Beneficial effect of anti-interleukin-33 on the murine model of allergic inflammation of the lower airway

Strategies Targeting Type 2 Inflammation: From Monoclonal Antibodies to JAK-Inhibitors

Bronchial asthma and its frequent comorbidity chronic rhinosinusitis (CRS), are characterized by an inflammatory process at lower and upper respiratory tract, with a variability in terms of clinical presentations (phenotypes) and distinct underpin pathophysiological mechanisms (endotypes). Based on the characteristics of inflammation, bronchial asthma can be distinguished into type 2 (eosinophilic) or nontype 2 (noneosinophilic) endotypes. In type 2 asthma endotype, the pathogenic mechanism is sustained by an inflammatory process driven by Th2 cells, type 2 innate lymphoid cells (ILC2) and type 2 cytokines, which include interleukin (IL)-4, IL-5, IL-9 and IL-13. The definition of asthma and chronic rhinusinusitis phenotype/endotype is crucial, taking into account the availability of novel biologic agents, such as monoclonal antibodies targeting the classical type 2 cytokines. Recently, new therapeutic strategies have been proposed and analyzed in preliminary clinical trials. Among them Janus kinase (JAK) inhibitors, now largely used for the treatment of other chronic inflammatory diseases such as rheumatoid arthritis and inflammatory bowel diseases, is receiving great relevance. The rationale of this strategy derives from the data that JAK is a tyrosine kinase involved in the signaling of T cell receptor and of several cytokines that play a role in allergic respiratory disease, such as IL-2, IL-4 and IL-9. In this review, we discuss whether treatment with biological agents and JAK inhibitors may be equally effective in controlling type 2 inflammatory process in both asthma and CRS.

Novel Anti-Cytokine Strategies for Prevention and Treatment of Respiratory Allergic Diseases

Asthma is a heterogeneous inflammatory disease characterized by airflow obstruction, wheezing, eosinophilia and neutrophilia of the airways. Identification of distinct inflammatory patterns characterizing asthma endotypes led to the development of novel therapeutic approaches. Cytokine or cytokine receptor targeting by therapeutic antibodies, such as anti-IL-4 and anti-IL-5, is now approved for severe asthma treatment. However, the complexity of cytokine networks in asthma should not be underestimated. Inhibition of one pro-inflammatory cytokine may lead to perturbed expression of another pro-inflammatory cytokine. Without understanding of the underlying mechanisms and defining the molecular predictors it may be difficult to control cytokine release that accompanies certain disease manifestations. Accumulating evidence suggests that in some cases a combined pharmacological inhibition of pathogenic cytokines, such as simultaneous blockade of IL-4 and IL-13 signaling, or blockade of upstream cytokines, such as TSLP, are more effective than single cytokine targeting. IL-6 and TNF are the important inflammatory mediators in the pathogenesis of asthma. Preliminary data suggests that combined pharmacological inhibition of TNF and IL-6 during asthma may be more efficient as compared to individual neutralization of these cytokines. Here we summarize recent findings in the field of anti-cytokine therapy of asthma and discuss immunological mechanisms by which simultaneous targeting of multiple cytokines as opposed to targeting of a single cytokine may improve disease outcomes.

IL-33/ST2 signaling modulates Afghanistan particulate matter induced airway hyperresponsiveness in mice

Increased symptoms of asthma-like respiratory illnesses have been reported in soldiers returning from tours of duty in Afghanistan. Inhalation of desert particulate matter (PM) may contribute to this deployment-related lung disease (DRLD), but little is known about disease mechanisms. The IL-33 signaling pathway, including its receptor ST2, has been implicated in the pathogenesis of lung diseases including asthma, but its role in PM-mediated airway dysfunction has not been studied. The goal of this study was to investigate whether IL-33/ST2 signaling contributes to airway dysfunction in preclinical models of lung exposure to Afghanistan PM (APM). Wild-type (WT) and ST2 knockout (KO) mice on the BALB/C background were oropharyngeally instilled with a single dose of saline or 50 μg of APM in saline. Airway hyperresponsiveness (AHR) and inflammation were assessed after 24 h. In WT mice, a single APM exposure induced AHR and neutrophilic inflammation. Unlike the WT mice, ST2 KO mice that lack the receptor for IL-33 did not demonstrate AHR although airway neutrophilic inflammation was comparable to the WT mice. Oropharyngeal delivery of a soluble ST2 decoy receptor in APM-exposed WT mice significantly blocked AHR. Additional data in mouse tracheal epithelial cell and lung macrophage cultures demonstrated a role of APM-induced IL-33/ST2 signaling in suppression of regulator of G protein signaling 2 (RGS2), a gene known to protect against bronchoconstriction. We present for the first time that APM may increase AHR, one of the features of asthma, in part through the IL-33/ST2/RGS2 pathway.

A role for early oral exposure to house dust mite allergens through breast milk in IgE-mediated food allergy susceptibility

BACKGROUND

Successful prevention of food allergy requires the identification of the factors adversely affecting the capacity to develop oral tolerance to food antigen in early life.

OBJECTIVES

This study sought to determine whether oral exposure to Dermatophagoides pteronyssinus through breast milk affects gut mucosal immunity with long-term effects on IgE-mediated food allergy susceptibility.

METHODS

Gut immunity was explored in 2-week-old mice breast-fed by mothers exposed to D pteronyssinus, protease-inactivated D pteronyssinus, or to PBS during lactation. We further analyzed oral tolerance to a bystander food allergen, ovalbumin (OVA). In a proof-of-concept study, Der p 1 and OVA levels were determined in 100 human breast milk samples and the association with prevalence of IgE-mediated egg allergy at 1 year was assessed.

RESULTS

Increased permeability, IL-33 levels, type 2 innate lymphoid cell activation, and T_h2 cell differentiation were found in gut mucosa of mice nursed by mothers exposed to D pteronyssinus compared with PBS. This pro-T_h2 gut mucosal environment inhibited the induction of antigen-specific FoxP3 regulatory T cells and the prevention of food allergy by OVA exposure through breast milk. In contrast, protease-inactivated D pteronyssinus had no effect on offspring gut mucosal immunity. Based on the presence of Der p 1 and/or OVA in human breast milk, we identified groups of lactating mothers, which mirror the ones found in mice to be responsible for different egg allergy risk.

CONCLUSIONS

This study highlights an unpredicted potential risk factor for the development of food allergy, that is, D pteronyssinus allergens in breast milk, which disrupt gut immune homeostasis and prevents oral tolerance induction to bystander food antigen through their protease activity.

Antialarmins for treatment of asthma: future perspectives

PURPOSE OF REVIEW

Recent studies have highlighted the role of alarmins in asthma pathophysiology and tested the roles of these cytokines in asthmatic patients. This review will discuss the recent advances in the role of alarmins in asthma and the potential of future targeted therapies in asthma.

RECENT FINDINGS

Epithelial-derived cytokines can be released upon exposure to external stimuli, causing damage to the epithelial barrier and resulting in tissue inflammation. Of these cytokines, IL-25, IL-33 and thymic stromal lymphopoeitin (TSLP), have been associated with asthma. These alarmins are all not only overexpressed in asthmatic airways, particularly in airway epithelial cells, but also in other structural and immune cells. Furthermore, all three alarmins drive type-2 pro-inflammatory responses in several immune cells that have been identified as key players in the pathogenesis of asthma, including innate lymphoid type-2 cells. Clinical trials testing therapeutics that block pathways of the alarmins are in progress.

SUMMARY

To-date, only TSLP blockade has been reported in human clinical trials, and this approach has shown efficacy in asthmatic patients. Current body of evidence suggests that alarmins are useful upstream targets for treatment of asthma.

Dichotomous function of IL-33 in health and disease: From biology to clinical implications

Interleukin (IL)-33 is a cytokine that is released from epithelial and endothelial cells at barrier surfaces upon tissue stress or damage to operate as an alarmin. IL-33 has been primarily implicated in the induction of T helper (Th) 2 type immune responses. Therefore, IL-33 has attracted a lot of interest as a potential therapeutic target in asthma and other allergic diseases. Over the years, it has become clear that IL-33 has a much broader activity and also contributes to Th1 immunity, expanding the possibilities for therapeutic modulation of IL-33 activity to multiple inflammatory diseases. However, more recently IL-33 has also been shown to mediate immunosuppression and tissue repair by activating regulatory T cells (Treg) and promoting M2 macrophage polarization. These pleiotropic activities of IL-33 illustrate the need for a tight molecular regulation of IL-33 activity, and have to be taken into account when IL-33 or its receptor is targeted for therapeutic modulation. Here we review the multiple molecular mechanisms that regulate IL-33 activity and describe how IL-33 can shape innate and adaptive immune responses by promoting Th1, Th2 and Treg function. Finally, we will discuss the possibilities for therapeutic modulation of IL-33 signaling as well as possible safety issues.

Comparison of Interleukin-33 Serum Levels in Asthmatic Patients with a Control Group and Relation with the Severity of the Disease

BACKGROUND

The relation between interleukin-33 (IL-33) and asthma is not precisely known yet. The present study set to compare the serum level of IL-33 in patients with asthma and controls and study the relation with the severity of disease.

METHODS

The serum level of IL-33 and total IgE in 89 asthmatic patients and 57 controls were analyzed. The association of levels of IL-33 with the severity of disease, levels of total IgE, measures of spirometry (forced expiratory volume in 1 s [FEV1]), age, sex, presence or absence of other allergic diseases, and the disease duration was evaluated.

RESULTS

Higher levels of IL-33 and total IgE were detected in asthmatic patients compared with controls (P = 0.0001 and P = 0.008, respectively). In the asthmatic group, a significant direct association of IL-33 with age (P = 0.02, R = 0.23) and with total IgE level (P = 0.003, R = 0.31) were observed, but there was no relationship between other variables. Comparison of mean level of IL-33 in different asthma groups concerning the disease severity showed the statistically significant difference between them and a significant increased serum level of total IgE was observed in more severe disease. The results showed a significant negative correlation between FEV1 and total IgE (P = 0.028, R = -0.23) and IL-33 level (P = 0.0001, R = -0.83).

CONCLUSIONS

IL-33 is suggested as a new inflammatory marker of severe and refractory asthma. Therefore, it may be a unique therapeutic target in these patients.

The Potential for Emerging Microbiome-Mediated Therapeutics in Asthma

PURPOSE OF REVIEW

In terms of immune regulating functions, analysis of the microbiome has led the development of therapeutic strategies that may be applicable to asthma management. This review summarizes the current literature on the gut and lung microbiota in asthma pathogenesis with a focus on the roles of innate molecules and new microbiome-mediated therapeutics.

RECENT FINDINGS

Recent clinical and basic studies to date have identified several possible therapeutics that can target innate immunity and the microbiota in asthma. Some of these drugs have shown beneficial effects in the treatment of certain asthma phenotypes and for protection against asthma during early life. Current clinical evidence does not support the use of these therapies for effective treatment of asthma. The integration of the data regarding microbiota with technologic advances, such as next generation sequencing and omics offers promise. Combining comprehensive bioinformatics, new molecules and approaches may shape future asthma treatment.

Glucosamine has an antiallergic effect in mice with allergic asthma and rhinitis

BACKGROUND

Glucosamine (GlcN) is generally used as a dietary supplement because of its antiinflammatory effects. We evaluated the antiallergic effect of GlcN in mice with allergic asthma and rhinitis.

METHODS

Thirty-two mice were allocated equally into 4 groups (n = 8). In group A (control), we performed intraperitoneal/intranasal challenge using sterile saline. In group B (asthma/rhinitis), we used ovalbumin for intraperitoneal/intranasal challenge to induce allergic asthma and rhinitis. In groups C and D (GlcN treatment), mice were given 1% and 5% GlcN throughout the period of ovalbumin challenge, respectively. We measured serum total and ovalbumin-specific immunoglobulin E (IgE), cytokine titers (interleukin-1, -4, -5, -6, -10, and -17; tumor necrosis factor-α; and interferon-γ), and the number of inflammatory cells (eosinophils, neutrophils, lymphocytes) in bronchoalveolar lavage (BAL) fluid. We also performed histopathologic examination of the lung and nasal cavity. Finally, we performed real-time polymerase chain reaction for the genes Bcl-2, EC-SOD, VEGF, caspase-3, Bax, COX-2, Hif-1α, and heme oxygenase-1.

RESULTS

Compared with group B, group D had significant serum total and ovalbumin-specific IgE decreases after GlcN treatment (p < 0.05). Titers for IL-4, IL-5, IL-6, and IL-17 in BAL fluid were significantly decreased in group D (p < 0.05). Eosinophils in BAL fluid were significantly decreased in group D compared with group B (p < 0.05). Groups C and D showed significant improvement of inflammation compared with group B. Group D had significant downregulation of EC-SOD, Bax, Hif-1α, and heme oxygenase-1 compared with group B.

CONCLUSION

GlcN had a significant antiallergic effect in mice with allergic asthma and rhinitis.

Anti-allergic effect of luteolin in mice with allergic asthma and rhinitis

AIM OF THE STUDY

We aimed to evaluate the anti-allergic effect of luteolin treatment in mice with allergic asthma and rhinitis.

MATERIAL AND METHODS

Thirty-two BALB/c mice (n = 8 for each group) were used. Mice in group A (nonallergic group) were exposed to saline, while those in Group B (allergic group) were exposed to ovalbumin (OVA) intraperitoneal (i.p.) injection and intranasal (i.n.) challenge. Null treatment group (Group C) received sterile saline (150 μl) i.p. injection, 30 minutes before each i.n. challenge. Finally, the treatment group (Group D) received luteolin (0.1 mg/kg) by i.p. injection, 30 minutes before each i.n. challenge. We evaluated the number of inflammatory cells including eosinophils, neutrophils and lymphocytes in bronchoalveolar lavage (BAL) fluid, the titers of IL-4, IL-5 and IL-13 in lung homogenate, and we also evaluated histopathologic findings, including infiltration of inflammatory cells into the pulmonary parenchyma and nasal mucosa.

RESULTS

After the OVA challenge, the number of eosinophils, neutrophils and lymphocytes in BAL fluid was significantly increased in group B, compared to group A (p < 0.001). Mice in group C had no significant difference (p > 0.05). On the other hand, group D showed a significant decrease in all inflammatory cells compared to group B (p < 0.05). Also, group D showed a significant decrease in IL-4, IL-5 and IL-13 in their lung homogenate compared to groups B and C (p < 0.05). Group D also showed a significant decrease in inflammatory cell infiltration after luteolin treatment (p < 0.05).

CONCLUSION

Luteolin had an anti-allergic effect in a murine model of allergic asthma and rhinitis.

Anti-interleukin-33 Reduces Ovalbumin-Induced Nephrotoxicity and Expression of Kidney Injury Molecule-1

Purpose:

To evaluate the effect of anti-interleukin-33 (anti-IL-33) on a mouse model of ovalbumin (OVA)-induced acute kidney injury (AKI).

Methods:

Twenty-four female BALB/c mice were assigned to 4 groups: group A (control, n=6) was administered sterile saline intraperitoneally (i.p.) and intranasally (i.n.); group B (allergic, n=6) was administered i.p./i.n. OVA challenge; group C (null treatment, n=6) was administered control IgG i.p. before OVA challenge; and group D (anti-IL-33, n=6) was pretreated with 3.6 µg of anti-IL-33 i.p. before every OVA challenge. The following were evaluated after sacrifice: serum blood urea nitrogen and creatinine levels, Kidney injury molecule-1 gene (Kim-1) and protein (KIM-1) expression in renal parenchyma, and expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), phosphorylated endothelial NOS (p-eNOS), and phosphorylated AMP kinase (p-AMPK) proteins in renal parenchyma.

Results:

After OVA injection and intranasal challenge, mice in groups B and C showed significant increases in the expression of Kim-1 at both the mRNA and protein levels. After anti-IL-33 treatment, mice in group D showed significant Kim-1 down-regulation at the mRNA and protein levels. Group D also showed significantly lower COX-2 protein expression, marginally lesser iNOS expression than groups B and C, and p-eNOS and p-AMPK expression at baseline levels.

Conclusions:

Kim-1 could be a useful marker for detecting early-stage renal injury in mouse models of OVA-induced AKI. Further, anti-IL-33 might have beneficial effects on these mouse models.

Antiallergic effects of anti-interleukin-33 are associated with suppression of immunoglobulin light chain and inducible nitric oxide synthase

OBJECTIVE

We aimed to find novel genes that are significantly induced in allergic mice and that are significantly downregulated with anti-interleukin (IL) 33 treatment.

METHODS

Thirty-six mice were allocated into each of group A (intraperitoneal [i.p.]) sensitized and intranasally challenged to saline solution), group B (sensitized and challenged to ovalbumin), group C (sensitized and challenged with ovalbumin, and null treatment with i.p. saline solution), and group D (sensitized and challenged with ovalbumin, and treatment with anti-IL-33 i.p. injection). We counted the number of nose-scratching in 10 minutes, serum ovalbumin-specific immunoglobulin E (IgE), and titers of cytokines (IL-1, IL-4, IL-5, IL-10, IL-13) in bronchoalveolar lavage fluid. By using one whole lung from each mouse, we performed microarray analysis and real-time polymerase chain reaction.

RESULTS

group D showed a significantly reduced nose-scratching events and lower serum ovalbumin-specific IgE compared with groups B and C. All the cytokines in the bronchoalveolar lavage fluid were significantly decreased after anti-IL-33 treatment. Microarray analysis revealed that group B (immunoglobulin free light chain [IgFLC], 89.1 times; nitric oxide synthase [NOS] 2, 11.5 times) and group C (IgFLC, 141.6 times; NOS2, 11.7 times) had significantly increased expression of IgFLC and NOS2 genes compared with group A. After anti-IL-33 treatment, group D showed significantly decreased expression of both IgFLC (49.3 times) and NOS2 (6.5 times). In real-time polymerase chain reaction, groups B and C had significantly increased expression of these genes (IgFLC, 10.4 times and 29 times, respectively; NOS2, 3.8 times and 4.5 times, respectively). After treatment, group D showed significantly decreased expression of IgFLC (5.0 times) and NOS2 (2.5 times).

CONCLUSION

The antiallergic effect of anti-IL-33 can be explained by suppression of IgFLC and NOS2 in a murine model of allergic rhinitis.

Vaccination against IL-33 Inhibits Airway Hyperresponsiveness and Inflammation in a House Dust Mite Model of Asthma

In several clinical and experimental studies IL-33 and its receptor have been found to play important roles in the development of asthma and allergic airway inflammation. We evaluated the effects of vaccination against IL-33 in a mouse model of airway inflammation induced by house dust mite (HDM) allergen. Balb/c mice received the IL-33 vaccine subcutaneously, followed by intranasal administration of HDM for up to six weeks. Vaccination against IL-33 induced high titers of specific anti-IL-33 IgG antibodies that inhibited HDM-induced airway hyperresponsiveness (AHR) in the conducting airways and tissue damping. The vaccination also attenuated the HDM-induced elevation in the numbers of eosinophils in bronchoalveolar lavage fluid (BALF) and suppressed the accumulation of inflammatory cells in the airways. Furthermore, the levels of IL-17A, IL-25, IL-33 and TSLP in lung tissue homogenates were reduced by vaccination against IL-33. These observations demonstrate that vaccination against IL-33 inhibits HDM-induced development of AHR, airway inflammation and production of inflammatory cytokines. The results also indicate an important role of IL-33 in the regulation of AHR of the distal lung compartments. Thus, administration of such a vaccine is potentially an effective therapeutic tool for treating allergic asthma.

IL-33 promotes the induction of immunoglobulin production after inhalation of house dust mite extract in mice

BACKGROUND

The initial immune response to house dust mite (HDM) is orchestrated by an interplay between epithelial cells (ECs) and dendritic cells (DCs). Innate cytokines released by HDM-exposed ECs activate airway DCs and effector inflammatory cells, which together induce a HDM-specific Th2 cell response. Here, we investigate the respective roles of DCs and IL-33 in sensitization to HDM.

METHOD

Balb/c mice were exposed via the airways to different HDM extracts, differing in at least endotoxin levels [Lotox (LT) and HiTox (HT)]. Alternatively, HDM-pulsed DCs in the presence or absence of additional LT-HDM, or administration of LT-HDM plus recombinant IL-33, were intratracheally (i.t.) administered to induce allergic airway inflammation. Eosinophil recruitment, cytokine production, serum immunoglobulins, and airway histology were analyzed.

RESULTS

Direct exposure of airways with HT-HDM induced an eosinophilic airway inflammation, Th2 cytokine production, and an increase in total IgE and HDM IgG1, while LT-HDM was not able to do so. In contrast, i.t. instillation of LT-HDM-pulsed DCs induced a similar airway inflammation, mucus production, and cytokine production, but IgE or HDM IgG1 was not induced. Administration of HDM-pulsed DCs together with LT-HDM, to supply B cells with unprocessed antigen, was not sufficient to induce antibody production. Simultaneous administration of recombinant IL-33 with LT-HDM induced an antibody response, besides a cellular immune response.

CONCLUSION

These results demonstrate that HDM-pulsed DCs were able to drive a Th2 response but that IL-33 was needed to induce a humoral immune response to a single inhalational challenge to HDM.

Thymic stromal lymphopoietin: a central regulator of allergic asthma

INTRODUCTION

Epithelial cell-derived mediators have emerged as key players for instigating local remodeling and the associated cellular inflammation in asthmatic airways. In particular, the epithelial-derived cytokine, thymic stromal lymphopoietin (TSLP), has been identified as a master switch for allergic inflammation.

AREAS COVERED

TSLP is expressed by structural and immune cells at the site of allergen entry in the airways. Stimuli for release of TSLP include common triggers of asthma symptoms, and TSLP levels correlate with disease severity. TSLP regulates helper T cell 2 (Th2) humoral immunity through upregulating OX40L on dendritic cells (DCs), which drives Th2 lymphocytes; however, activation of several other cells by TSLP also supports the development of Th2 inflammation. Animal models of asthma demonstrate that increased levels of TSLP can induce many of the characteristics of asthma.

EXPERT OPINION

The work conducted to date supports a critical role of TSLP in the pathogenesis of allergic asthma. The first clinical trial to block the downstream effects of OX40L has shown reduced levels of circulating IgE and airway eosinophils, confirming the importance of TSLP-induced OX40L levels on DCs. Clinical trials with TSLP blockade are underway and will unequivocally confirm whether TSLP is indeed a key driver of allergic inflammation in asthma.

Exposure to hypergravity increases serum interleukin-5 and pulmonary infiltration in mice with allergic asthma

Objective

We evaluated the effect of acute hypergravity (HG) on the immune response in a murine model of allergic asthma.

Material and methods

Twenty-eight BALB/c mice were used. Group A (control group, n = 7) mice were sensitized and challenged with normal saline. Group B (control HG exposure group, n = 7) mice were sensitized, challenged with saline, and exposed to acute HG (+10 Gz) for 4 hours. Group C (asthma group, n = 7) mice were challenged with intraperitoneal and intranasal ovalbumin (OVA) to induce asthma. Group D (asthma HG exposure group, n = 7) mice were exposed to HG for 4 hours after the induction of asthma. We estimated the total and OVA-specific serum IgE, serum titers of various cytokines, and the number of eosinophils, neutrophils, and lymphocytes in bronchoalveolar lavage (BAL) fluid. Histopathology of the lung was also evaluated.

Results

The serum level of interleukin (IL)-5 was significantly higher in Group D (12.9 ±4.9 pg/ml) compared to that in Group C (4.7 ±6.5 pg/ml, p = 0.017). In BAL fluid, the number of neutrophils was significantly increased in Group D compared to Group C (p = 0.014). Group D demonstrated a higher infiltration of inflammatory cells (9973.8 ±1642.7 cells/mm²) compared to Group C (7666.3 ±586.5 cells/mm², p = 0.017). This tendency of increase in infiltration was not significant in non-asthmatic animals (Group A: 4488.8 ±176.1 cells/mm² vs. Group B: 4946.3 ±513.7 cells/mm², p > 0.05).

Conclusions

Acute HG exacerbated the allergic response by increasing serum IL-5 levels and promoting pulmonary infiltration of inflammatory cells.

Additive anti-allergic effects of anti-interleukin-33 and anti-Siglec-F treatments in a murine model of allergic asthma

Background

Anti-interleukin-33 (anti-IL-33) and anti-Siglec-F antibodies have potent anti-allergic effects on murine allergic asthma and rhinitis and induce eosinophil apoptosis.

Objective

We aimed to determine whether post-sensitization with anti-IL-33/anti-Siglec-F treatments exhibited more potent effects compared to individual treatments in a murine allergic asthma model.

Material and methods

Twenty-five BALB/c mice were separated into five groups (n = 5): Group A (control), Group B (ovalbumin [OVA] challenge), Group C (OVA + anti-IL-33), Group D (OVA + anti-Siglec-F), and Group E (OVA + anti-IL-33 + anti-Siglec-F). Serum total/ OVA-specific IgE, bronchoalveolar lavage (BAL) inflammatory cells and cytokines (IL-4 and IL-5), histopathological lung properties, and airway hyperreactivity were compared.

Results

Ovalbumin challenge induced strong immune and inflammatory responses with > 6-fold IgE level increases; 10- to 25-fold BAL eosinophil, neutrophil, and lymphocyte count increases; and > 1.5-fold IL-4 and IL-5 level increases (p < 0.05). Whereas anti-IL-33 reduced neutrophil counts, anti-Siglec-F and anti-IL-33/anti-Siglec-F reduced both eosinophil and neutrophil counts (p < 0.05). Individual treatments reduced OVA-mediated bronchiolar infiltration by 50% (p <0.05). Ovalbumin challenge increased airway hyperreactivity by 4-fold (Group B; 2000.0 ±671.8% increase in Penh) compared to controls (Group A; 445.7 ±33.5% increase in Penh) (p = 0.016). The anti-IL-33 (Group C: 1579.4 ±973.6% increase in Penh) and anti-Siglec-F (Group D: 930.4 ±236.5%) groups demonstrated significantly reduced hyperreactivity (p = 0.029). Anti-IL-33/anti-Siglec-F therapy showed synergism towards neutrophil counts, IL-5 concentrations, bronchial infiltration, and hyperreactivity (p < 0.05).

Conclusions

Combination treatment with anti-IL-33/anti-Siglec-F had more potent anti-allergic effects, reducing eosinophilic infiltration through their additive effects in a murine allergic asthma model.

Therapeutic potential of combined anti-IL-1β IgY and anti-TNF-α IgY in guinea pigs with allergic rhinitis induced by ovalbumin

We have previously demonstrated that anti-IL-1β immunoglobulin yolk(IgY) inhibits pathological responses in allergic asthma guinea pigs induced by ovalbumin(OVA). This study aims to determine whether the combined blockade of IL-1β and TNF-α can more effectively inhibit allergic inflammation in allergic rhinitis(AR) guinea pigs induced by OVA. Healthy guinea pigs treated with saline were used as the healthy control. The AR guinea pigs induced by OVA were randomly divided into (1) the AR model group containing negative control animals treated with intranasal saline; (2) the 0.1% non-specific IgY treatment group treated with non-specific IgY; (3) the 0.1% anti-TNF-α IgY treatment group treated with 0.1% anti-TNF-α IgY; (4) the 0.1% anti-IL-1β IgY treatment group treated with 0.1% anti-IL-1β IgY; (5) the 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY treatment group treated with 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY; and (6) the fluticasone propionate treatment group treated with fluticasone propionate. Cytokines were measured using an enzyme-linked immunosorbent assay. The results showed that IL-1β, IL-5, IL-9, IL-13, IL-18, IL-22, IL-33, TNF-α, TGF-β1 and OVA-specific IgE levels in the peripheral blood (PB) and nasal lavage fluid (NLF) significantly decreased at 2h, 4h or 8h in the 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY treatment group compared to the AR model group and the 0.1% non-specific IgY treatment group (P<0.05). The data suggest that blockade of IL-1β and TNF-α by intranasal instillation of combined anti-IL-1β IgY and anti-TNF-α IgY could be a potential alternative strategy for preventing and treating allergic rhinitis.

Benzaldehyde suppresses murine allergic asthma and rhinitis

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

Blockade of IL-33/ST2 ameliorates airway inflammation in a murine model of allergic asthma

OBJECTIVE

Interleukin (IL)-33 is involved in the development of lung inflammation by inducing or amplifying Th2 type-mediated responses in various animal models of allergic asthma. The ST2 gene is a member of the IL-1 receptor family, producing a transmembrane form (ST2L) and a soluble secreted form (sST2). sST2 has been shown to block this IL-33/ST2 signaling pathway. This study aimed to investigate whether anti-IL-33 and sST2 reduced airway inflammation in a murine model of asthma.

METHODS

BALB/c mice were sensitized and challenged with ovalbumin (OVA), and the effect of sST2 and anti-IL-33 antibody on airway inflammation and airway hyperresponsiveness (AHR) was evaluated. Furthermore, we measured changes in various cytokines in the bronchoalveolar lavage (BAL) fluid when treated with sST2 or anti-IL-33.

RESULTS

We observed that anti-IL-33 antibody and sST2 exert a negative regulation on OVA-mediated allergic airway inflammation. Both treatments reduced total cell counts and eosinophil counts in BAL fluid and AHR to methacholine. The Th2 cytokines, such as IL-4, IL-5, and IL-13 in BAL fluid were also significantly decreased after both treatments. However, there were no changes in the level of TGF- ß1 and IL-10 after each treatment.

CONCLUSIONS

These results suggest that anti-IL-33 as well as sST2 have therapeutic potential for allergic asthma through inhibition of Th2 cytokine production.

Induced sputum levels of IL-33 and soluble ST2 in young asthmatic children

OBJECTIVE

Interleukin-33 is an IL-1 family cytokine which signals via its T1/ST2 receptor, and acts as a key regulator of inflammation, notably the type-2 response implicated in asthma. This study aims to measure the expression of soluble ST2 (sST2) and IL-33 in asthmatic children, depending on disease activity.

METHODS

Thirty-seven children with well-defined asthma (20 moderate and 17 mild asthmatics) were studied. IL-33 and sST2 were measured by ELISA in serum and induced sputum (IS) samples, and compared with 22 age- and sex-matched healthy controls. Real-time quantitative PCR was used to determine IL-33 and TNF-α mRNA expression in IS.

RESULTS

sST2 and IL-33 levels in IS and serum were significantly higher in patients compared with healthy controls (p = 0.0001). The increase in sST2 and IL33 was significantly more important in moderate cases than in mild asthma. A significant correlation was observed between serum and IS IL-33 levels (r = 0.497; p = 0.0018). Higher levels of IL-33 mRNA were detected in IS from asthmatics than those observed in controls. A significant correlation was found between TNF-α and IL-33 mRNA expression in the asthmatic subjects (r = 0.772, p = 0.0001).

CONCLUSIONS

Values of sST2 and IL-33 observed in IS were found to correlate with disease activity. Elevated IL-33 mRNA expression in IS and its correlation with TNF-α reflected the inflammatory process observed in the lung of young asthmatics.

Novel insights into mechanisms of food allergy and allergic airway inflammation using experimental mouse models

Over the last decades, considerable efforts have been undertaken in the development of animal models mimicking the pathogenesis of allergic diseases occurring in humans. The mouse has rapidly emerged as the animal model of choice, due to considerations of handling and costs and, importantly, due to the availability of a large and increasing arsenal of genetically modified mouse strains and molecular tools facilitating the analysis of complex disease models. Here, we review latest developments in allergy research that have arisen from in vivo experimentation in the mouse, with a focus on models of food allergy and allergic asthma, which constitute major health problems with increasing incidence in industrialized countries. We highlight recent novel findings and controversies in the field, most of which were obtained through the use of gene-deficient or germ-free mice, and discuss new potential therapeutic approaches that have emerged from animal studies and that aim at attenuating allergic reactions in human patients.