IL-12-STAT4-IFN-gamma axis is a key downstream pathway in the development of IL-13-mediated asthma phenotypes in a Th2 type asthma model

Interleukin 31 receptor α promotes smooth muscle cell contraction and airway hyperresponsiveness in asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Multiple cytokines, including IFNγ, IL-4, and IL-13 are associated with asthma; however, the mechanisms underlying the effects of these cytokines remain unclear. Here, we report a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31, in mouse models of allergic asthma. In support of this, IFNγ, IL-4, and IL-13 upregulated IL-31RA but not IL-31 in both human and mice primary airway smooth muscle cells (ASMC) isolated from the airways of murine and human lungs. Importantly, the loss of IL-31RA attenuated AHR but had no effect on inflammation and goblet cell hyperplasia in mice challenged with allergens or treated with IL-13 or IFNγ. We show that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression, augmenting calcium levels and myosin light chain phosphorylation in human and murine ASMC. These findings identify a role for IL-31RA in AHR that is distinct from airway inflammation and goblet cell hyperplasia in asthma.

Zi-Su-Zi decoction improves airway hyperresponsiveness in cough-variant asthma rat model through PI3K/AKT1/mTOR, JAK2/STAT3 and HIF-1α/NF-κB signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Cough-variant asthma (CVA) is one of the most common causes of chronic cough. Its pathogenesis is closely related to chronic airway inflammation and airway hyperresponsiveness. CVA belongs to the category of "wind cough" in Traditional Chinese medicine (TCM). Zi-Su-Zi decoction (ZSD) is a Chinese herbal formula that is clinically used for the treatment of cough and asthma, especially CVA. However, the mechanism of action remains unclear.

AIM OF THE STUDY

In this study, we aimed to explore the potential mechanism by which ZSD improves CVA airway hyperresponsiveness.

MATERIALS AND METHODS

The targets of ZSD in CVA were studied using a Network pharmacology. The main chemical components of ZSD were detected and analyzed using ultra-high-pressure liquid chromatography (UHPLC-MS/MS). In animal experiments, the rat model of CVA was established using Ovalbumin (OVA)/Aluminum hydroxide (AL(OH)3) sensitization. Moreover, the experiment also evaluated cough symptoms, percentage of eosinophils (EOS%), pulmonary function tests, histopathological sections, blood cytokine levels, mRNA and protein levels.

RESULTS

The results showed that Network pharmacology suggested 276 targets of ZSD and CVA and found that ZSD treatment with CVA was closely related to the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. UHPLC-MS/MS revealed that ZSD contained 52 main chemical components. Compared with the model group, the cough symptoms of the rats in the different ZSD concentration groups were relieved, the EOS% index was lowered, and body weight was increased. HE staining showed that ZSD reduced airway inflammation, edema and hyperplasia, thereby improving the pathological structure of lung tissue, and the effect of high-dose ZSD was especially significant. Our most important finding was that ZSD blocked the entry of hypoxia-inducible factor-1α (HIF-1α), signal transducer and activator of transcription-3 (STAT3) and nuclear factor kappa-B (NF-κB) into the nucleus by interfering with PI3K/AKT1/mechanistic target of rapamycin (mTOR), and janus kinase 2 (JAK2) signaling factors. Consequently, inhibiting the release of cytokines and immunoglobulin-E, thereby reducing airway hyperresponsiveness (AHR) and partially reverses airway remodeling.

CONCLUSIONS

This study showed that ZSD can improve airway hyperresponsiveness and partially reverse airway remodeling by inhibiting the PI3K/AKT1/mTOR, JAK2/STAT3 and HIF-1α/NF-κB signaling pathways. Therefore, ZSD is an effective prescription for the treatment of CVA.

Interleukin 31 receptor alpha augments muscarinic acetylcholine receptor 3-driven calcium signaling and airway hyperresponsiveness in asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Both Th1 and Th2 cytokines, including IFN-γ, IL-4, and IL-13 have been shown to induce asthma; however, the underlying mechanisms remain unclear. We observed a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31 during allergic asthma. In support of this, IFN-γ and Th2 cytokines, IL-4 and IL-13, upregulated IL-31RA but not IL-31 in airway smooth muscle cells (ASMC). Importantly, the loss of IL-31RA attenuated AHR but had no effects on inflammation and goblet cell hyperplasia in allergic asthma or mice treated with IL-13 or IFN-γ. Mechanistically, we demonstrate that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression and calcium signaling in ASMC. Together, these results identified a novel role for IL-31RA in AHR distinct from airway inflammation and goblet cell hyperplasia in asthma.

Pulmonary IFN-γ Causes Lymphocytic Inflammation and Cough Hypersensitivity by Increasing the Number of IFN-γ-Secreting T Lymphocytes

PURPOSE

Respiratory viral infection increases the number of lung-resident T lymphocytes, which enhance cough sensitivity by producing interferon-γ (IFN-γ). It is poorly understood why IFN-γ-secreting T lymphocytes persist for a long time when the respiratory viruses have been removed.

METHODS

Repeated pulmonary administration of IFN-γ and intraperitoneal injection with different inhibitors were used to study the effects of pulmonary IFN-γ in mice and guinea pigs.

RESULTS

IFN-γ administration caused the increasing of IFN-γ-secreting T lymphocytes in both lung and blood, followed by the elevated physiological level of IFN-γ in the lung, the airway inflammation and the airway epithelial damage. IFN-γ administration also enhanced the cough sensitivity of guinea pigs. IFN-γ activated the STAT1 and extracellular signal-regulated kinase (ERK) pathways in lung tissues, released IFN-γ-inducible protein 10 (IP-10), and resulted in F-actin accumulation in lung-resident lymphocytes. The CXC chemokine receptor 3 (CXCR3) inhibitor potently suppressed all the IFN-γ-induced inflammatory changes. The STAT1 inhibitor mitigated IFN-γ-secreting T lymphocytes infiltration by inhibiting T lymphocytes proliferation. F-actin accumulation and the ERK1/2 pathway contributed to pulmonary IFN-γ-induced augmentation of the airway inflammation and increasing of IFN-γ-secreting T lymphocytes in blood.

CONCLUSIONS

High physiological levels of IFN-γ in the lung may cause pulmonary lymphocytic inflammation and cough hypersensitivity by increasing the number of IFN-γ-secreting T lymphocytes through the IP-10 and CXCR3 pathways.

Effects of Inhalation of STIM-Orai Antagonist SKF 96365 on Ovalbumin-Induced Airway Remodeling in Guinea Pigs

Airway remodeling (AR) consists of wall thickening and hyperreactivity. STIM (stromal interaction molecule) and Orai protein pathways mediate extracellular Ca²⁺ signals involved in AR. This study aims to define the effects on AR of the STIM-Orai antagonist SKF 96365 given by inhalation in three increasing doses in ovalbumin-induced AR. In the control group, the antiasthmatic budesonide and salbutamol were given in the same model. The airway structure was evaluated by histological and immunohistochemistry and reactivity by specific airway resistance, contraction strength of isolated airway smooth muscles, and mucociliary clearance expressed by ciliary beating frequency. The immuno-biochemical markers of chronic inflammation were evaluated by BioPlex and ELISA assays. The AR was mediated by inflammatory cytokines and growth factors. The findings show significant anti-remodeling effects of SKF 96365, which were associated with a decrease in airway hyperreactivity. The anti-remodeling effect of SKF 96365 was mediated via the suppression of IL-4, IL-5, and IL-13 synthesis, and IL-12-INF-γ-TGF-β pathway. The budesonide-related AR suppression had to do with a decrease in proinflammatory cytokines and an increase in the anti-inflammatory IL-10, with negligible influence on growth factors synthesis and mucous glands activity.

Chlorella vulgaris α-L-arabino-α-L-rhamno-α,β-D-galactan structure and mechanisms of its anti-inflammatory and anti-remodelling effects

Microalgal exopolysaccharides (EPSs) are given great attention due to their potential biotechnology applications. Purified C. vulgaris EPS was subjected to compositional and sugar linkage analyses, and partial acid hydrolysis. Hydrolysate separation by gel chromatography afforded oligosaccharide fractions. Both, EPS and oligomers were studied by NMR spectroscopy. Data suggest very complex highly branched α-L-arabino-α-L-rhamno-α,β-D-galactan structure. Backbone repeating unit is formed by →2)-α-L-Rha (1 → 3)-α-L-Rha(1 → sequence, highly branched by long 1,6-linked α-D-Galp side chains, further branched at C2, C3 or C4 by α-L-Araf, α-D-Galf and β-D-Galf residues. α-L-Araf form longer 1,2-linked chains branched at C3, C4 or C5. Galf residues are localized as terminal units predominantly in the β configuration, while α-D-Galp and α-L-Araf may be partially O-methylated. Ex vivo biological assays showed increased interleukin-12 (IL-12) and interferon-gamma (INF-γ) levels corresponding to transforming growth factor beta (TGF-β) decrease in guinea pig model experimental asthma. These facts point to the anti-remodelling effect of Chlorella EPS and suggest its possible application in the treatment of asthma and chronic obstructive pulmonary disorder.

Baicalein, wogonin, and Scutellaria baicalensis ethanol extract alleviate ovalbumin-induced allergic airway inflammation and mast cell-mediated anaphylactic shock by regulation of Th1/Th2 imbalance and histamine release

Asthma is characterized by chronic inflammation, goblet cell hyperplasia, the aberrant production of the Th2 cytokines, and eosinophil infiltration into the lungs. In this study, we examined the effects of baicalein, wogonin, and Scutellaria baicalensis ethanol extract on ovalbumin (OVA)-induced asthma by evaluating Th1/Th2 cytokine levels, histopathologic analysis, and compound 48/80-induced systemic anaphylaxis and mast cell activation, focusing on the histamine release from rat peritoneal mast cells. Baicalein, wogonin, and S. baicalensis ethanol extract also decreased the number of inflammatory cells especially eosinophils and downregulated peribronchial and perivascular inflammation in the lungs of mice challenged by OVA. Baicalein, wogonin, and S. baicalensis ethanol extract significantly reduced the levels of tumor necrosis factor α, interleukin (IL)-1β, IL-4, IL-5 and the production of OVA-specific IgE and IgG1, and upregulated the level of interferon-γ and OVA-specific IgG2a. In addition, oral administration of baicalein, wogonin, and S. baicalensis ethanol extract inhibited compound 48/80-induced systemic anaphylaxis and plasma histamine release in mice. Moreover, baicalein, wogonin, and S. baicalensis ethanol extract suppressed compound 48/80-induced mast cell degranulation and histamine release from rat peritoneal mast cells. Conclusively, baicalein and wogonin as major flavonoids of S. baicalensis may have therapeutic potential for allergic asthma through modulation of Th1/Th2 cytokine imbalance and histamine release from mast cells.

Interleukin-12B gene polymorphisms and bronchial asthma risk: A meta-analysis

OBJECTIVE

This meta-analysis aims to investigate whether interleukin-12B (IL-12B) -1188A/C or the promoter polymorphisms may be a risk factor for asthma.

DATA SOURCES

Web of Science, PubMed, China National Knowledge Infrastructure (CNKI) and Wanfang databases were searched (updated August 20, 2015).

STUDY SELECTIONS

Articles evaluating the association between IL-12B genetic polymorphisms and asthma risk were selected.

RESULTS

13 eligible studies with a total of 5092 subjects were finally included in this meta-analysis. For IL-12B -1188A/C, analysis by ethnicity indicated that there was a markedly reduced risk for asthma in East Asian (CC + AC vs. AA: OR = 0.64, 95% CI = 0.50-0.81, P < 0.001). For IL-12B promoter, analysis by ethnicity indicated there was a markedly increased risk in East Asian (MM vs. WM + WW: OR = 1.57, 95% CI = 1.18-2.10, P = 0.002). Analysis by allergic state revealed the similar results in atopic subgroup.

CONCLUSIONS

IL-12B -1188 C allele may be a protective factor against asthma in East Asian. In addition, promoter MM genotype may be a risk factor for asthma in East Asian and allergic people.

Correction of lung inflammation in a F508del CFTR murine cystic fibrosis model by the sphingosine-1-phosphate lyase inhibitor LX2931

Progressive lung disease with early onset is the main cause of mortality and morbidity in cystic fibrosis patients. Here we report a reduction of sphingosine-1-phosphate (S1P) in the lung of unchallenged Cftr^tm1EUR F508del CFTR mutant mice. This correlates with enhanced infiltration by inducible nitric oxide synthase (iNOS)-expressing granulocytes, B cells, and T cells. Furthermore, the ratio of macrophage-derived dendritic cells (MoDC) to conventional dendritic cells (cDC) is higher in mutant mouse lung, consistent with unprovoked inflammation. Oral application of a S1P lyase inhibitor (LX2931) increases S1P levels in mutant mouse tissues. This normalizes the lung MoDC/cDC ratio and reduces B and T cell counts. Lung granulocytes are enhanced, but iNOS expression is reduced in this population. Although lung LyC6+ monocytes are enhanced by LX2931, they apparently do not differentiate to MoDC and macrophages. After challenge with bacterial toxins (LPS-fMLP) we observe enhanced levels of proinflammatory cytokines TNF-α, KC, IFNγ, and IL-12 and the inducible mucin MUC5AC in mutant mouse lung, evidence of deficient resolution of inflammation. LX2931 does not prevent transient inflammation or goblet cell hyperplasia after challenge, but it reduces MUC5AC and proinflammatory cytokine levels toward normal values. We conclude that lung pathology in homozygous mice expressing murine F508del CFTR, which represents the most frequent mutation in CF patients, is characterized by abnormal behavior of infiltrating myeloid cells and delayed resolution of induced inflammation. This phenotype can be partially corrected by a S1P lyase inhibitor, providing a rationale for therapeutic targeting of the S1P signaling pathway in CF patients.

Therapeutic implication of genetic variants of IL13 and STAT4 in airway remodelling with bronchial asthma

BACKGROUND

Several gene variants identified in bronchial asthmatic patients are associated with a decrease in pulmonary function. The effects of this intervention on pulmonary function have not been fully researched.

OBJECTIVE

We determined the effects of high-dose inhaled corticosteroids (ICSs) on decreased pulmonary function in asthmatic Japanese patients with variants of IL13 and STAT4 during long-term treatments with low to mild doses of ICS.

METHODS

In this study, 411 patients with bronchial asthma who were receiving ICSs and living in Japan were recruited, were genotyped, and underwent pulmonary function tests and fibreoptic examinations. The effects of 2 years of high-dose ICSs administered to asthmatic patients who were homozygous for IL13 AA of rs20541 or STAT4 TT of rs925847 and who progressed to airway remodelling were investigated.

RESULTS

High-dose ICS treatment increased the pulmonary function of patients homozygous for IL13 AA of rs20541 but not of patients homozygous for STAT4 TT of rs925847. The increased concentrations of the mediators IL23, IL11, GMCSF, hyaluronic acid, IL24, and CCL8 in bronchial lavage fluid (BLF) were diminished after high-dose ICS treatment in patients homozygous for IL13 AA of rs20541.

CONCLUSION AND CLINICAL RELEVANCE

IL13 AA of rs20541 and STAT4 TT of rs925847 are potential genomic biomarkers for predicting lower pulmonary function. The administration of high-dose ICSs to asthmatic patients with genetic variants of IL13 AA may inhibit the advancement of airway remodelling. The genetic variants of STAT4 TT did not respond to high-dose ICSs. Therefore, using medications other than ICSs must be considered even during the initial treatment of bronchial asthma. These genetic variants may aid in the realization of personalized and phenotype-specific therapies for bronchial asthma.

A hypothesis-effect of T cell epitope fusion peptide specific immunotherapy on signal transduction

Asthma is a chronic nonspecific inflammatory disease of the airway primarily mediated by different inflammatory cells, including mast cells, eosinophils and T cells. We hereby specially focused on a signal pathway for Janus kinase-signal transducer and activators of transduction (JAK-STATs), which has been the interest of study in asthma since it more likely regulates cellular proliferation and differentiation, and consequently modulates immune system. In our consideration, knowledge on this signal pathway may provide an avenue for rational options in treatment of asthma on control of immune response basis.

Platelet-derived growth factor mediates interleukin-13-induced collagen I production in mouse airway fibroblasts

Interleukin-13 (IL-13) is associated with the production of collagen in airway remodelling of asthma. Yet, the molecular mechanisms underlying IL-13 induction of collagen remain unclear; the aim of this study is to address this issue. IL-13 dose- and time-dependently-induced collagen I production in primary cultured airway fibroblasts; this was accompanied with the STAT6 phosphorylation, and pre-treatment of cells with JAK inhibitor suppressed IL-13- induced collagen I production. Further study indicated that IL-13 stimulated JAK/STAT6-dependent PDGF production and subsequent ERK1/2 MAPK activation in airway fibroblasts, and the presence of either PDGF receptor blocker or MEK inhibitor partially suppressed IL-13-induced collagen I production. Taken together, our study suggests that activation of JAK/STAT6 signal pathway and subsequent PDGF generation and resultant ERK1/2 MAPK activation mediated IL-13-induced collagen I production in airway fibroblasts.

Secreted phosphoprotein 1 is a determinant of lung function development in mice

Secreted phosphoprotein 1 (Spp1) is located within quantitative trait loci associated with lung function that was previously identified by contrasting C3H/HeJ and JF1/Msf mouse strains that have extremely divergent lung function. JF1/Msf mice with diminished lung function had reduced lung SPP1 transcript and protein during the peak stage of alveologenesis (postnatal day [P]14-P28) as compared with C3H/HeJ mice. In addition to a previously identified genetic variant that altered runt-related transcription factor 2 (RUNX2) binding in the Spp1 promoter, we identified another promoter variant in a putative RUNX2 binding site that increased the DNA protein binding. SPP1 induced dose-dependent mouse lung epithelial-15 cell proliferation. Spp1((-/-)) mice have decreased specific total lung capacity/body weight, higher specific compliance, and increased mean airspace chord length (Lm) compared with Spp1((+/+)) mice. Microarray analysis revealed enriched gene ontogeny categories, with numerous genes associated with lung development and/or respiratory disease. Insulin-like growth factor 1, Hedgehog-interacting protein, wingless-related mouse mammary tumor virus integration site 5A, and NOTCH1 transcripts decreased in the lung of P14 Spp1((-/-)) mice as determined by quantitative RT-PCR analysis. SPP1 promotes pneumocyte growth, and mice lacking SPP1 have smaller, more compliant lungs with enlarged airspace (i.e., increased Lm). Microarray analysis suggests a dysregulation of key lung developmental transcripts in gene-targeted Spp1((-/-)) mice, particularly during the peak phase of alveologenesis. In addition to its known roles in lung disease, this study supports SPP1 as a determinant of lung development in mice.

STAT4 deficiency fails to induce lung Th2 or Th17 immunity following primary or secondary respiratory syncytial virus (RSV) challenge but enhances the lung RSV-specific CD8+ T cell immune response to secondary challenge

Immune-mediated lung injury is a hallmark of lower respiratory tract illness caused by respiratory syncytial virus (RSV). STAT4 plays a critical role in CD4+ Th1 lineage differentiation and gamma interferon (IFN-γ) protein expression by CD4+ T cells. As CD4+ Th1 differentiation is associated with negative regulation of CD4+ Th2 and Th17 differentiation, we hypothesized that RSV infection of STAT4-/- mice would result in enhanced lung Th2 and Th17 inflammation and impaired lung Th1 inflammation compared to wild-type (WT) mice. We performed primary and secondary RSV challenges in WT and STAT4-/- mice and used STAT1-/- mice as a positive control for the development of RSV-specific lung Th2 and Th17 inflammation during primary challenge. Primary RSV challenge of STAT4-/- mice resulted in decreased T-bet and IFN-γ expression levels in CD4+ T cells compared to those of WT mice. Lung Th2 and Th17 inflammation did not develop in primary RSV-challenged STAT4-/- mice. Decreased IFN-γ expression by NK cells, CD4+ T cells, and CD8+ T cells was associated with attenuated weight loss and enhanced viral clearance with primary challenge in STAT4-/- mice compared to WT mice. Following secondary challenge, WT and STAT4-/- mice also did not develop lung Th2 or Th17 inflammation. In contrast to primary challenge, secondary RSV challenge of STAT4-/- mice resulted in enhanced weight loss, an increased lung IFN-γ expression level, and an increased lung RSV-specific CD8+ T cell response compared to those of WT mice. These data demonstrate that STAT4 regulates the RSV-specific CD8+ T cell response to secondary infection but does not independently regulate lung Th2 or Th17 immune responses to RSV challenge.

IMPORTANCE

STAT4 is a protein critical for both innate and adaptive immune responses to viral infection. Our results show that STAT4 regulates the immune response to primary and secondary challenge with RSV but does not restrain RSV-induced lung Th2 or Th17 immune responses. These findings suggest that STAT4 expression may influence lung immunity and severity of illness following primary and secondary RSV infections.

Effects of microRNA-21 on the interleukin 12/signal transducer and activator of transcription 4 signaling pathway in asthmatic mice

Objective

To study the effect of microRNA-21 (miRNA-21) on the regulation of the interleukin 12 (IL-12)/signal transducer and activator of transcription 4 (STAT4) pathway in the lung tissue of asthmatic mice.

Material and methods

Forty five male C57BL/6 mice were randomly divided into three groups of 15 mice each: normal control, asthmatic model, and dexamethasone. Our mouse model of allergic asathma was established using OVA sensitization and challenge. Hematoxylin and eosin staining was performed to observe the pathological changes in lung tissue morphology. Both the total cell number and the amount of eosinophils (EOS) in the bronchoalveolar lavage fluid (BALF) were manually counted. The expression of miRNA-21 was detected by real time quantitative PCR. The expression levels of IL-12 and STAT4 in lung tissue were assayed via western blot, and immunohistochemistry was used to observe the distribution of their expression.

Results

The expression levels of miRNA-21 as well as the total number of BALF cells and EOS were significantly higher in the asthmatic model group than in the control or dexamethasone groups, with significantly higher amounts found in the dexamethasone group than in the control group. The expression levels of IL-12 and STAT4 proteins were lower in the asthmatic model group than in the control and dexamethasone groups, with a significantly lower expression of IL-12 and STAT4 in the dexamethasone group than in the control group.

Conclusions

The expression level of miRNA-21 was significantly increased and the expression level of IL-12 and STAT4 proteins was significantly decreased in allergic asthmatic mice compared with normal control mice. These findings suggest a role for miRNA-21 and the IL-12/STAT4 pathway in the development of allergic asthma.

Inhibition of IFN-γ promotes anti-asthma effect of Mycobacterium bovis Bacillus Calmette-Guerin neonatal vaccination: a murine asthma model

OBJECTIVE

The Mycobacterium bovis Bacillus Calmette-Guerin (BCG) neonatal vaccination inhibits allergy-induced pathologic changes. However, the mechanisms underlying this process are unclear. This study aimed to investigate the role of interferon (IFN)-γ and interleukin (IL)-17 in the protective effects of the BCG neonatal vaccination on allergic pulmonary inflammation and airway hyperresponsiveness (AHR).

METHODS

Wild type (WT)-neonate and IL-17 knock out (KO) neonate mice were vaccinated with BCG. A murine asthma model was developed by sensitization and then challenging with ovalbumin (OVA). Recombinant IL-17 or recombinant IFN-γ was delivered to the airway to overexpress IL-17 or IFN-γ. An anti-IFN-γ neutralizing antibody was used to block the effects of IFN-γ.

RESULTS

We found exogenous IL-17 delivered to the airway reversed the anti-asthma effects of the neonatal BCG vaccination. BCG neonatal vaccination further reduced OVA-induced inflammation and AHR in IL-17 KO mice. Inhibition of IFN-γ in BCG neonatal vaccinated OVA-induced asthma model mice led to a further reduction in airway inflammation and AHR. In addition, airway inflammation and AHR were robust following treatment with exogenous IFN-γ. Neutralizing IL-17 was not sufficient to block OVA-induced airway inflammation and AHR. In IL-17 KO mice, airway inflammation and AHR did not occur following treatment with an anti-IFN-γ neutralizing antibody.

CONCLUSIONS

In an OVA-induced murine asthma model, inhibition of IFN-γ enhanced the anti-asthma effects of BCG neonatal vaccination.

Interleukin 13 and the evolution of asthma therapy

This is a concise review on Interleukin (IL)-13 and the evolution of asthma therapy, from discovery of the molecule, the identification of its pathogenic role in animal models of asthma, to the development of clinically successful neutralizing agents. The translational path from basic research to clinical application was not sequential as expected but random with respect to the tools (molecular & cell biology, animal models, human studies) used and to the application of academic versus industry research. The experiences with the development of neutralizing anti-IL-13 reagents emphasize the need for inclusion of a biomarker assay in the clinical trials that both identifies individuals that actually have aberrant expression of the pathway of interest and allows determining whether the target of interest is neutralized.

Prenatal allergen exposures prevent allergen-induced sensitization and airway inflammation in young mice

BACKGROUND

Immune-modulation such as tolerance induction appears to be an upcoming concept to prevent development of atopic diseases. Pregnancy might present a critical period for preventing allergic sensitization of the progeny. We investigated the effect of maternal allergen exposures during pregnancy on allergen-induced sensitization and airway inflammation in the offspring in a murine model.

METHODS

BALB/c mice were exposed to aerosolized ovalbumin (OVA) three times per week from day 7 of pregnancy until delivery (day 0). Offspring were systemically sensitized by six intraperitoneal injections with OVA between postnatal days 21 and 35, prior to airway allergen challenges on days 48, 49, and 50. Analyses were performed on day 52. To examine long-lasting effects of maternal OVA exposures some offspring were sensitized between days 115 and 129; analyses took place on day 147.

RESULTS

Compared to maternal placebo exposures, maternal OVA exposures suppressed OVA-specific IgE serum levels and inhibited development of allergen-induced airway inflammation in the OVA-sensitized offspring on both days 52 and 147. This protective effect was associated with a shift from a predominant Th2 immune response toward a predominant production of the cytokines IFN-γ and IL-10. Further, maternal OVA exposures were associated with development of CD25(+) Foxp3(+) regulatory T cells (T(regs)) in the OVA-sensitized offspring. Depletion of T(regs) or neutralization of IL-10 prior to allergen sensitization re-established OVA-induced sensitization and eosinophilic airway inflammation in the OVA-sensitized offspring.

CONCLUSIONS

In our model, maternal allergen exposures during pregnancy prevented later allergen-mediated sensitization and airway inflammation by allergen-specific tolerance induction in the offspring.

Mast cells play a key role in Th2 cytokine-dependent asthma model through production of adhesion molecules by liberation of TNF-α

Mast cells are well recognized as key cells in allergic reactions, such as asthma and allergic airway diseases. However, the effects of mast cells and TNF-α on T-helper type 2 (Th2) cytokine-dependent asthma are not clearly understood. Therefore, an aim of this study was to investigate the role of mast cells on Th2 cytokine-dependent airway hyperresponsiveness and inflammation. We used genetically mast cell-deficient WBB6F1/J-Kitw/Kitw-v (W/Wv), congenic normal WBB6F1/J-Kit+/Kit+ (+/+), and mast cell-reconstituted W/Wv mouse models of allergic asthma to investigate the role of mast cells in Th2 cytokine-dependent asthma induced by ovalbumin (OVA). And we investigated whether the intratracheal injection of TNF-α directly induce the expression of ICAM-1 and VCAM-1 in W/Wv mice. This study, with OVA-sensitized and OVA-challenged mice, revealed the following typical histopathologic features of allergic diseases: increased inflammatory cells of the airway, airway hyperresponsiveness, and increased levels of TNF-α, intercellular adhesion molecule (ICAM)-1, and vascular cellular adhesion molecule (VCAM)-1. However, the histopathologic features and levels of ICAM-1 and VCAM-1 proteins in W/Wv mice after OVA challenges were significantly inhibited. Moreover, mast cell-reconstituted W/Wv mice showed restoration of histopathologic features and recovery of ICAM-1 and VCAM-1 protein levels that were similar to those found in +/+ mice. Intratracheal administration of TNF-α resulted in increased ICAM-1 and VCAM-1 protein levels in W/Wv mice. These results suggest that mast cells play a key role in a Th2 cytokine-dependent asthma model through production of adhesion molecules, including ICAM-1 and VCAM-1, by liberation of TNF-α.

T(H)17 cells mediate pulmonary collateral priming

BACKGROUND

Our laboratory has shown that inhalational sensitization to new antigens is facilitated through an ongoing T(H)2-polarized inflammation of the lung, a phenomenon we call "collateral priming."

OBJECTIVE

We were interested to analyze whether a T(H)1-polarized pulmonary inflammation also facilitates priming toward new antigens and which cytokine or cytokines are involved.

METHODS

T(H)1-polarized T cells were generated in vitro and transferred into congenic mice. Mice were challenged initially with cognate antigen and an unrelated antigen; consecutively, they received cognate antigen or the secondary antigen. Airway inflammation, antigen-specific IgG2a levels, and airway hyperresponsiveness were assessed to determine the inflammatory phenotype, with antibody blocking studies used to determine cytokine requirements for T(H)1 collateral priming.

RESULTS

Our experiments revealed that ongoing inflammation of the lung induced by the transfer of T(H)1-polarized cells also facilitates priming toward new antigens, which results in lymphocytic inflammation of the lung. Interestingly, blocking studies identified IL-17A as a major contributor to this pathology. Accordingly, we could demonstrate for the first time that T(H)17-polarized cells alone can facilitate priming toward new antigens, inducing lymphocytic airway inflammation and strong airway hyperresponsiveness. Flow cytometric analysis revealed priming of endogenous T cells for IL-17A secretion with a distinct memory/effector phenotype compared to T(H)1 cells, thus presenting an exciting model to further elucidate differentiation of T(H)17 cells.

CONCLUSIONS

We show that airway inflammation mediated by T(H)17 cells facilitates sensitization to new antigens and confers increased airway responsiveness in a murine model of polysensitization, suggesting a mechanism involving IL-17A behind the increased risk for allergic sensitization in polysensitized subjects.