Analysis of induced sputum in adults with asthma: identification of subgroup with isolated sputum neutrophilia and poor response to inhaled corticosteroids

Biomarkers and asthma management: analysis and potential applications

PURPOSE OF REVIEW

Asthma features a high degree of heterogeneity in both pathophysiology and therapeutic response, resulting in many asthma patients being treated inadequately. Biomarkers indicative of underlying pathological processes could be used to identify disease subtypes, determine prognosis and to predict or monitor treatment response. However, the newly identified as well as more established biomarkers have different applications and limitations.

RECENT FINDINGS

Conventional markers for type 2-high asthma, such as blood eosinophils, fraction of exhaled nitric oxide, serum IgE and periostin, feature limited sensitivity and specificity despite their significant correlations. More distinctive models have been developed by combining biomarkers and/or using omics techniques. Recently, a model with a positive predictive value of 100% for identification of type 2-high asthma based on a combination of minimally invasive biomarkers was developed.

SUMMARY

Individualisation of asthma treatment regimens on the basis of biomarkers is necessary to improve asthma control. However, the suboptimal properties of currently available conventional biomarkers limit its clinical utility. Newly identified biomarkers and models based on combinations and/or omics analysis must be validated and standardised before they can be routinely applied in clinical practice. The development of robust biomarkers will allow development of more efficacious precision medicine-based treatment approaches for asthma.

Accuracy of objective tests for diagnosing adult asthma in symptomatic patients: A systematic literature review and hierarchical Bayesian latent-class meta-analysis

BACKGROUND

We obtain summary estimates of the accuracy of additional objective tests for the diagnosis of adult asthma using systematic review and meta-analysis of diagnostic test accuracy studies.

METHODS

Medline, Embase, and other relevant electronic databases were searched for papers published between January 1989 and December 2016. Studies were included if they evaluated the diagnostic accuracy of objective tests, including airway reversibility (AR), airway hyperresponsiveness (AHR), and fractionated exhaled nitric oxide (FeNO) for the diagnosis of adult asthma in patients with symptoms suggestive of asthma. If papers were assessed appropriate using the adapted QUADAS-2 tool, meta-analysis was conducted using the hierarchical bivariate model. This hierarchical model accounts for both within and between study variability.

RESULTS

Sixteen studies reported the performance of the evaluated objective tests at presentation. For diagnosis of adult asthma, overall sensitivity and specificity for AR were 0.39 (95% confidence interval [CI] 0.18 to 0.66) and 0.95 (95% CI 0.86 to 1.00); for AHR, 0.86 (95% CI 0.61 to 1.00) and 0.95 (95% CI 0.77 to 1.00); for FeNO, 0.65 (95% CI 0.53 to 0.77) and 0.83 (95% CI 0.75 to 0.90). Comprehensive comparison of three diagnostic tools for adult asthma using the back-calculated likelihood rate (LR) showed that AR and AHR corresponded to a higher LR+, and AHR gave a lower LR-.

CONCLUSIONS

In the current situation of no gold standard for diagnosis of adult asthma, AR and AHR are appropriate for ruling-in the true diagnosis, and AHR is superior for ruling-out a diagnosis. Since each objective test had a specific characteristic, it should be chosen depending on the situation, such as the capacity of the institution and the conditions of patients.

Precision medicine and phenotypes, endotypes, genotypes, regiotypes, and theratypes of allergic diseases

A rapidly developing paradigm for modern health care is a proactive and individualized response to patients' symptoms, combining precision diagnosis and personalized treatment. Precision medicine is becoming an overarching medical discipline that will require a better understanding of biomarkers, phenotypes, endotypes, genotypes, regiotypes, and theratypes of diseases. The 100-year-old personalized allergen-specific management of allergic diseases has particularly contributed to early awareness in precision medicine. Polyomics, big data, and systems biology have demonstrated a profound complexity and dynamic variability in allergic disease between individuals, as well as between regions. Escalating health care costs together with questionable efficacy of the current management of allergic diseases facilitated the emergence of the endotype-driven approach. We describe here a precision medicine approach that stratifies patients based on disease mechanisms to optimize management of allergic diseases.

Matrix Metalloproteinase-9-Dependent Release of IL-1β by Human Eosinophils

Asthma is often associated with airway eosinophilia, and therapies targeting eosinophils are now available to treat severe eosinophilic asthma. Eosinophilic asthma is often due to a type-2 immune response and production of IL-5, which leads to eosinophilopiesis and recruitment of mature eosinophils in the airways. A concomitant type-2 and type-17 response has been reported in some individuals. IL-17 may be enhanced by IL-1β production and can lead to neutrophilic inflammation. In fact, both eosinophilic and neutrophilic (mixed granulocytic) inflammation are simultaneously present in a large population of patients with asthma. In monocyte/macrophage cell populations, release of mature IL-1β occurs via toll-like receptor ligand-induced activation of the inflammasome. Within the inflammasome, a cascade of events leads to the activation of caspase-1, which cleaves pro-IL-1β protein into a mature, releasable, and active form. We have demonstrated that eosinophils can release IL-1β in a Toll-like receptor ligand-independent fashion. The objective of this study was to determine the mechanisms underlying the production and maturation of IL-1β in cytokine-activated eosinophils. Using eosinophils from circulating blood and from bronchoalveolar lavage fluid after an airway allergen challenge, the present study demonstrates that cytokine-activated eosinophils express and release a bioactive form of IL-1β with an apparent size less than the typical 17 kDa mature form produced by macrophages. Using a zymography approach and pharmacological inhibitors, we identified matrix metalloproteinase-9 (MMP-9) as a protease that cleaves pro-IL-1β into a ~15 kDa form and allows the release of IL-1β from cytokine-activated eosinophils. Therefore, we conclude that activated eosinophils produce MMP-9, which causes the release of IL-1β in an inflammasome/caspase-1-independent manner. The production of IL-1β by eosinophils may be a link between the eosinophilic/type-2 immune response and the neutrophilic/type-17 immune response that is often associated with a more severe and treatment-refractory type of asthma.

Research highlights from the 2018 European Respiratory Society International Congress: airway disease

The annual European Respiratory Society (ERS) International Congress (held in Paris in 2018) was once again a platform for discussion of the highest-quality scientific research, cutting-edge techniques and innovative new therapies within the respiratory field. This article discusses only some of the high-quality research studies presented at this year's Congress, with a particular focus on airway diseases including asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis and cough, as presented through Assembly 5 of the ERS (Airway Diseases: Asthma and COPD). The authors establish the key take-home messages of these studies, compare their findings and place them in the context of current understanding.

Adapting clinical trial design to maintain meaningful outcomes during a multicenter asthma trial in the precision medicine era

Precision medicine is expected to impact the care of people with asthma, given its high disease prevalence, heterogeneity of pathophysiologic mechanisms, and consequent clinical phenotypes. A novel phenotype-stratified clinical trial conducted by the NHLBI AsthmaNet Consortium, titled Steroids in Eosinophil Negative Asthma (SIENA), was a randomized, multicenter, clinical trial that prospectively stratified individuals according to their baseline level of sputum inflammation during a screening period. Two phenotypic strata were assigned based on an a priori defined extent of sputum eosinophilia (Eos Low versus Eos High). This article describes: the scientific premise for the trial design, including assumptions used for power calculations; modifications to the analysis plan implemented after the trial started due to a higher than expected prevalence of one phenotypic stratum which impacted the ability to accrue sufficient subjects within the planned budget and study period; investigator alternatives to address the strata imbalance weighing scientific impact and study feasibility; and the final modified SIENA study design and analysis plan. SIENA was successfully completed in a manner that maintained meaningful outcomes. We conclude with recommendations for incorporation of pre-specified contingency plans into phenotype-directed protocols, to address the potential for differences in observed compared to estimated prevalence of different phenotypes in a study population. These approaches can be applied to precision medicine trials for the future.

Tight junction, mucin, and inflammasome-related molecules are differentially expressed in eosinophilic, mixed, and neutrophilic experimental asthma in mice

BACKGROUND

Asthma is a chronic respiratory disease with marked clinical and pathophysiological heterogeneity. Specific pathways are thought to be involved in the pathomechanisms of different inflammatory phenotypes of asthma; however, direct in vivo comparison has not been performed.

METHODS

We developed mouse models representing three different phenotypes of allergic airway inflammation-eosinophilic, mixed, and neutrophilic asthma via different methods of house dust mite sensitization and challenge. Transcriptomic analysis of the lungs, followed by the RT-PCR, western blot, and confocal microscopy, was performed. Primary human bronchial epithelial cells cultured in air-liquid interface were used to study the mechanisms revealed in the in vivo models.

RESULTS

By whole-genome transcriptome profiling of the lung, we found that airway tight junction (TJ), mucin, and inflammasome-related genes are differentially expressed in these distinct phenotypes. Further analysis of proteins from these families revealed that Zo-1 and Cldn18 were downregulated in all phenotypes, while increased Cldn4 expression was characteristic for neutrophilic airway inflammation. Mucins Clca1 (Gob5) and Muc5ac were upregulated in eosinophilic and even more in neutrophilic phenotype. Increased expression of inflammasome-related molecules such as Nlrp3, Nlrc4, Casp-1, and IL-1β was characteristic for neutrophilic asthma. In addition, we showed that inflammasome/Th17/neutrophilic axis cytokine-IL-1β-may transiently impair epithelial barrier function, while IL-1β and IL-17 increase mucin expressions in primary human bronchial epithelial cells.

CONCLUSION

Our findings suggest that differential expression of TJ, mucin, and inflammasome-related molecules in distinct inflammatory phenotypes of asthma may be linked to pathophysiology and might reflect the differences observed in the clinic.

Greater eosinophil counts at first COPD hospitalization are associated with more readmissions and fewer deaths

Purpose

The impacts of high blood eosinophil count (HBEC) at admission for COPD exacerbation on posthospitalization outcomes are still unclear. Previous studies have focused on its associations with first readmission rates; yet, its impacts on longitudinal outcomes such as subsequent readmissions still have to be explored. The main objective of this study is to investigate outcomes associated with HBEC following a first hospitalization for COPD exacerbation.

Patients and methods

This is an observational cohort study design. We retrospectively analyzed data of patients with a first hospitalization within 5 years for COPD exacerbation between April 2006 and March 2013. Patients were stratified into the HBEC group if the blood eosinophil count at admission was ≥200 cells/µL and/or ≥2% of the total white blood cells. With information on exact dates of subsequent hospitalizations and death, we modeled readmissions and death as states in a multi-state Markov model and estimated transition probabilities to the next states. Sensitivity analyses were performed by varying thresholds for the definition of HBEC (≥300 cells/µL and/or ≥3%).

Results

A total of 479 patients were included, of which 173 had HBEC. The transition probabilities for a first readmission was 74% (95% CI, 66%–83%) for patients with HBEC vs 70% (95% CI, 63%–77%) for patients with normal blood eosinophil count (NBEC). The transition probabilities for a second readmission were 91% (95% CI, 84%–100%) for HBEC patients in contrast with 83% (95% CI, 74%–92%) for NBEC patients. Meanwhile, transition probability for death was lower in patients with HBEC. The differences enlarged in sensitivity analyses with higher cutoff.

Conclusion

Greater blood eosinophil cell counts during a first hospitalization for COPD predict increased susceptibility to up to two readmissions. These patients may however have a lower risk of death.

Repeated exacerbation of asthma: An intrinsic phenotype of uncontrolled asthma

Asthma is a chronic disease of the airways affecting a large number of people across the globe. Uncontrolled asthma poses an emotional as well as the physical burden on patients and results in a great economic burden. “Exacerbation-prone phenotype” asthmatics are a cluster of patients who may suffer from more frequent and severe exacerbations than other asthmatics. Factors such as inadequate symptom control, improper adherence to medications, and incorrect use of inhalers are responsible for frequent asthma exacerbations. Caring for the patient with “exacerbation-prone asthma” needs participation from both the doctor as well as the patient. Self-management, improving knowledge about the disease, control of comorbidities, and a stepwise approach with the use of a single inhaler maintenance and reliever therapy in patients with severe asthma could help in delivering better care for the “exacerbation-prone phenotype” of asthmatics.

Evaluation of Neutrophil Activation Status According to the Phenotypes of Adult Asthma

Purpose

Neutrophils are considered key effector cells in the pathogenic mechanisms of airway inflammation in asthma. This study assessed the activation status of neutrophils in adult asthmatics, and the therapeutic potential of FTY720, a synthetic sphingosine-1-phosphate analog, on activated neutrophils using an in vitro stimulation model.

Methods

We isolated peripheral blood neutrophils (PBNs) from 59 asthmatic patients (including 20 aspirin-exacerbated respiratory disease [AERD] and 39 aspirin-tolerant asthma [ATA] groups). PBNs were stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or lipopolysaccharide (LPS) and their activation status was determined based on reactive oxygen species (ROS) production, cell surface expression of CD11b, interleukin (IL)-8 and matrix metallopeptidase (MMP)-9 release. PBNs were primed with FTY720 to evaluate its anti-inflammatory action.

Results

In vitro PBN stimulation with fMLP or LPS induced a significant increase in ROS/CD11b/IL-8/MMP-9 levels (P < 0.05 for all). In asthmatics, fMLP-induced ROS level was significantly correlated with values of forced expiratory volume in 1 second/forced vital capacity (r = −0.278; P = 0.036), maximal mid-expiratory flow (r = −0.309; P = 0.019) and PC20 methacholine (r = −0.302; P = 0.029). In addition, ROS levels were significantly higher in patients with AERD and in those with severe asthma than in those with ATA or non-severe asthma (P < 0.05 for all). FTY720 treatment could suppress ROS/CD11b levels, and LPS-induced IL-8 and MMP-9 levels (P < 0.05 for all). Responders to FTY720 treatment had significantly higher neutrophil counts in sputum (P = 0.004).

Conclusions

Our findings suggest a useful in vitro PBN stimulation model for evaluating the neutrophil functional status and the therapeutic potentials of neutrophil-targeting candidates in asthmatics.

Expression of TSLP and IL-33 receptors on sputum macrophages of asthma patients and healthy subjects

Objective: Local cytokine milieu (especially Th2 inflammatory type) secreted into the asthmatic airways affect the alternative activated macrophages polarization (M2). TSLP and IL-33 are important alarmins of allergic response associated with Th2 inflammation. The aim of the study was to investigate the expression of the receptors for epithelial derived cytokines: TSLP (TSLPR) and IL-33 (ST2) on induced sputum CD206 positive macrophages from asthma and healthy subjects and analyze the relationships between these receptors and clinical features of the disease. Methods: Immunofluorescence staining for CD206 and TSLPR or ST2 on sputum macrophages was performed in 20 adult patients with stable asthma - 75% with atopy (3 intermittent, 12 mild-to-moderate, 5 severe, of which 11 were on biological anty-IgE treatment) and 23 healthy adult controls - 48% with atopy. Results: Our study demonstrated an increased expression of TSLP and IL-33 receptors on bronchial CD206 positive macrophages in asthma group. TSLPR but not ST2 had also greater expression on CD206 negative macrophages in asthma patients. Increased expression of both investigated receptors was related to longer disease duration and impaired lung function. We observed increased count of CD206_lowTSLP_high macrophages as well as positive correlation of these cells with total serum IgE in patients with atopy. Conclusions: The macrophage response during allergic reaction is likely to be connected with TSLP but rather not with IL-33 action. Our study indicates an important role of crosstalk between macrophages, TSLP and IL-33 in asthma pathophysiology.

Sulforaphane ameliorates steroid insensitivity through an Nrf2-dependent pathway in cigarette smoke-exposed asthmatic mice

Oxidative stress induced by cigarette smoke and other environmental pollutants contributes to refractory asthma. To better understand the role of smoking in asthma, we investigated the effects of cigarette smoke on allergic airway responses in mice and examined expression of nuclear factor-E2-related factor-2 (Nrf2) and its downstream factors, because Nrf2 is known to play a pivotal role in antioxidant responses. OVA-sensitized and challenged BALB/c mice were exposed to cigarette smoke and then treated with dexamethasone, sulforaphane (an activator of Nrf2), or their combination. Upon exposure to cigarette smoke, Nrf2 and associated transcripts were upregulated in response to oxidative stress, and asthmatic responses were steroid resistant. In OVA-sensitized and challenged mice exposed to cigarette smoke and treated with sulforaphane, Nrf2-mediated antioxidant responses were upregulated to a greater extent, and steroid sensitivity of asthmatic responses was restored. Moreover, the expression and activity of histone deacetylase 2 (HDAC2), a key regulator of steroid responsiveness, was reduced in mice exposed to cigarette smoke, but restored by sulforaphane treatment. No effects of sulforaphane were observed in Nrf2-deficient mice. These findings indicate that cigarette smoke induces steroid unresponsiveness in asthmatic airways, and that sulforaphane restores steroid sensitivity via upregulation of Nrf2 and enhancement of HDAC2 expression and activity. Thus, Nrf2 may serve as a potential molecular target for cigarette smoke-related refractory asthma resistant to steroid therapy.

Non-redundant Functions of IL-6 Produced by Macrophages and Dendritic Cells in Allergic Airway Inflammation

Asthma is a common inflammatory disease of the airway caused by a combination of genetic and environmental factors and characterized by airflow obstruction, wheezing, eosinophilia, and neutrophilia of lungs and sputum. Similar to other proinflammatory cytokines, IL-6 is elevated in asthma and plays an active role in this disease. However, the exact molecular mechanism of IL-6 involvement in the pathogenesis of asthma remains largely unknown and the major cellular source of pathogenic IL-6 has not been defined. In the present study, we used conditional gene targeting to demonstrate that macrophages and dendritic cells are the critical sources of pathogenic IL-6 in acute HDM-induced asthma in mice. Complete genetic inactivation of IL-6 ameliorated the disease with significant decrease in eosinophilia in the lungs. Specific ablation of IL-6 in macrophages reduced key indicators of type 2 allergic inflammation, including eosinophil and Th2 cell accumulation in the lungs, production of IgE and expression of asthma-associated inflammatory mediators. In contrast, mice with deficiency of IL-6 in dendritic cells demonstrated attenuated neutrophilic, but regular eosinophilic response in HDM-induced asthma. Taken together, our results indicate that IL-6 plays a pathogenic role in the HDM-induced asthma model and that lung macrophages and dendritic cells are the predominant sources of pathogenic IL-6 but contribute differently to the disease.

Intranasal curcumin protects against LPS-induced airway remodeling by modulating toll-like receptor-4 (TLR-4) and matrixmetalloproteinase-9 (MMP-9) expression via affecting MAP kinases in mouse model

OBJECTIVE

Bacterial infections can exacerbate asthmatic inflammation depending on lipopolysaccharide (LPS) composition, the outermost component of cell wall, its exposure timings as well as host's immune status. In present study, Balb/c mice were exposed to antigen (ovalbumin) and LPS simultaneously to establish an asthmatic model. Curcumin (diferuloylmethane), well known for its anti-inflammatory potential, was administered through intranasal route 1 h before LPS and OVA (ovalbumin) exposure to evaluate its efficacy against airway structural changes.

METHODS

Inflammatory cell infiltration in lungs was measured by flow cytometry and further eosinophils were especially measured by immunofluorescence detection of major basic protein (MBP) as marker of eosinophilc granule protein. We also measured reactive oxygen species (ROS) in BALF by spectrofluorometry. MMP-9 activity was evaluated by gelatin zymography and mRNA expressions of MMP-9, TIMP-1, TGF-β1, IL-13, Collagen-1 and TLR-4 were measured in lungs. Protein expression of MAP kinases (P-ERK, P-JNK, P-p38), TLR-4, Cox-2, Lox-5 and Eotaxin was measured by western blotting. Hydroxyproline level and masson's trichrome staining were used to evaluate collagen deposition in lung.

RESULTS

Exposure to LPS (0.1 µg) exacerbates airway inflammation and induces structural changes in lungs by enhanced ROS production, collagen deposition, expression of genes involved in airway remodeling and activation of MAP kinases pathway enzymes. Intranasal curcumin pretreatment had significantly suppressed inflammatory mediators and airway remodeling proteins.

CONCLUSION

Our results strongly suggest that intranasal curcumin effectively protects LPS-induced airway inflammation and structural changes by modulating genes involved in airway remodeling in safer way; hence, it can be considered as supplementary alternative towards asthma treatments.

Non-eosinophilic asthma: current perspectives

Although non-eosinophilic asthma (NEA) is not the best known and most prevalent asthma phenotype, its importance cannot be underestimated. NEA is characterized by airway inflammation with the absence of eosinophils, subsequent to activation of non-predominant type 2 immunologic pathways. This phenotype, which possibly includes several not well-defined subphenotypes, is defined by an eosinophil count <2% in sputum. NEA has been associated with environmental and/or host factors, such as smoking cigarettes, pollution, work-related agents, infections, and obesity. These risk factors, alone or in conjunction, can activate specific cellular and molecular pathways leading to non-type 2 inflammation. The most relevant clinical trait of NEA is its poor response to standard asthma treatments, especially to inhaled corticosteroids, leading to a higher severity of disease and to difficult-to-control asthma. Indeed, NEA constitutes about 50% of severe asthma cases. Since most current and forthcoming biologic therapies specifically target type 2 asthma phenotypes, such as uncontrolled severe eosinophilic or allergic asthma, there is a dramatic lack of effective treatments for uncontrolled non-type 2 asthma. Research efforts are now focusing on elucidating the phenotypes underlying the non-type 2 asthma, and several studies are being conducted with new drugs and biologics aiming to develop effective strategies for this type of asthma, and various immunologic pathways are being scrutinized to optimize efficacy and to abolish possible adverse effects.

The enigmatic role of the neutrophil in asthma: Friend, foe or indifferent?

Whilst severe asthma has classically been categorized as a predominantly Th2-driven pathology, there has in recent years been a paradigm shift with the realization that it is a heterogeneous disease that may manifest with quite disparate underlying inflammatory and remodelling profiles. A subset of asthmatics, particularly those with a severe, corticosteroid refractory disease, present with a prominent neutrophilic component. Given the potential of neutrophils to impart extensive tissue damage and promote inflammation, it has been anticipated that these cells are closely implicated in the underlying pathophysiology of severe asthma. However, uncertainty persists as to why the neutrophil is present in the asthmatic lung and what precisely it is doing there, with evidence supporting its role as a protagonist of pathology being primarily circumstantial. Furthermore, our view of the neutrophil as a primitive, indiscriminate killer has evolved with the realization that neutrophils can exhibit a marked anti-inflammatory, pro-resolving and wound healing capacity. We suggest that the neutrophil likely exhibits pleiotropic and potentially conflicting roles in defining asthma pathophysiology-some almost certainly detrimental and some potentially beneficial-with context, timing and location all critical confounders. Accordingly, indiscriminate blockade of neutrophils with a broad sword approach is unlikely to be the answer, but rather we should first seek to understand their complex and multifaceted roles in the disease state and then target them with the same subtleties and specificity that they themselves exhibit.

House dust mite-driven neutrophilic airway inflammation in mice with TNFAIP3-deficient myeloid cells is IL-17-independent

BACKGROUND

Asthma is a heterogeneous disease of the airways that involves several types of granulocytic inflammation. Recently, we have shown that the activation status of myeloid cells regulated by TNFAIP3/A20 is a crucial determinant of eosinophilic or neutrophilic airway inflammation. However, whether neutrophilic inflammation observed in this model is dependent on IL-17 remains unknown.

OBJECTIVE

In this study, we investigated whether IL-17RA-signalling is essential for eosinophilic or neutrophilic inflammation in house dust mite (HDM)-driven airway inflammation.

METHODS

Tnfaip3^fl/fl xLyz2^+/cre (Tnfaip3^LysM-KO ) mice were crossed to Il17ra^KO mice, generating Tnfaip3^LysM Il17ra^KO mice and subjected to an HDM-driven airway inflammation model.

RESULTS

Both eosinophilic and neutrophilic inflammation observed in HDM-exposed WT and Tnfaip3^LysM-KO mice respectively were unaltered in the absence of IL-17RA. Production of IL-5, IL-13 and IFN-γ by CD4⁺ T cells was similar between WT, Tnfaip3^LysM-KO and Il17ra^KO mice, whereas mucus-producing cells in Tnfaip3^LysM-KO Il17ra^KO mice were reduced compared to controls. Strikingly, spontaneous accumulation of pulmonary Th1, Th17 and γδ-17 T cells was observed in Tnfaip3^LysM-KO Il17ra^KO mice, but not in the other genotypes. Th17 cell-associated cytokines such as GM-CSF and IL-22 were increased in the lungs of HDM-exposed Tnfaip3^LysM-KO Il17ra^KO mice, compared to IL-17RA-sufficient controls. Moreover, neutrophilic chemo-attractants CXCL1, CXCL2, CXCL12 and Th17-promoting cytokines IL-1β and IL-6 were unaltered between Tnfaip3^LysM-KO and Tnfaip3^LysM-KO Il17ra^KO mice.

CONCLUSION AND CLINICAL RELEVANCE

These findings show that neutrophilic airway inflammation induced by activated TNFAIP3/A20-deficient myeloid cells can develop in the absence of IL-17RA-signalling. Neutrophilic inflammation is likely maintained by similar quantities of pro-inflammatory cytokines IL-1β and IL-6 that can, independently of IL-17-signalling, induce the expression of neutrophil chemo-attractants.

Efficacy of inhaled budesonide for the treatment of severe equine asthma

Background

Corticosteroids are the most potent drugs for the control of severe equine asthma, but adverse effects limit their chronic systemic administration. Inhaled medications allow for drug delivery directly into the airways, reducing the harmful effects of these drugs.

Objectives

To evaluate the efficacy of inhaled budesonide specifically formulated for the equine use and administered by a novel inhalation device in horses with severe asthma.

Study design

Experimental studies in horses with naturally occurring asthma with cross‐over, randomised, blinded experimental designs.

Methods

In Study 1, budesonide (1800 μg twice daily) administered using a novel Respimat^® based inhaler was compared to i.v. dexamethasone (0.04 mg/kg). In Study 2, 3 doses of budesonide (450, 900, and 1800 μg) were compared to oral dexamethasone (0.066 mg/kg). Lung function, bronchoalveolar fluid cytology (Study 1), CBC, serum chemistry, and serum cortisol and adrenocorticotropic hormone (ACTH) values were evaluated.

Results

In Study 1, there was a marked and significant improvement in the lung function of all horses treated with budesonide and dexamethasone. Neutrophil percentages in bronchoalveolar fluid decreased in all horses treated with dexamethasone and in four of six horses treated with budesonide. Serum cortisol and blood ACTH concentrations decreased with both treatments. In Study 2, there was a significant improvement in the lung function with all dosages of budesonide, and the effects of higher dosages were comparable to those of dexamethasone. Dexamethasone and budesonide at the two higher dosages induced a significant decrease of cortisol concentrations.

Main limitations

The Respimat^® based inhaler is not currently commercially available.

Conclusions

Administration of budesonide with the Respimat^® based inhaler provided dose‐dependent relief of airway obstruction in horses with severe asthma, but also a suppression of serum cortisol.

Exhaled Nitric Oxide: An Update

Fractional concentration of exhaled nitric oxide (FENO) is a biomarker used to identify allergic airway inflammation. Because it is noninvasive and easy to obtain, its utility has been studied in the diagnosis and management of several respiratory diseases. Much of the research has been done in asthma, and many studies support the use of FENO in aiding diagnosing asthma, predicting steroid responsiveness, and preventing exacerbations by guiding medication dosage and assessing adherence.

Molecular Endotypes Contribute to the Heterogeneity of Asthma

Diagnosis and management of asthma is commonly implemented based on clinical assessment. Although these nonmolecular biomarkers have been useful, limited resolution of the heterogeneity among asthmatic patients and little information regarding the underlying pathobiology of disease in individuals have been provided. Molecular endotying using global transcriptome expression profiling associated with clinical features of asthma has improved our understanding of disease mechanisms, risk assessment of asthma exacerbations, and treatment responses, especially in patients with type 2 inflammation. Further advances in establishing pathobiological subgroups, bioactive pathways, and true disease endotypes hold potential for a more personalized medical approach in asthmatic patients.

Cytokines in sensitization to aeroallergens

Knowledge about the immunological mechanisms underlying asthma bronchiale is a prerequisite for development of new (causal) interventions. A large number of studies has proven asthma to be a complex disease with subtypes with different immunological features. Cytokines and chemokines, which are secreted by immune cells as well as structural cells play an important role not only in maintenance and amplification but have significant impact in the initiation of pulmonary inflammations – the asymptomatic sensitization phase. This article describes important immunological mediators in the context of the pulmonary sensitization phase. Moreover chances and constraints of intervention strategies aiming at these mediators are discussed. Several new aspects like classification of immunological phenotypes in bronchial asthma for individualized strategies and taking the sensitization phase into account, reveal possible targets among both “old acquaintances” like IL-4 and newly identified mediators (e.g. IL-17, IL-33).

Precision medicine in asthma: linking phenotypes to targeted treatments

PURPOSE OF REVIEW

Asthma is a heterogeneous disease consisting of different phenotypes that are driven by different mechanistic pathways. The purpose of this review is to emphasize the important role of precision medicine in asthma management.

RECENT FINDINGS

Despite asthma heterogeneity, the approach to management has been on the basis of disease severity, with the most severe patients reserved for the maximum treatments with corticosteroids and bronchodilators. At the severe end, the recent availability of biologic therapies in the form of anti-IgE (omalizumab) and anti-IL5 therapies (mepolizumab and reslizumab) has driven the adaptation of precision medicine. These therapies are reserved for severe asthma with defined either allergic or eosinophilic background, respectively.

SUMMARY

Unbiased definition of phenotypes or endotypes (which are phenotypes defined by mechanisms) is an important step towards the use of precision medicine in asthma. Although T2-high asthma has been defined with targets becoming available for treating allergic or eosinophilic asthma, the definition of non-T2 phenotypes remains a priority. Precision medicine is also dependent on the definition of biomarkers that can help differentiate between these phenotypes and pinpoint patients suitable for specific-targeted therapies. Thus, precision medicine links phenotypes (endotypes) to targeted treatments for better outcomes.

The Canonical but Not the Noncanonical Wnt Pathway Inhibits the Development of Allergic Airway Disease

Asthma is a syndrome with multifactorial causes, resulting in a variety of different phenotypes. Current treatment options are not curative and are sometimes ineffective in certain disease phenotypes. Therefore, novel therapeutic approaches are required. Recent findings have shown that activation of the canonical Wnt signaling pathway suppresses the development of allergic airway disease. In contrast, the effect of the noncanonical Wnt signaling pathway activation on allergic airway disease is not well described. The aim of this study was to validate the therapeutic effectiveness of Wnt-1-driven canonical Wnt signaling compared with Wnt-5a-driven noncanonical signaling in murine models. In vitro, both ligands were capable of attenuating allergen-specific T cell activation in a dendritic cell-dependent manner. In addition, the therapeutic effects of Wnt ligands were assessed in two different models of allergic airway disease. Application of Wnt-1 resulted in suppression of airway inflammation as well as airway hyperresponsiveness and mucus production. In contrast, administration of Wnt-5a was less effective in reducing airway inflammation or goblet cell metaplasia. These results suggest an immune modulating function for canonical as well as noncanonical Wnt signaling, but canonical Wnt pathway activation appears to be more effective in suppressing allergic airway disease than noncanonical Wnt activation.

Sputum interleukin-25 correlates with asthma severity: a preliminary study

Introduction

Interleukin 25 is an epithelial-derived cytokine associated with allergic Th2 inflammation. However, little is known about the role of IL-25 in different asthma phenotypes and its relationship with disease severity.

Aim

To evaluate and compare the mRNA and protein expression of IL-25 in patients with mild-to moderate/severe asthma and cough variant asthma (CVA).

Material and methods

Thirty-eight patients with stable asthma (11 patients with mild-to-moderate asthma, 14 patients with severe asthma and 13 patients with CVA) and 14 control subjects were enrolled. IL-25 protein concentration was measured in induced sputum (IS) supernatants by ELISA and IL-25 mRNA expression was evaluated in IS cells by real time PCR.

Results

No differences in IS IL-25 mRNA and IL-25 concentration between controls and the whole asthma group were found. In the detailed analysis, a lower IL-25 mRNA expression in sputum cells was observed in severe asthma compared to CVA and controls. IL-25 protein concentration in sputum supernatants was elevated in patients with severe asthma compared to controls, CVA and mild-to-moderate asthma. A sputum IL-25 level was increased in atopic vs. non-atopic asthma patients. The elevated IL-25 mRNA expression and protein concentration was associated with a lower eosinophil and higher neutrophil percentage in asthmatic airways.

Conclusions

Our results suggest that IL-25 is particularly associated with severe asthma. The relationship between IL-25 and neutrophilic airway inflammation suggests the pleiotropic role of IL-25 in the immune response in this disease.

Towards precision medicine in severe asthma: Treatment algorithms based on treatable traits

Asthma is a common disease, and although its clinical manifestations may be similar among patients, recent research discoveries have shown that it consists of several distinct clinical clusters or phenotypes, each with different underlying molecular pathways yielding different treatment responses. Based on these observations, an alternative approach - known as 'precision medicine' - has been proposed for the management of patients with severe asthma. Precision medicine advocates identification of treatable traits, linking them to therapeutic approaches targeting genetic, immunological, environmental, and/or lifestyle factors in individual patients. The main "goal" of this personalised approach is to enable choosing a treatment which will be more likely to produce a beneficial response in the individual patient rather than a 'one size fits all' approach. The aim of the present review is to discuss different ways of phenotyping asthma and to provide a rationale for treatment algorithms based on principles of precision medicine.

Horses With Pasture Asthma Have Airway Remodeling That Is Characteristic of Human Asthma

Severe equine asthma, formerly recurrent airway obstruction (RAO), is the horse counterpart of human asthma, affecting horses maintained indoors in continental climates. Equine pasture asthma, formerly summer pasture RAO, is clinically similar but affects grazing horses during hot, humid conditions in the southeastern United States and United Kingdom. To advance translational relevance of equine pasture asthma to human asthma, histologic features of airway remodeling in human asthma were scored in lung lobes from 15 pasture asthma-affected and 9 control horses of mixed breeds. All noncartilaginous airways were scored using a standardized grading rubric (0-3) in hematoxylin and eosin (HE) and Movat's pentachrome-stained sections; 15 airways were chosen randomly from each lobe for analysis. Logistic regression identified disease, age, and lobe effects on probability of histologic outcomes. Airway smooth muscle (odds ratio [OR] = 2.5, P < .001), goblet cell hyperplasia/metaplasia (OR = 37.6, P < .0001), peribronchiolar elastic system fibers (OR = 4.2, P < .001), peribronchiolar fibrosis (OR = 3.8, P = .01), airway occlusion by mucus/inflammation (OR = 4.2, P = .04), and airway adventitial inflammation (OR = 3.0, P = .01) were significantly greater in diseased airways. A novel complex tissue disorganization, designated terminal bronchiolar remodeling, was overrepresented in diseased airways (OR = 3.7, P < .0001). Distribution of terminal bronchiolar remodeling corresponded to putative sites of air trapping in human asthma, at secondary pulmonary lobules. Age (>15 years) was an independent risk factor for increased peribronchiolar fibrosis, elastic system fibers, and terminal bronchiolar remodeling. Remodeling differed significantly between lung lobes, congruent with nonhomogeneous remodeling in human asthma. Equine pasture asthma recapitulates airway remodeling in human asthma in a manner not achieved in induced animal asthma models, endorsing its translational relevance for human asthma investigation.

Nonallergic Asthma and Its Severity: Biomarkers for Its Discrimination in Peripheral Samples

Asthma is a complex and heterogeneous respiratory disorder characterized by chronic airway inflammation. It has generally been associated with allergic mechanisms related to type 2 airway inflammation. Nevertheless, between 10 and 33% of asthmatic individuals have nonallergic asthma (NA). Several targeted treatments are in clinical development for patients with Th2 immune response, but few biomarkers are been defined for low or non-Th2-mediated inflammation asthma. We have recently defined by gene expression a set of genes as potential biomarkers of NA, mainly associated with disease severity: IL10, MSR1, PHLDA1, SERPINB2, CHI3L1, IL8, and PI3. Here, we analyzed their protein expression and specificity using sera and isolated peripheral blood mononuclear cells (PBMCs). First, protein quantification was carried out using ELISA (in sera) or Western blot (proteins extracted from PBMCs by Trizol procedure), depending on the biomarker in 30 healthy controls (C) subjects and 30 NA patients. A receiver operating characteristic curve analysis was performed by using the R program to study the specificity and sensitivity of the candidate biomarkers at a gene- and protein expression level. Four kinds of comparisons were performed: total NA group vs C group, severe NA patients vs C, moderate-mild NA patients vs C, and severe NA patients vs moderate-mild NA patients. We found that all the single genes showed good sensitivity vs specificity for some phenotypic discrimination, with CHI3L1 and PI3 exhibiting the best results for C vs NA: CHI3L1 area under the curve (AUC) (CI 95%): 0.95 (0.84-1.00) and PI3 AUC: 0.99 (0.98-1.00); C vs severe NA: PI3 AUC: 1 (0.99-1.00); and C vs moderate-mild NA: CHI3L1 AUC: 1 (0.99-1.00) and PI3 AUC: 0.99 (0.96-1.00). However, the results for discriminating asthma disease and severity with protein expression were better when two or three biomarkers were combined. In conclusion, individual genes and combinations of proteins have been evaluated as reliable biomarkers for classifying NA subjects and their severity. These new panels could be good diagnostic tests.

Precision Medicine in Targeted Therapies for Severe Asthma: Is There Any Place for "Omics" Technology?

According to the current guidelines, severe asthma still represents a controversial topic in terms of definition and management. The introduction of novel biological therapies as a treatment option for severe asthmatic patients paved the way to a personalized approach, which aims at matching the appropriate therapy with the different asthma phenotypes. Traditional asthma phenotypes have been decomposing by an increasing number of asthma subclasses based on functional and physiopathological mechanisms. This is possible thanks to the development and application of different omics technologies. The new asthma classification patterns, particularly concerning severe asthma, include an increasing number of endotypes that have been identified using new omics technologies. The identification of endotypes provides new opportunities for the management of asthma symptoms, but this implies that biological therapies which target inflammatory mediators in the frame of specific patterns of inflammation should be developed. However, the pathway leading to a precision approach in asthma treatment is still at its beginning. The aim of this review is providing a synthetic overview of the current asthma management, with a particular focus on severe asthma, in the light of phenotype and endotype approach, and summarizing the current knowledge about "omics" science and their therapeutic relevance in the field of bronchial asthma.

Genetic profiles of transcriptomic clusters of childhood asthma determine specific severe subtype

BACKGROUND

Previous studies have defined transcriptomic subtypes of adult asthma using samples of induced sputum and bronchial epithelium; however, those procedures are not readily applicable in the clinic, especially for childhood asthma.

OBJECTIVE

We aim to dissect the transcriptomic clusters of childhood asthma using highly variably expressed genes of peripheral blood mononuclear cells (PBMC) among patients.

METHODS

Gene expression of PBMC from 133 asthmatic children and 11 healthy controls was measured with Illumina microarrays. We applied the k-means clustering algorithm of 2048 genes to assign asthmatic children into clusters. Genes with differential expression between asthma clusters and healthy controls were used to investigate whether they could identify severe asthma of children and adults.

RESULTS

We identified 3 asthma clusters with distinct inflammatory profiles in peripheral blood. Cluster 1 had the highest eosinophil count. Cluster 2 showed lower counts of both eosinophils and neutrophils. Cluster 3 had the highest neutrophil count and the poorest treatment control. Compared with other patients, Cluster 3 exhibited a unique gene expression pattern which was associated with changes in the glucocorticoid signalling and activation of the T helper 1/T helper 17 (T_H 1/T_H 17) immune pathways. In the validation studies, an 84-gene signature could identify severe asthma in children on leucocytes, as well as severe asthma in adults on CD8⁺ T cells.

CONCLUSIONS AND CLINICAL RELEVANCE

Gene expression profiling of PBMC is useful for the identification of T_H 1/T_H 17-mediated asthma with poor treatment control. PBMC and CD8⁺ T cells could be important targets for the investigation and identification of severe asthma.

Human iPSC-MSCs prevent steroid-resistant neutrophilic airway inflammation via modulating Th17 phenotypes

BACKGROUND

Human induced pluripotent stem cells-derived mesenchymal stem cells (iPSC-MSCs) have been shown to be effective in Type 2 helper T cells (Th2)-dominant eosinophilic allergic airway inflammation. However, the role of iPSC-MSCs in Type 17 helper T cells (Th17)-dominant neutrophilic airway inflammation remains poorly studied. Therefore, this study was to explore the effects of iPSC-MSCs on an experimental mouse model of steroid-resistant neutrophilic airway inflammation and further determine the underlying mechanisms.

METHODS

A mouse model of neutrophilic airway inflammation was established using ovalbumin (OVA) and lipopolysaccharide (LPS). Human iPSC-MSCs were systemically administered, and the lungs or bronchoalveolar lavage fluids (BALF) were collected at 4 h and 48 h post-challenge. The pathology and inflammatory cell infiltration, the T helper cells, T helper cells-associated cytokines, nuclear transcription factors and possible signaling pathways were evaluated. Human CD4⁺ T cells were polarized to T helper cells and the effects of iPSC-MSCs on the differentiation of T helper cells were determined.

RESULTS

We successfully induced the mouse model of Th17 dominant neutrophilic airway inflammation. Human iPSC-MSCs but not dexamethasone significantly prevented the neutrophilic airway inflammation and decreased the levels of Th17 cells, IL-17A and p-STAT3. The mRNA levels of Gata3 and RORγt were also decreased with the treatment of iPSC-MSCs. We further confirmed the suppressive effects of iPSC-MSCs on the differentiation of human T helper cells.

CONCLUSIONS

iPSC-MSCs showed therapeutic potentials in neutrophilic airway inflammation through the regulation on Th17 cells, suggesting that the iPSC-MSCs could be applied in the therapy for the asthma patients with steroid-resistant neutrophilic airway inflammation.

Having concomitant asthma phenotypes is common and independently relates to poor lung function in NHANES 2007-2012

Background

Evidence for distinct asthma phenotypes and their overlap is becoming increasingly relevant to identify personalized and targeted therapeutic strategies. In this study, we aimed to describe the overlap of five commonly reported asthma phenotypes in US adults with current asthma and assess its association with asthma outcomes.

Methods

Data from the National Health and Nutrition Examination Surveys (NHANES) 2007-2012 were used (n = 30,442). Adults with current asthma were selected. Asthma phenotypes were: B-Eos-high [if blood eosinophils (B-Eos) ≥ 300/mm³]; FeNO-high (FeNO ≥ 35 ppb); B-Eos&FeNO-low (B-Eos < 150/mm³ and FeNO < 20 ppb); asthma with obesity (AwObesity) (BMI ≥ 30 kg/m²); and asthma with concurrent COPD. Data were weighted for the US population and analyses were stratified by age (< 40 and ≥ 40 years old).

Results

Of the 18,619 adults included, 1059 (5.6% [95% CI 5.1-5.9]) had current asthma. A substantial overlap was observed both in subjects aged < 40 years (44%) and ≥ 40 years (54%). The more prevalent specific overlaps in both age groups were AwObesity associated with either B-Eos-high (15 and 12%, respectively) or B-Eos&FeNO-low asthma (13 and 11%, respectively). About 14% of the current asthma patients were "non-classified". Regardless of phenotype classification, having concomitant phenotypes was significantly associated with (adjusted OR, 95% CI) ≥ 2 controller medications (2.03, 1.16-3.57), and FEV₁ < LLN (3.21, 1.74-5.94), adjusted for confounding variables.

Conclusions

A prevalent overlap of commonly reported asthma phenotypes was observed among asthma patients from the general population, with implications for objective asthma outcomes. A broader approach may be required to better characterize asthma patients and prevent poor asthma outcomes.

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.

Complex association patterns for inflammatory mediators in induced sputum from subjects with asthma

BACKGROUND

The release of various inflammatory mediators into the bronchial lumen is thought to reflect both the type and degree of airway inflammation, eosinophilic Th2, and Th9, or neutrophilic Th1, and Th17, in patients with asthma.

AIMS

We investigated whether cytokines and chemokines differed in sputum from subjects with more severe compared with milder asthma and whether unbiased factor analysis of cytokine and chemokine groupings indicates specific inflammatory pathways.

METHODS

Cell-free supernatants from induced sputum were obtained from subjects with a broad range of asthma severity (n = 158) and assessed using Milliplex^® Cytokines/Chemokine kits I, II and III, measuring 75 individual proteins. Each cytokine, chemokine or growth factor concentration was examined for differences between asthma severity groups, for association with leucocyte counts, and by factor analysis.

RESULTS

Severe asthma subjects had 9 increased and 4 decreased proteins compared to mild asthma subjects and fewer differences compared to moderate asthma. Twenty-six mediators were significantly associated with an increasing single leucocyte type: 16 with neutrophils (3 interleukins [IL], 3 CC chemokines, 4 CXC chemokines, 4 growth factors, TNF-α and CX3CL1/Fractalkine); 5 with lymphocytes (IL-7, IL-16, IL-23, IFN-α2 and CCL4/MIP1β); IL-15 and CCL15/MIP1δ with macrophages; IL-5 with eosinophils; and IL-4 and TNFSF10/TRAIL with airway epithelial cells. Factor analysis grouped 43 cytokines, chemokines and growth factors which had no missing data onto the first 10 factors, containing mixes of Th1, Th2, Th9 and Th17 inflammatory and anti-inflammatory proteins.

CONCLUSIONS

Sputum cytokines, chemokines and growth factors were increased in severe asthma, primarily with increased neutrophils. Factor analysis identified complex inflammatory protein interactions, suggesting airway inflammation in asthma is characterized by overlapping immune pathways. Thus, focus on a single specific inflammatory mediator or pathway may limit understanding the complexity of inflammation underlying airway changes in asthma and selection of appropriate therapy.

Role of sputum biomarkers in the management of asthma

PURPOSE OF REVIEW

Airway inflammation is considered to be a cardinal feature of asthma. However, the type of airway inflammation is heterogeneous and airway inflammation may even be absent. Biomarkers may help to identify the inflammatory phenotype or endotype, especially now the time has come that targeted therapies enter daily practice.

RECENT FINDINGS

Sputum biomarkers have increased our insights into the different inflammatory asthma phenotypes, their response to treatment and their association with progression of disease. New endotypes of type 2 driven inflammation were identified using a multidimensional approach. A specific mast cell subtype has been linked with type 2 driven inflammation and response to inhaled corticosteroids. Advances have been made with regard to sputum cytokine analysis and might also help to guide future treatment of severe asthma.

SUMMARY

Identifying the target population for biological therapies will not be possible without the use of biomarkers. Optimized, easy-to-apply, automated methods for sputum analysis (cellular content or soluble markers) need to be developed for implementation of sputum biomarkers in daily clinical practice.

T2-low asthma: current approach to diagnosis and therapy

PURPOSE OF REVIEW

Asthma is a heterogeneous disease not only on a clinical but also on a mechanistic level. For a long time, the molecular mechanisms of asthma were considered to be driven by type 2 helper T cells (Th2) and eosinophilic airway inflammation; however, extensive research has revealed that T2-low subtypes that differ from the dominant T2 paradigm are also common.

RECENT FINDINGS

Research into asthma pathways has led to the recognition that some asthma phenotypes show absence of T2 inflammation or alternate between T2 and non-T2 responses. Moreover, numerous immune response modifiers that block key-molecules such as interleukin (IL)-5, IL-13, and immunoglobulin E (IgE) have been identified. Along the way, these studies pointed that T2-low inflammation may also be responsible for lack of responsiveness to current treatment regimes.

SUMMARY

Asthma pathogenesis is characterized by two major endotypes, a T2-high featuring increased eosinophilic airway inflammation, and a T2-low endotype presenting with either neutrophilic or paucigranulocytic airway inflammation and showing greater resistance to steroids. This clearly presents an unmet therapeutic challenge. A precise definition and characterization of the mechanisms that drive this T2-low inflammatory response in each patient phenotype is necessary to help identify novel drug targets and design more effective and targeted treatments.

Type 2 Biomarkers and Prediction of Future Exacerbations and Lung Function Decline in Adult Asthma

BACKGROUND

Type 2 biomarkers that predict both likelihood of future severe exacerbations and response to mAb therapy in asthma would be useful clinically in identifying patients both at greater risk of hospitalization and most likely to benefit from mAb therapy.

OBJECTIVE

To describe the association between type 2 biomarkers, blood eosinophils, fractional exhaled nitric oxide (Feno), serum periostin, and serum IgE, and time to severe exacerbation in a broad asthma population.

METHODS

Participants from 2 adult asthma cohorts with baseline measurements of blood eosinophils, Feno, serum periostin, and serum IgE were reviewed after at least 12 months to obtain an exacerbation history, corroborated with general practitioner and hospital medical records. The association between baseline type 2 biomarkers and time to exacerbation was described by Cox proportional hazard ratios (HRs) using multivariate models.

RESULTS

A total of 212 participants were followed for a median (range) 3.8 (1.1-5.3) years; 67 of 212 (32%) had at least 1 severe exacerbation. The HRs (95% CI) of baseline type 2 biomarkers and time to exacerbation were as follows: blood eosinophils per 0.1 × 10⁹/L increase, 0.89 (0.76-1.05), P = .17; log Feno per 0.693 increase, 0.65 (0.52-0.81), P < .001; log serum periostin per 0.693 increase, 0.62 (0.35-1.09), P = .10; log serum IgE per 0.693 increase, 0.89 (0.80-1.00), P = .05.

CONCLUSIONS

The positive association between type 2 biomarkers and risk of severe exacerbations in populations with severe refractory asthma does not extend to mild and moderate asthma. Non-type 2 asthma may represent a phenotype associated with an increased risk of severe exacerbations in a broad asthma population.

Mechanisms and treatments for severe, steroid-resistant allergic airway disease and asthma

Severe, steroid-resistant asthma is clinically and economically important since affected individuals do not respond to mainstay corticosteroid treatments for asthma. Patients with this disease experience more frequent exacerbations of asthma, are more likely to be hospitalized, and have a poorer quality of life. Effective therapies are urgently required, however, their development has been hampered by a lack of understanding of the pathological processes that underpin disease. A major obstacle to understanding the processes that drive severe, steroid-resistant asthma is that the several endotypes of the disease have been described that are characterized by different inflammatory and immunological phenotypes. This heterogeneity makes pinpointing processes that drive disease difficult in humans. Clinical studies strongly associate specific respiratory infections with severe, steroid-resistant asthma. In this review, we discuss key findings from our studies where we describe the development of representative experimental models to improve our understanding of the links between infection and severe, steroid-resistant forms of this disease. We also discuss their use in elucidating the mechanisms, and their potential for developing effective therapeutic strategies, for severe, steroid-resistant asthma. Finally, we highlight how the immune mechanisms and therapeutic targets we have identified may be applicable to obesity-or pollution-associated asthma.

Plasma miR-199a-5p is increased in neutrophilic phenotype asthma patients and negatively correlated with pulmonary function

Objective

We investigated the relationship between plasma miRNAs levels and inflammatory characteristics in asthmatic patients.

Methods

Eligible adults with untreated asthma (n = 35) underwent a clinical assessment, sputum induction, and assessment of pulmonary function test and Asthma Control Test (ACT) scores. Asthma phenotypes were defined using the sputum cell count. miR-199a-5p expression was measured using quantitative real-time polymerase chain reaction (qPCR). Lipopolysaccharide (LPS) stimulation was used to detect miR-199a-5p secretion from peripheral blood-derived neutrophil, lymphocyte, macrophage and BEAS-2B cells. The correlation of miR-199a-5p expression with clinical parameters was analyzed using multiple linear regression analysis. In silico analysis predicted the target genes and signaling pathway of miR-199a-5p. Transfection of miR-199a-5p mimics in human airway smooth muscle cells (HASMCs) was performed in vitro.

Results

The miRNA-199a-5p levels in plasma and sputum increased significantly in patients with neutrophilic asthma compared to healthy subjects (ps = 0.014 and 0.006, respectively). Expression of miR-199a-5p in the plasma of asthmatic patients positively correlated with sputum miR-199a-5p expression (r = 0.511, p = 0.021). The miR-199a-5p level was only elevated with LPS stimulation in neutrophils but not macrophages, lymphocytes, or epithelial cells from healthy controls (p < 0.01). miR-199a-5p expression increased in response to LPS (p = 0.005) and LPS combined with IL-4 (p = 0.003), but not IL-4 alone. However, peripheral neutrophils from eosinophilic asthma patients did not respond to LPS with increased miR-199a-5p expression (n = 5, p > 0.05) in contrast to the significant response from neutrophilic patients (n = 4, p < 0.0001). miR-199a-5p negatively correlated with FEV_1, FVC and PEF (r = -0.377, p = 0.026; r = -0.419, p = 0.012; and r = -0.392, p = 0.024, respectively). Multivariate correlation analysis confirmed that the plasma miR-199a-5p levels negatively correlated with FEV₁ in patients with asthma (Adjusted R² = 0.164, p = 0.015). In silico analysis suggested that the WNT signaling pathway participates in miR-199a-5p mediation of smooth muscle cell hypertrophy. In vitro experiment, miR-199a-5p mimics inhibited the protein expressions of WNT2 and WNT4, decreased the c-myc expression and dramatically increased the Sm-MHC expression in HASMCs.

Conclusion

Plasma miR-199a-5p was increased in neutrophilic asthma and negatively correlated with pulmonary function, which suggests that miR-199a-5p actively contributes to disease pathogenesis by modulating the inflammatory process and transferring the signal from inflammatory cells to structure cells.

Asthma

Asthma-one of the most common chronic, non-communicable diseases in children and adults-is characterised by variable respiratory symptoms and variable airflow limitation. Asthma is a consequence of complex gene-environment interactions, with heterogeneity in clinical presentation and the type and intensity of airway inflammation and remodelling. The goal of asthma treatment is to achieve good asthma control-ie, to minimise symptom burden and risk of exacerbations. Anti-inflammatory and bronchodilator treatments are the mainstay of asthma therapy and are used in a stepwise approach. Pharmacological treatment is based on a cycle of assessment and re-evaluation of symptom control, risk factors, comorbidities, side-effects, and patient satisfaction by means of shared decisions. Asthma is classed as severe when requiring high-intensity treatment to keep it under control, or if it remains uncontrolled despite treatment. New biological therapies for treatment of severe asthma, together with developments in biomarkers, present opportunities for phenotype-specific interventions and realisation of more personalised treatment. In this Seminar, we provide a clinically focused overview of asthma, including epidemiology, pathophysiology, clinical diagnosis, asthma phenotypes, severe asthma, acute exacerbations, and clinical management of disease in adults and children older than 5 years. Emerging therapies, controversies, and uncertainties in asthma management are also discussed.

Targeted Therapy for Severe Asthma: Identifying the Right Patients

Asthma affects over 300 million people worldwide. Most asthmatics are well controlled with inhaled corticosteroids and long-acting beta-agonists; however, a proportion of patients are unresponsive and attain limited disease control. This group represents a considerable healthcare and financial burden, particularly patients who experience frequent exacerbations and require hospital admission. Development of new biological agents and disease biomarkers has provided novel avenues for treatment. These treatments have been highly successful, reducing exacerbations and yielding modest improvements in quality of life and lung function. However, only a proportion of severe asthmatics respond to this targeted treatment, highlighting the heterogeneity of severe asthma. One of the first biological therapies targeted immunoglobulin E (IgE) and demonstrated modest benefit but could only be used in a subgroup of patients. Recent research has shown that treatment aimed at the T helper-2-(Th₂)-high pathways and cytokines such as interleukin (IL)-5, IL-4, and IL-13 may also be effective in another partially overlapping subgroup. A blood eosinophil count over a defined threshold (generally ≥300 cells/μl) was a reliable biomarker and identified the majority of responders in this group. Further discovery and validation of biological markers to define asthmatic phenotypes that may benefit from biological treatments remain an area of intense interest and research. We review the latest information pertaining to biological agents and demonstrate how patient responders may potentially be identified for treatment.

New and emerging drug treatments for severe asthma

Asthma is a common chronic inflammatory condition of the airways affecting over 300 million people world-wide. In 5%-10% of cases, it is severe, with disproportionate healthcare resource utilization including costs associated with frequent exacerbations and the long-term health effects of systemic steroids. Characterization of inflammatory pathways in severe asthma has led to the development of targeted biological and small molecule therapies which aim to achieve disease control while minimizing corticosteroid-associated morbidity. Herein, we review currently licensed agents and those in development, and speculate how drug therapy for severe asthma might evolve and impact on clinical outcomes in the near future.

Differential Regulation of Zfp30 Expression in Murine Airway Epithelia Through Altered Binding of ZFP148 to rs51434084

Neutrophil chemotaxis to the airways is a key aspect of host response to microbes and a feature of multiple pulmonary diseases including asthma. Tight regulation of this recruitment is critical to prevent unwanted host tissue damage and inflammation. Using a mouse (Mus musculus) model of asthma applied to the Collaborative Cross population, we previously identified a lung gene expression quantitative trait locus (eQTL) for Zinc finger protein 30 (Zfp30) that was also a QTL for neutrophil recruitment and the hallmark neutrophil chemokine CXCL1. The Zfp30 eQTL is defined by three functionally distinct haplotypes. In this study, we searched for causal genetic variants that underlie the Zfp30 eQTL to gain a better understanding of this candidate repressor's regulation. First, we identified a putative regulatory region spanning 500 bp upstream of Zfp30, which contains 10 SNPs that form five haplotypes. In reporter gene assays in vitro, these haplotypes recapitulated the three previously identified in vivo expression patterns. Second, using site-directed mutagenesis followed by reporter gene assays, we identified a single variant, rs51434084, which explained the majority of variation in expression between two out of three haplotype groups. Finally, using a combination of in silico predictions and electrophoretic mobility shift assays, we identified ZFP148 as a transcription factor that differentially binds to the Zfp30 promoter region harboring rs51434084. In conclusion, we provide evidence in support of rs51434084 being a causal variant for the Zfp30 eQTL, and have identified a mechanism by which this variant alters Zfp30 expression, namely differential binding of ZFP148.

Risk factors of postoperative pulmonary complications in patients with asthma and COPD

Background

Postoperative pulmonary complications (PPC) in patients with pulmonary diseases remain to be resolved clinical issue. However, most evidence regarding PPC has been established more than 10 years ago. Therefore, it is necessary to evaluate perioperative management using new inhalant drugs in patients with obstructive pulmonary diseases.

Methods

April 2014 through March 2015, 346 adult patients with pulmonary diseases (257 asthma, 89 chronic obstructive pulmonary disease (COPD)) underwent non-pulmonary surgery except cataract surgery in our university hospital. To analyze the risk factors for PPC, we retrospectively evaluated physiological backgrounds, surgical factors and perioperative specific treatment for asthma and COPD.

Results

Finally, 29 patients with pulmonary diseases (22 asthma, 7 COPD) had PPC. In patients with asthma, smoking index (≥ 20 pack-years), peripheral blood eosinophil count (≥ 200/mm³) and severity (Global INitiative for Asthma(GINA) STEP ≥ 3) were significantly associated with PPC in the multivariate logistic regression analysis [odds ratio (95% confidence interval) = 5.4(1.4–20.8), 0.31 (0.11–0.84) and 3.2 (1.04–9.9), respectively]. In patients with COPD, age, introducing treatment for COPD, upper abdominal surgery and operation time (≥ 5 h) were significantly associated with PPC [1.18 (1.00–1.40), 0.09 (0.01–0.81), 21.2 (1.3–349) and 9.5 (1.2–77.4), respectively].

Conclusions

History of smoking or severe asthma is a risk factor of PPC in patients with asthma, and age, upper abdominal surgery, or long operation time is a risk factor of PPC in patients with COPD. Adequate inhaled corticosteroids treatment in patients with eosinophilic asthma and introducing treatment for COPD in patients with COPD could reduce PPCs.

Inhibiting Inflammasomes with Small Molecules

Modulation of inflammasomes has tremendous therapeutic potential and is hotly pursued by industry and academia alike. Indeed a growing number of patents are emerging to protect the intellectual property in valuable compound classes. This chapter focusses specifically on the suite of small-molecule NLRP3 inflammasome inhibitors published, as specific modulation of other inflammasomes is not yet well established. Synthetic molecules, known drugs and natural product NLRP3 modulators will be detailed. Some of the molecular classes discussed have been extensively characterised through cell-based screening, pharmacokinetic profiling and therapeutic proof of concept animal models. However, many inhibitors lack rigorous studies and/or have multiple activities of which NLRP3 modulation is only one. While this is not intended as an exhaustive list, it should give an impression of the range of structures and strategies that are being used, alongside challenges encountered, in an effort to exploit the significant therapeutic benefits of targeting inflammasomes.