Impact of Mycobacterium vaccae immunization on lung histopathology in a murine model of chronic asthma

BACKGROUND: Therapeutic modalities of asthma have not been proved to be successful in reversing the already established chronic changes of airways. OBJECTIVE: We aimed to determine the impact of heat-killed Mycobacterium vaccae immunization, a potent Th1 stimulant, on chronic changes of asthma. METHODS: Newborn BALB/c mice were divided into three groups; mice in M. vaccae group received 107 colony-forming units (CFU)/50 micro L of heat-killed M. vaccae subcutaneously on days 3, 14 and 42 before the development of chronic asthma model, whereas mice in control and chronic asthma groups received saline. Subsequently, mice in M. vaccae and chronic asthma groups were administered 10 micro g/100 micro L of ovalbumin (OVA) on days 43, 45, 47, 49, 51, 53 and 55 intraperitoneally, and 20 micro g/10 micro L of OVA on days 83, 86 and 89 intratracheally. Mice in control group received saline on the same days. RESULTS: Comparison of M. vaccae and chronic asthma groups showed statistically significant differences in goblet cell numbers, thickness of basement membrane and subepithelial smooth muscle of small, medium and large airways and epithelial thickness of medium airways. There was no significant difference between the control and M. vaccae groups except for goblet cell numbers of medium and large airways, and epithelial thickness of medium airways. CONCLUSION: Results of our study suggested that immunization by M. vaccae of newborn mice would prevent some of the chronic changes of airways due to asthma.     

Treatment with chitin microparticles is protective against lung histopathology in a murine asthma model

BACKGROUND: Chitin, a natural polysaccharide extracted from shrimp, is a potent T and B cell adjuvant when delivered in the form of chitin microparticles and can shift a polarized T-helper type 2 (Th2) immune response towards a Th1 response. OBJECTIVE: We investigated the beneficial effects of the intranasal application of chitin microparticles in newborn mice before and after the establishment of a model of allergic asthma. METHODS: Mice were grouped as asthma (A), primary prevention (PP), treatment (T), primary prevention+treatment (PPT) and control (C) groups. All mice except controls were sensitized with ovalbumin intraperitoneally and challenged intratracheally to establish the asthma model. Mice in the PP and PPT groups received chitin microparticles intranasally during the newborn period before sensitization. Mice in the PPT and T groups received intranasal chitin microparticles after challenge. Airway histopathology was evaluated in all groups. RESULTS: All of the airway histopathologic parameters of small and medium-sized airways of the T and PPT groups were significantly ameliorated when compared with the asthma model group. In the large airways, thicknesses of basement membrane, epithelium and subepithelial smooth muscle layers of the PPT group and basement membrane thicknesses of the T group were also significantly lower compared with the asthma model group. Comparison of the PP group with the asthma model group revealed significantly reduced goblet cell numbers and significantly reduced epithelial and basement membrane thicknesses in small and medium airways, in addition to significantly reduced basement membrane thicknesses in the medium-sized airways. CONCLUSION: Intranasal application of microgram quantities of chitin microparticles had a beneficial effect in preventing and treating histopathologic changes in the airways of asthmatic mice.     

Mycobacterium vaccae administration during allergen sensitization or challenge suppresses asthmatic features

BACKGROUND AND OBJECTIVE: The hygiene hypothesis suggests that a lack of bacterial infections would favour the development of allergic disease. For this reason, bacteria or their components can be used as potential treatment for allergic asthma. We investigated whether heat-killed Mycobacterium vaccae is either able to suppress the induction of allergic asthma or able to suppress already established allergic asthma. METHODS: Mice were sensitized with ovalbumin (OVA)/alum on days 0 and 14. Thereafter, mice were challenged on days 35, 39 and 42 by inhalation of either OVA or saline aerosols. M. vaccae-treated mice received an injection with 106, 107 or 108 CFU heat-killed M. vaccae on days 0 and 14 or 107 CFU on days 35 and 39. On day 43, the airway responsiveness of the mice to increasing concentrations of methacholine was assessed, blood was withdrawn to measure serum parameters, and lung lavage was performed to detect cytokines and inflammatory cell number. RESULTS: Treatment of OVA-sensitized mice with 107 CFU M. vaccae either during sensitization or challenge suppresses airway hyper-responsiveness, airway eosinophilia and IL-5 production after OVA challenge. The increases in OVA-specific serum IgE and in IL-4 by respiratory challenges with OVA were only diminished after M. vaccae treatment (107 CFU) during sensitization. CONCLUSIONS: Heat-killed M. vaccae prevents allergic and asthmatic manifestations in a mouse model and, more importantly, M. vaccae treatment during challenge suppresses features of asthma, which opens up possibilities for new therapeutic interventions.     

Increased surfactant protein D in rat airway goblet and Clara cells during ovalbumin-induced allergic airway inflammation

BACKGROUND: Structural remodelling of airways in asthma that follows inflammation may be affected by surfactant protein D (SP-D)-mediated effects on the immune response. OBJECTIVE: To determine potential sites of SP-D interaction with the pulmonary immune response, we examined the distribution of immunoreactive SP-D in an experimental model of allergen-induced airway inflammation using immunohistochemistry, biochemical methods and in situ hybridization. METHODS: The experimental model used subcutaneous injection of ovalbumin in adult rats, which induced an airway response to inhaled nebulized ovalbumin. Three groups of rats (ovalbumin, ovalbumin + dexamethasone and saline) were challenged thrice weekly for 3 weeks. A fourth group of seven rats (naive) were taken from the same delivery of rats as the other groups. Lungs were then lavaged to determine total cell count, eosinophil count, ovalbumin-specific IgE by enzyme-linked immunosorbent assay and SP-D by immunoblot. Tissue samples were fixed and embedded, and sections were studied for the infiltration of eosinophils and for expression of SP-D protein by histochemistry and mRNA by in situ hybridization. RESULTS: Ovalbumin induced perivascular and peribronchiolar eosinophilia which could be prevented by dexamethasone treatment. In addition, the ovalbumin-specific IgE levels in serum and bronchoalveolar lavage fluid of ovalbumin-challenged animals were enhanced. Increased amount of SP-D in lavage and tissue, particularly in type II pneumocytes, in Clara cells and, surprisingly, in hyperplastic goblet cells of inflamed lungs was found. SP-D mRNA was detected in goblet cells as well as in type II pneumocytes and Clara cells. Dexamethasone treatment did not affect level of SP-D immunoreactivity. CONCLUSION: SP-D accumulation is increased in this model of allergen-induced eosinophilia, both in upper and lower airways. The increase is unaffected by dexamethasone.     

The role of the tachykinin NK1 receptor in airway changes in a mouse model of allergic asthma

BACKGROUND: Tachykinins are present in sensory nerves and in nonneuronal cells like macrophages. Human data suggest a role for these peptides in asthma, but the exact role of tachykinins and their receptors in allergic airway inflammation is still a matter of debate. OBJECTIVE: The aim of this study was to determine the role of the tachykinin NK1 receptor in allergic airway responses in a mouse model. METHODS: Tachykinin NK1 receptor wild-type and knockout animals were sensitized intraperitoneally to ovalbumin and subsequently exposed from days 14 to 21 to aerosolized ovalbumin (1% ). On day 22, the immunologic and histologic changes were evaluated, and lung function measurements were performed. RESULTS: Mice lacking the tachykinin NK1 receptor and their wild-type litter mates developed inflammatory cell infiltrates in the airways and ovalbumin-specific IgE on sensitization and exposure to ovalbumin compared with saline-exposed controls. No differences were detected between wild-type and knockout mice. The substance P content of alveolar macrophages was not influenced by ovalbumin or by the lack of the NK1 receptor. Ovalbumin-induced hyperresponsiveness was not observed, but at baseline, the knockout mice were more reactive despite similar morphology. Ovalbumin induced more goblet cell hyperplasia in wild-type animals compared with knockout animals. No differences in airway wall thickness were observed. CONCLUSION: These data suggest that tachykinin NK1 receptors do not affect allergic airway inflammation or endogenous substance P content of alveolar macrophages but influence baseline responsiveness and promote features of remodeling such as goblet cell hyperplasia.     

HSP70/CD80嵌合DNA疫苗对哮喘小鼠气道炎症和气道高反应性的作用

目的 研究HSP70/CD80嵌合DNA质粒对哮喘小鼠气道炎症和气道高反应性的作用,为安全可靠的新型免疫调节性疫苗奠定基础.方法 将40只雌性健康BALB/c小鼠随机分为4组:对照组、哮喘组、pcDNA3.1载体组、HSP70/CD80嵌合DNA疫苗组,每组10只.用HSP70/CD80嵌合疫苗免疫小鼠后,建立鸡卵清蛋白致敏的小鼠哮喘模型,观察其气道阻力变化,支气管肺泡灌洗液中IL-13、IFN-γ含量的变化.取肺组织进行病理组织学分析,观察肺内炎症情况.结果 HSP70/CD80嵌合DNA疫苗免疫小鼠后,能有效减轻气道炎症(P＜0.05),降低气道阻力(P＜0.05),肺泡灌洗液中IFNl的分泌增加(P＜0.05),IL-13降低.结论 HSP70/CD80嵌合DNA疫苗可促进免疫反应向Th1偏移并增加IFN-γ的生成,减轻气道炎症,降低气道阻力,这为过敏性哮喘新型免疫调节性疫苗的机制及应用研究提供了实验资料.     

气道应用T-bet重组腺病毒抑制哮喘小鼠过敏性气道炎症

目的探讨气道应用T-bet重组腺病毒(AdT-bet)对哮喘小鼠气道炎症反应的影响及机制。方法C57BL/6小鼠随机分为4组,实验组(A组)、对照病毒组(B组)、PBS对照组(C组)和正常对照组(D组),A、B、C组采用卵蛋白(OVA)、明矾建立哮喘模型,分别于第19天激发前气道内单次应用50μLAdT-bet(108pfu)、AdLacZ、PBS。26d取肺泡灌洗液(BALF)测定细胞成分、IL-4、IL-5、IFNγ浓度,取血测定血浆IgE水平,观察肺组织病理学变化及GATA-3表达。结果1)A组BALF中的嗜酸粒细胞(EOS)为(0.5±0.2)%明显低于B组(21.2±6.9)%和C组(20.9±6.8)%(P<0.01);2)A组BALF中的IL-4(6.7±3.8)pg/mL和IL-5(12.4±4.9)pg/mL的水平明显低于B组[IL-4(91.4±22.5)pg/mL和IL-5(55.6±10.6)pg/mL]和C组[IL-4(89.8±23.6)pg/mL和IL-5(56.7±11.5)pg/mL](P<0.01),而IFNγ的水平(710±45)pg/mL则明显高于B组(13.1±3.5...     

Induction of airway remodeling of nasal mucosa by repetitive allergen challenge in a murine model of allergic rhinitis.

BACKGROUND: Although many studies regarding airway remodeling in asthma have been reported, only a few studies have investigated airway remodeling in allergic rhinitis. OBJECTIVES: To determine whether repetitive allergen challenge could induce airway remodeling in the nose and evaluate the effect of steroids using a murine model of allergic rhinitis. METHODS: To develop a mouse model of airway remodeling, ovalbumin-sensitized mice were repeatedly exposed to inhaled ovalbumin administration twice a week for 1 month and 3 months. Matched control mice were challenged with phosphate-buffered saline, and the treatment group received intraperitoneal dexamethasone injection. Trichrome, periodic acid-Schiff, hematoxylin-eosin, and immunohistochemical staining against matrix metalloproteinase 9 and tissue inhibitors of metalloproteinase 1 were performed to nasal and lung tissues, and the level of transforming growth factor beta in the nasal lavage fluid was analyzed. RESULTS: Repetitive ovalbumin challenge for 3 months induced circumferential peribronchial fibrosis in the lung. In the nose, subepithelial fibrosis, increased matrix metalloproteinase 9 and tissue inhibitors of metalloproteinase 1 expression, goblet cell hyperplasia, and submucous gland hypertrophy were observed compared with the control group. Features of airway remodeling were more prominent in the lung tissue. Administration of dexamethasone significantly inhibited these histologic changes. CONCLUSION: Airway remodeling associated with long-term allergen challenge can occur in the nasal mucosa and the lung. Steroid treatment prevents airway inflammation in response to acute allergen challenge, as well as airway remodeling by long-term allergen challenge.     

钙调神经磷酸酶在哮喘豚鼠气道重塑中的作用

目的:观察钙调神经磷酸酶(CaN)在哮喘豚鼠气道重塑中的作用。方法:实验分3组:对照组、哮喘组及CaN抑制剂环孢霉素(CsA)组,测定指标包括:①支气管肺泡灌洗液(BALF)蛋白含量、细胞计数及分类;②大气道平滑肌[³H]-TdR掺入量;③肺组织切片中小气道壁厚度及气道平滑肌厚度;④气管和肺组织CaN活性。结果:①BALF:CsA组蛋白含量、细胞计数及嗜酸粒细胞分别较哮喘组少46%、51%及60%(P＜0.01);②大气道平滑肌[³H]-TdR掺入量:CsA组较哮喘组低22%(P＜0.05);③小气道壁厚度:CsA组较哮喘组少34%(P＜0.01);气道平滑肌厚度:CsA组较哮喘组少37%(P＜0.01);④肺组织CaN活性:CsA组较哮喘组低52%(P＜0.01);气管CaN活性:CsA组较哮喘组低44%(P＜0.01)。结论:CsA可减轻哮喘豚鼠气道重塑,推测CaN参与气道重塑过程。     

氟伐他汀对哮喘气道重塑的抑制作用及机制研究

目的:探讨氟伐他汀对哮喘气道重塑过程的影响及分子机制。方法:以卵蛋白致敏的豚鼠哮喘模型为对象,观察正常对照组、哮喘组及氟伐他汀+哮喘组之间气道平滑肌肌层厚度的差异。氟伐他汀+哮喘组即每次激发哮喘前30min吸入浓度为05g/L的氟伐他汀2mL。同时采用Dot-blot分子杂交法、免疫组化SABC法检测各组气道ras基因的mRNA和蛋白水平变化。结果:哮喘组气道平滑肌层平均厚度为(7427±330)μm,显著高于正常对照组(3857±337)μm(P<001);氟伐他汀+哮喘组的平滑肌层厚度为(5170±413)μm,明显低于哮喘组(P<005)。哮喘组平滑肌细胞的ras基因表达水平明显高于正常对照组,但氟伐他汀+哮喘组未出现该基因的高表达。结论:氟伐他汀在一定程度上能抑制哮喘气道重塑的病理过程,其发挥效应的机制之一是阻断平滑肌细胞rasp21信号转导途径。     

A plasminogen activator inhibitor-1 inhibitor reduces airway remodeling in a murine model of chronic asthma

We previously reported that plasminogen activator inhibitor (PAI)-1 deficiency prevents collagen deposition in the airways of ovalbumin (OVA)-challenged mice. In this study, we explored the therapeutic utility of blocking PAI-1 in preventing airway remodeling, using a specific PAI-1 inhibitor, tiplaxtinin. C57BL/6J mice were immunized with intraperitoneal injections of OVA on Days 0, 3, and 6. Starting on Day 11, mice were challenged with phosphate-buffered saline or OVA by nebulization three times per week for 4 weeks. Tiplaxtinin was mixed with chow and administered orally from 1 day before the phosphate-buffered saline or OVA challenge. Lung tissues were harvested after challenge and characterized histologically for infiltrating inflammatory cells, mucus-secreting goblet cells, and collagen deposition. Airway hyperresponsiveness was measured using whole-body plethysmography. Tiplaxtinin treatment significantly decreased levels of PAI-1 activity in bronchoalveolar lavage fluids, which indicates successful blockage of PAI-1 activity in the airways. The number of infiltrated inflammatory cells was reduced by tiplaxtinin treatment in the lungs of the OVA-challenged mice. Furthermore, oral administration of tiplaxtinin significantly attenuated the degree of goblet cell hyperplasia and collagen deposition in the airways of the OVA-challenged mice, and methacholine-induced airway hyperresponsiveness was effectively reduced by tiplaxtinin in these animals. This study supports our previous findings that PAI-1 promotes airway remodeling in a murine model of chronic asthma, and suggests that PAI-1 may be a novel target of treatment of airway remodeling in asthma.     

动态观察过敏原诱导的哮喘小鼠模型从急性炎症到慢性重塑的发展

目的:动态观察对比卵白蛋白(OVA)诱导的哮喘小鼠模型从气道的急性炎症到慢性重塑的相关炎症指标及气道重塑指标的变化。方法:60只雌性BALB/c小鼠随机分为正常对照组和哮喘组。哮喘组给予OVA致敏和激发,正常对照组给予等量生理盐水(NS)作为对照,第21天开始,连续激发3 d,观察急性炎症反应;而后每周激发1次、每次激发后24 h内取材1次连续5周;动态观察对比OVA激发组和NS对照组小鼠气道炎症细胞的浸润情况、灌洗液细胞因子水平和气道重塑相关指标。结果:与NS组比较,OVA组肺组织的炎症细胞浸润明显,炎症因子升高;气道上皮细胞向杯状细胞转化明显;支气管外周胶原沉积显著。OVA组内比较,24 d组炎症细胞和炎症因子上升明显,而上皮细胞向杯状细胞的转化以及支气管外周胶原沉积相关重塑指标不明显,52 d组上皮细胞向杯状细胞的转化以及支气管外周胶原沉积相关重塑指标最为显著,而炎症细胞和炎症因子有所下降。结论:连续3次OVA激发可成功模拟炎症细胞和炎症因子显著的急性哮喘模型;每周1次、连续5周的OVA激发方式可成功模拟重塑明显的慢性哮喘模型。     

Role of vascular endothelial growth factor antagonism on airway remodeling in asthma

BackgroundVascular endothelial growth factor (VEGF) is an important mediator of the neoangiogenesis component of remodeling in asthma.ObjectiveTo evaluate the influence of VEGF blockage on airway remodeling, specifically epithelium thickness, subepithelial smooth muscle thickness, number of mast and goblet cells, and basement membrane thickness, in a mouse model of chronic asthma.MethodsWe used 30 BALB/c mice. The control group was not exposed to ovalbumin or any medication (group 1). Other groups were exposed to intraperitoneal and inhaled ovalbumin to achieve chronic asthma. Each of these groups received intraperitoneal saline (group 2), intraperitoneal dexamethasone (group 3), or intraperitoneal bevacizumab (group 4). Histomorphologic examination for epithelium thickness, subepithelial smooth muscle thickness, number of mast and goblet cells, and basement membrane thickness was performed from the middle zone of the left lung.ResultsTreatment with anti-VEGF caused significant reduction in epithelial, subepithelial muscle, and basement membrane thickness compared with untreated asthmatic mice (P = .001, P = .03, and P = .009, respectively). Goblet and mast cell numbers were significantly lower in mice treated with anti-VEGF than in untreated mice (P = .02 and P = .007, respectively). Dexamethasone treatment resulted in improvement of all histomorphologic markers, except goblet cell number. Influences of dexamethasone and anti-VEGF on epithelial and basement membrane thickness and mast and goblet cell numbers did not differ (P > .05), but subepithelial muscle layer was thinner in the former (P = .003).ConclusionVEGF blockage may provide adjunctive therapeutic options as steroid-sparing agents for more effective treatment of remodeling in asthma.     

Effects of ciclesonide and fluticasone propionate on allergen-induced airway inflammation and remodeling features

BACKGROUND: Several topical corticosteroids are available as anti-inflammatory treatment for asthma. Their comparative effects on allergic inflammation and airway remodeling are unclear. OBJECTIVE: We compared the effects of ciclesonide with those of fluticasone propionate in a Brown Norway rat model of chronic allergic asthma. METHODS: Rats sensitized and exposed to ovalbumin (OVA) were treated with dry powder vehicle, ciclesonide, or fluticasone (0.01, 0.03, and 0.1 mg/kg administered intratracheally) 24 hours and 1 hour before each of 6 OVA exposures. In a second protocol we administered 0.1 mg/kg ciclesonide or fluticasone only after the third OVA exposure. RESULTS: Ciclesonide at all doses inhibited the allergen-induced increase in airway eosinophils and T cells, reduced goblet cell hyperplasia, and decreased 5-bromo-2'-deoxyuridine-immunoreactive airway smooth muscle (ASM) and epithelial cells. At 0.03 and 0.1 mg/kg ciclesonide, bronchial hyperresponsiveness (BHR) was also inhibited. Fluticasone did not attenuate allergen-induced BHR, despite inhibiting airway eosinophils and T cells, goblet cell hyperplasia, and 5-bromo-2'-deoxyuridine-immunoreactive ASM and epithelial cells. Fluticasone (0.1 mg/kg) caused a significant reduction in body weight (9%) compared with ciclesonide (0.1 mg/kg). Ciclesonide did not change plasma corticosterone levels, whereas fluticasone (0.1 mg/kg) reduced them. In the second protocol both fluticasone and ciclesonide inhibited BHR, bronchial inflammation, goblet cell hyperplasia, and ASM proliferation. CONCLUSION: Ciclesonide potently inhibited chronic allergic inflammation, remodeling, and BHR without having an effect on body weight and the hypothalamic-pituitary-adrenal axis. Fluticasone prevented airway inflammation but not BHR, but both fluticasone and ciclesonide are effective at reversal of BHR, inflammation, and remodeling features.     

Time course study on the development of allergen-induced airway remodeling in mice: the effect of allergen avoidance on established airway remodeling

OBJECTIVE AND DESIGN: We carried out a time course study on the development of allergen-induced airway remodeling in a mouse model of allergic asthma. Moreover, we examined the effect of allergen avoidance on the established airway remodeling. MATERIALS AND METHODS: BALB/c mice were sensitized to ovalbumin (OA) with alum, and exposed daily for 3 weeks to aerosolized OA. At each designated point, bronchial responsiveness was measured, and bronchoalveolar lavage and histological examination were carried out. RESULTS: The numbers of inflammatory leukocytes in the airways and the percentage of goblet cells in the epithelium, Th2 cytokine production, IgE production, collagen deposition beneath the basement membrane and bronchial responsiveness to acetylcholine were all markedly increased after repeated antigen challenge for 1-3 weeks. In contrast, after cessation of antigen exposure, goblet cell hyperplasia, inflammatory infiltrates and bronchial hyperresponsiveness were gradually attenuated and had almost resolved 4 weeks after cessation, but subepithelial fibrosis was still observed at this time point. CONCLUSIONS: The present findings demonstrated that epithelial changes following repeated allergen challenge are rapidly induced and recover after the cessation of exposure, but subepithelial fibrosis has a late onset and relatively irreversible changes, and subepithelial fibrosis in contrast to goblet cells hyperplasia did not appear to contribute to bronchial hyperresponsiveness, at least, in this mouse model.     

微卡对哮喘豚鼠肺组织嗜酸粒细胞凋亡及Bcl-2蛋白表达的影响

目的：研究微卡对哮喘豚鼠肺组织嗜酸粒细胞凋亡及Bcl-2蛋白表达的影响。 方法： 30只豚鼠随机分为生理盐水组、哮喘组及微卡组，每组10只。微卡组每只豚鼠在OVA致敏前10 d肌注22.5 μg微卡。应用TUNEL法检测肺组织嗜酸粒细胞的凋亡，免疫组化法检测肺组织Bcl-2蛋白的表达。 结果： 微卡组豚鼠肺组织嗜酸粒细胞凋亡指数（23.78±5.42）%显著高于哮喘组（4.56±0.68）%(P<0.01)；肺组织Bcl-2蛋白平均积分吸光度值（1 556.3±492.4）显著低于哮喘组（2 321.9±751.2）（P<0.05）。 结论： 微卡能诱导哮喘豚鼠肺组织嗜酸粒细胞凋亡，可能与其抑制Bcl-2蛋白在哮喘豚鼠肺组织的表达有关。     

Prolonged allergen challenge in mice leads to persistent airway remodelling

BACKGROUND: Inflammatory infiltrates, airway hyper-responsiveness, goblet cell hyperplasia and subepithelial thickening are characteristic of chronic asthma. Current animal models of allergen-induced airway inflammation generally concentrate on the acute inflammation following allergen exposure and fail to mimic all of these features. OBJECTIVE: The aim of this study was to use a murine model of prolonged allergen-induced airway inflammation in order to characterize the cells and molecules involved in the ensuing airway remodelling. Moreover, we investigated whether remodelling persists in the absence of continued allergen challenge. METHODS: Acute pulmonary eosinophilia and airways hyper-reactivity were induced after six serial allergen challenges in sensitized mice (acute phase). Mice were subsequently challenged three times a week with ovalbumin (OVA) (chronic phase) up to day 55. To investigate the persistence of pathology, one group of mice were left for another 4 weeks without further allergen challenge (day 80). RESULTS: The extended OVA challenge protocol caused significant airway remodelling, which was absent in the acute phase. Specifically, remodelling was characterized by deposition of collagen as well as airway smooth muscle and goblet cell hyperplasia. Importantly, these airway changes, together with tissue eosinophilia were sustained in the absence of further allergen challenge. Examination of cytokines revealed a dramatic up-regulation of IL-4 and tumour growth factor-beta1 during the chronic phase. Interestingly, while IL-4 levels were significantly increased during the chronic phase, levels of IL-13 fell. Levels of the Th1-associated cytokine IFN-gamma also increased during the chronic phase. CONCLUSION: In conclusion, we have demonstrated that prolonged allergen challenge results in persistent airway wall remodelling.     

麻杏石甘汤对哮喘模型小鼠气道重塑及肺组织MMP-9和TIMP-1表达的影响

目的:观察麻杏石甘汤对哮喘模型小鼠气道重塑及肺组织基质金属蛋白酶9(MMP-9)和金属蛋白酶组织抑制物1(TIMP-1)表达的影响,探讨其治疗哮喘的可能机制。方法:将72只健康雌性BALB/c小鼠随机分为:空白对照组,模型组,麻杏石甘汤低剂量组、中剂量组和高剂量组,阳性对照组。采用卵清蛋白致敏激发建立小鼠哮喘模型。空白对照组和模型组于激发前30 min以生理盐水灌胃;麻杏石甘汤低剂量组、中剂量组和高剂量组分别于激发前30 min以麻杏石甘汤按5.0 g/kg、10.0 g/kg和20.0 g/kg剂量灌胃;阳性对照组于激发前30 min以地塞米松按0.005 g/kg剂量灌胃。连续给药7 d后,观察气道反应性、支气管肺泡冲洗液(BALF)中嗜酸性粒细胞(EOS)计数、杯状细胞百分比和胶原沉积的变化;ELISA法检测MMP-9和TIMP-1水平;Western blot法检测MMP-9和TIMP-1的蛋白表达;RT-qPCR法分析检测MMP-9和TIMP-1的mRNA表达。结果:与空白对照组比较,模型组的气道反应性、杯状细胞百分比、胶原沉积、BALF中EOS计数及肺组织MMP-9和TIMP-1的mRNA和蛋白水平均显著升高(P 0.01);与模型组比较,麻杏石甘汤低剂量组、中剂量组和高剂量组及阳性对照组上述指标则明显降低(P 0.05或P 0.01)。结论:麻杏石甘汤可能通过降低MMP-9和TIMP-1的表达改善哮喘模型小鼠气道重塑状态。     

Airway subepithelial fibrosis in a murine model of atopic asthma: suppression by dexamethasone or anti-interleukin-5 antibody

Fibrosis in the reticular layer beneath the epithelial basement membrane is a feature of airway remodeling in human asthma. We previously reported the presence of subepithelial fibrosis (SEF) in a disease model of atopic asthma in which mice were sensitized and intratracheally challenged with ovalbumin (OVA) (Blyth and colleagues, Am. J. Respir. Cell Mol. Biol. 1996;14:425-438). Here, we describe further studies to quantify the degree of SEF after its induction by repeated exposure of the airways to allergen. The amount of subepithelial reticulin in the airways of animals challenged three times with 80 microg OVA was typically increased 1. 4-fold. The increased amount of reticulin showed no reduction after a 50-d period after the third allergen challenge. A reduction in SEF was achieved by daily treatment with dexamethasone (DEX) for 8 d during the allergen challenge period, or by treatment with anti-interleukin-5 antibody (TRFK5) at the time of allergen challenge. Postchallenge treatment with DEX for 15 d resulted in significant resolution of previously established SEF. Severe nonallergic inflammation during repeated exposure of airways to lipopolysaccharide did not induce SEF. The results indicate that development of SEF is associated with eosinophil infiltration into airways, and may occur only when the inflammatory stimulus is allergic in nature.