Immunostimulatory DNA inhibits transforming growth factor-beta expression and airway remodeling

Immunostimulatory sequences of DNA (ISS) inhibit eosinophilic airway inflammation, Th2 responses, and airway hyperreactivity (AHR) in mouse models of acute ovalbumin (OVA)-induced airway inflammation. To determine whether ISS inhibits airway remodeling, we developed a mouse model of airway remodeling in which OVA-sensitized mice were repeatedly exposed to intranasal OVA administration for 1-6 mo. Mice chronically exposed to OVA developed sustained eosinophilic airway inflammation and sustained AHR to methacholine compared with control mice. In addition, the mice chronically exposed to OVA developed features of airway remodeling, including thickening of the peribronchial smooth muscle layer, peribronchial myofibroblast accumulation, expression of the profibrotic growth factor transforming growth factor-beta, and subepithelial collagen deposition (assessed by quantitation of the area of peribronchial trichrome staining using image analysis, and immunostaining with anti-collagen V antibodies). Administration of ISS systemically every other week significantly inhibited the development of AHR, eosinophilic inflammation, airway mucus production, and importantly, airway remodeling in mice chronically exposed to OVA for 3-6 mo. In addition, ISS significantly reduced bronchoalveolar lavage and lung levels of the profibrotic cytokine transforming growth factor-beta. These studies demonstrate that ISS prevents not only Th2-mediated airway inflammation in response to acute allergen challenge, but also airway remodeling associated with chronic allergen challenge.     

Components of airway hyperresponsiveness and their associations with inflammation and remodeling in mice

BACKGROUND: Pathologic changes, including inflammation and remodeling, occur in the asthmatic airway. However, their relative contribution to the components of airway hyperresponsiveness (AHR) remains unclear. OBJECTIVE: Attempting to delineate AHR into discrete immune-mediated and structural remodeling components, we performed a detailed time course of the development, progression, and persistence of maximal respiratory system resistance, airway reactivity, and airway sensitivity. METHODS: Mice exposed to increasing durations of persistent allergen were assessed for airway function, morphometry, and inflammation. RESULTS: Allergen exposure resulted in increases for all indices of AHR that persisted for at least 4 weeks after chronic allergen exposure (P < .01 for all values). Early increases in AHR were associated with increases in immune-mediated events, including airway eosinophils (P < .01), whereas sustained AHR was associated with structural remodeling events. Increased maximal respiratory system resistance, evident by 6 weeks postallergen and persisting for at least 4 weeks after 8 weeks of chronic exposure, was associated with an increase in collagen deposition (P < .01). Increased airway reactivity and sensitivity, each evident by 1 week after allergen and persisting for at least 4 weeks after 8 weeks of chronic exposure, were associated with an increase in airway smooth muscle area (P < .01). CONCLUSION: Our novel observation of distinct temporal relationships in the development, progression, and persistence of the individual indices of AHR supports our hypothesis that multiple underlying factors contribute to airway dysfunction. CLINICAL IMPLICATIONS: These findings illustrate the importance of clearly addressing specific components of airway dysfunction to provide greater insight into specific pathophysiologic mechanisms in airway disease.     

A novel prostacyclin agonist protects against airway hyperresponsiveness and remodeling in mice

Airway remodeling in bronchial asthma results from chronic, persistent airway inflammation. The effects of the reversal of airway remodeling by drug interventions remain to be elucidated. We investigated the effects of ONO-1301, a novel prostacyclin agonist with thromboxane inhibitory activity, on the prevention and reversibility of airway remodeling in an experimental chronic asthma model. Mice sensitized and challenged to ovalbumin (OVA) three times a week for 5 consecutive weeks were administered ONO-1301 or vehicle twice a day from the fourth week of OVA challenges. Twenty-four hours after the final OVA challenge, airway hyperresponsiveness (AHR) was assessed, and bronchoalveolar lavage was performed. Lung specimens were excised for staining to detect goblet-cell metaplasia, airway smooth muscle, and submucosal fibrosis. Mice administered ONO-1301 showed limited increases in AHR compared with mice administered the vehicle. The histological findings of airway remodeling were improved in ONO-1301-treated mice compared with vehicle-treated mice. Presumably, these therapeutic effects of ONO-1301 are attributable to the up-regulation of production of hepatocyte growth factor (HGF) in lung tissue, because the neutralization of HGF by antibodies prevented the effects of ONO-1301 on AHR and airway remodeling. Mice administered ONO-1301 showed similar levels of AHR and airway remodeling as mice administered montelukast, a cysteinyl-leukotriene-1 receptor antagonist, and lower levels were observed in mice administered dexamethasone. These data suggest that ONO-1301 exerts the effect of reversing airway remodeling, at least in part through an elevation of HGF in the lungs, and may be effective as an anti-remodeling drug in the treatment of asthma.     

CpG-oligodeoxynucleotides inhibit airway remodeling in a murine model of chronic asthma

BACKGROUND: We have previously demonstrated that CpG oligodeoxynucleotides (CpG-ODNs) protect against eosinophilia and airway hyperresponsiveness in murine models of allergen-induced asthma. Acute inflammation is hypothesized to induce chronic airway responses, but no previous studies have evaluated the effects of CpG-ODNs on allergen-induced airway remodeling. Because remodeling is thought to be responsible for many of the long-term adverse effects on asthmatic patients, we evaluated whether CpG-ODNs might similarly prevent these changes using a murine model of recurrent allergen exposure. OBJECTIVE: The purpose of this study was to evaluate the effect of CpG-ODNs on chronic inflammatory changes and airway remodeling by using a murine model of chronic allergen-induced asthma. METHODS: C57BL/6 mice were sensitized to ovalbumin (OVA) and subsequently exposed to nebulized OVA by means of inhalation 3 times weekly for 6 weeks. Some mice received CpG-ODNs by means of intraperitoneal injection at the time of sensitization. At the end of the exposure period, mice were evaluated for the development of airway inflammation, airway hyperresponsiveness, and airway remodeling. RESULTS: OVA-sensitized mice exposed to recurrent airway challenge with OVA have chronic inflammation, persistent airway hyperresponsiveness, and evidence of airway remodeling, including subepithelial collagen deposition and goblet cell hyperplasia-metaplasia. These changes are significantly reduced in mice treated with CpG-ODNs. Interestingly, mice treated with CpG-ODNs exhibit increased levels of bronchoalveolar lavage transforming growth factor beta, suggesting that regulatory T cells might be responsible for some of these protective effects. CONCLUSION: CpG-ODNs are effective not only in preventing acute inflammation but also appear to reduce markers of airway remodeling that develop after chronic allergen exposure.     

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。     

Natural killer T cells are dispensable in the development of allergen-induced airway hyperresponsiveness, inflammation and remodelling in a mouse model of chronic asthma

Natural killer T (NK T) cells have been shown to play an essential role in the development of allergen-induced airway hyperresponsiveness (AHR) and/or airway inflammation in mouse models of acute asthma. Recently, NK T cells have been reported to be required for the development of AHR in a virus induced chronic asthma model. We investigated whether NK T cells were required for the development of allergen-induced AHR, airway inflammation and airway remodelling in a mouse model of chronic asthma. CD1d^−/− mice that lack NK T cells were used for the experiments. In the chronic model, AHR, eosinophilic inflammation, remodelling characteristics including mucus metaplasia, subepithelial fibrosis and increased mass of the airway smooth muscle, T helper type 2 (Th2) immune response and immunoglobulin (Ig)E production were equally increased in both CD1d^−/− mice and wild-type mice. However, in the acute model, AHR, eosinophilic inflammation, Th2 immune response and IgE production were significantly decreased in the CD1d^−/− mice compared to wild-type. CD1d-dependent NK T cells may not be required for the development of allergen-induced AHR, eosinophilic airway inflammation and airway remodelling in chronic asthma model, although they play a role in the development of AHR and eosinophilic inflammation in acute asthma model.     

Time sequence of airway remodeling in a mouse model of chronic asthma: the relation with airway hyperresponsiveness

During the course of establishing an animal model of chronic asthma, we tried to elucidate the time sequence of airway hyperresponsiveness (AHR), airway inflammation, airway remodeling, and associated cytokines. Seven-week-old female BALB/c mice were studied as a chronic asthma model using ovalbumin (OVA). After sensitization, mice were exposed twice weekly to aerosolized OVA, and were divided into three groups depending on the duration of 4 weeks, 8 weeks, and 12 weeks. At each time point, airway responsiveness, inflammatory cells, cytokines in bronchoalveolar lavage fluids (BALF), serum OVA-specific IgE, IgG1, IgG2a, and histological examination were carried out. AHR to methacholine, increased levels of OVA-specific IgG1 and IgG2a, and goblet cell hyperplasia were continuously sustained at each time point of weeks. In contrast, we observed a time-dependent decrease in serum OVA-specific IgE, BALF eosinophils, BALF cytokines such as IL-13, transforming growth factor-beta1, and a time-dependent increase in BALF promatrix metalloproteinase-9 and peribronchial fibrosis. In this OVA-induced chronic asthma model, we observed airway remodelings as well as various cytokines and inflammatory cells being involved in different time-dependent manners. However, increased airway fibrosis did not directly correlate with a further increase in airway hyperresponsiveness.     

Dysfunction and remodeling of the mouse airway persist after resolution of acute allergen-induced airway inflammation

The mechanisms underlying airway hyperresponsiveness remain unclear, although airway inflammation and remodeling are likely important contributing factors. We hypothesized that airway physiology would differ between mice subjected to brief or chronic allergen exposure, and that these differences would be associated with characteristic inflammatory markers and indices of airway remodeling. BALB/c mice were sensitized to ovalbumin and studied at several time points following brief or chronic allergen challenge protocols. By measuring airway responses to methacholine, we demonstrated increases in maximal inducible bronchoconstriction that persisted for 8 wk following either brief or chronic allergen challenge; we also observed increases in airway reactivity, although it was only in chronically challenged mice that these changes persisted beyond the resolution of allergen-induced inflammation. Using airway morphometry, we further demonstrated that increases in maximal bronchoconstriction were associated with increases in airway contractile tissue in both models, and that chronic, but not brief, allergen challenge resulted in subepithelial fibrosis. Our observations that different aspects of sustained airway dysfunction and remodeling persist beyond the resolution of acute inflammatory events support the concept that remodeling occurs as a consequence of allergic airway inflammation, and that these structural changes contribute independently to the persistence of airway hyperresponsiveness.     

The effect of allergen-induced airway inflammation on airway remodeling in a murine model of allergic asthma

OBJECTIVE AND DESIGN: We examined the effect of airway inflammation on airway remodeling and bronchial responsiveness in a mouse model of allergic asthma. MATERIALS AND METHODS: BALB/c mice were sensitized to ovalbumin (OA), and exposed to aerosolized OA (0.01, 0.1 and 1%). Twenty-four hours after the final antigen challenge, bronchial responsiveness was measured, and bronchoalveolar lavage (BAL) and histological examinations were carried out. RESULTS: Repeated antigen exposure induced airway inflammation, IgE/IgG1 responses, epithelial changes, collagen deposition in the lungs, subepithelial fibrosis associated with increases in the amount of transforming growth factor (TGF)-beta1 in BAL fluid (BALF), and bronchial hyperresponsiveness to acetylcholine. The number of eosinophils in BALF was significantly correlated with TGF-beta1 production in BALF and the amount of hydroxyproline. Furthermore, significant correlations were found between these fibrogenic parameters and the bronchial responsiveness. CONCLUSION: These findings demonstrated that in this murine model airway eosinophilic inflammation is responsible for the development of airway remodeling as well as bronchial hyperresponsiveness in allergic bronchial asthma.     

Effects of a low-molecular-weight CCR-3 antagonist on chronic experimental asthma

Eosinophils represent one of the main effector cell populations of allergic airway inflammation and allergic bronchial asthma. Their infiltration correlates with many characteristics of the disease, including airway hyperresponsiveness (AHR) and increased mucus production. CCR-3 is the principle chemokine receptor involved in eosinophil attraction into inflamed tissue. Therefore, antagonizing CCR-3 could be a novel promising approach toward asthma therapy. We investigated the effect of a low-molecular-weight CCR-3 antagonist on established airway inflammation in a chronic model of experimental bronchial asthma. For this purpose, BALB/c mice intraperitoneally sensitized with ovalbumin (OVA) were chronically challenged with OVA aerosol to induce chronic airway inflammation and airway remodeling. The effect of antagonizing CCR-3 on asthma pathology was examined in BAL and lung histology. Airway reactivity was assessed by head-out body plethysmography. Treatment with the CCR-3 antagonist resulted in a marked reduction of eosinophils in the bronchoalveolar lumen and in airway wall tissue, whereas infiltration of lymphocytes or macrophages remained unchanged. The reduction in eosinophil infiltration was accompanied by normalization of AHR and prevention of goblet cell hyperplasia, indicating reduced mucus production. Furthermore, antagonizing CCR-3 prevented airway remodeling as defined by subepithelial fibrosis and increased accumulation of myofibrocytes in the airway wall of chronically challenged mice. These data demonstrate that antagonism of CCR3 reduces eosinophil numbers, which is accompanied by diminution of asthma pathology in a mouse model of established chronic experimental asthma. Therefore, antagonizing CCR-3 represents a new approach toward a promising asthma therapy.     

Prevention of allergic airway hyperresponsiveness and remodeling in mice by <Emphasis Type="Italic">Astragaliradix</Emphasis> Antiasthmatic decoction

Background

Astragali radix Antiasthmatic Decoction (AAD), a traditional Chinese medication, is found effective in treating allergic diseases and chronic cough. The purpose of this study is to determine whether this medication could suppress allergen-induced airway hyperresponsiveness (AHR) and remodeling in mice, and its possible mechanisms.

Methods

A mouse model of chronic asthma was used to investigate the effects of AAD on the airway lesions. Mice were sensitized and challenged with ovalbumin (OVA), and the extent of AHR and airway remodeling were characterized. Cells and cytokines in the bronchoalveolar lavage fluid (BALF) were examined.

Results

AAD treatment effectively decreased OVA-induced AHR, eosinophilic airway inflammation, and collagen deposition around the airway. It significantly reduced the levels of IL-13 and TGF-β1, but exerted inconsiderable effect on INF-γ and IL-10.

Conclusions

AAD greatly improves the symptoms of allergic airway remodeling probably through inhibition of Th2 cytokines and TGF-β1.

     

Inflammatory and remodeling events in asthma with chronic exposure to house dust mites: a murine model

Although animal models with ovalbumin have been used to study chronic asthma, there are difficulties in inducing recurrence as well as in maintaining chronic inflammation in this system. Using a murine model of house dust mite (HDM)-induced bronchial asthma, we examined the airway remodeling process in response to the chronic exposure to HDM. During the seventh and twelfth weeks of study, HDM were inhaled through the nose for three consecutive days and airway responsiveness was measured. Twenty-four hours later, bronchoalveolar lavage and histological examination were performed. The degree of overproduction of mucus, subepithelial fibrosis, and the thickness of the peribronchial smooth muscle in the experimental group was clearly increased compared to the control group. In addition, HDM-exposed mice demonstrated severe airway hyperreactivity to methacholine. In the bronchoalveolar lavage fluid, the number of total cells and eosinophils was increased; during the twelfth week, the number of neutrophils increased in the experimental group. With regard to changes in cytokines, the concentrations of IL-4, IL- 13, and transforming growth factor-beta (TGF-beta) were increased in the experimental group. The data suggest that eosinophils, IL-4, IL-13, and TGF-beta might play an important role in the airway remodeling process and that neutrophils may be involved with increased exposure time.     

Flt3-ligand plasmid prevents the development of pathophysiological features of chronic asthma in a mouse model

Airway inflammation and remodeling are primary characteristics of long-standing asthma. A balance between the T_H1/T_H2 cytokines regulates the accumulation and activation of inflammatory cells, including mast cells and eosinophils. Recently, we demonstrated that pUMVC3-hFLex, an active plasmid, mammalian expression vector for the secretion of Flt3-L, reversed established airway hyperresponsiveness (AHR) in a murine model of acute allergic airway inflammation. The present experiments were undertaken to examine the effect of pUMVC3-hFLex in a chronic model of allergic airway inflammation that was established in Balb/c mice by sensitization and challenge with ovalbumin (OVA). pUMVC3-hFLex or the control plasmid, pUMVC3, were administered by injection into the muscle interior tibialis. Treatment with pUMVC3-hFLex completely reversed established AHR (p<0.05), and this effect continued even after several exposures to the allergen (p<0.05). pUMVC3-hFLex treatment prevented the development of goblet cell hyperplasia and subepithelial fibrosis, and significantly reduced serum levels of IL-4 and IL-5, and increased serum IL-10 levels (p<0.05) with no effect on serum IL-13. Serum IgE or serum total and anti-OVA IgG1 and IgG2a levels did not change. Total BALF cellularity and BALF IL-5 levels were reduced (p<0.05), but there was no significant effect on BALF IL-10 and IL-13. These results suggest that pUMVC3-hFLex treatment can prevent the development of airway remodeling and maintain airway protection in chronic experimental asthma model, and might provide a novel approach for treating chronic asthma.     

Induction of vascular remodeling in the lung by chronic house dust mite exposure

Structural changes to the lung are associated with chronic asthma. In addition to alterations to the airway wall, asthma is associated with vascular modifications, although this aspect of remodeling is poorly understood. We sought to evaluate the character and kinetics of vascular remodeling in response to chronic aeroallergen exposure. Because many ovalbumin-driven models used to investigate allergic airway disease do so in the absence of persistent airway inflammation, we used a protocol of chronic respiratory exposure to house dust mite extract (HDME), which has been shown to induce persistent airway inflammation consistent with that seen in humans with asthma. Mice were exposed to HDME intranasally for 7 or 20 consecutive weeks, and resolution of the inflammatory and remodeling response to allergen was investigated 4 weeks after the end of a 7-week exposure protocol. Measures of vascular remodeling, including total collagen deposition, procollagen I production, endothelial and smooth muscle cell proliferation, smooth muscle area, and presence of myofibroblasts, were investigated histologically in lung vessels of different sizes and locations. We observed an increase in total collagen content, which did not resolve upon cessation of allergen exposure. Other parameters were significantly increased after 7 and/or 20 weeks of allergen exposure but returned to baseline after allergen withdrawal. We conclude that respiratory HDME exposure induces airway remodeling and pulmonary vascular remodeling, and, in accordance with airway remodeling, some components of these structural changes may be irreversible.     

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.     

Effect of tiotropium bromide on airway inflammation and remodelling in a mouse model of asthma

Background Tiotropium bromide, a long acting muscarinic receptor inhibitor, is a potent agent for patients with bronchial asthma as well as chronic obstructive pulmonary disease. Objective The aim of this study was to evaluate whether tiotropium bromide can inhibit allergen‐induced acute and chronic airway inflammation, T helper (Th)2 cytokine production, and airway remodelling in a murine model of asthma. Methods Balb/c mice were sensitized and challenged acutely or chronically to ovalbumin (OVA). The impact of tiotropium bromide was assessed using these mice models by histologic, morphometric, and molecular techniques. Moreover, the effect of tiotropium bromide on Th2 cytokine production from purified human peripheral blood mononuclear cells (PBMCs) was assessed. Results Treatment with tiotropium bromide significantly reduced airway inflammation and the Th2 cytokine production in bronchoalveolar lavage fluid (BALF) in both acute and chronic models of asthma. The levels of TGF‐β1 were also reduced by tiotropium bromide in BALF in a chronic model. The goblet cell metaplasia, thickness of airway smooth muscle, and airway fibrosis were all significantly decreased in tiotropium bromide‐treated mice. Moreover, airway hyperresponsiveness (AHR) to serotonin was significantly abrogated by tiotropium bromide in a chronic model. Th2 cytokine production from spleen cells isolated from OVA‐sensitized mice was also significantly inhibited by tiotropium bromide and 4‐diphenylacetoxy‐N‐methylpiperidine methiodide, which is a selective antagonist to the M3 receptor. Finally, treatment with tiotropium bromide inhibited the Th2 cytokine production from PBMCs. Conclusion These results indicate that tiotropium bromide can inhibit Th2 cytokine production and airway inflammation, and thus may reduce airway remodelling and AHR in a murine model of asthma. Cite this as: S. Ohta, N. Oda, T. Yokoe, A. Tanaka, Y. Yamamoto, Y. Watanabe, K. Minoguchi, T. Ohnishi, T. Hirose, H. Nagase, K. Ohta and M. Adachi, Clinical & Experimental Allergy, 2010 (40) 1266–1275.     

Asthmatic changes in mice lacking T-bet are mediated by IL-13

Mice with a targeted deletion of the T-bet gene exhibit spontaneous airway hyperresponsiveness (AHR), airway inflammation, enhanced recovery of T(h)2 cytokines from bronchoalveolar lavage fluid, sub-epithelial collagen deposition and myofibroblast transformation. Here we analyze the mechanisms responsible for the chronic airway remodeling observed in these mice. CD4+ T cells isolated from the lung of T-bet-deficient mice were spontaneously activated CD44(high)CD69(high) memory T cells, with a typical T(h)2 cytokine profile. Neutralization of IL-13 but not IL-4 resulted in amelioration of AHR in airways of mice lacking T-bet. IL-13 blockade also led to reduced eosinophilia and decreased vimentin, transforming growth factor beta (TGF-beta) and alpha smooth muscle actin (alphaSMA) levels. T-bet(-/-) lung fibroblasts proliferated very rapidly and released increased amounts of TGF-beta. Interestingly, neutralization of TGF-beta ameliorated aspects of the chronic airway remodeling phenotype but did not reduce AHR. These data highlight a T-bet-directed function for IL-13 in controlling lung remodeling that is both dependent on and independent of its interaction with TGF-beta in the asthmatic airway.     

Tissue inhibitor of metalloproteinase-1 modulates allergic lung inflammation in murine asthma

Matrix metalloproteinases (MMPs) modulate development, inflammation, and repair in lungs. Tissue inhibitors of MMPs (TIMPs) interact with MMPs, controlling the intensity and nature of the response to injury. Absence of MMP-9, -2, and -8 activities is associated with altered lung inflammation during allergic sensitization. To test the hypothesis that the absence of TIMP-1 enhances allergic lung inflammation, airway hyperreactivity (AHR), and lung remodeling in asthma, we studied TIMP-1 null (TIMP-1 KO) mice and their WT controls using an ovalbumin (OVA) asthma model. TIMP-1 KO mice, compared to WT controls, developed an asthma phenotype characterized by AHR, pronounced cellular lung infiltrates, greater reduction in lung compliance, enhanced Th2 cytokine mRNA and protein expression, and altered collagen lung content associated with enhanced MMP-9 activity. Our findings support the hypothesis that TIMP-1 plays a protective role by preventing AHR and modulating inflammation, remodeling, and cytokine expression in an animal model of asthma.     

Grape Seed Proanthocyanidin Extract Attenuates Allergic Inflammation in Murine Models of Asthma

Background

Antioxidants have been suggested to alleviate the pathophysiological features of asthma, and grape seed proanthocyanidin extract (GSPE) has been reported to have powerful antioxidant activity.

Purpose

This study was performed to determine whether GSPE has a therapeutic effect on allergic airway inflammation in both acute and chronic murine model of asthma.

Methods

Acute asthma model was generated by intraperitoneal sensitization of ovalbumin (OVA) with alum followed by aerosolized OVA challenges, whereas chronic asthma model was induced by repeated intranasal challenges of OVA with fungal protease twice a week for 8?weeks. GSPE was administered by either intraperitoneal injection or oral gavage before OVA challenges. Airway hyperresponsiveness (AHR) was measured, and airway inflammation was evaluated by bronchoalveolar lavage (BAL) fluid analysis and histopathological examination of lung tissue. Lung tissue levels of various cytokines, chemokines, and growth factors were analyzed by quantitative polymerase chain reaction and ELISA. Glutathione assay was done to measure oxidative burden in lung tissue.

Results

Compared to untreated asthmatic mice, mice treated with GSPE showed significantly reduced AHR, decreased inflammatory cells in the BAL fluid, reduced lung inflammation, and decreased IL-4, IL-5, IL-13, and eotaxin-1 expression in both acute and chronic asthma models. Moreover, airway subepithelial fibrosis was reduced in the lung tissue of GSPE-treated chronic asthmatic mice compared to untreated asthmatic mice. Reduced to oxidized glutathione (GSH/GSSG) ratio was increased after GSPE treatment in acute asthmatic lung tissue.

Conclusion

GSPE effectively suppressed inflammation in both acute and chronic mouse models of asthma, suggesting a potential role of GSPE as a therapeutic agent for asthma.     

Effects of the Histone Deacetylase Inhibitor,Trichostatin A,in a Chronic Allergic Airways Disease Model in Mice

There is a need for new asthma therapies that can concurrently address airway remodeling, airway hyperresponsiveness and progressive irreversible loss of lung function, in addition to inhibiting inflammation. Histone deacetylase inhibitors (HDACi) alter gene expression by interfering with the removal of acetyl groups from histones. The HDACi trichostatin A (TSA) has pleiotropic effects targeting key pathological processes in asthma including inflammation, proliferation, angiogenesis and fibrosis. The aim was to evaluate the effects of TSA treatment in a mouse model of chronic allergic airways disease (AAD). Wild-type BALB/c mice with AAD were treated intraperitoneally with 5 mg/kg TSA or vehicle control. Airway inflammation was assessed by bronchoalveolar lavage fluid (BALF) cell counts and histological examination of lung tissue sections. Remodeling was assessed by morphometric analysis and airway hyperresponsiveness was assessed by invasive plethysmography. TSA-treated mice had a reduced number of total inflammatory cells and eosinophils within the BALF as compared to vehicle-treated mice (both p < 0.05). Furthermore, airway remodeling changes were significantly reduced with TSA compared to vehicle-treated mice, with fewer goblet cells (p < 0.05), less subepithelial collagen deposition (p < 0.05) and attenuated airway hyperresponsiveness at the highest methacholine dose. These findings demonstrate that treatment with an HDACi can concurrently reduce structural airway remodeling changes and airway hyperresponsiveness, in addition to attenuating airway inflammation in a chronic AAD model. This has important implications for the development of novel treatments for severe asthma.