Allergic Airway Remodeling Research Articles

M 3 muscarinic receptor antagonist bencycloquidium bromide attenuates allergic airway inflammation, hyperresponsiveness and remodeling in mice

M 3 muscarinic receptors are localized on inflammatory cells, airway smooth muscle, and submucosal glands, known to mediate bronchoconstriction, mucus secretion, and airway remodeling. It is hypothesized bencycloquidium bromide (BCQB), a novel M 3 receptor antagonist, might have potential effects on airway hyperresponsiveness, inflammation and airway remodeling in a murine model of asthma. Mice sensitized and challenged with ovalbumin developed airway inflammation. Bronchoalveolar lavage fluid was examined to determine the total and differential cell counts, and cytokine levels. Lung tissues were evaluated for cell infiltration, mucus hypersecretion, airway remodeling, and the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Inhalation administration of BCQB significantly not only reduced ovalbumin-induced airway hyperresponsiveness comparing to methacholine, and prevented the ovalbumin-induced increase in total cell counts and eosinophil counts. Reverse transcriptase polymerase chain reaction analysis of whole lung lysates revealed that BCQB markedly suppressed ovalbumin-induced mRNA expression of eotaxin, IL-5, IL-4 and MMP-9, and increased mRNA expression of IFN-γ and TIMP-1 in a dose-dependent manner. Substantial IFN-γ/IL-4 (Th1/Th2) levels were recovered in bronchoalveolar lavage fluid after BCQB treatment. In addition, histological studies showed that BCQB dramatically inhibited ovalbumin-induced lung tissue eosinophil infiltration, airway mucus production and collagen deposition in lung tissues. Results reported in current paper suggest that M 3 receptors antagonist may provide a novel therapeutic approach to treat airway inflammation, hyperresponsiveness and remodeling.

Putative association of SMAPIL polymorphisms with risk of aspirin intolerance in asthmatics

Background. Aspirin-intolerant asthma (AIA), as a clinical syndrome caused by aspirin, is characterized by lung inflammation and reversible bronchoconstriction. Recently, the altered trafficking and diminished airway reactivity have been implicated in allergic airway remodeling. The stromal membrane-associated protein 1-like (SMAP1L) exerts common and distinct functions in vesicle trafficking including endocytosis. The disturbance of pulmonary surfactant synthesis has been elucidated to be associated with asthma experimentally. Moreover, in alveolar type II (ATII) cells that synthesize pulmonary surfactant, alterations of clathrin-dependent endocytosis cause disturbance at the surfactant function, suggesting that SMAP1L, which directly interacts with clathrin, could be associated with asthma and related phenotypes. Objective. To verify our hypothesis that SMAP1L could play a role in the development of AIA, this study investigated associations between single-nucleotide polymorphisms (SNPs) of the SMAP1L gene and AIA. Methods. We conducted an association study between 19 SNPs of the SMAP1L gene and AIA in a total of 592 Korean subjects including 163 AIA and 429 aspirin-tolerant asthma (ATA) patients. Associations between polymorphisms of SMAP1L and AIA were analyzed with sex, smoking status, atopy, and body mass index as covariates. Results. Logistic analyses revealed that three common polymorphisms, rs2982510, rs2294752, and rs446738, were putatively associated with the increased susceptibility to AIA (p = .003, pcorr = .004, OR = 0.24, 95% CI = 0.09–0.62 for rs2982510 and rs2294752; p = .008, pcorr = .03, OR = 0.44, 95% CI = 0.24–0.80 for rs446738, in the recessive model). In addition, rs2982510 and rs2294752 were significantly associated with the fall of forced expiratory volume in 1 s (FEV1) by aspirin provocation (p = .001, pcorr = .04 in the recessive model for both SNPs). Conclusions. Our findings suggest that SMAP1L might be a susceptible gene to AIA, providing a new strategy for the control of aspirin intolerance.

Mepacrine treatment attenuates allergic airway remodeling segregated from airway inflammation in mice

Asthma is a chronic airway disease characterized by increased airway hyperresponsiveness, airway inflammation, and airway remodeling including collagen deposition in subepithelial regions. We have shown earlier that mepacrine has anti-inflammatory activity and decreased the features of airway remodeling in a subacute model of asthma, when administered during the inflammatory phase. But it was not clear whether the reduction of airway remodeling by mepacrine was a direct effect or indirectly related to the reduction in the airway inflammation. In this study, we determined the effect of mepacrine on airway remodeling and airway hyperresponsiveness (AHR) in a chronic model of asthma which showed the features of airway inflammation in the initial stage (inflammation predominant stage) and airway remodeling with mild airway inflammation in a later stage (remodeling predominant stage). Mepacrine was administered only in the later stage that more accurately simulates human asthma, where airway remodeling already exists at the time of diagnosis. The remodeling predominant stage was associated with high levels of Th2 cytokines like IL-4 and IL-13, increase in the levels of profibrotic mediators such as arginase and TGF-β, and increased collagen deposition. These were efficiently attenuated by mepacrine treatment and led to a significant reduction in AHR. Thus, we conclude from this study that mepacrine has direct effects on established airway remodeling independent of its anti-inflammatory effects.

Eosinophils Are Dispensable for Allergic Remodeling and Immunity in a Model of House Dust Mite–induced Airway Disease

Current thinking accredits eosinophils with preeminent contributions to allergic airway responses, including a major role in the development of airway remodeling, a process thought to significantly contribute to airway dysfunction. However, direct evidence in support of this notion is limited and often controversial. We elucidated the requirement for eosinophils in the generation of allergic sensitization, airway inflammation, and remodeling in a model involving chronic respiratory exposure to house dust mite (HDM). We used three methods to selectively eliminate eosinophils, a depleting antibody (anti-CCR3), and two strains of eosinophil-deficient mice (ΔdblGATA and the transgenic line PHIL). Anti-CCR3 treatment markedly reduced pulmonary eosinophilia (> 80%) over the course of HDM exposure but had no effect on the remaining inflammatory response, the extent of lung Th2 cells, or the development of remodeling-associated changes, including subepithelial collagen deposition and smooth muscle thickening. In addition, we observed that, despite the absence of eosinophils, HDM-exposed GATA mice mounted robust airway and lung inflammation and hyperresponsiveness and showed a remodeling response equivalent to that observed in wild-type mice. Moreover, these mice had similar serum HDM-specific IgE levels and Th2-associated splenocyte cytokine production as HDM-exposed wild-type control mice. Similar observations were made in PHIL eosinophil-deficient mice subjected to chronic HDM exposure, although slight decreases in airway mononuclear cells, but not lung Th2 cells, and remodeling were noted. Collectively, these data demonstrate that, at variance with the prevailing paradigm, eosinophils play negligible roles in the generation of HDM-induced allergic immunity and airway remodeling.

Galectin‐3 mediates chronic airway allergic inflammation and airway remodeling

The role played by Galectin‐3 (Gal‐3) in airway remodeling, a feature of chronic asthma that leads to airway dysfunction and poor clinical outcome in humans, was investigated in a murine model of asthma. Wild‐type (WT) and Gal‐3 knock‐out (KO) mice were subjected to repetitive allergen challenge with ovalbumin (OVA) up to 12 weeks and bronchoalveolar lavage fluid (BALF) and lung tissue collected after the last challenge were evaluated. Chronic OVA challenge induced Gal‐3 expression in the lungs of WT mice. Cell counts in BALF and lung immunohistology demonstrated that eosinophil infiltration in OVA‐challenged Gal‐3 KO mice is significantly reduced compared to WT mice. Also, eotaxin‐1, IL‐2, IL‐4 and TGF‐β expression in these mice was substantially lower than in OVA‐challenged WT mice. Decreased eosinophil recruitment in Gal‐3 KO mice was associated with diminished remodeling of the airways with significantly reduced mucus secretion, sub‐epithelial fibrosis, smooth muscle thickness, and peribronchial angiogenesis. Finally, leukocytes from Gal‐3 KO mice demonstrated decreased trafficking on endothelial adhesion molecules compared to WT cells. Overall, blockade of Gal‐3 in a chronic setting leads to diminished airway inflammation and remodeling potentially due to reduced trafficking of inflammatory cells to sites of inflammation. 1National Institutes of Health grants AI35796, U19‐AI70535, HL0793041.

Role of Insulin-like Growth Factor Binding Protein-3 in Allergic Airway Remodeling

The hallmarks of allergic asthma are airway inflammation, obstruction, and remodeling. Airway remodeling may lead to irreversible airflow obstruction with increased morbidity and mortality. Despite advances in the treatment of asthma, the mechanisms underlying airway remodeling are still poorly understood. We reported that insulin-like growth factor (IGF) binding proteins (IGFBPs) contribute to extracellular matrix deposition in idiopathic pulmonary fibrosis; however, their contribution to airway remodeling in asthma has not been established. We hypothesized that IGFBP-3 is overexpressed in asthma and contributes to airway remodeling. We evaluated levels of IGFBP-3 in tissues and bronchoalveolar lavage fluid from patients with asthma at baseline and 48 hours after allergen challenge, in reparative epithelium in an in vitro wounding assay, and in conditioned media from cytokine- and growth factor-stimulated primary epithelial cells. IGFBP-3 levels and distribution were evaluated by Western blot, ELISA, and immunofluorescence. IGFBP-3 is increased in vivo in the airway epithelium of patients with asthma compared with normal control subjects. The concentration of IGFBP-3 is increased in the bronchoalveolar lavage fluid of patients with asthma after allergen challenge, its levels are increased in reparative epithelium in an in vitro wounding assay and in the conditioned medium of primary airway epithelial cell cultures stimulated with IGF-I. Our results suggest that one mechanism of allergic airway remodeling is through the secretion of the profibrotic IGFBP-3 from IGF-I-stimulated airway epithelial cells during allergic inflammation.

Allergic rhinitis and airway remodeling

Allergic rhinitis and airway remodeling

Exercise Reduces Effects of Creatine on Lung

We recently demonstrated that creatine supplementation increased some features of lung allergic sensitization in mice. On the other hand, other studies have shown that aerobic exercise inhibited allergic airway inflammation and remodeling. We hypothesized that aerobic exercise may decrease the exacerbatory effects of the creatine supplementation in a murine model of asthma. Balb/c mice were divided into six groups: Control, Creatine (Cr), Low Intensity Exercise+Creatine (Low+Cr), Ovalbumin (OVA), Ovalbumin+Creatine (OVA+Cr) and Ovalbumin+Creatine+Low Intensity Exercise (OVA+Cr+Low). OVA-sensitized groups were sensitized with OVA intraperitoneal injections (days 0, 14, 28, and 42). Aerosol challenge (OVA 1%) and Cr treatment (0.5 g/kg/day) were initiated on Day 21 until Day 53. Low intensity exercise began on day 22 and was sustained until day 50. Low intensity exercise in the presence of creatine supplementation in sensitized mice resulted in a decreased number of eosinophils in BALF (p<0.001) and in the airways (p<0.001), and a decreased density of inflammatory cells positive to IL-4 (p<0.001) and IL-5 (p<0.001), airway collagen (p<0.001) and elastic fibers (p<0.001) content, airway smooth muscle thickness (p<0.001) and bronchoconstriction index (p<0.05) when compared with OVA+Cr group. These results suggest that aerobic exercise reduces the exacerbatory effects of creatine supplementation in chronically sensitized mice.

Allergic airway hyperresponsiveness, inflammation, and remodeling do not develop in phosphoinositide 3-kinase γ–deficient mice

Bronchial asthma is characterized by chronic airway inflammation caused by inflammatory cells. Phosphoinositide 3-kinases (PI3Ks) are known to play a prominent role in fundamental cellular responses of various inflammatory cells, including proliferation, differentiation, and cell migration. PI3Ks therefore are expected to have therapeutic potential for asthma. Although some investigations of the involvement between the pathogenesis of asthma and PI3K have been performed, it is unknown whether PI3Kgamma, a PI3K isoform, is involved in the pathogenesis of asthma. We investigated the role of PI3Kgamma in allergen-induced allergic airway inflammation, airway hyperresponsiveness (AHR), and airway remodeling with PI3Kgamma-deficient mice. After ovalbumin (OVA) sensitization, wild-type (WT) and PI3Kgamma-deficient mice were exposed to aerosolized OVA 3 days per week for 5 weeks. In OVA-sensitized and OVA-challenged (OVA/OVA) PI3Kgamma-deficient mice, levels of airway inflammation, AHR, and airway remodeling were significantly decreased compared with those in OVA/OVA WT mice. On the other hand, no significant differences were detected in serum OVA-specific IgE and IgG1 levels and CD4/CD8 balance in bronchoalveolar lavage fluid between OVA/OVA WT mice and OVA/OVA PI3Kgamma-deficient mice. To determine in which phase of allergic responses PI3Kgamma plays a role, we transferred splenocytes from OVA-sensitized WT or PI3Kgamma-deficient mice to naive mice of either genotype. Similar increased levels of eosinophils were induced in both WT recipient mice but not in both PI3Kgamma-deficient recipient mice. PI3Kgamma might be involved in allergic airway inflammation, AHR, and airway remodeling by regulating the challenge/effector phase of allergic responses.

Association of peroxisome proliferator-activated receptor-gamma gene polymorphisms with the development of asthma

The peroxisome proliferator-activated receptors (PPAR) are the nuclear hormone receptor superfamily of ligand-activated transcriptional factors. PPAR-gamma (PPARG) activation downregulates production of Th2 type cytokines and eosinophil function. Additionally, treatment with a synthetic PPARG ligand can reduce lung inflammation and IFN-gamma, IL-4, and IL-2 production in experimental allergic asthma. In patients with asthma, PPARG gene expression is known to be associated with the airway inflammatory and remodeling responses. Thus, genetic variants of PPARG may be associated with the development of asthma. We genotyped two single nucleotide polymorphisms on the PPARG gene, +34C>G (Pro12Ala) and +82466C>T (His449His), in Korean subjects (839 subjects with asthma and 449 normal controls). Association analysis using logistic regression analysis showed that +82466C>T and haplotypes 1(CC) and 2(CT) were associated with the development of asthma (p=0.01-0.04). The frequency of PPARG-ht2 was significantly lower in the patients with asthma compared to the normal controls in codominant and dominant models (p=0.01, p(corr)=0.03 and p=0.02, p(corr)=0.03, respectively). Conversely, the frequency of PPARG-ht1 was significantly higher in the patients with asthma compared to the normal controls in the codominant model [p=0.04, OR: 1.27 (1.01-1.6)]. In addition, the rare allele frequency of +82466C>T was significantly lower in patients with asthma in comparison to normal controls in the codominant model (OR: 0.78, p=0.04). Thus, polymorphism of the PPARG gene may be linked to an increased risk of asthma development.

Effect of Procaterol, a β2-adrenoceptor Agonist, on Proliferation of Airway Sensory C-fibers after Lipopolysaccharide Inhalation in Rats

RATIONALE: Lipopolysaccharide (LPS) leads to neutrophil recruitment to the lung and is associated with exacerbation of allergic airway inflammation and remodeling in humans and in animal models. We examined whether inhaled LPS could cause hyperinnervation of sensory C-fibers in the rat airway, likely resulting in enhancement of neurogenic airway inflammation. In addition, the preventive effect of procaterol, a β2-adrenoceptor agonist, on the increased neural mechanism after LPS inhalation was investigated.

Production of Amphiregulin by Human Eosinophils

RATIONALE: Eosinophils play important roles in the formation of allergic inflammation and airway remodeling. Amphiregulin (AREG) is a member of epidermal growth factor family and is known to induce proliferation of epithelial cells and fibroblasts, and to induce mucous production from bronchial epithelial cells. In the present study we determined AREG production by human eosinophils.

TGF-&amp;#946;, Eosinophils and IL-13 in Allergic Airway Remodeling: A Critical Appraisal with Therapeutic Considerations

Airway remodeling is a characteristic feature of allergic asthma that is now thought to contribute to airway dysfunction and, ultimately, to clinical symptoms. A prevalent hypothesis holds that eosinophil-derived transforming growth factor-beta (TGF-beta) is a predominant underlying mechanism driving the development of remodeling and thus, represent promising targets for therapeutic intervention. This notion is supported by in vivo evidence from loss of function experiments conducted in animal models employing the surrogate allergen ovalbumin (OVA), and by indirect evidence from studies in human asthmatics. However, it is important to note that various studies in OVA systems have reported disconnects between eosinophils, TGF-beta and allergic remodeling. Moreover, recent investigations in a mouse model induced by respiratory exposure to a house dust mite extract have shown that remodeling can develop independently of TGF-beta. These findings challenge the above hypothesis and suggest that the mechanisms governing remodeling may be context specific. In addition to TGF-beta and eosinophils, several other factors have been implicated in the development of airway remodeling. Among these, interleukin (IL)-13 may be of particular importance given its role in type-2 immunity and in the tissue repair/fibrotic response. This review will appraise the evidence pertaining to the roles of TGF-beta, eosinophils and IL-13 in allergic remodeling, and will suggest that identifying robust targets for therapeutic intervention might benefit from a reconsideration of our approach to understanding remodeling.

Prior SO2 exposure promotes airway inflammation and subepithelial fibrosis following repeated ovalbumin challenge

Exposure to allergens or air pollutants often leads to asthma exacerbations associated with aggravation of airway inflammation. Although, repeated allergen challenge often induces chronic allergic airway inflammation (CAAI) and airway remodelling, yet, the effects of brief exposure to air pollutants such as SO(2) on development of CAAI and airway remodelling remain to be clarified. The aim of the experiment was to investigate the effects of acute neutrophilic airway inflammation induced by brief exposure to SO(2) on development of CAAI and subepithelial fibrosis (SEF) in a murine model of asthma. Acute airway inflammation was induced by brief exposure to 50 p.p.m. SO(2) (1 h/d, 3 days). CAAI and SEF in BALB/c mice were induced by repeated challenge with ovalbumin (OVA) for 5 or 9 weeks with or without prior exposure to SO(2). Bronchoalveolar lavage fluid (BALF) eosinophilia as index of CAAI, BALF endothelin-1 (ET-1) and TGF-beta1 levels, morphometric evaluation of fibrotic area beneath subbasement membrane and lung hydroxyproline content (Hyp) as indexes of SEF were monitored. Exposure to SO(2) led to acute neutrophilic inflammation and epithelial sloughing with profound elevation of BALF ET-1. Repeated OVA challenge resulted in CAAI and SEF along with elevation of Hyp, increase of fibrotic area beneath subbasement membrane and elevation of BALF TGF-beta1. Preceding SO(2) exposure exaggerated BALF eosinophilia, facilitated and enhanced SEF with more significant elevation of BALF ET-1 and TGF-beta1 levels compared with OVA-challenged mice without prior exposure to SO(2). The increase of Hyp was positively correlated with elevation of BALF TGF-beta1 during CAAI (r=0.842, P<0.01). This data demonstrated that SEF developed in parallel with severity and time course of CAAI following repeated OVA challenge. SO(2)-induced acute epithelial injury and neutrophilic inflammation could enhance CAAI and promote SEF, probably through overexpression of ET-1 and TGF-beta1.

The epidermal growth factor receptor mediates allergic airway remodelling in the rat

The chronicity of bronchial asthma is attributed to persistent airway inflammation and to a variety of structural changes, or remodelling, that includes smooth muscle and goblet cell hyperplasia. To investigate the mechanisms of airway remodelling, the current authors used an established allergen (ovalbumin; OVA)-driven rodent model (the Brown Norway rat). Brown Norway rats were sensitised to OVA and challenged three times at 5-day intervals to evoke airway remodelling. The effects of an epidermal growth factor (EGF) receptor inhibitor, AG1478, and a cysteinyl leukotriene-1 receptor antagonist, montelukast, on epithelial and airway smooth muscle (ASM) cell proliferation in vivo in response to repeated OVA challenge were tested. Three challenges with leukotriene (LT)D(4) were given, to examine their effects on remodelling with and without AG1478 pretreatment. OVA challenges caused ASM hyperplasia, with an increase in mass, epithelial cell proliferation and goblet cell proliferation. AG1478 prevented the changes, as did montelukast. Multiple OVA challenges increased heparin-binding EGF-like growth factor but not EGF expression by airway epithelium. LTD(4) reproduced the changes in remodelling induced by OVA and this was blocked by AG1478. Allergen-induced airway epithelial and airway smooth muscle remodelling is mediated by cysteinyl leukotrienes via the cysteinyl leukotriene-1 receptor with downstream effects on the epidermal growth factor receptor axis.

Mice Lacking 12/15-Lipoxygenase Have Attenuated Airway Allergic Inflammation and Remodeling

Arachidonate 15-lipoxygenase (LO)-1 has been implicated in allergic inflammation and asthma. The overall effect of 15-LO in allergic inflammation in vivo is, however, unclear. This study investigates systemic allergen sensitization and local allergic airway inflammation and remodeling in mice lacking the murine 12/15-LO, the ortholog to human 15-LO-1. Upon systemic sensitization with intraperitoneal ovalbumin, 12/15-LO-/- mice produced elevated levels of allergen-specific immunoglobulin E compared with wild-type (Wt) controls. However, when challenged with repeated aerosolized allergen, sensitized 12/15-LO-/- mice had an impaired development of airway allergic inflammation compared with Wt controls, as indicated by reduced bronchoalveolar lavage fluid leukocytes (eosinophils, lymphocytes, macrophages) and Th2 cytokines (IL-4, IL-5, IL-13), as well as tissue eosinophils. Allergen-induced airway epithelial proliferation was also significantly attenuated in 12/15-LO-/- mice, whereas goblet cell hyperplasia was unaffected. However, 12/15-LO-/- mice had significantly reduced luminal mucus secretions compared with Wt controls. The repeated allergen challenges resulted in a dramatic increase of alpha-smooth muscle actin-positive alveolar cells in the peripheral airways, a phenomenon that was significantly less developed in 12/15-LO-/- mice. In conclusion, our data suggest that 12/15-LO-/- mice, although having a fully developed systemic sensitization, did not establish a fully developed allergic airway inflammation and associated manifestations of central and peripheral airway remodeling. These data suggest that 12/15-LO-derived metabolites play an important pathophysiologic role in allergen-induced inflammation and remodeling. Hence, pharmacologic targeting of the human 15-LO-1 may represent an attractive therapeutic strategy to control inflammation and remodeling in asthma.

Leukotrienes and Antileukotriene Therapy in Allergic Rhinitis

Leukotrienes (LT) are the inflammatory mediators that have an important role in inflammatory diseases such as allergic rhinitis and asthma. The leukotrienes that contain cystein, cysteinyl leukotrienes (Cys LTs), are LTC4, LTD4 and LTE4. They are synthesized from arachidonic acid by 5-lipooxygenase pathway and eosinophils and mast cells can produce large amounts of Cys LTs from an endogenous pool of arachidonic acid. Cys LTs exert their effects by binding to their receptors namely Cys LT1 and Cys LT2 receptors. They contribute the allergic inflammation by promoting inflammatory cell recruitment and activation, enhancing production of certain cytokines that play a role in allergic inflammation, promoting fibrosis and airway remodeling in bronchi, inducing vascular leakage and vasodilatation leading to mucosal edema especially in nasal mucosa, stimulating mucus secretion by goblet cells and decreasing mucociliary clearance. The main symptom of allergic rhinitis related to Cys LTs seems to be nasal congestion. In allergic rhinitis, monotherapy with a Cys LT1 receptor anatagonist is better than placebo and equivalent to oral antihistamine therapy. Combination of LT1 receptor antagonists and oral antihistamines are superior to antihistamines alone. Intranasal corticosteroids alone are more effective than both LT1 receptor antagonists alone and the combination of LT1 eceptor antagonists with antihistamines. Clarification of the actions of Cys LTs mediated by Cys LT2 receptor and other possible receptors and further development of antagonists against those receptors might increase the efficacy of antilekotriene therapy on the symptoms of allergic rhinitis.

Transforming Growth Factor-β Regulates House Dust Mite–induced Allergic Airway Inflammation but Not Airway Remodeling

It is now believed that both chronic airway inflammation and remodeling contribute significantly to airway dysfunction and clinical symptoms in allergic asthma. Transforming growth factor (TGF)-beta is a powerful regulator of both the tissue repair and inflammatory responses, and numerous experimental and clinical studies suggest that it may play an integral role in the pathogenesis of asthma. We investigated the role of TGF-beta in the regulation of allergic airway inflammation and remodeling using a mouse model of house dust mite (HDM)-induced chronic allergic airway disease. We have previously shown that intranasal administration of an HDM extract (5 d/wk for 5 wk) elicits robust Th2-polarized airway inflammation and remodeling that is associated with increased airway hyperreactivity. Here, Balb/c mice were similarly exposed to HDM and concurrently treated with a pan-specific TGF-beta neutralizing antibody. We observed that anti-TGF-beta treatment in the context of either continuous or intermittent HDM exposure had no effect on the development of HDM-induced airway remodeling. To further confirm these findings, we also subjected SMAD3 knockout mice to 5 weeks of HDM and observed that knockout mice developed airway remodeling to the same extent as HDM-exposed littermate controls. Notably, TGF-beta neutralization exacerbated the eosinophilic infiltrate and led to increased airway hyperreactivity. Collectively, these data suggest that TGF-beta regulates HDM-induced chronic airway inflammation but not remodeling, and furthermore, caution against the use of therapeutic strategies aimed at interfering with TGF-beta activity in the treatment of this disease.

Levocetirizine and cytokine production and apoptosis of human eosinophils

Antihistamines are a common therapy for allergic symptoms. Eosinophilic infiltration is considered a hallmark of allergic inflammation. Eosinophils are capable of mediating airway mucosal damage by producing various inflammatory mediators including cytokines, chemokines, basic granule proteins, lipid mediators, and growth factors. Reduced eosinophil apoptosis is thought to be an important feature in the formation of eosinophilia in allergic diseases such as allergic rhinitis, atopic eczema, and asthma. The aim of this study was to investigate the effects of levocetirizine on the production of inflammatory mediators by eosinophils and on eosinophil apoptosis. The production of cytokines and other inflammatory mediators by human eosinophils was measured by a cytokine antibody array. Apoptosis of isolated human eosinophils was assessed by measuring the relative DNA content of propidium iodide-stained cells. Of the 40 cytokines studied, levocetirizine (1 microM) was found to enhance the release of tissue inhibitor of metalloproteinases 1 and 4, matrix metalloproteinase 9, and heparin-binding epidermal growth factor and to attenuate the production of interleukins (IL)-1 beta and IL-7 and stem cell factor in lipopolysaccharide-stimulated human eosinophils. Levocetirizine did not alter constitutive eosinophil apoptosis or eosinophil survival induced by IL-5, granulocyte/macrophage colony-stimulating factor, tumor necrosis factor alpha, or salbutamol. The results of this study suggest that levocetirizine modulates the profile of inflammatory mediators including cytokines, growth factors, proteinases, and antiproteinases produced by eosinophils, which may be of importance in allergic inflammation and airway remodeling. However, eosinophil longevity seems not to be modulated by levocetirizine.

Complete inhibition of allergic airway inflammation and remodelling in quadruple IL‐4/5/9/13−/− mice

T-helper type 2 (Th2)-derived cytokines such as IL-4, IL-5, IL-9 and IL-13 play an important role in the synthesis of IgE and in the promotion of allergic eosinophilic inflammation and airway wall remodelling. We determined the importance of IL-13 alone, and of the four Th2 cytokines together, by studying mice in which either IL-13 alone or the Th2 cytokine cluster was genetically disrupted. The knock-out mice and their BALB/c wild-type (wt) counterparts were sensitized and repeatedly exposed to ovalbumin (OVA) aerosol. Bronchial responsiveness measured as the concentration of acetylcholine aerosol needed to increase baseline lung resistance by 100% (PC100) was decreased in IL-13-/-, but increased in IL-4/5/9/13-/- mice. Chronic allergen exposure resulted in airway hyperresponsiveness (AHR) in wt mice but not in both genetically modified mice. After allergen exposure, eosinophil counts in bronchoalveolar lavage fluid and in airways mucosa, and goblet cell numbers were not increased in IL-4/5/9/13-/- mice, and were only attenuated in IL-13-/- mice. Airway smooth muscle (ASM) hyperplasia after allergen exposure was prevented in both IL-13-/- and IL-4/5/9/13-/- mice to an equal extent. Similarly, the rise in total or OVA-specific serum IgE levels was totally inhibited. IL-13 is mainly responsible for AHR, ASM hyperplasia and increases in IgE, while IL-4, -5 and -9 may contribute to goblet cell hyperplasia and eosinophilic inflammation induced by chronic allergen exposure in a murine model. Both redundancy or complementariness of Th2 cytokines can occur in vivo, according to specific aspects of the allergic response.