Asthma phenotypes and interleukin-13--moving closer to personalized medicine

Molecular T2 asthma phenotypes are stable but heterogeneous: the usefulness of periostin for endotyping

Background

The stability of molecular T2/non-T2 phenotypes remains uncertain. The objectives of this study were to assess the stability of these phenotypes and the correlation between serum periostin and asthma T2 phenotypes and endotypes.

Methods

Demographics, clinical data, and blood samples were collected. Patients diagnosed with moderate-to-severe asthma were classified into T2 or non-T2 according to previously defined thresholds of blood eosinophilia and serum total IgE levels. Asthma endotype was also determined. After at least 1 year of follow-up, the stability of T2 phenotypes and endotypes was assessed.

Results

A total of 53 patients (72% women), mean age 47 years (range 16-77), were included. In the initial and second evaluations, the T2 phenotype was found in 41.5% and 43.4% of patients and the non-T2 phenotype was found in 58.4% and 56.7%, respectively. The mean [standard deviation (SD), range] serum periostin level was 52.7 (26.2, 22.6-129.7) ng/mL in patients with T2 phenotype, and 39.3 (25.6, 7.7-104.) ng/mL in non-T2 patients (P = 0.063). Periostin levels correlated to endotypes (P = 0.001): 45.7 (27.9) ng/mL in allergic asthma (n = 16 patients), 64.7 (24.9) in aspirin-exacerbated respiratory disease (n = 14), 59.0 (27.6) ng/mL in late-onset eosinophilic asthma (n = 4), and 28.3 (13.3) ng/mL in non-eosinophilic asthma (n = 18).

Conclusions

T2 and non-T2 asthma phenotypes assessed by accessible methods in daily practice are stable over time yet widely heterogeneous. Serum periostin does not discriminate between T2 and non-T2 phenotypes. Nevertheless, its correlation to asthma endotypes may contribute to guide therapies targeting T2 cytokines in a more personalized approach.

Immunological profiling and development of a sensing device for detection of IL-13 in COPD and asthma

Chronic obstructive pulmonary disease (COPD) and asthma are the two most common obstructive lung diseases which affects millions worldwide and impose an enormous burden on global healthcare. The overlapping features shared by these two diseases often make differential diagnosis difficult to achieve, leading to misdiagnosis of these patients. Both asthma and COPD are associated with chronic inflammation of the airways which is perpetuated by the interplay between immunological mediators. The crucial role played by these mediators make them attractive targets for disease diagnosis. The present study investigates the immunological mediator profile in these patients as compared with controls. Further, a potential biomarker for the development of a sensing platform is identified. Multiplexed analysis of 8 commonly studied immunological markers (IL-4, IL-5, IL-6, IL-13, TGF-β, IFN-γ, MCP-1 and NGAL) in serum showed distinct dysregulation pattern, with IL-13 showing the highest potential for differential diagnosis. An impedimetric self-assembled monolayer (SAM) based sensor for detecting IL-13 is developed to distinguish between asthma and COPD. The device shows reliable output with high accuracy and sensitivity towards the detection of IL-13.

Reinventing polysomnography in the age of precision medicine

For almost 50 years, sleep laboratories around the world have been collecting massive amounts of polysomnographic (PSG) physiological data to diagnose sleep disorders, the majority of which are not utilized in the clinical setting. Only a small fraction of the information available within these signals is utilized to generate indices. For example, the apnea-hypopnea index (AHI) remains the primary tool for diagnostic and therapeutic decision-making for obstructive sleep apnea (OSA) despite repeated studies showing it to be inadequate in predicting clinical consequences. Today, there are many novel approaches to PSG signals, making it possible to extract more complex metrics and analyses that are potentially more clinically relevant for individual patients. However, the pathway to implement novel PSG metrics/analyses into routine clinical practice is unclear. Our goal with this review is to highlight some of the novel PSG metrics/analyses that are becoming available. We suggest that stronger academic-industry relationships would facilitate the development of state-of-the-art clinical research to establish the value of novel PSG metrics/analyses in clinical sleep medicine. Collectively, as a sleep community, it is time to reinvent how we utilize the polysomnography to move us towards Precision Sleep Medicine.

Clinical Applications Targeting Periostin

Since periostin is expressed and functioned in incredible diseases , clinical applications have been initiated to directly target periostin for inhibition or activation, or periostin expression is utilized to indicate the disease state or a marker for curing diseases, which will provide novel methods in clinical applications.

Blood Eosinophils as Biomarkers to Drive Treatment Choices in Asthma and COPD

BACKGROUND

Asthma and COPD are complex, heterogeneous conditions comprising a wide range of phenotypes, some of which are refractory to currently available treatments. Elucidation of these phenotypes and identification of biomarkers with which to recognize them and guide appropriate treatment remain a priority.

OBJECTIVE

This review describes the utility of blood eosinophils as a surrogate biomarker of eosinophilic airway inflammation, a common feature of specific asthma and COPD phenotypes. The role of blood eosinophils in airway disease is described, as is their relevance in reflecting airway eosinophilia. Each disease is discussed separately as the manner in which blood eosinophils might be used as biomarkers differs. Focusing on patients with severe disease (persistent eosinophilic asthma and exacerbating COPD), we evaluate evidence examining eosinophils as biomarkers.

RESULTS

In asthma, the rationale for using blood eosinophils to guide treatment is clearly defined, backed by prospective, well-controlled studies. Higher eosinophil counts identify patients with more severe disease and poorer outcomes, patients for whom biologic therapies targeting allergic and/or eosinophilic pathways are recommended. In COPD, the evidence is less robust. High blood eosinophil counts are a modest predictor of future exacerbations, and may predict a favourable response to ICS on top of LABA/LAMA, especially in patients with a history of frequent exacerbations.

CONCLUSION

Before extensive application in clinical practice, further evaluation of these findings in prospective clinical studies, and standardization of the appropriate thresholds of clinically relevant eosinophilia are needed, together with establishing whether single or multiple measurements are required in different clinical settings.

Periostin function in communication with extracellular matrices

Periostin is a secretory protein with a multi-domain structure, comprising an amino-terminal cysteine-rich EMI domain, four internal FAS 1 domains, and a carboxyl-terminal hydrophilic domain. These adjacent domains bind to extracellular matrix proteins (type I collagen, fibronectin, tenascin-C, and laminin γ2), and BMP-1 that catalyzes crosslinking of type I collagen, and proteoglycans, which play a role in cell adhesion. The binding sites on periostin have been demonstrated to contribute to the mechanical strength of connective tissues, enhancing intermolecular interactions in close proximity and their assembly into extracellular matrix architectures, where periostin plays further essential roles in physiological maintenance and pathological progression. Furthermore, periostin also binds to Notch 1 and CCN3, which have functions in maintenance of stemness, thus opening up a new field of periostin action.

Innate Lymphoid Cells: A Promising New Regulator in Fibrotic Diseases

Fibrosis is a consequence of chronic inflammation and the persistent accumulation of extracellular matrix, for which the cycle of tissue injury and repair becomes a predominant feature. Both the innate and adaptive immune systems play key roles in the progress of fibrosis. The recently identified subsets of innate lymphoid cells (ILCs), which are mainly localize to epithelial surfaces, have been characterized as regulators of chronic inflammation and tissue remodeling, representing a functional bridge between the innate and adaptive immunity. Moreover, recent research has implicated ILCs as potential contributing factors to several kinds of fibrosis diseases, such as hepatic fibrosis and pulmonary fibrosis. Here, we will summarize and discuss the key roles of ILCs and their related factors in fibrotic diseases and their potential for translation to the clinic.

IL-13 Augments Compressive Stress-Induced Tissue Factor Expression in Human Airway Epithelial Cells

Tissue factor (TF) is best known as a cellular initiator of coagulation, but it is also a multifunctional protein that has been implicated in multiple pathophysiologic conditions, including asthma. In the lung, airway epithelial cells express TF, but it is unknown how TF expression is regulated by asthma-associated mediators. We investigated the role of IL-13, a type 2 cytokine, alone and in combination with compressive stress, which mimics asthmatic bronchoconstriction, on TF expression and release of TF-positive extracellular vesicles from primary normal human bronchial epithelial cells. Well-differentiated normal human bronchial epithelial cells were treated with IL-13 and compressive stress, alone and in combination. TF mRNA, protein and activity were measured in the cells and conditioned media. TF was also measured in the bronchoalveolar lavage (BAL) fluid of allergen-challenged mice and patients with asthma. IL-13 and compressive stress increased TF expression, but only compressive stress induced TF-positive extracellular vesicle release. Pretreatment with IL-13 augmented compressive stress-induced TF expression and release. TF protein and activity in BAL fluid were increased in allergen-sensitized and -challenged mice. TF was elevated in the BAL fluid of patients with mild asthma after an allergen challenge. Our in vitro and in vivo data indicate close cooperation between mechanical and inflammatory stimuli on TF expression and release of TF-positive extracellular vesicles in the lungs, which may contribute to pathophysiology of asthma.

Point-of-Care Technologies for the Advancement of Precision Medicine in Heart, Lung, Blood, and Sleep Disorders

The commercialization of new point of care technologies holds great potential in facilitating and advancing precision medicine in heart, lung, blood, and sleep (HLBS) disorders. The delivery of individually tailored health care to a patient depends on how well that patient's health condition can be interrogated and monitored. Point of care technologies may enable access to rapid and cost-effective interrogation of a patient's health condition in near real time. Currently, physiological data are largely limited to single-time-point collection at the hospital or clinic, whereas critical information on some conditions must be collected in the home, when symptoms occur, or at regular intervals over time. A variety of HLBS disorders are highly dependent on transient variables, such as patient activity level, environment, time of day, and so on. Consequently, the National Heart Lung and Blood Institute sponsored a request for applications to support the development and commercialization of novel point-of-care technologies through small businesses (RFA-HL-14-011 and RFA-HL-14-017). Three of the supported research projects are described to highlight particular point-of-care needs for HLBS disorders and the breadth of emerging technologies. While significant obstacles remain to the commercialization of such technologies, these advancements will be required to achieve precision medicine.

Biomarkers Guided Treatment Strategies in Adult Patients with Asthma: Ready for the Clinical Field?

Asthma is a chronic inflammatory airways disorder mainly characterized by heterogeneity. In the more severe forms, a discordance often exists between symptoms and inflammation. Difficulty in managing asthma derives partly from the multiple phenotypes existing and our inability to recognize them. The use of non-invasive, with main representative the fraction of exhaled nitric oxide, or semi-invasive techniques such as induced sputum are effective tools that can help us to guide asthma treatment. In the latest years, several serum biomarkers related to asthmatic inflammation have been used for the better recognition of asthma sub-phenotypes to achieve optimization of therapy and disease outcome. In patients with mild-moderate asthma, as well as patients with more severe asthma, the use of blood eosinophils revealed an acceptable accuracy for the prediction of airway eosinophilia indicating that in future studies may facilitate both individualized treatment and management of asthma. None of the above techniques have been incorporated in clinical practice although sputum eosinophils can be used in patients with severe asthma particularly in specialized centers with great experience. Of great interest are blood eosinophils since current data support their role either as tool for treatment selections or/and as a biomarker of airway eosinophilia.

TGF-β-mediated airway tolerance to allergens induced by peptide-based immunomodulatory mucosal vaccination

We sought to modulate mucosal immune responses using neonatal vaccination to avert the development of allergic airways disease (AAD). Pulmonary pathology in AAD is driven by T helper (TH)2 cytokines, in particular interleukin (IL)4 and IL13, the expression and actions of which are regulated by the transcription factor STAT6. We developed a peptide homolog of STAT6, STAT6-IP. Neonatal mice given, intranasally, STAT6-IP, in an effort to modulate de novo airways immune responses, developed tolerance following subsequent allergen sensitization, with either ovalbumin or ragweed allergens, as demonstrated by reduced TH2 cytokines and specific immunoglobulin (Ig)E and the significant increases in the latency-associated peptide (LAP)(+) T-regulatory (Treg) cell subset and expression of transforming growth factor (TGF)-β. This regulatory phenotype was transferrable by CD4(+) T cells or CD11c(+) dendritic cells (DCs) derived from STAT6-IP-vaccinated mice. Anti-TGF-β treatment during allergen sensitization, however, re-established the pro-inflammatory TH2 response. Thus, neonatal STAT6-IP vaccination induces prospective TGF-β-dependent tolerance to allergen and constitutes a novel highly effective immunomodulatory allergy prevention strategy.

The Effect of Combined Therapy ICS/LABA and ICS/LABA plus Montelukast in Patients with Uncontrolled Severe Persistent Asthma Based on the Serum IL-13 and FEV1

BACKGROUND

IL-13 is one of many cytokines responsible for the chronic inflammation of asthma.

AIM

The aim of this study was to determine the effect of combined therapy ICS/LABA and ICS/LABA plus Montelukast in patients with uncontrolled severe persistent asthma by analyzing of serum IL-13 and FEV1 before the treatment and after 6 months of therapy.

MATERIAL AND METHODS

In study we included two groups. First group with 27 patients were treated with ICS/LABA. Second group with 29 patients were treated with ICS/LABA plus Montelukast. In each of them were measured serum IL-13 levels by the ELISA method and FEV1 before and after 6 months of treatment. Results were statistically analyzed according to the Wilcoxon Pairs Test and T-test.

RESULTS

The obtained results in both groups showed that the serum IL-13 before the start of therapy were much higher and after 6 months of treatment significantly reduces their value, which in the second group were more expressed. The difference in the average value of FEV1 in both groups before and after therapy was statistically significant.

CONCLUSION

Treatment with ICS/LABA plus Montelukast proved superior compared to therapy of ICS/LABA in patients with uncontrolled severe persistent asthma and allows achievement of well controlled of asthma with subjective clinical improvement.

Treatment responsiveness of phenotypes of symptomatic airways obstruction in adults

BACKGROUND

Asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous disorders encompassing different phenotypes of airflow obstruction, which might differ in their response to treatment.

OBJECTIVE

The aim of this study was to determine distinct phenotypes comprising the syndromes of asthma and COPD and the treatment responsiveness of these phenotypes to inhaled β-agonist, antimuscarinic, and corticosteroid therapy.

METHODS

We undertook a cross-sectional study with 3 phases. In phase 1, 1,264 participants aged 18 to 75 years with self-reported current wheeze and breathlessness were identified from a random population sample of 16,459. In phase 2, 451 participants attended for detailed assessment, including responsiveness to inhaled salbutamol and ipratropium bromide. In phase 3, 168 steroid-naive participants were enrolled in a 12-week trial of inhaled budesonide. Cluster analysis was performed in 389 participants who completed phase 2 with full data. Treatment responsiveness was compared between phenotypes.

RESULTS

Cluster analysis identified 5 phenotypes: moderate-to-severe childhood-onset atopic asthma, asthma-COPD overlap, obese-comorbid, mild childhood-onset atopic asthma, and mild intermittent. Bronchodilation after salbutamol was equal to or greater than that after ipratropium for all phenotypes. The moderate-to-severe childhood-onset atopic asthma, asthma-COPD overlap, and obese-comorbid phenotypes had greater efficacy with inhaled corticosteroid treatment than the mild intermittent group.

CONCLUSION

Cluster analysis of adults with symptomatic airflow obstruction identifies 5 disease phenotypes, including asthma-COPD overlap and obese-comorbid phenotypes, and provides evidence that patients with the asthma-COPD overlap syndrome might benefit from inhaled corticosteroid therapy.

Beyond TGFβ--novel ways to target airway and parenchymal fibrosis

Within the lungs, fibrosis can affect both the parenchyma and the airways. Fibrosis is a hallmark pathological change in the parenchyma in patients with idiopathic pulmonary fibrosis (IPF), whilst in asthma or chronic obstructive pulmonary disease (COPD) fibrosis is a component of the remodelling of the airways. In the past decade, significant advances have been made in understanding the disease behaviour and pathogenesis of parenchymal and airway fibrosis and as a result a variety of novel therapeutic targets for slowing or preventing progression of these fibrotic changes have been identified. This review highlights a number of these targets and discusses the potential for treating parenchymal or airway fibrosis through these mediators/pathways in the future.

Eosinophils as a pharmacological target for the treatment of allergic diseases

Eosinophils are innate immune cells and active players in inflammatory responses. Their activation and increased levels in the blood and at specific sites are associated with parasitic infections and several inflammatory conditions, notably allergic diseases in which eosinophils are considered to be damaging cells. Intervention targeting eosinophils is thought to prevent and/or limit irreversible organ damage and other eosinophil-associated disorders like hypereosinophilic syndromes, some cancers and autoimmune diseases. Several eosinophil-targeted therapeutic agents which block specific steps in eosinophil differentiation, migration and activation have recently been developed, showing encouraging results and new insights into their specific role in allergy. Here, we review some potentially effective drug compounds, their drawbacks and future prospective focusing on allergic diseases.

Linking GATA-3 and interleukin-13: implications in asthma

INTRODUCTION

Asthma is one of the serious global health problems and cause of huge mortality and morbidity. It is characterized by persistent airway inflammation, airway hyperresponsiveness, increased IgE levels and mucus hypersecretion. Asthma is mediated by dominant Th2 immune response, causing enhanced expression of Th2 cytokines. These cytokines are responsible for the various pathological changes associated with allergic asthma.

MATERIALS AND METHODS

The role of Th2 cells in the pathogenesis of the asthma is primarily mediated through the cytokine IL-13, also produced by type 2 innate lymphoid cells, that comes under the transcriptional regulation of GATA3. In this review we will try to explore the link between IL-13 and GATA3 in the progression and regulation of asthma and its possible role as a therapeutic target.

CONCLUSION

Inhibition of GATA3 activity or blockade of GATA3 expression may attenuate the interleukin-13 mediated asthma phenotypes. So, GATA3 might be a potential therapeutic target for the treatment of allergic asthma.

IL-25 and type 2 innate lymphoid cells induce pulmonary fibrosis

Disease conditions associated with pulmonary fibrosis are progressive and have a poor long-term prognosis with irreversible changes in airway architecture leading to marked morbidity and mortalities. Using murine models we demonstrate a role for interleukin (IL)-25 in the generation of pulmonary fibrosis. Mechanistically, we identify IL-13 release from type 2 innate lymphoid cells (ILC2) as sufficient to drive collagen deposition in the lungs of challenged mice and suggest this as a potential mechanism through which IL-25 is acting. Additionally, we demonstrate that in human idiopathic pulmonary fibrosis there is increased pulmonary expression of IL-25 and also observe a population ILC2 in the lungs of idiopathic pulmonary fibrosis patients. Collectively, we present an innate mechanism for the generation of pulmonary fibrosis, via IL-25 and ILC2, that occurs independently of T-cell-mediated antigen-specific immune responses. These results suggest the potential of therapeutically targeting IL-25 and ILC2 for the treatment of human fibrotic diseases.

Newer treatments in the management of pediatric asthma

Asthma control remains a significant challenge in the pediatric age range in which ongoing loss of lung function in children with persistent asthma has been reported, despite the use of regular preventer therapy. This has important implications for observed mortality and morbidity during adulthood. Over the past decade, there has been an emergence of other treatment adjuncts, such as anti-Immunoglobulin E (IgE)-directed therapy, low dose theophylline, and the use of macrolide antibiotics, yet their exact role in asthma management remains unclear, despite omalizumab now being incorporated into several international asthma guidelines. As with many aspects of pediatric care, this is driven by a lack of appropriately designed pediatric trials. Extrapolation of data reported in adult studies may be appropriate for adolescent asthma, but is not for younger age groups, in which important pathophysiological differences exist. Novel drugs under development offer potential for benefit in the future, but to date existing data are in most cases limited to adults. Pediatric asthma also offers unique potential to prevent or modify the underlying pathophysiology. Although attempts to do so have been unsuccessful to date, advances may yet come from this approach, as our understanding about the interaction between genetics, environmental factors, and viral illness improve. This review provides an overview of the newer treatment options available for management of pediatric asthma and discusses the merits of other novel therapies in development, as we search to optimize management and improve future outcomes.

The schistosoma granuloma: friend or foe?

Infection of man with Schistosoma species of trematode parasite causes marked chronic morbidity. Individuals that become infected with Schistosomes may develop a spectrum of pathology ranging from mild cercarial dermatitis to severe tissue inflammation, in particular within the liver and intestines, which can lead to life threatening hepatosplenomegaly. It is well established that the etiopathology during schistosomiasis is primarily due to an excessive or unregulated inflammatory response to the parasite, in particular to eggs that become trapped in various tissue. The eggs forms the foci of a classical type 2 granulomatous inflammation, characterized by an eosinophil-rich, CD4⁺ T helper (Th) 2 cell dominated infiltrate with additional infiltration of alternatively activated macrophages (M2). Indeed the sequela of the type 2 perioval granuloma is marked fibroblast infiltration and development of fibrosis. Paradoxically, while the granuloma is the cause of pathology it also can afford some protection, whereby the granuloma minimizes collateral tissue damage in the liver and intestines. Furthermore, the parasite is exquisitely reliant on the host to mount a granulomatous reaction to the eggs as this inflammatory response facilitates the successful excretion of the eggs from the host. In this focused review we will address the conundrum of the S. mansoni granuloma acting as both friend and foe in inflammation during infection.

Targeted therapies for systemic sclerosis

Pathogenic processes that underlie the development and progression of systemic sclerosis (SSc) are being defined in preclinical, clinical and genetic studies. Important evidence of interplay between the vasculature, connective tissue and specialized epithelial structures is emerging, and abnormalities of both the innate and adaptive immune systems have been identified. In this context, information regarding pivotal mediators, pathways or cell types that could be targets for therapeutic intervention, and that might offer potential for true disease modification, is accruing. Precedent for the regression of some aspects of the pathology has been set in clinical studies showing that potential exists to improve tissue structure and function as well as to prevent disease progression. This article reviews the concept of targeted therapies and considers potential pathways and processes that might be attenuated by therapeutic intervention in SSc. As well as improving outcomes, such approaches will undoubtedly provide information about pathogenesis. The concept of translational medicine is especially relevant in SSc, and we anticipate that the elusive goal of an effective antifibrotic treatment will emerge from one of the several clinical trials currently underway or planned in this disease. Therapeutic advances in SSc would have implications and potential beyond autoimmune rheumatic diseases.

The use of biological agents for the treatment of fungal asthma and allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is a virulent manifestation of the Th2 asthma endotype that includes asthma with fungal sensitization, raising the feasibility of biological therapies targeting Th2 pathway molecules or cells. The first molecule amenable to clinical intervention with a biological was IgE. Omalizumab, a humanized monoclonal antibody (Mab), targets the same epitope on the IgE CH3 region that binds to and crosslinks high-affinity receptors on mast cells and basophils, thereby initiating the allergic inflammatory cascade. Omalizumab is licensed for allergic asthma and has been beneficial in uncontrolled studies of ABPA, reducing exacerbations and steroid requirements. Trials of several Mabs directed against the Th2 cytokine IL-5 show clinical benefit in patients with a severe refractory eosinophilic asthma phenotype, while a Mab against IL-13 is effective in asthma patients with a Th2-high endotype. Immunodulation is also feasible with small molecule biologicals, such as antisense oligodeoxynucleotides and cholecalciferol. Controlled trials of Th2-inhibiting biologicals in patients with ABPA and severe asthma with fungal sensitization appear warranted.

Microbes and mucosal immune responses in asthma

The substantial increase in the worldwide prevalence of asthma and atopy has been attributed to lifestyle changes that reduce exposure to bacteria. A recent insight is that the largely bacterial microbiome maintains a state of basal immune homoeostasis, which modulates immune responses to microbial pathogens. However, some respiratory viral infections cause bronchiolitis of infancy and childhood wheeze, and can exacerbate established asthma; whereas allergens can partly mimic infectious agents. New insights into the host’s innate sensing systems, combined with recently developed methods that characterise commensal and pathogenic microbial exposure, now allow a unified theory for how microbes cause mucosal inflammation in asthma. The respiratory mucosa provides a key microbial interface where epithelial and dendritic cells interact with a range of functionally distinct lymphocytes. Lymphoid cells then control a range of pathways, both innate and specific, which organise the host mucosal immune response. Fundamental to innate immune responses to microbes are the interactions between pathogen-associated molecular patterns and pattern recognition receptors, which are associated with production of type I interferons, proinflammatory cytokines, and the T-helper-2 cell pathway in predisposed people. These coordinated, dynamic immune responses underlie the differing asthma phenotypes, which we delineate in terms of Seven Ages of Asthma. An understanding of the role of microbes in the atopic march towards asthma, and in causing exacerbations of established asthma, provides the rationale for new specific treatments that can be assessed in clinical trials. On the basis of these new ideas, specific host biomarkers might then allow personalised treatment to become a reality for patients with asthma.

Evaluation of nasal epithelium sampling as a tool in the preclinical development of siRNA-based therapeutics for asthma

The development of siRNA-based asthma therapeutics is currently hampered by a paucity of relevant biomarkers and the need to ascertain tissue-specific gene targeting in the context of active disease. Epithelial STAT6 expression is fundamental to asthma pathogenesis in which inflammatory changes are found throughout the respiratory tract. Therefore, to improve preclinical evaluation, we tested the efficacy of STAT6-targeting siRNA within nasal epithelial cells (NEC's) obtained from asthmatic and non-asthmatic donors. STAT6 expression was invariant in both donor groups and amenable to suppression by siRNA treatment. In addition, STAT6 mRNA was also suppressible by apically delivered siRNA treatment in comparative differentiated nasal epithelial cell-line monolayer cultures. Analysis of donor NEC's showed consistent elevation in CCL26 (eotaxin-3) mRNA within the asthmatic group suggesting potential as a relevant biomarker. Furthermore, targeting of STAT6 with siRNA attenuated IL-13-driven CCL26 expression in these cells, pointing to the utility of this approach in preclinical testing. Finally, siRNA-mediated suppression of STAT6 was independent of donor disease phenotype or epithelial cell differentiation status, signifying therapeutic potential.

IL-13 in asthma and allergic disease: asthma phenotypes and targeted therapies

Decades of research in animal models have provided abundant evidence to show that IL-13 is a key T(H)2 cytokine that directs many of the important features of airway inflammation and remodeling in patients with allergic asthma. Several promising focused therapies for asthma that target the IL-13/IL-4/signal transducer and activator of transcription 6 pathway are in development, including anti-IL-13 mAbs and IL-4 receptor antagonists. The efficacy of these new potential asthma therapies depends on the responsiveness of patients. However, an understanding of how IL-13-directed therapies might benefit asthmatic patients is confounded by the complex heterogeneity of the disease. Recent efforts to classify subphenotypes of asthma have focused on sputum cellular inflammation profiles, as well as cluster analyses of clinical variables and molecular and genetic signatures. Researchers and clinicians can now evaluate biomarkers of T(H)2-driven airway inflammation in asthmatic patients, such as serum IgE levels, sputum eosinophil counts, fraction of exhaled nitric oxide levels, and serum periostin levels, to aid decision making in clinical trials and drug development and to identify subsets of patients who might benefit from therapies. Although it is unlikely that these therapies will benefit all asthmatic patients with this heterogeneous disease, advances in understanding asthma subphenotypes in relation to clinical variables and T(H)2 cytokine responses offer the opportunity to improve the efficacy and safety of proposed therapies for asthma.

Mechanisms of fibrosis: therapeutic translation for fibrotic disease

Fibrosis is a pathological feature of most chronic inflammatory diseases. Fibrosis, or scarring, is defined by the accumulation of excess extracellular matrix components. If highly progressive, the fibrotic process eventually leads to organ malfunction and death. Fibrosis affects nearly every tissue in the body. Here we discuss how key components of the innate and adaptive immune response contribute to the pathogenesis of fibrosis. We also describe how cell-intrinsic changes in important structural cells can perpetuate the fibrotic response by regulating the differentiation, recruitment, proliferation and activation of extracellular matrix-producing myofibroblasts. Finally, we highlight some of the key mechanisms and pathways of fibrosis that are being targeted as potential therapies for a variety of important human diseases.

Mechanisms of fibrosis: therapeutic translation for fibrotic disease

Fibrosis is a pathological feature of most chronic inflammatory diseases. Fibrosis, or scarring, is defined by the accumulation of excess extracellular matrix components. If highly progressive, the fibrotic process eventually leads to organ malfunction and death. Fibrosis affects nearly every tissue in the body. Here we discuss how key components of the innate and adaptive immune response contribute to the pathogenesis of fibrosis. We also describe how cell-intrinsic changes in important structural cells can perpetuate the fibrotic response by regulating the differentiation, recruitment, proliferation and activation of extracellular matrix-producing myofibroblasts. Finally, we highlight some of the key mechanisms and pathways of fibrosis that are being targeted as potential therapies for a variety of important human diseases.

Responses to ragweed pollen in a pollen challenge chamber versus seasonal exposure identify allergic rhinoconjunctivitis endotypes

BACKGROUND

The level of concordance between allergic symptoms induced on exposure to pollen in a pollen challenge chamber (PCC) versus the natural season is unknown.

OBJECTIVE

We sought to test the hypothesis that the symptom levels of allergic rhinoconjunctivitis elicited after out-of-season exposure to short ragweed in a PCC and during the natural season for giant ragweed pollen are highly correlated.

METHODS

Thirty-one ragweed-sensitive participants recorded symptoms for 15 days during the natural giant ragweed season in San Antonio, Texas. Twenty-six of these participants were challenged to short ragweed pollen in a PCC for 3 hours per day for up to 4 days.

RESULTS

In the PCC participants were dichotomized into those in whom low versus high levels of symptoms developed slowly or rapidly (ie, slow/low vs rapid/high). Each successive exposure visit associated with a progressive increase in symptom levels that approximated those experienced during the natural season. Hierarchic clustering identified 3 endotypes: endotypes I and II reflected concordantly low (n= 7) versus high (n = 14) total symptom scores (TSSs) in both the natural season and the PCC, respectively. Accordingly, the correlation between the TSSs recorded in the natural season and in the PCC for these 21 participants was very high. Although participants with endotype III (n = 5) had greater TSSs in the natural season than in the PCC, the degree of correlation between the TSSs remained high.

CONCLUSIONS

Our findings affirm our hypothesis, underscore the high cross-reactivity between distinct pollens, and highlight the utility of the PCC to identify novel allergy endotypes that might have contrasting mechanistic underpinnings and potentially therapeutic responses.

Serum levels of interleukin-13 and interferon-gamma from adult patients with asthma in Mysore

Serum protein analysis for noninvasive quantification of airway inflammation in asthma is a promising research tool in the field of lung diseases. Cytokines are believed to have major role in inflammatory process of the airways of the lung. There is an imbalance between T-helper (Th)-2 cells, which secrete interleukin (IL)-4 and interleukin (IL)-13, and Th1 cells, which secrete interferon (IFN)-gamma in asthma. To test the hypothesis that serum IL-13 and IL-4 levels may be elevated whereas IFN-gamma would be decreased in this cohort of patients, a property that could make them possible candidate biomarkers in determining asthma occurrence and severity, we measured concentrations of IL-4, IL-13 and IFN-gamma in serum samples of 88 subjects (44 normal, 12 with mild asthma, 16 with moderate asthma, and 16 with severe asthma). Serum Levels of IL-4, IL-13, and IFN-gamma were determined by an enzyme-linked immune-sorbent assay (ELISA). Median serum level of IFN-gamma in asthmatic patients was 8.0 pg/ml, while it was 11.4 pg/ml in healthy controls. However, the difference was not significant. Among the different age groups in whom IFN-gamma was assessed, the highest median value in both cases and controls was observed in the age group of 31-40 years. The median serum level of IL-13 was 40.0 pg/ml in asthmatic patients and 58.25 pg/ml in healthy controls. The difference was not significant. On subgroup analysis, no significant difference of IFN-gamma and IL-13 between asthma of different severities was observed. The study also revealed nonsignificant difference of serum cytokines with the duration of asthma, number of allergens, and severity of sensitization. Normal serum levels of IFN-gamma and IL-13 in asthmatic patients suggest their neutral role in the inflammatory process; however, more studies are required to establish the effect of these cytokines in adulthood asthma in different ethnic populations.

Emerging drugs for asthma

INTRODUCTION

Current drug treatments for asthma relieve bronchospasm and airway inflammation but do not offer a cure, and symptoms return when treatment is stopped. Asthma management guidelines emphasize the importance of effective asthma treatment to achieve and maintain asthma control. However, despite widely available and effective treatments, achieving asthma control is still an unmet need for many patients.

AREAS COVERED

Remarkable efforts have been made to identify the characteristic features of difficult-to-control (usually severe) asthma that are different from those described for mild-to-moderate asthma, setting the stage for the development of new and even individualized therapies. The most fascinating options of the new asthma treatments are biologic therapies, in particular monoclonal antibodies. In addition, some novel once-daily combinations of long-acting β(2)-agonist and inhaled corticosteroids are under development.

EXPERT OPINION

Asthma is a complex syndrome made up of a number of disease variants or asthma phenotypes, with different underlying pathophysiology. As different drugs target different pathways, it is necessary to determine the individual profile of pathophysiological abnormalities for each patient. Several cytokines have been implicated in the inflammatory cascades leading to the different asthma phenotypes, and the most relevant ones are discussed. The challenge in treating asthma resides precisely in its heterogeneity.

T cell homing to epithelial barriers in allergic disease

Allergic inflammation develops in tissues that have large epithelial surface areas that are exposed to the environment, such as the lung, skin and gut. In the steady state, antigen-experienced memory T cells patrol these peripheral tissues to facilitate swift immune responses against invading pathogens. In at least two allergy-prone organs, the skin and the gut, memory T cells are programmed during the initial antigen priming to express trafficking receptors that enable them to preferentially home to these organs. In this review we propose that tissue-specific memory and inflammation-specific T cell trafficking facilitates the development of allergic disease in these organs. We thus review recent advances in our understanding of tissue-specific T cell trafficking and how regulation of T cell trafficking by the chemokine system contributes to allergic inflammation in mouse models and in human allergic diseases of the skin, lung and gut. Inflammation- and tissue-specific T lymphocyte trafficking pathways are currently being targeted as new treatments for non-allergic inflammatory diseases and may yield effective new therapeutics for allergic diseases.