Pulmonary Eosinophilic Inflammation Research Articles

Endothelin‐1 directs airway remodeling and hyper‐reactivity in a murine asthma model

BackgroundThe current paradigm describing asthma pathogenesis recognizes the central role of abnormal epithelial function in the generation and maintenance of the disease. However, the mechanisms responsible for the initiation of airway remodeling, which contributes to decreased lung function, remain elusive. Therefore, we aimed to determine the role of altered pulmonary gene expression in disease inception and identify proremodeling mediators.MethodsUsing an adenoviral vector, we generated mice overexpressing smad2, a TGF-β and activin A signaling molecule, in the lung. Animals were exposed to intranasal ovalbumin (OVA) without systemic sensitization.ResultsControl mice exposed to inhaled OVA showed no evidence of pulmonary inflammation, indices of remodeling, or airway hyper-reactivity. In contrast, local smad2 overexpression provoked airway hyper-reactivity in OVA-treated mice, concomitant with increased airway smooth muscle mass and peribronchial collagen deposition. Pulmonary eosinophilic inflammation was not evident, and there was no change in serum IgE or IgG1 levels. The profound remodeling changes were not mediated by classical pro-inflammatory Th2 cytokines. However, uric acid and interleukin-1β levels in the lung were increased. Epithelial-derived endothelin-1 and fibroblast growth factor were also augmented in smad2-expressing mice. Blocking endothelin-1 prevented these phenotypic changes.ConclusionsInnate epithelial-derived mediators are sufficient to drive airway hyper-reactivity and remodeling in response to environmental insults in the absence of overt Th2-type inflammation in a model of noneosinophilic, noninflammed types of asthma. Targeting potential asthma therapies to epithelial cell function and modulation of locally released mediators may represent an effective avenue for therapeutic design.

Prostaglandin E2deficiency causes a phenotype of aspirin sensitivity that depends on platelets and cysteinyl leukotrienes

Aspirin-exacerbated respiratory disease (AERD) is characterized by asthma, tissue eosinophilia, overproduction of cysteinyl leukotrienes (cysLTs), and respiratory reactions to nonselective cyclooxygenase (COX) inhibitors. Ex vivo studies suggest that functional abnormalities of the COX-2/microsomal prostaglandin (PG)E2 synthase-1 system may underlie AERD. We demonstrate that microsomal PGE2 synthase-1 null mice develop a remarkably AERD-like phenotype in a model of eosinophilic pulmonary inflammation. Lysine aspirin (Lys-ASA)-challenged PGE2 synthase-1 null mice exhibit sustained increases in airway resistance, along with lung mast cell (MC) activation and cysLT overproduction. A stable PGE2 analog and a selective E prostanoid (EP)2 receptor agonist blocked the responses to Lys-ASA by ∼90%; EP3 and EP4 agonists were also active. The increases in airway resistance and MC products were blocked by antagonists of the type 1 cysLT receptor or 5-lipoxygenase, implying that bronchoconstriction and MC activation were both cysLT dependent. Lys-ASA-induced cysLT generation and MC activation depended on platelet-adherent granulocytes and T-prostanoid (TP) receptors. Thus, lesions that impair the inducible generation of PGE2 remove control of platelet/granulocyte interactions and TP-receptor-dependent cysLT production, permitting MC activation in response to COX-1 inhibition. The findings suggest applications of antiplatelet drugs or TP receptor antagonists for the treatment of AERD.

Bacillus Calmette-Guérin Suppresses Asthmatic Responses via CD4(+)CD25(+) Regulatory T Cells and Dendritic Cells.

PurposeBacillus Calmette-Guérin (BCG) is known to suppress the asthmatic responses in a murine model of asthma and to induce dendritic cells (DCs) maturation. Mature DCs play a crucial role in the differentiation of regulatory T cells (Tregs), which are known to regulate allergic inflammatory responses. To investigate whether BCG regulates Tregs in a DCs-mediated manner, we analyzed in a murine model of asthma.MethodsBALB/c mice were injected intraperitoneally with BCG or intravenously with BCG-stimulated DCs and then sensitized and challenged with ovalbumin (OVA). Mice were analysed for bronchial hyperresponsiveness (BHR), the influx of inflammatory cells in the bronchoalveolar lavage (BAL) fluid, and histopathological changes in the lung. To identify the mechanisms, IgE, IgG1 and IgG2a in the serum were analysed and the CD25+ Tregs in the mice were depleted with anti-CD25 monoclonal antibody (mAb).ResultsBCG and the transfer of BCG-stimulated DCs both suppressed all aspects of the asthmatic responses, namely, BHR, the production of total IgE and OVA-specific IgE and IgGs, and pulmonary eosinophilic inflammation. Anti-CD25mAb treatment reversed these effects.ConclusionsBCG can attenuate the allergic inflammation in a mouse model of asthma by a Tregs-related mechanism that is mediated by DCs.

A Novel Synthetic Mycolic Acid Inhibits Bronchial Hyperresponsiveness and Allergic Inflammation in a Mouse Model of Asthma

PurposeRecognition of microbes is important to trigger the innate immune system. Mycolic acid (MA) is a component of the cell walls of mycobacteria such as Mycobacterium bovis Bacillus Calmette-Guerin. MA has immunogenic properties, which may modulate the innate and adaptive immune response. This study aimed to investigate whether a novel synthetic MA (sMA) inhibits allergic inflammatory responses in a mouse model of asthma.MethodsBALB/c mice were injected intraperitoneally with sMA followed by sensitization and challenge with ovalbumin (OVA). Mice were examined for bronchial hyperresponsiveness (BHR), the influx of inflammatory cells into the lung tissues, histopathological changes in the lungs and CD4+CD25+Foxp3+ T cells in the spleen, and examined the response after the depleting regulatory T cells (Tregs) with an anti-CD25mAb.ResultsTreatment of mice with sMA suppressed the asthmatic response, including BHR, bronchoalveolar inflammation, and pulmonary eosinophilic inflammation. Anti-CD25mAb treatment abrogated the suppressive effects of sMA in this mouse model of asthma and totally depleted CD4+CD25+Foxp3+ T cells in the spleen.ConclusionssMA attenuated allergic inflammation in a mouse model of asthma, which might be related with CD4+CD25+Foxp3+ T cell.

Development of a model of Ascaris Suum antigen-induced pulmonary inflammation in nonhuman primates

Airway inflammation is one of the hallmarks of asthma and can contribute to airway hyperresponsiveness. Using cynomolgus monkeys (Macaca fascicularis) that are naturally sensitized to Ascaris suum antigen in the wild, we developed a reproducible model of acute airway inflammation following segmental A.suum antigen challenge. A pediatric bronchoscope was used to perform bronchoalveolar lavage (BAL) for the collection of BAL cells and fluid (BALF). The bronchoscope was also used for the administration of a segmental lung A.suum challenge. Baseline BAL was performed on one lung prior to segmental antigen challenge on the opposite lung. BAL on the challenged lung was performed 24 hours post-challenge to assess pulmonary inflammation. As compared to baseline lavage, a single airway challenge with A.suum antigen, at a dose of 0.50 or 0.75 mg/challenge, resulted in a reproducible pulmonary inflammation. The inflammation was characterized by an increase in total BAL cell counts and increased eosinophils. From concentrated BALF samples, taken 24 hours post A.suum antigen challenge, there was also a trend towards increased IL-5 and eotaxin as measured by ELISA. In some studies, animals were treated with two doses of the steroid, dexamethasone (DEX), 1 mg/kg by IM injection, prior to antigen challenge. In these studies, administration of DEX prior to antigen challenge prevented airway inflammation. These data show that segmental challenge with A. suum antigen produced an acute pulmonary eosinophilic inflammation that was prevented by pretreatment with the steroid, dexamethasone. This model should be useful for testing the efficacy of selected drug candidates, as compared to proven anti-inflammatory therapy, in blocking the pulmonary inflammatory response to A. suum in a large animal model.

천식동물모델을 이용한 지골피(地骨皮), 상백피(桑白皮) 및 두 배합약물의 실험적 연구

Objectives : To clarify the possible effect of Lycium chinese Mill (LC)., Morus alba L (MA)., and Lycium chinese Mill. +Morus alba L. (LC+MA), we have examined their influence on the development of pulmonary eosinophilic inflammation in the asthmatic murine model. Methods : Female Balb/c mice (5weeks) were immunized on two different days (21 days and 7 days before inhalational exposure) by intraperitonial injections of 0.2ml alum-precipitated Ag containing <TEX>$100{\mu}g$</TEX> of OVA bound to 4 mg of aluminum hydroxide in PBS. Seven days after the second sensitization, mice were exposed to aerosolized ovalbumin for 30 minutes/day on 3 days/week for 8 weeks (at a flow rate of 250 L/min, 2.5% ovalbumin in normal saline) and, LC, MA, and LC+MA (500 mg/kg) were orally administered 3 times per a week for 8 weeks. Results : The suppressive effect of LC, MA, and LC+MA were demonstrated by the accumulation of eosinophills into airways, with the reduction of eosinophil, total lung leukocytes numbers. These were correlated with the marked reduction of IL-5, IL-13 and IL-4 levels in the BALF and serum. OVA-specific IgE levels were also decreased in serum and BAL from these mice. LC, MA, and LC+MA decreased eosinophil CCR3 expression and CD11b expression in lung cells. Conclusions : These results indicate that LC, MA, and LC+MA have high inhibitory effects on airway inflammation and hyper-responsiveness in the asthmatic murine model. The suppression of IL-5, IgE, eosinophil CCR3 expression and CD11b expression, and the increase of IFN-<TEX>${\gamma}$</TEX> production in BALF seem to contribute to this effect. Hence, the results indicated that LC, MA, and LC+MA could act as a immuno-modulator which possesses anti-inflammatory and anti-asthmatic property by modulating the imbalance between Th1 and Th2 cytokines.

Effects of Lactobacillus rhamnosus on asthma with an adoptive transfer of dendritic cells in mice

This study was designed to investigate whether the protective effects of Lactobacillus rhamnosus (Lcr35) on allergic asthma are associated with the adoptive transfer of dendritic cells (DCs) and regulatory T cells (Tregs), using a mouse experimental model of asthma. BALB/c mice were orally administered Lcr35 or intravenously treated with in vivo Lcr35-treated DCs daily and were then sensitized and challenged with ovalbumin (OVA) in accordance with a model of asthma protocol. Both the oral application of Lcr35 and intravenous administration of Lcr35-treated DCs suppressed all aspects of the asthmatic response, including bronchial hyperresponsiveness (BHR), total cell counts in the bronchoalveolar lavage (BAL) fluid, the production of OVA-specificimmunoglobulin E (IgE), and pulmonary eosinophilic inflammation. The mechanism of action of Lcr35 is related to Tregs, which suppress the Th2 response in the respiratory organs, and this is mediated by DCs in the mouse model of asthma. These results confirm that the mechanism underlying the effects of Lcr35 on asthma involves the adoptive transfer of DCs. This finding broadens the possibility that Lcr35 has potential as an alternative therapeutic approach to the treatment of human asthma.

Group V secretory phospholipase A2 is involved in macrophage activation and is sufficient for macrophage effector functions in allergic pulmonary inflammation.

We reported that Pla2g5-null mice lacking group V secretory phospholipase A2 (gV-sPLA2) showed reduced eosinophilic pulmonary inflammation and Th2 cytokine generation when challenged with an extract from house dust mite Dermatophagoides farinae, compared with wild-type (WT) controls. Adoptive transfer studies suggested that gV-sPLA2 in dendritic cells was necessary for sensitization of Pla2g5-null mice, but was not sufficient to induce the effector phase of pulmonary inflammation. In this study, we demonstrate that gV-sPLA2 is inducibly expressed in mouse and human macrophages (M) activated by IL-4 and is required for the acquisition of M effector functions that facilitate the effector phase of pulmonary inflammation. We demonstrate that gV-sPLA2 expression in M is sufficient for the development of pulmonary inflammation, even when inflammation is induced by intrapulmonary administration of IL-4. The concentrations of CCL22/CCL17 and effector T cell recruitment are severely impaired in Pla2g5-null mice. Intratracheal transfers of enriched CD68(+) cells isolated from the lungs of D. farinae-challenged WT donor mice induce eosinophilia, chemokine production, and recruitment of T cells into the lungs of Pla2g5-null recipients previously sensitized by WT D. farinae-loaded dendritic cells. Our studies identified a unique function of gV-sPLA2 in activation of M and in their capacity to recruit T cells to amplify the effector phase of pulmonary inflammation.

TSG-6 Protein Is Crucial for the Development of Pulmonary Hyaluronan Deposition, Eosinophilia, and Airway Hyperresponsiveness in a Murine Model of Asthma

Hyaluronan (HA) deposition is often correlated with mucosal inflammatory responses, where HA mediates both protective and pathological responses. By modifying the HA matrix, Tnfip6 (TNF-α-induced protein-6; also known as TSG-6 (TNF-stimulated gene-6)) is thought to potentiate anti-inflammatory and anti-plasmin effects that are inhibitory to leukocyte extravasation. In this study, we examined the role of endogenous TSG-6 in the pathophysiological responses associated with acute allergic pulmonary inflammation. Compared with wild-type littermate controls, TSG-6(-/-) mice exhibited attenuated inflammation marked by a significant decrease in pulmonary HA concentrations measured in the bronchoalveolar lavage and lung tissue. Interestingly, despite the equivalent induction of both humoral and cellular Th2 immunity and the comparable levels of cytokines and chemokines typically associated with eosinophilic pulmonary inflammation, airway eosinophilia was significantly decreased in TSG-6(-/-) mice. Most importantly, contrary to their counterpart wild-type littermates, TSG-6(-/-) mice were resistant to the induction of airway hyperresponsiveness and manifested improved lung mechanics in response to methacholine challenge. Our study demonstrates that endogenous TSG-6 is dispensable for the induction of Th2 immunity but is essential for the robust increase in pulmonary HA deposition, propagation of acute eosinophilic pulmonary inflammation, and development of airway hyperresponsiveness. Thus, TSG-6 is implicated in the experimental murine model of allergic pulmonary inflammation and is likely to contribute to the pathogenesis of asthma.

Chronic eosinophilic pneumonia: A case report and review of the literature

Objective: We introduce one case of chronic eosinophilic pneumonia (CEP) and review the literature nearly 10 years in order to improve the understanding of this rare disease. Methods: A case of CEP diagnosed by transbronchial lung biopsy with clinical and follow-up data was analyzed and its clinical features, diagnosis and treatment combined with the literature were discussed. Result: CEP is a chronic pulmonary eosinophilic inflammation with unknown etiology, characterized by history of allergic disease, cough, sputum, but often breathlessness and wheezing; eosinophil in peripheral blood and/or sputum and/or bronchoalveolar lavage fluid significantly increased; chest X-ray showed progressively peripheral non-segment distribution of high-density infiltrates, often called “reversed pulmonary edema sign”; Pathology showed eosinophil infiltration in lung interstitial, bronchial submucosal and excessive eosinophil exudation in alveolar. Oral corticosteroids had a good response, but easy to relapse. Conclusions: Eosinophil count of bronchoalveolar lavage or lung biopsy can confirm the diagnosis of CEP timely in suspected patients. Bronchoscope can play an important role in assisting diagnosis and improving symptoms.

Ursolic acid, a potential PPARγ agonist, suppresses ovalbumin-induced airway inflammation and Penh by down-regulating IL-5, IL-13, and IL-17 in a mouse model of allergic asthma

Allergic asthma is a chronic airway disorder characterized by airway hyperresponsiveness to allergens, chronic airway inflammation, airway edema, increased mucus secretion, excess production of Th2 cytokines, and eosinophil accumulation in the lungs. Ursolic acid is known for its pharmacological effects, such as its anti-tumor, anti-inflammatory and antimicrobial activities. To investigate the anti-asthmatic effects and mechanism of ursolic acid, we studied the development of pulmonary eosinophilic inflammation and enhanced pause (Penh) in a mouse model of allergic asthma.In this study, BALB/c mice were systemically sensitized to ovalbumin followed by intratracheal, intraperitoneal, and aerosol allergen challenges. We investigated the effect of ursolic acid and Cyclosporin A (CsA) on Penh, pulmonary eosinophilic infiltration, various immune cell phenotypes, Th2 cytokines, IL-17 production, and ovalbumin specific IgE production in a mouse model of asthma.In BALB/c mice, ursolic acid had suppressed eosinophil infiltration, allergic airway inflammation, and Penh, which occurred by suppressing the production of IL-5, IL-13, IL-17, and ovalbumin-specific IgE by blocking the GATA-3 and STAT6 pathways.Our data suggest the therapeutic mechanism of ursolic acid in asthma is based on reductions of Th2 cytokines (IL-5 and IL-13), ovalbumin-specific IgE production, and eosinophil infiltration via the Th2-GATA-3, STAT6, and IL-17-NF-κB pathways.

Glycyrrhiza uralensis Flavonoids Present in Anti‐Asthma Formula, ASHMITM, Inhibit Memory Th2 Responses in Vitro and in Vivo

Allergic asthma is associated with Th2-mediated inflammation. Several flavonoids were isolated from Glycyrrhiza uralensis, one of the herbs in the anti-asthma herbal medicine intervention. The aim of this investigation was to determine whether Glycyrrhiza uralensis flavonoids have inhibitory effects on memory Th2 responses in vitro and antigen-induced Th2 inflammation in vivo. The effects of three Glycyrrhiza uralensis flavonoids on effector memory Th2 cells, D10.G4.1 (D10 cells), were determined by measuring Th2 cytokine production. Isoliquiritigenin, 7, 4'-dihydroxyflavone (7, 4'-DHF) and liquiritigenin significantly suppressed IL-4 and IL-5 production in a dose-dependent manner, 7, 4'-DHF being most potent. It was also evaluated for effects on D10 cell proliferation, GATA-3 expression and IL-4 mRNA expression, which were suppressed, with no loss of cell viability. Chronic treatment with 7, 4'-DHF in a murine model of allergic asthma not only significantly reduced eosinophilic pulmonary inflammation, serum IgE levels, IL-4 and IL-13 levels, but also increased IFN-γ production in lung cell cultures in response to antigen stimulation.

Cysteinyl Leukotriene 2 Receptor on Dendritic Cells Negatively Regulates Ligand-Dependent Allergic Pulmonary Inflammation

Cysteinyl leukotrienes (cys-LTs) can mediate Th2 immunity to the house dust mite, Dermatophagoides farinae, via the type 1 receptor CysLT(1)R on dendritic cells (DCs). However, the role of the homologous type 2 receptor CysLT(2)R in Th2 immunity is unknown. D. farinae sensitization and challenge of CysLT(2)R-deficient mice showed a marked augmentation of eosinophilic pulmonary inflammation, serum IgE, and Th2 cytokines. Wild-type (WT) mice sensitized by adoptive transfer of D. farinae-pulsed CysLT(2)R-deficient bone marrow-derived DCs (BMDCs) also had a marked increase in D. farinae-elicited eosinophilic lung inflammation and Th2 cytokines in restimulated hilar nodes. This response was absent in mice sensitized with D. farinae-pulsed BMDCs lacking leukotriene C(4) synthase (LTC(4)S), CysLT(1)R, or both CysLT(2)R/LTC(4)S, suggesting that CysLT(2)R negatively regulates LTC(4)S- and CysLT(1)R-dependent DC-mediated sensitization. CysLT(2)R-deficient BMDCs had increased CysLT(1)R-dependent LTD(4)-induced ERK phosphorylation, whereas N-methyl LTC(4) activation of CysLT(2)R on WT BMDCs reduced such signaling. Activation of endogenously expressed CysLT(1)R and CysLT(2)R occurred over an equimolar range of LTD(4) and N-methyl LTC(4), respectively. Although the baseline expression of cell surface CysLT(1)R was not increased on CysLT(2)R-deficient BMDCs, it was upregulated at 24 h by a pulse of D. farinae, compared with WT or CysLT(2)R/LTC(4)S-deficient BMDCs. Importantly, treatment with N-methyl LTC(4) reduced D. farinae-induced CysLT(1)R expression on WT BMDCs. Thus, CysLT(2)R negatively regulates the development of cys-LT-dependent Th2 pulmonary inflammation by inhibiting both CysLT(1)R signaling and D. farinae-induced LTC(4)S-dependent cell surface expression of CysLT(1)R on DCs. Furthermore, these studies highlight how the biologic activity of cys-LTs can be tightly regulated by competition between these endogenously expressed receptors.

The Toll-like receptor 5 ligand flagellin promotes asthma by priming allergic responses to indoor allergens

Allergic asthma is a complex disease characterized by eosinophilic pulmonary inflammation, mucus production and reversible airway obstruction1. Exposure to indoor allergens is a clear risk factor for asthma, but this disease is also associated with high household levels of total and Gram-negative bacteria2. The ability of bacterial products to act as adjuvants3 suggests they might promote asthma by priming allergic sensitization to inhaled allergens. In support of this idea, house dust extracts (HDEs) can activate antigen presenting dendritic cells (DC) in vitro and promote allergic sensitization to inhaled innocuous proteinsin vivo4. It is unknown which microbial products provide most of the adjuvant activity in HDEs. A screen of microbial products for their adjuvant activity in the airway revealed that the bacterial protein, flagellin (FLA) stimulated strong allergic responses to an innocuous inhaled protein. Moreover, toll-like receptor (TLR)5, the mammalian receptor for FLA5,6, was required for priming strong allergic responses to natural indoor allergens present in HDEs. In addition, the incidence of human asthma was associated with high serum levels of FLA-specific antibodies. Together, these findings suggest that household FLA promotes the development of allergic asthma by TLR5-dependent priming of allergic responses to indoor allergens.

Allergen‐Induced Bone Marrow Eosinophilopoiesis and Airways Eosinophilic Inflammation in Leptin‐Deficient ob/ob Mice

Asthma and obesity are growing epidemics in the world. It is well established that obesity worsens the asthma outcomes. High-fat diet-induced obesity in mice exacerbates the pulmonary eosinophilic inflammation. We have used wild-type (WT) and ob/ob mice to further explore the mechanisms by which obesity aggravates the pulmonary eosinophilic inflammation. The eosinophil (EO) number in bronchoalveolar lavage (BAL) fluid, lung tissue, blood, and bone marrow were evaluated at 24, 48, and 72 h after ovalbumin (OVA) challenge in sensitized mice. The basal EO number (phosphate-buffered saline (PBS)-instilled mice) in lung tissue was about 3.5-fold greater in ob/ob compared with WT mice. OVA challenge in ob/ob mice promoted an EO accumulation into the lung that was accompanied by a lower emigration to airways lumen (BAL fluid) in comparison with WT mice. OVA challenge also markedly elevated the number of mature and immature EO in bone marrow of ob/ob mice at 24 h compared with WT group. Blood EO at 48 h was markedly greater in ob/ob mice. Tumor necrosis factor (TNF)-α and interleukin (IL)-10 levels in BAL fluid were significantly higher in ob/ob mice, whereas no changes for IL-5 and eotaxin were found. The IL-6 levels were significantly lower in ob/ob mice. In conclusion, OVA challenge in ob/ob obese mice potentiates eosinophilopoiesis and promotes an accumulation of EO into the lung tissue, delaying their transit to airways lumen. The longer EO remain into the lung tissue is likely to contribute, at least in part, to the asthma worsened by obesity.

Effects of Corni fructus on ovalbumin-induced airway inflammation and airway hyper-responsiveness in a mouse model of allergic asthma.

BackgroundAllergic asthma is a chronic inflammatory lung disease that is characterized by airway hyperresponsiveness (AHR) to allergens, airway oedema, increased mucus secretion, excess production of T helper-2 (Th2) cytokines, and eosinophil accumulation in the lungs. Corni fructus (CF) is a fruit of Cornus officinalis Sieb. Et. Zucc. (Cornaceae) and has been used in traditional Korean medicine as an anti-inflammatory, analgesic, and diuretic agent. To investigate the anti-asthmatic effects of CF and their underlying mechanism, we examined the influence of CF on the development of pulmonary eosinophilic inflammation and airway hyperresponsiveness in a mouse model of allergic asthma.MethodsIn this study, BALB/c mice were systemically sensitized to ovalbumin (OVA) by intraperitoneal (i.p.), intratracheal (i.t.) injections and intranasal (i.n.) inhalation of OVA. We investigated the effect of CF on airway hyperresponsiveness, pulmonary eosinophilic infiltration, various immune cell phenotypes, Th2 cytokine production, and OVA-specific immunoglobulin E (IgE) production.ResultsThe CF-treated groups showed suppressed eosinophil infiltration, allergic airway inflammation, and AHR via reduced production of interleuin (IL) -5, IL-13, and OVA-specific IgE.ConclusionsOur data suggest that the therapeutic effects of CF in asthma are mediated by reduced production of Th2 cytokines (IL-5), eotaxin, and OVA-specific IgE and reduced eosinophil infiltration.

Asthma Prevention byLactobacillus Rhamnosusin a Mouse Model is Associated With CD4+CD25+Foxp3+T Cells

PurposeProbiotic bacteria can induce immune regulation or immune tolerance in allergic diseases. The underlying mechanisms have been recently investigated, but are still unclear. The aim of this study was to evaluate the protective effects of the probiotic Lactobacillus rhamnosus (Lcr35) in a mouse model of asthma and to identify its mechanism of action.MethodsLcr35 was administered daily by the oral route at a dosage of 1×109 CFU/mouse in BALB/c mice for 7 days before the first sensitization. Clinical parameters and regulatory T (Treg) cells were examined. The role of CD4+CD25+Foxp3+ Treg cells was analyzed using a Treg cell-depleting anti-CD25 monoclonal antibody (mAb).ResultsAirway hyperresponsiveness, total IgE production, pulmonary eosinophilic inflammation, and splenic lymphocyte proliferation were suppressed after Lcr35 treatment. Th1 (IFN-γ) and Th2 (IL-4, IL-5, and IL-13) cytokines in the serum were suppressed, and the percentage of CD4+CD25+Foxp3+ Treg cells in the spleen was significantly increased in the Lcr35 treatment group. Anti-CD25 mAb administration abolished the protective effects of Lcr35, indicating that CD4+ CD25+Foxp3+ Treg cells are essential in mediating the activity of Lcr35.ConclusionsOral administration of Lcr35 attenuated the features of allergic asthma in a mouse model and induced immune regulation by a CD4+CD25+Foxp3+ Treg cell-mediated mechanism.

The therapeutic effect of Drynariae Rhizoma in a mouse model of allergic asthma

Objective : Allergic asthma is a chronic airway disease that affects millions of people in the developed world. The disease is characterized by concurring airway inflammation, Th2 cytokine production, increased mucus secretion, airway hyperresponsiveness (AHR) to inhaled antigen, and pulmonary fibrosis. To investigate the therapeutic and anti-asthmatic effects of Drynariae Rhizoma (DR), we examined the influence of DR on the development of pulmonary eosinophilic inflammation and airway hyperresponsiveness in a mouse model of allergic asthma. Methods : In this study, BALB/c mice were systemically sensitized to ovalbumin (OVA) followed intratracheally, intraperitoneally, and by aerosol allergen challenges. We investigated the effect of DR on airway hyperresponsiveness, pulmonary eosinophilic infiltration, various immune cell phenotypes, Th2 cytokine production and OVA specific IgE production in a mouse model of asthma. Results : In asthmatic mice, we found that DR.treated groups had suppressed eosinophil infiltration, allergic airway inflammation and AHR by suppressing the production of IL-5, IL-13 and OVA specific IgE. Conclusions : Our data suggest that the therapeutic mechanism by which DR effectively treats asthma is based on reductions of Th2 cytokines (IL-5), eotaxin, OVA-specific IgE production and eosinophil infiltration.

TGF-β1 suppresses mast cell functions in vivo. (151.15)

Abstract We have previously demonstrated the immunosuppressive effects of TGFβ1 on IgE signaling in human and mouse mast cells in vitro. Here we extend our focus to in vivo models, including mast cell-dependent airway inflammation. TGFβ1 injection into unimmunized mice reduced peritoneal mast cell numbers and their expression of the high affinity IgE receptor, as well as cKit. Further, TGFβ1 delivered as an aerosol to ovalbumin-immunized mice decreased pulmonary eosinophilic inflammation and mucus production. TGFβ1 did not affect Syk, Stat5, Fyn or Akt mRNA expression. However, mast cell Fyn and Stat5 protein levels were diminished by TGFβ1 treatment in vitro, while Akt and Syk were unaffected. Interestingly, we found that mast cells from the 129/SvJ mouse strain were resistant to TGFβ1-mediated suppression. Unlike their C57BL/6 counterparts, 129/SvJ mast cells did not demonstrate reduced IgE receptor expression or IgE-mediated cytokine production after culture with TGFβ1. These data show that TGFβ1 is a potent suppressor of the mast cell response that may be altered by host genetic makeup. We further find that the effects of TGFβ1 include selective reduction in key IgE-mediated signaling molecules.

Dectin-2 mediates Th2 immunity through the generation of cysteinyl leukotrienes

The innate signaling pathways for Th2 immunity activated by inhaled antigens are not well defined. We previously identified Dectin-2 as a receptor for glycans in allergen extracts from the house dust mite Dermatophagoides farinae (Df) that mediates cysteinyl leukotriene (cys-LT) generation from pulmonary CD11c+ cells and from GM-CSF-cultured bone marrow cells (BMCs(GM-CSF)). Using lentiviral knockdown of Dectin-2 in BMCs(GM-CSF) and adoptive transfer of Df-pulsed BMCs(GM-CSF) to sensitize naive mice, we now report that Dectin-2 is critical for the development of Df-elicited eosinophilic and neutrophilic pulmonary inflammation and Th2 cytokine generation in the lungs and restimulated lymph nodes. Sensitization with Df-pulsed BMCs(GM-CSF) from LTC(4) synthase (LTC(4)S)-deficient mice or type 1 cys-LT receptor (CysLT1R)-deficient mice demonstrated that both proteins were required for Df-elicited eosinophilic pulmonary inflammation and Th2 cytokine generation in the lungs and restimulated lymph nodes. Direct sensitization and challenge of Ltc4s-/- and Cysltr1-/- mice confirmed that cys-LTs mediate these parameters of Df-elicited Th2 pulmonary inflammation. Thus, the Dectin-2-cys-LT pathway is critical for the induction of Th2 immunity to a major allergen, in part through CysLT1R. These findings identify a previously unrecognized link between a myeloid C-type lectin receptor and Th2 immunity.