Aldose reductase inhibition prevents metaplasia of airway epithelial cells

Background

Goblet cell metaplasia that causes mucus hypersecretion and obstruction in the airway lumen could be life threatening in asthma and chronic obstructive pulmonary disease patients. Inflammatory cytokines such as IL-13 mediate the transformation of airway ciliary epithelial cells to mucin-secreting goblet cells in acute as well as chronic airway inflammatory diseases. However, no effective and specific pharmacologic treatment is currently available. Here, we investigated the mechanisms by which aldose reductase (AR) regulates the mucus cell metaplasia in vitro and in vivo.

Methodology/Findings

Metaplasia in primary human small airway epithelial cells (SAEC) was induced by a Th2 cytokine, IL-13, without or with AR inhibitor, fidarestat. After 48 h of incubation with IL-13 a large number of SAEC were transformed into goblet cells as determined by periodic acid-schiff (PAS)-staining and immunohistochemistry using antibodies against Mucin5AC. Further, IL-13 significantly increased the expression of Mucin5AC at mRNA and protein levels. These changes were significantly prevented by treatment of the SAEC with AR inhibitor. AR inhibition also decreased IL-13-induced expression of Muc5AC, Muc5B, and SPDEF, and phosphorylation of JAK-1, ERK1/2 and STAT-6. In a mouse model of ragweed pollen extract (RWE)-induced allergic asthma treatment with fidarestat prevented the expression of IL-13, phosphorylation of STAT-6 and transformation of epithelial cells to goblet cells in the lung. Additionally, while the AR-null mice were resistant, wild-type mice showed goblet cell metaplasia after challenge with RWE.

Conclusions

The results show that exposure of SAEC to IL-13 caused goblet cell metaplasia, which was significantly prevented by AR inhibition. Administration of fidarestat to mice prevented RWE-induced goblet cell metaplasia and AR null mice were largely resistant to allergen induced changes in the lung. Thus our results indicate that AR inhibitors such as fidarestat could be developed as therapeutic agents to prevent goblet cell metaplasia in asthma and related pathologies.     

Neutrophil elastase induces mucus cell metaplasia in mouse lung

Goblet cell hyperplasia in the superficial airway epithelia is a signature pathological feature of chronic bronchitis and cystic fibrosis. In these chronic inflammatory airway diseases, neutrophil elastase (NE) is found in high concentrations in the epithelial lining fluid. NE has been reported to trigger mucin secretion and increase mucin gene expression in vitro. We hypothesized that chronic NE exposure to murine airways in vivo would induce goblet cell metaplasia. Human NE (50 microg) or PBS saline was aspirated intratracheally by male Balb/c (6 wk of age) mice on days 1, 4, and 7. On days 8, 11, and 14, lung tissues for histology and bronchoalveolar lavage (BAL) samples for cell counts and cytokine levels were obtained. NE induced Muc5ac mRNA and protein expression and goblet cell metaplasia on days 8, 11, and 14. These cellular changes were the result of proteolytic activity, since the addition of an elastase inhibitor, methoxysuccinyl Ala-Ala-Pro-Val chloromethylketone (AAPV-CMK), blocked NE-induced Muc5ac expression and goblet cell metaplasia. NE significantly increased keratinocyte-derived chemokine and IL-5 in BAL and increased lung tissue inflammation and BAL leukocyte counts. The addition of AAPV-CMK reduced these measures of inflammation to control levels. These experiments suggest that NE proteolytic activity initiates an inflammatory process leading to goblet cell metaplasia.     

Antibody to mCLCA3 Suppresses Symptoms in a Mouse Model of Asthma

Background

Asthma is a complex and heterogeneous chronic inflammatory disorder that is associated with mucous cell metaplasia and mucus hypersecretion. Functional genomic analysis indicates that mucous cell metaplasia and mucus hypersecretion depend on members of the calcium-activated chloride channel (CLCA) gene family. It has been reported that the inhibition of CLCAs could relieve the symptoms of asthma. Thus, the mCLCA3 antibody may be a promising strategy to treat allergic diseases such as asthma.

Methods

We constructed asthmatic mouse models of OVA-induced chronic airway inflammatory disorder to study the function of the mCLCA3 antibody. Airway inflammation was measured by HE staining; goblet cell hyperplasia and mucus hypersecretion were detected by PAS staining; muc5ac, IL-13, IFN-γ levels in bronchoalveolar lavage fluid (BALF) were examined by ELISA; Goblet cell apoptosis was measured by TUNEL assay and alcian blue staining; mCLCA3, Bcl-2 and Bax expression were detected by RT-PCR, Western blotting and immunohistochemical analysis.

Results

In our study, mice treated with mCLCA3 antibody developed fewer pathological changes compared with control mice and asthmatic mice, including a remarkable reduction in airway inflammation, the number of goblet cells and mCLCA3 expression in lung tissue. The levels of muc5ac and IL-13 were significantly reduced in BALF. We also found that the rate of goblet cell apoptosis was increased after treatment with mCLCA3 antibody, which was accompanied by an increase in Bax levels and a decrease in Bcl-2 expression in goblet cells.

Conclusions

Taken together, our results indicate that mCLCA3 antibody may have the potential as an effective pharmacotherapy for asthma.     

CXCR2 is essential for maximal neutrophil recruitment and methacholine responsiveness after ozone exposure

Ozone (O(3)), a common air pollutant, induces airway inflammation and airway hyperresponsiveness. In mice, the neutrophil chemokines KC and macrophage inflammatory protein-2 (MIP-2) are expressed in the lungs following O(3) exposure. The purpose of this study was to determine whether CXCR2, the receptor for these chemokines, is essential to O(3)-induced neutrophil recruitment, injury to lungs, and increases in respiratory system responsiveness to methacholine (MCh). O(3) exposure (1 ppm for 3 h) increased the number of neutrophils in the bronchoalveolar lavage fluid (BALF) of wild-type (BALB/c) and CXCR2-deficient mice. However, CXCR2-deficient mice had significantly fewer emigrated neutrophils than did wild-type mice. The numbers of neutrophils in the blood and concentrations of BALF KC and MIP-2 did not differ between genotypes. Together, these data suggest CXCR2 is essential for maximal chemokine-directed migration of neutrophils to the air spaces. In wild-type mice, O(3) exposure increased BALF epithelial cell numbers and total protein levels, two indirect measures of lung injury. In contrast, in CXCR2-deficient mice, the number of BALF epithelial cells was not increased by O(3) exposure. Responses to inhaled MCh were measured by whole body plethysmography using enhanced pause as the outcome indicator. O(3) exposure increased responses to inhaled MCh in both wild-type and CXCR2-deficient mice 3 h after O(3) exposure. However, at 24 h after exposure, responses to inhaled MCh were elevated in wild-type but not CXCR2-deficient mice. These results indicate CXCR2 is essential for maximal neutrophil recruitment, epithelial cell sloughing, and persistent increases in MCh responsiveness after an acute O(3) exposure.     

Aggravation of Allergic Airway Inflammation by Cigarette Smoke in Mice Is CD44-Dependent

Background

Although epidemiological studies reveal that cigarette smoke (CS) facilitates the development and exacerbation of allergic asthma, these studies offer limited information on the mechanisms involved. The transmembrane glycoprotein CD44 is involved in cell adhesion and acts as a receptor for hyaluronic acid and osteopontin. We aimed to investigate the role of CD44 in a murine model of CS-facilitated allergic airway inflammation.

Methods

Wild type (WT) and CD44 knock-out (KO) mice were exposed simultaneously to house dust mite (HDM) extract and CS. Inflammatory cells, hyaluronic acid (HA) and osteopontin (OPN) levels were measured in bronchoalveolar lavage fluid (BALF). Proinflammatory mediators, goblet cell metaplasia and peribronchial eosinophilia were assessed in lung tissue. T-helper (Th) 1, Th2 and Th17 cytokine production was evaluated in mediastinal lymph node cultures.

Results

In WT mice, combined HDM/CS exposure increased the number of inflammatory cells and the levels of HA and OPN in BALF and Th2 cytokine production in mediastinal lymph nodes compared to control groups exposed to phosphate buffered saline (PBS)/CS, HDM/Air or PBS/Air. Furthermore, HDM/CS exposure significantly increased goblet cell metaplasia, peribronchial eosinophilia and inflammatory mediators in the lung. CD44 KO mice exposed to HDM/CS had significantly fewer inflammatory cells in BALF, an attenuated Th2 cytokine production, as well as decreased goblet cells and peribronchial eosinophils compared to WT mice. In contrast, the levels of inflammatory mediators were similar or higher than in WT mice.

Conclusion

We demonstrate for the first time that the aggravation of pulmonary inflammation upon combined exposure to allergen and an environmental pollutant is CD44-dependent. Data from this murine model of concomitant exposure to CS and HDM might be of importance for smoking allergic asthmatics.     

Increased airway epithelial Na+ absorption produces cystic fibrosis-like lung disease in mice

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene result in defective epithelial cAMP-dependent Cl(-) secretion and increased airway Na(+) absorption. The mechanistic links between these altered ion transport processes and the pathogenesis of cystic fibrosis lung disease, however, are unclear. To test the hypothesis that accelerated Na(+) transport alone can produce cystic fibrosis-like lung disease, we generated mice with airway-specific overexpression of epithelial Na(+) channels (ENaC). Here we show that increased airway Na(+) absorption in vivo caused airway surface liquid (ASL) volume depletion, increased mucus concentration, delayed mucus transport and mucus adhesion to airway surfaces. Defective mucus transport caused a severe spontaneous lung disease sharing features with cystic fibrosis, including mucus obstruction, goblet cell metaplasia, neutrophilic inflammation and poor bacterial clearance. We conclude that increasing airway Na(+) absorption initiates cystic fibrosis-like lung disease and produces a model for the study of the pathogenesis and therapy of this disease.     

IL-4 induces mucin gene expression and goblet cell metaplasia in vitro and in vivo

Goblet cell metaplasia and mucus hypersecretion are important features in the pathogenesis of asthma. The cytokine IL-4 has been shown to play a role in animal models of asthma, where it induces Th2 lymphocyte differentiation and B lymphocyte IgE class switch. IL-4 has also been implicated in the differentiation of goblet cells via effects on lymphocytes and eosinophils. In this study we hypothesized that IL-4 induces airway epithelial cell mucin gene expression and mucous glycoconjugate production by direct action on these cells. In vitro, cultured airway epithelial cells (NCI-H292) expressed IL-4R constitutively, and IL-4 (10 ng/ml) induced MUC2 gene expression and mucous glycoconjugate production. In vivo, mouse airway epithelial cells expressed IL-4R constitutively, and IL-4 (250 ng) increased MUC5 gene expression and Alcian blue/periodic acid-Schiff-positive staining at 24 h; IL-4 did not increase inflammatory cell numbers in airway tissue or in bronchoalveolar lavage. TNF-alpha and IL-1beta levels in bronchoalveolar lavage were not increased in response to IL-4 instillation. These results indicate that airway epithelial cells express IL-4R constitutively and that IL-4 directly induces the differentiation of epithelium into mucous glycoconjugate-containing goblet cells.     

Bulleyaconitine A inhibits the lung inflammation and airway remodeling through restoring Th1/Th2 balance in asthmatic model mice

ABSTRACT

The current study aimed to study the effects of Bulleyaconitine A (BLA) on asthma. Asthmatic mice model was established by ovalbumin (OVA) stimulation, and the model mice were treated by BLA. After BLA treatment, the changes in lung and airway resistances, total and differential leukocytes in the bronchoalveolar lavage fluid (BALF) were detected, and the changes in lung inflammation and airway remodeling were observed. Moreover, the secretion of IgE, Th1/Th2-type and IL-17A cytokines in BALF and serum of the asthmatic mice were determined. The resuts showed that BLA attenuated OVA-induced lung and airway resistances, inhibited the inflammatory cell recruitment in BALF and the inflammation and airway remodeling of the asthmatic mice. In addition, BLA suppressed the secretion of IgE, Th2-type cytokines, and IL-17A, but enhanced secretions of Th1-type cytokines in BALF and serum. The current study discovered that BLA inhibited the lung inflammation and airway remodeling via restoring the Th1/Th2 balance in asthmatic mice.     

Cold weather exercise and airway cytokine expression.

Athletes who perform repeated exercise while breathing cold air have a high prevalence of asthmalike chronic airway disease, but the mechanism linking such activity to airway inflammation is unknown. We used a novel animal model (exercising horses) to test the hypothesis that exercise-induced chronic airway disease is caused by exposure of intrapulmonary airways to unconditioned air, resulting in the upregulation of cytokine expression. Bronchoalveolar lavage fluid (BALF) was obtained from eight horses 5 h after submaximal exercise while they breathed room temperature or subfreezing air in a random crossover design. BALF total and differential nucleated cell counts were determined, and relative cytokine mRNA expression in BALF nucleated cells was quantified by real-time RT-PCR using primer and probe sequences specific for equine targets. There were no significant changes in total or differential cell concentrations between BALF recovered after warm and cold air exercise, although there was a strong trend toward increased concentrations of airway epithelial cells after cold air exercise (P = 0.0625). T(H)2 cytokines IL-4, IL-5, and IL-10 were preferentially upregulated after cold air exercise 12-, 9-, and 10-fold, respectively, compared with warm air exercise. Other cytokines (IL-2 and IL-6) were upregulated to a lesser extent (6- and 3-fold, respectively) or not at all (IL-1, IL-8, IFN-gamma, and TNF-alpha). These results suggest that cold weather exercise can lead to asthmalike airway disease through the local induction of cytokines typical of the T(H)2 phenotype.     

Serine protease inhibitor attenuates ovalbumin induced inflammation in mouse model of allergic airway disease

Background

Serine proteases promote inflammation and tissue remodeling by activating proteinase-activated receptors, urokinase, metalloproteinases and angiotensin. In the present study, 4-(2-Aminoethyl) benzenesulfonyl fluoride (AEBSF) a serine protease inhibitor was evaluated for prophylactic and therapeutic treatment in mouse model of airway allergy.

Methods

BALB/c mice were sensitized by i.p route and challenged with ovalbumin. They were treated i.n. with 2, 10 and 50 µg of AEBSF, one hour before or after challenge and euthanized to collect BALF (bronchoalveolar lavage fluid), blood and lungs. Proteolytic activity, total cell/eosinophil/neutrophil count eosinophil peroxidase activity (EPO), IL-4, IL-5, IL-10, IL-13, cysteinyl leukotrienes and 8-isoprostane were determined in BALF and immunoglobulins were measured in serum. H&E and PAS stained lung sections were examined for cellular infiltration and airway inflammation.

Results

Mice exposed to ovalbumin and treated with PBS showed increased cellular infiltration in lungs and higher serum IgE, IgG1 and IgG2a levels as compared to sham mice. Treatment with AEBSF reduced total cells/eosinophil/neutrophil infiltration. Both prophylactic and therapeutic AEBSF treatment of 10 or 50 µg reduced serum IgE and IgG1 significantly (p<0.05) than control. AEBSF treatment reduced the proteolytic activity in BALF. IL-4 IL-5 and IL-13 levels decreased significantly (p<0.05) after AEBSF treatment while IL-10 levels increased significantly (p<0.05) in BALF. Airway inflammation and goblet cell hyperplasia reduced as demonstrated by lung histopathology, EPO activity and cysteinyl leukotrienes in BALF after treatment. AEBSF treatment also suppressed oxidative stress in terms of 8-isoprostane in BALF. Among the treatment doses, 10 or 50 µg of AEBSF were most effective in reducing the inflammatory parameters.

Conclusions

Prophylactic and therapeutic treatment with serine protease inhibitor attenuates the airway inflammation in mouse model of airway allergy and have potential for adjunct therapy.     

Il-13 and IFN-gamma: interactions in lung inflammation

Chronic inflammatory diseases of the lungs, such as asthma, are frequently associated with mixed (Th2 and Th1) T cell responses. We examined the impact of critical Th1 and Th2 cytokines, IFN-gamma and IL-13, on the responses in the lungs. In a mouse model of airway inflammation induced by mixed T cell responses, the number of Th1 (IFN-gamma-positive) cells was found to be negatively correlated with airway hyperreactivity. In these mice, blockade of IL-13 partially inhibited airway hyperreactivity and goblet cell hyperplasia but not inflammation. In contrast, in mice that responded with a polarized Th2 response to the same Ag, blockade of IL-13 inhibited airway hyperreactivity, goblet cell hyperplasia, and airway inflammation. These results indicated that the presence of IFN-gamma would modulate the effects of IL-13 in the lungs. To test this hypothesis, wild-type mice were given recombinant cytokines intranasally. IFN-gamma inhibited IL-13-induced goblet cell hyperplasia and airway eosinophilia. At the same time, IFN-gamma and IL-13 potentiated each other's effects. In the airways of mice given IL-13 and IFN-gamma, levels of IL-6 were increased as well as numbers of NK cells and of CD11c-positive cells expressing MHC class II and high levels of CD86. In conclusion, IFN-gamma has double-sided effects (inhibiting some, potentiating others) on IL-13-induced changes in the lungs. This may be the reason for the ambiguous role of Th1 responses on Th2 response-induced lung injury.     

Apoptosis of airway epithelial cells in response to meconium

Meconium aspiration syndrome (MAS) is common among newborn children but its mechanism is unclear. The syndrome is known to produce a strong inflammatory reaction in the lungs resulting in massive cell death. In this work we studied lung cell death by apoptosis after meconium aspiration in forty two-week-old rabbit pups. Analyzing lung samples by ISEL-DNA end labeling demonstrated the specific spread of apoptotic bodies throughout the lungs. These bodies were shrunken and smaller in size compared to normal cells and many of them were lacking cell membranes. About 70% of all apoptotic bodies were found among the airway epithelium cell eight hours after meconium instillation. In comparison, among lung alveolar cells, only about 20% cells were apoptotic in the same animals. In meconium-treated lungs and A549 cells, a significant increase of angiotensinogen mRNA and Caspase-3 expression were observed. The pretreatment of cells with Caspase-3 inhibitor ZVAD-fmk significantly inhibited meconium-induced lung cell death by apoptosis. These findings demonstrate the apoptotic process in meconium-instilled lungs or A549 cells in culture. Our results show lung airway epithelial and A549 cell apoptosis after meconium instillation. We suggest that studies of lung airway epithelial cell death are essential to understanding the pathophysiology of MAS and may present a key point in future therapeutic applications.     

Inhibition of mucin secretion with MARCKS-related peptide improves airway obstruction in a mouse model of asthma.

Allergic asthma is associated with airway epithelial cell mucous metaplasia and mucin hypersecretion, but the consequences of mucin hypersecretion on airway function are unclear. Recently, a peptide derived from the myristoylated alanine-rich C kinase substrate protein NH(2)-terminal sequence (MANS) was shown to inhibit methacholine (MCh)-induced mucin secretion from airway mucous cells by >90%. We studied the effect of intranasal pretreatment with this peptide on specific airway conductance (sGaw) during challenge with MCh in mice with allergen-induced mucous cell metaplasia. sGaw was noninvasively measured in spontaneously breathing restrained mice, using a double-chamber plethysmograph. Pretreatment with MANS peptide, but not a control peptide [random NH(2)-terminal sequence (RNS)], resulted in partial inhibition of the fall in sGaw induced by 60 mM MCh (mean +/- SE; baseline 1.15 +/- 0.06; MANS/MCh 0.82 +/- 0.05; RNS/MCh 0.55 +/- 0.05 cmH(2)O/s). The protective effect of MANS was also seen in mice challenged with allergen for 3 consecutive days to increase airway hyperresponsiveness, although the degree of protection was less (baseline 1.1 +/- 0.08; MANS/MCh, 0.65 +/- 0.06; RNS/MCh 0.47 +/- 0.03 cmH(2)O/s). Because routine sGaw measurement in mice includes nasal airways, the effectiveness of MANS was also confirmed in mice breathing through their mouths after nasal occlusion (baseline 0.92 +/- 0.05; MANS/MCh 0.83 +/- 0.06; RNS/MCh 0.61 +/- 0.03 cmH(2)O/s). In all instances, sGaw in the MANS-pretreated group was approximately 35% higher than in RNS-treated controls, and mucous obstruction accounted for approximately 50% of the MCh-induced fall in sGaw. In summary, mucin secretion has a significant role in airway obstruction in a mouse model of allergic asthma, and strategies to inhibit mucin secretion merit further investigation.     

PAF mediates cigarette smoke-induced goblet cell metaplasia in guinea pig airways

Goblet cell metaplasia is an important morphological feature in the airways of patients with chronic airway diseases; however, the precise mechanisms that cause this feature are unknown. We investigated the role of endogenous platelet-activating factor (PAF) in airway goblet cell metaplasia induced by cigarette smoke in vivo. Guinea pigs were exposed repeatedly to cigarette smoke for 14 consecutive days. The number of goblet cells in each trachea was determined with Alcian blue-periodic acid-Schiff staining. Differential cell counts and PAF levels in bronchoalveolar lavage fluid were also evaluated. Cigarette smoke exposure significantly increased the number of goblet cells. Eosinophils, neutrophils, and PAF levels in bronchoalveolar lavage fluid were also significantly increased after cigarette smoke. Treatment with a specific PAF receptor antagonist, E-6123, significantly attenuated the increases in the number of airway goblet cells, eosinophils, and neutrophils observed after cigarette smoke exposure. These results suggest that endogenous PAF may play a key role in goblet cell metaplasia induced by cigarette smoke and that potential roles exist for inhibitors of PAF receptor in the treatment of hypersecretory airway diseases.     

Lunasin Alleviates Allergic Airway Inflammation while Increases Antigen-Specific Tregs

Lunasin is a naturally occurring peptide isolated from soybeans and has been explored in cancer treatment. Lunasin inhibits NF-κB activation and thus pro-inflammatory cytokine and mediator production in macrophages. In this study we demonstrate that lunasin can effectively suppress allergic airway inflammation in two murine models of asthma. In an OVA+Alum sensitization model, intranasal lunasin treatment at the time of OVA challenges significantly reduced total cells counts in bronchoalveolar lavage (BAL) fluid and eosinophilia, peribronchiolar inflammatory infiltration, goblet cell metaplasia and airway IL-4 production. In an OVA+LPS intranasal sensitization model, lunasin treatment either at the time of sensitization or challenge has similar effects in suppress allergic airway inflammation including significantly reduced total cell and eosinophil counts in BAL fluid, inflammatory gene Fizz1 expression in the lung, and IL-4 production by OVA re-stimulated cells from mediastinal lymph nodes. We further show that intranasal instillation of OVA+lunasin significantly increases OVA-specific regulatory T cell (Treg) accumulation in the lung comparing to OVA only treatment. Taken together, our results suggest lunasin as an anti-inflammatory agent can be potentially used in asthma therapy or as an adjuvant to enhance the induction of antigen-specific Tregs and thus boost the efficacy of allergy immunotherapy.     

丁苯酞对哮喘小鼠气道黏液高分泌及IL-13、TNF-α的影响*

目的: 研究丁苯酞对哮喘小鼠气道黏液高分泌及白介素-13(IL-13)、肿瘤坏死因子-α(TNF-α)的影响。方法: 小鼠随机分为空白对照组、模型对照组、阳性对照组和丁苯酞高、中、低剂量(100、50、25 mg/kg)组(n=12)。实验第1日、8日、15日通过注射卵清白蛋白(OVA)致敏,第22日吸入OVA连续激发5周复制哮喘模型,同时在激发前给予丁苯酞20 mg/kg进行干预,观测哮喘行为学、气道杯状细胞及黏蛋白5ac(Muc5ac)的分泌,测定支气管肺泡灌洗液(BALF)粘度,采用ELISA法测定BALF中Muc5ac、IL-13及TNF-α的水平。结果: 与空白对照组比较,模型对照组小鼠打喷嚏、抓鼻及哮喘的程度显著加重(P＜0.01),小鼠气道上皮杯状细胞增生及Muc5ac的分泌显著增加(P＜0.01),BALF的粘度及其中的Muc5ac、IL-13和TNF-α的含量显著升高(P＜0.01);与模型对照组比较,25、50、100 mg/kg丁苯酞干预后哮喘行为学评分明显下降(P＜0.01);小鼠气道上皮杯状细胞增生、Muc5ac的分泌、BALF的粘度及其中的Muc5ac、IL-13和TNF-α的含量均明显降低(P＜0.05, 0.01)。结论: 丁苯酞具有抑制哮喘气道黏液高分泌而平喘的作用,缓解IL-13、TNF-α异常高表达是其抑制气道黏液高分泌的作用机制之一。     

CD4(+) T cell-dependent airway mucus production occurs in response to IL-5 expression in lung

The potential role of airway interleukin-5 (IL-5) expression in eliciting mucus production was demonstrated in a pulmonary IL-5 transgenic mouse model (NJ.1726) in which naive transgenic mice display comparable levels of airway mucus relative to allergen-sensitized and -challenged wild-type mice. The intrinsic mucus accumulation of NJ.1726 was abolished in compound transgenic-gene knockout mice deficient of either CD4(+) cells [NJ.1726/CD4(-/-)] or alphabeta T cell receptor-positive (TCR(+)) cells [NJ.1726/alphabeta TCR(-/-)]. In addition, mucus production in naive NJ.1726 was inhibited by >90% after administration of the soluble anti-IL-4 receptor alpha-subunit antagonist. The loss of mucus production in NJ.1726/CD4(-/-), NJ.1726/alphabeta TCR(-/-), and anti-IL-4 receptor alpha-subunit antagonist-treated mice occurred notwithstanding the significant pulmonary eosinophilia and expansion of airway B cells induced by ectopic IL-5 expression. Furthermore, the loss of mucus accumulation occurred in these mice despite elevated levels of airway and peripheral IL-5, indicating that IL-5 does not directly induce goblet cell metaplasia and mucus production. Thus pulmonary expression of IL-5 alone is capable of inducing CD4(+) T cell-dependent goblet cell metaplasia, apparently mediated by IL-4 receptor alpha-subunit-ligand interactions, and represents a previously unrecognized novel pathway for augmenting allergen-induced mucus production.     

Matrix metalloproteinase-8 deficiency promotes granulocytic allergen-induced airway inflammation

Matrix metalloproteinases (MMPs) are involved in inflammatory reaction, including asthma-related airway inflammation. MMP-8, mainly produced by neutrophils, has recently been reported to be increased in the bronchoalveolar lavage fluid (BALF) from asthmatic patients. To evaluate the role of MMP-8 in asthma, we measured MMP-8 expression in lung tissue in an OVA-sensitized mouse model of asthma and addressed the effect of MMP-8 deletion on allergen-induced bronchial inflammation. MMP-8 production was increased in lungs from C57BL/6 mice exposed to allergens. After allergen exposure, MMP-8(-/-) mice developed an airway inflammation characterized by an increased neutrophilic inflammation in BALF and an increased neutrophilic and eosinophilic infiltration in the airway walls. MMP-8 deficiency was associated with increased levels of IL-4 and anti-OVA IgE and IgG1 in BALF and serum, respectively. Although allergen exposure induced an enhancement of LPS-induced CXC chemokine, KC, and MIP-2 levels in BALF and lung parenchyma, no difference was observed between the two genotypes. Inflammatory cell apoptosis was reduced in the lungs from MMP-8(-/-) mice. For the first time, our study evidences an important role of MMP-8 in the control of neutrophilic and eosinophilic infiltration during allergen-induced lung inflammation, and demonstrates that the anti-inflammatory effect of MMP-8 is partly due to a regulation of inflammatory cell apoptosis.