Pathophysiology of asthma: what has our current understanding taught us about new therapeutic approaches?

New phosphodiesterase-4 inhibitors present airways relaxant activity in a guinea pig acute asthma model

Asthma is a disease characterized by chronic inflammation and hyper responsiveness of airways. We aimed to assess the relaxant potential of phosphodiesterase-4 (PDE4) inhibitors N-sulfonilhidrazonic derivatives on non-asthmatic and asthmatic guinea pig trachea. Firstly, guinea pigs were sensitized and challenged with ovalbumin, and then morphological, and contractile changes were evaluated resulting from asthma, followed by evaluation of relaxant effect of derivatives on guinea pig trachea and the cAMP levels measurement by ELISA. It has been evidenced hypertrophy of airway smooth muscle, inflammatory infiltrate, and vascular abnormalities. Moreover, only sensitized tracheal rings were responsive to OVA. Contractile response to histamine, but not to carbachol, was greater in sensitized animals, however the relaxant response to aminophylline and isoprenaline were the same in non-asthmatics and asthmatics. N-sulfonilhidrazonic derivatives presented equipotent relaxant action independent of epithelium, with exception of LASSBio-1850 that presented a low efficacy (< 50%) and LASSBio-1847 with a 4-fold higher potency on asthmatics. LASSBio-1847 relaxant curve was impaired in the presence of propranolol and potentiated by isoprenaline in both groups. Furthermore, relaxation was potentiated 54- and 4-fold by forskolin in non-asthmatics and asthmatics, respectively. Likewise, LASSBio-1847 potentiated relaxant curve of aminophylline 147- and 4-fold in both groups. The PKA inhibitor H-89 impaired the relaxant potency of the derivative. Finally, LASSBio-1847 increased tracheal intracellular cAMP levels similarly to rolipram, selective PDE4 inhibitor, in both animals. LASSBio-1847 showed to be promising to relax guinea pig trachea from non-sensitized and sensitized guinea pigs by activation of β2-adrenergic receptors/AC/cAMP pathway.

Reprogramming of arachidonic acid metabolism using α-terpineol to alleviate asthma: insights from metabolomics

Asthma is a chronic inflammatory disorder in airways with typical pathologic features of airway inflammation and mucus hypersecretion. α-Terpineol is a monocyclic terpene found in many natural plants and foods. It has been reported to possess a wide range of pharmacological activities including anti-inflammatory and expectorant effects. However, the role of α-terpineol in asthma and its potential protective mechanism have not been well elucidated. This study is designed to investigate the pharmacological effect and mechanism of α-terpineol on asthmatic mice using the metabolomics platform. A murine model of asthma was established using ovalbumin (OVA) sensitization and then challenged for one week. The leukocyte count and inflammatory cytokines in the bronchoalveolar lavage fluid (BALF), lung histopathology, inflammatory  infiltrate and mucus secretion were evaluated. An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)-based metabolomics study was performed on lung tissues and serum to explore endogenous small molecule metabolites affected by α-terpineol in asthmatic mice. After α-terpineol treatment, leukocyte count, inflammatory cytokines in the BALF, and peribronchial inflammation infiltration were significantly downregulated. Goblet cell hyperplasia and mucus secretion were attenuated, with the level of Muc5ac in BALF decreased. These results proved the protective effect of α-terpineol against airway inflammation, mucus hypersecretion and Th1/Th2 immune imbalance. To further investigate the underlying mechanisms of α-terpineol in asthma treatment, UPLC-MS/MS-based metabolomics analysis was performed. 26 and 15 identified significant differential metabolites were found in the lung tissues and serum of the control, model and α-terpineol groups, respectively. Based on the above differential metabolites, enrichment analysis showed that arachidonic acid (AA) metabolism was reprogrammed in both mouse lung tissues and serum. 5-Lipoxygenase (5-LOX) and cysteinyl leukotrienes (CysLTs) are the key enzyme and the end product of AA metabolism, respectively. In-depth studies have shown that pretreatment with α-terpineol can alleviate asthma by decreasing the AA level, downregulating the expression of 5-LOX and reducing the accumulation of CysLTs in mouse lung tissues. In summary, this study demonstrates that α-terpineol is a potential agent that can prevent asthma via regulating disordered AA metabolism.

Clinical Subtypes of Neutrophilic Asthma: A Cluster Analysis From Australasian Severe Asthma Network

BACKGROUND

Clinical heterogeneity may exist within asthma subtypes defined by inflammatory markers. However, the heterogeneity of neutrophilic asthma (NA) remains largely unexplored.

OBJECTIVE

To explore potential clusters and the stability of NA.

METHODS

Participants with NA from the Australasian Severe Asthma Network underwent a multidimensional assessment. They were then asked to participate in a 12-month longitudinal cohort study. We explored potential clusters using a hierarchical cluster analysis and validated the differential future risk of asthma exacerbations in the identified clusters. A decision tree analysis was developed to predict cluster assignments. Finally, the stability of prespecified clusters was examined within 1 month.

RESULTS

Three clusters were identified in 149 patients with NA. Cluster 1 (n = 99; 66.4%) was characterized by female-predominant nonsmokers with well-controlled NA, cluster 2 (n = 16; 10.7%) by individuals with comorbid anxiety/depressive symptoms with poorly controlled NA, and cluster 3 by older male smokers with late-onset NA. Cluster 2 had a greater proportion of participants with severe exacerbations (P = .005), hospitalization (P = .010), and unscheduled visits (P = .013) and a higher number of emergency room visits (P = .039) than that of the other two clusters. The decision tree assigned 92.6% of participants correctly. Most participants (87.5%; n = 7) in cluster 2 had a stable NA phenotype, whereas participants of clusters 1 and 3 had variable phenotypes.

CONCLUSIONS

We identified three clinical clusters of NA, in which cluster 2 represents an uncontrolled and stable NA subtype with an elevated risk of exacerbations. These findings have clinical implications for the management of NA.

Current Progress and Future Perspectives on the Use of Bacillus clausii

Bacillus clausii is a probiotic that benefits human health. Its key characteristics include the ability to form spores; the resulting tolerance to heat, acid, and salt ensures safe passage through the human gastrointestinal tract with no loss of cells. Although B. clausii has been widely used for many decades, the beneficial properties of other probiotics, such as Lactobacillus spp. and Bifidobacterium spp., are better disseminated in the literature. In this review, we summarize the physiological, antimicrobial, and immunomodulatory properties of probiotic B. clausii strains. We also describe findings from studies that have investigated B. clausii probiotics from the perspective of quality and safety. We highlight innovative properties based on biochemical investigations of non-probiotic strains of B. clausii, revealing that B. clausii may have further health benefits in other therapeutic areas.

Oxidative Stress Promotes Corticosteroid Insensitivity in Asthma and COPD

Corticosteroid insensitivity is a key characteristic of patients with severe asthma and COPD. These individuals experience greater pulmonary oxidative stress and inflammation, which contribute to diminished lung function and frequent exacerbations despite the often and prolonged use of systemic, high dose corticosteroids. Reactive oxygen and nitrogen species (RONS) promote corticosteroid insensitivity by disrupting glucocorticoid receptor (GR) signaling, leading to the sustained activation of pro-inflammatory pathways in immune and airway structural cells. Studies in asthma and COPD models suggest that corticosteroids need a balanced redox environment to be effective and to reduce airway inflammation. In this review, we discuss how oxidative stress contributes to corticosteroid insensitivity and the importance of optimizing endogenous antioxidant responses to enhance corticosteroid sensitivity. Future studies should aim to identify how antioxidant-based therapies can complement corticosteroids to reduce the need for prolonged high dose regimens in patients with severe asthma and COPD.

Mast Cells in Inflammation and Disease: Recent Progress and Ongoing Concerns

Mast cells have existed long before the development of adaptive immunity, although they have been given different names. Thus, in the marine urochordate Styela plicata, they have been designated as test cells. However, based on their morphological characteristics (including prominent cytoplasmic granules) and mediator content (including heparin, histamine, and neutral proteases), test cells are thought to represent members of the lineage known in vertebrates as mast cells. So this lineage presumably had important functions that preceded the development of antibodies, including IgE. Yet mast cells are best known, in humans, as key sources of mediators responsible for acute allergic reactions, notably including anaphylaxis, a severe and potentially fatal IgE-dependent immediate hypersensitivity reaction to apparently harmless antigens, including many found in foods and medicines. In this review, we briefly describe the origins of tissue mast cells and outline evidence that these cells can have beneficial as well as detrimental functions, both innately and as participants in adaptive immune responses. We also discuss aspects of mast cell heterogeneity and comment on how the plasticity of this lineage may provide insight into its roles in health and disease. Finally, we consider some currently open questions that are yet unresolved.

Bacillus clausii, a Foreshore-Derived Probiotic, Attenuates Allergic Airway Inflammation Through Downregulation of Hypoxia Signaling

Background and Objectives: The immunomodulatory effects and mechanism of probiotics in allergic airway disease are largely unknown. We studied whether <i>Bacillus clausii</i> (BC), a probiotic derived from mudflats, had anti-allergic effects and compared the results with those of <i>Lactobacillus paracasei</i> (LP). We also examined whether the anti-allergic mechanisms of probiotics are associated with hypoxia signaling.Materials and Method: Forty-two BALB/c mice were randomly assigned to six experimental groups: controls, ovalbumin (OVA)-induced mice for inducing asthma, and OVA-induced mice that were orally administered LP or BC, at 1×10⁹ or 5×10⁹ CFU/mL each. We performed differential cell count testing on bronchoalveolar lavage fluid (BALF), lung histopathology, serum totals and OVA-specific IgE and IgG1 assessments, Th2 cytokine titers (IL-4, IL-5) in BALF and pulmonary parenchyma, quantitative PCR for <i>heme oxygenase (HO)-1</i> and <i>Hif-1α</i>, and immunohistochemistry.Results: Compared to the OVA group mice, OVA-sensitized mice treated with LP or BC showed significantly reduced numbers of eosinophils and neutrophils in the BALF (p<0.05). Both probiotics also significantly reduced pulmonary inflammation and eosinophil infiltration. Mice in the LP or BC group had a substantially lower titer of IL-4 and IL-5 in BALF, and decreased IL-4 and IL-5 expression in the lung parenchyma. Real-time PCR and immunohistochemistry showed that both LP and BC could significantly suppress <i>HO-1</i> and <i>Hif-1α</i> expression in asthmatic mice (p<0.05).Conclusion: BC can attenuate murine allergic asthma by regulating HIF-1α signaling, and its anti-allergic effect is comparable to that of LP.

Mediation of Firearm Violence and Preterm Birth by Pregnancy Complications and Health Behaviors: Addressing Structural and Postexposure Confounding

Firearm violence may indirectly affect health among pregnant women living in neighborhoods where it is endemic. We used birth, death, emergency department, and hospitalization data from California from 2007-2011 to estimate the association between living in a neighborhood with high firearm violence and preterm delivery, and assessed whether there was mediation by diagnoses of pregnancy complications and health behaviors during pregnancy. We used an ensemble machine learning algorithm to predict the propensity for neighborhoods to be classified as having a high level of firearm violence. Risk differences for the total effect and stochastic direct and indirect effects were estimated using targeted maximum likelihood. Residence in high-violence neighborhoods was associated with higher prevalence of preterm birth (risk difference (RD) = 0.46, 95% confidence interval (CI): 0.13, 0.80), infections (RD = 1.34, 95% CI: -0.17, 2.86), asthma (RD = 0.76, 95% CI: 0.03, 1.48), and substance use (RD = 0.74, 95% CI: 0.00, 1.47). The largest indirect effects for the association between violence and preterm birth were observed for infection (stochastic indirect effect = 0.04, 95% CI: 0.00, 0.08) and substance use (stochastic indirect effect = 0.04, 95% CI: 0.01, 0.06). Firearm violence was associated with risk of preterm delivery, and this association was partially mediated by infection and substance use.

MALT1 Protease Plays a Dual Role in the Allergic Response by Acting in Both Mast Cells and Endothelial Cells

The signaling protein MALT1 plays a key role in promoting NF-κB activation in Ag-stimulated lymphocytes. In this capacity, MALT1 has two functions, acting as a scaffolding protein and as a substrate-specific protease. MALT1 is also required for NF-κB-dependent induction of proinflammatory cytokines after FcεR1 stimulation in mast cells, implicating a role in allergy. Because MALT1 remains understudied in this context, we sought to investigate how MALT1 proteolytic activity contributes to the overall allergic response. We compared bone marrow-derived mast cells from MALT1 knockout (MALT1^-/-) and MALT1 protease-deficient (MALT^PD/PD) mice to wild-type cells. We found that MALT1^-/- and MALT1^PD/PD mast cells are equally impaired in cytokine production following FcεRI stimulation, indicating that MALT1 scaffolding activity is insufficient to drive the cytokine response and that MALT1 protease activity is essential. In addition to cytokine production, acute mast cell degranulation is a critical component of allergic response. Intriguingly, whereas degranulation is MALT1-independent, MALT1^PD/PD mice are protected from vascular edema induced by either passive cutaneous anaphylaxis or direct challenge with histamine, a major granule component. This suggests a role for MALT1 protease activity in endothelial cells targeted by mast cell-derived vasoactive substances. Indeed, we find that in human endothelial cells, MALT1 protease is activated following histamine treatment and is required for histamine-induced permeability. We thus propose a dual role for MALT1 protease in allergic response, mediating 1) IgE-dependent mast cell cytokine production, and 2) histamine-induced endothelial permeability. This dual role indicates that therapeutic inhibitors of MALT1 protease could work synergistically to control IgE-mediated allergic disease.

Differential expression of CCR2 and CX3CR1 on CD16+ monocyte subsets is associated with asthma severity

Background

Monocytes play an important role in immune and inflammatory diseases and monocyte subsets are predictors of disease in certain conditions. Expression of the chemokine receptors, CCR2 and CX₃CR1 on monocyte subsets relates to their function and can be used in their characterization. Our objective was to determine whether CD14, CD16, CCR2 and CX₃CR1 on monocyte subsets are potential indicators of asthma severity.

Methods

Blood samples were collected from Saudi Arabian patients with asthma and normal healthy individuals. Six-color flow-cytometry phenotypic analysis was used to identify human blood monocyte subsets, based on their expression of CD14 and CD16 following CD45 gating. Expression of CCR2 and CX₃CR1 was analysed on classical (CD14⁺⁺CD16⁻), intermediate (CD14⁺⁺CD16⁺) and non-classical (CD14⁺CD16⁺⁺) subsets and correlated with disease severity.

Results

We demonstrated a significant increase in percentage of total CD45-positive monocytes in the blood of patients with severe asthma, but the proportion of the individual monocyte subsets was not significantly changed when patients with mild, moderate and severe asthma were compared with healthy individuals. CD16 expression (mean fluorescence intensity, MFI) was decreased on intermediate and non-classical subsets in patients with severe asthma compared to healthy controls. CX₃CR1 expression was also lower, with a lower percentage of cells expressing CX₃CR1 in the non-classical CD14⁺CD16⁺⁺ subset in all patients with asthma and this was inversely related to the percentage of cells expressing CCR2.

Conclusions

CCR2 expression on monocytes indicated a tendency toward more phagocytic monocytes in patients with asthma. The differential expression of CD16, CX₃CR1 and CCR2 on monocyte subsets in peripheral blood indicates modulation of the inflammatory response and suggests a role for monocytes in asthma pathogenesis.

Bronchial Epithelial IgA Secretion Is Impaired in Asthma. Role of IL-4/IL-13

RATIONALE

Asthma is associated with increased lung IgE production, but whether the secretory IgA system is affected in this disease remains unknown.

OBJECTIVES

We explored mucosal IgA transport in human asthma and its potential regulation by T-helper cell type 2 inflammation.

METHODS

Bronchial biopsies from asthma and control subjects were assayed for bronchial epithelial polymeric immunoglobulin receptor (pIgR) expression and correlated to T-helper cell type 2 biomarkers. Bronchial epithelium reconstituted in vitro from these subjects, on culture in air-liquid interface, was assayed for pIgR expression and regulation by IL-4/IL-13.

MEASUREMENTS AND MAIN RESULTS

Downregulation of pIgR protein was observed in the bronchial epithelium from patients with asthma (P = 0.0002 vs. control subjects). This epithelial defect was not observed ex vivo in the cultured epithelium from patients with asthma. Exogenous IL-13 and IL-4 could inhibit pIgR expression and IgA transcytosis. Mechanistic experiments showed that autocrine transforming growth factor-β mediates the IL-4/IL-13 effect on the pIgR, with a partial contribution of upregulated transforming growth factor-α/epidermal growth factor receptor.

CONCLUSIONS

This study shows impaired bronchial epithelial pIgR expression in asthma, presumably affecting secretory IgA-mediated frontline defense as a result of type 2 immune activation of the transforming growth factor pathway.

Cohort profile: the West Sweden Asthma Study (WSAS): a multidisciplinary population-based longitudinal study of asthma, allergy and respiratory conditions in adults

PURPOSE

The West Sweden Asthma Study (WSAS) is a population-representative longitudinal study established to: (1) generate data on prevalence trends, incidence and remission of asthma, allergy and respiratory conditions, (2) elucidate on the risk and prognostic factors associated with these diseases, (3) characterise clinically relevant phenotypes of these diseases and (4) catalyse relevant mechanistic, genomic, genetic and translational investigations.

PARTICIPANTS

WSAS comprised of randomly selected individuals aged 16 to 75 years who are followed up longitudinally. The first stage involved a questionnaire survey (>42 000 participants) and was undertaken in 2008 and 2016. A random sample (about 8000) of participants in the initial survey undergoes extensive clinical investigations every 8 to 10 years (first investigations in 2009 to 2012, second wave currently ongoing). Measurements undertaken at the clinical investigations involve structured interviews, self-completed questionnaire on personality traits, physical measurements and extensive biological samples.

FINDINGS TO DATE

Some of our key findings have shown a 54% increase in the use of asthma medications between the 1990s and 2000s, primarily driven by a five-fold increase in the use of inhaled corticosteroids. About 36% of asthmatics expressed at least one sign of severe asthma indicator, with differential lung performance, inflammation and allergic sensitisation among asthmatics with different signs of severe asthma. Multi-symptom asthmatics were at greater risk of having indicators of severe asthma. In all adults, being raised on a farm was associated with a decreased risk of allergic sensitisation, rhinitis and eczema, but not asthma. However, among adolescents (ie, those 16 to 20 years of age), being raised on a farm decreased the risk of asthma. Personality traits were associated with both beliefs of asthma medication and adherence to treatment.

FUTURE PLANS

Follow-up of the cohort is being undertaken every 8 to 10 years. The repeated clinical examinations will take place in 2019 to 2022. The cohort data are currently being linked to routine Swedish healthcare registers for a continuous follow-up. Mechanistic, genomic, genetic and translational investigations are ongoing.

Role of innate lymphoid cells in allergic diseases

Background: Over the past decade, there has been increasing interest and research into understanding the type 2 immune responses by the epithelium-derived cytokines interleukin (IL) 33, IL-25, and thymic stromal lymphopoietin. Innate lymphoid cells (ILC) are a unique family of effector immune cells that functionally resemble T cells but lack clonal distributed antigen receptors. Group 2 ILCs, ILC2s, are known for their capability to secrete proallergic cytokines, including IL-5 and IL-13. ILC2s are enriched at mucosal barriers in lung, gut, and skin, and their activation has been associated with a variety of allergic disorders. Objective: To study the role of ILC2 in different allergic disorders, including allergic rhinitis, asthma, atopic dermatitis, and food allergies. Methods: A MEDLINE search was performed for articles that reported on ILC2 in allergic disorders, including allergic rhinitis, asthma, atopic dermatitis, and food allergies. Results: A review of the literature revealed an important role of ILC2 in various allergic disorders. Conclusion: Identification of ILC2s in patients with allergic rhinitis, asthma, and atopic dermatitis indicates that these cells may represent a new therapeutic target. In this review, we discussed the current understanding of ILC2 biology and its function and regulation in various allergic diseases.

Interleukin-Mediated Pendrin Transcriptional Regulation in Airway and Esophageal Epithelia

Pendrin (SLC26A4), a Cl⁻/anion exchanger, is expressed at high levels in kidney, thyroid, and inner ear epithelia, where it has an essential role in bicarbonate secretion/chloride reabsorption, iodide accumulation, and endolymph ion balance, respectively. Pendrin is expressed at lower levels in other tissues, such as airways and esophageal epithelia, where it is transcriptionally regulated by the inflammatory cytokines interleukin (IL)-4 and IL-13 through a signal transducer and activator of transcription 6 (STAT6)-mediated pathway. In the airway epithelium, increased pendrin expression during inflammatory diseases leads to imbalances in airway surface liquid thickness and mucin release, while, in the esophageal epithelium, dysregulated pendrin expression is supposed to impact the intracellular pH regulation system. In this review, we discuss some of the recent findings on interleukin-mediated transcriptional regulation of pendrin and how this dysregulation impacts airway and esophagus epithelial homeostasis during inflammatory diseases.

The regulatory roles of glycosphingolipid-enriched lipid rafts in immune systems

Lipid rafts formed by glycosphingolipids (GSLs) on cellular membranes play important roles in innate and adaptive immunity. Lactosylceramide (LacCer) forms lipid rafts on plasma and granular membranes of human neutrophils. These LacCer-enriched lipid rafts bind directly to pathogenic components, such as pathogenic fungi-derived β-glucan and Mycobacteria-derived lipoarabinomannan via carbohydrate-carbohydrate interactions, and mediate innate immune responses to these pathogens. In contrast, a-series and o-series gangliosides form distinct rafts on CD4⁺ and CD8⁺ T cell subsets, respectively, contributing to the respective functions of these cells and stimulating adaptive immune responses through T cell receptors. These findings suggest that gangliosides play indispensable roles in T cell selection and activation. This Review introduces the involvement of GSL-enriched lipid rafts in innate and adaptive immunity.

Childhood asthma clusters reveal neutrophil-predominant phenotype with distinct gene expression

BACKGROUND

Childhood asthma comprises different phenotypes with complex pathophysiology. Different asthma phenotypes evoke various clinical symptoms and vary in their responses to treatments.

METHODS

We applied k-means clustering algorithm of twelve objective laboratory tests among 351 asthmatic children enrolled in the Taiwanese Consortium of Childhood Asthma Study (TCCAS). We constructed gene expression profiles of peripheral blood mononuclear cells (PBMC) from children with different asthma phenotypes.

RESULTS

Five distinct phenotypes of childhood asthma were identified and can be characterized by either eosinophil-predominant or neutrophil-predominant inflammatory characteristics. In the gene expression profile analysis, significant differences were noted for neutrophil-predominant asthma, compared with samples from all the other asthma phenotypes. The vast majority of the differentially expressed genes in neutrophil-predominant asthma was associated with corticosteroid response. From an independent inhaled corticosteroid (ICS) response cohort, we also found neutrophils could be activated in this severe asthma phenotype and neutrophil-predominant asthma may be associated with corticosteroid nonresponsiveness.

CONCLUSION

Phenotype clustering of childhood asthma can be helpful to identify clinically relevant patients and reveal different inflammatory characteristics in asthmatic children. Neutrophil-predominant asthma is the most severe asthma phenotype with poor corticosteroid response. Gene expression profile of different asthma phenotypes not only improve our knowledge of childhood asthma, but also can guide asthma precision medicine.

Targeting matrix metalloproteinase-13 in bronchial epithelial repair

BACKGROUND

Viral infection of the bronchial epithelium disrupts the barrier properties of the epithelium in healthy individuals and those with lung disease. Repair of the bronchial epithelium is dependent of the formation of a provisional fibrin matrix and migration of epithelial cells to cover denuded areas, followed by proliferation and differentiation.

OBJECTIVE

The objective was to test the hypothesis that poly I:C, a model of viral infection, limits epithelial repair through the stimulated release of matrix metalloproteinase-13 (MMP-13).

METHODS

Confluent layers of cultured normal human primary bronchial epithelial cells (NHBE) and SV-40 virus-transformed 16HBE14o- bronchial epithelial cells were mechanically wounded, and video microscopy used to measure the rate of wound closure over 2 hours, in the absence and presence of poly I:C (1-20 μg/mL). MMP-13, tissue factor and endothelin release were measured by ELISA. The effect of inhibitors of MMP-13 activity and expression and a nonspecific endothelin receptor antagonist, bosentan, on the rate of epithelial repair was investigated.

RESULTS

Poly I:C limited the rate of epithelial repair, and NHBE were significantly more sensitive to poly I:C effects than 16HBE14o- cells. NHBE, but not 16HBE14o-, released MMP-13 in response to poly I:C. Inhibitors of MMP-13 activity (WAY 170523) and expression (dimethyl fumarate) significantly enhanced the rate of repair. Bosentan enhanced the rate of bronchial epithelial repair by a mechanism that was independent of MMP-13.

CONCLUSIONS AND CLINICAL RELEVANCE

Bronchial epithelial repair is limited by endothelin and by MMP-13, a protease that degrades coagulation factors, such as fibrinogen, and matrix proteins essential for epithelial repair. Further studies with primary cells from patients are needed to confirm whether repurposing bosentan and inhibitors of MMP-13 expression or activity, for inhalation may be a useful therapeutic strategy in diseases where repeated cycles of epithelial injury and repair occur, such as asthma and COPD.

Asthma predictive index in relation to respiratory mechanics by impulse oscillometry in recurrent wheezers

BACKGROUND

The identification of children who will have persistent asthma has become a focus of recent research. The aim of this study was to assess whether impulse oscillometry (IOS) has a diagnostic value to predict modified API (asthma predictive index) in pre-schoolers with recurrent wheezing.

METHODS

Pre-school children aged 3-6 years with recurrent wheezing were enrolled. The study population was divided into two groups based on mAPI criteria. Lung function was assessed by IOS.

RESULTS

115 children were assessed; 75 (65.2%) of them were male. The median age was 39 months (min: 36, max: 68 months). 64 (55.6%) of the children were mAPI positive. The R5-R20% levels of children with positive mAPI were significantly higher compared to negative mAPI. Also, R5-R20% levels of children with parental asthma and R20% pred and resonant frequency (Fres) levels of children with inhalant sensitization were higher than those without. No significant differences were found in IOS indices between groups based on the presence of atopic dermatitis, food sensitization, eosinophilia, inhaled corticosteroid usage or wheezing without colds. R5-R20% and total IgE values were found to be significantly related to positive mAPI (aOR: 1.40, p=0.022 and aOR: 1.02, p=0.001, respectively). In the ROC analysis, R5-R20% levels >14.4 had a sensitivity of 75% and specificity of 53% for predicting a positive mAPI (p=0.003).

CONCLUSION

IOS may help clinicians to identify the pre-school wheezers with a high risk of asthma.

Biology of GM3 Ganglioside

Since the successful molecular cloning in 1998 of GM3 synthase (GM3S, ST3GAL5), the enzyme responsible for initiating biosynthesis of all complex gangliosides, the efforts of our research group have been focused on clarifying the physiological and pathological implications of gangliosides, particularly GM3. We have identified isoforms of GM3S proteins having distinctive lengths of N-terminal cytoplasmic tails, and found that these cytoplasmic tails define subcellular localization, stability, and in vivo activity of GM3S isoforms. Our studies of the molecular pathogenesis of type 2 diabetes, focused on interaction between insulin receptor and GM3 in membrane microdomains, led to a novel concept: type 2 diabetes and certain other lifestyle-related diseases are membrane microdomain disorders resulting from aberrant expression of gangliosides. This concept has enhanced our understanding of the pathophysiological roles of GM3 and related gangliosides in various diseases involving chronic inflammation, such as insulin resistance, leptin resistance, and T-cell function and immune disorders (e.g., allergic asthma). We also demonstrated an essential role of GM3 in murine and human auditory systems; a common pathological feature of GM3S deficiency is deafness. This is the first direct link reported between gangliosides and auditory functions.

Oxidative stress serves as a key checkpoint for IL-33 release by airway epithelium

BACKGROUND

Interleukin (IL)-33 is implicated in the pathophysiology of asthma and allergic diseases. However, our knowledge is limited regarding how IL-33 release is controlled. The transcription factor nuclear factor-erythroid-2-related factor 2 (Nrf2) plays a key role in antioxidant response regulation.

OBJECTIVE

The goal of this project was to investigate the role of cellular oxidative stress in controlling IL-33 release in airway epithelium.

METHODS

Complementary approaches were used that included human bronchial epithelial cells and mouse models of airway type-2 immunity that were exposed to fungus Alternaria extract. The clinically available Nrf2 activator 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid methyl ester (CDDO-Me) was used to evaluate the role of Nrf2-induced antioxidant molecules.

RESULTS

Human bronchial epithelial cells produced reactive oxygen species (ROS) when they were exposed to Alternaria extract. ROS scavengers, such as glutathione (GSH) and N-acetyl cysteine, prevented extracellular secretion of ATP and increases in intracellular calcium concentrations that precede IL-33 release. Administration of CDDO-Me to mice enhanced expression of a number of antioxidant molecules in the lungs and elevated lung levels of endogenous GSH. Importantly, CDDO-Me treatment reduced allergen-induced ATP secretion and IL-33 release by airway epithelial cells in vitro and protected mice from IL-33 release and asthma-like pathological changes in the lungs.

CONCLUSIONS

The balance between oxidative stress and antioxidant responses plays a key role in controlling IL-33 release in airway epithelium. The therapeutic potential of Nrf2 activators needs to be considered for asthma and allergic airway diseases.

Omalizumab in children with uncontrolled allergic asthma: Review of clinical trial and real-world experience

Asthma is one of the most common chronic diseases of childhood. Allergen sensitization and high frequencies of comorbid allergic diseases are characteristic of severe asthma in children. Omalizumab, an anti-IgE mAb, is the first targeted biologic therapeutic approved for the treatment of moderate-to-severe persistent allergic asthma (AA) that remains uncontrolled despite high-dose inhaled corticosteroids plus other controller medications. Since its initial licensing for use in adults and adolescents 12 years of age and older, the clinical efficacy, safety, and tolerability of omalizumab have been demonstrated in several published clinical trials in children aged 6 to less than 12 years with moderate-to-severe AA. These studies supported the approval of the pediatric indication (use in children aged ≥6 years) by the European Medicines Agency in 2009 and the US Food and Drug Administration in 2016. After this most recent change in licensing, we review the outcomes from clinical trials in children with persistent AA receiving omalizumab therapy and observational studies from the past 7 years of clinical experience in Europe. Data sources were identified by using PubMed in 2016. Guidelines and management recommendations and materials from the recent US Food and Drug Administration's Pediatric Advisory Committee meeting are also reviewed.

The Unresolved Role of Interferon-λ in Asthma Bronchiale

Asthma bronchiale is a disease of the airways with increasing incidence, that often begins during infancy. So far, therapeutic options are mainly symptomatic and thus there is an increasing need for better treatment and/or prevention strategies. Human rhinoviruses (HRVs) are a major cause of asthma exacerbations and might cause acute wheezing associated with local production of pro-inflammatory mediators resulting in neutrophilic inflammatory response. Viral infections induce a characteristic activation of immune response, e.g., TLR3, 4, 7, 8, 9 in the endosome and their downstream targets, especially MyD88. Moreover, other cytoplasmic pattern recognition molecules (PRMs) like RIG1 and MDA5 play important roles in the activation of interferons (IFNs) of all types. Depending on the stimulation of the different PRMs, the levels of the IFNs induced might differ. Recent studies focused on Type I IFNs in samples from control and asthma patients. However, the administration of type I IFN-α was accompanied by side-effects, thus this possible therapy was abandoned. Type III IFN-λ acts more specifically, as fewer cells express the IFN-λ receptor chain 1. In addition, it has been shown that asthmatic mice treated with recombinant or adenoviral expressed IFN-λ2 (IL–28A) showed an amelioration of symptoms, indicating that treatment with IFN-λ might be beneficial for asthmatic patients.

LAT is essential for the mast cell stabilising effect of tHGA in IgE-mediated mast cell activation

Mast cells play a central role in the pathogenesis of allergic reaction. Activation of mast cells by antigens is strictly dependent on the influx of extracellular calcium that involves a complex interaction between signalling molecules located within the cells. We have previously reported that tHGA, an active compound originally isolated from a local shrub known as Melicope ptelefolia, prevented IgE-mediated mast cell activation and passive systemic anaphylaxis by suppressing the release of interleukin-4 (IL-4) and tumour necrosis factor (TNF)-α from activated rat basophilic leukaemia (RBL)-2H3 cells. However, the mechanism of action (MOA) as well as the molecular target underlying the mast cell stabilising effect of tHGA has not been previously investigated. In this study, DNP-IgE-sensitised RBL-2H3 cells were pre-treated with tHGA before challenged with DNP-BSA. To dissect the MOA of tHGA in IgE-mediated mast cell activation, the effect of tHGA on the transcription of IL-4 and TNF-α mRNA was determined using Real Time-Polymerase Chain Reaction (qPCR) followed by Calcium Influx Assay to confirm the involvement of calcium in the activation of mast cells. The protein lysates were analysed by using Western Blot to determine the effect of tHGA on various important signalling molecules in the LAT-PLCγ-MAPK and PI3K-NFκB pathways. In order to identify the molecular target of tHGA in IgE-mediated mast cell activation, the LAT and LAT2 genes in RBL-2H3 cells were knocked-down by using RNA interference to establish a LAT/LAT2 competition model. The results showed that tHGA inhibited the transcription of IL-4 and TNF-α as a result of the suppression of calcium influx in activated RBL-2H3 cells. The results from Western Blot revealed that tHGA primarily inhibited the LAT-PLCγ-MAPK pathway with partial inhibition on the PI3K-p65 pathway without affecting Syk. The results from RNAi further demonstrated that tHGA failed to inhibit the release of mediators associated with mast cell degranulation under the LAT/LAT2 competition model in the absence of LAT. Collectively, this study concluded that the molecular target of tHGA could be LAT and may provide a basis for the development of a mast cell stabiliser which targets LAT.

IL-4 and serum amyloid P inversely regulate fibrocyte differentiation by targeting store-operated Ca2+ channels

BACKGROUND

Circulating fibrocytes (CFs) have been shown to participate in subepithelial fibrosis of asthma with chronic airflow limitation by acting as an important source of fibroblasts deposited beneath airway epithelia. Serum amyloid P (SAP) is an innate inhibitor of fibrocytes differentiation. Store-operated Ca²⁺ entry (SOCE) is the major Ca²⁺ influx of non-excitable cells. In this study, the role of SOCE in the regulation of fibrocytes differentiation and the effects of Th2 cytokine IL-4 and SAP on SOCE of fibrocytes were investigated.

METHODS

Peripheral blood mononuclear cells or monocytes were cultured in serum-free medium for 7days to differentiate into fibrocytes; the expression of SOC channels was determined with PCR, SOCE was measured with Ca²⁺ fluorescence imaging.

RESULTS

IL-4 significantly promoted monocyte derived fibrocytes differentiation in vitro. It also increased both SOCE which was induced by thapsigargin or UTP and molecules STIM1 and Orai1 which were related to expression of SOC channels in fibrocytes. Fibrocytes differentiation induced by IL-4 and SOC channels activity could be inhibited by SOC channel blocker SKF-96365. As expected, SAP significantly inhibited IL-4-induced differentiation of fibrocytes, the activity of SOCE and the expression of STIM1 and Orai1 in IL-4-treated fibrocytes.

CONCLUSION

IL-4 and SAP reversely regulates cultured fibrocytes differentiation in vitro by respectively promoting or inhibiting the expression and activity of SOC channels in fibrocytes.

Severe Asthma in Children

PURPOSE OF REVIEW

The aim of this study is to characterize, diagnose, evaluate, and treat severe childhood asthma.

RECENT FINDINGS

Understanding the occurrence of the physiologic and clinical presentations of childhood severe asthma, the treatment and response may be predicted by biomarkers, but the patient's response is highly variable. The onset of severe asthma occurs early and is primarily predicted by severity of viral infection and coexistence of the atopic state.

Fungal immunomodulatory protein-fve could modulate airway remodel through by affect IL17 cytokine

BACKGROUND

Asthma is one of the most common allergic diseases. Our previous studies have reported that FIP-fve in acute allergic mouse model can reduce inflammation, improve the balance of the Th1/Th2 system. However, the effects of reducing airway remodeling on FIP-fve is still unknown.

OBJECTIVE

We hypothesized that orally administrated FIP-fve should be able to reduce airway remodeling in chronic allergic models.

METHODS

The chronic asthma animal model was established with 6-8 weeks female Balb/c mice. After intranasal challenges with OVA, the airway inflammation and AHR were determined by a BUXCO system. BALF was analyzed with Liu's stain and ELISA assay. Lung histopathologic changes and Collagen deposition were assayed with H&E, Masson's trichrome and IHC stain.

RESULTS

FIP-fve significantly decreased the number of infiltrating inflammatory cells and Th2 cytokines and increased Th1 cytokines in BALF and serum compared with the OVA sensitized mice. FIP-fve had a better effect than corticosteroid could reduce infiltrating cells in lung especially neutrophils and eosinophils. We also found that the oral FIP-fve group suppressed IL-17 and enhanced IL-22 in the serum and BALF. In addition, oral FIP-fve decreased MMP9 expression, collagen expression and airway remodeling in lung tissues.

CONCLUSION

FIP-fve had anti-inflammatory effects on OVA-induced airway inflammation and an effect to inhibited Th17 cells to reduced airway remodeling and collagen expression. Moreover, FIP-fve might be a potential alternative therapy for allergic airway diseases.

Airway tone dysfunction among pre-schoolers with positive asthma predictive index: A case-control study

OBJECTIVE

To measure lung function by impulse oscillometry (IOS) and spirometry in recurrent wheezer pre-schoolers according to their asthma predictive index (API) condition.

METHODS

We performed a case-control study enrolling all pre-schoolers with recurrent wheezing episodes (>3 episodes confirmed by physician) who presented at a paediatric pulmonology clinic. The population was divided according to stringent API criteria into positive or negative.

RESULTS

In the nine-month period, 109 pre-schoolers were enrolled. After excluding one patient (due to lung function technique problems) 108 pre-schoolers (56 males, age range from 24 to 72 months) completed the study; 50 belong to positive API and 58 to negative API group. There were no differences in demographics between groups. More use of ICS was found in those with positive API than with negative API (62% vs. 12%, respectively, p=0.001). No differences in basal lung function and post-bronchodilator response to salbutamol (by IOS or spirometry) were found between positive and negative API pre-schoolers. However, those positive API pre-schoolers with ICS had significantly higher central basal airway resistance (RA at 20Hz) and higher post-BD response (% change in FEF_25-75 and in FEV_0.5) than those positive API without ICS.

CONCLUSION

Recurrent wheezer pre-schoolers with positive API and ICS used may have airway dysfunction. More studies are needed to confirm this finding.

Corticosteroids inhibit anti-IgE activities of specialized proresolving mediators on B cells from asthma patients

Specialized proresolving mediators (SPMs) promote the resolution of inflammation and exert beneficial effects in animal models of chronic inflammatory diseases, including asthma. Previously, we have shown that certain SPMs reduce IgE production in B cells from healthy individuals, which has a critical role in allergic asthma. Here, we investigated the effects of SPMs on B cell IgE production in asthma patients. Peripheral blood mononuclear cells from asthma patients were treated with 17-HDHA or RvD1, and IgE levels were measured. RvD1 and 17-HDHA dampened IgE production in B cells from most asthma patients, whereas B cells from a subset of patients taking oral steroids were refractory to SPM treatment. Molecular mechanisms underlying the interaction between corticosteroids and SPMs were investigated by treating B cells from nonasthmatic donors with corticosteroids in vitro. Corticosteroids blocked the inhibitory effects of 17-HDHA and RvD1 on B cell IgE production by abolishing the suppressive activity of these mediators on IgE class switching. Corticosteroids decreased the expression of transcriptional repressor Bcl-6 as well as its suppressive activity on epsilon germline transcription. We conclude that 17-HDHA and RvD1 can reduce IgE production in asthma patients not taking high doses of steroids but that corticosteroids interfere with the ability of B cells to respond to proresolving mediators.

Low-Molecular-Weight Heparin-Coated and Montelukast-Filled Inhalable Particles: A Dual-Drug Delivery System for Combination Therapy in Asthma

Montelukast, a cysteinyl leukotriene type 1 receptor antagonist, exhibits secondary anti-inflammatory properties when used at higher concentrations. Low-molecular-weight heparin (LMWH) evokes pronounced anti-inflammatory effects by interrupting leukocyte adhesion and migration. We hypothesized that inhalable particles containing montelukast plus LMWH release both drugs in a sustained fashion and protect the lungs against allergen-induced inflammation. Large porous particles of montelukast and LMWH were prepared using a double-emulsion-solvent-evaporation method. Montelukast was first encapsulated in copolymer-based particles using polyethylenimine as a porosigen; the resulting particles were then coated with LMWH. The particles were evaluated for physicochemical properties, respirability, and release profiles. The anti-inflammatory effect of the optimized formulation was studied in ovalbumin-sensitized asthmatic Sprague Dawley rats. The optimized large porous particles had a diameter of 10.3 ± 0.7 μm, exhibited numerous surface indentations and pores, showed acceptable drug entrapment efficiency (66.8% ± 0.4% for montelukast; 91.7% ± 0.8% adsorption efficiency for LMWH), demonstrated biphasic release patterns, and escaped the uptake by the rat alveolar macrophages. The number of infiltrating inflammatory cells in asthmatic rat lungs, treated with dual-drug particles, was >74% fewer than in untreated asthmatic rat lungs. Similarly, the airway walls of asthmatic animals treated with dual-drug particles were 3-fold thinner than those of untreated asthmatic animals (p < 0.001). The optimized formulation protects lungs against methacholine-induced airway hyper-reactivity. Overall, this study demonstrates the feasibility of loading 2 drugs, montelukast and LMWH, into an inhalable particulate system and establishes that this novel combination therapy produces sustained drug release and elicits a robust anti-inflammatory response in the lungs.

Prostaglandin D2 receptor antagonists in early development as potential therapeutic options for asthma

INTRODUCTION

Asthma is a chronic inflammatory disease characterized by bronchial hyper-reactivity. Although many currently available treatment regimens are effective, poor symptom control and refractory severe disease still represent major unmet needs. In the last years, numerous molecular therapeutic targets that interfere with the innate inflammatory response in asthma have been identified. Promising preliminary results concern the signaling cascade promoted by prostaglandin D2 (PGD2) and its receptor antagonists.

AREAS COVERED

The aim of this review is to provide the most recent clinical and preclinical data on the efficacy and safety of newly developed compounds for the treatment of allergic asthma. The authors will present an overview of the pathogenetic molecular mechanisms sustaining the chronic inflammatory response in asthma; the focus will be then directed on the mediators of the PGD2 pathway, the chemoattractant receptor-homologous molecule expressed on TH2 cells, and their latest antagonists developed.

EXPERT OPINION

Bronchodilators and corticosteroids are not sufficient to achieve a satisfactory management of all asthmatic patients; the development of new specific treatments appears therefore essential. The good results in terms of cellular, functional and clinical outcomes, together with an acceptable safety of the CRTh2 antagonists represent a promising start for a tailored management of allergic asthma.

Regulation of eosinophilia and allergic airway inflammation by the glycan-binding protein galectin-1

Galectin-1 (Gal-1), a glycan-binding protein with broad antiinflammatory activities, functions as a proresolving mediator in autoimmune and chronic inflammatory disorders. However, its role in allergic airway inflammation has not yet been elucidated. We evaluated the effects of Gal-1 on eosinophil function and its role in a mouse model of allergic asthma. Allergen exposure resulted in airway recruitment of Gal-1-expressing inflammatory cells, including eosinophils, as well as increased Gal-1 in extracellular spaces in the lungs. In vitro, extracellular Gal-1 exerted divergent effects on eosinophils that were N-glycan- and dose-dependent. At concentrations ≤0.25 µM, Gal-1 increased eosinophil adhesion to vascular cell adhesion molecule-1, caused redistribution of integrin CD49d to the periphery and cell clustering, but inhibited ERK(1/2) activation and eotaxin-1-induced migration. Exposure to concentrations ≥1 µM resulted in ERK(1/2)-dependent apoptosis and disruption of the F-actin cytoskeleton. At lower concentrations, Gal-1 did not alter expression of adhesion molecules (CD49d, CD18, CD11a, CD11b, L-selectin) or of the chemokine receptor CCR3, but decreased CD49d and CCR3 was observed in eosinophils treated with higher concentrations of this lectin. In vivo, allergen-challenged Gal-1-deficient mice exhibited increased recruitment of eosinophils and CD3(+) T lymphocytes in the airways as well as elevated peripheral blood and bone marrow eosinophils relative to corresponding WT mice. Further, these mice had an increased propensity to develop airway hyperresponsiveness and displayed significantly elevated levels of TNF-α in lung tissue. This study suggests that Gal-1 can limit eosinophil recruitment to allergic airways and suppresses airway inflammation by inhibiting cell migration and promoting eosinophil apoptosis.

Effect of tranilast in comparison with beclomethasone in chronic murine model of asthma

AIM OF THE STUDY

The current investigation was taken to scrutinize the action of tranilast on the airway remodeling in chronic asthma in mice.

MATERIALS AND METHODS

Intraperitoneal injection of ovalbumin was applied to mice for sensitization and subsequent inhalation of 1% ovalbumin three times week for 10 weeks for challenge. Beclomethasone or tranilast were given daily for the 10 week challenge period. At the end of the study, lung weight index, total collagen content, bronchoalveolar lavage level of total and differential cell counts, interleukin-13, in addition to lung tissue nitrate/nitrite and transforming growth beta-1 were measured. Also, histological analysis was done.

RESULTS

Asthmatic mice demonstrated apparent fibrotic changes. Significant airway fibrosis was demonstrated by hyperplasia of goblet cells and thickening of airway epithelium, increased content of lung collagen, lung and bronchoalveolar lavage of transforming growth factor beta-1 and interleukin-13 mutually accompanied by reduction in nitrate/nitrite generation.

CONCLUSIONS

Beclomethasone influence on airway remodeling was mediated mainly via suppression of eosinophilic recruitment into the airways and reduction of interleukin-13 cytokine levels. Whereas, tranilast effects on airway remodeling was found to be mainly mediated via its inhibitory effect on transforming growth beta-1. Both beclomethasone and tranilast influence airway remodeling by different degrees and mechanisms.

Claudin-18 deficiency is associated with airway epithelial barrier dysfunction and asthma

BACKGROUND

Epithelial barrier dysfunction and increased permeability may contribute to antigen sensitization and disease progression in asthma. Claudin-18.1 is the only known lung-specific tight junction protein, but its contribution to airway barrier function or asthma is unclear.

OBJECTIVES

We sought to test the hypotheses that claudin-18 is a determinant of airway epithelial barrier function that is downregulated by IL-13 and that claudin-18 deficiency results in increased aeroantigen sensitization and airway hyperresponsiveness.

METHODS

Claudin-18.1 mRNA levels were measured in airway epithelial brushings from healthy controls and patients with asthma. In patients with asthma, claudin-18 levels were compared with a three-gene-mean marker of T_H2 inflammation. Airway epithelial permeability changes due to claudin-18 deficiency were measured in 16HBE cells and claudin-18 null mice. The effect of IL-13 on claudin expression was determined in primary human airway epithelial cells and in mice. Airway hyperresponsiveness and serum IgE levels were compared in claudin-18 null and wild-type mice following aspergillus sensitization.

RESULTS

Epithelial brushings from patients with asthma (n = 67) had significantly lower claudin-18 mRNA levels than did those from healthy controls (n = 42). Claudin-18 levels were lowest among T_H2-high patients with asthma. Loss of claudin-18 was sufficient to impair epithelial barrier function in 16HBE cells and in mouse airways. IL-13 decreased claudin-18 expression in primary human cells and in mice. Claudin-18 null mice had significantly higher serum IgE levels and increased airway responsiveness following intranasal aspergillus sensitization.

CONCLUSIONS

These data support the hypothesis that claudin-18 is an essential contributor to the airway epithelial barrier to aeroantigens. Furthermore, T_H2 inflammation suppresses claudin-18 expression, potentially promoting sensitization and airway hyperresponsiveness.

The transcription factor BATF modulates cytokine-mediated responses in T cells

The transcription factor BATF (basic leucine zipper transcription factor, ATF-like), belongs to the AP-1 family of transcription factors and has been shown to be predominantly expressed in cells of haematopoietic origin, especially in B and T cells. In studies using Batf-deficient mice, a profound defect in the differentiation of T helper cells type 17 (Th17) and follicular T helper cells (Tfh) was described, as well as an impairment of antibody production with switched isotypes. More recently BATF has been described to influence also Th2 and Th9 responses in models of murine experimental asthma. In CD8(+) T cells BATF has been found associated with anti-viral responses. This review summarizes the role of BATF in CD4(+) T cell subsets and in CD8(+) T cells, with particular focus on this transcription factor in the setting of allergic asthma.

Asthma in the elderly patient

Asthma affects a significant proportion of elderly patients, but unfortunately, it is responsible for a high asthma-related morbidity and mortality in this population. This may be related not only to the development of a more severe asthma phenotype compared to younger patients, with more marked airway obstruction and a more neutrophilic type of airway inflammation, but also to the presence of many co-morbid conditions. Furthermore, in older patients, asthma is often under-diagnosed, undertreated and poorly managed. Unfortunately, elderly patients have usually been excluded of clinical trials on asthma and there is an urgent need to perform more research on the optimal management of asthma in this population.

Local IgE in non-allergic rhinitis

Local allergic rhinitis (LAR) is characterized by the presence of a nasal Th2 inflammatory response with local production of specific IgE antibodies and a positive response to a nasal allergen provocation test (NAPT) without evidence of systemic atopy. The prevalence has been shown to be up to 25% in subjects affected with rhinitis with persistence, comorbidity and evolution similar to allergic rhinitis. LAR is a consistent entity that does not evolve to allergic rhinitis with systemic atopy over time although patients have significant impairment in quality of life and increase in the severity of nasal symptoms over time. Lower airways can be also involved. The diagnosis of LAR is based mostly on demonstration of positive response to NAPT and/or local synthesis of specific IgE. Allergens involved include seasonal or perennial such as house dusts mites, pollens, animal epithelia, moulds (alternaria) and others. Basophils from peripheral blood may be activated by the involved allergens suggesting the spill over of locally synthesized specific IgE to the circulation. LAR patients will benefit from the same treatment as allergic patients using antihistamines, inhaled corticosteroids and IgE antagonists. Studies on immunotherapy are ongoing and will determine its efficacy in LAR in terms of symptoms improvement and evolution of the natural course of the disease.

Decreased Serum Epinephrine in Children With Positive Skin Prick Test

Objectives

To evaluate the association between catecholamine levels and skin prick test results among children.

Methods

Two hundred eight first grade children from one elementary school were invited to participate in this study. Skin prick test (SPT) for six allergens (2 house dust mites, cat, dog, mugwort, and pollen mixture) was performed, and patient demographic information was recorded. The parents were surveyed using questionnaires about rhinitis-related symptoms. Finally, venous blood sampling was done to measure catecholamine levels (epinephrine, norepinephrine, and dopamine) by high-performance liquid chromatography.

Results

Out of 208 children, 174 (106 boys and 68 girls) enrolled in this study. Ninety-six of the children (55%) had negative SPT (nonsensitization group), while 78 (45%) had a positive SPT to at least one of six allergens (sensitization group). The diagnosis of chronic rhinitis was more prevalent in the sensitization group (35.9%) than nonsensitization group (26.0%), however the finding was not significant (P=0.186). Epinephrine levels were decreased between the sensitization group compared to the nonsensitization group (P=0.004). There was no difference in norepinephrine and dopamine levels (P>0.05).

Conclusion

Epinephrine levels are lower in children with positive SPT compared to controls, however, the level of the catecholamine was not associated with the presence or absence of rhinitis symptoms.

Experimentally manipulated sleep duration in adolescents with asthma: Feasibility and preliminary findings

OBJECTIVE

To examine the impact of sleep duration on lung function and asthma symptoms in adolescents.

METHODS

Ten adolescents with asthma (60% female, 60% Caucasian, mean age = 13.7 years, range 12-17) completed a 3-week randomized, cross-over sleep manipulation protocol. Following a week of self-selected sleep duration, adolescents were randomized to a five-night deficient sleep opportunity (6.5 hr in bed) or a healthy sleep opportunity (10 hr in bed) obtained by systematically changing bedtimes. Wake time remained consistent across all 3 weeks (including weekends). Daily reports of sleep patterns and asthma symptoms, actigraphy, and daily peak expiratory flow rates (PEFR), as well as weekly spirometry and exhaled nitric oxide were collected.

RESULTS

Participants averaged 3.2 hr less sleep (P < 0.001) per night in the short sleep condition versus the long sleep condition. Further, they had an 8.4% decrease overnight in PEFR (P = 0.007), and reported more asthma symptoms interfering with activities in the past 24 hr (P = 0.02) in the short sleep condition than the long sleep condition. No significant differences between experimental weeks were found for weekly spirometry or exhaled nitric oxide.

CONCLUSIONS

This pilot study demonstrated the feasibility of a cross-over sleep manipulation protocol in adolescents with asthma. Since overnight decrease in PEFR is a marker of nocturnal asthma, and has been associated with the severity of daytime airflow limitation, these early-stage results suggest that shortened sleep duration may exacerbate adolescent asthma and associated functional impairments.

Epithelial barrier function and immunity in asthma

The bronchial epithelium is constantly exposed to a wide range of environmental materials present in inhaled air, including noxious gases and anthropogenic and natural particulates, such as gas and particles from car emissions, tobacco smoke, pollens, animal dander, and pathogens. As a fully differentiated, pseudostratified mucociliary epithelium, the bronchial epithelium protects the internal milieu of the lung from these agents by forming a physical barrier involving adhesive complexes and a chemical barrier involving secretion of mucus, which traps inhaled particles that can be cleared by the mucociliary escalator. It is a testament to the effectiveness of these two barriers that most environmental challenges are largely overcome without the need to develop an inflammatory response. However, as the initial cell of contact with the environment, the bronchial epithelium also plays a pivotal role in immune surveillance and appropriate activation of immune effector cells and antigen presenting cells in the presence of pathogens or other danger signals. Thus, the bronchial epithelium plays a central role in controlling tissue homeostasis and innate immunity. This review will discuss these barrier properties and how dysregulation of these homeostatic mechanisms can contribute to disease pathologies such as asthma.

Obesity and atopy

The prevalence of obesity has increased worldwide, and weight gain has been shown to influence the development and clinical expression of various conditions including asthma. The relationships between atopy and obesity remain uncertain, both in adults and in children. Although there are physiopathologic mechanisms which could explain how obesity could influence the immune system and promote the process of sensitization, evidences in favour of a possible role of obesity on the development of atopy have been inconsistent. Furthermore, the bulk of evidence suggests that atopy does not mediate the relationship between obesity and asthma, although in some populations, particularly in children and women, such association has been reported. Such lack of relationship has also been found with rhinoconjunctivitis although it has been observed for atopic dermatitis. Several factors may explain these variable results, including populational or environmental characteristics, socioeconomic status, confounding factors, in addition to sample size, and methodology of the performed studies. The possibility that obesity influences atopy through its effects on sex hormones is suggested by a more frequent link between atopy and obesity in women, particularly postpuberal. Further research should be conducted on the influence of weight gain on atopy and atopic diseases.

New and future strategies to improve asthma control in children

Symptomatic asthma in childhood has lifelong effects on lung function and disease severity, emphasizing the need for improved pediatric asthma control. Control of pediatric risk and impairment domains can be achieved through increased medication adherence or new therapeutic strategies. Developing electronic monitoring device technology with reminders might be a key noninvasive resource to address poor adherence in children and adolescents in a clinical setting. In patients who have persistently poor control despite optimal medication compliance, newly emerging pharmaceuticals, including inhaled therapies and biologics, might be key to their treatment. However, barriers exist to their development in the pediatric population, and insights must be drawn from adult studies, which has its own unique limitations. Biomarkers to direct the use of such potentially expensive therapies to those patients most likely to benefit are imperative. In this review the current literature regarding strategies to improve pediatric asthma control is addressed with the goal of exploring the potential and pitfalls of strategies that might be available in the near future.

Syk mediates airway contractility independent of leukocyte function

BACKGROUND

Syk, an immune regulatory tyrosine kinase, plays a role in inflammatory disease processes. We recently reported a role for epithelial expression of Syk in the airways hyper-responsiveness in response to air pollution in a mouse model of asthma. The aim of this study was to further investigate the role of Syk in airway contractility in response to methacholine (MCh) and particulate matter (PM) air pollutants, in the absence of underlying inflammation.

METHODS

We used Syk(flox/flox) //rosa26CreER(T) (2) conditional Syk knockout mice to evaluate respiratory mechanics and MCh responsiveness following PM exposure in vivo using the ventilator-based flexiVent system.

RESULTS

While total and differential cell counts in bronchoalveolar lavage fluid were similar between the Syk(flox/flox) and Syk(del/del) mice, central airways respiratory resistance (RN ) to MCh was significantly augmented following PM exposure between Syk-intact (Syk(flox/flox) ) and Syk-deficient (Syk(del/del) ) mice (RN (max) : 2.06 ± 0.29 vs. 1.29 ± 0.10, respectively; p < 0.05, n = 8-10/group). We employed live videomicroscopy to investigate changes in airway luminal diameter using ex vivo lung slices, which were devoid of circulating leukocytes. MCh reduced the airway luminal area of Syk(flox/flox) mice to 81.1 ± 1.4% of baseline, which was virtually abrogated in Syk(del/del) mice (luminal area = 93.2 ± 0.5%, n = 5/group, p < 0.05). In response to PM exposure, Syk(flox/flox) airways contracted to 73.8 ± 2.7% of baseline luminal diameter, whereas Syk(del/del) airways exhibited minimal contractility to PM and MCh (90.0 ± 1.3% of baseline, n = 5/group, p < 0.05).

CONCLUSIONS

These observations suggest that Syk mediates airway contractility in the normal and allergic airways, independent of its role and function in leukocytes, and supports a paracrine role for airway epithelial Syk in modulating airway smooth muscle activity.

Novel treatments of asthma and allergic diseases

The prevalence of allergic diseases has considerably increased, mostly in industrialized countries (> 20%), and asthma affects approximately 300 million individuals worldwide. Current therapies are able to control symptoms although they do not modulate immunological dysregulation that characterizes allergic diseases. Over the last 30 years, only a few new drugs have been introduced on the market and they all act on Th2-type response which has a critical role in the pathogenesis of allergic diseases. Recently, a new scenario has been opened on Th17-cells, Th1-type cytokines and innate immune system components involved in the inflammatory pathogenesis of asthma and other allergic diseases. These findings suggest a promising therapeutic role of new agents that block the action of specific cytokines. Furthermore, the concept of an intrinsic structural defect in the bronchial epithelium paves the way to innovative therapeutic strategies. In this review we present an update on therapies for allergic diseases with special focus on asthma.

Effects of immunomodulatory supplementation with Lactobacillus rhamnosus on airway inflammation in a mouse asthma model

BACKGROUND

Asthma is a common allergic disease. In previous studies, probiotics improved the balance of intestinal microbes, reduced inflammation, and promoted mucosal tolerance. This study investigated whether oral administrations of Lactobacillus rhamnosus GG (LGG) inhibited allergen (ovalbumin or OVA)-induced airway inflammation in a mouse asthma model.

METHODS

The allergy/asthma animal model in this study was sensitization with OVA. After intranasal challenge with OVA, the airway inflammation and hyper-responsiveness were determined by a Buxco system, bronchoalveolar lavage fluid analysis with Liu stain, and enzyme-linked immunosorbent assay. Histopathologic changes in the lung were detected by hematoxylin and eosin staining and immunohistochemistry staining.

RESULTS

Both pre- and post-treatment with LGG suppressed the airway hyper-responsiveness to methacholine and significantly decreased the number of infiltrating inflammatory cells and Th2 cytokines in bronchoalveolar lavage fluid and serum compared with the OVA-sensitized mice. In addition, LGG reduced OVA-specific IgE levels in serum. Oral LGG decreased matrix metalloproteinase 9 expression in lung tissue and inhibited inflammatory cell infiltration.

CONCLUSION

LGG had an anti-inflammatory effect on OVA-induced airway inflammation and might be an additional or supplementary therapy for allergic airway diseases.

Dupilumab: a novel treatment for asthma

Simultaneously with the steady progress towards a better knowledge of the pathobiology of asthma, the potential usefulness of anticytokine therapies is emerging as one of the key concepts in the newly developing treatments of this widespread airway disease. In particular, given the key role played by interleukin (IL)-4 and IL-13 in the pathophysiology of the most typical aspects of asthma, such as chronic airway inflammation, tissue remodeling, and bronchial hyperresponsiveness, these pleiotropic cytokines are now considered as suitable therapeutic targets. Among the recently developed antiasthma biologic drugs, the monoclonal antibody dupilumab is very promising because of its ability to inhibit the biological effects of both IL-4 and IL-13. Indeed, dupilumab prevents IL-4/13 interactions with the α-subunit of the IL-4 receptor complex. A recent trial showed that in patients with difficult-to-control asthma, dupilumab can markedly decrease asthma exacerbations and improve respiratory symptoms and lung function; these effects were paralleled by significant reductions in T-helper 2-associated inflammatory biomarkers. However, further larger and longer trials are required to extend and validate these preliminary results, and also to carefully study the safety and tolerability profile of dupilumab.

Basophils as a primary inducer of the T helper type 2 immunity in ovalbumin-induced allergic airway inflammation

Antigen-induced allergic airway inflammation is mediated by T helper type 2 (Th2) cells and their cytokines, but the mechanism that initiates the Th2 immunity is not fully understood. Recent studies show that basophils play important roles in initiating Th2 immunity in some inflammatory models. Here we explored the role of basophils in ovalbumin (OVA) -induced airway allergic inflammation in BALB/c mice. We found that OVA sensitization and challenge resulted in a significant increase in the amount of basophils in blood and lung, along with the up-regulation of activation marker of CD200R. However, depletion of basophils with MAR-1 or Ba103 antibody attenuated airway inflammation, represented by the significantly decreased amount of the Th2 subset in spleen and draining lymph nodes, interlukin-4 level in lung and OVA-special immunoglobulin E (sIgE) levels in serum. On the other hand, adoptive transfer of basophils from OVA-challenged lung tissue to naive BALB/c mice provoked the Th2 immune response. In addition, pulmonary basophils from OVA-challenged mice were able to uptake DQ-OVA and express MHC class II molecules and CD40 in vivo, as well as to release interleukin-4 following stimulation by IgE-antigen complexes and promote Th2 polarization in vitro. These findings demonstrate that basophils may participate in Th2 immune responses in antigen-induced allergic airway inflammation and that they do so through facilitating antigen presentation and providing interleukin-4.

Group 2 innate lymphoid cells facilitate sensitization to local, but not systemic, TH2-inducing allergen exposures

BACKGROUND

Allergic inflammation involves the sensitization of naive CD4(+) T cells to allergens, resulting in a TH2-skewed inflammatory response. Although antigen presentation by dendritic cells to T cells in the lymph node is crucial for TH2 cell development, the innate signals that initiate adaptive type 2 inflammation and the role of group 2 innate lymphoid cells (ILC2s) are poorly understood.

OBJECTIVE

We sought to investigate the influence of ILC2s and the route of priming on the development of an adaptive type 2 immune response to lung allergens.

METHODS

Wild-type and ILC2-deficient mice were exposed intranasally or systemically to the TH2-inducing antigens house dust mite or ovalbumin in a model of allergic airway inflammation or the TH17-inducing bacterial antigen Saccharopolyspora rectivirgula in a model of hypersensitivity pneumonitis. The formation of an adaptive immune response was evaluated based on serum antibody titers and production of T cell-derived cytokines (IL-4, IL-5, IL-13 and IL-17A).

RESULTS

We find that lung ILC2s play a critical role in priming the adaptive type 2 immune response to inhaled allergens, including the recruitment of eosinophils, TH2 cytokine production and serum IgE levels. Surprisingly, systemic priming with ovalbumin, with or without adjuvants, circumvents the requirement for ILC2s in inducing TH2-driven lung inflammation. ILC2s were also found to be dispensable for the sensitization to TH1- or TH17-inducing antigens.

CONCLUSION

These data highlight a critical role for ILC2s in the development of adaptive type 2 responses to local, but not systemic, antigen exposure.