Polyopes affinis alleviates airway inflammation in a murine model of allergic asthma

Marine algae have been utilized in food as well as medicine products for a variety of purposes. The purpose of this study was to determine whether an ethanol extract of Polyopes affinis (P.affinis) can inhibit the pathogenesis of T helper 2 (Th2)-mediated allergen-induced airway inflammation in a murine model of asthma. Mice that were sensitized and challenged with ovalbumin (OVA) evidenced typical asthmatic reactions such as the following: an increase in the number of eosinophils in the bronchoalveolar lavage (BAL) fluid; a marked influx of inflammatory cells into the lung around blood vessels and airways as well as the narrowing of the airway luminal; the development of airway hyperresponsiveness (AHR); the presence of pulmonary Th2 cytokines; and the presence of allergenspecific immunoglobulin E (IgE) in the serum. The successive intraperitoneal administration of P. affinis ethanolic extracts before the last airway OVA-challenge resulted in a significant inhibition of all asthmatic reactions. These data suggest that P. affinis ethanolic extracts possess therapeutic potential for the treatment of pulmonary allergic disorders such as allergic asthma.     

Neovastat (AE-941) inhibits the airway inflammation and hyperresponsiveness in a murine model of asthma

Matrix metalloproteinase (MMP)-9 plays an important role in the pathogenesis of bronchial asthma. Neovastat, having significant antitumor and antimetastatic properties, is classified as a naturally occurring multifunctional antiangiogenic agent. We evaluated the therapeutic effect of Neovastat on airway inflammation in a mouse model of asthma. BALB/c mice were immunized subcutaneously with ovalbumin (OVA) on days 0, 7, 14, and 21 and challenged with inhaled OVA on days 26, 29, and 31. Neovastat was administrated by gavage (5 mg/kg body weight) three times with 12 h intervals, beginning 30 min before OVA inhalation. On day 32, mice were challenged with inhaled methacholine, and enhanced pause (Penh) was measured as an index of airway hyperresponsiveness. The severity of airway inflammation was determined by differential cell count of bronchoalveolar lavage (BAL) fluid. The MMP-9 concentration in BAL fluid samples was measured by ELISA, and MMP-9 activity was measured by zymography. The untreated asthma group showed an increased inflammatory cell count in BAL fluid and Penh value compared with the normal control group. Mice treated with Neovastat had significantly reduced Penh values and inflammatory cell counts in BAL fluid compared with untreated asthmatic mice. Furthermore, mice treated with Neovastat showed significantly reduced MMP-9 concentrations and activity in BAL fluid. These results demonstrate that Neovastat might have new therapeutic potential for airway asthmatic inflammation.     

Anti-inflammatory effects of Tat-Annexin protein on ovalbumin-induced airway inflammation in a mouse model of asthma

Chronic airway inflammation is a key feature of bronchial asthma. Annexin-1 (ANX1) is an anti-inflammatory protein that is an important modulator and plays a key role in inflammation. Although the precise action of ANX1 remains unclear, it has emerged as a potential drug target for inflammatory diseases such as asthma. To examine the protective effects of ANX1 protein on ovalbumin (OVA)-induced asthma in animal models, we used a cell-permeable Tat-ANX1 protein. Mice sensitized and challenged with OVA antigen had an increased amount of cytokines and eosinophils in their bronchoalveolar lavage (BAL) fluid. However, administration of Tat-ANX1 protein before OVA challenge significantly decreased the levels of cytokines (interleukin (IL)-4, IL-5, and IL-13) and BAL fluid in lung tissues. Furthermore, OVA significantly increased the activation of mitogen-activated protein kinase (MAPK) in lung tissues, whereas Tat-ANX1 protein markedly reduced phosphorylation of MAPKs such as extracellular signal-regulated protein kinase, p38, and stress-activated protein kinase/c-Jun N-terminal kinase. These results suggest that transduced Tat-ANX1 protein may be a potential protein therapeutic agent for the treatment of lung disorders including asthma.     

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.     

Mucosal immunotherapy with CpG oligodeoxynucleotides reverses a murine model of chronic asthma induced by repeated antigen exposure

Murine models of acute atopic asthma may be inadequate to study the effects of recurrent exposure to inhaled allergens, such as the epithelial changes seen in asthmatic patients. We developed a murine model in which chronic airway inflammation is maintained by repeated allergen [ovalbumin (OVA)] inhalation; using this model, we examined the response to mucosal administration of CpG DNA (oligonucleotides) and specific antigen immunotherapy. Mice repeatedly exposed to OVA developed significantly greater airway hyperresponsiveness and goblet cell hyperplasia, but not airway eosinophilia, compared with those exposed only twice. CpG-based immunotherapy significantly reversed both acute and chronic markers of inflammation as well as airway hyperresponsiveness. We further examined the effect of mucosal immunotherapy on the response to a second, unrelated antigen. Mice sensitized to both OVA and schistosome eggs, challenged with inhaled OVA, and then treated with OVA-directed immunotherapy demonstrated significant reduction of airway hyperresponsiveness and a moderate reduction in eosinophilia, after inhalation challenge with schistosome egg antigens. In this model, immunotherapy treatment reduced bronchoalveolar lavage (BAL) levels of Th2 cytokines (IL-4, IL-5, IL-13, and IL-10) without changing BAL IFN-gamma. Antigen recall responses of splenocytes from these mice demonstrated an antigen-specific (OVA) enhanced release of IL-10 from splenocytes of treated mice. These results suggest that CpG DNA may provide the basis for a novel form of immunotherapy of allergic asthma. Both antigen-specific and, to a lesser extent, antigen-nonspecific responses to mucosal administration of CpG DNA are seen.     

Inhalation of sphingosine kinase inhibitor attenuates airway inflammation in asthmatic mouse model

Sphingosine 1-phosphate (S1P) produced by sphingosine kinase (SPHK) is implicated in acute immunoresponses, however, mechanisms of SPHK/S1P signaling in the pathogenesis of bronchial asthma are poorly understood. In this study, we hypothesized that SPHK inhibition could ameliorate lung inflammation in ovalbumin (OVA)-challenged mouse lungs. Six- to eight-week-old C57BL/6J mice were sensitized and exposed to OVA for 3 consecutive days. Twenty-four hours later, mice lungs and bronchoalveolar lavage (BAL) fluid were analyzed. For an inhibitory effect, either of the two different SPHK inhibitors, N,N-dimethylsphingosine (DMS) or SPHK inhibitor [SK-I; 2-(p-hydroxyanilino)-4-(p-chlorophenyl) thiazole], was nebulized for 30 min before OVA inhalation. OVA inhalation caused S1P release into BAL fluid and high expression of SPHK1 around bronchial epithelial walls and inflammatory areas. DMS or SK-I inhalation resulted in a decrease in S1P amounts in BAL fluid to basal levels, accompanied by decreased eosinophil infiltration and peroxidase activity. The extent of inhibition caused by DMS inhalation was higher than that caused by SK-I. Like T helper 2 (Th2) cytokine release, OVA inhalation-induced increase in eotaxin expression was significantly suppressed by DMS pretreatment both at protein level in BAL fluid and at mRNA level in lung homogenates. Moreover, bronchial hyperresponsiveness to inhaled methacholine and goblet cell hyperplasia were improved by SPHK inhibitors. These data suggest that the inhibition of SPHK affected acute eosinophilic inflammation induced in antigen-challenged mouse model and that targeting SPHK may provide a novel therapeutic tool to treat bronchial asthma.     

Decreased expression of uteroglobin-related protein 1 in inflamed mouse airways is mediated by IL-9

Uteroglobin-related protein 1 (UGRP1) is a secretory protein, highly expressed in epithelial cells of airways. Although an involvement of UGRP1 in the pathogenesis of asthma has been suggested, its function in airways remains unclear. In the present study, a relationship between airway inflammation, UGRP1 expression, and interleukin-9 (IL-9), an asthma candidate gene, was evaluated by using a murine model of allergic bronchial asthma. A severe airway inflammation accompanied by airway eosinophilia and elevation of IL-9 in bronchoalveolar lavage (BAL) fluids was observed after ovalbumin (OVA) challenge to OVA-sensitized mice. In this animal model of airway inflammation, lung Ugrp1 mRNA expression was greatly decreased compared with control mice. A significant inverse correlation between lung Ugrp1 mRNA levels and IL-9 levels in BAL fluid was demonstrated by regression analysis (r = 0.616, P = 0.023). Immunohistochemical analysis revealed a distinct localization of UGRP1 in airway epithelial cells of control mice, whereas UGRP1 staining was patchy and faint in inflamed airways. Intranasal administration of IL-9 to naive mice decreased the level of Ugrp1 expression in lungs. These findings suggest that UGRP1 is downregulated in inflamed airways, such as allergic asthmatics, and IL-9 might be an important mediator for modulating UGRP1 expression.     

Effects of adenovirus-expressing IL-10 in alleviating airway inflammation in asthma

BACKGROUND: Allergic asthma strongly correlates with airway inflammation caused by cytokines secreted by allergen-specific type-2 T helper (Th2) cells, but the immunologic regulation of cell function is yet to be acquired. Further, IL-10 has been found to exert both antiinflammatory and immunoregulatory activities. This study aimed to elucidate the therapeutic effects of IL-10 administration via adenovirus-mediated gene delivery on airway inflammation in the ovalbumin (OVA)-induced murine model of asthma. METHODS: BALB/c mice were sensitized by intraperitoneal injections with OVA and challenged by nebulized OVA. The sensitized mice were given an intratracheal delivery of adenoviral vector expressing the murine IL-10 gene (AdIL-10), or mock adenoviral vector 4 days before the inhalation challenge of the OVA. Inflammatory parameters, such as the development of airway hyper-responsiveness (AHR), bronchial lavage fluid eosinophils, and chemokines were assayed. RESULTS: Intratracheal administration of AdIL-10 could efficiently inhibit antigen-induced AHR and significantly decrease the number of eosinophils and neutrophils in the bronchoalveolar lavage fluid of OVA-sensitized and challenged mice during the effector phase. CONCLUSIONS: Our data showed that the intratracheal transfer of the IL-10 gene could affect the recruitment of inflammatory cells during the challenge phase in a way that would result in the inhibition of airway inflammation. These findings suggest that the development of an immunoregulatory strategy based on IL-10 might shed light on more effective treatment.     

Airway hyperresponsiveness, late allergic response, and eosinophilia are reversed with mycobacterial antigens in ovalbumin-presensitized mice

Pretreatment with mycobacterial Ags has been shown to be effective in preventing allergic airway inflammation from occurring in a mouse model. Because most asthmatics are treated after the development of asthma, it is crucial to determine whether mycobacterial Ags can reverse established allergic airway inflammation in the presensitized state. Our hypothesis, based upon our previous findings, is that mycobacteria treatment in presensitized mice will suppress the allergic airway inflammation with associated clinical correlates of established asthma, with the noted exception of factors associated with the early allergic response (EAR). BALB/c mice sensitized and challenged with OVA were evaluated for pulmonary functions during both the EAR and late allergic response, and airway hyperresponsiveness to methacholine. Following this, sensitized mice were randomized and treated with placebo or a single dose (1 x 10(5) CFUs) of bacillus Calmette-Guérin (BCG) or Mycobacterium vaccae via nasal or peritoneal injection. One week later, the mice were rechallenged with OVA and methacholine, followed by bronchoalveolar lavage (BAL) and tissue collection. Mice treated with intranasal BCG were most significantly protected from the late allergic response (p < 0.02), airway hypersensitivity (p < 0.001) and hyperreactivity (p < 0.05) to methacholine, BAL (p < 0.05) and peribronchial (p < 0.01) eosinophilia, and BAL fluid IL-5 levels (p < 0.01) as compared with vehicle-treated, sensitized controls. Intranasal M. vaccae treatment was less effective, suppressing airway hypersensitivity (p < 0.01) and BAL eosinophilia (p < 0.05). No changes were observed in the EAR, BAL fluid IL-4 levels, or serum total and Ag-specific IgE. These data suggest that mycobacterial Ags (BCG>M. vaccae) are effective in attenuating allergic airway inflammation and associated changes in pulmonary functions in an allergen-presensitized state.     

Role for IgE in airway secretions: IgE immune complexes are more potent inducers than antigen alone of airway inflammation in a murine model

IgE is present in airway secretions from human patients with allergic rhinitis and bronchial asthma. However, the contribution of IgE present locally to the overall airway inflammation is not well understood. We hypothesize that Ag-specific IgE can capture airborne Ags and form immune complexes. These immune complexes may function as potent inducers of immune responses in the lung, contributing to the perpetuation of airway inflammation. BALB/c mice were first sensitized with OVA in alum systemically and then challenged with nebulized OVA. Bronchoalveolar lavage (BAL) fluid from these mice contained significant amounts of IgE, of which >50% was Ag specific. The IgE levels in airway secretions remained elevated for more than 15 days after the termination of Ag exposure. Significant amounts of IgE-OVA immune complexes were detected in BAL fluid from the OVA-challenged mice. For comparison of IgE immune complexes vs Ag alone, we treated OVA-immunized mice with intranasal administration of trinitrophenyl-OVA or trinitrophenyl-OVA-anti-DNP IgE. Those treated with the immune complexes showed significantly higher levels of IL-4 and more pronounced eosinophilia in BAL fluid than did those receiving the Ag alone. The IgE immune complexes did not augment the inflammatory response in high affinity IgE receptor (FcepsilonRI)-deficient mice. We conclude that IgE present in the airways can capture the Ag and that the immune complexes thus formed may augment allergic airway response in an FcepsilonRI-dependent manner. Thus, IgE present in airway secretions may facilitate Ag-mediated allergic airway inflammation.     

The presence of LPS in OVA inhalations affects airway inflammation and AHR but not remodeling in a rodent model of asthma

Ovalbumin (OVA) is the most frequently used allergen in animal models of asthma. Lipopolysaccharide (LPS) contaminating commercial OVA may modulate the evoked airway inflammatory response to OVA. However, the effect of LPS in OVA on airway remodeling, especially airway smooth muscle (ASM) has not been evaluated. We hypothesized that LPS in commercial OVA may enhance allergen-induced airway inflammation and remodeling. Brown Norway rats were sensitized with OVA on day 0. PBS, OVA, or endotoxin-free OVA (Ef-OVA) was instilled intratracheally on days 14, 19, 24. Bronchoalveolar lavage (BAL) fluid, lung, and intrathoracic lymph node tissues were collected 48 h after the last challenge. Immunohistochemistry for α-smooth muscle actin, Periodic-Acid-Schiff staining, and real-time qPCR were performed. Airway hyperresponsiveness (AHR) was also measured. BAL fluid macrophages, eosinophils, neutrophils, and lymphocytes were increased in OVA-challenged animals, and macrophages and neutrophils were significantly lower in Ef-OVA-challenged animals. The ASM area in larger airways was significantly increased in both OVA and Ef-OVA compared with PBS-challenged animals. The mRNA expression of IFN-γ and IL-13 in lung tissues and IL-4 in lymph nodes was significantly increased by both OVA and Ef-OVA compared with PBS and were not significantly different between OVA and Ef-OVA. Monocyte chemoattractant protein (MCP)-1 in BAL fluid and AHR were significantly increased in OVA but not in Ef-OVA. LPS contamination in OVA contributes to the influx of macrophages and MCP-1 increase in the airways and to AHR after OVA challenges but does not affect OVA-induced Th1 and Th2 cytokine expression, goblet cell hyperplasia, and ASM remodeling.     

Effect of fudosteine,a cysteine derivative,on airway hyperresponsiveness,inflammation, and remodeling in a murine model of asthma

AimsFudosteine is a cysteine derivative that is used as an expectorant in chronic bronchial inflammatory disorders. It has been shown to decrease the number of goblet cells in an animal model. This study examined the effects of fudosteine on airway inflammation and remodeling in a murine model of chronic asthma.Main methodsBALB/c mice were sensitized by an intraperitoneal injection of ovalbumin (OVA), and subsequently challenged with nebulized ovalbumin three days a week for four weeks. Seventy-two hours after the fourth challenge, airway hyperresponsiveness (AHR) and the cell composition of bronchoalveolar lavage (BAL) fluid were assessed. Fudosteine was administered orally at 10 mg/kg or 100 mg/kg body weight from the first to the fourth challenge.Key findingsWe investigated the effects of fudosteine on the development of allergic airway inflammation and airway hyperresponsiveness after chronic allergen challenges. The administration of fudosteine during the challenge with ovalbumin prevented the development of airway hyperresponsiveness and accumulation of lymphocytes in the airways. Eotaxin, IL-4, and TGF-β levels and the relative intensity of matrix metalloproteinase-2 and matrix metalloproteinase-9 (MMP-2 and MMP-9) in BAL fluid were reduced by the fudosteine treatment; however, the number of eosinophils in BAL fluid and serum IgE levels did not change. The expression of TGF-β, the development of goblet cell hyperplasia, subepithelial collagenization, and basement membrane thickening were also reduced by the fudosteine treatment.SignificanceThese results indicate that fudosteine is effective in reducing airway hyperresponsiveness, airway inflammation, and airway remodeling in a murine model of chronic asthma.     

Retnla Overexpression Attenuates Allergic Inflammation of the Airway

Resistin-like molecule alpha (Retnla), also known as ‘Found in inflammatory zone 1’, is a secreted protein that has been found in bronchoalveolar lavage (BAL) fluid of ovalbumin (OVA)-induced asthmatic mice and plays a role as a regulator of T helper (Th)2-driven inflammation. However, the role of Retnla in the progress of Th2-driven airway inflammation is not yet clear. To better understand the function of Retnla in Th2-driven airway inflammation, we generated Retnla-overexpressing (Retnla-Tg) mice. Retnla-Tg mice showed increased expression of Retnla protein in BAL fluid and airway epithelial cells. Retnla overexpression itself did not induce any alteration in lung histology or lung function compared to non-Tg controls. However, OVA-sensitized/challenged Retnla-Tg mice had decreased numbers of cells in BAL and inflammatory cells accumulating in the lung. They also showed a reduction in mucus production in the airway epithelium, concomitant with a decreased Muc5ac level. These results were accompanied by reduced levels of Th2 cytokines, including interleukin (IL)-4, IL-5, and IL-13, with no effect on levels of OVA-specific immunoglobulin isotypes. Furthermore, phosphorylation of ERK was markedly reduced in the lungs of OVA-challenged Retnla-Tg mice. Taken together, these results indicates that Retnla protects against Th2-mediated inflammation in an experimental mouse model of asthma, suggesting that therapeutic approaches to enhance the production of Retnla or Retnla-like molecules could be valuable for preventing allergic lung inflammation.     

The role of IL-15 deficiency in the pathogenesis of virus-induced asthma exacerbations

Rhinovirus infections are the major cause of asthma exacerbations. We hypothesised that IL-15, a cytokine implicated in innate and acquired antiviral immunity, may be deficient in asthma and important in the pathogenesis of asthma exacerbations. We investigated regulation of IL-15 induction by rhinovirus in human macrophages in vitro, IL-15 levels in bronchoalveolar lavage (BAL) fluid and IL-15 induction by rhinovirus in BAL macrophages from asthmatic and control subjects, and related these to outcomes of infection in vivo. Rhinovirus induced IL-15 in macrophages was replication-, NF-κB- and α/β interferon-dependent. BAL macrophage IL-15 induction by rhinovirus was impaired in asthmatics and inversely related to lower respiratory symptom severity during experimental rhinovirus infection. IL-15 levels in BAL fluid were also decreased in asthmatics and inversely related with airway hyperresponsiveness and with virus load during in vivo rhinovirus infection. Deficient IL-15 production in asthma may be important in the pathogenesis of asthma exacerbations.     

Involvements of p38 MAPK and oxidative stress in the ozone-induced enhancement of AHR and pulmonary inflammation in an allergic asthma model

Background

Exposure to ambient ozone (O₃) increases the susceptivity to allergens and triggers exacerbations in patients with asthma. However, the detailed mechanisms of action for O₃ to trigger asthma exacerbations are still unclear.

Methods

An ovalbumin (OVA)-established asthmatic mouse model was selected to expose to filtered air (OVA-model) or 1.0 ppm O₃ (OVA-O₃ model) during the process of OVA challenge. Next, the possible involvements of p38 MAPK and oxidative stress in the ozone actions on the asthma exacerbations were investigated on the mice of OVA-O₃ model by treating them with SB239063 (a p38 MAPK inhibitor), and/or the α-tocopherol (antioxidant). Biological measurements were conducted including airway hyperresponsiveness (AHR), airway resistance (Raw), lung compliance (CL), inflammation in the airway lumen and lung parenchyma, the phosphorylation of p38 MAPK and heat shock protein (HSP) 27 in the tracheal tissues, and the malondialdehyde (MDA) content and the glutathione peroxidase (GSH-Px) activity in lung tissues.

Results

In OVA-allergic mice, O3 exposure deteriorated airway hyperresponsiveness (AHR), airway resistance (Raw), lung compliance (CL) and pulmonary inflammation, accompanied by the increased oxidative stress in lung tissues and promoted p38 MAPK and HSP27 phosphorylation in tracheal tissues. Administration of SB239063 (a p38 MAPK inhibitor) on OVA-O3 model exclusively mitigated the Raw, the CL, and the BAL IL-13 content, while α-tocopherol (antioxidant) differentially reduced the BAL number of eosinophils and macrophages, the content of BAL hyaluronan, the peribronchial inflammation, as well as the mRNA expression of TNF-α and IL-5 in the lung tissues of OVA-O3 model. Administration of these two chemical inhibitors similarly inhibited the AHR, the BAL IFN-γ and IL-6 production, the perivascular lung inflammation and the lung IL-17 mRNA expression of OVA-O3 model. Interestingly, the combined treatment of both compounds together synergistically inhibited neutrophil counts in the BALF and CXCL-1 gene expression in the lung.

Conclusions

O₃ exposure during the OVA challenge process promoted exacerbation in asthma. Both p38 MAPK and oxidative stress were found to play a critical role in this process and simultaneous inhibition of these two pathways significantly reduced the O₃-elicited detrimental effects on the asthma exacerbation.

     

Inhibition of neutrophil elastase attenuates airway hyperresponsiveness and inflammation in a mouse model of secondary allergen challenge: neutrophil elastase inhibition attenuates allergic airway responses

Background

Chronic asthma is often associated with neutrophilic infiltration in the airways. Neutrophils contain elastase, a potent secretagogue in the airways, nonetheless the role for neutrophil elastase as well as neutrophilic inflammation in allergen-induced airway responses is not well defined. In this study, we have investigated the impact of neutrophil elastase inhibition on the development of allergic airway inflammation and airway hyperresponsiveness (AHR) in previously sensitized and challenged mice.

Methods

BALB/c mice were sensitized and challenged (primary) with ovalbumin (OVA). Six weeks later, a single OVA aerosol (secondary challenge) was delivered and airway inflammation and airway responses were monitored 6 and 48 hrs later. An inhibitor of neutrophil elastase was administered prior to secondary challenge.

Results

Mice developed a two-phase airway inflammatory response after secondary allergen challenge, one neutrophilic at 6 hr and the other eosinophilic, at 48 hr. PAR-2 expression in the lung tissues was enhanced following secondary challenge, and that PAR-2 intracellular expression on peribronchial lymph node (PBLN) T cells was also increased following allergen challenge of sensitized mice. Inhibition of neutrophil elastase significantly attenuated AHR, goblet cell metaplasia, and inflammatory cell accumulation in the airways following secondary OVA challenge. Levels of IL-4, IL-5 and IL-13, and eotaxin in BAL fluid 6 hr after secondary allergen challenge were significantly suppressed by the treatment. At 48 hr, treatment with the neutrophil elastase inhibitor significantly reduced the levels of IL-13 and TGF-β1 in the BAL fluid. In parallel, in vitro IL-13 production was significantly inhibited in spleen cells from sensitized mice.

Conclusion

These data indicate that neutrophil elastase plays an important role in the development of allergic airway inflammation and hyperresponsiveness, and would suggest that the neutrophil elastase inhibitor reduced AHR to inhaled methacholine indicating the potential for its use as a modulator of the immune/inflammatory response in both the neutrophil- and eosinophil-dominant phases of the response to secondary allergen challenge.