Emerging immune targets for the therapy of allergic asthma

Targeting the Notch Signaling Pathway in Chronic Inflammatory Diseases

The Notch signaling pathway regulates developmental cell-fate decisions and has recently also been linked to inflammatory diseases. Although therapies targeting Notch signaling in inflammation in theory are attractive, their design and implementation have proven difficult, at least partly due to the broad involvement of Notch signaling in regenerative and homeostatic processes. In this review, we summarize the supporting role of Notch signaling in various inflammation-driven diseases, and highlight efforts to intervene with this pathway by targeting Notch ligands and/or receptors with distinct therapeutic strategies, including antibody designs. We discuss this in light of lessons learned from Notch targeting in cancer treatment. Finally, we elaborate on the impact of individual Notch members in inflammation, which may lay the foundation for development of therapeutic strategies in chronic inflammatory diseases.

A novel therapeutic modality using CRISPR-engineered dendritic cells to treat allergies

Despite the important roles of dendritic cells (DCs) in airway allergies, current therapeutic strategies such as drugs, allergen immunotherapy and biologics haven't been targeted at them. In this study, we established a promising DC-based therapeutic approach for the alleviation of allergic rhinitis (AR)-associated allergic reactions, using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated targeted gene disruption. RNA sequencing analysis revealed upregulation of vacuolar protein sorting 37 B (VPS37B) in AR-derived DCs, indicating a novel molecular target. Following antigen presentation, VPS37A and VPS37B enabled endocytosis of the mannose receptor, which recognizes the house dust mite (HDM) allergen Der p 1. DCs with targeted disruption of VPS37A/B alleviated Th2 cytokine production when co-cultured in vitro with allogeneic naïve CD4⁺ T cell from patients with AR. Furthermore, nasal administration of Vps37a/b-disrupted bone marrow DCs to a mouse model of AR resulted in strongly reduced AR-related symptoms. Thus, this novel modality using genetically engineered DCs can provide an effective therapeutic and preventative strategy for allergic diseases.

The role of miR-29c/B7-H3 axis in children with allergic asthma

Background

MicroRNAs play roles in the pathogenesis of bronchial asthma. However, the mechanism of miR-29c in allergic asthma remains unclear. This study is to elucidate the regulation of Th cell differentiation by miR-29c in mononuclear macrophages.

Methods

A total of 52 children with asthma exacerbation and 26 children as controls were enrolled in the study. CD14⁺ monocytes were isolated from the peripheral blood. Differential expressions of microRNAs were evaluated using microarray analysis and miR-29c expression in monocytes was determined by qRT-PCR. The plasma B7-H3 was determined by ELISA. Transfection studies and luciferase reporter assay were performed to confirm target gene of miR-29c and its function.

Results

Compared to controls, 88 miRNAs in blood monocytes were up-regulated and 41 miRNAs down-regulated including miR-29c in asthma children. Children with asthma exacerbation had significantly lower level of miR-29c and higher level of plasma B7-H3 compared to controls (both P < 0.05). Functional studies based on luciferase reporter assay and immunofluorescence staining suggest that B7-H3 is the direct target of miR-29c and transfection anti-miR-29c into macrophages could enhance ROR-γt and GATA-3 expression in co-cultured CD4⁺ T cells and increase levels of IL-4 and IL-17 in supernatants.

Conclusion

The axis of miR-29c/B7-H3 plays an important role in children with asthma through regulating Th2/Th17 cell differentiation and may provide new targets for treatment of asthma.

Ginsenoside Rg1 Exhibits Anti-asthmatic Activity in an Aspergillus Protease-Induced Asthma Model in Mice

Asthma is one of the most common chronic airway diseases and is characterized by symptoms, such as, wheezing and coughing. Its prevalence in Korea is gradually increasing among children and adults, especially among those older than 60 years. In this study, we investigated the effects of ginsenoside Rg1 (Rg1), one of the major constituents of Panax ginseng Meyer on ovalbumin (OVA) plus Aspergillus protease ( A. protease) allergen-induced asthmatic mice. Mice were orally administered Rg1 for 10 days from 8 days after OVA + A. protease sensitization and intranasally administered booster doses of OVA + A. protease for 4 days from 14 days after sensitization. The effects of Rg1 administration on airway hyperresponsiveness (AHR), immune cell distributions in bronchoalveolar lavage fluid (BALF), and serum level of immunoglobulin E (IgE) were investigated at 18 days after sensitization. Histopathological changes in hematoxylin and eosin (H&E)-stained lung sections were also examined. Treatment of OVA + A. protease-sensitized/challenged asthmatic mice with Rg1 significantly decreased total eosinophil counts in BALF as compared with those of phosphate-buffered saline (PBS)-treated sensitized/challenged controls, and significantly decreased methacholine-induced AHR. Furthermore, IgE serum levels were significantly lower in Rg1 administered OVA + A. protease-sensitized asthmatic mice than in PBS-treated sensitized/challenged controls. The study shows Rg1 protects against A. protease allergen-induced asthma in mice.

Inhibitory effects of l-theanine on airway inflammation in ovalbumin-induced allergic asthma

l-theanine, a water-soluble amino acid isolated from green tea (Camellia sinensis), has anti-inflammatory activity, antioxidative properties, and hepatoprotective effects. However, the anti-allergic effect of l-theanine and its underlying molecular mechanisms have not been elucidated. In this study, we investigated the protective effects of l-theanine on asthmatic responses, particularly airway inflammation and oxidative stress modulation in an ovalbumin (OVA)-induced murine model of asthma. Treatment with l-theanine dramatically attenuated the extensive trafficking of inflammatory cells into bronchoalveolar lavage fluid (BALF). Histological studies revealed that l-theanine significantly inhibited OVA-induced mucus production and inflammatory cell infiltration in the respiratory tract and blood vessels. l-theanine administration also significantly decreased the production of IgE, monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-4, IL-5, IL-13, tumor necrosis factor-alpha (TNF-α), and interferon-gamma in BALF. The lung weight decreased with l-theanine administration. l-theanine also markedly attenuated the OVA-induced generation of reactive oxygen species and the activation of nuclear factor kappa B (NF-κB) and matrix metalloprotease-9 in BALF. Moreover, l-theanine reduced the TNF-α-induced NF-κB activation in A549 cells. Together, these results suggest that l-theanine alleviates airway inflammation in asthma, which likely occurs via the oxidative stress-responsive NF-κB pathway, highlighting its potential as a useful therapeutic agent for asthma management.

A Study of Agastachis Herba on Ovalbumin-induced Asthma in the Mouse

Agastachis Herba is one of the well-known medicinal herbs in Korean traditional medicine. This study was taken up to examine the beneficial effects of Agastachis Herba on a mice model of asthma. BALB/c mice were sensitized and challenged with ovalbumin to produce a murine model of asthma. Methanol extracts of Agastachis Herba were orally administered to the ovalbumin-induced asthmatic mice. The effects of methanol extract of Agastachis Herba on airway hyper responsiveness, immune cell distributions in bronchoalveolar lavage fluid, ovalbumin-specific immunoglobulin E in serum, and histopathological changes were evaluated. Mice treated with the methanol extract of Agastachis Herba showed reduction of airway hyper responsiveness as well as inhibited immune cell infiltration in bronchoalveolar region. Also ovalbumin-specific immunoglobulin E levels in bronchoalveolar lavage fluid significantly decreased in extract treated mice. Histopathological findings showed significant beneficial changes in inflammatory cell infiltration.

[Genome wide expression analysis of the effect of Socheongryong Tang in asthma model of mice]

OBJECTIVE

To investigate the molecular effect of Socheongryong Tang (SCRT, Xiaoqinglong Tang in Chinese) on whole genome level in asthma mouse model by microarray technology.

METHODS

Asthma was induced by intranasal instillation of ovalbumin in mouse. After administration of SCRT on asthma-induced mouse, the expression of genes in lung tissue was measured using whole genome microarray. The functional implication of differentially expressed genes was performed using ontological analysis and the similarity of promoter structure of genes was also analyzed.

RESULTS

Treatment of SCRT restored expression level of many up- or down-regulated genes in asth- ma model, and this recovery rate means SCRT could regulate a set of genes having specific TFBS binding sites.

CONCLUSION

In this study, we identified a set of genes subjected to similar regulation by SCRT in asthma model in mice.

Saponins, especially platyconic acid A, from Platycodon grandiflorum reduce airway inflammation in ovalbumin-induced mice and PMA-exposed A549 cells

We investigated the inhibitory effects of Platycodon grandiflorum root-derived saponins (Changkil saponins: CKS) on ovalbumin-induced airway inflammation in mice. CKS suppressed leukocytes number, IgE, Th1/Th2 cytokines, and MCP-1 chemokine secretion in bronchoalveolar lavage fluid. Also, ovalbumin-increased MUC5AC, MMP-2/9, and TIMP-1/-2 mRNA expression, NF-κB activation, leukocytes recruitment, and mucus secretion were inhibited by CKS treatment. Moreover, the active component of CKS, platyconic acid A (PA), suppressed PMA-induced MUC5AC mRNA expression (from 2.1 ± 0.2 to 1.1 ± 0.1) by inhibiting NF-κB activation (from 2.3 ± 0.2 to 1.2 ± 0.1) via Akt (from 3.7 ± 0.3 to 2.1 ± 0.2) (p < 0.01) in A549 cells. Therefore, we demonstrate that CKS or PA suppressed the development of respiratory inflammation, hyperresponsiveness, and remodeling by reducing allergic responses, and they may be potential herbal drugs for allergen-induced respiratory disease prevention.

So-Cheong-Ryong-Tang, a herbal medicine, modulates inflammatory cell infiltration and prevents airway remodeling via regulation of interleukin-17 and GM-CSF in allergic asthma in mice

Background:

So-Cheong-Ryong-Tang (SCRT), herbal medicine, has been used for the control of respiratory disease in East Asian countries. However, its therapeutic mechanisms, especially an inhibitory effect on inflammatory cell infiltration and airway remodeling in allergic asthma are unclear.

Objective:

The present study investigated the mechanism of antiasthmatic effects of SCRT in allergic asthma in mice.

Materials and Methods:

We investigated the influence of SCRT on levels of interleukin-17 (IL-17), granulocyte/macrophage colony-stimulating factor (GM-CSF), IL-4, and interferon gamma (IFN-γ) in bronchoalveolar lavage fluid (BALF), ovalbumin (OVA)-specific IgE in serum, and histopathological changes in allergen-induced asthma.

Results:

So-Cheong-Ryong-Tang decreased levels of IL-17 and GM-CSF in BALF. IL-4, a Th2-driven cytokine, was also decreased by SCRT, but IFN-γ, a Th1-driven cytokine, was not changed. Levels of OVA-specific IgE in serum were also decreased by SCRT. With SCRT treatment, histopathological findings showed reduced tendency of inflammatory cell infiltration, and prevention from airway remodeling such as epithelial hyperplasia.

Conclusion:

In this study, we firstly demonstrated that regulation of IL-17 and GM-CSF production may be one of the mechanism contributed to a reduction of inflammatory cell infiltration and prevention from airway remodeling.

Comparative study of Korean White Ginseng and Korean Red Ginseng on efficacies of OVA-induced asthma model in mice

Background

Korean ginseng is a well-known medicinal herb that has been widely used in traditional medicine to treat various diseases, including asthma. Ginseng can be classified as white ginseng (WG) or red ginseng (RG), according to processing conditions. In this study, the authors compared the efficacies of these two ginseng types in a mouse model of acute asthma.

Methods

To produce the acute asthma model, BALB/c mice were sensitized with ovalbumin (OVA) and aluminum hydroxide, and then challenged with OVA. WG and RG extracts were administered to mice orally. The influences of WG and RG on airway hyperresponsiveness (AHR), immune cell distributions in bronchoalveolar lavage fluid (BALF), and OVA-specific immunoglobulin E (IgE), IgG1, and IgG2a in serum were investigated. Cytokine production by lymphocytes isolated from peribronchial lymph nodes and histopathological changes was also examined.

Results

In OVA-sensitized mice, both WG and RG reduced AHR and suppressed immune cell infiltration in bronchoalveolar regions. BALF OVA-specific IgE levels were significantly lower in RG-treated OVA-sensitized mice than in the OVA-sensitized control group. WG and RG also suppressed inflammatory cytokine production by peribronchial lymphocytes. Histopathological findings showed reduced inflammatory cell infiltration and airway remodeling (e.g., epithelial hyperplasia) in WG- and RG-treated OVA mice compared with OVA controls.

Conclusion

In this study, WG and RG showed antiasthmatic effects in an OVA-sensitized mouse model, and the efficacies of RG were found to be better than those of WG.

Anti-asthmatic activities of an ethanol extract of Aster yomena in an ovalbumin-induced murine asthma model

Aster yomena is used in traditional remedies to treat cough, asthma and insect bites; however, its therapeutic mechanism is not completely understood. To elucidate the anti-asthmatic effect of A. yomena, we investigated the anti-asthmatic characteristics of an alcohol extract of A. yomena in an ovalbumin (OVA)-induced murine asthma model. In this study, we showed that A. yomena extract inhibited the overall pathophysiological features of asthma by suppressing Th2 responses and enzymes associated with the production of inflammatory mediators. This suppression resulted in decreased Th2 type cytokines and eosinophils in the bronchoalveolar lavage fluid and OVA-specific IgE in serum. Additionally, A. yomena extract significantly decreased airway hyperresponsiveness and abrogated the histopathological changes in the lungs, which reached normal levels in the OVA-challenged mice treated with A. yomena extract. These findings suggest that A. yomena could be a promising natural agent for treating bronchial asthma in humans.

Treatment with pyranopyran-1, 8-dione attenuates airway responses in cockroach allergen sensitized asthma in mice

Chronic allergic asthma is characterized by Th2-typed inflammation, and contributes to airway remodeling and the deterioration of lung function. Viticis Fructus (VF) has long been used in China and Korea as a traditional herbal remedy for treating various inflammatory diseases. Previously, we have isolated a novel phytochemical, pyranopyran-1, 8-dione (PPY), from VF. This study was conducted to evaluate the ability of PPY to prevent airway inflammation and to attenuate airway responses in a cockroach allergen-induced asthma model in mice. The mice sensitized to and challenged with cockroach allergen were treated with oral administration of PPY. The infiltration of total cells, eosinophils and lymphocytes into the BAL fluid was significantly inhibited in cockroach allergen-induced asthma mice treated with PPY (1, 2, or 10 mg/kg). Th2 cytokines and chemokine, such as IL-4, IL-5, IL-13 and eotaxin in BAL fluid were also reduced to normal levels following treatment with PPY. In addition, the levels of IgE were also markedly suppressed after PPY treatment. Histopathological examination demonstrated that PPY substantially inhibited eosinophil infiltration into the airway, goblet cell hyperplasia and smooth muscle hypertrophy. Taken together, these results demonstrate that PPY possesses a potent efficacy on controlling allergic asthma response such as airway inflammation and remodeling.

CD11a polymorphisms regulate TH2 cell homing and TH2-related disease

BACKGROUND

TH2-dependent diseases vary in severity according to genotype, but relevant gene polymorphisms remain largely unknown. The integrin CD11a is a critical determinant of allergic responses, and allelic variants of this gene might influence allergic phenotypes.

OBJECTIVE

We sought to determine major CD11a allelic variants in mice and human subjects and their importance to allergic disease expression.

METHODS

We sequenced mouse CD11a alleles from C57BL/6 and BALB/c strains to identify major polymorphisms; human CD11a single nucleotide polymorphisms were compared with allergic disease phenotypes as part of the international HapMap project. Mice on a BALB/c or C57BL/6 background and congenic for the other strain's CD11a allele were created to determine the importance of mouse CD11a polymorphisms in vivo and in vitro.

RESULTS

Compared with the C57BL/6 allele, the BALB/c CD11a allele contained a nonsynonymous change from asparagine to aspartic acid within the metal ion binding domain. In general, the BALB/c CD11a allele enhanced and the C57BL/6 CD11a allele suppressed TH2 cell-dependent disease caused by the parasite Leishmania major and allergic lung disease caused by the fungus Aspergillus niger. Relative to the C57BL/6 CD11a allele, the BALB/c CD11a allele conferred both greater T-cell adhesion to CD54 in vitro and enhanced TH2 cell homing to lungs in vivo. We further identified a human CD11a polymorphism that significantly associated with atopic disease and relevant allergic indices.

CONCLUSIONS

Polymorphisms in CD11a critically influence TH2 cell homing and diverse TH2-dependent immunopathologic states in mice and potentially influence the expression of human allergic disease.

Fringe controls naïve CD4(+)T cells differentiation through modulating notch signaling in asthmatic rat models

The ability of Notch signaling to regulate T helper cell development and differentiation has been widely accepted. Fringe, O-fucose-β1,3-N-acetylglucosaminyltransferases modulate Notch receptor expression and promote the Notch signaling pathway through receptor-ligand binding. In this study, we assayed the expression levels of three Fringe homologs in naive CD4⁺T cells in asthmatic rats. We found that Radical Fringe (Rfng) was highly expressed, whereas both Lunatic Fringe (Lfng) and Manic Fringe (Mfng) were expressed at low levels. Down-regulation of Rfng using siRNA, and overexpression of Lfng or Mfng enhanced Th1 subset lineages and diminished Th2 subset lineages. Notch signaling was more activated in asthmatic naïve CD4⁺T cells than in control cells, and Lfng, but not Mfng or Rfng, partly inhibited Notch signaling in asthmatic naïve CD4⁺T lymphocytes. Lfng overexpression resulted in significantly decreased Th2 cytokine production in asthma, which was the same effect as the GSI (γ-secretase inhibitor) treatment alone, but had an increased effect on Th1 cytokines than GSI treatment. Collectively, these data identify the essential role of Fringe modulating naïve CD4⁺T cells differentiation through Notch signaling. Lfng regulated Th2 cells differentiation via a Notch-dependent manner and Th1 cells differentiation via a Notch-independent manner. Fringe could be a therapeutic strategy for the management and prevention of allergic asthma.

Oral Nigella sativa oil ameliorates ovalbumin-induced bronchial asthma in mice

Nigella sativa oil (NSO) is used in folk medicine as a therapy for many diseases including bronchial asthma. We investigated the possible modulating effects of NSO on asthma-like phenotypes in a mouse model of bronchial asthma. BALB/c mice were actively sensitized by intraperitoneal injections of 50 μg ovalbumin (OVA) with 1mg alum on days 0 and 12. Starting on day 22, they were exposed to OVA (1% (w/v), in sterile physiological saline) for 30 min, three times every 4th day. Negative control animals were exposed to saline in a similar manner. NSO was administered orally for 31 day from day 0 to day 30. On the day of sensitization and challenge, NSO was given 30 min before the treatment. Airway function, number of inflammatory cells in bronchoalveolar lavage fluid (BALF), levels of interleukin (IL)-4, IL-5, IL-13 and interferon (IFN)-γ in BALF, serum levels of total IgE, OVA-specific IgE, IgG1 and IgG2a, and histopathological examination of lung tissues were investigated. Oral treatment with NSO showed significant decrease in airway hyperresponsiveness, the number of total leukocytes, macrophages and eosinophils, levels of IL-4, IL-5 and IL-13 in BALF, serum levels of total IgE, OVA-specific IgE and IgG1, and significant increase in BALF level of IFN-γ and serum level of OVA-specific IgG2a, indicating restoration of local Th1/Th2 balance. Furthermore, it significantly abrogated the histopathological changes of the lungs, as the images were nearly normal. These results suggest that the treatment with oral NSO could be a promising treatment for bronchial asthma in humans.

Allergic asthmatics show divergent lipid mediator profiles from healthy controls both at baseline and following birch pollen provocation

BACKGROUND

Asthma is a respiratory tract disorder characterized by airway hyper-reactivity and chronic inflammation. Allergic asthma is associated with the production of allergen-specific IgE and expansion of allergen-specific T-cell populations. Progression of allergic inflammation is driven by T-helper type 2 (Th2) mediators and is associated with alterations in the levels of lipid mediators.

OBJECTIVES

Responses of the respiratory system to birch allergen provocation in allergic asthmatics were investigated. Eicosanoids and other oxylipins were quantified in the bronchoalveolar lumen to provide a measure of shifts in lipid mediators associated with allergen challenge in allergic asthmatics.

METHODS

Eighty-seven lipid mediators representing the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 (CYP) metabolic pathways were screened via LC-MS/MS following off-line extraction of bronchoalveolar lavage fluid (BALF). Multivariate statistics using OPLS were employed to interrogate acquired oxylipin data in combination with immunological markers.

RESULTS

Thirty-two oxylipins were quantified, with baseline asthmatics possessing a different oxylipin profile relative to healthy individuals that became more distinct following allergen provocation. The most prominent differences included 15-LOX-derived ω-3 and ω-6 oxylipins. Shared-and-Unique-Structures (SUS)-plot modeling showed a correlation (R(2) = 0.7) between OPLS models for baseline asthmatics (R(2)Y[cum] = 0.87, Q(2)[cum] = 0.51) and allergen-provoked asthmatics (R(2)Y[cum] = 0.95, Q(2)[cum] = 0.73), with the majority of quantified lipid mediators and cytokines contributing equally to both groups. Unique structures for allergen provocation included leukotrienes (LTB(4) and 6-trans-LTB(4)), CYP-derivatives of linoleic acid (epoxides/diols), and IL-10.

CONCLUSIONS

Differences in asthmatic relative to healthy profiles suggest a role for 15-LOX products of both ω-6 and ω-3 origin in allergic inflammation. Prominent differences at baseline levels indicate that non-symptomatic asthmatics are subject to an underlying inflammatory condition not observed with other traditional mediators. Results suggest that oxylipin profiling may provide a sensitive means of characterizing low-level inflammation and that even individuals with mild disease display distinct phenotypic profiles, which may have clinical ramifications for disease.

Panax ginseng ameliorates airway inflammation in an ovalbumin-sensitized mouse allergic asthma model

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng (PG) is a medicinal herb that has been used to treat various immune diseases including asthma and COPD. In this study, we investigated the inhibitory mechanism of PG on asthma parameters in mice.

MATERIALS AND METHODS

BALB/c mice were sensitized with 20 μg/200 μl OVA adsorbed on 1.0mg/50 μl aluminum hydroxide gel adjuvant by i.p. injection on days 0 and 14. Mice were then challenged with 5% OVA in PBS to the nose for 30 min once a day for 3 days, from day 20 until day 22, using a nebulizer. PG (20mg/kg) or vehicle was administrated by i.p. injection once a day 10 min before every OVA challenge for 3 days. The recruitment of inflammatory cells into bronchoalveolar lavage fluid or lung tissues was measured. The expression of EMBP, Muc5ac, CD40, and CD40 ligand (CD40L) in lung tissues was investigated. In addition, the cytokines and mitogen activated protein (MAP) kinases were measured by RT-PCR and Western blot.

RESULTS AND CONCLUSIONS

PG restored the expression of EMBP, Muc5ac, CD40, and CD40L, as well as the mRNA and protein levels of interleukin (IL)-1β, IL-4, IL-5, and tumor necrosis factor (TNF)-α. In addition, PG inhibited the numbers of goblet cells and further small G proteins and MAP kinases in bronchoalveolar lavage cells and lung tissues increased in ovalbumin-induced allergic asthma in mice. These results suggest that PG may be used as a therapeutic agent in asthma, based on reductions of various allergic responses.

Anti-inflammatory effects of the R2 peptide, an inhibitor of transglutaminase 2, in a mouse model of allergic asthma, induced by ovalbumin

BACKGROUND AND PURPOSE

Transglutaminase 2 (TGase 2) expression is increased in inflammatory diseases, and TGase 2 inhibitors block these increases. We examined whether the R2 peptide inhibited the expression of TGase 2 in a mouse model of inflammatory allergic asthma.

EXPERIMENTAL APPROACH

C57BL/6 mice were sensitized and challenged by ovalbumin (OVA) to induce asthma. OVA-specific serum IgE and leukotrienes (LTs) levels were measured by enzyme-linked immunosorbent assay. Recruitment of inflammatory cells into bronchoalveolar lavage (BAL) fluid or lung tissues and goblet cell hyperplasia were assessed histologically. Airway hyperresponsiveness was determined in a barometric plethysmographic chamber. Expression of TGase 2, eosinophil major basic protein (EMBP), the adhesion molecule vascular cell adhesion molecule-1, Muc5ac and phospholipase A(2) (PLA(2) ) protein were determined by Western blot. Expression of mRNAs of Muc5ac, cytokines, matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) were measured by reverse transcriptase-polymerase chain reaction and nuclear factor-κB (NF-κB) by electrophoretic mobility shift assay.

KEY RESULTS

R2 peptide reduced OVA-specific IgE levels; the number of total inflammatory cells, macrophages, neutrophils, lymphocytes and eosinophils in BAL fluid and the number of goblet cells. Airway hyperresponsiveness, TGase 2 and EMBP levels, mRNA levels of interleukin (IL)-4, IL-5, IL-6, IL-8, IL-13, RANTES, tumour necrosis factor-α, and MMP2/9, Muc5ac, NF-κB activity, PLA(2) activity and expressions, and LT levels in BAL cells and lung tissues were all reduced by R2 peptide. R2 peptide also restored expression of TIMP1/2.

CONCLUSION AND IMPLICATIONS

R2 peptide reduced allergic responses by regulating NF-κB/TGase 2 activity in a mouse model of allergic asthma. This peptide may be useful in the treatment of allergic asthma.

Seeking common pathophysiology in asthma, atopy and sinusitis

Asthma and chronic sinusitis are inexplicably common airway diseases that are linked to atopy and allergic inflammation. T helper type 2 (Th2) cells and the associated cytokines are believed to play crucial pathogenic roles in asthma, but the environmental factors that instigate allergic airway disease remain poorly understood. Environmental proteinases are highly allergenic and are candidate inducers of airway Th2 responses. Determining the proteinases and their sources that are relevant to airway disease, however, remains challenging. In this Opinion, we summarize the evidence that implicates fungi as both a relevant source of allergenic proteinases and a potential cause of asthma, atopy and chronic sinusitis through airway infection. Clarification of the extrinsic causes of these processes will markedly improve diagnosis, prognosis and therapy.

Protective role of interleukin-10 in ozone-induced pulmonary inflammation

BACKGROUND

The mechanisms underlying ozone (O₃)-induced pulmonary inflammation remain unclear. Interleukin-10 (IL-10) is an anti-inflammatory cytokine that is known to inhibit inflammatory mediators.

OBJECTIVES

We investigated the molecular mechanisms underlying interleuken-10 (IL-10)-mediated attenuation of O₃-induced pulmonary inflammation in mice.

METHODS

Il10-deficient (Il10(-/-)) and wild-type (Il10(+/+)) mice were exposed to 0.3 ppm O₃ or filtered air for 24, 48, or 72 hr. Immediately after exposure, differential cell counts and total protein (a marker of lung permeability) were assessed from bronchoalveolar lavage fluid (BALF). mRNA and protein levels of cellular mediators were determined from lung homogenates. We also used global mRNA expression analyses of lung tissue with Ingenuity Pathway Analysis to identify patterns of gene expression through which IL-10 modifies O₃-induced inflammation.

RESULTS

Mean numbers of BALF polymorphonuclear leukocytes (PMNs) were significantly greater in Il10(-/-) mice than in Il10(+/+) mice after exposure to O₃ at all time points tested. O₃-enhanced nuclear NF-κB translocation was elevated in the lungs of Il10(-/-) compared with Il10(+/+) mice. Gene expression analyses revealed several IL-10-dependent and O₃-dependent mediators, including macrophage inflammatory protein 2, cathepsin E, and serum amyloid A3.

CONCLUSIONS

Results indicate that IL-10 protects against O₃-induced pulmonary neutrophilic inflammation and cell proliferation. Moreover, gene expression analyses identified three response pathways and several genetic targets through which IL-10 may modulate the innate and adaptive immune response. These novel mechanisms of protection against the pathogenesis of O₃-induced pulmonary inflammation may also provide potential therapeutic targets to protect susceptible individuals.

Intradermal cytosine-phosphate-guanosine treatment reduces lung inflammation but induces IFN-γ-mediated airway hyperreactivity in a murine model of natural rubber latex allergy

Asthma and other allergic diseases are continuously increasing, causing considerable economic and sociologic burden to society. The hygiene hypothesis proposes that lack of microbial T helper (Th) 1-like stimulation during early childhood leads to increased Th2-driven allergic disorders later in life. Immunostimulatory cytosine-phosphate-guanosine (CpG)-oligodeoxynucleotide motifs are candidate molecules for immunotherapeutic studies, as they have been shown to shift the Th2 response toward the Th1 direction and reduce allergic symptoms. Using natural rubber latex (NRL)-induced murine model of asthma, we demonstrated that intradermal CpG administration with allergen reduced pulmonary eosinophilia, mucus production, and Th2-type cytokines, but unexpectedly induced airway hyperreactivity (AHR) to inhaled methacholine, one of the hallmarks of asthma. We found that induction in AHR was dependent on STAT4, but independent of STAT6 signaling. CpG treatment increased production of IFN-γ in the airways and shifted the ratio of CD4(+):CD8(+) T cells toward CD8(+) dominance. By blocking soluble IFN-γ with neutralizing antibody, AHR diminished and the CD4(+):CD8(+) ratio returned to CD4(+) dominance. These results indicate that increased production of IFN-γ in the lungs may lead to severe side effects, such as enhancement of bronchial hyperreactivity to inhaled allergen. This finding should be taken into consideration when planning prophylaxis treatment of asthma with intradermal CpG injections.

Thymic stromal lymphopoietin promotes lung inflammation through activation of dendritic cells

Asthma is an epithelial disorder in which T helper 2 (Th2)-type inflammation has a prominent role. Recent studies indicated that a cytokine, thymic stromal lymphopoietin (TSLP), is essential for the development of antigen-induced asthma. The authors used ovalbumin (OVA) sensitization and challenge to induce a murine asthmatic model. The model was confirmed by airway hyperresponsiveness, serum levels of total and OVA-specific immunoglobulin (IgE), histological analysis of lung tissues. The authors found that expression of TSLP was significantly increased in both mRNA and protein levels in mice lungs treated with OVA. The expression of CD40, CD80, and CD86 in bronchoalveolar lavage fluid (BALF) was increased in mice with OVA. Tight correlation between TSLP mRNA and interleukin (IL)-4, IL-5, and IL-13 in BALF was identified. Furthermore, treating mice with TSLP-neutralizing antibody reduced the expression of TSLP mRNA of lungs, CD40, CD80, and CD86 on dendritic cells, and IL-4, IL-5, and IL-13 in the OVA group. This study indicates that TSLP is increased in the airway epithelium in mice treated with OVA. In the lung inflammation model, TSLP activates dendritic cells (DCs) via up-regulation of CD40, CD80, and CD86, then induces the differentiation of prime naive CD4(+) T cells to become proinflammatory Th2 cells. Blocking TSLP is capable of inhibiting the production of Th2 cytokines, thus presents a promising strategy for the treatment of asthma.

Allergen provocation increases TH2-cytokines and FOXP3 expression in the asthmatic lung

BACKGROUND

Allergic asthma is caused by allergen-specific IgE and T-helper cell (Th) type 2 responses towards airborne allergens. The objective of this study was to investigate local and systemic regulatory mechanisms in the early asthmatic response to bronchial allergen provocation.

METHODS

Birch pollen-allergic patients with mild asthma (n = 13) and healthy nonallergic controls (n = 14) were subjected to bronchoalveolar lavage (BAL) and blood sampling. On patients BAL was performed twice: without preceding provocation ('before samples') and 24 h after bronchial provocation with birch pollen allergen. Lymphocytes in BAL and peripheral blood mononuclear cells (PBMCs) were phenotyped by multi-colour flow cytometry and cytokines measured by cytometric bead array. Proliferation and secreted cytokines were analysed in allergen-stimulated PBMCs, CD25(+) depleted PBMCs and PBMCs with IL-10 neutralizing antibodies.

RESULTS

The numbers of CD69(+) and FOXP3(+) lymphocytes were higher in BAL after compared with before allergen provocation in asthmatic patients. Moreover, allergen provocation increased expression of FOXP3 in CD4(+)CD25(bright) cells. The cytokine profile in BAL fluid from asthmatics revealed higher levels of IL-5, compared with the controls, and an increase in IL-5, IL-6, IL-9 and IL-10 after allergen provocation. Pollen allergen stimulated PBMC cultures from asthmatic patients produced elevated levels of IL-5 and IL-13 compared with the controls, which were not affected by depletion of CD25(+) cells or IL-10 neutralization.

CONCLUSION

Despite an increase in CD4(+)CD25(bright) cells expressing high levels of FOXP3 in response to bronchial allergen provocation, asthmatic patients exhibit enhanced levels of Th2 cytokines in the lung, which may indicate an inability among infiltrating cells to suppress Th2 responses.

The role of thymic stromal lymphopoietin in allergic inflammation and chronic obstructive pulmonary disease

Thymic stromal lymphopoietin (TSLP) primes dendritic cells to promote a Th2 inflammatory response. Its action is mediated by a heterodimeric receptor which consists of the interleukin-7 receptor alpha chain and the TSLP receptor chain (TSLPR). TSLPR resembles the common gamma chain subunit utilized by many type 1 cytokine receptors. Normal epithelial cells, keratinocytes, and stromal cells constitutively express TSLP. Dendritic cells that are activated by TSLP promote the development of CD4(+) T cells into pro-inflammatory Th2 cells. TSLP thus plays a potentially important role in the pathogenesis of allergic inflammation in asthma and atopic dermatitis. TSLP also has direct effects on other types of cells in the bronchial mucosa. It is over-expressed in the bronchial mucosa in chronic obstructive pulmonary disease (COPD), which is traditionally described as a Th1-related disease, as well as severe asthma, which is traditionally described as a Th2-related disease. In this review we will discuss TSLP expression, function, and available and potential mechanisms in both allergic inflammation and COPD.

Developmental control of integrin expression regulates Th2 effector homing

Integrin CD18, a component of the LFA-1 complex that also includes CD11a, is essential for Th2, but not Th1, cell homing, but the explanation for this phenomenon remains obscure. In this study, we investigate the mechanism by which Th2 effector responses require the LFA-1 complex. CD11a-deficient T cells showed normal in vitro differentiation and function. However, Th2 cell-dependent allergic lung disease was markedly reduced in CD11a null mice and wild-type mice given LFA-1 inhibitors, whereas control of infection with Leishmania major, a Th1-dependent response, was enhanced. In both disease models, recruitment of IL-4-, but not IFN-gamma-secreting cells to relevant organs was impaired, as was adhesion of Th2 cells in vitro. These diverse findings were explained by the markedly reduced expression of CD29, an alternate homing integrin, on Th2, but not Th1, cells, which precludes Th2 homing in the absence of CD11a. Thus, murine Th1 and Th2 cells use distinct integrins for homing, suggesting novel opportunities for integrin-based therapeutic intervention in diverse human ailments influenced by Th2 cells.

Thymic stromal lymphopoietin: a new cytokine in asthma

Airway epithelial cells provide mechanical and immune protection against pathogens and allergens. Following activation, these cells produce a wide range of cytokines including thymic stromal lymphopoietin (TSLP). Recently it was established that a high level of TSLP is associated with asthma in mice and in humans. These findings suggest that interfering with the ability of cells to respond to TSLP might prevent the development of airway inflammation. Our review presents current knowledge on mediators that induce TSLP production and on the actions of TSLP on different populations of cells that are related to airway inflammation. TSLP affects dendritic cells, T cells, NKT cells, and mast cells, indicative of the broad role of TSLP in the regulation of inflammatory/allergic processes.

Allergen-specific polyclonal antibodies reduce allergic disease in a mouse model of allergic asthma

BACKGROUND

Recombinant allergen-specific immunoglobulin G (IgG) antibody therapy can reduce allergic asthma symptoms by inhibiting the immunoglobulin E (IgE)-mediated allergic response. This study investigated the effect of intranasally administered allergen-specific monoclonal (mAb) and polyclonal (pAb) antibody on airway inflammation and hyperresponsiveness (AHR) in a mouse model of human asthma.

METHODS

Ovalbumin (OVA)-specific IgG2b antibodies were generated by phage display using spleens from OVA-immunized mice, and screening against OVA and finally expressed in CHO cells. Sensitized mice were treated intranasally with either a recombinant anti-OVA mAb (gc32) or a polyclonal preparation comprising seven selected antibodies (including gc32). Control mice received diluent only, OVA only, a control polymeric IgG or dexamethasone. Following challenge with nebulized OVA, investigators assessed airway inflammation by histology and cellular composition of the bronchoalveolar fluid, and methacholine-induced airway hyperresponsiveness (AHR). Serum levels of total and OVA-specific IgE were measured by ELISA.

RESULTS

Sensitized mice developed airway inflammation and AHR in response to OVA challenge. Intranasally administered OVA-specific murine polyclonal or monoclonal IgG2b antibodies both reduced OVA-induced lung inflammation. Polyclonal, but not anti-OVA mAb, also reduced AHR and eosinophil influx into the airway lumen. Both anti-OVA antibody preparations reduced levels of specific IgE with no effect on total IgE levels.

CONCLUSIONS

Intranasal treatment with allergen-specific pAb reduces pulmonary inflammation and AHR in a mouse model of allergic asthma, but allergen-specific mAb reduces inflammation only. Allergen-specific recombinant pAb offers a potentially valuable therapeutic approach to the management of allergic asthma.

Kinase inhibitors and airway inflammation

Kinases are believed to play a crucial role in the expression and activation of inflammatory mediators in the airway, in T-cell function and airway remodelling. Important kinases such as Inhibitor of kappaB kinase (IKK)2, mitogen activated protein (MAP) kinases and phsopho-inositol (PI)3 kinase regulate inflammation either through activation of pro-inflammatory transcription factors such as activating protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB), which are activated in airway disease, or through regulation of mRNA half-life. Selective kinase inhibitors have been developed which reduce inflammation and some characteristics of disease in animal models. Targeting specific kinases that are overexpressed or over active in disease should allow for selective treatment of respiratory diseases. Interest in this area has intensified due to the success of the specific Abelson murine leukaemia viral oncogene (Abl) kinase inhibitor imatinib mesylate (Gleevec) in the treatment of chronic myelogenous leukaemia. Encouraging data from animal models and primary cells and early Phase I and II studies in other diseases suggest that inhibitors of p38 MAP kinase and IKK2 may prove to be useful novel therapies in the treatment of severe asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis and other inflammatory airway diseases.

Selective Itk inhibitors block T-cell activation and murine lung inflammation

Nonreceptor protein tyrosine kinases including Lck, ZAP-70, and Itk play essential roles in T-cell receptor (TCR) signaling. Gene knockout studies have revealed that mice lacking these individual kinases exhibit various degrees of immunodeficiency; however, highly selective small molecule inhibitors of these kinases as potential immunosuppressive agents have not been identified. Here we discovered two novel compounds, BMS-488516 and BMS-509744, that potently and selectively inhibit Itk kinase activity. The compounds reduce TCR-induced functions including PLCgamma1 tyrosine phosphorylation, calcium mobilization, IL-2 secretion, and T-cell proliferation in vitro in both human and mouse cells. The inhibitors suppress the production of IL-2 induced by anti-TCR antibody administered to mice. BMS-509744 also significantly diminishes lung inflammation in a mouse model of ovalbumin-induced allergy/asthma. Our findings represent the first description of selective inhibitors to probe human Itk function and its associated pathway, and support the hypothesis that Itk is a therapeutic target for immunosuppressive and inflammatory diseases.

Kinase targets and inhibitors for the treatment of airway inflammatory diseases: the next generation of drugs for severe asthma and COPD?

Kinases are believed to play a crucial role in the expression and activation of inflammatory mediators in the airway, in T-cell function, and in airway remodeling. Important pro-inflammatory transcription factors such as activating protein-1 and nuclear factor kappaB, which are activated in airway disease, require kinase activation to switch on inflammatory genes, while other kinases can regulate mRNA half-life. Selective kinase inhibitors have been developed that reduce inflammatory gene expression and some characteristics of disease in animal models. Targeting specific kinases that are overexpressed or overactive in disease should allow for selective treatment of airway inflammatory diseases. Interest in this area has intensified due to the success of the specific Abelson murine leukemia viral oncogene homolog tyrosine kinase inhibitor, imatinib mesylate, in the treatment of chronic myelogenous leukemia. Encouraging data from animal models and primary cells and early phase I and II studies in other diseases suggest that inhibitors of p38 mitogen-activated protein kinase and inhibitor of kappaB kinase-2 may prove to be useful novel therapies in the treatment of severe asthma and chronic obstructive pulmonary disease.

Airway IgG counteracts specific and bystander allergen-triggered pulmonary inflammation by a mechanism dependent on Fc gamma R and IFN-gamma

Besides IgE, the Ab isotype that gives rise to sensitization and allergic asthma, the immune response to common inhalant allergens also includes IgG. Increased serum titers of allergen-specific IgG, induced spontaneously or by allergen vaccination, have been implicated in protection against asthma. To verify the interference of topical IgG with the allergen-triggered eosinophilic airway inflammation that underlies asthma, sensitized mice were treated by intranasal instillation of specific IgG, followed by allergen challenge. This treatment strongly reduced eosinophilic inflammation and goblet cell metaplasia, and increased Th1 reactivity and IFN-gamma levels in bronchoalveolar lavage fluid. In contrast, inflammatory responses were unaffected in IFN-gamma-deficient mice or when applying F(ab')(2). Although dependent on specific allergen-IgG interaction, inflammation triggered by bystander allergens was similarly repressed. Perseverance of inflammation repression, apparent after secondary allergen challenge, and increased allergen capture by alveolar macrophages further characterized the consequences of topical IgG application. These results assign a novel protective function to anti-allergen IgG namely at the local level interference with the inflammatory cascade, resulting in repression of allergic inflammation through an FcgammaR- and IFN-gamma-dependent mechanism. Furthermore, these results provide a basis for topical immunotherapy of asthma by direct delivery of anti-allergen IgG to the airways.

The interplay between the glucocorticoid receptor and nuclear factor-kappaB or activator protein-1: molecular mechanisms for gene repression

The inflammatory response is a highly regulated physiological process that is critically important for homeostasis. A precise physiological control of inflammation allows a timely reaction to invading pathogens or to other insults without causing overreaction liable to damage the host. The cellular signaling pathways identified as important regulators of inflammation are the signal transduction cascades mediated by the nuclear factor-kappaB and the activator protein-1, which can both be modulated by glucocorticoids. Their use in the clinic includes treatment of rheumatoid arthritis, asthma, allograft rejection, and allergic skin diseases. Although glucocorticoids have been widely used since the late 1940s, the molecular mechanisms responsible for their antiinflammatory activity are still under investigation. The various molecular pathways proposed so far are discussed in more detail.

An enteric helminth infection protects against an allergic response to dietary antigen

Although helminths induce a polarized Th2 response they have been shown, in clinical studies, to confer protection against allergies. To elucidate the basis for this paradox, we have examined the influence of an enteric helminth infection on a model of food allergy. Upon Ag challenge, mice fed peanut (PN) extract plus the mucosal adjuvant cholera toxin (CT) produced PN-specific IgE that correlated with systemic anaphylactic symptoms and elevated plasma histamine. PN-specific IgE was not induced in helminth-infected mice fed PN without CT. Moreover, when PN plus CT was fed to helminth-infected mice, both PN-specific IgE and anaphylactic symptoms were greatly diminished. The down-regulation of PN-specific IgE was associated with a marked reduction in the secretion of IL-13 by PN-specific T cells. When helminth-infected PN plus CT-sensitized mice were treated with neutralizing Abs to IL-10, the PN-specific IgE response and anaphylactic symptoms were similar to, or greater than, those seen in mice that receive PN and CT alone. Taken together, these results suggest that helminth-dependent protection against allergic disease involves immunoregulatory mechanisms that block production of allergen-specific IgE.