Pathogenesis of severe asthma

Increased expression of IL1-RL1 is associated with type 2 and type 1 immune pathways in asthma

Background

Asthma is a common chronic airway disease in the world. The purpose of this study was to explore the expression of IL1-RL1 in sputum and its correlation with Th1 and Th2 cytokines in asthma.

Methods

We recruited 132 subjects, detected IL1-RL1 protein level in sputum supernatant by ELISA, and analyzed the correlation between the expression level of IL1-RL1 and fraction of exhaled nitric oxide (FeNO), IgE, peripheral blood eosinophil count (EOS#), and Th2 cytokines (IL-4, IL-5, IL-10, IL-13, IL-33 and TSLP) and Th1 cytokines (IFN-γ, IL-2, IL-8). The diagnostic value of IL1-RL1 was evaluated by ROC curve. The expression of IL1-RL1 was further confirmed by BEAS-2B cell in vitro.

Results

Compared with the healthy control group, the expression of IL1-RL1 in sputum supernatant, sputum cells and serum of patients with asthma increased. The AUC of ROC curve of IL1-RL1 in sputum supernatant and serum were 0.6840 (p = 0.0034), and 0.7009 (p = 0.0233), respectively. IL1-RL1 was positively correlated with FeNO, IgE, EOS#, Th2 cytokines (IL-4, IL-5, IL-10, IL-13, IL-33 and TSLP) and Th1 cytokines (IFN-γ, IL-2, IL-8) in induced sputum supernatant. Four weeks after inhaled glucocorticoids (ICS) treatment, the expression of IL1-RL1 in sputum supernatant and serum was increased. In vitro, the expression of IL1-RL1 in BEAS-2B was increased after stimulated by IL-4 or IL-13 for 24 h.

Conclusion

The expression of IL1-RL1 in sputum supernatant, sputum cells and serum of patients with asthma was increased, and was positively correlated with some inflammatory markers in patients with asthma. IL1-RL1 may be used as a potential biomarker for the diagnosis and treatment of asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-022-00499-z.

Immunobiology of Steroid-Unresponsive Severe Asthma

Asthma is a heterogeneous respiratory disease characterized by airflow obstruction, bronchial hyperresponsiveness and airway inflammation. Approximately 10% of asthma patients suffer from uncontrolled severe asthma (SA). A major difference between patients with SA from those with mild-to-moderate asthma is the resistance to common glucocorticoid treatments. Thus, steroid-unresponsive uncontrolled asthma is a hallmark of SA. An impediment in the development of new therapies for SA is a limited understanding of the range of immune responses and molecular networks that can contribute to the disease process. Typically SA is thought to be characterized by a Th2-low and Th17-high immunophenotype, accompanied by neutrophilic airway inflammation. However, Th2-mediated eosinophilic inflammation, as well as mixed Th1/Th17-mediated inflammation, is also described in SA. Thus, existing studies indicate that the immunophenotype of SA is diverse. This review attempts to summarize the interplay of different immune mediators and related mechanisms that are associated with airway inflammation and the immunobiology of SA.

Asthma with Fixed Airflow Obstruction: From Fixed to Personalized Approach

Asthma is generally characterized by variable symptoms such as dyspnea and wheezing and variable airflow obstruction. This review focuses on a subset of patients suffering from asthma with persistent airflow limitation that is not fully reversible (asthma with fixed airflow obstruction, FAO). The pathophysiology, the risk factors and the clinical outcomes associated with FAO are presented, as well as the distinct clinical entity of severe asthma and its inflammatory subtypes (T2 and non-T2). The current strategies for the treatment of these endotypes and treatment of the distinct Asthma/COPD overlap (ACO) phenotype are described. Management and medical interventions in FAO and/or ACO patients demand a holistic approach, which is not yet clearly established in guidelines worldwide. Finally, a treatment algorithm that includes FAO/ACO management based on pharmacological and non-pharmacological treatment, guideline-based management for specific co-morbidities, and modification of the risk factors is proposed.

Agnuside mitigates OVA-LPS induced perturbed lung homeostasis via modulating inflammatory, autophagy, apoptosis-fibrosis response and myeloid lineages in mice model of allergic asthma

Attributes of agnuside, a nontoxic, iridoid glycoside have been advocated for inflammatory disorders. However, information on its efficacy in alleviating allergic asthma largely remain ambiguous and yet to be deciphered. Present study aimed to assess efficacy of agnuside in targeting vicious circle of oxi-inflammation, autophagy and fibrosis, together with investigating its underlying molecular mechanism during OVA-LPS induced allergic asthma. Results revealed that agnuside showed prophylactic effect in assuaging asthmatic lung architecture impairment (p ≤ 0.01) as indicated by suppression of inflammatory cell infiltration, congestion, fibrosis, airway remodeling and alveolar collapse in OVA-LPS sensitized group. Decreased expression level (p ≤ 0.05) of allergic inflammatory mediators such as IgE, Th1/Th2, IL-4/IFN-γ, IL-4/IL-10, chemokines, endopeptidases and TGF-β, Smad2/4, Caspase9/3, connexin 43/50 observed in agnuside treatments. Analysis of redox molecular signaling cascade and autophagic proteins revealed concurrent upregulation in p-NF-κB, p-PI3K, p-Akt, p-p38, p-Stat3 activation, GATA3, LC3B expression and reduction in Bcl2/Bax, Beclin1 and p62 expression in sensitized mice (p ≤ 0.05) which were intensely counteracted by administration of agnuside. Suppression in myeloid cells activation and augmentation (p ≤ 0.001) of Tregs established modulatory attribute of agnuside for innate and adaptive immune response during allergic asthma. Collectively, these outcomes confer prophylactic attribute of agnuside and signify it as promising strategy to thwart allergic asthma.

The mixture of siRNAs targeted to IL-4 and IL-13 genes effectively reduces the airway hyperreactivity and allergic inflammation in a mouse model of asthma

Bronchial asthma (BA) is one of the most common chronic inflammatory disease of airways. There are huge experimental data indicating that Th2-cytokines IL-4 and IL-13 play a key role in BA pathogenesis. They are implicated in the IgE synthesis, eosinophil infiltration to the lungs and in the development of airway hyperreactivity (AHR), that makes these cytokines the promising targets. Neutralization of IL-4 and IL-13 or its common receptor chain (IL-4Rα) by monoclonal antibodies substantially reduce asthma symptoms. RNA interference provides a novel method for regulation of gene expression by siRNA molecules. In this study we evaluated whether the siRNA targeted to IL-4 and IL-13 reduce BA symptoms in mice model. Experimental BA was induced in BALB/c mice by sensitization to ovalbumin allergen followed by intranasal challenge. The intranasal delivery of siRNAs targeted to IL-4 and IL-13 inhibited the lung expression of these cytokines by more than 50% that led to the attenuation of AHR and pulmonary inflammation; the quantity of eosinophils in lungs which are one of the major inflammatory cells involved in allergic asthma pathogenesis decreased by more than 50% after siRNA treatment. These data support the possibility of a dual IL-4 and IL-13 inhibition by locally delivered siRNAs which in turn leads to the suppression of allergen-induced pulmonary inflammation and AHR.

Polyphenol containing Sargassum horneri attenuated Th2 differentiation in splenocytes of ovalbumin-sensitised mice: involvement of the transcription factors GATA3/STAT5/NLRP3 in Th2 polarization

CONTEXT

Sargassum horneri (Turner) C. Agardh (Sargassaceae) is a brown marine alga used in oriental medicine to treat allergic conditions.

OBJECTIVE

This study clarifies the effect of polyphenol-containing S. horneri ethanol extract (SHE) on T-helper type-2 (Th2) polarisation.

MATERIALS AND METHODS

All mice (BALB/c mice, n = 12) except in the healthy control group were first sensitised with an intraperitoneal injection of ovalbumin (OVA; 20 µg) and alum (2 mg) on Day 0 and Day 14. Similarly, phosphate-buffered saline (PBS) was injected according to the same schedule into the healthy control mice. After the final administration, splenocytes were obtained. OVA sensitised mice were challenged with OVA (100 µg/mL) in the absence or presence (62.5 and 125 µg/mL) of SHE while healthy control group remained untreated.

RESULTS

SHE (0-1000 µg/mL) was not cytotoxic to splenocytes and demonstrated IC50 values of 3.27 and 3.92 mg/mL, respectively, at 24 and 48 h of incubation. SHE suppressed cell proliferation at concentrations ≥62.5 µg/mL. SHE treatment (125 µg/mL) subdued (by 1.8-fold) the population expansion of CD3+CD4+ helper T cells induced by OVA challenge. SHE attenuated the OVA-induced activation of respective transcription factors GATA3 and NLRP3. Simultaneously, highly elevated levels of cytokines interleukin (IL)-4 and IL-5 caused by OVA stimulation were removed completely and IL-13 suppressed by 1.5-fold.

CONCLUSIONS

SHE exhibits Th2 immune suppression under OVA stimulation via GATA3- and NLRP3-dependent IL-4, IL-5, and IL-13 suppression. Therefore, SHE could be therapeutically useful for alleviating the symptoms of allergen-mediated immune diseases.

Parent-child conflict and physical health trajectories among youth with asthma

OBJECTIVE

To investigate the role of caregiver- and youth-reports of parent-child conflict on trajectories of asthma-related health outcomes over 2 years.

METHODS

In a sample of 193 youth with asthma (42.7% female; M age = 12.78) and their primary caregivers, we used a multi-method and multi-informant approach to assess self-reported parent-child conflict from youth and caregivers at both the daily and global levels at baseline. Next, we annually assessed subjective (i.e., youth self-reported asthma symptoms) and clinical (i.e., peak flow) asthma health outcomes for 2 years.

RESULTS

Latent growth curve models revealed an effect of baseline youth-reported global family conflict on peak flow trajectories such that youth who reported greater parent-child conflict at baseline experienced less of an increase in peak flow over time than youth who reported less parent-child conflict at baseline (standardized β = -0.27, p = .003).

CONCLUSIONS

Youth with asthma who perceive greater overall conflict with their caregivers experience less improvement in peak flow as they age. The research and clinical implications of these findings are discussed.

Cluster Analysis of Inflammatory Biomarker Expression in the International Severe Asthma Registry

BACKGROUND

Allergy, eosinophilic inflammation, and epithelial dysregulation are implicated in severe asthma pathogenesis.

OBJECTIVE

We characterized biomarker expression in adults with severe asthma.

METHODS

Within the International Severe Asthma Registry (ISAR), we analyzed data from 10 countries in North America, Europe, and Asia, with prespecified thresholds for biomarker positivity (serum IgE ≥ 75 kU/L, blood eosinophils ≥ 300 cells/μL, and FeNO ≥ 25 ppb), and with hierarchical cluster analysis using biomarkers as continuous variables.

RESULTS

Of 1,175 patients; 64% were female, age (mean ± SD) 53 ± 15 years, body mass index (BMI) 30 ± 8, postbronchodilator forced expiratory volume in 1 second (FEV₁) predicted 72% ± 20%. By prespecified thresholds, 59% were IgE positive, 57% eosinophil positive, and 58% FeNO positive. There was substantial inflammatory biomarker overlap; 59% were positive for either 2 or 3 biomarkers. Five distinct clusters were identified: cluster 1 (61%, low-to-medium biomarkers) comprised highly symptomatic, older females with elevated BMI and frequent exacerbations; cluster 2 (18%, elevated eosinophils and FeNO) older females with lower BMI and frequent exacerbations; cluster 3 (14%, extremely high FeNO) older, highly symptomatic, lower BMI, and preserved lung function; cluster 4 (6%, extremely high IgE) younger, long duration of asthma, elevated BMI, and poor lung function; cluster 5 (1.2%, extremely high eosinophils) younger males with low BMI, poor lung function, and high burden of sinonasal disease and polyposis.

CONCLUSIONS

There is significant overlap of biomarker positivity in severe asthma. Distinct clusters according to biomarker expression exhibit unique clinical characteristics, suggesting the occurrence of discrete patterns of underlying inflammatory pathway activation and providing pathogenic insights relevant to the era of monoclonal biologics.

Qingfei oral liquid inhibited autophagy to alleviate inflammation via mTOR signaling pathway in RSV-infected asthmatic mice

Qingfei oral liquid (QF) is a traditional Chinese medicine that has been used to treat patients with viral pneumonia and asthma for decades. Our previous study revealed that QF prevents airway inflammation and reduces airway hyperresponsiveness (AHR) in respiratory syncytial virus (RSV)-infected asthmatic mice. RSV infection can exacerbate asthma in pediatric patients and induce autophagy, which leads to the promotion of inflammatory cytokine production in the pathology of this disease. The effect of QF on regulating autophagy in RSV-infected asthma patients has not been fully elucidated. In this study, we identified compounds of QF by HPLC-DAD-Q-TOF-MS/MS. The RSV infected OVA challenged mice, we evaluated the RSV-infected asthma model. We found that treatment with QF alleviated airway inflammation and mitigated airway AHR in RSV-infected asthmatic mice. In addition, we found that QF inhibited autophagosome formation and the expression of LC3 protein by using electron and laser confocal microscopy, respectively, to assess RSV-infected asthmatic mice lung tissues. Furthermore, QF was found to reduce the quantity of autophagy and its related proteins LC3B (light chain 3B), Beclin-1, p62 and Atg5 (autophagy-related gene 5) and downstream inflammatory cytokines TNF-α, IL-4, IL-6, and IL-13 via an action in mTOR-dependent signaling in vivo and in vitro. These findings suggest that QF can alleviate the inflammation caused by RSV infection in asthmatic mice, and its mechanism may be involved in the regulation of autophagy via the mTOR signaling pathway.

Identification of histone acetylation in a murine model of allergic asthma by proteomic analysis

The pathogenesis of asthma is closely related to histone acetylation modification, but the specific acetylation sites related to this process remain indistinct. Herein, our study sought to identify differentially modified acetylation sites and their expression distribution in cells involved in asthma in lung tissues. The airway hyper-responsiveness, inflammation, and remodeling were assessed by non-invasive whole-body plethysmography, ELISA, and hematoxylin-eosin staining to confirm the successful establishment of the allergic asthma model. Afterward, the differentially modified acetylation sites in asthmatic lung tissues were identified and validated by using proteomics and western blotting, respectively. The immunohistochemistry analysis was applied to reveal the distribution of identified acetylation sites in asthmatic lung tissues. A total of 15 differentially modified acetylation sites, including 13 upregulated (H3K9ac, H3K14ac, H3K18ac, H3K23ac,H3K27ac, H3K36ac, H2B1KK120ac, H2B2BK20ac, H2BK16ac, H2BK20ac, H2BK108ac, H2BK116ac, and H2BK120ac) and 2 downregulated (H2BK5ac and H2BK11ac) sites were identified and validated. Furthermore, immunohistochemical staining of lung tissues showed that nine of the identified histone acetylation sites (H2BK5, H2BK11, H3K18, H2BK116, H2BK20, H2BK120, H3K9, H3K36, and H3K27) were differentially expressed in airway epithelial cells, and the acetylation of identified H3 histones were observed in both eosinophil and perivascular inflammatory cells. Additionally, differential expression of histone acetylation sites was also observed in nucleus of airway epithelial cells, vascular smooth muscle cells, perivascular inflammatory cells, and airway smooth muscle cells. In conclusion, we identified potential acetylation sites associated with asthma pathogenesis. These findings may contribute greatly in the search for therapeutic approaches for allergic asthma.

IL-2-Agonist-Induced IFN-γ Exacerbates Systemic Anaphylaxis in Food Allergen-Sensitized Mice

Food allergies are common, costly and potentially life-threatening disorders. They are driven by Th2, but inhibited by Th1 reactions. There is also evidence indicating that IL-2 agonist treatment inhibits allergic sensitization through expansion of regulatory T cells. Here, we tested the impact of an IL-2 agonist in a novel model for food allergy to hen´s egg in mice sensitized without artificial adjuvants. Prophylactic IL-2 agonist treatment expanded Treg populations and inhibited allergen-specific sensitization. However, IL-2 agonist treatment of already sensitized mice increased mast cell responses and allergic anaphylaxis upon allergen re-challenge. These effects depended on allergen-specific IgE and were mediated through IFN-γ, as shown by IgE transfer and blockade of IFN-γ with monoclonal antibodies. These results suggest that although shifting the allergic reaction toward a Treg/Th1 response inhibits allergic sensitization, the prototypic Th1 cytokine IFN-γ promotes mast cell activation and allergen-induced anaphylaxis in individuals that are already IgE-sensitized. Hence, while a Th1 response can prevent the development of food allergy, IFN-γ has the ability to exacerbate already established food allergy.

The DNA methylation of FOXO3 and TP53 as a blood biomarker of late-onset asthma

BACKGROUND

Late-onset asthma (LOA) is beginning to account for an increasing proportion of asthma patients, which is often underdiagnosed in the elderly. Studies on the possible relations between aging-related genes and LOA contribute to the diagnosis and treatment of LOA. Forkhead Box O3 (FOXO3) and TP53 are two classic aging-related genes. DNA methylation varies greatly with age which may play an important role in the pathogenesis of LOA. We supposed that the differentially methylated sites of FOXO3 and TP53 associated with clinical phenotypes of LOA may be useful biomarkers for the early screening of LOA.

METHODS

The mRNA expression and DNA methylation of FOXO3 and TP53 in peripheral blood of 43 LOA patients (15 mild LOA, 15 moderate LOA and 13 severe LOA) and 60 healthy controls (HCs) were determined. The association of methylated sites with age was assessed by Cox regression to control the potential confounders. Then, the correlation between differentially methylated sites (DMSs; p-value < 0.05) and clinical lung function in LOA patients was evaluated. Next, candidate DMSs combining with age were evaluated to predict LOA by receiver operating characteristic (ROC) analysis and principal components analysis (PCA). Finally, HDM-stressed asthma model was constructed, and DNA methylation inhibitor 5-Aza-2'-deoxycytidine (5-AZA) were used to determine the regulation of DNA methylation on the expression of FOXO3 and TP53.

RESULTS

Compared with HCs, the mRNA expression and DNA methylation of FOXO3 and TP53 vary significantly in LOA patients. Besides, 8 DMSs from LOA patients were identified. Two of the DMSs, chr6:108882977 (FOXO3) and chr17:7591672 (TP53), were associated with the severity of LOA. The combination of the two DMSs and age could predict LOA with high accuracy (AUC values = 0.924). In HDM-stressed asthma model, DNA demethylation increased the expression of FOXO3 and P53.

CONCLUSIONS

The mRNA expression of FOXO3 and TP53 varies significantly in peripheral blood of LOA patients, which may be due to the regulation of DNA methylation. FOXO3 and TP53 methylation is a suitable blood biomarker to predict LOA, which may be useful targets for the risk diagnosis and clinical management of LOA.

Associations of TNF-α -238G/A, TNF-α -308G/A, and IL-6 -174G/C polymorphisms with the risk of asthma: Evidence from a meta-analysis

BACKGROUND

Previously, many genetic epidemiological studies have investigated associations between Th1-related cytokine polymorphisms and the risk of asthma, with inconsistent results. Accordingly, we carried out a meta-analysis to more precisely estimate associations between Th1-related cytokine polymorphisms and the risk of asthma.

METHODS

Systematic literature searching of Medline, Embase, Wanfang, VIP, and CNKI was conducted by the authors to identify eligible publications, and 69 genetic epidemiological studies were finally found to be eligible for quantitative analyses.

RESULTS

We found that genotypic frequencies of TNF-α -238G/A (dominant comparison: odds ratio [OR] = 0.47, P = .006; overdominant comparison: OR = 1.87, P = .03; allele comparison: OR = 0.50, P = .004), TNF-α -308G/A (dominant comparison: OR = 0.76, P = .001; overdominant comparison: OR = 1.29, P = .002; allele comparison: OR = 0.81, P = .0009) and IL-6 -174G/C (dominant comparison: OR = 0.55, P = .0008) polymorphisms among patients with asthma and control subjects were significantly different. However, we did not detect such a genotypic distribution difference for the IL-1B-511C/T polymorphism.

CONCLUSIONS

The present meta-analysis shows that TNF-α -238G/A, TNF-α -308G/A, and IL-6 -174G/C polymorphisms may influence the risk of asthma.

Effect of bronchial thermoplasty on structural changes and inflammatory mediators in the airways of subjects with severe asthma

BACKGROUND

Bronchial thermoplasty (BT) is a novel technique used in the treatment of subjects with severe refractory asthma. Radiofrequency is provided to airway walls during bronchoscopy in order to reduce airway remodeling. Several clinical studies have reported an improvement in subjects' symptoms following BT. However, how BT affects the airway architectures and inflammatory mediators in the airways has not been yet fully elucidated.

METHODS

Fourteen subjects with severe asthma were recruited in this study according to the criteria of ATS severe asthma definition. The study subjects undertook bronchial biopsy during the bronchoscopy procedure at baseline and 6 weeks after the initial BT treatment. The obtained samples were stained with antibodies for α-smooth muscle actin (α-SMA); protein gene product (PGP) 9.5, a specific nerve marker; von Willebrand factor (vWF), a marker for blood vessels; interleukin-17A (IL-17A) and transforming growth factor-β1 (TGF-β1).

RESULTS

The expression of α-SMA and PGP9.5 were significantly reduced post-BT. There was no significant difference in the number of blood vessels between baseline and post-BT. In addition, BT did not affect the production of IL-17A and TGF-β1 in the airways. The changes in the expression of α-SMA and PGP9.5 had no significant correlation with the improvement of pulmonary function.

CONCLUSION

and Clinical Relevance: This study suggests that BT reduces airway smooth muscle mass and the airway innervation without affecting vasculature and the production of inflammatory mediators in the airways of subjects with severe asthma.

The fungal metabolite cyclonerodiol inhibits IL-4/IL-13 induced Stat6-signaling through blocking the association of Stat6 with p38, ERK1/2 and p300

The IL-4/IL-13/Stat6 pathway is the key driver of asthma pathophysiology. Therefore the development of inhibitors that specifically modulate IL-13/IL-4 or the downstream signaling molecules like Stat6 may be useful as a therapeutic strategy for the treatment of asthma and multiple allergic diseases. We have previously identified the fungal 2,6-cyclofarnesane cyclonerodiol as an inhibitor of IL-4 induced Stat6-dependent signaling in the alveolar epithelial cell line A549 using a transcriptional reporter. In this study we investigated the underlying mode of action of cyclonerodiol on the IL-4/IL-13/Stat6 pathway. Cyclonerodiol failed to interfere with activation, nuclear transport or binding of Stat6 to the corresponding consensus sequence on the DNA. Our results showed that cyclonerodiol blocked serine phosphorylation of Stat6 by affecting its association with p38 and Erk1/2. Cyclonerodiol also prevented the recruitment of the transcriptional coactivator p300 and Stat6 acetylation. These findings suggest that cyclonerodiol affects IL-4/IL-13 induced expression of asthma related marker genes by blocking transcriptional activation.

Dynamic changes in gene expression and alternative splicing mediate the response to acute alcohol exposure in Drosophila melanogaster

Environmental changes typically cause rapid gene expression responses in the exposed organisms, including changes in the representation of gene isoforms with different functions or properties. Identifying the genes that respond to environmental change, including in genotype-specific ways, is an important step in treating the undesirable physiological effects of stress, such as exposure to toxins or ethanol. Ethanol is a unique environmental stress in that chronic exposure results in permanent physiological changes and the development of alcohol use disorders. Drosophila is a classic model for deciphering the mechanisms of the response to alcohol exposure, as it meets the criteria for the development of alcohol use disorders, and has similar physiological underpinnings with vertebrates. Because many studies on the response to ethanol have relied on a priori candidate genes, broad surveys of gene expression and splicing are required and have been investigated here. Further, we expose Drosophila to ethanol in an environment that is genetically, socially, and ecologically relevant. Both expression and splicing differences, inasmuch as they can be decomposed, contribute to the response to ethanol in Drosophila melanogaster. However, we find that while D. melanogaster responds to ethanol, there is very little genetic variation in how it responds to ethanol. In addition, the response to alcohol over time is dynamic, suggesting that incorporating time into studies on the response to the environment is important.

Air pollution and resistance to inhaled glucocorticoids: Evidence, mechanisms and gaps to fill

Substantial evidence indicates that cigarette smoke exposure induces resistance to glucocorticoids, the primary maintenance medication in asthma treatment. Modest evidence also suggests that air pollution may reduce the effectiveness of these critical medications. Cigarette smoke, which has clear parallels with air pollution, has been shown to induce glucocorticoid resistance in asthma and it has been speculated that air pollution may have similar effects. However, the literature on an association of air pollution with glucocorticoid resistance is modest to date. In this review, we detail the evidence for, and against, the effects of air pollution on glucocorticoid effectiveness, focusing on results from epidemiology and controlled human exposure studies. Epidemiological studies indicate a correlation between increased air pollution exposure and worse asthma symptoms. But these studies also show a mix of beneficial and harmful effects of glucocorticoids on spirometry and asthma symptoms, perhaps due to confounding influences, or the induction of glucocorticoid resistance. We describe mechanisms that may contribute to reductions in glucocorticoid responsiveness following air pollution exposure, including changes to phosphorylation or oxidation of the glucocorticoid receptor, repression by cytokines, or inflammatory pathways, and epigenetic effects. Possible interactions between air pollution and respiratory infections are also briefly discussed. Finally, we detail a number of therapies that may boost glucocorticoid effectiveness or reverse resistance in the presence of air pollution, and comment on the beneficial effects of engineering controls, such as air filtration and asthma action plans. We also call attention to the benefits of improved clean air policy on asthma. This review highlights numerous gaps in our knowledge of the interactions between air pollution and glucocorticoids to encourage further research in this area with a view to reducing the harm caused to those with airways disease.

Effects of anthraquinones from Cassia occidentalis L. on ovalbumin-induced airways inflammation in a mouse model of allergic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Cassia occidentalis Linn. is a traditional ayruvedic edible shrub containing anthraquinones (AQs) as the principle active constituents. In folk medicine, it has a variety of uses including treatment of whooping cough ('pertussis') and inflammatory diseases. Despite these applications, limited data are available to validate the effects of C. occidentalis AQs on airways inflammation in asthma.

AIM OF THE STUDY

To explore the anti-inflammatory potential of AQs extracted from C. occidentalis using an in vivo model of ovalbumin (OVA)-induced asthma.

MATERIALS AND METHODS

Extraction and optimization of AQs from C. occidentalis was performed by mechanochemistry. Allergic asthma in BALB/c mice was sensitized and challenged by OVA, and the effects of AQs investigated in a mouse model. OVA-specific IgE concentrations in serum, and Th1/Th2 cytokine (IL-4, IL-5, IL-13 and IFN-γ) concentrations, inflammatory cell counts and classification in bronchoalveolar lavage fluid (BALF) were determined. Histopathological evaluation of lung tissue was performed using hematoxylin and eosin (H&E), and periodic acid-schiff (PAS) staining. Th1/Th2 cytokine mRNA expression was analyzed using the 2^-ΔΔCt method.

RESULTS

Treatment with AQs decreased inflammatory cell counts and production of Th2 cytokines (IL-4, IL-5 and IL-13) in BALF, and OVA-specific IgE in serum. In contrast,Th1 cytokine IFN-γ production in BALF was promoted. AQs also decreased mRNA expression of Th1/Th2 cytokine in lung tissue. Histological studies demonstrated that AQs substantially inhibited OVA-induced cellular infiltration, mucus hypersecretion and goblet cell hyperplasia in the lung.

CONCLUSIONS

These findings demonstrated the inhibitory effects of AQs, derived from C. occidentalis, on OVA-induced allergic asthma in mice. The results suggest a promising ethnopharmacological use for AQs in patients with asthma.

Biological therapies for eosinophilic asthma

INTRODUCTION

Severe uncontrolled asthma is by definition refractory to traditional therapies or can be controlled only with therapies that have intolerable side effects. Monoclonal antibodies that target interleukin (IL)-5/IL-5Rα, IgE, and IL-4Rα have shown favorable results in clinical trials, including reductions in asthma exacerbations and other important clinical outcomes. These biological agents offer treatment alternatives to patients with uncontrolled severe eosinophilic asthma.

AREAS COVERED

This article reviews how the shifting emphasis toward identifying distinct asthma phenotypes has led to the approval of biological therapies that preferentially benefit patients with severe eosinophilic asthma. The clinical trials that led to the approval of these biologic treatments are discussed in detail.

EXPERT OPINION

Biologic therapies targeting the IL-5, IgE, IL-4/IL-13 signaling pathways have been successful in clinical trials in subjects with severe eosinophilic asthma. Some of these agents have also been successful regardless of peripheral blood eosinophil counts. These treatments have shown a relatively favorable safety profile in clinical trials, although long-term safety data for some of these agents are limited. Due to the high costs associated with these medications, they should be reserved for select patients where they yield a therapeutic and pharmacoeconomic advantage.

MyD88-dependent dendritic and epithelial cell crosstalk orchestrates immune responses to allergens

Sensitization to inhaled allergens is dependent on activation of conventional dendritic cells (cDCs) and on the adaptor molecule, MyD88. However, many cell types in the lung express Myd88, and it is unclear how signaling in these different cell types reprograms cDCs and leads to allergic inflammation of the airway. By combining ATAC-seq with RNA profiling, we found that MyD88 signaling in cDCs maintained open chromatin at select loci even at steady state, allowing genes to be rapidly induced during allergic sensitization. A distinct set of genes related to metabolism was indirectly controlled in cDCs through MyD88 signaling in airway epithelial cells (ECs). In mouse models of asthma, Myd88 expression in ECs was critical for eosinophilic inflammation, whereas Myd88 expression in cDCs was required for Th17 cell differentiation and consequent airway neutrophilia. Thus, both cell-intrinsic and cell-extrinsic MyD88 signaling controls gene expression in cDCs and orchestrates immune responses to inhaled allergens.

Peucedanum japonicum extract attenuates allergic airway inflammation by inhibiting Th2 cell activation and production of pro-inflammatory mediators

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Peucedanum japonicum Thunberg is traditionally used to treat coughs, colds, headache and inflammatory diseases in Korea and Japan. Its effects on allergic lung inflammation have not been investigated.

AIM OF THE STUDY

To investigate the anti-asthmatic effects of Peucedanum japonicum extract (PJE) using a murine model of asthma and a lipopolysaccharide (LPS)-stimulated macrophage cell line.

MATERIALS AND METHODS

Mice underwent two rounds of sensitization with ovalbumin 1 week apart followed by four intranasal ovalbumin challenges on days 13-16. The control group received saline only. Two ovalbumin-sensitized groups were orally administered vehicle or PJE (200mg/kg) 5 days a week starting 1 week before the first ovalbumin sensitization. The third group was orally administered the asthma medication Montelukast (10mg/kg) on days 12-16. All animals were sacrificed on day 17. The lungs were assessed for histological features, inflammatory cell infiltration, Th2 cell activation and GATA-binding protein-3 (GATA-3) expression. The bronchoalveolar lavage fluid (BALF) was assessed for type 2 cytokine levels. The effect of PJE on the in vitro Th2 polarization of naïve CD4⁺ splenocytes and the production of pro-inflammatory mediators and cytokines by LPS-stimulated RAW 264.7 cells was evaluated.

RESULTS

PJE treatment inhibited OVA-induced inflammatory cell infiltration, eosinophilia, Th2 activation, and GATA-3 expression in the lung, reduced the interleukin (IL)-5 and IL-13 levels in BALF, down-regulated Th2 activation in vitro, and inhibited the macrophage production of inducible nitric oxide, cyclooxygenase-2, tumor necrosis factor-α, and IL-6.

CONCLUSION

PJE attenuated allergic airway inflammation by inhibiting Th2 cell activation and macrophage production of inflammatory mediators. Peucedanum japonicum may be candidate therapy for allergic lung inflammation.

Tomatidine Attenuates Airway Hyperresponsiveness and Inflammation by Suppressing Th2 Cytokines in a Mouse Model of Asthma

Tomatidine is isolated from the fruits of tomato plants and found to have anti-inflammatory effects in macrophages. In the present study, we investigated whether tomatidine suppresses airway hyperresponsiveness (AHR) and eosinophil infiltration in asthmatic mice. BALB/c mice were sensitized with ovalbumin and treated with tomatidine by intraperitoneal injection. Airway resistance was measured by intubation analysis as an indication of airway responsiveness, and histological studies were performed to evaluate eosinophil infiltration in lung tissue. Tomatidine reduced AHR and decreased eosinophil infiltration in the lungs of asthmatic mice. Tomatidine suppressed Th2 cytokine production in bronchoalveolar lavage fluid. Tomatidine also blocked the expression of inflammatory and Th2 cytokine genes in lung tissue. In vitro, tomatidine inhibited proinflammatory cytokines and CCL11 production in inflammatory BEAS-2B bronchial epithelial cells. These results indicate that tomatidine contributes to the amelioration of AHR and eosinophil infiltration by blocking the inflammatory response and Th2 cell activity in asthmatic mice.

Environmental perturbations lead to extensive directional shifts in RNA processing

Environmental perturbations have large effects on both organismal and cellular traits, including gene expression, but the extent to which the environment affects RNA processing remains largely uncharacterized. Recent studies have identified a large number of genetic variants associated with variation in RNA processing that also have an important role in complex traits; yet we do not know in which contexts the different underlying isoforms are used. Here, we comprehensively characterized changes in RNA processing events across 89 environments in five human cell types and identified 15,300 event shifts (FDR = 15%) comprised of eight event types in over 4,000 genes. Many of these changes occur consistently in the same direction across conditions, indicative of global regulation by trans factors. Accordingly, we demonstrate that environmental modulation of splicing factor binding predicts shifts in intron retention, and that binding of transcription factors predicts shifts in alternative first exon (AFE) usage in response to specific treatments. We validated the mechanism hypothesized for AFE in two independent datasets. Using ATAC-seq, we found altered binding of 64 factors in response to selenium at sites of AFE shift, including ELF2 and other factors in the ETS family. We also performed AFE QTL mapping in 373 individuals and found an enrichment for SNPs predicted to disrupt binding of the ELF2 factor. Together, these results demonstrate that RNA processing is dramatically changed in response to environmental perturbations through specific mechanisms regulated by trans factors.

IgE and eosinophils as therapeutic targets in asthma

PURPOSE OF REVIEW

Asthma is a chronic inflammatory disorder characterized by reversible airflow obstruction, which is being more widely recognized as a broad-spectrum disease that encompasses multiple patient characteristics and pathophysiologic mechanisms. Suboptimal asthma control leads to increasing burden of healthcare costs and loss of productivity to society. Biologic therapies targeted at IgE and eosinophils can be used in poorly controlled allergic and eosinophilic asthma, respectively. The purpose of this review is to analyze the advancements in currently available biologic therapies targeted at IgE and eosinophils in asthma and to identify how these therapies may impact overall healthcare costs.

RECENT FINDINGS

Omalizumab is an anti-IgE antibody that is approved for use of poorly controlled moderate-to-severe asthma. Many studies have confirmed that omalizumab not only improves quality of life and symptom scores, but also decreases urgent care and emergency department visits and hospitalizations. Dupilumab is a biologic agent targeted at TH2 cytokines, but indirectly impacts IgE and is an important biologic agent for atopic disease. Mepolizumab, reslizumab, and benralizumab target IL-5, a key cytokine for eosinophils. For patients with poorly controlled eosinophilic asthma, these biologic agents improve asthma symptoms, reduce exacerbations, and reduce emergency visits and hospitalizations.

SUMMARY

Poorly controlled severe asthma affects a small portion of patients with asthma in the United States and yet it accounts for large portion of healthcare utilization. Biological therapies in poorly controlled severe persistent asthma have been identified to reduce healthcare utilization, including emergency visits and hospitalizations. Biologic agents have a clear beneficial role in the management of severe asthma, and further evaluations should be continued in identifying optimal patient characteristics for the various agents and overall benefit toward healthcare utilization and cost.

Fluticasone/salmeterol reduces remodelling and neutrophilic inflammation in severe equine asthma

Asthmatic airways are inflamed and undergo remodelling. Inhaled corticosteroids and long-acting β2-agonist combinations are more effective than inhaled corticosteroid monotherapy in controlling disease exacerbations, but their effect on airway remodelling and inflammation remains ill-defined. This study evaluates the contribution of inhaled fluticasone and salmeterol, alone or combined, to the reversal of bronchial remodelling and inflammation. Severely asthmatic horses (6 horses/group) were treated with fluticasone, salmeterol, fluticasone/salmeterol, or with antigen avoidance for 12 weeks. Lung function, central and peripheral airway remodelling, and bronchoalveolar inflammation were assessed. Fluticasone/salmeterol and fluticasone monotherapy decreased peripheral airway smooth muscle remodelling after 12 weeks (p = 0.007 and p = 0.02, respectively). On average, a 30% decrease was observed with both treatments. In central airways, fluticasone/salmeterol reversed extracellular matrix remodelling after 12 weeks, both within the lamina propria (decreased thickness, p = 0.005) and within the smooth muscle layer (p = 0.004). Only fluticasone/salmeterol decreased bronchoalveolar neutrophilia (p = 0.03) to the same extent as antigen avoidance already after 8 weeks. In conclusion, this study shows that fluticasone/salmeterol combination decreases extracellular matrix remodelling in central airways and intraluminal neutrophilia. Fluticasone/salmeterol and fluticasone monotherapy equally reverse peripheral airway smooth muscle remodelling.

High probability of comorbidities in bronchial asthma in Germany

Clinical experience has shown that allergic and non-allergic respiratory, metabolic, mental, and cardiovascular disorders sometimes coexist with bronchial asthma. However, no study has been carried out that calculates the chance of manifestation of these disorders with bronchial asthma in Saarland and Rhineland-Palatinate, Germany. Using ICD10 diagnoses from health care institutions, the present study systematically analyzed the co-prevalence and odds ratios of comorbidities in the asthma population in Germany. The odds ratios were adjusted for age and sex for all comorbidities for patients with asthma vs. without asthma. Bronchial asthma was strongly associated with allergic and with a lesser extent to non-allergic comorbidities: OR 7.02 (95%CI:6.83-7.22) for allergic rhinitis; OR 4.98 (95%CI:4.67-5.32) allergic conjunctivitis; OR 2.41 (95%CI:2.33-2.52) atopic dermatitis; OR 2.47 (95%CI:2.16-2.82) food allergy, and OR 1.69 (95%CI:1.61-1.78) drug allergy. Interestingly, increased ORs were found for respiratory diseases: 2.06 (95%CI:1.64-2.58) vocal dysfunction; 1.83 (95%CI:1.74-1.92) pneumonia; 1.78 (95%CI:1.73-1.84) sinusitis; 1.71 (95%CI:1.65-1.78) rhinopharyngitis; 2.55 (95%CI:2.03-3.19) obstructive sleep apnea; 1.42 (95%CI:1.25-1.61) pulmonary embolism, and 3.75 (95%CI:1.64-8.53) bronchopulmonary aspergillosis. Asthmatics also suffer from psychiatric, metabolic, cardiac or other comorbidities. Myocardial infarction (OR 0.86, 95%CI:0.79-0.94) did not coexist with asthma. Based on the calculated chances of manifestation for these comorbidities, especially allergic and respiratory, to a lesser extent also metabolic, cardiovascular, and mental disorders should be taken into consideration in the diagnostic and treatment strategy of bronchial asthma.

BRONCHIAL ASTHMA

PREVALENCE OF CO-EXISTING DISEASES IN GERMANY: Patients in Germany with bronchial asthma are highly likely to suffer from co-existing diseases and their treatments should reflect this. Quoc Thai Dinh at Saarland University Hospital in Homburg, Germany, and co-workers conducted a large-scale study of patients presenting with bronchial asthma in the Saarland region between 2009 and 2012. Patients with asthma made up 5.4% of the region's total population, with a higher prevalence occurring in females. They found that bronchial asthma was strongly associated with allergic comorbidities such as rhinitis. Indeed, asthmatic patients had a seven times higher chance to suffer from allergic rhinitis than the rest of the population, and were at higher risk of respiratory diseases like pneumonia and obstructive sleep apnea syndrome. Further associations included cardiovascular, metabolic and mental disorders. Dinh's team call for asthma treatments to take such comorbidities into account.

Severe Asthma: Have We Made Progress?

Tremendous efforts have been invested in research to (1) discover risk factors, biomarkers, and clinical characteristics; (2) understand the pathophysiology and treatment response variability in severe asthma; and (3) design new therapies. However, to combat severe asthma, many questions concerning the pathogenesis of severe asthma, including its natural history, genetic and environmental risk factors, and disease mechanisms, must be answered. In this article we highlight some of the major discoveries concerning the pathogenesis of severe asthma and its therapeutic development. We conclude that discoveries on numerous fronts of severe asthma, from disease heterogeneity, features of airway remodeling, cytokine mediators and signaling pathways underlying disease pathogenesis, disease mechanisms, potential biomarkers, to new therapeutic targets, demonstrate that progress has been made in understanding and developing more effective treatments for this difficult-to-treat disease.

Protein phosphatase 5 mediates corticosteroid insensitivity in airway smooth muscle in patients with severe asthma

BACKGROUND

The mechanisms driving glucocorticoid (GC) insensitivity in patients with severe asthma are still unknown. Recent evidence suggests the existence of GC-insensitive pathways in airway smooth muscle (ASM) caused by a defect in GC receptor (GRα) function. We examined whether other mechanisms could potentially explain the reduced sensitivity of ASM cells to GC in severe asthmatics.

METHODS

Airway smooth muscle cells from healthy and severe asthmatic subjects were treated with TNF-α and responses to corticosteroids in both cohorts were compared by ELISA, immunoblot, immunohistochemistry and real-time PCR. Immunohistochemistry and flow cytometry assays were used to assess the expression of the protein phosphatase PP5 in endobronchial biopsies and ASM cells.

RESULTS

The production of CCL11 and CCL5 by TNF-α was insensitive to both fluticasone and dexamethasone in ASM cells from severe asthmatic compared to that in healthy subjects. Fluticasone-induced GRα nuclear translocation, phosphorylation at serine 211 and expression of GC-induced leucine zipper (GILZ) were significantly reduced in ASM cells from severe asthmatics compared to responses in healthy subjects. Levels of PP5 were increased in ASM cells from severe asthmatics and PP5 knockdown using siRNA restored fluticasone repressive action on chemokine production and its ability to induce GRα nuclear translocation and GRE-dependent GILZ expression. In vivo PP5 expression was also increased in the ASM bundles in endobronchial biopsies in severe asthmatics.

CONCLUSIONS

PP5-dependent impairment of GRα function represents a novel mechanism driving GC insensitivity in ASM in severe asthma.

Conjugated linoleic acids suppress inflammatory response and ICAM-1 expression through inhibition of NF-κB and MAPK signaling in human bronchial epithelial cells

Conjugated linoleic acids (CLAs) comprise a group of natural unsaturated fatty acids. CLA was reported to have anti-asthma, anti-adiposity, and anti-tumor effects. The present study aimed to evaluate the suppressive effects of cis-9, trans-11-CLA (c9,t11-CLA) on the expression of proinflammatory cytokines and intercellular adhesion molecule 1 (ICAM-1) in TNF-α-stimulated human bronchial epithelial (BEAS-2B) cells. After treating with various doses of c9,t11-CLA (12.5-100 μg ml(-1)), BEAS-2B cells were induced into an inflamed state by adding TNF-α or TNF-α/IL-4. The presence of c9,t11-CLA significantly suppressed the secretion of cytokines IL-6, IL-8, CCL5, and MCP-1. We also found that c9,t11-CLA inhibited ICAM-1 expression, and decreased monocyte adhesion to inflamed bronchial epithelial cells. Interestingly, c9,t11-CLA attenuated the phosphorylation of mitogen-activated protein kinase (MAPK) and down-regulated the activation of nuclear factor-κB (NF-κB). These results suggested that the anti-inflammatory effects of c9,t11-CLA were mediated by inhibiting proinflammatory cytokines, chemokines, and ICAM-1 expression by blocking NF-κB transcription regulation and by attenuating MAPK signaling pathways.

Increase of Frequency and Modulation of Phenotype of Regulatory T Cells by Atorvastatin Is Associated with Decreased Lung Inflammatory Cell Infiltration in a Murine Model of Acute Allergic Asthma

Regulatory T cells (Tregs) play an important role by controlling allergic inflammation of airways. Recently, it has been shown that statins have immunomodulatory properties, probably mediated by their effects on Tregs. Therefore, we evaluated the in vivo effect of atorvastatin (ATV) on Tregs and its association with the inflammatory process in a model of allergic asthma. BALB/c mice were sensitized with ovalbumin (OVA) and then challenged with intranasal OVA. ATV (40 mg/kg) was delivered by daily intraperitoneal injection for 7 or 15 days before each OVA challenge. ATV treatment for 7 days increased the frequency of Tregs in mediastinal lymph nodes (MLN) and the interleukin (IL)-10 in lungs. After 15 days of treatment, ATV increased the percentage of glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR+) and programmed cell death protein 1 (PD-1+) Tregs in the lung, without enhancing their suppressive activity, but also increased the percentage of conventional T cells expressing GITR+, PD1+, and OX-40 (tumor necrosis factor receptor superfamily member 4). Although no significant changes were observed in the number of inflammatory cells in the bronchoalveolar lavage (BAL), OVA-specific immunoglobulin E in the serum, and type 2 helper (Th2) cytokines in the lungs, there was a significant decrease of peribronchial inflammation that negatively correlated with the Tregs in MLN and the concentration of IL-10 in the lung. These results suggest that ATV has an immunomodulatory role possibly mediated by their effects on Tregs, which could contribute to the control of inflammation during allergic asthma. Further studies are necessary to elucidate the contribution of Treg to immunomodulatory action of statins in the context of allergic asthma.

Neutrophilic inflammation in asthma: mechanisms and therapeutic considerations

INTRODUCTION

Neutrophilic airway inflammation represents a pathologically distinct form of asthma and frequently appears in symptomatic adulthood asthmatics. However, clinical impacts and mechanisms of the neutrophilic inflammation have not been thoroughly evaluated up to date. Areas covered: Currently, distinct clinical manifestations, triggers, and molecular mechanisms of the neutrophilic inflammation (namely Toll-like receptor, Th1, Th17, inflammasome) are under investigation in asthma. Furthermore, possible role of the neutrophilic inflammation is being investigated in respect to the airway remodeling. We searched the related literatures published during the past 10 years on the website of Pub Med under the title of asthma and neutrophilic inflammation in human. Expert commentary: Epidemiologic and experimental studies have revealed that the neutrophilic airway inflammation is induced by a wide variety of stimuli including ozone, particulate matters, cigarette smoke, occupational irritants, endotoxins, microbial infection and colonization, and aeroallergens. These triggers provoke diverse immune and inflammatory responses leading to progressive and sometimes irreversible airway obstruction. Clinically, neutrophilic airway inflammation is frequently associated with severe asthma and poor response to glucocorticoid therapy, indicating the need for other treatment strategies. Accordingly, therapeutics will be targeted against the main mediators behind the underlying molecular mechanisms of the neutrophilic inflammation.

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

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

Therapeutic effects of histone deacetylase inhibitors in a murine asthma model

OBJECTIVE AND DESIGN

To investigate the therapeutic effects of various HDAC inhibitors on the development of chronic allergic airway disease in mice with airway inflammation, airway remodeling, and airway hyperresponsiveness.

SUBJECTS

Wild-type BALB/C mice (N = 72).

TREATMENT

Tubastatin A HCl [TSA, a selective histone deacetylase 6 (HDAC6) inhibitor], PCI-34051 (a selective HDAC8 inhibitor), and givinostat (a broad-spectrum HDAC inhibitor that inhibits class I and class II HDACs and several pro-inflammatory cytokines).

METHODS

Mice were divided into six groups: control, asthma, dexamethasone (positive control), TSA, PCI-34051, and givinostat (n = 12 per group). Twenty-four hours after OVA nebulization, airway hyperresponsiveness, inflammation, and remodeling were assessed.

RESULTS

The chronic asthma mouse model produced typical airway inflammation, airway remodeling, and airway hyperresponsiveness. Administration of PCI-34051 and dexamethasone reduced the eosinophilic inflammation and airway hyperresponsiveness in asthma to reduce the airway remodeling. Treatment with Tubastatin A HCl reduced airway inflammation and was associated with decreased IL-4, IL-5 and total inflammatory cell count, as well as goblet cell metaplasia and subepithelial fibrosis; however, this outcome was not as effective as that with dexamethasone. TGF-β1 expression in the cytoplasm of airway epithelium of mice in the Tubastatin A HCl group was reduced and expression of α-SMA in the airway smooth muscle was also decreased.

CONCLUSIONS

The results suggested that treatment with HDAC inhibitors can reduce airway inflammation, airway remodeling, and airway hyperresponsiveness in chronic allergic airway disease in mice.

The role of autophagy in allergic inflammation: a new target for severe asthma

Autophagy has been investigated for its involvement in inflammatory diseases, but its role in asthma has been little studied. This study aimed to explore the possible role of autophagy and its therapeutic potential in severe allergic asthma. BALB/c mice were sensitized with ovalbumin (OVA) on days 0 and 14, followed by primary OVA challenge on days 28–30. The mice received a secondary 1 or 2% OVA challenge on days 44–46. After the final OVA challenge, the mice were assessed for airway responsiveness (AHR), cell composition and cytokine levels in bronchoalveolar lavage fluid (BALF). LC3 expression in lung tissue was measured by western blot and immunofluorescence staining. Autophagosomes were detected by electron microscopy. 3-Methyladenine (3-MA) treatment and Atg5 knockdown were applied to investigate the potential role of autophagy in allergic asthma mice. AHR, inflammation in BALF and LC3 expression in lung tissue were significantly increased in the 2% OVA-challenged mice compared with the 1% OVA-challenged mice (P<0.05). In addition, eosinophils showed prominent formation of autophagosomes and increased LC3 expression compared with other inflammatory cells in BALF and lung tissue. After autophagy was inhibited by 3-MA and Atg5 shRNA treatment, AHR, eosinophilia, interleukin (IL)-5 levels in BALF and histological inflammatory findings were much improved. Finally, treatment with an anti-IL-5 antibody considerably reduced LC3 II expression in lung homogenates. Our findings suggest that autophagy is closely correlated with the severity of asthma through eosinophilic inflammation, and its modulation may provide novel therapeutic approaches for severe allergic asthma.

Simvastatin requires activation in accessory cells to modulate T-cell responses in asthma and COPD

T-cell-dependent airway and systemic inflammation triggers the progression of chronic obstructive pulmonary disease (COPD) and asthma. Retrospective studies suggest that simvastatin has anti-inflammatory effects in both diseases but it is unclear, which cell types are targeted. We hypothesized that simvastatin modulates T-cell activity. Circulating CD4+ and CD8+ T-cells, either pure, co-cultured with monocytes or alveolar macrophages (AM) or in peripheral blood mononuclear cells (PBMCs), were ex vivo activated towards Th1/Tc1 or Th2/Tc2 and incubated with simvastatin. Markers for Th1/Tc1 (IFNγ) and Th2/Tc2 (IL-5, IL-13) were measured by ELISA; with PBMCs this was done comparative between 11 healthy never-smokers, 11 current smokers without airflow limitation, 14 smokers with COPD and 11 never-smokers with atopic asthma. T-cell activation induced IFNγ, IL-5 and IL-13 in the presence and absence of accessory cells. Simvastatin did not modulate cytokine expression in pure T-cell fractions. β-hydroxy-simvastatin acid (activated simvastatin) suppressed IL-5 and IL-13 in pure Th2- and Tc2-cells. Simvastatin suppressed IL-5 and IL-13 in Th2-cells co-cultivated with monocytes or AM, which was partially reversed by the carboxylesterase inhibitor benzil. Simvastatin suppressed IL-5 production of Th2/Tc2-cells in PBMCs without differences between cohorts and IL-13 stronger in never-smokers and asthma compared to COPD. Simvastatin induced IFNγ in Th1/Tc1-cells in PBMCs of all cohorts except asthmatics. Simvastatin requires activation in accessory cells likely by carboxylesterase to suppress IL-5 and IL-13 in Th2/Tc2-cells. The effects on Il-13 are partially reduced in COPD. Asthma pathogenesis prevents simvastatin-induced IFNγ up-regulation. Simvastatin has anti-inflammatory effects that could be of interest for asthma therapy.

Urban Particulate Matter-Activated Human Dendritic Cells Induce the Expansion of Potent Inflammatory Th1, Th2, and Th17 Effector Cells

Exposure to urban particulate matter (UPM) exacerbates asthmatic lung inflammation. Lung dendritic cells (DCs) are critical for stimulating T cell immunity and in maintaining airway tolerance, but they also react to airway UPM. The adjuvant role of UPM in enhancing primary immune responses by naive cells to allergen has been reported, but the direct effects of UPM-activated DCs on the functionality of human memory CD4 T cells (Tms), which constitute the majority of T cells in the lung, has not been investigated. Blood CD1c(+) DCs were purified and activated with UPM in the presence or absence of house dust mite or tetanus toxoid control antigen. 5-(and -6)-Carboxyfluorescein diacetate succinimidyl ester-labeled blood Tms were cocultured with autologous DCs, T cell proliferation and effector function were assessed using flow cytometry, and secreted cytokines were measured by combined bead array. UPM-DCs elicited IFN-γ and IL-13 secretion and induced proliferation in Tms isolated from both allergic patients with asthma and healthy control subjects, whereas only IL-13 was produced by Tms from patients with atopic asthma stimulated by house dust mite-loaded DCs. UPM-DCs drove the expansion and differentiation of a mixed population of Th1, Th2, and Th17 cell effectors through a mechanism that was dependent on major histocompatibility class II but not on cytokine-driven expansion. The data suggest that UPM not only has adjuvant properties but is also a source of antigen that stimulates the generation of Th2, Th1, and Th17 effector phenotypes, which have been implicated in both exacerbations of asthma and chronic inflammatory diseases.

Efficacy and Safety of Benralizumab, a Monoclonal Antibody against IL-5Rα, in Uncontrolled Eosinophilic Asthma

Nonresponders to maximal guideline-based therapies of asthma account for most of the morbidity, mortality, and economic burden of the disease. Because eosinophils are key effector cells in asthmatic airway inflammation, blocking IL-5, the main cytokine responsible for its survival and activation, seems to be a rational strategy. While previous monoclonal antibodies against the IL-5 ligand resulted in inconsistent improvements in asthma outcomes, benralizumab has shown promise. Benralizumab is a monoclonal antibody against IL-5 receptor, and has an enhanced antibody dependent cell-mediated cytotoxicity function. In this article, we review the theoretical advantages of benralizumab compared to previous compounds, as well as current status of the clinical development of benralizumab in asthma. Lastly, we briefly discuss the potential role of benralizumab in chronic obstructive pulmonary disease.

Interaction Between Helminths and Toll-Like Receptors: Possibilities and Potentials for Asthma Therapy

Toll-like receptors (TLRs) are essential components of the innate immune system. They play an important role in the pathogenesis of allergic diseases, especially asthma. Since TLRs significantly orchestrate innate and adaptive immune response, their manipulation has widely been considered as a potential approach to control asthma symptoms. It is well established that helminths have immunoregulatory effects on host immune responses, especially innate immunity. They release bioactive molecules such as excretory-secretory (ES) products manipulating TLRs expression and signaling. Thus, given the promising results derived from preclinical studies, harnessing helminth-derived molecules affecting TLRs can be considered as a potential biological therapy for allergic diseases. Prospectively, the data that are available at present suggest that, in the near future, it is possible that helminth antigens will offer new therapeutic strategies and druggable targets for fighting allergic diseases. This review describes the interactions between helminths and TLRs and discusses the potential possibilities for asthma therapy. In this opinion paper, the authors aimed to review the updated literatures on the interplay between helminths, TLRs, and asthma with a view to proposing helminth-based asthma therapy.

Effect of the plant derivative Compound A on the production of corticosteroid-resistant chemokines in airway smooth muscle cells

Preclinical models of human conditions including asthma showed the therapeutic potential of Compound A (CpdA), a dissociated glucocorticoid (GC) receptor (GRα) ligand. Whether CpdA inhibits GC resistance, a central feature of severe asthma, has not been addressed. We investigated whether CpdA modulates cytokine-induced GC resistance in human airway smooth muscle (ASM) cells. Healthy and asthmatic ASM cells were treated with TNF-α/IFN-γ for 24 hours in the presence or absence of CpdA. ELISA and quantitative PCR assays were used to assess the effect of CpdA on chemokine expression. Activation of GRα by CpdA was assessed by quantitative PCR, immunostaining, and receptor antagonism using RU486. An effect of CpdA on the transcription factor interferon regulatory factor 1 (IRF-1) was investigated using immunoblot, immunostaining, and small interfering RNA (siRNA) knockdown. CpdA inhibited production of fluticasone-resistant chemokines CCL5, CX3CL1, and CXCL10 at protein and mRNA levels in both asthmatic and healthy cells. CpdA failed to induce expression of GC-induced Leucine Zipper while transiently inducing mitogen-activated protein kinase phosphatase 1 (MKP-1) at both mRNA and protein levels. CpdA inhibitory action was not associated with GRα nuclear translocation, nor was it prevented by RU486 antagonism. Activation of IRF-1 by TNF-α/IFN-γ was inhibited by CpdA. IRF-1 siRNA knockdown reduced cytokine-induced CCL5 and CX3CL1 production. siRNA MKP-1 prevented the inhibitory effect of CpdA on cytokine-induced CXCL10 production. For the first time, we show that CpdA inhibits the production of GC-resistant chemokines via GRα-independent mechanisms involving the inhibition of IRF-1 and up-regulation of MKP-1. Thus, targeting CpdA-sensitive pathways in ASM cells represents an alternative therapeutic approach to treat GC resistance in asthma.

Asthma phenotypes and IgE responses

The discovery of IgE represented a major breakthrough in allergy and asthma research, whereas the clinical interest given to IgE in asthma has been blurred until the arrival of anti-IgE biotherapy. Novel facets of the complex link between IgE and asthma have been highlighted by the effect of this treatment and by basic research. In parallel, asthma phenotyping recently evolved to the concept of endotypes, relying on identified/suspected pathobiological mechanisms to phenotype patients, but has not yet clearly positioned IgE among biomarkers of asthma.In this review, we first summarise recent knowledge about the regulation of IgE production and its main receptor, FcεRI. In addition to allergens acting as classical IgE inducers, viral infections as well as air pollution may trigger the IgE pathway, notably resetting the threshold of IgE sensitivity by regulating FcεRI expression. We then analyse the place of IgE in different asthma endo/phenotypes and discuss the potential interest of IgE among biomarkers in asthma.

Acupuncture Attenuated Inflammation and Inhibited Th17 and Treg Activity in Experimental Asthma

Acupuncture is an effective therapeutic method in asthma treatment in traditional Chinese medicine. Here, we evaluated the effect of acupuncture on airway hyperresponsiveness (AHR) and the associated inflammatory changes as well as Th17 and Treg activity in ovalbumin- (OVA-) induced experimental asthma. Our results revealed that acupuncture treatment significantly inhibited AHR, lung inflammation, and mucus secretion of experimental asthma mice. Furthermore, a decrease in lymphocytes and eosinophils as well as neutrophils was observed in bronchoalveolar lavage fluid (BALF) of mice treated with acupuncture. Acupuncture reduced the OVA specific IgE level as well as the Th17 cytokine levels including IL-17A, IL-17F, and IL-22 in the serum of the experimental asthma mice. Acupuncture treatment group also had reduced CD4+IL-17A+ cell numbers and increased CD4+Foxp3+ cell numbers in BALF. In addition, acupuncture could inhibit IL-17R, RORγt, p65, and the inhibitor of NF-κB kinase-α (IKKα) protein expression. Our results indicated that acupuncture was effective in inhibiting AHR and inflammation in OVA-induced experimental asthma, which may be associated with the regulation of Th17 and Treg activity and NF-κB pathway.

IFN-γ-induced JAK/STAT, but not NF-κB, signaling pathway is insensitive to glucocorticoid in airway epithelial cells

Although the majority of patients with asthma are well controlled by inhaled glucocorticoids (GCs), patients with severe asthma are poorly responsive to GCs. This latter group is responsible for a disproportionate share of health care costs associated with asthma. Recent studies in immune cells have incriminated interferon-γ (IFN-γ) as a possible trigger of GC insensitivity in severe asthma; however, little is known about the role of IFN-γ in modulating GC effects in other clinically relevant nonimmune cells, such as airway epithelial cells. We hypothesized that IFN-γ-induced JAK/STAT-associated signaling pathways in airway epithelial cells are insensitive to GCs and that strategies aimed at inhibiting JAK/STAT pathways can restore steroid responsiveness. Using Western blot analysis we found that all steps of the IFN-γ-induced JAK/STAT signaling pathway were indeed GC insensitive. Transfection of cells with reporter plasmid showed IFN-γ-induced STAT1-dependent gene transcription to be also GC insensitive. Interestingly, real-time PCR analysis showed that IFN-γ-inducible genes (IIGs) were differentially affected by GC, with CXCL10 being GC sensitive and CXCL11 and IFIT2 being GC insensitive. Further investigation showed that the differential sensitivity of IIGs to GC was due to their variable dependency to JAK/STAT vs. NF-κB signaling pathways with GC-sensitive IIGs being more NF-κB dependent and GC-insensitive IIGs being more JAK/STAT dependent. Importantly, transfection of cells with siRNA-STAT1 was able to restore steroid responsiveness of GC-insensitive IIGs. Taken together, our results show the insensitivity of IFN-γ-induced JAK/STAT signaling pathways to GC effects in epithelial cells and also suggest that targeting STAT1 could restore GC responsiveness in patients with severe asthma.

Double-stranded RNA evokes exacerbation in a mouse model of corticosteroid refractory asthma

RNA viruses are a major cause of respiratory infections and are known to exacerbate asthma and other respiratory diseases. Our aim was to test the ability of poly(I:C) (polyinosinic:polycytidylic acid), a viral surrogate, to elicit exacerbation in a model of severe asthma driven by HDM (house dust mite) in FCA (Freund's complete adjuvant). Poly(I:C) was administered intranasally around the HDM challenge in FCA-HDM-sensitized animals. Changes in AHR (airway hyperresponsiveness), BALF (bronchoalveolar lavage fluid) inflammatory infiltrate, HDM-specific immunoglobulins and cytokine/chemokine release were evaluated at different points after the challenge. The effect of oral dexamethasone was also assessed. Exacerbation was achieved when poly(I:C) was administered 24 h before the HDM challenge and was characterized by enhanced AHR and an increase in the numbers of neutrophils, macrophages and lymphocytes in the BALF. Th1, Th2 and Th17 cytokines were also elevated at different time points after the challenge. Peribronchial and alveolar inflammation in lung tissue were also augmented. AHR and inflammatory infiltration showed reduced sensitivity to dexamethasone treatment. We have set up a model that mimics key aspects of viral exacerbation in a corticosteroid-refractory asthmatic phenotype which could be used to evaluate new therapies for this condition.

Diagnosis of asthma - new theories

INTRODUCTION

Recent studies have shown a remarkably high frequency of poorly controlled asthma. Several reasons for this treatment failure have been discussed, however, the basic question of whether the diagnosis is always correct has not been considered. Follow-up studies have shown that in many patients asthma cannot be verified despite ongoing symptoms. Mechanisms other than bronchial obstruction may therefore be responsible. The current definition of asthma may also include symptoms that are related to mechanisms other than bronchial obstruction, the clinical hallmark of asthma.

AIM

Based on a review of the four cornerstones of asthma - inflammation, hyperresponsiveness, bronchial obstruction and symptoms - the aim was to present some new aspects and suggestions related to the diagnosis of adult non-allergic asthma.

CONCLUSION

Recent studies have indicated that "classic" asthma may sometimes be confused with asthma-like disorders such as airway sensory hyperreactivity, small airways disease, dysfunctional breathing, non-obstructive dyspnea, hyperventilation and vocal cord dysfunction. This confusion may be one explanation for the high proportion of misdiagnosis and treatment failure. The current diagnosis, focusing on bronchial obstruction, may be too "narrow". As there may be common mechanisms a broadening to include also non-obstructive disorders, forming an asthma syndrome, is suggested. Such broadening requires additional diagnostic steps, such as qualitative studies with analysis of reported symptoms, non-effort demanding methods for determining lung function, capsaicin test for revealing airway sensory hyperreactivity, careful evaluation of the therapeutic as well as diagnostic effect of corticosteroids and testing of suggested theories.

Single-cell analysis of mast cell degranulation induced by airway smooth muscle-secreted chemokines

BACKGROUND

Asthma is a chronic inflammatory disease characterized by narrowed airways, bronchial hyper-responsiveness, mucus hyper-secretion, and airway remodeling. Mast cell (MC) infiltration into airway smooth muscle (ASM) is a defining feature of asthma, and ASM regulates the inflammatory response by secreting chemokines, including CXCL10 and CCL5. Single cell analysis offers a unique approach to study specific cellular signaling interactions within large and complex signaling networks such as the inflammatory microenvironment in asthma.

METHODS

Carbon-fiber microelectrode amperometry was used to study the effects of ASM-secreted chemokines on mouse peritoneal MC degranulation.

RESULTS

MC degranulation in response to CXCL10 and CCL5 was monitored at the single cell level. Relative to IgE-mediated degranulation, CXCL10- and CCL5-stimulated MCs released a decreased amount of serotonin per granule with fewer release events per cell. Decreased serotonin release per granule was correlated with increased spike half-width and rise-time values.

CONCLUSIONS

MCs are directly activated by ASM-associated chemokines. CXCL10 and CCL5 induce less robust MC degranulation compared to IgE- and A23187-stimulation. The kinetics of MC degranulation are signaling pathway-dependent, suggesting a biophysical mechanism of regulated degranulation that incorporates control over granule trafficking, transport, and docking machinery.

GENERAL SIGNIFICANCE

The biophysical mechanisms, including variations in number of exocytotic release events, serotonin released per granule, and the membrane kinetics of exocytosis that underlie MC degranulation in response to CXCL10 and CCL5 were characterized at the single cell level. These findings clarify the function of ASM-derived chemokines as instigators of MC degranulation relative to classical mechanisms of MC stimulation.

Endurance training and the risk of bronchial asthma in female cross-country skiers

Exercise is one of the crucial factors responsible for asthma development and exacerbation. The purpose of the present study was to assess the risk of bronchial asthma in female athletes. Spirometric evaluations and physical exercise test were performed and exhaled nitric oxide (eNO) levels were measured in 12 female elite cross-country skiers. Serum concentrations of interleukin 1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and interleukin 6 (IL-6) were measured in all subjects before exercise, immediately after it, and after 15 min of recovery. Peak eNO values were 18.7±4.8 (ppb) and did not confirm the risk of early bronchial asthma symptoms. A graded exercise test caused significant increases in TNF-α and IL-1β concentration (p<0.05) after 15 min of recovery. A significant negative correlation was found between resting and post-exercise eNO and IL-6 levels (p<0.01). Our study did not confirm an increased risk of bronchial asthma or respiratory tract inflammatory conditions among female cross-country skiers exposed to physical exertion.

Parasites-allergy paradox: Disease mediators or therapeutic modulators

The noticeable phenomenon of an increased frequency of immune-inflammatory disorders, in the industrialized world, has led to the implication of parasitic infections in the pathophysiology of these diseases. Most of the studies investigated the infection connection to allergy have centered on helminthes. Parasitic helminthes are a group of metazoans that are evolutionary diverse, yet converge to evolve common modes of immunomodulation. Helminth immunoregulation is mainly mediated by a regulatory response including Treg and Breg cells with alternatively-activated macrophages. There is increasing evidence for a causal relationship between helminth infection and allergic hyporesponsiveness, however, conflicting data are still generating. The helminth immunoregulation seems to be species-specific and phase-specific. It depends on the stage of the clinical disease which correlates with a corresponding parasitic stage (egg, larva or mature adult). Here, we review the cellular and molecular mechanisms utilized by helminthes to manipulate the immune system and the consequent bystander immunomodulatory responses toward environmental allergens. We especially focus on parasitic species and molecules involved in the modulation of allergic disorders and summarize the experimental and clinical trials using them as therapeutic agents. We also discuss the potentials and obstacles, for helminthes and/or their derived molecules, to emerge as novel therapeutic modalities.

Regulation of IL-17A responses in human airway smooth muscle cells by Oncostatin M

Background

Regulation of human airway smooth muscle cells (HASMC) by cytokines contributes to chemotactic factor levels and thus to inflammatory cell accumulation in lung diseases. Cytokines such as the gp130 family member Oncostatin M (OSM) can act synergistically with Th2 cytokines (IL-4 and IL-13) to modulate lung cells, however whether IL-17A responses by HASMC can be altered is not known.

Objective

To determine the effects of recombinant OSM, or other gp130 cytokines (LIF, IL-31, and IL-6) in regulating HASMC responses to IL-17A, assessing MCP-1/CCL2 and IL-6 expression and cell signaling pathways.

Methods

Cell responses of primary HASMC cultures were measured by the assessment of protein levels in supernatants (ELISA) and mRNA levels (qRT-PCR) in cell extracts. Activation of STAT, MAPK (p38) and Akt pathways were measured by immunoblot. Pharmacological agents were used to assess the effects of inhibition of these pathways.

Results

OSM but not LIF, IL-31 or IL-6 could induce detectable responses in HASMC, elevating MCP-1/CCL2, IL-6 levels and activation of STAT-1, 3, 5, p38 and Akt cell signaling pathways. OSM induced synergistic action with IL-17A enhancing MCP-1/CCL-2 and IL-6 mRNA and protein expression, but not eotaxin-1 expression, while OSM in combination with IL-4 or IL-13 synergistically induced eotaxin-1 and MCP-1/CCL2. OSM elevated steady state mRNA levels of IL-4Rα, OSMRβ and gp130, but not IL-17RA or IL-17RC. Pharmacologic inhibition of STAT3 activation using Stattic down-regulated OSM, OSM/IL-4 or OSM/IL-13, and OSM/IL-17A synergistic responses of MCP-1/CCL-2 induction, whereas, inhibitors of Akt and p38 MAPK resulted in less reduction in MCP-1/CCL2 levels. IL-6 expression was more sensitive to inhibition of p38 (using SB203580) and was affected by Stattic in response to IL-17A/OSM stimulation.

Conclusions

Oncostatin M can regulate HASMC responses alone or in synergy with IL-17A. OSM/IL-17A combinations enhance MCP-1/CCL2 and IL-6 but not eotaxin-1. Thus, OSM through STAT3 activation of HASMC may participate in inflammatory cell recruitment in inflammatory airway disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0164-4) contains supplementary material, which is available to authorized users.

Neutrophils in asthma--a review

Asthma is a chronic inflammatory disease, with an array of cells involved in the pathogenesis of the disease. The role of neutrophils in the development of bronchial asthma is found to be complex, as they may trigger activation of immunocompetent cells and are a potent source of free oxygen radicals and enzymes participating in airway remodeling. The review highlights the role of neutrophils in bronchial asthma.