Effects of chronic L-NAME treatment lung tissue mechanics, eosinophilic and extracellular matrix responses induced by chronic pulmonary inflammation

The importance of lung tissue in asthma pathophysiology has been recently recognized. Although nitric oxide mediates smooth muscle tonus control in airways, its effects on lung tissue responsiveness have not been investigated previously. We hypothesized that chronic nitric oxide synthase (NOS) inhibition by N(omega)-nitro-L-arginine methyl ester (L-NAME) may modulate lung tissue mechanics and eosinophil and extracellular matrix remodeling in guinea pigs with chronic pulmonary inflammation. Animals were submitted to seven saline or ovalbumin exposures with increasing doses (1 approximately 5 mg/ml for 4 wk) and treated or not with L-NAME in drinking water. After the seventh inhalation (72 h), animals were anesthetized and exsanguinated, and oscillatory mechanics of lung tissue strips were performed in baseline condition and after ovalbumin challenge (0.1%). Using morphometry, we assessed the density of eosinophils, neuronal NOS (nNOS)- and inducible NOS (iNOS)-positive distal lung cells, smooth muscle cells, as well as collagen and elastic fibers in lung tissue. Ovalbumin-exposed animals had an increase in baseline and maximal tissue resistance and elastance, eosinophil density, nNOS- and iNOS-positive cells, the amount of collagen and elastic fibers, and isoprostane-8-PGF(2alpha) expression in the alveolar septa compared with controls (P<0.05). L-NAME treatment in ovalbumin-exposed animals attenuated lung tissue mechanical responses (P<0.01), nNOS- and iNOS-positive cells, elastic fiber content (P<0.001), and isoprostane-8-PGF(2alpha) in the alveolar septa (P<0.001). However, this treatment did not affect the total number of eosinophils and collagen deposition. These data suggest that NO contributes to distal lung parenchyma constriction and to elastic fiber deposition in this model. One possibility may be related to the effects of NO activating the oxidative stress pathway.     

Comparison of early and late responses to antigen of sensitized guinea pig parenchymal lung strips.

The peripheral lung parenchyma has been studied as a component of the asthmatic inflammatory response. During induced constriction, tissue resistance increases in different asthma models. Approximately 60% of the asthmatic patients show early and late responses. The late response is characterized by more severe airway obstruction. In the present study, we evaluated lung parenchymal strips mechanics in ovalbumin-sensitized guinea pigs, trying to reproduce both early and late inflammatory responses. Oscillatory mechanics of lung strips were performed in a control group (C), in an early response group (ER), and in two late response groups: 17 h (L1) and 72 h (L2) after the last ovalbumin challenge. Measurements of resistance and elastance were obtained before and after ovalbumin challenge in C and ER groups and before and after acetylcholine challenge in all groups. Using morphometry, we assessed the density of eosinophils and smooth muscle cells, as well as collagen and elastin content in lung strips. The baseline and postagonist values of resistance and elastance were increased in ER, L1, and L2 groups compared with C (P < or = 0.001). The morphometric analysis showed an increase in alveolar eosinophil density in ER and L2 groups compared with C (P < 0.05). There was a significant correlation between eosinophil density in parenchymal strips of C, L1, and L2 groups and values of resistance and elastance postacetylcholine (r = 0.71, P = 0.001 and r = 0.74, P < 0.001, respectively). The results show that the lung parenchyma is involved in the late response, and the constriction response in this phase is related to the eosinophilic inflammation.     

Effects of acute and chronic nitric oxide inhibition in an experimental model of chronic pulmonary allergic inflammation in guinea pigs

Endogenously produced nitric oxide is a recognized regulator of physiological lung events, such as a neurotransmitter and a proinflammatory mediator. We tested the differences between chronic and acute nitric oxide inhibition by N(omega)-nitro-L-arginine methyl ester (L-NAME) treatment in lung mechanics, inflammation, and airway remodeling in an experimental asthma model in guinea pigs. Both acute and chronic L-NAME treatment reduced exhaled nitric oxide in sensitized animals (P < 0.001). Chronic L-NAME treatment increased baseline and maximal responses after antigen challenge of respiratory system resistance and reduced peribronchial edema and mononuclear cells airway infiltration (P < 0.05). Acute administration of L-NAME increased maximal values of respiratory system elastance and reduced mononuclear cells and eosinophils in airway wall (P < 0.05). Chronic ovalbumin exposure resulted in airway wall thickening due to an increase in collagen content (P < 0.005). Chronic nitric oxide inhibition increased collagen deposition in airway wall in sensitized animals (P < 0.05). These data support the hypothesis that in this model nitric oxide acts as a bronchodilator, mainly in proximal airways. Furthermore, chronic nitric oxide inhibition was effective in reducing edema and mononuclear cells in airway wall. However, airway eosinophilic inflammation was unaltered by chronic L-NAME treatment. In addition, nitric oxide inhibition upregulates collagen deposition in airway walls.     

Autophagy induces eosinophil extracellular traps formation and allergic airway inflammation in a murine asthma model

Studies have shown autophagy participation in the immunopathology of inflammatory diseases. However, autophagy role in asthma and in eosinophil extracellular traps (EETs) release is poorly understood. Here, we attempted to investigate the autophagy involvement in EETs release and in lung inflammation in an experimental asthma model. Mice were sensitized with ovalbumin (OVA), followed by OVA challenge. Before the challenge with OVA, mice were treated with an autophagy inhibitor, 3-methyladenine (3-MA). We showed that 3-MA treatment decreases the number of eosinophils, eosinophil peroxidase (EPO) activity, goblet cells hyperplasia, proinflammatory cytokines, and nuclear factor kappa B (NFκB) p65 immunocontent in the lung. Moreover, 3-MA was able to improve oxidative stress, mitochondrial energy metabolism, and Na⁺, K⁺-ATPase activity. We demonstrated that treatment with autophagy inhibitor 3-MA reduced EETs formation in the airway. On the basis of our results, 3-MA treatment can be an interesting alternative for reducing lung inflammation, oxidative stress, mitochondrial damage, and EETs formation in asthma.     

Aerobic conditioning and allergic pulmonary inflammation in mice. II. Effects on lung vascular and parenchymal inflammation and remodeling

Recent evidence suggests that asthma leads to inflammation and remodeling not only in the airways but also in pulmonary vessels and parenchyma. In addition, some studies demonstrated that aerobic training decreases chronic allergic inflammation in the airways; however, its effects on the pulmonary vessels and parenchyma have not been previously evaluated. Our objective was to test the hypothesis that aerobic conditioning reduces inflammation and remodeling in pulmonary vessels and parenchyma in a model of chronic allergic lung inflammation. Balb/c mice were sensitized at days 0, 14, 28, and 42 and challenged with ovalbumin (OVA) from day 21 to day 50. Aerobic training started on day 21 and continued until day 50. Pulmonary vessel and parenchyma inflammation and remodeling were evaluated by quantitative analysis of eosinophils and mononuclear cells and by collagen and elastin contents and smooth muscle thickness. Immunohistochemistry was performed to quantify the density of positive cells to interleukin (IL)-2, IL-4, IL-5, interferon-gamma, IL-10, monocyte chemotatic protein (MCP)-1, nuclear factor (NF)-kappaB p65, and insulin-like growth factor (IGF)-I. OVA exposure induced pulmonary blood vessels and parenchyma inflammation as well as increased expression of IL-4, IL-5, MCP-1, NF-kappaB p65, and IGF-I by inflammatory cells were reduced by aerobic conditioning. OVA exposure also induced an increase in smooth muscle thickness and elastic and collagen contents in pulmonary vessels, which were reduced by aerobic conditioning. Aerobic conditioning increased the expression of IL-10 in sensitized mice. We conclude that aerobic conditioning decreases pulmonary vascular and parenchymal inflammation and remodeling in this experimental model of chronic allergic lung inflammation in mice.     

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.     

1′-Acetoxychavicol Acetate Isolated from Alpinia galanga Ameliorates Ovalbumin-Induced Asthma in Mice

The World Health Organization reports that 235 million people are currently affected by asthma. This disease is associated with an imbalance of Th1 and Th2 cells, which results in the upregulation of cytokines that promote chronic inflammation of the respiratory system. The inflammatory response causes airway obstruction and can ultimately result in death. In this study we evaluated the effect of 1′-acetoxychavicol acetate (ACA) isolated from Alpinia galanga rhizomes in a mouse model of ovalbumin (OVA)-induced asthma. To generate the mouse model, BALB/c mice were sensitized by intraperitoneal injection of OVA and then challenged with OVA inhalation for 5 days. Mice in the vehicle control group were sensitized with OVA but not challenged with OVA. Treatment groups received dexamethasone, 25 mg/kg/day ACA, or 50 mg/kg/day ACA for 5 days. Asthma-related inflammation was assessed by bronchoalveolar lavage fluid cell counts and histopathological and immunohistochemical analysis of lung tissues. Our results showed that ACA reduced the infiltration of white blood cells (especially eosinophils) and the level of IgE in the lungs of mice challenged with OVA and suppressed histopathological changes such as airway remodeling, goblet-cell hyperplasia, eosinophil infiltration, and glycoprotein secretion. In addition, ACA inhibited expression of the Th2 cytokines interleukin (IL)-4 and IL-13, and Th1 cytokines IL-12α and interferon-γ. Because asthmatic reactions are mediated by diverse immune and inflammatory pathways, ACA shows promise as an antiasthmatic drug candidate.     

Reactive oxygen species are involved in eosinophil extracellular traps release and in airway inflammation in asthma

In asthma, there are high levels of inflammatory mediators, reactive oxygen species (ROS), and eosinophil extracellular traps (EETs) formation in airway. Here, we attempted to investigate the ROS involvement in EETs release and airway inflammation in OVA-challenged mice. Before the intranasal challenge with ovalbumin (OVA), animals were treated with two ROS inhibitors, N-acetylcysteine (NAC) or diphenyleneiodonium (DPI). We showed that NAC treatment reduced inflammatory cells in lung. DPI and NAC treatments reduced eosinophil peroxidase (EPO), goblet cells hyperplasia, proinflammatory cytokines, NFκB p65 immunocontent, and oxidative stress in lung. However, only the NAC treatment improved mitochondrial energy metabolism. Moreover, the treatments with DPI and NAC reduced EETs release in airway. This is the first study to show that ROS are needed for EETs formation in asthma. Based on our results, NAC and DPI treatments can be an interesting alternative for reducing airway inflammation, mitochondrial damage, and EETs release in asthma.     

Lung Remodeling in a Mouse Model of Asthma Involves a Balance between TGF-β1 and BMP-7

A key event in chronic allergic asthma is the TGF-β-induced activation of fibroblasts into α-SMA-positive myofibroblasts which synthesize type-I collagen. In the present study we investigated the effect of the anti-fibrotic molecule BMP-7 in asthma. Balb/c mice were immunized i.p. with ovalbumin in alum and challenged every 2 days with ovalbumin aerosol (two or six challenges for acute and chronic protocols, respectively). The lung was evaluated for: α-SMA and type-I collagen by immunohistochemistry; BMP-7 and TGF- β1 gene expression by qRT-PCR; type-I collagen and Smads 2 and 3 by immunoblotting; mucus by PSA staining. Type-I collagen around bronchi, α-SMA, mucus secretion, TGF- β1 and BMP-7 gene expression were all increased in asthma. The TGF- β1/BMP-7 ratio was higher in the chronic group and correlated with higher levels of collagen. Fibroblasts isolated from asthmatic and healthy lungs produced type-I collagen upon stimulation with TGF- β1 via phosphorylation of Smad-2, Smad-3. Pre-treatment of the fibroblasts with BMP-7 reduced collagen production and Smads phosphorylation. Intranasal treatment of asthmatic mice with recombinant BMP-7 during the immunization protocol reduced lung inflammation and type I collagen deposition. These results suggest a protective role for BMP-7 in lung allergic inflammation, opposing the pro-fibrotic effects of TGF- β1.     

D-4F, an apoA-1 mimetic, decreases airway hyperresponsiveness, inflammation, and oxidative stress in a murine model of asthma

Asthma is characterized by oxidative stress and inflammation of the airways. Although proinflammatory lipids are involved in asthma, therapies targeting them remain lacking. Ac-DWFKAFYDKVAEKFKEAFNH(2) (4F) is an apolipoprotein (apo)A-I mimetic that has been shown to preferentially bind oxidized lipids and improve HDL function. The objective of the present study was to determine the effects of 4F on oxidative stress, inflammation, and airway resistance in an established murine model of asthma. We show here that ovalbumin (OVA)-sensitization increased airway hyperresponsiveness, eosinophil recruitment, and collagen deposition in lungs of C57BL/6J mice by a mechanism that could be reduced by 4F. OVA sensitization induced marked increases in transforming growth factor (TGF)β-1, fibroblast specific protein (FSP)-1, anti-T15 autoantibody staining, and modest increases in 4-hydroxynonenal (4-HNE) Michael's adducts in lungs of OVA-sensitized mice. 4F decreased TGFβ-1, FSP-1, anti-T15 autoantibody, and 4-HNE adducts in the lungs of the OVA-sensitized mice. Eosinophil peroxidase (EPO) activity in bronchial alveolar lavage fluid (BALF), peripheral eosinophil counts, total IgE, and proinflammatory HDL (p-HDL) were all increased in OVA-sensitized mice. 4F decreased BALF EPO activity, eosinophil counts, total IgE, and p-HDL in these mice. These data indicate that 4F reduces pulmonary inflammation and airway resistance in an experimental murine model of asthma by decreasing oxidative stress.     

Mycoplasma pneumoniae infection increases airway collagen deposition in a murine model of allergic airway inflammation

Mycoplasma pneumoniae (Mp) has been linked to chronic asthma. Airway remodeling (e.g., airway collagen deposition or fibrosis) is one of the pathological features of chronic asthma. However, the effects of respiratory Mp infection on airway fibrosis in asthma remain unclear. In the present study, we hypothesized that respiratory Mp infection may increase the airway collagen deposition in a murine model of allergic airway inflammation in part through upregulation of transforming growth factor (TGF)-beta1. Double (2 wk apart) inoculations of Mp or saline (control) were given to mice with or without previous allergen (ovalbumin) challenges. On days 14 and 42 after the last Mp or saline, lung tissue and bronchoalveolar lavage (BAL) fluid were collected for analyses of collagen and TGF-beta1 at protein and mRNA levels. In allergen-na?ve mice, Mp did not alter airway wall collagen. In allergen-challenged mice, Mp infections did not change airway wall collagen deposition on day 14 but increased the airway collagen on day 42; this increase was accompanied by increased TGF-beta1 protein in the airway wall and reduced TGF-beta1 protein release from the lung tissue into BAL fluid. Our results suggest that Mp infections could modulate airway collagen deposition in a murine model of allergic airway inflammation with TGF-beta1 involved in the collagen deposition process.     

A role for decorin in a murine model of allergen-induced asthma

Decorin (Dcn) is an extracellular matrix proteoglycan, which affects airway mechanics, airway-parenchymal interdependence, airway smooth muscle proliferation and apoptosis, and transforming growth factor-β bioavailability. As Dcn deposition is differentially altered in asthma, we questioned whether Dcn deficiency would impact the development of allergen-induced asthma in a mouse model. Dcn(-/-) and Dcn(+/+) mice (C57Bl/6) were sensitized with ovalbumin (OA) and challenged intranasally 3 days/wk × 3 wk. After OA challenge, mice were anesthetized, and respiratory mechanics measured under baseline conditions and after delivery of increasing concentrations of methacholine aerosol. Complex impedance was partitioned into airway resistance and tissue elastance and damping. Bronchoalveolar lavage was performed. Lungs were excised, and tissue sections evaluated for inflammatory cell influx, α-smooth muscle actin, collagen, biglycan, and Dcn deposition. Changes in TH-2 cytokine mRNA and protein were also measured. Airway resistance was increased in OA-challenged Dcn(+/+) mice only (P < 0.05), whereas tissue elastance and damping were increased in both OA-challenged Dcn(+/+) and Dcn(-/-), but more so in Dcn(+/+) mice (P < 0.001). Inflammation and collagen staining within the airway wall were increased with OA in Dcn(+/+) only (P < 0.001 and P < 0.01, respectively, vs. saline). IL-5 and IL-13 mRNA were increased in lung tissue of OA-challenged Dcn(+/+) mice. Dcn deficiency resulted in more modest OA-induced hyperresponsiveness, evident at the level of the central airways and distal lung. Differences in physiology were accompanied by differences in inflammation and remodeling. These findings may be, in part, due to the well-described ability of Dcn to bind transforming growth factor-β and render it less bioavailable.     

Nonhematopoietic NADPH oxidase regulation of lung eosinophilia and airway hyperresponsiveness in experimentally induced asthma

Pulmonary eosinophilia is one of the most consistent hallmarks of asthma. Infiltration of eosinophils into the lung in experimental asthma is dependent on the adhesion molecule vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells. Ligation of VCAM-1 activates endothelial cell NADPH oxidase, which is required for VCAM-1-dependent leukocyte migration in vitro. To examine whether endothelial-derived NADPH oxidase modulates eosinophil recruitment in vivo, mice deficient in NADPH oxidase (CYBB mice) were irradiated and received wild-type hematopoietic cells to generate chimeric CYBB mice. In response to ovalbumin (OVA) challenge, the chimeric CYBB mice had increased numbers of eosinophils bound to the endothelium as well as reduced eosinophilia in the lung tissue and bronchoalveolar lavage. This occurred independent of changes in VCAM-1 expression, cytokine/chemokine levels (IL-5, IL-10, IL-13, IFNgamma, or eotaxin), or numbers of T cells, neutrophils, or mononuclear cells in the lavage fluids or lung tissue of OVA-challenged mice. Importantly, the OVA-challenged chimeric CYBB mice had reduced airway hyperresponsiveness (AHR). The AHR in OVA-challenged chimeric CYBB mice was restored by bypassing the endothelium with intratracheal administration of eosinophils. These data suggest that VCAM-1 induction of NADPH oxidase in the endothelium is necessary for the eosinophil recruitment during allergic inflammation. Moreover, these studies provide a basis for targeting VCAM-1-dependent signaling pathways in asthma therapies.     

Regulation of eosinophilopoiesis in a murine model of asthma

Eosinophilic inflammation plays a key role in tissue damage that characterizes asthma. Eosinophils are produced in bone marrow and recent observations in both mice and humans suggest that allergen exposure results in increased output of eosinophils from hemopoietic tissue in individuals with asthma. However, specific mechanisms that alter eosinophilopoiesis in this disease are poorly understood. The current study used a well-characterized murine animal model of asthma to evaluate alterations of eosinophil and eosinophil progenitor cells (CFU-eo) in mice during initial sensitization to allergen and to determine whether observed changes in either cell population were regulated by T lymphocytes. Following the first intranasal installation of OVA, we observed sequential temporal elevation of eosinophils in bone marrow, blood, and lung. In immunocompetent BALB/c mice, elevation of bone marrow eosinophils was accompanied by transient depletion of CFU-eo in that tissue. CFU-eo rebounded to elevated numbers before returning to normal baseline values following intranasal OVA exposure. In T cell-deficient BALB/c nude (BALB/c(nu/nu)) mice, CFU-eo were markedly elevated following allergen sensitization, in the absence of bone marrow or peripheral blood eosinophilia. These data suggest that eosinophilia of asthma results from alterations in two distinct hemopoietic regulatory mechanisms. Elevation of eosinophil progenitor cells in the bone marrow is T cell independent and likely results from altered bone marrow stromal cell function. Differentiation of eosinophil progenitor cells and phenotypic eosinophilia is T cell dependent and does not occur in athymic nude mice exposed to intranasal allergen.     

咪喹莫特对慢性哮喘模型小鼠肺组织中基质金属蛋白酶-9-表达的影响

目的：观察Toll样受体7配体咪喹莫特对慢性哮喘小鼠模型气道重塑及肺组织中基质金属蛋白酶MMP-9表达的影响。方法：36只BALB／c小鼠按随机原则分成正常对照组、哮喘模型组、咪喹莫特组,每组12只。通过卵蛋白致敏,气道激发8周,末次激发24h后,检测各组小鼠气道反应性,HE染色观察气道炎症变化;Masson三色染色观察气道纤维化的改变;real-timePCR和western—blot分别检测肺组织中MMP-9的mRNA和蛋白表达。结果：慢性哮喘组小鼠气道炎症、气道高反应性和气道重塑较正常对照小鼠明显加重,而咪喹莫特组小鼠模型的气道炎症和气道反应性及气道重塑均较哮喘模型组小鼠减少或降低。慢性哮喘组小鼠肺组织MMP-9的mRNA和蛋白水平均较正常对照小鼠明显增加（P〈0．05）,而咪喹莫特治疗可显著降低哮喘小鼠肺组织MMP-9的mRNA和蛋白水平（P〈0．05）。结论：咪喹莫特能够显著抑制慢性哮喘小鼠模型的气道炎症、降低气道高反应性并减轻气道重塑,这可能与其抑制MMP-9的表达有关。     

Hyaluronan deposition and correlation with inflammation in a murine ovalbumin model of asthma

Asthma is a chronic inflammatory disease of the airways characterized by airway remodeling, which includes changes in the extracellular matrix (ECM). However the role of the ECM in mediating these changes is poorly understood. Hyaluronan (HA), a major component of the ECM, has been implicated in asthma as well as in many other biological processes. Our study investigates the processes involved in HA synthesis, deposition, localization and degradation during an acute and chronic murine model of ovalbumin (OVA)-induced allergic pulmonary inflammation. Mice were sensitized, challenged to OVA and sacrificed at various time points during an 8-week challenge protocol. Bronchoalveolar lavage (BAL) fluids, blood, and lung tissue were collected for study. RNA, HA, protein and histopathology were analyzed. Analyses of lung sections and BAL fluids revealed an early deposition and an increase in HA levels within 24 h of antigen exposure. HA levels peaked at day 8 in BAL, while inflammatory cell recovery peaked at day 6. Hyaluronan synthase (HAS)1 and HAS2 on RNA levels peaked within 2 h of antigen exposure, while hyaluronidase (HYAL)1 and HYAL2 on RNA levels decreased. Both inflammatory cell infiltrates and collagen deposition co-localized with HA deposition within the lungs. These data support a role for HA in the pathogenesis of inflammation and airway remodeling in a murine model of asthma. HA deposition appears largely due to up regulation of HAS1 and HAS2. In addition, HA appears to provide the scaffolding for inflammatory cell accumulation as well as for new collagen synthesis and deposition.     

Antibody-antigen interaction in the airway drives early granulocyte recruitment through BLT1

Antibody-antigen interactions in the airway initiate inflammation in acute asthma exacerbations. This inflammatory response is characterized by the recruitment of granulocytes into the airways. In murine models of asthma, granulocyte recruitment into the lung contributes to the development of airway hyperresponsiveness (AHR), mucus production, and airway remodeling. Leukotriene B4 is a mediator released following antigen challenge that has chemotactic activity for granulocytes, mediated through its receptor, BLT1. We investigated the role of BLT1 in granulocyte recruitment following antigen challenge. Wild-type mice and BLT1-/- mice were sensitized and challenged with ovalbumin (OVA) to induce acute allergic airway inflammation. In addition, to explore the relevance to antibody-antigen interactions, we injected OVA bound to anti-OVA IgG1 or anti-OVA IgE intratracheally into na?ve wild-type and BLT1-/- mice. Cell composition of the lungs, cytokine levels, histology, and AHR were determined. After sensitization and challenge with ovalbumin, there was significantly reduced neutrophil and eosinophil recruitment into the airways of BLT1-/- mice compared with wild-type animals after one or two daily antigen challenges, but this difference was not seen after three or four daily antigen challenges. Mucus production and AHR were not affected. Intratracheal injection of OVA bound to IgG1 or IgE induced neutrophil recruitment into the airways in wild-type mice but not in the BLT1-/- mice. We conclude that BLT1 mediates early recruitment of granulocytes into the airway in response to antigen-antibody interactions in a murine model of acute asthma.     

Paeonol attenuates airway inflammation and hyperresponsiveness in a murine model of ovalbumin-induced asthma

Paeonol, the main active component isolated from Moutan Cortex, possesses extensive pharmacological activities such as anti-inflammatory, anti-allergic, and immunoregulatory effects. In the present study, we examined the effects of paeonol on airway inflammation and hyperresponsiveness in a mouse model of allergic asthma. BALB/c mice sensitized and challenged with ovalbumin were administered paeonol intragastrically at a dose of 100?mg/kg daily. Paeonol significantly suppressed ovalbumin-induced airway hyperresponsiveness to acetylcholine chloride. Paeonol administration significantly inhibited the total inflammatory cell and eosinophil count in bronchoalveolar lavage fluid. Treatment with paeonol significantly enhanced IFN-γ levels and decreased interleukin-4 and interleukin-13 levels in bronchoalveolar lavage fluid and total immunoglobulin E levels in serum. Histological examination of lung tissue demonstrated that paeonol significantly attenuated allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells in the airway. These data suggest that paeonol exhibits anti-inflammatory activity in allergic mice and may possess new therapeutic potential for the treatment of allergic bronchial asthma.     

Zinc Suppressed the Airway Inflammation in Asthmatic Rats: Effects of Zinc on Generation of Eotaxin, MCP-1, IL-8, IL-4, and IFN-γ

Airway epithelium is rich in labile zinc (Zn), which may have an important protective role in the airway epithelium. The aim of this study is to investigate the effects of Zn on the airway inflammation and the generation of eotaxin, monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), interleukin-4 (IL-4), and interferon-?? (IFN-??) in rat models of ovalbumin (OVA)-induced allergic airway inflammation. For this purpose, animal model of asthma was established by OVA challenge and zinc-deficient and zinc-supplemented diets were given. Thirty-two Sprague?CDawley rats were divided into four groups: zinc-deficient diet with OVA treatment group, zinc-supplemented diet with OVA treatment group, zinc-normal diet with OVA treatment group, and zinc-normal diet with saline treatment group. Twenty-four hours after asthma was induced, lung histomorphological changes, cells in bronchoalveolar lavage fluid (BALF), contents of eotaxin, MCP-1, and IL-8 in BALF, and the expression of IFN-?? and IL-4 mRNAs were observed. Compared with the group of zinc-normal diet with OVA challenge rats, the group of zinc-deficient rats had higher numbers of eosinophils, neutrophils, and monocytes in BALF, as well as higher contents of eotaxin and MCP-1 in BALF and lower expression of lung IFN-?? mRNA. Conversely, Zn supplementation would decrease the numbers of eosinophils, neutrophils, and monocytes in BALF; suppress eotaxin and MCP-1 protein secretion; and increase lung IFN-?? mRNA expression. No significant difference was observed in IL-8 and IL-4 among OVA-challenged rats with different zinc diets. These studies suggested that Zn may be an important anti-inflammatory mediator of airway inflammation.     

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

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