Dissociation between airway inflammation and airway hyperresponsiveness in allergic asthma

Airway hyperresponsiveness in asthma: The role of the epithelium

Airway hyperresponsiveness (AHR) is a key clinical feature of asthma. The presence of AHR in people with asthma provides the substrate for bronchoconstriction in response to numerous diverse stimuli, contributing to airflow limitation and symptoms including breathlessness, wheeze, and chest tightness. Dysfunctional airway smooth muscle significantly contributes to AHR and is displayed as increased sensitivity to direct pharmacologic bronchoconstrictor stimuli, such as inhaled histamine and methacholine (direct AHR), or to endogenous mediators released by activated airway cells such as mast cells (indirect AHR). Research in in vivo human models has shown that the disrupted airway epithelium plays an important role in driving inflammation that mediates indirect AHR in asthma through the release of cytokines such as thymic stromal lymphopoietin and IL-33. These cytokines upregulate type 2 cytokines promoting airway eosinophilia and induce the release of bronchoconstrictor mediators from mast cells such as histamine, prostaglandin D2, and cysteinyl leukotrienes. While bronchoconstriction is largely due to airway smooth muscle contraction, airway structural changes known as remodeling, likely mediated in part by epithelial-derived mediators, also lead to airflow obstruction and may enhance AHR. In this review, we outline the current knowledge of the role of the airway epithelium in AHR in asthma and its implications on the wider disease. Increased understanding of airway epithelial biology may contribute to better treatment options, particularly in precision medicine.

A Functional Bread Fermented with Saccharomyces cerevisiae UFMG A-905 Prevents Allergic Asthma in Mice

Background

The administration of probiotics has been shown to be beneficial in asthma. The administration of Saccharomyces cerevisiae UFMG A-905 prevented asthma development. Traditionally, probiotics are administered using dairy-based matrices, but other vehicles (e.g., fruit juices, biscuits, candies, and breads) can be used.

Objectives

This study aimed to assess the effect of bread fermented with S. cerevisiae UFMG A-905 in asthma prevention.

Methods

Three breads were produced: fermented with commercial yeast, fermented with S. cerevisiae UFMG A-905, and fermented with S. cerevisiae UFMG A-905 with the addition of alginate microcapsules containing live S. cerevisiae UFMG A-905. Characterization of the microbial composition of the breads was performed. Male Balb/c mice were sensitized and challenged with ovalbumin. Breads were administered 10 d before the first sensitization and during sensitization and challenge protocol. Yeast fecal count, in vivo airway hyperresponsiveness, and airway and lung inflammation were assessed.

Results

In UFMG A-905 bread, there was an increase in yeast number and a decrease in total and lactic acid bacteria. Animals that received S. cerevisiae UFMG A-905 fermented bread with microcapsules had a significant increase in yeast recovery from feces. S. cerevisiae UFMG A-905-fermented breads partially reduced airway inflammation, decreasing eosinophils and IL5 and IL13 concentrations. When adding microcapsules, the bread also diminished airway hyperresponsiveness and increased IL17A concentrations.

Conclusions

S. cerevisiae UFMG A-905 was able to generate long-fermentation breads. Microcapsules were a safe and viable way to inoculate the live yeast into food. The administration of breads fermented with S. cerevisiae UFMG A-905 prevented asthma-like characteristics, being more pronounced when the breads contained microcapsules with live yeast.

Based on what parameters is safe to discontinuate inhaled corticosteroids in children with asthma?

OBJECTIVE

Remission of childhood asthma has not been widely studied. Patients in clinical remission continue to have some degree of bronchial hyperresponsiveness (BHR). The aim of this study was to investigate whether clinical parameters and lung function test are good parameters for discontinuation of inhaled corticosteroids (ICS) in asthmatic children, including patients with persistent BHR, as measured by the methacholine challenge test (MCT).

METHODS

One year after discontinuation of inhaled corticosteroids (ICS), MCT was performed in a group of 40 asthmatic children to confirm or exclude BHR. In all patients, ICS treatment was discontinued based on the same parameters: symptoms, spirometry, daily PEF, and negative bronchodilator test. After achieving complete asthma control for at least 6 to 12 months, ICS treatment was stepped down and discontinued. Clinical course and spirometry were followed up after ICS discontinuation.

RESULTS

Positive MCT was found in 50% of the patients. There was no statistically significant difference between the positive and negative MCT groups in age at initiation and discontinuation of ICS therapy, duration of ICS therapy, duration of stepping down period, FEV1, and PEF at the time of withdrawal of ICS and one year later. ICS treatment had to be restarted in two patients from the positive MCT group, due to recurrence of asthma symptoms.

CONCLUSION

Clinical parameters, normal spirometry, daily PEF values, and a negative bronchodilator test are good parameters for discontinuing ICS treatment in asthmatic children, even in patients with persistent BHR. Children should continue to be monitored, as symptoms may recur.

The role of microRNA-185 in the pathogenesis of human diseases: A focus on cancer

MicroRNAs (miRNAs) are a widely-studied class of non-coding RNAs characterized by their short length (18-25 nucleotides). The precise functions of miRNAs are not well-elucidated; however, an increasing number of studies suggest their involvement in various physiologic processes and deregulation in pathologic conditions. miRNA-185 (miR-185) is among the mostly-studied miRNAs in human diseases, which is found to play putative roles in conditions like metabolic disorders, asthma, frailty, schizophrenia, and hepatitis. Notably, many cancer studies report the downregulation of miR-185 in cell lines, tumor tissues, and plasma specimens of patients, while it demonstrates a suppressing role on the malignant properties of cancer cells in vitro and in vivo. Accordingly, miR-185 can be considered a tumor suppressor miRNA in human malignancies, while a few studies also report inconsistent findings. Being suggested as a prognostic/diagnostic biomarker, mi-185 is also found to offer clinical potentials, particularly for early diagnosis and prediction of the prognosis of cancer patients. In this review, we have outlined the studies that have evaluated the functions and clinical significance of miR-185 in different human diseases with a particular focus on cancer.

Airway Hyperresponsiveness, but Not Bronchoalveolar Inflammatory Cytokines Profiles, Is Modified at the Subclinical Onset of Severe Equine Asthma

Airway hyperresponsiveness (AHR) and inflammation are both observed in human and equine asthma. The aim of this study was to assess the timeline and relationship of both features at the subclinical onset of severe equine asthma (SEA). First, the repeatability of the pulmonary function test (PFT) using impulse oscillometry system, and the methacholine bronchoprovocation test (BPT) were assessed at a 1-day interval on six SEA horses in clinical remission and six control horses. Then, clinical and ancillary tests were performed before and after a 1-week low-dust environmental challenge, including weighted clinical score, respiratory endoscopy, bronchoalveolar fluid cytology, PFT, and BPT. Both PFT and BPT showed acceptable repeatability. No test allowed SEA horses in clinical remission to be distinguished from control, unlike in human patients. Because of the low-dust environment, no significant difference was observed in the results of clinical and conventional ancillary examinations after the challenge. However, SEA horses showed increased AHR after the environmental challenge. At that stage, no signs of inflammation or changes in pro-inflammatory cytokines profiles (quantification and gene expression) were observed, suggesting AHR is present at an earlier stage of equine asthma than airway inflammation. This feature indicates SEA could present in a different disease pathway than neutrophilic human asthma.

The Role of Eosinophil-Derived Neurotoxin and Vascular Endothelial Growth Factor in the Pathogenesis of Eosinophilic Asthma

Asthma is a chronic complex pulmonary disease characterized by airway inflammation, remodeling, and hyperresponsiveness. Vascular endothelial growth factor (VEGF) and eosinophil-derived neurotoxin (EDN) are two significant mediators involved in the pathophysiology of asthma. In asthma, VEGF and EDN levels are elevated and correlate with disease severity and airway hyperresponsiveness. Diversity in VEGF polymorphisms results in the variability of responses to glucocorticosteroids and leukotriene antagonist treatment. Targeting VEGF and eosinophils is a promising therapeutic approach for asthma. We identified lichochalcone A, bevacizumab, azithromycin (AZT), vitamin D, diosmetin, epigallocatechin gallate, IGFBP-3, Neovastat (AE-941), endostatin, PEDF, and melatonin as putative add-on drugs in asthma with anti-VEGF properties. Further studies and clinical trials are needed to evaluate the efficacy of those drugs. AZT reduces the exacerbation rate and may be considered in adults with persistent symptomatic asthma. However, the long-term effects of AZT on community microbial resistance require further investigation. Vitamin D supplementation may enhance corticosteroid responsiveness. Herein, anti-eosinophil drugs are reviewed. Among them are, e.g., anti-IL-5 (mepolizumab, reslizumab, and benralizumab), anti-IL-13 (lebrikizumab and tralokinumab), anti-IL-4 and anti-IL-13 (dupilumab), and anti-IgE (omalizumab) drugs. EDN over peripheral blood eosinophil count is recommended to monitor the asthma control status and to assess the efficacy of anti-IL-5 therapy in asthma.

Assessing the prognostic value of respiratory oscillometry in patients with difficult-to-treat asthma

Respiratory oscillometry is widely explored in asthma management; however, there is currently no consensus on its routine work-up in patients with difficult-to-treat asthma. We conducted a retrospective, cross-sectional study involving patients with difficult-to-treat asthma at Asia University Hospital between January 2017 and October 2020. We aimed to correlate clinical significance of respiratory oscillometry and asthma treatment outcomes including symptoms control and exacerbation in patients with difficult-to-treat asthma. Among the 69 patients enrolled in the study, a total of 26.1% of the patients experienced at least one severe or two moderate exacerbations. Patients with ACT < 20 presented a higher prevalence of higher frequency-dependent resistance (FDR; the difference in resistance at 5 Hz and 20 Hz) and frequency of resonance (Fres) than those with ACT ≥ 20. In the multivariable analysis, comorbidities, COPD or allergic rhinitis, and FDR were independent factors in increasing the odds ratio in poorly controlled asthma. (FDR ≥ 0.10 vs. < 0.10, adjusted ORR = 5.05, P = 0.037) There was a higher proportion of frequent exacerbations in patients with higher FDR (FDR ≥ 0.10 vs. < 0.10 = 30.0%:20.7%), but IOS parameters failed to predict frequent exacerbations on further analysis. FDR may be a potential clinical parameter for predicting symptom control in patients with difficult-to-treat asthma.

Airway and parenchyma transcriptomics in a house dust mite model of experimental asthma

Lung transcriptomics studies in asthma have provided valuable information in the whole lung context, however, deciphering the individual contributions of the airway and parenchyma in disease pathogenesis may expedite the development of novel targeted treatment strategies. In this study, we performed transcriptomics on the airway and parenchyma using a house dust mite (HDM)-induced model of experimental asthma that replicates key features of the human disease. HDM exposure increased the expression of 3,255 genes, of which 212 were uniquely increased in the airways, 856 uniquely increased in the parenchyma, and 2187 commonly increased in both compartments. Further interrogation of these genes using a combination of network and transcription factor enrichment analyses identified several transcription factors that regulate airway and/or parenchymal gene expression, including transcription factor EC (TFEC), transcription factor PU.1 (SPI1), H2.0-like homeobox (HLX), metal response element binding transcription factor-1 (MTF1) and E74-like factor 4 (ets domain transcription factor, ELF4) involved in controlling innate immune responses. We next assessed the effects of inhibiting lung SPI1 responses using commercially available DB1976 and DB2313 on key disease outcomes. We found that both compounds had no protective effects on airway inflammation, however DB2313 (8 mg/kg) decreased mucus secreting cell number, and both DB2313 (1 mg/kg) and DB1976 (2.5 mg/kg and 1 mg/kg) reduced small airway collagen deposition. Significantly, both compounds decreased airway hyperresponsiveness. This study demonstrates that SPI1 is important in HDM-induced experimental asthma and that its pharmacological inhibition reduces HDM-induced airway collagen deposition and hyperresponsiveness.

Peribronchial Inflammation Resulting from Regulatory T Cell Deficiency Damages the Respiratory Epithelium and Disturbs Barrier Function

Regulatory T cells (Tregs) that express the transcription factor Foxp3 have a critical role in limiting inflammatory processes and tissue damage. Whether Tregs are functional in maintaining epithelial barriers and in control of tight junction expression has not yet been explored. In this study, we investigated the effect of Treg deficiency on the airway epithelial barrier in an experimental murine model in which diphtheria toxin was repeatedly injected in Foxp3-diphtheria toxin receptor (DTR) mice to deplete Tregs. This resulted in spontaneous peribronchial inflammation and led to a systemic and local increase of IL-4, IL-5, CCL3, IFN-γ, and IL-10 and a local (lung) increase of IL-6 and IL-33 and decreased amphiregulin levels. Moreover, Treg depletion increased airway permeability and decreased epithelial tight junction (protein and mRNA) expression. CTLA4-Ig treatment of Treg-depleted mice almost completely prevented barrier dysfunction together with suppression of lung inflammation and cytokine secretion. Treatment with anti–IL-4 partly reversed the effects of Treg depletion on tight junction expression, whereas neutralization of IL-6 of IFN-γ had either no effect or only a limited effect. We conclude that Tregs are essential to protect the epithelial barrier at the level of tight junctions by restricting spontaneous T cell activation and uncontrolled secretion of cytokines, in particular IL-4, in the bronchi.

Chlorine exposure and intensive exercise induces airway hyperreactivity in a 3-week murine exercise model

RATIONALE

Exercise-induced bronchoconstriction (EIB) is defined as acute narrowing of the airways during or immediately after exercise. EIB has a high prevalence in elite swimmers probably due to the high ventilation rate and exposure to the chlorine by-products. It is still puzzling which pathophysiological mechanisms drive EIB.

OBJECTIVE

In this study, we evaluated airway hyperreactivity, permeability, integrity and inflammation in a murine swimmers EIB model with and without chlorine exposure.

METHODS

Mice performed a 3-week swimming protocol in a swimming pool with counter current. Three hours after the last swimming session, airway hyperreactivity to methacholine was assessed. Cytokine levels and cellular differential analysis was performed in BAL fluid. Airway permeability and tight junction expression was measured in serum and lung tissue. T-, B-, dendritic and innate lymphoid cells were determined in lung tissue via flow cytometry.

RESULTS

A significant higher airway resistance (Rn; P < 0.0001) was observed in mice swimming in chlorinated water (mean Rn = 1.26 cmH₂O.s/ml) compared to mice swimming in tap water (mean Rn = 0.76 cmH₂O.s/ml) and both inhalation groups in the absence of cellular inflammation. No significant differences were found in lung immune cell populations or in lung tight junction mRNA expression. Experiments in SCID, Rag2^-/-γc^-/- or Cpa3^cre/+ mice showed a limited involvement of the innate, adaptive immune system or the mast cells.

CONCLUSION

Our 3-week swimming murine model mimics intensive swimming in chlorinated water with the presence of airway hyperreactivity in mice swimming in chlorinated water in the absence of airway inflammation and airway epithelial damage.

Critical evaluation of asthma biomarkers in clinical practice

The advent of personalized medicine has revolutionized the whole approach to the management of asthma, representing the essential basis for future developments. The cornerstones of personalized medicine are the highest precision in diagnosis, individualized prediction of disease evolution, and patient-tailored treatment. To this aim, enormous efforts have been established to discover biomarkers able to predict patients' phenotypes according to clinical, functional, and bio-humoral traits. Biomarkers are objectively measured characteristics used as indicators of biological or pathogenic processes or clinical responses to specific therapeutic interventions. The diagnosis of type-2 asthma, prediction of response to type-2 targeted treatments, and evaluation of the risk of exacerbation and lung function impairment have been associated with biomarkers detectable either in peripheral blood or in airway samples. The surrogate nature of serum biomarkers, set up to be less invasive than sputum analysis or bronchial biopsies, has shown several limits concerning their clinical applicability. Routinely used biomarkers, like peripheral eosinophilia, total IgE, or exhaled nitric oxide, result, even when combined, to be not completely satisfactory in segregating different type-2 asthma phenotypes, particularly in the context of severe asthma where the choice among different biologics is compelling. Moreover, the type-2 low fraction of patients is not only an orphan of biological treatments but is at risk of being misdiagnosed due to the low negative predictive value of type-2 high biomarkers. Sputum inflammatory cell analysis, considered the highest specific biomarker in discriminating eosinophilic inflammation in asthma, and therefore elected as the gold standard in clinical trials and research models, demonstrated many limits in clinical applicability. Many factors may influence the measure of these biomarkers, such as corticosteroid intake, comorbidities, and environmental exposures or habits. Not least, biomarkers variability over time is a confounding factor leading to wrong clinical choices. In this narrative review, we try to explore many aspects concerning the role of routinely used biomarkers in asthma, applying a critical view over the "state of the art" and contemporarily offering an overview of the most recent evidence in this field.

Neuropilin‐2 regulates airway inflammation in a neutrophilic asthma model

Background

Asthma is a heterogenous disease that can be classified into eosinophilic (type 2‐high) and noneosinophilic (type 2‐low) endotypes. The type 2‐low endotype of asthma can be characterized by the presence of neutrophilic airway inflammation that is poorly responsive to corticosteroids. Dysregulated innate immune responses to microbial products including Toll‐like receptor (TLR) ligands have been associated with the pathogenesis of neutrophilic asthma. The key molecules that regulate inflammatory responses in individuals with neutrophilic asthma remain unclear. We previously reported that the immunoregulatory receptor neuropilin‐2 (NRP2) is expressed by murine and human alveolar macrophage (AM) and suppresses lipopolysaccharide (LPS)‐induced neutrophilic airway inflammation.

Methods

Here, we investigated the immunoregulatory role of NRP2 in a mouse model of neutrophilic asthma.

Results

We found that TLR ligands, but not T helper 2 (Th2)‐promoting adjuvants, induced NRP2 expression by AM. Using an LPS‐mediated model of neutrophilic asthma, we demonstrate that NRP2 was increased in AM and other lung antigen‐presenting cells following airway challenge with antigen. Conditional deletion of NRP2 in myeloid cells exacerbated airway inflammation in a neutrophilic asthma model. In contrast, myeloid‐specific ablation of NRP2 did not affect airway inflammation in a Th2‐mediated eosinophilic asthma model. Myeloid‐specific ablation of NRP2 did not affect Th1/Th17 responses to inhaled antigens or expression of neutrophil chemokines but rather resulted in impaired efferocytosis by AM, which is necessary for effective resolution of airway inflammation.

Conclusion

Our findings suggest that NRP2 is a negative regulator of airway inflammation associated with neutrophilic asthma.

Dual role for CXCR3 and CCR5 in asthmatic type 1 inflammation

BACKGROUND

Many patients with severe asthma (SA) fail to respond to type 2 inflammation-targeted therapies. We previously identified a cohort of subjects with SA expressing type 1 inflammation manifesting with IFN-γ expression and variable type 2 responses.

OBJECTIVE

We investigated the role of the chemotactic receptors C-X-C chemokine receptor 3 (CXCR3) and C-C chemokine receptor 5 (CCR5) in establishing type 1 inflammation in SA.

METHODS

Bronchoalveolar lavage microarray data from the Severe Asthma Research Program I/II were analyzed for pathway expression and paired with clinical parameters. Wild-type, Cxcr3-/-, and Ccr5-/- mice were exposed to a type 1-high SA model with analysis of whole lung gene expression and histology. Wild-type and Cxcr3-/- mice were treated with a US Food and Drug Administration-approved CCR5 inhibitor (maraviroc) with assessment of airway resistance, inflammatory cell recruitment by flow cytometry, whole lung gene expression, and histology.

RESULTS

A cohort of subjects with increased IFN-γ expression showed higher asthma severity. IFN-γ expression was correlated with CXCR3 and CCR5 expression, but in Cxcr3-/- and Ccr5-/- mice type 1 inflammation was preserved in a murine SA model, most likely owing to compensation by the other pathway. Incorporation of maraviroc into the experimental model blunted airway hyperreactivity despite only mild effects on lung inflammation.

CONCLUSIONS

IFNG expression in asthmatic airways was strongly correlated with expression of both the chemokine receptors CXCR3 and CCR5. Although these pathways provide redundancy for establishing type 1 lung inflammation, inhibition of the CCL5/CCR5 pathway with maraviroc provided unique benefits in reducing airway hyperreactivity. Targeting this pathway may be a novel approach for improving lung function in individuals with type 1-high asthma.

Role of miR-185-5p as modulator of periostin synthesis and smooth muscle contraction in asthma

Asthma is a chronic respiratory disease produced by an aberrant immune response that originates with breathing difficulties and cough, through airway remodeling. The above pathophysiological events of asthma emerge the regulators of effectors, like epigenetics, which include microRNAs (miRNAs) who perform post‐transcriptional regulation, controlling diverse pathways in respiratory diseases. The objective of the study was to determine how miR‐185‐5p regulates the secretion of periostin by airway structural cells, and smooth muscle cells contraction, both related to airway remodeling in asthma. We used miR‐185‐5p mimic and inhibitors in bronchial smooth muscle cells (BSMCs) and small airway epithelial cells (SAECs) from healthy subjects. Gene expression and protein levels of periostin (POSTN), CDC42, and RHOA were analyzed by RT‐PCR and ELISA/Western blot, respectively. BSMC contractility was analyzed using cell‐embedded collagen gels and measurement of intracellular calcium was performed using Fura‐2. Additionally, miR‐185‐5p and periostin expression were evaluated in sputum from healthy and asthmatics. From these experiments, we observed that miR‐185‐5p modulation regulates periostin mRNA and protein in BSMCs and SAECs. A tendency for diminished miR‐185‐5p expression and higher periostin levels was seen in sputum cells from asthmatics compared to healthy, with an inverse correlation observed between POSTN and miR‐185‐5p. Inhibition of miR‐185‐5p produced higher BSMCs contraction induced by histamine. Calcium mobilization was not modified by miR‐185‐5p, showing that miR‐185‐5p role in BSMC contractility is performed by regulating CDC42 and RhoA pro‐contractile factors instead. In conclusion, miR‐185‐5p is a modulator of periostin secretion by airway structural cells and of smooth muscle contraction, which can be related to asthma pathophysiology, and thus, might be a promising therapeutic target.

Asthma in the Precision Medicine Era: Biologics and Probiotics

Asthma is a major global health issue. Over 300 million people worldwide suffer from this chronic inflammatory airway disease. Typical clinical symptoms of asthma are characterized by a recurrent wheezy cough, chest tightness, and shortness of breath. The main goals of asthma management are to alleviate asthma symptoms, reduce the risk of asthma exacerbations, and minimize long-term medicinal adverse effects. However, currently available type 2 T helper cells (Th2)-directed treatments are often ineffective due to the heterogeneity of the asthma subgroups, which manifests clinically with variable and poor treatment responses. Personalized precision therapy of asthma according to individualized clinical characteristics (phenotype) and laboratory biomarkers (endotype) is the future prospect. This mini review discusses the molecular mechanisms underlying asthma pathogenesis, including the hot sought-after topic of microbiota, add-on therapies and the potential application of probiotics in the management of asthma.

IRAK-M knockout promotes allergic airway inflammation, but not airway hyperresponsiveness, in house dust mite-induced experimental asthma model

Background

IL-1 receptor associated-kinase (IRAK)-M, expressed by airway epithelium and macrophages, was shown to regulate acute and chronic airway inflammation exhibiting a biphasic response in an OVA-based animal model. House dust mite (HDM) is a common real-life aeroallergen highly relevant to asthma pathogenesis. The role of IRAK-M in HDM-induced asthma remains unknown. This study was aimed to investigate the effect of IRAK-M on allergic airway inflammation induced by HDM using IRAK-M knockout (KO) mice and the potential underlying mechanisms.

Methods

IRAK-M KO and wild-type (WT) mice were sensitized and challenged with HDM. The differences in airway inflammation were evaluated 24 hours after the last challenge between the two genotypes of mice using a number of cellular and molecular biological techniques. In vitro mechanistic investigation was also involved.

Results

Lung expression of IRAK-M was significantly upregulated by HDM in the WT mice. Compared with the WT controls, HDM-treated IRAK-M KO mice showed exacerbated infiltration of inflammatory cells, particularly Th2 cells, in the airways and mucus overproduction, higher epithelial mediators IL-25, IL-33 and TSLP and Th2 cytokines in bronchoalveolar lavage (BAL) fluid. Lung IRAK-M KO macrophages expressed higher percentage of costimulatory molecules OX40L and CD 80 and exhibited enhanced antigen uptake. However, IRAK-M KO didn’t impact the airway hyperreactivity (AHR) indirectly induced by HDM.

Conclusions

The findings indicate that IRAK-M protects allergic airway inflammation, not AHR, by modifying activation and antigen uptake of lung macrophages following HDM stimulation. Optimal regulation of IRAK-M might indicate an intriguing therapeutic avenue for allergic airway inflammation.

A snapshot of exhaled nitric oxide and asthma characteristics: experience from high to low income countries

Nitric oxide is a gas produced in the airways of asthmatic subjects and related to T2 inflammation. It can be measured as fractional nitric oxide (FeNO) in the exhaled air and used as a non-invasive, easy to evaluate, rapid marker. It is now widely used in many settings to determine airway inflammation. The aim of this narrative review is to report relationship between FeNO and the physiopathologic characteristics of asthmatic patients. Factors affecting FeNO levels have also been analysed as well as the impact of corticosteroid, target therapies and rehabilitation programs. Considering the availability of the test, spreading this methodology to low income countries has also been considered as a possibility for evaluating airway inflammation and monitoring adherence to inhaled corticosteroid therapy. PubMed data search has been performed restricted to English language papers. Research was limited to studies in adults unless studies in children were the only ones reported for a particular issue. This revision could be useful to summarize the role of FeNO in relation to asthma characteristics and help in the use of FeNO in different clinical settings particularly in low income countries.

Pequi (Caryocar brasiliense Cambess)-Loaded Nanoemulsion, Orally Delivered, Modulates Inflammation in LPS-Induced Acute Lung Injury in Mice

Pequi is a Brazilian fruit used in folk medicine for pulmonary diseases treatment, but its oil presents bioavailability limitations. The use of nanocarriers can overcome this limitation. We developed nanoemulsions containing pequi oil (pequi-NE) and evaluated their effects in a lipopolysaccharide (LPS)-induced lung injury model. Free pequi oil or pequi-NE (20 mg/kg) was orally administered to A/J mice 16 and 4 h prior to intranasal LPS exposure, and the analyses were performed 24 h after LPS provocation. The physicochemical results revealed that pequi-NE comprised particles with mean diameter of 174–223 nm, low polydispersity index (0.11 ± 0.01), zeta potential of −7.13 ± 0.08 mV, and pH of 5.83 ± 0.12. In vivo evaluation showed that free pequi oil pretreatment reduced the influx of inflammatory cells into bronchoalveolar fluid (BALF), while pequi-NE completely abolished leukocyte accumulation. Moreover, pequi-NE, but not free pequi oil, reduced myeloperoxidase (MPO), TNF-α, IL-1β, IL-6, MCP-1, and KC levels. Similar anti-inflammatory effects were observed when LPS-exposed animals were pre-treated with the nanoemulsion containing pequi or oleic acid. These results suggest that the use of nanoemulsions as carriers enhances the anti-inflammatory properties of oleic acid-containing pequi oil. Moreover, pequi’s beneficial effect is likely due its high levels of oleic acid.

Exercise and Asthma

Asthma is a chronic lower respiratory disease that is very common worldwide, and its incidence is increasing year by year. Since the 1970s, asthma has become widespread, with approximately 300 million people affected worldwide and about 250,000 people have lost their lives. Asthma seriously affects people's physical and mental health, resulting in reduced learning efficiency, limited physical activities, and decreased quality of life. Therefore, raising awareness of the risk of asthma and how to effectively treat asthma have become important targets for the prevention and management of asthma in recent years. For patients with asthma, exercise training is a widely accepted adjunct to drug-based and non-pharmacological treatment. It has been recommended abroad that exercise prescriptions are an important part of asthma management.

Searching for Inflammatory and Oxidative Stress Markers Capable of Clustering Severe Asthma

OBJECTIVE

Asthma inflammation may feature an imbalance between oxidative stress and antioxidant defenses. Oxidative stress induces propagation of airways inflammation and corticosteroid insensitivity contributing to poor asthma control, and frequent severe acute exacerbations. This study assessed inflammation and oxidative stress in severe asthmatic subjects and evaluated the possible correlations between inflammatory and oxidative stress markers investigated and asthma severity.

MATERIAL AND METHOD

Fifty-three patients with severe asthma, 11 patients with mild-moderate asthma and 12 healthy subjects were enrolled and underwent fractional exhaled nitric oxide (FENO) analysis and blood and sputum count cell collection. The content of mitochondrial DNA (MtDNA) and nuclear DNA (nDNA) was measured in exhaled breath condensate (EBC) by Real Time PCR and the ratio between MtDNA/nDNA was calculated. We detected MtDNA/nDNA in the EBC of severe asthmatics.

RESULTS

We found higher exhaled MtDNA/nDNA in severe asthmatics respectively compared to mild-moderate ones and to healthy controls (10.4±2.2 vs 7.9±2.5, p<0.05 and 10.4±2.2 vs 6.51±0.21, p<0.05). The level of exhaled MtDNA/nDNA was significantly higher in Non-T2 endotype severe asthmatics than T2 (14.07±10. 8 vs 6.5±5.5, p<0.05).

CONCLUSION

Oxidative stress marker (MtDNA/nDNA) is increased significantly with asthma severity and may be useful for endotyping severe asthma.

Serum Eosinophil-Derived Neurotoxin Better Reflect Asthma Control Status Than Blood Eosinophil Counts

BACKGROUND

Although several biomarkers have been proposed for eosinophilic asthma, biomarkers for reflecting asthma control status remain controversial. Eosinophil-derived neurotoxin (EDN), a degranulated eosinophil protein, is an emerging biomarker in asthmatic patients.

OBJECTIVE

This study analyzed serum EDN concentrations in asthmatics and compared its performance with that of blood eosinophil count as an indicator of asthma control status.

METHODS

We enrolled 75 uncontrolled asthmatics, 56 controlled asthmatics, and 43 healthy controls from Asan Medical Center. Serum EDN levels (ng/mL) were measured using an enzyme-linked immunosorbent assay kit. The predictability of EDN for asthma control status was analyzed by univariate and multivariable logistic regression analyses. A receiver operating characteristic (ROC) curve analysis was conducted to compare the performances of a serum EDN level and blood eosinophil count as indicators of uncontrolled asthma status.

RESULTS

The mean serum EDN level in the uncontrolled asthma group was higher than that in the controlled asthma and healthy groups (103.2 ± 60.2 vs 60.8 ± 49.7 vs 49.6 ± 28.3 ng/mL, P < .001). Serum EDN level was the significant parameter related to asthma control status in univariate and multivariable analysis (both P < .001). Serum EDN levels correlated with blood eosinophil counts (r = 0.510, P < .001). However, in the ROC analysis, serum EDN level showed a significantly better performance for predicting uncontrolled asthma status (area under the curve, 0.726 vs 0.628, P = .024).

CONCLUSIONS

Serum EDN levels significantly differed between patients with controlled and uncontrolled status in adult asthmatics. To our knowledge, this is the first study to identify EDN as a better indicator of asthma control status than blood eosinophil count.

Exploring the role of nerves in asthma; insights from the study of cough

Cough in asthma predicts disease severity, prognosis, and is a common and troublesome symptom. Cough is the archetypal airway neuronal reflex, yet little is understood about the underlying neuronal mechanisms. It is generally assumed that symptoms arise because of airway hyper-responsiveness and/or airway inflammation, but despite using inhaled corticosteroids and bronchodilators targeting these pathologies, a large proportion of patients have persistent coughing. This review focuses on the prevalence and impact of cough in asthma and explores data from pre-clinical and clinical studies which have explored neuronal mechanisms of cough and asthma. We present evidence to suggest patients with asthma have evidence of neuronal dysfunction, which is further heightened and exaggerated by both bronchoconstriction and airway eosinophilia. Identifying patients with excessive coughing with asthma may represent a neuro-phenotype and hence developing treatment for this symptom is important for reducing the burden of disease on patients' lives and currently represents a major unmet clinical need.

The Role of Airway Myofibroblasts in Asthma

Airway remodeling is a characteristic feature of asthma and is thought to play an important role in the pathogenesis of airway hyperresponsiveness. Myofibroblasts are key structural cells involved in injury and repair, and there is evidence that dysregulation of their normal function contributes to airway remodeling. Despite the importance of myofibroblasts, a lack of specific cellular markers and inconsistent nomenclature have limited recognition of their key role in airway remodeling. Myofibroblasts are increased several-fold in the airways in asthma, in proportion to the severity of the disease. Myofibroblasts are postulated to be derived from both tissue-resident and bone marrow-derived cells, depending on the stage of injury and the tissue. A small number of studies have demonstrated attenuation of myofibroblast numbers and also reversal of established myofibroblast populations in asthma and other inflammatory processes. In this article, we review what is currently known about the biology of myofibroblasts in the airways in asthma and identify potential targets to reduce or reverse the remodeling process. However, further translational research is required to better understand the mechanistic role of the myofibroblast in asthma.

Severe asthma phenotypes and endotypes

Current management of severe asthma relying either on guidelines (bulk approach) or on disease phenotypes (stratified approach) did not improve the burden of the disease. Several severe phenotypes are described: clinical, functional, morphological, inflammatory, molecular and microbiome-related. However, phenotypes do not necessarily relate to or give insights into the underlying pathogenetic mechanisms which are described by the disease endotypes. Based on the major immune-inflammatory pathway involved type-2 high, type-2 low and mixed endotypes are described for severe asthma, with several shared pathogenetic pathways such as genetic and epigenetic, metabolic, neurogenic and remodelling subtypes. The concept of multidimensional endotyping as un unbiased approach to severe asthma is discussed, together with new tools and targets facilitating the shift from the stratified to the precision medicine approach.

Comparison of serum eosinophil-derived neurotoxin levels between wheezing and non-wheezing groups in children with respiratory tract infection

Objective: Eosinophil-derived neurotoxin (EDN) is associated with recurrent wheezing episodes after bronchiolitis, childhood asthma, and allergic rhinitis. We investigated if there is a measurable difference between serum EDN levels in children with wheezing and non-wheezing respiratory infections.Methods: 171 children who visited a university hospital with respiratory infections were enrolled in the study. Subjects were divided into two groups: wheezing (n = 46) and non-wheezing (n = 125). Serum EDN levels were compared.Results: Serum EDN levels in the wheezing group were significantly higher than in the non-wheezing group (P < 0.001). The non-wheezing group was divided into three sub-groups: pneumonia, common cold, and tonsillitis. Serum EDN levels in the wheezing group were significantly higher than in the pneumonia, common cold, or tonsillitis subgroups (P < 0.001). There was no significant difference in serum EDN levels among the pneumonia, common cold, and tonsillitis subgroups.Conclusions: These findings suggest that elevated serum EDN levels could be a distinctive feature of respiratory infections with wheezing. EDN's utility as a biomarker for wheezing-associated disease should be explored through further study.

Effectiveness of pulmonary rehabilitation in severe asthma: a retrospective data analysis

Background: Pulmonary Rehabilitation (PR) is a multimodal treatment that is still poorly investigated in severe asthma where respiratory symptoms remain "uncontrolled" despite intensive pharmacological therapy. Bronchiectasis and obstructive sleep apnea (OSAS) are common comorbidities which may worsen asthma control.Aim: Aim of the present study is to investigate the effectiveness of PR on functional exercise, dyspnea, and muscle fatigue in patients with severe asthma.Methods: A total of 317 patients affected from severe asthma according to GINA guidelines who underwent a multidisciplinary 3 weeks rehabilitation program with an adherence of >80% to PR and able to complete a Six Minute Walking Test (6MWT) were retrospectively included in the analysis. Pulmonary rehabilitation included endurance training, educational meetings, chest physiotherapy, breathing exercises, and psychological support. Six-minute walking distance and Borg scale for dyspnea and muscle fatigue were recorded before and after the rehabilitation.Results: A total of 371 patients were analyzed, 39 had bronchiectasis (10.5%), 163 (43.9%) OSAS and 17 had both (4.6%). PR significantly improved 6MWT distance, Borg dyspnea and muscle fatigue (p value < 0.0001 for all outcomes) and mean SpO2 recorded during 6MWT (p value < 0.0001). Median (IQR) delta 6 minute walking distance was 33 (14-60) m. 6MWT distance (p < 0.0001) and the oxygen saturation (p < 0.01) significantly improved in severe asthma with bronchiectasis and/or OSAS.Conclusions: Our study provides evidence for the first time on a large sample of patients with severe asthma that a multidisciplinary PR program is effective in terms of exercise capacity and symptoms. In addition, exercise capacity improved in the presence of bronchiectasis and/or OSAS.

Bronchoprovocation Testing in Asthma: An Update

Bronchial hyperresponsiveness (BHR) is defined as a heightened bronchoconstrictive response to airway stimuli. It complements the cardinal features in asthma, such as variable or reversible airflow limitation and airway inflammation. Although BHR is considered a pathophysiologic hallmark of asthma, it should be acknowledged that this property of the airway is dynamic, because its severity and even presence can vary over time with disease activity, triggers or specific exposure, and with treatment. In addition, it is important to recognize that there is a component that is not reflective of a specific disease entity.

Cytokines and Chemokines as Biomarkers of Future Asthma

Antenatal and preschool factors are key in determining the progression to pre-school wheeze and eosinophilic school age asthma. The conventional view of eosinophilic asthma is that airway inflammation is the fundamental underlying abnormality, and airway inflammation and hyper-responsiveness are secondary; in fact, these three are parallel processes. Very early structural changes, independent of inflammation and infection, are associated with early airway hyper-responsiveness and later adverse respiratory outcomes. There is a bidirectional relationship between structural airway wall changes and airway inflammation, with airway contraction per se leading to the release of growth factors, and inflammatory pathways promoting airway remodeling. Early viral infection (and increasingly being appreciated, bacterial infection) is important in wheeze outcomes. There is evidence of abnormal immune function including cytokine release before the onset of viral infections. However, viral infections may also have prolonged effects on the host immune system, and the evidence for beneficial and adverse effects of viral infection is conflicting. In older children and adults, asthmatic epithelial cells show impaired interferon responses to viral infection, but only in the presence of uncontrolled type 2 inflammation, implying these are secondary phenomena. There are also compelling data relating the innate immune system to later asthma and atopy, and animal studies suggest that the effects of a high endotoxin, microbiologically diverse environment may be modulated via the epithelial alarmin IL-33. Whereas, previously only viral infection was thought to be important, early bacterial colonization of the upper airway is coming to the fore, associated with a mixed pattern of TH1/TH2/TH17 cytokine secretion, and adverse long term outcomes. Bacterial colonization is probably a marker of a subtle immune deficiency, rather than directly causal. The airway and gut microbiome critically impacts the development of Type 2 inflammatory responses. However, Type 2 inflammatory cytokines, which are critical both to progression from pre-school wheeze to eosinophilic asthma, and sustaining the eosinophilic asthmatic state, are not implicated in the very early development of the disease. Taken together, the evidence is that the earliest cytokine and chemokine signals will come from the study of bronchial epithelial cell function and their interactions with viruses and the microbiome.

Pathophysiological Mechanisms of Asthma

The recent Lancet commission has highlighted that "asthma" should be used to describe a clinical syndrome of wheeze, breathlessness, chest tightness, and sometimes cough. The next step is to deconstruct the airway into components of fixed and variable airflow obstruction, inflammation, infection and altered cough reflex, setting the airway disease in the context of extra-pulmonary co-morbidities and social and environmental factors. The emphasis is always on delineating treatable traits, including variable airflow obstruction caused by airway smooth muscle constriction (treated with short- and long-acting β-2 agonists), eosinophilic airway inflammation (treated with inhaled corticosteroids) and chronic bacterial infection (treated with antibiotics with benefit if it is driving the disease). It is also important not to over-treat the untreatable, such as fixed airflow obstruction. These can all be determined using simple, non-invasive tests such as spirometry before and after acute administration of a bronchodilator (reversible airflow obstruction); peripheral blood eosinophil count, induced sputum, exhaled nitric oxide (airway eosinophilia); and sputum or cough swab culture (bacterial infection). Additionally, the pathophysiology of risk domains must be considered: these are risk of an asthma attack, risk of poor airway growth, and in pre-school children, risk of progression to eosinophilic school age asthma. Phenotyping the airway will allow more precise diagnosis and targeted treatment, but it is important to move to endotypes, especially in the era of increasing numbers of biologicals. Advances in -omics technology allow delineation of pathways, which will be particularly important in TH2 low eosinophilic asthma, and also pauci-inflammatory disease. It is very important to appreciate the difficulties of cluster analysis; a patient may have eosinophilic airway disease because of a steroid resistant endotype, because of non-adherence to basic treatment, and a surge in environmental allergen burden. Sophisticated -omics approaches will be reviewed in this manuscript, but currently they are not being used in clinical practice. However, even while they are being evaluated, management of the asthmas can and should be improved by considering the pathophysiologies of the different airway diseases lumped under that umbrella term, using simple, non-invasive tests which are readily available, and treating accordingly.

Resveratrol Attenuates Allergic Asthma and Associated Inflammation in the Lungs Through Regulation of miRNA-34a That Targets FoxP3 in Mice

Asthma is a chronic inflammatory disease of airways mediated by T-helper 2 (Th2) cells involving complex signaling pathways. Although resveratrol has previously been shown to attenuate allergic asthma, the role of miRNA in this process has not been studied. We investigated the effect of resveratrol on ovalbumin-induced experimental allergic asthma in mice. To that end, BALB/c mice were immunized with ovalbumin (OVA) intraperitoneally followed by oral gavage of vehicle (OVA-veh) or resveratrol (100 mg/kg body) (OVA-res). On day 7, the experimental groups received intranasal challenge of OVA followed by 7 days of additional oral gavage of vehicle or resveratrol. At day 15, all mice were euthanized and bronchioalveolar fluid (BALF), serum and lung infiltrating cells were collected and analyzed. The data showed that resveratrol significantly reduced IL-5, IL-13, and TGF-β in the serum and BALF in mice with OVA-induced asthma. Also, we saw a decrease in CD3+CD4+, CD3+CD8+, and CD4+IL-4+ cells with increase in CD4+CD25+FOXP3+ cells in pulmonary inflammatory cell infiltrate in OVA-res group when compared to OVA-veh. miRNA expression arrays using lung infiltrating cells showed that resveratrol caused significant alterations in miRNA expression, specifically downregulating the expression of miR-34a. Additionally, miR-34a was found to target FOXP3, as evidenced by enhanced expression of FOXP3 in the lung tissue. Also, transfection studies showed that miR-34a inhibitor upregulated FOXP3 expression while miR-34a-mimic downregulated FOXP3 expression. The current study suggests that resveratrol attenuates allergic asthma by downregulating miR-34a that induces increased expression of FOXP3, a master regulator of Treg development and functions.

Bronchoalveolar lavage fluid cytology and airway hyper-reactivity in clinically normal horses

OBJECTIVE

To characterise the relationship between bronchoalveolar lavage fluid (BALF) cytology and pulmonary function testing with histamine bronchoprovocation (HBP) methods in a population of clinically normal horses.

DESIGN

Cross-sectional study METHODS: Clinically normal adult horses (n = 33) underwent pulmonary function testing and HBP with a commercial flowmetric plethysmography system. BAL was performed 1-5 days later. Statistical analysis was used to assess associations between BALF cell concentration, relative inflammatory cell percentages and categorisation, and airway hyper-reactivity (AHR).

RESULTS

AHR (PC₃₅  ≤ 8 mg/mL) was demonstrated in 17 (52%) of the horses. Using current definitions, BALF cytology was consistent with inflammatory airway disease in 14 (42%) of the horses and 7 of those demonstrated either mastocytic and/or eosinophilic responses. There was no correlation between total inflammatory cell counts or relative percentage and AHR. No statistical association was found between BALF inflammatory cell categories and AHR.

CONCLUSION

A direct association between cytological evidence of airway inflammation and AHR was not identified in this population of clinically normal horses. Determining the presence and measuring inflammatory cell mediators in BALF may more accurately reflect AHR. In addition, normal values for cell proportions in BALF may vary between different populations of horses and more appropriate regional reference ranges should be established.

Kininogen deficiency or depletion reduces enhanced pause independent of pulmonary inflammation in a house dust mite-induced murine asthma model

High-molecular-weight kininogen is an important substrate of the kallikrein-kinin system. Activation of this system has been associated with aggravation of hallmark features in asthma. We aimed to determine the role of kininogen in enhanced pause (Penh) measurements and lung inflammation in a house dust mite (HDM)-induced murine asthma model. Normal wild-type mice and mice with a genetic deficiency of kininogen were subjected to repeated HDM exposure (sensitization on days 0, 1, and 2; challenge on days 14, 15, 18, and 19) via the airways to induce allergic lung inflammation. Alternatively, kininogen was depleted after HDM sensitization by twice-weekly injections of a specific antisense oligonucleotide (kininogen ASO) starting at day 3. In kininogen-deficient mice HDM induced in Penh was completely prevented. Remarkably, kininogen deficiency did not modify HDM-induced eosinophil/neutrophil influx, T helper 2 responses, mucus production, or lung pathology. kininogen ASO treatment started after HDM sensitization reduced plasma kininogen levels by 75% and reproduced the phenotype of kininogen deficiency: kininogen ASO administration prevented the HDM-induced increase in Penh without influencing leukocyte influx, Th2 responses, mucus production, or lung pathology. This study suggests that kininogen could contribute to HDM-induced rise in Penh independently of allergic lung inflammation. Further research is warranted to confirm these data using invasive measurements of airway responsiveness.

Exhaled breath profiling by electronic nose enabled discrimination of allergic rhinitis and extrinsic asthma

AIM

To assess whether an e-nose could discriminate between subjects affected by allergic rhinitis with and without concomitant extrinsic asthma, as well as from healthy controls, in terms of exhaled VOC-profile.

METHODS

Fourteen patients with Extrinsic Asthma and Allergic Rhinitis (AAR), 14 patients with Allergic Rhinitis without asthma (AR) and 14 healthy controls (HC) participated in a cross-sectional study. Exhaled breath was collected by a standardized method and sampled by an e-nose (Cyranose 320). Raw data were reduced by Principal component analysis and analyzed by canonical discriminant analysis. Cross-validation accuracy (CVA) and Receiver Operating Characteristic(ROC)-curves were calculated. External validation in newly recruited patients (7 AAR, 7 AR and 7 HC) was tested using the previous training model.

RESULTS

Breathprints of patients with AR clustered from those with AAR (CVA = 85.7%), as well as HC (CVA = 82.1%). Breathprints from AAR were also separated from those of HC (CVA = 75.0%). External validation confirmed the above findings.

CONCLUSIONS

An e-nose can discriminate exhaled breath from subjects with allergic rhinitis with and without extrinsic asthma, which represent two different diseases with partly overlapping features. This supports the view of using breath profiling to diagnose asthma also in patients with allergic rhinitis.

Novel methods for device and adherence monitoring in asthma

PURPOSE OF REVIEW

The article aims to provide an updated and evidence-based review of the innovative electronic health interventions to monitor and improve inhaler technique and adherence to recommended therapy in asthma.

RECENT FINDINGS

Out of the 290 articles identified by the search strategy, 23 manuscripts fulfilled the review inclusion criteria. Included studies mainly addressed m-health, electronic reminders, telemedicine, and inhaler tracker interventions. Investigations were performed both in adults and children. Remarkably, the majority of studies were performed in the most recent years, showing a progressively increasing interest for this field. Existing findings appear to be of moderate-high quality. A significant number of papers, however, were published in scientific journals with a low impact factor (<2). Furthermore, extremely high heterogeneity was found in the considered study endpoints. Collected evidence supports a relevant role for e-health in monitoring and improving inhaler use and treatment adherence in asthma. The patients' acceptance and satisfaction towards assessed interventions were also found to be positive.

SUMMARY

E-health represents a highly valuable tool for achieving optimal and personalized asthma management. Unanimously agreed and adopted standards for conducting trials and reporting results on e-health in asthma are however needed to fully understand its real added value.

Orosomucoid-like 3 (ORMDL3) upregulates airway smooth muscle proliferation, contraction, and Ca2+ oscillations in asthma

BACKGROUND

Airway hyperresponsiveness is a major feature of asthma attributed predominantly to an extrinsic immune/inflammatory response increasing airway smooth muscle (ASM) contractility.

OBJECTIVE

We investigated whether increased ASM expression of orosomucoid-like 3 (ORMDL3), a gene on chromosome 17q21 highly linked to asthma, induced increased ASM proliferation and contractility in vitro and influenced airway contractility and calcium flux in ASM in precision-cut lung slices (PCLSs) from wild-type and hORMDL3Zp3-Cre mice (which express increased levels of human ORMDL3 [hORMDL3]).

METHODS

Levels of ASM proliferation and contraction were assessed in ASM cells transfected with ORMDL3 in vitro. In addition, airway contractility and calcium oscillations were quantitated in ASM cells in PCLSs derived from naive wild-type and naive hORMDL3Zp3-Cre mice, which do not have a blood supply.

RESULTS

Increased ASM expression of ORMDL3 in vitro resulted in increased ASM proliferation and contractility. PCLSs derived from naive hORMDL3Zp3-Cre mice, which do not have airway inflammation, exhibit increased airway contractility with increased calcium oscillations in ASM cells. Increased ASM ORMDL3 expression increases levels of ASM sarcoplasmic reticulum Ca2+ ATPase 2b (SERCA2b), which increases ASM proliferation and contractility.

CONCLUSION

Overall, these studies provide evidence that an intrinsic increase in ORMDL3 expression in ASM can induce increased ASM proliferation and contractility, which might contribute to increased airway hyperresponsiveness in the absence of airway inflammation in asthmatic patients.

Immunomodulatory innate defence regulator (IDR) peptide alleviates airway inflammation and hyper-responsiveness

BACKGROUND

Exacerbation in asthma is associated with decreased expression of specific host defence peptides (HDPs) in the lungs. We examined the effects of a synthetic derivative of HDP, innate defence regulator (IDR) peptide IDR-1002, in house dust mite (HDM)-challenged murine model of asthma, in interleukin (IL)-33-challenged mice and in human primary bronchial epithelial cells (PBECs).

METHODS

IDR-1002 (6 mg/kg per mouse) was administered (subcutaneously) in HDM-challenged and/or IL-33-challenged BALB/c mice. Lung function analysis was performed with increasing dose of methacholine by flexiVent small animal ventilator, cell differentials in bronchoalveolar lavage performed by modified Wright-Giemsa staining, and cytokines monitored by MesoScale Discovery assay and ELISA. PBECs stimulated with tumour necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ), with or without IDR-1002, were analysed by western blots.

RESULTS

IDR-1002 blunted HDM challenge-induced airway hyper-responsiveness (AHR), and lung leucocyte accumulation including that of eosinophils and neutrophils, in HDM-challenged mice. Concomitantly, IDR-1002 suppressed HDM-induced IL-33 in the lungs. IFN-γ/TNF-α-induced IL-33 production was abrogated by IDR-1002 in PBECs. Administration of IL-33 in HDM-challenged mice, or challenge with IL-33 alone, mitigated the ability of IDR-1002 to control leucocyte accumulation in the lungs, suggesting that the suppression of IL-33 is essential for the anti-inflammatory activity of IDR-1002. In contrast, the peptide significantly reduced either HDM, IL-33 or HDM+IL-33 co-challenge-induced AHR in vivo.

CONCLUSION

This study demonstrates that an immunomodulatory IDR peptide controls the pathophysiology of asthma in a murine model. As IL-33 is implicated in steroid-refractory severe asthma, our findings on the effects of IDR-1002 may contribute to the development of novel therapies for steroid-refractory severe asthma.

Low-density lipoprotein receptor-related protein 1 attenuates house dust mite-induced eosinophilic airway inflammation by suppressing dendritic cell-mediated adaptive immune responses

BACKGROUND

Low-density lipoprotein receptor-related protein 1 (LRP-1) is a scavenger receptor that regulates adaptive immunity and inflammation. LRP-1 is not known to modulate the pathogenesis of allergic asthma.

OBJECTIVE

We sought to assess whether LRP-1 expression by dendritic cells (DCs) modulates adaptive immune responses in patients with house dust mite (HDM)-induced airways disease.

METHODS

LRP-1 expression on peripheral blood DCs was quantified by using flow cytometry. The role of LRP-1 in modulating HDM-induced airways disease was assessed in mice with deletion of LRP-1 in CD11c⁺ cells (Lrp1^fl/fl; CD11c-Cre) and by adoptive transfer of HDM-pulsed CD11b⁺ DCs from Lrp1^fl/fl; CD11c-Cre mice to wild-type (WT) mice.

RESULTS

Human peripheral blood myeloid DC subsets from patients with eosinophilic asthma have lower LRP-1 expression than cells from healthy nonasthmatic subjects. Similarly, LRP-1 expression by CD11b⁺ lung DCs was significantly reduced in HDM-challenged WT mice. HDM-challenged Lrp1^fl/fl; CD11c-Cre mice have a phenotype of increased eosinophilic airway inflammation, allergic sensitization, T_H2 cytokine production, and mucous cell metaplasia. The adoptive transfer of HDM-pulsed LRP-1-deficient CD11b⁺ DCs into WT mice generated a similar phenotype of enhanced eosinophilic inflammation and allergic sensitization. Furthermore, CD11b⁺ DCs in the lungs of Lrp1^fl/fl; CD11c-Cre mice have an increased ability to take up HDM antigen, whereas bone marrow-derived DCs display enhanced antigen presentation capabilities.

CONCLUSION

This identifies a novel role for LRP-1 as a negative regulator of DC-mediated adaptive immune responses in the setting of HDM-induced eosinophilic airway inflammation. Furthermore, the reduced LRP-1 expression by circulating myeloid DCs in patients with eosinophilic asthma suggests a possible role for LRP-1 in modulating type 2-high asthma.

Anti-asthmatic effect of pitavastatin through aerosol inhalation is associated with CD4+ CD25+ Foxp3+ T cells in an asthma mouse model

Statins are competitive inhibitors of 3-hydroxy-3-methylglutaryl-CoA (HMG-A) reductase, and studies have shown that statins also have anti-inflammatory and immunomodulatory properties. The purpose of this study was to investigate the anti-asthmatic effects of pitavastatin, a type of statin, in an asthma mouse model. Mice were sensitized and challenged with ovalbumin (OVA) to establish the asthma model. These mice were then treated with inhaled pitavastatin (5 mg/kg) or dexamethasone (2 mg/kg), the latter of which served as a positive control. The results of the study showed that pitavastatin reduced allergen-induced increases in airway resistance and alleviated bronchial tube thickness and goblet cell hyperplasia in lung tissues. In addition, the results showed that pitavastatin inhibited OVA-induced increases in eosinophil counts and total inflammatory cell counts in bronchoalveolar lavage fluid (BALF) and increased the percentage of CD4+ CD25+ Foxp3+ Treg in the BALF of asthmatic mice. IL-4 and IL-17 levels were decreased, whereas IFN-γ levels were significantly increased in the BALF of pitavastatin-treated mice compared with the BALF of OVA-challenged mice. These results suggest that pitavastatin has potential as a therapy for allergic airway disease and that its effects are associated with its ability to regulate CD4+ CD25+ Foxp3+ T cell counts.

Transforming Growth Factor β1 Function in Airway Remodeling and Hyperresponsiveness. The Missing Link?

The pathogenesis of asthma includes a complex interplay among airway inflammation, hyperresponsiveness, and remodeling. Current evidence suggests that airway structural cells, including bronchial smooth muscle cells, myofibroblasts, fibroblasts, and epithelial cells, mediate all three aspects of asthma pathogenesis. Although studies show a connection between airway remodeling and changes in bronchomotor tone, the relationship between the two remains unclear. Transforming growth factor β1 (TGF-β1), a growth factor elevated in the airway of patients with asthma, plays a role in airway remodeling and in the shortening of various airway structural cells. However, the role of TGF-β1 in mediating airway hyperresponsiveness remains unclear. In this review, we summarize the literature addressing the role of TGF-β1 in airway remodeling and shortening. Through our review, we aim to further elucidate the role of TGF-β1 in asthma pathogenesis and the link between airway remodeling and airway hyperresponsiveness in asthma and to define TGF-β1 as a potential therapeutic target for reducing asthma morbidity and mortality.

Patient profiles and clinical utility of mepolizumab in severe eosinophilic asthma

Mepolizumab (Nucala^®) is an effective and specific anti-eosinophil molecular therapy that has recently been approved as add-on therapy for the management of severe eosinophilic asthma by the US Food and Drug Administration (FDA), European Medicines Agency (EMA; European Union) and more recently National Institute for Health and Care Excellence (NICE; UK). It is one of several molecular therapies in development for this indication and is illustrative of the strategic trajectory for pharmaceutical drug development taken over the past decade in several disease areas. Molecular therapies offer the prospect of improved specificity and effectiveness of biological effect. However, this necessitates a clear understanding of the underlying mechanistic pathways underpinning pathological processes, to inform drug development that yields novel more efficacious treatment options with a better clinical profile than existing agents. For the first time, utilization of molecular therapies in clinical trials is providing a novel in vivo model to characterize the association between specific pathways and clinical disease expression. It is increasingly recognized that asthma exhibits both clinical and pathological heterogeneity. It follows that a one-size-fits-all approach will not be appropriate and cost-effectiveness may only be achieved by identifying responder subgroups. This so-called personalized approach to therapy is being supported by the parallel development of companion biomarkers for clinical application. In this review, the author summarizes the clinical studies, their interpretation and the lessons learnt with mepolizumab that have informed our understanding of the approach to personalized molecular therapy in asthma.

Clinical outcomes of levalbuterol versus racemic albuterol in pediatric patients with asthma: Propensity score matching approach in a medicaid population

OBJECTIVE

Racemic albuterol and levalbuterol are used to treat acute episodes of asthma. The main objective of this study was to compare levalbuterol therapy to albuterol therapy on incidence rates of subsequent emergency department (ED) visits and hospitalizations.

METHOD

We conducted a retrospective cohort study of asthmatic children who had pharmacy refills for levalbuterol/albuterol in the South Carolina Medicaid database in 2002-2011. Children receiving levalbuterol were matched to those receiving albuterol using propensity score matching technique. For ED visits and separately for hospitalizations, multivariable negative binomial regression was used to estimate the two group-specific incidence rates and the incidence rate ratio (IRR).

RESULTS

A total of 8,172 asthmatic patients aged 2-18 years were identified in the South Carolina Medicaid database. During the 12-month follow-up period, the levalbuterol group had fewer asthma-related ED visits and hospitalizations: 939 (11.49%) children had asthma-related ED visits (levalbuterol: 8.76%; albuterol: 14.21%), and 89 (1.09%) children had asthma-related hospitalizations (levalbuterol: 1.07%; albuterol: 1.12%). Comparing the levalbuterol group to the albuterol group, the adjusted IRR estimate was 0.57 (95% confidence interval [CI], 0.49-0.65) for of asthma-related ED visits, and 0.93 (95%CI, 0.99-1.63) for hospitalizations. Children filling levalbuterol also had a lower IRR of all-cause ED visit (0.88; 95%CI, 0.82-0.95), but similar IRR of all-cause hospitalizations (1.08; 95%CI, 0.82-1.42).

CONCLUSION

This observational study of children aged 2-18 demonstrated levalbuterol prescription fills were associated with reduced ED visits, but not hospitalizations. Additional research may be necessary to assess this association. Pediatr Pulmonol. 2017;52:516-523. © 2016 Wiley Periodicals, Inc.

Targeting patients with asthma for omalizumab therapy: choosing the right patient to get the best value for money

The asthma syndrome has many manifestations, termed phenotypes, that arise by specific cellular and molecular mechanisms, termed endotypes. Understanding an individual's asthma phenotype helps clinicians make rational therapeutic decisions while the understanding of endotypes has led to the development of specific precision medications. Allergic asthma is an example of an asthma phenotype and omalizumab, a monoclonal antibody that neutralizes serum immunoglobulin (Ig)E, is a specific targeted treatment which was developed as a result of an understanding of the endotype of allergic asthma. Omalizumab has been widely used in clinical practice in Europe for over a decade as an add-on therapy to treat patients who have severe refractory allergic asthma. Over this period, many centres have reported their experience with omalizumab as an add-on therapy in patients with severe asthma. These 'real world' clinical effectiveness studies have confirmed the benefits, cost-effectiveness and clinical utility of this medication. Combining the outcomes of both sources of research has yielded important insights that may benefit patients with severe asthma, clinicians who treat them, as well as the funding agencies that reimburse the cost of this medication. The purpose of this review is to describe how to identify and evaluate a patient with asthma for whom treatment with omalizumab may be of clinical and cost-effective benefit. The assessment and investigations used to confirm allergic asthma, the objective assessment of adherence to asthma therapy and the expected benefits of add-on omalizumab treatment are described.

Bronchoconstriction Induces Structural and Functional Airway Alterations in Non-sensitized Rats

The impact of mechanical forces on pathogenesis of airway remodeling and the functional consequences in asthma remains to be fully established. In the present study, we investigated the effect of repeated bronchoconstriction induced by methacholine (MCh) on airway remodeling and airway hyperresponsiveness (AHR) in rats with or without sensitization to an external allergen. We provide evidence that repeated bronchoconstriction, using MCh, alone induces airway inflammation and remodeling as well as AHR in non-allergen-sensitized rats. Also, we found that the airways are structurally and functionally altered by bronchoconstriction induced by either allergen or MCh in allergen-sensitized animals. This finding provides a new animal model for the development of airway remodeling and AHR in mammals and can be used for studying the complex reciprocal relationship between bronchoconstriction and airway inflammation. Further studies on presented animal models are required to clarify the exact mechanisms underlying airway remodeling due to bronchoconstriction and the functional consequences.

A pathogenic role for the integrin CD103 in experimental allergic airways disease

The integrin CD103 is the α_E chain of integrin α_Eβ₇ that is important in the maintenance of intraepithelial lymphocytes and recruitment of T cells and dendritic cells (DC) to mucosal surfaces. The role of CD103 in intestinal immune homeostasis has been well described, however, its role in allergic airway inflammation is less well understood. In this study, we used an ovalbumin (OVA)-induced, CD103-knockout (KO) BALB/c mouse model of experimental allergic airways disease (EAAD) to investigate the role of CD103 in disease expression, CD4⁺ T-cell activation and DC activation and function in airways and lymph nodes. We found reduced airways hyper-responsiveness and eosinophil recruitment to airways after aerosol challenge of CD103 KO compared to wild-type (WT) mice, although CD103 KO mice showed enhanced serum OVA-specific IgE levels. Following aerosol challenge, total numbers of effector and regulatory CD4⁺ T-cell subsets were significantly increased in the airways of WT but not CD103 KO mice, as well as a lack of DC recruitment into the airways in the absence of CD103. While total airway DC numbers, and their in vivo allergen capture activity, were essentially normal in steady-state CD103 KO mice, migration of allergen-laden airway DC to draining lymph nodes was disrupted in the absence of CD103 at 24 h after aerosol challenge. These data support a role for CD103 in the pathogenesis of EAAD in BALB/c mice through local control of CD4⁺ T cell and DC subset recruitment to, and migration from, the airway mucosa during induction of allergic inflammation.

Acid-Sensing Ion Channel 1a Contributes to Airway Hyperreactivity in Mice

Neurons innervating the airways contribute to airway hyperreactivity (AHR), a hallmark feature of asthma. Several observations suggested that acid-sensing ion channels (ASICs), neuronal cation channels activated by protons, might contribute to AHR. For example, ASICs are found in vagal sensory neurons that innervate airways, and asthmatic airways can become acidic. Moreover, airway acidification activates ASIC currents and depolarizes neurons innervating airways. We found ASIC1a protein in vagal ganglia neurons, but not airway epithelium or smooth muscle. We induced AHR by sensitizing mice to ovalbumin and found that ASIC1a^-/- mice failed to exhibit AHR despite a robust inflammatory response. Loss of ASIC1a also decreased bronchoalveolar lavage fluid levels of substance P, a sensory neuropeptide secreted from vagal sensory neurons that contributes to AHR. These findings suggest that ASIC1a is an important mediator of AHR and raise the possibility that inhibiting ASIC channels might be beneficial in asthma.

Association of symptom control with changes in lung function, bronchial hyperresponsiveness, and exhaled nitric oxide after inhaled corticosteroid treatment in children with asthma

BACKGROUND

A key therapeutic approach to asthma, which is characterized by chronic airway inflammation, is inhaled corticosteroid (ICS). This study evaluated the association of symptom control with changes in lung function, bronchial hyperresponsiveness (BHR), and exhaled nitric oxide (eNO) after ICS treatment in asthmatic children.

METHODS

A total of 33 children aged between 5 and 12 years with mild to moderate persistent asthma were treated with 160 μg ciclesonide per day for 3 months. At days 0 and 90, the following parameters were assessed: asthma symptom scores; lung function, including forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and forced expiratory flow at 25-75% of forced vital capacity (FEF_25-75%); BHR to methacholine and adenosine 5-monophosphate (AMP); and eNO.

RESULTS

Asthma symptom scores, lung function parameters, BHR to methacholine and AMP, and eNO levels at day 90 were significantly improved versus day 0 (all p < 0.001). Symptom scores at day 90 were not correlated with changes in lung function and BHR to methacholine during the follow-up period, whereas those at day 90 were more closely correlated with changes in BHR to AMP (r = 0.511, p = 0.003) than with eNO (r = -0.373, p = 0.035). Additionally, changes in PC₂₀ AMP were correlated with changes in PC₂₀ methacholine (r = 0.451, p = 0.011) and eNO (r = -0.474, p = 0.006).

CONCLUSIONS

Changes in the BHR to AMP, and to a lesser extent eNO, correlate with asthma symptom control after ICS treatment. BHR to AMP may better reflect the relationship between improved airway inflammation due to ICS treatment and asthma symptoms.

Concordance between bronchial hyperresponsiveness, fractional exhaled nitric oxide, and asthma control in children

BACKGROUND

Previous studies on association between level of asthma control, markers of airway inflammation and the degree of bronchial hyperresponsiveness (BHR) have yielded conflicting results. Our aim was to determine the presence and severity of BHR and the concordance between BHR, asthma control, and fractional exhaled nitric oxide (FeNO) in children with asthma on therapy.

METHODS

In this cross-sectional observational study, children (aged 6-18 years) with asthma on British Thoracic Society (BTS) treatment steps 2 or 3, underwent comprehensive assessment of their asthma control (clinical assessment, spirometry, asthma control test [ACT], Pediatric Asthma Quality of Life Questionnaire [PAQLQ]), measurement of FeNO and BHR (using mannitol dry powder bronchial challenge test [MCT], Aridol™, Pharmaxis, Australia).

RESULTS

Fifty-seven children (63% male) were studied. Twenty-seven children were on BTS treatment step 2 and 30 were on step 3. Overall, 25 out of 57 (43.8%) children had positive MCT. Of note, 9 out of 27 (33.3%) children with clinically controlled asthma had positive MCT. Analyses of pair-wise agreement between MCT (positive or negative), FeNO (>25 or ≤25 ppb) and clinical assessment of asthma control (controlled or partially controlled/uncontrolled) showed poor agreement between these measures.

CONCLUSIONS

A substantial proportion of children with asthma have persistent BHR despite good clinical control. The concordance between clinical assessment of asthma control, BHR and FeNO was observed to be poor. Our findings raise concerns in the context of emerging evidence for the role of bronchoconstriction in inducing epithelial stress that may drive airway remodeling in asthma. Pediatr Pulmonol. 2016;51:1004-1009. © 2016 Wiley Periodicals, Inc.