Effects of simulated downwind coal combustion emissions on pre-existing allergic airway responses in mice

Context: Coal-fired power plant emissions can contribute a significant portion of the ambient air pollution in many parts of the world.

Objective: We hypothesized that exposure to simulated downwind coal combustion emissions (SDCCE) may exacerbate pre-existing allergic airway responses.

Methods: Mice were sensitized and challenged with ovalbumin (OVA). Parallel groups were sham-sensitized with saline. Mice were exposed 6?h/day for 3 days to air (control, C) or SDCCE containing particulate matter (PM) at low (L; 100 μg/m³), medium (M; 300 μg/m³), or high (H; 1000 μg/m³) concentrations, or to the H level with PM removed by filtration (high-filtered, HF). Immediately after SDCCE exposure, mice received another OVA challenge (pre-OVA protocol). In a second (post-OVA) protocol, mice were similarly sensitized but only challenged to OVA before air/SDCCE. Measurement of airway hyperresponsiveness (AHR), bronchoalveolar lavage (BAL), and blood collection were performed ~24?h after the last exposure.

Results: SDCCE significantly increased BAL macrophages and eosinophils in OVA-sensitized mice from the post-OVA protocol. However, there was no effect of SDCCE on BAL macrophages or eosinophils in OVA-sensitized mice from the pre-OVA protocol. BAL neutrophils were elevated following SDCCE in both protocols in nonsensitized mice. These changes were not altered by filtering out the PM. In the post-OVA protocol, SDCCE decreased OVA-specific IgG₁ in OVA-sensitized mice but increased levels of total IgE, OVA-specific IgE and OVA-specific IgG₁ and IgG_2a in non-sensitized animals. In the pre-OVA protocol, SDCCE increased OVA-specific IgE in both sensitized and non-sensitized animals. Additionally, BAL IL-4, IL-13, and IFN-γ levels were elevated in sensitized mice.

Conclusion: These results suggest that acute exposure to either the particulate or gaseous phase of SDCCE can exacerbate various features of allergic airway responses depending on the timing of exposure in relation to allergen challenge.     

Effects of gasoline engine emissions on preexisting allergic airway responses in mice

Gasoline-powered vehicle emissions contribute significantly to ambient air pollution. We hypothesized that exposure to gasoline engine emissions (GEE) may exacerbate preexisting allergic airway responses. Male BALB/c mice were sensitized by injection with ovalbumin (OVA) and then received a 10-min aerosolized OVA challenge. Parallel groups were sham-sensitized with saline. Mice were exposed 6 h/day to air (control, C) or GEE containing particulate matter (PM) at low (L), medium (M), or high (H) concentrations, or to the H level with PM removed by filtration (high-filtered, HF). Immediately after GEE exposure mice received another 10-min aerosol OVA challenge (pre-OVA protocol). In a second (post-OVA) protocol, mice were similarly sensitized but only challenged to OVA before air or GEE exposure. Measurements of airway hyperresponsiveness (AHR), bronchoalveolar lavage (BAL), and blood collection were performed approximately 24 h after the last exposure. In both protocols, M, H, and HF GEE exposure significantly decreased BAL neutrophils from nonsensitized mice but had no significant effect on BAL cells from OVA-sensitized mice. In the pre-OVA protocol, GEE exposure increased OVA-specific IgG(1) but had no effect on BAL interleukin (IL)-2, IL-4, IL-13, or interferon (IFN)-gamma in OVA-sensitized mice. Nonsensitized GEE-exposed mice had increased OVA-specific IgG(2a), IgE, and IL-2, but decreased total IgE. In the post-OVA protocol, GEE exposure reduced BAL IL-4, IL-5, and IFN-gamma in nonsensitized mice but had no effect on sensitized mice. These results suggest acute exposure to the gas-vapor phase of GEE suppressed inflammatory cells and cytokines from nonsensitized mice but did not substantially exacerbate allergic responses.     

Effects of Gasoline Engine Emissions on Preexisting Allergic Airway Responses in Mice

Gasoline-powered vehicle emissions contribute significantly to ambient air pollution. We hypothesized that exposure to gasoline engine emissions (GEE) may exacerbate preexisting allergic airway responses. Male BALB/c mice were sensitized by injection with ovalbumin (OVA) and then received a 10-min aerosolized OVA challenge. Parallel groups were sham-sensitized with saline. Mice were exposed 6 h/day to air (control, C) or GEE containing particulate matter (PM) at low (L), medium (M), or high (H) concentrations, or to the H level with PM removed by filtration (high-filtered, HF). Immediately after GEE exposure mice received another 10-min aerosol OVA challenge (pre-OVA protocol). In a second (post-OVA) protocol, mice were similarly sensitized but only challenged to OVA before air or GEE exposure. Measurements of airway hyperresponsiveness (AHR), bronchoalveolar lavage (BAL), and blood collection were performed ～24 h after the last exposure. In both protocols, M, H, and HF GEE exposure significantly decreased BAL neutrophils from nonsensitized mice but had no significant effect on BAL cells from OVA-sensitized mice. In the pre-OVA protocol, GEE exposure increased OVA-specific IgG₁ but had no effect on BAL interleukin (IL)-2, IL-4, IL-13, or interferon (IFN)-γ in OVA-sensitized mice. Nonsensitized GEE-exposed mice had increased OVA-specific IgG_2a, IgE, and IL-2, but decreased total IgE. In the post-OVA protocol, GEE exposure reduced BAL IL-4, IL-5, and IFN-γ in nonsensitized mice but had no effect on sensitized mice. These results suggest acute exposure to the gas–vapor phase of GEE suppressed inflammatory cells and cytokines from nonsensitized mice but did not substantially exacerbate allergic responses.     

Trimellitic anhydride-induced eosinophilia in a mouse model of occupational asthma

Trimellitic anhydride (TMA) is a low-molecular-weight chemical known to cause occupational asthma. The present study was designed to determine if TMA elicited eosinophil infiltration into lungs of sensitized mice similar to previous studies with the protein allergen ovalbumin (OA). BALB/c mice were sensitized intradermally with 0.1 ml of 3% TMA or 0.3% OA in corn oil followed by intratracheal instillation with TMA conjugated to mouse serum albumin (TMA-MSA; 30 or 400 microg) or OA (30 microg). Nonsensitized mice received corn oil vehicle intradermally and MSA (30 microg) intratracheally. The allergic response was elicited 3 weeks later by intratracheal instillation of 30 or 400 microg TMA-MSA, OA, or control MSA. Cellular infiltration into bronchoalveolar lavage fluid (BAL) was determined 72 h later. Eosinophil peroxidase (EPO) and myeloperoxidase (MPO) activity in lung homogenates was used as an estimate of numbers of eosinophils and neutrophils, respectively, in lung tissue. In TMA-sensitized mice, TMA-MSA challenge significantly increased numbers of eosinophils in BAL and EPO in lung, indicating an increase in number of eosinophils in the airway and tissue. In nonsensitized mice, TMA-MSA challenge also caused a small but significant increase in eosinophils in BAL compared to MSA control. Total IgE in both plasma and BAL was significantly higher in TMA-sensitized compared to nonsensitized mice. The eosinophil infiltration in TMA-sensitized mice was similar in magnitude to the response in OA-sensitized mice. These studies are the first to demonstrate TMA-induced eosinophilia in mouse lung and to provide a model for comparing mechanisms and mediators responsible for the substantial eosinophilia induced by TMA and OA.     

Mepacrine alleviates airway hyperresponsiveness and airway inflammation in a mouse model of asthma

Asthma is a multifactorial respiratory disease. Though its incidence is increasing rapidly all over the world, the available therapeutic strategies are neither sufficient nor safe for long term use. Mepacrine, a known antimalarial drug, has been shown to possess antioxidant, anti-inflammatory, platelet anti-aggregant, and PLA2 inhibitory activities. However, its possible use in asthma has not been studied yet. The objective of this study was to investigate the anti-asthmatic property of mepacrine using a mouse model of asthma. To accomplish this, male BALB/c mice were sensitized and challenged with ovalbumin and treated with increasing concentrations of mepacrine. Airway hyperresponsiveness (AHR) to methacholine was assessed using unrestrained whole body plethysmography. Mepacrine (1 mg/kg) has shown marked attenuation of AHR. Cytokines such as IL-4, IL-5, IL-13 and IFN-gamma and OVA-specific IgE levels were measured in BAL (bronchoalveloar lavage) fluid and sera, respectively. Mepacrine effectively reduced the rise in IL-4, IL-5, IL-13, and OVA-specific IgE and restored IFN-gamma levels. Mepacrine also significantly prevented the increase of sPLA2 (secretory phospholipase A2) activity in BAL fluid supernatant and Cys-LT (cysteinyl leukotrienes) in lung tissue homogenates of asthmatic mice. In addition, mepacrine treatment reduced BAL fluid eosinophilia and signs of allergic airway inflammation such as perivascular and peribronchial distribution of inflammatory cells. These findings indicate that mepacrine reduces the asthmatic features in ovalbumin induced asthma by acting on PLA2-Cys-LT axis. Thus, it could be useful for the development of better asthma therapy.     

Anti-allergic activity of a Kampo (Japanese herbal) medicine "Sho-seiryu-to (Xiao-Qing-Long-Tang)" on airway inflammation in a mouse model

Effects of a Kampo (Japanese herbal) medicine "Sho-seiryu-to (SST, Xiao-Qing-Long-Tang in Chinese)", which has been used for the treatment of allergic bronchial asthma clinically, were examined on ovalbumin (OVA)-sensitized allergic airway inflammation model (i.e., bronchial asthma) in a mouse. When SST was orally administered at 0.5 g/kg/day from day 1 to 6 days after OVA inhalation, SST reduced the OVA-specific IgE antibody titer in bronchoalveolar lavage (BAL) fluids at 7 days after the OVA inhalation. CD4(+) T cells obtained from the mouse lung produced more interleukin (IL)-4 and IL-5 but less interferon (IFN)-gamma than T cells from nonsensitized control animals. However, oral administration of SST reduced the production of IL-4 and IL-5 and the production of IFN-gamma returned to the control level. In addition, the IL-4 level was increased in the BAL fluid of the OVA-sensitized animals compared to the nonsensitized control, while the IFN-gamma levels decreased. SST reduced the IL-4 levels in the BAL fluids and returned the IFN-gamma level to control levels. Nerve growth factor (NGF) was increased in the BAL fluids of the OVA-sensitized mice over that of nonsensitized mice, but oral administration of SST augmented the NGF levels to approximately 2 times higher than in the sensitized mice. Although lung cells obtained from sensitized mice produced higher levels of NGF than nonsensitized mice, oral administration of SST augmented the production of NGF by the lung cells even higher ( approximately 2 times more than cells from sensitized mice). Administration of anti-NGF antibody to the airway blocked the effects of SST. These results suggest that SST modulates Th1/Th2 balance in the lungs and augmentation of NGF in the lungs may be related to the effects of SST. Pinellic acid (9S, 12S, 13S-trihydroxy-10E-octadecenoic acid), one component of the herbs of SST [Int. Immunopharmacol. 2 (2002) 1183], was purified from the tuber of Pinellia ternata Breitenbach. Oral administration of pinellic acid (50 microg/kg/day) also reduced the OVA-specific IgE antibody titer in BAL fluids from the sensitized mouse. This result suggests that pinellic acid is one of active ingredient(s) in SST.     

Airway inflammation and adjuvant effect after repeated airborne exposures to di-(2-ethylhexyl)phthalate and ovalbumin in BALB/c mice

BACKGROUND: Epidemiological studies have suggested an association between exposure to phthalate plasticizers, including di-(2-ethylhexyl)phthalate (DEHP), and increased prevalence of asthma, rhinitis or wheezing. Furthermore, studies in mice have demonstrated an adjuvant effect from DEHP after parenteral administration with the model allergen ovalbumin (OVA). OBJECTIVE: Exposures to DEHP were investigated for adjuvant effects and airway inflammation in a mouse inhalation model. METHODS: BALB/cJ mice were exposed to aerosols of 0.022-13 mg/m(3) DEHP and 0.14 mg/m(3) OVA 5 days/week for 2 weeks and thereafter weekly for 12 weeks. Mice exposed to OVA alone or OVA+Al(OH)(3) served as control groups. Finally, all groups were exposed to a nebulized 1% OVA solution on three consecutive days. Serum, bronchoalveolar lavage (BAL) fluid, and draining lymph nodes were collected 24h later. RESULTS: In the OVA+Al(OH)(3) group, significantly increased levels of OVA-specific IgE and IgG1 in serum as well as of eosinophils in BAL fluid were observed. DEHP affected OVA-specific IgG1 production in a concentration-dependent manner, whereas little effect was seen on IgE and IgG2a. Dose-dependent increases in inflammatory cells were observed in BAL fluids, leading to significantly higher lymphocyte, neutrophil and eosinophil numbers in the OVA+13 mg/m(3) DEHP group. Ex vivo cytokine secretion by cultures of draining lymph nodes suggested that DEHP has a mixed Th1/Th2 cytokine profile. CONCLUSION: Airborne DEHP is able to increase serum IgG1 and lung inflammatory cell levels, but only at very high concentrations. Realistic DEHP levels do not have an adjuvant effect or induce allergic lung inflammation in the present mouse model.     

Anti-inflammatory effect of thymoquinone in a mouse model of allergic lung inflammation

Thymoquinone (TQ), the main active constituent of the volatile oil extracted from Nigella sativa's seeds, has been reported to have an anti-inflammatory and immune stimulatory effect on bronchial asthma and inflammation. However, little is known about the factors and mechanisms underlying these effects. In the present study, we examined the effect of TQ on airway inflammation in a mouse model of allergic asthma. Intraperitoneal injection of TQ before airway challenge of ovalbumin (OVA)-sensitized mice resulted in a marked decrease in lung eosinophilia and the elevated Th2 cytokines observed after airway challenge with OVA antigen; both in vivo, in the bronchoalveolar lavage (BAL) fluid and in vitro, following stimulation of lung cells with OVA. TQ also decreased the elevated serum levels of OVA-specific IgE and IgG1. Histological examination of lung tissue demonstrated that TQ significantly inhibited allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells. While TQ showed a significant effect in inhibiting IL-4, IL-5 and IL-13 and some effect in inducing IFN-gamma production in the BAL fluid, it did show a slight effect on in vitro production of IL-4 by cultured lung cells stimulated with OVA antigen. These data suggest that TQ attenuates allergic airway inflammation by inhibiting Th2 cytokines and eosinophil infiltration into the airways; thus demonstrating its potential anti-inflammatory role during the allergic response in the lung.     

Benzaldehyde suppresses murine allergic asthma and rhinitis

To evaluate the antiallergic effects of oral benzaldehyde in a murine model of allergic asthma and rhinitis, we divided 20 female BALB/c mice aged 8–10 weeks into nonallergic (intraperitoneally sensitized and intranasally challenged to normal saline), allergic (intraperitoneally sensitized and intranasally challenged to ovalbumin), and 200- and 400-mg/kg benzaldehyde (allergic but treated) groups. The number of nose-scratching events in 10 min, levels of total and ovalbumin-specific IgE in serum, differential counts of inflammatory cells in bronchoalveolar lavage (BAL) fluid, titers of Th2 cytokines (IL-4, IL-5, IL-13) in BAL fluid, histopathologic findings of lung and nasal tissues, and expressions of proteins involved in apoptosis (Bcl-2, Bax, caspase-3), inflammation (COX-2), antioxidation (extracellular SOD, HO-1), and hypoxia (HIF-1α, VEGF) in lung tissue were evaluated. The treated mice had significantly fewer nose-scratching events, less inflammatory cell infiltration in lung and nasal tissues, and lower HIF-1α and VEGF expressions in lung tissue than the allergic group. The number of eosinophils and neutrophils and Th2 cytokine titers in BAL fluid significantly decreased after the treatment (P < 0.05). These results imply that oral benzaldehyde exerts antiallergic effects in murine allergic asthma and rhinitis, possibly through inhibition of HIF-1α and VEGF.     

Para-Bromophenacyl bromide alleviates airway hyperresponsiveness and modulates cytokines, IgE and eosinophil levels in ovalbumin-sensitized and -challenged mice

Airway hyperresponsiveness, airway eosinophilia and increased IgE levels in serum are the important characteristic features of asthma. We evaluated the potential of para-Bromophenacyl bromide (PBPB), a known phospholipase A(2) inhibitor, on allergen-induced airway hyperresponsiveness in a mouse model. We sensitized and challenged mice with ovalbumin (OVA) to develop airway hyperresponsiveness as assessed by airway constriction and airway hyperreactivity (AHR) to methacholine (MCh) induced by allergen. The mice were orally treated with PBPB (0.1, 1 and 10 mg/kg) during or after OVA-sensitization and OVA-challenge to evaluate its protective or reversal effect on airway constriction and AHR to MCh. Determination of OVA-induced airway constriction and AHR to MCh were performed by measuring specific airway conductance (SGaw) using non-invasive dual-chamber whole body-plethysmography. We observed that PBPB (1 mg/kg) significantly reduced OVA-induced airway constriction and AHR to MCh (p<0.01). PBPB (1 mg/kg) treatment significantly inhibited PLA(2) activity in the BAL fluid. Cytokine analysis of the BAL fluid revealed that PBPB caused an increase in interferon-gamma (IFN-gamma) (p<0.02) and a decrease in interleukin-4 (IL-4) (p<0.05) and interleukin-5 (IL-5) (p<0.05) levels. The OVA-specific serum IgE levels (p<0.01) and the BAL eosinophils (p<0.001) were also reduced significantly. Thus, PBPB is capable of modulating allergen induced cytokine levels and serum IgE levels, and alleviating allergen induced airway hyperresponsiveness and eosinophils in mice. These data suggest that PBPB could be useful in the development of novel agents for the treatment of allergen induced airway hyperresponsiveness.     

Nitrogen dioxide: no influence on allergic sensitization in an intranasal mouse model with ovalbumin and diesel exhaust particles

The role of traffic-related air pollution in the development of allergic diseases is still unclear. We therefore investigated if NO?, an important constituent of traffic-related air pollution, promotes allergic sensitization to the allergen ovalbumin (OVA). We also examined if NO? influenced the allergy adjuvant activity of diesel exhaust particles (DEP). For this purpose, mice were exposed intranasally to OVA with or without DEP present, immediately followed by exposure to NO? (5 or 25 parts per million [ppm]) or room air for 4?h in whole body exposure chambers. Eighteen hours after the last of three exposures, the lungs of half of the animals were lavaged with saline and markers of lung damage and lung inflammation in the bronchoalveolar lavage fluid (BALF) were measured. Three weeks later, after intranasal booster immunizations with OVA, the levels of OVA-specific IgE and IgG2a antibodies in serum were determined. Both NO? (25 ppm) and DEP gave lung damage, measured as increased total protein concentration in BALF, whereas only NO? seemed to stimulate release of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). In contrast, only DEP significantly increased the number of neutrophils. Furthermore, DEP in combination with OVA stimulated the production of serum allergen-specific IgE antibodies. NO?, however, neither increased the production of allergen-specific IgE antibodies, nor influenced the IgE adjuvant activity of DEP. Thus, based on our findings, NO? seems to be of less importance than combustion particles in the development of allergic diseases after exposure to traffic-related air pollution.     

Evaluation of anti-allergic properties of caffeic acid phenethyl ester in a murine model of systemic anaphylaxis

Caffeic acid phenethyl ester (CAPE) is an active component of honeybee propolis extracts. It has several positive effects, including anti-inflammatory, anti-oxidation, anti-cancer, anti-bacterial, anti-viral, anti-fungal, and immunomodulatory effects. In particular, the suppressive effect of NF-kappaB may disrupt a component of allergic induction. The principal objective of this experimental study was to evaluate the effects of CAPE on the active systemic anaphylaxis induced by ovalbumin (OVA) challenge in mice. Mice were intraperitoneally sensitized and intravenously challenged with OVA. Histopathological analysis, nuclear factor (NF)-kappaB activation, and the plasma levels of histamine and total IgE after allergen challenge were evaluated. After challenges, all of the sham-treated mice developed anaphylactic symptoms, increased plasma levels of histamine and OVA-specific IgE, marked vascular leakage, NF-kappaB activation, platelet-activating factor (PAF) production, and histological changes including pulmonary edema and hemorrhage in the renal medullae within 20 min. By way of contrast, a reduction in the plasma levels of histamine and OVA-specific IgE and an inhibition of NF-kappaB activation and PAF release were observed in the CAPE-treated mice. In addition, a significant prevention of hemoconcentration and OVA-induced pathological changes were noted. These results indicate that CAPE demonstrates an anti-allergic effect, which may be the result of its protective effects against IgE-mediated allergy.     

Does lipophilicity per se induce adjuvant effects? Methyl palmitate as model substance does not affect ovalbumin sensitization

Anthopogenically introduced substances and pollutants are suspected to promote sensitization and development of allergic airway diseases, that is, acting as adjuvants. Lipophilicity may serve as an immunological warning signal, promoting adjuvant effects. Whether the lipophilicity of an inhaled compound induces immunomodulatory effects was investigated in a murine inhalation model with the highly lipophilic methyl palmitate (MP) as model substance. First, studies of acute effects following a 1-h exposure of up to 348 mg/m3 MP showed no effects on cell composition in bronchoalveolar lavage (BAL) or on lung function parameters. Thus, MP did not possess irritant or inflammatory properties, which may be a precursive stimulus for adjuvant effects. Second, mice were exposed to aerosols of MP, 6 or 323 mg/m3, for 1 h followed by a 20-min low-dose ovalbumin (OVA) inhalation. OVA only and OVA + Al(OH)3 served as control groups. Exposures were performed 5 times/wk for 2 wk followed by a weekly exposure for 10 wk. Finally, the mice were challenged with a high-dose OVA aerosol for 3 consecutive days. Neither OVA-specific immunoglobulin (Ig) G1, IgE, or IgG2a production, nor inflammatory cells in BAL, nor respiratory patterns were significantly affected in the MP groups. The OVA + Al(OH)3 group had a significantly higher IgG1 and IgE production, as well as higher eosinophil infiltration in the BAL fluid. These studies showed that effects of adjuvants not are necessarily due to their lipophilicity; that is, additional structural properties are required.     

Enhancement of the pulmonary allergic granulocyte recruitment in rats exposed to DMTI-II, a Kunitz-type inhibitor isolated from Dimorphandra mollis seeds

DMTI-II (23-kDa trypsin inhibitor purified from Dimorphandra mollis seeds) promotes acute inflammation accompanied by an early infiltration of eosinophils, a critical cell type involved in allergic diseases. We have evaluated here the capacity of DMTI-II to enhance the allergic pulmonary inflammation, looking over time to the leukocyte trafficking from bone marrow to peripheral blood, and their recruitment into the allergic airways. Male Wistar rats were sensitized and challenged with ovalbumin (OVA). At 2 to 16h prior to OVA challenge, animals were exposed to DMTI-II (10μg). Bronchoalveolar lavage fluid (BAL), circulating blood and bone marrow were examined at 24h post-OVA challenge. Challenge with OVA significantly increased the influx of total inflammatory cells, neutrophils and eosinophils in BAL and lung tissue. Pre-exposure to DMTI-II potentiated total inflammatory cell and neutrophil recruitment (p<0.05). Neutropoiesis and neutrophilia accompanied pulmonary cell influx. Pre-exposure to DMTI-II also significantly increased eosinophil recruitment to BAL, an effect starting at 4h, remaining markedly elevated at 16h (p<0.05). Eosinopoiesis and eosinophilia (seen within 2 to 4h) were also observed. Exposure to DMTI-II alone increased the IL-4 levels, and further increased the IL-4 levels in OVA-challenged rats. The levels of IgE, LTB(4) and eotaxin in OVA-challenged rats were greater compared with non-sensitized rats, but DMTI-II exposure failed to further enhance such levels. In summary, our study shows that DMTI-II itself presents granulocytopoietic activity, and enhances allergen-induced neutrophil and eosinophil mobilization from bone marrow to lung tissues that is accompanied by enhanced IL-4 production.     

Role of adenosine in airway inflammation in an allergic mouse model of asthma

In the present study, we examined dynamic changes in cellular profile of bronchoalveolar lavage (BAL) fluid after adenosine challenge in ragweed sensitized and challenged mice. Mice systemically sensitized and airway challenged with ragweed showed marked airway inflammation manifesting increased eosinophils, lymphocytes, neutrophils and activated macrophages in BAL. Adenosine challenge further enhanced influx of inflammatory cells into BAL, notably neutrophils from 1 to 72 h and eosinophils from 1 to 48 h time-points (p<0.05), which sharply rose at 6-h time-point following adenosine challenge. Greater infiltration of lymphocytes into BAL was observed at 1 and 72 h and macrophages from 6 to 72 h (p<0.05) after adenosine challenge. Accordingly, markers of eosinophils, neutrophils and mast cells were analyzed at 6-h time-point after adenosine challenge. Adenosine challenge significantly increased the levels of eosinophil peroxidase, neutrophil myeloperoxidase and beta-hexosaminidase in BAL. There were more significant effects of adenosine challenge on the degranulation of mast cells in the lung than that in blood. The chemoattractant, eotaxin, was detected in BAL, which increased after adenosine challenge. Theophylline, a non-specific adenosine receptor antagonist, prevented adenosine-enhanced infiltration of inflammatory cells and their respective markers. Our findings suggest that adenosine plays an important role in airway inflammation in an allergic mouse model.     

Pinocembrin attenuates allergic airway inflammation via inhibition of NF-κB pathway in mice

Pinocembrin, one of the primary flavonoids in propolis, possesses many biological activities, including anti-inflammation, anti-oxidation and immunoregulation. This study aimed to evaluate whether pinocembrin could attenuate ovalbumin (OVA)-induced allergic airway inflammation in mice and to explore the possible mechanism. BALB/c mice sensitized and challenged with OVA were administered intraperitoneally with pinocembrin. Airway inflammation and airway hyperresponsiveness were examined. T-helper type (Th) 2 cytokines in bronchoalveolar lavage fluid (BALF) and OVA-specific immunoglobulin E (IgE) in serum were determined. The activation of nuclear factor kappa B (NF-κB) p65 were also measured. Our results showed that pinocembrin resulted in significant inhibition of pathophysiological signs of allergic asthma, including increased pulmonary eosinophilia infiltration, mucus hypersecretion and airway hyperresponsiveness (AHR). Treatment with pinocembrin significantly reduced Th2 cytokines interleukin (IL)-4, IL-5 and IL-13 in BALF, and OVA-specific IgE in serum. Moreover, pinocembrin treatment suppressed phosphorylation of inhibitor-κBα (IκBα) and NF-κB subunit p65 activation in lung tissue of OVA-sensitized mice. These data suggest that pinocembrin may inhibit allergic airway inflammation, and providing potential benefits in the treatment of inflammatory disease.     

Comparison of respiratory responses to Metarhizium anisopliae extract using two different sensitization protocols

Metarhizium anisopliae, an entomopathogenic fungus, is a prototypic microbial pesticide licensed for indoor control of cockroaches, a major source of allergens. We have previously demonstrated allergy and asthma-like responses in BALB/c mice intraperitoneally (IP) sensitized in the presence of adjuvant and intratracheally (IT) challenged with the soluble factors from M. anisopliae crude antigen (MACA) (Ward et al., 1998, 2000). This protocol has been used frequently to establish animal models of allergenicity. However, the sensitization protocol is artificial and not representative of an environmental exposure. Concern has been raised that this protocol might produce allergic responses that would not occur under normal environmental exposure conditions. The objective of this study was to compare responses in mice to MACA by two exposure protocols: (1) exclusive respiratory exposures without adjuvant (representative of environmental exposures) and (2) intraperitoneal sensitization in the presence of adjuvant followed by IT challenge (the traditional approach). The intratracheal protocol consisted of four IT exposures of 10 microg MACA in 50 microl HBSS each over a 4-week period. A vehicle control group of mice was exposed IT to HBSS. The intraperitoneal protocol consisted of IP sensitization with 25 microg MACA in 0.2 ml of 1.3% alhydrogel (aluminum hydroxide) followed 14 days later with an IT challenge (10 microg MACA/50 microl HBSS). Airway reactivity responsiveness to methacholine was assessed, serum and bronchoalveolar lavage fluid (BALF) samples were obtained, and the lungs were fixed for histopathology at 1, 3, and 8 days following the last MACA IT challenge. Both groups exhibited immune and pulmonary responses typical of allergic asthma. In general, local responses in the lung, including inflammatory responses (eosinophils, lymphocytes, and macrophages), BALF IgE, and functional responses to methacholine were greater in the IT sensitized group compared to the IP sensitized group, whereas the systemic IgE response was greater in the IP sensitized group. The BALF IL-5 cytokine levels were elevated before and throughout the eosinophil influx. IL-4 was detected in the BALF of IP sensitized, but not IT sensitized mice. Histopathologic changes in the two groups were similar in nature but more severe in the IT mice. The results suggest that the IP sensitization protocol does not induce the level of respiratory responsiveness that results from sensitization by a physiologically relevant route of exposure. Thus total serum IgE levels, which were greater following IP sensitization, may not be the best indicator of allergen potency, at least with respect to respiratory responses.     

Anti-asthmatic effect of marine red alga (Laurencia undulata) polyphenolic extracts in a murine model of asthma

The aim of the present work is focused on protective effects of an edible red alga, Laurencia undulata ethanolic (EtOH) extracts (LU) containing a large amount of polyphenols against OVA-induced murine allergic airway reactions using in vivo histological and cytokine assay. Mice sensitized and challenged with ovalbumin (OVA) showed typical asthmatic reactions as follows: an increase in the number of eosinophil in bronchoalveolar lavage fluid; a marked influx of inflammatory cells into the lung around blood vessels and airways, and airway luminal narrowing; the development of airway hyperresponsiveness; the detection of TNF-α and Th2 cytokines, such as IL-4 and IL-5 in the bronchoalveolar lavage (BAL) fluid; and detection of allergen-specific IgE in the serum. The successive intraperitoneal administration of LU before the last airway OVA-challenge resulted in a significant inhibition of all asthmatic reactions. These results suggest that L. undulata polyphenolic extracts possess therapeutic potential for combating bronchial asthma associated with allergic diseases.