Interleukin-13-dependent bronchial hyper-responsiveness following isolated upper-airway allergen challenge in a murine model of allergic rhinitis and asthma

A Comparative Study of Symptoms, Nasal Eosinophilia and Pulmonary Function Tests Before and After Short Term Treatment with Corticosteroid Nasal Spray in Patients with Allergic Rhinitis

Allergic rhinitis has been on the rise because of urbanization and major population shift in addition to changes in the particulate matter in the atmosphere. Intranasal corticosteroid sprays are recommended as first-line prescription treatment in all cases of allergic rhinitis. The propensity of co-existing non-apparent lower airway hyper-responsiveness is also on the rise and must be evaluated. The aim of this study is to compare the symptomatic improvement, changes in nasal eosinophilia and asymptomatic airway hyper responsiveness before and after short term treatment with steroid nasal spray. Fifty patients meeting the inclusion criteria for allergic rhinitis with no symptoms of asthma underwent pulmonary function tests and assessment of symptoms before and after one-month treatment with inhalational steroid nasal spray (Fluticasone Furoate), in the standard adult dosage. Based on TNSS (Total nasal symptom score) and TOSS (Total ocular symptom score), all 50 patients showed significant improvement after treatment. Among 20 patients with > 50 eosinophils per high power field, 80% had 0-10 eosinophils per high power field on nasal smear after treatment. Among 40 patients with mild large airway obstruction, 37 showed significant improvement in FEV1 data. Also FEV1/FVC data showed significant improvement. Significant improvement (FEF25-75 > 50%) was also noticed in small airway disease after treatment among the 5 patients. The study showed that lower airway hyper responsiveness coexists with allergic rhinitis and treating allergic rhinitis with just steroid nasal spray assists in reducing the former, supporting the concept of Unified Airway Disease (UAD).

Inhibition of TRPA1 reduces airway inflammation and hyperresponsiveness in mice with allergic rhinitis

This study was conducted to investigate whether a transient receptor potential ankyrin 1 (TRPA1) antagonist (HC-030031) can reduce airway inflammation and hyperresponsiveness in a murine allergic rhinitis (AR) model. BALB/c mice were sensitized and challenged by ovalbumin (OVA) to induce AR. HC-030031 or vehicle was administrated to mice via intraperitoneal injection prior to OVA challenges. Nose-scratching events, histopathologic alterations of the airways, and bronchial hyperresponsiveness (BHR) were assessed. Differential cells and proinflammatory cytokines in the nasal lavage (NAL) and bronchoalveolar lavage (BAL) fluid were measured. Expressions of TRPA1 in nasal mucosa were examined by immunohistochemistry. TRPA1-expressing vagal neurons were labeled by immunofluorescent staining. HC-030031-treated AR mice had markedly reduced type-2 inflammation in nasal mucosa and ameliorated-nose-scratching events than AR mice received vehicle. HC-030031 treatment also dramatically reduced leucocyte numbers and IL-8 level in the BAL fluid, inhibited lower airway remodeling and fibrosis, and nearly abolished BHR. HC-0300031 treatment significantly inhibited the upregulated number of TRPA1 expressing nasal epithelial cells and TRPA1 expressing sensory neurons, leading to downregulation of SP in both upper and lower airways. Targeting TRPA1 may represent a promising strategy for treating AR and AR-related asthma.

Biologic Therapies for Allergic Rhinitis and Nasal Polyposis

PURPOSE OF REVIEW

There is an emerging body of research on targeted biologic therapies for the treatment of severe inflammatory nasal disorders, especially chronic rhinosinusitis with nasal polyposis (CRSwNP). This paper will evaluate the efficacy of biologic therapies for severe nasal inflammation by summarizing key preclinical trials of biologics for animal models of allergic rhinitis and the recent phase 2 and 3 clinical trials of biologic therapies for CRSwNP.

RECENT FINDINGS

Biologics that target the IL-4 receptor (dupilumab), IgE (omalizumab), and IL-5 (mepolizumab, reslizumab, and benralizumab) in patients with CRSwNP have shown improvement of various metrics including Sino-Nasal Outcome Test (SNOT-22) scores, Nasal Polyp Scores (NPS), Nasal Congestion Scores (NCS), and Lund-Mackay sinus opacification scores. The efficacy demonstrated through the dupilumab phase 3 trials (LIBERTY NP SINUS-24 and SINUS-52) led to approval of the first biologic for the treatment of CRSwNP. Phase 3 trials for omalizumab (POLYP 1 and 2) and mepolizumab (SYNAPSE study) and post hoc analyses of phase 3 asthma studies for reslizumab and benralizumab have also demonstrated positive results for the use of biologics for patients with CRSwNP. Future efficacy studies and risk/benefit and cost analyses of these biologics and other cytokine targets for allergic rhinitis with and without nasal polyposis need to be performed.

The Nose and the Lung: United Airway Disease?

Epidemiologic, pathophysiologic, and clinical evidences recently revealed the link between upper and lower airways, changing the global pathogenic view of respiratory allergy. The aim of this review is to highlight the strong interaction between the upper and lower respiratory tract diseases, in particular allergic rhinitis and asthma.

Inhalation of inactivated‑Mycobacterium phlei prevents asthma‑mediated airway hyperresponsiveness and airway eosinophilia in mice by reducing IL‑5 and IL‑13 levels

The present study aimed to investigate whether inhalation of inactivated‑Mycobacterium phlei could prevent airway hyperresponsiveness and airway eosinophilia. A total of 24 male Balb/c mice were randomly divided into three groups: Normal control group (group A), asthma model group (group B) and the intervention group (group C), (8 mice/group). Group A mice were sensitized and with challenged saline and group B with ovalbumin (OVA). Group C mice were administered with aerosol Mycobacterium phlei once daily prior to the allergen challenge. Airway responsiveness in each group was assessed. All the animals were sacrificed and lung tissues, blood samples and bronchoalveolar lavage fluid (BALF) were harvested. Cell fractionation and differential cells were counted in serum and BALF. HE staining and alcian blue/periodic acid Schiff staining were used to measure airway eosinophilic inflammation and mucus production. The levels of the cytokines IL‑5, IL‑13 and IgE were measured in lung and BALF as determined by ELISA and reverse transcription‑quantitative polymerase chain reaction assays. The results indicated that inactivated‑Mycobacterium phlei suppressed the airway hyperresponsiveness and mitigated airway eosinophilia induced by a methacholine challenge, and significantly reduced the levels of cytokines IL‑5 and IL‑13 in lung tissue and IgE level in BALF when compared with the OVA‑sensitized mice. In conclusion, inhalation of inactivated‑Mycobacterium phlei could reduce OVA‑induced airway hyperresponsiveness and may be a potential alternative therapy for allergic airway diseases.

The role of IL-33/ST2, IL-4, and eosinophils on the airway hyperresponsiveness induced by Strongyloides venezuelensis in BALB/c mice

Strongyloidiasis is a neglected chronic nematode infection, in which the control of autoinfection rate and severity of disease is dependent on type 2 immune responses. Strongyloides also causes Th2 responses in the lung of infected animals and changes in airway function, including airway hyperresponsiveness (AHR). Mechanisms of AHR during Strongyloides venezuelensis infection are not entirely known, and we investigate here the role of IL-4, eosinophils, and IL-33/ST2. AHR was evaluated in infected mice by determining changes in lung function after increasing doses of methacholine. Balb/C, but no C57Bl/6, mice developed AHR, tissue eosinophilia, and increased local IL-4 and IL-5 production. Functional changes peaked at day 4 and 7, after the larva had left the lungs. AHR was clearly dependent on IL-4 but not on eosinophils, as evaluated by experiments in IL-4 and Gata-1-deficient mice. Experiments in ST2-deficient mice showed that this pathway was not needed for induction of AHR but was necessary for the maintenance of AHR and for Th2 responses in the lung. These studies clearly show a crucial role for IL-4 in the induction of AHR following S. venezuelensis infection and for IL-33/ST2 in maintaining AHR and lung Th2 responses.

Anti-Interleukin-1 Beta/Tumor Necrosis Factor-Alpha IgY Antibodies Reduce Pathological Allergic Responses in Guinea Pigs with Allergic Rhinitis

This study aims to determine whether the combined blockade of IL-1β and TNF-α can alleviate the pathological allergic inflammatory reaction in the nasal mucosa and lung tissues in allergic rhinitis (AR) guinea pigs. Healthy guinea pigs treated with saline were used as the healthy controls. The AR guinea pigs were randomly divided into (1) the AR model group treated with intranasal saline; (2) the 0.1% nonspecific IgY treatment group; (3) the 0.1% anti-TNF-α IgY treatment group; (4) the 0.1% anti-IL-1β IgY treatment group; (5) the 0.1% combined anti-IL-1β and TNF-α IgY treatment group; and (6) the fluticasone propionate treatment group. The inflammatory cells were evaluated using Wright's staining. Histopathology was examined using hematoxylin-eosin staining. The results showed that the number of eosinophils was significantly decreased in the peripheral blood, nasal lavage fluid, and bronchoalveolar lavage fluid (P < 0.05), and eosinophil, neutrophil, and lymphocyte infiltration and edema were significantly reduced or absent in the nasal mucosa and lung tissues (P < 0.05) in the combined 0.1% anti-IL-1β- and TNF-α IgY-treated guinea pigs. The data suggest that topical blockade of IL-1β and TNF-α could reduce pathological allergic inflammation in the nasal mucosa and lung tissues in AR guinea pigs.

An intratracheal challenge murine model of asthma: can bronchial inflammation affect the nose?

PURPOSE

Extensive data support the influence of the upper airway on lower airway inflammation and pathophysiology in allergic disease. However, few studies have focused on allergic inflammation in the nose after an isolated lower airway allergen challenge, a situation that can exist clinically when human subjects breathe primarily through the mouth, as occurs when nasally congested. This study used a mouse model to investigate whether upper airway inflammation and hyperresponsiveness were induced by an isolated lower airway allergen challenge.

METHODS

BALB/c mice were sensitized by systemic intraperitoneal injection of ovalbumin/saline and challenged with intratracheal ovalbumin/saline. Inflammation in the nose and lungs was assessed by cytology and histology of nasal tissues and bronchoalveolar lavage fluid (BALF), while nasal airway resistance and response were measured over 3 days post-challenge.

RESULTS

Intratracheal application of an allergen in anaesthetized mice resulted in exclusive deposition in the lower airway. Compared to control animals, ovalbumin-sensitized mice after challenge showed bronchial hyperreactivity and increased IL-5 in the serum BALF, as well as eosinophil infiltration in the lungs. However, nasal histology of the ovalbumin-sensitized mice showed no increase in eosinophil infiltration. The nasal lavage fluid revealed no increase in eosinophils or IL-5, and the nasal airway resistance did not increase after challenge either.

CONCLUSIONS

In a mouse allergy model, exclusive allergen challenge of the lower airway can elicit a pulmonary and systemic allergic response, but does not induce upper airway inflammatory or physiological responses.

IL-17 producing T cells correlate with polysensitization but not with bronchial hyperresponsiveness in patients with allergic rhinitis

Background

Th2-type T cell response has a considerable role in atopic diseases. The involvement of Th17 and IL-17 in atopy process provided new understanding of allergic diseases. Bronchial hyperresponsiveness is quite common in allergic rhinitis. We aimed to explore the expression of IL-17 producing CD3⁺ CD4⁺ T cells in peripheral blood of rhinitic patients, with/without bronchial hyperresponsiveness and sensitized to common allergens, as this relationship has not been examined.

Methods

Sixty one patients with allergic rhinitis and thirty controls were examined. IL-17 producing T cells were detected by flow cytometry, IL-17, IL-4 and IL-13 levels in peripheral blood were evaluated by ELISA. Bronchial hyperresponsiveness was investigated with methacholine challenge test. Atopy was evaluated by skin prick tests with common allergens.

Results

IL-17 producing T cell percentage of AR group was significantly higher: 2.59 ± 1.32 than in controls 1.24 ± 0.22, (p = 0.001). Significant sex related difference in CD3⁺ CD4⁺ IL-17 T cells was observed: respectively in male patients versus female 3.15 ± 1.8% and 2.31 ± 0.9%, (p = 0.02). Rhinitics had greater bronchodilator responses compared to controls (p = 0.001), however the percentages of T cells in both groups appeared equal. Serum IL-17 levels in AR group were significantly higher (5.10 ± 4.40) pg/ml than in controls (3.46 ±1.28) pg/ml, (p = 0.04). IL-4 levels (0.88 ± 1.27) and IL-13 levels (3.14 ± 5.85) in patients were significantly higher than in control’s (0.54 ± 0.10) pg/ml, (p = 0.001) and (1.19 ± 0.64) pg/ml; (p = 0.001) respectively.

The percentages of T cells in patients sensitized to 5 allergens (group I) were significantly lower (1.91 ± 0.62) than those sensitized to more than 5 allergens (group II) (2.91 ± 1.5) (p = 0.004).

Conclusions

The observed higher levels of IL-17 producing T cells in polysensitized males suggest a role of IL-17 in pathogenesis of AR. The higher airway responsiveness in AR may not be Th17 dependent. The higher serum values of IL-17, IL-4 and IL-13 demonstrate the presence of cytokine balance in atopic diseases.

Oral Bromelain Attenuates Inflammation in an Ovalbumin-induced Murine Model of Asthma

Bromelain, a widely used pineapple extract with cysteine protease activity, has been shown to have immunomodulatory effects in a variety of immune system models. The purpose of the present study was to determine the effects of orally administered bromelain in an ovalbumin (OVA)-induced murine model of acute allergic airway disease (AAD). To establish AAD, female C57BL/6J mice were sensitized with intraperitoneal (i.p.) OVA/alum and then challenged with OVA aerosols for 3 days. Mice were gavaged with either (phosphate buffered saline)PBS or 200 mg/kg bromelain in PBS, twice daily for four consecutive days, beginning 1 day prior to OVA aerosol challenge. Airway reactivity and methacholine sensitivity, bronchoalveolar lavage (BAL) cellular differential, Th2 cytokines IL-5 and IL-13, and lung histology were compared between treatment groups. Oral bromelain-treatment of AAD mice demonstrated therapeutic efficacy as evidenced by decreased methacholine sensitivity (P ≤ 0.01), reduction in BAL eosinophils (P ≤ 0.02) and IL-13 concentrations (P ≤ 0.04) as compared with PBS controls. In addition, oral bromelain significantly reduced BAL CD19+ B cells (P ≤ 0.0001) and CD8+ T cells (P ≤ 0.0001) in AAD mice when compared with controls. These results suggest that oral treatment with bromelain had a beneficial therapeutic effect in this murine model of asthma and bromelain may also be effective in human conditions.

Diospyros blancoi attenuates asthmatic effects in a mouse model of airway inflammation

Asthma is a complex disease linked to various pathophysiological events, including proteinase activity. In this study, we examined whether a Diospyros blancoi methanolic extract (DBE) exerts protective effects on allergic asthma in a murine asthma model. To investigate the specific role of DBE, we employed a murine model of allergic airway inflammation. BALB/c mice sensitized and challenged with ovalbumin (OVA) were orally administered 20 or 40 mg/kg DBE for 3 days during OVA challenge. DBE induced significant suppression of the number of OVA-induced total inflammatory cells, including eosinophils, macrophages, and lymphocytes, in bronchoalveolar lavage fluid (BALF). Moreover, treatment with DBE led to significant decreases in interleukin (IL)-4, IL-5, and eotaxin levels in BALF and OVA-specific immunoglobulin (Ig)E and IgG1 levels in serum. Histological examination of lung tissue revealed marked attenuation of allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells in the airway. Additionally, DBE suppressed matrix metalloproteinase-9 activity and induced heme oxygenase-1 expression. The present findings collectively suggest that DBE exhibits anti-inflammatory activity in an airway inflammation mouse model, supporting its therapeutic potential for the treatment of allergic bronchial asthma.

Bronchial responsiveness is related to increased exhaled NO (FE(NO)) in non-smokers and decreased FE(NO) in smokers

RATIONALE

Both atopy and smoking are known to be associated with increased bronchial responsiveness. Fraction of nitric oxide (NO) in the exhaled air (FE(NO)), a marker of airways inflammation, is decreased by smoking and increased by atopy. NO has also a physiological bronchodilating and bronchoprotective role.

OBJECTIVES

To investigate how the relation between FE(NO) and bronchial responsiveness is modulated by atopy and smoking habits.

METHODS

Exhaled NO measurements and methacholine challenge were performed in 468 subjects from the random sample of three European Community Respiratory Health Survey II centers: Turin (Italy), Gothenburg and Uppsala (both Sweden). Atopy status was defined by using specific IgE measurements while smoking status was questionnaire-assessed.

MAIN RESULTS

Increased bronchial responsiveness was associated with increased FE(NO) levels in non-smokers (p = 0.02) and decreased FE(NO) levels in current smokers (p = 0.03). The negative association between bronchial responsiveness and FE(NO) was seen only in the group smoking less <10 cigarettes/day (p = 0.008). Increased bronchial responsiveness was associated with increased FE(NO) in atopic subjects (p = 0.04) while no significant association was found in non-atopic participants. The reported interaction between FE(NO) and smoking and atopy, respectively were maintained after adjusting for possible confounders (p-values<0.05).

CONCLUSIONS

The present study highlights the interactions of the relationship between FE(NO) and bronchial responsiveness with smoking and atopy, suggesting different mechanisms behind atopy- and smoking-related increases of bronchial responsiveness.

Cytokine/anti-cytokine therapy - novel treatments for asthma?

Asthma is a chronic inflammatory disease of the airways and there are no preventions or cures. Inflammatory cells through the secretion of cytokines and pro-inflammatory molecules are thought to play a critical role in pathogenesis. Type 2 CD4(+) lymphocytes (Th2 cells) and their cytokines predominate in mild to moderate allergic asthma, whereas severe steroid-resistant asthma has more of a mixed Th2/Th1 phenotype with a Th17 component. Other immune cells, particularly neutrophils, macrophages and dendritic cells, as well structural cells such as epithelial and airway smooth muscle cells also produce disease-associated cytokines in asthma. Increased levels of these immune cells and cytokines have been identified in clinical samples and their potential role in disease demonstrated in studies using mouse models of asthma. Clinical trials with inhibitors of cytokines such as interleukin (IL)-4, -5 and tumour necrosis factor-α have had success in some studies but not others. This may reflect the design of the clinical trials, including treatments regimes and the patient population included in these studies. IL-13, -9 and granulocyte-macrophage colony-stimulating factor are currently being evaluated in clinical trials or preclinically and the outcome of these studies is eagerly awaited. Roles for IL-25, -33, thymic stromal lymphopoietin, interferon-γ, IL-17 and -27 in the regulation of asthma are just emerging, identifying new ways to treat inflammation. Careful interpretation of results from mouse studies will inform the development and application of therapeutic approaches for asthma. The most effective approaches may be combination therapies that suppress multiple cytokines and a range of redundant and disconnected pathways that separately contribute to asthma pathogenesis. Astute application of these approaches may eventually lead to the development of effective asthma therapeutics. Here we review the current state of knowledge in the field.

Intravenous immunoglobulin attenuates airway hyperresponsiveness in a murine model of allergic asthma

BACKGROUND

Intravenous immunoglobulin (IVIG) has potent anti-inflammatory and immune-modulating properties. IVIG has been utilized as a steroid-sparing agent in severe asthma, but the results of clinical trials have been conflicting.

OBJECTIVE

To determine whether IVIG is able to attenuate bronchial reactivity, pulmonary inflammation and T cell function using a murine model of allergic airways disease.

METHODS

BALB/c or C57BL/6 mice were sensitized to ovalbumin (OVA) or a phosphate-buffered saline control using local nasal sensitization, and then received five intranasal challenges on days 28-32 before sacrifice. Mice were treated intraperitoneally with either IVIG (1-2 g/kg) or equivalent human serum albumin 24 h before the first OVA challenge. Bronchial reactivity to methacholine was examined using the FlexiVent small animal ventilator. We evaluated pulmonary histology, mRNA from lung digests for T-helper type 2 (Th2)-related genes and bronchoalveolar lavage for cell counts and cytokines. Splenocytes were utilized to study OVA-induced cell proliferation, cytokine production and dendritic cell maturation.

RESULTS

IVIG markedly attenuated the perivascular and peribronchial pulmonary inflammation, and decreased bronchial hyperresponsiveness to methacholine. IVIG treatment of splenocytes from sensitized animals diminished cellular proliferation to OVA, whereas IVIG treatment in vivo markedly attenuated OVA-driven splenocyte proliferation. This is accompanied by diminished IL-13 and TNF-α levels in splenocyte culture, decreased expression of Jagged-1, increased Delta-4 and decreased GATA-3 mRNA levels, signs that IVIG has suppressed the expected Th2 response that accompanies repeated allergen exposure. Increased regulatory T cells were found in draining pulmonary lymph nodes in IVIG-treated mice but not in controls.

CONCLUSIONS AND CLINICAL RELEVANCE

IVIG was effective in ameliorating allergic airway disease in our model. IVIG may be a promising adjunct therapy requiring further study for patients with severe asthma.

The plant extract Isatis tinctoria L. extract (ITE) inhibits allergen-induced airway inflammation and hyperreactivity in mice

BACKGROUND

The herbal Isatis tinctoria extract (ITE) inhibits the inducible isoform of cyclooxygenase (COX-2) as well as lipoxygenase (5-LOX) and therefore possesses anti-inflammatory properties. The extract might also be useful in allergic airway diseases which are characterized by chronic inflammation.

METHODS

ITE obtained from leaves by supercritical carbon dioxide extraction was investigated in ovalbumin (OVA) immunised BALB/c mice given intranasally together with antigen challenge in the murine model of allergic airway disease (asthma) with the analysis of the inflammatory and immune parameters in the lung.

RESULTS

ITE given with the antigen challenge inhibited in a dose related manner the allergic response. ITE diminished airway hyperresponsiveness (AHR) and eosinophil recruitment into the bronchoalveolar lavage (BAL) fluid upon allergen challenge, but had no effect in the saline control mice. Eosinophil recruitment was further assessed in the lung by eosinophil peroxidase (EPO) activity at a dose of 30 microg ITE per mouse. Microscopic investigations revealed less inflammation, eosinophil recruitment and mucus hyperproduction in the lung in a dose related manner. Diminution of AHR and inflammation was associated with reduced IL-4, IL-5, and RANTES production in the BAL fluid at the 30 microg ITE dose, while OVA specific IgE and eotaxin serum levels remained unchanged.

CONCLUSION

ITE, which has been reported inhibiting COX-2 and 5-LOX, reduced allergic airway inflammation and AHR by inhibiting the production of the Th2 cytokines IL-4 and IL-5, and RANTES.

Petasites extract Ze 339 (PET) inhibits allergen-induced Th2 responses, airway inflammation and airway hyperreactivity in mice

BACKGROUND

The herbal Petasites hybridus (butterbur) extract (Ze 339, PET) is known to have leukotriene inhibiting properties, and therefore might inhibit allergic diseases.

METHODS

The effect of PET was investigated in ovalbumin (OVA) immunized BALB/c mice given intranasally together with antigen challenge in the murine model of allergic airway disease (asthma) with the analysis of the inflammatory and immune parameters in the lung.

RESULTS

PET given with the antigen challenge inhibited the allergic response. PET inhibited airway hyperresponsiveness (AHR) and eosinophil recruitment into the bronchoalveolar lavage (BAL) fluid upon allergen challenge, but had no effect in the saline control mice. Eosinophil recruitment was further assessed in the lung by eosinophil peroxidase (EPO) activity at a concentration of 100 microg PET. Microscopic investigations revealed less inflammation, eosinophil recruitment and mucus hyperproduction in the lung with 100 microg PET. Diminution of AHR and inflammation was associated with reduced IL-4, IL-5 and RANTES production in the BAL fluid with 30 microg PET, while OVA specific IgE and eotaxin serum levels remained unchanged.

CONCLUSION

PET, which has been reported to inhibit leukotriene activity, reduced allergic airway inflammation and AHR by inhibiting the production of the Th2 cytokines IL-4 and IL-5, and RANTES.

Interleukin-18-deficient mice exhibit diminished chronic inflammation and airway remodelling in ovalbumin-induced asthma model

Interleukin (IL)-18, which is produced by activated monocytes/macrophages and airway epithelial cells, is suggested to contribute to the pathophysiology of asthma by modulating airway inflammation. However, the involvement of IL-18 on modulating chronic airway inflammation and airway remodelling, which are characterized in a refractory asthma model exposed to long-term antigen, has not been investigated sufficiently. We examined the role of IL-18 in chronic airway inflammation and airway remodelling by long-term antigen exposure. IL-18-deficient and C57BL/6-wild-type mice were sensitized by ovalbumin (OVA) and were then exposed to aerosolized OVA twice a week for 12 weeks. We assessed airway inflammation by assessing the infiltration of cells into the airspace and lung tissues, and airway remodelling by airway mucus expression, peribronchial fibrosis and smooth muscle thickness. In IL-18-deficient mice, when exposed to OVA, the total cells and neutrophils of the bronchoalveolar lavage fluid (BALF) were diminished, as were the number of infiltrated cells in the lung tissues. IL-18-deficient mice exposed to OVA after 12 weeks showed significantly decreased levels of interferon (IFN)-gamma, IL-13 and transforming growth factor (TGF)-beta1 in the BALF. The airway hyperresponsiveness to acetyl-beta-methacholine chloride was inhibited in IL-18-deficient mice in comparison with wild-type mice. In addition, IL-18-deficient mice exposed to OVA had fewer significant features of airway remodelling. These findings suggest that IL-18 may enhance chronic airway inflammation and airway remodelling through the production of IFN-gamma, IL-13 and TGF-beta1 in the OVA-induced asthma mouse model.

CRTH2 plays an essential role in the pathophysiology of Cry j 1-induced pollinosis in mice

PGD(2) is the major prostanoid produced during the acute phase of allergic reactions. Two PGD(2) receptors have been isolated, DP and CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells), but whether they participate in the pathophysiology of allergic diseases remains unclear. We investigated the role of CRTH2 in the initiation of allergic rhinitis in mice. First, we developed a novel murine model of pollinosis, a type of seasonal allergic rhinitis. Additionally, pathophysiological differences in the pollinosis were compared between wild-type and CRTH2 gene-deficient mice. An effect of treatment with ramatroban, a CRTH2/T-prostanoid receptor dual antagonist, was also determined. Repeated intranasal sensitization with Cry j 1, the major allergen of Cryptomeria japonica pollen, in the absence of adjuvants significantly exacerbated nasal hyperresponsive symptoms, Cry j 1-specific IgE and IgG1 production, nasal eosinophilia, and Cry j 1-induced in vitro production of IL-4 and IL-5 by submandibular lymph node cells. Additionally, CRTH2 mRNA in nasal mucosa was significantly elevated in Cry j 1-sensitized mice. Following repeated intranasal sensitization with Cry j 1, CRTH2 gene-deficient mice had significantly weaker Cry j 1-specific IgE/IgG1 production, nasal eosinophilia, and IL-4 production by submandibular lymph node cells than did wild-type mice. Similar results were found in mice treated with ramatroban. These results suggest that the PGD(2)-CRTH2 interaction is elevated following sensitization and plays a proinflammatory role in the pathophysiology of allergic rhinitis, especially pollinosis in mice.

Systemic and local eosinophil inflammation during the birch pollen season in allergic patients with predominant rhinitis or asthma

Background

The aim of the study was to investigate inflammation during the birch pollen season in patients with rhinitis or asthma.

Methods

Subjects with birch pollen asthma (n = 7) or rhinitis (n = 9) and controls (n = 5) were studied before and during pollen seasons. Eosinophils (Eos), eosinophil cationic protein (ECP) and human neutrophil lipocalin were analysed.

Results

Allergic asthmatics had a larger decline in FEV1 after inhaling hypertonic saline than patients with rhinitis (median) (-7.0 vs.-0.4%, p = 0.02). The asthmatics had a lower sesonal PEFR than the rhinitis group. The seasonal increase in B-Eos was higher among patients with asthma (+0.17 × 109/L) and rhinitis (+0.27 × 109/L) than among controls (+0.01 × 109/L, p = 0.01). Allergic asthmatics and patients with rhinitis had a larger increase in sputum ECP (+2180 and +310 μg/L) than the controls (-146 μg/L, p = 0.02). No significant differences in inflammatory parameters were found between the two groups of allergic patients.

Conclusion

Patients with allergic asthma and rhinitis have the same degree of eosinophil inflammation. Despite this, only the asthmatic group experienced an impairment in lung function during the pollen season.

Inhibition of experimental allergic airways disease by local application of a cell-penetrating dominant-negative STAT-6 peptide

Allergic airways disease is initiated and perpetuated by an aberrant Th2 inflammatory response regulated in part by the cytokines IL-4 and IL-13, each of which induces activation of the STAT-6 transcription factor. Data from murine models indicate that the clinical manifestations of acute asthma are STAT-6 dependent, and thus, STAT-6 is a target for drug development in allergic airways disease. We designed a novel chimeric peptide (STAT-6 inhibitory peptide (STAT-6-IP)) comprised of a sequence predicted to bind to and inhibit STAT-6, fused to a protein transduction domain, to facilitate cellular uptake of the STAT-6-binding peptide. Our data demonstrate that the STAT-6-IP inhibited OVA-induced production of Th2 cytokines IL-4 and IL-13 in vitro. In contrast, the STAT-6-IP did not affect production of IFN-gamma, demonstrating specificity for Th2 cytokine inhibition. Following intranasal administration, the STAT-6-IP was localized to epithelial cells in the airways. Finally, in in vivo murine models of allergic rhinitis and asthma, intranasal delivery of the STAT-6-IP inhibited OVA-induced lung inflammation and mucus production as well as accumulation of eosinophils and IL-13 in bronchoalveolar lavage fluid and OVA-dependent airway hyperresponsiveness. Together these data show that local application of cell-penetrating peptide inhibitors of STAT-6 has significant potential for the treatment of allergic rhinitis and asthma.

Allergic Rhinitis and Onset of Bronchial Hyperresponsiveness

RATIONALE

Patients with allergic rhinitis have more frequent bronchial hyperresponsiveness (BHR) in cross-sectional studies.

OBJECTIVES

To estimate the changes in BHR in nonasthmatic subjects with and without allergic rhinitis during a 9-year period.

METHODS

BHR onset was studied in 3,719 subjects without BHR at baseline, who participated in the follow-up of the European Community Respiratory Health Survey.

MEASUREMENTS AND MAIN RESULTS

BHR was defined as a >or=20% decrease in FEV(1) for a maximum dose of 1 mg of methacholine. Allergic rhinitis was defined as having a history of nasal allergy and positive specific IgE (>or=0.35 IU/ml) to pollen, cat, mites, or Cladosporium. The cumulative incidence of BHR was 9.7% in subjects with allergic rhinitis and 7.0% in subjects with atopy but no rhinitis, compared with 5.5% in subjects without allergic rhinitis and atopy (respective odds ratios [OR] and their 95% confidence intervals [95% CI] for BHR onset, 2.44 [1.73-3.45]; and 1.35 [0.86-2.11], after adjustment for potential confounders including sex, smoking, body mass index and FEV(1)). Subjects with rhinitis sensitized exclusively to cat or to mites were particularly at increased risk of developing BHR (ORs [95% CI], 7.90 [3.48-17.93] and 2.84 [1.36-5.93], respectively). Conversely, in subjects with BHR at baseline (n = 372), 35.3% of those with allergic rhinitis, compared with 51.8% of those without rhinitis had no more BHR at follow-up (OR [95% CI], 0.51 [0.33-0.78]). BHR "remission" was more frequent in patients with rhinitis treated by nasal steroids than in those not treated (OR [95% CI], 0.33 [0.14-0.75]).

CONCLUSIONS

Allergic rhinitis was associated with increased onset of BHR, and less chance for remission except in those treated for rhinitis.

The impact of comorbid atopic disease on asthma: clinical expression and treatment

Clinically, asthma and allergic rhinitis involve separate regions of the respiratory tract while representing a common underlying inflammatory syndrome. Much evidence supports an epidemiologic association between the diseases, paranasal sinus involvement in both conditions, and parallel relationship in severity and treatment outcomes. Pathophysiologic mechanisms, including immunoglobulin E (IgE)- mediated inflammation, are also shared. Blocking IgE with the recombinant humanized monoclonal antibody omalizumab demonstrated clinical efficacy in patients with upper and lower airway diseases. IgE blockade, leukotriene modulation, and B-cell depletion therapy have all exhibited success in chronic inflammation, reinforcing and expanding the beneficial role of immunomodulation of global mediators.

Efficacy of IL-13 neutralization in a sheep model of experimental asthma

IL-13 contributes to airway hyperresponsiveness, mucus secretion, inflammation, and fibrosis, suggesting that it plays a central role in asthma pathogenesis. Neutralization of IL-13 with sIL-13Ralpha2-Fc (sIL-13R) reduces allergen-induced airway responses in rodent models of respiratory disease, but its efficacy in a large animal model has not been previously reported. In this study, we determined whether two different strategies for IL-13 neutralization modified experimental asthma in sheep. Sheep with natural airway hypersensitivity to Ascaris suum antigen were treated intravenously either with sIL-13R, a strong antagonist of sheep IL-13 bioactivity in vitro, or with IMA-638 (IgG1, kappa), a humanized antibody to human IL-13. Higher doses of IMA-638 were used because, although it is a potent antagonist of human IL-13, this antibody has 20 to 30 times lower binding and neutralization activity against sheep IL-13. Control animals received human IgG of irrelevant specificity. Sheep were treated 24 h before inhalation challenge with nebulized A. suum. The effects on antigen-induced early and late bronchial responses, and antigen-induced hyperresponsiveness, were assessed. Both sIL-13R and IMA-638 provided dose-dependent inhibition of the antigen-induced late responses and airway hyperresponsiveness. The highest dose of IMA-638 also reduced the early phase response. These findings suggest that IL-13 contributes to allergen-induced airway responses in this sheep model of asthma, and that neutralization of IL-13 is an effective strategy for blocking these A. suum-induced effects.