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The role of tumor necrosis factor-α (TNF-α) in contributing to allergen induced airway remodeling in asthma is unknown. In this study we have utilized a mouse model of chronic OVA allergen induced airway remodeling to determine whether TNF p55/p75 receptor deficient mice (abbreviated TNF-R KO) had reduced levels of airway remodeling. Chronic OVA challenged WT mice had significantly increased levels of lung eosinophilic inflammation as well as features of airway remodeling including increased peribronchial fibrosis, thickness of the peribronchial smooth muscle layer, mucus expression, and deposition of extracellular matrix proteins. In contrast, TNF-R KO mice had significantly reduced levels of major basic protein positive peribronchial eosinophils and significantly reduced peribronchial fibrosis assessed by quantitating the area of peribronchial trichrome staining and total lung collagen. In addition, TNF-R KO mice had significantly reduced thickness of the peribronchial smooth muscle layer, area of peribronchial α-smooth muscle actin immunostaining, and levels of the extracellular matrix protein fibronectin. There was a non-significant trend for reduced mucus expression in TNF-R KO mice. Levels of peribronchial cells immunostaining positive for TGF-β1 were significantly reduced in TNF-R KO mice suggesting that reduced levels of TGF-β1 expression in TNF-R KO mice may contribute to reduced airway remodeling. Overall, this study suggests an important role for TNF-α in contributing to many features of allergen induced airway remodeling including changes in levels of peribronchial smooth muscle, subepithelial fibrosis, and deposition of extracellular matrix., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: Basic fibroblast growth factor (bFGF) is a cytokine that is mitogenic for fibroblasts and smooth muscle and may play a role in airway remodeling in asthma. We have used a mouse model of chronic ovalbumin (OVA) allergen-induced airway remodeling to determine whether bFGF and fibroblast growth factor receptor-1 are expressed and regulated by corticosteroids in the airway, as well as to determine whether bFGF mediates expression of another proremodeling cytokine, transforming growth factor (TGF)-β1., Methods: The airway levels and localization of bFGF, FGF receptor-1 and TGF-β1 were determined by ELISA, immunohistology and image analysis in the remodeled airways of chronic OVA-challenged mice treated with either corticosteroids or diluent. In vitro cultures of bone narrow-derived macrophages were used to determine whether bFGF induced TGF-β1 expression., Results: Mice chronically challenged with OVA developed significant airway remodeling that was associated with significantly increased levels of bFGF and TGF-β1. Immunohistochemistry demonstrated significantly increased bFGF and FGF receptor-1 expression by peri- bronchial F4/80+ cells. Double-label immunofluorescence microscopy studies demonstrated that peribronchial macrophages coexpressed bFGF and TGF-β1. In vitro studies demonstrated that incubation of bone marrow-derived macrophages with bFGF induced expression of TGF-β1. Mice treated with corticosteroids and subjected to chronic OVA challenge had significantly reduced levels of bFGF, FGF receptor-1, peribronchial TGF-β1+ cells and airway remodeling., Conclusions: Overall, this study demonstrates that allergen challenge stimulates peribronchial macrophages to coexpress bFGF and TGF-β1 and that bFGF may potentiate macrophage release of TGF-β1 through autocrine and/or paracrine pathways., (Copyright © 2010 S. Karger AG, Basel.)

As genetically engineered mutant mice deficient in single genes are usually generated on a C57BL/6 background, to study mast cell trafficking in mutant mice, we initially investigated whether mast cells accumulated in bronchi in C57BL/6 mice challenged with OVA allergen acutely or chronically for 1 to 3 months. The total number of bronchial mast cells were quantitated using toluidine blue staining in airways of different sizes, i.e. , small (<90 microm), medium (90-155 microm), or large (>150 microm) airways. Non-OVA challenged and acute OVA challenged mice (C57BL/6 and BALB/c) had no detectable bronchial mast cells. Chronic OVA challenge in BALB/c mice for 1 or 3 months induced a significant increase in the number of bronchial mast cells in small-, medium-, and large-sized airways but minimal change in the number of bronchial mast cells in C57BL/6 mice. Both BALB/c and C57BL/6 mice developed significant lung eosinophilia following acute or chronic OVA challenge. Studies of IL-9-deficient mice on a BALB/c background demonstrated a significant increase in the number of bronchial mast cells in IL-9-deficient mice suggesting that IL-9 was not required for the bronchial accumulation of mast cells. Overall, these studies demonstrate that the chronic OVA challenge protocol we have utilized in BALB/c mice provides a model to study the mechanism of bronchial mast cell accumulation and that bronchial mast cell accumulation in chronic OVA challenged mice is independent of IL-9 in this model.

In this study, we have examined the role of phosphoinositide 3 kinase gamma (PI3Kgamma), a class Ib PI3K, in contributing to airway remodeling utilizing PI3Kgamma-deficient mice exposed to chronic allergen challenge. Wild-type (WT) mice sensitized to ovalbumin (OVA) and chronically challenged with OVA for 1 mo developed significantly increased levels of eosinophilic inflammation and airway remodeling. In contrast, PI3Kgamma-deficient mice challenged with OVA had significantly reduced numbers of bronchoalveolar lavage and peribronchial eosinophils compared with WT mice. There was no significant difference in the number of bone marrow or circulating peripheral blood eosinophils when comparing WT mice and PI3Kgamma-deficient mice, suggesting that trafficking of eosinophils into the lung was reduced in PI3Kgamma-deficient mice. PI3Kgamma-deficient and WT mice had similar levels of IL-5 and eotaxin-1. The reduced eosinophil recruitment to the airway in PI3Kgamma-deficient mice challenged with OVA was associated with significantly reduced numbers of TGF-beta1+ peribronchial cells, reduced numbers of pSmad 2/3+ airway epithelial cells, and pSmad 2/3+ peribronchial cells, as well as significantly reduced levels of peribronchial fibrosis (quantitated by trichrome staining and image analysis as well as by lung collagen levels). In addition, the area of peribronchial alpha-smooth muscle staining was significantly reduced in PI3Kgamma-deficient compared with WT mice. Overall, this study demonstrates an important role for PI3Kgamma in mediating allergen-induced eosinophilic airway inflammation and airway remodeling, suggesting that PI3Kgamma may be a novel therapeutic target in asthma.

Intracellular signaling pathways that converge on Smad 3 are used by both TGF-beta and activin A, key cytokines implicated in the process of fibrogenesis. To determine the role of Smad 3 in allergen-induced airway remodeling, Smad 3-deficient and wild-type (WT) mice were sensitized to OVA and challenged by repetitive administration of OVA for 1 mo. Increased levels of activin A and increased numbers of peribronchial TGF-beta1(+) cells were detected in WT and Smad 3-deficient mice following repetitive OVA challenge. Smad 3-deficient mice challenged with OVA had significantly less peribronchial fibrosis (total lung collagen content and trichrome staining), reduced thickness of the peribronchial smooth muscle layer, and reduced epithelial mucus production compared with WT mice. As TGF-beta and Smad 3 signaling are hypothesized to mediate differentiation of fibroblasts to myofibroblasts in vivo, we determined the number of peribronchial myofibroblasts (Col-1(+) and alpha-smooth muscle actin(+)) as assessed by double-label immunofluorescence microscopy. Although the number of peribronchial myofibroblasts increased significantly in WT mice following OVA challenge, there was a significant reduction in the number of peribronchial myofibroblasts in OVA-challenged Smad 3-deficient mice. There was no difference in levels of eosinophilic airway inflammation or airway responsiveness in Smad 3-deficient compared with WT mice. These results suggest that Smad 3 signaling is required for allergen-induced airway remodeling, as well as allergen-induced accumulation of myofibroblasts in the airway. However, Smad 3 signaling does not contribute significantly to airway responsiveness.

Environmental tobacco smoke (ETS) can increase asthma symptoms and the frequency of asthma attacks. However, the contribution of ETS to airway remodeling in asthma is at present unknown. In this study, we have used a mouse model of allergen-induced airway remodeling to determine whether the combination of chronic exposure to ETS and chronic exposure to OVA allergen induces greater levels of airway remodeling than exposure to either chronic ETS or chronic OVA allergen alone. Mice exposed to chronic ETS alone did not develop significant eosinophilic airway inflammation, airway remodeling, or increased airway hyperreactivity to methacholine. In contrast, mice exposed to chronic OVA allergen had significantly increased levels of peribronchial fibrosis, increased thickening of the smooth muscle layer, increased mucus, and increased airway hyperreactivity which was significantly enhanced by coexposure to the combination of chronic ETS and chronic OVA allergen. Mice coexposed to chronic ETS and chronic OVA allergen had significantly increased levels of eotaxin-1 expression in airway epithelium which was associated with increased numbers of peribronchial eosinophils, as well as increased numbers of peribronchial cells expressing TGF-beta1. These studies suggest that chronic coexposure to ETS significantly increases levels of allergen-induced airway remodeling (in particular smooth muscle thickness) and airway responsiveness by up-regulating expression of chemokines such as eotaxin-1 in airway epithelium with resultant recruitment of cells expressing TGF-beta1 to the airway and enhanced airway remodeling.

Matrix metalloproteinases (MMPs) are a family of extracellular proteases that are responsible for the degradation of the extracellular matrix during tissue remodeling. We have used a mouse model of allergen-induced airway remodeling to determine whether MMP-9 plays a role in airway remodeling. MMP-9-deficient and wild-type (WT) mice were repetitively challenged intranasally with ovalbumin (OVA) antigen to develop features of airway remodeling including peribronchial fibrosis and increased thickness of the peribronchial smooth muscle layer. OVA-challenged MMP-9-deficient mice had less peribronchial fibrosis and total lung collagen compared with OVA-challenged WT mice. There was no reduction in mucus expression, smooth muscle thickness, or airway responsiveness in OVA-challenged MMP-9-deficient compared with OVA-challenged WT mice. OVA-challenged MMP-9-deficient mice had reduced levels of bronchoalveolar lavage (BAL) regulated on activation, normal T cell expressed, and secreted (RANTES), as well as reduced numbers of BAL and peribronchial eosinophils compared with OVA-challenged WT mice. There were no significant difference in levels of BAL eotaxin, thymus- and activation-regulated chemokine (TARC), or macrophage-derived chemokine (MDC) in OVA-challenged WT compared with MMP-9-deficient mice. Overall, this study demonstrates that MMP-9 may play a role in mediating selected aspects of allergen-induced airway remodeling (i.e., modest reduction in levels of peribronchial fibrosis) but does not play a significant role in mucus expression, smooth muscle thickness, or airway responsiveness.

In response to inflammation or injury, airway epithelial cells express inducible genes that may contribute to allergen-induced airway remodeling. To determine the contribution of epithelial cell NF-kappaB activation to the remodeling response, we generated CC10-Cre(tg)/Ikkbeta(delta/delta) mice in which NF-kappaB signaling through IkappaB kinase beta (IKKbeta) is selectively ablated in the airway epithelium by conditional Cre-recombinase expression from the Clara cell (CC10) promoter. Repetitive ovalbumin challenge of mice deficient in airway epithelial IKKbeta prevented nuclear translocation of the RelA NF-kappaB subunit only in airway epithelial cells, resulting in significantly lower peribronchial fibrosis in CC10-Cre(tg)/Ikkbeta(delta/delta) mice compared with littermate controls as assessed by peribronchial trichrome staining and total lung collagen content. Levels of airway mucus, airway eosinophils, and peribronchial CD4+ cells in ovalbumin-challenged mice were also reduced significantly upon airway epithelial Ikkbeta ablation. The diminished inflammatory response was associated with reduced expression of NF-kappaB-regulated chemokines, including eotaxin-1 and thymus- and activation-regulated chemokine, which attract eosinophils and Th2 cells, respectively, into the airway. The number of peribronchial cells expressing TGF-beta1, as well as TGF-beta1 amounts in bronchoalveolar lavage, were also significantly reduced in mice deficient in airway epithelium IKKbeta. Overall, these studies show an important role for NF-kappaB regulated genes in airway epithelium in allergen-induced airway remodeling, including peribronchial fibrosis and mucus production.

To determine whether immunostimulatory sequences of DNA (ISS) can reverse established airway remodeling, mice that had developed airway remodeling following 3 mo of repetitive OVA challenges, were treated with ISS for 1-3 mo. Systemic administration of ISS to mice that had already developed established airway remodeling significantly reduced the degree of airway collagen deposition (assessed by lung collagen content, peribronchial trichrome staining, and immunostaining with anticollagen type III and type V Abs). ISS reduced bronchoalveolar lavage and lung levels of TGF-beta1 and reduced the number of TGF-beta1-positive eosinophils and TGF-beta1-positive mononuclear cells recruited to the airway. In vitro studies demonstrated that ISS inhibited TGF-beta1 expression by macrophages (RAW 264.7 cell line and bone marrow-derived macrophages). In addition, ISS significantly reduces lung levels of expression of the chemokine thymus- and activation-regulated chemokine, as well as the number of peribronchial CD4(+) lymphocytes that express Th2 cytokines that promote peribronchial fibrosis. Overall, these studies demonstrate that ISS can reverse features of airway collagen deposition by reducing levels of lung TGF-beta1, as well as by reducing levels of the chemokine thymus- and activation-regulated chemokine and the numbers of peribronchial CD4(+) lymphocytes that drive the ongoing Th2 immune response.

Few peribronchial mast cells are noted either in the lungs of naive mice or in the lungs of OVA-sensitized mice challenged acutely with OVA by inhalation. In this study, we demonstrate that OVA-sensitized mice exposed to repetitive OVA inhalation for 1-6 mo have a significant accumulation of peribronchial mast cells. This accumulation of peribronchial mast cells is associated with increased expression of the Th2 cell-derived mast cell growth factors, including IL-4 and IL-9, but not with the non-Th2 cell-derived mast cell growth factor, stem cell factor. Pretreating mice with immunostimulatory sequences (ISS) of DNA containing a CpG motif significantly inhibited the accumulation of peribronchial mast cells and the expression of IL-4 and IL-9. To determine whether mast cells express Toll-like receptor-9 (TLR-9; the receptor for ISS), TLR-9 expression by mouse bone marrow-derived mast cells (MBMMCs) was assessed by RT-PCR. MBMMCs strongly expressed TLR-9 and bound rhodamine-labeled ISS. However, incubation of MBMMCs with ISS in vitro neither inhibited MBMMC proliferation nor inhibited Ag/IgE-mediated MBMMC degranulation, but they did induce IL-6. Overall these studies demonstrate that mice exposed to repetitive OVA challenge, but not acute OVA challenge, have an accumulation of peribronchial mast cells and express increased levels of mast cell growth factors in the lung. Although mast cells express TLR-9, ISS does not directly inhibit mast cell proliferation in vitro, suggesting that ISS inhibits accumulation of peribronchial mast cells in vivo by indirect mechanism(s), which include inhibiting the lung expression of Th2 cell-derived mast cell growth factors.

Orosomucoid-like (ORMDL)3 has been strongly linked with asthma in genetic association studies. Because allergen challenge induces lung ORMDL3 expression in wild-type mice, we have generated human ORMDL3 zona pellucida 3 Cre (hORMDL3(zp3-Cre)) mice that overexpress human ORMDL3 universally to investigate the role of ORMDL3 in regulating airway inflammation and remodeling. These hORMDL3(zp3-Cre) mice have significantly increased levels of airway remodeling, including increased airway smooth muscle, subepithelial fibrosis, and mucus. hORMDL3(zp3-Cre) mice had spontaneously increased airway responsiveness to methacholine compared to wild-type mice. This increased airway remodeling was associated with selective activation of the unfolded protein response pathway transcription factor ATF6 (but not Ire1 or PERK). The ATF6 target gene SERCA2b, implicated in airway remodeling in asthma, was strongly induced in the lungs of hORMDL3(zp3-Cre) mice. Additionally, increased levels of expression of genes associated with airway remodeling (TGF-β1, ADAM8) were detected in airway epithelium of these mice. Increased levels of airway remodeling preceded increased levels of airway inflammation in hORMDL3(zp3-Cre) mice. hORMDL3(zp3-Cre) mice had increased levels of IgE, with no change in levels of IgG, IgM, and IgA. These studies provide evidence that ORMDL3 plays an important role in vivo in airway remodeling potentially through ATF6 target genes such as SERCA2b and/or through ATF6-independent genes (TGF-β1, ADAM8).

Studies of AMCase inhibition in mouse models of lung eosinophilic inflammation have produced conflicting results with some studies demonstrating inhibition of eosinophilic inflammation and others not. No studies have investigated the role of AMCase inhibition in eosinophilic esophagitis (EoE). We have used a mouse model of egg (OVA) induced EoE to determine whether pharmacologic inhibition of AMCase with allosamidin reduced eosinophilic inflammation and remodeling in the esophagus in EoE. Administration of intra-esophageal OVA for 6weeks to BALB/c mice induced increased levels of esophageal eosinophils, mast cells, and features of esophageal remodeling (fibrosis, basal zone hyperplasia, deposition of the extracellular matrix protein fibronectin). Administration of intraperitoneal (ip) allosamidin to BALB/c mice significantly inhibited AMCase enzymatic activity in the esophagus. Pharmacologic inhibition of AMCase with ip allosamidin inhibited both OVA induced increases in esophageal eosinophilic inflammation and OVA induced esophageal remodeling (fibrosis, epithelial basal zone hyperplasia, extracellular matrix deposition of fibronectin). This inhibition of eosinophilic inflammation in the esophagus by ip allosamidin was associated with reduced eotaxin-1 expression in the esophagus. Oral allosamidin inhibited eosinophilic inflammation in the epithelium but did not inhibit esophageal remodeling. These studies suggest that pharmacologic inhibition of AMCase results in inhibition of eosinophilic inflammation and remodeling in the esophagus in a mouse model of egg induced EoE partially through effects in the esophagus on reducing chemokines (i.e. eotaxin-1) implicated in the pathogenesis of EoE.

In this study, we used cre-lox techniques to generate mice selectively deficient in ORMDL3 in airway epithelium (Ormdl3Δ2-3/Δ2-3/CC10) to simulate an inhaled therapy that effectively inhibited ORMDL3 expression in the airway. In contrast to the anticipated reduction in airway hyperresponsiveness (AHR), OVA allergen-challenged Ormdl3Δ2-3/Δ2-3/CC10 mice had a significant increase in AHR compared with wild-type mice. Levels of airway inflammation, mucus, fibrosis, and airway smooth muscle were no different in Ormdl3Δ2-3/Δ2-3/CC10 and wild-type mice. However, levels of sphingosine-1-phosphate (S1P) were significantly increased in Ormdl3Δ2-3/Δ2-3/CC10 mice as well as in airway epithelial cells in which ORMDL3 was inhibited with small interfering RNA. Incubation of S1P with airway smooth muscle cells significantly increased contractility. Overall, Ormdl3Δ2-3/Δ2-3/CC10 mice exhibit increased allergen-induced AHR independent of inflammation and associated with increased S1P generation. These studies raise concerns for inhaled therapies that selectively and effectively inhibit ORMDL3 in airway epithelium in asthma. [ABSTRACT FROM AUTHOR]

Chronic asthma is associated with airway remodeling and decline in lung function. In this article, we show that follistatin-like 1 (Fstl1), a mediator not previously associated with asthma, is highly expressed by macrophages in the lungs of humans with severe asthma. Chronic allergen-challenged Lys-Cretg /Fstl1Δ/Δ mice in whom Fstll is inactivated in macrophages/myeloid cells had significantly reduced airway remodeling and reduced levels of oncostatin M (OSM), a cytokine previously not known to be regulated by Fstl1. The importance of the Fstl1 induction of OSM to airway remodeling was demonstrated in murine studies in which administration of Fstl1 induced airway remodeling and increased OSM, whereas administration of an anti-OSM Ab blocked the effect of Fstl1 on inducing airway remodeling, eosinophilic airway inflammation, and airway hyperresponsiveness, all cardinal features of asthma. Overall, these studies demonstrate that the Fstl1/OSM pathway may be a novel pathway to inhibit airway remodeling in severe human asthma. [ABSTRACT FROM AUTHOR]

Background: As passive environmental tobacco smoke (ETS) exposure in nonsmokers can increase both asthma symptoms and the frequency of asthma exacerbations, we utilized a mouse model, in which ovalbumin (OVA) + ETS induce significantly increased levels of eosinophilic airway inflammation and remodeling compared to either stimulus alone, to determine whether a Toll-like receptor-9 (TLR-9) agonist could reduce levels of airway inflammation, airway remodeling and airway hyperreactivity (AHR). Methods: Mice treated with or without a TLR-9 agonist were sensitized to OVA and challenged with OVA + ETS for 1 month. AHR to methacholine was assessed in intubated and ventilated mice. Lung Th2 cytokines and TGF-β1 were measured by ELISA. Lungs were processed for histology and immunohistology to quantify eosinophils, mucus, peribronchial fibrosis and smooth muscle changes using image analysis. Results: Administration of a TLR-9 agonist to mice coexposed to chronic ETS and chronic OVA allergen significantly reduced levels of eosinophilic airway inflammation, mucus production, peribronchial fibrosis, the thickness of the peribronchial smooth muscle layer, and AHR. The reduced airway remodeling in mice treated with the TLR-9 agonist was associated with significantly reduced numbers of peribronchial MBP+ and peribronchial TGF-β1+ cells, and with significantly reduced levels of lung Th2 cytokines [interleukin-5 and interleukin-13] and TGF-β1. Conclusion: These studies demonstrate that TLR-9-based therapies inhibit airway inflammation, remodeling and AHR in mice coexposed to ETS and allergen who exhibit enhanced airway inflammation and remodeling. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In response to inflammation or injury, airway epithelial cells express inducible genes that may contribute to allergen-induced airway remodeling. To determine the contribution of epithelial cell NE-κB activation to the remodeling response, we generated CC10- Cretg/IkkβΔ/Δ mice in which NF-κB signaling through 1κB kinase β (IKKβ) is selectively ablated in the airway epithelium by conditional Cre-recombinase expression from the Clara cell (CC10) promoter. Repetitive ovalbumin challenge of mice deficient in airway epithelial IKKβ prevented nuclear translocation of the ReIA NF-κB subunit only in airway epithelial cells, resulting in significantly lower peribronchial fibrosis in CC10-Cretg/lkkβΔ/Δ mice compared with littermate controls as assessed by peribronchial trichrome staining and total lung collagen content. Levels of airway mucus, airway eosinophils, and peribronchial CD4+ cells in ovalbumin-challenged mice were also reduced significantly upon airway epithelial lkkβ ablation. The diminished inflammatory response was associated with reduced expression of NF-κB-regulated chemokines, including eotaxin-1 and thymus- and activation-regulated chemokine, which attract eosinophils and Th2 cells, respectively, into the airway. The number of peribronchial cells expressing TGF-β1, as well as TGF-β1 amounts in bronchoalveolar lavage, were also significantly reduced in mice deficient in airway epithelium IKKβ. Overall, these studies show an important role for NF-κB regulated genes in airway epithelium in allergen-induced airway remodeling, including peribronchial fibrosis and mucus production. [ABSTRACT FROM AUTHOR]

Background: Allergen avoidance and anti-inflammatory therapy are standard therapeutic approaches guidelines advocate to control asthma symptoms. Currently, it is not known whether such strategies reduce airway remodeling. Objective: We have therefore used a mouse model of allergen-induced airway remodeling to determine whether allergen avoidance combined with corticosteroid therapy can reverse established airway remodeling. Methods: Mice were sensitized to ovalbumin and then repetitively challenged with intranasal ovalbumin for 3 months to develop structural features of airway remodeling including peribronchial fibrosis and increased thickness of the peribronchial smooth muscle layer. At this time point, mice were treated with allergen avoidance, allergen avoidance and corticosteroids, or corticosteroids for 1 month to determine whether either strategy could reverse established airway remodeling. Results: Mice repetitively challenged with ovalbumin developed peribronchial fibrosis (increased total lung collagen and increased peribronchial trichrome staining) as well as increased thickness of the peribronchial smooth muscle layer. Allergen avoidance significantly reduced airway inflammation and mucus expression, slightly reduced peribronchial fibrosis, and had no effect on the thickness of the peribronchial smooth muscle layer. Addition of corticosteroids to allergen avoidance significantly reduced levels of peribronchial fibrosis as well as the thickness of the peribronchial smooth muscle layer. Conclusion: Allergen avoidance reduces airway inflammation and mucus expression but has more limited immediate effects on reducing structural features of established airway remodeling. The combination of allergen avoidance and corticosteroid therapy is effective in reversing established features of airway remodeling including peribronchial fibrosis and the increased thickness of the smooth muscle layer. [Copyright &y& Elsevier]

Abstract: Siglec-F is a sialic acid binding immunoglobulin-superfamily receptor that is highly expressed on eosinophils. We have used a mouse model of oral egg ovalbumin (OVA)-induced eosinophilic inflammation of the gastro-intestinal mucosa associated with diarrhea and weight loss to determine whether administering an anti-Siglec-F antibody would reduce levels of intestinal mucosal eosinophilic inflammation. Mice administered the anti-Siglec-F antibody had significantly lower levels of intestinal eosinophilic inflammation, and this was associated with reduced intestinal permeability changes, normalization of intestinal villous crypt height, and restoration of weight gain. The reduced numbers of intestinal eosinophils in anti-Siglec-F antibody treated mice was associated with significantly reduced numbers of bone marrow and peripheral blood eosinophils, but was not associated with significant changes in the numbers of proliferating or apoptotic jejunal eosinophils. In addition, the anti-Siglec-F Ab reduced Th2 cytokines and IgE levels. Overall, these studies demonstrate that administration of an anti-Siglec-F antibody significantly reduces levels of eosinophilic inflammation in the intestinal mucosa and that this was associated with reduced intestinal permeability changes, normalization of intestinal villous crypt height, and restoration of weight gain. [Copyright &y& Elsevier]

The fungal allergen, Alternaría, is specifically associated with severe asthma, including life-threatening exacerbations. To better understand the acute innate airway response to Alternaría, naive wild-type (WT) mice were challenged once intranasally with Alternaría. Naive WT mice developed significant bronchoalveolar lavage eosinophilia following Alternaría challenge when analyzed 24 h later. In contrast to Alternaria, neither Aspergillus nor Candida induced bronchoalveolar lavage eosinophilia. Gene microarray analysis of airway epithelial cell brushings demonstrated that Afterwana-challenged naive WT mice had a >20-fold increase in the level of expression of found in inflammatory zone 1 (FIZZl/Retnla), a resistin-like molecule. Lung immunostaining confirmed strong airway epithelial FIZZ1 expression as early as 3 h after a single Alternaría challenge that persisted for 5 d and was significantly reduced in STAT6-deficient, but not protease-activated receptor 2-deficient mice. Bone marrow chimera studies revealed that STAT6 expressed in lung cells was required for epithelial FIZZ1 expression, whereas STAT6 present in bone marrow-derived cells contributed to airway eosinophilia. Studies investigating which cells in the nonchallenged lung bind FIZZ1 demonstrated that CD45+CDllc+ cells (macrophages and dendritic cells), as well as collagen-1-producing CD45- cells (fibroblasts), can bind to FIZZ1. Importantly, direct administration of recombinant FIZZ1 to naive WT mice led to airway eosinophilia, peribronchial fibrosis, and increased thickness of the airway epithelium. Thus, Alternaría induces STAT6-dependent acute airway eosinophilia and epithelial FIZZ1 expression that promotes airway fibrosis and epithelial thickness. This may provide some insight into the uniquely pathogenic aspects of After/iaria-associated asthma. [ABSTRACT FROM AUTHOR]