Mechanism of TH2/TH17-predominant and neutrophilic TH2/TH17-low subtypes of asthma

Gene Polymorphisms of NLRP3 Associated With Plasma Levels of 4β-Hydroxycholesterol, an Endogenous Marker of CYP3A Activity, in Patients With Asthma

Inflammation decreases the activity of cytochrome P450 3A (CYP3A). Nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) is responsible for regulating the inflammatory response, and its genetic polymorphisms have been linked to inflammatory diseases such as asthma. However, there have been few studies on the effect of NLRP3 on CYP3A activity. We aimed to investigate the association between polymorphisms in the NLRP3 gene and plasma 4β-hydroxycholesterol (4βOHC), an endogenous marker of CYP3A activity, in patients with asthma. In this observational study including 152 adult asthma patients, we analyzed 10 NLRP3 gene single-nucleotide polymorphisms (SNPs). Plasma 4βOHC levels were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results showed that five SNPs were associated with significantly lower plasma 4βOHC concentrations. Among these SNPs, rs3806265, rs4612666, rs1539019, and rs10733112 contributed to a significant increase in plasma IL-6 concentrations. Moreover, a multivariate regression model showed that the rs3806265 TT, rs4612666 CC, rs1539019 AA, and rs10733112 TT genotypes were significant factors for decreased plasma 4βOHC, even after including patient background factors and CYP3A5*3 (rs776746) gene polymorphisms as covariates. These results were also observed when plasma 4βOHC concentrations were corrected for cholesterol levels. We conclude that NLRP3 gene polymorphisms are involved in increasing plasma IL-6 concentrations and decreasing plasma 4βOHC concentrations in patients with asthma. Therefore, NLRP3 gene polymorphisms may be a predictive marker of CYP3A activity in inflammatory diseases such as asthma.

IL-4 regulates neutrophilic pulmonary inflammation in a mouse model of bronchial asthma

Neutrophilic pulmonary inflammation in asthmatics substantially exacerbates the severity of the disease leading to resistance to conventional corticosteroid therapy. Many studies established the involvement of Th1- and Th17-cells and cytokines produced by them (IFNg, IL-17A, IL-17F etc.) in neutrophilic pulmonary inflammation. Recent studies revealed that IL-4 - a Th2-cytokine regulates neutrophil effector functions and migration. It was showed that IL-4 substantially reduces neutrophilic inflammation of the skin in a mouse model of cutaneous bacterial infection and blood neutrophilia in a mouse model systemic bacterial infection. However, there are no data available regarding the influence of IL-4 on non-infectious pulmonary inflammation. In the current study we investigated the effects of IL-4 in a previously developed mouse model of neutrophilic bronchial asthma. We showed that systemic administration of IL-4 significantly restricts neutrophilic inflammation of the respiratory tract probably through the suppression of Th1-/Th17-immune responses and downregulation of CXCR2. Additionally, pulmonary neutrophilic inflammation could be alleviated by IL-4-dependant polarization of N2 neutrophils and M2 macrophages, expressing anti-inflammatory TGFβ. Considering these, IL-4 might be used for reduction of exaggerated pulmonary neutrophilic inflammation and overcoming corticosteroid insensitivity of asthma patients.

Allosteric inhibition of CXCR1 and CXCR2 abrogates Th2/Th17-associated Allergic Lung Inflammation in Mice

Background

IL4, IL5, IL13, and IL17-producing CD4 T helper 2 (Th2)-cells and IL17-producing CD4 T helper 17 (Th17)-cells contribute to chronic eosinophilic and neutrophilic airway inflammation in asthma and allergic airway inflammation. Chemokines and their receptors are upregulated in Th2/Th17-mediated inflammation. However, the ability of CXCR1 and CXCR2 modulate Th2 and Th17-cell-mediated allergic lung inflammation has not been reported.

Methods

Mice sensitized and challenged with cat dander extract (CDE) mount a vigorous Th2-Th17-mediated allergic lung inflammation. Allosteric inhibitor of CXCR1 and CXCR2, ladarixin was orally administered in this model. The ability of ladarixin to modulate allergen-challenge induced recruitment of CXCR1 and CXCR2-expressing Th2 and Th17-cells and allergic lung inflammation were examined.

Results

Allergen challenge in sensitized mice increased mRNA expression levels of Il4, Il5, Il13, Il6, Il1β, Tgfβ1, Il17, Il23, Gata3, and Rorc , and induced allergic lung inflammation characterized by recruitment of CXCR1- and CXCR2-expressing Th2-cells, Th17-cells, neutrophils, and eosinophils. Allosteric inhibition of CXCR1 and CXCR2 vigorously blocked each of these pro-inflammatory effects of allergen challenge. CXCL chemokines induced a CXCR1 and CXCR2-dependent proliferation of IL4, IL5, IL13, and IL17 expressing T-cells.

Conclusion

Allosteric inhibition of CXCR1 and CXCR2 abrogates blocks recruitment of CXCR1- and CXCR2-expressing Th2-cells, Th17-cells, neutrophils, and eosinophils in this mouse model of allergic lung inflammation. We suggest that the ability of allosteric inhibition of CXCR1 and CXCR2 to abrogate Th2 and Th17-mediated allergic inflammation should be investigated in humans.

Tailored Biologics Selection in Severe Asthma

The management of severe asthma presents a significant challenge in asthma treatment. Over the past few decades, remarkable progress has been made in developing new treatments for severe asthma, primarily in the form of biological agents. These advances have been made possible through a deeper understanding of the underlying pathogenesis of asthma. Most biological agents focus on targeting specific inflammatory pathways known as type 2 inflammation. However, recent developments have introduced a new agent targeting upstream alarmin signaling pathways. This opens up new possibilities, and it is anticipated that additional therapeutic agents targeting various pathways will be developed in the future. Despite this recent progress, the mainstay of asthma treatment has long been inhalers. As a result, the guidelines for the appropriate use of biological agents are not yet firmly established. In this review, we aim to emphasize the current state of biological therapy for severe asthma and provide insights into its future prospects.

Cytotoxic CD4+ tissue-resident memory T cells are associated with asthma severity

BACKGROUND

Patients with severe uncontrolled asthma represent a distinct endotype with persistent airway inflammation and remodeling that is refractory to corticosteroid treatment. CD4+ TH2 cells play a central role in orchestrating asthma pathogenesis, and biologic therapies targeting their cytokine pathways have had promising outcomes. However, not all patients respond well to such treatment, and their effects are not always durable nor reverse airway remodeling. This observation raises the possibility that other CD4+ T cell subsets and their effector molecules may drive airway inflammation and remodeling.

METHODS

We performed single-cell transcriptome analysis of >50,000 airway CD4+ T cells isolated from bronchoalveolar lavage samples from 30 patients with mild and severe asthma.

FINDINGS

We observed striking heterogeneity in the nature of CD4+ T cells present in asthmatics' airways, with tissue-resident memory T (TRM) cells making a dominant contribution. Notably, in severe asthmatics, a subset of CD4+ TRM cells (CD103-expressing) was significantly increased, comprising nearly 65% of all CD4+ T cells in the airways of male patients with severe asthma when compared to mild asthma (13%). This subset was enriched for transcripts linked to T cell receptor activation (HLA-DRB1, HLA-DPA1) and cytotoxicity (GZMB, GZMA) and, following stimulation, expressed high levels of transcripts encoding for pro-inflammatory non-TH2 cytokines (CCL3, CCL4, CCL5, TNF, LIGHT) that could fuel persistent airway inflammation and remodeling.

CONCLUSIONS

Our findings indicate the need to look beyond the traditional T2 model of severe asthma to better understand the heterogeneity of this disease.

FUNDING

This research was funded by the NIH.

Th2 cell clonal expansion at diagnosis in human type 1 diabetes

Soon after diagnosis with type 1 diabetes (T1D), many patients experience a period of partial remission. A longer partial remission is associated with a better response to treatment, but the mechanism is not known. The frequency of CD4+CD25+CD127hi (127-hi) cells, a cell subset with an anti-inflammatory Th2 bias, correlates positively with length of partial remission. The purpose of this study was to further characterize the nature of the Th2 bias in 127-hi cells. Single cell RNA sequencing paired with TCR sequencing of sorted 127-hi memory cells identifies clonally expanded Th2 clusters in 127-hi cells from T1D, but not from healthy donors. The Th2 clusters express GATA3, GATA3-AS1, PTGDR2, IL17RB, IL4R and IL9R. The existence of 127-hi Th2 cell clonal expansion in T1D suggests that disease factors may induce clonal expansion of 127-hi Th2 cells that prolong partial remission and delay disease progression.

Exploring redox imbalance and inflammation for asthma therapy

BACKGROUND

Asthma is a prolonged inflammatory disorder of the airways, that affects an estimated 300 million people worldwide. Asthma is triggered by numerous endogenous and exogenous stimuli with symptoms like wheezing, cough, short of breath, chest tightening, airway obstruction, and hyperreactivity observed in patients.

OBJECTIVE

The review seeks to identify targets of redox imbalance and inflammation that could be explored to create effective treatments for asthma.

METHODS

The methodology involved a search and review of literature relating to asthma pathogenesis, redox homeostasis, and inflammation.

RESULTS

 Eosinophils and neutrophils are involved in asthma pathogenesis. These inflammatory cells generate high levels of endogenous oxidants such as hydrogen peroxide and superoxide, which could result in redox imbalance in the airways of asthmatics. Redox imbalance occurs when the antioxidant systems becomes overwhelmed resulting in oxidative stress. Oxidative stress and inflammation have been linked with asthma inflammation and severity. Reactive oxygen species (ROS)/reactive nitrogen species (RNS) cause lung inflammation by activating nuclear factor kappa-B (NF-κB), mitogen-activated protein kinase (MAPK), activator protein-1, as well as additional transcription factors. These factors stimulate cytokine production which ultimately activates inflammatory cells in the bronchi, causing lung cellular injury and destruction. ROS/RNS is also produced by these inflammatory cells to eradicate invading bacteria. Antioxidant treatments for asthma have not yet been fully explored.

CONCLUSION

Redox and inflammatory processes are viable targets that could be explored to create better therapy for asthma.

Stratification of asthma by lipidomic profiling of induced sputum supernatant

BACKGROUND

Asthma is a chronic respiratory disease with significant heterogeneity in its clinical presentation and pathobiology. There is need for improved understanding of respiratory lipid metabolism in asthma patients and its relation to observable clinical features.

OBJECTIVE

We performed a comprehensive, prospective, cross-sectional analysis of the lipid composition of induced sputum supernatant obtained from asthma patients with a range of disease severities, as well as from healthy controls.

METHODS

Induced sputum supernatant was collected from 211 adults with asthma and 41 healthy individuals enrolled onto the U-BIOPRED (Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes) study. Sputum lipidomes were characterized by semiquantitative shotgun mass spectrometry and clustered using topologic data analysis to identify lipid phenotypes.

RESULTS

Shotgun lipidomics of induced sputum supernatant revealed a spectrum of 9 molecular phenotypes, highlighting not just significant differences between the sputum lipidomes of asthma patients and healthy controls, but also within the asthma patient population. Matching clinical, pathobiologic, proteomic, and transcriptomic data helped inform the underlying disease processes. Sputum lipid phenotypes with higher levels of nonendogenous, cell-derived lipids were associated with significantly worse asthma severity, worse lung function, and elevated granulocyte counts.

CONCLUSION

We propose a novel mechanism of increased lipid loading in the epithelial lining fluid of asthma patients resulting from the secretion of extracellular vesicles by granulocytic inflammatory cells, which could reduce the ability of pulmonary surfactant to lower surface tension in asthmatic small airways, as well as compromise its role as an immune regulator.

Macrophages Orchestrate Airway Inflammation, Remodeling, and Resolution in Asthma

Asthma is a heterogenous chronic inflammatory lung disease with endotypes that manifest different immune system profiles, severity, and responses to current therapies. Regardless of endotype, asthma features increased immune cell infiltration, inflammatory cytokine release, and airway remodeling. Lung macrophages are also heterogenous in that there are separate subsets and, depending on the environment, different effector functions. Lung macrophages are important in recruitment of immune cells such as eosinophils, neutrophils, and monocytes that enhance allergic inflammation and initiate T helper cell responses. Persistent lung remodeling including mucus hypersecretion, increased airway smooth muscle mass, and airway fibrosis contributes to progressive lung function decline that is insensitive to current asthma treatments. Macrophages secrete inflammatory mediators that induce airway inflammation and remodeling. Additionally, lung macrophages are instrumental in protecting against pathogens and play a critical role in resolution of inflammation and return to homeostasis. This review summarizes current literature detailing the roles and existing knowledge gaps for macrophages as key inflammatory orchestrators in asthma pathogenesis. We also raise the idea that modulating inflammatory responses in lung macrophages is important for alleviating asthma.

T helper 2 cells in asthma

Allergic asthma is among the most common immune-mediated diseases across the world, and type 2 immune responses are thought to be central to pathogenesis. The importance of T helper 2 (Th2) cells as central regulators of type 2 responses in asthma has, however, become less clear with the discovery of other potent innate sources of type 2 cytokines and innate mediators of inflammation such as the alarmins. This review provides an update of our current understanding of Th2 cells in human asthma, highlighting their many guises and functions in asthma, both pathogenic and regulatory, and how these are influenced by the tissue location and disease stage and severity. It also explores how biologics targeting type 2 immune pathways are impacting asthma, and how these have the potential to reveal hitherto underappreciated roles for Th2 cell in lung inflammation.

Long-term exposure to house dust mites accelerates lung cancer development in mice

BACKGROUND

Individuals with certain chronic inflammatory lung diseases have a higher risk of developing lung cancer (LC). However, the underlying mechanisms remain largely unknown. Here, we hypothesized that chronic exposure to house dust mites (HDM), a common indoor aeroallergen associated with the development of asthma, accelerates LC development through the induction of chronic lung inflammation (CLI).  METHODS: The effects of HDM and heat-inactivated HDM (HI-HDM) extracts were evaluated in two preclinical mouse models of LC (a chemically-induced model using the carcinogen urethane and a genetically-driven model with oncogenic KrasG12D activation in lung epithelial cells) and on murine macrophages in vitro. Pharmacological blockade or genetic deletion of the Nod-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome, caspase-1, interleukin-1β (IL-1β), and C-C motif chemokine ligand 2 (CCL2) or treatment with an inhaled corticosteroid (ICS) was used to uncover the pro-tumorigenic effect of HDM.  RESULTS: Chronic intranasal (i.n) instillation of HDM accelerated LC development in the two mouse models. Mechanistically, HDM caused a particular subtype of CLI, in which the NLRP3/IL-1β signaling pathway is chronically activated in macrophages, and made the lung microenvironment conducive to tumor development. The tumor-promoting effect of HDM was significantly decreased by heat treatment of the HDM extract and was inhibited by NLRP3, IL-1β, and CCL2 neutralization, or ICS treatment.

CONCLUSIONS

Collectively, these data indicate that long-term exposure to HDM can accelerate lung tumorigenesis in susceptible hosts (e.g., mice and potentially humans exposed to lung carcinogens or genetically predisposed to develop LC).

Bacterial DNA amplifies neutrophilic inflammation in IL-17-exposed airways

Background

Neutrophilic asthma (NA) is associated with increased airway interleukin (IL)-17 and abnormal bacterial community such as dominance of nontypeable Haemophilus influenzae (NTHi), particularly during asthma exacerbations. Bacteria release various products including DNA, but whether they cooperate with IL-17 in exaggerating neutrophilic inflammation is unclear. We sought to investigate the role of bacteria-derived DNA in airway neutrophilic inflammation related to IL-17-high asthma and underlying mechanisms (e.g. Toll-like receptor 9 (TLR9)/IL-36γ signalling axis).

Methods

Bacterial DNA, IL-8 and IL-36γ were measured in bronchoalveolar lavage fluid (BALF) of people with asthma and healthy subjects. The role of co-exposure to IL-17 and bacterial DNA or live bacteria in neutrophilic inflammation, and the contribution of the TLR9/IL-36γ signalling axis, were determined in cultured primary human airway epithelial cells and alveolar macrophages, and mouse models.

Results

Bacterial DNA levels were increased in asthma BALF, which positively correlated with IL-8 and neutrophil levels. Moreover, IL-36γ increased in BALF of NA patients. Bacterial DNA or NTHi infection under an IL-17-high setting amplified IL-8 production and mouse lung neutrophilic inflammation. DNase I treatment in IL-17-exposed and NTHi-infected mouse lungs reduced neutrophilic inflammation. Mechanistically, bacterial DNA-mediated amplification of neutrophilic inflammation is in part dependent on the TLR9/IL-36γ signalling axis.

Conclusions

Bacterial DNA amplifies airway neutrophilic inflammation in an IL-17-high setting partly through the TLR9 and IL-36γ signalling axis. Our novel findings may offer several potential therapeutic targets including TLR9 antagonists, IL-36γ neutralising antibodies and DNase I to reduce asthma severity associated with exaggerated airway neutrophilic inflammation.

The understanding of asthma pathogenesis in the era of precision medicine

Asthma is a syndrome with extremely diverse clinical phenotypes in which the onset, severity, and response to treatment are defined by the complex interplay of many genetic and environmental factors. Environmental factors epigenetically affect gene expression, and the disease is driven by a multidimensional dynamic network involving RNA and protein molecules derived from gene expression, as well as various metabolic products. In other words, specific pathophysiological mechanisms or endotypes are dynamic networks that arise in response to individual genotypes and the various environmental factors to which individuals have been exposed since before birth, such as diet, infection, air pollution, smoking, antibiotic use, and the bacterial flora of the intestinal tract, skin, and lungs. A key feature of asthma genome scans is their potential to reveal the molecular pathways that lead to pathogenesis. Endotypes that drive the disease have a significant impact on the phenotypes of asthma patients, including their drug responsiveness. Understanding endotypes will lead to not only the implementation of therapies that are tailored to the specific molecular network(s) underlying the patient's condition, but also to the development of therapeutic strategies that target individual endotypes, as well as to precision health, which will enable the prediction of disease onset with high accuracy from an early stage and the implementation of preventive strategies based on endotypes. Understanding of endotypes will pave the way for the practice of precision medicine in asthma care, moving away from 'one-size-fits-all' medicine and population-based prevention approaches that do not take individuals' susceptibility into account.

IL-1β and Allergy: Focusing on Its Role in Allergic Rhinitis

Allergic rhinitis (AR) is a chronic upper airway immune-inflammation response mediated by immunoglobulin E (IgE) to allergens and can seriously affect the quality of life and work efficiency. Previous studies have shown that interleukin-1β (IL-1β) acts as a key cytokine to participate in and promote the occurrence and development of allergic diseases. It has been proposed that IL-1β may be a potential biomarker of AR. However, its definitive role and potential mechanism in AR have not been fully elucidated, and the clinical sample collection and detection methods were inconsistent among different studies, which have limited the use of IL-1β as a clinical diagnosis and treatment marker for AR. This article systematically summarizes the research advances in the roles of IL-1β in allergic diseases, focusing on the changes of IL-1β in AR and the possible interventions. In addition, based on the findings by our team, we provided new insights into the use of IL-1β in AR diagnosis and treatment, in an attempt to further promote the clinical application of IL-1β in AR and other allergic diseases.

Efficacy and Safety of Diethylcarbamazine in Treatment of Allergic Rhinitis: A Double Blind Randomised Controlled Trial

There are many evidences showing diethylcarbamazine as a potential drug for the treatment of allergic rhinitis. This study evaluated the effectiveness of diethylcarbamazine in the treatment of allergic rhinitis and compared it with montelukast and levocetirizine. This parallel double-blind randomized clinical trial was done in allergic rhinitis patients. Seven hundred and twelve participants who met the inclusion criteria and provided informed written consent were randomized and divided into 2 equal groups. Diethylcarbamazine 300 mg/day orally in divided doses was given to group A, and montelukast 10 mg and levocetirizine 5 mg/day orally at night for 21 days was given to group B. Primary outcomes were the change in symptoms, absolute eosinophil count, serum total IgE, phadiatop and response in skin prick from baseline to 21 days and 3 months after treatment. Secondary outcome was to compare it with montelukast and levocetirizine. The mean (SD) age of the patients was 33 (10.6) years, with 374 (52.5%) males and 338 (47.5%) females. There was statistically significant improvement in all the parameters in both groups. Improvement was better with diethylcarbamazine compared to montelukast and levocetirizine and the effects were sustained for 3 months in diethylcarbamazine group. The findings suggest that diethylcarbamazine is effective in the treatment of allergic rhinitis. It gives better control and is cost-effective than montelukast and levocetirizine. Trial Registration: https://www.ctri.nic.in Identifier: CTRI/2020/03/024145 registered on 20-03-2020.

Sterols in asthma

While sterols regulate immune processes key to the pathogenesis of asthma, inhibition of sterols with statin drugs has shown conflicting results in human asthma. Here, a novel understanding of the impact of sterols on type 17 immune responses and asthma lead us to hypothesize that sterols and statins may be relevant to severe asthma endotypes with neutrophil infiltration.

Coadministration of Stigmasterol and Dexamethasone (STIG+DEX) Modulates Steroid-Resistant Asthma

Airway inflammation in asthma is managed with anti-inflammatory steroids such as dexamethasone (DEX). However, about 20% of asthmatics do not respond to this therapy and are classified as steroid-resistant. Currently, no effective therapy is available for steroid-resistant asthma. This work therefore evaluated the effect of a plant sterol, stigmasterol (STIG), and stigmasterol-dexamethasone combination (STIG+DEX) in LPS-ovalbumin-induced steroid-resistant asthma in Guinea pigs. To do this, the effect of drugs on inflammatory features such as airway hyperreactivity and histopathology of lung tissue was evaluated. Additionally, the possible pathway of drug action was assessed by measuring events such neutrophil levels, oxidative and nitrative stress, and histone deacetylase 2 (HDAC2) and interleukin 17 (IL-17) levels. STIG alone did not affect inflammatory features, although it caused some changes in the molecular events associated with steroid-resistant asthma. However, STIG+DEX caused significant modulation of inflammatory features by protecting against destruction of lung tissue. The modulation of inflammatory features was associated with significant inhibition of neutrophilia and oxidative and nitrative stress, decrease in HDAC2, and increase in IL-17 levels that are usually associated with steroid-resistant asthma. Our findings show that although STIG and DEX individually do not protect against steroid-resistant asthma, their coadministration results in significant modulation of inflammatory features and the associated molecular events that lead to steroid-resistant asthma.

Distinct spatial and temporal roles for Th1, Th2, and Th17 cells in asthma

Immune response in the asthmatic respiratory tract is mainly driven by CD4⁺ T helper (Th) cells, represented by Th1, Th2, and Th17 cells, especially Th2 cells. Asthma is a heterogeneous and progressive disease, reflected by distinct phenotypes orchestrated by τh2 or non-Th2 (Th1 and Th17) immune responses at different stages of the disease course. Heterogeneous cytokine expression within the same Th effector state in response to changing conditions in vivo and interlineage relationship among CD4⁺ T cells shape the complex immune networks of the inflammatory airway, making it difficult to find one panacea for all asthmatics. Here, we review the role of three T helper subsets in the pathogenesis of asthma from different stages, highlighting timing is everything in the immune system. We also discuss the dynamic topography of Th subsets and pathogenetic memory Th cells in asthma.

Modulation of IL-4/IL-13 cytokine signaling in the context of allergic disease

Aberrant activation of CD4 T_H2 cells and excessive production of T_H2 cytokines such as IL-4 and IL-13 have been implicated in the pathogenesis of allergic diseases. Generally, IL-4 and IL-13 utilize Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathways for induction of inflammatory gene expression and the effector functions associated with disease pathology in many allergic diseases. However, it is increasingly clear that JAK/STAT pathways activated by IL-4/IL-13 can themselves be modulated in the presence of other intracellular signaling programs, thereby changing the overall tone and/or magnitude of IL-4/IL-13 signaling. Apart from direct activation of the canonic JAK/STAT pathways, IL-4 and IL-13 also induce proinflammatory gene expression and effector functions through activation of additional signaling cascades. These alternative signaling cascades contribute to several specific aspects of IL-4/IL-13-associated cellular and molecular responses. A more complete understanding of IL-4/IL-13 signaling pathways, including the precise conditions under which noncanonic signaling pathways are activated, and the impact of these pathways on cellular- and host-level responses, will better allow us to design agents that target specific pathologic outcomes or tailor therapies for the treatment of uncommon disease endotypes.

The Mechanisms of Effector Th Cell Responses Contribute to Treg Cell Function: New Insights into Pathogenesis and Therapy of Asthma

CD4 ⁺ helper T (Th) cell subsets are critically involved in the pathogenesis of asthma. Naive Th cells differentiate into different subsets under the stimulation of different sets of cytokines, and the differentiation process is dominantly driven by lineage specific transcription factors, such as T-bet (Th1), GATA3 (Th2), RORγt (Th17) and Foxp3 (Treg). The differentiation mechanisms driven by these transcription factors are mutually exclusive, resulting in functional inhibition of these Th subsets to each other, particularly prominent between effector Th cells and Treg cells, such as Th2 versus Treg cells and Th17 versus Treg cells. Being of significance in maintaining immune homeostasis, the balance between effector Th cell response and Treg cell immunosuppression provides an immunological theoretical basis for us to understand the immunopathological mechanism and develop the therapy strategies of asthma. However, recent studies have found that certain factors involved in effector Th cells response, such as cytokines and master transcription factors (IL-12 and T-bet of Th1, IL-4 and GATA3 of Th2, IL-6 and RORγt of Th17), not only contribute to immune response of effector Th cells, but also promote the development and function of Treg cells, therefore bridging the interplay between effector Th cell immune responses and Treg cell immunosuppression. Although we have an abundant knowledge concerning the role of these cytokines and transcription factors in effector Th cell responses, our understanding on their role in Treg cell development and function is scattered thus need to be summarized. This review summarized the role of these cytokines and transcription factors involved in effector Th cell responses in the development and function of Treg cells, in the hope of providing new insights of understanding the immunopathological mechanism and seeking potential therapy strategies of asthma.

Molecular Clustering Analysis of Blood Biomarkers in World Trade Center Exposed Community Members with Persistent Lower Respiratory Symptoms

The destruction of the World Trade Center (WTC) on September 11, 2001 (9/11) released large amounts of toxic dusts and fumes into the air that exposed many community members who lived and/or worked in the local area. Many community members, defined as WTC survivors by the federal government, developed lower respiratory symptoms (LRS). We previously reported the persistence of these symptoms in patients with normal spirometry despite treatment with inhaled corticosteroids and/or long-acting bronchodilators. This report expands upon our study of this group with the goal to identify molecular markers associated with exposure and heterogeneity in WTC survivors with LRS using a selected plasma biomarker approach. Samples from WTC survivors with LRS (n = 73, WTCS) and samples from healthy control participants of the NYU Bellevue Asthma Registry (NYUBAR, n = 55) were compared. WTCS provided information regarding WTC dust exposure intensity. Hierarchical clustering of the linear biomarker data identified two clusters within WTCS and two clusters within NYUBAR controls. Comparison of the WTCS clusters showed that one cluster had significantly increased levels of circulating matrix metalloproteinases (MMP1, 2, 3, 8, 12, 13), soluble inflammatory receptors (receptor for advanced glycation end-products-RAGE, Interleukin-1 receptor antagonist (IL-1RA), suppression of tumorigenicity (ST)2, triggering receptor expressed on myeloid cells (TREM)1, IL-6Ra, tumor necrosis factor (TNF)RI, TNFRII), and chemokines (IL-8, CC chemokine ligand- CCL17). Furthermore, this WTCS cluster was associated with WTC exposure variables, ash at work, and the participant category workers; but not with the exposure variable WTC dust cloud at 9/11. A comparison of WTC exposure categorial variables identified that chemokines (CCL17, CCL11), circulating receptors (RAGE, TREM1), MMPs (MMP3, MMP12), and vascular markers (Angiogenin, vascular cell adhesion molecule-VCAM1) significantly increased in the more exposed groups. Circulating biomarkers of remodeling and inflammation identified clusters within WTCS and were associated with WTC exposure.

The Role of Exposomes in the Pathophysiology of Autoimmune Diseases II: Pathogens

In our continuing examination of the role of exposomes in autoimmune disease, we use this review to focus on pathogens. Infections are major contributors to the pathophysiology of autoimmune diseases through various mechanisms, foremost being molecular mimicry, when the structural similarity between the pathogen and a human tissue antigen leads to autoimmune reactivity and even autoimmune disease. The three best examples of this are oral pathogens, SARS-CoV-2, and the herpesviruses. Oral pathogens reach the gut, disturb the microbiota, increase gut permeability, cause local inflammation, and generate autoantigens, leading to systemic inflammation, multiple autoimmune reactivities, and systemic autoimmunity. The COVID-19 pandemic put the spotlight on SARS-CoV-2, which has been called “the autoimmune virus.” We explore in detail the evidence supporting this. We also describe how viruses, in particular herpesviruses, have a role in the induction of many different autoimmune diseases, detailing the various mechanisms involved. Lastly, we discuss the microbiome and the beneficial microbiota that populate it. We look at the role of the gut microbiome in autoimmune disorders, because of its role in regulating the immune system. Dysbiosis of the microbiota in the gut microbiome can lead to multiple autoimmune disorders. We conclude that understanding the precise roles and relationships shared by all these factors that comprise the exposome and identifying early events and root causes of these disorders can help us to develop more targeted therapeutic protocols for the management of this worldwide epidemic of autoimmunity.

Neutrophils and Asthma

Although eosinophilic inflammation is characteristic of asthma pathogenesis, neutrophilic inflammation is also marked, and eosinophils and neutrophils can coexist in some cases. Based on the proportion of sputum cell differentiation, asthma is classified into eosinophilic asthma, neutrophilic asthma, neutrophilic and eosinophilic asthma, and paucigranulocytic asthma. Classification by bronchoalveolar lavage is also performed. Eosinophilic asthma accounts for most severe asthma cases, but neutrophilic asthma or a mixture of the two types can also present a severe phenotype. Biomarkers for the diagnosis of neutrophilic asthma include sputum neutrophils, blood neutrophils, chitinase-3-like protein, and hydrogen sulfide in sputum and serum. Thymic stromal lymphoprotein (TSLP)/T-helper 17 pathways, bacterial colonization/microbiome, neutrophil extracellular traps, and activation of nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 pathways are involved in the pathophysiology of neutrophilic asthma and coexistence of obesity, gastroesophageal reflux disease, and habitual cigarette smoking have been associated with its pathogenesis. Thus, targeting neutrophilic asthma is important. Smoking cessation, neutrophil-targeting treatments, and biologics have been tested as treatments for severe asthma, but most clinical studies have not focused on neutrophilic asthma. Phosphodiesterase inhibitors, anti-TSLP antibodies, azithromycin, and anti-cholinergic agents are promising drugs for neutrophilic asthma. However, clinical research targeting neutrophilic inflammation is required to elucidate the optimal treatment.

Murine model of steroid-resistant neutrophilic bronchial asthma as an attempt to simulate human pathology

Bronchial asthma (BA) is a heterogeneous chronic inflammatory disease of the airways. The majority of patients with mild to moderate BA develop Th2-biased eosinophilic pulmonary inflammation and respond well to corticosteroid treatment. However up to 10% of BA patients develop severe pathology, which is associated with neutrophilic inflammation and resistant to conventional corticosteroid therapy. Contrary to eosinophil-predominant airway inflammation neutrophilic BA is developed through Th1- and Th17-immune responses. However, the etiology of corticoid insensitive neutrophilic BA is still remains unclear. Therefore, in the current study we developed a mouse model of BA with predominant neutrophilic rather than eosinophilic pulmonary inflammation. BALB/c mice were immunized with the mixture of the ovalbumin allergen and Freund's adjuvant, followed by aerosol challenge with the same allergen mixed with E. coli lipopolysaccharide. As a result, mice developed the main BA manifestations: production of allergen specific IgE, development of airway hyperreactivity, airway remodeling and pulmonary neutrophilic inflammation. Moreover, this pathology developed through Th1- and Th17-dependent mechanisms and mice with induced neutrophilic BA phenotype responded poorly to dexamethasone treatment, that coincide to clinical observations. The established mouse model could be useful both for studying the pathogenesis and for testing novel approaches to control neutrophilic BA.

Changes in the phenotype and function of mucosal-associated invariant T cells in neutrophilic asthma

Asthma is a chronic heterogeneous inflammatory disease. Most neutrophilic asthma (NA) cases are severe asthma involving many inflammatory cells and mediators, although the specific pathogenesis is not clear. Mucosal-associated invariant T (MAIT) cells as innate-like T lymphocytes play an important role in the immune response in asthma by producing cytokines. In this study, we evaluated the phenotype and function of circulating MAIT cells in patients with NA and inflammatory-related cytokines in plasma and induced sputum supernatants using flow cytometry. The results showed that the frequency of circulating MAIT cells in asthma patients, particularly NA patients, decreased significantly, and CD8⁺ MAIT and MAIT Temra cells also decreased significantly. Increased expression of CD69 and PD-1 on MAIT cells indicated excessive activation and depletion, leading to the decrease in MAIT cells. Levels of IL-17A and TNF-α secreted by MAIT cells of NA patients increased, whereas IFN-γ levels decreased, indicating that MAIT cells in NA are biased to the Th17 subtype. MAIT cells were also negatively correlated with clinical parameters, indicating that these cells are related to asthma severity. Pro-inflammatory cytokines in plasma and sputum supernatant increased to varying degrees, whereas IL-10 declined, corresponding with asthma severity. We speculate that increased IL-17A and TNF-α synergistically stimulated respiratory epithelial cells to secrete IL-6 and IL-8, thereby recruiting neutrophils to inflammatory sites and aggravating asthma symptoms. Therefore, MAIT cells could serve as a potential therapeutic target in NA immunity, thus providing a new strategy for the treatment of asthma.

TH17 cells and corticosteroid insensitivity in severe asthma

Asthma is classically described as having either a type 2 (T2) eosinophilic phenotype or a non-T2 neutrophilic phenotype. T2 asthma usually responds to classical bronchodilation therapy and corticosteroid treatment. Non-T2 neutrophilic asthma is often more severe. Patients with non-T2 asthma or late-onset T2 asthma show poor response to the currently available anti-inflammatory therapies. These therapeutic failures result in increased morbidity and cost associated with asthma and pose a major health care problem. Recent evidence suggests that some non-T2 asthma is associated with elevated T_H17 cell immune responses. T_H17 cells producing Il-17A and IL-17F are involved in the neutrophilic inflammation and airway remodeling processes in severe asthma and have been suggested to contribute to the development of subsets of corticosteroid-insensitive asthma. This review explores the pathologic role of T_H17 cells in corticosteroid insensitivity of severe asthma and potential targets to treat this endotype of asthma.

Refractory neutrophilic asthma and ciliary genes

BACKGROUND

Refractory asthma (RA) remains poorly controlled, resulting in high health care utilization despite guideline-based therapies. Patients with RA manifest higher neutrophilia as a result of increased airway inflammation and subclinical infection, the underlying mechanisms of which remain unclear.

OBJECTIVE

We sought to characterize and clinically correlate gene expression differences between refractory and nonrefractory (NR) asthma to uncover molecular mechanisms driving group distinctions.

METHODS

Microarray gene expression of paired airway epithelial brush and endobronchial biopsy samples was compared between 60 RA and 30 NR subjects. Subjects were hierarchically clustered to identify subgroups of RA, and biochemical and clinical traits (airway inflammatory molecules, respiratory pathogens, chest imaging) were compared between groups. Weighted gene correlation network analysis was used to identify coexpressed gene modules. Module expression scores were compared between groups using linear regression, controlling for age, sex, and body mass index.

RESULTS

Differential gene expression analysis showed upregulation of proneutrophilic and downregulation of ciliary function genes/pathways in RA compared to NR. A subgroup of RA with downregulated ciliary gene expression had increased levels of subclinical infections, airway neutrophilia, and eosinophilia as well as higher chest imaging mucus burden compared to other RA, the dominant differences between RA and NR. Weighted gene correlation network analysis identified gene modules related to ciliary function, which were downregulated in RA and were associated with lower pulmonary function and higher airway wall thickness/inflammation, markers of poorer asthma control.

CONCLUSIONS

Identification of a novel ciliary-deficient subgroup of RA suggests that diminished mucociliary clearance may underlie repeated asthma exacerbations despite adequate treatment, necessitating further exploration of function, mechanism, and therapeutics.

Mitochondria in Focus: From Function to Therapeutic Strategies in Chronic Lung Diseases

Mitochondria are essential organelles for cell metabolism, growth, and function. Mitochondria in lung cells have important roles in regulating surfactant production, mucociliary function, mucus secretion, senescence, immunologic defense, and regeneration. Disruption in mitochondrial physiology can be the central point in several pathophysiologic pathways of chronic lung diseases such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, and asthma. In this review, we summarize how mitochondria morphology, dynamics, redox signaling, mitophagy, and interaction with the endoplasmic reticulum are involved in chronic lung diseases and highlight strategies focused on mitochondrial therapy (mito-therapy) that could be tested as a potential therapeutic target for lung diseases.

Effects of Recombinant IL-35-BCG on Treg/Th17 Cell Imbalance and Inflammatory Response in Asthmatic Newborn Mice Induced by RSV

Treg/Th17 cell imbalance and inflammatory response may occur in neonatal asthma. IL-35 and BCG have inhibitory effects on inflammatory responses in diseases. However, studies on neonatal asthma after combination of the two have not been reported so far. A respiratory syncytial virus (RSV)-induced neonatal asthma model was first developed in newborn mice. Pathological sections of lung tissue of asthmatic mice were observed by HE staining. Masson staining was used to observe the lung tissue and to compare the deposition of collagen fibers under bronchial epithelium in model mice. The expression of cytokines in serum was detected by ELISA. Giemsa staining analyzed each cell in bronchoalveolar lavage fluid (BALF). Flow cytometry was used to detect the differentiation and development of Treg and Th17 subgroups in BALF. The expression levels of inflammation-related factors were detected by RT-qPCR. Western blot was used to detect the expression of JNK pathway-related proteins. Recombinant IL-35-BCG improved the pathological response of asthmatic mice; inhibited the expression of IgE in serum, neutrophils, macrophages, and eosinophils in BALF; and increased the expression of lymphocytes. In addition, recombinant IL-35-BCG significantly inhibited Th17 differentiation, promoted Treg cell differentiation, and inhibited the expression of inflammatory factors in lung tissue homogenates, thereby reducing allergic airway inflammation. This process might be achieved by inhibiting the JNK signaling pathway. Recombinant IL-35-BCG can regulate Treg/Th17 cell imbalance and inflammatory response in asthmatic newborn mice induced by RSV through JNK signaling pathway, suggesting a new path to neonatal asthma treatment.

The Emerging Roles of T Helper Cell Subsets and Cytokines in Severe Neutrophilic Asthma

Neutrophilic asthma (NA) is a severe type of steroid resistant asthma, and so far the immune mechanisms underlying NA are not clear. In this article, we performed a comprehensive assessment of Th-cell subsets and cytokines in severe NA patients. A total of 13 healthy individuals and 31 severe asthma patients were enrolled in this study. Refractory asthma patients were defined as those with eosinophilic asthma (EA, accounted for 32% of asthmatic patients) or NA (68%) according to sputum neutrophil/eosinophil counts or blood eosinophils. Th-cell subsets in peripheral blood mononuclear cells (PBMCs) were analyzed by flow cytometry, and cytokines were detected by cytometric bead array (CBA). The results showed significant differences were observed in Th-cell phenotypes, where the number of Th1 cells were reduced and the numbers of Th2 cells were increased in NA and EA groups, respectively, when compared with healthy controls. Th17 cells were not strongly associated with severe neutrophilic asthma. The frequencies of mucosal-associated invariant T (MAIT) cells were strikingly reduced in severe asthma patients, especially in the NA group. This NA group also showed increased levels of IL-17A, IL-17F, TNF-α, and IL-6 in serum and increased levels of IL-17A, IL-17F, IFN-γ, TNF-α, IL-1β, IL-5, IL-6, and IL-8 in sputum. In addition, sputum IL-6 was positively correlated with TNF-α, IFN-γ, IL-17A, and IL-8. Our results uncovered a controversial role for Th17 cells, which were reduced in severe asthma patients. Severe neutrophilic asthma was associated with a striking deficiency of MAIT cells and high pro-inflammatory cytokine levels.

Treatment approaches for the patient with T2 low asthma

OBJECTIVE

To identify treatment approaches that can be used in the management of patients with asthma who lack significant type 2 inflammation, also called T2 low asthma.

DATA SOURCES

Recent expert guideline updates on the management of asthma, recent journal articles and review articles, and foundational journal articles are referenced.

STUDY SELECTIONS

This review cites clinical cohort studies of highly characterized patients with asthma, clinical interventional trials of high impact, mechanistic studies relevant to T2 low asthma, and emerging work in this area.

RESULTS

T2 low asthma accounts for approximately one-third to one-half of individuals with asthma. Characteristics of participants with T2 low asthma include higher body mass index, cigarette smoking/smoke exposure, relative lack of responsiveness to steroids, less bronchodilator reversibility, and often the presence of neutrophilic inflammation. Multiple available interventions target these characteristics, including standard inhalers, azithromycin, and lifestyle interventions of weight loss and smoking cessation.

CONCLUSION

Treatment of T2 low asthma should involve currently available approaches and will benefit from improved definition and understanding of disease pathobiology.

Different Phenotypes in Asthma: Clinical Findings and Experimental Animal Models

Asthma is a respiratory allergic disease presenting a high prevalence worldwide, and it is responsible for several complications throughout life, including death. Fortunately, asthma is no longer recognized as a unique manifestation but as a very heterogenic manifestation. Its phenotypes and endotypes are known, respectively, as pathologic and molecular features that might not be directly associated with each other. The increasing number of studies covering this issue has brought significant insights and knowledge that are constantly expanding. In this review, we intended to summarize this new information obtained from clinical studies, which not only allowed for the creation of patient clusters by means of personalized medicine and a deeper molecular evaluation, but also created a connection with data obtained from experimental models, especially murine models. We gathered information regarding sensitization and trigger and emphasizing the most relevant phenotypes and endotypes, such as Th2-^high asthma and Th2-^low asthma, which included smoking and obesity-related asthma and mixed and paucigranulocytic asthma, not only in physiopathology and the clinic but also in how these phenotypes can be determined with relative similarity using murine models. We also further investigated how clinical studies have been treating patients using newly developed drugs focusing on specific biomarkers that are more relevant according to the patient's clinical manifestation of the disease.

Increased Proportion of Dual-Positive Th2-Th17 Cells Promotes a More Severe Subtype of Asthma

Asthma is a heterogeneous disease, and abnormal activation of T cells is the driving link of asthma's pathophysiological changes. Dual-positive Th2–Th17 cells, as newly discovered T-helper cells, have the functions of Th2 and Th17 cells and can coproduce Th2 and Th17 cytokines. Previous studies have shown that dual-positive Th2–Th17 cells increase the chances of asthma and correlate with asthma severity. However, the exact role of dual-positive Th2–Th17 cells in asthma is not known. Since there is no mature differentiation method for dual-positive Th2–Th17 cells, the present study aimed to clarify the strict differentiation conditions and reveal how dual-positive Th2–Th17 cells regulate asthma phenotypes. In this study, we confirmed that IL-1β, IL-6, anti-IFN-γ, and IL-21 promoted biphenotypic cell differentiation. Moreover, more proportion of dual-positive Th2–Th17 cells can be obtained by conditioned differentiation of mouse CD4⁺ T cells after classical allergic asthma modeling. Before asthma modeling, adoptive dual-positive Th2–Th17 cells promoted T cells to differentiate into the same biphenotype cells and exacerbated the severity of asthma. Together, our results clarify the differentiation conditions of dual-positive Th2–Th17 cells and further confirm that it stimulates asthma T cells to differentiate into the same biphenotype cells, leading to exacerbation of asthma.

Intimate Partner Violence and Adult Asthma Morbidity: A Population-Based Study

BACKGROUND

The etiologies for difficult-to-control asthma are complex and incompletely understood. Intimate partner violence (IPV) is a pervasive problem and may play a role in difficult-to-control asthma. IPV is associated with increased prevalence of asthma. There are no prior studies evaluating IPV's association with adult asthma exacerbations.

OBJECTIVE

This study hypothesized that IPV exposure would be associated with increased asthma exacerbations, higher symptom burden, and poorer asthma control among adults.

METHODS

Analyses are based on 2634 adults who participated in the 2005 Behavioral Risk Factor Surveillance System survey, reported active asthma, and completed the asthma and IPV questions. We used multivariate logistic regression to examine the association of IPV with asthma morbidity outcomes while controlling for the following potential confounders: sex, race, education, health care coverage, smoking status, age, and body mass index.

RESULTS

The prevalence of IPV was 32.4%. IPV was associated with increased odds of an asthma exacerbation (adjusted odds ratio [AOR] = 1.75, 95% confidence interval [CI] = 1.26-2.43), higher symptom burden (AOR = 2.33, 95% CI = 1.53-3.55), and lack of asthma control (AOR = 2.23, 95% CI = 1.22-4.09) when using composite measures for these outcomes. When using single-item measures for outcomes, IPV was also associated with increased asthma-related emergency department or urgent care visits (AOR = 2.35, 95% CI = 1.56-3.54), other urgent provider visits (AOR = 1.84, 95% CI = 1.28-2.64), perceived asthma attacks (AOR = 1.53, 95% CI = 1.12-2.09), limitations (AOR = 2.07, 95% CI = 1.49-2.89), daytime symptoms (AOR = 1.92, 95% CI = 1.35-2.72), and nocturnal awakenings (AOR = 1.88, 95% CI = 1.32-2.69).

CONCLUSIONS

IPV is prevalent in adult asthmatics and consistently and significantly associated with worsened adult asthma morbidity, even after adjusting for key confounders. Further research is needed to more fully understand the mechanisms underlying these relationships.

Management Strategies to Reduce Exacerbations in non-T2 Asthma

There have been considerable advances in our understanding of asthmatic airway inflammation, resulting in a paradigm shift of classifying individuals on the basis of either the presence or the absence of type 2 (T2) inflammatory markers. Several novel monoclonal antibody therapies targeting T2 cytokines have demonstrated significant clinical effects including reductions in acute exacerbations and improvements in asthma-related quality of life and lung function for individuals with T2-high asthma. However, there have been fewer advancements in developing therapies for those without evidence of T2 airway inflammation (so-called non-T2 asthma). Here, we review the heterogeneity of molecular mechanisms responsible for initiation and regulation of non-T2 inflammation and discuss both current and potential future therapeutic options for individuals with non-T2 asthma.

Transcriptomics of biopsies identifies novel genes and pathways linked to neutrophilic inflammation in severe asthma

BACKGROUND

Severe asthma is a complex disease. Transcriptomic profiling has contributed to understanding the pathogenesis of asthma, especially type-2 inflammation. However, there is still poor understanding of non-type-2 asthma, and consequently, there are limited treatment options.

OBJECTIVE

The aim of this study was to identify differentially expressed genes (DEGs) and pathways in endobronchial biopsies associated with inflammatory phenotypes of severe asthma.

METHODS

This cross-sectional study examined endobronchial biopsies from 47 adults with severe asthma (neutrophilic asthma (NA) n = 9, eosinophilic asthma (EA) n = 22 and paucigranulocytic asthma (PGA) n = 16) and 13 healthy controls (HC). RNA was extracted and transcriptomic profiles generated (Illumina Humanref-12 V4) and analysed using GeneSpring GX14.9.1. Pathway identification using Ingenuity Pathway Analysis.

RESULTS

NA had the most distinct profile, with signature of 60 top-ranked DEGs (FC >±2) including genes associated with innate immunity response, neutrophil degranulation and IL-10 signalling. NA presented enrichment to pathways previously linked to neutrophilic inflammation; dendritic cell maturation, Th1, TREM1, inflammasome, Th17 and p38 MAPK, as well as novel links to neuroinflammation, NFAT and PKCθ signalling. EA presented similar transcriptomic profiles to PGA and HC. Despite the higher proportion of bacterial colonization in NA, no changes were observed in the transcriptomic profiles of severe asthma culture positive compared with severe asthma culture negative.

CONCLUSIONS & CLINICAL RELEVANCE

NA features a distinct transcriptomic profile with seven pathways enriched in NA compared to EA, PGA and HC. All those with severe asthma had significant enrichment for SUMOylation, basal cell carcinoma signalling and Wnt/β-catenin pathways compared to HC, despite high-dose inhaled corticosteroids. These findings contribute to the understanding of mechanistic pathways in endobronchial biopsies associated with NA and identify potential novel treatment targets for severe asthma.

Impact of Probiotic Bacteria on Respiratory Allergy Disorders

Respiratory allergy is a common disease with an increased prevalence worldwide. The effective remedy is still unknown, and a new therapeutic approach is highly desirable. The review elaborates the influence of probiotic bacteria on respiratory allergy prevention and treatment with particular emphasis on the impact of the current methods of their administration – oral and intranasal. The background of the respiratory allergy is complex thus, we focused on the usefulness of probiotics in the alleviation of different allergy factors, in particular involved in pathomechanism, local hypersensitive evidence and the importance of epithelial barrier. In this review, we have shown that (1) probiotic strains may vary in modulatory potential in respiratory allergy, (2) probiotic bacteria are beneficial in oral and intranasal administration, (3) recombinant probiotic bacteria can modulate the course of respiratory allergy.

A Component-Resolved Therapeutic Vaccine for Cockroach Allergy Made of Per a 9 and Transforming Growth Factor-β Homologue, an Immunosuppressive Protein of Brugia malayi

Allergen-specific-immunotherapy (ASIT) can cause long-term resolution of allergic diseases, reduces drug use and chances of new allergen sensitization. Nevertheless, therapeutic vaccine and data on ASIT efficacy for cockroach (CR) allergy are relatively scarce. In this study, efficacy and mechanism of a novel intranasal vaccine consisting of liposome (L)-entrapped mixture of American CR (Periplaneta americana) major allergen (Per a 9) and immunosuppressive protein of Brugia malayi nematode named transforming growth factor-beta homologue (TGH) in treatment of CR allergy were investigated along with two other vaccines (L-Per a 9 alone and L-TGH alone). All three vaccines could reduce pathogenic type 2 response and lung immunopathology in the vaccines-treated CR-allergic mice, but by different mechanisms. L-Per a 9 caused a deviation of the pathogenic type 2 to type 1 response (IFN-γ-upregulation), whereas the L-(TGH + Per a 9) and L-TGH generated regulatory immune responses including up-expression of immunosuppressive cytokine genes and increment of serum adenosine and lung indoleamine-2,3-dioxygenase-1 which are signatures of regulatory T cells (Tregs) and tolerogenic dendritic cells, respectively. The L-(TGH + Per a 9) should be further evaluated towards clinical application, as this vaccine has a propensity to induce broadly effective therapeutic effects for inhalant allergies.

Merged Affinity Network Association Clustering: Joint multi-omic/clinical clustering to identify disease endotypes

Although clinical and laboratory data have long been used to guide medical practice, this information is rarely integrated with multi-omic data to identify endotypes. We present Merged Affinity Network Association Clustering (MANAclust), a coding-free, automated pipeline enabling integration of categorical and numeric data spanning clinical and multi-omic profiles for unsupervised clustering to identify disease subsets. Using simulations and real-world data from The Cancer Genome Atlas, we demonstrate that MANAclust’s feature selection algorithms are accurate and outperform competitors. We also apply MANAclust to a clinically and multi-omically phenotyped asthma cohort. MANAclust identifies clinically and molecularly distinct clusters, including heterogeneous groups of “healthy controls” and viral and allergy-driven subsets of asthmatic subjects. We also find that subjects with similar clinical presentations have disparate molecular profiles, highlighting the need for additional testing to uncover asthma endotypes. This work facilitates data-driven personalized medicine through integration of clinical parameters with multi-omics. MANAclust is freely available at https://bitbucket.org/scottyler892/manaclust/src/master/.

Clinical data commonly used in medical practice are underutilized in multi-omic analyses to identify disease endotypes. Tyler et al. present a python package called Merged Affinity Network Association Clustering (MANAclust) that automatically processes and integrates categorical and numeric data types, facilitating the inclusion of clinical data in multi-omic endotyping efforts.

Associations of TNFA, IL17A, and RORC mRNA expression levels in peripheral blood leukocytes with obesity-related asthma in adolescents

Obesity is associated with a unique non-T2 asthma phenotype, characterised by a Th17 immune response. Retinoid-related orphan receptor C (RORC) is the master transcription factor for Th17 polarisation. We investigated the association of TNFA, IL17A, and RORC mRNA expression levels with the non-T2 phenotype. We conducted a cross-sectional study in adolescents, subdivided as follows: healthy (HA), allergic asthma without obesity (AA), obesity without asthma (OB), and non-allergic asthma with obesity (NAO). TNFA, IL17A, and RORC mRNA expression in peripheral blood leukocytes were assessed by RT-PCR. NAO exhibited higher TNFA mRNA expression levels than HA or OB, as well as the highest IL17A and RORC mRNA expression levels among the four groups. The best biomarker for discriminating non-allergic asthma among obese adolescents was RORC mRNA expression levels (area under the curve: 0.95). RORC mRNA expression levels were associated with the non-T2 asthma phenotype, hinting at a therapeutic target in obesity-related asthma.

Complement C3 and allergic asthma: a cohort study of the general population

Complement C3 plays a role in asthma development and severity. We tested the hypothesis that high plasma complement C3 concentration is associated with high risks of asthma hospitalisation and exacerbation.We prospectively assessed the risk of asthma hospitalisation in 101 029 individuals from the Copenhagen General Population Study with baseline measurements of plasma complement C3, and genotyped for rs1065489, rs429608 and rs448260 determining levels of complement C3. Risk of asthma exacerbation was further assessed in 2248 individuals with allergic asthma.The multivariable adjusted hazard ratio of asthma hospitalisation was 1.23 (95% CI 1.04-1.45) for individuals in the highest tertile (>1.19 g·L^-1) of plasma complement C3 compared with those in the lowest tertile (<1.03 g·L^-1). The C3 rs448260 genotype was associated with risk of asthma hospitalisation with an observed hazard ratio of 1.17 (95% CI 1.06-1.28) for the CC genotype compared with the AA genotype. High plasma complement C3 was associated with high levels of blood eosinophils and IgE (p for trends ≤6×10^-9), but only the SKIV2L rs429608 genotype was positively associated with blood eosinophil count (p=3×10^-4) and IgE level (p=3×10^-4). In allergic asthma, the multivariable adjusted incidence rate ratio for risk of exacerbation was 1.69 (95% CI 1.06-2.72) for individuals in the highest plasma complement C3 tertile (>1.24 g·L^-1) versus the lowest (<1.06 g·L^-1).In conclusion, a high concentration of plasma complement C3 was associated with a high risk of asthma hospitalisation in the general population and with a high risk of asthma exacerbation in individuals with allergic asthma. Our findings support a causal role of the complement system in asthma severity.

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.

Nasal interferon responses to community rhinovirus infections are similar in controls and children with asthma

BACKGROUND

Rhinovirus (RV) is the main cause of asthma exacerbations in children. Some studies reported that persons with asthma have attenuated interferon (IFN) responses to experimental RV infection compared with healthy individuals. However, responses to community-acquired RV infections in controls and children with asthma have not been compared.

OBJECTIVE

To evaluate nasal cytokine responses after natural RV infections in people with asthma and healthy children.

METHODS

We compared nasal cytokine expression among controls and children with asthma during healthy, virus-negative surveillance weeks and self-reported RV-positive sick weeks. A total of 14 controls and 21 patients with asthma were studied. Asthma disease severity was based on symptoms and medication use. Viral genome was detected by multiplex polymerase chain reaction. Nasal cytokine protein levels were determined by multiplex assays.

RESULTS

Two out of 47 surveillance weeks tested positive for RV, illustrating an asymptomatic infection rate of 5%. A total of 38 of 47 sick weeks (81%) tested positive for the respiratory virus. Of these, 33 (87%) were positive for RV. During well weeks, nasal interleukin 8 (IL-8), IL-12, and IL-1β levels were higher in children with asthma than controls. Compared with healthy virus-negative surveillance weeks, IL-8, IL-13, and interferon beta increased during colds only in patients with asthma. In both controls and children with asthma, the nasal levels of interferon gamma, interferon lambda-1, IL-1β, IL-8, and IL-10 increased during RV-positive sick weeks. During RV infection, IL-8, IL-1β, and tumor necrosis factor-α levels were strongly correlated.

CONCLUSION

In both controls and patients with asthma, natural RV infection results in robust type II and III IFN responses.

Maternal-Fetal Inflammation in the Placenta and the Developmental Origins of Health and Disease

Events in fetal life impact long-term health outcomes. The placenta is the first organ to form and is the site of juxtaposition between the maternal and fetal circulations. Most diseases of pregnancy are caused by, impact, or are reflected in the placenta. The purpose of this review is to describe the main inflammatory processes in the placenta, discuss their immunology, and relate their short- and long-term disease associations. Acute placental inflammation (API), including maternal and fetal inflammatory responses corresponds to the clinical diagnosis of chorioamnionitis and is associated with respiratory and neurodevelopmental diseases. The chronic placental inflammatory pathologies (CPI), include chronic villitis of unknown etiology, chronic deciduitis, chronic chorionitis, eosinophilic T-cell vasculitis, and chronic histiocytic intervillositis. These diseases are less-well studied, but have complex immunology and show mechanistic impacts on the fetal immune system. Overall, much work remains to be done in describing the long-term impacts of placental inflammation on offspring health.

Targeting neutrophils in asthma: A therapeutic opportunity?

Suppression of airway inflammation with inhaled corticosteroids has been the key therapeutic approach for asthma for many years. Identification of inflammatory phenotypes in asthma has moreover led to important breakthroughs, e.g. with specific targeting of the IL-5 pathway as add-on treatment in difficult-to-treat eosinophilic asthma. However, the impact of interfering with the neutrophilic component in asthma is less documented and understood. This review provides an overview of established and recent insights with regard to the role of neutrophils in asthma, focusing on research in humans. We will describe the main drivers of neutrophilic responses in asthma, the heterogeneity in neutrophils and how they could contribute to asthma pathogenesis. Moreover we will describe findings from clinical trials, in which neutrophilic inflammation was targeted. It is clear that neutrophils are important actors in asthma development and play a role in exacerbations. However, more research is required to fully understand how modulation of neutrophil activity could lead to a significant benefit in asthma patients with airway neutrophilia.

Genome-Wide Analysis Reveals Mucociliary Remodeling of the Nasal Airway Epithelium Induced by Urban PM2.5

Air pollution particulate matter <2.5 μm (PM_2.5) exposure is associated with poor respiratory outcomes. Mechanisms underlying PM_2.5-induced lung pathobiology are poorly understood but likely involve cellular and molecular changes to the airway epithelium. We extracted and chemically characterized the organic and water-soluble components of air pollution PM_2.5 samples, then determined the whole transcriptome response of human nasal mucociliary airway epithelial cultures to a dose series of PM_2.5 extracts. We found that PM_2.5 organic extract (OE), but not water-soluble extract, elicited a potent, dose-dependent transcriptomic response from the mucociliary epithelium. Exposure to a moderate OE dose modified the expression of 424 genes, including activation of aryl hydrocarbon receptor signaling and an IL-1 inflammatory program. We generated an OE-response gene network defined by eight functional enrichment groups, which exhibited high connectivity through CYP1A1, IL1A, and IL1B. This OE exposure also robustly activated a mucus secretory expression program (>100 genes), which included transcriptional drivers of mucus metaplasia (SPDEF and FOXA3). Exposure to a higher OE dose modified the expression of 1,240 genes and further exacerbated expression responses observed at the moderate dose, including the mucus secretory program. Moreover, the higher OE dose significantly increased the MUC5AC/MUC5B gel-forming mucin expression ratio and strongly downregulated ciliated cell expression programs, including key ciliating cell transcription factors (e.g., FOXJ1 and MCIDAS). Chronic OE stimulation induced mucus metaplasia-like remodeling characterized by increases in MUC5AC⁺ secretory cells and MUC5AC mucus secretions. This epithelial remodeling may underlie poor respiratory outcomes associated with high PM_2.5 exposure.

Sargassum horneri extract containing mojabanchromanol attenuates the particulate matter exacerbated allergic asthma through reduction of Th2 and Th17 response in mice

Airborne particulate matter (PM) has become a serious health issue causing pulmonary diseases such as asthma. Due to the side effects and non-specificity of conventional drugs, there is a need to develop natural-product-based alternative treatments. Sargassum horneri is a brown alga shown to have anti-oxidant, anti-inflammatory, and anti-allergic effects. Thus, we sought to determine whether ethanol extract of Sargassum horneri (SHE) mitigates the effect of PM exposure on asthma development. To establish a mouse model of asthma, BALB/c mice were sensitized with ovalbumin (OVA, 10 μg) and challenged with PM (5 mg/m3) for 7 days consecutively. SHE (200, 400 mg/kg), Prednisone (5 mg/kg), or PBS was daily administrated orally before PM exposure. SHE mitigated PM exacerbated dendritic cell activation. More importantly, SHE restrained Th2 polarization by attenuating transcription factors GATA3 and STAT5, which further mitigated the expression of Th2 cytokines interleukin (IL)-4, IL-5, and IL-13 in the lung homogenates of PM-exacerbated asthmatic mice. SHE further attenuated PM-exacerbated eosinophil infiltration in the lung, trachea, and BALF. In addition, SHE markedly mitigated the activation of mast cells and the IgE level in serum. Concomitantly, SHE further restrained the Th17 cell response in PM-exposed allergic mice through attenuating expression of transcription factors RORγT, STAT3 and expression of relevant effector cytokines IL-17a. This resulted in mitigated neutrophil infiltration in the lung. Taken together, SHE significantly suppressed PM-exacerbated hypersecretion of mucus in asthmatic mice. These results suggest that SHE has therapeutic potential for treating PM-exacerbated allergic asthma through concomitantly inhibiting Th2/Th17 responses.