Role of IL-5 in the development of allergen-induced airway hyperresponsiveness

Evaluation serum levels of YKL-40, Periostin, and some inflammatory cytokines together with IL-37, a new anti-inflammatory cytokine, in patients with stable and exacerbated asthma

INTRODUCTION

As asthma has a wide range of inflammatory pathways, the researchers were focused on the markers that may be associated with exacerbation and stability in asthma.

OBJECTIVE

Our aim is to investigate the serum levels of some inflammatory markers and cytokines in stable and exacerbated asthmatic patients.

METHODS

The study included in 59 non-smoker asthma patient (Exacerbated=25, Stable=34) and 30 healthy volunteers. The serum level of periostin, YKL-40, IL-4, IL-5, IL-37, and TNF-α were detected by enzyme-linked immunosorbent assay.

RESULTS

Except for IL-37, the periostin, YKL-40, IL-4, IL-5, and TNF-α level in asthmatic patients were significantly higher than those of healthy control. In the exacerbated group, the periostin, YKL-40, IL-5, and TNF-α level were significantly higher than stable asthma and healthy control groups. The serum levels of IL-4 in exacerbated and stable asthma groups were significantly higher than healthy control group. There was a significant difference between IL4 levels, in stable asthma and healthy control groups. In exacerbated asthma group, IL-37 level was significantly lower than stable and healthy control groups. The highest area under the ROC curve (AUC) was found for IL-4. While there was a significant negative correlation between these parameters and FEV1, there was a positive correlation between IL-37 and FEV1, but not significant.

CONCLUSIONS

This study showed that increased serum periostin, YKL-40, IL-5, IL-4, and TNF-α and decreased serum IL-37 were associated with exacerbation showing uncontrolled asthma.

Sex-dependent responses to exertional heat stroke in mice

With increasing participation of females in endurance athletics and active military service, it is important to determine if there are inherent sex-dependent susceptibilities to exertional heat injury or heat stroke. In this study we compared responses of male and female adult mice to exertional heat stroke (EHS). All mice were instrumented for telemetry core temperature measurements and were exercise-trained for 3 wk before EHS. During EHS, environmental temperature was 37.5°C (35% RH) while the mice ran on a forced running wheel, using incremental increases in speed. The symptom-limited endpoint was loss of consciousness, occurring at ~42.2°C core temperature. Females ran greater distances (623 vs. 346 m, P < 0.0001), reached faster running speeds (7.2 vs. 5.1 m/min, P < 0.0001), exercised for longer times (177 vs. 124 min, P < 0.0001), and were exposed to greater internal heat loads (240 vs.160°C·min; P < 0.0001). Minimum Tc during hypothermic recovery was ~32.0°C in both sexes. Females lost 9.2% body weight vs. 7.5% in males ( P < 0.001). Females demonstrated higher circulating corticosterone (286 vs 183 ng/ml, P = 0.001, at 3 h), but most plasma cytokines were not different. A component of performance in females could be attributed to greater body surface area/mass and greater external power performance. However, there were significant and independent effects of sex alone and a crossed effect of "sex × power" on performance. These results demonstrate that female mice have greater resistance to EHS during exercise in hyperthermia and that these effects cannot be attributed solely to body size. NEW & NOTEWORTHY Female mice are surprisingly more resistant to exertional heat stroke than male mice. They run faster and longer and can withstand greater internal heat loads. These changes cannot be fully accounted for by increased body surface/mass ratio in females or on differences in aerobic performance. Although the stress-immune response in males and females was similar, females exhibited markedly higher plasma corticosteroid levels, which were sustained over 14 days of recovery.

Frontline Science: Coincidental null mutation of Csf2rα in a colony of PI3Kγ-/- mice causes alveolar macrophage deficiency and fatal respiratory viral infection

PI3Ks have been identified as key signaling proteins involved in many basic biologic processes in health and disease. Transgenic animals have been essential tools to study the underlying molecular mechanisms in this context and therefore, have been widely used to elucidate the role of these factors in many different settings. More specifically, PI3Kγ, a subunit highly expressed in the hematopoietic system, has been implicated to play an important role in many inflammatory diseases as well as cancer. Here, we report identification of multiple, additional, previously unknown mutations in the genome of a widely used PI3Kγ-deficient (PI3Kγ^-/-) mouse colony. These include a STOP mutation in the GM-CSFRα chain, leading to a complete and specific deficiency in GM-CSF signaling. PI3Kγ^-/- animals consequently lacked alveolar macrophages (AMs) and succumbed rapidly to influenza virus infection. Furthermore, PI3Kγ^-/- mice carried an additional mutation that affects mucin 2 (Muc2) transcripts. This protein is strongly involved in the regulation of colorectal cancer, and indeed, conflicting reports have indicated that PI3Kγ^-/- animals spontaneously develop colorectal tumors. Thus, we uncover previously unknown, confounding factors present in a strain of PI3Kγ^-/- mice, leading to additional deficiencies in important signaling pathways with potentially wide-ranging implications for the interpretation of previous studies. By separating the mutations, we established a unique Csf2ra^-/- mouse model that allows us to study the role of cell intrinsic GM-CSFR signaling in vivo without confounding variables introduced by defective IL-5R and IL-3R signaling in mice lacking the common β chain (Csf2rb).

Eosinophils contribute to the resolution of lung-allergic responses following repeated allergen challenge

BACKGROUND

Eosinophils accumulate at the site of allergic inflammation and are critical effector cells in allergic diseases. Recent studies have also suggested a role for eosinophils in the resolution of inflammation.

OBJECTIVE

To determine the role of eosinophils in the resolution phase of the response to repeated allergen challenge.

METHODS

Eosinophil-deficient (PHIL) and wild-type (WT) littermates were sensitized and challenged to ovalbumin (OVA) 7 or 11 times. Airway inflammation, airway hyperresponsiveness (AHR) to inhaled methacholine, bronchoalveolar lavage (BAL) cytokine levels, and lung histology were monitored. Intracellular cytokine levels in BAL leukocytes were analyzed by flow cytometry. Groups of OVA-sensitized PHIL mice received bone marrow from WT or IL-10(-/-) donors 30 days before the OVA challenge.

RESULTS

PHIL and WT mice developed similar levels of AHR and numbers of leukocytes and cytokine levels in BAL fluid after OVA sensitization and 7 airway challenges; no eosinophils were detected in the PHIL mice. Unlike WT mice, sensitized PHIL mice maintained AHR, lung inflammation, and increased levels of IL-4, IL-5, and IL-13 in BAL fluid after 11 challenges whereas IL-10 and TGF-β levels were decreased. Restoration of eosinophil numbers after injection of bone marrow from WT but not IL-10-deficient mice restored levels of IL-10 and TGF-β in BAL fluid as well as suppressed AHR and inflammation. Intracellular staining of BAL leukocytes revealed the capacity of eosinophils to produce IL-10.

CONCLUSIONS

After repeated allergen challenge, eosinophils appeared not essential for the development of AHR and lung inflammation but contributed to the resolution of AHR and inflammation by producing IL-10.

Midazolam inhibits IgE production in mice via suppression of class switch recombination

Anaphylactic shock is characterized by increased capillary permeability and a decline in blood pressure due to excessive production of IgE. Midazolam (MDZ) is reported to have immunomodulatory properties. However, little is known about the effect of MDZ on the production of IgE antibody. We examined whether MDZ can suppress antigen-specific and total IgE production followed by IgE class switch recombination (CSR). MDZ was administered intraperitoneally to mice prior to ovalbumin (OVA) plus native cholera toxin (nCT) immunization. Serum OVA-specific and total IgE responses, and surface IgE-positive B cells were analyzed by ELISA and flow cytometry. Furthermore, expression levels of CSR-associated molecules such as germ-line transcript ε (εGLT), germ-circle tanscript ε (εCT), AID, and Id2 in the spleen were compared. The levels of interferon-gamma (IFN-γ) and interleukin (IL)-4 mRNA and protein were also examined in the spleen and serum. MDZ significantly suppressed OVA-specific and total IgE levels in plasma and surface IgE-positive B cells in the spleen. Moreover, MDZ-treated mice had significantly reduced levels of εGLT and εCT. Furthermore, although the levels of IFN-γ mRNA and protein were significantly elevated, those of IL-4 were reduced in MDZ-treated mice. Therefore, MDZ may be an important modulator of allergic responses through its ability to downregulate IgE production.

Tripterygium polyglycosid attenuates the established airway inflammation in asthmatic mice

OBJECTIVE

To investigate the effect of Tripterygium polyglycosid on establishing airway eosinophil infiltration and related airway hyperresponsiveness of asthmatic mice.

METHODS

A mature murine asthmatic model was made with ovabulmin sensitized and challenged C57BL/6 mice. Forty mice were divided into four groups with 10 mice in each group: mice sensitized and challenged with saline (WS group), mice sensitized and challenged with ovalbumin (WO group), mice sensitized and challenged with ovalbumin and treated with Tripterygium polyglycosid (TP group) and Dexamethasone (DXM group). The mice were intraperitoneally injected with 20 μg chicken ovabulmin emulsified in injected alum on days 0 and 14, then were challenged with an aerosol generated from 1% ovabulmin on days 24, 25 and 26. Tripterygium polyglycosid was injected intraperitoneally at 50 mg/kg on days 25, 26 and 27 after ovabulmin challenge. Dexamethasone was administrated to mice at 2 mg/kg on day 21, 23 before ovabulmin challenge. The airway hyperresponsiveness, mucus production, eosinophils in parabronchial area and bronchoalveolar lavage fluid and the level of interleukin-5, granulo-macrophage clone stimulating factor in bronchoalveolar lavage fluid were measured as indexes of inflammation.

RESULTS

Tripterygium polyglycosid treatment after ovabulmin challenge completely inhibited eosinophil infiltration in bronchoalveolar lavage fluid [(0.63 ± 0.34)× 10(4) vs. (75.0 ± 14.8)× 10(4), P<0.05] and the peribrochial area (12.60 ± 3.48 mm(2) vs. 379.0 ± 119.3 mm(2), P<0.05), mucus overproduction in airway (2.8 ± 1.7 vs. 7.1±5.6, P<0.05), and increased interleukin-5 levels in bronchoalveolar lavage fluid (28.8 ± 2.8 pg/mL vs. 7.5 ± 3.5 pg/mL, P<0.05). Meanwhile, Tripterygium polyglycosid treatment after ovabulmin challenge also partially inhibited airway hyperresponsiveness. The level of granulo-macrophage clone stimulating factor in bronchoalveolar lavage fluid didn't change with drugs intervention.

CONCLUSIONS

The administration of Tripterygium polyglycosid could inhibit the established airway inflammation and reduce the airway hyperresponsiveness of allergic asthmatic mice. It provides a possible alternative therapeutic for asthma.

Molecular and clinical rationale for therapeutic targeting of interleukin-5 and its receptor

Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts in conformationally dynamic ways with the receptor's βc subunit, an aggregate of domains it shares with binding sites of IL-3 and granulocyte-macrophage colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. Although corticosteroid therapy is the primary treatment for these diseases, a substantial number of patients exhibit incomplete responses and suffer side-effects. Two monoclonal antibodies have been designed to neutralize IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability to reduce blood and tissue eosinophil counts. One additional monoclonal antibody, benralizumab (MEDI-563), has been developed to target IL-5R and attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All three monoclonal antibodies are being clinically evaluated. Antisense oligonucleotide technology targeting the common βc IL-5R subunit is also being used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small interfering RNA technology has also been used therapeutically to inhibit the expression of IL-5 in animal models. This review summarizes the structural interactions between IL-5 and IL-5R and the functional consequences of such interactions, and describes the pre-clinical and clinical evidence supporting IL-5R as a therapeutic target.

Thalidomide attenuates airway hyperresponsiveness and eosinophilic inflammation in a murine model of allergic asthma

Asthma is characterized by chronic eosinophilic inflammation and hyperresponsiveness of the airways. We hypothesized that thalidomide, which has numerous immunomodulatory properties, may have anti-inflammatory effects in allergic asthma. BALB/c mice sensitized and challenged with ovalbumin (OVA) were treated orally with thalidomide (30, 100, or 300 mg/kg) or a vehicle. When thalidomide was administered to OVA-challenged mice, the number of eosinophils in bronchoalveolar lavage fluid (BALF) was significantly decreased. The numbers of inflammatory cells other than eosinophils were not reduced by thalidomide. Thalidomide inhibited the elevated levels of interleukin-5 (IL-5) and tumor necrosis factor-alpha (TNF-alpha) in BALF by OVA challenges. Histological analysis of the lung revealed that both the infiltration of inflammatory cells and the hyperplasia of goblet cells were significantly suppressed by thalidomide treatment. Furthermore, thalidomide significantly inhibited the response to methacholine induced by OVA challenges. Taken together, thalidomide treatment decreased airway inflammation and hyperresponsiveness in a murine model of allergic asthma. These results might provide an opportunity for the development of novel therapeutics to treat severe asthma.

Suppression of type-I allergic responses by oral administration of grape marc fermented with Lactobacillus plantarum

We investigated the inhibitory effects of fermented grape marc (FGM), lyophilized fine powder of skin, and seeds of Vitis vinifera Koshu grape prepared by fermentation with Lactobacillus plantarum, on type-I allergic responses in mice. Repeated oral administration of FGM, but not non-fermented grape marc (GM), to BALB/c mice primed with ovalbumin (OVA) resulted in a significant reduction of serum IgE levels, compared with those of immunized controls. After OVA challenge, increased numbers of eosinophils in bronchial alveolar lavage fluids (BALF) significantly decreased by treatment with FGM but not with GM. For passive cutaneous anaphylaxis (PCA) reaction, BALB/c mice received intradermal sensitization with anti-OVA IgE serum and were challenged intravenously with OVA containing Evans blue at 24 h after IgE sensitization. Oral administration of FGM at 30 min before OVA challenge significantly suppressed the PCA reaction. On the other hand, Lactobacillus alone and non-fermented GM did not show any suppressive effects. Interestingly, FGM samples prepared from grapes for red wine, such as Negroamaro (rich in resveratrol) or Tannat (rich in oligomeric procyanidin), did not suppress the reaction. These results indicate that oral administration of FGM, prepared from Koshu grape for white wine but not from grapes for red wine, could suppress both phases of type-I allergic responses. A fraction extractable with acetone was responsible for the suppressive effects of FGM.

Effects of Enterococcus sp. isolated from deep seawater on inhibition of allergic responses in mice

The objective of the present study was to assess the effects of Enterococcus sp. strain TN-3 isolated from deep seawater on inhibition of eosinophil accumulation, IgE production and active cutaneous anaphylaxis (ACA). We investigated the effects of viable and non-viable TN-3 on allergen-induced peritoneal eosinophil accumulation in mice. Viable (5.4 x 1010 colony-forming units per 60 mg) or non-viable TN-3 (60 mg) was orally administered to BALB/c mice that had been sensitised with the cedar pollen (Cryptomeria japonica) allergen. Oral administration of non-viable TN-3 was effective in suppressing eosinophil accumulation while viable TN-3 was ineffective. We also examined the dose-response relationship for non-viable TN-3 in regard to eosinophil accumulation, IgE production and ACA in allergen-primed mice. Non-viable TN-3 was orally administered at doses of 15 mg (low dose), 30 mg (medium dose) and 60 mg (high dose) to BALB/c mice that had been sensitised with cedar pollen allergen. The anti-allergic effects expressed as inhibition of eosinophil accumulation, IgE production and ACA were found at the low and high doses, but not at the medium dose. These results suggest that non-viable TN-3 exhibited anti-allergic effects at doses of 15 and 60 mg.

Mechanisms of allergy and asthma

Allergies are the result of an inappropriate reaction against innocuous environmental proteins. The prevalence and severity of allergic diseases has increased dramatically during the last decade in developed countries. Allergen-specific T helper (Th) cells play a pivotal role in the pathogenesis of allergic hypersensitivity reactions. These Th cells activate a complex immune reaction that triggers the release of potent mediators and enhances the recruitment of inflammatory cells, which in turn elicit an inflammatory response that leads to the clinical symptoms of allergic disease. The current therapies for allergic diseases focus primarily on control of symptoms and suppression of inflammation, without affecting the underlying cause. However, the knowledge about the pathophysiology of allergic diseases has substantially increased, offering new opportunities for therapeutic intervention. In this review, we will focus on current insights into the mechanism of allergic reactions.

Heat-killed cells of lactobacilli skew the immune response toward T helper 1 polarization in mouse splenocytes and dendritic cell-treated T cells

It is believed that probiotics play an important role for the health of the host, including modulation of immune responses. Most studies have focused on the immunomodulatory effects of viable cells of lactic acid bacteria; however, we investigated those of heat-killed cells of lactic acid bacteria in this study. We first observed the effects on immune functions via stimulating splenocytes with three heat-killed Lactobacillus strains. Furthermore, we also investigated the effect of mouse dendritic cells (DCs) treated with these heat-killed Lactobacillus strains on T cell responses. The results showed that these Lactobacillus strains were able to stimulate cell proliferation and interleukin (IL)-10, IL-12 p70, and interferon (IFN)-gamma production but not transforming growth factor (TGF)-beta in splenocytes. In addition, these heat-killed Lactobacillus strains also stimulated high-level secretion of IL-12 p70 in DCs and switched T cells to T helper (Th) 1 immune responses, as evidenced by the elevated secretion of IFN-gamma but not IL-5, IL-13, and TGF-beta. These results showed that lactobacilli play a potentially important role in modulating immune responses and allergic reactions.

The role of Alkoxy group on the a ring of isoflavones in the inhibition of Interleukin-5

Novel isoflavones were found to be potent inhibitors of interleukin-5 (Il-5). 5-Benzyloxy-3-(4-hydroxyphenyl)-4H-chromen-4-one (2a, 87.8% inhibition at 50 microM, IC50 = 15.3 microM) was initially identified as a potent inhibitor of IL-5. Its activity was comparable to that of budesonide or sophoricoside (1a). The benzyloxy group appeared to be critical for the enhancement of the IL-5 inhibitory activity. To identify the role of this hydrophobic moiety, 5-cyclohexylmethoxy (2d), 7-cyclohexylmethoxy (2e), 5-cyclohexylethoxy (2f), 5-cyclohexylpropoxy (2g), 5-(2-methylpropoxy) (2h), 5-(3-methylbutoxy) (2i), 5-(4-methylpentoxy) (2j) and 5-(2-ethylbutoxy) (2k) analogs were prepared and tested for their effects on the bioactivity of IL-5. Compounds 2d (IC50 = 5.8 microM), 2e (IC50 = 4.0 microM) and 2j (IC50 = 7.2 microM) exhibited the most potent activities. Considering the cLog P values of compounds 2 and the different three dimensional structures of 2d and 2e, the alkoxy group on ring A contributed to their cell permeability for the enhancement of activity, rather than playing a role in the ligand motif binding to the receptor. The optimum alkoxy group should be one that provides cLog P values of compounds 2 in the range of 4.13 to 4.39.

Antiallergic effect of milk fermented with lactic acid bacteria in a murine animal model

The objective of this study was to assess the antiallergic effect of fermented milk prepared, respectively, with Streptococcus thermophilus MC, Lactobacillus acidophilus B, Lactobacillus bulgaricus Lb, L. bulgaricus 448, and Bifidobacterium longum B6. Female BALB/c mice fed fermented milk were immunized intraperitoneally with ovalbumin (OVA)/complete Freund's adjuvant (CFA) to evaluate the immune response by observing the secretion of cytokines IL-2, IL-4, and IFN-gamma and serum antibody IgE. The results showed that supplementation with lactic acid bacteria fermented milk did not significantly change the IL-2 spontaneous and OVA-stimulated secretions of splenocytes. However, both spontaneous and OVA-stimulated secretions of splenocytes from mice fed lactic acid bacteria fermented milk showed significantly (P < 0.05) lower levels of IL-4 (Th2 cytokine) than those from OVA/CFA-immunized mice fed non-fermented milk (OVA/CFA-milk group). The spontaneous secretion of IFN-gamma (Th1 cytokine) by splenocytes from mice fed L. bulgaricus 448 or L. bulgaricus Lb fermented milk significantly increased as compared to that from the OVA/CFA-milk group. The results showed that the ratios of IFN-gamma to IL-4 of both spontaneous and OVA-stimulated secretions in splenocytes from mice fed lactic acid bacteria fermented milk increased significantly as compared to that of PBS- or OVA/CFA-milk groups. The serum levels of OVA-specific IgE in fermented milk fed groups, especially the group fed S. thermophilus MC fermented milk, were significantly lower than those in the OVA/CFA-milk group through a 6 week feeding experiment. The results showed that milk fermented with lactic acid bacteria demonstrated in vivo antiallergic effects on OVA/CFA-immunized mice via increasing the secretion ratio of IFN-gamma/IL-4 (Th1/Th2) by splenocytes and decreasing the serum level of OVA-specific IgE.

The role of the hydrophobic group on ring A of chalcones in the inhibition of interleukin-5

Novel chalcones were found as potent inhibitors of interleukin-5 (11-5). 1-(6-Benzyloxy-2-hydroxyphenyl)-3-(4-hydroxyphenyl)propenone (2a, 78.8% inhibition at 50 microM, IC50 = 25.3 microM) was initially identified as a potent inhibitor of IL-5. This activity is comparable to that of budesonide or sophoricoside (1a). The benzyloxy group appears to be critical for the enhancement of the IL-5 inhibitory activity. To identify the role of this hydrophobic moiety, cyclohexyloxy (2d), cyclohexylmethoxy (2c), cyclohexylethoxy (2e), cyclohexylpropoxy (2f), 2-methylpropoxy (2g), 3-methylbutoxy (2h), 4-methylpentoxy (2i), and 2-ethylbutoxy (2j) analogs were prepared and tested for their effects on IL-5 bioactivity. Compounds 2c (IC50 = 12.6 microM), 2d (IC50 = 12.2 microM), and 2i (IC50 = 12.3 microM) exhibited the most potent activity. Considering the cLog P values of 2, the alkoxy group contributes to the cell permeability of 2 for the enhancement of activity, rather than playing a role in ligand motif binding to the receptor. The optimum alkoxy group in ring A of 2 should be one that provides the cLog P of 2 in the range of 4.22 to 4.67.

Allergen-Induced Airway Hyperresponsiveness Mediated by Cyclooxygenase Inhibition Is Not Dependent on 5-Lipoxygenase or IL-5, but Is IL-13 Dependent

Cyclooxygenase (COX) inhibition during allergic sensitization and allergen airway challenge results in augmented allergic inflammation. We hypothesized that this increase in allergic inflammation was dependent on increased generation of leukotrienes that results from COX inhibition, as leukotrienes are important proinflammatory mediators of allergic disease. To test this hypothesis, we allergically sensitized and challenged mice deficient in 5-lipoxygenase (5-LO). We found that 5-LO knockout mice that were treated with a COX inhibitor during allergic sensitization and challenge had significantly increased airway hyperresponsiveness (AHR) (p < 0.01) and airway eosinophilia (p < 0.01) compared with 5-LO knockout mice that were treated with vehicle. The proinflammatory cytokines have also been hypothesized to be critical regulators of airway inflammation and AHR. We found that the increase in airway eosinophilia seen with COX inhibition is dependent on IL-5, whereas the increase in AHR is not dependent on this cytokine. In contrast, the COX inhibition-mediated increase in AHR is dependent on IL-13, but airway eosinophilia is not. These results elucidate the pathways by which COX inhibition exerts a critical effect of the pulmonary allergen-induced inflammatory response and confirm that COX products are important regulators of allergic inflammation.

Adding salmeterol to an inhaled corticosteroid reduces allergen-induced serum IL-5 and peripheral blood eosinophils

BACKGROUND

Adding a long-acting beta(2)-agonist to inhaled corticosteroids results in better symptomatic asthma control than increasing the dose of inhaled corticosteroids.

OBJECTIVE

Investigating whether adding the long-acting beta(2)-agonist salmeterol to the inhaled corticosteroid fluticasone propionate has an effect on allergen-induced allergic inflammation in asthma.

METHODS

Bronchial allergen challenges were performed in 26 patients with allergic asthma, pretreating them with a single dose of either fluticasone/salmeterol (100/50 microg) or fluticasone alone (100 microg), in a double-blind, randomized, cross-over design. Sputum and serum markers of bronchial inflammation were measured after allergen challenge, as well as lung function parameters. Primary outcomes were sputum eosinophil numbers and eosinophil cationic protein.

RESULTS

Asthmatic responses after allergen challenge were significantly reduced after pretreatment with fluticasone/salmeterol relative to fluticasone alone. Sputum inflammatory markers after allergen challenge were not significantly affected by fluticasone/salmeterol pretreatment. By contrast, serum IL-5 was significantly reduced (geometric mean serum IL-5 [SEM]: 0.5 [0.3] vs 1.1 [0.3] pg/mL 1 hour and 0.6 [0.3] vs 1.1 [0.3] pg/mL 6 hours after challenge with fluticasone/salmeterol vs fluticasone alone pretreatment, respectively; P values < .05). Also, peripheral blood eosinophils were significantly reduced (geometric mean number x 10(6)/L [SEM]: 172 [0.1] vs 237 [0.1] at 6 hours and 271 [0.1] vs 351 [0.1] at 24 hours with fluticasone/salmeterol vs fluticasone alone pretreatment, respectively; P < .05).

CONCLUSION

Adding salmeterol to fluticasone reduces allergen-induced serum IL-5 and peripheral blood eosinophils. This phenomenon may contribute to the improved clinical outcomes that result from adding a long-acting beta(2)-agonist to inhaled corticosteroids.

Serum interleukin-5 measurements for monitoring acute asthma in children

Cytokine-mediated interactions among the inflammatory cells may play a role in the pathogenesis of bronchial asthma. Interleukin-5 (IL-5) is a major cytokine in the recruitment of neutrophils to the area of inflammation. Serum IL-5 is a marker of disease activity and treatment efficacy in bronchial asthma. To understand the role of IL-5 in disease activity in acute asthma, changes in serum concentrations of IL-5 elaborated by activated eosinophil before and after prednisolone therapy with clinical improvement were determined in the present study. Circulating levels of IL-5 in 16 normal control subjects and in sera from 22 allergic asthmatic children with acute exacerbation and in stable condition were determined by using commercially available assay kits. The mean concentration of serum IL-5 was higher in patients with acute exacerbation (6.30 +/- 2.21 pg/mL) and in stable asthmatics (5.55 +/- 2.23 pg/mL) compared to control group subjects (4.81 +/- 0.54 pg/mL; p > 0.05). However, the difference was not statistically significant between the acute exacerbation and stable asthmatics groups (p > 0.05). Serum IL-5 is a poor indicator of disease activity in acute asthma; therefore, monitoring serum IL-5 concentration is of limited value. The clinical value of serum IL-5 as a marker of disease activity remains to be established.

Oral administration of desloratadine prior to sensitization prevents allergen-induced airway inflammation and hyper-reactivity in mice

BACKGROUND

Histamine-1-receptor (H1R)-antagonists were shown to influence various immunological functions on different cell types and may thus be employed for immune-modulating strategies for the prevention of primary immune responses.

OBJECTIVE

The aim of this study was to investigate the effects of an H1R-antagonist on allergen-induced sensitization, airway inflammation (AI) and airway hyper-reactivity (AHR) in a murine model.

METHODS

BALB/c mice were systemically sensitized with ovalbumin (OVA) (six times, days 1-14) and challenged with aerosolized allergen (days 28-30). One day prior to the first and 2 h prior to every following sensitization, mice received either 1 or 0.01 microg of desloratadine (DL) or placebo per os.

RESULTS

Sensitization with OVA significantly increased specific and total IgE and IgG1 serum levels, as well as in vitro IL-5 and IL-4 production by spleen and peribronchial lymph node (PBLN) cells. Sensitized and challenged mice showed a marked eosinophilic infiltration in broncho-alveolar lavage fluids and lung tissues, and developed in vivo AHR to inhaled methacholine. Oral treatment with DL prior to OVA sensitization significantly decreased production of OVA-specific IgG1, as well as in vitro Th2-cytokine production by spleen and PBLN cells, compared with OVA-sensitized mice. Moreover, eosinophilic inflammation and development of in vivo AHR were significantly reduced in DL-treated mice, compared with sensitized controls.

CONCLUSION

Treatment with H1R-anatagonist prior to and during sensitization suppressed allergen-induced Th2 responses, as well as development of eosinophilic AI and AHR. This underscores an important immune modulating function of histamine, and implies a potential role of H1R-anatagonists in preventive strategies against allergic diseases.

Inhibition of signal transducer and activator of transcription 1 attenuates allergen-induced airway inflammation and hyperreactivity

BACKGROUND

Transcriptional factors of the signal transducer and activator of transcription (STAT) family play an important role in orchestrating immune reactions.

OBJECTIVE

The aim of the current study was to investigate the role of STAT-1 in murine allergen-induced sensitization and development of airway inflammation (AI) and airway hyperreactivity (AHR), cardinal features of bronchial asthma.

METHODS

BALB/c mice were systemically sensitized to ovalbumin and challenged with ovalbumin through the airways. Decoy oligonucleotide (ODN) specific for STAT-1 was applied once locally to the airways of sensitized animals before allergen airway challenges.

RESULTS

Single application of decoy ODN markedly and significantly reduced numbers of eosinophils and lymphocytes in bronchoalveolar lavage fluids compared with those seen in sensitized and challenged animals receiving mutant control ODN. Associated with this decrease in eosinophilic AI were significantly reduced levels of IL-5 in BAL fluid, of CD40 expression in peribronchial infiltrates, and of vascular cell adhesion molecule 1 expression in vascular endothelial cells, respectively. In addition, development of AHR after allergen sensitization and airway challenges was effectively abolished after local STAT-1 decoy ODN treatment.

CONCLUSION

The data indicate that a decoy ODN neutralizing STAT-1 effectively inhibits allergen-induced AI and AHR, probably by attenuating upregulation of costimulatory and adhesion molecules, and suggest a significant role of STAT-1 in asthma pathology.

Serum interleukin-5 levels are elevated in mild and moderate persistent asthma irrespective of regular inhaled glucocorticoid therapy

BACKGROUND

Interleukin-5 (IL-5) is thought to play a pivotal role in the pathogenesis of asthma. High levels of circulating IL-5 have been documented in acute asthma. However, serum IL-5 levels in mild to moderate asthmatics and the influence of regular use of inhaled glucocorticoids, is not known.

METHODS

Fifty-six asthmatics and 56 age and sex matched controls were recruited prospectively from an outpatient department. Information on asthma severity and treatment was gathered by a questionnaire. Serum IL-5, total IgE and specific IgE levels were measured in a blinded fashion.

RESULTS

There were 32 atopic and 24 non-atopic mild-to-moderate asthmatics. The median serum IL-5 levels in atopic asthmatics (9.5 pg/ml) and in non-atopic asthmatics (8.1 pg/ml) were significantly higher than in normal controls (4.4 pg/ml, both p < 0.003). However, median serum IL-5 levels in atopic and non-atopic asthmatics were not significantly different. The median serum IL-5 level was insignificantly higher in fourteen moderate persistent asthmatics (10.6 pg/ml) compared to forty-two mild persistent asthmatics (7.3 pg/ml) (p = 0.13). The median serum IL-5 levels in asthmatics using regular inhaled steroids (7.8 pg/ml) was not significantly different from those not using inhaled steroids (10.2 pg/ml). Furthermore, serum total IgE levels and eosinophil counts were not significantly different in those using versus those not using inhaled glucocorticoids.

CONCLUSION

Serum IL-5 levels are elevated in mild and moderate persistent atopic and non-atopic asthmatics. Regular use of inhaled glucocorticoids may not abrogate the systemic Th2 type of inflammatory response in mild-moderate persistent asthma.

Expression of interleukin-5- and granulocyte macrophage-colony-stimulating factor-responsive genes in blood and airway eosinophils

Because interleukin (IL)-5 family cytokines are critical regulators of eosinophil development, recruitment, and activation, this study was initiated to identify proteins induced by these cytokines in eosinophils. Using oligonucleotide microarrays, numerous transcripts were identified as responsive to both IL-5 and granulocyte macrophage-colony-stimulating factor (GM-CSF), but no transcripts were markedly affected by one cytokine and not the other. Expression of several gene products were seen to be increased following in vitro stimulation of human blood eosinophils, including the IL-3 receptor alpha subunit, lymphotoxin beta, Pim-1, and cyclin D3. Given that eosinophils recovered from the bronchoalveolar lavage fluid of allergic patients after antigen challenge are exposed to IL-5 or GM-CSF in the airway prior to isolation, the hypothesis was tested that selected IL-5- and GM-CSF-responsive genes are upregulated in airway eosinophils relative to the expression in blood cells. Airway eosinophils displayed greater cell surface expression of the IL-3 receptor alpha subunit, CD44, CD25, and CD66e, suggesting that these proteins may be markers of eosinophil activation by IL-5 family cytokines in airway eosinophils. Other genes that were induced by both IL-5 and GM-CSF showed protein expression at similar or decreased levels in airway eosinophils relative to their circulating counterparts (i.e., lymphotoxin beta and CD24). These studies have identified several transcriptional targets of IL-5 and GM-CSF in human eosinophils and suggest that a number of protein products are critical to the responsiveness of airway eosinophils.

Repeated daily exposure to 2 ppm nitrogen dioxide upregulates the expression of IL-5, IL-10, IL-13, and ICAM-1 in the bronchial epithelium of healthy human airways

BACKGROUND

Repeated daily exposure of healthy human subjects to NO2 induces an acute airway inflammatory response characterised by neutrophil influx in the bronchial mucosa

AIMS

To assess the expression of NF-kappaB, cytokines, and ICAM-1 in the bronchial epithelium.

METHODS

Twelve healthy, young non-smoking volunteers were exposed to 2 ppm of NO2/filtered air (four hours/day) for four successive days on separate occasions. Fibreoptic bronchoscopy was performed one hour after air and final NO2 exposures. Bronchial biopsy specimens were immunostained for NF-kappaB, TNF-alpha, eotaxin, Gro-alpha, GM-CSF, IL-5, -6, -8, -10, -13, and ICAM-1 and their expression was quantified using computerised image analysis.

RESULTS

Expression of IL-5, IL-10, IL-13, and ICAM-1 increased following NO2 exposure.

CONCLUSION

Upregulation of the Th2 cytokines suggests that repeated exposure to NO2 has the potential to exert a "pro-allergic" effect on the bronchial epithelium. Upregulation of ICAM-1 highlights an underlying mechanism for leucocyte influx, and could also explain the predisposition to respiratory tract viral infections following NO2 exposure since ICAM-1 is a major receptor for rhino and respiratory syncytial viruses.

Structural requirement of isoflavonones for the inhibitory activity of interleukin-5

Sophoricoside isolated from Sophora japonica is a glycoside of isoflavonone as an inhibitor of interleukin (IL)-5. To identify structural requirements of this isoflavonone for its inhibitory activity against IL-5, isoflavonones, isoflavanones, and their glycosides were prepared and their inhibitory activity was tested against IL-5. Among them, 5-benzyloxy-3-(4-hydroxyphenyl)chromen-4-one (4b, 87.9% inhibition at 50 microM, IC(50)=15.3 microM) shows the most potent activity, comparable with that of sophoricoside. The important structural requirements of these isoflavonone analogs exhibiting the inhibitory activity against IL-5 were recognized as (1) planarity of chromen-4-one ring, (2) existence of phenolic hydroxyl at 4-position of B ring, and (3) introduction of benzyloxy at 5-position, which may act as a bulky group for occupying hydrophobic pocket in putative binding site. However the glucopyranosyl moiety of sophoricoside is not an essential motif for the activity.

Effect of cocoa flavanols and their related oligomers on the secretion of interleukin-5 in peripheral blood mononuclear cells

We previously showed that flavanols and their related oligomers (FLO) isolated from cocoa can have immunomodulatory effects on production of the cytokines interleukin-1beta (IL-1beta), IL-2, and IL-4. In the present study, we examined whether selected FLO fractions isolated from cocoa (monomer through decamer) modulate IL-5 protein secretion from resting and phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC). Although FLO fractions were unstimulatory for IL-5 secretion in resting cells, PHA-induced IL-5 release from PBMC was markedly affected by certain FLO fractions. The monomeric and small oligomeric (dimer and trimer) fractions enhanced PHA stimulation by 50%, 54%, and 43%, respectively. In contrast, the larger oligomeric fractions (hexamer through decamer) inhibited IL-5 release in the range of 18% to 39%; the tetramer and pentamer showed intermediate effects. The increment in IL-5 suggests that FLO may preferentially stimulate immunoglobulin A. We suggest that in the oral cavity this could result in reduction in the risk for dental caries and periodontal disease. This work offers additional data for consideration of the health benefits of dietary FLO from a variety of foods, including those benefits associated specifically with consumption of some cocoas and chocolates.

Decreased expression of membrane IL-5 receptor alpha on human eosinophils: I. Loss of membrane IL-5 receptor alpha on airway eosinophils and increased soluble IL-5 receptor alpha in the airway after allergen challenge

IL-5 is a key cytokine for eosinophil maturation, recruitment, activation, and possibly the development of inflammation in asthma. High concentrations of IL-5 are present in the airway after Ag challenge, but the responsiveness of airway eosinophils to IL-5 is not well characterized. The objectives of this study were to establish, following airway Ag challenge: 1) the expression of membrane (m)IL-5Ralpha on bronchoalveolar lavage (BAL) eosinophils; 2) the responsiveness of these cells to exogenous IL-5; and 3) the presence of soluble (s)IL-5Ralpha in BAL fluid. To accomplish these goals, blood and BAL eosinophils were obtained from atopic subjects 48 h after segmental bronchoprovocation with Ag. There was a striking reduction in mIL-5Ralpha on airway eosinophils compared with circulating cells. Furthermore, sIL-5Ralpha concentrations were elevated in BAL fluid, but steady state levels of sIL-5Ralpha mRNA were not increased in BAL compared with blood eosinophils. Finally, BAL eosinophils were refractory to IL-5 for ex vivo degranulation, suggesting that the reduction in mIL-5Ralpha on BAL eosinophils may regulate IL-5-mediated eosinophil functions. Together, the loss of mIL-5Ralpha, the presence of sIL-5Ralpha, and the blunted functional response (degranulation) of eosinophils to IL-5 suggest that when eosinophils are recruited to the airway, regulation of their functions becomes IL-5 independent. These observations provide a potential explanation for the inability of anti-IL-5 therapy to suppress airway hyperresponsiveness to inhaled Ag, despite a reduction in eosinophil recruitment.

Eosinophilic gastroenteritis

Eosinophilic gastroenteritis is a rare gastrointestinal (GI) disorder of undetermined cause characterized by infiltration of eosinophils in the GI tract. Eosinophils accumulate in tissues and may release highly cytotoxic granular proteins, which cause severe tissue damage characteristic of eosinophilic gastroenteritis. Eotaxin may play a role in the recruitment of eosinophils into tissue in combination with chemoattractants and cytokines, including interleukin 3 and 5 and granulocyte-macrophage colony-stimulating factor. Food allergy, especially in children, can be a triggering factor, and an amino acid-based diet may be helpful. Accumulation of eosinophils in the gut is a common feature in food-induced GI disorders that can be regulated through a complex molecular network involving Th2 cells, various cytokines, and chemokines. Eosinophilic gastroenteritis has a wide spectrum of clinical presentation depending on the site of involvement. It may be confused with irritable bowel syndrome or dyspepsia and, rarely, mimics pancreatitis or appendicitis. Diagnosis is important and is usually made by a pathologist. Eosinophilic gastroenteritis is a treatable disease; patients generally respond to steroid therapy, although relapse is common. Non-enteric-coated budesonide, a locally acting corticosteroid with little risk of adrenal suppression, may be substituted, although more experience is needed. Promising new drugs for eosinophilic gastroenteritis include montelukast, a selective leukotriene receptor antagonist, and suplaplast tosilate, a selective Th2 cytokine inhibitor with inhibitory effects on allergy-induced eosinophilic infiltration and IgE production. Although it is likely a separate disease, more experience has accumulated, and an elimination or specific amino acid-based diet appears to be helpful in treatment.

Functional characterization and biomarker identification in the Brown Norway model of allergic airway inflammation

1. The antigen-induced inflammatory response in the Brown Norway rat is a model commonly used to assess the impact of novel compounds on airway eosinophilia. A detailed functional, cellular and molecular characterization of this model has not yet been performed within a single study. This information together with the temporal changes in this phenomenon should be known before this model can be used, with confidence, to elucidate the mechanisms of action of novel anti-inflammatory drugs. 2. Antigen challenge caused an accumulation of eosinophils in lung tissue 24 h after challenge. Accumulation of CD2(+) T cells was not apparent until after 72 h. 3. Interestingly, mRNA for the Th2 type cytokines interleukin (IL)-4, IL-5 and IL-13 and eotaxin were elevated in lung tissue after challenge and the expression of IL-13 and eotaxin protein increased at around 8-12 h. The temporal changes in both the biomarker production and the functional responses are important factors to consider in protocol design prior to initiating a compound screening program. 4. A neutralising antibody (R73) against alphabeta-TCR caused a significant reduction in T cell numbers accompanied by a significant suppression of eosinophil accumulation. 5. Airway hyperreactivity (AHR) was not apparent in this specific Brown Norway model in sensitized animals after a single or multiple challenges although eosinophil influx was seen in the same animals. 6. In conclusion, this is a convenient pre-clinical model (incorporating the measurement of biomarkers and functional responses) for screening novel small molecule inhibitors and/or biotherapeutics targeted against T cell/eosinophil infiltration/activation.

Human milk-specific mucosal lymphocytes of the gastrointestinal tract display a TH2 cytokine profile

BACKGROUND

A number of gastrointestinal disorders, including allergic eosinophilic gastroenteritis and food protein-induced enteropathy, have been associated with milk hypersensitivity. The immunologic reactions appear to involve T cells that are activated by specific food proteins.

OBJECTIVE

The present study was performed to examine the cytokine profiles of milk-specific lymphocytes from the duodenal lamina propria from children with milk-induced gastrointestinal diseases.

METHODS

Duodenal biopsy specimens obtained from 10 patients with allergic eosinophilic gastroenteritis, food protein-induced enteropathy, or both and 12 control subjects were mechanically minced and cultured with either mitogens (i.e., polyclonal T-cell expansion) or milk proteins (i.e., milkspecific T-cell expansion). By using flow cytometry, expanded T cells were phenotyped with anti-CD4, anti-CD8, anti-IL-4, anti-IL-5, and anti-IFN-gamma mAbs. The milk specificity of the lines was evaluated by means of the lymphocyte proliferation assay. In addition, the release of T(H)1, T(H)2, and T(H)3 cytokines was determined after restimulation.

RESULTS

In patients and control subjects polyclonal expansion of mucosal lymphocytes resulted in predominantly T(H)1 cells. Milk-specific mucosal T-cell lines could be established in 60% of the patients but in none of the control subjects. In contrast to the polyclonal expansion of T cells, the milk-specific expansion of mucosal T cells showed a clear T(H)2 cytokine profile. On restimulation with milk protein, these cells showed a high proliferative response. They released T(H)2 cytokines, predominately IL-13, but failed to release T(H)3 cytokines important in the development of oral tolerance.

CONCLUSION

The release of T(H)2 cytokines after stimulation of milk-specific mucosal T cells may play a pathogenic role in the inflammatory changes seen in milk-induced gastrointestinal disorders.

Eosinophilic bronchitis: clinical manifestations and implications for treatment

Airway inflammation with eosinophils is now reported to occur not only in asthma but in other airway diseases such as cough variant asthma, chronic cough, atopic cough, episodic symptoms without asthma, allergic rhinitis, and COPD. Although the prevalence of eosinophilic bronchitis (EB) is less than in asthma, the causes, mechanisms and treatment of EB in these conditions appears to be similar to asthma where allergen induced IL-5 secretion and symptoms are readily responsive to inhaled corticosteroids. The prognosis of EB without asthma is not known but it may be a precursor for asthma and, if so, recognition of this syndrome may permit effective treatment and reduction in the rising prevalence of asthma. Induced sputum analysis allows recognition of EB in clinical practice. The place of the asthma treatment paradigm with early and sustained corticosteroid treatment needs to be defined in EB without asthma. Airway wall remodelling can occur in rhinitis, COPD, and cough variant asthma with EB. The mechanisms and long term implications of this complication in EB without asthma need to be clarified.

Fas deficiency delays the resolution of airway hyperresponsiveness after allergen sensitization and challenge

BACKGROUND

In asthma, persistent inflammation might be the result of (1) an impaired ability to clear inflammatory cells from the airways and/or (2) impaired apoptotic responses.

OBJECTIVE

In a mouse model, we investigated the regulatory role of Fas (CD95)-induced apoptosis in the development and resolution of airway inflammation and airway hyperresponsiveness (AHR).

METHODS

Mice that were either Fas-sufficient (wild-type; WT) or Fas-deficient (lpr ) were sensitized by intraperitoneal injections of ovalbumin (OVA) and challenged once intranasally with OVA (IP-IN mice). Control (IN) mice were challenged only.

RESULTS

IP-IN WT mice developed AHR at 48 hours; changes in airway resistance resolved by 96 hours. Airway responsiveness at 48 hours in IP-IN lpr mice was similar to that in IP-IN WT mice. However, in contrast to WT mice, IP-IN lpr mice sustained significant AHR at 96 hours in comparison with IN lpr mice; the AHR resolved by 6 days. Bronchoalveolar lavage fluid cell composition was similar in all of the different groups at 48 hours and 96 hours. Both IP-IN WT mice and lpr mice exhibited similar tissue eosinophilia, whereas IP-IN lpr mice had significantly lower numbers of TdT-mediated dUTP nick end labeling (TUNEL)-positive cells in comparison with IP-IN WT mice at 48 hours. Anti-IL-5 antibody given to IP-IN lpr mice 48 hours and 72 hours after the challenge significantly decreased AHR and eosinophilic inflammation and increased TUNEL-positive cell numbers at 96 hours.

CONCLUSION

These results suggest that Fas expression can regulate the onset and resolution of AHR through an increase in eosinophil apoptosis.

Il-13 and IFN-gamma: interactions in lung inflammation

Chronic inflammatory diseases of the lungs, such as asthma, are frequently associated with mixed (Th2 and Th1) T cell responses. We examined the impact of critical Th1 and Th2 cytokines, IFN-gamma and IL-13, on the responses in the lungs. In a mouse model of airway inflammation induced by mixed T cell responses, the number of Th1 (IFN-gamma-positive) cells was found to be negatively correlated with airway hyperreactivity. In these mice, blockade of IL-13 partially inhibited airway hyperreactivity and goblet cell hyperplasia but not inflammation. In contrast, in mice that responded with a polarized Th2 response to the same Ag, blockade of IL-13 inhibited airway hyperreactivity, goblet cell hyperplasia, and airway inflammation. These results indicated that the presence of IFN-gamma would modulate the effects of IL-13 in the lungs. To test this hypothesis, wild-type mice were given recombinant cytokines intranasally. IFN-gamma inhibited IL-13-induced goblet cell hyperplasia and airway eosinophilia. At the same time, IFN-gamma and IL-13 potentiated each other's effects. In the airways of mice given IL-13 and IFN-gamma, levels of IL-6 were increased as well as numbers of NK cells and of CD11c-positive cells expressing MHC class II and high levels of CD86. In conclusion, IFN-gamma has double-sided effects (inhibiting some, potentiating others) on IL-13-induced changes in the lungs. This may be the reason for the ambiguous role of Th1 responses on Th2 response-induced lung injury.

Preclinical efficacy and safety of mepolizumab (SB-240563), a humanized monoclonal antibody to IL-5, in cynomolgus monkeys

BACKGROUND

Allergic respiratory diseases are characterized by large numbers of eosinophils and their reactive products in airways and blood; these are believed to be involved in progressive airway damage and remodeling. IL-5 is the principal cytokine for eosinophil maturation, differentiation, and survival. Mepolizumab (SB-240563), a humanized monoclonal antibody (mAb) specific for human IL-5, is currently in clinical trials for treatment of asthma.

OBJECTIVE

The purpose of this study was to characterize the pharmacologic activity and long-term safety profile of an anti--human IL-5 mAb to support clinical trials in asthmatic patients.

METHODS

Naive and Ascaris suum -sensitive cynomolgus monkeys received various dose levels of mepolizumab and were monitored for acute and chronic pharmacologic and toxic responses.

RESULTS

To support preclinical safety assessment, cynomolgus monkey IL-5 was cloned, expressed, and characterized. Although monkey IL-5 differs from human IL-5 by 2 amino acids (Ala27Gly and Asn40His), mepolizumab has comparable inhibitory activity against both monkey IL-5 and human IL-5. In A suum--sensitive monkeys, single doses of mepolizumab significantly reduced blood eosinophilia, eosinophil migration into lung airways, and levels of RANTES and IL-6 in lungs for 6 weeks. However, mepolizumab did not affect acute bronchoconstrictive responses to inhaled A suum. In an IL-2--induced eosinophilia model (up to 50% blood eosinophilia), 0.5 mg/kg mepolizumab blocked eosinophilia by >80%. Single-dose and chronic (6 monthly doses) intravenous and subcutaneous toxicity studies in naive monkeys found no target organ toxicity or immunotoxicity up to 300 mg/kg. Monkeys did not generate anti-human IgG antibodies. Monthly mepolizumab doses greater than 5 mg/kg caused an 80% to 100% decrease in blood and bronchoalveolar lavage eosinophils lasting 2 months after dosing, and there was no effect on eosinophil precursors in bone marrow after 6 months of treatment. Eosinophil decreases correlated with mepolizumab plasma concentrations (half-life = 13 days).

CONCLUSION

These studies demonstrate that chronic antagonism of IL-5 by mepolizumab in monkeys is safe and has the potential, through long-term reductions in circulating and tissue-resident eosinophils, to be beneficial therapy for chronic inflammatory respiratory diseases.

Anti-allergy properties of fermented foods: an important immunoregulatory mechanism of lactic acid bacteria?

Clinical reports have suggested that dietary consumption of fermented foods, such as yogurt, can alleviate some of the symptoms of atopy and might also reduce the development of allergies, possibly via a mechanism of immune regulation. Controlled studies have indicated that consumption of fermented milk cultures containing lactic acid bacteria (LAB) can enhance production of Type I and Type II interferons at the systemic level. In animal models, LAB have been shown to promote interferon expression, and to reduce allergen-stimulated production of IL-4 and IL-5 in some cases. Recent results have shown that LAB are potent inducers of pro-interferon monokines (IL-12 and IL-18), and that cytokine secretion is stimulated by the interaction of Gram-positive cell wall components with surface receptors of mononuclear phagocytes, via NF-kappa B and STAT signalling pathways. However, it is clear that the extent and quality of LAB-induced immunoregulation is strain-dependent. This review discusses the clinical and laboratory evidence for anti-allergy properties of fermented foods, and proposes a model for the mechanism by which some well-defined strains of immunoregulatory LAB might down-regulate a Th2 allergic phenotype.

Inhibition of IgE-induced activation of human mast cells by IL-10

BACKGROUND

IL-10 exhibits anti-inflammatory effects on activated rodent mast cells (MC) in vitro and inhibits allergen-induced airway inflammation in vivo in murine models. The effects of IL-10 on the allergic activation of human MC are presently unknown.

OBJECTIVE

In light of the well-known heterogeneity of mast cell reactivity between animal species, one cannot readily predict the response of human MC to IL-10. Moreover, the impact of IL-10 on MC-derived proinflammatory mediators is still unknown. Thus, the objective of this study was to investigate the effects of IL-10 on the release of inflammatory mediators by IgE/anti-IgE-challenged human cord blood-derived mast cells (CBMC), used as an in vitro model of MC phenotypically similar to human lung MC.

MATERIALS AND METHODS

Highly purified human MC were obtained by a first step of long-term culture of cord blood mononuclear cells in the presence of human recombinant stem cell factor (rhSCF) and of human recombinant IL-6 (rhIL-6), followed by a second step of purification by depletion of contaminating cells with an immunomagnetic

METHOD

The cells were treated with human IgE, then challenged with anti-human IgE, in the presence or the absence of recombinant rhIL-10 used at various concentrations. Histamine, tumour necrosis factor-alpha (TNF-alpha), IL-5 and IL-8 were measured in the various supernatants collected at different times after the beginning of the challenge.

RESULTS

IL-10 inhibited the release of TNF-alpha and of IL-8, but not of IL-5, by activated CBMC. Interestingly, IL-10 also inhibited the release of histamine by activated CBMC, contrasting with data reported for rodent MC.

CONCLUSIONS

These findings suggest that IL-10 might have anti-inflammatory effects on IgE/anti-IgE-challenged human MC by inhibiting their release of TNF-alpha, IL-8 and histamine. These data provide new insights into the control of human mast cell activation and might lead to a better knowledge of the cellular mechanisms controlling allergic reactions.

Cytokine fingerprinting and hazard assessment of chemical respiratory allergy

Allergic sensitization of the respiratory tract resulting in occupational asthma and other symptoms can be caused by a variety of chemicals and represents an important occupational health problem. Although there is a need to identify and characterize those chemicals that are able to cause respiratory allergy, there are currently no well validated or widely accepted predictive test methods. Some progress has been made with guinea pig assays, but our attention in this laboratory has focused instead on the development of novel approaches based on an understanding of the nature of immune responses induced in mice by chemical allergens. We have shown that whereas contact allergens provoke in mice selective type 1 immune responses, characterized by the secretion by draining lymph node cells (LNC) of high levels of the cytokine interferon gamma (IFN-gamma), chemical respiratory allergens stimulate instead preferential type 2 responses associated with comparatively high levels of interleukins 4 and 10 (IL-4 and IL-10). The divergent immune responses provoked by different classes of chemical allergens, and the phenotypes of selective cytokine secretion that characterize such responses, form the basis of a novel method-cytokine fingerprinting--that permits chemicals that have the potential to cause respiratory allergy to be identified and distinguished from those that are associated primarily with contact sensitization. In this article the immunobiological basis for cytokine fingerprinting is considered and the development, evaluation and practical application of the assay are reviewed.

Expression and in vitro properties of guinea pig IL-5: comparison to human and murine orthologs

Interleukin-5 (IL-5) is a key mediator of eosinophilic inflammation. The biological role of this cytokine in an allergic airway inflammatory response has been widely demonstrated in guinea pigs, yet the interaction of guinea pig IL-5 (gpIL-5) with its receptor has not been studied. Experiments were performed to quantitate the interaction of gpIL-5 with gpIL-5r and to compare this affinity with that of hIL-5 and mIL-5 and their cognate receptors. The cross-species affinity and agonist efficacy were evaluated to see if gpIL-5r had a restricted species reactivity (as is the case with mIL-5r) or did not distinguish between IL-5 orthologs (similar to hIL-5r). gpIL-5 was cloned using mRNA isolated from cells obtained by bronchoalveolar lavage. Recombinant gpIL-5 was expressed in T. ni insect cells and purified from spent media. Binding assays were performed using insect cells expressing hIL-5ralphabeta or gpIL-5ralphabeta1 as previously described (Cytokine, 12:858-866, 2000) or using B13 cells which express mIL-5r. The agonist potency and efficacy properties of each IL-5 ortholog were evaluated by quantitating the proliferative response of human TF-1 cells and murine B13 cells. gpIL-5 bound with high affinity to recombinant gpIL-5r as demonstrated by displacing [125I]hIL-5 (Ki = 160 pM). gpIL-5 also bound to hIL-5r with high affinity (Ki = 750 pM). hIL-5 and mIL-5 showed similar, high-affinity binding profiles to both gpIL-5r and hIL-5r. In contrast, gpIL-5 and hIL-5 did not bind to the mIL-5r as demonstrated by an inability to displace [125I]mIL-5, even at 1000-fold molar excess. These differences in affinity for IL-5r orthologs correlated with bioassay results: human TF-1 cells showed roughly comparable proliferative responses to guinea pig, human and murine IL-5 whereas murine B13 cells showed a strong preference for murine over guinea pig and human IL-5 (EC50 = 1.9, 2200 and 720 pM, respectively). Recombinant gpIL-5 binds to the gpIL-5r with high affinity, similar to that seen with the human ligand-receptor pair. gpIL-5r and hIL-5r do not distinguish between the three IL-5 orthologs whereas mIL-5r has restricted specificity for its cognate ligand.