for MUC5AC, EGFR, tumor necrosis factor-alpha, and CD16 on neutrophils. RESULTS: Neutrophilic inflammation was significantly higher in the tissue of DPB patients than in that of control subjects (p = 0.002). In the bronchiolar epithelium, goblet cell metaplasia, by AB/PAS staining and mucin MUC5AC expression, was significantly higher than that in control subjects (p = 0.001 and p = 0.002, respectively). In addition, the morphometric quantification of intraluminal mucus secretion showed that the areas of the bronchiolar lumen occupied by mucus secretion were significantly increased in the tissue of DPB patients (p = 0.001), suggesting goblet cell degranulation. EGFR expression was observed in the bronchiolar epithelium of DPB patients, but not in that of control subjects. CONCLUSIONS: In DPB, we suggest that mucus hypersecretion due to goblet cell metaplasia is closely associated with neutrophilic inflammation and the expression of EGFR. The study also shows that intraluminal secretion due to the degranulation of goblet cells degranulation is related to neutrophilic inflammation.     

Niflumic acid inhibits goblet cell degranulation in a guinea pig asthma model

Background: Human Ca^2 +-activated Cl ion channel 1 (hCLCAl) is expressed in goblet cell hyperplasia in the airway of asthmatics, and murine CLCA3 is associated with antigen-sensitized and IL-13-induced goblet cell metaplasia in mice. However, the role of CLCA in goblet cell degranulation is not fully investigated. Niflumic acid (NFA), a relatively specific CLCA inhibitor, inhibits goblet cell metaplasia, but the effect of NFA on goblet cell degranulation has not been determined in an asthma model.Methods: Guinea pigs were sensitized with ovalbumin (OA) twice and then challenged with saline, OA, histamine, and one of the Ca^2 + -dependent secretagogues, UTP. The PAS/AB-stained mucus area in the tracheal epithelium was measured with a computer image analysis system, and the morphology of mucus granules was examined by transmission electron microscopy. In the in vitro experiment, goblet cells cultured with IL-13 at the air-liquid interface were stimulated with UTP in the presence or absence of NFA, and the MUC5AC level in cell lysates was measured by ELISA.Results: The mucus areas were smaller in the OA-, histamine-, and UTP-challenged animals than in the saline-challenged animals. NFA inhibited the decrease in mucus area and morphological changes in mucus granules. UTP caused swelling and exocytosis of mucus granules and MUC5AC secretion by cultured goblet cells, and NFA inhibited these changes.Conclusions: NFA inhibited the secretory response of mucus granules in an asthma model, suggesting that CLCA may be associated with goblet cell degranulation and that CLCA inhibitors may be useful for the treatment of hypersecretion in asthma.     

Mucus and MUC in asthma

PURPOSE OF REVIEW: Asthma is characterized by chronic airway inflammation and a mucus hypersecretory phenotype comprising excess mucus secretion, goblet cell hyperplasia and submucosal gland hypertrophy. This augmented mucus secretion has been relatively undervalued in asthma compared with airway inflammation. However, mucus plugging contributes to airflow limitation and airway hyperresponsiveness, and to morbidity and mortality in asthma. We review recent contributions to this field and therapeutic avenues to control mucus hypersecretion. RECENT FINDINGS: A distinct mucus hypersecretory phenotype may present in asthma. Overexpression of MUC5AC, MUC5B and MUC2 have been described in asthma secretions, but identification of defined biochemical abnormalities and polymorphisms of mucin genes linked to asthma remains elusive. Activation of epidermal growth factor receptor (EGFR) activation appears central in transducing many different stimuli, including oxidative stress, proteases and cytokines. In contrast, nitrosative stress has barely been investigated. The existence of crosstalk between EGFR and other receptor systems may provide new clues regarding the activity of acetylcholine, adenosine and other agonists of G-protein-coupled receptors and other receptor families on mucin secretion. Modern techniques for noninvasive detection of mucus pathology will advance clinical research in this field. SUMMARY: Airway mucus hypersecretion as a part of airway remodelling represents a problem in asthma, and studies of pathophysiology and therapeutic approaches are therefore warranted. Identification of targets such as the EGFR cascade, which are crucial in excessive and abnormal mucus secretion, may lead to the rational design of new antihypersecretory drugs that may enhance future asthma treatment.     

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(aquaporin 5,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.     

气道黏液高分泌及其调节

正常情况下气道黏膜下腺体在MUC5B调控下分泌少量黏液,具有吸附吸入的微粒及病原菌等屏障作用;病理状态下存在黏液细胞增生、化生,黏液过度分泌导致气道狭窄.气道黏液高分泌的机制复杂,且针对高分泌目前缺乏有效治疗手段.新近研究显示,气道黏蛋白基因上调及其下游信号的激活是上述病理改变的基础.调控黏蛋白基因抑或成为未来治疗气道黏液高分泌的方向.     

Increased leukotrienes in exhaled breath condensate in childhood asthma

Cysteinyl leukotrienes (cys-LTs; LTC4, LTD4, and LTE4) are generated predominantly by mast cells and eosinophils and induce airway smooth muscle contraction, microvascular leakage, and mucous hypersecretion whereas leukotriene B4 (LTB4) is a potent chemoattractant of neutrophils. We measured cys-LTs and LTB4 in exhaled breath condensate from children aged 7-14 years including healthy nonatopic children (n = 11) and children with mild intermittent asthma (steroid naive, n = 11), mild persistent asthma (low-dose inhaled steroid treatment, n = 13), or moderate to severe persistent asthma (high-dose inhaled steroid treatment, n = 13). Exhaled LTB4 levels were increased in patients with mild and moderate to severe persistent asthma compared with patients with mild intermittent asthma (126.0 +/- 8.8 and 131.9 +/- 7.1 versus 52.7 +/- 3.8 pg/ml, p < 0.001 and p < 0.0001) and normal subjects (126.0 +/- 8.8 and 131.9 +/- 7.1 versus 47.9 +/- 4.1 pg/ml, p < 0.0001). Elevated exhaled cys-LT levels were found in patients with mild and moderate to severe persistent asthma compared with normal subjects (27.9 +/- 2.8 and 31.5 +/- 4.5 versus 18.5 +/- 0.5 pg/ml, p < 0.01 and p < 0.05). There was an inverse correlation between exhaled cys-LTs and LTB4 in patients with mild persistent asthma. We conclude that exhaled cys-LTs and LTB4 may be noninvasive markers of airway inflammation in pediatric asthma.     

Differential regulation by glucocorticoid of interleukin-13-induced eosinophilia,hyperresponsiveness, and goblet cell hyperplasia in mouse airways

Interleukin (IL)-13 induces important features of bronchial asthma such as eosinophilic infiltration, airway hyperresponsiveness (AHR), and mucus hypersecretion. Although glucocorticoids suppress airway inflammation and remain the most effective therapy for asthma, the effects of glucocorticoids on the IL-13-dependent features are unknown. We studied the effects of dexamethasone on eotaxin production, eosinophil accumulation, goblet cell hyperplasia, and AHR after IL-13 administration into the airways of mice in vivo. MUC5AC gene expression, a marker of goblet cell hyperplasia, was also analyzed. IL-13 alone dose dependently induced AHR. Treatment with dexamethasone inhibited eotaxin expression and completely abolished eosinophil accumulation, but it did not affect AHR, MUC5AC overexpression, or goblet cell hyperplasia induced by IL-13. The effects of tumor necrosis factor-alpha on IL-13-induced AHR were also examined. Tumor necrosis factor-alpha did not affect AHR despite marked enhancement of eosinophil infiltration in IL-13-treated mice. These findings suggest that glucocorticoid is not sufficient to suppress IL-13-induced AHR or goblet cell hyperplasia and that eotaxin expression and eosinophilic inflammation do not have a causal relationship to the induction of AHR or goblet cell hyperplasia by IL-13. Control of steroid-resistant features induced by IL-13, including AHR and mucus production, may provide new therapeutic modalities for asthma.     

The inhibitory effects of rebamipide on cigarette smoke-induced airway mucin production

Cigarette smoke may be the main cause of chronic bronchitis. Exposure of cigarette smoke induces the recruitment of inflammatory cells in the airway epithelium, and release of the tumor necrosis factor alpha (TNFalpha) from airways. Previous reports have shown that cigarette smoke induces goblet cell metaplasia by activating an epidermal growth factor receptor (EGFR) cascade, and that this results in mucin production. Rebamipide (2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinon-4-yl] propionic acid, OPC-12759) directly inhibits the production of superoxide (O2-) and inhibits proinflammatory cytokines (such as TNFalpha and IL-8). In the present study, we aimed to analyze the inhibitory effects of rebamipide on TNFalpha and EGFR activation after cigarette smoke treatment in vitro and in vivo. NCl-H292 cells and Sprague-Dawley rats were used for in vitro and in vivo studies. In vitro studies, cigarette smoke solution was found to increase TNFalpha secretion, and EGFR-specific tyrosine phosphorylation, and to elevate MUC5AC production. These effects were inhibited dose-dependently by pretreatment with rebamipide (MUC5AC protein levels were inhibited from 44% to 17%, P<0.05). In vivo studies, cigarette smoke was found to cause inflammatory cell recruitment and to increase the secretion of TNFalpha in bronchoalveolar lavage (BAL) fluids (from 198+/-78 to 2270+/-158 pg/ml, P<0.01). Moreover, the pretreatment of rats with rebamipide inhibited goblet cell metaplasia and TNFalpha secretion, dose-dependently (from 2270+/-158 to 1377+/-112 pg/ml, P<0.05). In conclusion, the exposure of airway epithelium to cigarette smoke-induced TNFalpha production, neutrophil recruitment, activated EGFR, and caused MUC5AC mucin synthesis. Moreover, rebamipide was found to prevent this cigarette smoke-induced TNFalpha release, and mucin production.     

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。     

Bronchial inflammation and airway responses to deep inspiration in asthma and chronic obstructive pulmonary disease

RATIONALE: Deep inspirations provide physiologic protection against airway narrowing in healthy subjects, which is impaired in asthma and chronic obstructive pulmonary disease (COPD). Airway inflammation has been suggested to alter airway mechanics during deep inspiration. OBJECTIVES: We tested the hypothesis that the number of bronchial inflammatory cells is related to deep inspiration-induced bronchodilation in asthma and COPD. METHODS: In a cross-sectional study, three modified methacholine challenges were performed in 13 patients with mild, persistent asthma, 12 patients with mild to moderate COPD, and 12 healthy control subjects. MEASUREMENTS AND MAIN RESULTS: After a 20-minute period of deep inspiration avoidance, inhalation of methacholine was followed by either one or five deep inspirations, or preceded by five deep inspirations. The response to deep inspiration was measured by forced oscillation technique. Inflammatory cells were counted within the lamina propria and airway smooth muscle area in bronchial biopsies of patients with asthma and COPD. The reduction in expiratory resistance by one and five deep inspirations was significantly less in asthma (mean change+/-SD: -0.5+/-0.8 and -0.9+/-1.0 cm H2O/L/s, respectively) and COPD (+0.2+/-1.1 and +0.4+/-1.0 cm H2O/L/s, respectively) as compared with healthy subjects (-1.5+/-1.3 and -2.0+/-1.2 cm H2O/L/s, respectively; p=0.05 and p=0.001, respectively). In asthma, this was related to an increase in mast cell numbers within the airway smooth muscle area (r=0.73; p=0.03), and in CD4+ lymphocytes in the lamina propria (r=0.61; p=0.04). CONCLUSIONS: Inflammation in the airway smooth muscle bundles and submucosa of bronchial biopsies is positively associated with impaired airway mechanics during deep inspiration in asthma, but not in COPD. Clinical trial registered with www.clinicaltrials.gov (NCT OO279136).     

Expression of MUC5AC and MUC5B mucins in normal and cystic fibrosis lung

Hypersecretion of airway mucus is a characteristic feature of chronic airway diseases like cystic fibrosis (CF) and leads via impairment of the muco-ciliary clearance and bacterial superinfection to respiratory failure. The major components of the mucus matrix forming family of mucins in the airways are MUC5AC and MUC5B. To investigate the expression of these glycoproteins in CF, immunohistochemistry was carried out on trachea, bronchi and peripheral lung obtained from CF patients and compared to normal lung tissues. MUC5AC immunohistochemistry demonstrated signals in goblet cells of the epithelial lining. Also, goblet cells inside glandular secretory ducts revealed MUC5AC-positive staining. In comparison to those from normal subjects, CF sections were characterized by inflammatory changes and goblet cell hyperplasia, resulting in increased numbers of MUC5AC-positive cells. Immunohistochemical staining for MUC5B showed abundant staining of submucosal glands and epithelial goblet cells. Inside the glands, the immunoreactivity was restricted to glandular mucous cells. MUC5AC and MUC5B are expressed in the same histological pattern in CF compared to normal tissues with an increase of MUC5AC-positive cells due to goblet cell hyper- and metaplasia.     

Relationship of epidermal growth factor receptors to goblet cell production in human bronchi

To determine the relationship of epidermal growth factor receptor (EGFR) expression to mucin synthesis in human airways, we examined EGFR and MUC5AC expression at both gene and protein levels using in situ hybridization and immunohistochemical analysis in human bronchi. Bronchial mucosal biopsy specimens were obtained from 12 asthmatic subjects and 11 healthy subjects. In asthmatic airways, EGFR mRNA was expressed in the airway epithelium. EGFR immunoreactivity staining patterns varied among the asthmatic airways: staining was positive mainly in goblet cells, in basal cells, or in both. In contrast, healthy airways showed little expression of EGFR mRNA; EGFR immunoreactivity was observed mainly in goblet cells. In parallel to EGFR expression, MUC5AC mRNA expression was greater in asthmatic airways; mucous glycoconjugates that stained positively with Alcian blue/PAS were also increased in asthmatic airways. Ciliated cells were negative for EGFR and MUC5AC both in asthmatic and in healthy subjects at both mRNA and protein levels. There was a significant positive correlation between EGFR immunoreactivity and the area of MUC5AC-positive staining in both asthmatics and healthy subjects. These findings suggest a sequence of events by which EGFR activation is involved in mucin expression in asthmatic airway epithelium.     

Hyperplasia of smooth muscle in mild to moderate asthma without changes in cell size or gene expression

Bronchial hyperresponsiveness in mild to moderate asthma may result from airway smooth muscle cell proliferation or acquisition of a hypercontractile phenotype. Because these cells have not been well characterized in mild to moderate asthma, we examined the morphometric and gene expression characteristics of smooth muscle cells in this subgroup of patients with asthma. Using bronchial biopsies from 14 subjects with mild to moderate asthma and 15 control subjects, we quantified smooth muscle cell morphology by stereology and the expression of a panel of genes related to a hypercontractile phenotype of airway smooth muscle, using laser microdissection and two-step real-time polymerase chain reaction. We found that airway smooth muscle cell size was similar in both groups, but cell number was nearly twofold higher in subjects with asthma (p = 0.03), and the amount of smooth muscle in the submucosa was increased 50-83% (p < 0.005). Gene expression profiling in smooth muscle cells showed no difference in the expression of genes encoding phenotypic markers in cells from healthy subjects and subjects with asthma (all p > 0.1). We conclude that airway smooth muscle proliferation is a pathologic characteristic of subjects with mild to moderate asthma. However, smooth muscle cells in mild to moderate asthma do not show hypertrophy or gene expression changes of a hypercontractile phenotype observed in vitro.     

Role of gob-5 in mucus overproduction and airway hyperresponsiveness in asthma

Airway hyperresponsiveness (AHR), goblet cell metaplasia, and mucus overproduction are important features of bronchial asthma. To elucidate the molecular mechanisms behind these pulmonary pathologies, we examined for genes preferentially expressed in the lungs of a murine model of allergic asthma by using suppression subtractive hybridization (SSH). We identified a gene called gob-5 that had a selective expression pattern in the airway epithelium with AHR. Here, we show that gob-5, a member of the calcium-activated chloride channel family, is a key molecule in the induction of murine asthma. Intratracheal administration of adenovirus-expressing antisense gob-5 RNA into AHR-model mice efficiently suppressed the asthma phenotype, including AHR and mucus overproduction. In contrast, overexpression of gob-5 in airway epithelia by using an adenoviral vector exacerbated the asthma phenotype. Introduction of either gob-5 or hCLCA1, the human counterpart of gob-5, into the human mucoepidermoid cell line NCI-H292 induced mucus production as well as MUC5AC expression. Our results indicated that gob-5 may play a critical role in murine asthma, and its human counterpart hCLCA1 is therefore a potential target for asthma therapy.     

Epithelial cell proliferation contributes to airway remodeling in severe asthma

RATIONALE: Despite long-term therapy with corticosteroids, patients with severe asthma develop irreversible airway obstruction. OBJECTIVES: To evaluate if there are structural and functional differences in the airway epithelium in severe asthma associated with airway remodeling. METHODS: In bronchial biopsies from 21 normal subjects, 11 subjects with chronic bronchitis, 9 subjects with mild asthma, and 31 subjects with severe asthma, we evaluated epithelial cell morphology: epithelial thickness, lamina reticularis (LR) thickness, and epithelial desquamation. Levels of retinoblastoma protein (Rb), Ki67, and Bcl-2 were measured, reflecting cellular proliferation and death. Terminal deoxynucleotidyl-mediated dUTP nick end labeling (TUNEL) was used to study cellular apoptosis. MEASUREMENTS AND MAIN RESULTS: Airway epithelial and LR thickness was greater in subjects with severe asthma compared with those with mild asthma, normal subjects, and diseased control subjects (p=0.009 and 0.033, respectively). There was no significant difference in epithelial desquamation between groups. Active, hypophosphorylated Rb expression was decreased (p=0.002) and Ki67 was increased (p<0.01) in the epithelium of subjects with severe asthma as compared with normal subjects, indicating increased cellular proliferation. Bcl-2 expression was decreased (p<0.001), indicating decreased cell death suppression. There was a greater level of apoptotic activity in the airway biopsy in subjects with severe asthma as compared with the normal subjects using the TUNEL assay (p=0.002), suggesting increased cell death. CONCLUSIONS: In subjects with severe asthma, as compared with subjects with mild asthma, normal subjects, and diseased control subjects, we found novel evidence of increased cellular proliferation in the airway contributing to a thickened epithelium and LR. These changes may contribute to the progressive decline in lung function and airway remodeling in patients with severe asthma.     

Increased expression of the human Ca2+-activated Cl- channel 1 (CaCC1) gene in the asthmatic airway

Mucus overproduction is a clinical feature of asthma. Ca2+-activated Cl- channel 1 (CaCC1) has been identified as a protein that is expressed in intestinal epithelia and that plays an important role in fluid and electrolyte transport. Recently, its mouse counterpart, gob-5, was identified as a key molecule in the induction of murine asthma through mucus overproduction. To elucidate the relationship of CaCC1 to human asthma, we examined CaCC1 expression using real-time quantitative polymerase chain reaction analysis in bronchial tissues from patients with asthma and normal control subjects. The expression of CaCC1 was significantly upregulated in patients with bronchial asthma compared with control subjects. In situ hybridization and immunohistochemical analysis demonstrated that CaCC1 is located in the bronchial epithelium, especially in mucus-producing goblet cells. In vitro transfection of a CaCC1 expression vector into the human mucoepidermoid cell line, NCI-H292, increased mucus production and induced the MUC5AC gene. These results suggest that CaCC1 plays a direct role in mucus production and differentiation in goblet cells and may contribute to the pathogenesis of asthma through its mucus-inducing activity.     

Epithelial desquamation in asthma: artifact or pathology?

To determine whether the denudation of the bronchial epithelium observed in endobronchial biopsies from asthmatic subjects is a true pathologic feature or an artifact of tissue sampling, we analyzed epithelial integrity in bronchial biopsies from 14 subjects with mild and moderate asthma and 12 healthy subjects. In each subject, 4 to 8 bronchial biopsies were taken from large airways during bronchoscopy, fixed in 4% paraformaldehyde, embedded in glycomethacrylate, cut into 2-microM sections, and stained with toluidine blue. A x4 image of each biopsy was copied to a computer file using a video camera, and lines were drawn and measured along the basement membrane underlying areas completely denuded of overlying epithelium, areas covered by a single layer of basal cells, and areas of intact epithelium. We found that the percentage of basement membrane that was denuded of epithelium was similar in the healthy and asthmatic subjects (14.8 +/- 11.8 versus 11.4 +/- 9.8% respectively, p = 0.38); the percentage of basement membrane that was covered by a single layer of basal cells was also similar in the two groups (46.4 +/- 11.0 versus 54.5 +/- 9.8%, respectively, p = 0. 11). In the asthmatic subjects, we found no significant correlation between the percentage of basement membrane covered by denuded epithelium or by a single layer of basal cells and the FEV(1) percentage of predicted or the PC(20) methacholine. We conclude that denudation of bronchial epithelium in endobronchial biopsies from asthmatic subjects with stable mild and moderate disease is an artifact of tissue sampling and is not a true pathologic feature of the disease, and that the extent of airway epithelial denudation is not correlated with the severity of airway narrowing or the severity of bronchial hyperresponsiveness.     

Inhibition of allergen-induced airway remodelling by tiotropium and budesonide: a comparison.

Chronic inflammation in asthma and chronic obstructive pulmonary disease drives pathological structural remodelling of the airways. Using tiotropium bromide, acetylcholine was recently identified as playing a major regulatory role in airway smooth muscle remodelling in a guinea pig model of ongoing allergic asthma. The aim of the present study was to investigate other aspects of airway remodelling and to compare the effectiveness of tiotropium to the glucocorticosteroid budesonide. Ovalbumin-sensitised guinea pigs were challenged for 12 weeks with aerosolised ovalbumin. The ovalbumin induced airway smooth muscle thickening, hypercontractility of tracheal smooth muscle, increased pulmonary contractile protein (smooth-muscle myosin) abundance, mucous gland hypertrophy, an increase in mucin 5 subtypes A and C (MUC5AC)-positive goblet cell numbers and eosinophilia. It was reported previously that treatment with tiotropium inhibits airway smooth muscle thickening and contractile protein expression, and prevents tracheal hypercontractility. This study demonstrates that tiotropium also fully prevented allergen-induced mucous gland hypertrophy, and partially reduced the increase in MUC5AC-positive goblet cell numbers and eosinophil infiltration. Treatment with budesonide also prevented airway smooth muscle thickening, contractile protein expression, tracheal hypercontractility and mucous gland hypertrophy, and partially reduced MUC5AC-positive goblet cell numbers and eosinophilia. This study demonstrates that tiotropium and budesonide are similarly effective in inhibiting several aspects of airway remodelling, providing further evidence that the beneficial effects of tiotropium bromide might exceed those of bronchodilation.