Advances in asthma in 2017: Mechanisms, biologics, and genetics

Benralizumab: from tissue distribution to eosinophilic cytotoxicity up to potential immunoregulation

INTRODUCTION

Benralizumab, a monoclonal IgG antibody, has emerged as a key therapeutic agent in severe asthma by specifically targeting eosinophils, pivotal cells that drive inflammation and tissue damage. Over the past two decades, the availability of such targeted therapies has allowed patients to achieve better disease control. Real-world evidence has consistently demonstrated the effectiveness of benralizumab in managing severe asthma.

AREAS COVERED

This paper discusses the kinetic and potential mechanism of action of benralizumab beyond the well-known antibody-dependent cell-mediated cytotoxicity involving natural killer cells.

EXPERT OPINION

The available data so far clearly show that reducing eosinophils, one of the main drivers of inflammation and tissue damage in SA, accounts for clinical benefits to these patients. Benralizumab is able to directly reduce tissue levels of eosinophils via multiple mechanisms, and additionally, it is potentially able to modulate the innate immune response. The complex and unique multiple modes of action of benralizumab and its pharmacokinetic features, seem to be the milestone on which the effectiveness of benralizumab is founded.

Asthma remission one, none and one-hundred thousand: the relevance of the patient's view

OBJECTIVE

Achieving remission in severe asthma holds paramount importance in elevating patient quality of life and reducing both individual and societal burdens associated with this chronic condition. This study centers on identifying pivotal patient-relevant endpoints through standardized, reproducible methods, while also developing a patient-centric definition of remission, essential for effective disease management.

METHODS

A discrete choice experiment (DCE) was conducted to assess patients' perceptions on the four primary criteria for defining severe asthma remission, as outlined by the SANI survey. Additionally, it investigated the correlation between these perceptions and improvements in the doctor-patient therapeutic alliance during treatment decision-making.

RESULTS

249 patients (70% aged between 31-60, 59% women and 82% without other pathologies requiring corticosteroids) prioritize the use of oral corticosteroids (OCS, 48%) and the Asthma Control Test (ACT, 27%) in defining their condition, ranking these above lung function and exacerbations. This preference for OCS stems from its direct role in treatment, tangible tracking, immediate symptom relief, and being a concrete measure of disease severity compared to the less predictable and quantifiable exacerbations.

CONCLUSIONS

This study explores severe asthma remission from patients' perspectives using clinician-evaluated parameters. The DCE revealed that most patients highly value OCS and the ACT, prefer moderate improvement, and avoid cortisone cycles. No definitive preference was found for lung function status. Integrating patient-reported information with professional insights is crucial for effective management and future research. Personalized treatment plans focusing on patient preferences, adherence, and alternative therapies aim to achieve remission and enhance quality of life.

CLDN1 silencing suppresses the proliferation and migration of airway smooth muscle cells by modulating MMP14

Airway remodeling is an important pathologic factor in the progression of asthma. Abnormal proliferation and migration of airway smooth muscle cells (ASMCs) are important pathologic mechanisms in severe asthma. In the current study, claudin-1 (CLDN1) was identified as an asthma-related gene and was upregulated in ASMCs stimulated with platelet-derived growth factor BB (PDGF-BB). Cell counting kit-8 and EdU assays were used to evaluate cell proliferation, and transwell assay was carried out to analyze cell migration and invasion. The levels of inflammatory factors were detected using enzyme-linked immunosorbent assay. The results showed that CLDN1 knockdown inhibited the proliferation, migration, invasion, and inflammation of ASMCs treated with PDGF-BB, whereas overexpression of CLDN1 exhibited the opposite effects. Protein-protein interaction assay and co-immunoprecipitation revealed that CLDN1 directly interacted with matrix metalloproteinase 14 (MMP14). CLDN1 positively regulated MMP14 expression in asthma, and MMP14 overexpression reversed cell proliferation, migration, invasion, and inflammation induced by silenced CLDN1. Taken together, CLDN1 promotes PDGF-BB-induced cell proliferation, migration, invasion, and inflammatory responses of ASMCs by upregulating MMP14 expression, suggesting a potential role for CLDN1 in airway remodeling in asthma.

Unraveling the link between PTBP1 and severe asthma through machine learning and association rule mining method

Severe asthma is a chronic inflammatory airway disease with great therapeutic challenges. Understanding the genetic and molecular mechanisms of severe asthma may help identify therapeutic strategies for this complex condition. RNA expression data were analyzed using a combination of artificial intelligence methods to identify novel genes related to severe asthma. Through the ANOVA feature selection approach, 100 candidate genes were selected among 54,715 mRNAs in blood samples of patients with severe asthmatic and healthy groups. A deep learning model was used to validate the significance of the candidate genes. The accuracy, F1-score, AUC-ROC, and precision of the 100 genes were 83%, 0.86, 0.89, and 0.9, respectively. To discover hidden associations among selected genes, association rule mining was applied. The top 20 genes including the PTBP1, RAB11FIP3, APH1A, and MYD88 were recognized as the most frequent items among severe asthma association rules. The PTBP1 was found to be the most frequent gene associated with severe asthma among those 20 genes. PTBP1 was the gene most frequently associated with severe asthma among candidate genes. Identification of master genes involved in the initiation and development of asthma can offer novel targets for its diagnosis, prognosis, and targeted-signaling therapy.

Allergen-induced DNA release by the airway epithelium amplifies type 2 immunity

BACKGROUND

Alternaria alternata and house dust mite exposure evokes IL-33 secretion from the airway epithelium, which functions as an alarmin to stimulate type 2 immunity. Extracellular DNA (eDNA) is also an alarmin that intensifies inflammation in cystic fibrosis, chronic obstructive pulmonary disease, and asthma.

OBJECTIVE

We investigated the mechanisms underlying allergen-evoked DNA mobilization and release from the airway epithelium and determined the role of eDNA in type 2 immunity.

METHODS

Human bronchial epithelial (hBE) cells were used to characterize allergen-induced DNA mobilization and extracellular release using comet assays to measure DNA fragmentation, Qubit double-stranded DNA assays to measure DNA release, and DNA sequencing to determine eDNA composition. Mice were used to investigate the role of eDNA in type 2 immunity.

RESULTS

Alternaria extract rapidly induces mitochondrial and nuclear DNA release from human bronchial epithelial cells, whereas house dust mite extract induces mitochondrial DNA release. Caspase-3 is responsible for nuclear DNA fragmentation and becomes activated after cleavage by furin. Analysis of secreted nuclear DNA showed disproportionally higher amounts of promotor and exon sequences and lower intron and intergenic regions compared to predictions of random DNA fragmentation. In mice, Alternaria-induced type 2 immune responses were blocked by pretreatment with a DNA scavenger. In caspase-3-deficient mice, Alternaria-induced DNA release was suppressed. Furthermore, intranasal administration of mouse genomic DNA with Alternaria amplified secretion of IL-5 and IL-13 into bronchoalveolar lavage fluid while DNA alone had no effect.

CONCLUSION

These findings highlight a novel, allergen-induced mechanism of rapid DNA release that amplifies type 2 immunity in airways.

Glucocorticoids and COVID-19

Coronavirus Disease 19 (COVID-19) is associated with high morbidity and mortality rates globally, representing the greatest health and economic challenge today. Several drugs are currently approved for the treatment of COVID-19. Among these, glucocorticoids (GCs) have received particular attention due to their anti-inflammatory and immunosuppressive effects. In fact, GC are widely used in current clinical practice to treat inflammatory, allergic and autoimmune diseases. Major mechanisms of GC action include inhibition of innate and adaptive immune activity. In particular, an important role is played by the inhibition of pro-inflammatory cytokines and chemokines, and the induction of proteins with anti-inflammatory activity. Overall, as indicated by various national and international regulatory agencies, GCs are recommended for the treatment of COVID-19 in patients requiring oxygen therapy, with or without mechanical ventilation. Regarding the use of GCs for the COVID-19 treatment of non-hospitalized patients at an early stage of the disease, many controversial studies have been reported and regulatory agencies have not recommended their use. The decision to start GC therapy should be based not only on the severity of COVID-19 disease, but also on careful considerations of the benefit/risk profile in individual patients, including monitoring of adverse events. In this review we summarize the effects of GCs on the major cellular and molecular components of the inflammatory/immune system, the benefits and the adverse common reactions in the treatment of inflammatory/autoimmune diseases, as well as in the management of COVID-19.

Clusters Based on Immune Markers in a Lithuanian Asthma Cohort Study

OBJECTIVE

Asthma is divided into various distinct phenotypes on the basis of clinical characteristics, physiological findings, and triggers, and phenotyping is usually performed in a hypothesis-driven univariate manner. However, phenotyping can also be performed using computer algorithms to evaluate hypotheses-free relationships among many clinical and biological characteristics. We aimed to identify asthma phenotypes based on multiple demographic, clinical, and immunological characteristics.

METHODS

Cluster analysis in R v3.5.0 was performed using asthma patient data. A total of 170 adult patients with asthma (diagnosed according to the GINA recommendations) were recruited to the study. All patients completed questionnaires about their smoking history and underwent physical examination, spirometry, skin-prick test, blood sample collection to evaluate peripheral blood cell counts and serum IgE, periostin, and interleukin (IL)-33 levels, as well as body mass index measurements. Data normality was checked with histograms and QQ plots. Hierarchical clustering was performed using Ward's linkage with Ward's clustering criterion. The optimal number of clusters was validated using the Dunn criterion as well as by comparing different clustering algorithms using the clValid package.

RESULTS

Three clusters characterizing asthma phenotypes were identified: (1) early-onset, highly atopic, and eosinophilic asthma associated with male sex and high levels of IL-33 and periostin; (2) late-onset, eosinophilic asthma associated with female sex and low levels of IL-33 and periostin; and (3) late-onset, obese, neutrophilic asthma associated with female sex, persistent airway obstruction, and very low IL-33 and periostin levels.

Trends and age-period-cohort effects on incidence and mortality of asthma in Sichuan Province, China, 1990-2019

Background

The provinces in western China have undergone rapid urbanization and industrialization, particularly since the Chinese government launched the Great Western Development Strategy in 2000. We examined the time trends and contributions of age, period, and cohort effects to asthma incidence and mortality in Sichuan Province, a populous province in western China, from 1990 to 2019.

Methods

The data of Sichuan Province from 1990 to 2019 were extracted from the Global Burden of Disease study 2019. Trends and average annual percentage change were estimated using joinpoint regression. Age, period, and cohort effects were estimated using an age-period-cohort model with the intrinsic estimator method.

Results

In the latest period (2015–2019), the highest incidence of asthma was 2004.49/100,000 in children aged < 5 years, and the highest mortality rate was 22.04/100,000 for elderly people aged > 80 years. Age-standardized rates generally remained stable (95% confidence interval [CI]  − 0.21, 0.11) for incidence and declined by 4.74% (95% CI − 5.09, − 4.39) for mortality over the last 30 years. After controlling for other effects, the age effect on asthma showed that the incidence rate ratio (RR) was highest in the < 5 years age group, and the mortality RR was highest in the > 80 years age group. The period effect on incidence and mortality decreased from 1990 to 2019, respectively. A cohort effect was found the incidence RR increased slowly from the early birth cohorts to the later birth cohorts, especially after the 2005 birth cohort, whereas the mortality RR continued to decline.

Conclusions

There was a significant effect of older age on the asthma mortality rate over the last 30 years, and the incidence rate in children aged < 5 years increased. The relative risk of asthma incidence in the later birth cohorts increased. Effective preventive measures and public health policies should be to protect children and elderly people from potentially harmful chronic diseases.

Local IL-10 replacement therapy was effective for steroid-insensitive asthma in mice

Subgroups of patients with severe asthma showing marked increases in sputum eosinophils and/or neutrophils are insensitive to corticosteroids. Previous reports have shown that exogenous administration of an anti-inflammatory cytokine, interleukin (IL)-10 negatively regulated both eosinophilic and neutrophilic migration into tissues. The objective of this study was to elucidate whether intratracheal IL-10 administration suppresses asthmatic responses in a steroid-insensitive model of mice. Ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at 500 µg/animal four times. Dexamethasone (1 mg/kg, intraperitoneal) or IL-10 (25 ng/mouse, intratracheal) was administered during the multiple challenges. The number of leukocytes, expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and IL-10 receptor in the lung, and the development of airway remodeling and hyperresponsiveness were evaluated after the fourth challenge. Consistent with our previous study, dexamethasone hardly suppressed the development of airway remodeling and hyperresponsiveness. Although intratracheal IL-10 administration did not affect the development of airway remodeling, the infiltration of eosinophils and neutrophils, and the development of airway hyperresponsiveness were significantly inhibited. Moreover, IL-10 administration significantly decreased the numbers of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, which express IL-10 receptor 1, even though neither production of eosinophilic nor neutrophilic cytokines in the lung was inhibited. Therefore, IL-10 can suppress eosinophil and neutrophil infiltration by inhibiting the proliferation of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, resulting in inhibition of airway hyperresponsiveness in steroid-insensitive asthmatic mice. IL-10 replacement therapy may be clinically useful for the treatment of steroid-insensitive asthma.

Immune Regulation of Heme Oxygenase-1 in Allergic Airway Inflammation

Heme oxygenase-1 (HO-1) is not only a rate-limiting enzyme in heme metabolism but is also regarded as a protective protein with an immunoregulation role in asthmatic airway inflammation. HO-1 exerts an anti-inflammation role in different stages of airway inflammation via regulating various immune cells, such as dendritic cells, mast cells, basophils, T cells, and macrophages. In addition, the immunoregulation role of HO-1 may differ according to subcellular locations.

Nuclear factor-kappa B (NF-κB) inhibition as a therapeutic target for plant nutraceuticals in mitigating inflammatory lung diseases

Nutraceuticals are dietary supplements that are used to improve health, postpone aging, prevent illnesses, and maintain the human body's correct functioning. Nutraceuticals are now garnering a lot of interest because of their nutritional and therapeutic benefits. The research indicating the relevance of nutraceuticals as a possible therapeutic candidate against inflammatory lung disease was covered in this review. Nowadays, inflammatory lung diseases such as chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, asthma, pneumonia, lung cancer, becoming highly dreadful because of their associated fatality. Inflammation is one of the cores and common factors of these diseases which is mainly associated with nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation, NF-κB p65 and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) phosphorylation, and initiation of the signaling pathway of the NF-κB. The secondary metabolites from natural sources are the active component that attenuates NF-κB and the associated pathway that inhibits inflammation in lung diseases. Nutraceuticals belonging to the chemical category polyphenols, alkaloids, terpenoids, flavonoids, tannins have the potential to combat the NF-κB pathway. Accordingly, this review discusses the medical value of nutraceuticals briefly and their ability to mitigate various inflammatory lung diseases through targeting inhibition of NF-κB.

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

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

Atopic Neutrophils Prevent Postviral Airway Disease

Respiratory syncytial virus (RSV) infection in infancy is associated with increased risk of asthma, except in those with allergic disease at the time of infection. Using house dust mite allergen, we examined the effect of pre-existing atopy on postviral airway disease using Sendai virus in mice, which models RSV infection in humans. Sendai virus drives postviral airway disease in nonatopic mice; however, pre-existing atopy protected against the development of airway disease. This protection depended upon neutrophils, as depletion of neutrophils at the time of infection restored the susceptibility of atopic mice to postviral airway disease. Associated with development of atopy was an increase in polymorphonuclear neutrophil-dendritic cell hybrid cells that develop in Th2 conditions and demonstrated increased viral uptake. Systemic inhibition of IL-4 reversed atopic protection against postviral airway disease, suggesting that increased virus uptake by neutrophils was IL-4 dependent. Finally, human neutrophils from atopic donors were able to reduce RSV infection of human airway epithelial cells in vitro, suggesting these findings could apply to the human. Collectively our data support the idea that pre-existing atopy derives a protective neutrophil response via potential interaction with IL-4, preventing development of postviral airway disease.

Role of STAT3 Transcription Factor in Pathogenesis of Bronchial Asthma

Bronchial asthma is a heterogeneous chronic inflammatory disease of airways. The studies of molecular and cellular mechanisms of bronchial asthma have established that a wide range of immune (T and B cells, eosinophils, neutrophils, macrophages, etc.) and structural (epithelial and endothelial) cells are involved in its pathogenesis. These cells are activated in response to external stimuli (bacteria, viruses, allergens, and other pollutants) and produce pro-inflammatory factors (cytokines, chemokines, metalloproteinases, etc.), which ultimately leads to the initiation of pathological processes in the lungs. Genes encoding transcription factors of the STAT family (signal transducer and activator of transcription), that includes seven representatives, are involved in the cell activation. Recent studies have shown that the transcription factor STAT3 plays an important role in the activation of the abovementioned cells, thus contributing to the development of asthma. In animal studies, selective inhibition of STAT3 significantly reduces the severity of lung inflammation, which indicates its potential as a therapeutic target. In this review, we describe the mechanisms of STAT3 activation and its role in polarization of Th2/Th17 cells and M2 macrophages, as well as in the dysfunction of endothelial cells, which ultimately leads to development of bronchial asthma symptoms, such as infiltration of neutrophils and eosinophils into the lungs, bronchial hyperreactivity, and the respiratory tract remodeling.

The Role of Glucocorticoids in Inflammatory Diseases

For more than 70 years, glucocorticoids (GCs) have been a powerful and affordable treatment option for inflammatory diseases. However, their benefits do not come without a cost, since GCs also cause side effects. Therefore, strong efforts are being made to improve their therapeutic index. In this review, we illustrate the mechanisms and target cells of GCs in the pathogenesis and treatment of some of the most frequent inflammatory disorders affecting the central nervous system, the gastrointestinal tract, the lung, and the joints, as well as graft-versus-host disease, which often develops after hematopoietic stem cell transplantation. In addition, an overview is provided of novel approaches aimed at improving GC therapy based on chemical modifications or GC delivery using nanoformulations. GCs remain a topic of highly active scientific research despite being one of the oldest class of drugs in medical use.

Mechanisms and biomarkers of airway epithelial cell damage in asthma: A review

Bronchial asthma is a heterogeneous disease with complex pathological mechanisms representing different phenotypes, including severe asthma. The airway epithelium is a major site of complex pathological changes in severe asthma due, in part, to activation of inflammatory and immune mechanisms in response to noxious agents. Current imaging procedures are unable to accurately measure epithelial and airway remodeling. Damage of airway epithelial cells occurs is linked to specific phenotypes and endotypes which provides an opportunity for the identification of biomarkers reflecting epithelial, and airway, remodeling. Identification of patients with more severe epithelial disruption using biomarkers may also provide personalised therapeutic opportunities and/or markers of successful therapeutic intervention. Here, we review the evidence for ongoing epithelial cell dysregulation in the pathogenesis of asthma, the sentinel role of the airway epithelium and how understanding these molecular mechanisms provides the basis for the identification of candidate biomarkers for asthma prediction, prevention, diagnosis, treatment and monitoring.

The central role of IL-33/IL-1RL1 pathway in asthma: From pathogenesis to intervention

Interleukin-33 (IL-33), a member of the IL-1 family, and its cognate receptor, Interleukin-1 receptor like-1 (IL-1RL1 or ST2), are susceptibility genes for childhood asthma. In response to cellular damage, IL-33 is released from barrier tissues as an 'alarmin' to activate the innate immune response. IL-33 drives type 2 responses by inducing signalling through its receptor IL-1RL1 in several immune and structural cells, thereby leading to type 2 cytokine and chemokine production. IL-1RL1 gene transcript encodes different isoforms generated through alternative splicing. Its soluble isoform, IL-1RL1-a or sST2, acts as a decoy receptor by sequestering IL-33, thereby inhibiting IL1RL1-b/IL-33 signalling. IL-33 and its receptor IL-1RL1 are therefore considered as putative biomarkers or targets for pharmacological intervention in asthma. This review will provide an overview of the genetics and biology of the IL-33/IL-1RL1 pathway in the context of asthma pathogenesis. It will discuss the potential and complexities of targeting the cytokine or its receptor, how genetics or biomarkers may inform precision medicine for asthma targeting this pathway, and the possible positioning of therapeutics targeting IL-33 or its receptor in the expanding landscape of novel biologicals applied in asthma management.

The intersect of genetics, environment, and microbiota in asthma-perspectives and challenges

In asthma, a significant portion of the interaction between genetics and environment occurs through microbiota. The proposed mechanisms behind this interaction are complex and at times contradictory. This review covers recent developments in our understanding of this interaction: the "microbial hypothesis" and the "farm effect"; the role of endotoxin and genetic variation in pattern recognition systems; the interaction with allergen exposure; the additional involvement of host gut and airway microbiota; the role of viral respiratory infections in interaction with the 17q21 and CDHR3 genetic loci; and the importance of in utero and early-life timing of exposures. We propose a unified framework for understanding how all these phenomena interact to drive asthma pathogenesis. Finally, we point out some future challenges for continued research in this field, in particular the need for multiomic integration, as well as the potential utility of asthma endotyping.

Asthma and stroke: a narrative review

Asthma is a heterogeneous disease, usually characterized by chronic airway inflammation, bronchial reversible obstruction and hyperresponsiveness to direct or indirect stimuli. It is a severe disease causing approximately half a million deaths every year and thus possessing a significant public health burden. Stroke is the second leading cause of death and a major cause of disability worldwide. Asthma and asthma medications may be a risk factors for developing stroke. Nevertheless, since asthma is associated with a variety of comorbidities, such as cardiovascular, metabolic and respiratory, the increased incidence of stroke in asthma patients may be due to a confounding effect. The purpose of this review is to analyze the complex relationship between asthma and stroke.

Modern View of Neutrophilic Asthma Molecular Mechanisms and Therapy

For a long time asthma was commonly considered as a homogeneous disease. However, recent studies provide increasing evidence of its heterogeneity and existence of different phenotypes of the disease. Currently, classification of asthma into several phenotypes is based on clinical and physiological features, anamnesis, and response to therapy. This review describes five most frequently identified asthma phenotypes. Neutrophilic asthma (NA) deserves special attention, since neutrophilic inflammation of the lungs is closely associated with severity of the disease and with the resistance to conventional corticosteroid therapy. This review focuses on molecular mechanisms of neutrophilic asthma pathogenesis and on the role of Th1- and Th17-cells in the development of this type of asthma. In addition, this review presents current knowledge of neutrophil biology. It has been established that human neutrophils are represented by at least three subpopulations with different biological functions. Therefore, total elimination of neutrophils from the lungs can result in negative consequences. Based on the new knowledge of NA pathogenesis and biology of neutrophils, the review summarizes current approaches for treatment of neutrophilic asthma and suggests new promising ways to treat this type of asthma that could be developed in future.

Biomarkers of Bronchial Asthma

Asthma is a complex disease with a variable course. Efforts to identify biomarkers to predict asthma severity, the course of disease and response to treatment have not been very successful so far. Biomarker research has expanded greatly with the advancement of molecular research techniques. An ideal biomarker should be suitable to identify the disease as well the specific endotype/phenotype, useful in the monitoring of the disease and to determine the prognosis, easily to obtain with minimum discomfort or risk to the patient. An ideal biomarker should be suitable to identify the disease as well the specific endotype/phenotype, useful in the monitoring of the disease and to determine the prognosis, easily to obtain with minimum discomfort or risk to the patient - exhaled breath analysis, blood cells and serum biomarkers, sputum cells and mediators and urine metabolites could be potential biomarkers of asthma bronchiale. Unfortunately, at the moment, an ideal biomarker doesn't exist and the overlap between the biomarkers is a reality. Using panels of biomarkers could improve probably the identification of asthma endotypes in the era of precision medicine.

Toll-Like Receptor Characterization Correlates with Asthma and Is Predictive of Diagnosis

Toll-like receptors (TLRs) play crucial roles in the recognition of invading pathogens and the immune system. However, the effect of TLRs in asthma is still not fully known. This study was performed to better understand the role of TLR signatures in asthma. Blood samples from case-control studies (study 1: 348 asthmas and 39 normal controls and validation study 2: 411 asthmas and 87 normal controls) were enrolled. The single-sample gene set enrichment analysis method was performed to quantify the abundance of 21 TLR signatures. Gene ontology analysis and pathway function analysis were conducted for functional analysis, and a protein-protein interaction network was constructed. The area under the curve (AUC) value was used to assess the diagnostic capacity. In this study, TLR2/TLR3/TLR4 pathway, MyD88-dependent/independent TLR pathway, positive regulation of TLR4 pathway, and TLR binding signatures were significantly higher in asthma. Functional analysis showed that biological processes and pathways were still involved in TLR cascades and TLR signaling pathway. Eleven hub TLR-related genes were identified, and further validation demonstrated that the combination of TLR-related genes was a good diagnostic biomarker for asthma (AUC = 0.8). Our study provided more insight into the underlying immune mechanism of how TLR signatures affected asthma. The use of the easy-to-apply TLR-related genes might represent a promising blood-based biomarker for early detection of asthma.

Small RNA Sequencing Reveals Exosomal miRNAs Involved in the Treatment of Asthma by Scorpio and Centipede

Asthma is a common respiratory disease with inflammation in the lungs. Exosomes and microRNAs (miRNAs) play crucial role in inflammation, whereas the role of exosomal miRNA in asthma remains unknown. Here, we aimed to identify the key exosomal miRNAs and their underlying mechanisms involved in scorpio and centipede (SC) treatment in asthma. Eighteen mice were randomly divided into three groups: control group, asthma group, and SC treatment group. Effect of SC was assessed by hematoxylin-eosin staining and real-time PCR. Exosomes from asthma and SC treatment groups were analyzed by small RNA-seq. Results revealed SC significantly alleviated the pathogenesis of asthma and suppressed the release of inflammatory cytokines. A total of 328 exosomal miRNAs were differentially expressed between the exosomes from asthma and SC-treated mice, including 118 up- and 210 downregulated in SC-treated mice. The altered exosomal miRNAs were primarily involved in the function of transcription, apoptotic process, and cell adhesion; and pathway of calcium, Wnt, and MAPK signaling. Real-time PCR verified exosomal miR-147 was downregulated, while miR-98-5p and miR-10a-5p were upregulated in SC-treated mice compared to asthma mice. Moreover, the target genes of miR-147-3p, miR-98-5p, and miR-10a-5p were mainly enriched in Wnt and MAPK inflammatory signaling. miR-10a-5p promoted the proliferation of mouse lung epithelial cells and downregulated the expression of Nfat5 and Map2k6. These data suggest SC-induced exosomal miRNAs might mediate the inflammatory signaling and might be involved in the SC treatment in asthma. The exosomal miRNAs might be promising candidates for the treatment of asthma.

Altered Frequency of NK Cells and Treg Cells by Astragalus Polysaccharide Combined with Budesonide in Asthma Model Mice

Objective. We investigated the efficacy of astragalus polysaccharide (APS) combined with budesonide and the effect on expressions of peripheral NK cells and Treg cells and the molecular mechanism in mice with bronchial asthma. Methods. In this study, we established a mouse model of asthma. Four groups of BaLB/C mice were developed; control group had no asthma induction, and the other three groups of mice were sensitized by OVA (Ovalbumin), OVA + budesonide, and OVA + APS + budesonide. Flow cytometry was used to determine the proportion of NK cells and Treg cells. Levels of cytokines IL-4 and IL-10 were detected using RT-PCR and ELISA. Results. Asthma mice treated with APS + budesonide showed alleviated airway resistance compared to model mice (P<0.05). The percentage of dendritic cells (DCs) was reduced (P<0.05), while anti-inflammatory NK cells and Treg cells significantly increased after APS + budesonide treatment (P<0.05). Further, APS + budesonide treatment resulted in improvements in IL-4 and IL-10 mRNA and protein levels (P<0.05). Conclusion. APS combined with budesonide medication may regulate expressions of DCs cells and related cytokines, reliving clinical symptom of bronchial asthma.

[Analyses of Foxp3+ Treg cells and Tr1 cells in subcutaneous immunotherapy-treated allergic individuals in humans and mice]

Subcutaneous immunotherapy (SCIT) is a causative treatment for allergic diseases. More recently, it has become clear that regulatory T (Treg) cells are increased by SCIT. Treg cells are generally divided into two main groups: 1) CD25⁺ Foxp3⁺ CD4⁺ T cells (Foxp3⁺ Treg cells) and 2) IL-10-producing Foxp3^- CD4⁺ T cells (Tr1 cells). We demonstrated that the number of Tr1 cells in peripheral blood mononuclear cells in SCIT-treated pollinosis patients were significantly higher than that in non-SCIT-treated patients, but Foxp3⁺ Treg cells were not. Consistent with the results of human peripheral blood, Tr1 cells were increased in the lungs of asthmatic mice by SCIT, but Foxp3⁺ Treg cells were not. Moreover, in vitro-induced Tr1 cells were responded to the antigen to produce a large amount of IL-10 in in vitro and in vivo. Adoptive transfer of the induced Tr1 cells significantly suppressed the development of asthma. In any species of human and mouse, the increase in Tr1 cells rather than Foxp3⁺ Treg cells could be important for the effects of SCIT. The increased Tr1 cells by SCIT functionally suppressed allergic asthma probably via production of IL-10 in response to the specific antigen. Therefore, analyses of the induction mechanisms of Tr1 cells and search for compounds which induce Tr1 cells are thought to lead to development of more efficient SCIT.

[Environmental risk factors for asthma developement]

The prevalence of asthma has increased rapidly since the early 1970s, and only changes in exposure to environmental factors; which go together with changes in lifestyle, are likely to explain such a rapid increase. Exposure to allergens is a risk factor for allergic sensitization, and allergic sensitization is a risk factor for allergic asthma. However, apart from indoor mold exposure as a risk factor for childhood asthma, there is insufficient evidence to conclude that the associations between allergen exposure and asthma development are causal. A new challenge for research is to analyze the huge amount of data derived from the metagenomic characterization of the environmental and human microbiome, to understand the role of interactions between viruses, bacteria and allergens in the development of asthma. It is recognized that prenatal and postnatal exposure to air pollution and maternal smoking increase the risk of developing asthma in children. In adults, the data are scarce and the results remain controversial as regards these exposures and asthma incidence. Further research is needed to appraise the effect of exposure to phenols, phthalates and perfluorinated compounds, which are widespread in the environment and may be associated with asthma, especially in children. Frequent use of chemicals for home cleaning especially in the form of sprays - which is a common practice at the population level - is a risk factor for the development of adult asthma. The domestic use of cleaning products might also be a risk factor for asthma in children exposed at home. The chemicals involved in these relationships are still to be identified. Occupational asthma is a major phenotype of adult asthma. A significant part of these asthma cases might relate to occupational exposure to cleaning products. While there is evidence of associations between diet during pregnancy or during childhood and the risk of developing asthma in children, the data in adults are insufficient. Beyond genetic factors, body composition is influenced by dietary choices and physical activity. Further research is needed to clarify the complex interplay between these nutritional factors and asthma development. The new challenge for research is to decipher the role of all the environmental factors to which the individual is exposed since conception ("exposome") in the development of asthma, using a holistic approach.

Biomarkers in asthma: state of the art

Asthma is a heterogenous disease characterized by multiple phenotypes driven by different mechanisms. The implementation of precision medicine in the management of asthma requires the identification of phenotype-specific markers measurable in biological fluids. To become useful, these biomarkers need to be quantifiable by reliable systems, reproducible in the clinical setting, easy to obtain and cost-effective. Using biomarkers to predict asthma outcomes and therapeutic response to targeted therapies has a great clinical significance, particularly in severe asthma. In the last years, significant research has been realized in the identification of valid biomarkers for asthma. This review focuses on the existent and emerging biomarkers with clinical higher applicability in the management of asthma.