Pathogenesis of murine experimental allergic rhinitis: a study of local and systemic consequences of IL-5 deficiency

Sex Dimorphism in Pain Threshold and Neuroinflammatory Response: The Protective Effect of Female Sexual Hormones on Behavior and Seizures in an Allergic Rhinitis Model

Our previous research demonstrated that allergic rhinitis could impact behavior and seizure threshold in male mice. However, due to the complex hormonal cycles and hormonal influences on behavior in female mice, male mice are more commonly used for behavioral tests. In this study, we aimed to determine whether these findings were replicable in female mice and to explore the potential involvement of sexual hormones in regulating neuroinflammation in an allergic model. Our results indicate that pain threshold was decreased in female mice with allergic rhinitis and the levels of IL-23/IL-17A/IL-17R were increased in their Dorsal root ganglia. However, unlike males, female mice with AR did not display neuropsychological symptoms such as learning and memory deficits, depression, and anxiety-like behavior. This was along with decreased levels of DNA methyl transferase 1 (DNMT1) and inflammatory cytokines in their hippocampus. Ovariectomized mice were used to mitigate hormonal effects, and the results showed that they had behavioral changes and neuroinflammation in their hippocampus similar to male mice, as well as increased levels of DNMT1. These findings demonstrate sex differences in how allergic rhinitis affects behavior, pain sensitivity, and seizure thresholds. Furthermore, our data suggest that DNMT1 may be influenced by sexual hormones, which could play a role in modulating inflammation in allergic conditions.

Targeting the RhoA-GEF-H1 pathway of mast cells attenuates experimental airway allergy

Mast cells are the major effector cells in allergic diseases. RhoA and its downstream pathway is associated with the pathogenesis of airway allergy. The objective of this study is to test a hypothesis that modulating the RhoA-GEF-H1 axis in mast cells can attenuate airway allergy. An airway allergic disorder (AAD) mouse model was employed. Mast cells were isolated from AAD mouse airway tissues to be analyzed by RNA sequencing. We observed that mast cells isolated from the respiratory tract of AAD mice were resistant to apoptosis. Mast cell mediator levels in nasal lavage fluid were correlated with apoptosis resistance in AAD mice. Activation of RhoA in AAD mast cells was related to resistance to apoptosis. Mast cells isolated from the airway tissues in AAD mouse exhibited strong RhoA-GEF-H1 expression. The RhoA-GEF-H1 axis was associated with the lower FasL expression in AAD mast cells. Activation of the RhoA-GEF-H1 axis promoted the production of mediators in mast cells. Inhibition of GEF-H1 facilitated the SIT-induced mast cell apoptosis and enhanced the therapeutic efficacy of AAD. In conclusion, RhoA-GEF-H1 activities are associated with resistance to apoptosis in mast cells isolated from sites of allergic lesions. The state of apoptosis resistance in mast cells is associated with the state of AAD disease. Inhibition of GEF-H1 restores the sensitivity of mast cells to apoptosis inducers, and alleviates experimental AAD in mice.

Mepolizumab decreases tissue eosinophils while increasing type-2 cytokines in eosinophilic chronic rhinosinusitis

BACKGROUND

Eosinophilic chronic rhinosinusitis is an often treatment-resistant inflammatory disease mediated by type-2 cytokines, including interleukin (IL)-5. Mepolizumab, a monoclonal antibody drug targeting IL-5, has demonstrated efficacy and safety in inflammatory airway disease, but there is negligible evidence on direct tissue response. The study's aim was to determine the local effect of mepolizumab on inflammatory biomarkers in sinonasal tissue of eosinophilic chronic rhinosinusitis patients.

METHODS

Adult patients with eosinophilic chronic rhinosinusitis received 100mg mepolizumab subcutaneously at four-weekly intervals for 24 weeks in this prospective phase 2 clinical trial. Tissue eosinophil counts, eosinophil degranulation (assessed as submucosal eosinophil peroxidase deposition by immunohistochemistry) and cytokine levels (measured in homogenates by immunoassay) were evaluated in ethmoid sinus tissue biopsies collected at baseline and at weeks 4, 8, 16 and 24.

RESULTS

Twenty patients (47.7 ± 11.7 years, 50% female) were included. Sinonasal tissue eosinophil counts decreased after 24 weeks of treatment with mepolizumab (101.64 ± 93.80 vs 41.74 ± 53.76 cells per 0.1 mm² ; p = .035), eosinophil degranulation remained unchanged (5.79 ± 2.08 vs 6.07 ± 1.20, p = .662), and type-2 cytokine levels increased in sinonasal tissue for IL-5 (10.84 ± 18.65 vs 63.98 ± 50.66, p = .001), IL-4 (4.48 ± 3.77 vs 9.38 ± 7.56, p = .004), IL-13 (4.02 ± 2.57 vs 6.46 ± 3.99, p = .024) and GM-CSF (1.51 ± 1.74 vs 4.50 ± 2.97, p = .001).

CONCLUSION

Mepolizumab reduced eosinophils in sinonasal tissue, demonstrating that antagonism of IL-5 suppresses eosinophil trafficking. With reduced tissue eosinophils, a local type-2 inflammatory feedback loop may occur. The study exposes mechanistic factors which may explain incomplete treatment response.

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.

Construction of an irreversible allergic rhinitis-induced olfactory loss mouse model

Clinical data show that part of patients with sinonasal diseases suffered from olfactory dysfunction, especially with allergic rhinitis (AR) and chronic rhinosinusitis (CRS). However, the mechanisms responsible for AR-induced olfactory loss are still largely unknown. Because of the difficulty to obtain human olfactory mucosa, an AR-induced olfactory loss animal model needs to be constructed to clarify the mechanism. The AR mouse model was induced by intraperitoneal sensitizing with ovalbumin (OVA) followed by intranasal challenge lasted from 1 to 12 weeks. For groups with recovery, mice were housed for another 4-week long without any treatment after the last intranasal challenge. Olfactory function, olfactory receptor neurons (ORNs) density and leukocytes infiltration were examined at different time points. Olfactory loss occurs immediately after 1-week intranasal challenge and deteriorates almost to anosmia after 8th week, and after that olfactory loss become irreversible. Nasal inflammation induces significant infiltration of leukocytes into olfactory epithelium (OE), which negatively correlated with the density of ORNs and mouse olfaction in a time dependent manner. The neutrophilic subtype dominates in number amongst the total infiltrated leukocytes, indicating its pivotal role in nasal inflammation-induced olfactory dysfunction. In this study, we constructed a persistent AR-induced olfactory loss mouse model, losing the ability to recover from dysfunction if the disease duration more than eight weeks, which implies that timely treatments are necessary. Meanwhile, this mouse model could provide an easy and reliable system to clarify the mechanisms of AR-induced irreversible olfactory dysfunction.

Antiallergic Effect of Hizikia fusiformis in an Ovalbumin-Induced Allergic Rhinitis Mouse Model

Objectives

The extract of Hizikia fusiformis is known to exhibit anticancer, antiatopic and antioxidant activities. We aimed to investigate the extract of H. fusiformis on allergic rhinitis inflammation in a mouse model.

Methods

The 4-week-old BALB/c mice were randomly assigned into four groups: group A, control group (n=9); group B, allergic rhinitis group (n=10); group C (n=10) received 300 mg/kg of H. fusiformis during nasal challenging period; group D (n=10) received 600 mg/kg of H. fusiformis during general sensitization period and 300 mg/kg of H. fusiformis during nasal challenging period. Allergic inflammation was made with ovalbumin (OVA) and alum then challenged intranasally with OVA. H. fusiformis was intraperitoneally administered 3 hours before the OVA administration. Allergic symptom score and the levels of immunoglobulin G₁ (IgG₁), IgG_2a, OVA-specific IgE antibodies, levels of cytokines in the nasal mucosa and in spleen cell culture supernatant, such as tumor necrosis factor alpha (TNF-α), interleukin 4 (IL-4), IL-5, IL-13, and IL-10 were assessed. The percentage of regulatory T cell was analyzed by flow cytometry. Eosinophilic infiltration and goblet cell hyperplasia were also evaluated.

Results

H. fusiformis administered groups C and D showed significant inhibitory effects on nasal symptoms, IL-13 mRNA expression and eosinophil infiltration/goblet cell hyperplasia in the nasal tissue; OVA-specific IgE production in serum (P<0.05). In group D, H. fusiformis treatment downregulated IL-4, IL-5, IL-13, TNF-α, and IL-10 cytokine expression in splenocyte culture as well as significantly decreased IgG_2a, IgG₁ levels in serum compared with group B (P<0.05). However, the expressions of IL-5, interferon-γ and forkhead box P3 mRNA did not change in groups C and D.

Conclusion

H. fusiformis could induce antiallergic inflammation by suppressing the T-helper type 2 cytokine production (IL-13) locally and systemically, OVA-specific IgE formation, goblet cell hyperplasia, and eosinophilic infiltration in a mouse model of allergic rhinitis. Thus, H. fusiformis could be considered as a potential therapeutic agent in treating allergic rhinitis.

Effects of a Thermosensitive In Situ Gel Containing Mometasone Furoate on a Rat Allergic Rhinitis Model

Background Mometasone furoate, one of the second generation intranasal corticosteroids, is currently used in suspension form due to its poor solubility. However, this is not favorable for nasal application because of the rapid elimination of the instilled drug from the nasal cavity by mucociliary clearance and delayed onset of action due to the slow dissolution of drug in suspension. Objective The aim of this study was to determine the antiallergic effects of mucoadhesive thermosensitive in situ gel containing mometasone furoate that we developed previously to prolong the contact between the drug and nasal mucosa and to prevent drainage of the formulation in an ovalbumin-induced rat model of allergic rhinitis. Methods An experimental allergic rhinitis model was developed in female Wistar albino rats by intraperitoneal injection of ovalbumin every 2 days for 14 days followed by its repeated intranasal instillation for 7 consecutive days. Intranasal instillation of ovalbumin was continued every other day for 14 days. Mometasone furoate in situ gel (5 μg/10 µl), mometasone furoate suspension (5 μg/10 µl), and physiological saline (10 µl) were administered into the bilateral nasal cavities from day 22 to day 35. Antiallergic effects were evaluated through histopathological evaluation, analysis of ovalbumin-specific serum immunoglobulin E, and a symptom score. Results Mometasone furoate in situ gel significantly decreased the nasal symptoms and ovalbumin-specific serum immunoglobulin E level as compared with mometasone furoate suspension and physiological saline. Additionally, inflammatory histological symptoms such as mucosal edema, vascular dilatation, eosinophil infiltration, and loss of cilia within the nasal mucosa of allergic rhinitis model rats were remarkably improved with the treatment of mometasone furoate in situ gel. Conclusion These results suggest that mometasone furoate in situ gel has a better therapeutic potential for the treatment of allergic rhinitis compared to mometasone furoate suspension.

Mouse Model of IL-17-Dominant Rhinitis Using Polyinosinic-Polycytidylic Acid

Interleukin (IL)-17 plays an important role in rhinitis and the level thereof correlates with the severity of disease. However, no mouse model for IL-17-dominant rhinitis has yet been developed. Our objective was to establish a mouse model of IL-17-dominant rhinitis via intranasal application of polyinosinic-polycytidylic acid (abbreviated as Poly(I:C)). Mice were divided into 6 groups (n=8 for each group); 1) 1 negative control group, 2) 1 positive control group (OVA/alum model), 3) 2 Poly(I:C) groups (10 or 100 μg), and 4) 2 OVA/Poly(I:C) groups (10 or 100 μg). The positive control group was treated with the conventional OVA/alum protocol. In the Poly(I:C) and OVA/Poly(I:C) groups, phosphate-buffered saline or an OVA solution plus Poly(I:C) were administered. The OVA/Poly(I:C) groups exhibited significantly greater neutrophil infiltration and increased IL-17/interferon γ expression compared with the other groups. However, the levels of total immunoglobulin E (IgE), OVA-specific IgE, eosinophil infiltration, IL-4, IL-5, IL-6, and IL-10 were significantly lower in the OVA/Poly(I:C) groups than in mice subjected to conventional Th2-dominant OVA/alum treatment (the positive control group). IL-17 and neutrophil measurement, chemokine (C-X-C motif) ligand 1 immunohistochemistry, and confocal microscopy revealed increased numbers of IL-17-secreting cells in the nasal mucosa of the OVA/Poly(I:C) groups, which included natural killer cells, CD4 T cells, and neutrophils. In conclusion, we developed a mouse model of IL-17-dominant rhinitis using OVA together with Poly(I:C). This model will be useful in research on neutrophil- or IL-17-dominant rhinitis.

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.

The Role of IL-17 in a Lipopolysaccharide-Induced Rhinitis Model

Purpose

Lipopolysaccharide (LPS) is a cell wall component of Gram-negative bacteria and important for pro-inflammatory mediators. This study aimed to establish a rhinitis model using ovalbumin (OVA) and LPS in order to evaluate the role of interleukin (IL)-17 in the pathogenesis of an LPS-induced non-eosionophilic rhinitis model.

Methods

Mice were divided into 4 groups and each group consisted of 10 mice (negative control group, allergic rhinitis model group, 1-µg LPS treatment group, and 10-µg LPS treatment group). BALB/c mice were sensitized with OVA and 1 or 10 µg of LPS, and challenged intranasally with OVA. Multiple parameters of rhinitis were also evaluated to establish the LPS-induced rhinitis model. IL-17 knockout mice were used to check if the LPS-induced rhinitis model were dependent on IL-17. Eosinophil and neutrophil infiltration, and mRNA and protein expression profiles of cytokine in nasal mucosa or spleen cell culture were evaluated using molecular, biochemical, histopathological, and immunohistological methods.

Results

In the LPS-induced rhinitis model, neutrophil infiltration increased in the nasal mucosa, and systemic and nasal IL-17 and interferon-gamma (IFN-γ) levels also increased as compared with the OVA-induced allergic rhinitis model. These findings were LPS-dose-dependent. In IL-17 knockout mice, those phenotypes (neutrophil infiltration, IL-17, and IFN-γ) were reversed, showing IL-17 dependency of LPS-induced rhinitis. The expression of vascular endothelial growth factor (VEGF), an important mediator for inflammation and angiogenesis, decreased in IL-17 knockout mice, showing the relationship between IL-17 and VEGF.

Conclusions

This study established an LPS-induced rhinitis model dependent on IL-17, characterized by neutrophil infiltration and increased expression of IL-17.

Stepwise management of asthma

BACKGROUND

Stepwise management of asthma remains an area of evolving research. Asthma is one of the most expensive chronic diseases in the United States; stepwise management is an important area of focus, with several recent guidelines recommending management.

METHODS

This is a review of published English language literature, focusing on management guidelines for asthma in adult and pediatric patients.

RESULTS

Asthma is a chronic disease whose assessment of severity allows for therapeutic goals to match the impairment noted. Good evidence exists to aid risk reduction, leading to decreased emergency room visits, preventing loss of lung function in adults and lung growth in children, and optimizing pharmacotherapy with reduced side effects profile.

CONCLUSION

Recent asthma management guidelines incorporate 4 components of asthma care including: monitoring of severity, patient education, controlling external triggers, and medications, including recent attention to medication adherence. Asthma is an expensive chronic disease with preventive measures leading to reduced healthcare costs. Future targeted cytokine therapy to decrease serum and blood eosinophils may become an integral part of asthma management.

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.

IL-23, rather than IL-17, is crucial for the development of ovalbumin-induced allergic rhinitis

Interleukin-23 (IL-23) and IL-17 are involved in the pathogenesis of allergic rhinitis (AR). However, the roles of IL-23 and IL-17 in ovalbumin (OVA)-induced AR remain unclear. Therefore in this study we aim to investigate the precise roles of IL-23 and IL-17 in a mouse model of OVA-induced AR. We found that during OVA-induced AR, eosinophil and goblet cells in the nose were significantly decreased in IL-23-deficient, but not in IL-17-deficient mice. However, there was no difference in the serum IgE and IgG1 levels between IL-23-deficient or IL-17-deficient and wild-type mice. Moreover, IL-4 levels in lymph node cell culture supernatants were significantly decreased in IL-23-deficient, but not IL-17-deficient, compared with wild-type mice. Furthermore, OVA-induced AR developed similarly in wild-type mice transferred with either IL-23-deficient BM cells or wild-type BM cells. These findings suggest that IL-23, but not IL-17 is crucial for the development of OVA-induced AR, and IL-23 neutralization may be a potential approach for treatment of OVA-induced AR in humans.

In situ hematopoiesis: a regulator of TH2 cytokine-mediated immunity and inflammation at mucosal surfaces

Hematopoiesis refers to the development of blood cells in the body through the differentiation of pluripotent stem cells. Although hematopoiesis is a multifocal process during embryonic development, under homeostatic conditions it occurs exclusively within the bone marrow. There, a limited number of hematopoietic stem cells differentiate into a rapidly proliferating population of lineage-restricted progenitors that serve to replenish circulating blood cells. However, emerging reports now suggest that under inflammatory conditions, alterations in hematopoiesis that occur outside of the bone marrow appear to constitute a conserved mechanism of innate immunity. Moreover, recent reports have identified previously unappreciated pathways that regulate the egress of hematopoietic progenitor cells from the bone marrow, alter their activation status, and skew their developmental potential. These studies suggest that progenitor cells contribute to inflammatory response by undergoing in situ hematopoiesis (ISH). In this review, we highlight the differences between homeostatic hematopoiesis, which occurs in the bone marrow, and ISH, which occurs at mucosal surfaces. Further, we highlight factors produced at local sites of inflammation that regulate hematopoietic progenitor cell responses and the development of TH2 cytokine-mediated inflammation. Finally, we discuss the therapeutic potential of targeting ISH in preventing the development of inflammation at mucosal sites.

Generation of eosinophils from cryopreserved murine bone marrow cells

Eosinophils are produced in the bone marrow from CD34⁺ eosinophil lineage–committed progenitors, whose levels in the bone marrow are elevated in a variety of human diseases. These findings suggest that increased eosinophil lineage–committed progenitor production is an important process in disease-associated eosinophilia. The pathways central to the biology of the eosinophil lineage–committed progenitor remain largely unknown. Thus, developing new methods to investigate the regulators of eosinophil lineage–committed progenitor differentiation is needed to identify potential therapeutic targets to specifically inhibit eosinophil production. We tested cytokine regimens to optimize liquid cultures for the study of eosinophil lineage–committed progenitor and eosinophil precursor differentiation into mature eosinophils. Stem cell factor (but not fms-related tyrosine kinase 3 ligand) was required for optimal yield of eosinophils. Furthermore, we evaluated the effects of cell preservation and scale on the culture, successfully culturing functional eosinophils from fresh and frozen murine bone marrow cells and in a standard-sized and 96-well culture format. In summary, we have developed an adaptable culture system that yields functionally competent eosinophils from murine low-density bone marrow cells and whose cytokine regime includes expansion of progenitors with stem cell factor alone with subsequent differentiation with interleukin 5.

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.

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.

Changes of T-helper type 1/2 cell balance by anticholinergic treatment in allergic mice

BACKGROUND

Anticholinergic drugs or vidian neurectomy can alleviate the symptoms of allergic rhinitis.

OBJECTIVE

To show that inhibition of the cholinergic nerve influences the balance of T-helper type 1 and 2 cells in allergic rhinitis mice.

METHODS

Twenty-four mice were randomly allocated to 1 of 4 groups: control, model, model with ipratropium bromide treatment, and model with 6-hydroxydopamine treatment. Allergic model-treated mice were sensitized with ovalbumin. Evaluation of allergic symptoms was recorded according to a symptom score. Ovalbumin serum IgE was measured by enzyme-linked immunosorbent assay. Expression of interleukin-4, interferon-γ, forkhead box P3, substance P, and vasoactive intestinal peptides was detected by immunohistochemistry and imaging analysis.

RESULTS

Symptoms in allergic mice were significantly alleviated by ipratropium bromide. Ovalbumin serum IgE and eosinophils of nasal mucosa were significantly decreased. Interleukin-4 expression level was significantly higher in the allergic model group than in the control group and significantly decreased by ipratropium bromide (P < .05). In contrast, the expression of forkhead box P3 was lower in the allergic model group than in the control group and increased with treatment by ipratropium bromide (P < .05). Conversely, interferon-γ expression was not changed by anticholinergic treatment in the nasal mucosa of allergic mice. Expression of substance P and vasoactive intestinal peptide was significantly increased in allergic mice and decreased by ipratropium bromide. Sympathetic denervation did not change the expression of interleukin-4, interferon-γ, forkhead box P3, substance P, and vasoactive intestinal peptide.

CONCLUSION

inhibition of the cholinergic nerve not only alleviated symptoms of allergic rhinitis by inhibiting the impulse of the parasympathetic nerve but also modulated the T-helper type 2-predominant immune reaction, expression of neuropeptides, and related inflammation factors.

Molecular mechanism of action of K(D)PT as an IL-1RI antagonist for the treatment of rhinitis

K(D)PT curing allergic rhinitis through keeping IL-1RI in close status.

Antiallergic effect of anti-Siglec-F through reduction of eosinophilic inflammation in murine allergic rhinitis

BACKGROUND

Sialic acid-binding Ig-like lectin-F (Siglec-F) in mice and its functional paralog Siglec-8 in humans are transmembrane receptors that play a role in the apoptosis of eosinophils. We aimed to evaluate the therapeutic potential of anti-Siglec-F antibodies in a murine model of allergic rhinitis.

METHODS

Twenty-eight BALB/c mice were used. In group A (control group, n = 7), mice were sensitized and challenged with saline. In group B (ovalbumin [OVA] challenge group, n = 7), OVA was used for i.p. sensitization and intranasal challenge. Mice in group C (control IgG group, n = 7) or those in group D (anti-Siglec-F group, n = 7) had been given rabbit control IgG or anti-Siglec-F antibody injections, respectively. We assessed the number of nose-scratching events; serum total/OVA-specific IgE; the number of eosinophils, neutrophils, and lymphocytes in bronchoalveolar lavage (BAL) fluid; histopathological changes in nasal cavity tissues; and the levels of IL-4, IL-5, and IL-13 in BAL fluid.

RESULTS

Mice in group D had significantly less nose scratching. Serum total and OVA-specific IgE were not significantly changed. The number of eosinophils in BAL fluid and in the lamina propria of the nasal cavity mucosa was significantly decreased with anti-Siglec-F antibody treatment. The levels of Th2 cytokines such as IL-4, IL-5, and IL-13 were also significantly decreased with anti-Siglec-F antibody treatment.

CONCLUSION

Anti-Siglec-F antibody has beneficial effects in a mouse model of experimental allergic rhinitis.

Mast Cell-Activated Bone Marrow Mesenchymal Stromal Cells Regulate Proliferation and Lineage Commitment of CD34(+) Progenitor Cells

BACKGROUND

Shortly after allergen exposure, the number of bone marrow (BM) and circulating CD34(+) progenitors increases. We aim to analyze the possible mechanism whereby the allergic reaction stimulates BM to release these effector cells in increased numbers. We hypothesize that mast cells (MCs) may play a predominant role in this process.

OBJECTIVE

To examine the effect of IgE-activated MCs on BM mesenchymal stromal cells which regulate proliferation and differentiation of CD34(+) progenitors.

METHODS

Primary MCs were derived from CD34(+) precursors and activated with IgE/anti-IgE. BM mesenchymal stromal cells were co-cultured with CD34(+) progenitor cells and stimulated with IL-1/TNF or IgE/anti-IgE-activated MCs in Transwell system.

RESULTS

BM mesenchymal stromal cells produce low level of thymic stromal lymphopoietin (TSLP) under steady state conditions, which is markedly increased by stimulation with proinflammatory cytokines IL-1 and TNF or IgE-activated MCs. The latter also triggers bone marrow-derived mesenchymal stromal cells production of G-CSF, and GM-CSF while inhibiting SDF-1. MC-activated mesenchymal stromal cells stimulate CD34(+) cells to proliferate and to regulate their expression of early allergy-associated genes.

CONCLUSION AND CLINICAL RELEVANCE

This in vitro study indicates that IgE-activated MCs trigger BM mesenchymal stromal cells to release TSLP and hematopoietic growth factors and to regulate the proliferation and lineage commitment of CD34(+) precursor cells. The data predict that the effective inhibition of MCs should impair mobilization and accumulation of allergic effector cells and thereby reduce the severity of allergic 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.

Eosinophils in fungus-associated allergic pulmonary disease

Asthma is frequently caused and/or exacerbated by sensitization to fungal allergens, which are ubiquitous in many indoor and outdoor environments. Severe asthma with fungal sensitization is characterized by airway hyperresponsiveness and bronchial constriction in response to an inhaled allergen that is worsened by environmental exposure to airborne fungi and which leads to a disease course that is often very difficult to treat with standard asthma therapies. As a result of complex interactions among inflammatory cells, structural cells, and the intercellular matrix of the allergic lung, patients with sensitization to fungal allergens may experience a greater degree of airway wall remodeling and progressive, accumulated pulmonary dysfunction as part of the disease sequela. From their development in the bone marrow to their recruitment to the lung via chemokine and cytokine networks, eosinophils form an important component of the inflammatory milieu that is associated with this syndrome. Eosinophils are recognized as complex multi-factorial leukocytes with diverse functions in the context of allergic fungal asthma. In this review, we will consider recent advances in our understanding of the molecular mechanisms that are associated with eosinophil development and migration to the allergic lung in response to fungal inhalation, along with the eosinophil’s function in the immune response to and the immunopathology attributed to fungus-associated allergic pulmonary disease.

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

OBJECTIVE

Interleukin (IL)-33, which mediates the T(h)2 allergic pathway, may play a key role in allergic airway inflammation. This study was conducted to evaluate the therapeutic potential of anti-IL-33 antibody for treatment of allergic inflammation of the lower airway in a murine model.

METHODS

Twenty-four BALB/c mice were used in this study. Saline was used for sensitization and challenge of mice in Group A (control group, n = 6). Mice in Group B (ovalbumin (OVA) group, n = 6) received intraperitoneal (ip) and intranasal OVA challenge. In Group C (control IgG group, n = 6), mice received ip injection with control IgG prior to OVA challenge. Mice in Group D (anti-IL-33 group, n = 6) received an ip injection of anti-IL-33 prior to challenge. Measurements of serum total and OVA-specific IgE and the number of eosinophils, neutrophils, and lymphocytes in bronchoalveolar lavage (BAL) fluid were performed. We performed histopathologic examination to evaluate the degree of eosinophilic infiltration in lung tissue. Airway hyperreactivity was measured according to change of enhanced pause (Penh).

RESULTS

A significant decrease in serum total and OVA-specific IgE and the number of eosinophils and neutrophils in BAL fluid was observed in Group D, compared with Group B or Group C (p < .05). In Group D, treatment with anti-IL-33 resulted in a significant decrease in eosinophilic infiltration in lung tissue, compared with Group B and Group C (p < .05). Degree of airway hyperreactivity, measured by Penh, showed a significant decrease in the anti-IL-33 treatment group, compared with the OVA group or the control IgG treatment group (p < .01, at 50 mg/mL of methacholine).

CONCLUSIONS

Anti-IL-33 has therapeutic potential for treatment of allergic inflammation of the lower airway.

Anti-IL-33 antibody has a therapeutic effect in a murine model of allergic rhinitis

BACKGROUND

Interleukin (IL)-33 is involved in the Th2 immune response and could play an essential role in nasal allergy. Therefore, we aimed to investigate the therapeutic potential of anti-IL-33 for allergic rhinitis (AR).

METHODS

Twenty-four BALB/c mice were used. In group A (control group, n = 6), mice were sensitized and challenged with saline. Group B [ovalbumin (OVA) group, n = 6] mice received intraperitoneal and intranasal OVA challenge. In group C (control IgG group, n = 6), mice were injected intraperitoneally with rabbit control IgG before OVA challenge. In group D (anti-IL-33 group, n = 6), anti-IL-33 was injected before challenge. We evaluated the number of nose-scratching events and external morphology; serum total and OVA-specific IgE; number of eosinophils, neutrophils, and lymphocytes in bronchoalveolar lavage (BAL) fluid; histopathologic examination of nasal cavity; and IL-4, IL-5, and IL-13 in BAL fluid.

RESULTS

Anti-IL-33 treatment significantly reduced the nose-scratching events and ameliorated skin denudation. Serum total and OVA-specific IgE was significantly decreased in group D. The number of eosinophils in BAL fluid was also significantly decreased. Eosinophilic infiltration in the nasal cavity was significantly decreased in group D. IL-4, IL-5, and IL-13 in BAL fluid were also significantly decreased after treatment.

CONCLUSIONS

Anti-IL-33 antibody has a therapeutic potential for experimental AR.

Hemopoietic progenitors: the role of eosinophil/basophil progenitors in allergic airway inflammation

Progenitor cells play important roles in the physiology and homeostasis of the overall hemopoietic system. The majority of hemopoietic activity takes place in the bone marrow, under the influence of resident marrow stromal cells, accessory cells, and/or their products. This constitutes the complex network of the hemopoietic inductive microenvironment, which is crucial for providing signals necessary for the maintenance of populations of progenitors at varying stages of lineage commitment. Accumulation of eosinophils and basophils in tissues is characteristic of allergic inflammation. A large body of evidence now exists which confirms that these tissue inflammatory events are coincident with relevant changes in progenitors; it has thus been hypothesized that the observed changes in mature cell numbers occur directly or indirectly as a result of differentiation of lineage-committed eosinophil/basophil, and perhaps other, progenitor cells. Differentiation and maturation of hemopoietic cells have traditionally been thought to be restricted to the bone marrow microenvironment. More recently, evidence has accumulated to suggest that some hemopoietic cells present in allergic tissue may be recruited from the bone marrow, traffic through the peripheral circulation and into tissues to participate in the ongoing inflammatory process at these distal sites. The clinical administration of monotherapy with topical corticosteroids, oral cysteinyl leukotriene antagonists and cytokine antagonists such as antibodies to interleukin-5, suggest that suppression of hemopoietic contributions to allergic inflammation may be necessary for full control of allergic inflammation and disease manifestations. In addition to progenitors being targets of therapy, they may well determine how and whether allergic inflammation is generated in early life, thus serving as biomarkers of disease.

Eosinophils infiltrate thyroids, but have no apparent role in induction or resolution of experimental autoimmune thyroiditis in interferon-gamma(-/-) mice

Granulomatous experimental autoimmune thyroiditis (G-EAT) is induced by mouse thyroglobulin (MTg)-sensitized splenocytes activated with MTg and interleukin (IL)-12. Our previous studies showed that, when used as donors and recipients, interferon (IFN)-gamma(-/-) and wild-type (WT) DBA/1 mice both develop severe G-EAT. Thyroid lesions in IFN-gamma(-/-) mice have many eosinophils and few neutrophils, while those in WT mice have extensive neutrophil infiltration and few eosinophils. Thyroid lesions in IFN-gamma(-/-) mice consistently resolve by day 40-50, whereas those in WT mice have ongoing inflammation and fibrosis persisting for more than 60 days. To determine if the extensive infiltration of eosinophils in thyroids of IFN-gamma(-/-) mice contributes to thyroid damage and/or early resolution of G-EAT, anti-IL-5 was used to inhibit migration of eosinophils to thyroids. G-EAT severity was compared at day 20 and day 40-50 in IFN-gamma(-/-) recipients given anti-IL-5 or control immunoglobulin G (IgG). Thyroids of anti-IL-5-treated IFN-gamma(-/-) mice had few eosinophils and more neutrophils at day 20, but G-EAT severity scores were comparable to those of control IgG-treated mice at both day 20 and day 40-50. Expression of chemokine (C-X-C motif) ligand 1 (CXCL1) mRNA was higher and that of chemokine (C-C motif) ligand 11 (CCL11) mRNA was lower in thyroids of anti-IL-5-treated IFN-gamma(-/-) mice. IL-5 neutralization did not influence mRNA expression of most cytokines in IFN-gamma(-/-) mice. Thus, inhibiting eosinophil migration to thyroids did not affect G-EAT severity or resolution in IFN-gamma(-/-) mice, suggesting that eosinophil infiltration of thyroids occurs as a consequence of IFN-gamma deficiency, but these cells have no apparent pathogenic role in G-EAT.

Haemopoietic processes in allergic disease: eosinophil/basophil development

Haemopoietic myeloid progenitors contribute to the ongoing recruitment of pro-inflammatory cells, such as eosinophils and basophils (Eo/B), to target tissue sites in allergic diseases. It is apparent that the development of allergic inflammation is critically dependent on the ability of the bone marrow to support the proliferation, differentiation and mobilization of haemopoietic progenitors. The haemopoietic inductive microenvironment in the bone marrow is crucial for providing signals necessary for maintenance of progenitor populations at varying stages of lineage commitment and permitting these cells to circulate in the bloodstream. Progenitors demonstrate responsiveness to specific cytokines, which varies with stage of differentiation. Pro-inflammatory signals, Th2 cytokines in particular, generated following allergen challenge, can impact on haemopoietic progenitor differentiation and mobilization, leading to accelerated Eo/B production. Allergen inhalation by allergic asthmatics induces a time-dependent change in cytokine levels within the bone marrow compartment, influencing differentiation of Eo/B progenitors, as evidenced by the relationship between increased bone marrow IL-5 levels and Eo/B production. It is proposed that inhaled allergen induces trafficking of IL-5-producing T lymphocytes to the bone marrow, further promoting eosinophilopoiesis through IL-5R signalling. In this manner, Th2 lymphocyte trafficking from the airway may regulate events occurring in the bone marrow. Negative regulators of Eo/B differentiation, including Th1 cytokines, may prove to be important for restoring homeostasis. Eo/B progenitors are also altered in cord blood of infants at risk of atopy and asthma, offering a potential biomarker for, and raising the possibility that Eo/B progenitors are directly involved in the development of allergic disease. For example, changes in the expression of haemopoietic cytokine receptors on cord blood progenitor cells are associated with maternal allergic sensitization, atopic risk and its development, suggesting that haemopoietic processes underlying the allergic phenotype may begin to evolve in the perinatal period.

Absence of nasal blockage in a Japanese cedar pollen-induced allergic rhinitis model mouse

BACKGROUND

Japanese cedar pollen-induced allergic rhinitis in a guinea pig model clearly induced not only sneezing but also biphasic nasal blockage. To date, there have only been a few reports on models of murine allergic rhinitis which clearly show nasal blockage. Therefore, in order to try and develop such a model, we administered multiple dosages of intranasal pollen or purified antigen protein Cry j 1.

METHODS

B10.S mice were sensitized by intranasal instillations of either pollen extract or Cry j 1 twice a day for 7 days, which was adsorbed on Al(OH)(3). Subsequently, once a week, the mice were given multiple intranasal instillation challenges of either the pollen suspension or Cry j 1 and the frequency of sneezing was observed after respective challenges were made. Specific airway resistance (sRaw) was measured as an indicator for nasal blockage. Cry j 1-specific IgE levels were measured using an enzyme-linked immunosorbent assay.

RESULTS

The serum Cry j 1-specific IgE level showed clear elevation only in the group sensitized by Cry j 1 + Al(OH)(3) and then challenged by Cry j 1. No elevations were seen in the groups sensitized by pollen extract + Al(OH)(3) followed by a pollen suspension challenge. There was an immediate increase in sneezing after challenges in all of the sensitized-challenged groups. Nevertheless, no increases in sRaw in any of the groups were detected at any of the time points during the 8 hours following the challenges.

CONCLUSIONS

Cry j 1 may be more effective than crude antigens for efficient sensitization/challenge in mice. No increase in sRaw occurred, even in mice that possessed high amounts of Cry j 1-specific IgE and that exhibited sneezing.

Eosinophil progenitors in airway diseases: clinical implications

Asthma, allergic rhinitis, nasal polyposis, chronic rhinosinusitis, and related forms of upper and lower airway diseases are often characterized by eosinophilic and basophilic inflammation, involving systemic processes. Eosinophil/basophil (Eo/B) lineage-committed progenitor cells in cord blood, peripheral blood, bone marrow, lung tissue, and sputum are up-regulated in the above conditions, and respond to allergen and other stimuli with increased differentiative and migratory capacity. A considerable body of evidence now exists showing that activation of such Eo/B-selective hemopoietic processes is not only associated with the onset and maintenance of allergic inflammation in atopic adults, but also with the development of the allergic diathesis. Moreover, eosinophilopoietic processes within hemopoietic compartments and, importantly, at mucosal tissue sites during an allergic inflammatory response provide novel targets for the treatment of allergy as a systemic process and disease.

The effects of montelukast on tissue inflammatory and bone marrow responses in murine experimental allergic rhinitis: interaction with interleukin-5 deficiency

The cysteinyl leukotrienes (cysLTs) are potent lipid mediators in allergic disease, acting through the receptors, cysLT1R and cysLTR2, and are produced by eosinophils derived from eosinophil/basophil (Eo/B) bone marrow (BM) progenitors. We have demonstrated the suppressive effects of either interleukin-5 (IL-5) deficiency or montelukast on eosinophil recruitment in murine allergic rhinitis, but neither of them fully abrogated the symptoms caused by residual inflammation and cytokine redundancy in eliciting BM Eo/B responses. We hypothesized that IL-5 deficiency and montelukast act synergistically to suppress tissue inflammatory and BM responses. Our objective was to investigate the effects of the cysLT1R antagonist, montelukast, on in vivo tissue inflammatory and BM responses in murine experimental allergic rhinitis with or without IL-5 deficiency. Three groups of age-matched BALB/c mice with or without IL-5 deficiency were tested: controls (ovalbumin sensitization and challenge, placebo treatment) and two montelukast-treated groups (2.5 mg/kg or 5 mg/kg). Nasal symptoms, BM and nasal mucosal eosinophils, basophils, and BM Eo/B colony-forming units (CFU) were evaluated. Montelukast decreased nasal symptoms in a dose-dependent manner, and significantly decreased the number of eosinophils in both BM and nasal tissue in IL-5-replete mice compared to controls. In IL-5-deficient mice, in which eosinophilia was absent, montelukast significantly decreased both nasal symptoms and basophils in BM and nasal mucosal tissue, and lowered IL-5-responsive Eo/B-CFU ex vivo, compared to controls. The addition of cysLT1R blockade to IL-5 deficiency more fully attenuates symptoms and upper airway inflammation than either factor alone, providing evidence of systemic, BM mechanisms in allergic rhinitis.

Chemotactic action of prostaglandin E2 on mouse mast cells acting via the PGE2 receptor 3

Mast cells are long-lived cells that are principally recognized for their effector function in helminth infections and allergic reactions. These cells are derived from pluripotential hematopoietic stem cells in the bone marrow that give rise to committed mast cell progenitors in the blood and are recruited to tissues, where they mature. Little is known about the chemotactic signals responsible for recruitment of progenitors and localization of mature mast cells. A mouse model was set up to identify possible mast cell progenitor chemoattractants produced during repeated allergen challenge in vivo. After the final challenge, the nasal mucosa was removed to produce conditioned medium, which was tested in chemotaxis assays against 2-wk murine bone marrow-derived c-kit+ mast cells (BMMC). A single peak of chemotactic activity was seen on reverse-phase HPLC with a retention time and electrospray mass spectrum consistent with prostaglandin E2 (PGE2). This lipid was found to be a highly potent chemoattractant for immature (2-wk) and also mature (10-wk) BMMC in vitro. Fluorescently labeled 2-wk c-kit+ BMMC, when injected intravenously, accumulated in response to intradermally injected PGE2. Analysis using TaqMan showed mRNA expression of the PGE2 receptors 3 (EP3) and 4 (EP4) on 2- and 10-wk BMMC. Chemotaxis induced by PGE2 was mimicked by EP3 agonists, blocked by an EP3 receptor antagonist, and partially inhibited by a MAPKK inhibitor. These results show an unexpected function for PGE2 in the chemotaxis of mast cells.

A preliminary study towards downregulation of murine bone marrow eosinophilopoiesis mediated by small molecule inhibition of interleukin-5 receptor alpha gene in vitro

BACKGROUND

Bone marrow eosinophilopoiesis induced by IL-5 makes a major contribution to eosinophilic airway inflammation in asthma. Bone marrow CD(34)(+) cells expressing IL-5Ralpha may be eosinophil progenitors. However, research on the effect of blocking IL-5Ralpha expression on bone marrow eosinophilopoiesis has seldom been reported.

OBJECTIVE

To explore the effect of inhibiting IL-5Ralpha expression with IL-5Ralpha short hairpin RNA-expressing vector on murine bone marrow eosinophilopoiesisin vitro.

METHODS

We constructed 4 kinds of plasmid vectors that could express small molecule inhibition, short hairpin RNA, which targeted IL-5Ralpha (P-IL-5Ralpha), and selected an effective one by transfecting B lymphoma cells in vitro. We also constructed an adenovirus vector which was inserted into an effective template sequence (Ad-IL-5Ralpha). The bone marrow cells were obtained from healthy Balb/c mice, and cultured and transfected by Ad-IL-5Ralpha in vitro. The expression of IL-5Ralpha and the count of newly produced eosinophils were detected in the cultured bone marrow cells.

RESULTS

We found that P-IL-5Ralpha-3 targeted at the sequence of CAG CTG CCT GGT TCG TCT T markedly suppressed the IL-5Ralpha expression in the B lymphoma cellsin vitro. Ad-IL-5Ralpha could suppress the IL-5Ralpha expression of murine bone marrow cellsin vitro and it could also significantly decrease the IL-5-induced eosinophilia in the cultured bone marrow cells.

CONCLUSION

These results indicate that the blocking of IL-5Ralpha expression by small molecule inhibition can help to effectively decrease murine bone marrow eosinophilopoiesis, and that bone marrow may be used as a critical target organ in the diseases involved in eosinophilia, such as asthma.

Botulinum toxin therapy in the ovalbumin-sensitized rat

OBJECTIVE

The aim of this study was to determine whether intranasal administration of botulinum toxin type A (BTX-A) could relieve the typical symptoms of allergic rhinitis (AR) and alter substance P (SP)- and vasoactive intestinal peptide (VIP)-immunoreactive (IR) expression in nasal mucosa of AR animals sensitized with ovalbumin (OVA).

METHODS

AR was induced by intraperitoneal injection of OVA followed by its repeated intranasal instillation in female Wistar rats. Some AR animals were intranasally treated with a cotton strip containing BTX-A (10 U per nostril) for 1 h. After BTX-A treatment, OVA was repeatedly instilled in AR and AR + BTX-A groups every 2 days for 10 days. Subsequently, nasal symptoms were evaluated, and nasal secretions collected. Finally, the nasal mucosae of all animals were prepared for histological and immunohistochemical assessment.

RESULTS

BTX-A administration alleviated typical AR symptoms including rhinorrhea, nasal itching and sneezing, and subsequent intranasal repeated challenge with OVA did not trigger AR symptoms. After BTX-A treatment, inflammatory histological characteristics within the nasal mucosa of AR animals were absent, but atrophy of serous glands was observed. BTX-A decreased dense SP-IR and VIP-IR cells and fibers within and beneath the epithelium, around blood vessels and close to serous glands in AR animals.

CONCLUSION

Local BTX-A treatment is an effective method to reduce AR symptoms. BTX-A decreased the excessive SP-IR and VIP-IR expression induced by OVA. Therefore, BTX-A may affect the nasal mucosa via the suppression of neuropeptides, playing a major role in autonomous mucosal innervation in the pathophysiology of AR.

Effect of interleukin-5 receptor-alpha short hairpin RNA-expressing vector on bone marrow eosinophilopoiesis in asthmatic mice

Bone marrow eosinophilopoiesis induced by interleukin (IL)-5 is a major contributor to eosinophilic airway inflammation in asthma. However,research on the use of IL-5 receptor alpha (IL-5Ralpha) as the target has seldom been reported. This study was undertaken to explore the effects of inhibition of IL-5Ralpha expression through an IL-5Ralpha short hairpin RNA-expressing vector on bone marrow eosinophilopoiesis and airway inflammation in an asthmatic mouse model. An effective plasmid vector was selected that could express short hairpin RNA targeted at IL-5Ralpha (P-IL-5Ralpha). An adenovirus vector (Ad) was then constructed that was inserted in an effective template sequence (Ad-IL-5Ralpha). An animal model of asthma was established by sensitizing and challenging Balb/c mice with ovalbumin. Animals were treated intravenously with Ad-IL-5Ra and changes in bone marrow eosinophilopoiesis and airway inflammation were detected in asthmatic mice. Investigators found that P-IL-5Ra-3 targeted at the sequence of CAG CTG CCT GGT TCG TCT T markedly suppressed IL-5Ralpha expression in B lymphoma cells in vitro. In addition, Ad-IL-5Ralpha could suppress IL-5Ralpha expression in murine bone marrow cells in vitro and in vivo, and it could significantly decrease IL-5-induced eosinophilia in cultured bone marrow cells. Additional studies indicated that intravenously injected Ad-IL-5Ralpha not only selectively reduced the number of eosinophils in the bone marrow, peripheral blood, and bronchoalveolar lavage fluid, it also relieved airway inflammation in asthmatic mice. Results reported here show that blocking of IL-5Ralpha expression through RNA interference can enhance effective treatment of asthma, and that bone marrow can be used as a key targeted organ in the treatment of asthmatic mice.

Is rhinosinusitis a cause of asthma?

There is a great deal of evidence of an association between rhinosinusitis and asthma. However, it is less clear whether rhinosinusitis is a direct trigger for asthma or the two conditions are simply manifestations of a common underlying process. Evidence for a role for rhinosinusitis as a trigger for asthma includes many examples of improvement in asthma once concomitant rhinosinusitis is treated medically or surgically. Possible mechanisms for this relationship include naso-pharyngo-bronchial reflexes, postnasal drip, abnormal breathing, and the local production of inflammatory mediators that trigger pulmonary inflammation via the bone marrow. On the other hand, evidence exists that rhinosinusitis and asthma are manifestations of a common process. For example, there are similarities between the histopathological changes in the epithelium in chronic rhinosinusitis and asthma. The bone marrow may provide the link between the upper and lower airways in creating a common disease. A second possible mechanism for a common disease is response to staphylococcal enterotoxins. Although evidence exists to suggest that rhinosinusitis either triggers asthma or represents a local manifestation of a shared disorder, the key to reconciling this apparent controversy is to consider that rhinosinusitis is not just a single, uniform disease. Current evidence suggests that rhinosinusitis with neither polyps nor eosinophilic inflammation acts as a direct trigger for asthma, whereas rhinosinusitis with both polyps and eosinophilic inflammation shares underlying mechanisms with asthma. Clearly, however, there is considerable overlap between the different, complex mechanisms that link rhinosinusitis to asthma.

Induction of a late asthmatic response associated with airway inflammation in mice

To investigate mechanisms underlying the late asthmatic response, we developed a murine model using repetitive intratracheal antigen challenge. BALB/c mice sensitized by i.p. injection with ovalbumin+alum were challenged with ovalbumin intratracheally 4 times. The 1st challenge induced early airway obstruction peaking at 30 min but without a late response; however, the 4th challenge caused not only early but also late airway obstruction at 2-8 h. Eosinophils, and CD4+ and CD8+ T lymphocytes were increased in the airway before the 4th but not before the 1st-3rd challenges. The numbers of IgE+/CD117+ (mast) cells were also increased in the lung before the 4th challenge. Levels of Th2 cytokines were also increased in the airway. Daily administration of dexamethasone during the challenge period suppressed all these inflammatory events. Thus, this experimental late asthmatic response is associated with Th2 cytokine production from inflammatory cells recruited as a consequence of the 1st-3rd challenges.

Epicutaneous antigen exposure primes for experimental eosinophilic esophagitis in mice

BACKGROUND & AIMS

Eosinophilic esophagitis (EE) is frequently associated with atopic disease, including dermatitis and asthma. Data are emerging that atopic skin may provide an early entry point for antigen sensitization. We aimed to test the hypothesis that epicutaneous exposure to antigen primes for subsequent respiratory antigen-induced EE.

METHODS

Wild-type and genetically engineered mice were subjected to epicutaneous antigen sensitization and the development of experimental EE, and immune responses were examined.

RESULTS

We show that exposure to antigen via the epicutaneous route primes for marked eosinophilic inflammation in the esophagus triggered by a single airway antigen challenge. The development of experimental EE is associated with significant skin eosinophilia, accelerated bone marrow eosinophilopoiesis, blood eosinophilia, and large increases in serum antigen-specific immunoglobulin G1/immunoglobulin E using ovalbumin or Aspergillus fumigatus as the epicutaneous antigen. Mechanistic analysis with gene-targeted mice showed that interleukin-5 was required for esophageal eosinophilia and that interleukin-4, interleukin-13, and STAT6 contributed to a lesser extent.

CONCLUSIONS

These findings provide the first evidence that epicutaneous exposure to allergens potently primes for EE via a Th2-dependent mechanism.

Atopic march: link to upper airways

PURPOSE OF REVIEW

This review examines the role of the upper airways in the atopic march. Evidence examining the theory that allergic rhinitis precedes asthma will be discussed. In addition, the role of allergic rhinitis as an end point in the atopic march will be reviewed.

RECENT FINDINGS

Ciprandi and colleagues found that nasal symptoms, airflow and markers of inflammation (eosinophils, cytokine levels) directly correlated with lower airway markers. This confirms previous studies finding that many patients with allergic rhinitis have lower airway hyperreactivity or bronchial hyperresponsiveness and the link between upper and lower airways. Leynaert and colleagues questioned over 90 000 individuals and found that patients with rhinitis have increased risk for asthma and lower airway reactivity compared with patients without rhinitis. In the German Multicenter Atopy Study, a longitudinal study of 1300 children, patients with atopic dermatitis were found to have increased risk for asthma at 7 years of age. Patients with atopic dermatitis and no wheezing in the first 3 years, however, did not have an increased risk for developing current wheezing or bronchial hyperresponsiveness at 7 years of age. It was proposed that atopic dermatitis and asthma are linked, but atopic dermatitis does not precede asthma.

SUMMARY

Allergic rhinitis is a risk factor for asthma and can precede asthma in the atopic march.

An evaluation of peripheral blood eosinophil/basophil progenitors following nasal allergen challenge in patients with allergic rhinitis

OBJECTIVE

To evaluate the effect of a single nasal allergen challenge on peripheral blood eosinophil/basophil (Eo/B) progenitor cells and induced sputum eosinophil counts in subjects with allergic rhinitis.

METHODS

Sixteen adults entered a sequential nasal control and allergen challenge study, outside the pollen season. Blind assessment of peripheral blood Eo/B progenitor colony forming units (CFU), induced sputum and nasal lavage cell counts was made before and 24 h after both challenges. Subjects recorded their rhinitis symptoms and nasal peak inspiratory flow, hourly at home, following both challenges.

RESULTS

When comparing the values 24 h after the control vs. the allergen challenge, there were no significant differences in Eo/B progenitor CFU (control (mean, SD): 3.6 (1.0)/10(6) cells; allergen: 4.4 (1.1)/10(6) cells) or sputum eosinophils (control (median, inter-quartile range): 1.0 (0.3-1.7)%; allergen: 0.7 (0.0-1.3)%) despite a significant increase in the percentage (median (inter-quartile range) of eosinophils in nasal lavage (control: 0.6 (0.1-0.9)%; allergen; 1.9 (0.9-8.1)% and significant worsening of nasal peak inspiratory flow and rhinitis symptoms.

CONCLUSIONS

Despite a significant increase in nasal symptoms and lavage eosinophil counts, a single nasal allergen challenge was not sufficient to elicit a measurable haemopoietic response in circulation, or an increase in sputum eosinophil counts.

Rhinosinusitis and pediatric asthma

Rhinosinusitis is a common disease in patients of all age groups. Rhinosinusitis arises from a variety of infectious and inflammatory mechanisms. There is ample evidence that rhinosinusitis can directly influence asthma. There is also growing evidence that rhinosinusitis may be associated with asthma as different manifestations of the same disorder. A great deal of future research is required to fully elucidate the different mechanisms whereby rhinosinusitis influences or associates with asthma, but it is clear that rhinosinusitis needs to be considered in patients with severe or refractory asthma.

Identification of a cooperative mechanism involving interleukin-13 and eotaxin-2 in experimental allergic lung inflammation

Pulmonary eosinophilia, a hallmark pathologic feature of allergic lung disease, is regulated by interleukin-13 (IL-13) as well as the eotaxin chemokines, but the specific role of these cytokines and their cooperative interaction are only partially understood. First, we elucidated the essential role of IL-13 in the induction of the eotaxins by comparing IL-13 gene-targeted mice with wild type control mice by using an ovalbumin-induced model of allergic airway inflammation. Notably, ovalbumin-induced expressions of eotaxin-1 and eotaxin-2 mRNA in the lungs were almost completely dependent upon IL-13. Second, in order to address the specific role of eotaxin-2 in IL-13-induced pulmonary eosinophilia, we generated eotaxin-2 gene-deficient mice by homologous recombination. Notably, in contrast to observations made in eotaxin-1-deficient mice, eotaxin-2-deficient mice had normal base-line eosinophil levels in the hematopoietic tissues and gastrointestinal tract. However, following intratracheal IL-13 administration, eotaxin-2-deficient mice showed a profound reduction in airway eosinophilia compared with wild type mice. Most interestingly, the level of peribronchial lung tissue eosinophils in IL-13-treated eotaxin-2-deficient mice was indistinguishable from wild type mice. Furthermore, IL-13 lung transgenic mice genetically engineered to be deficient in eotaxin-2 had a marked reduction of luminal eosinophils. Mechanistic analysis identified IL13-induced eotaxin-2 expression by macrophages in a distinct lung compartment (luminal inflammatory cells) compared with eotaxin-1, which was expressed solely in the tissue. Taken together, these results demonstrate a cooperative mechanism between IL-13 and eotaxin-2. In particular, IL-13 mediates allergen-induced eotaxin-2 expression, and eotaxin-2 mediates IL-13-induced airway eosinophilia.